JPH0552328B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an ultraviolet curable resin composition, and more particularly, the present invention relates to an ultraviolet curable resin composition, and more particularly, it has reduced adhesive strength with an optical fiber core, and is suitable as a primary coating material and a secondary coating material for an optical fiber core. The present invention relates to an ultraviolet curable resin composition. [Prior art] Optical fiber is used by forming a core of two types of glass or plastic with different refractive indexes into a core-sheath shape, and applying a primary coating and a secondary coating to the outer periphery of this core. Since it has the property of transmitting light from one end to the other without scattering it, communication technology that takes advantage of this property is being put into practical use. An ultraviolet curable resin composition is used as the core coating material, primary coating material, and secondary coating material. By the way, when connecting optical fibers,
The coating material must be removed from the core at each end. However, because there is strong adhesion between the primary coating material and the core, and between the primary coating material and the secondary coating material, it is difficult to remove these coating materials, so-called peeling, and this may damage the core. There were drawbacks such as giving. [Object of the Invention] An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide an ultraviolet curable resin composition with good so-called peelability. [Structure of the Invention] The resin composition of the present invention that achieves the above object is an ultraviolet curable resin composition comprising an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator, in which the acrylic oligomer is diphenylmethane diisocyanate and a molecular weight of 650 to 650. Terminal obtained from 1300 polytetramethylene glycol and
Using urethane acrylate obtained by acrylating NCO's urethane prepolymer with a monoacrylate having one OH group, the amount of the acrylic monomer used is 10 to 100 parts by weight per 100 parts by weight of the acrylic oligomer, and internal mold release is performed. It is characterized by containing 0.1 to 5 parts by weight of stearic acid, metal stearate, or phosphates as an agent per 100 parts by weight of the total amount of the acrylic oligomer and acrylic monomer. The acrylic oligomer in the present invention includes:
Urethane acrylate, epoxy acrylate,
Polyether acrylate, polyester acrylate, melamine acrylate, etc. are used, and urethane acrylate is preferably used. This urethane acrylate is composed of diphenylmethane diisocyanate and a molecular weight of 650 as shown in the formula below.
~1300 polytetramethylene glycol by acrylation of NCO-terminated urethane prepolymers obtained from polytetramethylene glycol with monoacrylates having one OH group. In the present invention, diphenylmethane diisocyanate is used as the diisocyanate as described above, and good results are given to the physical properties of the resulting resin composition. That is, the urethane acrylate using toluene diisocyanate has a lower elastic modulus than the urethane acrylate in the present invention. Further, in the present invention, the use of polytetramethylene glycol having a molecular weight of 650 to 1300 in the production of urethane acrylate also contributes to its suitability as a coating material for an optical fiber core. For example, urethane acrylate using lactone polyol has poor UV curability;
Urethane acrylate using polypropylene glycol or polyester polyol has poor heat and humidity resistance and water resistance. Polytetramethylene glycol has a molecular weight of
The range of 650 to 1300 is elongated, the elastic modulus is large, and both are balanced. It is difficult to produce polytetramethylene glycol with a molecular weight of less than 650, and resin compositions using polytetramethylene glycol with a molecular weight of more than 1300 have too small an elastic modulus and low elongation. As the monoacrylate having one OH group, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, etc. are used. Acrylic monomers used in the present invention include isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, and 2-methoxyethyl acrylate. Acrylate, 2-
Butoxyethyl acrylate, 2-phenoxyethyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, etc. are used, and 2-phenoxyethyl acrylate and dicyclopentenyl acrylate are preferably used. Such acrylic monomers can be used singly or in combination, and the amount used is 10 to 100 parts by weight per 100 parts by weight of the urethane acrylate. If the amount of monoacrylate used is less than 10 parts by weight, the workability of the resin composition of the present invention will deteriorate, and if it exceeds 100 parts by weight, the workability and elastic modulus will decrease. Furthermore, in the present invention, as a photopolymerization initiator,
Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether,
benzophenone, 4-methoxybenzophenone,
1-hydroxycyclohexyl phenyl ketone,
Benzyl dimethyl ketal, benzyl-β-methoxyethyl acetal, methylbenzoyl, acetophenone, 2,2-diethoxyacetophenone, diethylthioxanthone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, 2-hydroxy-2 -Methylpropiophenone, 2-methoxyanthraquinone, etc. are used,
1-hydroxycyclohexyl phenyl ketone,
Benzyl dimethyl ketal is preferably used. Such photopolymerization initiators may be used alone or in combination, and the amount used is 0.5 to 10 parts by weight per 100 parts by weight of the total amount of the urethane acrylate and acrylic monomer. If the amount of photopolymerization initiator used is less than 0.5 parts by weight, the curing speed of the resin composition of the present invention will decrease, while if it is added in excess of 10 parts by weight, it will not only cause a decrease in heat and humidity resistance but also cause the resin composition to deteriorate. increases the cost of the composition. Furthermore, in the present invention, in order to reduce the adhesive force between the core and the primary coating material, and between the primary coating material and the secondary coating material, and to improve peelability, stearic acid, Metal stearates, such as zinc stearate, aluminum stearate, calcium stearate, etc., or phosphates, such as phosphate alcohols, are used, preferably phosphate alcohols. The amount of the internal mold release agent used is 0.1 to 5 parts by weight per 100 parts by weight of the total amount of the acrylic oligomer and acrylic monomer. If the amount of internal mold release agent used is less than 0.1 part by weight, the effect of reducing the adhesive force of the resin composition is small, and if it exceeds 5 parts by weight, the effect of reducing the adhesive force due to the increase in the internal mold release agent is significant. It disappears. In addition, in the present invention, a thermal polymerization inhibitor and a photosensitizer can also be added as necessary. As the thermal polymerization inhibitor, hydroquinone, methoquinone, p-benzoquinone, t-butylhydroquinone, etc. are used, and the amount used is 0.001 to 1.0% of the total amount of urethane acrylate, acrylic monomer, and diluent. Such a thermal polymerization inhibitor has the function of improving the thermal stability of the resin composition of the present invention during storage. In addition, photosensitizers function as catalysts that promote ultraviolet curing, and include triethylamine,
2-dimethylaminoethanol, N-methyldiethanolamine, triethanolamine, 3-dimethylamino-1-propanol, 2-dimethylamino-1-propanol, p-dimethylaminobenzoic acid, isocyanyl p-dimethylaminobenzoate, p- Methyl dimethylaminobenzoate and the like are used. [Effects of the Invention] As described above, according to the present invention, in an ultraviolet curable resin composition comprising an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator, diphenylmethane diisocyanate and a polyester having a molecular weight of 650 to 1300 are used as the acrylic oligomer. Using urethane acrylate obtained by acrylating a terminal NCO urethane prepolymer obtained from tetramethylene glycol with a monoacrylate having one OH group in the ester group, the amount of acrylic monomer used is per 100 parts by weight of acrylic oligomer.
10 to 100 parts by weight, and further contains 0.1 to 5 parts by weight of stearic acid, stearic acid metal salt, or phosphates as an internal mold release agent per 100 parts by weight of the total amount of the acrylic oligomer and acrylic monomer. , the following effects are achieved. B. The resin composition of the present invention has good ultraviolet curability, heat and humidity resistance, and water resistance, has high elongation and elastic modulus, and has excellent workability. Adhesion between the primary coating material or the primary coating material and the secondary coating material is reduced by the resin composition of the invention. Therefore, the covering material can be easily peeled off when connecting the cores. (b) As described above, the adhesive strength of the coating material is reduced, so even if stress due to the difference in thermal expansion coefficient between the core and coating material is applied to the optical fiber, or stress due to bending is applied, the primary Relative slippage occurs between the coating material and the secondary coating material, and the stress of the optical fiber itself is not transmitted, resulting in no increase in transmission loss. C. Therefore, the ultraviolet curable resin composition of the present invention is
It is suitable as a primary coating material and a secondary coating material for an optical fiber core. [Examples] Example 1 Production of urethane acrylate. Put 2 moles of diphenylmethane diisocyanate into a 3-4-necked flask equipped with a stirrer, thermometer, and dropping funnel, heat to 60°C, stir, and add polytetramethylene glycol with a molecular weight of 850 while flowing _N2 gas. 1 mol was added dropwise and reacted for 4 hours,
A urethane prepolymer was produced. Completion of the reaction was confirmed by checking NCO%. Then, 2-hydroxyethyl acrylate 2
Mol was added dropwise and reacted for 6 hours to produce urethane acrylate. The reaction products were analyzed by infrared spectroscopy, but NCO
No peak was observed. Examples 2, 3, 4, 5 and Comparative Examples 1 and 2 Using the urethane acrylate produced in Example 1 as an acrylic oligomer, an ultraviolet curable resin composition consisting of an acrylic monomer, a photopolymerization initiator, and an internal mold release agent was prepared. The adhesive strength and curing speed were measured. The results are shown in the table below. In addition, Comparative Example 1 in which no internal mold release agent was used, and Comparative Example 2 in which the amount of internal mold release agent used exceeded 5 parts by weight were investigated, and the results are also shown in the table.

[Table] As is clear from the above table, the ultraviolet resin compositions of the present invention have low adhesive strength and high curing speed. Therefore, it is suitable as a primary coating material and a secondary coating material for an optical fiber core. Note that Comparative Example 1 had a high adhesive strength, and Comparative Example 2
However, the curing speed is slow, making it unsuitable as a core coating material.

Claims (1)

[Claims] 1. In an ultraviolet curable resin composition comprising an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator, the acrylic oligomer is a urethane prepolymer with a terminal NCO obtained from diphenylmethane diisocyanate and polytetramethylene glycol having a molecular weight of 650 to 1300. Urethane acrylate obtained by acrylation with a monoacrylate having one OH group is used, the amount of the acrylic monomer used is 10 to 100 parts by weight per 100 parts by weight of the acrylic oligomer, and stearic acid and stearin are used as internal mold release agents. An ultraviolet curable resin composition comprising 0.1 to 5 parts by weight of acid metal salts or phosphates per 100 parts by weight of the acrylic oligomer and acrylic monomer.