KR100312040B1 - UV curable compositions for optical fibers - Google Patents

Abstract

The present invention relates to an ultraviolet curable secondary coating resin composition used for optical fiber production. Important properties required for the resin for secondary coating include high tensile modulus and high elongation, excellent water resistance and hardenability, and the present invention provides a new oligomer having a large number of urethane bonds or urea bonds in a molecule. By using synthetically, the required physical properties were achieved. The present invention is a urethane (meth) acrylate oligomer; Photocurable (meth) acrylate monomers; A photocurable resin composition for optical fiber secondary coating comprising at least one photoinitiator capable of being initiated by ultraviolet light, wherein the urethane (methane) acrylate oligomer is a diisocyanate compound; A mixture of at least one monomolecular diol having a molecular weight of less than 400 and a polyol having a molecular weight of 400 to 3,000; And synthesized from a (meth) acrylate compound having a hydroxyl group. By using the oligomer developed in the present invention, it is possible to easily achieve the physical properties of the secondary coating resin having a high toughness characteristic with little decrease in elongation while showing an excellent effect on improving the tensile modulus.

Description

UV curable compositions for optical fiber coatings

The present invention relates to an ultraviolet curable resin composition for optical fiber coating, and more specifically, a rigid urethane methacrylate oligomer or a urethane acrylate oligomer (hereinafter referred to as 'urethane (meth) acrylate oligomer'); Photocurable methacrylate monomers or acrylate monomers (hereinafter referred to as '(meth) acrylate monomers'); And it relates to an ultraviolet curable resin composition for optical fiber secondary coating containing a photoinitiator. The cross-sectional view of the optical fiber and the tomographic cutaway perspective view are shown in FIGS. 1 and 2.

Optical fibers are generally composed of a shim (1) that has a high refractive index and serves as a light passage, a clad that has a low refractive index and serves as a reflective surface of light, and a flexible polymer having a low glass transition temperature and a low tensile modulus. It consists of a primary coating (4), which serves as a shock buffer of the fiber, and a secondary coating (5), which serves to protect the glass fiber from external pressure by being composed of a rigid polymer having a high glass transition temperature and a high tensile modulus. The optical transmission principle of the optical fiber is based on the principle that when light is incident on the core part, the light is totally reflected by the difference in refractive index at the interface with the clad having the low refractive index. However, when the optical fiber is bent or the like, a clad mode phenomenon occurs in which part of the light traveling through the seam (1) portion is refracted and exits to the clad (2) layer. Returning to the part causes noise phenomenon in the optical signal. Therefore, in order to prevent this, all of the light exiting with the refractive index of the primary coating 4 set to 1.48 or more higher than the refractive index of the cladding and the refractive index of the secondary coating 5 set to 1.50 or more is refracted toward the seam 1. It has an optical structure that allows it to disappear.

In addition, the primary and secondary coatings (4) and (5) impart mechanical strength to the optical fiber, and also impart water resistance and moisture permeability to the glass fiber to improve long-term stability due to changes in the external environment, and in particular, transmission loss of light. This is an essential component that contributes to minimizing microbending, which is the biggest cause of this problem. Micro bending is a phenomenon in which fine bending occurs in an optical fiber due to external pressure or the like and causes diffuse reflection of light to cause transmission loss. Therefore, in order to reduce light loss due to micro bending, the primary coating is composed of a flexible resin having a low glass transition temperature (below 0 ° C.) and a low tensile modulus (below 5 MPa). In order to protect the glass fiber, it is composed of a resin having excellent mechanical properties with high tensile modulus (25 ° C, 1000 MPa or more).

In general, the ultraviolet curable resin composition for optical fiber coating comprises a polyurethane (meth) acrylate having a number average molecular weight of 1,000 to 15,000, a photocurable reactive monomer diluent, and a photoinitiator. Conventionally, there have been methods for adding various oligomers having high strength or adding polyfunctional monomer diluents to improve the mechanical properties of secondary coating resins. For example, epoxy acrylates such as bisphenol didiacrylate diglycidyl ether may be used in combination with polyurethane acrylate oligomers (US Pat. No. 4,472,019) or high tensile diols such as polycarbonate diols may be used with isocyanates. Addition of reacted polyurethane acrylate oligomer (US Pat. No. 4,514,037) or polyfunctional polyurethane acrylate oligomer to increase crosslinking degree (US Pat. No. 4,690,501, US Pat. No. 4,690,502), polyurethane acrylic There is an example in which physical properties are improved by using a mixture of a late oligomer and isocyanurate (US Pat. No. 4,902,440, Japanese Patent Laid-Open No. 62-50315). Moreover, what introduce | transduced the amine group into the polyurethane acrylate oligomer was also applied (Japanese Patent Laid-Open No. 62-78131). However, when the secondary coating resin is prepared by the above-described method, the coating film shows a high tensile modulus of elasticity but tends to decrease in elongation, and thus does not sufficiently cope with external pressure, that is, side pressure, bending, and the like. And the like can cause light transmission loss. In addition, problems such as solvent resistance, water resistance, an increase in shrinkage rate, and a decrease in miscibility are also caused. Further, a photocurable resin composition for optical fiber secondary coating usually contains rigid polyurethane (meth) acrylate as its main composition. Hard polyurethane (meth) acrylates, unlike soft materials, generally have high tensile modulus and high elongation rate, which are required in resin compositions for optical fiber secondary coatings. There is a problem that is difficult to give together.

The present invention is to solve the problems of the conventional UV-curable resin composition for optical fiber secondary coating as described above, and to provide a resin composition having a high tensile modulus while minimizing the deterioration of characteristics such as decrease in elongation of the coating film. Polyurethanes synthesized only with diisocyanates and monomolecular diols with low molecular weight have a low number-average molecular weight and have a very low elongation, but a high tensile modulus, and a polyurethane synthesized only with diisocyanates and relatively high molecular weight polyols. In this case, the number-average molecular weight is soft and the elongation rate is large while the tensile modulus tends to be greatly decreased. From the mixture of mono-molecular diols and polyols, we have begun to develop urethane prepolymers suitable for the properties of optical fiber secondary coatings, and after a long period of research, we have completed the present invention. ) Acrylate has a low elongation when the tensile modulus is increased, but a mixture of monomolecular diol or monomolecular diamine and polyol having a relatively low molecular weight; In the case where urethane bonds are introduced by reacting the diisocyanate at an appropriate mole ratio, the elongation rate increases with an increase in the tensile modulus. After reacting diisosinate to synthesize a urethane or urea (meth) acrylate oligomer having a high density urethane bond, a photocurable monomer diluent and a photoinitiator are mixed therewith to have a tensile modulus of 1000 MPa or more and an elongation of 10% or more. A photocurable resin composition for optical fiber secondary coating was obtained.

1 is a cross-sectional view of an optical fiber

Fig. 2 is a perspective view of tomography of an optical fiber

* Explanation of symbols on main parts of drawing *

1 ... core 2 ... clad 3 ... glass fiber 4 ... 1st coating 5 ... 2nd coating

Hereinafter, the present invention will be described in detail. Compositions of the present invention include urethane (meth) acrylate oligomers; Photocurable (meth) acrylate monomer diluents; And an ultraviolet curable resin composition for optical fiber secondary coating containing a photoinitiator, wherein the urethane (meth) acrylate oligomer is a diisocyanate; A mixture of at least one monomolecular diol having a molecular weight of less than 400 and a polyol having a molecular weight of 400 to 3,000; And a urethane (meth) acrylate oligomer having a number average molecular weight of 800 to 5,000 containing a high-density urethane bond (4-12) in the molecule by reacting a hydroxyl-containing (metal) acrylate compound. The ultraviolet curable resin composition for this invention is related. In addition, when monomolecular diamine is used instead of monomolecular diol, the urethane urea (meth) acrylate oligomer containing a urea bond can be manufactured. In addition, this invention is 60-75 weight% of said urethane (meth) acrylate oligomers. ; 20-50% by weight of a photocurable (meth) acrylate monomer diluent; And it is a resin composition for UV curing for optical fiber secondary coating, including 1 to 5% by weight photoinitiator.

The urethane bond (or urea bond) in the molecule is a mixture of 1 to 1.67 mol (mole) of at least one monomolecular diol (or monomolecular diamine) having a molecular weight of less than 400 and a polyol having a molecular weight of 400 to 3,000 to 2 moles of diisocyanate ( Mole) can be introduced at a high density of 4 to 12 densities per molecule by controlling the reaction so that the number average molecular weight is polymerized in the range of 800 to 5,000. There are various known methods for introducing a bond, but preferred methods include reacting with 2 moles of hydroxyl group-containing (meth) acrylate per 1 mole of urethane prepolymer (prepolymer method), At this time, the hydroxyl group-containing (meth) acrylate has 2 to 6 carbons in the alkyl group, preferably 2-hydroxyethyl (meth) acrylate, 2-hydroxyprop (Meth) acrylate, it is preferable to use, 2-hydroxybutyl (meth) acrylate. In another method, 0.34-1 mole of hydroxyl group-containing (meth) acrylate is reacted with 1 mole diisocyanate and then reacted with 0.5-0.83 mole of a mixture of one or more monomolecular diols and one or more polyols. There is a method for producing a urethane diacrylate oligomer having a double bond (acrylate isocyanate method). Examples of the diisocyanate include isophorone diisocyanate, 2,4-toluene diisocyanate and isomers thereof, hexamethylene diisocyanate and lysine di Isocyanate, trimethylhexamethylene diisocyanate, 2,2-bis-4'-propane isocyanate, 6-isopropyl-1,3-phenyldiisocyanate, bis (2-isocyanate ethyl) -fumarate, 1,6-hexanedi Isocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethylphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane Socyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate, etc. can be used, Preferably it is 2, It is preferable to use 4-toluene diisocyanate and its isomers, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate and the like. Monomolecular diols having a molecular weight of less than 400 include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentylglycol, 1,4- Cyclohexane dimethanol, bisphenol A, bisphenol F, reduced bisphenol A, reduced bisphenol F, dicyclopenta diol, tricyclodecanediol, and the like, and compounds having three or more hydroxyl groups in the molecule, that is, glycerol, trimethylol ethane, Trimethylolpropane, pentaerythritol, sorbose, and sorbitol may be mixed and used. As the polyol having a molecular weight of 400 to 3,000, a polyether polyol, a polyester polyol, a polycarbonate polyol, or a polycaprolactone polyol is used in combination with the above monomolecular diol. Examples of the polyether polyols used may include copolymerization forms of polyethylene glycol, 1,2-polypropylene glycol, 1,3-polypropylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, and the like. As the polyester polyol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, polytetramethylene glycol, tetramethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol , Diols such as 1,4-cyclohexanedimethanol, 3-methyl-1,8-octanediol, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumalic acid, adipic acid, sebacic acid, etc. A polyester polyol in the form reacted with an acid of or a copolymerized form thereof can be exemplified. Examples of polycarbonate polyols include 1,6-hexane polycarbonate, and polycaprolactone polyols include ε-caprolactone and ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butanediol, Reaction with diols such as 1,4-butanediol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol One form can be illustrated.

Examples of the diamines include ethylenediamine, propylenediamine, butylenediamine, 4,4-diaminodiphenylmethane, 3,3'-dichloro 4,4'-diaminodiphenylmethane, benzidine, 3,3 '-Dimethylbenzidine, p-phenylenediamine and the like can be mentioned. Further, as the monofunctional monomer among the photocurable acrylate monomers, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, t- Octyl (meth) acrylate, N, N-dimethyl (meth) acrylamide, N-vinyl caprolactam, N-vinylpyrrolidone, isobutoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, bonyl ( Meta) acrylate, isobonyl (meth) acrylate, tricyclotecanyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentadiene (meth) acrylate, methoxy polypropylene glycol (meth) Acrylate, methoxy polyethylene glycol ( Meta) acrylate, ethoxyethoxyethyl (meth) acrylate, methoxyethylene glycol (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, phenoxyethyl (meth ) Acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, epoxydiethylene glycol (meth) acrylate, butoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, styryl (Meth) acrylate, octadecyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, undecyl (meth) acrylate, isodecyl (meth) acrylate, decyl (meth) Acrylate, nonyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, octyl (meth) acrylate, heptyl (meth) acrylate, hexyl (meth) Acrylate, isoamyl (meth) acrylate, pentyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, amyl (meth) acrylate, butyl (metal) acrylate, iso Propyl (meth) acrylate, propyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) acrylate, N, N-diethyl (meth) acrylamide, N, N'-dimethyl-aminopropyl (meth ) Acrylates and the like, and examples of the polyfunctional monomers include trimethylol propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene glycol di (meth) acrylate, and 1,6-hexane. Dioldi (meth) acrylate, tripropylene glycol dia Relate, trimethylolpropane trioxyethyl (meth) acrylate, tricyclodecanedimethanol diacrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tricyclodecanedimethol di ( Meth) acrylate etc. can be illustrated. In addition, silicone acrylate may be mixed with the acrylate monomer in order to improve the tensile property of the coating film, and examples of the silicone acrylate may include acrylate-modified polysiloxane and the like, and may be used alone or in combination of two or more thereof. .

The composition of the present invention requires a photoinitiator and used initiators include 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenyl-acetophenone, xanthone, benzaldehyde, anthraquinone, 3-methylaceto Phenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoinethyl ether, 1- (4-isopropyl-phenol) -2 Hydroxy-2-methyl propane-l-one, thioxanthone, etc. can be exemplified, and commercially supplied products include Irgacure184, 651, 500, 819, 907, 1700, 1800 (Shibagai Corporation) and Darocure 1116, 1173. (Merck Co., Ltd.), Lucirine LR8728 (BASF Co., Ltd.), Ubecyl-936 (CBC), etc., and these may be used alone or in combination of two or more thereof. Small photosensitizers such as diethylamine can also be added.

In addition to the above composition, antioxidants, light stabilizers, silane coupling agents, thermal polymerization inhibitors, leveling agents, surfactants and the like may also be added.

Next, the present invention will be described by way of Examples, but the present invention is not necessarily limited to the following Examples. In addition, all expressed in% are weight% unless otherwise stated.

Synthesis Example 1.

Into a 3-liter round bottom flask with a stirrer was added 696.0 g (4 mole) of 2,4-toluene diisocyanate and 0.15 g of dibutyltindilaurate. After the reaction temperature was maintained at 70 ° C., 1000.0 g (1 mole) of polytetramethylene glycol having a number average molecular weight of 1000 and 180.0 g (2 mole) of 1,4-butanediol were added to the reactor for 2 hours. After the completion of the addition, the reaction was allowed to react until the NCO concentration of the reactant reached the theoretical NCO concentration, and the reaction temperature was lowered to 50 ° C. and 1 g of methylhydroquinone was added as a polymerization inhibitor. Subsequently, the reaction rate may be slowed down by the increase of the viscosity. In order to increase the stirring effect, 255.5 g of butanediol diacrylate is added to the reactive diluent and 232.0 g (2 mole) 2-hydroxyethyl acrylate is gradually added. The reaction was advanced. After the addition, the reaction was terminated after confirming that the NCO peak of 2270cm ^-1 disappeared by infrared spectroscopy while maintaining the reaction temperature at 70 ° C for 6 hours.

Example 1.

60 wt% of the urethane acrylate oligomer synthesized in Synthesis Example 1 was added to a reactor equipped with a stirrer, 4.4 wt% tetrahydrofurfuryl acrylate, 8.6 wt% propylene glycol monoacrylate, and 20 wt% butanediol diacryl. 0.5% by weight of methylhydroquinone was added as a rate, 3.0% by weight of acrylate-modified polysiloxane (TEGORad 2100 (Tego)), 0.5% by weight of antioxidant (Irganox 1035 (Shibagai Co.)) and polymerization inhibitor. As a photoinitiator, 2.5 wt% of Irgacure 651 (Shibagai Co., Ltd.) was added, and 0.5 wt% of diethylamine was added as a photosensitizer, and the mixture was stirred at 400 rpm for 30 minutes at room temperature. A clear liquid composition having a viscosity of 1500 cps at 50 ° C. was obtained.

The obtained liquid composition was molded in the following manner and the physical properties thereof were measured.

① Film forming

Using a bar coater (bar coater) on the glass plate was coated with a thickness of 0.1mm and then irradiated with 1.0J / cm ² in an ultraviolet curing machine to prepare a cured film.

② Tensile Properties (Tensile Modulus, Elongation, Tensile Strength)

Using a universal tensile tester, the cured film was taken in a size of 10 mm x 80 mm at 25 ° C. and 50% relative humidity, and measured at a speed of 5 mm per minute with a distance of 50 mm for a specimen use gauge.

③ water resistance

Take the cured film into the size of 100mm × 100mm and measure the weight (A), soak it in 72 ℃ distilled water for 72 hours, take it out again, wipe off the surface with dust-free toilet paper, and measure the weight (B) again. After drying at room temperature and humidity, the weight (C) was measured. Finally, the following equation was used.

% Change in weight = (B-A) / A × 100

% Extraction = (A-C) / A × 100

④ Gel fraction (Soxlet method)

The initial weight (Wo) of the cured film was measured, and then extracted in a soxhlet extraction flask using methyl ethyl ketone as a solvent for 24 hours, and the residue was dried at 50 ° C. for 72 hours to obtain a weight (W ₁ ). It measures and obtains a gel fraction by following Formula.

Gel fraction (%) = W ₁ / Wo × 100

Example 2.

70% by weight of the urethane acrylate oligomer synthesized in Synthesis Example 1 was added to a reactor equipped with a stirrer, 3% by weight of tetrahydrofurfuryl acrylate, 6% by weight of propylene glycol monoacrylate, and 14% by weight of butanediol diacryl. 0.5 wt% of methylhydroquinone is added as a rate, a triangular-% acrylate-modified polysiloxane (TEGORad 2100 (Tego)), 0.5 wt% of an antioxidant (Irgacure 1035, Ciba-Geigy Co.) and a polymerization inhibitor. As a photoinitiator, 2.5 wt% of Irgacure 651 (Shibagai Co., Ltd.) was added, 0.5 wt% of diethylamine was added as a photosensitizer, and the mixture was stirred at 400 rpm for 30 minutes at room temperature. A clear liquid composition having a viscosity of 2500 cps at 50 ° C. was obtained and the physical properties of the cured film were measured by the method illustrated in Example 1.

Example 3.

75% by weight of the urethane acrylate synthesized in Synthesis Example 1 was added to a reactor equipped with a stirrer, 2.3% by weight of tetrahydrofurfuryl acrylate, 4.7% by weight of propylene glycol monoacrylate, and 11% by weight of butanediol diacrylate. , 0.5% by weight of methylhydroquinone was added as 3% by weight of acrylate-modified polysiloxane (TEGORad 2100 (Tego)), 0.5% by weight of antioxidant (Irganox 1035 (Shibagai Co.)) and polymerization inhibitor. As a photoinitiator, 2.5 wt% of Irgacure 651 (Shibagai Co., Ltd.) was added, and 0.5 wt% of diethylamine was added as a photosensitizer, followed by mixing at 400 rpm for 30 minutes at room temperature. A clear liquid composition having a viscosity of 2800 cps at 50 ° C. was obtained and the physical properties of the cured film were measured by the method illustrated in Example 1.

Comparative Example 1.

Into a 3-liter round bottom flask with a stirrer was added 500.0 g (2.88 mole) of 2,4-toluene diisocyanate and 0.11 g of dibutyltin dilaurate as a urethane reaction catalyst. After the reaction temperature was maintained at 70 ° C, 1436.0 g (1.44 mole) of polytetramethylene glycol having a number average molecular weight of 1000 was added thereto while being careful not to exceed the reaction temperature of 70 ° C. After completion of the reaction, the reactant is allowed to react until the NCO concentration of the reactant reaches the theoretical NCO concentration. Then, the reaction temperature is reduced to 50 ° C and 0.8 g of methylhydroquinone is added as a polymerization inhibitor. In addition, 153.8g of hexanediol diacrylate in a reactive diluent is added and 333.4g (2.88 mole) of 2-hydroxyethyl acrylate is gradually added to increase the stirring effect because the reaction rate may be slowed down by the increase of the viscosity. The reaction was advanced. At this time, the reaction temperature should be careful not to exceed 60 ℃ and the reaction was terminated after confirming that the NCO peak of 2270cm ^-1 disappeared by infrared spectroscopy while maintaining the reaction temperature at 60 ℃ for 5-6 hours after the addition.

The polyurethane acrylate synthesized in Synthesis Example 1 was substituted in the same manner as in Example 3 using the polyurethane acrylate synthesized as described above. A liquid composition having a viscosity of 1900 cps at 50 ° C. was obtained and the physical properties of the cured film were measured by the method illustrated in Example 1.

Comparative Example 2.

60% by weight of the urethane acrylate synthesized in Comparative Example 1 was added to a reactor equipped with a stirrer, 33% by weight of pentaerythritol triacrylate, 3.0% by weight of acrylate-modified polysiloxane (TEGORad 2100 (TEGO Co.)), 0.5 0.5% by weight of methylhydroquinone is added as a weight% antioxidant (Irganox 1035 (Shibagai Co.)) and a polymerization inhibitor. As a photoinitiator, 2.5 wt% of Irgacure 651 (Shibagai Co., Ltd.) was added thereto, and 0.5 wt% of diethylamine was added thereto as a photosensitizer. The mixture was stirred at room temperature at 400 rpm for 30 minutes. A transparent liquid composition having a viscosity of 2100 cps at 50 ° C. was obtained, and the physical properties of the cured film were measured by the method exemplified in Example 1, and the experimental results are shown in Table 1 below.

As can be seen from Table 1, when using the oligomers developed in the present invention, the physical properties of the cured coating film have a superior value of 1000 MPa or more (US Patent No. 4,904,051), which is the tensile modulus required for the optical fiber secondary coating agent. Elongation is also excellent value of more than 10%. On the other hand, as shown in Comparative Examples 1 and 2, oligomers in which low molecular weight monomolecular diols are not introduced into the urethane segment, that is, low density of hard segments in which monomolecular diols and polyglycols are not introduced into the urethane bond together It can be seen that the film properties are generally reduced when the mixture is used using an oligomer, and when the tensile modulus is increased by using a trifunctional diluent, a decrease in elongation is remarkable. As a result, it can be seen that the ultraviolet curable resin composition for optical fiber coating developed in the present invention shows an excellent effect on the improvement of tensile modulus and tensile strength, while the decrease in elongation is small and has excellent toughness. Therefore, the liquid composition of the present invention is particularly suitable for use as a resin composition for optical fiber secondary coating, and as can be seen from the result of 0% of water extract, it can be seen that the water resistance is also very strong against moisture. In addition, it can be seen that the gel fraction is more than 90% and excellent in curability. Overall, the results of the measurement show that the optical fiber curable resin composition for the secondary coating has superior characteristics.

Claims (3)

Urethane (meth) acrylate oligomers; Photocurable (meth) acrylate monomer diluents; In the ultraviolet curable resin composition for optical fiber secondary coating comprising a photoinitiator, The urethane (meth) acrylate oligomer is a diisocyanate compound; A mixture of at least one monomolecular diol or monomolecular diamine having a molecular weight of less than 400 and a polyol having a molecular weight of 400 to 3,000; And a urethane (meth) acrylate oligomer or urethane urea (meth) acrylate oligomer having a number average molecular weight of 800 to 5,000 synthesized from a (meth) acrylate compound having a hydroxyl group and a number average urethane bond per molecule in the range of 4 to 12 UV-curable resin composition for optical fiber secondary coating, characterized in that. The method of claim 1, wherein the ultraviolet curable resin composition for secondary coating of the optical fiber is 60 to 75% by weight of a urethane (meth) acrylate oligomer; 20-50% by weight of a photocurable (meth) acrylate monomer diluent; And 1 to 5% by weight of a photoinitiator UV curable resin composition for optical fiber secondary coating. The UV curable resin composition for optical fiber secondary coating according to claim 1 or 2, wherein the cured coating film of the UV curable resin composition for optical fiber secondary coating has a tensile modulus of 1200 MPa to 1700 MPa and an elongation of 10.0% to 19%.