JPS636505B2 - - Google Patents

Description

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

Optical glass fibers (hereinafter simply referred to as optical fibers) used as optical transmission media usually have a diameter of 200 μm or less and are brittle, so they may be damaged during manufacturing, cable production, or storage. It has the drawback that scratches are easily generated on the surface, and these scratches become a stress concentration source, and the optical fiber easily breaks when stress is applied from the outside. For this reason, it is extremely difficult to use optical fiber as it is as an optical transmission medium. Therefore, attempts have been made heretofore to provide a method of manufacturing an optical fiber in which the surface of the optical fiber is coated with plastic, whereby the initial strength immediately after the optical fiber is manufactured and the optical fiber can withstand long-term use.

Conventionally, epoxy resins and urethane resins have been used as such resin coating materials, but
Since it takes a long time to cure and dry, productivity is poor, and due to insufficient curing, adhesion to the optical fiber is insufficient, which tends to result in a lack of long-term reliability. In addition, such conventional coating materials have a disadvantage that transmission characteristics are impaired due to microbending due to poor flexibility.

For this reason, the present inventors have already proposed carbon-carbon diuretic derivatives of 1,4-polybutadienes having two or more functional groups in one molecule or the polybutadienes derived from this as an alternative to the above-mentioned materials. We proposed a coating material based on modified polybutadiene in which polymerizable carbon-carbon double bonds, which are different from double bonds, have been introduced.This material reduces drying and curing time, improves adhesion to optical fibers, and improves coating properties. This led to improvements in flexibility.

As a result of further studies following the above-mentioned prior invention, this invention was developed by adding hydrogen to the carbon-carbon double bond contained in the molecule of 1,4-polybutadiene having two or more functional groups in one molecule. The so-called hydrogenated material added thereto can be suitably applied as a coating material for optical fibers, either alone or in a mixed system with the above-mentioned non-hydrogenated material. Or, in all cases, it was discovered that good results were obtained in maintaining flexibility when left at high temperatures for a long period of time, and that the transmission characteristics could be further improved accordingly.

That is, this invention provides (a) hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule, or (b) component a and two or more functional groups in one molecule. or (c) a mixture with non-hydrogenated 1,4-polybutadiene, or (c) carbon derived from the above components a and b, which may remain in component a or contained in component b. - The present invention relates to a coating material for optical glass fiber, characterized in that the main material is a modified polybutadiene into which a polymerizable carbon-carbon double bond different from a carbon double bond is introduced.

As described above, since the coating material of the present invention is mainly composed of hydrogenated 1,4-polybutadiene, a mixture of hydrogenated 1,4-polybutadiene and non-hydrogenated 1,4-polybutadiene, or derivatives thereof, it is not included in this. It has the property of being heat-curable, photo-curable, or electron beam-curable due to its functional groups or polymerizable carbon-carbon double bonds, and its curing speed is faster than that of conventional coating materials, making it easy to mass-produce optical fibers. can be greatly improved, and deterioration in adhesion due to insufficient curing can be suppressed.

Furthermore, the cured coating formed from the coating material of the present invention has excellent flexibility compared to those using conventional thermosetting resins and compared to other polymers such as 1,2-polybutadiene. Not only can good results be obtained in terms of strength, but the increase in transmission loss caused by microbending, which is seen in conventional thermosetting resins, can be suppressed, making it possible to manufacture highly reliable optical fibers. It becomes possible.
In particular, since hydrogenated 1,4-polybutadienes or derivatives thereof are used as part or all of the main material, the non-hydrogenated 1,4-polybutadienes or derivatives thereof, which the present inventors have already proposed, can be used alone. For example, the temperature is higher than that used for
It is possible to prevent a decrease in flexibility when left at temperatures of 150°C or higher for a long period of time, and thereby improve transmission characteristics under high-temperature conditions.

1 as the a component used in this invention
Hydrogenation with two or more functional groups in the molecule 1.
4-polybutadienes have at least two functional groups such as a hydroxyl group, a carboxyl group, an isocyanate group, or an epoxy group in the molecule. Particularly preferably, 1,4-polybutadiene having the above-mentioned functional groups in less than two molecules is hydrogenated. It can be obtained by Further, after the above hydrogenation reaction, synthesis may be carried out by further reacting a polyfunctional compound, for example, by reacting a dicarboxylic acid or a diisocyanate compound with hydrogenated 1,4-polybutadiene containing a hydroxyl group.

The hydrogenation reaction can be carried out according to a general hydrogenation method using a Raney catalyst or the like, and the hydrogenation rate is 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, in the hydrogenated 1,4-polybutadiene of the present invention, the carbon-carbon double bonds contained in the 1,4-polybutadiene are not completely hydrogenated. Of course things are also included.

A first aspect of the coating material of the present invention is based on component a, that is, two or more hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule, and each polybutadiene It is a coating material whose functional groups react with each other. In a second embodiment, at least one hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule as component b, that is, component a, is used.
and at least one type of non-hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule, and the functional groups of each polybutadiene react with each other. It is something that

The non-hydrogenated 1,4-polybutadiene used as one of the main materials in the latter embodiment is
1,4- containing various functional groups as described as raw materials for the synthesis of hydrogenated 1,4-polybutadienes
A commercially available polybutadiene may be used as it is, or if necessary, one synthesized by, for example, reacting 1,4-polybutadiene containing a hydroxyl group with a dicarboxylic acid or a diisocyanate compound.

If too much of this unhydrogenated 1,4-polybutadiene is used, hydrogenated 1,4-polybutadiene
Hydrogenation of 1 and 4
- The proportion used is preferably 50% by weight or less, particularly preferably 30% by weight or less, based on the total weight of the polybutadiene.

A third aspect of the coating material of the present invention is the above-mentioned first coating material.
In contrast to the second embodiment, which is a coating material that is cured by the reaction between the functional groups contained in 1,4-polybutadiene, component a or component b, that is, two or more in one molecule. The main material is hydrogenated 1,4-polybutadiene having a functional group of This is a coating material containing a polyfunctional compound other than 1,4-polybutadiene that reacts with the functional group of 1,4-polybutadiene.

As an example of this third aspect, hexane diisocyanate, dodecane diisocyanate, diphenylmethane diisocyanate is added to hydroxyl group-containing hydrogenated 1,4-polybutadiene or a mixture of this and hydroxyl group-containing unhydrogenated 1,4-polybutadiene. There are coating materials containing diisocyanate compounds such as diphenyl ether diisocyanate. In addition, diols such as neopentyl glycol, polyethylene glycol, polypropylene glycol, hexamethylene Diamines, diamines such as diaminodiphenylmethane and diaminodiphenyl ether, adipic acid,
There are coating materials containing polybasic acids such as sebacic acid, dodecanedicarboxylic acid, phthalic anhydride, trimellitic anhydride, and dimethyl sebacate, or their esters.

Incidentally, it is possible to improve the coating properties by blending various polyfunctional compounds other than the above-mentioned 1,4-polybutadienes into the coating materials of the first and second embodiments.

In this way, in this invention, 2
When using hydrogenated 1,4-polybutadienes having 1 or more functional groups or a mixture of this and non-hydrogenated 1,4-polybutadienes having the same functional groups as mentioned above as the main material, the above-mentioned 3.
As seen in the embodiments of the present invention, all of them cause a curing reaction between functional groups, and therefore, if the functional groups have very high reactivity with each other, a two-component type is used as necessary.

A fourth aspect of the coating material of the present invention is mainly composed of modified polybutadienes as component c, and the modified polybutadienes are derived from the above-mentioned components a and b, and are included in component a. It is characterized by the introduction of a polymerizable carbon-carbon double bond different from the carbon-carbon double bonds that may remain or are contained in component b. That is, according to these modified polybutadienes, the above-mentioned functional group-curable coating material can be thermally cured, photocured, or electron beam cured by the polymerizable carbon-carbon double bond introduced into the molecule. It can provide a coating material that can be coated with water.

These modified polybutadienes include various types, one of which is hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule or hydrogenated polybutadienes having the same functional groups as above. There is a polycondensation reaction product of a mixture with unadded 1,4-polybutadiene and a polyfunctional compound having a polymerizable carbon-carbon double bond. Typically, the hydrogenated or unhydrogenated 1,4-polybutadiene having the above-mentioned functional group is hydrogenated or unhydrogenated 1,4-polybutadiene containing a hydroxyl group, and has a polymerizable carbon-carbon double bond. There is a polyester condensate in which the polyfunctional compound having the following formula is an unsaturated dibasic acid such as maleic acid, fumaric acid, itaconic acid, or citraconic acid, or a derivative thereof such as an acid anhydride.

In obtaining the above polyester condensate, the ratio of unsaturated dibasic acid or its derivative to hydroxyl group-containing hydrogenated or non-hydrogenated 1,4-polybutadiene is such that the equivalent of carboxyl group per equivalent of hydroxyl group is used. The ratio is such that it is at least 0.5 equivalent or more, preferably 0.7 to 2.0 equivalent,
It is preferable to prevent unreacted 1,4-polybutadiene from remaining as much as possible. If unreacted substances remain, when curing is performed using polymerizable carbon-carbon double bonds, there is a risk that the properties of the cured film will deteriorate.

The polycondensation reaction product is, of course, not limited to the polyester condensate mentioned above, but can also be a polymerizable carbon-carbon double bond having a functional group corresponding to the functional group of hydrogenated or non-hydrogenated 1,4-polybutadiene. By selecting a polyfunctional compound having the following, various forms can be obtained, such as polyurethane condensates, polyimide condensates, polyamide condensates, and polyamide-imide condensates.

When a modified polybutadiene consisting of such a polycondensation reaction product is used as the main material of the coating material of the present invention, it can be cured by heat curing, photocuring, or electronic curing by using an appropriate thermosetting catalyst or photosensitizer. Although it can be line-cured, it is generally preferable to add a compound having a polymerizable carbon-carbon double bond as an aid or to improve handling properties.

Among the compounds having a polymerizable carbon-carbon double bond, particularly preferred are acrylic esters, methacrylic esters, and allyl esters. Specifically, butyl triethylene glycol acrylate, polypropylene glycol methacrylate, neopentyl glycol diacrylate, polyester diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, diallyl adipate, diallyl phthalate, diethylene glycol bis(allyl carbonate), triallyl Examples include isocyanurate.

Other examples of modified polybutadienes include hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule, and unhydrogenated 1,4-polybutadienes having the same functional groups as above. It is a condensation reaction product of a mixture of and a monofunctional compound having a polymerizable carbon-carbon double bond, and it is particularly preferable that the monofunctional compound has an acrylic group, a methacrylic group, or an allyl group.

The above condensation reaction product can be produced by reacting hydrogenated or unhydrogenated 1,4-polybutadiene containing hydroxyl groups with acrylic acid, methacrylic acid, halides such as their chlorides, or esters such as methyl esters, or isocyanate. By reacting group-containing hydrogenated or non-hydrogenated 1,4-polybutadiene with hydroxyalkyl esters such as 2-hydroxyethyl acrylate or methacrylate, allyl alcohol, etc., hydrogenated or non-hydrogenated 1,4-polybutadiene containing carboxyl groups can be further produced. It is obtained by reacting 1,4-polybutadiene with an epoxy group-containing ester such as glycidyl acrylate or methacrylate, or allyl alcohol. Modified polybutadienes made of such condensation reaction products are more easily thermocurable, photocured, or electron beam cured than the polycondensation reaction products described above.

As described above, the optical fiber coating material of the present invention is a hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule or a non-hydrogenated 1,4-polybutadiene having the same functional group as above. Embodiments such as the first, second and third above, in which the mixture with 4-polybutadiene is used as the main material as it is;
There is a fourth embodiment in which a modified polybutadiene in which a polymerizable carbon-carbon double bond is introduced into the molecule derived from the above-mentioned 1,4-polybutadiene is used as the main material. It is cured by a reaction between groups, and in the latter case mainly by thermal or photopolymerization or electron beam polymerization of polymerizable carbon-carbon double bonds.

Therefore, in the case of functional group curing, no initiator is particularly required for curing, but in the case of polymerization curing, thermosetting catalysts such as benzoyl peroxide, t-butyl peroxybenzoate, acetophenone, benzophenone, benzoisopropyl ether, etc. are generally used. photosensitizers are used. These initiators may normally be used in an amount of about 0.1 to 10% by weight of the total coating material.

The coating material of the present invention may contain a modifying resin and various additives as required, and may be diluted with a solvent if desired. The modifying resin is used in an amount equal to or less than the amount of the main material, preferably 1/4 or less. Specific examples thereof include epoxy resin, polyamide, polyurethane, polyether, polyamideimide, silicone resin, and phenolic resin. Examples of the additives include curing accelerators such as cobalt naphthenate, zinc naphthenate, dimethylaniline, and dibutyltin dilaurate, organosilicon compounds, and surfactants.

In this invention, the method for coating optical fiber is as follows:
The coating material of the present invention is applied to the surface of the optical fiber immediately after the optical fiber spinning process, that is, the process of heating and stretching a rod-shaped material or block-shaped material for optical fiber to spin it into an optical fiber of a desired diameter. After coating, it is usually cured by applying heat or by irradiating light such as ultraviolet rays or electron beams.

The rod-shaped material for the optical fiber mentioned above is generally called the base material of quartz fiber.
The block-like material is one that is spun using a double crucible method using multicomponent fibers. Further, the desired diameter of the optical fiber is usually 200 μm or less.

As explained above, the optical fiber coating material of the present invention not only has a faster curing speed than conventional materials and is superior in optical fiber productivity, but also
By forming a flexible coating and by forming a thick coating, the strength and reliability of the optical fiber is improved.

The present invention will be described below with reference to Examples, but the invention is not limited to these Examples. In addition, hereinafter, parts mean parts by weight.

Example 1 Non-hydrogenated 1・ having hydroxyl groups at both ends of the molecule
4-Polybutadiene (hydroxyl group content 0.83 milliequivalents/
g) 120g, Raney nickel catalyst 7g and dioxane 120g) were placed in 1 autoclave,
Hydrogenation was carried out at a hydrogen pressure of 8 kg/cm ² and a reaction temperature of 70° C. to obtain hydrogenated 1,4-polybutadiene (hydroxyl group content: 0.8 meq/g) with a hydrogenation rate of 80%.

238 parts of this hydrogenated 1,4-polybutadiene,
100 parts of the above hydrogenated 1,4-polybutadiene adduct with tolylene diisocyanate (isocyanate group content: 8% by weight) and 0.05 part of dibutyltin diacrylate were mixed to prepare the optical fiber coating material of the present invention. The viscosity immediately after mixing was 4500 centipoise/60°C, and the hardness after curing at 150°C for 5 minutes was Shore A25.

Example 2 100 parts of the tolylene diisocyanate adduct of the hydrogenated 1,4-polybutadiene obtained in Example 1, 95 parts of polypropylene glycol having an average molecular weight of 1000, and 0.05 part of dibutyltin dilaurate were mixed to prepare an optical fiber of the present invention. It was used as a covering material. The viscosity immediately after mixing is 1200 centipoise/60℃, 150℃,
Hardness after curing for 5 minutes is Shore A27
It was hot.

Example 3 125 g of hydrogenated 1,4-polybutadiene having hydroxyl groups at both ends of the molecule obtained in Example 1 and 4.9 g of maleic anhydride were charged into a 300 c.c. flask.
React at ~125℃ for 3 hours, acid value 7, viscosity 22,500
A centipoise/60°C polyester was obtained. 70 parts of this polyester, 30 parts of neopentyl glycol diacrylate and 2 parts of benzoyl peroxide.
A coating material for optical fiber of the present invention was prepared by mixing the following parts. After curing at 150°C for 10 minutes, the hardness was Shore A30.

Example 4 125 g of hydrogenated 1,4-polybutadiene having hydroxyl groups at both ends of the molecule obtained in Example 1 was charged into a 300 c.c. flask, and 17.4 g of tolylene diisocyanate was added.
g was added dropwise over 1 hour at 30 to 40°C to form an isocyanate adduct, and then further added at 30 to 40°C for 2 hours.
By dropping 11.6 g of -hydroxyethyl acrylate over 1 hour and causing a reaction, a yellow transparent viscous liquid having acrylic groups at both ends of the molecule was obtained.
The viscosity was 250 poise/50°. 5 parts of benzoin isobutyl ether was mixed with 100 parts of this viscous liquid to obtain the optical fiber coating material of the present invention.

For the above materials, 80W/cm high pressure mercury lamp 2
After curing using a light at a conveyor speed of 10 m/min, the hardness was Shore A30.

Example 5 Non-hydrogenated 1・ having hydroxyl groups at both ends of the molecule
4-Polybutadiene (hydroxyl group content 0.83 milliequivalents/
g) 20 parts, hydrogenated 1.4- having hydroxyl groups at both ends of the molecule obtained by the method of Example 1 using the above raw materials
Polybutadiene (hydroxyl group content 0.8 meq/g)
80 parts, 42 parts of hydrogenated 1,4-polybutadiene having isocyanate groups at both ends of the molecule (isocyanate group content: 8% by weight) obtained by the method of Example 1 using the above raw materials, and 0.05 part of dibutyltin diacrylate. were mixed to form the optical fiber coating material of the present invention.

The viscosity of this material immediately after mixing was 2700 centipoise/60°C, and the hardness after curing at 150°C for 5 minutes was Shore A25.

Comparative Example 1 Non-hydrogenated 1・ having hydroxyl groups at both ends of the molecule
4-Polybutadiene (hydroxyl group content 0.83 milliequivalents/
g) Using 120 g of tolylene diisocyanate, 17.4 g of tolylene diisocyanate, and 11.6 g of 2-hydroxyethyl acrylate, the reaction was carried out in the same manner as in Example 4 to obtain a yellow transparent viscous liquid having acrylic groups at both ends of the molecule. The viscosity was 500 poise/50°C. 5 parts of benzoin isobutyl ether was mixed with 100 parts of this viscous liquid to prepare a coating material for optical fiber.

This material was cured in the same manner as in Example 4, and the hardness was Shore A50.

Comparative Example 2 5 parts of benzoin isobutyl ether was mixed with 100 parts of bisphenol type epoxy acrylate to prepare a coating material for an optical fiber. This viscosity is
The temperature was 320 poise/50°C and the hardness was Shore D90.

Next, using the coating materials of Example 4 and Comparative Examples 1 and 2 among the above Examples, the following Test Examples 1 and 2 were prepared.
As shown in the figure, the optical fiber is actually coated,
I tested its performance.

Test Example 1 The surface of an optical fiber with a diameter of 125 μm spun at a speed of 30 m/min was coated with the coating material shown in Example 4 in a process subsequent to the spinning process, and then irradiated with ultraviolet rays (2 kW lamp output). and cured. The outer diameter of the optical fiber after coating was approximately 250 μm, and the surface was uniform. In addition, the breaking strength is 6Kg
, and no increase in transmission loss was observed up to -40°C. Furthermore, even after being left at 150°C for a long time, almost no increase in transmission loss was observed at temperatures below -40°C.

On the other hand, when the same test as above was attempted for the coating material of Comparative Example 1, it was found that Example 4 except that it was left for a long time.
Although the results were almost the same as those of -40℃, the hardness of the cured film gradually increased when left at 150℃ for a long time.
An increase in transmission loss was observed in the following cases.

Test Example 2 An optical fiber was coated in the same manner as in Test Example 1 using the coating material of Comparative Example 2. The outer diameter of the optical fiber after coating varied from 175 to 215 μm. Furthermore, the breaking strength was 5.5 kg, and a rapid increase in transmission loss was observed below -40°C.

As explained above, the optical fiber coating material of the present invention has a fast curing speed, so it can be coated quickly and with good adhesion during the optical fiber spinning process, and it is highly flexible after curing, and can be used especially at high temperatures. Since the above-mentioned flexibility is maintained even after being left for a long time, there is an advantage that an optical fiber coating with excellent transmission characteristics can be obtained.

Claims (1)

[Scope of Claims] 1 (a) Hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule, or (b) the above component a and two or more functional groups in one molecule or (c) a mixture derived from the above components a and b, with a
The main material is a modified polybutadiene into which a polymerizable carbon-carbon double bond different from the carbon-carbon double bond that may remain in the component or is contained in component b is introduced. Coating material for optical glass fiber. 2. Claim 1, which is mainly composed of two or more hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule, and the functional groups of each polybutadiene react with each other. Coating material for optical glass fibers as described in . 3 At least one type of hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule and non-hydrogenated 1,4-polybutadiene having two or more functional groups in one molecule. at least 1
2. The coating material for optical glass fiber according to claim 1, wherein the coating material for optical glass fibers is a material based on polybutadiene species, and the functional groups of each polybutadiene species react with each other. 4 Hydrogenated 1,4-polybutadienes having two or more functional groups in one molecule or unhydrogenated 1,4-polybutadienes having two or more functional groups in one molecule
The coating material for an optical glass fiber according to claim 1, which is mainly composed of a mixture with 4-polybutadienes and contains a polyfunctional compound other than these polybutadienes. 5 Hydrogenated 1,4-polybutadienes in which modified polybutadienes have two or more functional groups in one molecule, or unhydrogenated 1,4-polybutadienes in which modified polybutadienes have two or more functional groups in one molecule and a polycondensation reaction product of a polyfunctional compound having a polymerizable carbon-carbon double bond; . 6 Hydrogenated 1,4-polybutadienes in which modified polybutadienes have two or more functional groups in one molecule, or unhydrogenated 1,4-polybutadienes in which modified polybutadienes have two or more functional groups in one molecule 2. The coating material for optical glass fibers according to claim 1, comprising a condensation reaction product of a mixture of the above and a monofunctional compound having a polymerizable carbon-carbon double bond, the reaction product being the main material.