JPS61174208A - Production of resin for molding optical disc - Google Patents

Abstract

PURPOSE:To produce a resin for molding an optical disc enhanced in heat resistance and hardness and decreased in water absorptivity, by radical- polymerizing a specified acrylic compound. CONSTITUTION:A compound of the formula (wherein R is H or CH3) is subjected to radical polymerization carried out either by adding a radical initiator such as an organic peroxide or an azo compound to an acrylic compound of the formula and curing the mixture by heating, or by adding a photosensitizer thereto and curing the mixture by irradiation with ultraviolet rays, electron beams, radiations or the like. Examples of said radical initiators include benzoyl peroxide and azobisisobutyronitrile, which is used preferably in an amount of 0.01-10pts.wt. per 100pts.wt. acrylic compound of the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a resin for a molding material for optically readable discs (video discs, memory discs, digital audio discs, etc.).

(Prior art) Optical discs have many characteristics such as extremely high recording density and excellent image and sound quality reproduced from them, so they are widely used for recording and reproducing images and audio, storing and reproducing large amounts of information, etc. It is hoped that this will be put into practical use.

Taking a memory disk as an example, inorganic glass and polymethyl methacrylate resin are used as disk materials. However, when inorganic glass is used as a disc material, it has no moisture permeability and therefore has little adverse effect on the recording layer, but it is heavy and easy to break. Further, there are drawbacks such as the high precision processing of the glass. On the other hand, polymethyl methacrylate resin has advantages such as being less likely to break and being cheaper than glass, but it is easily scratched and lacks optical stability. In addition, due to its low heat resistance and high moisture absorption, the disc is easily warped, which causes the aperture lens in the recording and reproducing optical system to become out of focus, causing malfunctions, which is a fatal flaw. However, there is a strong desire to improve these drawbacks.

(Problems to be Solved by the Invention) In view of the above-described circumstances, the present invention is to provide a disk molding material having high heat resistance, high hardness, and low water absorption.

(Specific Means for Solving All Problems) The present invention provides a resin for optical disk molding material which is characterized by radically polymerizing a compound represented by the general formula [wherein R is H or CI (3)]. A manufacturing method is provided.

The resin for optical discs can be obtained by curing the acrylic compound represented by the above general formula in the same manner as the commonly used radical polymerization method. for example,
A radical initiator such as an organic peroxide or an azo compound is blended into this acrylic compound and cured by heating, or a photosensitizer is blended and the radical is cured by irradiation with ultraviolet rays, electron beams, radiation, etc. Can be polymerized. In addition, the radical initiator used at that time is not particularly limited, and examples thereof include organic peroxides such as benzoyl peroxide, diisopropyl peroxide, tertiary-butyl peroxyvivalate, and lauroyl peroxide; Compounds: Radical initiators such as photosensitizers such as benzophenone, benzoin ethyl ether, benzyl, acetophenone and anthraquinone, and sulfur compounds such as diphenyl sulfite and thiocarbamate can be used.

The amount of the radical initiator used is in the range of 0.01 to 20 parts, more preferably 0.0 parts to 10 parts, based on 100 parts of the acrylic compound represented by the above general formula.

Furthermore, in addition to the acrylic compound represented by the above general formula, radically polymerizable monomers used as known disc molding materials, specifically diethylene glycol bisallyl carbonate, diallyl phthalate, 4.4'-
It is also possible to use bis(β-methacroylethoxy)diphenylpropane or the like in combination without deteriorating the excellent properties of the present invention.

The radical polymerization of the present invention is preferably carried out in the atmosphere at a temperature of 10 to 150°C.

This? The resin obtained has a light transmittance of 8.5% or more, a birefringence of I x 10"-5 or less, and a heat resistance of 200°C or more (with a pencil strength of 2 parts or more). .

Examples are shown below. In addition, parts in the examples are parts by weight, and percentages are based on weight.

In addition, various physical properties obtained in the examples were measured by the following test methods.

(1) Light transmittance: Measure the light transmittance at 500°C using a spectrophotometer.

(2) Birefringence: Measured using a polarizing microscope.

(3) Heat resistance: Measured using a heat deformation tester according to ASTM-D-648.

(4) Hardness: Measured using a pencil hardness tester according to JIS-6911.

(5) Water absorption rate: Measured according to JI S-6911.

Example 1 Bis(oxymethyl)tricyclo(s,2.x,o2I
5] Add 0.5 parts of benzoyl peroxide to 100 parts of decane dimethacrylate, heat to 60°C, stir and mix uniformly, defoamer, and pour this liquid into a tube with a diameter of 120 vw.
The mixture was poured into a mold consisting of a glass plate and a silicone rubber spacer, and polymerization was carried out by holding the mixture at 60°C for 24 hours, at 80°C for 2 hours, and at 100°C for 2 hours.

The cured product was taken out from the mold to obtain a disk substrate with a diameter of 120 m. The evaluation results of various physical properties of the disk substrate are shown below.
Shown in 1.

Example 2 Bis(oxymethyl)tricyclo(5,2,1,02・
5] Add 3 parts of benzoin ethyl ether to 100 parts of decarbonized diacrylate, heat to 60°C, stir and mix uniformly, defoamer, and mix the liquid with a glass plate and a silicone rubber spacer. It was poured into a mold and irradiated with ultraviolet rays for 1 minute using a high-pressure mercury lamp with an output of 80 W/tm to perform polymerization.

The cured product was taken out from the mold to obtain a disk substrate with a diameter of 120 mm. Table 1 shows the evaluation results of various physical properties of the disk substrate.
Shown below.

Comparative Example 1 Bis(oxymethyl)tricyclo(5,2,
1,02"5] Using 100 parts of methyl methacrylate and 0.5 parts of benzoyl peroxide instead of decane dimethacrylate, a diameter of 1
A disk substrate of 20 cm was obtained.

Table 1 shows the evaluation results of various physical properties of the disk substrate.

Comparative Example 2 Instead of methyl methacrylate in Comparative Example 1, 4゜4'-
Bis(β-methacroyloxyethoxy) diphenylpropane i o o parts and pensoyl peroxide 0.
Using 5 parts, the diameter was 120w using the same method as in Example 1.
n disk substrates were obtained. Table 1 shows the evaluation results of various physical properties of the disk substrate.

(Margin below)

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum diagram of the cured product obtained in Example 1.

Claims (1)

[Claims] General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R is H or CH_3. ] A method for producing a resin for optical disc molding material, which comprises radically polymerizing a compound represented by: