JPH0364706A - Plastic optical transmission body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a plastic light beam having a continuous refractive index distribution from the center to the outer periphery, which is used in light-focusing lenses, light-focusing fibers, etc. It is related to the transmission body.

[Prior Art] As an optical transmission body having a continuous refractive index distribution from the center of the optical transmission body toward external use, a glass one has already been proposed in Japanese Patent Publication No. 47-816. however,
Glass optical transmission bodies have problems such as low productivity, high cost, and poor flexibility.

In contrast to such a glass optical transmission body, several methods have been proposed for manufacturing a plastic optical transmission body.

The manufacturing methods of plastic optical transmitters having a continuous refractive index distribution from the center to the outer periphery can be roughly divided into: (1) from the central axis of a synthetic resin rod made of an ionic W polymer to its surface; (Special Publication No. 47-269)
(No. 13), (2) A synthetic resin rod manufactured from a mixture of two or more transparent polymers having different refractive indexes is treated with a specific solvent to partially remove at least one of the constituent components of the synthetic resin rod. (Japanese Patent Publication No. 47-28059) (3) By devising a polymerization method of two types of monomers with different refractive indexes, a continuous refractive index distribution can be created from the surface to the inside. (4) A monomer having a lower refractive index than the surface of the crosslinked polymer is diffused so that the content of this monomer changes continuously from the surface to the inside. (5) refractive index lower than that of the surface of a polymer having reactivity; (Japanese Patent Publication No. 57-29682) by diffusing and reacting a low-molecular-weight compound with a high index of refraction to create a continuous refractive index distribution from the surface to the inside.
etc.

[Problems to be Solved by the Invention] Common problems with these conventional methods include the long time it takes to diffuse or extract the substance that gives the optical transmission body a refractive index distribution, and the resulting refractive index distribution type. Because the length of the optical transmission body itself is limited, the production process is intermittent, in other words, it is a batch production method, which has extremely low productivity and is extremely difficult to select manufacturing conditions and difficult to reproduce. Each of these manufacturing methods has its own problems as an industrial technology, such as the inability to obtain properties.

The optical transmission body obtained by the present invention is composed of a composition different from that obtained by the above-mentioned prior art, solves the unreasonableness caused by the intermittent production process that the above-mentioned prior art had, and uses glass or plastic optical fibers. This enables continuous production similar to that of

That is, the gist of the present invention is to provide an optical transmission body made of a polymer mixture of a polymer formed by photopolymerization and a polymer made by thermal polymerization, A plastic optical transmission body characterized in that the abundance ratio of photopolymer to thermal polymer continuously changes from the center to the periphery to form a refractive index distribution.

The polymer formed by photopolymerization used in the present invention mainly contains (meth)acrylate monomers as monomer units, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl. (meth)acrylate, benzyl (meth)acrylate, adamantyl (meth)acrylate, and perfluoroalkyl (meth)acrylate are preferably used. properties and good solubility in polymers obtained by thermal polymerization.

The refractive index distribution type optical transmission body of the present invention is usually produced by shaping a mixture of a thermally polymerized polymer and a photopolymerizable monomer as shown in the later examples, and in the shaped body, the monomer is It is preferable that the excipient be subjected to treatments such as diffusion and escape to impart a concentration distribution of the photopolymerizable monomer, or that the excipient be polymerized by irradiating the excipient with light.

Therefore, when carrying out the present invention, the mixing ratio of the photopolymerizable monomer to the thermal polymer is preferably 40% by weight or more in order to improve its transparency and shapeability. However, in order not to deteriorate the polymerization reactivity of the polymer composition, it is desirable that the monomer content be 75% by weight or less.

Further, in order to improve the photopolymerization reactivity of the polymer composition, it is preferable to add 0.1 to 5% by weight of a photopolymerization initiator to the polymer a acid.

The polymer mixture of the present invention consisting of a polymer made by photopolymerization and a polymer made by thermal polymerization may be any combination as long as the resulting plastic light transmitting body is transparent.

The significant shape and refractive index distribution of the plastic optical transmitter of the present invention is that the cross-sectional shape is circular fiber-like, and the refractive index decreases continuously from the center toward the periphery, and has a light focusing function or a convex lens. It has an optical fiber function.

In this case, coupling is achieved by increasing the mixing ratio of polymers with lower refractive index 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=No (1-ar") where the refractive index N0 at the center and the distance in the radial direction from the central axis is r. This is the case given by .

The amount of monomer remaining in the optical transmission body of the present invention (preferably as little as possible is 1 bar, 3% or less, preferably 1.5% or less), and this can be achieved by the method described above.

The present invention will be explained in more detail below with reference to Examples.

[Example] - Evaluation method 15 Evaluation device Lens performance was evaluated using an evaluation device as shown in FIG.

2. Adjustment of the sample Cut the trial-produced gradient index lens so that it has a length (λ) of approximately A of the period (λ) of the light beam determined from the undulation of the passing He-Ne laser beam, and cut it using a polishing machine. The sample was polished so that both end surfaces were parallel planes perpendicular to the long axis, and used as evaluation materials.

3.Measurement method As shown in Figure 2, set the prototype sample (108) on the sample stand placed on the top of the optical bench (101), adjust the aperture (104) L7 and turn on the light fi ( a lens for condensing light from (102) (103), an aperture (104),
After passing through the glass plate (105) and making it incident on the entire surface of the sample, the positions of the sample (108) and the Polaroid camera 007) were adjusted so that they were focused on the Polaroid film, and a square grid image was taken. , the distortion of the lattice was observed. The glass plate (105) used was a chrome-plated glass for photomasks that had a chrome film precisely processed into a 0.1 arm square grid pattern.

-Measurement of refractive index distribution Measurement was performed by a known method using an Interfaco Chishita microscope manufactured by Carl Zeiss.

Example 1 48 parts by weight of poly-(2°2.3.3-tetrafluoropropyl methacrylate) (nol, 420, ([η) 2.285 measured in ME at 25°C), 35 parts by weight of methyl methacrylate part, tart-butyl methacrylate
1.17 parts by weight, 1 ton of cyclohexyl ketone O, 51 parts by weight of 1 tL of hydroquinone O are charged into the cylinder shown in Fig. 1, heated to 80°C, passed through a kneading section, and then was pushed out from the 2.0m nozzle. The viscosity of this precursor composition upon extrusion is lXl0
'It was Boyz. Next, the extruded fibers were heated to 80°C, passed through a volatilization section where nitrogen gas flows at a rate of 10 i/win in 13 minutes, and passed through a 500-cm ultra-high pressure chamber installed in six circles at equal intervals. Light is irradiated through the fiber at the center of the mercury lamp for 5 minutes at 20cm/si.
A nip roller was used to remove the tension at a speed of n. The diameter of the obtained fiber was 1.00 m, and the refractive index distribution measured with an interfaco interference microscope was 1.448 m at the center.
, the peripheral part was 1.433, and it decreased continuously from the center to the peripheral part.

In addition, the results of compositional analysis of the obtained fiber by NMR showed that the center contained 61% by weight of poly-(2,2,3,3-tetrafluoropropyl methacrylate), and the peripheral part contained 82% by weight. .

In addition, polymethyl methacrylate is 30% by weight in the center.
, the surrounding area contained 5% by weight.

The overall monomer residue was 1.3%.

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

Comparative Example 1 48 parts by weight of poly-(2,2,3,3-tetrafluoropropyl methacrylate) ([η] 2.285 measured at 25°C in nnL420.0IEK), 35 parts by weight of methyl methacrylate, t, Example 1 17 parts by weight of ert-butyl methacrylate and 0.1 parts by weight of Hyde O-quinone
An optical transmission body was obtained by performing the same operation as above. However, the total amount of monomers remaining in this optical transmission body was as large as 4.5%. For this reason, it had poor environmental resistance properties such as heat resistance, and was subject to severe changes over time and had no practical properties.

Example 2 Polymethyl methacrylate was fed into the apparatus shown in Figure 1 and extruded through a nozzle (1) heated to 230"C to form a filament with a diameter of 500μ, and then 2.2.3.3-tetrafluoropropyl methacrylate. 25 parts by weight of methyl methacrylate, 20 parts by weight of Acrivet VHK (manufactured by Mitsubishi Rayon Co., Ltd.), and 1 part by weight of .2.3.3-tetrafluoropropyl methacrylate 50 parts by weight, 2°2.3,
3.4,4.5.5-octafluoropentyl methacrylate 20 parts by weight, methyl methacrylate 10 parts by weight,
A polymerizable composition consisting of 20 parts by weight of polymethyl methacrylate and 1 part by weight of 1-hydroxycyclohexylphenyl ketone was used as the second layer transparent material, and the second layer was coated using the composite nozzle (2) shown in FIG. The thickness of one layer was 170× and the thickness of the second layer was 30×. After this, 7
N at 0°C, gas at 51. After 3 minutes, it was irradiated with ultraviolet rays for 3 minutes using 8 20-meter chemical lamps to photopolymerize it to obtain a gradient index optical transmission body with a diameter of 900-meters. Ta. When the refractive index distribution of this optical transmission body was measured using an interfaco interference microscope, the center refractive index was 1.487, and the refractive index at the outer periphery was 1.448.
It varied continuously from the center to the outer periphery.

Further, when both ends of this optical transmission body were polished to a length of 3.5 m and an image was observed, an inverted real image was observed.

The total monomer residue was 1.2%.

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 3 Polymethyl methacrylate ([η) = 0.56°MEK
(Measured at 25°C) 46 parts by weight, 44 parts by weight of benzyl methacrylate, 10 parts by weight of methyl methacrylate, 1
-0.5 parts by weight of hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated to 70°C and kneaded to make a core stock solution, and polymethyl methacrylate ([η) -0,34,MEK , 25°C), 48 parts by weight of methyl methacrylate, 0.4 parts by weight of 1-hydroxycyclohexylphenyl ketone, and 0.1 part by weight of hydroquinone were heated to 70°C, kneaded, and mixed to make the stock solution of the sheath. As a result, both the core and sheath stock solutions were extruded simultaneously using a concentric compound nozzle. The discharge ratio at this time was (core component):(sheath component)=1:2. Further, the heat retention temperature of the composite nozzle was 40°C. Then, 90
After that, the fiber was passed through the center of 120 CII, 40-fluorescent lamps arranged in a circle at equal intervals, and taken off with a nip roller at a speed of 25 cm/min. The resulting fiber has a diameter of 1155 mm and a refractive index N measured by Interfaco interference microscopy.
The distribution of , is 1.515 at the center and 1.492 at the periphery.
and decreased continuously from the center to the periphery. Further, when both ends of this optical transmission body were polished to a length of 4.5 m and an image was observed, an inverted real image was observed.

The total monomer residue was 1.5%.

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

[Effects of the Invention] The manufacturing method of the present invention solves the irrationality caused by the intermittent production process of the prior art, and makes it possible to continuously produce optical transmission bodies.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a spinning device that can be effectively used to manufacture the plastic optical transmission body of the present invention.

Claims (1)

[Claims] 1. A linear optical transmission body made of a polymer mixture consisting of a polymer formed by a photopolymerization method and a polymer formed by a thermal polymerization method, and the presence of a photopolymer contained in the optical transmission body. A plastic optical transmission body characterized in that the ratio changes continuously from the center to the periphery to form a refractive index distribution.