JPS62148346A - Material for coating optical glass fiber - Google Patents

Abstract

PURPOSE:To obtain the titled coating material having a low tensile elastic modulus by composing the material of a liq. diene polymer having a polymerizable unsaturated bond, a specified polymer, a compd. contg. a (meth) acryloyl group, and a photopolymerization initiator. CONSTITUTION:A liq. diene polymer (e.g., polybutadiene) contg. an active hydrogen group is allowed to react with an unsaturated carboxylic acid (derivative) such as (meth)acrylic acid and maleic acid(anhydride) to obtain a liq. diene polymer (A) contg. 1.3-4 units of a polymerizable unsaturated bond in one molecule and having 300-6,000 number average mol.wt. Then 0.01-20wt% of photopolymerization initiator (D) (e.g., benzophenone) is incorporated into the composition consisting of 100pts.wt. of component (A), 2-180pts.wt. of component (B) obtained by introducing a cinnamic acid group into a polymer having an ether coupling, an ester coupling or a diene bond, and active hydrogen in the molecular skeleton and having 300-8,000 number average mol.wt., and 5-300pts.wt. of compd. (C) contg. a (meth)acryloyl group [e.g., phenoxy(meth) acrylate].

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a material for coating optical glass fibers for light transmission.

[Conventional technology]

Optical glass fibers that are generally used as optical transmission media are extremely fragile and easily damaged, and contamination increases optical transmission loss.

For this reason, the surface of an optical fiber has conventionally been coated with a resin immediately after spinning the optical fiber from a glass base material. For this reason, thermosetting epoxy resins and urethane resins have been used, but these have long curing times, poor adhesion to glass fibers, and lack flexibility, especially at low temperatures. This increased transmission loss due to microbending, making it unreliable for long-term use.

For this reason, silicone resins, which have low tensile modulus, low glass transition temperature, and excellent transmission loss, are now exclusively used, but because they are thermosetting resins, they have poor curing properties and slow production speeds. It has drawbacks such as high price.

In recent years, various coating materials have been proposed as substitutes for silicone resin in order to reduce the cost of optical fibers. For example, materials such as UV-curable epoxy acrylate and urethane acrylate have been proposed, but these materials have a relatively high glass transition temperature compared to silicone resin, so their tensile modulus at low temperatures is high; Optical fibers coated with materials have the disadvantage of high transmission loss due to microbending and the like.

Recently, coating materials of thermosetting 1,4-polybutadienes having functional groups or 1,4-polybutadienes having introduced polymerizable unsaturated bonds have been proposed (Japanese Patent Application Laid-Open No. 7103-1983). Since this resin has a lower glass transition temperature than epoxy resins and urethane resins, optical fibers coated with this resin have excellent transmission characteristics even at low temperatures.

However, coating materials using 1,4-polybutadienes have high viscosity, poor high-speed workability, poor adhesion to quartz fibers, and furthermore, when exposed to high temperatures, they become reticulated and have poor tensile elasticity. rate tends to increase. Therefore, optical fibers coated with these materials have the disadvantage that transmission loss increases over time.

As a method to overcome these drawbacks, methods have been proposed to improve workability by using a plasticizer to lower the viscosity or a reactive diluent (Japanese Patent Laid-Open No. 59-227915). However, there are disadvantages in that the strength of the obtained cured film is significantly reduced, the flexibility and low-temperature/high-temperature properties, etc. are reduced, and the curability such as ultraviolet curing speed is also reduced. On the other hand, as a method to eliminate the increase in tensile modulus over time, a method of adding an antioxidant has been proposed (Japanese Patent Laid-Open No. 59-208505), but this method has not always been sufficiently effective.

For this reason, coating materials using 1,4-polybutadienes have the problem of deterioration in strength and transmission loss during high-tension Bruf tests of coated optical fibers.

[Problem that the invention seeks to solve]

Coating materials mainly composed of polybutadienes have a lower glass transition temperature than coating materials based on epoxy resins and urethane resins, so optical fibers coated with this material have stable transmission characteristics even at low temperatures. Because of this, active research is being carried out on the use of this material in optical fiber coating materials.

However, in order to have the functions of both a secondary coating material and a buffer layer, the tensile modulus of the coating material containing polybutadiene as a main component is high, and it is required to find a way to lower this modulus.

Currently, the coating structure of optical fibers is (a) a two-layer structure consisting of a primary coating and a buffer layer for tight structure strands, but (b)
The loose structure wire has a two-layer structure with a primary coating and a hollow space. In order to simplify the coating structure and thereby reduce the cost of the optical fiber, it is desirable to integrate the primary coating and the buffer layer in tight structure strands.

For this purpose, it is strongly required that the tensile elasticity of conventional coating materials containing polybutadiene as a main component be 1.0 or less, preferably on the order of 0.1.

Furthermore, the tensile modulus of the coating material containing polybutadiene as a main component increases significantly when exposed to a thermal environment, resulting in worsening of optical transmission loss.

The object of the present invention is to eliminate these drawbacks and provide a coating material that can perform both the functions of the secondary coating and the two-layer structure of the buffer layer with only one layer coating. As a result, the coating operation for the optical fiber strands is performed only once, thereby reducing the manufacturing cost of optical glass fibers.

[Means for solving problems]

The present invention uses the following components: (A) having a polymerizable unsaturated bond and having a number average molecular weight of 300 to
6.000 liquid diene polymer (hereinafter referred to as (A) or (A)
), (B) having a bond selected from the group consisting of an ether bond, an ester bond, and a diene bond, and having a cinnamic acid group in the molecule, a number average molecular weight of 300 to s, o o o. Polymer (hereinafter referred to as (B) or (B) polymer), (C)
A compound having an acryloyl group or a methacryloyl group (hereinafter referred to as (C) or (C) compound), and (D) a photopolymerization initiator containing the above components (A), (B), (C) and (D). This is a coating material for optical glass fiber characterized by the following characteristics.

Next, the present invention will be explained in detail.

The polymer (A) used in the present invention is a polymer having a number average molecular weight of 3 and containing 1.3 to 4 polymerizable unsaturated bonds in one molecule.
It is a liquid diene polymer with a molecular weight of 00 to 6,000. These liquid diene polymers include diene polymers having 4 to 14 carbon atoms, copolymers thereof, and copolymers of these diene monomers and α-olefinic addition polymerizable monomers having 2 to 24 carbon atoms. There is. Specifically, butadiene homopolymer, isoprene homopolymer, chloroprene homopolymer, butadiene-styrene copolymer, butadiene-
Examples include isoprene copolymer, butadiene-acrylonitrile copolymer, pucdiene-2-ethylhexyl acrylate copolymer, and butadiene-n-octadecyl acrylate copolymer.

Furthermore, various types of polymerizable unsaturated bonds can be used here. For example, acryloyl group,
Examples include methacryloyl group, acrylamide allyl group, vinyl ether group, vinylthioether group, vinylamino group, and among these, acryloyl group, methacryloyl group, acrylamide, and methacrylamide group are preferred from the viewpoint of curability.

(A) Various methods can be employed to produce the polymer. For example, (i) reacting an active hydrogen group-containing liquid diene polymer with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or maleic acid or a derivative thereof (anhydride, etc.), (ii) reacting an active hydrogen group-containing liquid diene (iii) reacting the active hydrogen group-containing liquid diene polymer with isocyanate-hydroxyalkyl acrylate or isocyanate-hydroxyalkyl methacrylate; (1) isocyanate; Reacting a group-containing liquid diene polymer with hydroxyalkyl acrylate or hydroxyalkyl methacrylate, (v) reacting an epoxy group-containing liquid diene polymer with acrylic acid, methacrylic acid, etc., (vi) active hydrogen group. Containing liquid diene polymer and isocyanato alkyl acrylate, isocyanato alkyl methacrylate, vinyl isocyanate,
It can be produced by a method of reacting propenyl isocyanate or the like. The active hydrogen group-containing liquid diene polymer used here is a liquid diene polymer having an active hydrogen group such as a hydroxyl group, an amino group, an imino group, a carboxyl group, or a mercapto group at the molecular end.

If the number average molecular weight of the polymer (A) is less than 300, the coating material obtained by photocuring will be hard and brittle, making it unsuitable as a coating material for optical glass fibers. On the other hand, if the number average molecular weight exceeds 6.000, the viscosity of the coating material will be high, making it extremely difficult to coat it onto optical glass fibers.

Furthermore, if the number of polymerizable unsaturated bonds in the polymer (A) is less than 1.3 per molecule, the chain length extension of the molecular weight of the photocurable coating material will be low, resulting in a lack of toughness.

On the other hand, if the number exceeds 4, the degree of crosslinking will be too high and flexibility will be lacking.

The polymer (B) used in the present invention is obtained by introducing a cinnamic acid group into each polymer which has an ether bond, an ester bond, or a diene bond in its molecular skeleton and also has active hydrogen. Having an ether bond in the molecular skeleton referred to here,
In addition, examples of the polymer having active hydrogen include ordinary polyalkylene ether polyols obtained by reacting water or polyhydric alcohol with at least one selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide, and tetrahydrofuran polymers. Polytetramethylene ether glycols obtained by ring polymerization.

Examples of polyhydric alcohols include ethylene glycol, propylene glycol, pentane glycol, hexane glycol, hexane butylene glycol, decamethylene glycol, glycerin, diethylene glycol,
Dipropylene glycol, diglycerin, trimethylolpropane, pentaerythritol, 1,2,6-hexandriol, sucrose, sorbitol, thioglycol, triethanolamine, and the like are used.

In addition, the polymers having an ester bond and containing active hydrogen mentioned here include condensates of polycarboxylic acids and polyhydric alcohols, condensates of hydroxycarboxylic acids and polyhydric alcohols, and lactone and lancton polymers. Things, etc.

Examples of the polycarboxylic acids include benzenetricarboxylic acid, adipic acid, succinic acid, superric acid, cepatic acid, oxalic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, fucuric acid, terephthalic acid, and isophthalic acid. , thiodipropionic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, dimer acid, or any similar carboxylic acid.

Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3
-butanediol, ■, 5-bentanediol, 1,6
-hexanediol, bis(hydroxymethylchloride), diethylene glycol, dipropylene glycol, 1,2,6-hexandriol, trimethylolpropane, pentaerythritol, sorbitol,
Glycerin or any similar polyhydric alcohol can be used.

The lactone polymer is obtained by ring-opening polymerization of lactones such as ε-caprolactone, δ-valerolactone, and ρ-enantholactone using glycol or the like as an initiator.

Moreover, as the polymer having a diene bond in the molecular skeleton and containing active hydrogen, the polymer (A) can be used.

Next, the above-mentioned (B) polymer can be produced by various methods.

For example, (i) reacting cinnamic acid or cinnamic acid chloride with an active hydrogen-containing polymer having ether bonds, ester bonds, or diene bonds in the molecular skeleton; (ii) reacting cinnamic acid or cinnamic acid chloride with an ether bond, ester bond, or diene bond in the molecular skeleton; (iii
) reacting glycidyl cinnamate, etc. with an active hydrogen-containing polymer having an ether bond, an ester bond, and a diene bond in its molecular skeleton; (iv) reacting an epoxy group-containing polymer with an ether bond, an ester bond, and a diene bond in its molecular skeleton; (v) A method of reacting 2-hydroxydiethyl cinnamate etc. with a pre-charged combination of an active hydrogen-containing polymer and an isocyanate compound having an ether bond, ester bond or diene bond in the molecular skeleton. It can be manufactured by etc. The active hydrogen-containing polymer having an ether bond, ester bond, or diene bond in the molecular skeleton used here includes a polymer having an active hydrogen group such as a hydroxyl group, amine group, imino group, carboxyl group, or mercapto group at the molecular end. Point.

The number average molecular weight of the polymer (B) obtained as described above was 300 to 8. It's OOO. Number average molecular weight is 300
If it is less than 1.0, the tensile modulus of the coating material obtained by photocuring will be as high as 1.0 or more, resulting in a decrease in the ability to buffer against external pressure, which is not preferable.

Conversely, if the number average molecular weight is 8. If OOO is exceeded, tackiness remains on the surface of the photocurable coating material and the secondary coating material (nylon,
(liquid crystalline polyester, etc.).

Next, the compound (C) used in the present invention specifically refers to monofunctional compounds such as phenoxy (meth)acrylate, 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylate. ) dodecyl acrylate,
Esters of (meth)acrylic acid with 2-butoxyshetanol or 2-ethoxyethanol, tetrahydrofurfuryl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, butoxyethyl (meth)acrylate, lauryl ( meth)acrylate, stearyl(meth)acrylate, benzyl(
meth)acrylate, hexyldiglycol(meth)acrylate, 2-hydroxyethyl(meth)acrylate, cyclohexyl acrylate, phenoxyethyl(
meth)acrylate, polyethylene glycol mono
(meth)acrylates, polypropylene glycol monoacrylates, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate These monofunctional compounds may be used alone or in combination of two or more.

In addition, as polyfunctional compounds, 1,4-butanediol di(meth)acrylate, 1,6-hexanethiol di(meth)acrylate, pentaerythritol tri
(meth)acrylate, trimethylolpropane tri
(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate,
Examples include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and neopentyl hydroxypivalate glycol di(meth)acrylate.

In addition, if necessary, the above (C) compound and other vinyl groups,
It is also possible to use a mixture of a monomer having an unsaturated bond such as an allyl group and a monomer that inhibits hydrogen bond formation in urethane such as N-vinylpyrrolidone.

The blending ratio of the above-mentioned components is (A) 100 parts by weight of polymer, (B) 2 to 180 parts by weight of polymer, (C) 5 parts by weight of compound.
It is used within the range of 300 parts by weight.

If the amount of the (B) polymer is less than 2 parts by weight, the coating material obtained by photocuring will have a high tensile modulus and will lack buffering ability against external pressure. On the other hand, if the amount exceeds 180 parts by weight, tackiness remains on the surface of the photocured coating material, which impedes the coating operation of the secondary coating (nylon, liquid crystal polyester, etc.).

Next, if the amount of the compound (C) used is less than 5 parts by weight, the viscosity of the coating material will be high, making it impossible to uniformly coat the coating material to a desired thickness. On the other hand, if the amount exceeds 300 parts by weight, the viscosity of the coating material will be too low and it will not be possible to coat it thickly, and the photocured coating material will lack flexibility and toughness.

The photopolymerization initiator (CD) used in the present invention is not particularly limited, but includes, for example, the following compounds. Benzophenone, acetophenone, benzoin, benzoin isobutyether, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin acetate, 2-chlorobenzophenone, 4-methoxybenzophenone, 4,4'-bisdimethylaminobenz Phenone, 4,4'-dimethylhensiphenone, henzyldimethylkecour, 2-chlorothioxanthone, 4-bromohensiphenone, 2,4-dimethylthioxanthone, 2,2'-diisopropylthioxanthone, 1-hydroxycyclo hexylphenyl ketone, 2.2',
4.4'-tetrachlorobenzophenone, 2-chloro-
4'-Methylhensiphenone, 3-methylbenzophenone, 4-t-butylbenzophenone, benzylic acid, diacetyl, 2,2-jethoxyacetophenone, 9,10
-phenanthrenequinone, 2-methylanthraquinone,
2-ethylanthraquinone, 2-t-butylanthraquinone, diphenyldisulfisode, dithiocarbamate, p-nitrodiphenyl, p-nitroaniline, 2,4
-Dinitroaniline, p-nitroacetanilide, picramide 1-methoxy 42I-lonaphthalene, 2-chloro-4-nitroaniline anthraquinone, 1,2-benzanthraquinone, 3-methyl-1-diaza-1,9 −
Benzanthrone, 1,9-benzanthrone, pp
'-tetramethyldiaminohendphenone 2, N-methyl-2-hendiylnaphthothiapurine, 5-nitrofluorene, 5-nitroacenaphthene, N-acetyl-4-
Nitro-1-naphthylamine, 1,2-benzanthraquinone, 1,9-benzanthrone, 2.4.6-1-
These include liphenylvirylium salts.

The amount of the photopolymerization initiator (D) used is the same as the amount of the photoinitiator (A) described above.
), 0.01 to 20 relative to the total amount of (B) and (C)
It is a heavy weight%. , these photopolymerization initiators may be used alone or in combination
Used in combination with more than one species.

It is also possible to use these photopolymerization initiators together with a small amount of sensitizing aid such as amines.

Such amines include primary amines such as butylamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and monoethanolamine;
diethylamine, dimethylaniline, dimethyl-para-
Examples include secondary or tertiary amines such as toluidine, pyridine, N,N'-dimethylcyclohexylamine, jetanolamine, and triethanolamine.

Further, in order to improve the thermal stability of the resin according to the present invention, a known thermal polymerization inhibitor or the like may be added.

Examples of the thermal polymerization inhibitor include di-t-butyl-p-cresol, hydroquinone monomethyl ether, pyrogallol, quinone, hydroquinone, t-butylcatechol,
Examples include hydroquinone monobenzyl ether, methylhydroquinone, amylquinone, phenol, hydroquinone monopropyl ether, phenothiazine, and nitrobenzene.

The coating material for optical glass fiber of the present invention has the above-mentioned (A>
, (B), (C) and (D), if necessary, plasticizers such as phthalate esters and phosphate esters, inorganic fillers such as silica, clay, kaolin, etc. Auxiliary components such as a repellent, a thixotrobinox-imparting agent, a coupling agent, a coloring agent, and a diluent may be added as desired.

The amounts of these auxiliary ingredients added are (A), (B) and (
The amount ranges from 0 to 200 parts by weight based on 100 parts by weight of the total amount of C).

The coating material for optical glass fiber of the present invention is the above-mentioned (A
), (B), (C), and (D) and auxiliary components added as necessary, and to actually coat an optical glass fiber with the photopolymerization initiators, conventionally known methods are used. Generally, the coating material of the present invention may be applied to the surface of an optical glass fiber following the spinning process, and then polymerized and cured by irradiation with ultraviolet electron beams or the like.

Although the coating material according to the present invention is suitable for coating optical glass fibers, it is also suitable for coating various coating agents, paints,
It can be used in adhesives, inks, impregnation materials, electrical insulation materials, etc. Specifically, it is used in protective coating materials for printed circuit boards, plating and solder resist materials, insulating materials for motors and electric coils, adhesives for liquid crystal panels, adhesives and sealants for optical desks, and caulking and sealing agents.

[Effect]

A coating material whose main component is a liquid diene polymer having a polymerizable unsaturated bond in its molecule, which has a bond selected from the group consisting of an ether bond, an ester bond, and a diene bond in its molecular skeleton, In addition, the photocured coating material obtained by blending a polymer having a cinnamic acid group in the molecule as an essential component has an extremely low tensile modulus, has no surface tackiness, and has a strong optical properties with a high modulus of elasticity. A coating material for glass fibers can be provided. This is because there is a difference in the curing speed and mechanism between a photosensitive double bond such as an acryloyl group (methacryloyl group) and a cinnamic acid group against ultraviolet rays (electron beam).

As a result of this, the coating material forms an interpenetrating network. It is believed that this made it possible to create a photocurable coating material that had a significantly low tensile modulus, suppressed an increase in the tensile modulus under a heated atmosphere, and was highly elastic and tough.

The optical glass fiber according to the present invention has a strong buffering effect against external pressure at room temperature, and therefore does not cause optical transmission loss due to microbending due to external pressure.

Moreover, it maintains a low rg due to the diene bond chains in the molecular skeleton and suppresses the increase in elastic modulus at high temperatures, so it maintains excellent optical transmission loss even when exposed to low-temperature and high-temperature cycle environments. I can do it.

〔Example〕

Next, the present invention will be specifically explained with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited only to these examples. Note that parts and percentages in the examples are parts by weight and percentages by weight.

Synthesis Example A-1 (A) Synthesis of polymer: 132 parts of 2.4-) lylene diisocyanate and 1.0 part of dibutyltin dilaurate in a reaction vessel equipped with a stirrer, a reflux condenser and an air blowing tube. and 3.0 parts p.
- Methoxyphenol was charged and to this was added 93 parts of hydroxyethyl acrylate over a period of 2 hours in a stream of dry air. The temperature rose due to the exothermic reaction, but once it reached about 70°C, this temperature was maintained and stirring was continued for an additional hour.

Next, 1000 parts of hydroxyl group-containing liquid polybutadiene (Idemitsu Kosan poly bd R-45HT, hydroxyl group content 0.8 meq/g, number average molecular weight 2.800, trans L 460%, cis 1,420%, 1.2 vinyl
20%) was added over 3 hours. The temperature rises due to the exothermic reaction, but when it reaches about 70℃, maintain it at this temperature,
Stirring was continued for further 2 hours to obtain (A) polymer (A)-1.

Synthesis Examples A-2, 3, and 4 As shown in Table 1, in place of 2,4-tolylene diisocyanate in Synthesis Example A-1, bis(4-isocyanatocyclohexyl)methane, Using 1,2-polybutadiene instead of liquid polybutadiene and selecting the amounts of other raw materials, the reaction was carried out according to Synthesis Example A-1 to obtain (A) a polymer (A)-2,3 ,4 was obtained.

Synthesis Example A-5 340 parts of carboxyl group-containing liquid polybutadiene (
Idemitsu Kosan Hycar CTBN 1300×13, number average molecular weight 3,400, acid value 33), 186 parts of ethylene glycol, 550 parts of toluene, and 0.4 parts of para-toluenesulfonic acid were charged and heated under reflux at about 110°C. A dehydration reaction was carried out. A theoretical amount of water was collected by dehydration reaction for 22 hours. This was neutralized with sodium carbonate, washed with water, distilled off toluene under reduced pressure, dehydrated and dried, and produced a hydroxyl group-containing polybutadiene.
Acrylonitrile copolymer glycol (hydroxyl value 31)
I got it.

Next, in the same reaction vessel as in Synthesis Example A-1, 43 parts of bis(4-
Isocyanatocyclohexyl)methane, 0.3 parts of dibutyltin dilaurate and 0.9 parts of p-methoxyphenol were charged, and to this was added 19 parts of hydroxyethyl acrylate over a period of 2 hours in a stream of dry air.

If the temperature rises due to an exothermic reaction and reaches about 70°C,
This temperature was maintained and stirring continued for an additional hour.

Add to this 300 parts of the synthesized hydroxyl group-containing polybutadiene.
Acrylonitrile copolymer glycol (hydroxyl value 31)
was added over a period of 3 hours. The temperature rises due to the exothermic reaction, but when it reaches about 70°C, maintain it at this temperature and heat it for another 1
Stirring was continued for hours to obtain (A) Polymer (A)-5.

Synthesis Example B-1 (B) Synthesis of polymer:
0 parts of polypropylene ether glycol (number average molecular weight: 1002, hydroxyl value: 112) and 100 parts of pyridine were charged, and 166 parts of cinnamic acid chloride was added thereto over 3 hours.

If the temperature rises due to an exothermic reaction and reaches about 60°C,
This temperature was maintained and stirring continued for an additional 2 hours.

Next, after being allowed to cool to room temperature, it was washed with a 10% aqueous solution of sodium carbonate to remove unreacted cinnamic acid chloride, and then thoroughly washed with water. This was dehydrated and dried under residual pressure (B
) polymer was synthesized.

[Sample (B)-1) Synthesis Examples B-2, 3, and 4 As shown in Table 2, the polypropylene glycol in Synthesis Example B-1 was varied, and the amounts of other raw materials added were varied. Polymer (B) was synthesized by reaction according to Example B-1. [Sample (B)-2°3 and 4].

Example 1 35 of (A) polymer (A)-1 obtained in Synthesis Example A-1
0 part contains 280 parts of phenoxyethyl acrylate as the compound (C) and 70 parts of N as the photopolymerization aid of (D).
-Vinylpyrrolidone t- was added and mixed well, and 70% of the (B) polymer (B)-1 obtained in Synthesis Example B-1 was added thereto.
21 parts of hensyl dimethyl ketal and 4 parts of p-
Nitroacetanilide (a photopolymerization initiator for cinnamic acid compound) was added and thoroughly mixed and dissolved again. This final composition is
After passing through a micron filter, it was used as an optical glass fiber coating material.

[Sample 1] Examples 2 to 8 According to Example 1, as shown in Table 3, the coating material of the present invention [
Samples 2 to 8] were prepared. For convenience, Example 1 is also listed in Table 3.

Comparative Examples 1 to 5 As comparative examples, coating materials (samples C-1 to C-5) were prepared according to Example 1 as shown in Table 4.

Table 2 Compensation itm Note (1) Number average molecular weight 1002, hydroxyl value 112° (
2) 〃6BB, 〃163゜(3) 〃,
976〃115 (manufactured by Dainippon Ink Industries: Bolilite 0O-X-240) (4) Number average molecule ffi 2
800, hydroxyl group content 0.80 meq/q, trans 1.4: 60%, cis 1.4: 20%, 1.2
Vinyl: 20% (Idemitsu Kosan (■: poly bd R
-45HT) Table 4 Report 16B) Test Example 1 Using the optical glass fiber coating materials of Examples 1 to 8 and Comparative Examples 1 to 5 obtained as described above, a sheet cured by ultraviolet rays was prepared, Its tensile strength and elastic modulus were measured. The method for preparing the cured product sheet and the method for measuring the tensile modulus will be described below.

The measurement results obtained are shown in Table 5.

<Test method> i) Curing of coating material and sheet production Examples 1 to 8
The optical glass fiber coating materials of Comparative Examples 1 to 5 are applied onto a tin test plate using a doctor blade to a thickness of 0.1 fin.

Next, photocuring was performed by irradiating for 10 seconds using an 80 W/am metal halide lamp and an ultraviolet curing device with a distance between lamps of 40 cm. A sheet for peeling test was prepared from this using the mercury amalgam method.

ii) Measurement of elastic modulus The test sheet obtained by the method in item i) was heated at 20°C 150%.
After leaving it in a constant temperature room at RH for 24 hours, JISK-711
The elastic modulus was measured according to 3.

For heat aging, the elastic modulus was measured after heating for 7 days in a heat aging tester at 80°C.

iii) Glass transition temperature Measured using an apparatus manufactured by Toyo Baldwin under the conditions of a frequency of 35 Hz, a heating rate of 2 °C/min, a dynamic displacement of ±0.025 fl, and a measurement temperature of -100 °C to +100 °C. Temperature was measured.

Table 5 Test Example 2 Examples 1-
Using each of the coating material samples 1 to 8 of 8, the outer diameter after coating was 4.
After coating to a thickness of 0.00 μm, ultraviolet rays were irradiated using a metal halide lamp of 80 W/cm to obtain a coated fiber.

In the obtained coated optical fiber, no change in transmission loss due to the coating was observed, and the change in transmission loss in the temperature range of -50°C to +60°C was ±0.05 dB/km or less.

〔Effect of the invention〕

As is clear from the above description, the present invention uses a coating material mainly composed of a liquid diene-based polymer having polymerizable unsaturated bonds in the molecule. The tensile modulus of elasticity after curing of the coating material for optical glass fibers is significantly reduced by blending as an essential component a polymer having a bond selected from the group consisting of: and a cinnamic acid group in the molecule. Furthermore, the glass transition points of the cured products are low at -60°C or lower, and therefore the tensile modulus at low temperatures is also low. Moreover, the increase in tensile modulus is also significantly reduced by exposure to high temperatures.

This allows the optical fiber to maintain its flexibility and flexibility even when used in low-temperature and high-temperature cycle environments, and its low tensile modulus provides excellent mitigation ability against lateral pressure and thermal shrinkage of the optical glass fiber. , an increase in optical transmission loss due to microbending and the like can be prevented.

Of course, the liquid resin coating material of the present invention has low viscosity and is suitable for high-speed workability, has good adhesion to quartz fibers, has extremely low water resistance and moisture permeability, is suitable as a material for coating optical glass fibers, and is wide. It can be effectively used in the field.

Applicant (430) Nippon Soda Co., Ltd. Agent Patent Attorney Haruyuki Ito ~ Yoshimi Yokotoba

Claims (2)

[Claims] (1) (A) Number average molecular weight 3 having a polymerizable unsaturated bond
(B) having a bond selected from the group consisting of an ether bond, an ester bond, and a diene bond, and having a cinnamate group in the molecule and a number average molecular weight of 300 to 6,000; 8,000 polymer, (C) a compound having an acryloyl group or a methacryloyl group, and (D) a photopolymerization initiator. An optical glass fiber coating material characterized by: (2) The blending ratio of components (A), (B), (C) and (D) is (A) 100 parts by weight, (B) 2 to 180 parts by weight, and (C) 5 to 300 parts by weight. , (D) in an amount of 0.01 to 20% by weight based on the total amount of (A), (B) and (C).