JPS6358773B2 - - 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 referred to as optical fibers) used for optical transmission are fragile, easily damaged, and have poor flexibility. Destroy. Therefore, conventionally, optical fibers have been coated with a resin on their surfaces immediately after being spun from a glass base material. Such resin coating materials include:
Epoxy resins, urethane resins, silicone resins, and the like are used, but they have the drawback of poor adhesion to optical fibers, and when they absorb moisture, they deteriorate the strength of the optical fibers.

This invention was made to solve the above problems, and has the following general formula: (In the formula, R ₁ is an alkylene group and R ₂ is an alkyl group.) A siloxane derivative having a hydroxyl group at both ends represented by the formula is reacted with a diisocyanate, and a siloxane derivative having an additional hydroxyl group is added to the isocyanate group contained in this reaction product. The present invention relates to a coating material for an optical fiber, which contains as a constituent a urethane acrylate or urethane methacrylate having a siloxane bond in the molecule and having a number average molecular weight of 900 to 1100, which is obtained by reacting an acrylate or methacrylate.

In addition, hereinafter, (meth)acrylate means acrylate or methacrylate. Therefore, compounds containing this term (meth)acrylate, for example urethane (meth)acrylate means urethane acrylate or urethane methacrylate, polyester (meth)acrylate means polyester acrylate or polyester methacrylate, and for other compounds The same applies to the above.

The coating material of the present invention can be easily cured by applying light or heating after being applied to the surface of the optical fiber. Even when exposed to a humid atmosphere, the adhesion is not significantly impaired. For this reason, the optical fiber after coating exhibits great strength not only under normal conditions but also under high humidity conditions, and its optical transmission characteristics are greatly improved compared to those using conventional coating materials. .

The urethane (meth)acrylate having a siloxane bond in the molecule used in this invention has the following general formula; (In the formula, R ₁ is an alkylene group and R ₂ is an alkyl group.) A siloxane derivative having a hydroxyl group at both terminals, such as bis(2-hydroxyethyl)tetramethyldisiloxane, represented by the following is used as a starting material, and this and a diisocyanate are used as starting materials. After reacting with, the isocyanate group contained in this reaction product,
Furthermore, it can be obtained by reacting a (meth)acrylate having a hydroxyl group, and those having a number average molecular weight in the range of 900 to 1100 are used.

Examples of diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate,
Examples include p-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and isophorone diisocyanate.

Examples of (meth)acrylates having a hydroxyl group include 2-hydroxyethyl acrylate (methacrylate), 2-hydroxypropyl acrylate (methacrylate), and pentaerythritol acrylate (methacrylate).

The urethane (meth)acrylate having a siloxane bond in the molecule synthesized in this manner can be used alone, but other (meth)acrylates are generally used in combination at a ratio of 70% by weight or less.
For example, (meth)acrylate of monohydric or polyhydric alcohol, polyester (meth)acrylate,
These include epoxy (meth)acrylate, urethane (meth)acrylate, etc.

There is no need to mention these examples, but just to be safe, specific examples of acrylates of monohydric or polyhydric alcohols include cyclohexyl acrylate, benzyl acrylate, carbitol acrylate, 2-ethylhexyl acrylate, and ethylene glycol diacrylate. , diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1.6-hexanediol diacrylate, polyethylene glycol diacrylate, polypropylene glycol dideacrylate, trimethylolpropane triacrylate,
Examples include pentaerythritol triacrylate.

In addition to the above-mentioned components, the optical fiber coating material of the present invention may optionally contain various modifying resins such as acrylic resin, polyamide resin, polyether, polyurethane, polyamideimide, silicone resin, and phenolic resin, as well as curing resins. Various additives such as accelerators, organosilicon compounds, and surfactants may be added.

In the case of light irradiation, a photopolymerization initiator is used. Examples of these include benzoin alkyl ethers, benzophenones, acetophenones, thioxanthone, and the like. The amount used is urethane (meth)acrylate and other (meth)acrylates that have siloxane bonds in the molecule.
0.1 to 10 parts by weight per 100 parts by weight, preferably 1 to 10 parts by weight
It is 5 parts by weight. When curing by heating, an organic peroxide such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, etc. is added to 100 parts by weight of the above urethane (meth)acrylate and other (meth)acrylates.
The amount is 0.1 to 10 parts by weight, preferably 1 to 3 parts by weight.

In order to actually coat an optical fiber with the optical fiber coating material of the present invention, it may be carried out according to a conventionally known method, and generally, the coating material of the present invention is coated on the surface of the optical fiber in a process subsequent to the spinning process. After coating, it may be polymerized and cured by irradiating it with heat or light such as ultraviolet rays.

As described above, according to the coating material for optical fiber of the present invention, it is possible to obtain an optical fiber coating that has excellent film properties and adhesion to the optical fiber, and exhibits great strength not only under normal conditions but also under high humidity conditions. be able to.

Hereinafter, the present invention will be explained in more detail by describing examples. In addition, in the following, parts mean parts by weight.

Example 1 100 with thermometer, stirrer and reflux condenser
Charge 22.4 g of bis(2-hydroxyethyl)tetramethyldisiloxane and 34.8 g of tolylene diisocyanate into a four-neck CC flask, and add 50 to 60 g of tolylene diisocyanate.
After reacting at .degree. C. for 3 hours, 23.2 g of 2-hydroxyethyl acrylate was added and further reacting at 60.degree. C. for 1 hour to obtain urethane acrylate having a number average molecular weight of 900 and having a siloxane bond in the molecule.

50 parts of this product, 50 parts of polyethylene glycol diacrylate with an average molecular weight of 400, and 3 parts of benzoin isobutyl ether were dissolved and mixed.
℃) 450 centipoise coating material for optical fiber was obtained.

Example 2 A four-necked flask similar to that used in Example 1 was charged with 22.4 g of bis(2-hydroxyethyl)tetramethyldisiloxane and 44.6 g of isophorone diisocyanate, and reacted at 60 to 70°C for 2 hours. Later, 2-hydroxyethyl acrylate 23.2
A urethane acrylate having a number average molecular weight of 1000 and having a siloxane bond in the molecule was obtained by further reacting at 70° C. for 1 hour.

10 parts of this product, 90 parts of urethane acrylate (an oligomer with a number average molecular weight of 3300 synthesized from polypropylene glycol with an average molecular weight of 1000 and isophorone diisocyanate), and 3 parts of benzoin isobutyl ether were dissolved and mixed, and the mixture had a viscosity (50°C) of 6000.
A centipoise coating material for optical fiber was obtained.

Example 3 A four-necked flask similar to that used in Example 1 was charged with 22.4 g of bis(2-hydroxyethyl)tetramethyldisiloxane and 50 g of diphenylmethane diisocyanate, and reacted at 80 to 90°C for 2 hours. After this, 26 g of 2-hydroxypropyl acrylate was added and the reaction was further carried out at 80°C for 1 hour to obtain urethane acrylate having a number average molecular weight of 1100 and having a siloxane bond in the molecule.

30 parts of this product, 70 parts of bisphenol A diethylene glycol diacrylate, and 3 parts of benzoin isobutyl ether were dissolved and mixed.
A coating material for optical fiber of 1100 centipoise was obtained.

Next, in order to examine the performance of each coating material of Examples 1 to 3 above, the following tests were conducted.

<Adhesion test> After applying each material to a thickness of 0.1 mm on a quartz glass plate, it was cured using a high-pressure mercury lamp of 80 W/cm x 2 lights at a conveyor speed of 50 m/min, and then left in water. The time required for the cured film to peel off was measured. As a result, no peeling phenomenon was observed in any of Examples 1 to 3 even after being left for 7 days.

<Coating test> In the process following the spinning process, each material of Examples 1 to 3 was applied to the surface of an optical fiber with a diameter of 125 μm spun at a speed of 50 m/min, and then UV rays (lamp output 2 KW 2 lights) were irradiated. and cured. The outer diameter of each optical fiber after coating is 300 μm.
The breaking strength was 6 kg in all cases.

Next, the coated optical fiber is placed in water at 60℃.
After immersing for 100 hours, the breaking strength was examined.
In Examples 1 to 3, the weight was 5 to 6 kg, which was almost the same as before immersion in water.

Claims (1)

[Claims] 1. The following general formula; (In the formula, R ₁ is an alkylene group and R ₂ is an alkyl group.) A siloxane derivative having a hydroxyl group at both ends represented by the formula is reacted with a diisocyanate, and a siloxane derivative having an additional hydroxyl group is added to the isocyanate group contained in this reaction product. 1. A coating material for optical glass fiber, comprising urethane acrylate or urethane methacrylate having a siloxane bond in the molecule and having a number average molecular weight of 900 to 1100, obtained by reacting acrylate or methacrylate.