U.S. patent application number 13/295700 was filed with the patent office on 2012-03-15 for radiation curable composition.
This patent application is currently assigned to DSM IP Assets B.V.. Invention is credited to Alfred Jean Paul BCKMANN, Jacobus Willem GRIFFIOEN, Gerardus Cornelis OVERBEEK, Michael Arnoldus Jacobus SCHELLEKENS.
Application Number | 20120065326 13/295700 |
Document ID | / |
Family ID | 36177945 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120065326 |
Kind Code |
A1 |
OVERBEEK; Gerardus Cornelis ;
et al. |
March 15, 2012 |
RADIATION CURABLE COMPOSITION
Abstract
A radiation curable composition comprising 15 to 85 wt % of at
least one solvent comprising .ltoreq.20 wt % of water; 5 to 50 wt %
of at least one radiation curable material having a Mn in the range
of from 50 to 10,000 g/mol; and 10 to 70 wt % of at least one
polyurethane having a Mw in the range of from 4,000 to 70,000
g/mol, the polyurethane having 0 to 5 wt % of isocyanate-reactive
component(s) bearing ionic or potentially ionic water-dispersing
groups and a free isocyanate group content.ltoreq.0.5 wt %.
Inventors: |
OVERBEEK; Gerardus Cornelis;
(Waalwijk, NL) ; BCKMANN; Alfred Jean Paul;
(Waalwijk, NL) ; SCHELLEKENS; Michael Arnoldus
Jacobus; (Waalwijk, NL) ; GRIFFIOEN; Jacobus
Willem; (Waalwijk, NL) |
Assignee: |
DSM IP Assets B.V.
Heerlen
NL
|
Family ID: |
36177945 |
Appl. No.: |
13/295700 |
Filed: |
November 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12097665 |
Aug 19, 2008 |
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PCT/EP2006/011764 |
Dec 7, 2006 |
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13295700 |
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Current U.S.
Class: |
524/591 ;
101/483 |
Current CPC
Class: |
C09J 175/08 20130101;
C09D 11/101 20130101; C09D 11/102 20130101; C09D 175/16 20130101;
C09D 175/04 20130101; C09D 175/16 20130101; C08L 75/08 20130101;
C08L 2666/20 20130101; C09J 175/04 20130101 |
Class at
Publication: |
524/591 ;
101/483 |
International
Class: |
C09D 11/10 20060101
C09D011/10; C09J 175/00 20060101 C09J175/00; B41F 33/00 20060101
B41F033/00; C08L 75/00 20060101 C08L075/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2005 |
EP |
05112487.3 |
Claims
1. According to the present invention there is provided a radiation
curable composition comprising: (a) 15 to 85 wt % of at least one
solvent comprising .ltoreq.20 wt % of water; (b) 5 to 50 wt % of at
least one radiation curable material having a Mn in the range of
from 50 to 10,000 g/mol and an average acrylate functionality in
the range of from 2 to 6; (c) 10 to 70 wt % of at least one
polyurethane (i) having a Mw in the range of from 4,000 to 70,000
g/mol; (ii) having 0 to 1.5 wt % of isocyanate-reactive
component(s) bearing ionic or potentially ionic water-dispersing
groups; (iii) having a free isocyanate group content<0.5 wt %;
and wherein (a), (b) and (c) add up to 100%.
2. A composition according to claim 1 wherein the ratio of (b) to
(c) is in the range of from 9/91 to 40/60.
3. A composition according to claim 1 wherein the solvent (a)
comprises 75 wt % of solvents having an evaporation
rate.gtoreq.1.0.
4. A composition according to claim 1 wherein the radiation curable
material (b) is a UV curable material.
5. A composition according to claim 1 wherein the polyurethane (c)
has a viscosity.ltoreq.18,000 mPa s at any solids content in the
range of from 20 to 60 wt %, in a solvent comprising .gtoreq.70 wt
% of at least one solvent having a molecular weight.ltoreq.105
g/mol.
6. A composition according to claim 1 comprising: (a) 15 to 85 wt %
of at least one solvent comprising .ltoreq.1 wt % of water; (b) 5
to 50 wt % of at least one radiation curable material: (i) having a
Mn in the range of from 550 to 3500 g/mol; (ii) having an average
acrylate function in the range of from 2 to 5; (c) 10 to 70 wt % of
at least one polyurethane: (i) having a Mw in the range of from
6,000 to 55,000 glmol; (ii) having 0 to 1.5 wt % of
isocyanate-reactive component(s) bearing ionic or potentially ionic
water-dispersing groups; (v) having a non-detectable free
isocyanate group content; (vi) having 0 to 0.1 mol of CC bonds per
100 g; and wherein (a), (b) and (c) add up to 100%; where the ratio
of (b) to (c) is in the range of from 14/86 to 35/65.
7. A composition according to claim 1 wherein the polyurethane is
obtained by the reaction of the components: (i) 5 to 50 wt % of at
least one polyisocyanate; (ii) 0 to 20 wt % of at least one
isocyanate-reactive component having a Mw in the range of from 50
to 200 g/mol; (iii) 0 to 90 wt % of at least one
isocyanate-reactive component having a Mw in the range of from 201
to 20,000 g/mol; (iv) 0 to 95 wt % of at least one
isocyanate-reactive component not comprised by (ii) or (iii); (v) 0
to 40 wt % of at least one chain-extending and/or chain-terminating
component not comprised by (i), (ii), (iii) or (iv); where (i),
(ii), (iii), (iv) and (v) add up to 100%; in the presence of a
solvent; where the components comprise 0 to 1.5 wt % of
isocyanate-reactive component(s) bearing ionic or potentially ionic
water-dispersing groups.
8. A composition according to claim 1 having a solids content in
the range of from 25 to 85 wt %.
9. A composition according to claim 1 having a resolubility within
30 seconds.
10. An adhesive comprising a composition according to claim 1.
11. An ink comprising: (a) 15 to 84 wt % of at least one solvent
comprising .ltoreq.20 wt % of water; (b) 5 to 50 wt % of at least
one radiation curable material having an Mn in the range of from 50
to 10,000 g/mol and an average acrylate functionality in the range
of from 2 to 6; (c) 10 to 70 wt % of at least one polyurethane: (i)
having a Mw in the range of from 4,000 to 70,000 g/mol; (ii) having
0 to 1.5 wt % of isocyanate-reactive component(s) bearing ionic or
potentially ionic water-dispersing groups; having a free isocyanate
group content.ltoreq.0.5 wt %; and (d) 0.1 to 50 wt % of at least
one colorant: wherein (a), (b), (c) and (d) add up to 100%; and
where the ratio of (b) to (c) is in the range of from 9/91 to
40/60.
12. An ink according to claim 11 comprising .ltoreq.10 wt % of
water.
13. An ink according to claim 11 having a viscosity in the range of
from 50 to 1,000 mPa s.
14. A process for printing an image on a substrate comprising
applying thereto an ink according to claim 11.
15. A flexographic printing process comprising applying an ink
according to claim 11 to a substrate.
16. A gravure printing process comprising applying an ink according
to claim 11 to a substrate.
17. A gravure printing process comprising applying an ink according
to claim 12 to a substrate.
Description
[0001] This application is a continuation of commonly owned
co-pending U.S. application Ser. No. 12/097,665, filed Jun. 16,
2008, which in turn is the national phase application under 35 USC
.sctn.371 of PCT/EP/2006/011764, filed Dec. 7, 2006, which
designated the U.S. and claims priority to EP Application No.
05112487.3, filed Dec. 20, 2005, the entire contents of each of
which are hereby incorporated by reference.
[0002] The invention relates to a composition comprising at least
one radiation curable material and at least one solvent borne
polyurethane, an adhesive comprising the composition and an ink
comprising the composition.
[0003] Such inks are suited for various printing techniques such as
flexographic printing, gravure printing, and screen printing, and
can be used in number of applications, including for example inks
for flexible packaging substrates like paper, board and plastic as
well as metallic foils for both surface printing and lamination
applications.
[0004] Laminates are multi-layered composites where each layer
consists of the same or different materials. In the field of
flexible packaging, laminates usually comprise plastic and/or
metallized films. Flexible packaging is used for example in the
food industry and has many requirements such as for example
eliminating or limiting the transfer of moisture, oxygen, oils and
flavours; flexible packaging used for microwave cooking needs to
protect the contents during storage but also needs to have good
heat resistance; flexible packaging used for beverages needs to
have good cold resistance and handling resistance; flexible
packaging used in other applications may also need to be resistant
to the transfer to perfumes, resistant to surfactants, resistant to
oil/water mixtures, and additionally the flexible packaging should
be easy to open when required.
[0005] Generally laminates are produced by joining two or more
layers using adhesives or by carrying out adhesive-free extrusion
coating. Additionally it is often desirable to apply an image to
one or more of the layers during the lamination process.
[0006] For example, if using an adhesive laminating method an image
may be printed onto a plastic film substrate, after which an
adhesive is applied to the inked substrate, followed by applying a
second film to the adhesive (the adhesive could also be applied to
the second film). If using an extrusion coating/laminating method
an image may be printed onto a plastic film substrate, optionally
followed by the application of a primer and then a molten resin is
extruded onto the inked substrate to form a second layer followed
by the formation of a bond between the two substrates. It is
therefore desirable that laminating inks possess excellent adhesion
to the printing substrate as well as to the film adhesive and/or
film to be laminated.
[0007] Laminated films, when used to make packaging, often undergo
heat sealing and when used as food packaging must be able to
undergo a boiling or retorting treatment for cooking or sterilizing
the contents. It is therefore also desirable that delamination does
not occur during such processes.
[0008] The properties of a laminate therefore depend on the type of
films used, the laminating process, the type of adhesive and the
ink properties and in particular the properties of any resins used
as binders in the ink.
[0009] The types of films that are used in flexible packaging
laminates include amongst others: polyester, cellophane,
polypropylene, polyethylene, aluminium foils, nylon and paper. Such
films may also have been functionalised through a range of chemical
and physical treatments.
[0010] A range of binders have been used in laminating inks such as
modified PVC (polyvinyl chloride), polyvinyl butyral, polyamides,
polyesters, nitrocellulose and both water- and solvent-based
polyurethanes, acrylics and co-polymers thereof. However it has
been found that some binders are incompatible, difficult to clean
up from ink printing equipment and many only adhere to certain
substrates and even if the binders do adhere, they may be poor in
their resistance to boiling or retorting treatments and generally
do not achieve desirable bond strength. In addition there is an
increase in demand for high line speed printing, especially at line
speeds greater than 200 m/min or even greater than 300 m/min.
However, at such line speeds printability problems such as cob
webbing may occur for flexo printing and scumming may appear for
gravure printing processes. One cause of such problems is the
limited resolubility, also called redispersibility, of the binders
used in the inks in the typical solvents used in these
applications. Resolubility is a property, well known to the
printing industry, whereby dry or drying polymer obtained from an
aqueous or solvent based polymer composition is redispersible or
redissolvable in that same composition when the latter is applied
thereto. Resolubility is defined in more detail below. Resolubility
is of great importance in the process of printing which generally
involves applying the ink-formulation by various cylinders (smooth,
engraved or flexo diches); these can become blocked with polymer by
evaporation of the liquid medium (solvent and/or water) and/or the
ink formulation can dry on the roller surface (e.g. during a short
stoppage of the process for one reason or another) and this would
obviously create problems when the process is restarted if the
polymer were not resoluble.
[0011] Although the use of solvents such as ketones or solvents
with a slower evaporation rate may be used to solve some of the
problems, these solvents have other inherent issues such as safety
and environmental issues as well as being slow to dry which can
result in the solvent migrating into the packed material. Therefore
the use of solvents with a faster evaporation rate is useful,
although if they are too fast then printability failures may also
occur.
[0012] There are also concerns with chlorine being given of during
the incineration of packaging printed with polyvinyl chloride based
inks and polyvinyl butyral based inks are associated with printing
difficulties.
[0013] A method for overcoming such problems is to use a
combination of binders where binders may be chosen to suit
particular films and adhesives. However a disadvantage with such an
approach is that a large number of binders need to be prepared and
stored for all the different types of inks that may be applied to
the laminate films. Additionally if the various inks are not
compatible with each other then extensive cleaning of the printing
equipment would be required for each change over.
[0014] EP 0,338,791 discloses printing inks consisting of a
water-in-oil emulsion including a radiation curable component. A
disadvantage of having mainly a radiation curable component is that
coatings may shrink on cure and there may be an odour and taint
impact, as a result of possible migration of low molecular weight
fractions. This migration may also lead to a taste impact when
applied on a material which is used for food packaging.
[0015] EP 0,604,890 discloses a printing ink composition for a
laminate containing a polyurethane resin. U.S. Pat. No. 6,642,343
discloses the use of a polyurethane resin as a film forming binder
in inks. WO 01/14442 discloses a polyurethane resin that may be
used in formulating printing ink compositions. WO 02/38643
discloses solvent based poly(urethane/urea) resins suitable for
formulating laminating printing inks.
[0016] A disadvantage of such polyurethanes is that they often
still require combining with several other binders, especially hard
binders to get a good balance of properties such as for example
adhesion, block resistance, flexibility, solvent retention,
chemical resistances and resistance to sterilisation.
[0017] The addition of a radiation curable material was found to
give an improved balance of film properties. GB 1,564,542 discloses
radiation curable, solvent-free coatings. U.S. Pat. No. 5,061,605
discloses a photopolymerisable compositions. EP 0,241,027 discloses
an adhesive composition comprising a photopolymerisable compound
and a free isocyanate compound. EP 0,040,923 discloses a radiation
curable composition for an adhesive coating.
[0018] Surprisingly we have found that it is possible to prepare a
combination of a polyurethane binder with a radiation curable
material that may overcome many of the disadvantages of the prior
art systems with a polyurethane system which is suitable for use as
an adhesive or as an ink, especially as an ink for screen printing
and for flexo and gravure printing processes on a broad range of
substrates used in flexible packaging film laminates and which are
suitable for extrusion lamination. Furthermore, compared to
water-borne inks, which generally require the use of more
hydrophilic i.e. water compatible binder or stabilisation
materials, solvent based polyurethanes in combination with
radiation curable materials may show improved chemical resistances
which may be of importance for food packaging applications.
[0019] According to the present invention there is provided a
radiation curable composition comprising: [0020] (a) 15 to 85 wt %
of at least one solvent comprising .ltoreq.20 wt % of water; [0021]
(b) 5 to 50 wt % of at least one radiation curable material having
a Mn in the range of from 50 to 10,000 g/mol; [0022] (c) 10 to 70
wt % of at least one polyurethane: [0023] (i) having a Mw in the
range of from 4,000 to 70,000 g/mol; [0024] (ii) having 0 to 5 wt %
of isocyanate-reactive component(s) bearing ionic or potentially
ionic water-dispersing groups; [0025] (iii) having a free
isocyanate group content.ltoreq.0.5 wt %; and [0026] wherein (a),
(b) and (c) add up to 100%.
[0027] Preferably the ratio of (b) to (c) is in the range of from
9/91 to 40/60 and most preferably from 14/86 to 35/65.
[0028] Preferably radiation curable includes UV curable and
electron beam curable, most preferably radiation curable is UV
curable.
[0029] Compared to laminating inks that are based on a higher Mw
solvent borne polyurethane binder, the present invention offers an
improved drying speed due to a higher attainable solids content and
the combination of radiation curing and thermal drying which may
result in higher line speeds being possible.
[0030] Preferably the composition of the invention comprises 15 to
80 wt % and most preferably 15 to 75 wt % of solvent (a).
[0031] Preferably the solvent (a) comprises .gtoreq.75 wt %, more
preferably .gtoreq.90 wt %, most preferably .gtoreq.98 wt % and
especially 100 wt % of fast evaporating solvents. Fast evaporating
solvents are solvents having an evaporation rate of .gtoreq.1.0,
more preferably .gtoreq.1.4 and most preferably .gtoreq.1.6. Values
for evaporation rates were published by Texaco Chemical Company in
a bulletin Solvent Data: Solvent Properties (1990). (The values
given are relative to the evaporation rate (ER) of butyl acetate
which is defined as 1.00). Determination of evaporation rates of
solvents that are not listed the Texaco bulletin is as described in
ASTM D3539.
[0032] Fast evaporating solvents are particularly useful where fast
drying times are required, especially when printing onto
hydrophobic and non-absorbent substrates, for example plastic,
metal and glass.
[0033] The solvent (a) is preferably selected from the group
consisting of alcohols (such as ethanol, isopropanol, n-butanol,
n-propanol, cyclohexanol), esters (such as ethyl acetate, propyl
acetate, isopropyl acetate, butyl acetate), aromatic solvents (such
as toluene), ketone solvents (such as acetone, methyl ethyl ketone,
methyl isobutyl ketone) cyclohexanone; diacetone alcohol; aliphatic
hydrocarbons; chlorinated hydrocarbons (such as CH.sub.2Cl.sub.2);
ethers (such as diethyl ether, tetrahydrofuran); and mixtures
thereof. Most preferably at least 70 wt %, more preferably at least
85 wt % and especially more than 98 wt % of the solvent (a)
comprises a solvent selected from the group comprising ethanol,
isopropanol, ethylacetate and mixtures thereof. Preferably the
solvent (a) comprises 10 wt % of water, more preferably .ltoreq.6
wt % and most preferably .ltoreq.1 wt % of water.
[0034] The radiation curable material of the invention composition
may comprise one or more than one radiation curable material.
[0035] Preferably the radiation curable material (b) has a Mn in
the range of from 220 and 7,000 g/mol more preferably 400 to 6,000
g/mol, most preferably 500 to 5,200 g/mol and especially 550 to
3,500 g/mol.
[0036] Mn (number average molecular weight) and Mw (weight average
molecular weight) herein when measured, are measured by Gel
Permeation Chromatography (GPC), using THF as a solvent and
polystyrene standards i.e. g/mol based on polystyrene
standards.
[0037] Preferably the radiation curable material is cured with a
radical mechanism. The radiation curable material when cured by a
radical mechanism may also be initiated with a thermal initiator
instead of a photoinitiator or with both. Use of a thermal
initiator is commonly referred to as thermal curing.
[0038] The radiation curable material may comprise a wide variety
of monofunctional or multifunctional materials. Preferably the
radiation curable material has one, preferably two or more
radiation polymerisable ethylenically unsaturated bonds which are
capable of polymerisation. Preferably the radiation curable
material has an average acrylate functionality in the range of from
1 to 6, more preferably 2 to 6 and most preferably 2 to 5.
[0039] Typical examples of such materials include but are not
limited to epoxy (meth)acrylates; polyester (meth)acrylates;
urethane (meth)acrylates; silicon (meth)acrylates; acrylated
acrylics; mono- and multi-functional (meth)acrylate monomers and
amine-(meth)acrylate adducts.
[0040] At the lower molecular weight range of the radiation curable
material, the radiation curable material preferably comprises one
or more monofunctional or multifunctional (meth)acrylate monomers,
or amine-(meth)acrylate adducts.
[0041] Examples of monofunctional radiation curable material are:
phenoxyethyl acrylate (PEA), isobornyl (meth)acrylate (IBOA and
IBOMA), isooctyl acrylate (IOA), octyl and decyl acrylate, isodecyl
acrylate (IDA), (ethoxylated) nonylphenol acrylate (NPEA),
ethoxyethoxyethyl acrylate (EEEA), dicyclopentyloxyethyl
(meth)acrylate (DCPEA and DCPEMA), tetrahydrofurfuryl
(meth)acrylate (THFA and THFMA), beta-carboxyethyl acrylate (BCEA),
acrylic acid, caprolactone (meth)acrylate, alkoxylated
(meth)acrylate, glycerol (meth)acrylate, N-vinylpyrolidone,
N-vinylformamide, N-vinylcaprolactam, styrene, dimethylacrylamide
and silane monomers. Multifunctional (meth)acrylate monomers are
for example (meth)acrylic acid esters of di- and tri-hydroxyl
alcohols (e.g. polyethylene glycol, polypropylene glycol, aliphatic
diols, neopentyl glycol, ethoxylated bisphenol A,
trimethylolpropane, pentaerythritol, glycerol,
di-trimethylolpropane, hydroxyl functional polyesters,
dipentaerythritol and the ethoxylated, propoxylated and
polycaprolactone analogues of all the above). Preferably such
multifunctional materials are substituted and unsubstituted
(meth)acrylates. Preferred examples are: (alkoxylated) neopentyl
glycol di(meth)acrylate (NPGDA), (alkoxylated)trimethylolpropane
tri(meth)acrylate (TMPTA and TMPTMA), (alkoxylated)pentaerythritol
tri(meth)acrylate and tetra(meth)acrylate (PETA), 1,4-butanediol
di(meth)acrylate (BDDA and BDDMA), 1,6-hexanediol di(meth)acrylate
(HDDA and HDDMA),
2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate
di(meth)acrylate, triethylene glycol di(meth)acylate (TEGDA and
TEGDMA), tripropylene glycol di(meth)acrylate (TPGDA and TPGDMA),
glycerol propoxylate triacrylate (GPTA), alkoxylated bisphenol A
diacrylate, polyethyleneglycol di(meth)acrylate (PEGDA and PEGDMA),
dipentaerythritol pentaacrylate (DPEPA), and the like.
[0042] Amine-(meth)acrylate adducts are those products prepared by
the partial "Michael Type Addition" of primary and secondary amines
to ethylenic unsaturation i.e. the double bond of (meth)acrylate
containing compounds. Of particular interest here are the
multi-functional (meth)acrylate monomers as mentioned below.
Examples of amine-acrylate adducts are diethylamine modified
trimethylolpropane triacrylate and ethanolamine modified
ethoxylated trimethylolpropane triacrylate.
[0043] Epoxy (meth)acrylates are products formed by the reaction of
(meth)acrylic acid with an epoxy(glycidyl) functional component
e.g. aliphatic and aromatic containing epoxy resins, epoxidized
oils, acrylic polymers and acrylic grafted polymers in which the
acrylic component contains pendent epoxy groups. Some of the
(meth)acrylic acid may be replaced by other acids, both
ethylenically unsaturated and saturated, so as to impart specific
properties e.g. aliphatic acids, fatty acids and aromatic acids.
These products may alternatively be prepared by the reaction of a
carboxylic acid functional component (e.g. polyesters and acrylic
polymers) with a second component containing both epoxy groups and
ethylenic unsaturation e.g. glycidyl (meth)acrylate.
[0044] Urethane (meth)acrylates are those products formed by the
reaction of an isocyanate containing component with a hydroxyl
containing component. At least one of these components must contain
ethylenic unsaturation. Examples of isocyanate functional
components are hexamethylene diisocyanate, isophorone diisocyanate,
isocyanate functional acrylic polymers and polyurethanes, reaction
products of hydroxyl functional components (e.g. polyethylene
glycol, polypropylene glycol and di-, tri- and etc-hydroxy
aliphatic alcohols (e.g. glycerol and trimethylolpropane) and their
ethoxylated, propoxylated and polycaprolactone analogs) with di-,
tri- and etc-isocyanates (e.g. hexamethylene diisocyanate,
isophorone diisocyanate and toluene diisocyanate). Examples of
hydroxy containing ethylenically unsaturated components are
hydroxyethyl (meth)acrylate and its ethoxylated, propoxylated and
polycaprolactone analogs as well as (meth)acrylated polyester
polyols and (meth)acrylated polyether polyols.
[0045] Preferably the radiation curable material (b) is selected
from the group consisting of bisphenol A epoxyacrylate, fatty acid
modified bisphenol A acrylate, aliphatic epoxy (meth)acrylate,
epoxy modified oil (meth)acrylate, polyester (meth)acrylate,
urethane (meth)acrylate, acrylated acrylic, silicone acrylate,
IBOA, IBOMA, PEA, TMPTA, alkoxylated TMPTA, TMPTMA, HDDA,
alkoxylated HDDA, HDDMA, TPGDA, PETA, alkoxylated PETA, and
mixtures thereof. These are all UV curable materials.
[0046] Preferably the composition of the invention comprises 5 to
40 wt % and most preferably 6 to 35 wt % of radiation curable
material (b).
[0047] Preferably the viscosity of the radiation curable material
(b) is .ltoreq.200 Pas, more preferably .ltoreq.100 Pa--s and most
preferably .ltoreq.50 Pa--s at 25.degree. C.
[0048] The polyurethane (c) may comprise one or more than one
polyurethane.
[0049] Preferably the Mw of the polyurethane (c) is in the range of
from 5,000 to 65,000 g/mol and more preferably 6,000 to 55,000
g/mol.
[0050] Preferably the composition of the invention comprises 20 to
70 wt %, more preferably 20 to 65 wt % and most preferably 22 to 55
wt % of polyurethane (c).
[0051] For clarity, it is preferred that the polyurethane (c) is
not radiation curable, although it may be possible for some of the
higher Mw polyurethanes to have a degree of C.dbd.C double bonds
that may be curable.
[0052] Preferably any polyurethane (c) with a Mw in the range of
from 4,000 to 30,000 g/mol and especially any polyurethane (c) with
a Mn in the range of from 1,000 to 10,000 g/mol is essentially free
of C.dbd.C double bonds. By essentially free is meant 0 to 0.1 mol
of C.dbd.C double bonds per 100 g of polyurethane.
[0053] Preferably the PDi of the polyurethane (c) is in the range
of from 1.3 to 10, more preferably 1.3 to 6 and especially 1.6 to
3. The polydispersity index (PDi) is defined as the weight average
molecular weight (Mw) divided by the number average molecular
weight (Mn).
[0054] In an embodiment of the invention the polyurethane (c) has
an Mp in the range of from 10,000 to 35,000 g/mol, more preferably
the Mp is in the range of from 13,000 to 32,000 g/mol, most
preferably 17,000 to 31,000 g/mol and especially 19,000 to 30,000
g/mol. The Mp is the molecular weight with the highest signal (i.e.
the apex of the peak) in a chromatogram resulting from the
measuring of the molecular weight using GPC with polystyrene as a
standard and tetrahydrofuran as an eluent. Mp values are discussed
in Modern Size Exclusion Liquid Chromatography, W. W. Yau, J. K.
Kirkland and D. D. Bly, John Wiley & Sons, USA, 1997.
[0055] The polyurethane (c) of the invention composition preferably
has a viscosity.ltoreq.18,000 mPas, more preferably .ltoreq.12,000
mPas and most preferably .ltoreq.6,000 mPas at any solids content
in the range of from 20 to 60 wt %, in a solvent comprising
.ltoreq.70 wt %, more preferably .ltoreq.90 wt % and most
preferably 100 wt % of at least one solvent having a molecular
weight.ltoreq.105 g/mol. All viscosities are measured according to
ISO 2555-1989 at 25.degree. C. Preferred solvents used to measure
the viscosity of the polyurethane (c) in, include ethanol,
isopropanol, n-propanol, ethyl acetate, propyl acetate and or
mixtures thereof.
[0056] The polyurethane (c) of the invention composition is
preferably obtained by the reaction of components comprising:
[0057] (i) 5 to 50 wt % of at least one polyisocyanate; [0058] (ii)
0 to 20 wt % of at least one isocyanate-reactive component having a
Mw in the range of from 50 to 200 g/mol; [0059] (iii) 0 to 90 wt %
of at least one isocyanate-reactive component having a Mw in the
range of from 201 to 20,000 g/mol; [0060] (iv) 0 to 95 wt % of at
least one isocyanate-reactive component not comprised by (ii) or
(iii); [0061] (v) 0 to 40 wt % of at least one chain-extending
and/or chain-terminating component not comprised by (i), (ii),
(iii) or (iv); where (i), (ii), (iii), (iv) and (v) add up to 100%;
in the presence of a solvent; where the components comprise 0 to 5
wt % of isocyanate-reactive component(s) bearing ionic or
potentially ionic water-dispersing groups.
[0062] The polyisocyanate component (i) may be an aliphatic
polyisocyanate, an aromatic polyisocyanate or mixtures thereof.
[0063] The term aromatic polyisocyanate (for the sake of clarity)
is intended to mean compounds in which all the isocyanate groups
are directly bonded to an aromatic group, irrespective of whether
aliphatic groups are also present. Examples of suitable aromatic
polyisocyanates include but are not limited to p-xylene
diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate,
2,6-toluene diisocyanate, 4,4'-methylene bis(phenyl isocyanate),
polymethylene polyphenyl polyisocyanates, 2,4'-methylene bis(phenyl
isocyanate) and 1,5-naphthylene diisocyanate. Preferred aromatic
isocyanates include 2,4'-methylene bis(phenyl isocyanate) and
4,4'-methylene bis(phenyl isocyanate). Aromatic polyisocyanates
provide chemical resistance and toughness but may yellow on
exposure to UV light.
[0064] The term aliphatic polyisocyanate (for the sake of clarity)
is intended to mean compounds in which all the isocyanate groups
are directly bonded to aliphatic or cycloaliphatic groups,
irrespective of whether aromatic groups are also present.
[0065] Examples include but are not limited to ethylene
diisocyanate, para-tetra methylxylene diisocyanate (p-TMXDI),
meta-tetra methylxylene diisocyanate (m-TMXDI), 1,6-hexamethylene
diisocyanate, isophorone diisocyanate (IPDI),
cyclohexane-1,4-diisocyanate and 4,4'-dicyclohexylmethane
diisocyanate. Aliphatic polyisocyanates improve hydrolytic
stability, resist UV degradation and do not yellow. Preferred
aliphatic iscocyanates include isophorone diisocyanate,
4,4'-dicyclohexylmethane diisocyanate and 1,6-hexamethylene
diisocyanate.
[0066] Preferably at least 70 wt %, more preferably at least 85 wt
% and most preferably at least 95 wt % of the polyisocyanate in
component (i) has two isocyanate groups.
[0067] Aromatic or aliphatic polyisocyanates which have been
modified by the introduction of, for example, urethane,
allophanate, urea, biuret, uretonimine and urethdione or
isocyanurate residues may be used for component (i).
[0068] Preferably the polyurethane comprises 4 to 30 wt % and more
preferably 10 to 20 wt % of component (i).
[0069] The isocyanate-reactive components (ii) to (iv) will
normally consist of a polyol component bearing isocyanate-reactive
groups which may also bear other reactive groups such as ionic
(anionic and cationic) and non-ionic water dispersing groups.
Isocyanate-reactive groups include groups such as --OH, --SH,
--NH--, --NH.sub.2 and --CHR.sup.1--COOH where R.sup.1 can be H or
alkyl (more preferably C.sub.1 to C.sub.8 alkyl).
[0070] Examples of component (ii) include but are not limited to
1,4-cyclohexyldimethanol, ethylene glycol, propylene glycol,
diethylene glycol, neopentyl glycol, 1,4-butanediol,
1,6-hexanediol, furan dimethanol, cyclohexane dimethanol, glycerol,
trimethylolpropan, dimethylol propanoic acid (DMPA) and dimethylol
butanoic acid (DMBA). DMPA and DMBA are examples of
isocyanate-reactive components (ii) bearing anionic or potentially
anionic water-dispersing groups.
[0071] Preferably component (ii) has an average of 1.8 to 2.5
isocyanate-reactive groups and more preferably component (ii) has
two hydroxy functional groups.
[0072] Preferably the weight average molecular weight (Mw) of
component (ii) is in the range of from 62 to 200 g/mol and more
preferably 84 to 200 g/mol.
[0073] Preferably the polyurethane (c) comprises 0 to 5 wt % and
more preferably 0 to 3 wt % of component (ii).
[0074] Examples of component (iii) and (iv) include but are not
limited to polyols such as polypropylene glycols, poly(propylene
oxide/ethylene oxide) copolymers, polytetrahydrofuran,
polybutadiene, hydrogenated polybutadiene, polysiloxane, polyamide
polyesters, isocyanate-reactive polyoxyethylene compounds,
polyester, polyether, polycaprolactone, polythioether,
polycarbonate, polyethercarbonate, polyacetal and polyolefin
polyols. Generally polyester polyols provide good weathering, good
adhesion, improved chemical resistance and toughness; polyether
polyols provide good flexibility and elasticity; polycaprolactone
polyols provide improved weathering and better heat resistance than
polyether polyols and better water resistance than adipate
polyester polyols.
[0075] Polyester amides may be obtained by the inclusion of
amino-alcohols such as ethanolamine in polyesterification mixtures.
Polyesters which incorporate carboxy groups may be used, for
example polyesters where DMPA and/or DMBA are used during the
synthesis.
[0076] Polyether polyols which may be used include products
obtained by the polymerisation of a cyclic oxide, for example
ethylene oxide, propylene oxide or tetrahydrofuran or by the
addition of one or more such oxides to polyfunctional initiators,
for example water, methylene glycol, ethylene glycol, propylene
glycol, diethylene glycol, cyclohexane dimethanol, glycerol,
trimethylopropane, pentaerythritol or Bisphenol A. Especially
useful polyether polyols include polyoxypropylene diols and triols,
poly (oxyethylene-oxypropylene) diols and triols obtained by the
simultaneous or sequential addition of ethylene and propylene
oxides to appropriate initiators and polytetramethylene ether
glycols obtained by the polymerisation of tetrahydrofuran.
Particularly preferred are polypropylene glycols.
[0077] Preferably the weight average molecular weight of component
(iii) is in the range of from 500 to 11,000 g/mol, more preferably
600 to 6,000 g/mol and especially 700 to 5,000 g/mol.
[0078] Components (iii) and (iv) may also include crosslinking
groups. Crosslinking groups are well known in the art and include
groups which crosslink at ambient temperature (20.+-.3.degree. C.)
or at elevated temperatures up to 185.degree. C., preferably up to
160.degree. C. by a number of mechanisms including but not limited
to Schiff base crosslinking (for example the reaction of carbonyl
functional groups with carbonyl reactive amine and/or hydrazine
functional groups); silane crosslinking (for example the reaction
of alkoxy silane groups in the presence of water), melamine
crosslinking and epoxy groups crosslinking with epoxy-reactive
functional groups or isocyanate curing, where hydroxy or amine
(primary or secondary) functional polyurethanes are combined with
polyisocyanates. Usually the polyisocyanates are added shortly
before application. In a preferred embodiment, blocked
polyisocyanates are used, where for example the polyurethane is
blocked with a mekoxime, which deblocks at elevated temperature
after application and can then react with a hydroxyl functional
urethane at the elevated temperature. Isocyanate crosslinking is
most preferred, when crosslinking is applied during the application
process.
[0079] Preferably the polyurethane (c) comprises 20 to 90 wt % and
more preferably 60 to 90 wt % and especially 70 to 90 wt % of
component (iii).
[0080] Preferably the polyurethane (c) comprises 0 to 6 wt % and
more preferably 0 to 3 wt % and most preferably 0 wt % of component
(iv).
[0081] Preferably polyurethane (c) comprises 0 to 5 wt %, more
preferably 0 to 3 wt % and especially 0 to 1.5 wt % of isocyanate
reactive component(s) bearing ionic or potentially ionic
water-dispersing groups. This includes components (ii), (iii), (iv)
and (v).
[0082] Component (v) is a chain-extending and/or chain-terminating
component.
[0083] Examples of chain-terminating components include
mono-alcohols, amino-alcohols, primary or secondary amines and
mono-functional hydrazines as are well known in the art. Di- or
poly-functional isocyanate-reactive components may be used as a
chain-terminating component if only one isocyanate-reactive group
reacts under the given conditions. Examples of such difunctional
components include mono-ethanol amine. The chain-terminating
component may also be a mono-functional isocyanate.
[0084] Examples of chain-extending components include
amino-alcohols, primary or secondary diamines or polyamines such as
ethylene diamine, propylene diamine and cyclic amines such as
isophorone diamine and 4,4'-dicyclohexylmethane diamine; hydrazine
and substituted hydrazines such as, for example, dimethyl
hydrazine, 1,6-hexamethylene-bis-hydrazine, carbodihydrazine,
hydrazides of dicarboxylic acids and sulphonic acids such as adipic
acid dihydrazide, oxalic acid dihydrazide, isophthalic acid
dihydrazide, hydrazides made by reacting lactones with hydrazine,
bis-semi-carbazide, and bis-hydrazide carbonic esters of glycols;
azines such as acetone azine, and or mixtures thereof. Another
suitable class of chain-extending components are the so-called
"Jeffamine" compounds with a functionality of 2 or 3 (available
from Huntsman). These are PPO or PEO-based di or triamines, e.g.
"Jeffamine" T403 and "Jeffamine" D-400. In a special embodiment
where the prepolymer has isocyanate-reactive functional groups
(such as hydroxyl groups) a chain-extending component may also be a
difunctional isocyanate.
[0085] Preferably the polyurethane (c) comprises 0.2 to 40 wt %,
more preferably 0.7 to 25 wt %, especially 1 to 10 wt % and most
especially 3 to 6 wt % of component (v).
[0086] The polyurethane (c) of the invention composition may be
prepared conventionally by reacting a stoichiometric excess of the
organic polyisocyanate (component (i)) with the isocyanate-reactive
components (components (ii), (iii) and (iv)) under substantially
anhydrous conditions at a temperature between about 30.degree. C.
and about 130.degree. C., more preferably about 45.degree. C. to
about 85.degree. C. until reaction between the isocyanate groups
and the isocyanate-reactive groups is substantially complete to
form an isocyanate-terminated prepolymer; preferably the reactants
for the prepolymer are generally used in proportions corresponding
to a ratio of isocyanate groups to isocyanate-reactive groups of
from about 1.2:1 to about 2:1, more preferably from about 1.3:1 to
2.0:1 and most preferably 1.45:1 to 2:1. If desired, catalysts such
as dibutyltin dilaurate and stannous octoate, zirconium or titanium
based catalysts may be used to assist the polyurethane formation.
Optionally no catalyst is added. Preferably no tin based catalyst
is added. The catalyst, if used may be added immediately to a
mixture of components (i) to (iv) or the mixture of components (i)
to (iv) may be allowed to react for a period of time before the
addition of a catalyst.
[0087] The reaction is usually carried out in the presence of an
organic solvent to control the viscosity. Suitable organic solvents
include but are not limited to acetone, tetrahydrofuran, ethyl
acetate, methyl ethyl ketone, methyl isobutyl ketone and other
solvents well known in the art. However it is preferred that
solvents containing hydroxyl-functionality, such as ethanol or
isopropanol should not be used during the early stages of the
polyurethane synthesis as they may have a detrimental effect on the
molecular weight build up. During chain-extension, these solvents
can be used, since the reaction of (di)amines with isocyanate
groups is significantly faster than the reaction of isocyanate
groups with hydroxyl groups.
[0088] If an isocyanate-terminated prepolymer is formed it is then
reacted with a chain-extending and/or chain-terminating component
(v). Preferably the reactants are used in proportions so that all
isocyanate groups are reacted so that the resultant polyurethane
(c) has a free isocyanate group content 0.5 wt %, most preferably
0.01 wt % and especially is so low that the isocyanate group
content is no longer detectable using methods well known in the
art. Alternately a hydroxyl-terminated prepolymer may be formed
which is then reacted with a chain-extending and/or
chain-terminating component (v).
[0089] The reaction between the components may be carried out in
any order. According to a preferred embodiment of the present
invention there is provided a composition comprising: [0090] (a) 15
to 85 wt % of at least one solvent comprising .ltoreq.1 wt % of
water; [0091] (b) 5 to 50 wt % of at least one radiation curable
material: [0092] (i) having a Mn in the range of from 550 to 3500
g/mol; [0093] (ii) having an average acrylate function in the range
of from 2 to 5; [0094] (c) 10 to 70 wt % of at least one
polyurethane: [0095] (i) having a Mw in the range of from 6,000 to
55,000 g/mol; [0096] (ii) having 0 to 5 wt % of isocyanate-reactive
component(s) bearing ionic or potentially ionic water-dispersing
groups; [0097] (iii) having a non-detectable free isocyanate group
content; [0098] (iv) having 0 to 0.1 mol of C.dbd.C bonds per 100
g; and [0099] wherein (a), (b) and (c) add up to 100%; where the
ratio of (b) to (c) is in the range of from 14/86 to 35/65.
[0100] Preferably the composition of the invention has a solids
content in the range of from 25 to 85 wt % and more preferably 40
to 85 wt % and most preferably 45 to 75 wt %.
[0101] Preferably the composition of the invention has a
resolubility within 30 seconds, more preferably within 20 seconds
and most preferably within 10 seconds.
[0102] The resultant composition may be used directly as a binder
for inks or in combination with, for example, defoamers,
anti-oxidants, corrosion inhibitors, bacteriocides, anti-settling
agents, dispersing agents, fillers, waxes, thickeners, co-resins
and/or colorants.
[0103] In an embodiment of the present invention there is provided
an adhesive, more preferably a laminating adhesive, comprising a
composition according to the invention.
[0104] In a further embodiment of the present invention there is
provided an ink comprising the composition according to the
invention and additionally a colorant (d).
[0105] The ink preferably has a viscosity in the range of from 50
to 1,000 mPas and more preferably 100 to 500 mPas at 20.degree.
C.
[0106] Preferably the ink comprises 0.1 to 50 wt %, more preferably
3 to 40 wt % and most preferably 8 to 40 wt % of (d), the
colorant.
[0107] Colorants include dyes, pigments or mixtures thereof. The
pigment may be any conventional organic or inorganic pigment such
as titanium dioxide, carbon black or any coloured pigments well
known in the art.
[0108] The dyes may be any conventional dyes selected from acid
dyes, natural dyes, cationic or anionic direct dyes, basic dyes and
reactive dyes.
[0109] Optionally the ink may also contain other ingredients used
in inks, for example defoamers, anti-oxidants, corrosion
inhibitors, bacteriocides and viscosity modifiers.
[0110] Preferably the ink comprises .ltoreq.10 wt % of water, more
preferably .ltoreq.6 wt % and most preferably .ltoreq.1 wt % of
water.
According to another preferred embodiment of the present invention
there is provided a ink comprising: [0111] (a) 15 to 84 wt % of at
least one solvent comprising .ltoreq.20 wt % of water; [0112] (b) 5
to 50 wt % of at least one radiation curable material having a Mn
in the range of from 50 to 10,000 g/mol; [0113] (c) 10 to 70 wt %
of at least one polyurethane: [0114] (i) having a Mw in the range
of from 4,000 to 70,000 g/mol; [0115] (ii) having 0 to 5 wt % of
isocyanate-reactive component(s) bearing ionic or potentially ionic
water-dispersing groups; [0116] (iii) having a free isocyanate
group content.ltoreq.0.5 wt %; and [0117] (d) 0.1 to 50 wt % of at
least one colorant; [0118] wherein (a), (b), (c) and (d) add up to
100%; and [0119] where the ratio of (b) to (c) is in the range of
from 9/91 to 40/60.
[0120] The ink may be used in a number of printing processes
including screen printing, flexographic and/or gravure printing
processes. Preferably the printing process is a flexographic and/or
gravure printing process.
[0121] In a further embodiment of the present invention there is
provided a process for printing an image on a substrate comprising
applying thereto an ink containing a composition according to the
present invention.
[0122] The invention will now be described by example only. All
parts and percentages are by weight unless specified otherwise.
Components Used
[0123] NeoRez U-347=available from DSM NeoResins BV, is a
non-reactive aromatic polyurethane with an average molecular weight
of Mn=3500 g/mol and Mw=8,500 g/mol and a solids content of 75%
(volatiles: 22.5% ethyl acetate, 2.5% ethanol). Viscosity
Brookfield (25.degree. C.): 1100 mPas. The Mp is 4,800 and the PDi
is 2.43. The wt % of isocyanate reactive components bearing ionic
or potentially ionic water dispersion groups used to make NeoRez
U-347 was 0%. There was no detectable isocyanate group content. The
level of C.dbd.C bonds per 100 g was 0 mol. NeoRez U-335=available
from DSM NeoResins BV, is a non-reactive semi-aliphatic
polyurethane with an average molecular weight of Mn=20,000 g/mol
and Mw=53,000 g/mol and a solids content of 45% (volatiles: 12.5%
ethyl acetate, 42.5% ethanol). Viscosity Brookfield (25.degree.
C.): 3,100 mPas. The Mp is 50,000 and the PDi is 2.65. The wt % of
isocyanate reactive components bearing ionic or potentially ionic
water dispersion groups used to make NeoRez U-335 was 0%. There was
no detectable isocyanate group content. The level of C.dbd.C bonds
per 100 g was 0 mol. Craynor CN104=available from Cray Valley, is a
bisphenol A epoxyacrylate (100%). Average molecular weight Mn=900
g/mol and the viscosity is 18 Pas at 50.degree. C. and the
functionality is 2. Ebecryl 8210=available from Cytec Surface
Specialties, is an aliphatic acrylated polyurethane (100%). Average
molecular weight Mn=600 g/mol and the viscosity is 4,500 mPas at
25.degree. C. and the functionality is 4. Ebecryl 810=available
from Cytec Surface Specialties, is a polyester acrylate (100%).
Average molecular weight Mn=1000 g/mol and the viscosity is 500
mPas at 25.degree. C. and the functionality is 4. Esacure
KIP100F=Photoinitiator (100%) is available from Lamberti. Irgacure
819=Photoinitiator (100%) is available from Ciba. EtAc=Ethyl
acetate
EtOH=Ethanol
[0124] Solsperse 20000=surfactant available from Noveon Solsperse
12000=surfactant available from Noveon Nitrocellulose 3.5
DLX=available from ICI Sunfast Blue=pigment available from Sun
Chemical
Compositions (Non-Pigmented)
[0125] Compositions of the invention (Examples 2, 3, 5, and 6) and
comparative compositions (Comparative examples C1 and C4) were
prepared by mixing the components as shown below in Table 1.
TABLE-US-00001 TABLE 1 Example C1 2 3 C4 5 6 Components (wt %)
NeoRez U-347 60 48.4 48.4 0 0 0 NeoRez U-335 0 0 0 100 80.6 80.6
Craynor CN104 0 15.5 0 0 15.5 0 Ebecryl 8210 0 0 15.5 0 0 15.5
Esacure KIP 100F (40% in IPA) 0 3.9 3.9 0 3.9 3.9 Ethyl
acetate/ethanol (3/1 wt) 40 32.2 32.2 0 0 0 Total 100 100 100 100
100 100 Solids % 45 51.8 51.8 45 51.8 51.8
Inks (Pigmented)
[0126] Inks comprising compositions of the invention and
comparative compositions were prepared by mixing the components as
shown below in Table 2.
TABLE-US-00002 TABLE 2 Example C7 8 9 C10 11 12 13 Composition
components (wt %) NeoRez U-347 60 43.4 43.4 0 0 0 0 NeoRez U-335 0
0 0 38 27.5 27.5 34.4 Craynor CN104 0 13.8 0 0 5.3 0 0 Ebecryl 8210
0 0 13.8 0 0 5.3 0 Ebecryl 810 0 0 0 0 0 0 6.6 Irgacure 819 0 13.8
13.8 0 5.3 5.3 6.6 (10% in EtAc/EtOH) EtAc/EtOH (3/1 wt) 40 29 29
62 61.9 61.9 52.4 Total 100 100 100 100 100 100 100 Viscosity mPa s
35 29 26 36 21 21 34 Ink components (wt %) Composition 70 70 70 70
70 70 70 Nitrocellulose blue paste 30 30 30 30 30 30 30 Total 100
100 100 100 100 100 100 Solids level % 40.0 41.8 41.8 20.4 21.1
21.1 24.5 Viscosity mPa s 38 33 30 40 30 30 40 * Nitrocellulose
blue paste (parts by weight) = EtAc (55.9%), EtOH (15.9%),
Solsperse 20000 (2.2%), Solsperse 12000 (0.4%), Nitrocellulose 3.5
DLX (8.0%) Sunfast Blue (17.6%) Final solids content 28%.
[0127] Examples C1 to 6 were further diluted with ethyl
acetate/ethanol (3/1) to attain a viscosity level of about 20 to 50
mPas. Examples C1 to 6 and inks C7 to 12 were then applied on
various substrates (cardboard, PET, PE-white, MB-400) using a 12
micron wire rod. Directly after application the wet films were
dried for 10 seconds at 80.degree. C.
[0128] The UV curable material containing examples (2, 3, 5, 6, 8,
9, 11, 12) were subsequently cured by UV radiation using the
following conditions: 2.times.200 mJ/cm.sup.2 at 240 nm for the
non-pigmented examples (2, 3, 5, 6) and 2.times.300 mJ/cm.sup.2 at
420 nm for the blue ink examples (8, 9, 11, 12).
[0129] All of the obtained films were examined for gloss, adhesion,
block resistance, chemical resistances, dry wrinkle, wet wrinkle
and resolubility. Test results are given below in Table 3 and
4.
Dry Wrinkle Test
[0130] A 12 .mu.m thick wet film formulation was cast onto Corona
treated white polyethylene (LDPE) film available from Oerlemans
Plastics BV (Genderen, NL). This was dried for 10 seconds at
80.degree. C. and then at least one day (to maximum of five days)
at room temperature (20 to 25.degree. C.). The dried film is folded
for at least five times (in a concertina fashion) and wrinkled for
10 seconds. The sensitivity towards dry wrinkle is assessed by
determining the degree of coating damage (5=very good: coating is
undamaged; 1=very poor: formulation is completely removed).
Wet Wrinkle Test
[0131] The wet wrinkle test proceeds according the dry wrinkle
test, only that in this case the dried film is placed for 20
minutes in a beaker filled with cold water, after which the wrinkle
test is immediately performed. The wrinkling is performed for 10
seconds under cold water.
Resolubility
[0132] The composition of the invention or the formulated ink was
cast onto a test card and dried for 1 hour at room temperature. A
drop of the same ink formulation was put on the dried film. After a
period of time (e.g. 5 seconds), the drop was removed with a wet
tissue. This period of time was then increased until the dried film
was completely redissolved by the drop i.e. resolubility of the
formulation had occurred and the time needed to completely
resolubilise the formulation was measured.
Block Resistance
[0133] The degree of blocking of a coating against the same coating
(lacquer to lacquer or L/L blocking) or lacquer to backside of the
substrate (L/B) was assessed with a Koehler Block tester (ex
Instrument Company Inc.). The blocking resistance of dried films
(10 seconds at 80.degree. C.) is measured after 16 hrs in an oven
at 52.degree. C. under a pressure of 1 kg/cm.sup.2. Printed
substrates (with a 12 .mu.m wet coating of the composition of the
invention) were cut into small pieces of 30.times.100 mm and folded
twice so that lacquer against lacquer and lacquer against substrate
backside was tested. The degree of blocking was determined on the
ease of pulling the two test specimens apart and assessing the
coating for any damage. (5 very good=entirely separated and
undamaged. 4=fair, some sticking, hardly any damage. 3=mediocre.
2=poor. 1=very poor, stuck together; once pulled apart, they are
both completely damaged.)
Adhesion
[0134] A self adhesive tape (Sellotape.TM. 25 mm from Henkel
Consumer Adhesives or Scotch.TM. tape 20 mm from 3M) was applied
under uniform pressure onto a printed ink layer on a substrate
immediately after drying of the layer and torn off the substrate
immediately thereafter. The quantity of the print adhered to the
tape was classified with a scale from 0 to 5, where 0 means more
than 95% of the printed layer adhered to the tape, 1 means more
than 50% of the layer adhered to the tape, 2 means less than 30%,
of the printed layer adhered to the tape, 3 means less than 20% of
the printed layer adhered to the tape, 4 means less than 10% of the
printed layer adhered to the tape and 5 means less than 2% of the
printed film adhered to the tape.
Substrates that may be used for this test are: MB 400, co-extruded
bioriented polypropylene (Mobil) PET foil PASD 0.10 mm (from SIHL
Benelux) PE-white (LDPE, from Oerlemans Plastics BV, Genderen NL),
which was corona treated with a Vetaphone ET-1, 300 W at 15 m/min
and about 2 mm distance between the substrate and the
corona-treater.
Chemical Resistance Test
[0135] A 12 .mu.m thick wet film formulation was cast onto a Leneta
test card and dried for 10 seconds at 80.degree. C. and then for at
least 2 hours at approximately 20.degree. C. A small piece of
cotton wool was placed on the dried film, which was then soaked
with the test liquid, such as demineralised water, alcohol/water
(30/70) mixture, coffee or squalane. The soaked pieces of cotton
wool were then covered by a petri-dish to prevent drying out. After
16 hours the pieces of cotton wool and residual liquid were removed
and the degree of coating damage was determined (5=very good: no
visible damage or degradation/discoloration; 4=only slight visible
damage or haze/blooming; 3=clear haze/blooming or damage; 2=coating
partially dissolved; 1=very poor: coating is (almost) completely
dissolved).
Gloss
[0136] A 12 .mu.m thick wet film formulation was cast onto a Leneta
test card and dried for 10 seconds at 80.degree. C. and then for at
least a 2 hours at approximately 20.degree. C. The gloss level of
the dried film was determined using a Byk Gardner micro-TRI-gloss
device set at an angle of 20 degrees or 60 degrees.
TABLE-US-00003 TABLE 3 Example C1 2 3 C4 5 6 Gloss 20.degree. 40 60
71 60 54 47 60.degree. 81 90 92 87 90 85 Adhesion (Sellotape .TM.
25 mm*/Scotch .TM. tape 20 mm) PE-white 1/1 5/5 5/5 4/1 5/5 5/5 MB
400 (*) 1 5 5 4 5 5 PET 1/1 5/5 5/5 4/1 5/5 5/5 Block resistance
PE-white (L-B/L-L) 1/1 4/3 4/4 1/1 4/4 4/4 MB-400 (L-B/L-L) 1/1 4/2
4/4 1/1 4/2 4/1 Chemical resistances Demineralised water 1 5 5 3 5
4-5 Squalane 1 5 5 5 5 5 Butter 1 5 5 2 5 4-5 Dry wrinkle
(PE-white) 1 5 5 1 5 5 Wet wrinkle (PE-white) 1 5 5 1 5 5
TABLE-US-00004 TABLE 4 C7 8 9 C10 11 12 Gloss 20.degree. 37 40 43
19 16 15 60.degree. 75 81 82 60 61 59 Adhesion (Sellotape .TM. 25
mm*/Scotch .TM. tape 20 mm) PE-white 2/2 5/5 5/5 5/2 5/5 5/5 MB 400
(*) 2 5 5 5 5 5 PET 2/2 5/5 5/5 5/2 5/5 5/5 Block resistance
PE-white (L-B/L-L) 1/1 4/4 4/4 4/1 5/4 5/4 MB-400 (L-B/L-L) 1/1 5/3
5/2 4/1 5/4 5/3-4 Chemical resistances Demineralised water 2 4 4 3
3 3 Ethanol/water (30/70) 2 5 4 2 2 2 Squalane 4 5 5 5 5 4-5 Butter
3 4-5 4 4 4 4 Dry wrinkle (PE white) 1 3-4 4 2-3 4-5 4-5 Wet
wrinkle (PE white) 1 2-3 3-4 1 2-3 2-3 Resolubility (s) <5 <5
<5 <5 <5 <5
Printability
[0137] Printability properties were determined with a K-control
coater type K-101 with an anilox application device. The
printability of the ink was determined by assessing the rheology of
the applied dry ink layer (ink flow behaviour and ink layer
appearance), wetting behaviours on the selected substrate and ink
transfer from the anilox onto the rubber roller which was used to
print the ink onto the substrate.
[0138] The overall printability on a clean polyethylene film was
determined using a scale from 0 to 5, with 5 being the best result.
The results are shown below in Table 5 below.
Cob Webbing
[0139] Using a pipette five drops of blue ink compositions prepared
as described above were put onto clean polyethylene film. The drops
were cast immediately with a flexographic hand roller which was
rolled 5 times (up and down), under a spot suction. The cob webbing
tendency was observed during the application.
[0140] After 5 minutes, the appearance of the ink applied onto the
polyethylene film was judged with respect the amount of ink which
is removed from the substrate, indicating different evolution of
tack among the versions. The results are shown below in Table
5.
[0141] The scale used was 0 to 5, with 5 being the best result.
TABLE-US-00005 TABLE 5 Example C7 8 9 C10 13 Printability 5 5 5 5 5
Cob webbing 5 5 5 3 4
[0142] An advantage of the composition of the invention when
compared with the poyurethane component on its own is that higher
solids levels are attainable, this is shown below in Table 6. The
blends were diluted with EtAc/EtOH (3/1) to attain the required
viscosities.
TABLE-US-00006 TABLE 6 Example C14 15 C16 17 Components (wt %)
NeoRez U-347 100 70 0 0 NeoRez U-335 0 0 100 70 Ebecryl 810 0 30 0
30 Total 100 100 100 100 Solids level (wt %) at a given viscosity
(25.degree. C.) 100 mPa s 55 64 23 30 250 mPa s 63 72 29 37 500 mPa
s 68 75 34 43 1000 mPa s 73 80 38 47
* * * * *