JPH0894863A - Optical transmission tube - Google Patents

Abstract

PURPOSE: To obtain an optical transmission tube using a fluoro-rubber, which is prevented from the deterioration of optical transmission property as much as possible even in use for a long time, as a clad material by controlling the content of a residual halogen compound in a vulcanized fluoro-rubber to equal to or below a specific value. CONSTITUTION: The inner surface of the clad 1 at least in contact with a core 2 is formed from the vulcanized fluoro-rubber and in this case, a vulcanized fluoro-rubber containing <=80ppm, preferably <=30ppm and more preferably <=5ppm residual halogen compound expressed in terms of halogen atom is used as the vulcanized fluoro-rubber. The residual halogen compound is halogen molecule, HI, HBr and the like, exhibits atom, molecule, ion or a compound with another atom or molecule and is mainly in molecular state or hydrogenated state. Where, the whole clad can be formed out of the vulcanized fluoro-rubber or the clad can be made by forming the main body composed of another elastic body instead of the vulcanized fluoro-rubber and the vulcanized fluoro-rubber layer on the inner surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission tube using fluororubber as a clad material.

[0002]

2. Description of the Related Art Conventionally, an optical transmission tube including a transparent core and a clad having a refractive index lower than that of the core has been used for various optical transmission applications.

In this case, solid cores and liquid cores are known as cores, and various types of clads for coating the cores are selected according to the type of the core. According to the results of the examination, it was found that when a liquid core, particularly silicone oil is used as the core, it is effective that the inner surface of the clad which is in contact with the core is at least fluororubber from the viewpoint of swelling property.

However, when fluororubber is used as the clad, it is found that the optical transmission characteristics are deteriorated during long-term use. Therefore, it is possible to prevent the optical transmission characteristics from being deteriorated even after long-term use. A new solution problem arose.

The present invention has been made to solve the above problems, and provides an optical transmission tube using fluororubber as a clad material in which deterioration of optical transmission characteristics is prevented as much as possible even after long-term use. The purpose is to

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that an optical transmission tube using fluororubber as a clad material can transmit the optical transmission over time. It was found that the cause of the deterioration of the properties was that the coloring component in the clad was eluted into the core, and as a result of further studies to obtain a fluororubber clad with less coloring, the coloring of the fluororubber was It was found that it was significantly affected by the residual halogen compound of 1) and that it was effective to set the content of the residual halogen compound in the vulcanized fluororubber to 80 ppm or less as a halogen atom.

Particularly, when vulcanizing an unvulcanized fluororubber, peroxide vulcanization is preferable from the viewpoint of coloring, and when performing peroxide vulcanization, a fluororubber having a halogen atom in the molecule is used, Vulcanization proceeds by eliminating halogen atoms in the molecule by radicals from peroxide to form highly active radicals, and in this case iodine atoms are preferred as bromine atoms as halogen atoms in the molecule. However, in any case, the residual halogen compound remained in the fluororubber, and it was found that removal of this residual halogen compound is effective from the viewpoint of preventing coloration. in this case,
As the halogen atom in the molecule, as described above, the iodine atom is preferable to the bromine atom in terms of coloring, but the bromine atom is superior in terms of reactivity, and has a bromine atom in the molecule. By removing the residual bromine compound from the vulcanized fluororubber obtained by vulcanizing the fluororubber, the vulcanized fluororubber obtained by vulcanizing the fluororubber having an intramolecular bromine atom which is inferior in coloring is used for the optical transmission tube. It can be effectively used as a clad, and by using a vulcanized fluororubber having a content of residual halogen atoms of 80 ppm or less as described above, the optical transmission characteristics of the optical transmission tube are maintained for a long period of time.
The present inventors have completed the present invention by finding that an optical transmission tube in which coloring is prevented can be obtained.

Therefore, according to the present invention, in an optical transmission tube having a transparent core and a clad having a refractive index lower than that of the core, at least the inner surface of the clad in contact with the core has a residual halogen compound content of halogen. There is provided an optical transmission tube characterized by being formed from a vulcanized fluororubber having an atomic number of 80 ppm or less.

The present invention will be described in more detail below.
As shown in FIG. 1, the optical transmission tube of the present invention comprises a core 2 covered with a hollow tubular clad 1 (note that although 3a and 3b are sealing plugs, the core 2 is solid). However, in the present invention, at least the inner surface of the clad 1 in contact with the core is formed of vulcanized fluororubber, and in this case, the content of the residual halogen compound as the vulcanized fluororubber is A vulcanized fluororubber having a halogen atom content of 80 ppm or less, preferably 30 ppm or less, and more preferably 5 ppm or less is used. As the residual halogen compound, a halogen molecule,
There are HI, HBr, etc., and it shows an atom, a molecule, an ion, or a compound with another atom or molecule, but it is mainly in a molecular state or a hydrogenated state. The clad may be entirely formed of vulcanized fluororubber, or the clad main body may be formed of an elastic body other than vulcanized fluororubber, and the vulcanized fluororubber layer may be formed on the inner surface thereof.

Here, as the fluororubber, VD type fluorine such as vinylidene fluoride (VDF) -hexafluoropropylene (HFP) binary copolymer and VDF-HFP-tetrafluoroethylene (TFE) ternary copolymer are used. Examples thereof include rubber, propylene-tetrafluoroethylene-based fluororubber, tetrafluoroethylene-perfluoroalkylvinylether-based fluororubber, and thermoplastic fluororubber.

The optical transmission tube of the present invention uses the above-mentioned vulcanized fluororubber as the clad material. In this case, the method for crosslinking unvulcanized fluororubber is not particularly limited. In addition to radical cross-linking methods such as peroxide vulcanization and electron beam vulcanization, polyamine vulcanization and polyol vulcanization can be adopted, but the radical cross-linking method is preferable because of less coloring.

A typical example of the radical crosslinking method is a peroxide vulcanization method. When peroxide vulcanization is carried out, the peroxides include ketone peroxides, hydroperoxides and dialkyl peroxides. , Diacyl peroxides, peroxyesters and the like.

Specifically, 2,5-dimethylhexane-
2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,
Di-t-butyl peroxide, t-butyl cumyl peroxide, 2,2-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) octane, 1,1-bis (t -Butylperoxy) cyclohexane, t-butylperoxybenzate, benzoyl peroxide, lauroyl peroxide, 2,4-
Dichlorobenzoyl peroxide, 1,1-bis (t
-Butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) palerate, dicumyl peroxide, α,
Examples include α'-bis (t-butylperoxyisopropyl) benzene and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane. Among these, decomposition products are said to be less colored. From the point of view, peroxides having an aliphatic or alicyclic structure containing no aromatic ring, such as 2,5-dimethylhexane-2,5-dihydroperoxide and 2,5-dimethyl-2,5-di (t -Butylperoxy) hexyne-3, di-t-butylperoxide, 2,2-bis (t-butylperoxy) butane,
2,2-bis (t-butylperoxy) octane, 1,
1-bis (t-butylperoxy) cyclohexane, lauroyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
2,5-Dimethyl-2,5-di (t-butylperoxy) hexane is preferred.

The amount of the above-mentioned peroxide used is appropriately selected, but is preferably 0.1 to 10 parts, more preferably 0.5 to 100 parts by weight per 100 parts by weight of fluororubber (the same applies hereinafter).
5 parts, more preferably 2 to 4 parts. If the amount of peroxide is too small, vulcanization cannot be performed sufficiently and the rubber physical properties cannot be sufficiently expressed, and unvulcanized fluororubber is eluted into the core, which causes light scattering in the core and the formation of the core and the clad. Scattering at the interface deteriorates the optical transmission characteristics. In addition, the residual halogen in the fluororubber is released at a high temperature, deteriorating the light transmission characteristics. On the other hand, when the amount of peroxide is large, the compatibility between the fluororubber and the peroxide is generally poor, and therefore the peroxide aggregates and causes foaming during vulcanization. Therefore, the light scattering at the interface between the core and the clad becomes large, and especially in the case of a liquid core such as silicone oil, the liquid core penetrates into the rubber elastic body through the pinhole formed in the clad and swells it. There are cases in which In addition, since the peroxide decomposed products and unreacted products are increased, the optical characteristics are deteriorated.

Further, at the time of peroxide vulcanization, it is preferable to add a crosslinking aid in order to increase the crosslinking efficiency of the fluororubber. As the crosslinking aid, an acryloxy group-containing compound, a methacryloxy group-containing compound, or an aryl group-containing compound can be added. Acrylic acid or methacrylic acid derivatives such as esters thereof can be used as the compound provided for this purpose.

Examples of the alcohol residue of the ester include an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a dodecyl group, a stearyl group and a lauryl group, a cyclohexyl group, a tetrahydrofurfuryl group and an aminoethyl group. , 2-hydroxyethyl group, 3-hydroxypropyl group, 3-chloro-2-hydroxypropyl group and the like. Furthermore, esters with polyfunctional alcohols such as ethylene glycol, triethylene glycol, and polyethylene glycol can be similarly used.

As the aryl group-containing compound, diallyl phthalate, diallyl fumarate, diallyl maleate, triallyl isocyanurate and triallyl cyanurate are preferably used.

The amount of these used is preferably 0.1 to 20 parts, particularly 0.5 to 5 parts, per 100 parts of fluororubber.

Here, when performing peroxide vulcanization,
As the fluororubber, one having a halogen atom as a radical active site in its molecule is used. This is because the halogen atom in the molecule is desorbed by the radical from peroxide,
It becomes a highly active radical and vulcanization proceeds as shown in the following formula. In addition, as the position of the halogen atom, in the main chain,
It may be located at any of the side chain and the end of the main chain, but is particularly preferably at the end of the main chain.

[0020]

[Chemical 1]

As the halogen atom in the molecule, bromine is mainly used because of its high reactivity. However, according to the study by the present inventor, the fluororubber having a bromine atom in the molecule is often colored. Therefore, as the vulcanized fluororubber itself, those having an iodine atom in the molecule are suitable as the clad material from the viewpoint of less coloring, but in the present invention,
Since the residual halogen compound is removed by a method for removing the residual halogen compound as described below to reduce the coloring, the fluororubber having an intramolecular bromine atom can be effectively used.

Although the peroxide vulcanization conditions vary depending on the peroxide species, for example, Perhexa 25B
When (2,5-dimethyl-2,5-di (t-butylperoxy) hexane) is used, it is usually 140 to 160.
After primary vulcanization at 10 ° C. for 1 minute to 1 hour, secondary vulcanization is performed at 160 to 200 ° C. for 1 to 20 hours. For vulcanization, a press, an oven, an autoclave, or the like is used. In the case of an oven or an autoclave, in order to prevent crosslinking inhibition by oxygen, replacement with an inert gas such as N ₂ or steam,
Vacuuming or the like is needed as appropriate. Regarding the vulcanization temperature and time, if the temperature is too low or the time is too short, not only the vulcanization of the rubber may not proceed sufficiently, but also the adhesion may be insufficient. Decomposition or adhesion of rubber (especially when silane coupling agent is used)
May be seen.

In the case of electron beam vulcanization, a radical is generated by an electron beam without using the above-mentioned peroxide, and triallyl isocyanurate (TAIC), α-TMPT,
Crosslinked using TMPT etc., in this case 0.5
The irradiation dose is preferably -20 Mrad, more preferably 2-10 Mrad, and is preferably carried out in an atmosphere of an inert gas such as nitrogen gas. The amount of the crosslinking aid used is the same as above.

Also in the case of electron beam vulcanization, the unvulcanized fluororubber to be used is preferably one having a bromine atom, an iodine atom or a chlorine atom in the molecule, particularly at the terminal, in terms of less coloring.

As the clad material in the optical transmission tube of the present invention, a vulcanized fluororubber having a residual halogen compound content of 80 ppm or less as a halogen atom is used as described above. It is effective to remove the residual halogen compound in the vulcanized fluororubber by employing a method of washing the vulcanized fluororubber with a solvent, a method of subjecting it to heat treatment, a method of subjecting it to a reduced pressure treatment, or the like.

Here, as a method for cleaning the vulcanized fluororubber with a solvent, a solvent which dissolves a halogen compound such as iodine or bromine and does not attack the fluororubber, for example, a lower alcohol, a ketone, an aromatic hydrocarbon, Examples of the method include washing with one or a mixture of two or more kinds of water, a fluorine-based solvent, silicone, a petroleum-based solvent, a phosphoric acid ester-based solvent, preferably ethanol or water. As the cleaning method, a method of dipping treatment, a method of steaming in steam (steam stripping), or the like can be adopted.

In order to promote the sublimation and evaporation of halogen molecules, a method of heat treatment at a high temperature, preferably above the melting point of the halogen molecules is also effective, and the halogen molecules can be depressurized or vacuumed using a vacuum oven or the like. The method of removing is also suitable.

In this case, the solvent washing treatment, the heat treatment and the depressurization treatment may be carried out individually or in combination. For example, the heat treatment and the depressurization treatment can be carried out simultaneously in parallel.

In the present invention, the vulcanized fluororubber has a residual halogen compound content of 80 as a halogen atom.
The content of the residual halogen compound is ppm or less, and means the value measured by the following method.

Crosslinked rubber containing the above-mentioned peroxide or containing peroxide and a crosslinking aid (including electron beam crosslinked products)
Is free-distilled with alcohol (in particular, methanol is suitable in this case) (with a trap of AgNO ₃ solution) to extract free halogen, and an aqueous solution of AgNO ₃ is added thereto to precipitate the free halogen as silver halide (AgX). Then, the amount of AgX is determined by filtration and weighing (including high-temperature drying) (precipitate is washed with water and then with methanol and methyl ethyl ketone to remove impurities such as unreacted AgNO ₃ and dissolved fluororubber, etc., and high purity. belongs to).

Further, the halogen species (species X) of silver halide (AgX) are determined by XMA (X-ray microanalysis), converted into the amount of halogen, and the content in the sample is determined by the following formula. Is. The halogen X here mainly targets Br, iodine, and chlorine, but can be applied to other halogens.

[0032]

[Equation 1]

In the present invention, when the clad is composed of a rubber elastic body and a vulcanized fluoro rubber formed inside thereof, examples of the rubber elastic body include dimethyl silicone rubber, methylphenyl silicone rubber, fluorosilicone rubber and the like. Butyl rubbers such as silicone rubbers, butyl rubbers, halogenated butyl rubbers and saturated butyl rubbers, EP
DM, acrylic rubber, nitrile rubber, SBS, SE
Although thermoplastic elastomers such as BS and SIS are used, and these can have a single layer structure or a multilayer structure of two or more layers, silicone rubber type, butyl rubber type, EP
DM-based vulcanized rubber is preferable, and thermoplastic elastomer is also preferable. Among these, silicone rubbers are preferably used from the viewpoint of heat resistance and the like, and butyl rubbers and EPDMs are preferably used from the viewpoint of gas barrier properties against water vapor and the like.

In the optical transmission tube of the present invention, the core material is not particularly limited, and a solid, liquid or fluid transparent material having a higher refractive index than the clad material is used.

In this case, as the solid transparent material, acrylic resins and methacrylic resins are preferably used, and examples thereof include alkyl acrylates such as methyl acrylate and methyl methacrylate, homopolymers and copolymers of alkyl methacrylates, and monomers thereof and co-polymers thereof. The thing which copolymerized other acrylate and methacrylate which can obtain a transparent polymer which can be polymerized can be mentioned. Specific examples of the liquid or fluid transparent material include aqueous solutions of inorganic salts, polyhydric alcohols such as ethylene glycol and glycerin, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane, polyethers, polyesters, and liquid paraffin. Hydrocarbons, etc.
Halogenated hydrocarbon such as trifluorochloroethylene oil,
Examples thereof include phosphoric acid esters such as tris (chloroethyl) phosphate and trioctylphosphate, and polymer solutions prepared by diluting the polymer with a suitable solvent.

Of these, liquid or fluid core materials, especially silicone oil, are effective for the purpose of the present invention.

The sealing plug may be used even if the core material is solid, but it is necessary especially when the core material is liquid or fluid, and in this case, as a light window material. When operating, the material forming the sealing plug needs to be transparent, and specific examples of the material of the sealing plug include inorganic materials such as quartz glass, Pyrex glass, multi-component glass, sapphire, and quartz. Glass, polyethylene, polypropylene, ABS resin, acrylonitrile
Styrene copolymer resin, styrene-butadiene copolymer,
Acrylonitrile / EPDM / styrene terpolymer,
Styrene / methyl methacrylate copolymer, (meth) acrylic resin, epoxy resin, polymethylpentene, allyl diglycol carbonate resin, spirane resin, amorphous polyolefin, polycarbonate, polyamide, polyarylate, polysulfone, polyallylsulfone, polyethersulfone Examples thereof include organic glass and plastic transparent materials such as phone, polyether imide, polyimide, polyethylene terephthalate, diallyl phthalate, fluororesin, polyester carbonate, and silicone resin. Among these, quartz glass, Pyrex glass, inorganic glass such as multi-component glass is not only transparent, but also excellent in heat resistance, and also chemically stable,
It does not chemically react with the core that comes into contact with its inner end surface and the gas or moisture that comes into contact with its outer end surface, and it is possible to provide excellent performance over a long period of time.

Here, it is preferable to use a window material (sealing plug) having a refractive index substantially equal to that of the core. In addition, it is preferable to provide an antireflection film for at least the light wavelength range to be transmitted on the end surface of the window material (sealing plug) on the light incident side. Further, when the incident light contains ultraviolet rays or infrared rays, an ultraviolet ray and / or infrared ray cut film is optionally provided in a window material (sealing material) in order to prevent deterioration of the core due to ultraviolet rays and to prevent temperature rise due to infrared rays. It can be provided on the incident end face of the stopper. Window material (sealing stopper)
You may use what has itself UV and / or IR absorptivity.

If transparency is not required, metal or ceramics can be used.

Although not shown, when the cladding end is sealed with a sealing plug, heat shrinkage treatment, adhesive treatment, hose band fastening, winding with wire wire, fixing with shape memory alloy, sleeve, O -Mechanical fastening, such as fastening via rings or packing, can be carried out as required. Among them, stainless steel, aluminum, copper, copper alloys such as brass, steel, T
It is preferable that a metal sleeve made of i, Ni, or the like is fitted to the outer peripheral portion of the clad so as to cover the clad, and the sealing plug is fixed to the clad by a caulking method of compressively deforming the sleeve.

In the present invention, if necessary, the clad may be coated with an appropriate coating material for the purpose of protecting the optical transmission tube. The coating material can be selected from plastic, elastomer, metal, glass, and inorganic material.

Specifically, polyamide, epoxy resin,
Polymers such as polyvinyl chloride, polycarbonate, polystyrene, fluororesin, butyl rubber, halogenated butyl rubber, polyethylene, polypropylene, polyurethane, hydrochloric acid rubber, natural rubber, polyisoprene rubber, polybutadiene rubber, chloroprene rubber, acrylic rubber, EPDM, fluororubber The material can be coated, extruded, wrapped with a tape-shaped material, heat-shrinked or the like to cover the clad.

Further, metal materials such as SUS, aluminum, copper, iron, etc., or the above polymeric materials are pipe-shaped, bellows-shaped,
You may insert the clad which coat | covered the core in what was shape | molded in the shape of a spiral wire. Furthermore, the metal film can be coated by plating a metal material on the outer periphery of the clad by plating, vapor deposition, sputtering, or the like.

These coating materials can be used alone or as a composite with other materials.

The above-mentioned coating material can be provided not only for protecting the light transmission tube but also for the purpose of blocking light or causing only the required portion to emit light. For example, when a hole is formed in a required portion of the above covering material or the portion is made transparent, light leaks out from the portion to form a large number of spot-shaped or line-shaped light emitters.

[0046]

EXAMPLES The present invention will be specifically described below by showing experimental examples and examples, but the present invention is not limited to the following examples.

[Experimental Example] As a fluororubber, a VDF-HFP binary copolymer having an iodine atom at the end (Daiel G901) and a VDF-HFP having a bromine atom at the end are used.
Binary copolymer (Viton VTR7085) is used, and 100 parts thereof are blended with 1.5 parts of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 4 parts of triallyl isocyanurate. Then, the mixture was kneaded to prepare a fluororubber composition.

This rubber composition was molded into a sheet having a thickness of 1 mm, press-vulcanized at 160 ° C. for 30 minutes as primary vulcanization, and then peroxide-vulcanized at 180 ° C. for 5 hours in an oven as secondary vulcanization. Sulfurized.

Next, the vulcanized rubber was treated under the following conditions. The ethanol washed vulcanized rubber was immersed in ethanol and immersed at 20 ° C. for 100 hours. Heated and depressurized vulcanized rubber is put in a vacuum oven and heated at 140 ° C, 10 Tor
It was treated with r for 10 hours.

The residual halogen atom content and the transmittance at wavelengths of 400 nm and 500 nm of the untreated and the above-mentioned treated vulcanized rubber were measured. The results are shown in Table 1. The residual halogen atom content was measured by the above method.

[0051]

[Table 1]

Example 1 Experiment No. Using the fluororubber composition of No. 1, this was molded into a tube having an inner diameter of 10 mm, an outer diameter of 12 mm and a length of 2 m, and vulcanized.

This tube was filled with silicone oil, and a Pyrex glass sealing plug (diameter: 10 m) at both ends.
m × length 20 mm) was attached to prepare an optical transmission tube.

Example 2 Experiment No. Using the fluororubber composition of No. 4, this was molded into a tube shape having an inner diameter of 10 mm, an outer diameter of 12 mm and a length of 2 m, and vulcanized.

This tube was filled with silicone oil, and both ends were sealed with Pyrex glass (diameter: 10 m).
m × length 20 mm) was attached to prepare an optical transmission tube.

The optical transmission tube obtained above had good optical transmission characteristics for a long period without the core being substantially colored.

[0057]

The optical transmission tube of the present invention is capable of preventing the deterioration of the optical transmission characteristics even if it is used for a long period of time.

[Brief description of drawings]

FIG. 1 is a partially omitted sectional view showing an example of a light transmission tube of the present invention.

[Explanation of symbols]

 1 clad 2 core 3a, 3b sealing plug

Claims (2)

[Claims] 1. An optical transmission tube comprising a transparent core (2) and a cladding (1) having a refractive index lower than that of the core (2), wherein at least the inner surface of the cladding (1) in contact with the core is An optical transmission tube comprising a vulcanized fluororubber having a residual halogen compound content of 80 ppm or less as a halogen atom. 2. A vulcanized fluororubber is subjected to solvent cleaning, heat treatment and reduced pressure treatment alone or in combination thereof,
The content of the residual halogen compound is 80 as a halogen atom.
The optical transmission tube according to claim 1, wherein the optical transmission tube has a ppm or less.