JPH0894861A - 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, as a clad material by using the fluoro-rubber cross-linked by radical reaction. CONSTITUTION: The inner surface of the clad 1 at least in contact with a core 2 is formed out of the fluoro-rubber and in this case. the fluoro-rubber cross- linked by radical reaction is used. The cause of the deterioration of optical transmission property of the optical transmission tube using a fluoro-rubber as the clad material with the lapse of time is the elusion of a coloring component in the clad material to the core and the fluoro-rubber vulcanized by peroxide is small in coloring and is suitable for the clad material of the optical transmission tube. And in electron beam vulcanization, a reaction by-products are further small. When the fluoro-rubber cross-linked by the radical reaction is used for the clad material, the optical transmission property of the optical transmission tube is kept over a long time and the optical transmission tube small in coloring is obtained.

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. We found that the reason for 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 little coloration, the fluororubber crosslinked by the radical reaction was found. Was found to be the most suitable clad material.

That is, the vulcanization method of fluororubber includes polyamine vulcanization and polyol vulcanization, as well as radical reaction vulcanization such as peroxide vulcanization and electron beam vulcanization. In polyamine vulcanization, by-products generated during vulcanization or the vulcanizing agent itself are highly colored, and this colored component is eluted into the core to color transmitted light, whereas peroxide vulcanization is less colored. Therefore, it is suitable as a clad material for optical transmission tubes. In the case of electron beam vulcanization, radicals are generated by an electron beam and crosslinked with triallyl isocyanurate (TAIC), etc. When the amount of material is even less and the fluororubber cross-linked by such radical reaction is used as the clad, the light transmission characteristics of the light transmission tube are maintained for a long period of time, and light with little coloring is retained. A delivery tube can be obtained, and in this case, as an unvulcanized fluororubber that is radically crosslinked, a fluororubber having an iodine atom in the molecule is more effective because it is less colored when crosslinked. Based on the above findings, the present invention has been completed.

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 is made of a fluororubber cross-linked by a radical reaction. Provided is a light transmission tube characterized by being formed, and a light transmission tube in which a fluororubber crosslinked by a radical reaction has an iodine atom in its molecule.

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 fluororubber, and in this case, the fluororubber crosslinked by a radical reaction is used. Is. 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 fluororubber as its cladding material, and when it is crosslinked to form a cladding, it is crosslinked by radical crosslinking.

In this case, examples of the radical crosslinking method include peroxide vulcanization, electron beam vulcanization, and photocrosslinking.

When peroxide vulcanization is performed, examples of the peroxide include ketone peroxides, hydroperoxides, 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 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.

In addition, in the 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.

[0021]

[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, even if the reactivity is somewhat low, those having an iodine or chlorine atom in the molecule are suitable as the clad material from the viewpoint of less coloring, and from this point, the fluororubber clad of the present invention by radical crosslinking is suitable. It is preferable to use a radical-crosslinked fluororubber having an iodine or chlorine atom in the molecule.

The peroxide vulcanization conditions vary depending on the peroxide species, but 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.

In the present invention, when the clad is composed of a rubber elastic body and a vulcanized fluororubber 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. For example, alkyl acrylates such as methyl acrylate and methyl methacrylate, homopolymers and copolymers of alkyl methacrylates, these monomers and their copolymers are used. 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 strands, 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-mentioned polymer 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.

[0039]

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 1] As a fluororubber, a VDF-HFP binary copolymer having an iodine atom at the end (Dayer G801) and a VDF-HF having a bromine atom at the end were used.
P binary copolymer (Viton VTR7085) was used, and 100 parts of it were added with 0.75 parts of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2 parts of triallyl isocyanurate. The ingredients were blended and kneaded to prepare a fluororubber composition.

This rubber composition was molded into a sheet having a thickness of 1 mm and press-vulcanized at 160 ° C. for 30 minutes. Next, the transmittance of the vulcanized rubber was measured at a wavelength of 400 nm.

For comparison, VDF-H was used as fluororubber.
FP binary copolymer (Daiel G201, DAIEL G70
4) was used to carry out polyamine vulcanization and polyol vulcanization, respectively. Table 1 shows the above results.

[0043]

[Table 1]

[Experimental Example 2] V having an iodine atom at the terminal
Using 100 parts of DF-HFP binary copolymer as fluororubber, the amount of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was set as shown in Table 2, and triallyl isocyanurate 2 was used. Parts were mixed and kneaded to prepare a fluororubber composition.

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

Next, the transmittance of the vulcanized rubber is set to 500 nm.
Was measured at the wavelength of. The above results are shown in Table 2.

[0047]

[Table 2]

Example 1 Experiment No. Using the fluororubber composition of No. 8, this was molded into a tube having an inner diameter of 10 mm, an outer diameter of 11 mm and a length of 1,000 mm, and was placed in an N ₂ -substituted oven at 160 ° C. for 30 minutes and then at 180 ° C. for 5 hours. It was vulcanized under the conditions.

This tube was filled with silicone oil, and sealing plugs made of Pyrex glass were attached to both ends to prepare an optical transmission tube.

[Example 2] Experiment No. 2 except that no peroxide was added. A fluororubber composition having the same composition as that of No. 1 was used, and the irradiation dose was 20 Mr at a pressurizing voltage of 750 KV
An optical transmission tube was obtained in the same manner as in Example 1 except that vulcanization was performed under the ad condition.

The optical transmission tube obtained above had good optical transmission characteristics for a long period of time without substantially coloring the core.

[0052]

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 (3)

[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 a radical. An optical transmission tube characterized by being formed from fluororubber crosslinked by a reaction. 2. The light transmission tube according to claim 1, wherein the fluororubber crosslinked by a radical reaction has an iodine atom in its molecule. 3. Crosslinking by radical reaction is peroxide vulcanization, and is 0.1 per 100 parts by weight of fluororubber.
The optical transmission tube according to claim 1 or 2, wherein -10 parts by weight of a peroxide having an aliphatic or alicyclic structure is used for vulcanization.