U.S. patent application number 11/785973 was filed with the patent office on 2007-08-30 for urethane-acrylic coatings for optical fiber.
This patent application is currently assigned to DSM N.V.. Invention is credited to Wendell W. Cattron, Xiaosong Wu.
Application Number | 20070203321 11/785973 |
Document ID | / |
Family ID | 22991186 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070203321 |
Kind Code |
A1 |
Cattron; Wendell W. ; et
al. |
August 30, 2007 |
Urethane-acrylic coatings for optical fiber
Abstract
The present invention relates to a method of improving the
tensile, elongation, and/or modulus (overall toughness) of a
radiation curable composition by reacting in a free
multi-functional isocyanate prior to curing.
Inventors: |
Cattron; Wendell W.; (Iron
Station, NC) ; Wu; Xiaosong; (Gastonia, NC) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DSM N.V.
TE HEERLEN
NL
|
Family ID: |
22991186 |
Appl. No.: |
11/785973 |
Filed: |
April 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10042382 |
Jan 11, 2002 |
7226958 |
|
|
11785973 |
Apr 23, 2007 |
|
|
|
60260915 |
Jan 12, 2001 |
|
|
|
Current U.S.
Class: |
528/44 |
Current CPC
Class: |
C03C 25/106 20130101;
G02B 6/4402 20130101; C09D 175/16 20130101; C08F 290/06 20130101;
C09D 4/06 20130101; C03C 25/1065 20130101; G02B 6/4482 20130101;
C09D 4/06 20130101 |
Class at
Publication: |
528/044 |
International
Class: |
C08G 18/00 20060101
C08G018/00 |
Claims
1-21. (canceled)
22. A method of improving the tensile strength, modulus, and/or
elongation of a radiation-curable composition comprising: adding a
multi-functional isocyanate to the composition prior to curing.
23. The method according to claim 22, further comprising reacting
at least a portion of the added multi-functional isocyanate with a
hydroxyl-functional mono(meth)acrylate.
24. A composition obtainable by the method according to any one of
claims 22-23.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of commonly owned copending
U.S. application Ser. No. 10/042,382, filed on Jan. 11, 2002 (now
allowed), which claims the benefit of U.S. provisional application
60/260,915 which was filed on Jan. 12, 2001, and which is hereby
incorporated in its entirety by reference.
FIELD OF THE INVENTION
[0002] The present invention relates, inter alia, to fiber optic
coating compositions having improved toughness. Furthermore, the
present invention relates to a method of improving the tensile,
modulus, and/or elongation of a radiation curable coating
composition by adding a free isocyanate.
BACKGROUND OF THE INVENTION
[0003] In the production of optical fibers, a resin coating is
applied immediately after drawing of the glass fibers for
protection and reinforcement of the glass fiber. Generally, two
coatings are applied, a soft primary coating layer of a flexible
resin (low modulus and low Tg) which is coated directly on the
glass surface and a secondary coating layer of a rigid resin
(higher modulus and higher Tg) which is provided over the primary
coating layer. Often, for identification purposes, the fibers will
be colored. Accordingly, the fibers may further be coated with an
ink, which generally is a curable resin comprising a colorant (such
as a pigment and/or a dye), or the secondary coating may be a
colored secondary coating (i.e., comprise a colorant).
[0004] Several coated (and optionally inked) optical fibers can be
bundled together to form a so-called optical fiber ribbon, e.g.,
four or eight coated (and optionally inked) optical fibers are
arranged on a plane and secured with a binder to produce a ribbon
structure having a rectangular cross section. Said binder material
for binding several optical fibers to produce the optical fiber
ribbon structure is called a ribbon matrix material. In addition, a
material for the further binding of several optical fiber ribbons
to produce multi-core optical fiber ribbons is called a bundling
material.
[0005] Resins that cure on exposure to radiation such as
ultraviolet radiation are favored in the industry, due to their
fast cure, enabling the coated fiber to be produced at high speed.
In many of these radiation curable resin compositions, use is made
of urethane oligomers having reactive terminal groups (such as an
acrylate or methacrylate functionality, herein referred to as
(meth)acrylate functionality) and a polymer backbone. Generally,
these compositions may further comprise reactive diluents,
photoinitiators, and optionally suitable additives.
[0006] It is a continual objective of the industry to improve the
performance of the coatings. Among the many performance
characteristics required of the coating systems, the tensile
strength, modulus and elongation are important. Accordingly,
formulators add components to the composition to manipulate these
characteristics.
[0007] The applicants have discovered that they can introduce a
free multi-functional isocyanate either directly mixed with the
multi-functional acrylate or into the final composition, prior to
curing, and thereby improve tensile, elongation, and/or modulus
properties, in the composition. Applicants have furthermore
discovered that the addition of relatively small amounts of
aromatic urethane acrylate components can also give improved
mechanical properties.
SUMMARY OF THE INVENTION
[0008] The present invention provides a method of improving the
tensile, elongation, and/or modulus (overall toughness) of a
radiation curable composition by reacting in a free
multi-functional isocyanate prior to curing.
[0009] The present invention further provides a method of improving
the tensile, elongation, and/or modulus (overall toughness) of a
radiation curable composition by having relative small amounts
aromatic urethane acrylate components present.
[0010] In addition, the present invention provides compositions
comprising [0011] (i) a component according to the following
formula (a) A-X.sub.1-A (a) [0012] wherein [0013] A represents a
(meth)acrylate group; and [0014] X.sub.1 represents an aliphatic or
aromatic group; and [0015] (ii) a urethane (meth)acrylate component
comprising a (meth)acrylate group, X.sub.1, and a residue of a
multifunctional isocyanate.
[0016] The inventors have found, that the components as supplied by
raw material manufacturers, often comprise undesired by-products or
side-products ("impurities"), which may lessen one or more of the
effects the components are supposed to accomplish. For instance,
multi-functional acrylate components (such as ethoxylated Bisphenol
A diacrylate) often are inclusive of minor amounts of
monofunctional acrylates (such as ethoxylated Bisphenol A mono
acrylate) which effect the overall performance properties of the
coatings. The present invention comprises the step of converting at
least a portion of the mono-functional components to
multi-functional components, and therewith improve properties.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0017] Multi-functional refers to a compound having at least two
functional groups. For example, multifunctional acrylate or
multi-functional isocyanate refers to an acrylate or an isocyanate
compound having at least 2, preferably 2-3, acrylate or isocyanate
groups, respectively.
[0018] The radiation-curable composition of present invention may
be formulated using any suitable components and processes used for
such purposes. Typcially, the coatings will be (meth)acrylate
radiation curable compositions preferably having, relative to the
total weight of the composition, more than 90% acrylate-functional
components.
[0019] The radiation curable composition preferably comprises a
radiation curable oligomer and a radiation curable diluent. Each of
the components may be mono or polyfunctional, poly meaning 2 or
more functional. Generally, the functionality of the radiation
curable components is 12 or lower. Preferred functionality for at
least one of the components is on average 1.8-4.
[0020] The terms diluent and oligomer are used in this
specification to denote a compound with lower, respectively, higher
viscosity. The oligomer generally will have a molecular weight of
about 400 or higher and an average functionality of about 1.2 or
higher, preferably an average functionality of about 1.8-4.
[0021] The reactive diluent has a viscosity that is lower than the
viscosity of the oligomer. In case an oligomer is used with high
viscosity, the diluent may have a molecular weight up to about
700.
(A) Oligomer
[0022] Generally, optical fiber coating materials comprise as an
oligomer a urethane acrylate oligomer, comprising an acrylate
group, urethane groups and a backbone. The backbone is derived from
a polyol which has been reacted with a diisocyanate and
hydroxyalkylacrylate. However, urethane-free ethylenically
unsaturated oligomers such as polyester acrylates may also be
used.
[0023] Examples of suitable polyols are polyether polyols,
polyester polyols, polycarbonate polyols, polycaprolactone polyols,
acrylic polyols, and other polyols. These polyols may be used
either individually or in combinations of two or more. There are no
specific limitations to the manner of polymerization of the
structural units in these polyols. Any of random polymerization,
block polymerization, or graft polymerization is acceptable.
[0024] Given as examples of the polyether polyols are polyethylene
glycol, polypropylene glycol, polypropylene glycol-ethyleneglycol
copolymer, polytetramethylene glycol, polyhexamethylene glycol,
polyheptamethylene glycol, polydecamethylene glycol, and polyether
diols obtained by ring-opening copolymerization of two or more
ion-polymerizable cyclic compounds. Here, given as examples of the
ion-polymerizable cyclic compounds are cyclic ethers such as
ethylene oxide, isobutene oxide, tetrahydrofuran,
2-methyltetrahydrofuran, 3-methyltetrahydrofuran, dioxane,
trioxane, tetraoxane, cyclohexene oxide, styrene oxide,
epichlorohydrin, isoprene monoxide, vinyl oxetane, vinyl
tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether,
butyl glycidyl ether, and glycidyl benzoate. Specific examples of
combinations of two or more ion-polymerizable cyclic compounds
include combinations for producing a binary copolymer such as
tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and
3-methyltetrahydrofuran, and tetrahydrofuran and ethylene oxide;
and combinations for producing a ternary copolymer such as a
combination of tetrahydrofuran, 2-methyltetrahydrofuran, and
ethylene oxide, a combination of tetrahydrofuran, butene-1-oxide,
and ethylene oxide, and the like. The ring-opening copolymers of
these ion-polymerizable cyclic compounds may be either random
copolymers or block copolymers.
[0025] Included in these polyether polyols are products
commercially available under the trademarks, for example, PTMG1000,
PTMG2000 (manufactured by Mitsubishi Chemical Corp.), PEG#1000
(manufactured by Nippon Oil and Fats Co., Ltd.), PTG650 (SN),
PTG1000 (SN), PTG2000 (SN), PTG3000, PTGL1000, PTGL2000
(manufactured by Hodogaya Chemical Co., Ltd.), PEG400, PEG600,
PEG1000, PEG1500, PEG2000, PEG4000, PEG6000 (manufactured by
Daiichi Kogyo Seiyaku Co., Ltd.) and Pluronics (by BASF).
[0026] Polyester diols obtained by reacting a polyhydric alcohol
and a polybasic acid are given as examples of the polyester
polyols. As examples of the polyhydric alcohol, ethylene glycol,
polyethylene glycol, tetramethylene glycol, polytetramethylene
glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol,
2-methyl-1,8-octanediol, and the like can be given. As examples of
the polybasic acid, phthalic acid, dimer acid, isophthalic acid,
terephthalic acid, maleic acid, fumaric acid, adipic acid, sebasic
acid, and the like can be given.
[0027] These polyester polyol compounds are commercially available
under the trademarks such as MPD/IPA500, MPD/IPA1000, MPD/IPA2000,
MPD/TPA500, MPD/TPA1000, MPD/TPA2000, Kurapol A-1010, A-2010,
PNA-2000, PNOA-1010, and PNOA-2010 (manufactured by Kuraray Co.,
Ltd.).
[0028] As examples of the polycarbonate polyols, polycarbonate of
polytetrahydrofuran, poly(hexanediol carbonate), poly(nonanediol
carbonate), poly(3-methyl-1,5-pentamethylene carbonate), and the
like can be given.
[0029] As commercially available products of these polycarbonate
polyols, DN-980, DN-981 (manufactured by Nippon Polyurethane
Industry Co., Ltd.), Priplast 3196, 3190, 2033 (manufactured by
Unichema), PNOC-2000, PNOC-1000 (manufactured by Kuraray Co.,
Ltd.), PLACCEL CD220, CD210, CD208, CD205 (manufactured by Daicel
Chemical Industries, Ltd.), PC-THF-CD (manufactured by BASF), and
the like can be given.
[0030] Polycaprolactone diols obtained by reacting e-caprolactone
and a diol compound are given as examples of the polycaprolactone
polyols having a melting point of 0.degree. C. or higher. Here,
given as examples of the diol compound are ethylene glycol,
polyethylene glycol, polypropylene glycol, polypropylene glycol,
tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene
glycol, 1,6-hexanediol, neopentyl glycol,
1,4-cyclohexanedimethanol, 1,4-butanediol, and the like.
[0031] Commercially available products of these polycaprolactone
polyols include PLACCEL 240, 230, 230ST, 220, 220ST, 220NP1, 212,
210, 220N, 210N, L230AL, L220AL, L220PL, L220PM, L212AL (all
manufactured by Daicel Chemical Industries, Ltd.), Rauccarb 107 (by
Enichem), and the like.
[0032] As examples of other polyols ethylene glycol,
1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, polyoxyethylene
bisphenol A ether, polyoxypropylene bisphenol A ether,
polyoxyethylene bisphenol F ether, polyoxypropylene bisphenol F
ether, and the like can be given.
[0033] As these other polyols, those having a alkylene oxide
structure in the molecule, in particular polyether polyols, are
preferred. Specifically, polyols containing polytetramethylene
glycol and copolymer glycols of butyleneoxide and ethyleneoxide are
particularly preferred.
[0034] The reduced number average molecular weight derived from the
hydroxyl number of these polyols is usually from about 50 to about
15,000, and preferably from about 1,000 to about 8,000.
[0035] Given as examples of the polyisocyanate used for the
oligomer are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate,
1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene
diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate,
4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene
diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane
diisocyanate, isophorone diisocyanate,
methylenebis(4-cyclohexylisocyanate), 2,2,4-trimethylhexamethylene
diisocyanate, bis(2-isocyanato-ethyl)fumarate,
6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane
diisocyanate, hydrogenated diphenylmethane diisocyanate,
hydrogenated xylylene diisocyanate, tetramethyl xylylene
diisocyanate, lysine isocyanate, and the like. These polyisocyanate
compounds may be used either individually or in combinations of two
or more. Preferred polyisocyanates are isophorone diisocyanate,
2,2,4-trimethylhexamethylene diisocyanate, 2,4-tolylene
diisocyanate, and 2,6-tolylene diisocyanate.
[0036] Examples of the hydroxyl group-containing (meth)acrylate
used in the oligomer, include, (meth)acrylates derived from
(meth)acrylic acid and epoxy and (meth)acrylates comprising
alkylene oxides, more in particular, 2-hydroxy ethyl
(meth)acrylate, 2-hydroxypropylacrylate and
2-hydroxy-3-oxyphenyl(meth)acrylate. Acrylate functional groups are
preferred over methacrylates.
[0037] The ratio of polyol, polyisocyanate, and hydroxyl
group-containing (meth)acrylate used for preparing the urethane
(meth)acrylate is determined so that about 1.1 to about 3
equivalents of an isocyanate group included in the polyisocyanate
and about 0.1 to about 1.5 equivalents of a hydroxyl group included
in the hydroxyl group-containing (meth)acrylate are used for one
equivalent of the hydroxyl group included in the glycol.
[0038] In the reaction of these three components, a urethanization
catalyst such as copper naphthenate, cobalt naphthenate, zinc
naphthenate, di-n-butyl tin dilaurate, triethylamine, and
triethylenediamine-2-methyltriethyleneamine, is usually used in an
amount from about 0.01 to about 1 wt % of the total amount of the
reactant. The reaction is carried out at a temperature from about
10 to about 90.degree. C., and preferably from about 30 to about
80.degree. C.
[0039] The number average molecular weight of the urethane
(meth)acrylate used in the composition of the present invention is
preferably in about 500 or higher, more preferably 800 or higher,
and particularly preferred 1,200 g/mol or higher. Generally, the
molecular weight is about 20,000 g/mol or lower, and more
preferably about 10,000 g/mol or lower. If the number average
molecular weight of the urethane (meth)acrylate is less than about
100 g/mol, the resin composition tends to solidify; on the other
hand, if the number average molecular weight is larger than about
20,000 g/mol, the viscosity of the composition becomes high, making
handling of the composition difficult. Particularly preferred for
outer primary coatings inks or matrix materials are oligomers
having a number average molecular weight between about 800 and
about 4,000 g/mol.
[0040] The urethane (meth)acrylate is used in an amount of 5% or
more, preferably from about 10 wt % or more, and more preferably
from about 20 wt % or more, of the total amount of the resin
composition. Generally, the amount of urethane(meth)acrylate
oligomer is about 90% or less, preferably about 80 wt % or less.
When the composition is used as a coating material for optical
fibers, the range from about 20 to about 80 wt % is particularly
preferable to ensure excellent coatability, as well as superior
flexibility and long-term reliability of the cured coating.
[0041] Other oligomers that can be used include polyester
(meth)acrylate, epoxy (meth)acrylate, polyamide (meth)acrylate,
siloxane polymer having a (meth)acryloyloxy group, a reactive
polymer obtained by reacting (meth)acrylic acid and a copolymer of
glycidyl methacrylate and other polymerizable monomers, and the
like. Particularly preferred are bisphenol A based acrylate
oligomers such as alkoxylated bisphenol-A-diacrylate and
diglycidyl-bisphenol-A-diacrylate.
[0042] Beside the above-described components, other curable
oligomers or polymers may be added to the liquid curable resin
composition of the present invention to the extent that the
characteristics of the liquid curable resin composition are not
adversely affected.
[0043] Preferred oligomers are polyether based acrylate oligomers,
polycarbonate acrylate oligomers, polyester acrylate oligomers,
alkyd acrylate oligomers and acrylated acrylic oligomers. More
preferred are the urethane-containing oligomers thereof. Even more
preferred are polyether urethane acrylate oligomers and urethane
acrylate oligomers using blends of the above polyols, and
particularly preferred are aliphatic polyether urethane acrylate
oligomers. The term "aliphatic" refers to a wholly aliphatic
polyisocyanate used. However, also urethane-free acrylate
oligomers, such as urethane-free acrylated acrylic oligomers,
urethane-free polyester acrylate oligomers and urethane-free alkyd
acrylate oligomers are also preferred.
(B) Reactive Diluent
[0044] Suitable reactive diluents include those exemplified herein
below.
[0045] Polymerizable vinyl monomers such as polymerizable
monofunctional vinyl monomers containing one polymerizable vinyl
group in the molecule and polymerizable polyfunctional vinyl
monomers containing two or more polymerizable vinyl groups in the
molecule may be added to the liquid curable resin composition of
the present invention.
[0046] Given as specific examples of the polymerizable
monofunctional vinyl monomers are vinyl monomers such as N-vinyl
pyrrolidone, N-vinyl caprolactam, vinyl imidazole, and vinyl
pyridine; (meth)acrylates containing an alicyclic structure such as
isobornyl (meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl
(meth)acrylate, dicyclopehtanyl (meth)acrylate, dicyclopentenyl
(meth)acrylate, and cyclohexyl (meth)acrylate; benzyl
(meth)acrylate, 4-butylcyclohexyl (meth)acrylate,
acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl
(meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl
(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,
isopropyl (meth)acrylate, butyl (meth)acrylate, amyl
(meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate,
pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl
(meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate,
isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl
(meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate,
undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl
(meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate,
tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate,
ethoxydiethylene glycol (meth)acrylate, benzyl(meth)acrylate,
phenoxyethyl(meth)acrylate, polyethylene glycol mono(meth)acrylate,
polypropylene glycol mono(meth)acrylate, methoxyethylene glycol
(meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene
glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate,
diacetone(meth)acrylamide, isobutoxy methyl(meth)acrylamide,
N,N-dimethyl(meth)acrylamide, t-octyl(meth)acrylamide,
dimethylaminoethyl (meth)acrylate, diethylaminoethyl
(meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate,
N,N-diethyl(meth)acrylamide, N,N-dimethyl amino
propyl(meth)acrylamide, hydroxy butyl vinyl ether, lauryl vinyl
ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, acrylate
monomers shown by the following formulas (1) to (3), ##STR1##
wherein R.sup.7 is a hydrogen atom or a methyl group, R.sup.8 is an
alkylene group having 2-6, and preferably 2-4 carbon atoms, R.sup.9
is a hydrogen atom or an organic group containing 1-12 carbon atoms
or an aromatic ring, and r is an integer from 0 to 12, and
preferably from 1 to 8, ##STR2## wherein R.sup.7 is the same as
defined above, R.sup.10 is an alkylene group having 2-8, and
preferably 2-5 carbon atoms, and q is an integer from 1 to 8, and
preferably from 1 to 4, ##STR3## wherein R.sup.7, R.sup.10, and q
are the same as defined above.
[0047] As examples of commercially available products of the
polymerizable monofunctional vinyl monomers, Aronix M102, M110,
M111, M113, M117 (manufactured by Toagosei Co., Ltd.), LA, IBXA,
Viscoat #190, #192, #2000 (manufactured by Osaka Organic Chemical
Industry Co., Ltd.), Light Acrylate EC-A, PO-A, NP-4EA, NP-8EA,
M-600A, HOA-MPL (manufactured by Kyoeisha Chemical Co., Ltd.),
KAYARAD TC110S, R629, R644 (manufactured by Nippon Kayaku Co.,
Ltd.), and the like can be given.
[0048] Given as examples of the polymerizable polyfunctional vinyl
monomers are the following acrylate compounds: trimethylolpropane
tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene
glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate,
polyethylene glycol di(meth)acrylate, 1,4-butanediol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol
di(meth)acrylate, trimethylolpropanetrioxyethyl (meth)acrylate,
tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate,
tris(2-hydroxyethyl)isocyanurate di(meth)acrylate,
bis(hydroxymethyl)tricyclodecane di(meth)acrylate, di(meth)acrylate
of a diol which is an addition compound of ethylene oxide or
propylene oxide to bisphenol A, di(meth)acrylate of a diol which is
an addition compound of ethylene oxide or propylene oxide to
hydrogenated bisphenol A, epoxy(meth)acrylate obtained by the
addition of (meth)acrylate to diglycidyl ether of bisphenol A,
diacrylate of polyoxyalkylene bisphenol A, and triethylene glycol
divinyl ether.
[0049] Examples of commercially available products of the
polymerizable polyfunctional vinyl monomers include Yupimer UV
SA1002, SA2007 (manufactured by Mitsubishi Chemical Corp.), Viscoat
#195, #230, #215, #260, #335HP, #295, #300, #700 (manufactured by
Osaka Organic Chemical Industry Co., Ltd.), Light Acrylate 4EG-A,
9EG-A, NP-A, DCP-A, BP-4EA, BP-4PA, PE-3A, PE-4A, DPE-6A
(manufactured by Kyoeisha Chemical Co., Ltd.), KAYARAD R-604,
DPCA-20,-30,-60,-120, HX-620, D-310, D-330 (manufactured by Nippon
Kayaku Co., Ltd.), Aronix M-208, M-210, M,-215, M-220, M-240,
M-305, M-309, M-315, M-325 (manufactured by Toagosei Co., Ltd.),
and the like.
[0050] These polymerizable vinyl monomers are used in an amount
from about 10 to about 70 wt %, and preferably from about 15 to
about 60 wt %, of the total amount of the resin composition. If the
amount is less than about 10 wt %, the viscosity of the composition
is so high that coatability is impaired. The amount exceeding about
70 wt % may result in not only an increased cure shrinkage, but
also insufficient toughness of the cured products.
[0051] Preferred reactive diluents include alkoxylated alkyl
substituted phenol acrylate, such as ethoxylated nonyl phenol
acrylate, vinyl monomers such as vinyl caprolactam, isodecyl
acrylate, and alkoxylated bisphenol A diacrylate such as
ethoxylated bisphenol A diacrylate.
(C) Specific Combination of Components
[0052] Preferably, the present compositions comprise: [0053] (i) a
component represented by the following formula (a) A-X.sub.1-A (a)
[0054] wherein [0055] A represents a (meth)acrylate group,
preferably an acrylate group; and [0056] X.sub.1 represents an
aliphatic or aromatic group, preferably having a molecular weight
below 750, more preferably below 500, most preferably less than 350
g/mol; and [0057] (ii) a urethane (meth)acrylate component
comprising a (metha)acrylate group (preferably an acrylate group),
X.sub.1, and a residue of a multifunctional isocyanate (preferably
a residue of a diisocyanate).
[0058] Component (ii) may be a urethane (meth)acrylate component
represented by the following formula (b); X.sub.2--I--X.sub.2 (b)
[0059] wherein I represents a diisocyanate residue and X.sub.2
represents a residue of a component represented by the following
formula (c): A-X.sub.1--OH (c).
[0060] Accordingly, X.sub.2 represents a residue of a
hydroxyfunctional (meth)acrylate.
[0061] Preferably X.sub.1 comprises one or more aromatic rings,
preferably 2 aromatic rings. The one or more aromatic rings are
preferably present in X.sub.1 as phenolic residues. It is also
preferred that X.sub.1 comprises one or more alkoxy groups (e.g.
1-20, 1-10, or 2-6 alkoxy groups), for instance ethoxy and/or
propoxy groups.
[0062] Preferably, A-X.sub.1-A represents a bisphenol diacrylate,
for instance a bisphenol A diacrylate such as an alkoxylated (e.g.
ethoxylated and/or propoxylated) bisphenol A diacrylate.
[0063] Component (ii) may be prepared by reacting at least part of
the hydroxyfunctional side-products, that may be present in a
sample of A-X.sub.1-A, with one or more suitable diisocyanates.
Therewith, hydroxyfunctional impurities (side products) can be
converted into difunctional components. This conversion may be done
in situ, i.e. by simply adding diisocyanate to a composition
comprising several components, one of which being a component
represented by A-X.sub.1-A. The conversion may also be effected by
first adding diisocyanate to a sample of A-X.sub.1-A, reacting
diisocyanate with hydroxyfunctional impurities present in the
sample, and then adding the sample to the composition.
[0064] Suitable diisocyanates include, for example 2,4-tolylene
diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate,
1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate,
m-phenylene diisocyanate, p-phenylene diisocyanate,
3,3'-dimethyl-4,4'-diphenylmethane diisocyanate,
4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene
diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane
diisocyanate, isophorone diisocyanate,
methylenebis(4-cyclohexylisocyanate), 2,2,4-trimethylhexamethylene
diisocyanate, bis(2-isocyanato-ethyl)fumarate,
6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane
diisocyanate, hydrogenated diphenylmethane diisocyanate,
hydrogenated xylylene diisocyanate, tetramethyl xylylene
diisocyanate, lysine isocyanate, and the like. These polyisocyanate
compounds may be used either individually or in combinations of two
or more. Preferred polyisocyanates include aromatic isocyanates,
particularly tolylene diisocyanates.
(D) Photoinitiator
[0065] When the liquid curable resin composition of the present
invention is cured by radiation, a photo-polymerization initiator
is used.
[0066] In a preferred embodiment of the present invention, the
photoinitiators (Ci) are free radical photoinitiators.
[0067] Free-radical photoinitiators are generally divided into two
classes according to the process by which the initiating radicals
are formed. Compounds that undergo unimolecular bond cleavage upon
irradiation are termed Type I or homolytic photoinitiators, as
shown by formula (1): ##STR4##
[0068] Depending on the nature of the functional group and its
location in the molecule relative to the carbonyl group, the
fragmentation can take place at a bond adjacent to the carbonyl
group (.alpha.-cleavage), at a bond in the .beta.-position
(.beta.-cleavage) or, in the case of particularly weak bonds (like
C--S bonds or O--O bonds), elsewhere at a remote position. By far
the most important fragmentation in photoinitiator molecules is the
.alpha.-cleavage of the carbon-carbon bond between the carbonyl
group and the alkyl residue in alkyl aryl ketones which is known as
the Norrish Type I reaction.
[0069] If the excited state photoinitiator interacts with a second
molecule (a coinitiator COI) to generate radicals in a bimolecular
reaction as shown by formula (2), the initiating system is termed a
Type II photoinitiator. In general, the two main reaction pathways
for Type II photoinitiators are hydrogen abstraction by the excited
initiator or photoinduced electron transfer, followed by
fragmentation. Bimolecular hydrogen abstraction is a typical
reaction of diary ketones. Photoinduced electron transfer is a more
general process which is not limited to a certain class of
compounds. ##STR5##
[0070] Examples of suitable Type I homolytic free-radical
photoinitiators are benzoin derivatives, methylolbenzoin and
4-benzoyl-1,3-dioxolane derivatives, benzilketals,
.alpha.,.alpha.-dialkoxyacetophenones, a-hydroxy alkylphenones,
.alpha.-aminoalkylphenones, acylphosphine oxides, bisacylphosphine
oxides, acylphosphine sulphides halogenated acetophenone
derivatives, and the like. Commercial examples of suitable Type I
photoinitiators are Irgacure 651 (benzildimethyl ketal or
2,2-dimethoxy-1,2-diphenylethanone, Ciba-Geigy),
Irgacure 184 (1-hydroxy-cyclohexyl-phenyl ketone as the active
component, Ciba-Geigy),
Darocur 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one as the active
component, Ciba-Geigy),
Irgacure 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholino
propan-1-one, Ciba-Geigy),
Irgacure 369
(2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one as the
active component, Ciba-Geigy),
Esacure KIP 150 (poly
{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one},
Fratelli Lamberti),
Esacure KIP 100 F (blend of poly
{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one} and
2-hydroxy-2-methyl-1-phenyl-propan-1-one, Fratelli Lamberti),
Esacure KTO 46 (blend of poly
{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one},
2,4,6-trimethylbenzoyldiphenylphosphine oxide and
methylbenzophenone derivatives, Fratelli Lamberti),
acylphosphine oxides such as Lucirin TPO (2,4,6-trimethylbenzoyl
diphenyl phosphine oxide, BASF),
Irgacure 819 (bis (2,4,6-trimethylbenzoyl)-phenyl-phosphine-oxide,
Ciba-Geigy),
[0071] Irgacure 1700 (25:75% blend of bis
(2,6-dimethoxybenzoyl)2,4,4-trimethylpentyl phosphine oxide and
2-hydroxy-2-methyl-1-phenyl-propan-1-one, Ciba-Geigy), and the
like. Also mixtures of type I photoinitiators can be used. For
colored (e.g. pigmented) systems, phosphine oxide type
photoinitiators and Irgacure 907 are preferred.
[0072] Examples of suitable Type-II (hydrogen abstraction)
photoinitiators are aromatic ketones such as benzophenone,
xanthone, derivatives of benzophenone (e.g. chlorobenzophenone),
blends of benzophenone and benzophenone derivatives (e.g. Photocure
81, a 50/50 blend of 4-methyl-benzophenone and benzophenone),
Michler's Ketone, Ethyl Michler's Ketone, thioxanthone and other
xanthone derivatives like Quantacure ITX (isopropyl thioxanthone),
benzil, anthraquinones (e.g. 2-ethyl anthraquinone), coumarin, and
the like. Chemical derivatives and combinations of these
photoinitiators can also be used.
[0073] Type-II photoinitiators generally are used together with an
amine synergist. Preferably, the amine synergist is chosen from the
group consisting of a monomer tertiary amine compound, an oligomer
(polymer) tertiary amine compound, a polymerizable amino acrylate
compound, a polymerized amino acrylate compound and mixtures
thereof.
[0074] The amine-synergist may include tertiary amine compounds,
such as alkanol-dialkylamines (e.g., ethanol-diethylamine),
alkyldialkanolamines (e.g. methyldiethanolamine), trialkanolamines
(e.g. triethanolamine), and ethylenically unsaturated
amine-functional compounds including amine-functional polymer
compounds, copolymerizable amine acrylates, and the like. The
ethylenically unsaturated amine compounds may also include
dialkylamino alkyl(meth)acrylates (e.g., diethylaminoethylacrylate)
or N-morpholinoalkyl-(meth)acrylates (e.g.,
N-morpholinoethyl-acrylate).
[0075] Preferably, the total amount of photoinitiators present is
between about 0.10 wt. % and about 20.0 wt. % relative to the total
amount of the coating composition. More preferably, the total
amount is at least about 0.5 wt. %, particularly preferred, at
least about 1.0 wt. %, and most preferred, at least about 2.0 wt.
%. Moreover, the total amount is preferably less than about 15.0
wt. %, more preferably, less than about 10.0 wt. %, and
particularly preferred, less than about 6.0 wt. %
[0076] Preferably, each of the photoinitiators (Ci) is individually
present in an amount of at least about 0.02 wt. %, more preferably,
at least about 0.05 wt. %, particularly preferred, at least about
0.1 wt. %, and most preferred, at least about 0.15 wt. %. Further,
each photoinitiator (Ci) is individually preferably present in an
amount of about 10.0 wt. % or less, more preferably, about 5.0 wt.
% or less, particularly preferably, about 4.0 wt. % or less, and
most preferred, about 2.5 wt. % or less.
[0077] The ratio C.sub.i:C of the amount of individual
photoinitiator (Ci) to the total amount of photoinitiators (C)
preferably is about 50% or less, more preferably about 45% or less,
particularly preferred about 40% or less, most preferred about 30%
or less. The ratio C.sub.i:C preferably is at least about 2%, more
preferably at least about 5%, particularly preferred at least about
10%.
[0078] It is preferred that at least two of the compounds (Ci) are
homolytic free radical photoinitiators, preferably, at least three,
more preferably, at least four, particularly preferred all the
compounds (Ci) are homolytic free radical photoinitiators.
Moreover, it is preferred that at least two of the compounds (Ci)
are .alpha.-cleavage homolytic free radical photoinitiators, more
preferred, at least three, particularly preferred at least four and
most preferred, all of the compounds (Ci) are of the
.alpha.-cleavage type.
[0079] In one preferred embodiment of the present invention at
least one of the photoinitiators contains a phosphorous, sulfur or
nitrogen atom. It is even more preferred that the photoinitiator
package comprises at least a combination of a photoinitiator
containing a phosphorous atom and a photoinitiator containing a
sulfur atom.
[0080] In another preferred embodiment of the invention, at least
one of the compounds (Ci) is an oligomeric or polymeric
photoinitiator. Besides showing an improved cure speed, said
coating compositions comprising at least one polymeric
photoinitiator (Ci) additionally exhibit, upon cure, improved
release properties from another covering layer, such as a matrix or
bundling material or any other material applied to the surface of
the subject composition.
[0081] The oligomeric photoinitiator can include Esacure KIP 100F,
available form Sartomer Corporation.
(E) Additives
[0082] An amine compound can be added to the liquid curable resin
composition of the present invention to prevent generation of
hydrogen gas, which causes transmission loss in the optical fibers.
As examples of the amine which can be used here, diallylamine,
diisopropylamine, diethylamine, diethylhexylamine, and the like can
be given.
[0083] In addition to the above-described components, various
additives such as antioxidants, UV absorbers, light stabilizers,
silane coupling agents, coating surface improvers, heat
polymerization inhibitors, leveling agents, surfactants, colorants,
preservatives, plasticizers, lubricants, solvents, fillers, aging
preventives, and wettability improvers can be used in the liquid
curable resin composition of the present invention, as required.
Examples of antioxidants include Irganox 1010, 1035, 1076, 1222
(manufactured by Ciba Specialty Chemicals Co., Ltd.), Antigene P,
3C, FR, Sumilizer GA-80 (manufactured by Sumitomo Chemical
Industries Co., Ltd.), and the like; examples of UV absorbers
include Tinuvin P, 234, 320, 326, 327, 328, 329, 213 (manufactured
by Ciba Specialty Chemicals Co., Ltd.), Seesorb 102, 103, 110, 501,
202, 712, 704 (manufactured by Sypro Chemical Co., Ltd.), and the
like; examples of light stabilizers include Tinuvin 292, 144, 622LD
(manufactured by Ciba Specialty Chemicals Co., Ltd.), Sanol LS770
(manufactured by Sankyo Co., Ltd.), Sumisorb TM-061 (manufactured
by Sumitomo Chemical Industries Co., Ltd.), and the like; examples
of silane coupling agents include aminopropyltriethoxysilane,
mercaptopropyltrimethoxy-silane, and
methacryloxypropyltrimethoxysilane, and commercially available
products such as SH6062, SH6030 (manufactured by Toray-Dow Corning
Silicone Co., Ltd.), and KBE903, KBE603, KBE403 (manufactured by
Shin-Etsu, Chemical Co., Ltd.); examples of coating surface
improvers include silicone additives such as dimethylsiloxane
polyether and commercially available products such as DC-57, DC-190
(manufactured by Dow-Corning), SH-28PA, SH-29PA, SH-30PA, SH-190
(manufactured by Toray-Dow Corning Silicone Co., Ltd.), KF351,
KF352, KF353, KF354 (manufactured by Shin-Etsu Chemical Co., Ltd.),
and L-700, L-7002, L-7500, FK-024-90 (manufactured by Nippon Unicar
Co., Ltd.).
[0084] The description on radiation curable compositions can also
apply to colored compositions, being either a colored single, inner
primary, or outer primary composition, an ink composition or a
colored matrix or bundling material. The colorant can be a pigment
or dye. The pigment can be any pigment suitable for use in
pigmented colored optical fiber coatings. Preferably, the pigment
is in the form of small particles and is capable of withstanding
UV-radiation.
[0085] Pigments can be conventional or organic pigments as
disclosed in, for example, Ullman's Encyclopedia of Industrial
Chemistry, 5.sup.th Ed., Vol. A22, VCH Publishers (1993), pages
154-155, the complete disclosure of which is hereby fully
incorporated by reference. The pigment can be selected based on,
for example, whether the composition is a colored secondary, ink
coating or matrix material. Ink coatings are typically more heavily
pigmented.
[0086] General classes of suitable colorants include, among others,
inorganic white pigments, black pigments; iron oxides; chronium
oxide greens; iron blue and chrome green; violet pigments;
ultramarine pigments; blue, green, yellow, and brown metal
combinations; lead chromates and lead molybdates; cadmium pigments;
titane pigments; pearlescent pigments; metallic pigments; monoazo
pigments, diazo pigments; diazo condensation pigments; quinacridone
pigments, dioxazine violet pigment; vat pigments; perylene
pigments; thioindigo pigments; phthalocyanine pigments; and
tetrachloroindolinones; azo dyes; anthraquinone dyes; xanthene
dyes; and azine dyes. Fluorescent pigments can also be used.
[0087] Preferably, the pigment has a mean particle size of not more
than about 1 .mu.m. The particle size of the commercial pigments
can be lowered by milling if necessary. The pigment is preferably
present in an amount of about 0.1 to about 10% by weight, and more
preferably in an amount of about 0.3 to about 8% by weight.
[0088] Instead of pigments also dyes can be used if sufficiently
color stable. Reactive dyes are particularly preferred. Suitable
dyes include polymethine dyes, di and triarylmethine dyes, aza
analogues of diarylmethine dyes, aza (18) annulenes (or natural
dyes), nitro and nitroso dyes, aza dyes, anthraquinone dyes and
sulfur dyes. These dyes are well known in the art.
[0089] All these additives may be added to the compositions
according to the invention in an amount that is usual for the
additive when used in optical fiber coatings.
Physical Characteristics
[0090] The viscosity of the liquid curable resin composition of the
present invention is usually in the range from about 200 to about
20,000 cps at 25.degree. C., and preferably from about 2,000 to
about 15,000.
[0091] The radiation curable composition of the present invention
may be formulated to be used as a single coating, an inner primary
coating, outer primary coating, a matrix material or bundling
material (all of which can be colored or not), or as an ink. The
invention is particularly suitable for harder materials such as
coatings, inks or matrix materials having modulus of about 400 MPa
or higher, more preferably 600 MPa or higher and most preferably
800 MPa or higher. In particular, the radiation-curable
compositions of the present invention may be formulated such that
the composition after cure has a modulus as low as 0.1 MPa and as
high as 2,000 MPa or more. Those having a modulus in the lower
range, for instance, from 0.1 to 10 MPa, preferably 0.1 to 5 MPa,
and more preferably 0.5 to less than 3 MPa are typically suitable
for inner primary coatings for fiber optics. In contrast, suitable
compositions for outer primary coatings, inks and matrix materials
generally have a modulus of above 50 MPa, with outer primary
coatings tending to have a modulus more particularly above 100 up
to 2,500 MPa and matrix materials tending to be more particularly
between about 50 MPa to about 200 MPa for soft matrix materials,
and between 200 to about 2,500 MPa for hard matrix materials. The
radiation-curable composition of the present invention may be
formulated such that the composition after cure has a Tg between
-70.degree. C. and 130.degree. C. The Tg is measured as the peak
tan-delta in a DMA curve. Preferably, for harder materials, the Tg
is about 40.degree. C. or higher, more preferably, about 60.degree.
C. or higher.
[0092] Elongation and tensile strength of these materials can also
be optimized depending on the design criteria for a particular use.
For cured coatings formed from radiation-curable compositions
formulated for use as inner primary coatings on optical fibers, the
elongation-at-break is typically greater than 65%, preferably
greater than 80%, more preferably the elongation-at-break is at
least 110%, more preferably at least 150% but not typically higher
than 400%. For coatings formulated for outer primary coatings, inks
and matrix materials the elongation-at-break is typically between
6% and 100%, and preferably higher than 10%, more preferably about
20% or higher and in particular about 25% or higher.
[0093] In one preferred embodiment of the invention, polyfunctional
isocyanates are added to the otherwise final coating composition,
and the mixture is stirred for obtaining a homogeneous mixture.
Hydroxyfunctional components are in this way reacted with each
other, and, apparently, this leads to improved mechanical
properties.
[0094] In another preferred embodiment, specific components know to
comprise hydroxyfunctional compounds are reacted with
polyfunctional isocyanates, and, thereafter, these components are
added to the coating composition. This also gives an improvement in
mechanical properties.
[0095] In yet another embodiment, the specific components known to
comprise hydroxy functional compounds are reacted with a both
polyisocyanates and hydroxyfunctional acrylate compounds, so
obtaining further oligomeric compounds that yield improved
mechanical properties.
[0096] A preferred hydroxyfunctional component is alkoxylated
bisphenol-A or alkoxylated bispheno/-A-mono acrylate. Polyfunctioal
isocyanates and hydroxyfunctional acrylate compounds as described
above are particularly useful. Useful amounts of these toughening
agents are, for instance, 10 wt % or less, e.g. 5 wt % or less,
relative to the total composition. This means that generally 0.2-5%
by wt. polyisocyanate is used, preferably 0.3-3% by wt., to achieve
the toughening.
[0097] Preferred applications for the present compositions are in
the field of optical fiber coatings, such as, for instance, matrix
materials, bundling materials, secondary coatings, colored
secondary coatings, and inks.
EXAMPLES
[0098] The following examples are given as particular embodiments
of the invention and to demonstrate the practice and advantages
thereof. The examples are given by way of illustration and are not
intended to limit the specification or claims.
Tensile Strength, Elongation, Modulus, and Toughness Test
Method
[0099] The tensile strength, elongation and secant modulus of cured
samples was tested using a universal testing instrument, Instron
Model 4201 equipped with a personal computer and software "Series
IX Materials Testing System." The load cells used were 2 and 20
pound capacity. The ASTM D638M was followed, with the following
modifications.
[0100] A drawdown of each material to be tested was made on glass
plate or Mylar (in particular, the outer primary coating
compositions, unless otherwise noted, were measured on Mylar) and
cured using a UV processor. The cured film was conditioned at 22 to
24.degree. C. and 50.+-.5% relative humidity for a minimum of
sixteen hours prior to testing.
[0101] A minimum of eight test specimens, having a width of
0.5.+-.0.002 inches and a length of 5 inches, were cut from the
cured film. To minimize the effects of minor sample defects, sample
specimens were cut parallel to the direction in which the drawdown
of the cured film was prepared. If the cured film was tacky to the
touch, a small amount of talc was applied to the film surface using
a cotton tipped applicator.
[0102] The test specimens were then removed from the substrate.
Caution was exercised so that the test specimens were not stretched
past their elastic limit during the removal from the substrate. If
any noticeable change in sample length had taken place during
removal from the substrate, the test specimen was discarded.
[0103] If the top surface of the film was talc coated to eliminate
tackiness, then a small amount of talc was applied to the bottom
surface of test specimen after removal from the substrate.
[0104] The average film thickness of the test specimens was
determined. At least five measurements of film thickness were made
in the area to be tested (from top to bottom) and the average value
used for calculations. If any of the measured values of film
thickness deviates from the average by more than 10% relative, the
test specimen was discarded. All specimens came from the same
plate.
[0105] The appropriate load cell was determined by using the
following equation: [A.times.145].times.0.0015=C Where: [0106]
A=Product's maximum expected tensile strength (MPa); [0107]
145=Conversion Factor from MPa to psi; [0108] 0.00015=approximate
cross-sectional area (in.sup.2) of test specimens; and [0109]
C=lbs. The 2 pound load cell was used for materials where C=1.8
lbs. The 20 pound load cell was used for materials where
1.8<C<18 lbs. If C>19, a higher capacity load cell was
required.
[0110] The crosshead speed was set to 1.00 inch/min (25.4 mm/min),
and the crosshead action was set to "return at break". The
crosshead was adjusted to 2.00 inches (50.8 mm) jaw separation. The
air pressure for the pneumatic grips was turned on and adjusted as
follows: set approximately 20 psi (1.5 Kg/cm.sup.2) for primary
optical fiber coatings and other very soft coatings; set
approximately 40 psi (3 Kg/cm.sup.2) for optical fiber single
coats; and set approximately 60 psi (4.5 Kg/cm.sup.2) for secondary
optical fiber coatings and other hard coatings. The appropriate
Instron computer method was loaded for the coating to be
analyzed.
[0111] After the Instron test instrument had been allowed to
warm-up for fifteen minutes, it was calibrated and balanced
following the manufacturer's operating procedures.
[0112] The temperature near the Instron Instrument was measured and
the humidity was measured at the location of the humidity gage.
This was done just before beginning measurement of the first test
specimen.
[0113] Specimens were only analyzed if the temperature was within
the range 23.+-.1.0 C and the relative humidity was within
50.+-.5%. The temperature was verified as being within this range
for each test specimen. The humidity value was verified only at the
beginning and the end of testing a set of specimens from one
plate.
[0114] Each test specimen was tested by suspending it into the
space between the upper pneumatic grips such that the test specimen
was centered laterally and hanging vertically. Only the upper grip
was locked. The lower end of the test specimen was pulled gently so
that it has no slack or buckling, and it was centered laterally in
the space between the open lower grips. While holding the specimen
in this position, the lower grip was locked.
[0115] The sample number was entered and sample dimensions into the
data system, following the instructions provided by the software
package.
[0116] The temperature and humidity were measured after the last
test specimen from the current drawdown was tested. The calculation
of tensile properties was performed automatically by the software
package.
[0117] The values for tensile strength, % elongation, and secant,
or segment, modulus were checked to determine whether any one of
them deviated from the average enough to be an "outlier." If the
modulus value was an outlier, it was discarded. If there were less
than six data values for the tensile strength, then the entire data
set was discarded and repeated using a new plate. The toughness was
determined as the area under the stress-strain curve up to the
elongation at break.
[0118] All, recorded values were normalized as shown below.
EXAMPLES
[0119] These examples illustrate the change observed in various
physical properties of the below listed primary coating
compositions, wherein an isocyanate is introduced either via a
pre-mixture or in situ.
[0120] Outer Primary Coating Composition A (Approximate
Percentages): TABLE-US-00001 Ethoxylated Bisphenol A Diacrylate
(SR-349, Sartomer) 75% Polyether Urethane Oligomer 20% Ethoxylated
Nonylphenol Acrylate (SR-504D, Sartomer) 5% Hydroxycyclohexyl
Phenyl Ketone (Irgacure-184) .about.1% 2,4,6-Trimethylbenzoyl
Diphenyl Phosphine Oxide <1% Thiodiethylene bis
(3,5-di-tert-butyl-4-Hydroxy)hydrocinnamate <1%
[0121] Outer Primary Coating Composition B (Approximate
Percentages): TABLE-US-00002 Ethoxylated Bisphenol A Diacrylate
(SR-349, Sartomer) 56% Polyether Urethane Oligomer 33% Ethoxylated
Nonylphenol Acrylate (SR-504D, Sartomer) 6% Hydroxycyclohexyl
Phenyl Ketone (Irgacure-184) 2% 2,4,6-Trimethylbenzoyl Diphenyl
Phosphine Oxide 1% Thiodiethylene bis (3,5-di-tert-butyl-4-Hydroxy)
Hydrocinnamate <1%
[0122] Pre-Mixture Composition (Percent Based on Weight):
TABLE-US-00003 Ethoxylated Bisphenol A Diacrylate (SR-349,
Sartomer) 94.3% Toluene Diisocyanate 3.7% 2-Hydroxyethyl acrylate
1.9% Butylated Hydroxy Toluene 0.08% Dibutyltin Dilaurate 0.04%
[0123] TABLE-US-00004 TABLE 1 Relative Physical Properties of
Composition A upon Addition of the Pre-Mixture Composition. Example
1 2 3 4 5 Composition A/Pre- 100/0.0 97.5/2.5 95/5.0 92.5/7.5
90/10.0 Mixture (wt/wt) Relative Tensile Strength 1.105 1.234 1.230
1.000 1 .054 Relative Elongation 1.288 1.494 1.438 1.000 1.193
Relative Modulus 1.145 1.113 1.105 1.105 1.000 Relative Toughness 1
.000 1.736 1.692 1.038 1.443 Relative means that the lowest value
in a category (tensile strength, elongation, modulus, or toughness)
is normalized to 1.000, and that the other values are relative
thereto.
[0124] TABLE-US-00005 TABLE 2 3/36 Relative Physical Properties of
Composition A upon Addition of an Isocyanate Percent Isocyanate* 0
0.5 1 1.5 2 Relative Tensile Strength TDI 1.181 1.183 1.341 1.371
1.181 TMDI 1.181 1.156 1.108 1.100 1.000 IPDI 1.181 1.162 1.224
1.174 1.134 Relative Modulus TDI 1.093 1.110 1.076 1.102 1.127 TMDI
1.093 1.102 1.000 1.059 1.068 IPDI 1.093 0.966 1.068 1.051 1.025
Relative Elongation TDI 1.723 1.70 2.135 2.250 2.554 TMDI 1.723
1.655 1.527 1.324 1.000 IPDI 1.723 1.932 1.757 1.723 1.507 Relative
Viscosity TDI 1.000 1.294 1.671 1.897 1.968 TMDI 1.000 1.008 1.156
1.215 1.247 IPDI 1.000 1.021 1.026 1.215 1.273 Relative Toughness
TDI 1.020 1.188 1.584 1.703 2.050 TMDI 1.020 1.129 0.990 0.911
0.614 IPDI 1.020 1.356 1.248 1.178 1.000 *Isocyanates used in this
experiment were as follows: Toluene Diisocyanate (TDI);
2,2,4-Trimethyl Hexamethylene Diisocyanate (TMDI); and Isophorone
Diisocyanate (IPDI). The indicated isocyanates were added to
Composition A and stirred at 70.degree. C. for 1.5 h, prior to
curing and testing.
[0125] TABLE-US-00006 TABLE 3 Relative Physical Properties of
Composition B upon Addition of Toluene Diisocyanate. Percent TDI 0
1 1.5 Relative Tensile Strength +HC,29 1.163 1.055 1.000 Relative
Elongation 1.386 1.246 1.000 Relative Modulus 1.000 1.005 1.051
Relative Viscosity 1.000 1.437 1.553 Relative Toughness 1.471 1.245
1.000 Toluene diisocyanate (TDI) was added to Composition B then
heated to 70.degree. C. for 1.5 h, prior to curing and testing.
* * * * *