JPS61227948A - Coating material for optical glass fiber - Google Patents

Abstract

PURPOSE:To improve elongation and toughness of hardened product by using an oligomer contg. a specified (meth)acryloyl group as main component and incorporating a reactive diluent and a polymn. initiator to the main component. CONSTITUTION:The coating material for optical glass fiber comprises an oligomer having (meth)acryloyl group as main component, a compd. for adjusting the viscosity of the main component, and a polymn. initiator. Said oligomer is prepd. by allowing an aliphatic linear compd. having terminal OH groups and >=500 mean mol.wt., to react with a diisocyanate compd., further with a compd. having (meth)acryloyl groups which is a polyvalent ester of an aliphatic polyhydric alcohol with (meth)acrylic acid. Said viscosity adjusting compd. is one having low viscosity, and contg. >= one polymerizable C=C double bond in a molecule, such as (meth)acrylate of caprolactone adduct of tetrahydrofurfuryl alcohol.

Description

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

[Conventional technology]

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 a medium for optical transmission. Therefore, conventionally, attempts have been made to coat the surface of an optical fiber with a resin, thereby maintaining the initial strength immediately after manufacturing the optical fiber and producing an optical fiber that can withstand long-term use.

Examples of such resin coating materials include those using thermosetting resins such as silicone resin, epoxy resin, and urethane resin, and those using ultraviolet curable resins such as epoxy acrylate, urethane acrylate, and polyester acrylate. It is being

[Problem that the invention seeks to solve]

However, the above-mentioned thermosetting materials require a long time to cure and dry, resulting in poor optical fiber productivity, and lack of long-term reliability due to insufficient curing, which impairs the adhesion between the coating and the optical fiber. I don't like it. In addition, although the above-mentioned ultraviolet curable materials exhibit relatively good curing properties, they are still not satisfactory.Moreover, these types of materials generally have poor elongation and toughness of the cured product, which is a problem for optical fibers. This is one of the causes of lower reliability.

Therefore, the present invention solves the above conventional problems and improves the productivity of optical fibers with excellent curability.
Moreover, the present invention aims to provide an industrially useful coating material for optical fibers that has good elongation and toughness of the cured product and contributes to improving the reliability of optical fibers.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors discovered that the main chain of the molecule is composed of an aliphatic long-chain compound and has two or more (meth)acryloyl groups at both ends of the molecule. When a (meth)acryloyl group-containing oligomer with a specific structure bonded with a valent ester is used as the main material of this type of material, it can be coated on the surface of an optical fiber and then quickly cured by heating or irradiating with ultraviolet rays or electron beams. This invention was based on the knowledge that the cured product has excellent elongation and toughness and greatly contributes to improving the long-term reliability of optical fibers.

That is, this invention provides: a) an aliphatic chain compound having a hydroxyl group at both ends of the molecule and having a number average molecular weight of 500 or more, a diisocyanate compound, and a polyvalent ester of an aliphatic polyhydric alcohol and (meth)acrylic acid; (meth)acryloyl group-containing oligomer obtained by reacting a compound having at least one hydroxyl group and two or more (meth)acryloyl groups in one molecule, b) as a reactive diluent for component a above. 1. A coating material for an optical fiber, comprising: (C) a polymerization initiator; and (C) a polymerization initiator.

This is related to fees.

In this specification, the (meth)7acryloyl group refers to an acryloyl group and/or a methacryloyl group,
(Meth)acrylate means acrylate and/or methacrylate, and (meth)acrylic acid means acrylic acid and/or methacrylic acid, respectively.

In addition, the number average molecular weight described in this specification refers to a value measured by gel permeation chromatography (GPC) using polystyrene as a standard.
In addition, the viscosity refers to a value measured using a Brookfield viscometer.

[Structure and operation of the invention]

The (meth)acryloyl group-containing oligomer as component a used in this invention is an aliphatic chain compound having a number average molecular weight of 500 or more and having hydroxyl groups at both ends of the molecule.
Obtained by reacting a diisocyanate compound and a compound having at least one hydroxyl group and two or more (meth)acryloyl groups in one molecule with a polyvalent ester of an aliphatic polyhydric alcohol and (meth)acrylic acid. It is something.

This oligomer has two or more (
Since it has a meth)acryloyl group and is cured very quickly by active energy such as heat, ultraviolet rays, and electron beams, it is easy to improve the productivity of optical fibers by using it as the main material of the coating material. I can do it. Moreover, this cured product exhibits good elongation and toughness due to the aliphatic chain compound that constitutes the main chain of the molecule, and this elongation and toughness are further enhanced by the aliphatic polyvalent ester bonded to both ends of the molecule. . Therefore, an optical fiber coated with such a cured product exhibits less increase in transmission loss and is highly reliable compared to fibers using conventional coating materials.

Examples of the aliphatic chain compounds mentioned above for obtaining such oligomers include polyether polyols such as polypropylene glycol, polyethylene glycol, and polyoxytetramethylene glycol, polyolefin glycols, polyester polyols, polycarbonate polyols, and polycaprolactone polyols. Can be mentioned. The molecular weight of these aliphatic chain compounds is preferably a number average molecular weight of 500 or more, usually 500 to s, ooo, preferably I, 000 to 3,000; if it is less than 500, the cured product Good results cannot be obtained in terms of elongation and toughness.

The diisocyanate compound to be reacted with such an aliphatic chain compound containing a terminal hydroxyl group has a molecular weight of 170.
~1,000, specifically, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, bis(incyanate methyl)cyclohexane, dicyclohexylmethane diisocyanate, 1.
There is 6-hexane diisocyanate.

Since free isocyanate groups exist at both ends of the molecule of the aliphatic chain compound reacted with the above diisocyanate compound, a polyhydric ester of an aliphatic polyhydric alcohol and (meth)acrylic acid is added to the isocyanate group. Component C of the present invention can be obtained by reacting a compound having at least one hydroxyl group and two or more (meth)acryloyl groups in one molecule. That is, this component C has a structure in which the main chain of the molecule is composed of an aliphatic chain compound, and the polyvalent ester is bonded to both ends of the molecule via a diisocyanate compound.

Note that the reaction between an aliphatic chain compound, a diisocyanate compound, and the above polyvalent ester is generally performed by first reacting the aliphatic chain compound with the diisocyanate compound, and then reacting this reaction product with the polyvalent ester. Although a two-step reaction method is used in which the above-mentioned components are reacted at the same time, it is also possible to use a method in which the above-mentioned champions are reacted at the same time.

The above-mentioned polyvalent ester for obtaining such component C is as follows:
An aliphatic polyhydric alcohol having generally up to 50 carbon atoms having 3 to 10 hydroxyl groups in one molecule and (meth)acrylic acid, at least one in each molecule, usually 2
It is made by reacting so that up to 2 hydroxyl groups remain and (meth)acryloyl groups of 2 or more and usually up to 8 are introduced. Specific examples thereof include trimethylolpropane diacrylate, Examples include pentaerythritol triacrylate and dipentaerythritol pentaacrylate.

The coating material according to the present invention has a (meth)acryloyl group-containing oligomer as the component C obtained as described above, and a polymerizable component in one molecule as the component b that acts at least as a reactive diluent for the component C. It can be obtained by blending a compound containing one or more carbon-carbon double bonds that is liquid with low viscosity at room temperature, and further adding a polymerization initiator as component C.

The above b component is because the above (meth)acryloyl group-containing oligomer is usually solid or highly viscous at room temperature.
It is used to adjust the viscosity of the coating material and improve the workability when coating optical fibers, but it also acts as an effective component to adjust the flexibility and hardness of the cured film.

As the b component, a compound having one or more polymerizable carbon-carbon double bonds, preferably 1 to 3 carbon-carbon double bonds in the molecule and which is a low viscosity liquid at room temperature is used. is in the range of about 2 to 2,000 centivoices/25°C.

This compound is not limited to one type, but two or more types can be used in combination,
When used together, the properties of the mixture should be as described above. Therefore, one of them may be solid or have high viscosity at room temperature.

The molecular weight of this b component is usually 150 to 5,000.
That's about it.

Specific examples of the above-mentioned components include those having a (meth)acryloyl group as a polymerizable carbon-carbon double bond, such as 2
- Ethylhexyl (meth)acrylate, tetrahydrofurfuryl alcohol caprolactone adduct (meth)
Acrylate, (meth)acrylate of nonylphenol ethylene oxide adduct, polyethylene glycol di(meth)acrylate, polybrobylene glycol di(meth)acrylate, bisphenol diethylene glycol di(meth)acrylate, hydrogenated bisphenol triethylene glycol di(meth)acrylate , trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and mono to poly(meth)acrylate such as epoxy(meth)acrylate synthesized from bisphenol diglycidyl ether.

Further, as the above-mentioned components, allyl esters such as diallyl adipate, diallyl phthalate, triallyl trimellitate, and triallyl isocyanurate, and vinyl compounds such as styrene, vinyl acetate, and N-vinylpyrrolidone can also be used. Furthermore, urethane (meth)acrylate synthesized from polyoxytetramethylene glycol, polyester polyol, etc. can also be used.

The amount of the above component used is b in the total amount of component C above.
The content of the components is usually 50 to 90% by weight, preferably 55 to 80% by weight.

If the amount of component b is too small, the coating workability will be reduced or the purpose of modifying the film properties cannot be achieved, and if it is too large, the curability, elongation, toughness, etc. of the cured film will be reduced, so neither is preferable.

In this invention, the polymerization initiator used as component C is preferably a photopolymerization initiator that can quickly cure the coating material by irradiation with ultraviolet rays. Various types of sensitizers can be used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methylanthraquinone, 2,2-jethoxyacetophenone , 2-methylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, anthracene, 1,1-dichloroacetophenone, methylorthobenzoylbenzoate, etc., and those used in combination with small amounts of sensitizing aids such as amines. etc. can be mentioned.

Further, as the above polymerization initiator, it is also possible to use a thermal polymerization initiator, and specific examples thereof include peresters such as tertiary butyl peroctoate and tertiary butyl perpivalate, bis-(4-tertiary (butylcyclohexyl)-peroxydicarbonate, diacyl peroxides such as benzoyl peroxide, dialkyl peroxides such as di-tert-butyl peroxide and dicumyl peroxide, cyclohexanone peroxide,
Hydroperoxides such as methyl ethyl ketone peroxide and cumene hydroperoxide, and 2-
Examples include peroxide polymerization initiators such as ethylhexanoic acid and naphthenic acid in combination with metal promoters such as cobalt-■ salts, and other azo compounds can also be used.

The amount of these polymerization initiators to be added is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 weight parts of the total amount of components C and B. If this amount is too small, the curability cannot be satisfied, and even if it is used in excess of a predetermined amount, no further improvement in the curing rate can be expected.

The optical fiber coating material of the present invention includes the above C components, b
component and C component are essential components, and if necessary, various modifying resins such as acrylic resin, polyamide resin, polyester resin, polyether resin, polyurethane resin, polyamideimide resin, silicone resin, phenol resin, and organic Various additives such as silicon compounds and surfactants may be added (the overall viscosity is usually adjusted within the range of 1,000 to 10,000 centivoise (25°C) from the viewpoint of coating workability). It is desirable that

The coating material of the present invention having such a structure is tough and provides a relatively hard cured product, so it is usually softer than when directly applied to the optical fiber surface. After applying the inner layer coating, it is desirable to coat the outer layer on top of this.The coating thickness in this case is usually 50 to 15011 m after curing. Depending on the type of post-polymerization initiator, it may be cured by heating or by irradiation with ultraviolet rays, electron beams, etc.

Furthermore, on 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 may be further formed as the outermost layer. As a result, an optical fiber coating with even better fiber strength can be obtained.

〔Effect of the invention〕

As described above, in this invention, by using the specific (meth)acryloyl group-containing oligomer as the component a as the main material of the coating material, it has excellent curability and contributes to productivity, and the cured product It is possible to provide an industrially extremely useful optical fiber coating material that has excellent elongation and toughness and contributes to improving the long-term reliability of optical fibers.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example 1 3! with stirrer, cooler and thermometer. 1 mole of polypropylene glycol with a number average molecular weight of 1,000, 2 moles of tolylene diisocyanate, and 200 ppm of dibutyltin laurate were placed in a four-bottle flask, and 60 to 7
The reaction was carried out at 0°C for 3 hours. Then, 2 mol of pentaerythritol triacrylate was added and reacted at the same temperature as above. This reaction was carried out until the characteristic absorption band of the isocyanate group at 2.270 cm-' disappeared from the infrared absorption spectrum.

Acryloyl group-containing oligomer 30 obtained in this way
20 parts of epoxy acrylate (an acrylate obtained by reacting acrylic acid with Pico 1004, a trade name manufactured by Shell Chemical Co., Ltd.), 50 parts of bisphenol diethylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylamine ethanol were added and mixed well. An optical fiber coating material having a viscosity of 3,800 centipoise (25° C.) was obtained.

Example 2 In the same manner as in Example 1, an acryloyl group-containing oligomer was obtained from 1 mole of polyoxytetramethylene glycol having a number average molecular weight of 2.000, 2 moles of 1,6-hexane diisocyanate, and 2 moles of pentaerythritol triacrylate. To 20 parts of this oligomer, 20 parts of epoxy acrylate (same as in Example 1), 60 parts of bisphenol diethylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added and mixed well. )
A coating material for optical fiber was obtained.

Example 3 In the same manner as in Example 1, the number average molecular weight was 2. An acryloyl group-containing oligomer was obtained from 1 mole of OOO polyester (polyester synthesized from adipic acid and 1,4-butanediol), 2 moles of isophorone diisocyanate, and 2 moles of trimethylolpropane diacrylate. To 40 parts of this oligomer, 20 parts of epoxy acrylate (same as in Example 1), 40 parts of bisphenol diethylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added and mixed well. ) coating material for optical fiber was obtained.

Example 4 To 40 parts of the acryloyl group-containing oligomer obtained in Example 1, 30 parts of polyethylene glycol diacrylate having a number average molecular weight of 400, 30 parts of tripropylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added. The mixture was mixed to obtain an optical fiber coating material having a viscosity of 2.900 centipoise (25° C.).

Comparative example epoxy acrylate (same as that of Example 1) 30
70 parts of bisphenol diethylene glycol diacrylate and 3 parts of benzophenone.

and 1 part of diethylaminoethanol were added and mixed well to obtain an optical fiber coating material having a viscosity of 7,500 centipoise (25°C).

In order to examine the performance of the coating materials of Examples 1 to 4 and Comparative Examples, the following Test Examples 1 and 2 were conducted.

Test Example 1 After applying each coating material to a thickness of 0.25 m on a glass plate, it was cured using a high-pressure mercury lamp (80 W/cIm), and the amount of ultraviolet irradiation required for complete curing (mJ/cti) was determined. ,
The tensile strength, elongation and flexibility of the cured film were measured. The results were as shown in the table below. Note that tensile strength and elongation were measured in accordance with JIS K7113. Regarding the flexibility, when the cured coating peeled off from the glass plate was bent 180 degrees, those that were not damaged were evaluated as ○, and those that were damaged were evaluated as x.

<Test Example 2> An inner layer material (an oligomer synthesized from polyoxytetramethylene glycol with a number average molecular weight of 2.000, tolylene diisocyanate, and 2-hydroxyethyl acrylate, and tetrahydrofurfuryl alcohol caprolactone) was applied to the surface of an optical fiber with a diameter of 125 μm. (compounded with adducts) was coated so that the diameter after coating was 250 μm, and heated for 10 minutes using a 160 W/am high pressure mercury lamp
After curing at a linear speed of 0 m/min, the coating materials of Examples 1 to 4 and Comparative Examples were further applied as outer layers so that the diameter after coating was 400 μm, and the same high-pressure mercury lamp as above was used. It was cured at the same speed as above.

The optical fiber coated body thus obtained was prepared in Example 1.
The materials using materials No. 4 to 4 had good bobbin winding characteristics and lateral pressure characteristics, and no increase in transmission loss was observed. However, the comparison example using material No. 1 was inferior to both of the above characteristics and the transmission loss A significant increase was observed.

The above bobbin winding characteristics are obtained by examining the increase in transmission loss when wound on a bobbin with a diameter of 30 cm (tension: 80 g), and the lateral pressure characteristics are measured using sandpaper Fh150.
The increase in transmission loss was investigated by inserting an optical fiber 60 cm round trip and applying a load.

Claims (1)

[Claims] (1) a) A polyvalent ester of an aliphatic chain compound having a hydroxyl group at both ends of the molecule and having a number average molecular weight of 500 or more, a diisocyanate compound, and further an aliphatic polyhydric alcohol and (meth)acrylic acid. At least 1 in 1 molecule
a (meth)acryloyl group-containing oligomer obtained by reacting a compound having two or more hydroxyl groups with two or more (meth)acryloyl groups; 1. A coating material for an optical glass fiber, comprising: a compound containing one or more polymerizable carbon-carbon double bonds and having a low viscosity at room temperature; and c) a polymerization initiator.