JPH0216504A - Production of plastic light transmission body - Google Patents

Abstract

PURPOSE:To allow continuous production and to allow the production of the light transmission body having good transparency by concentrically extruding a polymerizable mixture composed of a polymer essentially consisting of methyl methacrylate and a monomer which is liquid at ordinary temp. as the laminate of >=2 kinds of the polymerizable mixtures having different refractive indices and subjecting the laminate to polymn. curing. CONSTITUTION:The monomer which is liquid at ordinary temp. includes methyl (meth)acrylate and ethyl (meth)acrylate. A copolymer of the homopolymer of methyl methacrylate and the monomer thereof is used as the polymer essentially consisting of the methyl methacrylate. The distributed index type light transmission body 6 is obtd. by concentrically extruding 1, >=2 kinds of the polymerizable mixtures having the different refractive indices, diffusing 3 the monomers of the polymerizable mixtures between the respective layers to each other to form a distributed index type yarn-like object 2 and subjecting the object to a curing treatment 4. The distributed index type plastic light transmission body 6 having good flexibility is continuously and efficiently produced in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention has a continuous refractive index distribution from the surface to the inside,
The present invention relates to a method of manufacturing a plastic optical transmission body used for a light-focusing lens, a light-focusing optical fiber, an optical IC, etc.

[Conventional technology]

As an optical transmission body having a continuous refractive index distribution from the surface to the inside, a glass one has already been proposed in Japanese Patent Publication No. 47-816. However, optical transmission bodies made of glass have the problems of low productivity (and high price), and poor flexibility.In contrast to such optical transmission bodies made of glass, optical transmission bodies made of plastic Several methods have been proposed for manufacturing these plastic light transmitting bodies, which have a continuous refractive distribution from the surface to the inside. The metal ions have a continuous concentration change toward the surface (%Koshō 47-269).
(Refer to Publication No. 16), (2) A synthetic resin body manufactured from a mixture of two or more transparent polymers having different refractive indexes is treated with a specific solvent to reduce the amount of the constituent components of the synthetic resin body (
(Refer to Japanese Patent Publication No. 47-28059) (5)
) Two types of monomers with different refractive indexes are manufactured by devising a polymerization method to create a continuous refractive index distribution from the surface to the inside (see [Refer to Publication No. 54-50301), (4) A crosslinked polymer in which a monomer with a refractive index lower than that of the polymer is diffused from the surface of the polymer, arranged so that the content of the monomer changes continuously from the surface to the inside, and then polymerized to give a refractive index distribution. (Refer to Japanese Patent Publication No. 52-5857 and Japanese Patent Publication No. 56-57521), and (5) Diffusing and reacting a low-molecular compound having a refractive index lower than that of the polymer from the surface of the reactive polymer. (See Japanese Patent Publication No. 57-29682) in which a continuous refractive index distribution is provided from the surface to the inside.

[Problem to be solved by the invention]

These conventional methods require a long time for processes such as diffusion or extraction, the length of the optical transmission body is limited, the production process is intermittent, so productivity is extremely low, and the selection of manufacturing conditions is difficult. This method has problems such as being extremely difficult and not reproducible.

The present invention solves the unreasonableness of the conventional intermittent production process, enables continuous production, and provides a method for manufacturing an optical transmission body with good transparency.

[Means to solve the problem]

The present invention involves extruding a polymerizable mixture of a polymer mainly composed of methyl methacrylate and a monomer that is liquid at room temperature in a concentric circle as a laminate of two or more polymerizable mixtures having different refractive indexes. This is a method of manufacturing a plastic light transmitting body, characterized in that the light transmitting body has a refractive index that changes sequentially from the inside toward the surface by polymerization and curing.

Examples of monomers that are liquid at room temperature that can be used in the present invention include the following compounds. Methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate,
Tertiary butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-(n-butoxy)ethyl (meth)acrylate,
Monofunctional (meth)acrylates such as glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2=2*2)lifluoroethyl (meth)acrylate , 2,2,3.3-tetrafluoropropyl (meth)acrylate, 2.2.3,3.
3-pentafluoropropyl (meth)acrylate, 2
,2,3,4,4,4-hexafluorobutyl (meth)
Acrylate, 2,2. ! 1. ．． 5,4,4,5,5-
Fluorinated alkyl (meth)acrylates such as octafluoropentyl (meth)acrylate, alkylene glycol di(meth)acrylate, trimethylolpropane di- or tri(meth)acrylate, pentaerythritol di-, tri- or tetra(meth)acrylate, di- Polyfunctional (meth)acrylates such as glycerin tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, diethylene glycol bisallyl carbonate, fluorinated alkylene glycol poly(meth)acrylate, acrylic acid, methacrylic acid, styrene , chlorstyrene, etc.

As the polymer mainly composed of methyl methacrylate, a homopolymer of methyl methacrylate and a copolymer of methyl methacrylate and the above-mentioned monomers are used.

When carrying out the present invention, a polymerizable mixture of two or more types having different refractive indexes is prepared, which is composed of a polymer mainly composed of methyl methacrylate and a monomer that is liquid at room temperature.

Polymerizable mixtures having different refractive indexes can be prepared by changing the types, blending amounts, etc. of polymers and/or monomers. At that time, a thermosetting catalyst and/or a photocuring catalyst is also added.

A common peroxide catalyst is used as the thermosetting catalyst. As a photopolymerization catalyst, penzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-2-methyl-propiophenone, 1-hydroxycyclohexylphenyl ketone, benzyl methyl ketal, 2,2-jethoxyacetophenone, Examples include chlorothioxanthone, thioxanthone compounds, benzophenone compounds, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N-methyljetanolamine, and triethylamine.

The polymerizable mixture must have a viscosity of 103 to 105 voids and be curable. If the viscosity is lower than 103 poise, yarn breakage occurs during spinning, making it difficult to form a filament.

Furthermore, if the viscosity is greater than 105 voids, the spinning operability will be poor and it will be difficult to obtain a filament with less uneven diameter.

Next, two or more types of polymerizable mixtures having different refractive indexes are extruded concentrically, and while passing through a guide tube made of quartz glass, the monomers of the polymerizable mixture between each layer are mutually diffused and refracted. After being made into an index distribution type filament, a curing treatment is performed to obtain a refractive index distribution type optical transmission body. In the monomer interdiffusion section, the filamentous material can be heated if necessary.
In any case, it is kept in an uncured state during that time.

Next, in order to cure the uncured filament, the filament containing the thermosetting catalyst and/or photocuring catalyst is subjected to heat treatment or light irradiation treatment, preferably by applying ultraviolet rays from the surroundings in the curing section.

The present invention can be carried out using, for example, the thread forming apparatus shown in FIG. Figure 1 is a process diagram that schematically shows the yarn forming device, with only the interdiffusion section and the hardening section shown in longitudinal section. In the figure, symbol 1 is a concentric compound nozzle, and symbol 2 is an extruded nozzle. An uncured thread-like material, 6 a mutual diffusion section for mutually diffusing monomers in each layer of the thread-like material to provide a refractive index distribution, 4 a curing section for curing the uncured material, 5
6 is a take-up roller; 6 is a manufactured refractive index distribution type plastic optical transmission body; 7 is a winding section; 8 is an inert gas inlet; and 9 is an inert gas outlet. In order to remove volatile substances liberated from the filamentous material 2 from the interdiffusion section 6 and the curing section 4, an inert gas such as nitrogen gas is introduced from the inert gas inlet 8.

The gradient index optical transmission body of the present invention may further be provided with a coating layer having a low refractive index. To form the coating layer, trifluoroalkyl acrylate, pentafluoroalkyl acrylate, hexafluoroalkyl acrylate, fluoroalkylene diacrylate, 1
．． L2,2-tetrahydrohebbutadecafluorodecyl acrylate, hexanediol diacrylate, neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, etc. are mixed as appropriate, and the above-mentioned ingredients are added to adjust the coating properties and refractive index as necessary. It is preferable to use a polymer in which a fluorinated acrylate or methacrylate polymer is added thereto, and the photopolymerization initiator described above is further added thereto.

As light sources for photopolymerization, carbon arc lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, chemical lamps, xenon lamps, laser beams, etc. that emit light with a wavelength of 150 to 600 nm are used.

[Effects of the present invention]

According to the present invention, it is possible to continuously and efficiently manufacture a gradient index plastic optical transmission body having good flexibility.

Furthermore, by changing the refractive index of the components of each layer of the gradient index plastic optical transmission body and the thickness of each layer, it is possible to easily control the refractive index distribution, which has been extremely difficult with conventional techniques.

Lens performance and refractive index distribution in the following examples were measured by the following method.

(2) Measurement and Evaluation Apparatus for Lens Performance Lens performance was measured using the evaluation apparatus shown in FIG.

He-N passing through the optical transmission body obtained in Sample Preparation Example
e FR4W of the light beam determined from the undulation of the laser beam (
2) The sample was cut to a height of 4 mm and η/l/·\, and polished using a polisher so that both end surfaces of the sample became parallel planes perpendicular to the long axis, and used as an evaluation sample.

Measurement method: Set the prototype evaluation sample (18) on the sample stage (16) placed on the optical bench (11), and
4) so that the light from the light source (12) passes through the condensing lens (
13), an aperture (14), and a glass plate (15) provided with a square grating image, so that the light enters the entire end face of the sample (18), and then the sample (18) and the Polaroid camera (
j7) was adjusted so that it was in focus on the Polaroid film, a square grid image was taken, and the distortion of the grid was observed. The glass plate (15) used was a chrome-plated photomask glass plated with a chrome coating precision-processed into a 0.1 m 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 Polymethyl methacrylate ([η) = 0.56, MEK
, 25°C) 46 parts by weight, benzyl methacrylate 44
parts by weight, 10 parts by weight of methyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone, and 0.1 parts by weight of hydroquinone were heated and kneaded at 70°C to prepare a first mixture.
This was used as the stock solution for the layer (center). Further, 50 parts by weight of polymethyl methacrylate ([η)=0.41, MEK, 25°C), 50 parts by weight of methyl methacrylate, 1 ciL part of 1-hydroxycyclohexylphenyl ketone, and 0.1 part by weight of hydroquinone were added at 70°C. Heat and knead to form the second layer (
Peripheral area) was used as a stock solution. Both stock solutions were simultaneously extruded using a concentric compound nozzle to prepare a filamentous material. The viscosity during extrusion was 4.5'×10 poise for the first layer stock solution and 2.0×10 poise for the second layer stock solution. Further, the heat retention temperature of the composite nozzle was 55°C.

Next, using the apparatus shown in Figure 1, the fiber was passed through a mutual diffusion section with a length of 90 crn, and then placed in the center of a quartz tube around which 12 40 W fluorescent lamps with a length of 120 crn were installed at equal intervals. was passed through the fiber at a speed of 25 Crr/min to cure it, taken up with a nip roller, and wound on a winder to obtain a fiber with a diameter of 1000 μm.

When the ejection ratio is 1st layer: 2nd layer = 1:2, the refractive index distribution measured with an Interfaco interference microscope (manufactured by Carl Zeiss, East Germany) is 1.515 at the center and t4 at the periphery.
94, and the refractive index decreased continuously from the center to the periphery.

The total amount of residual methyl methacrylate and benzyl methacrylate was 0.7% by weight. Furthermore, as a result of measuring the lens performance, the image of the square grating had less distortion.

In addition, when the ejection ratio is 1st layer: 2nd layer = 1 = 1, the fiber has a diameter of 1050 μm, and the refractive index distribution is 1 at the center.
．． 519 and 1.495 at the periphery, decreasing continuously from the center to the periphery. The total amount of residual monomers was 0.8% by weight. Furthermore, as a result of measuring the lens performance, the image of the square grating had less distortion. In this way, by changing the discharge ratio of the stock solution, the refractive index distribution became different.

Example 2 The stock solution used in Example 1 was used for the first and second layers, and polymethyl methacrylate ([η] = 0.3
4, MEK, 25°C) 45 parts by weight, 2.2, 3, 3, 4
, 35 parts by weight of 4,5,5-octafluoropentyl methacrylate, 20 parts by weight of methyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 70°C. The stock solutions of the first layer, second layer, and sixth layer were extruded simultaneously using a concentric compound nozzle to prepare a filamentous material. The viscosity during extrusion is 4゜5X10' for the first layer stock solution.
Boys, the stock solution of the second layer is 2. OX 10' poise, the stock solution for the third layer was 2.2 x 10' poise. The heat retention temperature of the composite nozzle was 60°C.

Next, using the apparatus shown in FIG. 1, a fiber with a diameter of 1000 μm was obtained in the same manner as in Example 1 (interdiffusion part 45cr
11).

When the ejection ratio is 1st layer: 2nd layer: 3rd layer = 1:i:1,
The refractive index distribution measured using an Interfaco interference microscope is 1.512 at the center and 1.470 at the periphery. The refractive index decreased continuously from the center to the periphery. Methyl methacrylate, 2.2, 5.3, 4.4, 5
．． The residual monomer content of 5-octafluoropentyl methacrylate and benzyl methacrylate was 1.2% by weight. Furthermore, as a result of measuring lens performance, the square lattice image had less distortion. In this case as well, by changing the ejection ratio, optical transmission bodies having various shapes of refractive index distributions were obtained.

Example 6 The stock solution of the first layer used in Example 1 was used as the first layer, polymethyl methacrylate ([η)=0.40, MEK.

25°C), 20 parts by weight of methyl methacrylate, 30 parts by weight of benzyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 65°C to form the second layer. It was used as a stock solution. In addition, the stock solution of the second layer used in Example 1 was added to the sixth layer.
Polymethyl methacrylate ([η
]=0.40, MEK, 25°C) 50 parts by weight, 30 parts by weight of methyl methacrylate, 20 parts by weight of 2,2.3.3-tetrafluoropropyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone Parts by weight and 061 parts by weight of hydroquinone were heated and kneaded to prepare a stock solution for the fourth layer. The four stock solutions described above were simultaneously extruded using a concentric compound nozzle to prepare a filamentous material. The viscosity during extrusion is 4.5 x 10'poise for the first layer stock solution, 4.0 x 10'poise for the second layer stock solution, and 2.0XI for the third layer stock solution.
G Boise, the stock solution of the fourth layer was 2.2×10 poise.

The heat retention temperature of the composite nozzle was 60°C.

Next, using the apparatus shown in FIG. 1, a fiber with a diameter of 1050 μm was obtained in the same manner as in Example 1 (interdiffusion part 30c
rIT).

Ejection ratio is 1st layer: 2nd layer: 3rd layer: 4th layer = 2:1:
In the case of 1:1, the refractive index distribution measured by an interfaco interference microscope is 1.511 at the center and 1.4 at the periphery.
79, and decreased continuously from the center to the periphery. The residual monomer content was 1.1% by weight. At this time, since 2.2.5.3-tetrafluoropropyl methacrylate was slightly volatilized, the refractive index distribution was slightly raised at the peripheral portion. Therefore, when we measured the lens performance, we found that the square lattice image was distorted at its periphery.

Example 4 Using the stock solutions from the first layer to the fourth layer used in Example 6,
Further, the stock solution used in the third layer of Example 2 was used for the fifth layer, and the stock solutions from the first layer to the fifth layer were simultaneously extruded using a concentric compound nozzle to prepare a filamentous material. A fiber was obtained in the same manner as above (interdiffusion part 20 crn
).

The ejection ratio is 1st layer: 2nd layer: 6th layer: 4th layer: 5th layer = 4
:1 :1 :1 :2, the refractive index distribution measured by an interfaco interference microscope shows that the residual monomer content is 1.
It was 0% by weight.

As a result of measuring lens performance, the square lattice image had less distortion. In this case as well, the refractive index distribution became different by changing the discharge ratio of the stock solution.

Example 5 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 parts by weight of hydroquinone were added to the ingredients shown in the batter below, and the mixture was heated and kneaded at 70°C to prepare stock solutions for layers 1 to 10. . These 10 kinds of stock solutions were simultaneously extruded using a concentric compound nozzle to prepare a filamentous material. The viscosity of each stock solution during extrusion was as shown in the table. Further, the heat retention temperature of the composite nozzle was 60°C. Next, the filamentous material was immediately cured in the same manner as in Example 1 without undergoing interdiffusion treatment to obtain a fiber.

When the ejection ratios in the table were used, the refractive index distribution measured by an interfaco interference microscope was 1.512 at the center and 1.472 at the periphery, and decreased continuously from the center to the periphery. In addition, as a result of measuring lens performance,
There was very little distortion of the square. By changing the ejection ratio, optical transmission bodies having various shapes of refractive index distributions were obtained.

Example 6 Polymer consisting of 65% by weight of methyl methacrylate and 65% by weight of phenyl methacrylate (nD=1.517,
[η] = 1.50, 47 parts by weight of MEK, 256c), 56 parts by weight of phenyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 65°C. This was used as the stock solution for the first layer. Further, 50 parts of the same polymer, 50 parts of methyl methacrylate, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were heated and kneaded at 65 DEG C. to prepare a stock solution for the second layer. These stock solutions were treated in the same manner as in Example 1 to obtain fibers (interdiffusion section 90CrrI).

The viscosity of the first layer stock solution at the time of discharge was 4. OX 10'Boys, the stock solution of the second layer is 2. It was lx10 bois. Further, the heat retention temperature of the composite nozzle was 60°C.

When the ejection ratio is 1st layer: 2nd layer = 1 = 1, the obtained fiber has a diameter of 10oOμm, and the refractive index distribution is 1.540 at the center and 1.511 at the periphery. It decreased continuously towards the periphery. The residual monomer content was 1.0% by weight. Furthermore, as a result of measuring the lens performance, the image of the square grating had less distortion. In this case as well, the refractive index distribution became different by changing the discharge ratio of the stock solution.

[Brief explanation of the drawing]

Fig. 1 is a process diagram schematically showing a thread forming apparatus used in carrying out the present invention, in which only the interdiffusion section and the curing processing section are shown in longitudinal section, and Fig. 2 is a process diagram schematically showing the thread forming apparatus used in carrying out the present invention. 1 is a partially longitudinal side view schematically showing a lens performance measuring device used for body evaluation, in which symbol 1 is a concentric compound nozzle, 2 is a filamentous material, 3 is a mutual diffusion part, and 4 is a hardening treatment. Part, 6
is a light transmission body, 12 is a light source, 16 is a lens, 14 is an aperture,
15 is a glass plate, 17 is a camera, and 18 is a sample.

Claims (1)

[Claims] A polymerizable mixture of a polymer mainly composed of methyl methacrylate and a monomer that is liquid at room temperature is extruded concentrically as a laminate of two or more polymerizable mixtures with different refractive indexes, and then polymerized and cured. A method for manufacturing a plastic optical transmission body, characterized in that the optical transmission body has a refractive index that changes sequentially from the inside toward the surface.