JP2001042137A - Optical fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flexibility suitable for the purpose for which a core is used to an organic-inorganic composite material and to reduce transmission loss. SOLUTION: A polymerization reactive material prepared by blending a photopolymerizable monomer with an auxiliary photoreaction initiator and a catalyst are added to a sol-gel solution prepared by blending a metal alkoxide, preferably ethyl silicate with alcohol and water. The resulting mixed solution 2 is poured into a core forming mold 3, irradiated with UV and held at 60-100 deg.C to form a core 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber and a method for manufacturing an optical fiber, and more particularly, to an optical fiber and a method for manufacturing an optical fiber having a core made of a flexible organic / inorganic composite material suitable for a purpose of use. About the method.

[0002]

2. Description of the Related Art Conventionally, a silica glass optical fiber has been used as an optical fiber, and the technology of the silica glass optical fiber has been completed. However, this silica glass optical fiber has poor flexibility and poor handling properties. Therefore, in recent years, synthetic resin optical fibers have been used. This synthetic resin-based optical fiber is composed of a polymer having good light transmittance and a high refractive index as a core component, and a polymer having a lower refractive index than the core component polymer as a clad component. It is constituted by a structure. As a core component of the synthetic resin optical fiber, polymethyl methacrylate (PMMA) having excellent transparency, weather resistance, mechanical properties, and the like is used. A plastic optical fiber (PO) using an organic material such as PMMA
F) has come to be used as a medium for networks such as automobiles and homes because of its flexibility and ease of handling.

[0003]

SUMMARY OF THE INVENTION However, PMM
Synthetic resin-based optical fibers using A or PC (polycarbonate) as the core of the optical fiber have excellent flexibility, but the transmission loss is much larger than that of silica glass-based optical fibers, and there is a problem in use. have. In order to solve this problem, it has been proposed to use an organic material such as an organosiloxane represented by silicone or an organopolysiloxane for the core (Japanese Patent No. 2836256).
JP-A-8-199067, JP-A-9-18492
9, JP-A-4-350802).

However, any of these synthetic resin optical fibers using an organic material as a core is based on an organic material and cannot adjust the flexibility (hardness) of the optical fiber. In addition, since synthetic resin optical fibers using these organic materials for the core have many impurities, for example, in the case of polysiloxane, one or more organic molecules are bonded to silica 1 and transmission loss is low. In the case of only glass fiber, it is 0.3 to 3 dB / km,
In the case of a plastic fiber made of PMMA or the like, the value is as high as 200 dB / km, and there is a problem that transmission loss is large.

On the other hand, a conventional silica glass optical fiber is
Although the transmission loss is very low, the terminal processing of the silica glass based optical fiber is very complicated due to the very small size of the core, and the element for converting electricity for the silica glass based optical fiber into light (E / O), an element that converts light into electricity (O /
E) has a high price and lacks executable performance. Further, the glass produced by the conventional sol-gel method has a problem that the volume control is very difficult because the volume shrinks very much during the drying and sintering stages.

An object of the present invention is to reduce the transmission loss by providing an organic / inorganic composite material as a core with flexibility suitable for the intended use.

[0007]

According to a first aspect of the present invention, there is provided an optical fiber comprising: an inorganic material comprising a metal alkoxide; and an organic fiber comprising an acrylic photopolymerizable monomer or an epoxy photopolymerizable monomer. A core is formed by mixing materials. With this configuration, according to the first aspect of the invention, the organic / inorganic composite material can be used as the core to have flexibility suitable for the intended use, and transmission loss can be reduced.

In order to achieve the above object, an optical fiber according to a second aspect is characterized in that the metal alkoxide is composed of ethyl silicate. Generally, a metal alkoxide is a compound in which hydrogen of a hydroxyl group of an alcohol is replaced with silicon. When an alkali metal is dissolved in alcohol, hydrogen is generated to generate an alkoxide. This alkoxide generates an alkoxy anion. When the anion directly participates in a nucleophilic reaction, alkoxylation occurs. When the anion is deprived of a proton from a substance participating in the reaction to induce the reaction, the alkoxide acts as a condensing agent. Ethyl silicate is a compound in which the hydrogen of the hydroxyl group of ethyl alcohol is replaced with silicon. According to the second aspect of the present invention, a core having an organic / inorganic composite material, which has a small transmission loss, has flexibility suitable for the intended use, and has a small transmission loss. Can be formed.

According to a third aspect of the present invention, there is provided a method for manufacturing an optical fiber, comprising: a sol-gel solution comprising a metal alkoxide, an alcohol and water; A mixed solution obtained by adding a polymerization reaction material and a catalyst to a core mold, and irradiating the poured solution with ultraviolet rays to maintain a temperature of 60 ° C to 100 ° C to form a core. It is. After pouring a mixed solution of a sol-gel solution containing a metal alkoxide, an alcohol, and water, a polymerization reaction material containing a photopolymerization monomer and a photoreaction initiation aid, and a catalyst, into a mold for molding a core. Then, the mixed solution is irradiated with ultraviolet rays, and the photopolymerization monomer starts the polymerization reaction by the action of the photoreaction initiation aid. Thereafter, the mixture is allowed to stand at a temperature of 60 ° C. to 100 ° C. to cause a hydrolysis reaction of silica to proceed, and a mixture of an organic material and an inorganic material (silica) forms a core.

By changing the amount of the photopolymerizable monomer used as the polymerization reactant, the amount of the photopolymerizable monomer can be changed from a soft material such as a silicone resin (in this case, the amount of the monomer is equal to or greater than that of the metal alkoxide) to a material such as silica glass. The strength can be adjusted up to a solid (in the absence of any monomer) (adjustment of flexibility). Further, when the photopolymerization monomer (organic material) forms a — (Si—O) — network by a sol-gel method, the strength and transmission of the core depend on the degree of dispersion in the Si bond. Determining the loss (basically, since the absorption of light due to-(CH)-coupling becomes the optical wavelength region of the region used in optical communication, the smaller the loss, the smaller the transmission loss) become. The amount of the photopolymerizable monomer affects the hardness (hardness) of the core when the core is formed. That is, it is necessary to proceed the reaction more slowly as the hardness of the core increases, and to prevent the occurrence of cracks. The photoreaction initiation aid of the polymerization reaction material promotes the polymerization of the photopolymerizable monomer, and the amount added depends on the amount of the photopolymerizable monomer to be polymerized. If less (for example,
1% by weight), there is no problem even if it is not added. The alcohol contained in the sol-gel solution is added to hydrolyze the metal alkoxide, and the amount of the alcohol controls the speed of the hydrolysis reaction in the sol-gel method. In other words, if the amount of alcohol added is increased,
The hydrolysis reaction proceeds slowly, and when the amount of alcohol added is reduced, the hydrolysis reaction proceeds faster by that amount. Therefore, when the amount of the photopolymerization monomer is large, the core becomes hard when the core is formed, so that the addition amount of the alcohol is increased to prevent the occurrence of cracks when the core is formed, and the hydrolysis reaction proceeds slowly. Will be. The water contained in the sol-gel solution may accelerate the hydrolysis reaction due to moisture in the air, and in such a case, it may not be necessary to add it at all. Hydrogen chloride (HCl),
Ammonia (NH ₃ ) or the like is used. This catalyst
It has the effect of affecting the hydrolysis reaction, and the start time of the hydrolysis reaction in the sol-gel method can be controlled by the amount and timing of addition. Therefore, this catalyst was added to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water, and a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid was added thereto. I have.

When a catalyst is added to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water as described above, a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid is added, The start timing of the hydrolysis reaction is controlled by the amount of the catalyst added, and the mixed solution is irradiated with ultraviolet rays, whereby the polymerization reaction of the photopolymerizable monomer is started by the action of the photoreaction initiation aid. The hydrolysis reaction of the metal alkoxide is allowed to proceed by being left at a temperature of 60 ° C to 100 ° C in parallel with the start of the polymerization reaction.
According to the third aspect of the present invention having such a configuration, the organic / inorganic composite material can be used as a core to reduce transmission loss and provide flexibility suitable for the intended use,
A core with small transmission loss can be formed.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an optical fiber, comprising mixing a photopolymerizable monomer and a photoreaction initiation aid into a sol-gel solution comprising a metal alkoxide, an alcohol and water. The mixed solution obtained by adding the polymerization reaction material and the catalyst is poured into a tube constituting a clad, and the poured mixed solution is irradiated with ultraviolet rays.
The optical fiber is manufactured while maintaining the temperature at 0 ° C to 100 ° C. A sol-gel solution containing a metal alkoxide, an alcohol, and water, a polymerization reaction material containing a photopolymerization monomer and a photoreaction initiation aid, and a mixed solution containing a catalyst were poured into a tube constituting a clad. Thereafter, the mixed solution is irradiated with ultraviolet rays, and the photopolymerization monomer, which is a polymerization reaction material, starts a polymerization reaction by the action of a photoreaction initiation aid. Thereafter, the mixture is allowed to stand at a temperature of 60 ° C. to 100 ° C. to cause a hydrolysis reaction of silica to proceed, and a mixture of an organic material and an inorganic material (silica) forms an optical fiber. According to the fourth aspect of the present invention, by using the organic / inorganic composite material as a core, light having a small transmission loss and flexibility suitable for the intended use can be provided, and light having a small transmission loss can be provided. Fibers can be formed.

In order to achieve the above object, a method of manufacturing an optical fiber according to a fifth aspect is characterized in that the metal alkoxide is composed of ethyl silicate. Ethyl silicate is a compound in which the hydrogen of the hydroxyl group of ethyl alcohol is replaced with silicon as described above. According to the fifth aspect of the present invention, by using the organic / inorganic composite material as a core, light having a small transmission loss and flexibility suitable for the intended use can be provided, and light having a small transmission loss can be provided. Fibers can be formed.

According to a sixth aspect of the present invention, there is provided a method for manufacturing an optical fiber, wherein the mixed solution comprises 10 to 50% by weight of a metal alkoxide and 1 to 30% by weight of a photopolymerizable monomer.
%, 15% or less by weight of a photoreaction initiation aid, 0 to 60% by weight of alcohol, 0 to 30% by weight of water, and 5% by weight or less of a catalyst. The amount of the metal alkoxide constituting the sol-gel solution determines the transmission characteristics of the optical fiber. Also, the photopolymerizable monomer constituting the polymerization reaction material determines the hardness of the core, and the core produced can be made harder by increasing the amount of the photopolymerizable monomer. The hardness of the core can be adjusted by reducing the number of cores. Further, the addition amount of the photoreaction initiation aid constituting the polymerization reaction material depends on the amount of the photopolymerization monomer to be polymerized. If the amount of the photopolymerization monomer is large, the amount of addition is relatively large. The amount of alcohol added to hydrolyze the metal alkoxide constituting the sol-gel solution is increased when the hydrolysis reaction of the metal alkoxide proceeds slowly. If you want to make it go faster, reduce the amount of alcohol added. Furthermore, the addition amount of water constituting the sol-gel solution is relatively large when the addition amount of alcohol is large as in the case of the addition amount of alcohol, and is relatively small when the addition amount of alcohol is small. . The amount of catalyst added is
It is determined by the start time for hydrolyzing the metal alkoxide. According to this structure, claim 6
According to the invention described in (1), an organic / inorganic composite material can be used as a core to provide an optical fiber with a small transmission loss and flexibility suitable for the intended use, and a small transmission loss.

In order to achieve the above object, in the method of manufacturing an optical fiber according to the present invention, the time of irradiating the mixed solution with ultraviolet rays is set before the start of the hydrolysis reaction or simultaneously with the start of the hydrolysis reaction. Things. The time when the mixed solution is irradiated with ultraviolet light indicates the time when the photoreaction initiation aid added to the mixed solution is acted on, and when the mixed solution is irradiated with ultraviolet light, the photoreaction initiation aid is acted upon by the action of the photoreaction initiation aid. The polymerization monomer will initiate the polymerization reaction. Before starting the hydrolysis reaction, before the hydrolysis reaction of the metal alkoxide started, while mixing the metal alkoxide, the photopolymerization monomer and the photoreaction initiation auxiliary, after adding the alcohol and water first, It may be just after adding the catalyst. The timing of irradiating the mixed solution with ultraviolet rays may be the same as the start of the hydrolysis reaction. Simultaneously with the start of the hydrolysis reaction, it means that the hydrolysis reaction of the metal alkoxide has started, and the sol-gel solution obtained by mixing the metal alkoxide, the alcohol and water is mixed with the photopolymerization monomer and the photoreaction initiation aid. This is the time when the hydrolysis reaction of the metal alkoxide constituting the sol-gel solution was started by further adding a catalyst to the polymerization reaction material. Whether or not the hydrolysis reaction of the metal alkoxide constituting the sol-gel solution has started can be determined by checking the viscosity of the sol-gel solution. That is, a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water,
The solution containing the polymerization reaction material, which is a mixture of the photopolymerization monomer and the photoreaction initiation aid, is a sol-like solution. When the hydrolysis reaction of the metal alkoxide starts by adding a catalyst, the sol-like solution becomes a gel. Therefore, the viscosity of the sol-gel solution changes. By looking at this viscosity, it can be determined whether or not the hydrolysis reaction of the metal alkoxide in the sol-gel solution has started. It is important that the mixed solution is irradiated with ultraviolet light before the start of the hydrolysis reaction or at the same time as the start of the hydrolysis reaction, and after the hydrolysis reaction has occurred, the polymerization reaction is caused by the irradiation of ultraviolet light. Even so, the polymer cannot be dispersed and bonded in the-(Si-O)-network, resulting in a bias. When such a bias occurs, an organic material (polymer) having a large molecular weight is dispersed in a — (Si—O) — network, and the organic material (polymer) acts as a spring. However, it cannot be expected that cracks are prevented from occurring in response to volume shrinkage during vitrification after the hydrolysis reaction. In other words, irradiating the sol-gel solution with ultraviolet light before starting the hydrolysis reaction or simultaneously with the start of the hydrolysis reaction disperses the organic material (polymer) having a high molecular weight, and vitrifies the sol-gel solution after the hydrolysis reaction. This is necessary in order to prevent the organic material (polymer) having a high molecular weight from acting as a spring when volume shrinkage occurs and to prevent cracks from occurring in the core formed by vitrification. With this configuration, according to the invention described in claim 7, the core made of the organic-inorganic composite material can have flexibility suitable for the intended use without causing cracks in the core, and An optical fiber with small transmission loss can be formed.

In order to achieve the above object, a method of manufacturing an optical fiber according to claim 8, wherein the time when the temperature is maintained at 60 ° C to 100 ° C is determined by uniformly dispersing the photopolymerizable monomer in the solution. Are the ones that initiate the polymerization reaction by the action of the photoreaction initiation aid and form a molecular network at the same time or after the molecular network is formed. 60 ° C-100
The time when the temperature is maintained at ℃ is when the hydrolysis of the metal alkoxide (silica) proceeds. Generally, the mixed solution is irradiated with ultraviolet rays, and the photopolymerization monomer is polymerized by the action of the photoreaction initiation aid. Is started, and after the polymerization reaction has sufficiently proceeded, the mixture is left at a temperature of 60 ° C to 100 ° C. The temperature of 60 ° C to 100 ° C is a temperature suitable for promoting the hydrolysis of the metal alkoxide (silica). At the time when the temperature is maintained at 60 ° C. to 100 ° C., the photopolymerizable monomer uniformly dispersed in the sol-gel solution starts the polymerization reaction by the action of the photoreaction initiation aid, and simultaneously forms a molecular network. Or after the formation of a molecular network. That is, it is important that the timing of maintaining the temperature at 60 ° C. to 100 ° C. (the timing of starting the hydrolysis reaction) is after the photopolymerizable monomer starts the polymerization reaction by the action of the photoreaction initiation aid. If the photopolymerizable monomer initiates the hydrolysis reaction before starting the polymerization reaction by the action of the photoreaction initiation aid,-(Si-O)- The polymer cannot be dispersed and bonded in the network of
This is because when vitrified after the hydrolysis reaction, cracks occur in the core due to volume shrinkage. 60 ° C-1
The time at which the temperature is maintained at 00 ° C. may be the same as when the molecular network is formed. The formation of this molecular network is carried out by starting the hydrolysis reaction of the metal alkoxide by adding a catalyst. With this configuration, according to the invention of claim 8, the core made of the organic-inorganic composite material can be provided with flexibility suitable for the intended use without causing cracks in the core, and An optical fiber with small transmission loss can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an optical fiber and a method for manufacturing the optical fiber according to the present invention will be described. FIG. 1 is a conceptual diagram showing one embodiment of a method for manufacturing an optical fiber according to the present invention.

In FIG. 1A, a mixed solution 2 is contained in a container 1. This mixed solution 2 is obtained by adding a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water, and a catalyst. The mixed solution 2 contained in the container 1 is poured into a core forming die 3 which is a die for forming a core.

The amount of metal alkoxide (specifically, ethyl silicate (TEOS)) constituting the sol-gel solution is 1
0 to 50% by weight, the amount of alcohol (specifically, ethanol) is 0 to 60% by weight, and the amount of water is 0 to 30%.
% By weight. The amount of the photopolymerizable monomer (acrylic or epoxy type) constituting the polymerization reaction material is 1 to 30% by weight, and the amount of the photoreaction initiation aid (specifically, benzoyether) is 15% by weight. It consists of the following. Further, the amount of the catalyst (specifically, HCl, NH ₃ or the like) is 5% by weight or less.

A mixed solution 2 mixed in such a ratio
Is poured into the core mold 3 from the container 1 and left as it is, the metal alkoxide in the sol-gel solution starts a hydrolysis reaction. Therefore, before or simultaneously with the start of the hydrolysis reaction of the metal alkoxide in the sol-gel solution, as shown in FIG.
V). When the mixed solution 2 is irradiated with ultraviolet light, the photopolymerization monomer starts a polymerization reaction by the action of the photoreaction initiation aid constituting the polymerization reaction material mixed in the mixed solution 2 to form a molecular network.

In the polymerization reaction of the photopolymerizable monomer, a hydrolysis reaction is performed by a temperature treatment at the same time as the formation of the molecular network or after the formation of the molecular network, as shown in FIG. This temperature treatment
This is performed by maintaining the temperature at about 60 ° C. to 100 ° C. and leaving it to stand. In this state, the hydrolysis reaction of silica proceeds, and a mixture of an organic material and an inorganic material (silica) forms the core 4.

As described above, a mixed solution 2 containing a photo-polymerizable monomer and a photo-reaction initiation aid and a catalyst-added mixed solution 2 in a sol-gel solution containing a metal alkoxide, an alcohol and water are used as a core. After pouring the mixture 4 into the core mold 3 for molding, the mixed solution 2 is irradiated with ultraviolet rays, and the photopolymerization monomer starts the polymerization reaction by the action of the photoreaction initiation aid. Thereafter, the core 4 is formed by mixing the organic material and the inorganic material (silica) by allowing the silica to undergo a hydrolysis reaction by being left at a temperature of 60 ° C to 100 ° C.

By changing the amount of the photopolymerization monomer used as the polymerization reaction material, the photopolymerization monomer can be changed from a soft material such as a silicone resin (in this case, the amount of the monomer is equal to or more than the metal alkoxide) to a material such as silica glass. The strength can be adjusted up to a solid (in the absence of any monomer) (adjustment of flexibility). Further, when the photopolymerization monomer (organic material) forms a — (Si—O) — network by a sol-gel method, the strength and transmission of the core depend on the degree of dispersion in the Si bond. Determining the loss (basically, since the absorption of light due to-(CH)-coupling becomes the optical wavelength region of the region used in optical communication, the smaller the loss, the smaller the transmission loss) become. The amount of the photopolymerizable monomer affects the hardness (hardness) of the core when the core is formed. That is, it is necessary to proceed the reaction more slowly as the hardness of the core increases, and to prevent the occurrence of cracks.

The photoreaction initiation aid of the polymerization reaction material promotes the polymerization of the photopolymerization monomer.
It depends on the amount of the photopolymerizable monomer to be polymerized. When the amount of the photopolymerizable monomer is extremely small (for example, 1% by weight), there is no problem even if it is not added. The alcohol compounded in the sol-gel solution is specifically added with ethanol or the like to hydrolyze a metal alkoxide (specifically, ethyl silicate or the like). It controls the speed of the hydrolysis reaction. In other words, if the amount of alcohol added is increased,
The hydrolysis reaction proceeds slowly, and when the amount of alcohol added is reduced, the hydrolysis reaction proceeds faster by that amount. Therefore, when the amount of the photopolymerization monomer is large, the core becomes hard when the core is formed, so that the addition amount of the alcohol is increased to prevent the occurrence of cracks when the core is formed, and the hydrolysis reaction proceeds slowly. Will be.

The water contained in the sol-gel solution may accelerate the hydrolysis reaction due to the moisture in the air, in which case it may not be added at all (0% by weight). Hydrogen chloride (HCl), ammonia (NH ₃ ), or the like is used as a catalyst for the hydrolysis reaction. This catalyst has an effect on the hydrolysis reaction, and the start time of the hydrolysis reaction in the sol-gel method can be controlled by the amount and timing of the addition. Therefore, this catalyst was added to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water, and a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid was added thereto. I have.

When a catalyst is added to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water as described above, a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid is added. The start time of the hydrolysis reaction is controlled by the amount of the catalyst added, and FIG.
As shown in (1), by irradiating ultraviolet rays, the polymerization reaction of the photopolymerizable monomer is started by the action of the photoreaction initiation aid. 60 ° C. to 100 ° C. in parallel with the start of the polymerization reaction.
The hydrolysis reaction of the metal alkoxide is allowed to proceed by being left at a temperature of ° C. The amount of the metal alkoxide constituting the sol-gel solution determines the transmission characteristics of the optical fiber. Also, the photopolymerizable monomer constituting the polymerization reaction material determines the hardness of the core, and the core produced can be made harder by increasing the amount of the photopolymerizable monomer. The hardness of the core is adjusted by reducing.

Further, the amount of the photoreaction initiation aid constituting the polymerization reaction material depends on the amount of the photopolymerization monomer to be polymerized. If the amount of the photopolymerization monomer is large, it is necessary to add a relatively large amount. become. The amount of alcohol added to hydrolyze the metal alkoxide constituting the sol-gel solution is increased when the hydrolysis reaction of the metal alkoxide proceeds slowly. If you want to make it go faster, reduce the amount of alcohol added. further,
As with the alcohol, the amount of water constituting the sol-gel solution is relatively large when the alcohol is large, and is small when the alcohol is small. Further, the amount of the catalyst to be added is determined by the starting time for hydrolyzing the metal alkoxide.

The timing of irradiating the mixed solution 2 with ultraviolet rays indicates the timing of causing the photoreaction initiation aid added to the mixed solution 2 to act. The photopolymerization monomer starts the polymerization reaction by the action of the auxiliary material. Before starting the hydrolysis reaction, before the hydrolysis reaction of the metal alkoxide started, while mixing the metal alkoxide, the photopolymerization monomer and the photoreaction initiation auxiliary, after adding the alcohol and water first, It may be just after adding the catalyst. Further, the timing of irradiating the mixed solution 2 with ultraviolet rays may be simultaneous with the start of the hydrolysis reaction. Simultaneously with the start of the hydrolysis reaction means that the hydrolysis reaction of the metal alkoxide has started,
A sol-gel solution is formed by adding a catalyst to a sol-gel solution obtained by mixing a metal alkoxide, an alcohol and water, and a polymerization reaction material obtained by mixing a photopolymerization monomer and a photoreaction initiation aid. This is when the hydrolysis reaction of the metal alkoxide starts. Whether or not the hydrolysis reaction of the metal alkoxide constituting the sol-gel solution has started can be determined by checking the viscosity of the sol-gel solution. That is, a solution in which a polymerization reaction material in which a photopolymerization monomer and a photoreaction initiation auxiliary material are mixed in a sol-gel solution in which metal alkoxide, alcohol and water are mixed is a sol-like solution, and a catalyst is added. When the hydrolysis reaction of the metal alkoxide starts, the sol-like solution gels, so that the viscosity of the sol-gel solution changes. By looking at this viscosity, it can be determined whether or not the hydrolysis reaction of the metal alkoxide in the sol-gel solution has started.

As described above, it is important that the time when the mixed solution 2 is irradiated with the ultraviolet ray is before the start of the hydrolysis reaction or at the same time as the start of the hydrolysis reaction. After the hydrolysis reaction has occurred, even if the polymerization reaction is caused by irradiation with ultraviolet rays, the polymer cannot be dispersed and bonded in the-(Si-O)-network, resulting in a bias. When such a bias occurs, an organic material (polymer) having a large molecular weight is dispersed in a — (Si—O) — network, and the organic material (polymer) acts as a spring. However, it cannot be expected that cracks are prevented from occurring in response to volume shrinkage during vitrification after the hydrolysis reaction. In other words, irradiating the sol-gel solution with ultraviolet light before starting the hydrolysis reaction or simultaneously with the start of the hydrolysis reaction disperses the organic material (polymer) having a high molecular weight, and vitrifies the sol-gel solution after the hydrolysis reaction. When volume shrinkage occurs, the organic material (polymer) having a large molecular weight acts as a spring, and is necessary to prevent cracks from occurring in the core formed by vitrification.

The time of maintaining the temperature at 60 ° C. to 100 ° C. is when the hydrolysis of the metal alkoxide (silica) proceeds, and generally, the mixed solution 2 is irradiated with ultraviolet rays to assist the photoreaction. After the photopolymerization monomer starts the polymerization reaction by the action of the material and the polymerization reaction proceeds sufficiently,
This is to leave at a temperature of 00 ° C. This 60 ° C-10
The temperature of 0 ° C. is a temperature suitable for promoting the hydrolysis of the metal alkoxide (silica).

When the temperature is maintained at 60 ° C. to 100 ° C., the photopolymerizable monomer uniformly dispersed in the sol-gel solution starts the polymerization reaction by the action of the photoreaction initiation aid to form a molecular network. This is at the same time as the formation or after the formation of the molecular network. That is, 60 ° C.-1
Time when the temperature is kept at 00 ° C (time to start the hydrolysis reaction)
It is important that after the photopolymerizable monomer starts the polymerization reaction by the action of the photoreaction initiation aid. If the photopolymerizable monomer initiates the hydrolysis reaction before starting the polymerization reaction by the action of the photoreaction initiation aid,-(Si-O)- The polymer cannot be dispersed and bonded in the network, and the polymer is unbalanced. When the polymer is vitrified after the hydrolysis reaction, the core is cracked due to volume shrinkage. 60 ° C-10
The time at which the temperature is maintained at 0 ° C. may be the same as when the molecular network is formed. The formation of this molecular network is carried out by starting the hydrolysis reaction of the metal alkoxide by adding a catalyst.

An optical fiber cable can be formed by forming a clad layer on the core 4 thus formed. Also, by using a resin mold or tube (a plastic-based material having a refractive index lower than the refractive index of the mixed solution after drying) as a clad for the core mold 3, the mixing housed in the container 1 is obtained. The optical fiber cable is formed at the stage where the solution 2 is poured into the core mold 3 to form the core.

[0033]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, the organic / inorganic composite material can be used as a core to have flexibility suitable for the intended use, and transmission loss can be reduced.

According to the second aspect of the present invention, an organic / inorganic composite material can be used as a core to provide a small transmission loss and flexibility suitable for the intended use, thereby forming a core with a small transmission loss. be able to.

According to the third aspect of the present invention, the organic / inorganic composite material can be used as a core to provide a transmission characteristic with low transmission loss and flexibility suitable for the intended use, and to form a core with low transmission loss. be able to.

According to the present invention, an organic / inorganic composite material can be used as a core to provide an optical fiber having a small transmission loss and a flexibility suitable for a purpose of use and a small transmission loss. can do.

According to the fifth aspect of the present invention, an organic / inorganic composite material can be used as a core to provide an optical fiber having a small transmission loss and a flexibility suitable for the purpose of use, and a small transmission loss. can do.

According to the sixth aspect of the present invention, an organic / inorganic composite material is used as a core to provide an optical fiber with a small transmission loss and flexibility suitable for a purpose of use and a small transmission loss. can do.

According to the seventh aspect of the invention, the core made of the organic / inorganic composite material can be provided with flexibility suitable for the intended use without causing cracks in the core, and the transmission loss of the core can be reduced. Fewer optical fibers can be formed.

According to the eighth aspect of the present invention, the core made of the organic / inorganic composite material can be provided with flexibility suitable for the intended use without causing cracks in the core, and the transmission loss of the core can be reduced. Fewer optical fibers can be formed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a method for manufacturing an optical fiber according to the present invention.

[Explanation of symbols]

 1 …………………………………………………………………………… Mixed solution 3 ………………………………………………………………………………………………………………………………………… 4 ………core

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08F 2/48 C08F 2/48 290/06 290/06 F term (reference) 2H050 AA13 AB04X AB42X AB43X AC03 4J011 GA02 GB03 GB08 PA13 PA16 PA25 PA47 PA99 PB22 PC02 PC08 PC13 PC15 QA03 QB19 TA06 TA09 TA10 UA01 WA07 WA10 4J027 AE01 BA06 BA07 CA10 CA18 CA20 CA29 CA36 CB10 CC05 CD01

Claims (8)

[Claims] An inorganic material comprising a metal alkoxide,
An optical fiber, wherein a core is formed by mixing an organic material comprising an acrylic photopolymerizable monomer or an epoxy photopolymerizable monomer. 2. The optical fiber according to claim 1, wherein the metal alkoxide is ethyl silicate. 3. A core mold is prepared by mixing a sol-gel solution containing a metal alkoxide, an alcohol and water with a polymerization reaction material containing a photopolymerization monomer and a photoreaction initiation aid, and a catalyst. A method for producing an optical fiber, comprising: pouring, irradiating the poured solution with ultraviolet rays, and maintaining the temperature at 60 ° C. to 100 ° C. to form a core. 4. A clad comprising a sol-gel solution comprising a metal alkoxide, an alcohol and water, a polymerization reaction material comprising a photopolymerization monomer and a photoreaction initiation aid, and a catalyst-added mixed solution. Pour the mixture into a tube, and irradiate the mixed solution with ultraviolet rays at 60 ° C. to 100 ° C.
An optical fiber manufacturing method for manufacturing an optical fiber while maintaining the temperature. 5. The method according to claim 3, wherein the metal alkoxide is ethyl silicate. 6. The mixed solution is prepared by mixing a metal alkoxide with 1
0 to 50% by weight, 1 to 30% by weight of a photopolymerizable monomer, 15% by weight or less of a photoreaction initiation aid, and 0 to 60% of an alcohol.
6. The method for producing an optical fiber according to claim 3, wherein the optical fiber is blended in a ratio of 0% to 30% by weight, water, and 5% by weight or less. 7. The method for producing an optical fiber according to claim 3, wherein the time of irradiating the mixed solution with ultraviolet rays is before or at the same time as the start of the hydrolysis reaction. . 8. When the temperature is maintained at 60 ° C. to 100 ° C., the photopolymerizable monomer uniformly dispersed in the mixed solution starts a polymerization reaction by the action of a photoreaction initiation aid, 8. The method for producing an optical fiber according to claim 3, wherein the network is formed simultaneously with or after the formation of the molecular network.