JPS61176618A - Production of resin for molding material of optical disk substrate - Google Patents

Abstract

PURPOSE:To obtain the titled resin having high heat resistance, high hardness and low water absorption, by radically polymerizing an acrylic compound having a specific structural formula. CONSTITUTION:Preferably 0.01-0.1pts.wt. radical initiator, e.g. benzoyl peroxide, is added to a compound expressed by the formula (R is H or CH3), e.g. 1,4-bis(methacryloyloxymethyl)cyclohexane, and reacted therewith at 10-150 deg.C preferably in the air to give the aimed resin having generally >=85% light transmittance, <=1X10<-5> birefringence, >=200 deg.C heat resistance and >=2H pencil hardness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a resin for a substrate 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 memory disks as an example, inorganic glass and polymethyl methacrylate resin are practically used as optical disk substrate materials. However, when inorganic glass is used as a disc material, it has no moisture permeability, so although it has little negative effect on the recording layer, it is heavy and easily broken. 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 prone to warping, which causes the aperture lens in the recording and reproducing optical system to become out of focus, resulting in a fatal flaw, causing malfunction. Therefore, it is strongly desired 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 the problems) The present invention is based on the general formula (1) [wherein R is H or a mountain]. ] Provided is a method for producing a resin for optical disk substrate molding material, which is characterized by radically polymerizing a compound represented by the following.

The resin for optical disk substrates can be obtained by curing the acrylic compound represented by the general formula (D) in the same manner as the commonly used radical polymerization method.

For example, methods include adding a radical initiator such as an organic peroxide or an azo compound to the acrylic compound and curing it by heating, or adding a photosensitizer and curing it by irradiating it with ultraviolet rays, electron beams, radiation, etc. Radical polymerization can be carried out by

Further, the radical initiator used at that time is not particularly limited, and examples include benzoyl peroxide, diisopropyl peroxide, tert-butyloxypivalate,
Organic peroxides such as lauroyl peroxide, azo compounds such as azoisobutyronitrile; photosensitizers such as benzophenone, benzoin ethyl ether, benzyl, acetophenone, and anthraquinone; radical initiators such as sulfur compounds such as diphenyl sulfite and thiocarbamate. Can be used. The amount of the radical initiator used is 0.01 to 20 parts per 100 parts of the acrylic compound represented by the above general formula,
More preferably, it is in the range of 0.01 to 10 parts.

Furthermore, in addition to the acrylic compound represented by the general formula (I), radically polymerizable monomers used as known disc molding materials, specifically diethylene glycol bisallyl carbonate, Schiff 1J ruphthalate, 4
．． It is also possible to use 4'-bis(β-methacroylethoxy)diphenylpropane or the like in combination without deteriorating the excellent properties of the present invention.

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

The resin thus obtained has a light transmittance of 85% or more,
It has a birefringence index of I x 10''-5 or less, a heat resistance of 200° C. or more, and a pencil hardness 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 so nm using a two-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 0.0 parts of benzoyl peroxide was added to 100 parts of 1.4-bis(methacroyloxymethyl)cyclohexane.
After adding 5 parts and heating to 60°C, stirring and mixing uniformly, defoaming, pouring this liquid into a mold consisting of a glass plate with a diameter of 12 (1 m) and a silicone rubber spacer,
Polymerization was carried out by holding at 100°C for 24 hours, 80°C for 2 hours, and 100°C for 2 hours.

The cured product was taken out from the mold to obtain a disk substrate with a diameter of 120 cm. The evaluation results of various physical properties of the disk substrate are shown below.
Shown in 1. Furthermore, an infrared absorption spectrum diagram of the cured product is shown in FIG.

Example 2 3 parts of benzoin ethyl ether was added to 100 parts of 1.4-bis(acroyloxymethyl)cyclohexane, heated to 60°C, stirred and mixed uniformly, defoamed, and poured the liquid onto a glass plate. The mixture was poured into a mold made of a silicone rubber spacer and irradiated with ultraviolet rays for 1 minute using a high-pressure mercury lamp with an output of 80 W/cm to perform polymerization.

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

Comparative Example 1 1,4-bis(methacroyloxymethyl) of Example 1
Methyl methacrylate 100 instead of cyclohexane
A disk substrate having a diameter of 120 mm was obtained in the same manner as in Example 1 using 0.5 parts of benzoyl peroxide and 0.5 parts of benzoyl peroxide. 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'-
A disk substrate having a diameter of 120 mm was obtained in the same manner as in Example 1 using 100 parts of bis(β-methacroyloxyethoxy)diphenylpropane and 0.5 parts of benzoyl peroxide. Table 1 shows the evaluation results of various physical properties of the disk substrate.

[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 substrate molding material, which comprises radically polymerizing a compound represented by: