U.S. patent number RE39,423 [Application Number 08/624,354] was granted by the patent office on 2006-12-12 for optical fiber coating composition and method of preparing a cured coating composition.
This patent grant is currently assigned to Dainippon Ink and Chemicals, Inc.. Invention is credited to Yutaki Hashimoto, Masayuki Kamei, Jun Shirakami.
United States Patent |
RE39,423 |
Hashimoto , et al. |
December 12, 2006 |
Optical fiber coating composition and method of preparing a cured
coating composition
Abstract
A curing composition comprising (1) a fluorine-containing curing
monomer containing a fluorinated alkyl group having not less than 6
carbon atoms, (2) a fluorine-containing curing monomer containing a
fluorinated alkyl group having not more than 5 carbon atoms, and
(3) a polyfunctional curing monomer, the weight ratio of said
fluorine-containing curing monomer (1) to said fluorine-containing
curing monomer (2) ranging from 75/25 to 99/1. The composition is
coated on an optical fiber base and cured by active energy rays to
provide a core/clad optical fiber excellent in transparency,
mechanical strength, environmental resistance, and optical
characteristics.
Inventors: |
Hashimoto; Yutaki (Osaka,
JP), Shirakami; Jun (Osaka, JP), Kamei;
Masayuki (Osaka, JP) |
Assignee: |
Dainippon Ink and Chemicals,
Inc. (Tokyo, JP)
|
Family
ID: |
26345908 |
Appl.
No.: |
08/624,354 |
Filed: |
April 11, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
07827212 |
Jan 30, 1992 |
05302316 |
Apr 12, 1994 |
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Foreign Application Priority Data
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Jan 31, 1991 [JP] |
|
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3-10609 |
Mar 12, 1991 [JP] |
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3-46698 |
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Current U.S.
Class: |
252/183.11 |
Current CPC
Class: |
C03C
25/105 (20130101); C09D 4/00 (20130101); G02B
1/048 (20130101); G02B 1/048 (20130101); C08L
33/16 (20130101); C09D 4/00 (20130101); C08F
220/22 (20130101) |
Current International
Class: |
C09K
3/00 (20060101) |
Field of
Search: |
;252/183.11 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Carone; Michael J.
Attorney, Agent or Firm: Armstrong, Kratz, Quintos, Hanson
& Brooks, LLP
Claims
What is claimed is:
1. A curable coating composition comprising.Iadd.:.Iaddend. 1) a
first monomer represented by formula (A) RfOCOC(R).dbd.CH.sub.2 (A)
wherein Rf represents .Iadd.a .Iaddend.linear or branched
fluorinated alkyl group having not less .[.that.]. .Iadd.than
.Iaddend.6 carbon atoms, a hydroxyl substituted fluorinated alkyl
having not less .[.that.]. .Iadd.than .Iaddend.6 carbon atoms, a
fluorinated sulfonamide having not less .[.that.]. .Iadd.than
.Iaddend.6 carbon atoms, or a fluorinated amide having not less
.[.that.]. .Iadd.than .Iaddend.6 carbon atoms, and R represents
H.[...]. .Iadd., .Iaddend.F, or C.sub.1-10 fluorinated alkyl; 2) a
second monomer represented by formula (B)
.Iadd.Rf'OCOC(R').dbd.CH.sub.2 (B).Iaddend. wherein Rf' represents
a linear or branched C.sub.1-5 fluorinated alkyl and R' represents
--H, --F, or --CH.sub.3; and 3) at least one polyfunctional
methacrylic curable monomer, wherein the weight ratio of the first
monomer to the second monomer .Iadd.is .Iaddend.from 75:25 to
99:1.
2. A curable coating composition as defined in claim 1, wherein the
first monomer is a member of the group consisting of
C.sub.8F.sub.17CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 and
C.sub.6F.sub.13CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 and R
represents H, F, or C.sub.1-10 fluorinated alkyl.
3. A curable coating composition as defined in claim 1, wherein Rf'
is at least one of a branched C.sub.1-5 fluorinated alkyl or a
linear C.sub.1-5 fluorinated alkyl, each having a fluorohydrocarbon
end group.
4. A curable coating composition as defined in claim 1, wherein the
second monomer is a member of the group consisting of
H(CF.sub.2CF.sub.2).sub.2CH.sub.2OCOC(R').dbd.CH.sub.2 and
(CF.sub.3).sub.2CHOCOC(R').dbd.CH.sub.2.
5. A curable coating composition as defined in claim 1, wherein the
polyfunctional curable monomer is present in an amount of 1 to 50%
by weight compared to the total weight of the curable
composition.
6. A curable composition as claimed in claim 1, wherein said
polyfunctional curing monomer (3) is
(CH.sub.2.dbd.C(R)COOCH.sub.2).sub.3CC.sub.2H.sub.5, wherein R
represents a hydrogen atom, a methyl group, or a fluorine atom.
7. A curable composition as claimed in claim 1, wherein said
polyfunctional curing monomer (3) is trimethylolpropane
triacrylate.
8. A curable composition as claimed in claim 1, wherein said
composition contains a thiol-containing compound.
9. A curable composition as claimed in claim 8, wherein said
thiol-containing compound is
.gamma.-mercaptopropyltrimethoxysilane.
.Iadd.10. A process for preparing a transparent cured coating on a
substrate, comprising the steps of: (A) applying on a substrate a
coating of a curable resin composition comprising: 1) a first
monomer represented by formula (A) RfOCOC(R).dbd.CH.sub.2 (A)
wherein Rf represents a linear or branched fluorinated alkyl group
having not less than 6 carbon atoms, a hydroxyl substituted
fluorinated alkyl having not less than 6 carbon atoms, a
fluorinated sulfonamide having not less than 6 carbon atoms, or a
fluorinated amide having not less than 6 carbon atoms, and R
represents H, F, or C.sub.1-10 fluorinated alkyl; 2) a second
monomer represented by formula (B) Rf'OCOC(R').dbd.CH.sub.2 (B)
wherein Rf' represents a linear or branched C.sub.1-5 fluorinated
alkyl and R' represents --H, --F, or --CH.sub.3; and 3) at least
one polyfunctional methacrylic curable monomer, wherein the weight
ratio of the first monomer to the second monomer is from 75:25 to
99:1; and (B) curing the coating by applying active energy
radiation, heat, or a combination of active energy radiation and
heat..Iaddend.
.Iadd.11. A process as in claim 10, wherein the first monomer is a
member selected from the group consisting of
C.sub.8F.sub.17CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 and
C.sub.6F.sub.13CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 and R
represents H, F, or C.sub.1-10 fluorinated alkyl..Iaddend.
.Iadd.12. A process as in claim 10, wherein Rf' is at least one
member selected from the group consisting of a branched C.sub.1-5
fluorinated alkyl and a linear C.sub.1-5 fluorinated alkyl, each
having a fluorohydrocarbon group..Iaddend.
.Iadd.13. A process as in claim 10, wherein the second monomer is
one member selected from the group consisting of
H(CF.sub.2CF.sub.2).sub.2CH.sub.2OCOC(R').dbd.CH.sub.2 and
(CF.sub.3).sub.2CHOCOC(R').dbd.CH.sub.2..Iaddend.
.Iadd.14. A process as in claim 10, wherein the polyfunctional
curable monomer is present in an amount of 1 to 50% by weight
compared to the total weight of the curable
composition..Iaddend.
.Iadd.15. A process as in claim 10, wherein said polyfunctional
curing monomer (3) is (CH.sub.2.dbd.C(R)COOCH.sub.2).sub.3
CC.sub.2H.sub.5, wherein R represents a hydrogen atom, a methyl
group, or a fluorine atom..Iaddend.
.Iadd.16. A process as in claim 10, wherein said polyfunctional
curing monomer (3) is trimethylolpropane triacrylate..Iaddend.
.Iadd.17. A process as in claim 10, wherein said composition
contains a thiol-containing compound..Iaddend.
.Iadd.18. A process as in claim 17, wherein said thiol-containing
compound is .gamma.-mercaptopropyltrimethoxysilane..Iaddend.
Description
FIELD OF THE INVENTION
This invention relates to an optical fiber and a curing composition
for optical fiber cladding. More particularly, it relates to an
optical fiber excellent in mechanical strength, environmental
resistance, and optical characteristics and to a curing composition
for producing the same.
BACKGROUND OF THE INVENTION
Plastic-clad optical fibers comprising quartz, silica, glass, etc.
as a core and plastics as a cladding (hereinafter abbreviated as
PCF) are relatively cheap, excellent in light transmission, and
easy to have an increased numerical aperture and are therefore used
as optical fibers for short-to-medium distance communication or
light guides.
While silicone resins have conventionally been used as cladding
materials, fluorine-containing resins having high hardness have
recently been proposed and practically used as cladding materials
from the standpoint of easy handling and environmental resistance
as disclosed in U.S. Pat. Nos. 4,511,209 and 4,707,076,
JP-A-63-40104, JP-A-63-43104, JP-A-63-208805, JP-A-63-208806,
JP-A-63-208807,JP-A-63-249112, EP 257863, and EP 333464 (the term
"JP-A" as used herein means an "unexamined published Japanese
patent application") In particular, EP 257863 discloses an active
energy ray-curing cladding material mainly comprising fluorinated
acrylates and an optical fiber using the composition as a cladding
material, in which the curable cladding material comprises a
fluorine-containing curing monomer containing a fluorinated alkyl
group having not less than 6 carbon atoms, a fluorine-containing
curing monomer containing a fluorinated alkyl group having not more
than 5 carbon atoms, and a polyfunctional curing monomer with a
weight ratio of the former fluorine-containing curing monomer to
the latter fluorine-containing curing monomer being 68/32.
However, having poor compatibility or homogeneity at room
temperature, the above-described curable cladding material, when
coated as such at room temperature, provides optical fibers having
seriously deteriorated optical characteristics such as light
transmission properties. Besides, the formed cladding has poor
adhesion to the core and easily peels off, causing reduction of
environmental resistance or tensile strength of the optical fiber,
eventually making the optical fiber useless. Where the cladding
material is heated for coating so as to have improved compatibility
or homogeneity, the heating temperature must be strictly controlled
to prevent eccentricity, etc., which accordingly requires a
complicated drawing apparatus and deteriorates workability.
Further, where the cladding resin is rendered transparent at room
temperature, the resulting cladding layer would have reduced
mechanical strength and an increased refractive index and fail to
maintain a desired numerical aperture.
Therefore, under the present situation, there is no cladding
material which exhibits satisfactory transparency at room
temperature, has a low refractive index and excellent workability,
and exhibits excellent transparency and dynamic strength after
curing to thereby provide an optical fiber having sufficient
dynamic strength, optical characteristics, and environmental
resistance, e.g., heat- and humidity-resistance.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a
curing composition which provides a cured resin simultaneously
satisfying the requirements of transparency, mechanical strength,
environmental resistance, and optical characteristics.
Another object of the present invention is to provide an optical
fiber simultaneously satisfying the requirements of transparency,
mechanical strength, environmental resistance, and optical
characteristics.
As a result of extensive investigations, the inventors have now
found that the above objects of the present invention are
accomplished by a curing composition comprising at least two
fluorine-containing curing monomers different in carbon atom number
of the fluorinated alkyl group thereof at a specific mixing ratio,
thus having reached the present invention.
The present invention provides a curing composition including (1) a
fluorine-containing curing monomer containing a fluorinated alkyl
group having not less than 6 carbon atoms (hereinafter simply
referred to as monomer (1)), (2) a fluorine-containing curing
monomer containing a fluorinated alkyl group having not more than 5
carbon atoms (hereinafter simply referred to as monomer (2)), and
(3) a polyfunctional curing monomer (hereinafter simply referred to
as monomer (3)), the weight ratio of monomer (1) to monomer (2)
ranging from 75/25 to 99/1.
The present invention also provides an optical fiber comprising an
optical fiber base and a coated and cured layer comprising the
above-described curing composition.
DETAILED DESCRIPTION OF THE INVENTION
The optical fiber base which can be used in the present invention
may be any of commonly employed bases and includes, for example,
optical fiber cores made of quartz, silica, glass, or plastics and
optical fibers having a core/cladding structure.
Monomers (1) and (2) which can be used in the present invention can
be selected from any known compounds having a polymerizable
ethylenically unsaturated group. Monomers having the following
acrylic ester groups or analogous groups thereof are suitable from
the viewpoint of availability and requirements for the particular
use as a cladding material, that is, dynamic strength and optical
characteristics.
Monomer (1) preferably includes fluorinated (meth)acrylates
represented by formula (A): RfOCOC(R).dbd.CH.sub.2 (A) wherein Rf
represents a fluorinated alkyl group having not less than 6 carbon
atoms, which may be either straight or branched or which may
contain in the main chain thereof an oxygen atom, e.g.,
(CF.sub.3).sub.2CFOC(CF.sub.3)FCF.sub.2--; and R represents a
hydrogen atom, a methyl group, or a fluorine atom.
The terminology "(meth)acrylate" as used herein inclusively means
compounds containing an acryloyl group, a methacryloyl group, or an
.alpha.-fluorinated acryloyl group.
Specific examples of the fluorinated (meth)acrylate represented by
formula (A) are shown below for illustrative purposes only but not
for limitation:
TABLE-US-00001 a-1:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2C.sub.8F.sub.17 a-2:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2CH.sub.2C.sub.8F.sub.17 a-3:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2C.sub.12F.sub.25 a-4:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2CH.sub.2C.sub.12F.sub.25 a-5:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2C.sub.10F.sub.21 a-6:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2C.sub.10F.sub.21 a-7:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2C.sub.6F.sub.13 a-8:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2CH.sub.2C.sub.6F.sub.13 a-9:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2C.sub.4F.sub.9 a-10:
CH.sub.2.dbd.C(F)COOCH.sub.2CH.sub.2C.sub.6F.sub.13 a-11:
CH.sub.2.dbd.CHCOOCH.sub.2(CH.sub.2).sub.6CF(CF.sub.3).sub.2 a-12:
CH.sub.2.dbd.CHCOOCH.sub.2(CF.sub.2).sub.6H a-13:
CH.sub.2.dbd.CHCOOCH.sub.2(CF.sub.2).sub.6H a-14:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2(CF.sub.2).sub.8H a-15:
CH.sub.2.dbd.CHCOOCH.sub.2(CF.sub.2).sub.10H a-16:
CH.sub.2.dbd.CHCOOCH.sub.2(CF.sub.2).sub.12H a-17:
CH.sub.2.dbd.CHCOOCH.sub.2C(OH)HCH.sub.2C.sub.8F.sub.17 a-18:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2N(C.sub.3H.sub.7)SO.sub.2C.sub.8F-
.sub.17 a-19:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2N(C.sub.2H.sub.5)COC.sub.7F.sub.1-
5 a-20:
CH.sub.2.dbd.CHCOO(CH.sub.2).sub.2(CF.sub.2).sub.8CF(CF.sub.3).sub.-
2 a-21:
CH.sub.2.dbd.C(CH.sub.2CH.sub.2C.sub.8F.sub.17)COOCH.sub.2CH.sub.2C-
.sub.8F.sub.17
The fluorinated (meth)acrylates (A) may be used either individually
or in combinations of two or more thereof.
Preferred fluorinated (meth)acrylates (A) are those represented by
formula (A-1) or (A-2):
C.sub.8F.sub.17CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 (A-1)
C.sub.6F.sub.17CH.sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 (A-2) wherein R
is as defined above.
Among the above-mentioned specific examples, preferred fluorinated
(meth)acrylates (A) are a-1, a-2, a-7, and a-8, and particularly
a-1 and a-7, from the standpoint of transparency, dynamic strength,
and solvent resistance of a cured resin and optical
characteristics, dynamic strength and solvent resistance of the
optical fibers, especially PCF, prepared by using the curing
composition.
Monomer (2) preferably includes fluorinated (meth)acrylates
represented by formula (B): Rf'OCOC(R).dbd.CH.sub.2 (B) wherein Rf'
represents a fluorinated alkyl group containing not more than 5
carbon atoms, which may be either straight or branched; and R is as
defined above.
Specific examples of the fluorinated (meth)acrylates represented by
formula (B) are shown below for illustrative purposes only but not
for limitation:
TABLE-US-00002 b-1: CH.sub.2.dbd.CHCOOCH.sub.2CF.sub.3 b-2:
CH.sub.2.dbd.CHCOOCH.sub.2CF.sub.2CF.sub.3 b-3:
CH.sub.2.dbd.CHCOOCH.sub.2CFHCF.sub.3 b-4:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2CFHCF.sub.3 b-5:
CH.sub.2.dbd.CHCOOCH.sub.2CH.sub.2CF.sub.3 b-6:
CH.sub.2.dbd.CHCOOCH.sub.2CF.sub.2CFHCF.sub.3 b-7:
CH.sub.2.dbd.CHCOOCH.sub.2CF(CF.sub.3)CF.sub.3 b-8:
CH.sub.2.dbd.CHCOOCH(CF.sub.3.sub.2) b-9:
CH.sub.2.dbd.C(F)COOCH(CF.sub.3.sub.2) b-10:
CH.sub.2.dbd.C(CH.sub.3)COOCH(CF.sub.3).sub.2 b-11:
CH.sub.2.dbd.CHCOOCH.sub.2(CF.sub.2CF.sub.2).sub.2H b-12:
CH.sub.2.dbd.C(F)COOCH.sub.2(CF.sub.2CF.sub.2).sub.2H b-13:
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2(CF.sub.2CF.sub.2).sub.2H b-14:
CH.sub.2.dbd.CHCOOCH.sub.2CF.sub.2CF.sub.2CFHCF.sub.3
The fluorinated (meth)acrylates (B) may be used either individually
or in combinations of two or more thereof.
Preferred fluorinated (meth)acrylates (B) are those represented by
formula (B-1) or (B-2):
H(CF.sub.2CF.sub.2).sub.2CH.sub.2OCOC(R).dbd.CH.sub.2 (B-1)
(CF.sub.3).sub.2CHOCOC(R).dbd.CH.sub.2 (B-2) wherein R is as
defined above.
Among the above-mentioned specific examples, preferred fluorinated
(meth)acrylates (B) are those in which the terminal fluorine atoms
of the fluorinated alkyl group thereof are partly substituted with
a hydrogen atom and those in which the fluorinated alkyl group
thereof has a branched structure from the standpoint of
compatibility or homogeneity of the curing composition at room
temperature; stability of these properties; workability and
productivity in the production of optical fibers (especially PCF);
and optical characteristics and dynamic strength of the optical
fibers (especially PCF). Those having a branched fluorinated alkyl
group are particularly preferred from the viewpoint of solvent
resistance of a cured resin.
To accomplish the objects of the present invention, it is essential
to mix monomers (1) and (2). The monomers (1) to (2) mixing ratio
ranges from 75/25 to 99/1 by weight, and preferably from 80/20 to
99/1 by weight. If the monomers (1) to (2) mixing ratio is out of
the above-mentioned range, compatibility and transparency at room
temperature, stability of these properties, dynamic strength, and
optical characteristics of the curing composition are deteriorated.
Further, such a curing composition has reduced workability or
efficiency in the production of optical fibers. Furthermore, the
resulting optical fibers undergo reductions in dynamic strength,
optical characteristics and environmental resistance such as
solvent resistance.
Monomer (3) may be any of commonly employed polyfunctional curing
monomers. Particularly preferred are those generally called
polyfunctional (meth)acrylates or special acrylates, and those
generally called prepolymers, base resins, oligomers or acrylic
oligomers (hereinafter inclusively referred to as (meth)acrylates
(C)). Specific examples of (meth)acrylates (C) are shown below. (i)
Polyfunctional (meth)acrylates containing two or more (meth)acrylic
ester groups bonded to a polyhydric alcohol. (ii) Polyester
acrylates containing two or more (meth)acrylic ester groups bonded
to a polyester polyol obtained by the reaction between a polyhydric
alcohol and a polybasic acid.
Examples of the polyhydric alcohols in (i) and (ii) above are
ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol,
neopentyl glycol, trimethylolpropane, dipropylene glycol,
polyethylene glycol, polypropylene glycol, pentaerythritol, and
dipentaerythritol. Examples of the polybasic acids in (ii) are
phthalic acid, adipic acid, maleic acid, trimellitic acid, itaconic
acid, succinic acid, terephthalic acid, and an alkenylsuccinic
acid. (iii) Epoxy-modified (meth)acrylates comprising an epoxy
resin whose epoxy group is esterified with (meth)acrylic acid to a
(meth)acryloyl functional group.
Examples of the epoxy resin are bisphenol A-epi-chlorohydrin epoxy
resins, phenol-novolak-epi-chlorohydrin epoxy resins, and
polyhydric alcohol-epi-chlorohydrin alicyclic resins. (iv)
Polyurethane acrylates obtained by reacting a polyisocyanate
compound with a hydroxyl-containing (meth)acrylate.
Examples of the polyisocyanate compound include compounds having a
polyester, polyether or polyurethane skeleton having bonded to both
terminals of an isocyanate group. (v) Polyether (meth)acrylates,
melamine (meth)acrylates, alkyd (meth)acrylates, isocyanurate
(meth)acrylate, and silicone (meth)acrylates.
Specific examples of (meth)acrylates (C) are shown below for
illustrative purposes only but not for limitation.
TABLE-US-00003 c-1: Ethylene glycol di(meth)acrylate c-2:
Diethylene glycol di(meth)acrylate c-3: Triethylene glycol
di(meth)acrylate c-4: Polyethylene glycol di(meth)acrylate (number
average molecular weight: 150-1000) c-5: Propylene glycol glycol
di(meth)acrylate c-6: Dipropylene glycol di(meth)acrylate c-7:
Tripropylene glycol di(meth)acrylate c-8: Polypropylene glycol
di(meth)acrylate (number average molecular weight: 200-1000) c-9:
Neopentyl glycol di(meth)acrylate c-10: 1,3-Butanediol glycol
di(meth)acrylate c-11: 1,4-Butanediol glycol di(meth)acrylate c-12:
1,6-Hexanediol glycol di(meth)acrylate c-13: Hydroxypivalic ester
neopentyl glycol di(meth)acrylate c-14: Bisphenol A glycol
di(meth)acrylate c-15: Trimethylolpropane tri(meth)acrylate c-16:
Pentaerythritol tri(meth)acrylate c-17: Dipentaerythritol
hexa(meth)acrylate c-18: Pentaerythritol tetra(meth)acrylate c-19:
Trimethylolpropane di(meth)acrylate c-20: Dipentaerythritol
monohydroxypenta(meth)acrylate
These (meth)acrylates (C) are commercially available under the
following trade names. The parentheses indicate the corresponding
compound No. listed above. Neomer MA-305 (c-21), Neomer BA-60
(c-22), Neomer TA-505 (c-23), Neomer TA-401 (c-24), Neomer PHA 405X
(c-25), Neomer TA 705X (c-26), Neomer EA 400X (c-27). Neomer EE
401X (c-28), Neomer EP 405X (c-29), Neomer HB 601X (c-30), and
Neomer HB 605X (c-31) - all produced by Sanyo Chemical Industries,
Ltd. KAYARAD HY-220 (c-32), HX-620 (c-33), D-310 (c-34), D-320
(c-35), D-330 (c-36), DPHA (c-37), DPCA-20 (c-38), DPCA-30 (c-39),
DPCA-60 (c-40), and DPCA-120 (c-41) - all produced by Nippon Kayaku
Co., Ltd. FA-713A (c-42) - produced by Hitachi Chemical Co.,
Ltd.
These polyfunctional (meth)acrylates (C) may be used either
individually or in combinations of two or more thereof.
According to the inventors' finding, preferred of the above
described (meth)acrylates (C) are c-9 and c-15, and particularly
c-15, from the standpoint of compatibility with fluorinated
(meth)acrylates (A) and (B) and optical characteristics and dynamic
strength after curing.
For the purpose of reducing a refractive index of the curing
composition, fluorine-containing polyfunctional monomers, such as
those represented by formula shown below, may also be used as
monomer (3).
CH.sub.2.dbd.C(R)COO(CH.sub.2).sub.x(CF.sub.2).sub.y(CH.sub.2).sub.x-OOC-
C(R).dbd.CH.sub.2
wherein R is as defined above; x represents 1 or 2; and y
represents an integer of from 4 to 12.
Specific examples of such fluorine-containing polyfunctional
monomers are shown below.
TABLE-US-00004 c-43:
CH.sub.2.dbd.CHCOOCH.sub.2(C.sub.2F.sub.4).sub.2CH.sub.2OCOCH.dbd.C-
H.sub.2 c-44:
CH.sub.2.dbd.CHCOOC.sub.2H.sub.4(C.sub.2F.sub.4).sub.3C.sub.2H.sub.-
4OCOCH.dbd.CH.sub.2 c-45:
CH.sub.2.dbd.C(CH.sub.3)COOC.sub.2H.sub.4(C.sub.2F.sub.4).sub.3C.su-
b.2H.sub.4OCOC(CH.sub.3).dbd.CH.sub.2 c-46:
CH.sub.2.dbd.C(F)COOC.sub.2H.sub.4(C.sub.2F.sub.4).sub.6C.sub.2H.su-
b.4OCOC(F).dbd.CH.sub.2 c-47:
CH.sub.2.dbd.CHCOOC.sub.2H.sub.4(C(CF.sub.3)FCF.sub.2).sub.4C.sub.2-
H.sub.4OCOCH.dbd.CH.sub.2 c-48:
CH.sub.2.dbd.CHCOOC.sub.2H.sub.4(C.sub.2H.sub.4).sub.6(C(CF.sub.3)F-
CF.sub.2).sub.6 C.sub.2H.sub.4OCOCH.dbd.CH.sub.2
The fluorine-containing polyfunctional monomer further includes
compounds represented by formula:
CH.sub.2.dbd.C(R)COOCH.sub.2C(OH)HCH.sub.2Rf'OCH.sub.2.
C(OH)HCH.sub.2OCOC(R).dbd.CH.sub.2 wherein R is as defined above;
and Rf' represents
(CH.sub.2).sub.x(CF.sub.2).sub.y(CH.sub.2).sub.x, wherein x and y
are as defined above, ##STR00001##
The proportion of monomer (3) in the curing composition is not
particularly limited but preferably ranges from 1 to 50% preferably
from 1 to 45%, and more preferably from 1 to 30%, by weight from
the viewpoint of optical characteristics and dynamic strength.
As monomer (3), trimethylolpropane triacrylate is preferably used
from the standpoint of compatibility with monomer (1) and monomer
(2), curing property, and transparency, dynamic strength, and
solvent resistance after curing, and further optical
characteristics, mechanical strength, and solvent resistance as
optical fibers.
In order to improve environmental resistance of the curing
composition after curing, such as heat resistance and moisture
resistance, and to improve the same properties of the curing
composition after molded into a cladding layer, it is very
effective to incorporate in the curing composition an antioxidant,
such as thiol-containing compounds and hindered phenol compounds.
From the standpoint of curing properties and environmental
resistance of the composition, thiol-containing compounds are
preferred.
Thiol-containing compounds as antioxidant include monofunctional
thiol compounds, such as alkylthiol compounds having from 2 to 18
carbon atoms in the alkyl moiety thereof, thioglycolic esters
containing an alkyl group having from 2 to 18 carbon atoms, and
C.sub.8F.sub.17CH.sub.2CH.sub.2SH; and polyfunctional thiol
compounds having at least two thiol groups per molecule, such as
neopentyl thioglycol, trithiomethylolpropane, and thiodicarboxylic
acid esters, e.g., dilauryl thiodipropionate. Particularly
preferred of these thiol-containing compounds is
.gamma.-mercaptopropyltrimethoxysilane which contains a coupling
group as well as a thiol group per molecule and contributes to
excellent environmental resistance, i.e., heat- and
moisture-resistance, of optical fibers, particularly PCF.
Specific examples of hindered phenol compounds useful as
antioxidant are 2,6-di-t-butyl-4-methylphenol,
2,2'-methylenebis(4-methyl-6-t-butylphenol),
4,4'-thiobis(6-t-butyl-3-methylphenol),
4,4'butylidene-bis(3-methyl-6-t-butylphenol),
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)-benzene,1,3,5--
tris(2-methyl-4-hydroxy-5-t-butylphenol)butane,
octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene
glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate],
1,6-hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
and
pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].
These thiol-containing compounds and hindered phenol compounds may
be used either individually or in combinations of two or more
thereof.
The proportion of the thiol-containing compounds or hindered phenol
compounds in the curing composition ranges from 0.01 to 5% by
weight and, for better optical characteristics and dynamic strength
after curing, from 0.01 to 3% by weight.
If desired, the curing composition of the present invention may
further contain other various additives and a photopolymerization
initiator in addition to the above-described components.
Additives which can be used in the present invention include
polymers and solvents for viscosity adjustment; light stabilizers,
coloring agents; coupling agents for improving adhesion between an
optical fiber base and a cladding; defoaming agents, leveling
agents, and surface active agents for uniform coating; surface
modifiers for controlling adhesion between optical fibers and a
primary coating; flame retardants; and plasticizers.
Useful coupling agents include silane coupling agents, titanium
coupling agents, and zirco-aluminate coupling agents, with silane
coupling agents being preferred. Specific examples of the silane
coupling agents are dimethyldimethoxysilane,
dimethyldiethoxysilane, methyltrimethoxysilane,
dimethylvinylmethoxysilane, phenyltrimethoxysilane,
.gamma.-chloropropyltrimethoxysilane,
.gamma.-chloropropylmethyldimethoxysilane,
.gamma.-aminopropyltriethoxysilane,
.gamma.-glycidoxypropyltrimethoxysilane,
.gamma.-glycidoxypropylmethyldimethoxysilane,
.gamma.-methacryloxypropylmethoxysilane,
.gamma.-methacryloxypropylmethyldimethoxysilane,
.gamma.-acryloxypropylmethyltrimethoxysilane,
.gamma.-acryloxypropylmethyldimethoxysilane, and
.gamma.-mercaptopropyltrimethoxysilane which also serves as an
antioxidant as described above.
Defoaming agents, leveling agents, surface active agents, and
surface modifiers to be used are preferably fluorine-containing
compounds.
In addition to the above-described thiol-containing compounds and
hindered phenol compounds, phosphorus-containing compounds and
disulfide-containing compounds are also useful as antioxidants.
Useful flame retardants include bromine-containing flame
retardants, zinc compounds, antimony compounds, phosphorus
compounds, and combinations thereof. Examples of the
bromine-containing flame retardants are decabromodiphenyl oxide,
hexabromobenzene, hexabromocyclododecane,
dodecachloropentacyclooctadeca-7,15-diene,tetrabromobisphenol A,
tribromophenol, tetrabromophthalic anhydride, dibromoneopentyl
glycol, and 2-(2,4,6-tribromophenoxy)ethyl (meth)acrylate. Examples
of the zinc compounds are zinc borate compounds (e.g., 3ZnO.sub.2,
2B.sub.2O.sub.3.3H.sub.2O, 2ZnO.3B.sub.2O.sub.3.3.5H.sub.2O), zinc
molybdate compounds (e.g., ZnO.ZnMoO.sub.4, CaO.ZnMoO.sub.4),
Zn.sub.3(PO.sub.4).sub.2.4H.sub.2O, ZnO-MgO complex calcined
materials, ZnO, and ZnCO.sub.3. Examples of the antimony compounds
include antimony trioxide.
For the purpose of plasticizing the curing composition or
controlling the refractive index of the resulting cladding,
non-polymerizable fluorine compounds; fluorinated alcohols, e.g.,
HO(CH.sub.2).sub.rC.sub.sF.sub.2s+1, wherein r is an integer of
from 1 to 4, and s is an integer of from 1 to 20; fluorinated
carboxylic acids, e.g., HOOC(CH.sub.2).sub.t-C.sub.uF.sub.2u+1,
wherein t is 0 or an integer of from 1 to 4, and u is an integer of
from 1 to 20; fluorinated polyethers generally called fluorine
oils; and so-called fluorine-containing inert liquids, e.g.,
N(C.sub.4F.sub.9).sub.3, perfluorodecalin,
C.sub.8F.sub.17OC.sub.4F.sub.9, and C.sub.9F.sub.20, can also be
added to the curing composition.
The curing composition according to the present invention can be
applied to an optical fiber base, especially an optical fiber core,
by coating or impregnation and then irradiated with an active
energy ray, e.g., light, electron beam, or radiation, to undergo
polymerization curing to form a desired coating layer or cladding
layer. In some cases, heat may be used as a curing energy source
either alone or in combination with the above-mentioned active
energy ray.
Where light, such as ultraviolet light, is used as an active energy
ray, photopolymerization initiators known in the art can be used as
a catalyst. Examples of suitable photopolymerization initiators are
(d-1) benzophenone; (d-2) acetophenone; (d-3) benzoin; (d-4)
benzoin ethyl ether; (d-5) benzoin isobutyl ether; (d-6) benzyl
methyl ketal; (d-7) azobisisobutyronitrile; (d-8) hydroxycyclohexyl
phenyl ketone; and (d-9) 2-hydroxy-2-methyl-1-phenylpropan-1-one.
If desired, polymerization can be accelerated by addition of
photosensitizers, such as amine compounds and phosphorus
compounds.
The photopolymerization initiator is preferably used in an amount
of from 0.01 to 10% by weight, and more preferably from 0.1 to 7%
by weight, based on the total weight of the curing composition.
Where polymerization curing is effected with electron rays or
radiation, any initiator is not particularly needed.
Where heat is utilized as a polymerization initiator,
polymerization curing can be carried out in the presence or absence
of a polymerization initiator, e.g., azobisisobutyronitrile,
benzoyl peroxide, and methyl ethyl ketone peroxide-cobalt
naphthenate, at a temperature e.g., of from 80.degree. to
200.degree. C.
Polymerization curing with any of ultraviolet beam, electron rays,
and radiation is preferred as compared with heat curing from the
standpoint of workability, productivity and economy in the
production of optical fibers and performance characteristics of the
resulting optical fibers. In particular, ultraviolet curing is the
most convenient and economical.
If desired, a solvent may be added to the curing composition for
the purpose of controlling viscosity, coating properties, and
coating film thickness. Solvents to be used are not particularly
limited as far as they have no adverse influences on the
polymerization reaction. Examples of suitable solvents include
alcohols, e.g., methanol, ethanol, and isopropyl alcohol; ketones,
e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone;
esters, e.g., methyl acetate, ethyl acetate, and butyl acetate;
chlorinated hydrocarbons, e.g., chloroform, dichloroethane, and
carbon tetrachloride; and low-boiling organic solvents, e.g.,
benzotrifluoride, chlorobenzotrifluoride, m-xylene hexafluoride,
tetrachlorodifluoroethane, 1,1,2-trichloro-1,2,3-trifluoroethane,
and trichloromonofluoromethane. The solvent, if used, must be
removed from the coated layer before the commencement of
polymerization curing at room temperature or, if desired, under
heating or under reduced pressure. In cases when the solvent is
removed by heating, the heating temperature should be so controlled
as not to induce thermal polymerization of the monomers, etc.
The curing composition can be coated on an optical fiber base,
i.e., an optical fiber core or a core/cladding optical fiber, by
various known techniques, such as coating by means of a brush, an
applicator, a bar coater, a roller brush, or a roll coater; spray
coating by means of an airless spray coater; flow coating by means
of a shower coater or a curtain coater; dip coating; and casting.
An appropriate coating technique should be selected according to
the material, shape or use of the base.
For the formation of a cladding or a coat on an optical fiber core
or a core/cladding optical fiber, known coating and curing
techniques as described in West German Patent Publication No.
2,459,320, JP-A-53-139545, and U.S. Pat. No. 4,125,644 can be
employed. For example, an optical fiber base is threaded through an
extrusion-coating die, and the curing composition is continuously
extrusion-coated on the base. After removal of a solvent, if any,
an active energy ray is irradiated onto the coating to form a
cladding or a coat.
Any conventional active energy ray source for polymerization curing
can be used, for example, germicidal lamps, fluorescent sunlamps,
carbon arc lamps, xenon lamps, high-pressure mercury lamps for
copying, middle- or high-pressure mercury lamps, ultrahigh-pressure
mercury lamps, electrodeless discharge tubes, metal halide lamps,
and natural sunlight for ultraviolet rays; and scanning type or
curtain type electron accelerators for electron rays. Where a
coating film having a thickness of 5 .mu.m or less is cured with
ultraviolet rays, ultraviolet irradiation is preferably conducted
in an inert gas atmosphere, e.g., nitrogen gas, for ensuring
polymerization efficiency.
Optical fiber cores which can be coated with the curing composition
of the present invention include those made of inorganic materials
such as quartz, silica, and glass; and those made of plastics such
as polymethyl methacrylate, deuterated polymethyl methacrylate,
polystyrene, and polycarbonate. Taking the characteristics of the
curing composition of the present invention into consideration,
quarts, silica, and glass are particularly suitable materials.
The curing composition according to the present invention is
applicable as not only a cladding of an optical fiber core or a
coat of a core/cladding optical fiber as hereinbefore described but
also a cladding of light waveguide sheets, adhesives for optics,
electrically insulating materials (e.g., potting materials and
sealants), and wire coatings. Further, having a low refractive
index, the curing composition of the present invention also finds
its use as a low reflecting coat on a transparent glass or plastic
sheet or plate or as a sealant for optical IC.
In addition, since the curing composition of the present invention
forms a cured film excellent in scratch resistance, oil resistance,
smoothness, water- and oil-repellency, water resistance,
moistureproofness, rustproofness, stainproofness, release
properties, and low water absorption properties, it is useful as a
protective coat of various materials and substrates.
For example, the curing composition is suitable as a protective
coat on non-magnetic metals, e.g., copper, aluminum and zinc; a
protective coat on plastics, e.g., polyesters (e.g., polyethylene
terephthalate, polyethylene-2,6-naphthalate), polyolefins (e.g.,
polypropylene), cellulose derivatives (e.g., cellulose acetate),
and polycarbonate; and, in some cases, as a protective coat on a
magnetic layer of magnetic tapes or discs, including a
ferromagnetic alloy film (comprising iron, cobalt and/or nickel as
major components and aluminum, silicon, chromium, manganese,
molybdenum, titanium, various heavy meals, or rare earth metals as
minor components) deposited on glass, paper, wood, fibrous
materials or ceramics (porcelain and earthenware) and a magnetic
layer comprising iron, cobalt and chromium, deposited on a plastic
film (e.g., a polyester film) in the presence of a trace amount of
oxygen; and also as a surface or back surface treating agent for
magnetic recording media, e.g., magnetic tape and floppy discs,
which are particularly required to have lubricity.
On the other hand, since the curing composition of the present
invention is capable of forming a transparent, smooth, and thin
film on a glass surface, it is also useful in applications
requiring oil resistance and wiping resistance as an oil strain
inhibitor or an oil penetration inhibitor for various optical
instruments.
Further, the curing composition of the present invention is
suitable as a protective film of solar cells which particularly
require moistureproofness or as a protective coat of optical
fibers, optical fiber cables, optical discs, and optomagnetic
discs. Furthermore, the excellent scratch resistance,
stainproofness and moisture resistance of the composition can be
taken advantage of for use in surface protection of medical tools
or equipment, surface protection of teeth or artificial teeth,
filling of teeth, or molding of artificial teeth.
The curing composition of the present invention is applicable to
various molded products or as hard coating agents for films,
sheets, etc., since the coated film is excellent in scratch
resistance.
The curing composition of the present invention can be compounded
with pigments and dispersing agents to provide stainproof and
non-tacky coatings or inks applicable to the bottom of ships.
The present invention is now illustrated in greater detail with
reference to Examples, but it should be understood that the present
invention is not deemed to be limited thereto. All the percents,
parts, and ratios are by weight unless otherwise indicated.
EXAMPLES 1 TO 10 AND COMPARATIVE EXAMPLES 1 TO 3
Curing compositions of the present invention and comparative
compositions were prepared according to the formulation shown in
Table 1.
An optical fiber core having an outer diameter of 200 .mu.m
obtained by melt spinning of synthetic quartz at a drawing speed of
60 m/min was threaded through an extrusion-coating die, and each
curing composition prepared was continuously coated thereon at the
die temperature of 25.degree. C. and cured in a nitrogen atmosphere
by means of two high-pressure mercury lamps (output: 120 W/cm) to
obtain a PCF having a 15 .mu.m thick cladding.
Physical properties of the curing composition and transmission loss
of the resulting PCF were determined according to the following
test methods. The results obtained are shown in Table 1.
1) Transparency before Curing
Transparency of a curing composition was evaluated with eyes.
2) Transparency after Curing
A curing composition was cast on a 1 mm deep glass-made tray, and a
1 mm thick quartz plate was put thereon taking care not to
incorporate air bubbles. The cast composition was cured by
irradiation using a high-pressure mercury lamp of 120 W/cm, and
transparency of the resulting cured resin plate was observed with
eyes.
3) Refractive Index
A refractive index of the 1 mm thick cured resin plate as prepared
in (2) above with an Abbe refractometer.
4) Transmission Loss (Initial)
Transmission loss was measured at a wavelength of 850 nm according
to a cut-back method.
5) Transmission Loss after Exposure to Heat
After the PCF was preserved at 130.degree. C. for 1000 hours, the
transmission loss was measured in the same manner as described
above.
6) Transmission Loss after Exposure to Moisture
After the PCF was preserved at 70.degree. C. and 98% RH for 500
hours, the transmission loss was measured in the same manner as
described above.
TABLE-US-00005 TABLE 1 Refractive Transmission Loss (dB/km)
Transparency Index Shore After After Example Curing Composition
Before After After Hard- Exposure Exposure No. (part) Curing Curing
Curing ness Initial to Heat to Moisture Example 1 a-1 68.0 trans-
trans- 1.403 D76 5.4 5.8 5.9 b-11 7.5 parent parent c-15 (A*) 24.0
d-9 0.5 MPTMS** 1.4 Example 2 a-1 56.6 trans- trans- 1.414 D75 5.5
5.9 5.9 b-11 18.9 parent parent c-15 (A) 24.0 d-9 0.5 MPTMS 1.4
Comparative a-1 51.3 trans- slightly 1.418 D68 9.6 36.2 49.9
Example 1 b-11 24.2 parent turbid c-15 (A) 24.0 d-9 0.5 MPTMS 1.4
Comparative n-1 68.0 opaque whitened unmeasure- D-43 >100
>300 >3- 00 Example 2 n-7 7.5 able c-15 (A) 24.0 d-9 0.5
MPTMS 1.4 Comparative a-1 75.5 opaque whitened unmeasure- D45
>100 >300 >30- 0 Example 3 c-15 (A) 24.0 d-9 0.5 MPTMS 1.3
Example 3 a-1 66.2 trans- trans- 1.408 D74 5.6 6.5 6.4 b-8 9.3
parent parent c-15 (A) 24.0 d-9 0.5 MAPTMS*** 0.5 acrylic 0.1 acid
Example 4 a-1 66.2 trans- trans- 1.408 D74 5.5 5.7 5.8 b-8 9.3
parent parent c-15 (A) 24.0 d-9 0.5 MPTMS 1.3 Example 5 a-1 70.0
trans- trans- 1.400 D75 5.7 6.5 6.6 b-1 5.0 parent parent c-15 (A)
24.0 d-9 0.5 octyl thio- 0.5 glycolate MPATMS 0.5 Example 6 a-1
72.5 trans- trans- 1.401 D77 5.4 5.7 5.8 b-8 3.0 parent parent c-15
(A) 22.0 c-9 (A) 2.0 d-9 0.5 MPTMS 1.4 Example 7 a-1 40.9 trans-
trans- 1.437 D79 5.5 5.9 6.1 b-3 13.6 parent parent c-15 (A) 45.0
d-9 0.5 MAPTMS 0.7 TP**** 0.5 Example 8 a-7 76.8 trans- trans-
1.397 D68 5.4 5.7 5.7 b-11 3.2 parent parent c-15 (A) 19.5 d-9 0.5
MFTMS 1.2 Example 9 a-13 68.0 trans- trans- 1.402 D75 5.5 6.2 6.2
b-11 7.5 parent parent c-15 (A) 24.0 d-9 0.5 MFTMS 1.2 Example 10
a-1 68.0 trans- trans- 1.403 D75 5.5 6.3 6.4 b-11 7.5 parent parent
c-15 (A) 24.0 d-9 0.5 MAPTMS 1.4 Note: *Acrylate compound
**.gamma.-Mercaptopropyltrimethoxysilane
***.gamma.-Methacryloxypropyltrimethoxysilane
****2,2-Thio-diethylenebis(3-(3,5-di-i-butyl-4-hydroxyphenyl)propionase
EXAMPLE 11
Curing compositions having the following formulation were prepared
using each of the fluorinated (meth)acrylates (A) and fluorinated
(meth)acrylates (B) shown in Table 2. A Shore hardness after curing
and transparency before and after curing were examined. The results
obtained are shown in Table 2.
TABLE-US-00006 Formulation Fluorinated (meth)acrylate (A) 63.6%
Fluorinated (meth)acrylate (B) 15.9% c-15 (A) 20.0% d-9 0.5%
.gamma.-Mercaptopropyltrimethoxysilane 1.2%
The symbol "G" in Table 2 means satisfactory transparency:- the
left one indicates transparency before curing, and the right one
after curing.
TABLE-US-00007 TABLE 2 Fluor- inated (Meth)- acry- late Fluorinated
(Meth)acrylate (A) (B) a-1 a-2 a-5 a-6 a-7 a-8 a-9 a-12 a-13 b-1
D75 D75 D77 D70 D73 D73 D66 D76 D79 G/G G/G G/G G/G G/G G/G G/G G/G
G/G b-2 D76 D73 D76 D69 D70 D70 D65 D77 D79 G/G G/G G/G G/G G/G G/G
G/G G/G G/G b-3 D74 D72 D77 D65 D72 D72 D66 D78 D77 G/G G/G G/G G/G
G/G G/G G/G G/G G/G b-4 D70 D72 D70 D68 D70 D72 D67 D76 D78 G/G G/G
G/G G/G G/G G/G G/G G/G G/G b-5 D76 D74 D76 D69 D70 D73 D65 D75 D79
G/G G/G G/G G/G G/G G/G G/G G/G G/G b-6 D77 D73 D78 D70 D71 D74 D64
D77 D79 G/G G/G G/G G/G G/G G/G G/G G/G G/G b-7 D77 D74 D76 D65 D73
D73 D64 D76 D77 G/G G/G G/G G/G G/G G/G G/G G/G G/G b-8 D79 D80 D79
D69 D78 D76 D66 D80 D77 G/G G/G G/G G/G G/G G/G G/G G/G G/G b-9 D78
D80 D75 D65 D76 D76 D67 D78 D76 G/G G/G G/G G/G G/G G/G G/G G/G G/G
b-10 D77 D76 D72 D66 D76 D75 D66 D76 D77 G/G G/G G/G G/G G/G G/G
G/G G/G G/G b-11 D78 D78 D77 D67 D76 D74 D64 D77 D78 G/G G/G G/G
G/G G/G G/G G/G G/G G/G b-12 D77 D77 D74 D66 D77 D77 D64 D76 d78
G/G G/G G/G G/G G/G G/G G/G G/G G/G b-13 D78 D79 D76 D67 D75 D73
D65 D78 D77 G/G G/G G/G G/G G/G G/G G/G G/G G/G b-14 D78 D64 D77
D65 D74 D75 D65 D77 D76 G/G G/G G/G G/G G/G G/G G/G G/G G/G
When the whole or half of c-15(A) was replaced with c-9(A), each of
the compositions had satisfactory transparency both before and
after curing.
EXAMPLE 12
Curing compositions (5.times.5.times.5 mm) having the following
formulation were prepared using each of the fluorinated
(meth)acrylates (A) and fluorinated (meth)acrylates (B) shown in
Tables 3 and 4.
TABLE-US-00008 Formulation Fluorinated (meth)acrylate (A) 63.6%
Fluorinated (meth)acrylate (B) 15.9% c-15 (A) 20.0% d-9 0.5%
.gamma.-Mercaptopropyltrimethoxysilane 1.2%
For an immersion test, these curing compositions were immersed in
acetone or ethyl acetate at 23.degree. C., and then the weight
change (wt %) after immersion for 48 hours (i.e., swelling degree)
was measured. The results obtained are shown in Tables 3 and 4.
TABLE-US-00009 TABLE 3 Immersion in Acetone Fluorinated Fluorinated
(Meth)acrylate (A) (Meth)acrylate (B) a-1 a-7 b-8 +1.3 +1.9 b-9
+1.2 +1.7 b-10 +1.5 +1.9 b-11 +4.7 +5.3 b-12 +4.5 +5.2
TABLE-US-00010 TABLE 4 Immersion in Ethyl Acetate Fluorinated
Fluorinated (Meth)acrylate (A) (Meth)acrylate (B) a-1 a-7 b-8 +3.7
+4.6 b-9 +3.5 +4.4 b-10 +3.9 +4.7 b-11 +6.4 +7.8 b-12 +6.4 +7.6
As is clear from Tables 3 and 4, the cured resin of the composition
using a combination of a-1 and b-8, a combination of a-1 and b-9,
or a combination of a-1 and b-10 exhibited far more excellent
solvent resistance than that of the composition using a combination
of a-1 and b-11 or a combination of a-1 and b-12. Further, the
cured resin of the composition using a combination of a-7 and b-8,
a combination of a-7 and b-9, or a combination of a-7 and b-10
exhibited far more excellent solvent resistance than that of the
composition using a combination of a-7 and b-11 or a combination of
a-7 and b-12.
As described and demonstrated above, the curing resin composition
according to the present invention is excellent in transparency and
homogeneity at room temperature and is also excellent in
transparency and dynamic strength after curing. Thus, when it is
used as a cladding material or a coating material of optical
fibers, excellent workability is obtained because of no need to
heat as has been usual with the conventional cladding materials,
whereby the problem of eccentricity frequently accompanying heating
can be minimized while providing optical fibers excellent in
mechanical strength, optical characteristics, and environmental
resistance such as heat resistance and moisture resistance.
While the invention has been described in detail and with reference
to specific examples thereof, it will be apparent to one skilled in
the art that various changes and modifications can be made therein
without departing from the spirit and scope thereof.
* * * * *