JPH0749425A - Manufacture of refractive index distributed type plastic mold - Google Patents

Abstract

PURPOSE:To continuously produce an optical transmitter by combining a polymer with two kinds of monomers. CONSTITUTION:A composite formed by mutually dissolving and mixing a polymer A having a low refraction index N1; a highly volatile monomer C which provides a polymer B having a high refraction index N2; and a monomer E which provides a polymer D having a refraction index N3 higher than the polymer A and is more volatile than the monomer C is put in a cylinder 1. The composite is quantitatively extruded by a piston 4 while it is heated by a heater 3, homogeneously mixed in a kneading part 2, and then extruded by a nozzle to provide a stranded fiber. The stranded fiber is passed through a first volatilizing tower 7a to selectively volatilize the monomer C from the outer circumferential part of the strand fiber 6 under a fixed condition, and then passed through a second volatilizing tower 7b to volatilize also the monomer E, providing a continuous distribution from the surfaces of the monomers C, E in the strand fiber to the center, and the monomer mixture is then polymerized and solidified by an active beam irradiating part 8, and wound on a winding drum 11 through a nip roller 10 to provide an optical transmitter 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a light converging lens, a light converging fiber, etc., from the center of a plastic molded product to the outer periphery, or from one end face to the other end face of the molded product. The present invention relates to a method for manufacturing a plastic optical transmission body having a continuous refractive index distribution.

[0002]

2. Description of the Related Art An optical transmission body having a continuous refractive index distribution from the center to the outer periphery of a molded article has already been disclosed in Japanese Patent Publication No.
A glass-made one is proposed in Japanese Patent No. 816. However, the optical transmitter made of glass has the problems of low productivity, high cost, poor impact resistance, and difficulty in handling.

For such a glass optical transmission medium, several methods for manufacturing a plastic optical transmission medium have been proposed. These methods are methods for producing a plastic optical transmission body having a continuous refractive index distribution from the center of the plastic columnar body to the outer periphery. When roughly classified, the center of the synthetic resin columnar body made of an ionic cross-linked polymer is used. One in which the metal ion concentration is continuously changed from the axis toward the surface thereof (Japanese Patent Publication No. 47-26913), and it is prepared from a mixture of two or more transparent polymers having different refractive indexes. By mixing the synthetic resin columnar body with a specific solvent to partially dissolve and remove at least one of the constituent components of the synthetic resin body, the mixing ratio of the two polymers from the center to the outer periphery of the cylindrical body To change the refractive index distribution (Japanese Patent Publication No. 47-28059),
Put a mixture of two kinds of monomers with different refractive index into a cylindrical container, devise a polymerization method, polymerize the monomer, and change the composition ratio of the polymer of the cylindrical object from the center to the surface to obtain the refractive index distribution. What makes it possible
4-30301), a monomer capable of forming a polymer having a refractive index lower than that of the crosslinked polymer is diffused from the surface of the columnar crosslinked polymer, and the monomer of the monomer is spread from the surface to the inside. An optical transmission body having a refractive index distribution obtained by polymerizing the monomer after arranging so that the content rate changes continuously (Japanese Patent Publication No. 52-5857).
JP-B-56-37521), and a low molecular weight compound having a group having a refractive index lower than that of a reactive cylindrical polymer and capable of reacting with the reactive polymer. Is allowed to diffuse and react to continuously change the concentration of the low molecular weight compound from the surface of the columnar polymer to the inside thereof so as to have a refractive index distribution (JP-B-57
No. 29682).

[0004]

The problems common to these conventional methods are that the process of diffusing or extracting the compound for providing the refractive index distribution into the plastic cylindrical body takes a long time, and the obtained refractive index distribution is Since the length of the optical transmission medium is limited, the production process is a batch-type production method, and there is the drawback that the characteristics of the optical transmission medium obtained for each batch change, and the productivity is extremely poor. ,
As an industrialized technology, there are many points to be improved.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the irrationality of the gradient index plastic molded product by the intermittent production process, which the above-mentioned conventional technique has, and it is similar to a glass or plastic optical fiber. The purpose of this is to provide a polymer (A) having a low refractive index N1 and a polymer having a refractive index N2 higher than that of the polymer (A).
Highly volatile monomer (C) and polymer (A) giving (B)
Gives a polymer (D) with a higher refractive index N3 than
(C) A monomer mixture (E) having a lower volatility than that of (C) is molded into a desired mixture, and the monomer is first mixed on the surface of the molded product.
(C) is volatilized, then, by placing the monomer (E) under the condition of volatilizing, from the inside of the molded article toward the surface,
Alternatively, from one end surface to the other end monomer (C),
Manufacture of a gradient index plastic molded product characterized by polymerizing the unpolymerized monomers (C) and (E) in the molded product with a continuous concentration distribution of (E) On the way.

The combination of the polymer (A) and the monomer (C) and the monomer (E) used in the present invention is a monomer (C),
Any combination can be used as long as (E) is a combination in which the composition formed by polymerization and curing and the polymer (A) becomes transparent.

A major feature of the present invention is that an optical transmission material having a desired refractive index distribution can be obtained by a combination method of the polymer (A), the monomer (C) and the monomer (E). , And a shaping method thereof, it is possible to obtain a refractive index distribution type optical transmission body having a desired shape such as a fiber-shaped material or a plate-shaped material.

In the present invention, the more significant shape and refractive index distribution is that the cross-sectional shape is a fibrous shape with a circular shape, and the refractive index is continuously smaller from the center toward the periphery, and the light focusing function or It has a convex lens function and an optical fiber function. In this case, the refractive index distribution can be imparted to the columnar material by decreasing the mixing ratio of the polymer (A) from the center to the periphery. Particularly preferably, the refractive index distribution N in a cross section perpendicular to the central axis of the cylindrical body is expressed by [Equation 1], where r _{0 is} the refractive index of the central portion and r is the radial distance from the central axis. This is the case when the distribution is close to the distribution.

[Equation 1]

An example of the method of manufacturing the graded index optical transmission body of the present invention is shown in FIG. Polymer with low refractive index N1
(A) and a polymer (B) with a refractive index N2 higher than that of the polymer (A) .A highly volatile monomer (C) and a polymer (D) with a refractive index N3 higher than that of the polymer (A). ), And a composition obtained by dissolving and mixing a monomer (E) having a lower volatility than the monomer (C) is charged into the cylinder 1, and quantitatively with the piston 4 while heating with the heater 3. Then, the mixture is homogeneously mixed in the kneading section 2 and then extruded from a nozzle to obtain a strand fiber. The strand fiber is passed through the first volatilization tower 7a to selectively volatilize the monomer (C) from the outer peripheral portion of the strand fiber 6 under a certain condition, and thereafter, the monomer (C) is passed through the second volatilization tower 7b so as to be separated. After the monomer (E) is also volatilized to give a continuous distribution from the surface of the monomer (C) and the monomer (E) in the strand fiber toward the center, then the actinic ray irradiator 8 Guide, polymerize and solidify the monomer mixture, and nip roller 10
After that, it is wound on the winding drum 11 to continuously obtain the desired optical transmission body 12. At this time, it is desirable to introduce an inert gas such as nitrogen or argon gas through the gas introduction hole 9 for the purpose of facilitating the temperature control of the heat retention tower 7 and facilitating the polymerization by the actinic ray.

In the gradient index optical transmission body produced by the method of the present invention, the refractive index distribution in the vicinity of the outermost peripheral portion is close to a quadratic curve, and it is assumed that the disorder of the refractive index distribution due to tailing is remarkably improved. be able to.

Further, in the present invention, a conventionally known photopolymerization initiator, or an accelerator and a sensitizer for promoting the photopolymerization of the monomer in the strand fiber are added to the resin composition for forming the strand fiber. Doing is an effective means. Further, in order to increase the storage stability of the composition and to prevent the viscosity change and the thermal polymerization when the composition is shaped into a fiber, it is preferable to use a conventionally known thermal polymerization inhibitor. The composition thus obtained does not undergo a thermal polymerization reaction at a temperature of about 100 ° C., but the precursor composition needs to be sufficiently homogeneously kneaded in order to obtain a homogeneous light transmission body.

A conventionally known kneading device can be used for the kneading operation. Further, in order to obtain a fibrous optical transmission body having a diameter of about 0.5 to 5 mm, the viscosity of the composition for forming a strand fiber at the extrusion temperature is particularly important.
It should be in the viscosity range of 000 poise, preferably 5,000 to 50,000 poise.

As the active light source for monomer polymerization used in the present invention, a carbon arc lamp, a super high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a chemical lamp, a xenon lamp, a laser beam, etc., which emits light having a wavelength of 150 to 600 nm, etc. Can be used.
In some cases, electron beams may be irradiated to cause polymerization. Further, in order to complete the polymerization or to reduce the residual monomer as much as possible, it is effective to carry out the photopolymerization in two stages or to use the thermal polymerization method and the photopolymerization method in combination. Following the polymerization, the residual monomer may be dried with hot air or the like. The amount of the monomer remaining in the optical transmission medium of the present invention is preferably as small as possible, and is 5% or less, further 3% or less, and further preferably 1.5% or less, which can be achieved by the above method. is there.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0015]

【Example】

[Evaluation method] 1. Evaluation Device Evaluation of lens performance was performed using an evaluation device as shown in FIG. 2. Sample preparation Almost 1 / (1 /) of the period (λ) of the light beam judged from the swell of the He-Ne laser beam passing through the prototype gradient index lens
The sample was cut to a length of 4 (λ) and polished using a polishing machine so that both end faces of the sample were parallel planes perpendicular to the long axis, to give an evaluation sample. 3. Measurement method As shown in FIG. 2, the sample 108 is set on the sample table placed on the optical bench 101, and the diaphragm 104 is adjusted so that the light from the light source 102 is condensed by the condenser lens 103 and the diaphragm. 104
After passing through the glass plate 105 and the entire end face of the sample, adjust the positions of the sample 108 and the polaroid camera 107 so that they are in focus on the polaroid film, take a square lattice image, and distort the lattice. Was observed. As the glass plate 105, a chrome film of chrome-plated glass for a photomask, which was precisely processed into a 0.1 mm square lattice pattern, was used. [Measurement of Refractive Index Distribution] The refractive index distribution was measured by a known method using an Interfaco interference microscope manufactured by Carl Zeiss.

[0016]

Example 1 Poly- (2,2,3,3-tetrafluoropropylmethacrylate) obtained by bulk polymerization (refractive index of homopolymer n _D = 1.420, [η] = 2.285, in MEK at 25 ° C.) Measurement) 50
Parts by weight, methyl methacrylate (refractive index of homopolymer n _D
= 1.498, boiling point 100 ° C) 32 parts by weight, tert-butyl methacrylate (refractive index of homopolymer n _D = 1.483, boiling point 67 ° C / 70mm
Hg) 18 parts by weight, 1-hydroxycyclohexyl phenyl ketone 0.1 parts by weight, and hydroquinone 0.1 parts by weight were charged into the cylinder 11 of FIG. 1, heated to 70 ° C., passed through the kneading part,
It was extruded from a nozzle having a diameter of 2.0 mm. At this time, the viscosity of this precursor composition at the time of extrusion was 1 × 10 ⁴ poise. Subsequently, the extruded fiber was heated to 50 ° C, passed through a volatilization section in which nitrogen gas flows at a rate of 10 liter / min in 8 minutes, and subsequently heated to 80 ° C, and nitrogen gas was fed at a rate of 10 liter / min. The fiber is passed through the center of 500 W ultra-high pressure mercury lamps, which are installed in 6 circles at equal intervals, by passing through the flowing volatile part in 6 minutes, irradiating light for 0.5 minutes, and nip roller at a speed of 20 cm / min. I took it in. The diameter of the obtained fiber was 1.00 mm, and the refractive index profile measured by an interferco interference microscope was 1.448 at the center and 1.431 at the peripheral part, which decreased continuously from the central part to the peripheral part. It was

The results of the composition analysis by NMR of the obtained fiber showed that poly- (2,2,3,3-tetrafluoropropylmethacrylate) was 56% by weight in the central portion and 83% by weight in the peripheral portion. Was included. Methyl methacrylate is 30% by weight in the center and 4% by weight in the periphery, and tert-butyl methacrylate is 14% by weight in the center.
It was 13% by weight in the peripheral portion. The residual monomer content was 1.0% overall. As a result of the above-mentioned measurement of the lens performance, the image of the square lattice has little distortion.

[0018]

Example 2 53 parts by weight of a copolymer (n _D = 1.423) composed of 90% by weight of 2,2,3,3-tetrafluoropropylmethacrylate and 10% by weight of methylmethacrylate produced by bulk polymerization, and 32% of methylmethacrylate. Parts by weight, iso-butyl methacrylate (refractive index of homopolymer n _D = 1.426, boiling point 155
15 parts by weight, 0.1 part by weight of 1-hydroxycyclohexyl phenyl ketone and 0.1 part by weight of hydroquinone were charged into the apparatus shown in FIG. 1 and a fiber having a diameter of 1,000 μm was obtained in the same manner as in Example 1. However, a gradient index optical transmission member was produced in exactly the same manner as in Example 1 except that the temperature of the second volatilization part was 70 ° C. The refractive index distribution of the obtained optical transmission medium measured by an interphaco interference microscope was 1.452 at the center and 1.435 at the peripheral portion, and it continuously decreased from the central portion to the peripheral portion. The composition ratio of 2,2,3,3-tetrafluoropropylmethacrylate copolymer in the light transmitter is 49% by weight in the central part of the light transmitter and 80% by weight in the peripheral part. Is 28% by weight in the central part and 5% by weight in the peripheral part, and iso-butyl methacrylate is in the central part.
It was 22% by weight and 13% by weight in the peripheral portion. As a result of measuring the lens performance, the image has little distortion and is bright.

[0019]

Example 3 Poly- (2,2,3,3-tetrafluoropropyl methacrylate) obtained in Example 1 (n _D = 1.420, [η] =
2.285 at 25 ° C, measured in MEK) 45 parts by weight, methylmethacrylate 30 parts by weight, benzylmethacrylate (refractive index of homopolymer n _D = 1.568, boiling point 160 ° C / 100 mmHg) 25 parts by weight, 1-hydroxycyclohexylphenylketone 1 part by weight and 0.1 part by weight of hydroquinone were charged into the apparatus shown in FIG. 1 and shaped in the same manner as in Example 1 to evaporate the monomer from the strand fiber and polymerize the monomer. Got fiber. However, the temperature of the second volatilization section was 100 ° C. The results obtained were evaluated refractive index distribution type optical transmission article, the refractive index n _D of the central 1.467, the refractive index n _D of the peripheral portion is 1.444, toward the periphery from the center n _D
Was continuously decreasing. The composition ratio of poly- (2,2,3,3-tetrafluoropropyl methacrylate) in the optical transmission medium was 58% by weight in the central part and 82% by weight in the peripheral part. Is 20% by weight in the central portion and 3% by weight in the peripheral portion. The composition ratio of benzyl methacrylate is 22% by weight in the central portion and 15% by weight in the peripheral portion, and methylmethacrylate is 75% by weight in the central portion. The peripheral portion was 65% by weight. As a result of measuring the lens performance,
Although slightly worse than those of Examples 1 and 2, the strain was small.

[0020]

According to the manufacturing method of the present invention, it is possible to solve the absurdity of the prior art, which is caused by the intermittent production process, and to continuously produce the optical transmission body.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for carrying out the method for producing a plastic optical transmission body of the present invention.

FIG. 2 is a conceptual diagram of an apparatus for evaluating the lens performance of the plastic optical transmission article of the present invention.

[Explanation of symbols]

1 ………… Cylinder 2 ………… Kneading part 3 ………… Heater 4 ………… Piston 5 ………… Nozzle 6 ………… Strand fiber 7a ………… First volatile tower 7b …… …… 2nd Volatilizer 8 ………… Actinic ray irradiation part 9 ………… Gas introduction hole 10 ………… Nip roller 11 ………… Winding drum 12 ………… Light transmitter 101 ………… … Optical bench 102 ………… Light source 103 ………… Condensing lens 104 ………… Aperture 105 ………… Glass with chrome film of chrome-plated glass for photomask precision processed into a square lattice pattern of 0.1 mm Plate 106 ………… Sample stand 107 ………… Camera 108 ………… Evaluation sample

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Oda 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. A polymer (A) having a low refractive index N1 and a polymer (A)
Polymers with higher refractive index N2 than those with higher volatility (C) and polymers with higher refractive index N3 than polymers (A)
(D) is given, and a composition obtained by dissolving and mixing the monomer (E) having a lower volatility than the monomer (C) is molded into a desired shape, and a single amount is first added from the surface of the molded product. By subjecting the body (C) to volatilization and then the monomer (E) to volatilize, the monomer is moved from the inside to the surface of the molded article, or from one end surface to the other end surface of the molded article. (C) and monomer (E) in the state where a continuous concentration distribution is provided, the unpolymerized monomer in the molded body
A process for producing a gradient index plastic molding, which comprises polymerizing (C) and a monomer (E).