JP2008197239A - Method for manufacturing polyvinyl chloride resin based optical transmission body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a polyvinyl chloride resin based optical transmission body which can be formed optimal in refractivity distribution with improved productivity. <P>SOLUTION: This manufacturing method includes a step of heat treating a polyvinyl chloride-based resin optical transmission body of a coaxial bilayer structure composed of an inner layer made of a polyvinyl chloride resin and one or more sorts of transparent and diffusible additives higher than this resin in refractivity with a Tg of 60-110°C, and an outer layer made of a polyvinyl chloride resin and one or more sorts of transparent and diffusible additives lower than this resin in refractivity with a Tg of 80-130°C and whose Tg is higher by 20°C than that of the inner layer to diffuse the above additive to the outer or center areas of the optical transmission body, and forming an area continuously changing its refractivity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a polyvinyl chloride resin optical transmission body, and more particularly to a method for manufacturing a polyvinyl chloride resin optical transmission body having a refractive index distribution.

A plastic graded-index optical transmission body having a region in which the refractive index continuously changes from the center of the linear body or rod-shaped body toward the outer periphery has already been proposed and put into practical use.
Various methods for manufacturing such an optical transmission body have been proposed (see, for example, Patent Documents 1 and 2).

  In the method of Patent Document 1, a polymer solution containing a non-polymerizable compound having a high refractive index is filled in a hollow of a polymer hollow tube prepared in advance. , Polymerizing the non-polymerizable compound having a high refractive index in the filled polymerizable solution while promoting diffusion to the central part to obtain a rod-shaped preform, and then melting it to a desired diameter. A batch polymerization process of stretching is adopted.

Further, the method of Patent Document 2 includes a first material made of a transparent polymer melt, a transparent non-polymerizable material having a refractive index different from that of the polymer, or a refractive index of the first material. A transparent and diffusible non-polymerizable material different from the polymer and at least one material including a melt of the polymer, the first material and the at least one material flow concentrically with each other. The diffusible material is diffused in the radial direction of the flow for a predetermined time. By this method, a plastic optical transmission body having a refractive index distribution can be manufactured.
Japanese Patent No. 3333292 Japanese Patent No. 3471015

  In order to transmit a large amount of information using an optical transmitter, it is necessary to keep mode dispersion low, but in general, the refractive index distribution shape of the optical transmitter is close to a “parabolic shape” expressed by Expression (1). It is known that mode dispersion is minimized when it is in shape.

Here, r is the position from the core center, n (r) is the refractive index at the position r, n ₁ is the refractive index of the core center, n ₂ is the refractive index of the cladding (or the outermost periphery of the core), and a is the core The radius, g, is a refractive index distribution coefficient, and the optimum value is 2-3 depending on the material.

Although the method of patent document 1 has the advantage that it is easy to form an optimal refractive index distribution shape, there exists a subject that it is inferior to productivity in order to employ | adopt a batch polymerization process.
In addition, the method of Patent Document 2 has improved productivity, but has a problem that the refractive index distribution shape around the core tails and deviates from the optimum refractive index distribution shape.

  The present invention has been made in view of the above problems, and provides a method for manufacturing an optical transmission body made of a polyvinyl chloride resin, which can easily form an optimum refractive index profile and can improve production efficiency. With the goal.

  The method for producing an optical transmission body made of a polyvinyl chloride resin according to the present invention comprises a polyvinyl chloride resin and one or more additives that have a refractive index higher than that of the polyvinyl chloride resin and are transparent and diffusible. An inner layer configured to include a polyvinyl chloride resin, and a refractive index lower than that of the polyvinyl chloride resin and including or not including one or more additives that are transparent and diffusible. It consists of an outer peripheral layer, the glass transition temperature of the inner layer is 60 to 110 ° C., the glass transition temperature of the outer peripheral layer is 80 to 130 ° C., and the glass transition temperature of the outer peripheral layer is 20 ° C. or higher than that of the inner layer. The polyvinyl chloride resin optical transmission body having a coaxial two-layer structure is heat-treated, and the additive is diffused toward the periphery or the center of the polyvinyl chloride resin optical transmission body. Including forming a changing region And features.

  Further, the transparent and diffusible additive contained in the inner layer is one or more compounds selected from the group consisting of sulfur compounds, and the transparent and diffusible additive contained in the outer peripheral layer is trimellitic acid. One or more compounds selected from the group consisting of esters and dipentaerythresters are preferred.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to manufacture the optical transmission body which has the optimal refractive index distribution shape for mass information transmission with high manufacturing efficiency.

  The method for producing an optical transmission body made of a polyvinyl chloride resin according to the present invention generally comprises a polyvinyl chloride resin and one or more additives that are transparent and diffusible, unlike the polyvinyl chloride resin. Hereinafter, the kind and / or composition of the diffusible additive used for the optical transmission body made of a polyvinyl chloride resin, which is simply comprised of “a diffusible additive” may be selected. In this method, the refractive index distribution shape is controlled to be a desired one.

  The polyvinyl chloride resin of the present invention is a (co) polymer obtained by polymerizing or copolymerizing a vinyl chloride monomer and / or a monomer copolymerizable with vinyl chloride, or a chlorinated product thereafter.

Monomers copolymerizable with vinyl chloride include all known vinyl monomers, for example, α-olefins such as ethylene, propylene and butylene: vinyl esters such as vinyl acetate and vinyl propionate: ethyl vinyl ether, Vinyl ethers such as butyl vinyl ether: (meth) acrylic acid esters such as methyl (meth) acrylate, butyl (meth) acrylate, and hydroxyethyl (meth) acrylate. These may be used alone or in combination of two or more. The polyvinyl chloride resin is not limited to those described above, and is described in, for example, JP 2005-36195 A, JP 2005-36196 A, JP 2005-36216 A, and the like of the same applicant. In addition, the described method and the method formed according to the method can be used. Further, it is effective to use a zirconium compound, an aluminum compound, an alkyl lithium, etc. as a catalyst in that case.
The refractive index of the polyvinyl chloride resin is not particularly limited, but is usually about 1.52 to 1.57.

  In the present invention, the polyvinyl chloride-based resin is preferably a post-chlorinated product from the viewpoint of low dehydrochlorination property and improved transparency. A chlorinated product obtained by the conversion method is preferred. A polyvinyl chloride resin having a chlorine content of 62% or more and 73% or less is preferred. Thereby, light scattering due to the presence of aggregates and crystal structures of polymer particles is small, and transparency can be improved.

  As the diffusible additive of the present invention, the transmittance of light having a wavelength of 650 nm, 780 nm or the like is 90% or more, preferably 93% or more, and has the property of being able to diffuse into the polyvinyl chloride resin used at the same time. It is most important to have such a material, and any material may be used as long as the refractive index is different from that of the polyvinyl chloride resin.

  Examples of the diffusible additive having a refractive index higher than that of the polyvinyl chloride resin include diphenyl sulfone and sulfur compounds such as diphenyl sulfone, diphenyl sulfide, and diphenyl sulfoxide. Examples of diphenylsulfone chloride include 4,4'-dichlorodiphenylsulfone, 3,3 ', 4,4'-tetrachlorodiphenylsulfone, and the like. Moreover, triphenyl phosphate is also mentioned. Their refractive index is 1.6 or more.

  Examples of the diffusible additive having a refractive index lower than that of the polyvinyl chloride resin include adipic acid esters such as di-2-ethylhexyl adipate, dibutyl adipate, diisodecyl adipate; di-2-ethylhexyl azelate, Azelaic acid esters such as diisooctyl azelaic acid; sebacic acid esters such as di-2-ethylhexyl sebacate and dibutyl sebacate; oligomers having a basic structure obtained by polycondensation of dibasic acid and glycol can be used. Examples of the dibasic acid include sebacic acid, azelaic acid, adipic acid, and phthalic acid. Examples of the glycol include propylene glycol, ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, hexanediol and the like.

In addition, phthalic acid esters (particularly alkyl esters) such as dimethyl phthalate, di-2-ethylhexyl phthalate, diisodecyl phthalate, isotridecyl phthalate; pyromellitic esters (particularly alkyl esters) such as pyromellitic octyl ester An ester obtained by esterification reaction of trimellitic acid and alcohol, that is, the following formula (I)

(In the formula, R1 to R3 are the same or different and each represents an alkyl group.)
Trimellitic acid ester represented by the following formula (II) such as UL-6 manufactured by Asahi Denka

(In the formula, R ⁴ represents an arbitrary functional group, and x represents an integer of 1 to 4.)
Dipentaerystol ester represented by the following may be used.

Here, the alkyl groups of R ^{1 to} R ³ may be different from each other, but it is preferable that three are the same. Further, an alkyl group having 1 to 12 carbon atoms, and more preferably 4 to 10 carbon atoms is preferable.
Examples of R ⁴ include lower alkyl groups having 1 to 6 carbon atoms (methyl, ethyl, propyl, n-butyl, t-butyl, etc.), aryl groups (phenyl, tolyl, xylyl, biphenyl, etc.),

Etc. are exemplified. Incidentally, the substituent R ^4, when x is 2 to 4 can be a divalent to tetravalent substituent in accordance with the number. Specifically, a compound in which x is 2 and R ⁴ is — (CH ₂ ) ₄ — is exemplified.

Examples of trimellitic acid esters include trialkyl trimellitic acid such as tributyl trimellitic acid, tri-2-ethylhexyl trimellitic acid, tri-n-octyl trimellitic acid, triisononyl trimellitic acid, and triisodecyl trimellitic acid. . Moreover, the ester of trimellitic acid and multiple types of alcohol may be sufficient. Of these, tri-2-ethylhexyl trimellitic acid and triisodecyl trimellitic acid are preferable.
The refractive index of these diffusible additives is 1.5 or less.

  In particular, from the viewpoint of imparting high transparency to a polyvinyl chloride resin, sulfur compounds (particularly diphenylsulfone and diphenylsulfone chloride) are used as high refractive index additives, and trimellitic acid is used as a low refractive index additive. Esters and dipentaerystol esters are preferred.

  The blending amount of these transparent and diffusible additives is not particularly limited. Depending on the type of polyvinyl chloride resin to be used, the type of additive to be used, etc., the high refractive index additive is 10% with respect to the total inner layer weight. -30% by weight, preferably 0-20% by weight of low refractive index additive with respect to the entire outer peripheral layer, 10-25% by weight of high refractive index additive, 0-15% by weight of low refractive index additive % Is more preferable.

  The glass transition temperature of the outer layer before diffusion of the diffusible additive of the present invention (that is, the mixture of the polyvinyl chloride resin and the additive forming the outer layer) is that of the inner layer (that is, the inner layer is formed). 20 ° C. or higher than a mixture of a polyvinyl chloride resin and an additive). By setting the difference in glass transition temperature between the outer layer and the inner layer to 20 ° C. or more, it is possible to prevent the diffusion of the diffusible additive in the outer layer from proceeding more than necessary, and tailor the refractive index profile at the core periphery. The optimum refractive index distribution shape can be obtained without doing so.

  The glass transition temperature of the outer peripheral layer and the inner layer indicates the peak temperature of the loss elastic modulus E ″ at 10 Hz when the temperature is raised from 0 ° C. to 150 ° C. at 3 ° C./min using a viscoelastic spectrometer.

  By setting the glass transition temperature of the outer peripheral layer before diffusing the diffusible additive to 80 ° C. or higher, it is possible to prevent the diffusion of the diffusible additive in the outer peripheral layer from progressing more than necessary, and The optimum refractive index distribution shape can be obtained without tailing the refractive index distribution shape. Moreover, the workability of a polyvinyl chloride resin can be made favorable by setting it as the glass transition temperature of 130 degrees C or less.

  The glass transition temperature of the inner layer before diffusing the diffusible additive is preferably 60 ° C. or higher. By setting the temperature to 60 ° C. or higher, the re-diffusion of the diffusible additive is prevented during use of the optical transmission member produced in the present invention, and the refractive index distribution shape deviates from the optimal refractive index distribution shape over time. Can be prevented. Further, the increase in plasticity can be prevented and the mechanical strength and shape necessary for use can be ensured. The glass transition temperature of the outer layer before diffusion of the diffusible additive is 130 ° C. or less, and the difference in glass transition temperature between the outer layer and the inner layer is 20 ° C. or more. It is suitable that the temperature is not higher than ° C.

  The method for producing the optical transmission body made of the polyvinyl chloride resin having the coaxial two-layer structure of the present invention is not particularly limited, and various methods known in the art can be used. For example, two types of mixtures containing a transparent resin and a diffusible additive are prepared, a method of spinning these two layers coaxially, a method of extrusion molding two layers coaxially, and melt spinning a preform formed by coaxial two-layer extrusion And the like.

  Such an optical transmission body made of a polyvinyl chloride resin can be adjusted by adjusting the diffusion time, temperature, etc., thereby adjusting the spread of the region where the refractive index continuously changes. The shorter the diffusion time or the lower the temperature, the narrower the region where the refractive index continuously changes, and a relatively steep refractive index gradient can be provided. If the diffusion time is increased or the temperature is increased, the region is expanded and a relatively gentle refractive index gradient can be realized.

The temperature at this time is preferably 200 ° C. or lower in order to avoid a decrease in fiber performance due to deterioration of the resin. Further, in order to increase the diffusion rate and improve the production efficiency, it is preferably 30 ° C. higher than the glass transition temperature of the outer peripheral layer before the diffusible additive is diffused.
The treatment time is not particularly limited. For example, in the case of the above-described temperature, about 30 seconds to 1 hour, and further about 1 minute to 30 minutes are suitable.

  The method of heat-treating the optical transmission body made of the polyvinyl chloride resin having the coaxial two-layer structure of the present invention is not particularly limited. For example, the temperature of the reel is controlled while the optical transmission body is wound around a metal reel. Examples include a method of installing in a possible tank, maintaining at a predetermined temperature for a predetermined time, and then taking out the optical transmission body, a method of passing through a diffusion tube at a predetermined temperature following the coaxial two-layer extrusion molding at a predetermined speed, etc. It is done.

  The light transmission body made of the polyvinyl chloride resin of the present invention has a range that does not impair the characteristics of the polyvinyl chloride resin, for example, acid resistance, alkali resistance, water resistance, electrical insulation, flame resistance, mechanical strength, etc. If necessary, a compounding agent known in the art, for example, a heat stabilizer, a heat stabilization aid, a lubricant, a processing aid, a heat resistance improver, an antioxidant, a light stabilizer and the like may be blended. Good. A compounding agent can be used individually or in combination of 2 or more types.

  Examples of the heat stabilizer include organic tin stabilizers such as dimethyltin mercapto, lead stearate, dibasic lead phosphite and the like. Examples of the stabilizing aid include epoxidized soybean oil. Examples of the lubricant include an internal lubricant and an external lubricant. Examples of the internal lubricant include lauryl alcohol, and examples of the external lubricant include montanic acid wax. Examples of the processing aid include acrylic processing aids which are alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2,000,000. Specific examples include n-butyl acrylate-methyl methacrylate copolymer. Examples thereof include heat improvers such as coalescence. Examples of the antioxidant include phenolic antioxidants. Examples of the light stabilizer include hindered amine light stabilizers.

In the optical transmission body of the present invention, the region where the diffusible additive is diffused becomes the core layer. Further, an undiffused region that maintains the composition before the additive is diffused in the outer peripheral layer can be formed to be a cladding layer (inner cladding in a double-clad structure optical transmission body).
The optical transmission body of the present invention has a double clad structure covered with a layer made of another material having a refractive index lower than that of the outer peripheral layer before diffusing the diffusible additive (hereinafter sometimes referred to as “outer clad”). Then, since a bending loss is reduced, it is preferable. Other materials having a low refractive index include polyvinyl chloride resins, polymethacrylic resins having a lower refractive index and / or a higher amount of additive than the additive added to the outer peripheral layer before diffusing additive is diffused. Methyl acid and polyvinylidene fluoride are preferred because of their good adhesion to polyvinyl chloride resins.

  The optical transmission body of the present invention includes a core layer made of a material having a high refractive index and a clad layer made of a material having a lower refractive index. Since both additives in the inner layer containing an additive having a refractive index higher than that of the polyvinyl chloride resin and the outer layer containing an additive having an arbitrarily low refractive index move relative to each other, a part of the inner layer and the outer layer Is the core layer, and the outer peripheral layer is the cladding layer. The clad layer may have a laminated structure, for example, a double clad layer structure. In this case, the outer peripheral layer may be an inner clad, and an outer clad layer made of a material having a refractive index equivalent to the outer peripheral layer / a refractive index lower than that of the outer peripheral layer may be formed. By forming the outer cladding, bending loss can be reduced. The outer clad layer may be formed by surrounding the outer peripheral layer with a material in which the additive is not diffused in the outer peripheral layer. Alternatively, the outer clad layer may be formed by adding a lower amount of additive added to the outer peripheral layer than the outer peripheral layer. A layer made of a material containing an additive, a material containing an additive having a refractive index lower than that of an additive having a lower refractive index and / or a layer made of another material having a refractive index lower than that of the outer layer is formed so as to surround the outer layer. May be. Further, the inner clad and the outer clad may have a layer structure in which no additive is contained by selecting materials having different refractive indexes. Here, examples of other materials having a low refractive index include materials having good adhesion to polyvinyl chloride resins, such as polymethyl methacrylate and polyvinylidene fluoride, in addition to polyvinyl chloride resins.

  The production method of the double clad structure is not particularly limited, for example, a method of compound spinning using a spinning nozzle together with two kinds of mixture containing a transparent resin and a diffusible additive and an outer clad material, Method of co-extruding two kinds of mixture containing resin and diffusible additive and outer clad material, outer clad material after co-extrusion of two kinds of mixture containing transparent resin and diffusible additive A method of extrusion coating, or a method of extrusion coating an outer clad material after obtaining a polyvinyl chloride resin optical transmission body having a refractive index distribution, a monomer of an outer clad resin is applied, and an outer clad is passed through a polymerization process. Examples thereof include a layering method, a coating method in which a solvent-diluted outer clad resin is applied, and then the solvent is evaporated and dried.

  Hereinafter, examples of the optical transmission body of the present invention will be described in detail, but the present invention is not limited to the following examples.

(Example 1)
A resin composition in which 15% by weight of dichlorodiphenylsulfone (2Cl-DPS) is blended in a chlorinated polyvinyl chloride resin having a chlorine content of 66.5% and a polymerization degree of 700 is used as an inner layer, and the chlorinated polyvinyl chloride resin is a trimellit. A resin composition containing 2% by weight of tri-2-ethylhexyl acid (TOTM) was molded using two single-screw extruders and a two-layer mold so as to form an outer peripheral layer, and two coaxial layers having a diameter of 20 mm An optical fiber preform with a structure was obtained. Table 1 shows the results of measuring the glass transition temperature of each layer using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho.
The obtained preform was supplied to a cylindrical heater and heated and stretched to produce an optical fiber having a diameter of 0.5 mm.

The obtained optical fiber was wound on a metal reel, placed in a temperature-controllable tank, held at 150 ° C. for 10 minutes, and then the optical fiber was taken out.
The refractive index distribution of this optical fiber was measured using a transmission type two-beam interference microscope manufactured by Mizoji Optical Industry. The result is shown in FIG.
As shown in FIG. 1, the optical fiber has an optimum refractive index distribution in which the refractive index continuously decreases from the central axis portion to the peripheral portion.

(Example 2)
The above-mentioned chlorinated poly which does not contain a transparent and diffusible additive in a resin composition in which diphenyl sulfone (DPS) is blended in 11% by weight with a chlorinated polyvinyl chloride resin having a chlorine content of 70.0% and a polymerization degree of 550 A vinyl chloride resin was molded and heated and stretched in the same manner as in Example 1 so as to form an outer peripheral layer, thereby producing an optical fiber having a diameter of 0.5 mm.
The obtained optical fiber was wound on a metal reel and placed in a temperature-controllable tank. After maintaining at 160 ° C. for 30 minutes, the optical fiber was taken out. The refractive index distribution of the obtained optical fiber was evaluated in the same manner as in Example 1. As a result, it was confirmed that it had the same optimum refractive index distribution as in Example 1.

(Example 3)
A chlorinated polyvinyl chloride having a chlorine content of 67.7% and a degree of polymerization of 730 and a resin composition containing 20% by weight of diphenyl sulfone is added to a nozzle having an inner diameter of 0.6 mm so as to form an inner layer. A resin composition containing 8% by weight of dipentaerythrester (DPEE) in resin is supplied in a melted state to a nozzle having an outer diameter of 1 mm and an inner diameter of 0.6 mm so as to form an outer peripheral layer. A layer structure was formed. Subsequently, it was continuously led to a cylindrical diffusion tube (inner diameter: 1 mm, tube length: 300 mm) whose temperature was controlled at 180 ° C. at a rate of 5 mm / S, and diffusible additives were mutually diffused. Thereafter, after discharging the outer diameter of 1 mm from the foremost end of the spinning nozzle, it was wound up while being drawn on a metal reel to produce an optical fiber having a diameter of 0.5 mm.
The refractive index distribution of the obtained optical fiber was evaluated in the same manner as in Example 1.
As a result, it was confirmed that it had the same optimum refractive index distribution as in Example 1.

Example 4
A resin composition in which 12% by weight of dichlorodiphenylsulfone is blended in a chlorinated polyvinyl chloride resin having a chlorine content of 63.0% and a polymerization degree of 700 is used as an inner layer, and the chlorinated polyvinyl chloride resin is trimellitic acid tri-2- A resin composition containing 3% by weight of ethylhexyl was molded and heated and stretched to form an outer peripheral layer in the same manner as in Example 1 to produce an optical fiber having a diameter of 0.5 mm.
The obtained optical fiber was wound on a metal reel and placed in a temperature-controllable tank. After holding at 130 ° C. for 10 minutes, the optical fiber was taken out. The refractive index distribution of the obtained optical fiber was evaluated in the same manner as in Example 1. As a result, it was confirmed that it had the same optimum refractive index distribution as in Example 1.

(Example 5)
After obtaining the preform of Example 1, this preform was extrusion coated with polymethyl methacrylate to obtain a preform having a coaxial three-layer structure having an outer cladding layer.
The obtained preform was supplied to a cylindrical heater and heated and stretched to produce an optical fiber having a diameter of 0.5 mm. The obtained optical fiber was wound on a metal reel, placed in a temperature-controllable tank, held at 150 ° C. for 10 minutes, and then the optical fiber was taken out.
As a result of evaluating the refractive index distribution of the obtained optical fiber in the same manner as in Example 1, it was confirmed that the optical fiber had an optimum refractive index distribution.

(Comparative Example 1)
A resin composition prepared by blending 15% by weight of dichlorodiphenylsulfone with a chlorinated polyvinyl chloride resin having a chlorine content of 66.5% and a polymerization degree of 700 is used as an inner layer, and the chlorinated polyvinyl chloride resin is trimellitic acid tri-2- A resin composition containing 10% by weight of ethylhexyl was molded and heated and stretched in the same manner as in Example 1 so as to form an outer peripheral layer, thereby producing an optical fiber having a diameter of 0.5 mm.
The obtained optical fiber was wound on a metal reel and placed in a temperature-controllable tank. After holding at 150 ° C. for 10 minutes, the optical fiber was taken out.
The refractive index distribution of this optical fiber was evaluated in the same manner as in Example 1. The result is shown in FIG.
As shown in FIG. 2, the diffusion of the diffusible additive in the outer peripheral layer proceeded more than necessary, and the refractive index distribution shape tailed and deviated from the optimum refractive index distribution shape.

(Comparative Example 2)
A resin composition in which 28% by weight of diphenyl sulfone is blended with a chlorinated polyvinyl chloride resin having a chlorine content of 67.0% and a polymerization degree of 650 is used as an inner layer, and the chlorinated polyvinyl chloride resin is tri-2-ethylhexyl trimellitic acid. When an optical fiber having a diameter of 0.5 mm was produced by molding and heating and stretching a resin composition containing 8% by weight of the resin composition in the same manner as in Example 1 so as to form an outer peripheral layer, plastic deformation occurred.

  INDUSTRIAL APPLICABILITY The present invention relates to a wide variety of polyvinyl chloride resin optical transmission bodies such as a gradient index polymer optical fiber, a gradient index waveguide, a gradient index rod lens, and a polymer optical fiber having optical functionality, and a method for manufacturing the same. Applicable.

It is a graph which shows the refractive index distribution of the optical transmission body obtained by the manufacturing method of the plastic optical transmission body of this invention. 6 is a graph showing a refractive index distribution of an optical transmission body obtained by the method for manufacturing a plastic optical transmission body of Comparative Example 1.

Claims (5)

  An inner layer comprising a polyvinyl chloride resin, a refractive index higher than that of the polyvinyl chloride resin, and one or more additives that are transparent and diffusible, a polyvinyl chloride resin, and a refractive index Is lower than the polyvinyl chloride resin, and comprises an outer peripheral layer constituted with or without containing one or more transparent and diffusible additives, and the glass transition temperature of the inner layer is 60 to 110 ° C. Heat treatment of optical transmission body made of a polyvinyl chloride resin having a coaxial two-layer structure in which the glass transition temperature of the outer peripheral layer is 80 to 130 ° C. and the glass transition temperature of the outer peripheral layer is 20 ° C. higher than that of the inner layer And diffusing the additive toward the periphery or the center of the polyvinyl chloride resin optical transmission body to form a region in which the refractive index continuously changes. A method of manufacturing a transmission body.   The method for producing an optical transmission body made of a polyvinyl chloride resin according to claim 1, wherein the transparent and diffusible additive contained in the inner layer is one or more compounds selected from the group consisting of sulfur compounds.   The polyvinyl chloride system according to claim 1 or 2, wherein the transparent and diffusible additive contained in the outer peripheral layer is one or more compounds selected from the group consisting of trimellitic acid ester and dipentaerystol ester. Manufacturing method of resin optical transmission body.   The manufacturing method of the optical transmission body made from polyvinyl chloride resin of Claims 1-3 comprised from the polyvinyl chloride resin which a chlorine content rate is 62% or more and 73% or less. The polychlorination according to claims 1 to 4, wherein the transparent and diffusible additive is diffused at a temperature 30 ° C higher than the glass transition temperature of the outer peripheral layer before diffusion of the additive to 200 ° C for 30 seconds to 1 hour. A method for producing a vinyl resin optical transmission body.