JPS62108208A - Plastic optical transmission body and its production - Google Patents

Abstract

PURPOSE:To produce the titled body having a wide use by a simple process with a good productivity by forming the titled body composed of a mixture contg. specific two kinds of copolymers and by forming a distribution of said components in such a way that the mixing ratio of both components changes continuously from an inner part of the titled body to a surface thereof. CONSTITUTION:The copolymer A composed of vinylidene fluoride and hexafluoroacetone, the copolymer B composed of a polymethylmethacrylate or a methylmethacrylate unit as a main component, and the monomer mixture C composed of a methylmethacrylate monomer as the main component, or the copolymer a and the monomer mixture C are fed to a cylinder 1 and are extruded quantitatively by a piston 4 while heating it with a heater 3 followed by mixing it in a kneading part 2 and then by producing a strend fiber 6 from a nozzle 5. The obtd. fiber 6 is introduced to a vaporizing part 7 and is vaporized the monomer C from the surface of said strand by an air or an another gas led from a gas inlet pipe 9 whereby the prescribed distribution of the concentration of said components from the inner part of the strand to the surface thereof is obtained. the obtd. strand is solidified by polymerizing said components in the irradiating part 8 of an active ray, followed by winding up it on a drum 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plastic optical transmission body having a continuous refractive index distribution from the surface to the inside, and a method for manufacturing the same. More specifically, the present invention relates to various optical transmission lines such as light-focusing lenses, light-focusing optical fibers, optical transmission lines used in optical ICs, etc., and methods for manufacturing the same.

[Conventional technology]

A photoconductor having a continuous refractive index distribution from the surface to the inside has already been proposed in Japanese Patent Publication No. 47-816, which is made of glass. However, such optical transmission bodies made of glass have problems in that they have low productivity, are expensive, and have poor flexibility.

Several methods of manufacturing a glass optical transmission body have been proposed for such a glass optical transmission body. These plastic optical transmitters that have a continuous refractive index distribution from the surface to the inside can be roughly divided into: (1) metal ions that are continuously directed from the central axis of the synthetic resin body made of an ionically crosslinked polymer toward the surface; (Japanese Patent Publication No. 47-26915), (2) A synthetic resin body made from a mixture of two or more transparent polymers with different refractive indices is treated with a specific solvent, Products manufactured by partially dissolving and removing at least one of the constituent components of a synthetic resin body (Japanese Patent Publication No. 47-28059), (3
) Two types of polymers with different refractive indexes were created by devising a polymerization method to create a continuous refractive index distribution from the surface to the inside (Japanese Patent Publication No. 54-3030)
No. 1), (4) Diffusing a monomer with a lower refractive index than the polymer from the surface of the crosslinked polymer, extending from the surface to the inside,
After arranging the compound so that the content thereof changes continuously, it is polymerized to give a refractive index distribution (Japanese Patent Publication No. 52
-5857, Special Publication No. 56-37521), and (
5) A low-molecular compound having a refractive index lower than that of the polymer is diffused and reacted with the surface of a reactive polymer to create a continuous refractive index distribution from the surface to the inside ( Special Publication No. 57-29682) etc.

[Problem that the invention seeks to solve]

A common problem with these conventional methods is that processes such as diffusion or extraction take a long time, or that the length is limited, so the production process is intermittent.In other words, it is a batch-type production method. These manufacturing methods each have their own problems as an industrialization technology, such as extremely poor productivity, extremely difficult selection of manufacturing conditions, and inability to achieve reproducibility.

The present invention solves the irrationality caused by the intermittent production process that the above-mentioned prior art had, and enables continuous production similar to that of optical fibers or plastic optical fibers.

[Means for solving problems]

The present invention is an optical transmission material comprising a mixture of a copolymer (A) of vinylidene fluoride and hexafluoroacetone and a copolymer (B) whose main component is polymethyl methacrylate or methyl methacrylate units. , (A) component and (B
) The first invention is a plastic optical transmitter characterized by the composition ratio of components being distributed while changing continuously from the inside toward the surface, and the first invention is a plastic optical transmitter characterized by a copolymerization of vinylidene fluoride and hexafluoroacetone. A composition obtained by dissolving and mixing the aggregate (A), a copolymer (B) containing polymethyl methacrylate or methyl methacrylate units as a main component, and a monomer mixture (C) containing a methyl methacrylate monomer as a main component, Alternatively, a composition obtained by dissolving and mixing a copolymer of vinyl fluoride and hexafluoroacetone (A) and a monomer mixture containing methyl methacrylate monomer as a main component (C) is molded into a desired shape. , after molding, the monomer is volatilized from the surface of the molded product, and after or while giving a continuous concentration distribution from the inside to the surface, the unpolymerized single rods are polymerized. A second invention is a method for manufacturing a plastic optical transmission body.

The composition ratio of the copolymer of vinylidene fluoride and hexafluoroacetone used in the present invention is not particularly limited, but compatibility with polymethyl methacrylate or a copolymer mainly composed of methyl methacrylate units is taken into consideration. In this case, the composition ratio of hexafluoroacetone is preferably at least 1 mo/l/ti or more. Furthermore, when considering the substantial performance such as heat resistance, mechanical properties, workability, refractive index power, etc. of the plastic optical transmitter obtained by the manufacturing method of the present invention, the content of vinyl fluoride should be at least Preferably it is 50 mo/L/%. When the vinylidene fluoride content is 75 mo/I/4 or less, the copolymer becomes a rubber-like, non-quality polymer, and a plastic optical transmission body having particularly high flexibility can be obtained.

In addition, in the present invention, in order to improve practical performance such as heat resistance, mechanical properties, workability, and refractive index balance, vinylidene fluoride and hexafluoroacetone may contain other substances other than vinylidene fluoride and hexafluoroacetone, such as tetrafluoroethylene. A third component such as propylene hexafluoride or vinyl fluoride may be copolymerized.

Another ingredient in the present invention is POLYMETHYP METAC! IV
-1- and a copolymer containing this as a main component are used. Copolymerization components include ethyl methacrylate p1 propyl methacrylate, n-buty methacrylate μ, t-buty methacrylate, cyclohexy p methacrylate, pheniμ methacrylate, benzymethacrylate p1 methacrylate/71! i12.
2.2-Trieloloethyl μ-β-hydroxyethyl methacrylate, glycidyl methacrylate, β-methacrylate
methacrylates such as methyl glycidi p, methyl acrylate, ethyl acrylate p1 propy acrylate p1 acrylates such as butyl acrylate, methacrylic acid,
Co-produced with styrene acrylate, α-methylene styrene, etc.
Coalescence 75: Examples include, but are not limited to, and a copolymer containing a small amount of other components such as acrylonitrile and maleic anhydride may also be used.

The amount of these copolymer components is preferably 50% by weight or less, preferably 30% by weight or less, and more preferably 15% by weight*S or less.

The present invention shows that the mixture of vinylidene fluoride and hexafluoroacetone copolymers and methyl methacrylate thread polymers has excellent compatibility so that nearly molecular dispersion is achieved and, despite the mixture of polymers with considerably different refractive indices, a fairly wide This is an application of the property of being transparent even within a range of mixing ratios.

The range of the transparent mixing ratio is that the vinylidene fluoride and hexafluoroacetone copolymer is in the range of D to 95% by weight, and the ratio of vinylidene fluoride and hexafluoroacetone copolymer is 95% by weight or more. In this case, the vinylidene fluoride and hexafluoroacetone copolymer easily crystallizes and becomes milky white and opaque, which is not preferable.

That is, in the present invention, the mixing ratio of vinylidene fluoride and hexafluoroacetone copolymer is 0 to 95% by weight, preferably 0 to 95% by weight.
It is a plastic optical transmission body in which the refractive index changes continuously within a range of 80% by weight, and the refractive index also changes continuously accordingly.

A major feature of the present invention is that various shapes and refractive index distributions can be set depending on the purpose.

The shape and refractive index distribution that is more meaningful in the present invention is that the cross-sectional shape is circular and the refractive index decreases continuously from the center toward the periphery, and has a light focusing function, a convex lens function, and an optical fiber function. It is something.

In this case, this is achieved by increasing the mixing ratio of vinylidene fluoride and hexafluoroacetone copolymer from the center to the periphery.

Particularly preferably, the refractive index distribution N in each cross section perpendicular to the central axis is close to N wNo (1-ar'') where No is the refractive index at the central axis and r is the distance in the radial direction from the central axis. This is the case given by the distribution.

In addition to this, waveguides and flat plate lenses in which a refractive index distribution is formed in a υ flat plate according to the present invention are also possible.

FIG. 1 shows a cross-sectional view of an example of the optical transmission body manufacturing apparatus of the present invention. The polymer (A) and the monomer mixture (C) are placed in a cylinder (
1), extruded quantitatively with the piston (4) while heating with the heater (3), mixed homogeneously in the kneading section (2), and then the nozzle (5)!Re-strand fiber (6)
get.

The strand fiber (6) is led to the volatilization part (7), and the monomer (C) is volatilized from its surface by a gas such as air, nitrogen, or argon introduced from the gas hole (9), and the monomer (C) is inside the strand fiber. A concentration distribution of mer (C) is generated. After drawing the concentration distribution according to the purpose, such as the thickness of the strand fiber, the discharge amount, the take-up speed, the residence time, the temperature of the volatile part, the flow rate, etc., it is guided to the actinic ray irradiation part (A)), and the remaining Polymerize and solidify the monomers that are
) and then wound onto a winding drum (11) to continuously obtain the desired optical transmission body (12). In this method, the light irradiation may be performed after the volatilization part as described above, but the volatilization and light irradiation may be performed simultaneously if the conditions can be set. Further, the volatilization may be carried out with a stream of air or an inert gas such as nitrogen or argon, or may be carried out under reduced pressure. Furthermore, in order to further reduce the residual monomer in the light transmission body (12), a thermal polymerization section may be set after the light irradiation section, or the light irradiation may be further performed while the polymer is heated to T9 or higher. is also valid.

In the precursor composition of the present invention, only vinylidene fluoride and hexafluoroacetone copolymer may be used as the polymer, or both vinylidene fluoride and hexafluoroacetone copolymer and methyl methacrylate thread polymer may be used. may be mixed, or a third component may be mixed and used as long as the brightness is not impaired.

Further, in the vehicle mass mixture (C) to be dissolved, only methyl methacrylate was used as a monomer, and 4J1. stone,
There is absolutely no problem in including the monomer copolymer constituting the methyl methacrylate copolymer mentioned above. Furthermore, it is also preferable to use trifunctional or trifunctional polymers such as ethylene glyco-p dimethacrylate in combination to improve thermal properties, processability, and mechanical properties.

Further, in the present invention, it is an effective means to add and use a conventionally known photopolymerization initiator, accelerator, or sensitizer to promote photopolymerization.

Further, in order to enhance the storage stability of the precursor composition and to prevent viscosity change, that is, thermal polymerization when forming the composition into a fibrous form, it is preferable to use a conventionally known thermal polymerization inhibitor.

Although the precursor composition thus obtained does not undergo a thermal polymerization reaction at a temperature of about 100° C., it is necessary to knead the precursor composition sufficiently homogeneously in order to obtain a homogeneous optical transmitter.

A conventionally known mixing device can be used for the kneading operation. In addition, in order to obtain a fibrous optical transmission body with a diameter of approximately α5 to 5 φ,
The viscosity of the precursor composition at the extrusion temperature is particularly important, and should be in the range of 1.000 to 100,000 poise, preferably s, o o o to 50,000 poise.

As an active light source that can be used in the present invention, 150
An arc lamp that emits light with a wavelength of ~600 nm,
Ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, chemical pumps, xenon pumps, laser lights, etc. can be used. Further, depending on the case, polymerization may be carried out by irradiation with an electron beam.

Furthermore, in order to complete the polymerization or to minimize residual monomer, light irradiation is carried out in two stages.
Alternatively, it is effective to use it in combination with thermal polymerization. Following the polymerization, residual monomers may be dried with hot air or the like.

The amount of monomer remaining in the optical transmission body of the present invention is preferably as small as possible, and is preferably 5% or less, more preferably 3% or less, and even more preferably 1.5% or less, which can be achieved by the method described above. is possible.

In order to further improve the optical properties of the light transmitting material obtained according to the present invention, the obtained light transmitting material is heated to a temperature higher than about 100° C. and a blend of vinylidene fluoride, hexafluoroacetone copolymer, and methyl methacrylate-based polymer. It is preferable that the material is once heated to a temperature lower than the lower critical cosolution temperature of the material, and then rapidly cooled to room temperature or a temperature lower than that using a refrigerant such as air, water, ice, dry ice, or liquid nitrogen. This heat treatment improves the optical transmission properties and resolution of the optical transmission body.

The present invention will be explained in more detail below with reference to Examples. In the examples, parts indicate parts by weight.

〔Evaluation methods〕

(2) Measurement of Lens Performance (2) Evaluation Apparatus Lens performance was evaluated using an evaluation apparatus as shown in FIG.

■ Preparation of the sample Cut the prototype gradient index lens to a length 1) that is approximately 1/4 of the period (λ) of the light beam determined from the ridges υ of the He-Ne laser beam passing through it. Using a polisher, both end surfaces of the sample were polished to become parallel planes perpendicular to the long axis, and used as an evaluation sample.

■Measurement method As shown in Figure 2, the prototype sample (10a) is set on the sample stage placed on the optical bench (101), the aperture (104) is adjusted, and the light source (102) is set. After the light passes through the condensing lens (103), the aperture (104), and the glass plate (105) and is incident on the entire end surface of the sample, the positions of the sample (108) and the Polaroid camera (107) are adjusted. Adjust the focus so that it is on the Polaroid film, shoot a square grid image,
The distortion of the grid was observed. The glass plate (105) used was a chrome-plated photomask glass plated with a chrome coating precisely processed into an α1 square grid pattern.

(2) Measurement of refractive index distribution Measurement was carried out by a known method using an Interfaco interference microscope manufactured by Carl Zeiss.

Example 1 Copolymer (nDl, 390) consisting of 91 mo/L vinylidene fluoride/91 mo/L/% hexafluoroacetone (nDl, 390) 8
1 part, 27 parts of polymethyl methacrylate (nDl, 492) produced by continuous bulk polymerization method, 65 parts of methyl methacrylate monomer, 1 part of benzyl dimethyl keter pα, 1 part of hydroquinone α, cylinder (1) of the apparatus shown in FIG.
heated to 80°C, passed through the kneading section to a diameter 2.0
It was extruded from the nozzle μ of the electric wire φ. At this time, the viscosity of this precursor composition during extrusion was 2-5XIQ4 poise. Next, the extruded fiber was passed through the volatilization section in which nitrogen gas heated to 80℃ flows at a flow rate of 10-7 minutes in 12 minutes, and the fiber was passed through the center of six 400W high-pressure mercury lamps installed at equal intervals in a circle. The fiber was passed through the fiber, irradiated with light for about 5 minutes, and pulled off with a nip roller at a speed of zom/min.

The diameter of the obtained fiber was 1000 μm, and the refractive index distribution measured by an ink-faco interference microscope was 1.471 at the center and 1.465 at the periphery, and decreased continuously from the stop to the periphery. Was.

In addition, as a result of the compositional analysis of the obtained fiber by NMH, the center portion contained 20 weight percent of a copolymer of vinylidene fluoride and hexafluoroacetone, and the peripheral portion contained 50 weight percent. The residual amount of methyl methacrylate monomer is
The total amount was 1.0% by weight.

Furthermore, as a result of the above-mentioned lens performance measurement, it was found that the image of the square lattice had little distortion.

Example 2 Copolymer (nDl, 390) consisting of 91 moA/% vinylidene fluoride and 9 mo/L/% hexafluoroacetone (nDl, 390) 50
1 part, 50 parts of methyl methacrylate monomer, 110.1 parts of benzene μ dimethyl keter, and 11 parts of hydroquinone were charged into the apparatus shown in FIG. 1, and a fiber was obtained in the same manner as in Example 1. As a result of evaluation in the same manner as in Example 1, the center part was n
Dl, 450, vinylidene fluoride, hexafluoroacetone copolymer composition ratio 60 times, peripheral area no 1.
415, the same composition ratio was 80% by weight, and it decreased continuously from the center to the periphery.

As a result of 4+1J adjustment of the lens performance, the image of the square lattice had little distortion, but the contrast of the image was slightly poor. In addition, the scattering was greater toward the periphery of the lens.

The Corlens was heated at 140°C for 5 minutes and quenched with 10°C water.

The lens properties of this rapidly cooled and heat-treated lens were such that the image was clear and had good contrast.

Scattering around the lens was also reduced.

Example 3 30 parts of a copolymer (nDt39o) consisting of 91 mo/&% vinylidene fluoride and 9 mole hexafluoroacetone, polymethacrylate (nDl
, 492) 20 parts, methyl methacrylate monomer 5
0 parts, 1-hydroxycyclohexylphenylphene p-ketone 0
．． 2 parts and 11.1 parts of hydroquinone were charged into the apparatus shown in FIG. 1, and a fiber was obtained in the same manner as in Example 1.

As a result of evaluation in the same manner as in Example 1, the central portion nD1.
455, vinylidene fluoride, hexafluoroacetone copolymer composition ratio 40% by weight, peripheral area n n 1.455,
The composition ratio is 55% by weight, and from the center to the periphery n
D was decreasing continuously.

As a result of measuring the lens performance, the image had little distortion and had a larger numerical aperture than Example 1.

Example 4 Copolymer (nDl, 370) consisting of vinylidene fluoride (75 motv%), hexafluoroacetone (25 motv%) Vcs
A fiber was obtained in the same manner as in Example 1 except that 'fj was used. As a result of evaluation in the same manner as in Example 1, the central part nD
1.468, composition ratio of vinylidene fluoride/hexafluoroacetone copolymer 20% by weight, peripheral area no '1.4
60, the same composition ratio was 50% by weight, and np decreased continuously from the center toward the periphery. As a result of measuring the lens performance, the image had little distortion, and its mechanical properties were particularly rich in flexibility.

〔Effect of the invention〕

The plastic optical transmission body according to the present invention can be used for rod lenses used in V lens arrays for copiers, lens arrays for facsimile machines, optical fiber coupling elements, optical demultiplexers, line sensors, etc., graded index optical fibers, light emitting It is used for a wide range of applications as a decorative optical fiber, and the process is very simple and the productivity is high, and it provides an efficient manufacturing method as an engineering process.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of the optical transmission body manufacturing apparatus of the present invention;
FIG. 2 is an explanatory diagram of the arrangement of an apparatus for evaluating lens performance of a synthetic resin body obtained according to the present invention. 1... Cylinder 2... Kneading section 3... Heater 4... Piston 5... Nozzle 6... Strand fiber 7... Volatile section 8... Actinic ray irradiation section 9. ... Gas introduction hole 10 ... - Nip roller 11 ... Winding drum 12 ... Light transmission body 102 ... Tungsten lamp for light source 103 ... Focusing lens 108 ... Evaluation materials

Claims (1)

[Scope of Claims] 1) An optical transmission material comprising a mixture of a copolymer (A) of vinylidene fluoride and hexafluoroacetone and a copolymer (B) containing polymethyl methacrylate or methyl methacrylate units as a main component. 1. A plastic optical transmitter, characterized in that the mixing ratio of components (A) and (B) is continuously varied and distributed from the inside toward the surface. 2) The constituent components of the copolymer (A) are vinylidene fluoride/hexafluoroacetone (molar ratio) in the range of 99/1 to 50/50 in terms of monomers. plastic optical transmission body. 3) A copolymer of vinylidene fluoride and hexafluoroacetone (A), a copolymer containing polymethyl methacrylate or methyl methacrylate units as a main component (B), and a monomer mixture containing a methyl methacrylate monomer as a main component (C), or a monomer mixture containing vinylidene fluoride and hexafluoroacetone copolymer (A) and methyl methacrylate monomer as main components (
A composition obtained by dissolving and mixing C) is molded into a desired shape, and after molding, the monomer is volatilized from the surface of the molded product to give a continuous concentration distribution from the inside to the surface. Alternatively, a method for producing a plastic optical transmitter, characterized in that unpolymerized monomers are polymerized while being fed.