WO1998009923A1

WO1998009923A1 - Photo-curable liquid resin composition

Info

Publication number: WO1998009923A1
Application number: PCT/NL1997/000499
Authority: WO
Inventors: Ikuno Higa; Zen Komiya; Takashi Ukachi
Original assignee: Dsm N.V.; Japan Synthetic Rubber Co. Ltd.
Priority date: 1996-09-05
Filing date: 1997-09-01
Publication date: 1998-03-12
Also published as: AU4138797A; JP3756585B2; JPH1081705A

Abstract

A photo-curable liquid resin composition comprising: (A) a polymer containing an ethylenically unsaturated group and a structural unit containing an ether bond, an ester bond, or ether ester bond, (B) a monomer containing an ethylenically unsaturated group represented by formula (I) wherein R9 represents a hydrogen atom or a methyl group and R10 represents a hydrogen atom or an alkyl group having 1-10 carbon atoms, and (C) a photopolymerization initiator. The composition exhibits excellent stability during a long-term storage and easily processed when coated to optical fibers, and generates only a slight amount of hydrogen gas. The composition also exhibits adequate adhesion to optical fibers and excellent characteristics such as superior UV light resistance, heat resistance, resistance against becoming yellowed by heat and light, and oil resistance.

Description

TITLE OF THE INVENTION PHOTO-CTJRABLE LIQUID RESIN COMPOSITION

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a photo-curable liquid resin composition and, more particularly, to a photo-curable liquid resin composition possessing a low viscosity, exhibiting excellent stability during a long-term storage, and after curing has excellent characteristics and suitable for use as an optical fiber coating material.

Description of the Background Art

In the production of optical fibers, a resin coating is provided for protection and reinforcement of molten glass fiber immediately after spinning. A known structure of the resin coating consists of a primary coating layer of a flexible resin which is applied to the surface of optical fiber and a secondary coating layer provided over the primary coating layer. Because the optical fiber coating process is carried out immediately after spinning molten glass fibers by drawing from a raw material, the coating material must have a high curing rate to expedite manufacture of optical fiber and to increase productivity. If the curing rate of the coating material is slow, the drawing speed in the manufacture of optical fiber is inevitably retarded, resulting in a low productivity.

In addition, the coating material must exhibit superior characteristics after cure, such as minimal changes in the properties due to temperature changes over a wide range and superior durability and reliability under various environmental conditions. An object of the present invention is therefore to provide a photo-curable liquid resin composition, suitable for coating optical fibers, having a low viscosity at room temperature, exhibiting excellent stability during a long-term storage and adequate adhesion to optical fibers, and after curing has excellent characteristics such as superior UV light resistance, heat resistance, yellowing resistance due to heat and light, and oil resistance, and producing only a slight amount of hydrogen.

SUMMARY OF THE INVENTION

This object of the present invention can be achieved in the present invention by a photo-curable liquid resin composition comprising, (A) a polymer containing at least one ethylenically unsaturated group and a backbone oligomer,

(B) at least one monomer comprising a (meth)acrylate group and a dioxane group,

(C) a photopolymerization initiator. The object can be achieved also by a coated optical fiber, of which at least one of the coatings comprises a photo-cured composition, the composition is uncured form being formulated from components comprising

(A) a polymer containing at least one ethylenically unsaturated group and a backbone oligomer,

(B) at least one monomer comprising a (meth)acrylate group and a dioxane group,

(C) a photopolymerization initiator.

The monomer comprising a (meth)acrylate group and dioxane group used in suitable amounts gives the composition very desirable properties such as a low viscosity at room temperature in the uncured composition, and high adhesion to glass and low hydrogen production in the cured composition. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The photocurable composition of the present invention comprises at least three components: (A) a polymer, (B) a monomer and (C) an initiator.

The component (A) preferably comprises a polymer having (meth)acrylate group attached to a backbone oligomer. The backbone oligomer preferably contains at least one polyether, polyolefin, polyester, polycarbonate or bisphenol group; mixtures of these polymer groups can be used, as well as groups that are (block) copolymers of said groups.

More in particular, the backbone oligomer of component (A) comprises at least one structural unit selected from the following groups (l)-(4),

- ( R'-O ) - (1)

wherein R¹ is an alkylene group having 2-6 carbon atoms,

-(C-(CH₂)_m-0)- (2)

II 0 wherein m denotes an integer of 3-10 ,

- ( 0-C-R²-C-0-R³ ) - ( 3 )

II II o o

wherein R² and R³ individually represent a divalent organic group having 2-13 carbon atoms, and - ( R⁴-0- ) _n-C-0 ) - ( 4 )

II o

wherein n is an integer of 1-50 and R⁴ is an alkylene group having 2-6 carbon atoms or a divalent organic group of the following formula (5),

wherein R⁵, R⁶, R⁷, and R⁸ individually represent a hydrogen atom or an alkyl group having 1-8 carbon atoms.

Preferred alkylene groups having 2-6 carbon atoms which are represented by R¹ in formula (1) are the structural units shown by the following formulas (7-1) to (7-8).

-(CH₂CH₂)- (7-1)

-(CH₂CH₂CH₂)- (7-2)

CH₃

I -(CH₂-CH)- (7-3)

-(CH₂CH₂CH₂CH₂)- (7-4)

-(CH₂-CH)- (7-5)

I

CH₂ H₃ CH₃

- ( CH₂CH₂CH₂-CH) - ( 7-6 )

CH₃

I ( CH₂CH₂-CH-CH₂ ) - ( 7-7 )

-(CH₂CH₂CH₂CH₂CH₂CH₂)- (7-8)

Of these, the structural units (7-1), (7-3), (7-4), (7-5), and (7-7) are particularly preferred. In the structural unit represented by the formula (2), m is an integer 3-10 and particularly preferably 5.

In the structural unit shown by the formula (3), as the divalent organic groups represented by R² or R³ divalent alkylene groups and arylene groups are preferred. Given as specific examples of R² or R³ are groups such as ethylene, propylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, phenylene, diphenylene, and bis(phenylenemethane) .

Given as specific preferred alkylene groups having 2-6 carbon atoms which are represented by R⁴ in the formula (4) are the structural units shown by the above formulas (7-1) to (7-8). Of these, the structural units (7-1) and (7-3) are particularly preferred.

Specific examples of the divalent organic group represented by R⁴ of the formula (5) are (bis)phenylene- methane, 2 , 2 '-(bis)phenylenepropane, 2 ,2 '-(bis)phenylene- butane. Of these groups, the structural unit 2 , 2 '-

(bis)phenylenepropane [i.e. the derivative from bis- phenol-A] is particularly preferred.

In the structural units shown by the formula (4), n is an integer of 1-50, and preferably 1-25.

The polymer comprises a backbone and an ethenenically unsaturated group, the latter preferably comprises an acrylate or methacrylate group. An acrylate is most preferred because of the improved cure speed.

The following groups (8-1) to (8-5) are given as specific examples of the ethylenically unsaturated groups contained in the component (A).

CH₂=C- (8-1)

R¹²

CH₂ = C - C - 0 - R¹³- (8-2) R¹² 0

CH,=C ( ¹² ) -C-0-CH₂ CH₂-0-C- ( ¹² ) -C=CH₂

^" II o ^s \ /

CH₂=C ( R¹² ) -COCH₂ ₂--CC--CCHH₂₂OOCCHH₂₂--CC--CCH₂- ( 8-5 )

II o

/ \ CH₂=C (R¹² ) -C-0-CH₂ CH₂-0-C- ( R¹² ) -C=CH₂

II II o o

In the formulas (8-1) to (8-5), R¹² individually represent a hydrogen atom or a methyl group and R¹³ is an alkylene group having 2-9 carbon atoms, and preferably alkylene groups having 2-5 carbon atoms, such as an ethylene group, propylene group, a tetramethylene group, and a pentamethylene group.

Of the above groups (8-1) to (8-5), the groups (8-1) having one ethylenically unsaturated group, (8-2) having one ethylenically unsaturated group, (8-3) having two ethylenically unsaturated groups, and (8-4) having three ethylenically unsaturated groups are preferred, with the groups (8-1) and (8-2) being particularly preferred.

The structural units (1), (2), (3), (4) and the ethylenically unsaturated group which constitute the component (A) are preferably bonded via at least one bond selected from the group consisting of a urethane bond, a urea bond, an amide bond, an ester bond, and an ether bond.

For reducing the temperature dependence of the Young's modulus of elasticity of the cured products made from the composition at a temperature range of -40°C to 60°C and for appropriately maintaining the viscosity of the composition, the number average molecular weight (hereinafter abbreviated as Mn) of the component (A) is preferably 1,000-10,000, and more preferably 1,500-8,000. The number of the ethylenically unsaturated groups contained in the component (A) is 1-20, preferably 1-10, and most preferably about 2-4, per molecule. Excellent curability of the composition, and favorable durability and flexibility of the cured products are obtained by keeping the proportion of the ethylenically unsaturated group in the above range. These polymers containing an ethylenically unsaturated group may be used either individually or in combination of two or more as the component (A).

The proportion of the component (A) in the composition is preferably 10-75% by weight, and more preferably 30-70% by weight. Excellent coatability and processability of the composition, as well as superior flexibility, can be achieved by keeping the proportion of the component (A) in this range.

Embodiments of the process for manufacturing the component (A) are now described.

Process 1

A process comprising reacting a diol (hereinafter referred to as diol (A)) containing at least one structural unit selected from the above formulas (1), (2), (3), and (4), and optionally a diol other than the diol (A), with a diisocyanate compound, to produce a polymer bonded by urethane bonds and having an isocyanate group, and then reacting the isocyanate group of this polymer with a compound having a hydroxyl group and the ethylenically unsaturated group represented by the formulas (8-1) to (8-5) (such a compound is hereinafter referred to as "specific unsaturated compound (A)), thereby introducing the ethylenically unsaturated group via the urethane bond and completing the manufacture of component (A). Process 2

A process comprising reacting the diol (A), and optionally a combination of the diol (A) and a diol compound other than the diol (A) or a diamine, with a diisocynate compound to produce a polymer bonded by urethane bonds, and optionally by urea bonds, and having an isocyanate group, and then reacting the isocyanate group of this polymer with the specific unsaturated compound (A), thereby introducing the ethylenically unsaturated group via the urethane bond and completing the manufacture of component (A).

Process 3

A process comprising reacting a diisocyanate compound with the specific unsaturated compound (A) to produce a polymer bonded by urethane bonds and having an isocyanate group and ethylenically unsaturated groups, and reacting the isocyanate group of this polymer with the diol (A), and optionally a combination of the diol (A) and at least one compound selected from diol compounds other than the diol (A) and diamines, thereby producing urethane bonds, and optionally urea bonds and completing the manufacture of component (A).

Process 4

A process comprising reacting the diol (A), and optionally a combination of the diol (A) and at least one compound selected from diol compounds other than the diol (A) and diamines, with a diisocynate compound to produce a polymer having at least two functional groups selected from hydroxyl group, primary amino group, and secondary amino group, and then reacting these functional groups with a compound having a carboxyl group, an epoxy group, or acid halide group and also having the ethylenically unsaturated group represented by the formulas (8-1) to (8-5), thereby producing ester bonds or amide bonds and completing the manufacture of component (A).

The products produced by these Processes 1 to 4 are urethane (meth)acrylate polymers which are suitable for use as the component (A). The urethane (meth)acrylates are ideal components for providing superior mechanical characteristics such as strength and toughness required for a coating material for optical fibers in combination for with low or high Tg (for respectively, soft or hard mate ials ) .

Examples of the diol (A) containing the above structural unit (1) include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyheptamethylene glycol, polyhexamethylene glycol, poly-2-methyltetramethylene glycol, ethylene oxide adduct to bisphenol A, butylene oxide adduct to bisphenol A, ethylene oxide adduct to bisphenol F, butylene oxide adduct to bisphenol F, ethylene oxide adduct to hydrogenated bisphenol A, butylene oxide adduct to hydrogenated bisphenol A, ethylene oxide adduct to hydrogenated bisphenol F, butylene oxide adduct to hydrogenated bisphenol F, and polyether diols obtained by the ring-opening copolymer ization of two or more types of ionic-polymer izable cyclic compounds.

Examples of the ionic-polymerizable cyclic compound used to produce these polyether diols include cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetra-hydrofuran, dioxane, trioxane, tetraoxane, butadiene monoxide, and isoprene monoxide.

It is also possible to use a polyether diol obtained by the ring-opening copolymer ization of one of the above-mentioned ionic polymerizable cyclic compounds and a cyclic imine such as ethylene imine or the like, a cyclic lactone such as β-propiolactone, glycolic acid lactide, or the like, or a cyclic siloxane such as dimethylcyclopolysiloxane; or a polyether diol obtained by the ring-opening copolymerization of one of the above-mentioned ionic polymerizable cyclic compounds and an ionic polymerizable cyclic compound other than the above-mentioned ionic polymerizable cyclic compounds, such as 3,3-bischloromethyloxetane, styrene oxide, epichlorhydrine, glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, allyl glycidyl carbonate, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidylbenzoate.

Specific examples of the combination of the two or more types of ionic-polymerizable cyclic compounds include tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, and ethylene oxide and butene-1-oxide. The ring-opening copolymers of these two or more ionic-polymerizable cyclic compounds may be randomly bonded.

Examples of commercial available diols (A) having the structural unit shown by the formula (1) include PTMG 1000 and PTMG 2000 (Mitsubishi Chemical Co. , Ltd.); PPG 1000, PPG 2000, EXCENOL 2020, EXCENOL 1020 (Asahi Oline Co., Ltd.); PEG 1000, UNISAFE DC 1100, DA 400, DC 1800 (Nippon Oil and Fats Co., Ltd.); PPTG 2000, PPTG 1000, PTG 400, PTGL 2000 (Hodogaya Chemical Co.,

Ltd.); and PBG 2000A, PBG 2000B (Dai-ichi Kogyo Seiyaku Co., Ltd.).

Further, examples of the diol (A) having the structural unit of formula (2) include diols obtained by the reaction of ε-caprolactone and a divalent diol, such as ethylene glycol, tetramethylene glycol, 1,6-hexane glycol, neopentylene glycol, or 1,4-butane diol.

Examples of the diol (A) having the structural unit of formula (3), include polyester diols obtained by the reaction of a polyhydric alcohol, such as ethylene glycol, propylene glycol, tetramethylene glycol, 1,6-hexane diol, neopentylene glycol, or

1 , 4-cyclohexanedimethanol , and a polybasic acid, such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, or sebacic acid.

Commercially available products which can be used include, for example, Nipporane 4060 (Nippon Polyurethane Co., Ltd. ).

Examples of the diol (A) having the structural unit of formula (4), include commercially available products, such as DN-980, DN-981, DN-982, DN-983, Nipporane N-982 (Nippon Polyurethane), and PC-8000 (PPG Industries Inc.).

Examples of the diol compounds other than the diol (A) used in the Processes 1-4 include:

1,4-cyclohexanedimethanol , dimethylol compounds of dicyclopentadiene, tricyclodecanedimethanol , β-methyl-δ-valerolactone, polybutadiene with terminal hydroxyl groups, hydrogenated polybutadiene with terminal hydroxyl groups, castor oil-denatured polyol, polydimethylsiloxane with terminal diols, and polydimethylsiloxane carbitol-denatured polyols.

In addition, examples of the diamine used in the Processes 2-4 above include, ethylene diamine, tetramethylene diamine, hexamethylene diamine, paraphenylene diamine, 4,4 '-diaminodiphenylmethane, diamines containing hetero atoms, and polyether diamines. Examples of the diisocyanate used in Processes 1-4 include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1 , 5-naphthalene diisocyanate, p-phenylene diisocyanate, 3 , 3 '-dimethyl-4,4 '-diphenylmethane diisocyanate, 4 , 4 '-diphenylmethane diisocyanate, 3, 3 '-dimethylphenylene diisocyanate, 4,4 '-biphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylene bis(4-cyclohexylisocyanate) , hydrogenated diphenylmethane diisocyanate, 2 ,2 , 4-trimethylhexamethylene diisocyanate, 2, 5-bis( isocyanatemethyl )-bicyclo[ 2.2.1]heptane, 2 , 6-bis( isocyanatemethyl )-bicyclo[ 2.2.1]heptane, bis(2-isocyanate-ethyl ) fumarate, 6-isopropyl-l , 3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, and lysine diisocyanate.

Furthermore, examples of the (meth)acrylate compounds having a hydroxyl group as in the specific unsaturated compound(A) include. Given as examples of such (meth)acrylate compounds having hydroxyl group are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyoctyl (meth)acrylate, pentaerythritol tri (meth)acrylate, glycerine di (meth)acrylate, dipentaerythritolmonohydroxy penta (meth)aer late, 1, -butanediol mono(meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 1 , 6-hexanediol mono(meth)acrylate, neopentylglycol mono(meth)acrylate, tr imethylolpropane di (meth)acrylate, trimethylolethane di (meth)acrylate, (meth)acrylates represented by the following formulas (9-1) or (9-2),

CH₂= C - C-0-CH₂-CH-CH₂-0-R²⁰ (9-1) i ii i

R¹⁴ O OH CH₂= C - C-0-CH₂CH₂- ( 0-CCH₂CH₂CH₂CH₂CH₂ ) _D-OH ( 9-2 )

I II II

R¹⁴ o o

wherein R¹⁴ is a hydrogen atom or a methyl group, R²⁰ is a phenyl group and p is an integer from 1-5. An example of commercially available products which can be used is ARONIX M113 (Toagosei Chemical Co., Ltd.).

Component (B) of the photo curable liquid curable resin composition is a compound comprising a (meth)acrylate and a dioxane group.

Preferably the compound constituting component (B) has a molecular wight of less than about 1400, but more than about 170. More in particular, the molecular weight of this compound is about 170-250.

The dioxane group preferably is a 1,3-dioxane or a 1,4-dioxane group, which may be substituted on one or more of the carbon atoms, and which is bound to the (meth)acrylate group via a C₁__i alkylene group. More in particular, a 1,3-dioxane group preferably is bound to the (meth)acrylate through a methylene bond at its 5 position. More in particular, this ethylenically unsaturated monomer is represented by the formula (6)

R⁹ R¹⁰

I I

CH₂=C-C-0-CH₂-C-CH₂ ( 6 )

II 0 CH₂ 0

0-CH₂

wherein R⁹ represents a hydrogen atom or a methyl group and R¹⁰ represents a hydrogen atom or an alkyl group having 1-10 carbon atoms.

Preferably, R⁹ is a hydrogen, and R¹⁰ is methyl, ethyl, iso- or n-propyl. Most preferably, R¹⁰ is ethyl.

These monomers may be used either individually or in combination of two or more.

The proportion of the component (B) in the composition is preferably 5-40% by weight, and more preferably 10-30% by weight. In addition, it is desirable that the total of the components (A) and (B) in the liquid curable resin composition of the present invention be 30% by weight or more, and preferably 40% by weight or more. Examples of the component (C) which is comprised in the liquid resin composition of the present invention include: 1-hydroxycyclohexyl phenyl ketone, 2 , 2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, tr iphenylamine,. carbazole, 3-methyl-acetophenone, 4-chlorobenzophenone, 4,4 '-dimethoxy-benzophenone, 4, '-diaminobenzophenone, Michler 's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl methyl ketal, l-(4-isopropylphenyl )-2-hydroxy-2-methylpropane-l-on, 2-hydroxy-2-methyl-l-phenylpropan-l-one, thioxanethone, diethylthioxanthone, 2-isopropylthio-xanthone, 2-chlorothioxanthone, 2-methy1-1-4-(methylthio)- phenyl-2-morpholino-propan-l-on, 2 ,4, 6-trimethylbenzoyl diphenylphosphine oxide, bis-(2, 6-dimethoxybenzoyl)- 2 ,4,4-trimethylpentylphosphine oxide, and commercially available products, such as Irgacure 184, 369, 651, 500, 907, CGI 1700, CGI 1750, CGI 1850, CG24-61 (Ciba Geigy); Lucerin LR8728 (BASF); Darocur 1116, 1173 (Ciba Geigy); and Uvecryl P36 (UCB). These compounds of the component (C) may be used either individually or in combination of two or more. The proportion of the component (C) in the composition is preferably 0.1-10% by weight, and more preferably 1-5% by weight. A photosensitizer may be optionally added in addition to these photopolymerization initiators. Examples of the photosensitizers include triethylamine, diethylamine, N-methyldiethanoleamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate, and commercially available products such as Uvecryl P102, 103, 104, 105 (UCB).

In addition to the above components, it is desirable to incorporate at least one reactive diluent such as a mono-functional compound having one ethylenically unsaturated group in the molecule, but different from the component (B) (hereinafter referred to as mono-functional compound (D) ) or a poly-functional compound having two or more ethylenically unsaturated groups in the molecule (hereinafter referred to as poly-functional compound (E)).

Generally, two or more more reactive diluents are used in order to tailor mechanical properties such as Tg, modulus and elongation. In particular, the at least one reactive diluent preferably has a molecular weight of not more than 600, or a viscosity at room temperature of not more than about 300 mPa.s (measured as 100% diluent).

Examples of the mono-functional compounds (D) which can be incorporated in the composition include: 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 ( eth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (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, methoxypolypropylene glycol (meth)acrylate, dicyclopentadienyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, t icyclodecanyl (meth)acrylate, isobornyl (meth)acrylate, bornyl (meth)acrylate, diacetone

(meth)acrylamide, isobutoxymethyl (meth)acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformaldehyde, 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 '-dimethylaminopropyl (meth)acrylamide, (meth)acryloyl morpholine; vinyl ethers such as hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, and 2-ethylhexyl vinyl ether; esters of maleic acid; esters of fumaric acid; and compounds represented by the following formulas (11) to (13).

CH₂=C - C -(R¹⁶0) '_g-R¹⁷ (11) I II R¹⁵ O

wherein R¹⁵ is a hydrogen atom or a methyl group; R¹⁶ is an alkylene group containing 2 to 6, preferably 2 to 4 carbon atoms; R¹⁷ is a phenyl group, optionally substituted with an alkyl group containing 1 to 12, preferably 1 to 9, carbon atoms; and q is an integer from 0 to 12, and preferably from 1 to 8.

CH₂= C - C - 0-(0R^lβ)_r-0-CH₂-R²¹ (12)

I II

R¹⁵ 0

wherein R¹⁵ is the same as the R¹⁵ of formula (11); R^lβ is an alkylene group containing 2 to 8, preferably 2 to 5, carbon atoms; and r is an integer from 1 to 8, and preferably from 1 to 4, and R²¹ is a tetrahydrofurfuryl group.

wherein R¹⁵ and R¹⁸ are the same as the R¹⁵, R^lβ in formula (12); s is an integer from 1 to 15; and R¹⁹s are individually a hydrogen atom or a methyl group.

Commercially available monofunctional compounds ARONIX M102, Mill, M113, M114, M117 (Toagosei Chemical Co., Ltd.), KAYARAD TC110S, R629, R644 (Nippon Kayaku Co. Ltd.), and VISCOAT#3700 (Osaka Organic Chemical Industry, Ltd. ).

Examples of polyfunctional compounds (E) which can be incorporated into the composition include: tr imethylolpropane tri (meth)acrylate, pentaerythr itol tri(meth)acrylate, pentaerythr itol tetra(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, tricyclodecanedimethanol di (meth)acrylate, and epoxy (meth)acrylate which is an addition compound of (meth)acrylate to bisphenol A glycidyl ether.

Commercially available polyfunctional compounds: YUPIMER-UV, SA1002, SA2007 (Mitsubishi Chemical Co., Ltd.), VISCOAT#700 (Osaka Organic Chemical Industry Ltd.), KAYARAD R-604, DPCA-20, DPCA-30, DPCA-60, DPCA-120, HX-620, D-310, D-330, (Nippon Kayaku Co., Ltd.), and ARONIX M-210, M-215, M-315, M-325 (Toagosei Chemical Co., Ltd.). It is desirable that the composition of the present invention contain at least one compound selected from these components (D) or components (E) in an amount of 1-40% by weight.

Further, in addition to the above components, polymers or oligomers can be added to the compositions as additives. Such polymers or oligomers include epoxy resin, polyamide, polyamideimide, polyurethane, polybutadiene, chloroprene, polyether, polyester, pentadiene derivatives, styrene/butadiene/styrene block copolymer, styrene/ethylene/butene/styrene block copolymer, styrene/isoprene/styrene block copolymer, petroleum resin, xylene resin, ketone resin, fluorine-containing oligomer, silicone oligomer, polysulfide oligomer, and the like. In addition, reactive oligomers prepared by copolymerizing styrene compounds, (meth)acryl compounds, (meth)acryl compounds with an epoxy group, and the like, and introducing an acryloyl group into the copolymer (e.g. AP-2150, B-3000 to B-3006 (Sin-Nakamura Chemical Co.)) may be incorporated in the composition. Beside the above components, the composition of the present invention may be formulated with various components, as required, such as antioxidants, UV absorbers, photo-stabilizers, silane coupling agents, aging preventives, thermal polymerization inhibitors, leveling agents, coloring matters, surface active agents, preservatives, plasticizers, lubricants, solvents, fillers, wettability improvers, and coated surface improvers. Commercially available antioxidants which can be used include Irganox 1010, 1035, 1076, 1222 (Ciba Geigy), and the like. Examples of UV absorbers which can be used include Tinuvin P234, P320, P326, P327, P328, P213 (Ciba Geigy), Sumisorb 110, 130, 140, 220, 250, 300, 320, 340, 350, 400 (Sumitomo Chemical Industries Co., Ltd.). Commercially available photo-stabilizers which can be added include Tinuvin 292, 144, 622LD (Ciba Geigy), and Sanol LS770, LS765, LS292, LS2626, LS1114, LS744 (Sankyo Co.). Examples of silane coupling agents which can be used include γ-aminopropyltr iethoxysilane, γ-mercaptopropyltrimethoxy-silane, γ-methacryloxypropyltrimethoxysilane, and commercial products such as SH6062, SZ6030 (Toray-Dow Corning Silicone Co.) and KBE903, KBM803 (Shin-etsu Silicone Co.). Commercially available aging preventives include Antigene W, S, P, 3C, 6C, RD-G, FR, AW, and Sumiriser GA-80 (Sumitomo Chemical Co.).

The liquid curable resin composition of the present invention has a viscosity of 200 to 20,000 cP , and preferably 2,000 to 15,000 cP, at 25°C.

When the liquid curable resin composition of the present invention is used as a secondary coating material of optical fiber or a bundling material for a optical fiber ribbon matrix, it is desirable that the Young's modulus after cure be 10 to 250 kg/mm², particularly 40 to 150 kg/mm². When used as a primary coating material for optical fiber, a desirable Young's modulus of the resin composition after cure is 0.05 to 0.3 kg/mm².

The liquid curable resin composition of the present invention can be cured by heat and/or radiation on a substrate as to obtain a coated substrate, or to use the resin composition as a photo-curable adhesive.

The liquid curable coating composition can be used in a process for coating a pristine drawn optical fiber with a primary coating and/or a secondary coating according this invention, and curing the coating with radiation.

The liquid curable coating composition can also be used, in combination with suitable pigments or dyes, as an ink to color coated optical glass fibers.

It is also possible to use the resin composition of the present invention as matrix material in order to bind a plurality of coated and colored optical fibers together. A ribbon unit comprises generally 2-12 coated and colored optical fibers aligned in parallel.

The resin composition of the present invention can also be used as a bundling material as to bind a plurality of ribbons together. The bundle of ribbons generally comprises 2-12 ribbons.

Here, radiation means radiation of infrared light, visible light, ultraviolet light, X-rays, electron beam, α-rays, β-rays, γ-rays, and the like.

EXAMPLES The present invention will be hereinafter described in more detail by way of examples which are given for illustration of the present invention and shall not to be construed as limiting the present invention. In the examples below, "part" indicates "part by weight", the parts in the examples do not necessary add up to 100. Synthetic Example 1

Synthesis of urethane acrylate

The following components were charged into a vessel equipped with a stirrer: 9.7 g of tolylene diisocyanate, 85.5 g of a ring-opening polymer of ethylene oxide and butene oxide having Mn of 2,000, 0.024 g of 2 , 6-di-tert-butyl-p-cresol, and 0.008 g of tr icyclodecane dimethanol diacrylate (manufactured by Mitsubishi Chemical Co., Ltd.). The mixture was cooled with ice to 10°C or below while stirring. After the addition of 0.08 g of dibutyl tin dilaurate, the mixture was stirred for two hours while controlling the temperature at 20-30°C. Then, 0.1 g of γ-mercaptopropyltr imethoxysilane was added, followed by stirring for one hour at 30-40°C. After the addition of 3.7 g of hydroxyethyl acrylate, the mixture was stirred for four hours at 50-60°C. The reaction was terminated when the amount of the residual isocyanate is 0.1% by weight or less, thus obtaining urethane acrylate (A-l) having Mn of 4,800.

Example 1

The following components were charged into a vessel equipped with a stirrer: 50.0 parts of urethane acrylate (A-l), 7.8 parts of N-vinyl caprolactam, 15.5 parts of polyoxyethylene nonylphenyl ether acrylate (M113, manufactured by Toagosei Chemical Co.), 24.1 parts of compound of the above-described chemical formula (6) with R⁹ is hydrogen and R¹⁰ is ethyl, 1.2 parts of 2,4, 6-tr imethylbenzoyldiphenylphosphine oxide (manufactured by BASF) as a photopolymerization initiator, 0.3 part of Irganox 1035 as an antioxidant, and 0.1 part of diethylamine as a photosensitizer . The mixture was stirred 50-60°C to obtain a liquid resin composition of the present invention. Example 2

The following components were charged into a vessel equipped with a stirrer: 50.0 parts of urethane acrylate (A-l), 7.8 parts of N-vinyl caprolactam, 4.1 parts of M113 (manufactured by Toagosei Chemical Co. ) ,

35.5 parts of the compound of the above-described chemical formula (6) with R⁹ is hydrogen and R¹⁰ is ethyl, 1.2 parts of 2 ,4, 6-tr imethylbenzoyldiphenylphosphine oxide (manufactured by BASF) as a photopolymerization initiator, 0.3 part of Irganox 1035 as an antioxidant, and 0.1 part of diethylamine as a photosensitizer. The mixture was stirred 50-60°C to obtain a liquid resin composition of the present invention.

Example 3

The following components were charged into a vessel equipped with a stirrer: 50.0 parts of urethane acrylate (A-l), 7.8 parts of N-vinyl caprolactam, 8.6 parts of M113 (manufactured by Toagosei Chemical Co. , Ltd.), 13.5 parts of M-600A (manufactured by Kyoeisha Chemical Co., Ltd.), 6.9 parts of lauryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.), 10.6 parts of the compound of the above-described chemical formula (6) with R⁹ is hydrogen and R¹⁰ is ethyl, 1.2 parts of 2 , , 6-trimethylbenzoyldiphenylphosphine oxide

(manufactured by BASF) as a photopolymerization initiator, 0.3 part of Irganox 1035 as an antioxidant, and 0.1 part of diethylamine as a photosensitizer. The mixture was stirred 50-60°C to obtain a liquid resin composition of the present invention.

Test Examples

The viscosity, weight loss, T-peel strength, and the amount of hydrogen generated of the compositions prepared in Examples 1-3 were evaluated according to the following methods. The results are shown in Table 1.

(1) Measurement of viscosity

An amount equal to (specific gravity)xl0.3 g of each composition was accurately weighed. The composition was allowed to stand in a thermostat bath at 25°C for 30 minutes. Then, the viscosity was measured using a B-type viscometer (Type-B8H, manufactured by Tokyo Keiki Co. , Ltd) .

(2) Measurement of the weight loss

Cured resin samples were prepared by irradiating the resin compositions with UV light at a dose of 1000 mJ/cm² in the air using a 3.5 KW metal halide lamp (SMX-3500/F-OS, manufactured by ORC Co.). An amount of 1.0 g of these samples were accurately weighed. After extraction in methyl ethyl ketone for 12 hours using a Soxhlet extractor, the residue was dried under a vacuum of 10 mmHg at 60°C for 6 hours. The weight loss (%) was determined according to the following formula.

Weight of the ■ample after extraction

Weight Loss (%) ■ xl00%

Weight of the aanple before extraction

(3) Measurement of T-peel strength

Cured films were prepared by coating the resin compositions to quartz plates using an applicator bar with a thickness of 150 mm to prepared films and irradiating the films with UV light at a dose of 100 mJ/cm² in a nitrogen gas stream using a 3.5 KW metal halide lamp

(SMX-3500/F-OS, manufactured by ORC Co.). The cured films attached to the quartz plates were allowed to stand at 23°C and RH 50% for 24 hours to obtain test leaves. The test leaves were cut into pieces with a 1 cm width. The T-peel strength (g/cm) was measured for each test leaf at a cross head speed of 50 mm/min using a peel tester (Autograph AGS-1KND Type-1 , manufactured by Shimazu Manufacturing Co., Ltd.).

(4) Measurement of hydrogen gas generation Cured resin samples were prepared by irradiating the resin compositions with UV light at a dose of 1000 mJ/cm² in a nitrogen stream using a 3.5 KW metal halide lamp (SMX-3500/F-OS, manufactured by ORC Co.). An amount of 1.0 g of these samples were accurately weighed and placed in glass ampoules. The ampoules were sealed and allowed to stand at 100°C for 7 days, following which the ampoules were placed in a glass vial and the vial was sealed. The ampoules were then broken in the glass vial and gas in the glass vial was sampled to quantitatively analyze hydrogen gas contained therein by gas ehromatography.

TABLE 1

* available as Actilane 411® from Akcros

The photo-curable liguid resin composition for optical fibers of the present invention has a low viscosity at room temperatures, exhibits excellent stability during a long-term storage and adeguate adhesion to optical fibers, and produces cured products with excellent characteristics such as superior UV light resistance, heat resistance, resistance against becoming yellowed by heat and light, and oil resistance. In addition, the cured products generate only a slight amount of hydrogen gas.

Claims

WHAT IS CLAIMED IS:

1. Photo-curable liguid resin composition, suitable for coating optical glass fibers, comprising at least components (A), (B) and (C) , in which component (A) comprises a polymer containing at least one ethylenically unsaturated group and a backbone oligomer, component (B) is at least one monomer comprising a (meth)acrylate group and a dioxane group, and component (C) is at least one photopolymerization initiator .

2. Resin composition according to claim 1, wherein the ethylenically unsaturated group of component

A is a (meth)acrylate group.

3. Resin composition according to any one of claims 1-2, wherein the backbone oligomer of the polymer of component A contains at least one polyether, polyolefin, polyester, polycarbonate, or bisphenol group.

4. Resin composition according to any one of claims 1-3, wherein the composition comprises as component (B) a compound having a molecular weight of less than about 400, and more than about 170, the compound comprising a 1,3-dioxane or a.1,4- dioxane group.

5. Resin composition according to claim 4, wherein the composition comprises as component (B) a monomer containing an ethylenically unsaturated group represented by the following formula (6),

R⁹ R¹⁰

I I CH,=C-C-0-CH₂-C-CH₂ (6)

II / I

O CH, 0

\ /

0-CH₂ wherein R⁹ represents a hydrogen atom or a methyl group and R¹⁰ represents a hydrogen atom or an alkyl group having 1-10 carbon atoms.

6. Resin composition according to any one of claims 1-5, comprising,

(A) 10-75% by weight of the polymer containing an ethylenically unsaturated group and a backbone oligomer,

(B) 5-40% by weight of the monomer containing an ethylenically unsaturated group and a dioxane

(1,3) group, and

(C) 0.1-10% by weight of a photopolymerization initiator .

7. Resin composition according to any one of claims 1-6, wherein the component (A) is a urethane

(meth)acrylate.

8. Resin composition according to any one of claims 1-7, wherein the total amount of the component (A) and the component (B) is at least 30% by weight of the composition.

9. Resin composition according to any one of claims 1-8, further comprising 1-40% by weight of .at least one compound selected from the group consisting of (D) mono-functional compounds having one ethylenically unsaturated group in the molecule, but different from the component (B) , and (E) poly-functional compounds having two or more ethylenically unsaturated groups in the molecule.

10. Resin composition according to any one of claims 1-9, wherein the number average molecular weight of component (A) is 1,000-10,000.

11. Resin composition according to any one of claims 1-10, wherein the number of ethylenically unsaturated groups in the polymer of component (A) is 1-10 per molecule.

12. Resin composition according to claim 5, wherein R⁹ is hydrogen.

13. Resin composition accoridng to claim 5, wherein R¹⁰ is ethyl.

14. Resin composition according to any one of claims 1-13, wherein the composition further comprises suitable additives.

15. Resin composition according to any one of claims 1-14, wherein the composition has a viscosity of 200 to 25,000 cP at 25°C.

16. Coated optical glass fiber, at least one of the coatings comprises a photo-cured composition, the composition in uncured form being formulated from components as defined in any one of claims 1-15.

17. Coated fiber according to claim 16, wherein the primary coating is a photocured coating, which coating in uncured form is being formulated from components as defined in any one of claims 1-15.

18. Process for the preparation of a coated optical fiber wherein a liquid coating composition according to any one of claims 1-15 is applied on a pristine drawn optical fiber, and cured by radiation.

19. Optical fiber coated with at least one cured primary coating, the primary coating before curing being a resin composition according to any one of claims 1-15, the cured primary coating having a Young's modulus of 0.05-0.3 kg/mm².

20. Process for the preparation of a coated optical fiber wherein a liquid curable composition according to any one of claims 1-15 is applied as secondary coating on an optical fiber, and cured by radiation.

21. Optical fiber coated with a primary and a secondary coating, the secondary coating before curing being a resin composition according to any one of claims 1-15, the cured secondary coating having a Young's modulus of 10-250 kg/mm².

22 . Optical fiber ribbon comprising a plurality of coated optical fibers, bonded together with a matrix material, the matrix material being a cured coating, said coating before curing being a liquid curable resin composition according to any one of claims 1-15, said cured coating having a Young's modulus of 5-250 kg/mm².

23. Optical fiber bundle comprising plurality of optical fiber ribbons, bonded together with a bundling material, the bundling material being a cured coating, said coating before curing being a liquid curable resin composition according to any one of claims 1-15, said cured coating having a Young's modulus of 5-250 kg/mm².