JPH0239462B2 - - 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 for optical transmission are brittle, easily damaged, and have poor flexibility. destroy it. Therefore, conventionally, optical fibers have been coated with a resin on their surfaces immediately after being spun from a glass base material. Epoxy resins, urethane resins, silicone resins, and the like are used as such resin coating materials, but these have the drawback of poor adhesion to the optical fiber and deterioration of the strength of the optical fiber when moisture is absorbed.

This invention was made to solve the above problems, and its gist is:
It is characterized by containing an oligomer having a urethane bond in its molecular skeleton and an acrylic or methacrylic group in the molecule and having a number average molecular weight of 1000 to 8000, a silane coupling agent having an amino group, and a photopolymerization initiator. Coating materials for optical fibers.

The coating material of this invention can be easily cured by applying it to the surface of an optical fiber and then irradiating it with light, and this cured film has excellent elongation and elasticity and adheres well to the surface of the optical fiber. In addition, even when exposed to high humidity conditions, 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 oligomer used in this invention can generally be obtained by reacting a polyol with a diisocyanate and then reacting the isocyanate group contained in the reaction product with an acrylate or methacrylate having a hydroxyl group.

As polyols, polyester polyols and polyether polyols are typically used.
Specific examples of polyester polyols include ethylene glycol, 1,4-butanediol, 1,
Examples include condensation products of 6-hexanediol and the like with adipic acid, sebacic acid, dodecanedicarboxylic acid, etc. Specific examples of polyether polyols include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and polytetramethylene ether. Examples include glycol. In addition to polyester polyols and polyether polyols, it is also possible to use other polyols such as polycarbonate diols.

Examples of diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate,
Examples include p-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and isophorone diisocyanate. Further, examples of the acrylate or methacrylate having a hydroxyl group include 2-hydroxyethyl acrylate (methacrylate), 2-hydroxypropyl acrylate (methacrylate), and pentaerythritol acrylate (methacrylate).

Oligomers obtained from such raw material components have urethane bonds in their molecular skeletons and acrylic or methacrylic groups in their molecules, and have less elongation after curing than other oligomers such as epoxy acrylate. It has excellent elasticity and elasticity, which greatly contributes to improving the strength of the optical fiber. Among such oligomers, those in which acrylic or methacrylic groups are bonded to at least both ends of the molecule are preferred.

The molecular weight of oligomers is 1000 to 1000 in number average molecular weight.
It is 8000. If it is lower than 1000, the cured film may become brittle, and if it is higher than 8000, the content of acrylic or methacrylic groups becomes too low, which slows down the curing speed and reduces the productivity of optical fibers. It's inappropriate.

The amino group-containing silane coupling agent used in the present invention, when used in combination with the oligomer, greatly improves the adhesion to the optical fiber and gives very good results in improving moisture resistance. On the other hand, with silane coupling agents that do not have amino groups, such as γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltris(methoxyethoxy)silane, etc., the above-mentioned improvement in moisture resistance cannot be achieved.

Specific examples of silane coupling agents having an amino group include aminobutyldimethylmethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and N-2-aminoethyl-3-
Examples include aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, hexamethyldisilazane, etc. .

The amount of the silane coupling agent used is 0.01 to 10% by weight, preferably 0.01 to 10% by weight based on the total amount with the oligomer.
It is 0.1 to 3% by weight. In addition, when using a reactive diluent to be described later, the proportion of the diluent and the oligomer in the total amount may be within the above range.

In the optical fiber coating material of this invention,
In addition to the oligomer and silane coupling agent mentioned above, a photopolymerization initiator is used as an essential component. Examples of the initiator include benzoin alkyl ether, benzophenone, acetophenone, and thioxanthone. The amount used is based on 100 parts by weight of oligomer (total amount of this and oligomer when using a reactive diluent).
The amount is 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight.

Since most of the oligomers in the coating material for optical fibers of the present invention are generally highly viscous or solid, it is desirable to improve the coating workability by using an appropriate reactive diluent. Such reactive diluents include monoacrylates (methacrylates) and polyacrylates (methacrylates).
is effective, but other conventionally known methods can be widely applied. The amount used varies considerably depending on the type of the oligomer, but it is generally preferred to be 60% by weight or less based on the total amount with the oligomer.

Among typical reactive diluents, specific examples of monoacrylates and polyacrylates include:
For example, cyclohexyl acrylate, benzyl acrylate, carbitol acrylate, 2-
Ethylhexyl acrylate, 2-hydroxyethyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate,
Examples include triethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate. As the monomethacrylate or polymethacrylate, those having the same chemical structure as the above monoacrylate or polyacrylate except that the acrylic group is replaced by the methacrylic group are used.

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 resin. Various additives such as accelerators, organosilicon compounds, and surfactants may be added.

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 irradiation with light such as ultraviolet rays.

As detailed above, the optical fiber coating material of the present invention 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. Obtainable.

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 1 300 equipped with thermometer, stirrer and reflux condenser
1.6 synthesized by a conventional method in a cc four-necked flask.
- Prepare 102 g of polyester polyol (hydroxyl value 110) of hexanediol and adipic acid and 34.8 g of tolylene diisocyanate, and heat the mixture at 50 to 70°C.
After reacting for an hour, 23.2 g of 2-hydroxyethyl acrylate was added and the reaction was further carried out at 70°C for 2 hours to obtain an oligomer with a number average molecular weight of 1600.

60 parts of this oligomer, 40 parts of neopentyl glycol diacrylate, 3 parts of benzoin isobutyl ether and 0.5 part of N-2-aminoethyl-3-aminopropyltrimethoxysilane were dissolved and mixed to give a viscosity (25°C) of 2700 centipoise. A coating material for optical fiber was obtained.

Example 2 A four-neck flask similar to that used in Example 1 was charged with 100 g of polypropylene glycol having a number average molecular weight of 1000 and 33.5 g of isophorone diisocyanate, and after reacting at 60 to 80°C for 2 hours, 2-
By adding 11.6 g of hydroxyethyl acrylate and further reacting at 70°C for 2 hours, an oligomer with a number average molecular weight of 3300 was obtained.

70 parts of this oligomer, 30 parts of 1,6-hexanediol diacrylate, 3 parts of benzoin isobutyl ether and 0.5 part of N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane were dissolved and mixed. (25℃) 3500
A centipoise coating material for optical fiber according to the present invention was obtained.

Example 3 Into a four-necked flask similar to that used in Example 1, 200 g of polytetramethylene ether glycol with a number average molecular weight of 2000 and 37.5 g of diphenylmethane diisocyanate were charged and reacted at 80 to 90°C for 2 hours. Thereafter, 11.6 g of 2-hydroxyethyl acrylate was added and the reaction was further carried out at 80°C for 1 hour to obtain an oligomer with a number average molecular weight of 5100.

60 parts of this oligomer, 40 parts of polyethylene glycol diacrylate with a number average molecular weight of 400, 3 parts of benzoin isobutyl ether and 0.5 part of hexamethyldisilazane were dissolved and mixed, and the viscosity (25°C)
A coating material for optical fiber of the present invention having a centipoise of 5500 was obtained.

Next, in order to examine the performance of each of the coating materials of Examples 1 to 3, 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.

In addition, one in which the silane coupling agent was removed from the material of Example 1 (Comparative Example 1) and one in which 0.5 part of vinyltris(methoxyethoxy)silane was used in place of the silane coupling agent in Example 1 (Comparative Example 2). In this case, peeling of the cured film was observed 0.5 hours and 1 hour after being left in water, respectively.

<Coating test> In the process subsequent to 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 irradiated with ultraviolet rays (lamp output 2 KW 2 lights). and cured. The outer diameter of each optical fiber after coating is 300μ.
m, and the breaking strength was 6 kg in all cases. In addition,
Almost similar results were obtained for Comparative Examples 1 and 2.

Next, the coated optical fiber is placed in water at 60℃.
When the breaking strength was examined after being immersed for 100 hours, it was 5 to 6 kg for Examples 1 to 3, which was almost the same as that before immersion in water. On the other hand, in Comparative Examples 1 and 2, the weight decreased to 2 kg.

Claims (1)

[Claims] 1. Contains an oligomer with a number average molecular weight of 1000 to 8000 having a urethane bond in the molecular skeleton and an acrylic or methacrylic group in the molecule, a silane coupling agent having an amino group, and a photopolymerization initiator. Coating material for optical glass fiber.