JPS59182259A - Covering material for optical fiber - Google Patents

Abstract

PURPOSE:The titled covering material having low modulus of elasticity, consisting of a polyfunctional (meth)acrylate and a specific acrylate. CONSTITUTION:A polyfunctional (meth)acrylate (e.g., 1,4-polybutadiene acrylate) having >=500mol.wt. is blended with an acrylate shown by the formula (m and n are positive integer), a photopolymerization initiator (e.g., benzophenone), and if necessary, a silane coupling agent, an ultraviolet absorber, an antioxidant, etc. The prepared covering material has low modulus of elasticity and high curing rate, so covering speed of optical fiber can be increased, to give optical fiber having improved transmitting properties.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to materials for optical transmission glass fibers (herein abbreviated as optical fibers), specifically, materials with low elastic modulus and fast curing speed. Regarding coating materials.

[Prior art]

Silicone rubber (polydimethylsiloxane, polydimethylsiloxane, Polymethylphenylsiloxane) is used. The primary coating material for optical fibers needs to have a low elastic modulus and glass transition temperature from the viewpoint of loss of transmission, and from the viewpoint of economical efficiency of optical fibers, it is necessary to have a low price and to improve the productivity of optical fibers. In order to increase the coating speed (curing speed), it is desired that the coating speed (curing speed) be fast.

Because silicone has a low elastic modulus and glass transition temperature,
Optical fiber coated with this material has excellent transmission characteristics, but
It has the disadvantage of being more expensive than general plastic materials. For this reason, inexpensive coating materials that are cured by ultraviolet rays have been proposed, such as engineered oxyacrylate compositions, urethane acrylate compositions, and polybutadiene acrylate compositions. Taking a urethane acrylate composition as an example, this type of composition has a relatively high molecular weight, high viscosity polyfunctional urethane acrylate and a monoacrylate diluent as its main components. However, compositions in which monoacrylates with relatively long side chains are added to lower the elastic modulus generally have a slow curing speed, resulting in a slow coating speed for optical fibers. Therefore, a composition containing a monoacrylate with a short side chain has a high modulus of elasticity, which has the disadvantage that the transmission loss of an optical fiber coated with the composition increases.

[Purpose of the invention]

The present invention has been made to solve these drawbacks, and its purpose is to provide a coating material that has a low modulus of elasticity and a high curing speed.

[Structure of the invention]

That is, to summarize the present invention, the present invention is an invention of an optical fiber coating material, which comprises a polyfunctional acrylate or a polyfunctional methacrylate having a molecular weight of 500 or more, and the following general formula I: (where m and n is a positive integer).

The optical fiber coating material of the present invention may further contain a photopolymerization initiator, a polyfunctional acrylate, a polyfunctional methacrylate, a monofunctional acrylate, a monofunctional methacrylate, a silane coupling agent, an ultraviolet absorber, an oxidizing agent, etc., as necessary. Various additives such as inhibitors and fillers are added.

Polyfunctional acrylic with a molecular weight of 500 or more in the present invention
Typical examples of methacrylates include urethane acrylate, epoxy acrylate, 1,4-polybutadiene acrylate, polyester acrylate, and methacrylates corresponding to these. Among these, particularly preferred are urethane acrylate, 1
．． They are 4-polybutadiene acrylate and 1.4-polybutadiene methacrylate. Note that if the molecular weight is less than 590, the crosslinking density is high and the elastic modulus is large, so it cannot be applied. These polyfunctional acrylates or methacrylates in the present invention have urethane bonds or 1,4
- having a butadiene bond and having multiple acrylic or methacrylic groups in the molecule, a method for producing the same,
The structural formula etc. are not particularly limited.

The monoacrylate represented by the general formula I is an essential component of the present invention. The present inventors investigated various monoacrylates with relatively long side chains and fast curing speeds, and found that the compound represented by the general formula (2) was superior. The present invention was based on the discovery that a composition containing the compound represented by the formula has a low elastic modulus and a fast curing speed, so it is possible to coat optical fibers at high speed, and optical fibers coated with this composition exhibit excellent transmission characteristics. reached.

Although the photopolymerization initiator used in the present invention is not particularly limited, for example, the following compounds are used. Benzophenone, acetophenone, benzoin, benzoin isobutyl ether, benzoin isopropyl ether, benzoin ethyl ether, 4,4'-bisdimethylaminobenzophenone, benzyl dimethyl ketal,
2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,2'-diisopropylthioxanthone, 1
-Human roxycyclohexyl phenyl ketone.

Further, the polyfunctional acrylate or methacrylate that can be used in the present invention is not particularly limited, but examples include the following. 1.6-hexanediol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate,
Neopentyl glycol diacrylate, 1.3-butylene glycol diacrylate, 2.2'-bis(4-
Acryloxyglopoxyphenyl)propane, 2.2'
- His(4-acryloxyjethoxyphenyl)propane, tetramethylolmethane triacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, acrylate adducts of various diglycidyl ethers and their corresponding methacrylates.

The monofunctional acrylate or methacrylate other than the monoacrylate represented by the general formula I used in the present invention is not particularly limited, and examples thereof include the following. tetrahydrofurfuryl acrylate,
2-hydroxy-3-phenyloxyglobyl acrylate, butoxyethyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, hexyldiglycol acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, Examples include dicyclopentadiene acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, and the corresponding methacrylates.

〔Example〕

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 1.4-polybutadiene acrylate having acrylic groups at both ends (molecular weight: approximately 3.000, viscosity: 40.0
00 cplil/60 C), 50 parts by weight of structural acrylate and 3 parts by weight of benzyl dimethyl ketal as a photopolymerization initiator was obtained. The elastic modulus of the coating material is 2°Kg/crn2, and the ultraviolet irradiation energy required for curing is 2.7 J/crn2.
It was crn2.

Next, the coating material was applied to the spun optical fiber at a speed of 50 m/min, and then! It was cured by irradiating ultraviolet rays with an L2KW high-pressure mercury lamp. In the obtained optical fiber, no increase in transmission loss due to coating was observed, and no increase in transmission loss was observed up to -40°C.

Example 2 1,4-polybutadiene acrylate having 3 acrylic groups per molecule (molecular weight: approximately 2,000, viscosity: 1
A coating material was obtained consisting of 55 parts by weight of acrylate, 45 parts by weight of acrylate, and 3 parts by weight of benzyl dimethyl ketal. The modulus of elasticity of the coating material is 2
5 Kg/cm2, and the ultraviolet irradiation energy necessary for curing was 2.2 J/crn2.

Next, the coating material was applied to an optical fiber spun at a speed of 70 m/min, and then cured by irradiating ultraviolet rays from a 3.2 KW high-pressure mercury lamp.

In the obtained optical fiber, no increase in transmission loss was observed due to the coating, and no increase in transmission loss was observed up to -40°C.

Example 3 40 parts by weight of 1,4-polybutadiene acrylate used in Example 1, 10 parts by weight of 1,4-polybutadiene acrylate used in Example 2, 50 parts by weight of acrylate used in Example 2 , and 3 parts by weight of benzyl dimethyl ketal. The elastic modulus of the coating material is 22 h
/cm2, and the ultraviolet irradiation energy required for curing is 2
．． It was 5J/crn2.

Next, the coating material was applied to an optical fiber spun at a speed of 60 m/min, and then cured by irradiation with ultraviolet rays using a 5.2 KH high-pressure mercury lamp. In the obtained optical fiber, no increase in transmission loss due to coating was observed, and no increase in transmission loss was observed up to -40°C.

Example 4 1,4-polybutadiene methacrylate having methacrylic groups at both ends (molecular weight: approximately 3.000).

Viscosity: 40.000 cps / 60 °C) 50
40 parts by weight of the acrylate used in Example I, 10 parts by weight of polyethylene glycol monoacrylate
A coating material was obtained consisting of the f B-part and 6 parts by weight of benzyl dimethyl ketal. The modulus of elasticity of the coating material is 22 K4
/6n", the ultraviolet irradiation energy required for curing is 3
．． It was 2 J/cm2.

Next, apply the coating material to 30. The coating was applied to an optical fiber that was spun at a speed of 1,000 yen per minute, and then cured by irradiating ultraviolet rays with a 3.2 KW high-pressure mercury lamp. In the obtained optical fiber, no increase in transmission loss due to coating was observed, and no increase in transmission loss was observed up to -40°C.

Example 5 Urethane acrylate having 92 acrylic groups per molecule (molecular weight: approximately 1.800, viscosity 12,000 CI)
)E+/2 s°C) 60 parts by weight, 40 parts by weight of the acrylate used in Example 1, and 3 parts by weight of penzyl dimethyl ketal. The elastic modulus of the coating material is 28 kg/m2, and the ultraviolet irradiation energy required for curing is 3 J/c! It was n2.

Next, the coating material was applied to an optical fiber spun at a speed of 40 n1/min, and then cured by irradiation with ultraviolet rays using a 3.2 KW high-pressure mercury lamp.

In the obtained optical fiber, no increase in transmission loss due to coating was observed, and no change in transmission loss was observed up to -40°C.

Example 6 30 parts by weight of 1,4-polybutene acrylate (molecular weight: about 2, OOO, viscosity: 12,000 ape/2s°C) having 2.5 acrylic groups per molecule in Example 5 A coating material was prepared consisting of 30 parts by weight of the urethane acrylate used, 40 parts by weight of the acrylate used in Example 1, and 3 parts by weight of benzyl dimethyl ketal. The elastic modulus of the obtained cutting material was 27K17cm2,
The ultraviolet irradiation energy required for curing was 2.6 J/cm2.

Next, the coloring material was applied to an optical fiber spun at a speed of 50 m/min, and then cured by irradiation with ultraviolet rays using a 5.2 KH high-pressure mercury lamp. In the obtained optical fiber, no increase in transmission loss due to coating was observed, and no increase in transmission loss was observed up to -40°C.

〔Effect of the invention〕

As explained above, since the coating material of the present invention has a low elastic modulus and a fast curing speed, it is possible to improve the coating speed of an optical fiber. It has a particularly remarkable effect of having excellent transmission characteristics.

Patent applicant: Nippon Telegraph and Telephone Corporation Agent Hiroshi Nakamoto Same as Akira Ii

Claims (1)

[Claims] 1゜ A polyfunctional acrylate or a polyfunctional methacrylate with a molecular weight of 500 or more, and an acrylate represented by the following general formula I: (wherein m and n mean positive integers) An optical fiber coating material characterized by containing. 2. The polyfunctional acrylate or polyfunctional methacrylate is at least one selected from the group consisting of polybutadiene acrylate, polybutadiene methacrylate, and urethane acrylate. k optical fiber coating material.