JP2501561B2 - Optical disc material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc material.

More specifically, the present invention relates to an optical disk material having excellent heat resistance and transparency and a small birefringence.

[Conventional technology and problems]

In recent years, the demand for plastic materials as optical element materials is expanding, and transparent resins such as polymethylmethacrylate, polystyrene, and polycarbonate are currently used as optical element materials, but all have difficulty in heat resistance and dimensional stability. There is.

The properties required of the optical disc material are dimensional stability under environmental conditions and heat resistance.

Polymethylmethacrylate resin is currently the most commonly used material for optical disk substrates for injection molding. Polycarbonate resins are also in practical use, but they are unsuitable for large discs and have excellent heat resistance, but have poor moldability and large birefringence due to molding strain.

Polymethylmethacrylate and polystyrene have excellent moldability, but have poor heat resistance and cannot withstand use under high temperature conditions. In addition, polymethylmethacrylate is particularly excellent in optical properties, but has a drawback that it has a large elongation due to moisture absorption, it greatly warps when a reflecting film is provided on one side, and the focus surface is deformed by the thermal energy of laser light. .

[Means for solving problems]

As a result of studies aimed at solving the above-mentioned drawbacks, the present inventors have combined an imidized copolymer having a specific composition with a copolymer composed of an aromatic vinyl monomer and a vinyl cyanide monomer. It was found that by doing so, an optical disk material having excellent heat resistance, transparency and moldability and having a small birefringence can be obtained.

That is, the present invention relates to (A) component: aromatic vinyl monomer residue 30 to 79% by weight, N-phenylmaleimide monomer residue 20 to 60% by weight, maleic anhydride monomer residue 1 to 10 10 to 90 parts by weight of an imidized copolymer consisting of 0 to 40% by weight of vinyl monomer residues other than these, and (B) component: 40 to 80% by weight of aromatic vinyl monomer, cyanated The present invention provides an optical disk material comprising 10 to 90 parts by weight of a copolymer composed of 0 to 40% by weight of a vinyl monomer and 0 to 40% by weight of a residue of a vinyl monomer other than these. .

In the present invention, the optical disc specifically includes a video disc, an audio disc, a file disc, and the like.

First, the imidized copolymer as the component (A) and a method for producing the same will be described.

The method for producing the imidized copolymer of the component (A) is as follows:
A method of copolymerizing an aromatic vinyl monomer, an N-phenylmaleimide monomer, a maleic anhydride monomer, and a mixture of vinyl monomers copolymerizable with these monomers. As a production method, an aromatic vinyl monomer, a maleic anhydride monomer and a polymer obtained by copolymerizing a mixture of vinyl monomers copolymerizable with these monomers are added to the acid anhydride group in the polymer. There may be mentioned a method of reacting with aniline to convert a part of the acid anhydride group into an imide group, and an imidized copolymer can be obtained by any method.

The aromatic vinyl monomer used in the first production method of the imidized copolymer (A) is a styrene-based monomer such as styrene, α-methylstyrene, vinyltoluene, t-butylstyrene or chlorostyrene. And styrene as a substitution monomer thereof, of which styrene is particularly preferable.

As the aromatic vinyl monomer used in the second production method, the one used in the first production method can be used.

Further, in the first and second production methods, as the vinyl monomer copolymerizable with the aromatic vinyl monomer, the maleic anhydride monomer and the N-phenylmaleimide monomer, acrylonitrile, methacrylonitrile, Vinyl cyanide monomer such as α-chloroacrylonitrile, methacrylic acid ester monomer such as methyl acrylic acid ester and ethyl acrylic acid ester, methacrylic acid ester monomer such as methyl methacrylic acid ester and ethyl methacrylic acid ester,
There are vinylcarboxylic acid monomers such as acrylic acid and methacrylic acid, and acrylic acid amides and methacrylic acid amides. Among these, acrylonitrile, methacrylic acid ester, acrylic acid and methacrylic acid are preferred.

In the second production method, when the imidization reaction is carried out in a solution state or a suspension state, it is preferable to use an ordinary reaction vessel, for example, an autoclave, and when it is carried out in a bulk molten state, an extruder equipped with a devolatilization device is used. May be used. A solvent may be present during imidization, and for example, a tertiary amine or the like is preferably used.

The temperature of the imidization reaction is about 80 to 350 ° C, preferably 100 to 300 ° C. If the temperature is lower than 80 ° C, the reaction rate is slow and the reaction takes a long time, which is not practical. On the other hand, when the temperature exceeds 350 ° C, the physical properties are deteriorated due to thermal decomposition of the polymer.

In the second production method, the amount of acid anhydride residue is adjusted by the molar equivalent of aniline added to the acid anhydride group.

As the solvent for imidization in a solution state, there are acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, tetrahydrofuran, dimethylformamide and the like. Among these, methyl ethyl ketone and methyl isobutyl ketone are preferable. The non-aqueous medium used for imidization in suspension in a non-aqueous medium includes aliphatic hydrocarbons such as heptane, hexane, pentane, octane, 2-methylpentane, cyclopentane and cyclohexane.

The imidized copolymer of the component (A) is an aromatic vinyl monomer 30 to 79% by weight, preferably 40 to 75% by weight, an N-phenylmaleimide monomer residue 20 to 60% by weight, preferably 25 ~ 55 wt%, maleic anhydride monomer residue 1 ~
An imidized copolymer comprising 10% by weight, preferably 1 to 5% by weight, and 0 to 40% by weight, preferably 0 to 30% by weight of a vinyl monomer residue copolymerizable therewith, When the amount of the vinyl monomer residue is less than 30% by weight, moldability and dimensional stability are impaired, and when it exceeds 79% by weight, impact strength and heat resistance are impaired. When the amount of the N-phenylmaleimide monomer residue is less than 20% by weight, the effect of improving the heat resistance is not sufficient, while when it exceeds 60% by weight, the resin composition becomes brittle and the moldability is significantly deteriorated. If the amount of the maleic anhydride monomer residue exceeds 10% by weight, thermal stability and hot water resistance are deteriorated, which is not preferable. If it is less than 1% by weight, the moldability is poor. If the amount of the vinyl monomer residue copolymerizable with these exceeds 40% by weight, dimensional stability and heat resistance will be impaired.

 Next, the component (B) will be described.

As the aromatic vinyl monomer used as the component (B), styrene, α-methylstyrene, vinyltoluene, t-
It is a styrene monomer such as butyl styrene or chlorostyrene and a substituted monomer thereof, and among these, styrene and α-methylstyrene are particularly preferable.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like, and acrylonitrile is particularly preferable. Vinyl monomers copolymerizable with them include acrylic acid ester monomers such as methyl acrylic acid ester, ethyl acrylic acid ester and butyl acrylic acid ester, and methacrylic acid ester monomers such as methyl methacrylic acid ester and ethyl methacrylic acid ester. Examples thereof include monomers, vinylcarboxylic acid monomers such as acrylic acid and methacrylic acid, acrylic acid amide, and methacrylic acid amide.

The optical disc material of the present invention comprises the above-mentioned component (A) and (B).
There is no particular limitation on the mixing method of the component (A) and the component (B) for producing the composition, and a known means can be used. Examples thereof include a Banbury mixer, a tumbler mixer, a mixing roll, a single-screw or twin-screw extruder, and the like.

Examples of the mixing form include normal melt mixing, multistage melt mixing using master pellets, and solution blending.

〔Example〕

 The present invention will be described below with reference to examples.

All parts and% in the examples are expressed on a weight basis.

Experimental Example (1) Manufacture of a polymer in which a copolymer obtained by polymerizing an aromatic vinyl monomer and maleic anhydride was imidized. 60 parts of styrene and 50 parts of methyl ethyl ketone were charged in an autoclave equipped with a stirrer, and the system was cooled. Was replaced with nitrogen gas and then the temperature was raised to 85 ° C., and 40 parts of maleic anhydride and 0.15 part of benzoyl peroxide were mixed with 250 parts of methyl ethyl ketone.
The solution dissolved in 1 part was continuously added over 8 hours. The temperature was maintained at 85 ° C for a further 3 hours after the addition. A part of the viscous reaction liquid was sampled and the polymerization rate was quantified by gas chromatography. As a result, styrene 99%, maleic anhydride
It was 99%. 34 parts of aniline and 0.3 part of triethylamine, 0.90 molar equivalents to maleic anhydride, were added to the copolymer solution obtained here, and the mixture was reacted at 140 ° C. for 7 hours. 200 parts of methyl ethyl ketone was added to the reaction solution, cooled to room temperature, poured into 1500 parts of vigorously stirred methanol, precipitated, separated by filtration and dried to obtain an imidized copolymer. From C-13 NMR analysis, the maleic anhydride monomer residue was 3.1% by weight. This was designated as a polymer (A).

Experimental Example (2) Production of Copolymer of Aromatic Vinyl Monomer, N-Phenylmaleimide Monomer, and Maleic Anhydride Polymerized 50 parts of styrene and 50 parts of methyl ethyl ketone were charged into an autoclave equipped with a stirrer. After substituting the inside of the system with nitrogen gas, the temperature was raised to 85 ° C., and N-phenylmaleimide 47
Parts, maleic anhydride 3 parts, benzoyl peroxide 0.
A solution of 15 parts dissolved in 250 parts methyl ethyl ketone was added continuously over 8 hours. Addition temperature for 3 hours after addition 85 ℃
Kept at. The polymerization rate was 99% styrene, 98% N-phenylmaleimide, and 99% maleic anhydride. This polymer was precipitated with methanol to obtain an imidized copolymer. This was designated as a polymer (B).

Experimental Example (3) Production of a polymer obtained by imidizing a copolymer obtained by polymerizing aromatic vinyl, maleic anhydride and a vinyl monomer copolymerizable therewith, styrene was used instead of 60 parts of styrene in Experiment (1). Using 60 parts and 10 parts of acrylonitrile, 30 parts of 40 parts of maleic anhydride
And a copolymer was obtained in the same manner as in Experimental Example (1). The polymerization rate of this polymer was 98% styrene and 98% maleic anhydride.

The same operation as in Experimental Example (1) was performed except that 26 parts of aniline was used in the copolymer solution obtained here to obtain an imidized copolymer. This was designated as a polymer (C).

Experimental Example (4) Production of styrene-acrylonitrile copolymer Acrylonitrile 30 parts, styrene 70 parts, sodium stearate 2.5 parts, t-dodecyl mercaptan 0.6 parts and water 25
0 part was heated to 70 ° C., and 0.05 part of potassium persulfate was added to initiate polymerization. Five hours after the initiation of the polymerization, 0.03 part of potassium persulfate was further added, and the temperature was raised to 75 ° C. and maintained for 3 hours to complete the polymerization. The obtained latex was coagulated with calcium chloride, washed with water and dried to obtain a white powder copolymer, which was designated as AS resin.

Examples 1 to 3 60 parts of the polymer obtained in Experimental Examples (1) to (3) and 40 parts of the AS resin obtained in Experimental Example (4) were blended, and this mixture was heated at 260 ° C. in a vented extruder. After extrusion pelletization, injection molding was performed at 260 ° C., and a disk having a thickness of 1.2 mm and a diameter of 120 mm was molded and evaluated. The results are shown in Table 1.

Examples 4 to 6 Polymer (A) obtained in Experimental Example (1) and Experimental Example (4)
The AS resin obtained in 1. was mixed in various proportions, and the same procedure as in Example 1 was carried out. The results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that AS resin was not used. The results are shown in Table 1.

Comparative Example 2 A polycarbonate resin (Teijin Panlite L-1225) was used instead of the imidized copolymer and the AS resin, and the same procedure as in Example 1 was performed. The results are shown in Table 1.

The methods for measuring the physical properties shown in the table were as follows.

(1) VSP: Load 5 kg Compliant with ASTM D-1525 (2) Light transmittance: Compliant with JIS K6714 (3) Optical path difference: Measured by an automatic ellipsometer (4) Izod impact strength: 1/4 inch without notch AST
According to MD-256 [Effect of the Invention] As described in detail above, the resin composition of the present invention is excellent in heat resistance and transparency, has good moldability, and has moldability with small optical distortion. it can.

Claims (1)

(57) [Claims] 1. Component (A): Aromatic vinyl monomer residue 30 to
Imide composed of 79% by weight, 20 to 60% by weight of N-phenylmaleimide monomer residue, 1 to 10% by weight of maleic anhydride monomer residue, and 0 to 40% by weight of vinyl monomer residue other than these 10 to 90 parts by weight of the copolymer, component (B): 40 to 80% by weight of an aromatic vinyl monomer, 0 to 40% by weight of a vinyl cyanide monomer and a vinyl monomer residue of 0 other than these An optical disc material comprising 10 to 90 parts by weight of a copolymer containing 40 to 40% by weight.