JPS62146966A - Actinic radiation-curable coating composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which can form an excellent cured film having low elongation and low modulus, containing a specified star type oligomer, a non-star type oligomer and a polymerizable, monoethylenically unsaturated monomer. CONSTITUTION:1-99wt% star type oligomer having at least three soft segment chains selected from polyoxyalkylene (carbonyl) chains and poly(oxyalkylene/ oxyalkylenecarbonyl) chains having an MW of 60-4,000 per molecule of a core substance having active hydrogen atoms attached to an oxygen atom and/or a nitrogen atom, said chains extending from said core substance, and having polymerizable unsaturated groups attached to the terminals of said soft segments through an ester linkage or an (acyl)urethane linkage is blended with 1-99wt% non-star type oligomer having an MW of 200-50,000 and polymerizable, ethylenically unsaturated groups at the terminals of its high- molecular chains and 2-60wt% polymerizable, monoethylenically unsaturated monomer to obtain an actinic radiation-curable coating compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) and -1 The present invention relates to a coating composition that is cured by irradiation with active energy rays, and particularly to an active energy ray-curable coating composition suitable for coating optical fibers.

For protection, optical fibers are coated with a protective film immediately after being drawn. This protective film not only prevents scratches on the glass in subsequent processes, but also prevents fiber deterioration and microhenting, which causes signal attenuation, even after the product is manufactured. MoJ-”f
It is f. Generally, it is difficult to satisfy all the required characteristics with a single layer of protective film.
It is common to form two or three coating layers, each having a certain role to play. For example - next cover 51. For example, the layer is required to have a low Young's modulus, high elongation, and high refractive index, and the secondary coating layer is required to have toughness and abrasion resistance. In order to meet these demands, there are already many proposals for improving the resin itself of the coating layer.
It is difficult to satisfy all required performances.

In addition, with the increase in the drawing speed of optical fibers, there is a need to shorten the curing time of coating compositions, and active energy ray-curable resin compositions such as ultraviolet ray curing and electron beam curing are attracting attention. For example, see Japanese Patent Application Laid-Open No. 58-223638.

Such an active energy ray-curable coating composition has (1
) an oligomer containing an ethylenically unsaturated group at the end of the polymer chain; and (2) an ethylenically unsaturated monomer.

In order to use such an active energy ray-curable coating composition as a primary coating material for optical fibers, it must have a low Tg and a relatively high molecular weight in order to meet the required performance such as a small initial Young's modulus and a high elongation. It was necessary to use oligomers. However, high molecular weight oligomers are not sufficiently three-dimensional, especially 1'+ (more than 1r).
At a high temperature, the polymer becomes rubbery and the interaction between polymer molecules becomes small, resulting in a disadvantage that it does not exhibit sufficient elongation.

In order to promote three-dimensionalization and avoid a rubbery state at high temperatures, a polyfunctional monomer may be added, but a low Young's modulus and high elongation cannot be achieved.

Both hardness and elongation are necessary to provide the external force protection and internal sheath protection required of the secondary sheath. To make it hard, add polyfunctional monomers,
Although it is possible to increase the crosslinking density, elongation decreases because the distance between the crosslinking points is short.

If monofunctional or difunctional monomers or oligomers with soft segments are used as monomers or oligomers,
Although it can improve elongation, it has the disadvantage of decreasing hardness.

Furthermore, unlike FMS curable coating compositions, active energy ray curable coating compositions are generally solvent-free so that they do not require volatilization or setting of the solvent by raising the temperature; The use of ugly oligomers increases the viscosity of the composition, making it difficult to coat.

In particular, when used for coating optical fibers, the present invention provides (1
) - As a secondary coating, the tensile strength does not decrease in the rubber state at high temperatures, the elongation rate is high and the modulus is low, and (2) as a secondary coating, it forms a cured film with a good balance of hardness and elongation. An object of the present invention is to provide an energy beam-curable coating composition.

The present invention provides an active energy ray-curable coating composition containing (1) an oligomer containing an ethylenically unsaturated group at the end of a polymer chain and (2) an ethylenically unsaturated monomer as film-forming components. relating to things. The characteristics of the present invention are (1) as an oligomer containing an ethylenically unsaturated group at the end of the polymer chain;
(A star-shaped oligomer having at least three polymer chains containing an al soft segment and having an ethylenically unsaturated group bonded to the terminal. A polyoxyalkylene chain, a polyoxyalkylenecarbonyl chain, or a poly(oxyalkylene-oxyalkylenecarbonyl) chain with a molecular weight of 60 or more and 4,000 or less is added to a nuclear material having at least 3 bonded active hydrogen atoms per molecule of the nuclear material. 3+l&I or more, and an ethylenically unsaturated group is bonded to each terminal of the soft segment 1 to chain via an ester bond, urethane bond, or acyl urethane bond.

The star oligomer is a molecule having an ethylenically unsaturated group at the end of the bl polymer chain ffl 2 0 (l
a non-star oligomer having a molecular weight of less than 50,000;
In combination with fcl monoethylenically unsaturated monomer,
ζ used. Their proportions are (nl I −
99%.

(b) 1-99%, (c12-60%).

Until now, it has not been known to use the star oligomer used in the present invention in an active energy ray-curable coating composition for optical fibers. This star-shaped oligomer contains soft segments, is trifunctional or more polyfunctional, and the crosslinking point is at the end of the chain extending from the core substance, so when used as the primary coating of an optical fiber, the crosslinking density is low. The chain length between the and crosslinks can be increased, thereby preventing a decrease in tensile strength in a rubber state at a temperature higher than the polymer Tg, and making it possible to obtain a coating with a high elongation rate and low modulus. When used as a secondary coating, a coating with well-balanced hardness and elongation can be obtained.

Furthermore, it is generally known that star-shaped polymer compounds have a lower viscosity than straight-shaped polymer compounds when compared with the same molecular weight. Therefore, according to the present invention, it is possible to use an oligomer having a relatively large molecular weight without reducing the coating workability of the composition.

The star oligomer of the present invention can be synthesized using a compound having three or more active hydrogen atoms bonded to oxygen and/or nitrogen atoms as a core material.

An example of a nuclear material having three or more active hydrogen atoms bonded to an oxygen atom is trimethylolethane.

Glycerin, hexanetriol, l-rimedylolpropane, butanetriol, pentaerythritol, erythritol, dicrycerin, adonitol, arabitol, α-methylglucoside.

Examples include trivalent or higher polyhydric phenols such as xylitol, sorbitol, dipentaerythritol, galactitol, mannitol, sucrose, sorbicun, phenol formaldehyde initial condensate, and triethanolamine.

The active hydrogen atom bonded to the nitrogen atom is 3 (1'lI
An example of a nuclear material having + or more is ethylenediamine.

Propylene diamine, hexamethylene diamine.

Examples include diethylenetriamine, toluenediamine, phenylenediamine, and iminobispropylamine.

Compounds having a total of 113111i1 or more active hydrogen atoms bonded to oxygen atoms and active hydrogen atoms bonded to nitrogen atoms in the same molecule can also be used as nuclear substances, such as monoethanolamine.

Examples include jetanolamine, buchnolamine, propatoolamine, 2-hydroxyethylpropylamine, jetanolaminopropylamine, and the like.

Next, the active hydrogen of the nuclear material is subjected to cyclic ether and/or alkali ring-opening polymerization or cationic ring-opening polymerization using a conventional method, so that each has a molecular weight of 60 or more and 4,000 or more.
Introduce zero or less soft segment chains. Ethylene oxide is an example of a cyclic ether into which polyoxyalkylene can be introduced.

Cyclic ethers having 2 to 6 carbon atoms such as propylene oxide, epichlorohydrin, isobutylene oxide, oxetane, and tetrahydrofuran are used. The lactone into which a polyoxyalkylene carbonyl chain can be introduced has the formula (wherein Rs and R2 are hydrogen, respectively, a hydrocarbon residue, and n
represents an integer from 4 to 7), and ε−
Caprolactone is a typical example. Random or block copolymerized poly(oxyalkylene-oxyalkylenecarbonyl) chains may be introduced using both cyclic ethers and lactones. Molecular weight GJ of each soft segment chain, from 400 to 4,0 for -order coating materials
00, and preferably 60 to 2,000 for the secondary coating material.

The star oligomer of the present invention can be obtained by introducing an ethylenically unsaturated group using the terminal hydroxyl group of each soft segment of the addition polymer thus obtained. One method for introducing an ethylenically unsaturated group is to acylate the soft segment droxyl group using (meth)acrylic acid or a reactive derivative of (meth)acrylic acid such as (meth)acryloyl chloride. be.

The second method is to introduce an ethylenically unsaturated group through an acyl urethane bond using (meth)acryloyl isocyanate. Furthermore, NGO101 added a diisocyanate compound to the terminal hydroxyl group of the soft segment.
This method involves reacting at a ratio of 1=2/I and utilizing the remaining NGO groups to introduce hydroxyalkyl (meth)acrylate or its lactone adduct through a urethane bond.

First, a diisocyanate and a hydroxyalkyl (meth)acrylate or a lactone adduct thereof are reacted,
The soft segment may then be reacted with the terminal hydroxyl group. Diisocyanates that can be used include ethylene diisocyanate, propylene diisocyanate,
Tetramethylene diisocyanate, hexamethylene diisocyanate, 1-methyl-2,4-diisocyanate cyclohexane, 1-methyl-2,6-diisocyanate cyclohexane, ω, ω1-diisocyanate diethylbenzene, ω, ω”-diisocyanate dimethylaminotoluene, ω, ω゛-diisocyanate dimethylxylene, ω, ω1-diisocyanate diethylxylene,
Lysine diisocyanate, 4.4'-methylenebis(cyclohexylisocyanate), 4.4''-ethylenebis(cyclohexylisocyanate), ω,ω°-diisocyanate 1.3-dimethylbenzene, ω,ω”-
Diisocyanate-L4-dimethylbenzene, isophorone diisocyanate, 2.4-) lylene diisocyanate
1., 2.6-Dylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4”-methylene bis(
Hydroxyalkyl (meth)acrylates such as phenyl isocyanate), triphenylmethane 1-diisocyanate, etc.
-Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, etc. can be used. As the lactone, the lactone used for introducing the soft segment mentioned above, especially ε-caprolactone, can be used.

(b) Su-oligomer An oligomer that has hitherto been commonly used in active energy ray-curable coating compositions is used. They are linear or branched oligomers with a polymerizable ethylenically unsaturated group at the end of the polymer chain, and have a molecular weight of 200 or more, 50,
000 or less.

These oligomers are well known and include, for example, urethane acrylate resins, epoxy acrylate resins, polyester acrylate resins, spiran acrylate resins, polyether acrylate resins, silicone acrylate resins, polybutadiene acrylate resins,
Vinyl acrylate resins and the like are well known.

fcl monoethylene 1 monomer This component is also well known as a component of active energy ray-curable coating compositions, and includes methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl. Alkyl (meth)acrylates such as (meth)acrylate, lauryl (meth)acrylate, and nonyl (meth)acrylate 2-hydroxyethyl (meth)acrylate 2-hydroxypropyl (
Hydroxyalkyl (meth) such as meth)acrylates
Acrylates 2-ethoxyethyl (meth)acrylate, alkoxyalkyl (meth)acrylate-I-series 2-phenoxyethyl (meth)acrylate, such as 4-methoxybutyl (meth)acrylate.

Aryloxyalkyl acrylates such as 2-nonylphenoxyethyl (meth)acrylate, cycloalkyl acrylates such as cyclohexyl acrylate, cyclopentyl acrylate, isobornyl acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Examples include cycloalkenyl (meth)acrylates such as diethylaminoethyl (meth)acrylate-1-aminoalkyl acrylates, vinyl compounds such as styrene, vinyltoluene, vinyl acetate, and N-vinylpyrrolidone.

Active energy rays include ultraviolet rays, electron beams, X-rays, and radiation.

Ultraviolet rays include those with wavelengths of 1100n to 400nm. Among them, ultraviolet rays with short wavelengths of 200 to 300 nm are called deep UV. These energies range from 70 to 300 K Cal/m
ol, which is almost the same as the bond dissociation energy of organic compounds, and molecules absorb this light and become excited,
It is thought that it decomposes and generates radicals, which induce reactions. Also, electron beams, X-rays, and radiation (radiation includes α-rays, β-rays, γ-rays, hard X-rays, etc., among which β-rays with moderate penetration are used as accelerated electron beams) It is believed that irradiation with these high-energy rays produces ions, excited molecules, and radicals through interaction with orbital electrons of atoms in the material, and that curing progresses through a polymerization reaction caused by the radicals.

The coating composition of the present invention contains, by weight, 1 to 99% fat star oligomer as a film-forming component.

(contains 1-99% of bll star oligomer (c) 2-60% of monoethylenically unsaturated monomer). , may optionally contain other additives.

Photosensitizers include benzophenone, Michler's ketone,
Xanthone, thioxane I, 2-chlorothioxanthone, benzyl, 2-ethyl anthraquinone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-isopropyl-2-methyl-propiophenone, methylbenzoyl formate, benzoin methyl ether, hendiin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether,
Benzoin isobutyl ether, acetophenone, trichloroacetophenone, 2,2-jethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, etc. can be used.

Other additives include fillers (for example, inorganic fine powder such as colloidal silica and extender pigments), colorants, stabilizers, and the like.

When the composition of the present invention is used as a coating for an optical fiber, it can be applied to the surface of the optical fiber by known techniques such as die ironing, spraying, and fluid dipping, and then cured by irradiation with active energy rays.

Although the composition of the present invention has been explained by taking as an example the case where it is used for coating optical fibers, the composition of the present invention can be used not only as a coating material for optical fibers, but also as active energy ray-curable paints, adhesives, sealants, inks, etc. It can also be used as

Hereinafter, the present invention will be explained in detail with reference to Reference Examples, Examples, and Comparative Examples. In these, "parts" are based on weight.

Reference Example 1 A suspension of 41 parts of pentaerythritol, 348 parts of propylene oxide, 3.4 parts of potassium hydroxide and 20 parts of water
A solution was prepared. Put this suspension in an autoclave,
It was sealed and pressurized to 30 psi with nitrogen gas, heated to 95° C. over 30 minutes, and then cooled to room temperature. The reaction mixture was stirred during heating and cooling. Water, potassium hydroxide, and propylene oxide were removed from the reaction mixture to obtain a star polyol (tetrafunctional; molecular weight 1200).

Next, 150 parts of ethyl acetate, 0.3 parts of dibutyltin dilaurate, and 0.3 parts of hydroquinone were added to 100 parts of the star-shaped polyol obtained above in a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, and the mixture was stirred. Lower, temperature 40
While maintaining the temperature at °C, 37 parts of acryloyl isocyanate was added dropwise over 30 minutes. Stirring was carried out for 1 hour after dropping, and 22
After confirming the completion of the reaction by measuring the disappearance of the absorption of one NGO group due to 70<:tn-' by infrared spectroscopy,
Put the reaction mixture into the evaporator and 18mm+IIg
Heating at about 50°C for 1 hour under reduced pressure of
A functionally reactive star oligomer was obtained.

Reference Example 2 In a reaction vessel equipped with a stirrer, temperature needle and reflux condenser,
SANNIX GP-4000 (trifunctional polyol with propylene oxide added to glycerin).

400 parts of former Sanyo Chemical Co., Ltd. with a molecular weight of 400 and 5 parts of chilled acetate
00 parts and 63 parts of isophorone diisocyanate were added thereto, and 1 part of dibutyltin dilaurate was gradually added dropwise while cooling with water and keeping the temperature below 60°C. After the dropwise addition, the mixture was stirred for about 30 minutes, heated to maintain the temperature at 80°C, and stirred for 1 hour. Next, add 1 part of hydroquinone to this reaction system,
69 parts of Plaxel FA-1 (an adduct of 2-hydroxyethyl acrylate and ε-caprolactone; manufactured by Daicel Chemical Industries, Ltd.) was added dropwise over about 30 minutes. After the dropwise addition, stirring was carried out for 3 hours, and the completion of the reaction was confirmed by infrared spectroscopy using 4-degree infrared spectroscopy to confirm the disappearance of the absorption of one NGO group attributable to 2270 cm. The mixture was heated at °C for 1 hour and ethyl acetate was removed to obtain a trifunctional reactive star oligomer having an ethylenically unsaturated bond from a star polyalkyleneoxy group via a urethane bond.

Reference Example 3 Using the same apparatus as Reference Example 2, 103 parts of diethylenetriamine, 5.2 parts of dibutyltin oxide, and 2500 parts of ε-caprolactone were placed in a reaction vessel, and the temperature was raised to 18
The mixture was reacted for about 1 hour while being maintained at 0° C. to obtain a star polyol (trifunctional polyol; molecule (t2600)).

300 parts of ethyl acetate and 63 parts of isophorone diisocyanate were added to 260 parts of the star-shaped polyol obtained above, and 1.0.7 part of dibutyltin dilaure was gradually added dropwise while stirring and keeping the temperature at 80°C. Approximately 3 after dripping
Stir for 0 min, heat and maintain temperature at 50°C, and stir for about 1 hour. Next, 0.7 parts of hydroquinone was added to this reaction system, and 35 parts of 2-hydroxyethyl acrylate was added dropwise over about 30 minutes. After dropping, the disappearance of the -NGO group was confirmed using infrared spectroscopy, and the ethyl sulfate was removed using an evaporator, and the ethylenically unsaturated bond was extracted from the star-shaped polyalkyleneoxycarbonyl group via the urethane bond. A trifunctional reactive star oligomer was obtained.

Reference Example 4 Perform the same operation as in Reference Example 1 to obtain pentaerythritol 6.
A star-like polyether polyol (tetrafunctional; molecular weight 1,300) was obtained from 8 parts of polyether and 580 parts of propylene oxide.

Next, 650 parts of the star-shaped polyether polyol obtained above, 3.6 parts of dibutyltin oxide, and 1140 parts of ε-caprolactone were placed in a reaction vessel equipped with a stirrer, a temperature needle, a decanter, and a reflux condenser. Temperature 18
The mixture was reacted for about 1 hour while being maintained at 0° C. to obtain a star oligomer (tetrafunctional polyol; molecular weight 3500). Then, cool to room temperature, add 60 parts of xylene and 14 parts of acrylic acid.
After adding 4 parts and 2 parts of dibutyltin oxide, the reaction was carried out for 3 hours while keeping the temperature at 200°C to form an ester bond from the polyalkyleneoxycarbonyl group further connected to the chain part of the star-shaped polyalkyleneoxy group. A tetrafunctional reactive star oligomer having an ethylenically unsaturated bond was obtained.

Reference Example 5 300 parts of n-butyl acetate, 200 parts of polytetramethylene glycol with a molecular weight of 2000, and 1-44.4 parts of isophorone diisocyanate were charged into 11 reaction vessels equipped with a stirrer, a cooler, and a temperature control device. After stirring thoroughly,
1.0.25 part of dibutyltin dilaure was added, and the temperature was raised to 80°C and maintained for 1 hour. Next, 5 parts of 2-hydroxyethyl acrylate-1-23° and 0.28 parts of hydroquinone were added dropwise over 1 hour while keeping the system at 80"C, and the mixture was left for another 4 hours to absorb -NGO groups by TR. After confirming that it had disappeared, a polyether acrylate resin was obtained by removing the solvent under reduced pressure.

Reference Example 6 Using the same apparatus as used in Reference Example 5, 300 parts of n-butyl acetate and an average molecular weight of 200 parts having hydroxyl groups at both ends were prepared.
After thoroughly mixing 200 parts of No. 0 polybutadiene resin and 0.2 part of hydroquinone, 22 parts of methacryloyl isocyanate was added dropwise over 30 minutes while maintaining the temperature at 30°C. After the dropwise addition was completed, the reaction between methacryloyl isocyanate and hydroxyl group was checked using infrared absorption spectroscopy, and it was found that the peak at 2250cm-' caused by the -NGO group disappeared, the peak at 3300c+n-1 caused by the -Nl+ group appeared, and the acylcarbonyl group The appearance of a peak at 1760 cm', which was shifted from the normal carbonyl group due to , was confirmed. Furthermore, nuclear magnetic resonance spectroscopy (N
MR method) confirmed the appearance of a signal due to the -Nu group proton and a chemical shift of the signal due to the vinyl proton by about 0.3 ppm to a high magnetic field. A polybutadiene acrylate resin was thus obtained.

Example 1 70 parts of the polyether urethane acrylate resin obtained in Reference Example 5, 5 parts of the reactive star oligomer obtained in Reference Example 2, NK Ester AMP-60G (Shin Nakamura Chemical @
25 parts of a monoacrylate having a polyethylene oxide chain with a phenol-capped end) and 3 parts of benzoin methyl ether were mixed to obtain an ultraviolet curable optical fiber sub-coating composition.

A cured film thickness of 100 μm was applied to the composition on a glass plate.
A cured film could be obtained by coating the film so that it became as follows, and then performing ultraviolet treatment under the conditions shown below. The cured film was free from adhesion and had sufficient curability. Next, a sample with a hardening degree of 1 was peeled off from the glass plate and tested at 20°C as a tensile test sample, and the initial Young's modulus was 0.
40 kg/nJ.

Elongation rate -100%, initial Young's modulus at -20℃ -〇,
52 kg/mf, elongation rate = 180%, and initial Young's modulus at 60°C -0,32 kg/mJ, elongation rate 75%
The values are shown for each. In particular, there was no significant decrease in initial Young's modulus or elongation even at high temperatures, and the composition had sufficient flexibility, and was found to be suitable as a secondary coating composition for optical fibers.

High-pressure mercury lamp made by Nippon Battery - 2ON (BOW/cm)
Type.

The length direction of the lamp (using a condensing type device) is placed perpendicular to the conveyor traveling direction, and the conveyor speed is set to 3 m/min at a height of 80 mm from the conveyor surface.

-Nu By Ims/Nu For the measurement of the initial Young's modulus for a sample of film length 50fl, medium 1011 using a Raw Tensilon tensile tester (manufactured by Toyo Baldwin Co., Ltd., former model -100), please refer to Ims/
min, and for elongation measurements are carried out at a pulling rate of 50 fins/min.

Garth fiber - Glass fiber whose main component is quartz glass with a diameter of 1
A primary coated glass fiber could be obtained by spinning from a preform to a thickness of 25μ, coating the spinning eye composition directly to a thickness of 100μ, and performing ultraviolet treatment. The second coated glass fiber had sufficient flexibility even when bent without cracking or peeling.

Comparative Example 1 An optical fiber composition was obtained in the same manner as in Example 1 except that the reactive star oligomer was not used.

When such a composition was formed into a film in exactly the same manner as in Example 1 and a physical property test was performed, the initial Young's modulus = 0 at 20°C.
．． 33 kg/nJ, elongation rate -55%, and at -20°C, initial Young's modulus = 0.46 kg/mf, elongation rate -190%. Also, at 60℃, initial Young's modulus =
The elongation rate was -40% at 0.25 kg/nut, and the physical properties at high temperatures deteriorated significantly due to the insufficient degree of crosslinking.

Comparative Example 2 An optical fiber sub-coating composition was obtained in the same manner as in Example 1 except that 5 parts of trimethylolpropane triacrylate was used instead of the reactive star oligomer. When this composition was formed into a film in exactly the same manner as in Example 1 and physical property tests were conducted, the initial Young's modulus at 20°C was -2°6 kg/nJl, the elongation rate was -31%, and the initial Young's modulus at -20°C was Initial Young's modulus = 2.6 kg/m at 60°C, elongation rate -56%
The elongation rate was -28%, and both the initial Young's modulus and the elongation rate were not sufficient as an optical fiber-subsequent coating composition.

Example 2 Polybutadiene acrylate resin 9 obtained in Reference Example 6
An electron beam curable optical fiber secondary coating composition was obtained from 0 parts of the reactive star oligomer obtained in Reference Example 4 and 3 parts of trioctyl phosphate. Example 1
Similarly, such a composition is coated to a film thickness of 100μ, and an electron beam with an electron energy of 300 keV is irradiated with an electron current of 30 mA to give a dose of 3 Mrad to obtain a cured film with no surface adhesion. I was able to do that. The physical properties of the obtained film were an initial Young's modulus of -0 at 20°C.

4.5 kg/mJ, elongation rate -100%, and at -20℃ initial Young's modulus = 0.62 kg/n++ff, elongation rate = 110%, and at 60'c initial Young's modulus -0.35
kg/wM, elongation rate = 82%, optical fiber -
It had sufficient performance as a subsequent coating composition.

Example 3 Polyester urethane acrylate oligomer (obtained as a reaction product of polyester oligomer obtained from phthalic acid and 1.5-bentanediol and isophorone diisocyanate and 2-hydroxyethyl acrylate. Average molecular weight - about 1500) 70 parts and reference example A UV-curable optical fiber secondary coating composition was prepared from 10 parts of the reactive star oligomer obtained in Example 3, 20 parts of N-vinylpyrrolidone, and 2 parts of diacetophenone.

This composition was cured in the same manner as in Example 1, and the resulting film was subjected to physical property tests.
The initial Young's modulus was 45 kg/muff and the elongation rate was 48%. The obtained film was strong and had sufficient performance as an optical fiber secondary coating composition.

Comparative Example 3 A UV-curable coating composition was obtained in exactly the same manner as in Example 3, except that trimethylolpropane was used instead of the reactive star oligomer. When the physical properties of the film were tested in the same manner, the initial Young's modulus at 20°C was 75 kg/uJ.

A film was obtained in which the crosslinking density was increased to an elongation rate of 15%, and the hardness was increased, but the elongation was insufficient.

Example 4 50 parts of the same polyester urethane acrylate oligomer used in Example 3, 20 parts of the reactive star oligomer obtained in Reference Example 1, 1 part of dimethyl acrylamide
An optical fiber secondary coating composition was obtained consisting of 0 parts of epoxy acrylate resin (obtained by modifying a bisphenol A type epoxy resin with acrylic acid, average molecular weight of about 530), and 3 parts of diacetophenone. The film obtained from this composition had an initial Young's modulus of 70 kg/++J at 20°C and an elongation rate of 29%.

Example 5 15 parts of polybutadiene acrylate resin in Reference Example 6,
A cured composition for optical fibers was obtained, which consisted of 70 parts of the polyester urethane acrylate oligomer of Example 3, 15 parts of the reactive star oligomer obtained in Reference Example 1, and 0.5 parts of diacetophenone. A film obtained by curing this composition with an electron beam in the same manner as in Example 2 had an initial Young's modulus of 50 kg/++J and an elongation of 35% at 20°C.

Claims (2)

[Claims] (1) (a) A polyoxyalkylene chain, a polyoxyalkylene carbonyl chain, or a poly(oxyalkylene carbonyl chain) with a molecular weight of 60 to 4,000 extending from a nuclear substance having an active hydrogen atom bonded to an oxygen atom and/or a nitrogen atom. Each molecule of the nuclear substance has three or more soft segment chains selected from the group consisting of alkylene-oxyalkylene carbonyl chains, and is bonded to each end of the soft segment chain via an ester bond, a urethane bond, or an acyl urethane bond. (b) a star oligomer containing a polymerizable ethylenically unsaturated group at the end of the polymer chain and having a molecular weight of 200 to 50,000; An active energy ray-curable coating composition comprising 1 to 99% by weight of a non-star oligomer and (c) 2 to 60% by weight of a polymerizable monoethylenically unsaturated monomer. (2) The active energy ray-curable coating composition according to item 1, which contains an initiator and/or a photosensitizer.