JPS616155A - Cladding material for optical glass fiber - Google Patents

Abstract

PURPOSE:To obtain the titled cladding material having superior flexibility and mechanical strength after curing by incorporating a modified polybutadiene mixture having a specified compsn., a liquid reactive diluent having polymerizable C=C double bond, and a polymerization initiator. CONSTITUTION:(A) 30-70wt% modified 1,2-polybutadiene prepd. by introducing at lest two (meth)acryloyl groups into hydrogenated 1,2-polybutadiene is mixed with (B) 70-30wt% modified 1,4-polybutadiene prepd. by introducing at least two (meth)acryloyl groups into hydrogen added 1,4-polybutadiene. The titled cladding material is obtd. by adding at least one polymerizable C=C double bond in one molecule as a reactive diluent (e.g., cyclohexyl acrylate) and a polymerization initiator (e.g. benzoin methyl ether) with said mixture (A).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] This invention relates to materials for coating optical glass fibers for light transmission.

[Prior art]

Optical glass fibers (hereinafter simply referred to as optical fibers) used as optical transmission media usually have a diameter of 20 mm.
Since it is less than 0 μm and the material is brittle, scratches are likely to occur on the surface during manufacturing, cable production, and storage, and these scratches become a source of stress concentration, making it easy to damage when external stress is applied. The disadvantage is that the optical fiber may break.

For this reason, it is extremely difficult to use optical fiber as it is as an optical transmission medium. Therefore, conventionally, attempts have been made to provide a plastic coating on the surface of an optical fiber, thereby maintaining the initial strength immediately after manufacturing the optical fiber and manufacturing an optical fiber that can withstand long-term use.

Conventionally, thermosetting resins such as silicone resins, epoxy resins, and urethane resins have been used as such resin coating materials, but they require a long time to cure and dry, resulting in poor productivity and insufficient curing. The adhesion to the optical fiber is insufficient and there is a tendency for long-term reliability to be lacking. In addition, ultraviolet curable resin coating materials have been used to improve this drawback, but they generally have poor flexibility and have the drawback of impairing transmission characteristics due to microhenting.

Therefore, as an alternative to the above-mentioned material, the inventors have already used modified 4-polybutadiene, in which at least two acryloyl groups or methacryloyl groups have been introduced into hydrogenated 1,4-polybutadiene, as the main material. (Japanese Patent Application No. 129407/1982)
This improved the curing properties, adhesion to the optical fiber, and flexibility of the coating, and particularly good results were obtained in maintaining flexibility when left at high temperatures for long periods of time.

Further, as a result of subsequent studies, the inventors discovered that modified 1,2-polybutadiene in which at least two acryloyl groups or methacryloyl groups were introduced into hydrogenated 1,2-polybutadiene instead of the modified 1,4-polybutadiene A patent application was filed in 1982 for a coating material based on
No. 6816).

Similar to the above, this coating material can be suitably used as a coating material for optical fibers, and particularly good results have been obtained in low-temperature properties in that flexibility can be maintained well at low temperatures, resulting in further improvement in transmission properties. We were able to achieve this goal.

However, the coating material obtained in the above-mentioned prior invention cannot be said to be sufficient in terms of the mechanical strength of the cured product (
A coating material for optical fibers with even higher reliability is desired.

[Purpose of the invention]

It is an object of the present invention to provide a coating material for optical fibers which is superior in cured product properties, particularly in flexibility and mechanical strength, as compared to the coating materials according to the prior invention.

[Summary of the invention]

As a result of intensive studies to achieve the above object, the inventors discovered that the main material is a mixture of modified 1,4-polybutadiene and modified]-2-polybutadiene according to the above-mentioned prior invention in a specific blending ratio. The present inventors discovered that when used as a coating material, a coating material with excellent flexibility and mechanical strength, which could not be achieved when used alone, can be obtained, and this invention was made based on the findings.

That is, the present invention provides: a) 30 to 70% by weight of modified 1,2-polybutadiene in which at least two 7-acryloyl groups or methacryloyl groups have been introduced into hydrogenated 1,2-polybutadiene; Modified l-4-polybutane into which acryloyl or methacryloyl groups have been introduced 1 fluff 0 to 30
B) a liquid compound having at least one polymerizable carbon-carbon double bond in one molecule that acts as a reactive diluent for component a, and C) a polymerization initiator. The present invention relates to an optical fiber coating material characterized by the following.

[Structure of the invention]

Modified 1,2-polybutadiene and modified 1,4-polybutadiene as component a used as an essential component in this invention each contain functional groups such as hydroxyl group, carboxyl group, isosyphte group, and epoxy group.
[Hydrogenated having at least two of the above functional groups in the molecule, particularly preferably at both ends of the molecule]-2-polybutadiene and hydrogenated 1,4-polybutadiene, this hydrogenated 1,2-polybutadiene and hydrogenated l・4～
A compound having one functional group and one acryloyl group or methacryloyl group in one molecule that can react with the functional group of polybutadiene in a ratio such that the functional group of the polybutadiene is approximately 1 equivalent to 1 equivalent of the functional group of this compound. It can be obtained by reacting with

The above reaction may also be carried out simultaneously by mixing hydrogenated 1,2-polybutadiene and hydrogenated 1,4-polybutadiene in a predetermined ratio.
- A mixture of polybutadiene and modified 1,4-polybutadiene can be obtained. In addition, when the above reactions to obtain modified 1,2-polybutadiene and modified 1,4-polybutadiene are carried out separately and the two are mixed at a predetermined ratio after the reaction, the above-mentioned compounds used in the above-mentioned reaction of each polybutadiene are of the same type. It may be different or different.

The above hydrogenated 1,2-polybutadiene and hydrogenated 1,4-polybutadiene can be obtained by hydrogenating 1,2-polybutadiene and 1,4-polybutadiene having the above-mentioned functional groups, or by further hydrogenating the hydrogenated 1,2-polybutadiene and 1,4-polybutadiene after this hydrogenation reaction. It can be obtained by reacting a polyfunctional compound, for example, by reacting a hydroxyl group-containing hydrogenated 1,2-polybutadiene or hydrogenated 1,4-polybutadiene with a diisocyanate compound or dicarboxylic acid.

This diisocyanate compound generally has a molecule of 1
170 to i, o o o are used, specifically tolylene diisocyanate, diphenylmethane diisonanate, naphthalene diisonanate, p-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, Examples include isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, 1.6-hexane diisocyanate, and the like.

Further, as the dicarboxylic acid, an aliphatic one having about 2 to 50 carbon atoms excluding the carboxyl group is used, and specific examples thereof include succinic acid, adipic acid, and dimer acid. Examples of aromatic acids include fucuric acid, isophthalic acid, and terephthalic acid.

The above-mentioned hydrogenation reaction can be carried out according to a general hydrogenation method using a porcelain catalyst or the like, and the hydrogenation rate is usually preferably 50% or more. If it is lower than this, it becomes difficult to maintain the flexibility of the coating under high temperature conditions.

As is clear from the above explanation, hydrogenated 1,2-polybutadiene and hydrogenated l
- 4-Polybutadiene naturally includes 1,2-polybutadiene and 1,4-polybutadiene in which the carbon-carbon double bond is not completely hydrogenated.

The molecular weight of the above-mentioned hydrogenated 1,2-polybutadiene and hydrogenated 1,4-polybutadiene is usually 500 to 5,000, preferably 500 to 5,000, preferably 500 to 3,000. 0
It is 00. The molecular weight is too large (if it becomes too large, the compatibility with component b will deteriorate, which is not preferable).

In addition, compounds having one functional group and one acryloyl or methacryloyl group in one molecule that can react with the functional W of the hydrogenated 1,2-polybutadiene and hydrogenated 1,4-polybutadiene include, for example, a hydroxyl group. Acrylic acid, methacrylic acid, halides such as their chlorides, or lower alkyl esters of alkyl groups having 3 or less carbon atoms such as methyl ester, etc., which have a functional group that can react with isocyanate groups, etc. -Hydroquine ethyl acrylate or methacrylate, hydroxyalkyl acrylate or methacrylate (hydroxyfurkyl group has 2 to 5 carbon atoms) such as 2-hydroxypropyl acrylate or methacrylate, or glycidyl acrylate or methacrylate having a functional group that can react with a carboxyl group. Epoxy group-containing acrylate or methacrylate, such as methacrylate, with a molecular weight of 100 to 1°00
(approximately 0).

The mixing ratio of modified 1,2-polybutadiene and modified 1,4-polybutadiene in the above component a is 30 to 7% of the total amount of modified 1,2-polybutadiene in both components.
0% by weight, preferably 40-60% by weight, modified 14-
Polybutanene is 70 to 30% by weight, preferably 60 to 30% by weight
The content shall be 40% by weight. If the mixing ratio is outside the above range, the cured film will have poor flexibility and mechanical strength, and is therefore unsuitable.

Component b, which is used as another essential component in this invention together with the above component a, is used as a reactive diluent for the above component a, that is, because the above component a is generally solid or highly viscous at room temperature, it is coated. It is used to adjust the viscosity of the material to improve coating workability and to adjust the elongation and hardness of the cured film.

As the above b component, a liquid compound having a molecular weight of 100 or more, preferably about 150 to 1.500 in terms of -C is used, and a compound having a molecular weight of 1/2 or less of the molecular weight of the a component is preferable. . Among these, liquid acrylic esters or methacrylic esters having at least one, preferably 1 to 3 polymerizable return element-carbon double bonds in one molecule are particularly preferred. Specific examples of these esters include cyclohexol acrylate or methacrylate, benzyl acrylate or methacrylate, carpitol acrylate or methacrylate, 2-ethylhexol acrylate or methacrylate,
-Hydroxyethyl acrylate or methacrylate, 2-hydroxypropyl acrylate or methacrylate, tetrahydrofurfuryl acrylate or methacrylate, ethylene glycol cyacrylate L-
- dimethacrylate or dimethacrylate, diethylene glycol diacrylate or dimethacrylate, triethylene glycol diacrylate toner or dimethacrylate μ
-1., tripropylene glycol diacrylate or dimethacrylate, polyethylene glycol diacrylate or dimethacrylate, polypropylene glycol diacrylate or dimethacrylate, butylene glycol diacrylate or dimethacrylate, neopentyl glycol diacrylate or dimethacrylate μ-1. , 1,6-hexane glycol diacrylate] or dimethacrylate, pentaerythritol diacrylate or dimethacrylate,
Examples include pentaerythritol triacrylate or trimethacrylate, trimethylolpropane triacrylate or trimethacrylate.

In addition, the above-mentioned components include allyl esters such as diallyl adipate, diallylphthale-1-, triallyl trimellitate, triallyl isocyanurate, styrene,
Vinyl compounds such as vinyl acetate and N-vinylpyrrolidone can also be used.

The amount of the above ingredients to be used is the total amount of ingredients b
The content of the components is usually 10 to 70% by weight, preferably 20 to 60% by weight.

Too little component b is not preferred because the viscosity of the coating material becomes too high and coating workability decreases.

Furthermore, if the amount of component b is too large, the flexibility and mechanical strength of the cured film will decrease, which is not preferable.

The coating material of this invention contains component a as described above.

It is obtained by incorporating a polymerization initiator as component C into component b.

Examples of the above-mentioned polymerization initiators include photopolymerization initiators and thermal polymerization initiators. When a photopolymerization initiator is used, the coating material can be easily and quickly cured with ultraviolet rays or electron beams. By using this and a photopolymerization initiator, the coating material can be cured by heating.

Examples of the photopolymerization initiator include hengeine methyl ether, hengeine ethyl ether, hengeine isopropyl ether, hengeine isobutyl ether, henzphenone, methylorthohenzoylbenzoate, henzyl, henzyl dimethyl ketal, 2-2- Jetoxyacetophenone, 1,1-dichloroacetophenone, 2-chlorodioxanthone, 2-methylthioxanthone, 2-
Examples include isopropylthioxane], anthracene, and those used in combination with small amounts of sensitizing aids such as amines.

In addition, as the thermal polymerization initiator, peresters such as tertiary-butyl peroctoate-1 and tertiary-butyl perbivalate, bis-(4-tert-butylcyclohexyl)-bar-
Percarbonate esters such as oxodicarboxyl peroxide, diacyl peroxides such as hensyl peroxide, dialkyl peroxides such as di-tert-butyl peroxide and diacyl peroxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, etc. hydroperoxide, and these and 2
Examples include peroxide-based polymerization initiators such as combinations with metal promoters such as cohal)-II salts of ethylhexanoic acid and naphthenic acid, and other azo compounds can also be used.

The amount of these polymerization initiators to be used is usually about 1 to 7 parts by weight based on 100 parts by weight of the above-mentioned total amount of components a and b. If this amount is too small, the curability cannot be satisfied. Further, even if the amount exceeds the predetermined amount, no further improvement in the curing speed can be expected, so it is best to keep the amount within the above-mentioned range for practical use.

The optical fiber coating material of the present invention comprises the above components a, b
The essential components are 1 min. Various additives such as organic silicon compounds, surfactants, etc. may also be blended. The combined amount of these additives is preferably 30% by weight or less of the total material. From the viewpoint of coating workability, the overall viscosity is usually 1,000 to 10.00 as measured by a Brookfield viscometer.
It is desirable that the temperature be adjusted within the range of 0 centivoices (cps)/25°C.

When applying this coating material to optical fibers, the above-mentioned material is coated on the surface of the optical fiber immediately after spinning by an appropriate means so that the thickness after curing is usually 10 to 200 μm, and then the type of polymerization initiator is applied. Depending on the situation, the material may be cured by heating or by irradiation with ultraviolet rays or electron beams.

In addition, by forming an outer layer on top of the coating layer thus formed, a tough coating such as an ultraviolet curable coating such as epoxy acrylate or urethane acrylate, or a thermoplastic resin coating such as polyethylene or nylon. , it is also possible to provide an optical fiber coating with good fiber strength.

〔Effect of the invention〕

The coating of this invention (material 4 is the acryloyl group or methacryloyl group contained in the modified 1,2-polybutadiene and modified 1,4-polybutadiene that are component a, or the polymerizable carbon-carbon double bond contained in this and component b) It has the property of being heat-curable, photo-curable, or electron beam-curable in the presence of a polymerization initiator, and its curing speed is faster than that of conventional thermosetting resins.
When the coating material of the present invention is used, the resiliency of the optical fiber is improved, and deterioration in adhesion due to insufficient curing is suppressed, so that the reliability of the optical fiber can be improved.

Moreover, the cured film formed from the coating material of this invention is
Compared to those using conventional thermosetting resins or those using conventional ultraviolet curable resins, it has excellent flexibility and mechanical strength, and this flexibility and mechanical strength make it even stronger. Not only can good results be obtained, but the increase in transmission losses caused by microhenting and the like can be suppressed, making it possible to manufacture highly reliable optical fibers.

That is, in the coating material of this invention, hydrogenation 1.
Since modified 1,2-polybutadiene and modified 1,4-polybutadiene derived from 2-polybutadiene and hydrogenated 1,4-polybutadiene are used in the above-mentioned specific mixing ratio, hydrogenation as already proposed by the inventors 3AR modified l from 1,4-polybutadiene
・Compared to the one using 4-polybutadiene alone as the soil material and the modification derived from hydrogenated 1,2-polybutadiene which was subsequently proposed by these inventors]・The one using 2-polybutadiene alone as the main material Good results were obtained in terms of the flexibility and mechanical strength of the cured film, and the transmission characteristics of the optical Noah 1C could be further improved.

〔Example〕

Examples of the present invention will be described in more detail below. In addition, in the following, parts shall mean parts by weight. Furthermore, in the following, the term average molecular weight refers to the number average molecular weight measured by the CPC method using boristine as a reference material, and the term viscosity refers to the viscosity measured by a Brookfield viscometer.

Example 1 Hydrogenated 1,2-polycitadiene having an average molecular weight of 1.000 and having hydroxyl groups at both ends of the molecule (hydrogenation rate 90%) was placed in a 1,000-meter four-bottle flask equipped with a stirrer and a thermometer. 464g of tolylene diisocyanate was added dropwise at 50 to 60°C for 30 minutes, then 5 parts of 2-hydroxyethyl acrylate was added and reacted for 5 hours to form a mixture with acryloyl groups at both ends of the molecule. Modified 1,2-polybutadiene was obtained.

In addition, 666 g of hydrogenated 1,4-polybutadiene (hydrogenation rate 90%) with an average molecular weight of II, 000 having hydroxyl groups at both ends of the molecule was charged into the same flask as above.
87g of tolylene diisocyanate at 50-60°C
The mixture was added dropwise over a period of 0 minutes, and 58 g of 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate) was added thereto, followed by reaction for 5 hours to obtain modified 1,4-polybutadiene having acryloyl groups at both ends of the molecule.

Next, the modified 12-bolybutadi obtained above, ene 2
5 parts of cyclohexyl acrylate and 4 parts of henzyl dimethyl ketal were blended with 5 parts of cyclohexyl acrylate and 25 parts of modified 1,4-polybutadiene to obtain a coating material for optical fiber of the present invention having a viscosity of 8°,000 cps (25°C). .

Example 2 The amount of modified 1,2-polybutadiene used was 30 parts, modified 1
An optical fiber coating material of the present invention having a viscosity of 7.500 cps (25° C.) was obtained in the same manner as in Example 1 except that the amount of 4-polybutadiene used was 20 parts.

Example 3 The amount of modified 1,2-polybutanene used was 20 parts, modified 1
・Same as Example 1 except that the amount of 4-polycitadiene used was 30 parts, and the viscosity was 8.700 cps (25'C
) was obtained as a coating material for optical fiber according to the present invention.

Comparative Example 1 50 parts of cyclohexyl acrylate and 4 parts of henzyl dimethyl ketal were blended with 50 parts of the modified 1,2-polybuterine obtained in Example 1 to give a viscosity of 7,000 cps (
A coating material for optical fiber was obtained for comparison at a temperature of 25°C.

Comparative Example 2 1.50 parts of cyclohexyl acrylate and 4 parts of henzyl dimethyl ketal were blended with 50 parts of modified 1,4-polybutadiene obtained in Example 1, and the viscosity was 9.300 cps (
A coating material for optical fiber was obtained for comparison (25°C).

Comparative Example 3 The amount of modified 1,2-polybutadiene used was 10 parts, modified 1
・Same as Example 1 except that the amount of 4-polycitadiene used was 40 parts, and the viscosity was 8.700 cps (25'cps).
) Coating materials for optical fibers were obtained for comparison.

Comparative Example 4 The amount of modified 1,2-polybutadiene used was 40 parts, modified 1
- Viscosity s, oo in the same manner as in Example 1 except that the amount of 4-polybutadiene used was 10 parts.

A coating material for optical fiber was obtained for comparison of cps (25° C.).

Example 4 50 parts of cyclohexyl methacrylate and 4 parts of henzyl dimethyl ketal were blended with 25 parts of modified 1-2-polybutadiene and 21 parts of modified 14-polybutadiene obtained in Example 1, and the resulting mixture had a viscosity of 7.700 cps. An optical fiber coating material of the present invention was obtained at (25°C).

Comparative Example 5 50 parts of cyclohexyl methacrylate and 4 parts of henzyl dimethyl ketal were blended with 50 parts of modified 1,2-polybutadiene obtained in Example 1, and the viscosity was 6.600 cps.
(25°C) A coating material for optical fiber was obtained for comparison.

Comparative Example 6 1-50 parts of cyclohexyl methacrylate and 4 parts of henzyl methyl chloride were added to 50 parts of the modified 1-4-polybutadiene obtained in Example 1, and the resulting mixture had a viscosity of 9. OO0cp
A coating material for optical fiber was obtained for comparison of s (25° C.).

Example 5 Modified 1,2-polybutadiene of Example 1 and modified 1,2-polybutadiene
In the reaction to obtain 4-polybutadiene, each 2-
Except that 64 g of 2-hydroxyethyl methacrylate was used instead of 58 g of hydroxyethyl acrylate.
Using the same reaction procedure and conditions as in Example 1, modified 1,2-polybutadiene and modified 1,4-polybutadiene having methacryloyl groups at both ends of the molecule were obtained.

To 25 parts of this modified 1,2-polybutadiene and 25 parts of 91 parts of this modified 1,4-polybuta, 50 parts of tetrahydrofurfuryl acrylate and 4 parts of henzyl dimethyl ketal were added.
A coating material for optical fiber of the present invention having a viscosity of 7.0 O (1 cps (25°C)) was obtained.

Comparative Example 7 50 parts of tetrahydrofurfuryl acrylate and 4 parts of henzyl dimethyl ketal were blended with 50 parts of modified 1,2-polybutadiene obtained in Example 5, and the viscosity was 6.500 c.
A coating material for optical fiber was obtained for comparison of ps (25°C).

Comparative Example 8 50 parts of tetrahydrofurfuryl acrylate and 4 parts of henzyl dimethyl ketal were blended with 50 parts of modified 1,4-polybutadiene obtained in Example 5, and the viscosity was 8.000.
A coating material for optical fiber was obtained for comparison of cps (25° C.).

In order to evaluate the performance of each optical fiber coating material obtained in the above Examples and Comparative Examples, each material was coated on a glass plate with 0.
．． After coating to a thickness of 3 fins, it was cured with ultraviolet light using two 80 W/CII high pressure mercury lamps at a conhair speed of 10 m/min. The hardness, tensile strength and elongation of the obtained cured film were examined and the results are as shown in the table below.

The hardness is measured using the Share hardness tester type A.
The tensile strength and elongation were measured using a dumbbell No. 2 test piece using a tensile test method based on JIS-6911.

As is clear from the above results, the hardness of the cured products using the materials of Examples is appropriate, the elongation is good, the flexibility is low, and the tensile strength is high (mechanical In contrast, in the case of using the material of the comparative example, the cured product had poor elongation, poor flexibility, and low tensile strength, resulting in poor mechanical strength.

Test Example> The coating materials for optical fibers of Example 1 and Comparative Example 1.2 were applied to the surface of an optical fiber with a diameter of 125 μm spun at a speed of 50 m/min in a process subsequent to the spinning process. The film was cured with ultraviolet light using a high-pressure mercury lamp (80 w/cm, 2 lamps).

As a result, in both the coating materials of Example and Comparative Examples 1 and 2, the outer diameter of the optical fiber after coating was approximately 250 μm.
The surface was uniform, but when the coating material of Example 1 was used, it was flexible and the breaking strength was as high as 6.5 kg, indicating that the mechanical strength was low. On the other hand, when the coating material of Comparative Example 1.2 was used, the flexibility was slightly inferior to that of the coating material of Example 1, and the breaking strength was also slightly low at 6.0 kg, resulting in poor mechanical strength. Ta.

Claims (1)

[Claims] (1)a) 30 to 70% by weight of modified 1,2-polybutadiene in which at least two acryloyl or methacryloyl groups have been introduced into hydrogenated 1,2-polybutadiene
and 70 to 30% by weight of modified 1,4-polybutadiene in which at least two acryloyl or methacryloyl groups have been introduced into hydrogenated 1,4-polybutadiene; b) a reactive diluent for component a above; 1. A coating material for an optical glass fiber, comprising: a liquid compound having at least one polymerizable carbon-carbon double bond in one molecule and c) a polymerization initiator.