U.S. patent application number 12/309641 was filed with the patent office on 2010-05-13 for photo-curing of thermoplastic coatings.
Invention is credited to Niels Jorgen Madsen, Bo Rud Nielsen, Egon Triel.
Application Number | 20100119833 12/309641 |
Document ID | / |
Family ID | 38858929 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100119833 |
Kind Code |
A1 |
Madsen; Niels Jorgen ; et
al. |
May 13, 2010 |
PHOTO-CURING OF THERMOPLASTIC COATINGS
Abstract
The present invention relates to a method for the preparation of
a medical device element by means of extrusion or injection
moulding and to medical devices comprising such extruded or
injection moulded medical device elements. The medical device
elements (e.g. tubes, wires, lines, stents, catheters, guides,
endodontic instruments, needles, trocars for e.g. laparoscopic
surgery, laparoscopic accessories, surgical instruments, guide
wires) are characterized by a prefabricated shaped article or a
thermoplastic substrate polymer having thereon a layer of a
covalently cross-linked coating composition of a thermoplastic
matrix polymer and a hydrophilic polymer. The method involves a
coating composition comprising a thermoplastic matrix polymer, a
hydrophilic polymer, and one or more photo-initiator(s), e.g.
covalently linked to molecules of the thermoplastic matrix polymer
and/or to molecules of the hydrophilic polymer. The coating
composition is irradiated with UV or visible light so as to
covalently cross-link said coating composition.
Inventors: |
Madsen; Niels Jorgen;
(Allerod, DK) ; Triel; Egon; (Golden Valley,
MN) ; Nielsen; Bo Rud; (Allerod, DK) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W., SUITE 600
WASHINGTON
DC
20004
US
|
Family ID: |
38858929 |
Appl. No.: |
12/309641 |
Filed: |
July 25, 2007 |
PCT Filed: |
July 25, 2007 |
PCT NO: |
PCT/EP2007/057666 |
371 Date: |
October 1, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60832945 |
Jul 25, 2006 |
|
|
|
Current U.S.
Class: |
428/413 ;
427/2.1; 428/423.1 |
Current CPC
Class: |
B29C 45/0053 20130101;
B29K 2077/00 20130101; C08G 2210/00 20130101; Y10T 428/31511
20150401; B29C 48/151 20190201; B29C 2035/0827 20130101; A61L 31/10
20130101; B29C 71/04 20130101; C08G 65/331 20130101; B29K 2023/06
20130101; B29L 2031/753 20130101; B29C 2045/0075 20130101; B05D
2201/00 20130101; B29K 2075/00 20130101; B29L 2031/7542 20130101;
B29C 45/1679 20130101; B05D 3/067 20130101; C08G 18/83 20130101;
C08G 18/4833 20130101; A61L 27/34 20130101; Y10T 428/31786
20150401; B29K 2995/0092 20130101; B29C 48/09 20190201; B29K
2023/086 20130101; B29C 45/14 20130101; B29K 2023/083 20130101;
A61L 29/085 20130101; B05D 5/08 20130101; Y10T 428/31551 20150401;
A61L 31/14 20130101; C08G 65/3324 20130101 |
Class at
Publication: |
428/413 ;
427/2.1; 428/423.1 |
International
Class: |
A61L 31/10 20060101
A61L031/10; B05D 3/00 20060101 B05D003/00; B32B 27/38 20060101
B32B027/38; B32B 27/40 20060101 B32B027/40; B32B 27/18 20060101
B32B027/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2006 |
DK |
PA 2006 01013 |
Jul 25, 2006 |
DK |
PCT/DK2006/000715 |
Claims
1-23. (canceled)
24. A method for the preparation of a medical device element, said
method comprising the steps of: (i) providing a prefabricated
shaped article and/or a thermoplastic substrate polymer; (ii)
providing a coating composition comprising a thermoplastic matrix
polymer, a hydrophilic polymer, and one or more photo-initiator(s);
(iii) extruding, injection moulding or powder coating the coating
composition of step (ii) on the prefabricated shaped article and/or
the thermoplastic substrate polymer of step (i) so as to provide
the medical device element of said prefabricated shaped article
and/or said substrate polymer having thereon a layer of said
coating composition, wherein, when both of said prefabricated
shaped article and said substrate polymer are present, said
prefabricated shaped article has thereon a layer of said substrate
polymer; (iv) irradiating the coating composition with UV or
visible light so as to covalently cross-link said coating
composition.
25. The method according to claim 24, wherein the one or more
photo-initiator(s) is at least two different photo-initiators.
26. The method according to claim 24, wherein one or more
photo-initiator moieties are covalently linked to a polymer.
27. The method according to claim 24, wherein said one or more
photo-initiators are covalently linked to molecules of the
thermoplastic matrix polymer and/or to molecules of the hydrophilic
polymer.
28. The method according to claim 26, wherein the one or more
photo-initiator moieties are covalently linked to a polymer
selected from the group consisting of polyurethanes, polyethylene
glycols, poly(lactic acid)s, collagen, nylons, vinyl polymers, and
polysaccharides.
29. The method according to claim 24, wherein a plurality of
photo-initiator moieties are covalently linked to a scaffold.
30. The method according to claim 24, wherein the coating
composition does not comprise (meth)acrylic monomers.
31. The method according to claim 24, wherein the thermoplastic
matrix polymer is selected from the group consisting of hydrophilic
polyurethane polymers and amphiphilic block-copolymers.
32. The method according to claim 24, wherein the hydrophilic
polymer is a poly(ethylene oxide).
33. The method according to claim 24, wherein a prefabricated
shaped article is provided in step (i), and wherein step (iii)
involves extruding, injection moulding or powder coating the
coating composition of step (ii) on the prefabricated shaped
article of step (i) so as to provide the medical device element of
said prefabricated shaped article having thereon a layer of said
coating composition.
34. The method according to claim 24, wherein a thermoplastic
substrate polymer is provided in step (i), and wherein step (iii)
involves extruding or injection moulding the coating composition of
step (ii) together with the thermoplastic substrate polymer of step
(i) so as to provide the medical device element of said
thermoplastic substrate polymer having thereon a layer of said
coating composition.
35. The method according to claim 24, wherein a prefabricated
shaped article and a thermoplastic substrate polymer are provided
in step (i), and wherein step (iii) involves extruding, injection
moulding or powder coating the coating composition of step (ii) on
the prefabricated shaped article together with the thermoplastic
substrate polymer of step (i) so as to provide the medical device
element of said prefabricated shaped article and said thermoplastic
substrate polymer, said prefabricated shaped article having thereon
a layer of said thermoplastic substrate polymer and said
thermoplastic substrate polymer having thereon a layer of said
coating composition.
36. A medical device comprising a medical device element of a
thermoplastic substrate polymer having thereon a layer of a
covalently cross-linked coating composition of (a) a thermoplastic
matrix polymer and (b) a hydrophilic polymer; wherein said coating
composition is (co)extruded or injection moulded with said
thermoplastic substrate polymer; and wherein the covalent
cross-linking of the coating composition is the result of the
presence of one or more photo-initiators in the coating composition
and the exposure of the coating composition to UV or visible
light.
37. A medical device comprising a medical device element of a
prefabricated shaped article having thereon a layer of a covalently
cross-linked coating composition of (a) a thermoplastic matrix
polymer and (b) a hydrophilic polymer; wherein said coating
composition is extruded or injection moulded with said
prefabricated shaped article; and wherein the covalent
cross-linking of the coating composition is the result of the
presence of one or more photo-initiators in the coating composition
and the exposure of the coating composition to UV or visible
light.
38. A medical device comprising a medical device element of a
prefabricated shaped article having thereon a layer of a
thermoplastic substrate polymer, where said thermoplastic substrate
polymer has thereon a layer of a covalently cross-linked coating
composition of (a) a thermoplastic matrix polymer and (b) a
hydrophilic polymer; wherein said coating composition is
(co)extruded or injection moulded with said prefabricated shaped
article and said thermoplastic substrate polymer; and wherein the
covalent cross-linking of the coating composition is the result of
the presence of one or more photo-initiators in the coating
composition and the exposure of the coating composition to UV or
visible light.
39. The medical device according to claim 36, wherein one or more
photo-initiator moieties are covalently linked to a polymer.
40. The medical device according to claim 37, wherein one or more
photo-initiator moieties are covalently linked to a polymer.
41. The medical device according to claim 38, wherein one or more
photo-initiator moieties are covalently linked to a polymer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for the
preparation of a medical device element by means of extrusion,
injection moulding or powder coating. The invention further relates
to medical devices comprising such extruded, injection moulded or
powder coated medical device elements. The medical device elements
are characterized by a prefabricated shaped article or a
thermoplastic substrate polymer having thereon a layer of a
covalently cross-linked coating composition of a thermoplastic
matrix polymer and a hydrophilic polymer.
BACKGROUND OF THE INVENTION
[0002] Many medical devices require a lubricated surface. In the
medical field, simple devices such as, for example, catheters,
guide wires, etc., must be inserted into a body cavity or through
the skin and at a later time be withdrawn. Patient treatment often
includes catheterization procedures or nutrition delivery systems,
most of which involve invasive techniques. In all such cases,
effective lubrication which is stable throughout both the insertion
and withdrawal stages of the procedure contributes greatly to
patient comfort.
[0003] U.S. Pat. No. 5,084,315 discloses a method for preparing a
shaped article, e.g. by co-extrusion, utilizing a composition
including PEO and a polyurethane, which is not covalently
cross-linked. The surface of the article is said to be lubricious
when contacted with water.
[0004] U.S. Pat. No. 5,061,424 discloses a method for preparing a
shaped article, e.g. by co-extrusion, utilizing a composition
including PVP and a polyurethane, which is not covalently
cross-linked. The surface of the article is said to be lubricious
when contacted with water.
[0005] U.S. Pat. No. 6,447,835 discloses a method of preparing a
coated hollow polymeric tubular member for a medical device by
co-extruding the tube together with a coating. The coating may
comprise acrylic monomers which may be reacted to form a
cross-linked acrylic polymer network after extrusion.
SUMMARY OF THE INVENTION
[0006] Although the shaped articles of U.S. Pat. No. 5,084,315 and
U.S. Pat. No. 5,061,424 may have certain desirable and--for some
applications--satisfactory properties with respect to reduced
friction, the present inventors have found (see Reference Examples
1-3) that it was not possible to combine the exceptionally low
friction required for certain medical devices, such as catheters
and guide wires, with a sufficient cohesion of the coating and a
sufficient adhesion of the coating to a substrate. Hence, the
present inventors found it necessary to develop methods for the
preparation of medical devices which provide advantages with
respect to simplicity, exceptionally low friction, excellent
cohesion and excellent adhesion.
[0007] Hence, the present invention provides a solution to the
above-mentioned problems by providing a method for the preparation
of medical devices, cf. the method defined in claim 1, which
provides advantages with respect to simplicity, exceptionally low
friction, excellent cohesion and excellent adhesion, and novel
medical devices, cf. claims 12, 13 and 14.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 illustrates a medical device (e.g. a tube of
catheter) of a prefabricated tube, a layer of a thermoplastic
substrate polymer, and a covalently cross-linked coating
composition (see Example 6).
[0009] FIG. 2 shows delamination from the tube after swelling due
to insufficient photo-curing (see Example 6).
[0010] FIG. 3 shows swelled layers bonded to the tube due to proper
photo-curing (see Example 6).
[0011] FIG. 4 shows non-cross-linked disintegration of a PVP
coating composition (see Reference Example 2). a) 12.5.times. zoom;
b) 40.times. zoom.
[0012] FIG. 5 shows the adhesion properties of different blends
after hot-press lamination onto Estane 58212. .box-solid.-symbols
represent blends that disintegrated when they were swelled in
water: The water absorption was high but the gel strength was too
low. The -symbols represent complete delamination, and separation
of the layer from the substrate occurs. The -symbols indicate good
adhesion to the substrate with no or very few water blisters
between the layers. See Reference Example 3 for details and an
explanation of areas I and II.
[0013] FIG. 6 shows the adhesion of extruded layers of
compounds/compositions A, B and C, respectively, on a Estane 58212
polyurethane tube as a function of photo-curing time, as evaluated
on a subjective scale from 1 to 4 (see Example 6 for details).
[0014] FIG. 7 shows the progress of the reaction between Gantrez AN
119 BF, MPEG 350 and Irgacure 2959 at 100.degree. C., as measured
by FT-IR (see Example 7 for details).
[0015] FIG. 8 shows the instantaneous reaction between
3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA) and
the diamine Jeffamine D-230 (see Example 12 for details).
DETAILED DESCRIPTION OF THE INVENTION
The Method of the Invention
[0016] As mentioned above, the present invention relates to a
method for the preparation of a medical device element, said method
comprising the steps of:
(i) providing a prefabricated shaped article and/or a thermoplastic
substrate polymer; (ii) providing a coating composition comprising
a thermoplastic matrix polymer, a hydrophilic polymer, and one or
more photo-initiator(s); (iii) extruding, injection moulding or
powder coating the coating composition of step (ii) on the
prefabricated shaped article and/or the thermoplastic substrate
polymer of step (i) so as to provide the medical device element of
said prefabricated shaped article and/or said substrate polymer
having thereon a layer of said coating composition, wherein, when
both of said prefabricated shaped article and said substrate
polymer are present, said prefabricated shaped article has thereon
a layer of said substrate polymer; (iv) irradiating the coating
composition with UV or visible light (wavelength in the range of
100-750 nm) so as to covalently cross-link said coating
composition.
[0017] The invention is based on the finding that cross-linking of
the coating composition subsequent to extrusion, injection moulding
or powder coating by means of one or more photo-initiator(s) and UV
or visible light provides medical device elements which have: good
adhesion of the coating composition including the hydrophilic
polymer to the prefabricated shaped article or the substrate
polymer; good cohesion of the coating composition; and good water
retention of the hydrophilic polymer in the wet state and thereby
excellent properties with respect to low friction for an extended
period of time.
[0018] The good properties with respect to good water retention of
the hydrophilic polymer and excellent properties with respect to
low friction for an extended period of time is somewhat
contradictory to the fact the flexibility of the polymer chains
will be restricted by means of the cross-linking of the polymer and
anchoring to the substrate polymer or prefabricated shaped
article.
[0019] In one important embodiment of the invention, the one or
more photo-initiator(s) are covalently linked to a polymer or a
scaffold, e.g. to molecules of the thermoplastic matrix polymer
and/or to molecules of the hydrophilic polymer.
Medical Device
[0020] The term "medical device" should be interpreted in a fairly
broad sense. Suitable examples of medical devices (including
instruments) are catheters (such as urinary catheters), endoscopes,
laryngoscopes, tubes for feeding, tubes for drainage, endotracheal
tubes, guide wires, sutures, cannulas, needles, thermometers,
condoms, urisheaths, barrier coatings e.g. for gloves, stents and
other implants, contact lenses, extra corporeal blood conduits,
membranes e.g. for dialysis, blood filters, devices for circulatory
assistance, condoms, dressings for wound care, and ostomy bags.
Most relevant are catheters, endoscopes, laryngoscopes, tubes for
feeding, tubes for drainage, guide wires, sutures, and stents and
other implants. Particularly interesting medical devices within the
context of the present invention are catheters, such as urinary
catheters.
[0021] It is also envisaged that the method of the invention is
equally useful for the preparation of devices with low-friction
surfaces for non-medical purposes, e.g. packaging for foodstuff,
razor blades, fishermen's net, conduits for wiring, water pipes
having a coating inside, sports articles, cosmetic additives, mould
release agents, and fishing lines and nets.
[0022] Some medical devices may be constructed of one or more
medical device elements which, when being assembled or rearranged,
represent the ready-to-use medical device. Reference to a "medical
device element" and "catheter element" means the medical device or
catheter as such (i.e. one piece medical device or catheter) or a
part of a "ready-to-use" medical device or catheter.
[0023] Medical device elements are in the present context formed
from a prefabricated shaped article and/or a thermoplastic
substrate polymer and a coating composition. Upon (co)extrusion or
injection moulding of the prefabricated shaped article and/or the
thermoplastic substrate polymer and the simultaneous or subsequent
application of the coating composition by co-extrusion, injection
moulding or powder coating, at least a part of the surface of the
prefabricated shaped article or the substrate polymer becomes
coated with the coating composition as will be explained in more
detail in the following. In some embodiments, the coating
composition (i.e. a hydrophilic coating) is covering the full
(outer) surface of the prefabricated shaped article/substrate
polymer, and in some other embodiments, only to a part of the
surface thereof. In the most relevant embodiments, the coating
composition covers at least a part of the surface (preferably the
whole surface) of the medical device that--upon proper use--comes
into direct contact with body parts for which the medical device is
intended.
Prefabricated Shaped Articles
[0024] In the embodiments where a prefabricated shaped article is
involved, the method is designed to provide a coating onto such as
shaped article. A wide variety of shaped articles are envisaged
(e.g. tubes, wires, lines, stents, catheters, guides, endodontic
and orthodontic instruments, needles, trocars for e.g. laparoscopic
surgery, laparoscopic accessories, surgical instruments, guide
wires), just as a number of different materials may constitute such
shaped articles, such as metals and alloys, e.g. stainless steel
cores or typical guide-wire alloys, e.g. Ti alloys such as Nitinol
and pseudoplastic Beta Ti--Mo--V--Nb--Al alloys. Glasses and
ceramics just as thermoplastic polymers are also envisaged.
Suitable materials also include: Thermoplastic polymers such as
hydrophilic polyurethanes, hydrophobic polyurethanes, polyether
block amides (e.g. Pebax.TM.), PVC, polyamides, polyesters,
biodegradable polyesters, polyacrylates, PS, silicones, latex
rubber; block copolymers with the different structures diblock
(A-B), multiblock (A-B).sub.n or triblock (A-B-A) such as SEBS,
SIS, SEPS, SBS, SEEPS (the block copolymers may be grafted with
maleic anhydride onto the rubber block, typically the mid-block for
triblock copolymers); thermoplastic polymers such as LDPE, LLDPE,
VLDPE, PP, PE, and copolymers of ethylene and propylene,
metallocene polymerized polyolefins, PS, EMA, EEA, EnBA, PE g-MAH,
EVA, EVOH and vinyl acetate copolymer grafted with maleic anhydride
(EVA g-MAH), or combinations thereof e.g. Orevac.RTM.
ethylene-vinyl acetate-maleic anhydride terpolymers; and the
functional polyolefins range, such as Lotader.RTM. ethylene-acrylic
ester terpolymers with either MAH or GMA; and the maleic anhydride
grafted polymers of PE, PP, PS, etc. The abbreviations are
explained in the Table in Examples.
Thermoplastic Substrate Polymer
[0025] In the embodiments where a thermoplastic substrate polymer
is involved, the method is designed to provide a coating onto this
substrate. The thermoplastic substrate polymer is selected so as to
provide the physical shape of the medical device element or so as
to provide a suitable interface between the coating composition and
the prefabricated shaped article. Hence, the substrate polymer is
typically selected from polyurethanes, polyether block amides (e.g.
Pebax.TM.), PVC, polyamides, polyesters, polyacrylates, PS,
silicones, latex rubber, SEBS, SIS, SEPS, SEEPS, EVA, PE, and
copolymers of ethylene and propylene; thermoplastic polymers such
as hydrophilic polyurethanes, hydrophobic polyurethanes, polyether
block amides (e.g. Pebax.TM.), PVC, polyamides, polyesters,
polyacrylates, PS, silicones, latex rubber; block copolymers with
the different structures diblock (A-B), multiblock (A-B).sub.n or
triblock (A-B-A) such as SEBS, SIS, SEPS, SBS, SEEPS; the block
copolymers may be grafted with MAH onto the rubber block, typically
the mid-block for triblock copolymers; thermoplastic polymers such
as LDPE, LLDPE, VLDPE, PP, PE, and copolymers of ethylene and
propylene, metallocene polymerized polyolefins, PS, EMA, EEA, EnBA,
PE g-MAH, EVA, EVOH and EVA g-MAH, or combinations thereof, e.g.
Orevac.RTM. ethylene-vinyl acetate-maleic anhydride terpolymers;
the functional polyolefins range, such as Lotader.RTM.
ethylene-acrylic ester terpolymers with either MAH or GMA; maleic
anhydride grafted polymers of PE, PP, PS, etc.; and the EPOCROS
K-series of reactive acrylate-oxazoline copolymers or the
RPS/RAS-series of styrene-oxazoline copolymers, or
styrene-acrylonitrile-oxazoline copolymers.
[0026] Currently very relevant materials for use as the
thermoplastic substrate polymer are polyurethanes and PVC, in
particular polyurethanes, e.g. hydrophobic polyurethanes.
Coating Composition
[0027] The principal constituents of the coating composition are
the thermoplastic matrix polymer, the hydrophilic polymer and the
one or more photo-initiators. These constituents will be discussed
in detail further below.
[0028] The matrix polymer and the hydrophilic polymer are
preferably used in a relative weight ratio from 95:5 to 5:95, in
particular from 80:20 to 20:80, or from 75:25 to 30:70.
[0029] Depending on the intended use, additives may be incorporated
into the coating composition in order to achieve particular
properties. For example one or more additives such as flow aids,
flatting agents, heat stabilizers, surface cure modifiers,
antibacterial agents, and osmolality increasing compounds may be
added to the coating composition. Such additives and their use to
modify polymer properties are conventional and well known to those
skilled in the art. Such other components may be used in an amount
of up to 10% by weight, e.g. up to 5% by weight, of the coating
composition.
[0030] Antibacterial agent may be a silver salt, e.g. silver
sulphadiazine; an acceptable iodine source such as povidone iodine
(also called PVP iodine); chlorhexidine salts such as the
gluconate, acetate, hydrochloride or the like; or salts or
quaternary antibacterial agents such as benzalkonium chloride or
other antiseptics or antibiotics. Antibacterial agents reduce the
risk of infection, e.g. when urodynamic examinations are
performed.
[0031] For medical devices or instruments suitable for introduction
into human cavities, it may be advantageous to include an
osmolality increasing compound, e.g. a water-soluble non-ionic
compound such as glucose, sorbitol, glycerin, or urea; or ionic
compounds such as halides, nitrates, acetates, citrates or
benzoates of alkali metals or alkaline earth metals or silver; or
carboxylic acids such as acetic acid, etc.
[0032] For some hydrophilic polymers, e.g. PVP, it may be necessary
or desirable to include a plasticizer in order to facilitate the
extrusion, injection moulding or powder coating. In such instances,
a plasticizer may be included in an amount of up to 60% by weight
of the coating composition.
[0033] In one embodiment, the coating composition preferably
comprises:
20-80% by weight of the matrix polymer, 20-80% by weight of the
hydrophilic polymer, 0-60% by weight of one or more plasticizers
0.0001-5.0% by weight of the one of more photo-initiators, and 0-5%
by weight of other components.
[0034] In a more interesting embodiment, the coating composition
comprises:
20-80% by weight of the matrix polymer, 20-80% by weight of the
hydrophilic polymer, 0-5% by weight of one or more plasticizers,
0.0001-5.0% by weight of the one of more photo-initiators, and 0-5%
by weight of other components.
[0035] In a particular embodiment, the coating composition
comprises:
30-75% by weight of the matrix polymer being a hydrophilic
polyurethane, 25-70% by weight of the hydrophilic polymer being a
PEO, 0.001-2.5% by weight of the one of more photo-initiators, and
0-5% by weight of other components.
[0036] In another particular embodiment, the coating composition
comprises:
30-75% by weight of the matrix polymer being a hydrophilic
polyurethane, 25-50% by weight of the hydrophilic polymer being a
PEO, 0-60% by weight of one or more plasticizers 0.001-2.5% by
weight of the one of more photo-initiators, and 0-5% by weight of
other components.
Thermoplastic Matrix Polymer
[0037] The main requirement to the matrix polymer is the
thermoplasticity. Moreover, the thermoplastic polymers should
preferably be limpid (i.e. clear, non-opaque) at the temperature of
photo-curing. The thermoplastic matrix polymers as such should
preferably have low absorbance in the UV-C part of the
electromagnetic spectrum (i.e. wavelengths below 280 nm), which is
where most photo-initiators have their maximum absorbance.
Preferably, the absorbance of the thermoplastic polymers in UV-B
(280-315 nm) and UV-A (315-380 nm) should also be low, since some
photo-initiators absorb in that region.
[0038] Examples of suitable thermoplastic matrix polymers are those
of the type defined for the thermoplastic substrate polymer (see
the section "Thermoplastic Substrate polymer"). Suitable
thermoplastic matrix polymers include MAH-modified PE (e.g.
Orevac.RTM.) and MAH-modified PP (e.g. Fusabond.RTM.).
Polyurethanes, in particular hydrophilic polyurethanes (including
polyetherurethanes), are particularly useful. Furthermore,
amphiphilic block copolymers can also be particularly useful for
use as the thermoplastic matrix polymer.
[0039] A group of preferred thermoplastic matrix polymers are the
hydrophilic polyurethanes Tecogel 500 and Tecogel 2000 from Noveon,
or Hydromed TP from Cardiotech. The thermoplastic polymer should be
able to swell at least 80% in water, so the medical device does not
dry out during normal use. The main function of the thermoplastic
matrix polymer(s) is to make the entire coating composition
thermoplastic and hence suitable for (co)extrusion or injection
moulding, even though the additionally added hydrophilic polymer(s)
and photo-initiator(s) may not be thermoplastic per se.
[0040] Thermoplastic polyurethanes prepared from polyisocyanates,
high molecular weight polyetherglycols, and low molecular weight
diols and diamines as chain extenders are conventionally referred
to as polyetherurethanes, and this term will be used herein for
polyurethanes having a polyether backbone.
[0041] Polyetherurethane compositions develop micro-domains
conventionally termed "hard segment domains" and "soft segment
domains" and are often referred to as segmented polyurethanes. They
are (AB).sub.n type block copolymers, A being the hard segment and
B the soft segment. The hard segment domains form by localization
of the portions of the copolymer molecules which include the
isocyanate and extender components whereas the soft segment domains
form from the polyether glycol portions of the copolymer chains.
The phase separated micro-domain structure forms if the hard
segments of polyetherurethane chain have a certain size. A long
hard segment promotes the phase separated micro-domain structure.
Conversely, non-extended formulations (those lacking an extender)
have very short hard segments and minimum phase separated
micro-domain structure. The hard segment is crystalline and
provides physical cross-linking and reinforcement. The polyether
glycol soft segment is mostly in a rubbery state and provides
elasticity. Therefore, polyetherurethanes are thermoplastic
elastomeric materials. A wide range of physical properties can be
obtained by altering the relative ratios of the hard and soft
segments. The elasticity, toughness and other desirable properties
of polyetherurethanes are the result of their phase separated
microdomain structure.
[0042] Hydrophilic polyetherurethanes (HPEUs) suitable for use as
the thermoplastic matrix polymer of the coating composition include
three essential components, a diisocyanate, a polyether glycol and
a chain extender. Suitable diisocyanates are aromatic diisocyanates
such as MDI, alicyclic diisocyanates such as isophorone
diisocyanate and methylene-4,4'-dicyclohexyldiisocyanate, and
aliphatic diisocyanates, as, for example, hexamethylene
diisocyanate. The most preferred diisocyanate is MDI.
[0043] The polyether glycol component may be PEG, alone or mixed
with poly(1,2-propylene oxide) glycol or poly(tetramethylene oxide)
glycol. The preferred polyol is PEG having a molecular weight of
from about 600 to 8,000, or a mixture containing 50% or more by
weight thereof. The most preferred polyether glycol is a PEG having
an average molecular weight of 1000 to 1450. In order to reduce the
crystallinity of the PEG domains, polyether polyols based on either
random or block copolymers of ethylene oxide/1,2-propylene oxide or
the Tegomer.RTM. D 3403, a polyether diol can be chosen.
[0044] The chain extender may be water and/or a low molecular
weight branched or unbranched diol, diamine or aminoalcohol of up
to 10 carbon atoms or mixtures thereof. Representative nonlimiting
examples of chain extenders are BDO; ethylene glycol; diethylene
glycol; triethylene glycol; 1,2-propanediol (propylene glycol);
1,3-propanediol; 1,6-hexanediol; 1,4-bis(hydroxymethyl)cyclohexane;
hydroquinone dihydroxyethyl ether; ethanolamine; ethylenediamine;
and hexamethylenediamine. Preferred chain extenders are
1,6-hexanediol; ethylenediamine; hexamethylenediamine and, most
preferably, BDO.
[0045] The percentages of the components may be such that the hard
and soft segments of the composition may be from 25% to 60% and
from 40% to 75%, respectively, preferably from 30% to 50% and from
50% to 70%, respectively, of the total weight of the formulation.
From these percentages and ratios, suitable proportions of the
components may readily be calculated. Representative elastomeric
segmented HPEU matrix polymers and their preparation are known from
U.S. Pat. No. 5,061,424 (Example I). The HPEU matrix polymer may be
prepared by solution or bulk synthesis methods. Alternatively, the
HPEU may be prepared by conventional emulsion polymerization in
water, to give an HPEU latex.
[0046] Amphiphilic block polymers consist of a non-polar polymeric
chain coupled to a polar polymeric chain. More in particular the
polar chain end of the polymer must be water-soluble or water
swellable to at least a content of 300% water if taken alone. The
non-polar chain preferably does not take up more than 10% of water
when submersed in water.
[0047] The polymers are made from two or more monomers each of
which are grouped in blocks. The polymers may for instance be a
diblock from monomers A and B having a structure AAAAAABBBBBB or a
triblock having a linear structure like AAAABBBBAAAA or
alternatively in the form of a multiblock or a three- or multiarm
star-shaped copolymer structure.
[0048] The incorporation of amphiphilic block copolymers having
long hydrophobic end blocks as diblock, triblock, multiblock or
star-shaped block copolymers improves the cohesion dramatically
compared to the incorporation of conventionally used associative
thickeners. Due to the physical cross-linking the amphiphilic block
copolymers maintain the high cohesion in the coating during
hydration and water absorption.
[0049] The hydrophobic block of the block copolymer will constitute
separate physically cross-linked domains being incompatible with
the continuous hydrophilic phase.
[0050] The hydrophobic part of the amphiphilic block copolymer may
suitably be polystyrene; polyethylene; a poly(.alpha.-olefin) such
as polypropylene, poly(1-butene) or polyisobutylene; a
poly(meth)acrylate, a poly(vinyl ether), a poly(vinyl acetate), a
polysiloxane, a hydrophobic polyester or similar polymer moieties
conventionally used in pressure sensitive adhesive
formulations.
[0051] The hydrophilic part of the amphiphilic block copolymer (B
block) may suitably be any type of polymer that will be able to
absorb significant amounts of water. If taken alone, the
hydrophilic block is water-soluble or at least highly water
absorbing. Suitable polymers for use in amphiphilic polymers for
use in accordance with the present invention are PEG (poly(ethylene
glycol)), PVP (poly(vinyl pyrrolidone)), poly(acrylic acid), salts
of poly(acrylic acid), salts of polymers composed of other mono-
and diacids such as maleic acid, fumaric acid, crotonic acid,
tiglic acid, and itaconic acid; poly(vinyl alcohol), hydrophilic
polyurethanes, carbohydrates or gelatins. The hydrophilic block
preferably has a minimum molecular weight of about 500 g/mol in
order to be able to form separate hydrophilic domains in the
coating composition. Preferably the molecular weight is higher than
1000 g/mol in case of end-blocks and higher than 5000 g/mol in case
of mid-blocks.
[0052] For use in accordance with the present invention it is
suitable that the amphiphilic polymer contains polystyrene blocks.
In a suitable alternative embodiment of the invention the
amphiphilic polymer contains hydrophobic polyacrylate blocks.
[0053] In a further embodiment of the invention the amphiphilic
polymer contains hydrophobic blocks from the polymer of a vinylic,
unsaturated aliphatic hydrocarbon comprising from 1 to 6 carbon
atoms, the 4 carbon vinylic, unsaturated hydrocarbons polybutylene
and polyisobutylene being most preferred.
[0054] In the preferred amphiphilic block copolymers to be used in
accordance with the present invention the hydrophobic A domain is a
thermoplastic homopolymer with a number average molecular weight of
about 1000 to about 50,000 g/mol of an aromatic monovinyl compound,
and the hydrophilic B domain has a number average molecular weight
of about 1000 to about 500,000 g/mol.
[0055] Hydrophobic monomers for use in the A block are aromatic
monovinyl compounds, which typically contain from about 8 to about
18 carbon atoms, such as styrene, .alpha.-methylstyrene,
vinyltoluene, vinylpyridine, ethylstyrene, tert-butylstyrene,
iso-propylstyrene, dimethylstyrene, and other alkylated styrenes.
The A block could also suitably consist of acrylic esters or vinyl
esters.
[0056] Alternatively, the A domain may comprise ethylenically
unsaturated monomers chosen from butadiene, chloroprene,
(meth)acrylic esters, vinyl halides such as vinyl chloride, vinyl
nitriles, and vinyl esters such as vinyl acetate, vinyl versatate
and vinyl propionate.
[0057] "(Meth)acrylic esters" is used in the present context to
designate esters of acrylic acid or methacrylic acid with
optionally halogenated, e.g. chlorinated or fluorinated,
C.sub.1-C.sub.12 straight or branched alcohols, preferably
C.sub.1-C.sub.8 alcohols. Examples of such esters are methyl
acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate,
isobutyl acrylate, 2-ethylhexyl acrylate, tert-butyl acrylate,
methyl methacrylate, ethyl methacrylate, n-butyl methacrylate and
isobutyl methacrylate.
[0058] Suitable vinyl nitriles are those having from 3 to 12 carbon
atoms, such as, in particular, acrylonitrile and
methacrylonitrile.
[0059] In another embodiment of the present invention styrene is
completely or partly replaced by derivatives of styrene, such as
.alpha.-methylstyrene or vinyltoluene.
[0060] The preferred hydrophilic B block for a diblock or triblock
copolymer will be described in more detail below.
[0061] Hydrophilic monomers for use in the B block are e.g.
ethylenically unsaturated monocarboxylic and dicarboxylic acids,
such as acrylic acid, methacrylic acid, itaconic acid, maleic acid
and fumaric acid; and monoalkyl esters of dicarboxylic acids of the
type mentioned above with alkanols, preferably alkanols having from
1 to 4 carbon atoms, optionally with unalkylated or alkylated amino
groups; amides of unsaturated carboxylic acids, such as acrylamide,
methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, and
N-alkylacrylamides; ethylenic monomers containing a sulphonic acid
group and ammonium or alkali metal salts thereof, for example
S-vinylsulphonic acid, vinylbenzenesulphonic acid,
2-acrylamido-2-methylpropanesulphonic acid (AMPS) and 2-sulphoethyl
methacrylate; amides of vinylamine, especially N-vinylformamide or
N-vinylacetamide; and unsaturated ethylenic monomers containing a
secondary or tertiary amino group or a quaternary ammonium group,
or a heterocyclic group containing nitrogen, such as, for example,
vinylpyridines or vinylimidazole; aminoalkyl(meth)acrylates such as
dimethylaminoethyl(meth)acrylate and
di-tert-butylaminoethyl(meth)acrylate, N,N-dialkyl(meth)acrylamides
such as N,N-dimethyl(meth)acrylamide. It is also possible to use
zwitterionic monomers such as, for example,
N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulphopropyl)ammonium
betaine (SPE).
[0062] In the currently most preferred embodiments, the
thermoplastic matrix polymer is selected from the group consisting
of hydrophilic polyurethane polymers and amphiphilic
block-copolymers.
[0063] It should be understood that the expression "a thermoplastic
matrix polymer" and the like is intended to encompass a single
thermoplastic polymer as well as a mixture of two or more
thermoplastic polymers.
Hydrophilic Polymer
[0064] The main requirement to the hydrophilic polymer is to ensure
that the covalently cross-linked coating composition becomes very
slippery when it is swollen with hydrophilic liquids such as water
or glycerol. Hence, the main function of the hydrophilic polymer(s)
is to give the swollen coating low friction and high water
retention.
[0065] The hydrophilic polymer is preferably also limpid at the
temperature of photo-curing and has low absorbance in UV-C, UV-B
and UV-A, so that it does not block the UV or visible light
intended for the photo-initiator(s). The hydrophilic polymer may
suitably be selected from one or more of the following materials:
[0066] Poly(vinyl lactams) such as PVP; and copolymers of NVP and
DMAEMA, (meth)acrylic acid, (meth)acrylic esters including
2-sulfoethyl methacrylate, (meth)acrylic amides including
N,N-dimethylacrylamide and N-vinylacetamide, MAH, maleic esters,
P-vinylphosphonic acid, methyl vinyl ether, etc. [0067] Slightly
cross-linked PVP or PVP copolymers are preferred. [0068] Linear or,
preferably, cross-linked PEO with high molecular weight, and
copolymers of EO and PO. [0069] Superabsorbent homo- and copolymers
of water-soluble .alpha.,.beta.-ethylenically unsaturated
carboxylic acids and derivatives, such as acrylic acid, methacrylic
acid, fumaric acid, maleic acid, crotonic acid, tiglic acid, and
itaconic acid; and their esters and amides. [0070] Cellulosic
superabsorbent polymers, e.g. hydroxypropyl methylcellulose or CMC,
or starch-graft copolymers, such as starch-graft-polyacrylonitrile,
starch-graft-poly(acrylic acid) and the like. [0071] PVOH, homo-
and copolymers of sulphonic acid group containing monomers, such as
S-vinylsulphonic acid, sodium sulfoethyl methacrylate,
2-acrylamido-2-methylpropane-sulphonic acid or the sodium salt
(AMPS) and the like. [0072] Alt-copoly(methyl vinyl ether/maleic
anhydride) (tradename Gantrez at ISP Corporation) which has been
either hydrolyzed in basic solution (to form a polyanion),
hydroxy-modified (to form an ester acid) or amino-modified (to form
an amide acid). [0073] Poly(vinyl methyl ether), polyethyleneimine,
poly(2-ethyl-2-oxazoline),
copoly(2-ethyl-2-oxazoline/2-phenyl-2-oxazoline) as random or block
copolymers, or the hydrophilic EPOCROS WS-series, such as WS-500,
WS-700.
[0074] The preferred hydrophilic polymers are those selected from
the group consisting of poly(vinyl lactams) [e.g. PVP], PEO,
polyoxazolines, PVOH, and polyacrylates. The currently most
preferred hydrophilic polymer is PEO.
[0075] When PEO is used a hydrophilic polymer, it may be of any
suitable weight average molecular weight (M.sub.w), but preferably
in the range of 100,000 to 8,000,000, most preferably 200,000 to
4,000,000. Suitable PEOs may be purchased from Dow under the trade
name Polyox.RTM..
[0076] When PVP is used as a hydrophilic polymer, it may be of any
suitable weight average molecular weight (M.sub.w), but preferably
in the range of 10,000 to 3,500,000. Suitable PVPs may be purchased
from ISP Corp. under the tradename Plasdone.
[0077] It should be understood that the expression "a hydrophilic
polymer" and the like is intended to encompass a single hydrophilic
polymer as well as a mixture of two or more hydrophilic
polymers.
[0078] The choice of materials for the thermoplastic substrate
polymer and the thermoplastic matrix polymer depends on the
materials chosen for the prefabricated shaped article. Typically,
if the prefabricated shaped article is made of a polyurethane, a
hydrophilic polyurethane will be chosen as the thermoplastic
substrate polymer, and the coating composition will preferably
contain a hydrophilic polyurethane as the thermoplastic matrix
polymer.
[0079] If the prefabricated shaped article is made of a polyolefin,
polyolefins will typically be preferred as a thermoplastic
substrate polymer and often in combination with more polar polymers
or polymers with functional groups, which can introduce
compatibility with the final hydrophilic lubricious coating.
[0080] In order to improve and obtain a proper surface anchoring
between different layers on prefabricated shaped articles there
will be several strategies. In some cases di- or triblock
copolymers with one or more polyolefinic groups together with more
polar PS block(s) can give an optimal surface anchoring between
layers. Otherwise the substrate polymer can be modified during
reactive polymer blending where functional groups on the polymers
can be utilized to combine non-polar polymers with polar or
hydrophilic polymers.
[0081] Reactive polymer blending can also be used to obtain
covalent bonding between photo-initiators and non-polar, polar or
hydrophilic functional polymers in order to improve surface
anchoring during a photo-curing after a co-extrusion of the
coatings.
[0082] When the term "polymer" is used herein, e.g. connection with
the expressions "thermoplastic matrix polymer" and "hydrophilic
polymer", it typically implies that the weight average molecular
weight is more than 10 kDa. The molecular weight limit range
provided for "polymers" is hence complementary to the limit given
for "low molecular weight", i.e. up to 10 kDa".
Photo-Initiators
[0083] The presence of one or more photo-initiators in the coating
composition is mandatory. The one or more photo-initiators are
typically present in an amount of in the range of 0.001-10 w/w-%,
such as in the range of 0.01-5 w/w-%, in particular in the range of
0.1-4 w/w-%.
[0084] The main function of the photo-initiator(s) is to ensure
good cross-linking of the thermoplastic, hydrophilic coating to
itself and to the substrate, in order to obtain good cohesion and
adhesion to the substrate.
[0085] As will be understood from the following, the one or more
photo-initiators may be present in the coating composition (a) as
discrete molecules, (b) as photo-initiators covalently linked to a
polymer, or (c) as a plurality of photo-initiator moieties
covalently linked to a low molecular weight scaffold, or a
combination thereof. This will be discussed in more detail
below.
[0086] In one possible embodiment, which also will be described in
more details in the following, the one or more photo-initiators are
covalently linked to molecules of a polymer, e.g. the thermoplastic
matrix polymer and/or to molecules of the hydrophilic polymer
and/or a third polymer not being the thermoplastic matrix polymer
or the hydrophilic polymer.
[0087] In one variant hereof, the one or more photo-initiator
moieties are covalently linked to a polymer selected from the group
consisting of polyurethanes, polyethylene glycols, poly(lactic
acid)s, collagen, nylons (e.g. polycaprolactam, polylauryl lactam,
polyhexamethylene adipamide and polyhexamethylene dodecanediamide),
vinyl polymers (e.g. polyvinyl pyrrolidone and polyvinyl alcohol),
and polysaccharides (e.g. amylose, dextran, chitosan, hyaluronic
acid, amylopectin, hyaluronic acid and hemi-celluloses).
[0088] The one or more photo-initiators efficiently transform light
from the UV or visible light source to reactive radicals which can
abstract hydrogen atoms and other labile atoms from polymers and
hence effect covalent cross-linking. Optionally, amines, thiols and
other electron donors may be added. Radical photo-initiators can be
classified as either cleavable (Norrish type I reaction) or
non-cleavable (of which the Norrish type II reaction is a special
case, see e.g. A. Gilbert, J. Baggott: "Essentials of Molecular
Photochemistry", Blackwell, London, 1991).
[0089] Upon excitation cleavable photo-initiators spontaneously
break down to two radicals, at least one of which is reactive
enough to abstract a hydrogen atom from most substrates. Benzoin
ethers (including benzil dialkyl ketals), phenyl hydroxyalkyl
ketones and phenyl aminoalkyl ketones are important examples of
cleavable photo-initiators. Addition of electron donors is not
required but may enhance the overall efficiency of cleavable
photo-initiators according to a mechanism similar to that described
for the non-cleavable photo-initiators below.
[0090] Recently a new class of .beta.-keto ester based
photo-initiators has been introduced by M. L Gould, S.
Narayan-Sarathy, T. E. Hammond, and R. B. Fechter from Ashland
Specialty Chemical, USA (2005): "Novel Self-Initiating UV-Curable
Resins: Generation Three", Proceedings from RadTech Europe 05,
Barcelona, Spain, October 18-20 2005, vol. 1, p. 245-51, Vincentz.
After base-catalyzed Michael addition of the ester to
polyfunctional acrylates a network is formed with a number of
quaternary carbon atoms, each with two neighbouring carbonyl
groups. Upon UV or visible light excitation these photo-initiators
predominantly cleave by a Norrish type I mechanism and cross-link
further without any conventional photo-initiator present, and thick
layers may be cured. Such self-initiating systems are within the
scope of the present invention.
[0091] Excited non-cleavable photo-initiators do not break down to
radicals but abstract a hydrogen atom from an organic molecule or,
more efficiently, abstract an electron from an electron donor (such
as an amine or a thiol). The electron transfer produces a radical
anion on the photo-initiator and a radical cation on the electron
donor. This is followed by proton transfer from the radical cation
to the radical anion to produce two uncharged radicals; of these
the radical on the electron donor is sufficiently reactive to
abstract a hydrogen atom from most substrates. Benzophenones,
thioxanthones, xanthones, anthraquinones, fluorenones,
dibenzosuberones, benzils, and phenyl ketocoumarins are important
examples of non-cleavable photo-initiators. Most amines with a C--H
bond in .alpha.-position to the nitrogen atom and many thiols will
work as electron donors.
[0092] Another self-initiating system based on maleimides has also
been identified by C. K. Nguyen, W. Kuang, and C. A. Brady from
Albemarle Corporation and Brady Associates LLC, both USA (2003):
"Maleimide Reactive Oligomers", Proceedings from RadTech Europe 03,
Berlin, Germany, Nov. 3-5, 2003, vol. 1, p. 589-94, Vincentz.
Maleimides initiate radical polymerization mainly by acting as
non-cleavable photo-initiators and at the same time spontaneously
polymerize by radical addition across the maleimide double bond. In
addition the strong UV absorption of the maleimide disappears in
the polymer, i.e. maleimide is a photobleaching photo-initiator;
this could make it possible to cure thick layers. Such
maleimide-containing systems are within the scope of the present
invention.
[0093] The preferred cleavable photo-initiators are benzoin ethers
(including benzil dialkyl ketals) such as Irgacure 651 (Ciba);
phenyl hydroxyalkyl ketones such as Darocur 1173, Irgacure 127,
Irgacure 184, and Irgacure 2959 (all from Ciba), Esacure KIP 150
and Esacure One (both from Lamberti); phenyl aminoalkyl ketones
such as Irgacure 369 (Ciba), Irgacure 379 (Ciba), and Chivacure
3690 (from Double Bond Chemical); methylthiophenyl morpholinoalkyl
ketones such as Irgacure 907 (Ciba) and Chivacure 3482 (Double bond
Chemicals); and mono- or dibenzoylphosphinoxides such as Irgacure
819 and Darocur TPO (both from Ciba).
[0094] The preferred non-cleavable photo-initiators are
benzophenone; 4-benzoylbenzoic acid (=4-carboxybenzophenone) and
esters thereof; 2-benzoylbenzoic acid (=2-carboxybenzophenone) and
esters thereof; 4,4'-bis(dimethylamino)benzophenone (Michler's
ketone); 2,4,6-trimethylbenzophenone; BTDA; Omnipol BP (IGM
Resins), and other benzophenone derivatives; thioxanthones such as
Omnipol TX (IGM Resins); xanthones; anthraquinones; fluorenones;
dibenzosuberones; benzils and other .alpha.-diketo compounds such
as camphorquinone; and phenyl ketocoumarins. The preferred optional
electron donors are benzocaine (ethyl 4-aminobenzoate), PVP-DMAEMA,
tribenzylamine, triethanolamine, 2-(N,N-dimethylamino)ethanol, and
N,N-dimethylethylenediamine. The preferred acrylate-containing
photo-initiators are Omnilane XP-144 LS-B (light sensitive
trifunctional aliphatic urethane acrylate; from IGM/Bomar) and
acrylated benzophenones.
[0095] The currently most preferred photo-initiators are those
selected from the group Irgacure 2959, Irgacure 651, Esacure KIP
150, BTDA and derivatives thereof, 4-carboxybenzophenone and
derivatives thereof, and 2-carboxybenzophenone and derivatives
thereof.
[0096] In one embodiment, one or more identical photo-initiator
moieties are present in the coating composition as discrete
molecules, i.e. as molecules comprising only one photoactive
group.
[0097] In one interesting embodiment, the one or more
photo-initiator(s) include at least two different photo-initiators.
More particular, the one or more photo-initiator(s) comprises at
least one cleavable photo-initiator and at least one non-cleavable
photo-initiator (see Example 8).
[0098] A blend of several photo-initiators may exhibit synergistic
properties, as is e.g. described by J. P. Fouassier: "Excited-State
Reactivity in Radical Polymerisation Photo-initiators", Ch. 1, pp.
1-61, in "Radiation curing in Polymer Science and technology", Vol.
II ("Photo-initiating Systems"), ed. by J. P. Fouassier and J. F.
Rabek, Elsevier, London, 1993. Briefly, efficient energy transfer
or electron transfer takes place from one photo-initiator to the
other in the pairs
[4,4'-bis(dimethylamino)benzophenone+benzophenone],
[benzophenone+2,4,6-tri-methylbenzophenone],
[thioxanthone+methylthiophenyl morpholinoalkyl ketone]. However,
many other beneficial combinations may be envisaged.
[0099] Furthermore, it has recently been found that covalently
linked Irgacure 2959 and benzophenone in the molecule
4-(4-benzoylphenoxyethoxy)phenyl 2-hydroxy-2-propyl ketone gives
considerably higher initiation efficiency of radical polymerization
than a simple mixture of the two separate compounds, see S.
Kopeinig and R. Liska from Vienna University of Technology, Austria
(2005): "Further Covalently Bonded Photoinitiators", Proceedings
from RadTech Europe 05, Barcelona, Spain, October 18-20 2005, vol.
2, p. 375-81, Vincentz. This shows that different photo-initiators
may show significant synergistic effects when they are present in
the same oligomer or polymer. Such covalently linked
photo-initiators are within the scope of the present invention.
[0100] The preferred properties of the photo-initiator(s) are: (i)
good overlap between the lamp emission spectrum and the
photo-initiator absorption spectrum; (ii) small overlap or no
overlap between the photo-initiator absorption spectrum and the
intrinsic, combined absorption spectrum of the other components of
the coating (i.e. the thermoplastic matrix polymer (e.g. a
thermoplastic, hydrophilic polyurethane) and the hydrophilic
polymer (e.g. a hydrophilic polymer with lubricant properties));
and good compatibility of the photo-initiator(s) with the
thermoplastic matrix polymer (e.g. hydrophilic polyurethane) and
preferably also with the hydrophilic polymer of the coating.
[0101] In another embodiment, one or more photo-initiators are
present in the coating composition as photo-initiators moieties
covalently linked to a polymer, e.g. molecules of the thermoplastic
matrix polymer, molecules of the hydrophilic polymer, or molecules
of a suitable third polymer type. Such a polymer, or polymers, may
include one or more identical or different photo-initiator moieties
and may therefore represent--in full or in part--the one or more
photo-initiators.
[0102] The polymer part of the photo-reactive polymer is typically
a thermoplastic polymer. Hence, in a particular embodiment, the one
or more photo-initiator(s) comprises at least one thermoplastic
polymer having photo-reactive groups attached thereto.
[0103] As discussed above, it is advantageous to include
photoactive polymers or a plurality of photo-initiators covalently
linked to a low molecular weight scaffold in the coating
composition in order to ensure that the photo-initiation is
homogeneously distributed within the coating composition.
[0104] In the embodiments where the photo-initiator moieties are
covalently attached to molecules of the thermoplastic matrix
polymer and/or molecules of the hydrophilic polymer, and it should
be understood that only the photo-initiator moieties will
contribute to the weight percentage of the one or more
photo-initiators, whereas the thermoplastic matrix polymer and the
molecules of the hydrophilic polymer will contribute to the weight
percentage of thermoplastic matrix polymer and hydrophilic polymer,
respectively.
[0105] Photoactive polymers may be tailor-made to give optimal
compatibility with the thermoplastic matrix polymer and the
hydrophilic polymer of the coating composition, optimal
cross-linking geometry, and optimal thermoplasticity.
Photoinitiators Linked to a Polymer or Scaffold
[0106] A number of illustrative examples of the incorporation of
the one or more photo-initiator(s) will be provided in the
following so as to emphasis the diversity of means for
incorporating the one or more photo-initiators into the coating
composition in the form of photo-initiator moieties (illustrated by
means of Irgacure 2959 and other commercially available
photo-initiator molecules) covalently linked to a polymer (e.g. the
thermoplastic matrix polymer or the hydrophilic polymer or a third
polymer) or a scaffold.
[0107] Irgacure 2959 is a Norrish type I photo-initiator which
contains a nucleophilic primary hydroxyl group:
##STR00001##
[0108] The hydroxyl group in Irgacure 2959 may be functionalized to
an electrophilic acid derivative in several ways, so that it may
react with free hydroxyl and amino groups like BTDA and other
benzophenone derivatives, e.g.:
[0109] If stronger nucleophilicity is needed, Irgacure 2959 may be
sulfonated and then transformed into the corresponding primary
amine, e.g. by the Gabriel synthesis (see e.g. J. March: "Advanced
Organic Chemistry. Reaction, Mechanisms, and Structure", 3. ed., p.
377-9, Wiley-Interscience, New York, 1985):
##STR00002##
1. Synthesis of the Acid Derived from Cr(VI)-Oxidation of Irgacure
2959:
##STR00003##
2. Synthesis of the Acid Derived from 1:1 Reaction Between Irgacure
2959 and Succinic Anhydride:
##STR00004##
3. Synthesis of the Acid Derived from 1:1 Reaction Between Irgacure
2959 and Maleic Anhydride:
##STR00005##
[0110] Conversely, electrophilic 2- or 4-benzoylbenzoyl chloride
may be transformed to a nucleophile by slow addition to a large
excess of ethylene glycol, ethanolamine or ethylenediamine in order
to form the nucleophilic 1:1 ester or amide, which may e.g. react
with polyanhydrides such as Gantrez AN 119 BF and
poly(styrene-co-maleic anhydride) (SMA) (see further below), and
with isocyanates:
##STR00006##
[0111] The functionalization of Irgacure 2959 or BTDA or other
benzophenone derivatives on
Polystyrene-block-polybutadiene-block-polystyrene (SBS) is
interesting but not straightforward. For direct one-step coating
the double bond of SBS could be hydroxylated and esterified with
Irgacure 2959 acid, BTDA, 4-carboxybenzophenone,
2-carboxybenzophenone or others, e.g.:
##STR00007##
[0112] The aromatic keto groups of the photo-initiators are crucial
for the photoactivity, so it must be ensured that the vicinal diols
do not form ketals (i.e. 1,3-dioxolane derivatives) in an acid
catalyzed process with the keto groups, e.g. for Irgacure 2959:
##STR00008##
[0113] A coating on SBS may also consist of two layers: A basecoat
containing a photo-initiator and a compound that is compatible with
SBS, and a topcoat containing the thermoplastic polymer(s),
hydrophilic polymer(s), and photo-initiator(s). Usually the
concentration of photo-initiator should be higher in the basecoat
than in the topcoat in order to get good through curing. After
application of both the basecoat and the topcoat the coating must
be photo-cured. There are various possibilities: [0114] 1. The
basecoat may consist of a photo-initiator and a polybutadiene
diacrylate (such as BAC-45 with a molecular weight around 3000 Da,
but other molecular weights may also be used) from San Esters
Corporation. The topcoat should then consist of thermoplastic
polymer(s), hydrophilic polymer(s), photo-initiator(s) and
(meth)acrylates. After application of both layers the coating
should be photo-cured, whereby the primer coat and the topcoat are
cross-linked by (meth)acrylate polymerization. San Esters
Corporation indicate that the double bonds in SBS usually do not
participate in acrylate polymerization (see
http://www.sanesters.com/download/BAC-PRESENTATION.PPT). [0115] 2.
The basecoat may consist of a hydroxyl-terminated polybutadiene,
such as Krasol LBH 3000 (Sartomer) or similar, and
photo-initiator(s) containing a carboxylic acid or a carboxylic
acid forming group (such as an anhydride or an acid chloride). The
hydroxyl-terminated polybutadiene and the photo-initiator may then
react to form an ester during co-extrusion, injection moulding or
dipping, or they may be made to react before application of the
basecoat. The topcoat should consist of thermoplastic polymer(s),
hydrophilic polymer(s), and photo-initiator(s). After application
of both layers the coating should be photo-cured. [0116] 3. The
basecoat may consist of a hydroxyl-terminated polybutadiene which
is further epoxidized along the chain, such as Poly bd 600E or
similar from Sartomer, and photo-initiator(s) containing a
carboxylic acid or a carboxylic acid forming group (such as an
anhydride or an acid chloride). The carboxylic acid or carboxylic
acid forming group only reacts with free OH-groups and not with the
epoxide itself, so an amine is often added in order to hydrolyze
the epoxide ring, according to M. P. Stevens: "Polymer Chemistry.
An Introduction", 3. ed., p. 327-8, Oxford University Press, New
York, 1999. The hydrolysis may also be performed with aqueous
HClO.sub.4 or with HO.sup.- in DMSO, according to J. March:
"Advanced Organic Chemistry. Reaction, Mechanisms, and Structure",
3. ed., p. 332, Wiley-Interscience, New York, 1985. The
hydroxyl-terminated, ring-opened epoxidized polybutadiene may react
with the photo-initiator to form an ester during co-extrusion,
injection moulding or dipping, or they may be made to react before
application of the basecoat. The topcoat should consist of
thermoplastic polymer(s), hydrophilic polymer(s), and
photo-initiator(s). After application of both layers the coating
should be photo-cured. [0117] 4. The basecoat may consist of a
hydroxyl-terminated polybutadiene which is further epoxidized along
the chain, such as Poly bd 600E or similar from Sartomer, and
photo-initiator(s) containing a primary hydroxy group, such as
Irgacure 2959. The primary hydroxy group can react with epoxides
with an acid or a base catalyst to form a .beta.-hydroxy ether,
either before or during co-extrusion, injection moulding or
dipping:
[0117] ##STR00009## [0118] The hydroxyl-terminated, ring-opened
epoxidized polybutadiene may react further with acidic
photo-initiators to form an ester during co-extrusion, injection
moulding or dipping, or they may be made to react before
application of the basecoat. The topcoat should consist of
thermoplastic polymer(s), hydrophilic polymer(s), and
photo-initiator(s). After application of both layers the coating
should be photo-cured. [0119] 5. The basecoat may consist of an
isocyanate-terminated polybutadiene, such as Krasol NN-3A from
Sartomer, and photo-initiator(s) containing either a carboxylic
acid group (in which case the reaction product is an amide after
decarboxylation of the initial reaction product) or a hydroxyl
group (in which case the reaction product is a urethane). The
isocyanate-terminated polybutadiene and the photo-initiator may
react to form the product during co-extrusion, injection moulding
or dipping, or they may be made to react before application of the
basecoat. The topcoat should consist of thermoplastic polymer(s),
hydrophilic polymer(s), and photo-initiator(s). After application
of both layers the coating should be photo-cured.
[0120] HPEU, PEO, poly(1,2-propylene oxide), poly(tetramethylene
oxide), sugars, gelatins, hydroxypropyl methylcellulose,
starch-graft-polyacrylonitrile, starch-graft-poly(acrylic acid),
PVOH, poly(ethyleneimine) and other thermoplastic matrix polymers
or hydrophilic polymers, which are terminated with hydroxyl or
amino groups, may react with electrophilic photo-initiators such as
BTDA, 2- and 4-benzoylbenzoyl chloride, and Irgacure 2959 acid
chloride to form the corresponding photo-active esters or amides.
For example, BTDA may react with HPEU to form the following
polymers:
##STR00010##
[0121] The cross-linking reaction of the photoactive BTDA-based
poly(ester urethane acid) will be:
##STR00011##
[0122] Poly(amide acids) are formed from BTDA and diamine at room
temperature. They should have greater hydrolytic stability than
poly(ester acids) and hence be preferred over the esters. The acid
groups make the properties of the polyamide acids pH dependent: At
increasing pH their viscosity (and solubility) should increase in
water, and at low pH (i.e. as neutral species) they should be
soluble in polar organic solvents such as DMSO, DMA, DMF, and NMP;
together with pyridine these solvents are also best for the
synthesis of amide acids.
[0123] Jeffamine D-230 (hydrophobic; a=2-3, b=c=0) shown below as
diamine (from Huntsman) will reacted willingly with BTDA:
##STR00012##
[0124] Polyanhydrides might be functionalized with Irgacure 2959
(from Ciba):
##STR00013##
[0125] As mentioned above, BTDA may react with the hydroxyl end
groups of PEO (Polyox) and other polyethers or with amino groups in
poly(ethyleneimine) or other hydrophilic polymers. Upon
photo-curing of Polyox a stable, cross-linked, hydrophilic polymer
network is formed, which becomes very slippery when wet:
##STR00014##
[0126] Isocyanate-capped polyurethane as the thermoplastic matrix
polymer may also be functionalized with a nucleophilic
photo-initiator (such as Irgacure 2959) at both ends to form
photo-active polyurethane:
##STR00015##
[0127] Similarly, the side chains of the thermoplastic matrix
polymer poly(styrene-co-maleic anhydride) (SMA) may be modified
with a nucleophilic photo-initiator (such as Irgacure 2959 or
modified benzophenones):
##STR00016##
[0128] The hydrophilic polymer Gantrez AN-119 [=poly(maleic
anhydride-alt-methyl vinyl ether)] may also be functionalized with
Irgacure 2959 at the side chains:
##STR00017##
[0129] Acidic components of the thermoplastic matrix polymer and
the hydrophilic polymer may be transformed to the corresponding
acid chlorides, sulphonyl chlorides or phosphonyl chlorides by
treatment with SOCl.sub.2 or PCl.sub.5. Alternatively, the acids
may be treated with a dehydrating agent, such as
N,N'-dicyclohexylcarbodiimide, to species resembling acid
anhydrides in reactivity towards nucleophiles. Such acid chlorides,
sulphonyl chlorides and phosphonyl chlorides and the corresponding
anhydrides are activated towards reaction with nucleophilic
photo-initiators [such as Irgacure 2959, 2- or
4-hydroxybenzophenone, N-(2-hydroxyethyl)-2-benzoylbenzamide,
N-(2-hydroxyethyl)-4-benzoylbenzamide,
N-(2-aminoethyl)-2-benzoylbenzamide, and
N-(2-aminoethyl)-4-benzoylbenzamide] to form the respective esters,
amides, sulphonyl esters, sulphonamides, phosphonyl esters, and
phosphonamides. The acidic components of the thermoplastic matrix
polymer and the hydrophilic polymer include homo- and copolymers of
(meth)acrylic acid; maleic acid; fumaric acid; crotonic acid;
tiglic acid; itaconic acid; monoalkyl esters of dicarboxylic acids;
S-vinylsulphonic acid; vinylbenzenesulphonic acid;
2-acrylamido-2-methylpropanesulphonic acid (AMPS); 2-sulphoethyl
methacrylate; P-vinylphosphonic acid; carboxyl-containing
carbohydrates, such as pectin, alginates, CMC, furcellaran,
carrageenans, gum arabic, gum tragacanth, and xanthan gum; gelatin;
and starch-graft-poly(acrylic acid).
[0130] Photoactive esters and amides may be formed with excess
photo-active nucleophiles and electrophiles by transesterification,
transamidation or acidolysis of esters from the thermoplastic
matrix polymer and the hydrophilic polymer. Catalysts (such as
manganese or zinc salts) may be added, and a vacuum may be applied
if the photoinactive component to be removed has a lower boiling
point than the photoactive component, so as to remove the
photoinactive component from the equilibrium. There are three
possibilities of reaction, as the polymer side of the ester may be
both the acyl part (as e.g. in polyacrylates) and the alkoxyl part
(as e.g. in poly(vinyl acetate)):
Polymer-CO--OR+HO-Photo-initiator.fwdarw.Polymer-CO--O-Photo-initiator+H-
O--R (transesterification)
Polymer-CO--OR+H.sub.2N-Photo-initiator.fwdarw.Polymer-CO--NH-Photo-init-
iator+HO--R (transamidation)
Polymer-O--COR+HOOC-Photo-initiator.fwdarw.Polymer-O--CO-Photo-initiator-
+HOOC--R (acidolysis)
[0131] "Polymer-CO--OR" may be e.g. poly[alkyl(meth)acrylate],
poly(alkyl crotonate), poly(alkyl tiglate), poly(dialkyl maleate),
poly(dialkyl fumarate), and poly(dialkyl itaconate).
"Polymer-O--COR" may be e.g. poly(vinyl acetate).
"HO-Photo-initiator" may be e.g. Irgacure 2959, 2- or
4-hydroxybenzophenone, N-(2-hydroxyethyl)-2-benzoylbenzamide, and
N-(2-hydroxyethyl)-4-benzoylbenzamide. "H.sub.2N-Photo-initiator"
may be e.g. N-(2-aminoethyl)-2-benzoylbenzamide and
N-(2-aminoethyl)-4-benzoylbenzamide. "HOOC-Photo-initiator" may be
e.g. 2- or 4-benzoylbenzoic acid and Irgacure 2959 acid.
[0132] Several radical polymerized monoblock, diblock and triblock
copolymers are suitable as thermoplastic matrix polymers and
hydrophilic polymers (see above). Each hydrophobic block in those
diblock and triblock copolymers [e.g. homo- and copolymers of
styrenes, such as styrene, .alpha.-methylstyrene, vinyltoluene,
vinylpyridine, ethylstyrene, tert-butylstyrene, isopropylstyrene,
dimethylstyrene, and other alkylated styrenes; (meth)acrylic
esters, such as methyl acrylate, ethyl acrylate, propyl acrylate,
n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate,
tert-butyl acrylate, methyl methacrylate, ethyl methacrylate,
n-butyl methacrylate, and isobutyl methacrylate; butadiene;
chloroprene; vinyl halides, such as vinyl chloride; vinyl nitriles,
such as acrylonitrile and methacrylonitrile; vinyl esters, such as
vinyl acetate, vinyl versatate and vinyl propionate; ethylene;
propylene; 1-butene; and isobutylene] and each hydrophilic block
[e.g. homo- and copolymers of N-vinylpyrrolidone; (meth)acrylic
acid; maleic acid; fumaric acid; crotonic acid; tiglic acid;
itaconic acid; monoalkyl esters of dicarboxylic acids;
(meth)acrylamide; N-methylol(meth)acrylamide, and other
N-alkylacrylamides; N,N-dialkyl(meth)acrylamides, such as
N,N-dimethyl(meth)acrylamide; salts and acidic forms of
S-vinylsulphonic acid, vinylbenzenesulphonic acid,
2-acrylamido-2-methylpropanesulphonic acid (AMPS), 2-sulphoethyl
methacrylate, and P-vinylphosphonic acid; amides of vinylamine,
such as N-vinylformamide or N-vinylacetamide; vinylpyridine;
vinylimidazole; aminoalkyl (meth)acrylates, such as
dimethylaminoethyl(meth)acrylate and di-tert-butylaminoethyl
(meth)acrylate; and
N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulphopropyl)ammonium
betaine (SPE)] may suitably be copolymerized with a small amount of
a radical polymerizable photo-initiator in such a way that the
photo-initiator is left unchanged during radical polymerization.
Such radical polymerizable photo-initiators include esters or
amides of an alcohol or amine derivative of a photo-initiator (such
as a Norrish type I photo-initiator like Irgacure 2959 and/or a
hydrogen abstraction photo-initiator like 4-hydroxybenzophenone)
with polymerizable electrophiles like (meth)acrylic acid, maleic
acid, fumaric acid, itaconic acid, crotonic acid, tiglic acid,
N-acryloylglycine (or their derivatives, such as anhydrides and
acid chlorides), 2-vinyl-4,4-dimethyl-5-oxazolone,
2-(2-propenyl)-4,4-dimethyl-5-oxazolone,
2-vinyl-4,4-diethyl-5-oxazolone, or
2-vinyl-4,4-tetramethylene-5-oxazolone. Radical polymerizable
photo-initiators also include esters or amides of an acid
derivative of the photo-initiator (such as Irgacure 2959 acid
and/or 2- or 4-benzoylbenzoyl chloride) and an alcohol or amine
derivative of a polymerizable acid (such as 2-hydroxyethyl
methacrylate or 2-hydroxyethyl acrylate) or with 2-vinyloxazoline
or 2-(2-propenyl)oxazoline (which react with the carboxylic acid
group to form a radical polymerizable ester).
[0133] Benzophenones may be formed in situ by Friedel-Crafts
benzoylation of an electron-rich aromatic moiety with benzoyl
chloride and a Lewis acid as catalyst, e.g. AlCl.sub.3. Aromatic
anhydrides, such as phthalic anhydride, pyromellitic dianhydride
(1,2,4,5-benzenetetracarboxylic acid dianhydride) and BTDA, are
less reactive than benzoyl chloride but may also be used. If the
para position of the aromatic moiety is vacant, then the para
compound is the main product because of the size of the benzoyl
group (see e.g. J. March: "Advanced Organic Chemistry. Reaction,
Mechanisms, and Structure", 3. ed., p. 484-7, Wiley-Interscience,
New York, 1985). However, the method may also be used with aromatic
moieties which do not have vacant para positions. The aromatic
moiety may be part of homo- or copolymers of vinylpyridine,
styrene, .alpha.-methylstyrene, vinyltoluene, alkoxystyrene,
aryloxystyrene, ethylstyrene, tert-butylstyrene, isopropylstyrene,
dimethylstyrene, and other alkylated styrenes. Any aromatic
diisocyanates or aromatic diols that have been employed in the
production of HPEU may also be benzoylated. The aromatic moiety may
be present in either the thermoplastic matrix polymer or in the
hydrophilic polymer or in both. The aromatic ring of the benzoyl
chloride may also itself be substituted; electron donating
substituents on the benzoyl chloride will increase the rate of
reaction. As an example, with ordinary polystyrene the following
reaction occurs:
##STR00018##
[0134] Ethers such as PEO, poly(1,2-propylene oxide), or
poly(tetramethylene oxide) may be acyloxylated by reaction with a
tert-butyl peroxyester of a carboxyl-containing photo-initiator to
give the ether ester and tert-butyl alcohol (see J. March:
"Advanced Organic Chemistry. Reaction, Mechanisms, and Structure",
3. ed., p. 636-7, Wiley-Interscience, New York, 1985). The ether
may be present in either the thermoplastic matrix polymer or in the
hydrophilic polymer or in both. As an example, the coupling with a
benzophenone derivative (2-benzoylbenzoyl chloride) is shown
here:
##STR00019##
[0135] The reaction may also be carried out with BTDA or with an
acid chloride derivative of a Norrish type I photo-initiator, such
as Irgacure 2959 acid chloride.
[0136] Ethers such as PEO, poly(1,2-propylene oxide), or
poly(tetramethylene oxide) may alkylate (i.e. add to)
photo-initiator double bonds in the presence of peroxides to give
the corresponding alkylated ethers. The best results are obtained
with electron-deficient alkenes such as maleic anhydride (see C.
Walling, E. S. Huyser: "Free radical additions to olefins to form
carbon-carbon bonds", Organic Reactions, 13, 91-149). The ether may
be present in either the thermoplastic matrix polymer or in the
hydrophilic polymer or in both. A nucleophilic photo-initiator
(such as Irgacure 2959) may e.g. acquire an electron-deficient
double bond by esterification with maleic anhydride.
##STR00020##
[0137] PEO forms a strong water-soluble complex with urea (see N.
Clinton and P. Matlock: "Ethylene oxide polymers and copolymers",
in Encyclopaedia of Polymer Science and Engineering, 2. edition,
eds. H. F. Mark, N. M. Bikales, C. G. Overberger, vol. 6, p. 252
(1986)). An electrophilic photo-initiator (such as 2- or
4-benzoylbenzoyl chloride, BTDA or Irgacure 2959 acid chloride) may
react with N-(2-hydroxyethyl)urea to form the corresponding
photo-initiator ester urea, which will make a strong non-covalent
complex with PEO. Alternatively, polyureas terminated with amino
groups may react with electrophilic photo-initiators (such as 2- or
4-benzoylbenzoyl chloride or Irgacure 2959 acid chloride) to form
the corresponding photo-initiator amide polyureas, which will make
a strong non-covalent complex with PEO. Polyureas terminated with
isocyanate groups may react with nucleophilic photo-initiators
(such as Irgacure 2959) to form the corresponding photo-initiator
urethane polyureas, which will make a strong non-covalent complex
with PEO.
[0138] In a still further embodiment, a plurality of
photo-initiator moieties are covalently linked to a low molecular
weight scaffold, e.g. the photo-initiators may be covalently linked
to a low molecular scaffold, e.g. star-shaped, or a dendrimer.
[0139] The term "low molecular weight" refers to a scaffold
(without the photo-initiator moieties) having a molecular weight of
up to 10 kDa.
[0140] In applications where the potential presence of a small
amount of residual monomer is not prohibitive, a range of acrylate
monomers and oligomers may be added to the coating, e.g.
polybutadiene diacrylate (San Esters), Omnilane JL-103M
(acrylamidomethyl substituted cellulose ester polymer; from
IGM/Bomar), Omnilane BR 3641AA (1.3-functional aliphatic urethane
acrylate, adhesion promoter), Omnilane BDE-1029 (14-functional
dendritic polyester acrylate blend). Such compounds may cross-link
by reaction with radicals from photo-curing, e.g. PVP-centered
radicals:
##STR00021##
[0141] As it will be evident from the description above, the
present invention takes advantage of a covalent cross-linking
method which does not require cross-linking by means of
(meth)acrylate monomers, and the coating composition does therefore
in the most interesting embodiments not comprise (meth)acrylic
monomers. Residual acrylates may be acutely toxic, genotoxic,
carcinogenic, or they may cause allergy, skin rashes, sensitization
or, at best, be only locally irritating. Hence systems with
residual acrylates or other reactive monomers are best avoided.
Detailed Procedure for the Preparation of a Medical Device
Element
Step (i)
[0142] In an initial step of the method, the prefabricated shaped
article and/or the thermoplastic substrate polymer are
provided.
[0143] As it is clear from the section "Thermoplastic substrate
polymer", the substrate polymer is typically a commercial product
traded in a suitable physical form, e.g. as pellets, chips,
granules, etc. Hence, pre-treatment or preparation is normally not
necessary.
[0144] If a mixture of two or more substrate polymers is used, it
is typically desirable to homogenize the polymers, either in a
melted form or by dissolving the polymers in a common solvent
followed by solvent removal by conventional procedures and
involving conventional equipment, such as spray coating, roller
drying or precipitation in a non-solvent. Preferably, the solvent
solution is cast into a film and the solvent removed from the film
by any conventional technique. Reduced pressure and/or elevated
temperature may be used to aid solvent removal. The resulting
homogeneous blend may be chipped or pelletized prior to melt
processing.
[0145] It is further clear from the section "Prefabricated shaped
article" that the shaped article is often available from commercial
sources, or is readily prepared as will be known by the skilled
person within the relevant art. Alternatively, but also very
interestingly, the shaped article may be prepared immediately prior
to its use in the method of the invention, in certain embodiments
even in the same process line as the one where the method is
applied. Moreover, the prefabricated shaped article may be
pre-treated and even pre-coated prior to use in the method of the
invention.
Step (ii)
[0146] The coating composition for the preparation of the medical
device element may be prepared by dissolving the constituents
thereof in a common solvent. The solvent may then be removed to
leave a homogeneous blend of the matrix polymer, the hydrophilic
polymer, the one or more photo-initiators, and any additives, which
is ready for extrusion. Any conventional procedure or equipment may
be used for solvent removal, such as spray coating, roller drying
or precipitation in a non-solvent such as acetone or carbon
tetrachloride. Preferably the solvent solution is cast into a film
and the solvent removed from the film by any conventional
technique. The cast film may then be heated in a convection oven at
a temperature from ambient to about 70.degree. C. Reduced pressure
may be used to aid solvent removal. The resulting homogeneous blend
may be chipped or pelletized prior to melt processing or powder
coating.
[0147] In another embodiment, one or more of the matrix polymer and
the hydrophilic polymer, preferably the matrix polymer, is/are
in-situ polymerized in the formation of the coating, i.e. either in
step (iii) or in step (iv).
[0148] Typically, a mix of monomers or prepolymers corresponding to
the matrix polymer or the hydrophilic polymer or both are mixed
with the other constituents of the coating composition. The
homogeneous mixture of the monomers or the prepolymers is typically
heated and reacted to completion (e.g. 99-100% conversion). The
reaction of the monomers or the prepolymers can take place in a
continuous process such as in a twin-screw extruder or similar. The
reaction may also be carried out as a batch process with or without
stirring. The mixture or resulting homogeneous blend may after a
cooling step be chipped or pelletized prior to melt processing or
powder coating.
[0149] This pelletized coating composition may subsequently be
extruded, injection moulded or powder coated on the prefabricated
shaped article or the thermoplastic substrate polymer as described
for step (iii) below.
[0150] In one embodiment, monomers or pre-polymers corresponding to
the matrix polymer are mixed with the other constituents of the
coating composition.
[0151] For example, a mixture containing an organic isocyanate, low
molecular weight polyethylene glycols, chain extenders and a
suitable amount of catalysts is mixed with a hydrophilic polymer,
one or more photo-initiators and other additives.
[0152] The organic diisocyanate reactant may be any aliphatic,
alicyclic, aliphatic-alicyclic, aromatic or aliphatic-aromatic
compound consisting of 4 to 26 carbon atoms, more usually 6 to 20
carbon atoms and preferably 8 to 15 carbon atoms. Representative
diisocyanates are tetramethylene diisocyanate, hexamethylene
diisocyanate, trimethylhexamethylene diisocyanate, dimer acid
diisocyanate, isophorone diisocyanate, diethylbenzene diisocyanate,
decamethylene-1,10-diisocyanate, cyclohexylene-1,2-diisocyanate,
cyclohexylene 1,4-diisocyanate and
methylenebis(cyclohexyl-4-isocyanate); and aromatic isocyanates
such as 2,4- and 2,6-tolylene diisocyanate, 4,4-diphenylmethane
diisocyanate, 1,5-naphthalene diisocyanate, dianisidine
diisocyanate, toluidine diisocyanate, xylylene diisocyanate, and
tetrahydronapthalene-1,5-diisocyanate.
[0153] The poly(oxyalkylene) glycols are typically derived from
C2-C4 alkylene oxides such as oxyethylene, oxytrimethylene,
propylene glycol, oxybutylene, oxyisobutylene, butylene glycol and
oxytetramethylene (or the blend of poly(tetraoxymethylene) and
other polyether glycols) and further include random or block
copolymer polyols obtained by adding ethylene oxide to
1,2-propylene oxide or by adding ethylene oxide to a
poly(oxypropylene) chain. Furthermore the hydrophilic polyols may
also be branched or introduce branching such as in Tegomer.RTM. D
3403.
[0154] Chain extender examples include diols such as ethylene
glycol, diethylene glycol, triethylene glycol, 1,4-butanediol,
hexamethylene glycol, thiodiglycol, 2,2-dimethylpropane-1,3-diol,
1,4-bis(hydroxymethyl)benzene, bis(hydroxyethyl)disulphide,
cyclohexanedimethanol and hydroquinone; diamines such as
ethylenediamine, hexamethylenediamine and 1,4-butane diamine;
dihydrazides such as carbodithydrazide, oxalic hydrazide, hydrazine
and substituted hydrazines. The preferred chain extenders are
ethylene glycol, diethylene glycol and other alkylene glycols of 2
to 6 carbon atoms.
[0155] Suitable catalysts include tin salts and organotin esters
such as stannous octoate and dibutyl tin dilaurate, tertiary amines
such as triethylene diamine (DABCO.TM.),
N,N,N',N'-tetramethyl-1,3-butanediamine and other recognized
catalysts for urethane reactions.
[0156] In one particular embodiment the photo-initiator may contain
functional groups such as hydroxyl, carboxyl or amine groups either
as mono, di or multifunctional and may be polymerized into the
matrix polymer. Monofunctional photo-initiators will terminate the
polymerization of polyurethanes and give end-functional
polyurethanes. Continuous polymerization processes will be of
particular interest, such as polymerization in a twin-screw
extruder or similar continuous processes.
[0157] The advantages of in-situ polymerization are that several
process steps such as drying, compounding, pelletizing and hence
some types of characterization are avoided. Furthermore the
material is ideally mixed and the degradation is diminished because
the pelletized coating composition can be used directly without any
further treatment.
[0158] One example of in-situ polymerization of the matrix polymer
in the formation of the coating will be described in more detail in
the following.
[0159] Since PVP does not react with any of the components used to
prepare an HPEU, a coating composition comprising PVP and a
hydrophilic polyetherurethane may be prepared by adding the PVP to
the recipe for HPEU synthesis. Alternatively, the components of the
composition may be blended by melt compounding, such as in a
Brabender mixer, or with a single or twin screw extruder. In such
an instance, the HPEU and PVP are mixed in a suitable solvent
wherein the ratio of HPEU to PVP may be from 99:1 to 30:70 by
weight. The preferred ratio is about 50:50 by weight. Suitable
solvents are DMSO, DMF, DMAC and NMP. These high boiling solvents
may be used alone but are preferably mixed with a low boiling
solvent such as THF, methylene chloride or methyl ethyl ketone.
Most preferably, a solvent mixture containing a 3:2 ratio of DMAC
to THF is used. The composition may be about 1% to 20%, preferably
about 4 to 12% by weight in the solvent. It is evident that, if the
HPEU is prepared by emulsion polymerization as described above,
water may serve as the solvent and the PVP merely added
thereto.
[0160] Photo-initiators, either with low molecular weights,
oligomeric, polymeric or with functional groups can be blended and
eventually during the hot melt blending be grafted by chemically
bonding onto the thermoplastic matrix polymers.
Step (iii)
[0161] This step involves extruding, injection moulding or powder
coating the coating composition of step (ii) on the prefabricated
shaped article or together with the thermoplastic substrate polymer
of step (i) so as to provide the medical device element of said
prefabricated shaped article and/or substrate polymer having
thereon a layer of said coating composition, wherein, when both of
said prefabricated shaped article and substrate polymer are
present, said prefabricated shaped article has thereon a layer of
said substrate polymer.
[0162] Three main embodiments are encompassed by this step.
[0163] In a first main embodiment, only a prefabricated shaped
article is provided in step (i), and step (iii) involves extruding,
injection moulding or powder coating the coating composition of
step (ii) on the prefabricated shaped article of step (i) so as to
provide the medical device element of said prefabricated shaped
article having thereon a layer of said coating composition.
[0164] In a second main embodiment, only a thermoplastic substrate
polymer is provided in step (i), and step (iii) involves extruding
or injection moulding the coating composition of step (ii) together
with the thermoplastic substrate polymer of step (I) so as to
provide the medical device element of said thermoplastic substrate
polymer having thereon a layer of said coating composition.
[0165] In a third main embodiment, a prefabricated shaped article
as well as a thermoplastic substrate polymer are provided in step
(i), wherein step (iii) involves extruding or injection moulding
the coating composition of step (ii) on the prefabricated shaped
article together with the thermoplastic substrate polymer of step
(i) so as to provide the medical device element of said
prefabricated shaped article and said thermoplastic substrate
polymer, said prefabricated shaped article having thereon a layer
of said thermoplastic substrate polymer and said thermoplastic
substrate polymer having thereon a layer of said coating
composition.
[0166] The three main embodiments will be discussed in the
following.
[0167] In a first variant of the first main embodiment, a melt of
the coating composition is extruded onto a surface of a
prefabricated shaped article (see, e.g., Example 5).
[0168] In a second variant of the first main embodiment, a melt of
the coating composition is injection moulded onto a surface of a
prefabricated shaped article.
[0169] In a third variant of the first main embodiment, the coating
composition is powder coated onto a surface of a prefabricated
shaped article.
[0170] In one variant of the second main embodiment, a melt of the
thermoplastic substrate polymer and a melt of the coating
composition are extruded to give a shaped article having a coating
of the coating composition on the surface of the substrate
polymer.
[0171] In another variant of the second main embodiment, a melt of
the thermoplastic substrate polymer and a melt of the coating
composition are injection moulded to give a shaped article having a
coating of the coating composition on the surface of the substrate
polymer. This interesting variant can be accomplished in a two step
injection moulding process wherein in the outer layer of the
coating composition is first moulded followed by the moulding of
the thermoplastic substrate polymer.
[0172] In one variant of the third main embodiment, a melt of the
substrate polymer and a melt of the coating composition are
extruded onto a surface of a prefabricated shaped article (see,
e.g., Example 5).
[0173] In another variant of the third main embodiment, a melt of
the substrate polymer and a melt of the coating composition are
injection moulded onto a surface of a prefabricated shaped article.
This interesting variant can be accomplished in a two step
injection moulding process wherein in the outer layer of the
coating composition is first moulded using a solid core followed by
the moulding of the thermoplastic substrate polymer using the
prefabricated shaped article as the core.
[0174] The coating composition may be extruded/co-extruded with the
substrate polymer using any conventional and commercially available
extrusion equipment. Suitable co-extrusion apparatus may be
purchased, for example, from Genca Cable Company, Clearwater, Fla.,
or from Wayne Machine and Die Company, Totowa, N.J., or, if
desired, custom co-extrusion apparatus can be designed for
fabrication of any specific medical device element.
[0175] Alternatively, the composition may be crosshead-extruded or
co-extruded onto a prefabricated shape article, e.g. polymeric
article. Extrusion of a skin layer is a conventional process in
which a melt of a thermoplastic material (here the thermoplastic
substrate polymer or the coating composition) is metered through a
die directly onto a solid, continuous, shaped surface.
[0176] Moreover, (co)extrusion and injection moulding may be
conducted as described in U.S. Pat. Nos. 5,061,424 and
6,447,835.
[0177] The coating composition may also injection moulded so as to
provide a coating on a thermoplastic substrate polymer or
prefabricated shaped article. The injection moulding variants may
one or two process steps. In one variant corresponding to the
second variant of the first main embodiment (see above), the
coating composition is injected at high pressure into a mould,
which is the inverse of the shape of the final product, using a
solid core of the prefabricated shaped article. In a second variant
(corresponding to the second variant of the second main embodiment
(see above), step (iii) can be accomplished in two sub-steps,
namely by first moulding the coating composition using a solid
core, removing the solid core, and subsequently moulding the
thermoplastic substrate polymer, optionally using a slightly
smaller solid core. In a third variant (corresponding to the second
variant of the third main embodiment (see above), step (iii) can be
accomplished in two sub-steps, namely by first moulding the coating
composition using a solid core, removing the solid core, and
subsequently moulding the thermoplastic substrate polymer, using
the prefabricated solid article as the solid core. In a fourth
variant (corresponding to the second variant of the second main
embodiment (see above), step (iii) can be accomplished in two
sub-steps, namely by first moulding the thermoplastic substrate
polymer using a cavity of one size, removing the cavity, and
subsequently moulding the coating composition onto the
thermoplastic substrate polymer using a slightly larger cavity. In
a fifth variant (corresponding to the second variant of the third
main embodiment (see above), can be accomplished in two sub-steps,
namely by first moulding the thermoplastic substrate polymer using
a cavity of one size and the prefabricated shaped article as the
core, removing the cavity, and subsequently moulding the coating
composition onto the thermoplastic substrate polymer using a
slightly larger cavity.
[0178] With regard to powder coating which generally follows
conventional principles, the pelletized compound containing
hydrophilic polymers, photo-initiators and the thermoplastic matrix
polymers can be milled to a particle size in the range of 5 to 250
micrometers. Usually a powder coating composition with a particle
size distribution in the range of 10 to 100 micrometers is
preferred.
[0179] The powder coating compositions are typically applied by
spraying or by the use of a fluidized bed system. In case of a
metal substrate (prefabricated shaped article), application of the
coating by electrostatic spraying is preferred. In case of spraying
the powder coating can be applied in a single sweep or in several
passes to provide a film having the preferred thickness.
[0180] After applying the powder by spraying or by using a
fluidized bed system or any other powder coating application
technology known in the industry, the thermoplastic powder is
heated to about 80 to 200.degree. C., depending on the type of
substrate, to form a uniform coating layer about 5 to 250
micrometers thick, usually about 10 to 100 micrometers thick.
[0181] Within the various embodiments of the invention, the
thermoplastic matrix polymers in the compound may be either
polymerized "in situ" with polymerizable photo-initiators, or the
thermoplastic matrix polymers may be modified with photo-initiators
after polymerisation, so as to obtain covalent bonding between the
polymers and the photo-initiators. The hydrophilic polymers may
also contain photoactive groups, either by copolymerization of
hydrophilic monomers with monomers containing photo-initiators, or
the photoactive group may be covalently bound by a chemical
reaction between the hydrophilic polymers and the
photo-initiators.
[0182] The thickness of the dry layer of the coating composition is
typically 2.5-500 .mu.m, preferably 2.5-125 .mu.m.
[0183] The thickness of the substrate polymer (if present) is
typically 5-1000 .mu.m, more typically 10-50 .mu.m or 100-500
.mu.m.
[0184] The medical device element obtained by the method is dry and
in general non-sticky until humidified by finger-touch or wetted
with a liquid, at which time it develops a slippery, lubricious
surface. The chains of the hydrophilic polymer (e.g. PVP) are
believed to be substantially trapped in the matrix polymer both by
means of physical entrapment and by covalent bonding.
[0185] The method of the invention is particularly useful for the
preparation of medical device elements having the shape of a rod or
tubing. For example, a catheter thus prepared becomes instantly
lubricious when it comes into contact with a water-containing fluid
and thereby contributes greatly to the comfort of a patient
undergoing catheterization. An extruded rod in the form of a
guide-wire becomes lubricious when wet and thus slides easily.
[0186] After extrusion or injection moulding, it may be necessary
to cool the medical device element, e.g. by cold air or in a water
bath.
[0187] This being said, the currently most preferred embodiments of
the step (iii) are those involving (co)extrusion.
Step (iv)
[0188] In a subsequent step, the coating composition is irradiated
with UV or visible light so as to covalently cross-link the coating
composition. UV or visible light is defined as light having a
wavelength of 100-750 nm. Particularly relevant wavelength ranges
are 100-250 nm and 250-400 nm (both UV light), and 400-750 nm
(visible light). In the present context, the terms "photo-curing",
"photo-cure" and the like refer to curing by means of UV or visible
light. Curing by means of UV light is preferred, although curing by
means of blue light (visible light wavelength range) is equally
applicable.
[0189] The UV or visible light may be applied by means of a
polychromatic or monochromatic UV or visible light source,
preferably with high intensity and with an emission spectrum that
matches the absorbance spectrum of the photo-initiator(s) as well
as possible. In the absence of reactive monomers, the cross-linking
of the coating takes place only by the bimolecular combination of
radicals derived from the UV (or visible light) irradiated
photo-initiators. Hence, if the light intensity is doubled, the
concentration of radicals is also doubled, but the amount of
cross-linking reactions is quadrupled. This is why a high light
intensity is preferred. Suitable polychromatic light sources
include: (i) deuterium lamps, (ii) mercury lamps, possibly doped
with iron, gallium or other elements that significantly affects the
output spectrum, (iii) xenon arc lamps, both pulsed and unpulsed,
and (iv) halogen lamps (emit mainly visible light). Suitable
monochromatic light sources include: (v) gas and solid state lasers
(possibly frequency doubled, tripled, quadrupled or in other ways
frequency manipulated), both pulsed and unpulsed, and (vi) light
emitting diodes in the UV and visible area, both pulsed and
unpulsed.
[0190] An optimal irradiation period and light intensity can easily
be found by the skilled person by routine experiments, e.g. as
described in Example 6. For practical reasons (e.g. in the large
scale production of the medical device), the irradiation period
should preferably not exceed 300 sec, and in particular should not
exceed 600 sec.
[0191] Currently most preferred embodiments of the method of the
present invention include:
[0192] I. A method for the preparation of a medical device element,
said method comprising the steps of:
(i) providing a thermoplastic substrate polymer; (ii) providing a
coating composition comprising a thermoplastic matrix polymer
selected from hydrophilic polyurethane polymers and amphiphilic
block-copolymers, a hydrophilic polymer selected from polyethylene
oxide, and two or more different photo-initiators; (iii)
co-extruding the coating composition of step (ii) and the
thermoplastic substrate polymer of step (i) so as to provide the
medical device element of said substrate polymer having thereon a
layer of said coating composition; (iv) irradiating the coating
composition with UV or visible light so as to covalently cross-link
said coating composition.
[0193] II. A method for the preparation of a medical device
element, said method comprising the steps of:
(i) providing a thermoplastic substrate polymer; (ii) providing a
coating composition comprising a thermoplastic matrix polymer
selected from hydrophilic polyurethane polymers and amphiphilic
block-copolymers, a hydrophilic polymer selected from polyethylene
oxide, and one or more photo-initiator(s) covalently linked to a
polymer or a scaffold; (iii) co-extruding the coating composition
of step (ii) and the thermoplastic substrate polymer of step (i) so
as to provide the medical device element of said substrate polymer
having thereon a layer of said coating composition; (iv)
irradiating the coating composition with UV or visible light so as
to covalently cross-link said coating composition.
[0194] III. A method for the preparation of a medical device
element, said method comprising the steps of:
(i) providing a prefabricated shaped article and optionally a
thermoplastic substrate polymer; (ii) providing a coating
composition comprising a thermoplastic matrix polymer selected from
hydrophilic polyurethane polymers and amphiphilic block-copolymers,
a hydrophilic polymer selected from polyethylene oxide, and two or
more different photo-initiator(s); (iii) co-extruding the coating
composition of step (ii) on the prefabricated shaped article and,
if present, the thermoplastic substrate polymer of step (i) so as
to provide the medical device element of said prefabricated shaped
article and, if present, said substrate polymer having thereon a
layer of said coating composition, wherein, when said substrate
polymer is present, said prefabricated shaped article has thereon a
layer of said substrate polymer; (iv) irradiating the coating
composition with UV or visible light so as to covalently cross-link
said coating composition.
[0195] IV. A method for the preparation of a medical device
element, said method comprising the steps of:
(i) providing a prefabricated shaped article and optionally a
thermoplastic substrate polymer; (ii) providing a coating
composition comprising a thermoplastic matrix polymer selected from
hydrophilic polyurethane polymers and amphiphilic block-copolymers,
a hydrophilic polymer selected from polyethylene oxide, and one or
more photo-initiator(s) covalently linked to a polymer or a
scaffold; (iii) co-extruding the coating composition of step (ii)
on the prefabricated shaped article and, if present, the
thermoplastic substrate polymer of step (i) so as to provide the
medical device element of said prefabricated shaped article and, if
present, said substrate polymer having thereon a layer of said
coating composition, wherein, when said substrate polymer is
present, said prefabricated shaped article has thereon a layer of
said substrate polymer; (iv) irradiating the coating composition
with UV or visible light so as to covalently cross-link said
coating composition.
[0196] V. A method for the preparation of a medical device element,
said method comprising the steps of:
(i) providing a thermoplastic substrate polymer; (ii) providing a
coating composition comprising a thermoplastic matrix polymer
selected from hydrophilic polyurethane polymers and amphiphilic
block-copolymers, a hydrophilic polymer selected from polyethylene
oxide, and one or more different photo-initiator(s), e.g. two or
more different photo-initiators, where such photo-initiator(s) may
be covalently linked to a polymer or to a scaffold; (iii) injection
moulding the coating composition of step (ii) and the thermoplastic
substrate polymer of step (i) so as to provide the medical device
element of said substrate polymer having thereon a layer of said
coating composition; (iv) irradiating the coating composition with
UV or visible light so as to covalently cross-link said coating
composition.
[0197] VI. A method for the preparation of a medical device
element, said method comprising the steps of:
(i) providing a prefabricated shaped article and optionally a
thermoplastic substrate polymer; (ii) providing a coating
composition comprising a thermoplastic matrix polymer selected from
hydrophilic polyurethane polymers and amphiphilic block-copolymers,
a hydrophilic polymer selected from polyethylene oxide, and one or
more different photo-initiator(s), e.g. two or more different
photo-initiators, where such photo-initiator(s) may be covalently
linked to a polymer or to a scaffold; (iii) injection moulding the
coating composition of step (ii) on the prefabricated shaped
article and, if present, the thermoplastic substrate polymer of
step (i) so as to provide the medical device element of said
prefabricated shaped article and, if present, said substrate
polymer having thereon a layer of said coating composition,
wherein, when said substrate polymer is present, said prefabricated
shaped article has thereon a layer of said substrate polymer; (iv)
irradiating the coating composition with UV or visible light so as
to covalently cross-link said coating composition.
Novel Medical Devices
[0198] It is believed that the medical device elements resulting
from the method described above represent products which are novel
per se.
[0199] Hence, the present invention also relates to novel medical
devices comprising a medical device element of a thermoplastic
substrate polymer having thereon a layer of a covalently
cross-linked coating composition of (a) a thermoplastic matrix
polymer and (b) a hydrophilic polymer; wherein said coating
composition is (co)extruded or injection moulded with said
thermoplastic substrate polymer, or said coating composition is
powder coated on said thermoplastic substrate polymer; and wherein
the covalent cross-linking of the coating composition is the result
of the presence of one or more photo-initiators in the coating
composition and the exposure of the coating composition to UV or
visible light.
[0200] The present invention further relates to novel medical
devices comprising a medical device element of a prefabricated
shaped article having thereon a layer of a covalently cross-linked
coating composition of (a) a thermoplastic matrix polymer and (b) a
hydrophilic polymer; wherein said coating composition is extruded,
injection moulded or powder coated on said prefabricated shaped
article; and wherein the covalent cross-linking of the coating
composition is the result of the presence of one or more
photo-initiators in the coating composition and the exposure of the
coating composition to UV or visible light.
[0201] The present invention still further relates to novel medical
devices comprising a medical device element of a prefabricated
shaped article having thereon a layer of a thermoplastic substrate
polymer, where said thermoplastic substrate polymer has thereon a
layer of a covalently cross-linked coating composition of (a) a
thermoplastic matrix polymer and (b) a hydrophilic polymer; wherein
said coating composition is (co)extruded, injection moulded or
powder coated on said prefabricated shaped article and said
thermoplastic substrate polymer; and wherein the covalent
cross-linking of the coating composition is the result of the
presence of one or more photo-initiators in the coating composition
and the exposure of the coating composition to UV or visible
light.
[0202] In interesting embodiments of the above, said one or more
photo-initiators are covalently linked to molecules of the
thermoplastic matrix polymer and/or to molecules of the hydrophilic
polymer
[0203] Following the discussion further above, the coating
composition does not comprise low-molecular weight residues of
(meth)acrylic monomers.
[0204] The materials useful as the prefabricated shaped article,
the thermoplastic substrate polymer and as constituents of the
coating compositions are as described above for the method of the
invention.
[0205] Hence, in one embodiment, the thermoplastic substrate
polymer is selected from the group consisting of polyurethanes, and
PVC.
[0206] In a further embodiment, the thermoplastic matrix polymer is
a polyurethane polymer, in particular a hydrophilic polyurethane
polymer.
[0207] In a still further embodiment, the hydrophilic polymer is
selected from the group consisting of poly(vinyl lactams) [e.g.
PVP], PEO, polyoxazolines, PVOH, and polyacrylates. The currently
most preferred hydrophilic polymer is PEO.
EXAMPLES
TABLE-US-00001 [0208] Abbreviations Trade name/ trivial name/
abbreviation Chemical name 2-BBCl 2-Benzoylbenzoyl chloride BDO
1,4-Butanediol BTDA 3,3',4,4'-Benzophenonetetracarboxylic acid
dianhydride Chivacure 3482
2-Methyl-1-[4-(alkylthio)phenyl]-2-(4-morpholinyl)-1-propanone
(alkyl chain not revealed) Chivacure 3690
2-Benzyl-2-(dimethylamino)-1-[4-(alkylmethylamino)phenyl]-1-butanone
(alkyl chain not revealed) CMC Carboxymethylcellulose Darocur 1173
2-Hydroxy-2-methylpropiophenone; 2-hydroxy-2-propyl phenyl ketone
Darocur TPO Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide DMAC
N,N-Dimethylacetamide DMAEMA N,N-Dimethylaminoethyl methacrylate
DMF N,N-Dimethylformamide DMSO Dimethylsulfoxide EEA
Copoly(ethylene/ethyl acrylate) EMA Copoly(ethylene/methyl
acrylate) EnBA Copoly(ethylene/n-butyl acrylate) EO Ethylene oxide
Esacure KIP
Oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone} 150
Esacure One "Difunctional .alpha.-hydroxy ketone" (structure not
revealed) EVA Copoly(ethylene/vinyl acetate) EVA g-MAH
Copoly(ethylene/vinyl acetate)-graft-poly(maleic anhydride) EVOH
Copoly(ethylene/vinyl alcohol) GMA Glycidyl methacrylate
(2,3-epoxypropyl methacrylate) HPEU Hydrophilic polyetherurethane
Irgacure 127 Bis(4-(2-hydroxy-2-propylcarbonyl)phenyl)methane
Irgacure 184 1-Hydroxy-1-cyclohexyl phenyl ketone Irgacure 2959
2-Hydroxy-2-propyl 4-(hydroxyethoxy)phenyl ketone Irgacure 369
2-Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone
Irgacure 379
2-(4-Methylbenzyl)-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-
butanone Irgacure 651 Benzil .alpha.,.alpha.-dimethyl ketal;
.alpha.,.alpha.-dimethoxy-.alpha.-phenylacetophenone; 2,2-
dimethoxy-1,2-diphenyl-1-ethanone Irgacure 819
Phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide Irgacure 907
2-Methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone
LDPE Low density polyethylene LLDPE Linear low density polyethylene
MAH Maleic anhydride MDI Methylene-4,4'-diphenyldiisocyanate NMP
N-Methylpyrrolidone NVP N-Vinyl pyrrolidone Omnilane XP- "Medium
molecular weight, trifunctional, aliphatic polyether urethane
acrylate 144 LS-B oligomer with backbone-grafted photo-initiator"
(photo-initiator not revealed but may be benzoin.sup..sctn.)
Omnipol BP Poly(tetramethylene glycol) 250 diester of
4-benzoylphenoxyacetic acid Omnipol TX Poly(tetramethylene glycol)
250 diester of 2-thioxanthonyloxyacetic acid PE Polyethylene PE
g-MAH Polyethylene-graft-poly(maleic anhydride) Pebax
Polyether-block-polyamide PEG Poly(ethylene glycol) PEO
Poly(ethylene oxide) PMDA Pyromellitic acid dianhydride;
1,2,4,5-benzenetetracarboxylic acid dianhydride PO 1,2-Propylene
oxide PP Polypropylene PS Polystyrene PVC Poly(vinyl chloride) PVOH
Poly(vinyl alcohol) PVP Poly(vinyl pyrrolidone) PVP-DMAEMA
Copoly(vinyl pyrrolidone/N,N-dimethylaminoethyl methacrylate) SBS
Polystyrene-block-polybutadiene-block-polystyrene SEBS
Polystyrene-block-poly(ethylene/butylene)-block-polystyrene SEEPS
Polystyrene-block-hydrogenated
poly(isoprene/butadiene)-block-polystyrene SEPS
Polystyrene-block-poly(ethylene/propylene)-block-polystyrene SIS
Polystyrene-block-polyisoprene-block-polystyrene SMA
Poly(styrene-co-maleic anhydride) THF Tetrahydrofuran VLDPE Very
low density polyethylene .sup..sctn.See J. A. Leon, I. V. Khudyakov
from Bomar Specialties, USA (2005): "UV-Light Sensitive (LSR)
Urethane Acrylate Oligomers", Proceedings from RadTech Europe 05,
Barcelona, Spain, Oct. 18-20, 2005, vol. 2, p. 359-64,
Vincentz.
Materials
[0209] The hydrophilic polyurethane Tecogel 2000 (lots CD53RA015
and PM-03-36D with a water absorption of 500% and 1800%,
respectively) were from Noveon; unless otherwise stated lot
CD53RA015 was used. The hydrophilic polyurethane Tecogel 500 and
the hydrophobic polyurethane Estane 58212 were also from Noveon.
The phenoxy resins PKHB (M.sub.n 9.5 kDa), PKHH (M.sub.n 16 kDa),
and PKCP80 (phenoxyresin modified with caprolactone; M.sub.w 39
kDa) were from InChem. Corp.
[0210] The PEO's WSR N-80 (MW 200 kDa) and N-301 (MW 4 MDa) were
from Dow. MPEG 350 and PEG 400 was from Clariant. PVP K-25 and PVP
K-90 were from ISP Corp. (Wayne, N.J.). PEG 35000 ("Polyglykol
Hoechst 35000 Schuppen", batch E06389543; MW 35 kDa) was from
Hoechst.
[0211] The photo-initiator Esacure KIP 150 was from Lamberti Spa
(Gallarate, Italy). The photo-initiators Irgacure 127, Irgacure
651, and Irgacure 2959 were from Ciba Specialty Chemicals (Basel,
Switzerland). 97% BTDA was from Alfa Aesar. 4-Benzoylbenzoic acid,
2-benzoylbenzoic acid and tert-butyl peroxybenzoate were from
Aldrich. CuCl was from Fluka.
[0212] Gantrez AN 119 BF (polyanhydride, reactive) and Gantrez ES
225 (alcoholyzed polyanhydride, non-reactive) were from ISP. PMDA
(pyromellitic acid dianhydride; 1,2,4,5-benzenetetracarboxylic acid
dianhydride) was from Aldrich. SMA 1000 (acid no. 465-495 mg KOH/g
sample, MW 5500 g/mol), SMA 2000 (acid no. 335-375 mg KOH/g sample,
MW 7500 g/mol), and SMA 3000 (acid no. 265-305 mg KOH/g sample, MW
9500 g/mol) were from Atofina. Joncryl 804 was from BASF.
[0213] 1-Methylimidazole and pyridine were from Merck. Ethyl
acetate, 2-propanol and acetone were from Bie & Berntsen
(Denmark). DMSO and thionyl chloride were from Aldrich. Benzene was
from Fluka. MIBK was from Baker. Acetic acid was from Merck.
Dichloromethane was from AppliChem. Jeffamine D-230 was from
Huntsman.
[0214] All percentages and parts given are weight/weight-% unless
otherwise stated.
Example 1
Preparation
[0215] 60 parts Tecogel 2000 and 40 parts Polyox N-80 were
compounded together in a Brabender compounder at 120.degree. C. for
10 minutes. During the last 5 minutes 0-1 part Esacure KIP 150 (see
the table below) was added to the blend. After compounding, the
blends were hot melt pressed at 120.degree. C. for 20 seconds into
thin sheets with a thickness of 150-200 .mu.m. The sheets were hot
press laminated at 120.degree. C. for 90 seconds onto substrates of
the polyurethane Tecogel 500, which is less hydrophilic than
Tecogel 2000. The laminates were UV cured for 4 minutes with a
UVASPOT 400/T F-lamp (450 W; arc about 1 inch long; substrate
placed about 26 cm from the bulb; Dr. K. Honle GmbH UV-Technologie,
Planegg b. Munchen, Germany) at a temperature of approximately
65.degree. C. where the blends were limpid and hence transparent to
the UV light.
Results and Discussion
[0216] The friction and the adhesion to the substrate were
evaluated subjectively after swelling in water for at least 24
hours. The adhesion between the two layers (coating and substrate)
was given a score from 1 to 4:
1. Complete delamination 2. Poor adhesion, a lot of water blisters
3. Good adhesion, few water blisters 4. Very good adhesion, smooth
surface
TABLE-US-00002 Score of UV cured Score of not UV cured % Esacure
KIP 150 preparation preparation 0.0 2 2 0.1 2 2 0.5 4 2 1.0 3 2
[0217] The adhesion between the two layers increased upon UV curing
with a photo-initiator concentration above 0.1%. A few blisters
were observed at 1.0% photo-initiator. This insufficient curing at
the interface between the two layers could be caused by the high
concentration and the pronounced absorption of the UV light at the
top of the layer, i.e. at the surface. The friction was also lower
for the UV cured layers containing the photo-initiator (data not
shown). The UV cross-linking of the water-soluble Polyox N-80 bound
it to the polyurethane and prevented it from dissolving and from
being washed out, i.e. the friction could be maintained for a
longer period of time.
Example 2
Preparation
[0218] Tecogel 2000 was hot melt compounded with different
concentrations of Polyox N-80. The blends contained 1% of Esacure
KIP 150. The preparation of the samples and the UV curing were as
described in Example 1. The blends were laminated onto substrates
of Tecogel 500 or Estane 58212.
Results and Discussion
[0219] The adhesion to the substrate was evaluated subjectively
after swelling in water for at least 24 hours.
TABLE-US-00003 Tecogel 500 Estane 58212 w/w-ratio Polyox N- UV Not
UV UV Not UV 80:Tecogel 2000 cured cured cured cured 20:80 4 2 2 1
40:60 4 2 2 1 60:40 4 1 1 1 80:20 4 1 1 1
[0220] The adhesion to Tecogel 500 was greatly improved by UV
curing and was unaffected by the concentration of Polyox N-80. The
adhesion to Estane 58212 did not improve with UV curing, since
Tecogel 2000 and Estane 58212 were not compatible and all the
samples either delaminated or had blisters.
Example 3
Preparation
[0221] 59.5% Tecogel 2000, 40% Polyox N-80, and 0.5% Esacure KIP
150 were hot melt compounded. The preparation of the samples and
the UV curing were as described in Example 1.
[0222] The blend was laminated onto different substrates. The
substrates were primarily based on Estane 58212 but different types
and amounts of phenoxy resins were added as compatibilizers, cf.
the table below.
Results and Discussion
[0223] The adhesion to the substrate was evaluated subjectively
after swelling in water for at least 24 hours.
TABLE-US-00004 Substrate UV cured Not UV cured Estane 58212 1 1
Phenoxy resin, PKHB 3 1 Phenoxy resin, PKHH 4 1 Phenoxy resin,
PKCP80 3 1 90% Estane 58212 + 10% 3 1 PKHB 60% Estane 58212 + 40% 4
1 PKHB 90% Estane 58212 + 10% 3 1 PKHH 60% Estane 58212 + 40% 4 1
PKHH 90% Estane 58212 + 10% 4 1 PKCP80 60% Estane 58212 + 40% 4 1
PKCP80
[0224] The addition of a phenoxy resin compatibilizer to the
polyurethane Estane 58212 made it possible to UV bond the Tecogel
2000 blend to the substrates, but without UV curing, good adhesion
was not obtained.
Example 4
Preparation
[0225] 59.5% Tecogel 2000 was hot melt compounded with 40% Polyox
N-80 and 0.5% of either Esacure KIP 150, Irgacure 127 or Irgacure
651 as photo-initiator. The preparation of the samples was as
described in Example 1. The UV curing was done with a Fusion 600I
H-lamp (600 W/inch, arc about 20 cm long, substrate placed about 26
cm from the bulb) at 100% intensity for 4 minutes.
[0226] The blends were hot press laminated onto substrates of
Tecogel 500, Estane 58212, and 90% Estane 58212 with 10% phenoxy
resin PKHH.
Results and Discussion
[0227] The adhesion to the substrate was subjectively evaluated
after swelling in water for at least 24 hours.
TABLE-US-00005 90% Estane 58212 + Tecogel 500 Estane 58212 10% PKHH
UV Not UV UV Not UV UV Not UV Photo-initiator cured cured cured
cured cured cured Esacure KIP 3 2 4 2 4 2 150 Irgacure 127 4 3 3 2
2 1 Irgacure 651 3 1 4 1 4 1
[0228] All three photo-initiators improved the adhesion to all
three substrates, although Irgacure 127 was less effective than
Esacure KIP 150 and Irgacure 651 in effecting adhesion to
substrates containing Estane 58212. The addition of phenoxy resin
did not improve the bonding between the layers. Furthermore, a
comparison between (a) the sample with Esacure KIP 150 on Estane
58212 that was UV cured with the Fusion lamp, and (b) the
corresponding sample from Example 3 that was cured with the weaker
lamp from Dr. Hanle showed, that the higher UV intensity used with
the former sample was very beneficial for the adhesion of the
coating on the substrate.
Example 5
Preparation
[0229] 59.5% of either of two different lots of Tecogel 2000 with
different water absorption capacity (CD53RA015 and PM-03-36D) were
hot melt compounded with 40% Polyox N-80 and 0.5% Irgacure 651.
[0230] The preparation of the samples was as described in Example
1. The UV curing was done with a Fusion 600I H-lamp at 100%
intensity for 2 minutes. The blends were hot press laminated onto
substrates of Tecogel 500.
Results and Discussion
[0231] The adhesion to the substrate was evaluated subjectively
after swelling in water for at least 24 hours.
TABLE-US-00006 Ratio of Tecogel 2000 types CD53RA015:PM-03-36D UV
cured Not UV cured 100:0 4 2 40:60 2 1 20:80 2 1
[0232] Adding the extremely hydrophilic polyurethane PM-03-36D to
the blend made it more difficult to UV bond the layer to the
substrate. To get good adhesion the two layers need to be
compatible with each other, so that during lamination there will be
good mixing of the polymer chains at the interface. This would give
a better cross-linking of the polymer chains from the two
layers.
Example 6
TABLE-US-00007 [0233] Compound Compound Compound Compound
Ingredients A B C D Tecogel 2000 59.7% 39.8% 19.9% Tecogel 500
99.5% PolyOx N-80 39.8% 59.7% 79.6% Irgacure 651 0.5% 0.5% 0.5%
0.5%
[0234] These ingredients were compounded together with a twin-screw
extruder. The ingredients were fed to the extruder by gravimetric
feeders, extruded into strands and pelletized. The extruder profile
was:
TABLE-US-00008 zone 1 zone 2 zone 3 zone 4 zone 5 zone 6 zone 7
zone 8 zone 9 Die .degree. C. 80 90 100 110 120 130 140 150 150
150
[0235] Two single screw extruders were then connected to a single
crosshead dual tube die. Extruder #1 was charged with Compound D,
and extruder #2 was charged with Compound A, B or C. The blends
were extruded onto a prefabricated tube of Estane 58212 (see FIG.
1). Extruder #1 then extruded Compound D as the inner layer and
extruder #2 extruded Compound A, B or C as the outer layer. The
ratios of inner to outer layer was varied by adjusting the output
of either extruder by increasing or lowering the screw speed. The
thickness of the layers was adjusted by varying either the output
or the haul-off speed.
[0236] The two extruders had the same temperature profile.
TABLE-US-00009 zone 1 zone 2 zone 3 zone 4 zone 5 Head Die .degree.
C. 40 105 155 175 175 195 200
[0237] After extrusion, the coated tube was cut into 35 cm long
samples and UV cured for 0, 60, 120, or 180 seconds with a Fusion
600I H-lamp at 100% intensity. The UV cured samples were swelled in
a 0.9% saline solution for at least 24 hours. The adhesion of the
layers to the tube were subjectively evaluated as in Example 1.
[0238] The period of the UV treatment of Compounds A, B and C is
shown in FIG. 6. The adhesion to the tube was improved for all
three compounds when they were UV cured. Compound C with the lowest
amount of polyurethane in the outer layer needed the longest UV
treatment to adhere properly to the tube. FIG. 2 shows delamination
from the tube after swelling due to insufficient UV curing. FIG. 3
shows swelled layers bonded to the tube due to proper UV
curing.
Example 7
Coatings Consisting of Polyox with and without 20% Irgacure 2959 as
Photo-Initiator, Bound and Unbound to Gantrez AN 119 BF
[0239] Preparation of Sample 7A: Irgacure 2959 Bound to Polymer at
100.degree. C. and then Compounded with Polyox
[0240] 7.8 g Gantrez AN 119 BF (50 mmol anhydride), 15.5 g MPEG 350
(44 mmol), and 1.7 g Irgacure 2959 (7.6 mmol) were mixed and
compounded in a Brabender mixer at 100.degree. C. for 90 minutes.
No work-up was performed; this was Mixture 1. The progress of the
reaction with time was monitored by FT-IR as the decrease of the
anhydride peaks at 1854-5 cm.sup.-1 and 1772-6 cm.sup.-1 and the
simultaneous increase in the ester/carboxylic acid peak at 1726
cm.sup.-1, see FIG. 7.
[0241] After about 90 minutes a substantial amount of the anhydride
had reacted, and the level of remaining anhydride only decreased
slowly, so the reaction was stopped at this time.
[0242] 83.745 parts Polyox N-301 and 9.305 parts Polyox N-80 were
premixed and melted by slow addition to a Brabender mixer at
120.degree. C. After complete addition of Polyox, the mixture was
compounded for 2 minutes, and 6.95 parts of Mixture 1 was added.
The resulting mixture was compounded for 2 minutes at atmospheric
pressure, then for 2 minutes in vacuum. This was Mixture 2, which
contained 0.47 w/w-% Irgacure 2959.
[0243] Mixture 2 was hot pressed at 100.degree. C. for a minute to
form a circular slice with thickness 1 mm. A quarter of the slice
was further hot pressed at 100.degree. C. without distance pieces
to a slice that was as thin as possible. The thickness was not
measured routinely but was between 150 and 200 .mu.m.
[0244] The thin slice of Mixture 2 was laminated on a sheet of
Estane 58212, which had previously been wiped clean with ethanol,
at 100.degree. C. and 50 bars for about 30-45 seconds (no distance
pieces used).
[0245] The sample was divided into two sections, that were both
heated to 60-80.degree. C. for 5-10 minutes until they were
transparent. One sample was then immediately UV cured for 1 minute
and the other for 5 minutes at a distance of about 26 cm from a
Fusion I600H-lamp running at 100% intensity.
Preparation of Sample 7B: Irgacure 2959 Bound to Polymer at
120.degree. C. and then Compounded with Polyox
[0246] 7.8 g Gantrez AN 119 BF (50 mmol anhydride), 15.5 g MPEG 350
(44 mmol), and 1.7 g Irgacure 2959 (7.6 mmol) were mixed and
compounded in a Brabender mixer at 120.degree. C. for 90 minutes.
The rest of the procedure was identical to that described for
sample 7A. The samples contained 0.47% Irgacure 2959.
Preparation of Sample 7C: MPEG 350 Bound to Polymer and then
Compounded with Polyox
[0247] 7.2 g Gantrez AN 119 BF (46 mmol anhydride) and 17.8 g MPEG
350 (51 mmol) were mixed and heated for 24 hours at 90.degree. C.
in a heat cupboard. No work-up was performed; this was Mixture
3.
[0248] 84.6 parts Polyox N-301 and 9.4 parts Polyox N-80 were
premixed and melted by slow addition to a Brabender mixer at
120.degree. C. After complete addition of Polyox, the mixture was
compounded for 2 minutes, and 6.0 parts of Mixture 3 was added. The
resulting mixture was compounded for 2 minutes at atmospheric
pressure, then for 2 minutes in vacuum. This was Mixture 4, which
contained no photo-initiator.
[0249] Mixture 4 was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A.
Preparation of Sample 7D: MPEG 350 Bound to Polymer and Compounded
with Polyox in One Step
[0250] 1.5 parts Gantrez AN 119 BF, 3.0 parts MPEG 350, 85.95 parts
Polyox N-301, and 9.55 parts Polyox N-80 were compounded in a
Brabender mixer at 120.degree. C. for 2 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained no photo-initiator.
Preparation of Sample 7E: Irgacure 2959 not Bound to Polymer
[0251] 3.04 parts Gantrez ES 225 (non-reactive homologue of Gantrez
AN 119 BF), 3.00 parts MPEG 350, 0.48 parts Irgacure 2959, 84.13
parts Polyox N-301, and 9.35 parts Polyox N-80 were compounded in a
Brabender mixer at 120.degree. C. for 2 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained 0.48% Irgacure 2959.
Preparation of Sample 7F: MPEG 350 not Bound to Polymer
[0252] 3.04 parts Gantrez ES 225, 3.00 parts MPEG 350, 84.56 parts
Polyox N-301, and 9.40 parts Polyox N-80 were compounded in a
Brabender mixer at 120.degree. C. for 2 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained no photo-initiator.
Results and Discussion for Samples 7A-F
[0253] The samples were immersed in deionized water for at least 24
hours. The adhesion of the UV cured coatings to the Estane 58212
substrate was scored as described in Example 1. At the same time
the cohesion of the gels was scored on a subjective scale from 1 to
6:
1=No cross-linking; coating dissolved 2=Very weak, loose gel which
cannot be handled without breaking 3=Somewhat stable gel 4=Rather
stable gel 5=Almost stable gel 6=Entirely stable and cohesive
gel
[0254] The results are shown here:
TABLE-US-00010 1 min. UV curing 5 min. UV curing Contains Gel
Adhesion to Gel Adhesion to photo- Reactive cohesion substrate
cohesion substrate Sample initiator? polymer? (1-6) (1-4) (1-6)
(1-4) 7A-100 Yes Yes 1 1 3 1 7B-120 Yes Yes 2 1 2.5 1 7C No Yes 1 1
1 1 7D No Yes 1 1 1 1 7E Yes No 3.5 1 5.5 1 7F No No 1 1 1 1
[0255] The sample with unbound photo-initiator (7E) gave a stronger
gel than the samples with photo-initiator bound to the Gantrez
polymer (7A-B) after both 1 and 5 minutes UV curing. Sample 7E gave
an especially strong gel after 5 minutes UV curing. Furthermore,
there was no significant difference between 7A and 7B, indicating
that the formation of the polymer-bound photo-initiator was robust
towards temperature changes during production. Gels with no
photo-initiator (7C-D and 7F) had no cohesion. Hence
photo-initiator was necessary to cross-link the coating in this
system. None of the gels stuck to the substrate polymer.
[0256] In this and the later examples several measurements were
made on systems that had not been UV cured. In all tested cases the
gels were non-cohesive and non-adhesive, so the data were not
shown.
Example 8
Coatings Consisting of Polyox and Tecogel 2000 with and without
Irgacure 2959 and BTDA as Photo-Initiators
Preparation of Sample 8A: Irgacure 2959 Bound to BTDA (Double
Photo-Initiator System)
[0257] 7.93 g 97% BTDA (23.9 mmol), 14.71 g MPEG 350 (42.0 mmol),
and 2.36 g Irgacure 2959 (10.5 mmol) were mixed and heated for 24
hours at 90.degree. C. in a heat cupboard. No work-up was
performed; this was Mixture 5.
[0258] 51.4 parts Polyox N-301, 5.7 parts Polyox N-80, and 38.1
parts Tecogel 2000 were premixed and melted by slow addition to a
Brabender mixer at 120.degree. C. After complete addition, the
mixture was compounded for 10 minutes, and 4.8 parts of Mixture 5
was added. The resulting mixture was compounded for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. This was
Mixture 6.
[0259] Mixture 6 was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A. The samples
contained 1.48% BTDA and 0.45% Irgacure 2959.
Preparation of Sample 8B: Photoactive Irgacure 2959 Bound to
Photoinactive PMDA
[0260] 5.98 g 97% PMDA (26.6 mmol), 16.39 g MPEG 350 (46.8 mmol),
and 2.63 g Irgacure 2959 (11.7 mmol) were mixed and heated for 24
hours at 90.degree. C. in a heat cupboard. No work-up was
performed; this was Mixture 7.
[0261] 51.4 parts Polyox N-301, 5.7 parts Polyox N-80, and 38.1
parts Tecogel 2000 were premixed and melted by slow addition to a
Brabender mixer at 120.degree. C. After complete addition, the
mixture was compounded for 10 minutes, and 4.8 parts of Mixture 7
was added. The resulting mixture was compounded for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. This was
Mixture 8.
[0262] Mixture 8 was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A. The samples
contained 0.50% Irgacure 2959.
Preparation of Sample 8C: Photoactive BTDA Bound to Photoinactive
MPEG 350
[0263] 7.54 g 97% BTDA (22.7 mmol) and 17.47 g MPEG 350 (49.9 mmol)
were mixed and heated for 24 hours at 90.degree. C. in a heat
cupboard. No work-up was performed; this was Mixture 9.
[0264] 52.2 parts Polyox N-301, 5.8 parts Polyox N-80, and 38.7
parts Tecogel 2000 were premixed and melted by slow addition to a
Brabender mixer at 120.degree. C. After complete addition, the
mixture was compounded for 10 minutes, and 3.3 parts of Mixture 9
was added. The resulting mixture was compounded for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. This was
Mixture 10.
[0265] Mixture 10 was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A. The samples
contained 0.97% BTDA.
Preparation of Sample 8D: Photoinactive MPEG 350 Bound to
Photoinactive PMDA
[0266] 5.65 g 97% PMDA (25.1 mmol) and 19.35 g MPEG 350 (55.3 mmol)
were mixed and heated for 24 hours at 90.degree. C. in a heat
cupboard. No work-up was performed; this was Mixture 11.
[0267] 51.4 parts Polyox N-301, 5.7 parts Polyox N-80, and 38.1
parts Tecogel 2000 were premixed and melted by slow addition to a
Brabender mixer at 120.degree. C. After complete addition, the
mixture was compounded for 10 minutes, and 4.8 parts of Mixture 11
was added. The resulting mixture was compounded for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. This was
Mixture 12.
[0268] Mixture 12 was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A. The samples
contained no photo-initiator.
Results and Discussion for Samples 8A-D
[0269] The samples were immersed in deionized water for at least 24
hours. The adhesion and cohesion of the UV cured coatings to the
Estane 58212 substrate was scored as described in Example 7.
[0270] The results are shown here:
TABLE-US-00011 1 min. UV curing 5 min. UV curing Contains Gel
Adhesion to Gel Adhesion to Irgacure Contains cohesion substrate
cohesion substrate Sample 2959? BTDA? (1-6) (1-4) (1-6) (1-4) 8A
Yes Yes 6 3 6 3 8B Yes No 6 1 6 1 8C No Yes 6 3 5 3 8D No No 1 1 6
1
[0271] Excellent gels resulted after 1 or 5 minutes UV curing when
either or both of the photo-initiators Irgacure 2959 or BTDA were
present in the recipe (samples 8A-C). Furthermore, when BTDA was
present (samples 8A and 8C), the gels adhered strongly to the
substrate, whereas PMDA-bound Irgacure 2959 alone (sample 8B) did
not bind to the substrate. By contrast, the gel observed in sample
8D without photo-initiator was neither cohesive nor adhesive after
1 minute UV curing. However, after 5 minutes UV curing sample 8D
produced an excellent coating, even if it did not stick to the
substrate. Comparing Examples 7 and 8 it hence appeared that gels
containing Tecogel 2000 were able to UV cure slowly in the absence
of added photo-initiators, but if photo-initiators) were added, it
was possible to increase the UV curing speed and to control the
adhesion of the gels to the substrate.
Example 9
Coatings Consisting of Polyox with and without Tecogel 2000 with
and without Unbound IRGACURE 2959
Preparation of Sample 9A: Unbound Irgacure 2959 in a Gel Consisting
of Polyox
[0272] 0.48 parts Irgacure 2959, 89.57 parts Polyox N-301, and 9.95
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A. The samples
contained 0.48% Irgacure 2959.
Preparation of Sample 9B: Gel Consisting of Polyox
[0273] 90 parts Polyox N-301 and 10 parts Polyox N-80 were
compounded in a Brabender mixer at 120.degree. C. for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A. The samples contained no
photo-initiator.
Preparation of Sample 9C: Unbound Irgacure 2959 in a Gel Consisting
of Polyox and Tecogel 2000
[0274] 0.48 parts Irgacure 2959, 53.74 parts Polyox N-301, 5.97
parts Polyox N-80, and 39.81 parts Tecogel 2000 were compounded in
a Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained 0.48% Irgacure 2959.
Preparation of Sample 9D: Gel Consisting of Polyox and Tecogel
2000
[0275] 54 parts Polyox N-301, 6 parts Polyox N-80, and 40 parts
Tecogel 2000 were compounded in a Brabender mixer at 120.degree. C.
for 10 minutes at atmospheric pressure, then for 2 minutes in
vacuum. The mixture was hot pressed, laminated and UV cured for 1
and 5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A. The samples
contained no photo-initiator.
Results and Discussion for Samples 9A-D
[0276] The results are shown here:
TABLE-US-00012 1 min. UV curing 5 min. UV curing Contains Gel
Adhesion to Gel Adhesion to Irgacure Contains cohesion substrate
cohesion substrate Sample 2959? Tecogel? (1-6) (1-4) (1-6) (1-4) 9A
Yes No 3 1 4.5 1 9B No No 1 1 1 1 9C Yes Yes 6 3 6 3 9D No Yes 2.5
3 2.5 3
[0277] In samples without Tecogel 2000 (9A-B) the presence of
Irgacure 2959 (9A) gave a cohesive gel after UV curing, whereas the
photo-initiator-free preparation 9B did not form any kind of
cohesive gel after 1 or 5 minutes UV curing. Hence Irgacure 2959
gave cohesion to the gel which, however, did not stick to the
substrate. With Tecogel 2000 in the samples (9C-D) all gels adhered
strongly to the substrate, but the gels in sample 9C with Irgacure
2959 were superior relative to the gels from the
photo-initiator-free preparation 9D.
[0278] In Example 8B Irgacure 2959 bound to PMDA in the presence of
MPEG 350 produced an excellent gel which did not, however, adhere
to the Estane 58212 substrate as sample 9C did, although the
amounts of photo-initiator in the two preparations were almost
identical. Hence the binding of Irgacure 2959 to PMDA and/or the
presence of MPEG 350 may have decreased the ability of Irgacure
2959 to abstract hydrogen from the polyurethane substrate,
resulting in poorer adhesion.
[0279] Samples 8D and 9D were also similar in the respect that both
recipes contained Tecogel 2000 but no photo-initiator. However, in
sample 8D a gel with excellent cohesion but no adhesion to the
substrate was formed after 5 minutes UV curing, whereas sample 9D
gave a very weak but adhesive gel after both 1 and 5 minutes. Hence
it seemed that the MPEG 350-PMDA ester present in sample 8D was
able to cross-link the gel with low efficiency but without binding
the gel to the substrate, whereas the hydrophilic Tecogel 2000
polyurethane in sample 9D only barely made the gel cohesive but did
manage to bind to the hydrophobic polyurethane substrate, possibly
through urethane-urethane hydrogen bond formation.
Example 10
Coatings Consisting of SMA-Bound Irgacure 2959 and Polyox with and
without Tecogel 2000
Synthesis of the Irgacure 2959 ester of SMA 1000
Compound 1
[0280] 1.124 g SMA 1000 (4.81 mmol anhydride based on an average
acid number of 480 mg KOH/g sample) and 1.373 g Irgacure 2959 (6.12
mmol) were dissolved in 12 g acetone. When 0.503 g
1-methylimidazole (6.13 mmol) was added as combined catalyst and
base, the solution turned yellow. The mixture was placed in an
airtight, pressure-resistant vial at 70.degree. C. The
disappearance of anhydride groups was followed between 1770 and
1860 cm.sup.-1 by FT-IR and indicated that the reaction was
essentially complete after 63 hours (data not shown). Upon cooling
the solution became unclear, and a little precipitate was observed.
The solution was acidified with HCl to pH 1-2, and the SMA 1000
acid ester of Irgacure 2959 was extracted with ethyl acetate. After
drying of the ethyl acetate phase and evaporation of the solvent a
viscous, yellowish oil remained. The compound was dissolved in
methanol, transferred to a tared Petri dish, put into a ventilated
heat cupboard and dried at 70.degree. C. for 80 min to a sticky,
yellow compound; this was Compound 1. No further work-up was done.
The yield was 2.00 g. The maximum theoretical amount of Irgacure
2959 in the polymer was 49 w/w-%. However, the maximum amount of
Irgacure 2959 present in the preparation was determined by UV-Vis
spectroscopy to be 22 w/w-%, on the assumption that the extinction
coefficients of free and bound Irgacure 2959 were identical. This
was an upper estimate, because no correction was made for a
possible background absorption at the wavelength of maximum
absorbance of Irgacure 2959 (274-5 nm in methanol and
1,3-dioxolane).
Preparation of Sample 10A: Irgacure 2959 Bound to SMA 1000 in a Gel
Consisting of Polyox
[0281] 0.91 parts Compound 1, 89.18 parts Polyox N-301, and 9.91
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. This mixture contained maximum 0.20% Irgacure
2959. The mixture was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A.
Synthesis of the Irgacure 2959 ester of SMA 2000
Compound 2
[0282] 1.428 g SMA 2000 (4.52 mmol anhydride based on an average
acid number of 355 mg KOH/g sample) and 1.151 g Irgacure 2959 (5.13
mmol) were dissolved in 12 g acetone. When 0.421 g
1-methylimidazole (5.13 mmol) was added, the solution turned
yellow. The mixture was placed in an airtight, pressure-resistant
vial at 70.degree. C. The disappearance of anhydride groups was
followed between 1770 and 1860 cm.sup.-1 by FT-IR, which indicated
that the reaction was 60-65% complete after 63 hours (data not
shown). Hence the reaction was slower than with SMA 1000. The
solution was acidified with HCl to pH 1-2, and the SMA 2000 acid
ester of Irgacure 2959 was filtered off, dissolved in acetone,
transferred to a tared Petri dish, put into a ventilated heat
cupboard and dried at 70.degree. C. for 170 min to a pale yellow,
mainly hard crystalline substance with a few softer areas; this was
Compound 2. No further work-up was done. The yield was 1.88 g. The
maximum theoretical amount of Irgacure 2959 in the polymer was 41.5
w/w-%. However, the maximum amount of Irgacure 2959 present in the
preparation was determined by UV-Vis spectroscopy to be 11
w/w-%.
Preparation of Sample 10B: Irgacure 2959 Bound to SMA 2000 in a Gel
Consisting of Polyox
[0283] 1.12 parts Compound 2, 88.99 parts Polyox N-301, and 9.89
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. This mixture contained 0.12% Irgacure 2959. The
mixture was hot pressed, laminated and UV cured for 1 and 5
minutes, as described for sample 7A. The samples were subjectively
evaluated as described for sample 7A.
Synthesis of the Irgacure 2959 ester of SMA 3000
Compound 3
[0284] 1.647 g SMA 3000 (4.18 mmol anhydride based on an average
acid number of 285 mg KOH/g sample) and 0.991 g Irgacure 2959 (4.42
mmol) were dissolved in 12 g acetone. When 0.363 g
1-methylimidazole (4.42 mmol) was added, the solution turned
yellow. The mixture was placed in an airtight, pressure-resistant
vial at 70.degree. C. The disappearance of anhydride groups was
followed between 1770 and 1860 cm.sup.-1 by FT-IR, which indicated
that the reaction was 60-65% complete after 63 hours (data not
shown). Hence the reaction was slower than with SMA 1000 but about
as fast as with SMA 2000. The solution was acidified with HCl to pH
1-2, and the SMA 3000 acid ester of Irgacure 2959 was extracted
with methyl isobutyl ketone. After drying of the methyl isobutyl
ketone phase and evaporation of the solvent a yellow substance
remained. The compound was dissolved in acetone, transferred to a
tared Petri dish, put into a ventilated heat cupboard and dried at
70.degree. C. overnight to a pale yellow, transparent, brittle
glass; this was Compound 3. No further work-up was done. The yield
was 2.22 g. The maximum theoretical amount of Irgacure 2959 in the
polymer was 36 w/w-%. However, the maximum amount of Irgacure 2959
present in the preparation was determined by UV-Vis spectroscopy to
be 25 w/w-%
Preparation of Sample 10C: Irgacure 2959 Bound to SMA 3000 in a Gel
Consisting of Polyox
[0285] 1.33 parts Compound 3, 88.80 parts Polyox N-301, and 9.87
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. This mixture contained maximum 0.33% Irgacure
2959. The mixture was hot pressed, laminated and UV cured for 1 and
5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A.
Preparation of Sample 10D: Irgacure 2959 Bound to SMA 1000 in a Gel
Consisting of Polyox and Tecogel 2000
[0286] 0.91 parts Compound 1, 53.51 parts Polyox N-301, 5.94 parts
Polyox N-80, and 39.64 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained maximum 0.20% Irgacure
2959.
Preparation of Sample 10E: Irgacure 2959 Bound to SMA 2000 in a Gel
Consisting of Polyox and Tecogel 2000
[0287] 1.12 parts Compound 2, 53.40 parts Polyox N-301, 5.93 parts
Polyox N-80, and 39.55 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained maximum 0.12% Irgacure
2959.
Preparation of Sample 10F: Irgacure 2959 Bound to SMA 3000 in a Gel
Consisting of Polyox and Tecogel 2000
[0288] 1.33 parts Compound 3, 53.28 parts Polyox N-301, 5.92 parts
Polyox N-80, and 39.47 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained maximum 0.33% Irgacure
2959.
Results and Discussion for Samples 10A-F
[0289] The results are shown here:
TABLE-US-00013 1 min. UV curing 5 min. UV curing Gel Adhesion to
Gel Adhesion to Contains cohesion substrate cohesion substrate
Sample SMA type Tecogel? (1-6) (1-4) (1-6) (1-4) 10A 1000 No 2 1
4.5 1 10B 2000 No 1 1 1 1 10C 3000 No 4.5 1 6 3 10D 1000 Yes 4.5 3
6 2 10E 2000 Yes 2 3 2 3 10F 3000 Yes 6 3 4.5 3
[0290] Within the samples with a pure Polyox coating (10A-C) as
well as within the samples with Tecogel 2000 added to the coating
(10D-F) the cohesion of the gels follows the same pattern: SMA 3000
(0.33% Irgacure 2959)>SMA 1000 (0.20% Irgacure 2959)>SMA 2000
(0.12% Irgacure 2959). This order follows the concentration of
Irgacure 2959 in the samples, whereas the order of the SMA polymers
seems to be random. Hence the concentration of Irgacure 2959 must
be at least 0.3% in order to achieve a good UV cross-linking of the
gels, whereas the effect of the SMA type appears to be smaller.
[0291] When sample 10C was UV cured for 5 minutes a superb gel
resulted which, in addition, adhered strongly to the substrate,
even though no Tecogel 2000 was present. This effect may be due to
the still relatively low concentration of Irgacure 2959 in sample
10C, which allows for better through curing, or the effect may be
due to an especially good compatibility of the SMA-bound Irgacure
2959 with both substrate and Polyox.
[0292] Sample 10F produced an excellent Tecogel-containing gel with
strong adhesion to the substrate after just 1 minute UV curing, but
so did samples 8A, 8C and 9C, so this was not a unique feature of
the SMA-bound Irgacure 2959.
Example 11
Coatings Consisting of Polyox and Irgacure 2959 Bound to Aliphatic,
Hydrophobic Polyurethanes
[0293] Compounds 4 and 5 were custom synthesized by Bomar
Specialties Co (Winsted, Conn.) and distributed in Europe by IGM
Resins (Waalwijk, the Netherlands). Compound 4 was an aliphatic,
trifunctional polyether urethane of medium molecular weight, which
was functionalised with Irgacure 2959 at all three ends. The
content of Irgacure 2959 in Compound 4 was 33.0 w/w-%, as indicated
by Bomar. Compound 5 was an aliphatic, linear polyether urethane of
medium molecular weight, which was functionalised with Irgacure
2959 at both ends. The content of Irgacure 2959 in Compound 5 was
15.5 w/w-%, as indicated by Bomar. Neither compound contained any
acrylate groups, as determined by FT-IR (data not shown).
Preparation of Sample 11A: 1% Compound 4 in a Gel Consisting of
Polyox
[0294] 1 part Compound 4, 89.1 parts Polyox N-301, and 9.9 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 0.33% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 11B: 5% Compound 4 in a Gel Consisting of
Polyox
[0295] 5 parts Compound 4, 85.5 parts Polyox N-301, and 9.5 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 1.65% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 11C: 10% Compound 4 in a Gel Consisting of
Polyox
[0296] 10 parts Compound 4, 81 parts Polyox N-301, and 9 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 3.30% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 11D: 1% Compound 5 in a Gel Consisting of
Polyox
[0297] 1 part Compound 5, 89.1 parts Polyox N-301, and 9.9 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 0.16% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 11E: 5% Compound 5 in a Gel Consisting of
Polyox
[0298] 5 parts Compound 5, 85.5 parts Polyox N-301, and 9.5 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 0.78% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 11F: 10% Compound 5 in a Gel Consisting of
Polyox
[0299] 10 parts Compound 5, 81 parts Polyox N-301, and 9 parts
Polyox N-80 were compounded in a Brabender mixer at 120.degree. C.
for 2 minutes at atmospheric pressure, then for 2 minutes in
vacuum. This mixture contained 1.55% Irgacure 2959. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Results and Discussion for Samples 11A-F
[0300] The results are shown here:
TABLE-US-00014 1 min. UV curing 5 min. UV curing Gel Adhesion to
Gel Adhesion to % Irgacure Compound cohesion substrate cohesion
substrate Sample 2959 number (1-6) (1-4) (1-6) (1-4) 11A 0.33 4 4 1
5 3 11B 1.65 4 5 1 5 3 11C 3.30 4 5 1 5 3 11D 0.16 5 2 1 2 1 11E
0.78 5 5 1 5 1 11F 1.55 5 5 1 5 1
[0301] Samples 11A-C produced strong gels that adhered well to the
substrate after 5 minutes UV curing. Samples 11E-F also produced
strong gels after 5 minutes UV curing, but these gels did not
adhere to the substrate. These experiments clearly demonstrated
that the geometry of the photoactive polymer was more important for
the adhesion to the substrate than the sheer concentration of
photo-initiating groups in the gel. That is, the trifunctional
photoactive polyurethane Compound 4 adhered strongly to the
substrate polymer whereas the difunctional Compound 5 did not. It
also appeared that 0.16% Irgacure 2959 in the gel was not enough to
induce efficient cross-linking of the gel, even after 5 minutes UV
curing (sample 11D), as this result was also found for sample
10B.
Example 12
Coatings Consisting of Polyox with and without Tecogel 2000 with
BTDA-Jeffamine Condensation Polymers as Photo-Initiator
Synthesis of BTDA-Jeffamine D-230 Condensation Polymer
Compound 6
[0302] 1.77 g 97% BTDA (5.33 mmol) was dissolved in 12 g DMSO by
magnetic stirring and heating to 60.degree. C. 1.23 g Jeffamine
D-230 (5.35 mmol) was added with perceptible heat evolution. FT-IR
recorded within minutes after mixing indicated that the reaction
between the dianhydride and the diamine was instantaneous; see FIG.
8.
[0303] The solution was acidified with HCl to pH 1-2, and the
BTDA-Jeffamine D-230 condensation polymer was extracted with
dichloromethane. The dichloromethane phase was dried and the
dichloromethane evaporated; this was Compound 6. The compound
contained maximum 11.4% BTDA, but this could not be verified by
UV-Vis spectroscopy because of a large background absorption at the
maximum absorption of BTDA (257 nm in ethanol).
Preparation of Sample 12A: BTDA/Jeffamine D-230 Condensation
Polymer as Photo-Initiator in a Gel Consisting of Polyox
[0304] 1.73 parts Compound 6, 88.44 parts Polyox N-301, and 9.83
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A. The samples
contained maximum 0.20% BTDA.
Preparation of Sample 12B: BTDA/Jeffamine D-230 Condensation
Polymer as Photo-Initiator in a Gel Consisting of Polyox and
Tecogel 2000
[0305] 1.73 parts Compound 6, 53.06 parts Polyox N-301, 5.90 parts
Polyox N-80, and 39.31 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A. The samples contained maximum 0.20 BTDA.
Results and Discussion for Samples 12A-B
[0306] The results are shown here:
TABLE-US-00015 1 min. UV curing 5 min. UV curing Gel Adhesion to
Gel Adhesion to Contains cohesion substrate cohesion substrate
Sample Tecogel? (1-6) (1-4) (1-6) (1-4) 12A No 3 1 4 1 12B Yes 4 3
5 3
[0307] A relatively strong gel was formed from samples 12A-B after
1 minute UV curing in spite of the low concentration of
photo-initiator used, but the gel strength at 5 minutes UV curing
was better. The Tecogel 2000-containing gel 12B was slightly
stronger than the pure Polyox gel of sample 12A. Furthermore, the
gel of sample 12B adhered strongly to the substrate, whereas the
gel of sample 12A did not. In this respect sample 12B was similar
to many of the other Tecogel 2000-containing samples with
photo-initiator, which also adhered well to the substrate.
Example 13
Coatings Consisting of Polyox with and without Tecogel 2000 with
Benzophenone Bound to Boltorn or Joncryl Polyols as
Photo-Initiator
Synthesis of 4-benzoylbenzoyl chloride
[0308] 5.00 g 4-benzoylbenzoic acid (22.1 mmol), 10.0 mL thionyl
chloride (16.31 g, 137 mmol) and one drop of DMF in a 100 mL
round-bottom flask was refluxed for 75 minutes in an oil bath kept
at 100.degree. C. The stream of gaseous SO.sub.2 and HCl, that was
formed during the reaction, was directed via rubber tubing and a
glass pipette onto the surface of a vigorously stirred 1 M NaOH
solution, where most of the gas was absorbed and transformed to
sulphite and chloride. Care was taken not to let the tip of the
glass pipette touch the surface of the sodium hydroxide solution
because of the risk of back suction of sodium hydroxide into the
system.
[0309] After 75 minutes reflux the oil bath was removed, and the
reaction mixture was cooled to room temperature. The condenser was
removed and the setup rearranged, so a piece of rubber tubing from
the round-bottom flask was directed to the entrance of a membrane
pump, and the exit from the membrane pump was directed via rubber
tubing and a glass pipette towards the stirred 1 M NaOH solution.
The glass pipette should be at a larger distance from the NaOH
solution than during the first part of the experiment, because the
air flow through the pump was much larger than the spontaneous flow
of gaseous SO.sub.2 and HCl from the first part of the experiment.
Then suction was applied and the unreacted SOCl.sub.2 removed,
first for 10 minutes at room temperature and later with gentle
heating of the reaction mixture in the still warm oil bath for
another 10 minutes. The flask with the pale, yellow, solid
4-benzoylbenzoyl chloride was stoppered until it was used in the
next step of the synthesis. The membrane pump was flushed free of
residual SOCl.sub.2 by direct suction of 500 mL of deionized water
through the pump and into one of two small holes in the lid of a
plastic bucket in a fume hood.
Synthesis of the Boltorn H-20 ester of 4-benzoylbenzoic acid
Compound 7
[0310] 2.43 g Boltorn H-20 (22.1 mmol OH based on an average
OH-number of 510 mg KOH/g sample) was dissolved in 50 mL pyridine
(48.9 g; 0.618 mol) in a 250 mL round-bottom flask with a directly
attached distillation head. The mixture was dried by distillation
by means of a heating mantle with magnetic stirrer, since water
forms a low boiling azeotrope with pyridine (azeotrope by
93.6.degree. C.; azeotrope contains 75.5 mol-% water). As soon as
the water was removed, the distillation temperature increased to
the boiling point of pure pyridine, i.e. 115.3.degree. C.; from
this point an additional 4-5 mL pyridine/water was collected in a
measuring cylinder through a small funnel.
[0311] A 100 mL dropping funnel, which had been dried in a heat
cupboard at 130.degree. C., was placed on the 100 mL round-bottom
flask containing 4-benzoylbenzoyl chloride (see above). The warm,
dried solution of Boltorn H-20 was transferred to the dropping
funnel, and a nitrogen bubbler was attached to exclude moisture.
10-15 mL of the Boltorn solution was added at such a rate that only
a small amount of gaseous HCl was formed above the liquid; this
should re-enable magnetic stirring in the flask. The rest of the
solution was added at such a rate that the temperature of the
outside of the flask did not exceed about 40.degree. C., as judged
by the bare hand (no external cooling or heating was applied). The
reaction mixture became brown. If necessary, the solution was
cooled in an ice bath. Towards the end of Boltorn addition the
reaction mixture became thicker because of the precipitation of
apparently light brown pyridinium chloride. After about an hour the
heat evolution had stopped, and the reaction mixture had reverted
to room temperature as a sign that the reaction was complete.
[0312] Excess concentrated HCl was added to protonate all pyridine
to make it water soluble, and the Boltorn ester was extracted from
the aqueous phase into 3.times.50 mL CH.sub.2Cl.sub.2. The organic
extract was dried overnight with MgSO.sub.4 and the
CH.sub.2Cl.sub.2 evaporated. The Boltorn H-20 ester of
4-benzoylbenzoic acid was a light tan, hard solid. This was
Compound 7.
Preparation of Sample 13A: Boltorn H-20 Ester of 4-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox
[0313] 1.45 parts Compound 7, 88.695 parts Polyox N-301, and 9.855
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A.
Synthesis of the Boltorn H-30 ester of 4-benzoylbenzoic acid
Compound 8
[0314] 2.48 g Boltorn H-30 (22.1 mmol OH based on an average
OH-number of 500 mg KOH/g sample) was dissolved in 50 mL pyridine
(48.9 g; 0.618 mol), dried and made to react with 4-benzoylbenzoyl
chloride produced from 5.00 g 4-benzoylbenzoic acid, as described
in the synthesis of the Boltorn H-20 ester of 4-benzoylbenzoic acid
(Compound 7). The Boltorn H-30 ester of 4-benzoylbenzoic acid was a
light tan wax. This was Compound 8.
Preparation of Sample 13B: Boltorn H-30 Ester of 4-benzoylbenzoic
Acid as Photo-initiator in a Gel Consisting of Polyox
[0315] 1.46 parts Compound 8, 88.69 parts Polyox N-301, and 9.85
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A.
Synthesis of 2-benzoylbenzoyl chloride
Batch #1 (Abbreviated "2-BBCl-1")
[0316] The synthesis of 2-BBCl-1 was carried out like the synthesis
of 4-benzoylbenzoyl chloride (see above). However, 2-BBCl-1 was a
yellow oil and not a solid like 4-benzoylbenzoyl chloride.
Synthesis of the Boltorn H-20 ester of 2-benzoylbenzoic acid
Compound 9
[0317] 2.43 g Boltorn H-20 (22.1 mmol OH based on an average
OH-number of 510 mg KOH/g sample) was dissolved in 50 mL pyridine
(48.9 g; 0.618 mol), dried and made to react with 2-BBCl-1 produced
from 5.00 g 2-benzoylbenzoic acid as described above. The Boltorn
H-20 ester of 2-benzoylbenzoic acid was a light tan, hard solid.
This was Compound 9.
Preparation of Sample 13C: Boltorn H-20 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox
[0318] 1.45 parts Compound 9, 88.695 parts Polyox N-301, and 9.855
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A.
Synthesis of the Boltorn H-30 ester of 2-benzoylbenzoic acid
Compound 10
[0319] 2.48 g Boltorn H-30 (22.1 mmol OH based on an average
OH-number of 500 mg KOH/g sample) was dissolved in 50 mL pyridine
(48.9 g; 0.618 mol), dried and made to react with 2-BBCl-1 produced
from 5.00 g 2-benzoylbenzoic acid as described above. The Boltorn
H-30 ester of 2-benzoylbenzoic acid was a light tan, hard solid.
This was Compound 10.
Preparation of Sample 13D: Boltorn H-30 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox
[0320] 1.46 parts Compound 10, 88.69 parts Polyox N-301, and 9.85
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A.
Synthesis of the Joncryl 804 ester of 2-benzoylbenzoic acid
Compound 11
[0321] 10.15 g Joncryl 804 (7.96 mmol OH based on an average
OH-number of 44 mg KOH/g sample) was dissolved in 75 mL pyridine
(73.35 g; 0.927 mol), dried and made to react with 2-BBCl-1
produced from 1.80 g 2-benzoylbenzoic acid (7.96 mmol) which was
made as described above, however only with 3.6 mL thionyl chloride
instead of 10.0 mL. The synthesis of the Joncryl 804 ester of
2-benzoylbenzoic acid was like the synthesis of the Boltorn H-20
ester of 4-benzoylbenzoic acid (Compound 7). The Joncryl 804 ester
of 2-benzoylbenzoic acid was an almost transparent wax. This was
Compound 11.
Preparation of Sample 13E: Joncryl 804 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox
[0322] 6.45 parts Compound 11, 84.19 parts Polyox N-301, and 9.36
parts Polyox N-80 were compounded in a Brabender mixer at
120.degree. C. for 2 minutes at atmospheric pressure, then for 2
minutes in vacuum. The mixture was hot pressed, laminated and UV
cured for 1 and 5 minutes, as described for sample 7A. The samples
were subjectively evaluated as described for sample 7A.
Preparation of Sample 13F: 2-benzoylbenzoic Acid not Bound to
Boltorn H-20 in a Gel Consisting of Polyox
[0323] 0.24 parts 2-benzoylbenzoic acid, 1.21 parts Boltorn H-20,
88.695 parts Polyox N-301, and 9.855 parts Polyox N-80 were
compounded in a Brabender mixer at 120.degree. C. for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 13G: 2-Benzoylbenzoic Acid not Bound to
Joncryl 804 in a Gel Consisting of Polyox
[0324] 1.00 part 2-benzoylbenzoic acid, 5.45 parts Joncryl 804,
84.19 parts Polyox N-301, and 9.36 parts Polyox N-80 were
compounded in a Brabender mixer at 120.degree. C. for 2 minutes at
atmospheric pressure, then for 2 minutes in vacuum. The mixture was
hot pressed, laminated and UV cured for 1 and 5 minutes, as
described for sample 7A. The samples were subjectively evaluated as
described for sample 7A.
Preparation of Sample 13H: Boltorn H-20 Ester of 4-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox and Tecogel
2000
[0325] 1.45 parts Compound 7, 53.22 parts Polyox N-301, 5.91 parts
Polyox N-80, and 39.42 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A.
Preparation of Sample 13I: Boltorn H-30 Ester of 4-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox and Tecogel
2000
[0326] 1.46 parts Compound 8, 53.21 parts Polyox N-301, 5.91 parts
Polyox N-80, and 39.42 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A.
Preparation of Sample 13J: Boltorn H-20 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox and Tecogel
2000
[0327] 1.45 parts Compound 9, 53.22 parts Polyox N-301, 5.91 parts
Polyox N-80, and 39.42 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A.
Preparation of Sample 13K: Boltorn H-30 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox and Tecogel
2000
[0328] 1.46 parts Compound 10, 53.21 parts Polyox N-301, 5.91 parts
Polyox N-80, and 39.42 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A.
Preparation of Sample 13L: Joncryl 804 Ester of 2-benzoylbenzoic
Acid as Photo-Initiator in a Gel Consisting of Polyox and Tecogel
2000
[0329] 6.45 parts Compound 11, 50.52 parts Polyox N-301, 5.61 parts
Polyox N-80, and 37.42 parts Tecogel 2000 were compounded in a
Brabender mixer at 120.degree. C. for 10 minutes at atmospheric
pressure, then for 2 minutes in vacuum. The mixture was hot
pressed, laminated and UV cured for 1 and 5 minutes, as described
for sample 7A. The samples were subjectively evaluated as described
for sample 7A.
Preparation of Sample 13M: 4-Benzoylbenzoic Acid not Bound to
Boltorn H-30 in a Gel Consisting of Polyox and Tecogel 2000
[0330] 0.24 parts 4-benzoylbenzoic acid, 1.21 parts Boltorn H-30,
53.22 parts Polyox N-301, 5.91 parts Polyox N-80, and 39.42 parts
Tecogel 2000 were compounded in a Brabender mixer at 120.degree. C.
for 10 minutes at atmospheric pressure, then for 2 minutes in
vacuum. The mixture was hot pressed, laminated and UV cured for 1
and 5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A.
Preparation of Sample 13N: 2-Benzoylbenzoic Acid not Bound to
Joncryl 804 in a Gel Consisting of Polyox and Tecogel 2000
[0331] 1.00 part 2-benzoylbenzoic acid, 5.45 parts Joncryl 804,
50.52 parts Polyox N-301, 5.61 parts Polyox N-80, and 37.42 parts
Tecogel 2000 were compounded in a Brabender mixer at 120.degree. C.
for 10 minutes at atmospheric pressure, then for 2 minutes in
vacuum. The mixture was hot pressed, laminated and UV cured for 1
and 5 minutes, as described for sample 7A. The samples were
subjectively evaluated as described for sample 7A.
Results and Discussion for Samples 13A-N
[0332] The results are shown here:
TABLE-US-00016 1 min. UV curing 5 min. UV curing Photo- PI Cohesion
Adhesion Cohesion Adhesion Sample initiator? bound? Polymer?
Tecogel? (1-6) (1-4) (1-6) (1-4) 13A 4-BBA Yes H-20 No 5.5 1 5.5 3
13B 4-BBA Yes H-30 No 4 1 4.5 4 13C 2-BBA Yes H-20 No 6 1 6 1 13D
2-BBA Yes H-30 No 6 1 6 1 13E 2-BBA Yes J804 No 6 1 6 1 13F 2-BBA
No H-20 No 1 1 6 1 13G 2-BBA No J804 No 6 1 6 2 13H 4-BBA Yes H-20
Yes 5.5 3 5 4 13I 4-BBA Yes H-30 Yes 4 3 6 3 13J 2-BBA Yes H-20 Yes
6 1 6 1 13K 2-BBA Yes H-30 Yes 6 3 6 3 13L 2-BBA Yes J804 Yes 6 3 6
3 13M 4-BBA No H-30 Yes 5.5 3 5.5 3 13N 2-BBA No J804 Yes 6 1 6 4
4-BBA: 4-Benzoylbenzoic acid. 2-BBA: 2-Benzoylbenzoic acid. PI:
Photo-initiator. H-20: Boltorn H-20. H-30: Boltorn H-30. J804:
Joncryl 804.
[0333] Comparing the samples 13A-E, which all had bound
photo-initiators, it was clear that only 4-BBA (13A-B) could secure
good adhesion of the coating to the substrate after 5 minutes UV
curing of a Polyox-coating without Tecogel 2000, whereas 2-BBA
could not (13C-D). On the other hand 2-BBA formed stronger Polyox
gels than 4-BBA. Sample 13F with unbound 2-BBA and H-20 did not
form a strong gel after 1 minute UV curing, as opposed to all other
photo-initiator combinations in pure Polyox; apparently H-20 worked
best with the photo-initiator bound to it. Joncryl 804 made very
strong gels with both bound and unbound 2-BBA but could not stick
to the substrate.
[0334] In the gels with Tecogel 2000 there was again a clear
tendency that bound or unbound 2-BBA formed stronger gels than
bound or unbound 4-BBA (compare samples 13H-N). As opposed to the
pure Polyox gels, however, with Tecogel 2000 present all bound
photo-initiators gave strong adhesion to the polyurethane substrate
after just 1 minute UV curing; except for 2-BBA with H-20 (sample
13J), which failed entirely to give an adhesive coating, just as
when no Tecogel was present (sample 13C). Apparently the overall
performance of photo-initiators derived from Boltorn H-20 was
slightly lower than those derived from Boltorn H-30. The unbound
2-BBA with Joncryl 804 (sample 13N) only managed to bind tightly to
the substrate after 5 minutes UV curing, whereas the corresponding
bound photo-initiator (sample 13L) made the gel bind strongly to
the substrate after just 1 minute UV curing.
Example 14
Model Coatings Consisting of Polyox and/or a Thermoplastic Matrix
Polymer with Covalently Bound Photo-Initiator
Synthesis of Benzoyloxylated Polyox WSR N-80 in Benzene
[0335] 2.00 g Polyox WSR N-80, 2.2 mg CuCl, and 200 mL benzene were
placed in a three-necked 500 mL round-bottomed flask with a
condenser, a dropping funnel and a stopper and purged with N.sub.2,
leaving the flask under a N.sub.2 blanket. 885 .mu.L tert-butyl
peroxybenzoate in 24 mL benzene was added drop-wise from the
dropping funnel during vigorous magnetic stirring. During the
addition the solution acquired a bluish colour.
[0336] After 72 hours the bluish colour had almost vanished. 2.4 mL
2 M Na.sub.2CO.sub.3 was added during stirring, a distillation head
was attached, and the water was removed azeotropically. Some
frothing was observed when about 5 mL benzene-water mixture had
distilled, but nothing dramatic. A total of 55 mL liquid was
distilled to make sure all water had gone. The solution was cooled,
the salts filtered off, transferred the filtrate to a 500 mL
beaker, and added 100 mL pentane. The yellow, rubbery product
precipitated out on the walls and bottom of the beaker and was
scraped off with a glass spatula, then dried. Yield: 2.17 g. A
strong IR peak at 1724 cm.sup.-1 confirmed the presence of ester
groups in the compound.
Reference Synthesis of Benzoyloxylated Polyox WSR N-80 in Methyl
Isobutyl Ketone/Acetic Acid
[0337] 10.0 g Polyox WSR N-80 (227 mmol ether linkages), 2.0 mg
CuCl (MW=99.00 g/mol; 20 .mu.mol), 475 mL MIBK (bp 117-8.degree.
C.) and 25 mL acetic acid (bp 117-8.degree. C.) were placed in a 1
L three-necked flask with a condenser, a dropping funnel and a
stopper. Acetic acid was added to increase the solubility of copper
salts (see J. K. Kochi, A. Bemis (1968): "Catalytic reactions of
peroxides, direct initiation by cuprous species", Tetrahedron, 24,
5099-5113).
[0338] The flask was flushed with N.sub.2 and then heated to reflux
under a N.sub.2 blanket. 4 mL tert-butyl peroxybenzoate (density
1.034 g/mL; MW=194.23 g/mol; 21 mmol) was added drop-wise over
10-15 min. The addition of the peroxyester was accompanied by a
colour change from yellowish to greenish because of the oxidation
of Cu(I) to Cu(II). The progress of the reaction was followed by
monitoring the disappearance of the peroxyester peak at 1756
cm.sup.-1 by IR spectroscopy. After 19 hours the peroxyester peak
had almost disappeared, and the greenish colour had changed back to
yellow, as a further sign that all copper had been reduced to Cu(I)
and no more peroxyester was present to oxidize it to Cu(II) (see D.
J. Rawlinson, G. Sosnovsky (1972): "One-Step Substitutive
Acyloxylation at Carbon. Part I. Reactions Involving Peroxides",
Synthesis, International Journal of Methods in Synthetic Organic
Chemistry, 1, 1-28).
[0339] The reaction mixture was poured into a 1 L beaker and slowly
cooled in air to well below the melting point of Polyox
(62-65.degree. C.) and then in ice water, taking advantage of the
fact that Polyox is much more soluble in boiling MIBK than in cold
MIBK. The heavy, white, crystalline precipitate was filtered on a
Buchner funnel, washed once with 50 mL cold 19:1 MIBK:acetic acid
(v/v) to remove copper salts, two times with diethyl ether, and
then dried. Yield: 6.17 g. IR spectroscopy revealed a small
carbonyl peak at 1737 cm.sup.-1, so basically the reaction did not
give the desired product. Hence the reaction conditions must be
carefully selected and optimized.
Synthesis of 2-benzoylbenzoyl chloride
Batch 2 (abbreviated "2-BBCl-2")
[0340] 74.8 g 4-benzoylbenzoic acid (331 mmol) and 150 mL thionyl
chloride (245 g, 2.06 mol) were placed in a 500 mL round-bottomed
flask fitted with a condenser and, on top of the condenser, tubing
to lead gaseous HCl and SO.sub.2 to above the surface of a
vigorously stirred NaOH solution, where most of the gas was
absorbed and transformed to sulphite and chloride. The NaOH
solution contained more than 8.5 mol NaOH, i.e. more than the
stoichiometric amount needed to neutralize 2.06 mol SOCl.sub.2
according to:
SOCl.sub.2+4HO.sup.-.fwdarw.SO.sub.3.sup.2-+2Cl.sup.-+2H.sub.2O.
[0341] 10 drops of DMF were added to the reaction mixture, and heat
was applied for 60 minutes to keep the mixture refluxing. The
heating was removed and the reaction mixture cooled to room
temperature. The condenser was removed and the setup rearranged, so
a piece of rubber tubing from the round-bottomed flask was directed
to the entrance of a membrane pump, and the exit from the membrane
pump was directed via rubber tubing towards the stirred NaOH
solution. The tubing should be at a larger distance from the NaOH
solution than during the first part of the experiment, because the
air flow through the pump was much larger than the spontaneous flow
of gaseous SO.sub.2 and HCl from the first part of the experiment.
Then suction was applied and the unreacted SOCl.sub.2 was removed
by heating to 80.degree. C. in vacuo for several days. The product
(2-BBCl-2; MW=244.68 g/mol) was a yellow liquid, probably
containing both the photochemically active 2-benzoylbenzoylchloride
and the photochemically inactive pseudo-acid chloride (see M. S.
Newman, C. Courduvelis (1966): "Reactions Proceeding by the [3.2.1]
Bicyclic Path", J. Am. Chem. Soc., 88(4), 781-4):
[0342] Yield: 83.58 g (342 mmol, 103%, the surplus probably being
unremoved SOCl.sub.2). The membrane pump was flushed free of
residual SOCl.sub.2 by direct suction of several liters of
deionized water through the pump and into one of two small holes in
the lid of a plastic bucket in a fume hood. The pump was then
flushed with ethanol and dried.
Synthesis of Polyox WSR N-80 End-Functionalized with 2-BBCl-2
[0343] 1.51 g Polyox WSR N-80 (7.55 .mu.mol) was added to 165 mL
benzene, heated to near the boiling point to effect dissolution,
and cooled to room temperature again. 375 .mu.L 2-BBCl-2 (>375
mg; MW=244.68 g/mol; >1.5 mmol, i.e. a large stoichiometric
excess) was added at once during magnetic stirring. After an hour 3
mL 2 M Na.sub.2CO.sub.3 (6 mmol) was added in order to extract
residual 2-benzoylbenzoyl chloride, 2-benzoylbenzoic acid and other
acidic impurities. A major part of the Polyox precipitated out in
spite of the presence of the superior solvent benzene, and the
benzene phase became milky, so water was distilled off
azeotropically at about 69.degree. C. in order to precipitate salts
and force modified Polyox back into solution. During this phase
frothing occurred, which was excessive and uncontrollable in case
of Polyox concentrations in benzene over 1 w/v-% but controllable
at 1% and below. When all water was removed (after 25-30 mL
distillate) the temperature at the top of the distillation head
increased to 78-9.degree. C. The resulting clear benzene solution
was cooled, the salts were filtered off, and the solution was
evaporated to near dryness. Yield: 1.7 g.
[0344] The UV-Vis spectrum of 5 g/L of the compound in benzene
showed an absorbance of 0.6 at the global maximum at 322 nm. This
corresponded to a theoretical absorbance of 51 at the global
benzophenone maximum at about 252 nm, since the ratio between the
extinction coefficients at 255 and 322 nm is 86 for benzophenone in
ethanol (data not shown). However, unfortunately the 252 nm peak
could not be observed in benzene, which has very strong absorption
below 300 nm. Hence benzene was not an ideal solvent for the UV-Vis
measurements but was chosen anyway because of its superior
solvation of Polyox, PEG 35000 and Tecogel 2000. Instead the local
maximum at 322 nm, which is also exhibited by benzophenone, was
used to calculate the approximate concentration of benzophenone
groups.
[0345] The absorbance of the Polyox 2-BBCl-2 ester corresponded to
a benzophenone content of about 19% by weight of the polymer. This
was very unrealistic and indicated that a contamination of some
benzophenone derivative was present, but because of lack of time it
was decided to treat the compound as if it had this concentration
of photo-initiator anyway.
[0346] Interestingly, 2-benzoylbenzoic acid could not be used as a
reference, because it had only a very small absorbance at 322 nm
which, furthermore, did not obey Lambert-Beer's law at increasing
concentrations; this possibly indicated a concentration dependent
dimer formation including the acid hydroxyl group in the very
non-polar benzene, since the effect was absent in the synthesized
Polyox 2-benzoylbenzoate.
Synthesis of PEG 35000 End-Functionalized with 2-BBCl-2
[0347] 35.0 g Polyglykol Hoechst 35000 Schuppen (batch E06389543)
and 200 mL benzene were mixed in a 500 mL round-bottomed flask and
heated until everything was dissolved. The rather viscous solution
was cooled to room temperature, and 5 mL 2-BBCl-2 was added in
small portions during vigorous stirring. After an hour the mixture
was transferred to a beaker, rinsing the flask with a little
benzene. The modified PEG 35000 was precipitated by addition of 100
mL pentane. The compound was filtered off, washed several times
with pentane and dried. Yield: 35.3 g.
[0348] The UV-Vis spectrum of 2.55 g/L compound in benzene had an
absorbance of 0.035 at 322 nm, corresponding to A=3 at 252 nm and a
concentration of 2.2% benzophenone by weight of the polymer. This
was unrealistic but because of lack of time it was decided to treat
the compound as if it had this concentration of photo-initiator
anyway, as also described above for WSR N-80 end-functionalized
with 2-BBCl-2.
Synthesis of Tecogel 2000 End-Functionalized with 2-BBCl-2
[0349] 10.0 g Tecogel 2000 was added to 400 mL hot benzene during
vigorous stirring. The solution contained some cross-linked,
insoluble material (as is sometimes the case), which was filtered
off using a metal sieve with 212 .mu.m hole size. 250 .mu.L
2-BBCl-2 was added at once during stirring at room temperature.
After an hour the solution was transferred to a beaker, and 200 mL
hexane was added during vigorous magnetic stirring and stirring by
hand, since the voluminous precipitate was so hard that it
prevented proper mixture of benzene and hexane by magnetic stirring
alone. The compound formed a hard cylinder on the Buchner funnel
and was filtered off. The compound was dried at 80.degree. C. for a
day, during which time it formed a porous ball, probably because of
the internal pressure from the evaporating solvents. Yield: 10.3 g.
The material was extremely tough and had to be divided using a
strong knife and a butcher's metal glove! The UV-Vis spectrum in
benzene was very similar to the control, which had not been
subjected to 2-BBCl-2, and showed no sign at 322 nm of any attached
benzophenone groups.
Production of Samples for Solvent Casting and Compounding
[0350] Based on the UV-Vis data mentioned above, the following set
of samples (labelled 17-26) were made so that the maximum
absorbance at 252 nm should not exceed 0.6, which would mean good
through cure:
TABLE-US-00017 Percentage composition (w/w-%) Thermoplastic matrix
polymer Hydrophilic polymers Photo- TG 2000 TG-P (w. PO-P (w. PEG-P
(w. initiator Solution CD 53 RA photo- Polyox photo- PEG photo-
Benzo- No. * 015 initiator) WSR N-80 initiator) 35000 initiator)
phenone Type 17 1 1 2.983 0.017 0 0 0 A 18 0 2 3 0 0 0 0 B 19 2 0
2.966 0.034 0 0 0 C 20 2 0 3 0 0 0 0.0065 D 21 2 0 3 0 0 0 0 E 22 1
1 0 0 2.855 0.1455 0 A 23 0 2 0 0 3 0 0 B 24 2 0 0 0 2.709 0.291 0
C 25 2 0 0 0 3 0 0.0065 D 26 2 0 0 0 3 0 0 E A. Double positive:
Half amount of photo-initiator on matrix polymer and half on
hydrophilic polymer B. Positive #1: Photo-initiator bound to
thermoplastic matrix polymer C. Positive #2: Photo-initiator bound
to hydrophilic polymer D. Positive #3: Unbound photo-initiator
added E. Negative: No photo-initiator added * In each instance,
0.01 w/w-% of triethanolamine was added and 23.75 w/w-% water and
71.24 w/w-% of 2-propanol were used as the solvent system, the
constituents thereby adding up to 100 w/w-%.
[0351] In some cases triethanolamine may act as an auxiliary
electron donor for benzophenone and hence increase the cure speed.
In order to ascertain whether it was necessary to add the amine
here, sample 25 was compounded with and without 0.01%
triethanolamine present, respectively, and UV cured at 10 or 40
m/min, respectively. At 10 m/min the coating was stable regardless
of whether the amine was present or not, but at 40 m/min (with much
less light) the coating without amine was completely unstable,
whereas the coating with amine was stable. Hence triethanolamine
was added to all samples.
[0352] Tecogel 2000 and TG-.beta. (Tecogel 2000 modified with
photo-initiator) were actually refluxed in the 3:1 2-propanol:water
solvent (w:w) to form stock solutions, because of their otherwise
very slow dissolution. All solutions contained 5% dry matter. 4 g
of each solution was spread out across a circular sheet (area 20
cm.sup.2) of the polyurethane substrate Estane 58212, which was
glued to the bottom of a slightly conical aluminium container. The
containers were then heated overnight at 60.degree. C. in order to
evaporate the solvent and leave a dry, homogeneous coating of about
100 .mu.m thickness. The coatings were heated to about 65.degree.
C. (where they became transparent) and UV cured under a Fusion LH6
500 W/inch Hg lamp at a speed of 40 m/min. They were swelled in
60.degree. C. hot tap-water for at least 5 minutes. Then the
stability of the coatings was subjectively evaluated by continuous
finger rubbing under running water on the following scale. The
following results were obtained:
TABLE-US-00018 Solution Score of UV cured preparation 17 1 18 1 19
2 20 2 21 2 22 2 23 2 24 2 25 2 26 2
[0353] No clear conclusion could be drawn from the results obtained
in this example although a tendency towards a preference for the
variants with photo-initiator linked to one or both of the
thermoplastic matrix polymer and the hydrophilic polymer was
observed. It is envisaged that further optimisation of the relative
ratios of the constituents and the loading of the photo-initiator
will support this hypothesis.
Projected Synthesis 1: 2-Benzoylbenzoyloxylation of Polyox WSR
N-80
[0354] tert-Butyl 2-benzoylperoxybenzoate may be synthesized as
described by L. Thijs, S. N. Gupta, D. C. Neckers (1979):
"Photochemistry of Perester Initiators", J. Org. Chem., 44(23),
4123-8, or by adding 2-benzoylbenzoyl chloride slowly to tert-butyl
hydroperoxide in pyridine solvent; adding diethyl ether (or toluene
or ethyl acetate); acidifying to extract pyridine; washing the
ether phase with aqueous carbonate or bicarbonate to remove
residual SOCl.sub.2, SO.sub.2, HCl, 2-benzoylbenzoyl chloride and
2-benzoylbenzoic acid; drying the organic phase; and removing the
solvent.
[0355] The resulting tert-butyl 2-benzoylperoxybenzoate may then be
made to react with Polyox WSR N-80 in benzene and purified in the
same manner as described for the synthesis of benzoyloxylated
Polyox WSR N-80 in benzene. To the knowledge of the inventors no
literature describes this reaction being applied to a polyether
like Polyox.
Projected Synthesis 2:
[0356] It has been described in the literature that when some small
benzoyloxylated ethers (e.g. tetrahydrofuran, see G. Sosnovsky,
S.-O. Lawesson (1964): "The Peroxyester Reaction", Angew. Chem.
Int. Edit., 3(4), 269-76; or dibutyl ether, see S.-O. Lawesson, C.
Berglund (1961): "Studies on peroxy compounds. XVIII. The
preparation of aldehydes and ketones from ethers", Arkiv for Kemi,
17(45), 465-73) are boiled with an excess of alcohol (e.g. Irgacure
2959), benzoic acid is eliminated to give an unsaturated ether
which can then add the alcohol to give the acetal:
##STR00022##
[0357] The reaction in this scheme may be performed in a range of
inert solvents with high boiling points, e.g. ketones (such as MIBK
or cyclohexanone), amides (such as DMF, DMAC, or NMP), DMSO, or the
like.
Reference Example 1
TABLE-US-00019 [0358] Compound Compound Compound Compound
Ingredients A B C D Tecogel 2000 75% 50% 75% 50% PVP K25 12.5% 25%
PVP K90 12.5% 25% PEG 400 12.5% 25% 12.5% 25%
[0359] The ingredients were hot melt compounded in a Brabender
compounder. PVP K25 and PVP K90 were from ISP Corp. In order to
make the PVP processable and thermoplastic at 120.degree. C. it was
plasticized with PEG 400 prior to compounding. No photo-initiators
were added. The blends were hot press laminated onto flat
substrates of Tecogel 500. The adhesion and friction were evaluated
after swelling in water for at least 24 hours on the scale defined
in Example 1.
TABLE-US-00020 Adhesion after 24 hours Friction after 24 hours
Compound A 3 High friction - Rough surface Compound B 1 High
friction - Very rough surface Compound C 3 High friction - Rough
surface Compound D 2 High friction - Rough surface
[0360] With 25% of 1:1 PVP:PEG 400 in 75% Tecogel 2000 it was
possible to get good adhesion to Tecogel 500. If the content of 1:1
PVP:PEG400 was increased to 50%, delaminating and severe blistering
was observed. The friction of all four blends had increased after
24 hours compared to the friction after 5 minutes.
Reference Example 2
TABLE-US-00021 [0361] Ingredients Compound E Tecogel 2000 50.0% PVP
K25 33.3% PEG 400 16.7%
[0362] The ingredients were compounded together in a twin-screw
extruder. PEG 400 was added to the extruder by a peristaltic pump,
and Tecogel 2000 and PVP K25 were added by two gravimetric feeders.
The blend was extruded into strands and pelletized.
[0363] Two single screw extruders were then connected to a single
crosshead dual tube die. Extruder #1 was charged with a hydrophilic
polyurethane, Tecophilic (Noveon), and extruder #2 was charged with
Compound E. In this example, the materials were extruded onto a
prefabricated tube of Estane 58212. Extruder #1 extruded Tecophilic
as the inner layer, and extruder #2 extruded the outer layer. The
ratios of inner to outer layer were varied by adjusting the output
of either extruder by increasing or lowering the screw speed. The
thickness of the layers was adjusted by varying either the output
or the haul-off speed.
[0364] After extrusion the coated tube was swelled in water for at
least 24 hours. It was observed (see FIGS. 4 (a) and (b)) that
Compound E disintegrated when swelled, due to high water absorption
and very low gel strength. The inner layer of Tecophilic had a
tendency to bond poorly to the Estane 58212 tube. Delamination was
observed on most of the tube.
Reference Example 3
TABLE-US-00022 [0365] Ingredients (see FIG. 5 for compositions)
Tecogel 2000 Tecogel 500 Polyox N80
[0366] The ingredients were compounded together in a Brabender
compounder in various ratios. The blends were hot press laminated
onto flat substrates of Estane 58212. The adhesion was evaluated
after swelling in water for at least 24 hours. The friction was
evaluated after a dry-out period of 5 minutes.
[0367] The position of the symbols in FIG. 5 indicates the
composition of the blends. .box-solid.-symbols represent blends
that disintegrated when they were swelled in water: The water
absorption was high but the gel strength was too low. The -symbols
represent complete delamination, and separation of the layer from
the substrate occurs. The -symbols indicate good adhesion to the
substrate with no or very few water blisters between the
layers.
[0368] As illustrated in FIG. 5 high levels of the less hydrophilic
Tecogel 500 gave good adhesion to the substrate, Area I, but the
friction in this area was too high. Low frictions were observed on
laminates with blends from Area II. However, these blends
disintegrated or delaminated when they were swelled in water for 24
hours.
[0369] Hence, it was not possible to get a combination of low
friction and good adhesion when laminating these blends on Estane
58212 without photo-initiator.
* * * * *
References