JPH0122864B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a methacrylic resin composition for optical equipment. Methacrylic resin has excellent weather resistance and aesthetic appearance, as well as excellent mechanical properties and moldability.The molded resin has excellent transparency and useful optical properties, so it is used in various optical applications. It is known that it can be used for equipment. Recently, the camera
2. Description of the Related Art There is a growing tendency to use plastic as a substitute for glass due to demands for lighter weight copying machines and the ease of manufacturing aspherical lenses. Examples of transparent resins with high refractive index include styrene resin, polycarbonate resin, methyl methacrylate-styrene copolymer, and acrylonitrile-styrene copolymer, but all of them have high light dispersion and birefringence due to orientation. Since the refractive index is large and the moldability is poor, there is a demand for a high refractive index methacrylic resin with low light dispersion and low orientation birefringence. It has long been known that cyclohexyl methacrylate, as a homopolymer, has a higher refractive index and better light dispersion properties than other methacrylate-based polymers, and has excellent basic performance as a material for plastic lenses. However, polycyclohexyl methacrylate is extremely brittle and difficult to mold under normal conditions, posing major problems in putting it into practical use. In view of this current situation, the inventors of the present invention conducted intensive studies to develop a resin material with a high refractive index, low light dispersion, and excellent mechanical strength. A methacrylic resin composition consisting of a copolymer mainly composed of methacrylate and a copolymer mainly composed of methyl methacrylate has a high refractive index and low light dispersion without significantly sacrificing the original properties of methacrylic resin. We have discovered that this resin has low water absorption and is suitable for use in optical devices. That is, the present invention comprises 50 to 95% by weight of cyclohexyl methacrylate (A) and 5% by weight of methyl methacrylate (B).
~50% by weight, and 5 to 95 parts by weight of a copolymer () consisting of 0 to 10% by weight of another unsaturated vinyl compound (C) copolymerizable with (A) and (B), and 50% by weight or more of methyl methacrylate. This is a methacrylic resin composition for optical equipment, comprising 95 to 5 parts by weight of a methyl methacrylate polymer (). In the present invention, cyclohexyl methacrylate (A) in the copolymer () increases the refractive index of the final resin composition and is necessary to reduce fluctuations in the refractive index due to water absorption. 50-95% by weight of coalescence () can be used. If the content of (A) is less than 50% by weight, the refractive index of the copolymer will not increase, and if it exceeds 95% by weight, the copolymer will become brittle and cannot be put to practical use. Methyl methacrylate (B) in the copolymer () is necessary to increase compatibility with the methyl methacrylate polymer () and maintain strength, and its content is 5 to 50% by weight of the copolymer (). % can be used. When the content of (B) is less than 5% by weight, the strength becomes weak and the compatibility with the methyl methacrylate polymer () decreases. If the content of (B) exceeds 50% by weight, the refractive index will not increase, and neither is suitable. Other unsaturated vinyl compounds (C) that can be copolymerized with (A) and (B), which can be used as necessary in the copolymer () of the present invention, are used to improve heat-resistant dispersibility during heating. and its blending amount is 10 of the copolymer ()
% by weight or less. Specific examples of the unsaturated vinyl compound (C) include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, styrene, acrylonitrile, etc., but in particular, butyl acrylate, 2-ethylhexyl acrylate, etc. Ethylhexyl acrylate is preferred. The methyl methacrylate polymer () contains 50% by weight or more of methyl methacrylate. If the content of methyl methacrylate is less than 50% by weight, the compatibility with () and the inherent physical properties of the methacrylic resin will be impaired. The resin composition of the present invention is composed of a copolymer () and a methyl methacrylate polymer (), and the blending ratio is 5 to 95 parts by weight of the copolymer () and 95 to 95 parts by weight of the methyl methacrylate polymer (). 5
The parts by weight are necessary to provide high refractive index, low light dispersion, low hygroscopicity and mechanical strength,
Specifically, the blending amount varies depending on the required performance level of the product to be used, but preferably (25)
~70 parts by weight and ()75-30 parts by weight.
If the amount of () is less than 5 parts by weight, the refractive index will not increase and the water absorption will not decrease. On the other hand, if the amount of () is more than 95 parts by weight, the strength of the molded product will be insufficient and cannot be put to practical use. The method for producing the resin composition of the present invention includes a method in which the copolymer () and the methyl methacrylate polymer () are respectively produced by bulk polymerization, suspension polymerization, etc., and then melt-kneaded using an extruder;
Examples include a method of dissolving the copolymer () or the methyl methacrylate polymer () in the monomer mixture constituting the copolymer () or the monomer mixture constituting the copolymer (), followed by bulk polymerization or suspension polymerization. Furthermore, an impact-resistant acrylic resin containing a rubber component may be added as the methyl methacrylate polymer (). Further, if necessary, ultraviolet absorbers, antioxidants, heat stabilizers, etc. may be added. The methacrylic resin composition of the present invention has excellent optical properties as mentioned above, and also has a low water absorption rate, so dimensional changes due to moisture absorption and warpage of molded products are significantly less than conventional methacrylic resins. Therefore, it can be suitably used as a substrate for various optical devices such as plastic lenses, prisms, etc., as well as information recording media such as audio disks, video disks, and information disks for computers. The present invention will be specifically explained below using Examples. Example 1 Methyl methacrylate 300g, cyclohexyl methacrylate 650g, butyl methacrylate 50g
1 g of azobisisobutyronitrile as an initiator, 1 g of n-octyl mercaptan as a chain transfer agent, and 1 g of stearic acid were added to the monomer mixture of g, and mixed and stirred to form water in which 30 g of polyvinyl alcohol was dissolved.
2,000 g of the polymer was placed in a tube, heated and stirred at 80°C for 2 hours to polymerize, and then polymerized at 98°C for 3 hours to obtain a bead-like polymer (). This polymer was washed, dried, and used as a molding material. In addition, 2.5 g of azobisisobutyronitrile and 3.3 g of n-octyl mercaptan as a chain transfer agent were added to a monomer mixture of 1400 g of methyl methacrylate, 540 g of cyclohexyl methacrylate, and 60 g of methyl acrylate, and after stirring, water in which 45 g of polyvinyl alcohol was dissolved was added. 3,000 g of polymer, polymerized at 80°C for 2 hours, then at 98°C for 3 hours, washed and dried to obtain bead-shaped polymers (). 800g of the former copolymer () and the latter copolymer ()
After stirring 1200 g for 2 minutes using a Henschel mixer, the mixture was extruded and shaped at a temperature of 240°C. The obtained polymer was molded at a mold temperature of 60°C and a cylinder temperature of 250°C to produce an injection molded plate of 110 x 110 x 2 m/m. Using this injection molded plate, total light transmittance, parallel light transmittance, haze value, refractive index, water absorption, bending strength, HDT, FR, and hygroscopic strain were measured. The results are shown in Table 1. Comparative Example 1 200 g of methyl methacrylate and 780 g of cyclohexyl methacrylate were prepared in exactly the same manner as in Example 1.
g, a monomer mixture of 20 g of ethyl acrylate was polymerized, the resulting polymer was washed, dried, and manipulated in the usual way, and shaped at 230°C, and the cylinder temperature was 220°C.
Molded at a mold temperature of 65℃, injection molded plate (110 x 110 x
2 mm) was prepared, and the results of evaluation of its physical properties are shown in Table 1. Comparative Example 2 In exactly the same manner as in Example 1, 800 g of a polymer obtained by polymerizing a monomer mixture of 970 g of cyclohexyl methacrylate and 30 g of 2-ethylhexyl acrylate, 700 g of methyl methacrylate,
After kneading and shaping a monomer mixture of 150 g of cyclohexyl methacrylate and 150 g of butyl acrylate with 200 g of a polymer obtained, Table 1 shows the results of evaluating the physical properties of the injection molded plate. Comparative Example 3 In exactly the same manner as in Example 1, a monomer mixture of 900 g of methyl methacrylate and 100 g of methyl acrylate was polymerized, the resulting polymer was kneaded and shaped, and then molded and evaluated for physical properties using an injection molded plate. The results are shown in Table 1.

[Table] Example 2 300 g of methyl methacrylate in a 3-separable flask equipped with a condenser, stirrer, and thermometer.
Add 700g of cyclohexyl methacrylate monomer mixture, and add 22 n-octyl mercaptan.
g, add 0.6 g of azobisvaleronitrile, and heat to 100°C.
The mixture was heated for 10 minutes for polymerization to obtain a partially polymerized product. Add 0.2 g of azobisvaleronitrile to 500 g of this partially polymerized product, dissolve it, and then inject it into a glass cell.
After polymerization at 65° C. for 4 hours, polymerization was further carried out at 120° C. for 2 hours, and the obtained sheet-like polymer having a thickness of about 4 mm was ground into pellets. () Meanwhile, in exactly the same manner as in Example 1, 900 g of methyl methacrylate, 80 g of butyl acrylate,
A monomer mixture containing 20 g of styrene was polymerized to obtain a bead-shaped polymer. () 400g of the former copolymer () and the latter copolymer ()
After kneading and shaping, 600 g of the injection molded plate was molded, and the physical properties of the injection molded plate were evaluated. The results are shown in Table 2. Example 3 200 g of methyl methacrylate and 800 g of cyclohexyl methacrylate were prepared in exactly the same manner as in Example 1.
300g of polymer obtained by polymerizing 500g of methyl methacrylate, cyclohexyl methacrylate
Dissolved in 200 g of monomer mixture, 0.2 g of azobisvaleronitrile, Tinuvin P (manufactured by Ciba Geigy)
Add 0.3g of ultraviolet absorber (trade name), melt it, inject it into a glass cell, polymerize at 65℃ for 4 hours, and then further heat at 120℃ for 2 hours to obtain a sheet-like polymer with a thickness of 2mm. . The physical properties of this polymer are shown in Table 2. Example 4 Put 3000 g of water into a separable flask equipped with a stirrer, condenser, and thermometer, and add 30 g of emulsifier Sarcosinate LN (manufactured by Nikko Chemicals) to it.
Dissolve 0.015 g of iron sulfate, 0.06 g of ethylenediaminetetraacetate disodium salt, and 4.5 g of initiator t-butyl hydroperoxide.
A monomer mixture of 600 g of methyl methacrylate and 900 g of cyclohexyl methacrylate in which 3 g of n-octyl mercaptan was dissolved was added and polymerized at 65°C to obtain a latex. Latex at 80℃ 0.67
% aqueous sulfuric acid solution and coagulated, dehydration, washing, and drying were performed. 350g of the obtained polymer and
In exactly the same manner as in Example 1, 800 g of methyl methacrylate, 130 g of cyclohexyl methacrylate,
After kneading and shaping 650 g of a polymer obtained by polymerizing a monomer mixture of 70 g of ethyl acrylate,
The physical properties of the injection molded plate were evaluated. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. 50 to 95% by weight of cyclohexyl methacrylate (A), 5 to 50% by weight of methyl methacrylate (B), and other unsaturated vinyl compound (C) copolymerizable with (A) and (B).
A methacrylic resin composition for optical equipment comprising 5 to 95 parts by weight of a copolymer () containing 0 to 10% by weight and 95 to 5 parts by weight of a methyl methacrylate polymer () containing 50% by weight or more of methyl methacrylate. . 2 Other unsaturated vinyl compounds copolymerizable with (A) and (B)
2. The methacrylic resin composition for optical equipment according to claim 1, wherein (C) is an alkyl acrylate or alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms.