JPS5940335A - Board for information recording medium - Google Patents

Abstract

PURPOSE:To obtain a board for information recording medium which excels in the double refraction properties with high sensitivity and a simple layer constitution, by molding a resin composition made of a polymer containing ester methacrylate and having a low level temperature of loss in guantity in the air. CONSTITUTION:A resin composition is substantially made of a polymer containing >=10wt% ester methacrylate and has <=310 deg.C 10% loss temperature under the 10 deg.C/min temperature rise conditions in the air. The polymerization component, i.e., ester methacrylate of the polymer uses methyl methacrylate, cyclohexyl methacrylate, etc.; while the copolymerization component of the polymer uses preferably the styren compounds such as styrene, methyl styrene, etc., alpha-methyl styrene, etc., the ethylene halogenide compounds such as polyvinyl chloride, etc., the vinyl aromatic compounds such as vinyl carbazole, etc., the olefin compounds such as ethylene, etc. The polymer discharges thermally a part of a polymer molecule and denatures it or produces the cleavage of the main chain of the polymer to decompose the whose molecule. Furthermore it is preferable that the polymer which is quickly decomposed when it receives high energy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention causes a change in the thermal state of an information recording layer using a high-energy beam such as a laser beam, and records information using the resulting change in yC characteristics. It is related to the foundation of information recording media.

Immediately after writing information in a high-density information recording medium that uses a laser beam that can provide n light with high illuminance and for a short time,
Can be read directly without post-processing [DRAW J
(Direot Read After Write
) The usefulness of media having these characteristics has been actively pointed out in recent years in the fields of computers, data files, V, T, R, audio discs, reproduction recording media, etc. In addition, many studies regarding materials for DRAW recording media have been reported.

Conventionally, many of the recording layers in known laser beam recording media are reflective metal thin films such as klSRb, Au, Or, etc., amorphous metals such as To, Bi, Ss, or oxides thereof. Or Se-Te-As, Te-A
This is a vapor-deposited thin film of a chalcogen compound such as s. In many cases, information is recorded by forming pits (four parts) based on the principle that these recording layers are irradiated with a laser beam and the recording layer is melted and vaporized by the energy of the laser beam. One problem with such recording media is how efficiently the energy of laser light can be used, and many attempts have been made to solve this problem.

For example, reflective type information recording media often have a two-layer structure consisting of a light absorption layer (recording layer) and a light reflection layer to improve the SR ratio. Since conductivity causes problems such as low recording sensitivity, it has been proposed to provide a transparent heat insulating layer between the two layers as a solution to this problem.

Also, a recording medium using a film in which fine metal powder is dispersed in a binder as a recording layer (Japanese Patent Laid-Open No. 57-24290)
In this paper, we aim to improve sensitivity by using a self-assembling compound in the binder itself or in the binder, and taking advantage of the decomposition and foaming of this self-oxidizing compound when it absorbs laser light. Ru.

However, until now, there have been few attempts to improve the sensitivity by focusing on the characteristics of the base of the information recording medium. That is,
In the present invention, a substrate is formed of a resin composition that is made of an aggregate containing 10 or more methacrylic acid esters and has a 10% solidification temperature of 31Q°C or less when heated at 10°C/min in the atmosphere. By using this method, when the recording layer receives high energy, the substrate itself also decomposes, helping to form bits in the recording layer. Furthermore, it is an attempt to satisfy the requirement that the substrate of an information recording medium has low refraction.

That is, an object of the present invention is to obtain high sensitivity with a simple layer structure.
The objective is to provide a basis for an information recording medium that has excellent birefringence and has excellent birefringence.

The object of the present invention is to obtain a polymer containing 10% by weight or more of methacrylic acid ester, which has a 10% weight loss temperature of 310°C or lower when heated at 10°C/min in the atmosphere.

This is achieved by an information recording medium base formed by molding a resin composition.

The resin composition used for the base of the present invention consists essentially of a polymer containing 10% by weight or more of methacrylic acid ester, and has a 10% weight loss temperature of 31% when heated at 10°C/min in the atmosphere.
It is sufficient if the temperature is 0° C. or lower, but it is preferable that the temperature does not cause thermal decomposition to the extent that it is inconvenient during molding. This weight loss temperature is preferably 300°C or lower, more preferably 290°C or lower.

Examples of the methacrylic acid ester which is a polymerization component of the polymer used in the resin composition of the present invention include methyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate-F1 tert-butyl methacrylate, phenyl methacrylate, benzyl methacrylate, and naphthyl methacrylate. etc. Metaac 1) Two or more types of acid esters may be used in combination).

Copolymerization components of the above polymer include styrenes such as styrene, methylstyrene, and chlorostyrene, α-methylstyrene, α,0-dimethylstyrene, α m-dimethylstyrene, α,p-dimethylstyrene, and 0-chlorostyrene. −α
-Methylstyrene, etc. σ) α-Methylstyrenes, vinyl chloride, hini'J chloride, halogenated ethylenes such as tetrafluoroethylene, vinyl aromatics such as vinyl carbazole, vinylnaphthalene, ethylene, propylene, butadiene, etc. olefins and the like are preferred.

Furthermore, the polymer used in the resin composition of the present invention is one in which a part of the polymer molecule is thermally released and denatured, or the main chain of the polymer molecule is cleaved, and the entire molecule is decomposed. It is preferable that the material decomposes quickly when exposed to high energy.

Note that the high energy source here includes laser light, focused visible, ultraviolet, or infrared light, electron beam, high temperature, and the like.

In the polymer used in the present invention, if the methacrylic ester content is less than 10% by weight, the birefringence when used as a substrate is large, which is undesirable.

The measurement conditions for the above-mentioned "loss temperature" characteristic are as follows. In other words, sample powder (sufficiently fine) is used, Part 1
It is sufficient to take ~10m9 of the sample, raise the temperature in the atmosphere at 10°C/min using a thermobalance, and measure the 10% weight loss temperature.

Here, "consisting essentially of a polymer containing 10% by weight or more of methacrylic acid ester" means that components other than the polymer may be included as long as the effects of the present invention are not impaired.

The resin used in the base of the present invention is used as a heat stabilizer to ensure stability during molding.
Cresol, 2,4-di-methyl-6-tert-butylphenol, 2,2-methylenehis(4-methyl-6-tert-butylphenol), 4,41-butylidenebis(3
-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol, 1,
1.3-tris(2-methyl-4-hydroxy-5-tert-butylphenylbutane, H dilaurylthiodibropionate, distearylthiodipropionate, distearyl β, β-thi) It's okay.

By controlling the amount of these heat stabilizers to an appropriate level, the thermal decomposition temperature can be controlled and the basis of the present invention can be obtained.

In addition, the resin mixture forming the basis of the present invention includes benzoyl peroxide, cyclohexanone peroxide, p-menthane hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, azobisisobutyronitrile, 1.1 '-azobis(cyclohexane-
It may contain a reagent that generates radicals by heat, such as 1-carponitrile, and may be controlled to easily cause thermal decomposition.

In order to improve the moldability, the resin mixture forming the basis of the present invention contains 2-ethylhexyl phthalate, n-butyl phthalate, isodecanyl phthalate, tridecanyl phthalate, heptyl phthalate, nonyl 7-thalate, etc. Alkyl 7-talates, 2-ethylhexyl adipate,
Alkyl esters of dibasic acids such as 2-ethylhexyl sebacate, alkyl esters of dibasic acids such as tributyl phosphate, trioctyl phosphate, tricresyl phosphate, triphenyl phosphate, epoxidized octyl oleate,
Epoxidized fatty acid esters such as epoxidized butyl oleate, polyester plasticizers, chlorinated fatty acid esters, amides such as ethylene bisstearamide, stearamide, palmitic acid amide, oleic acid amide, stearyl alcohol, etc. It may also contain a lubricant such as a higher alcohol.

The substrate of the present invention not only receives heat from the recording layer but also absorbs light by itself, so carbon black, phthalocyanine, methylene blue, malachite green, etc.
It may contain dyes or pigments such as crystal violet, night blue, Victoria blue, rhodamine B1 Capri blue, horsetail, rose bengal, thionine, methionine, polymethine pigments, and thioxanthin pigments.

The fat-reducing composition forming the basis of the present invention uses 2,4-dinitrophenol, 2.4.6, to improve thermal decomposition properties.
-) Rinitroresorcin, 2,4.6-Dolinitrometacresol, 2,4.6-) Rinitroaniline, 1,5
- It may contain autooxidizing compounds such as nitro compounds such as dinitronaphthalene and 1,8-dinitronaphthalene, and nitrate esters such as bent lift and nitrohexanol.

Specific examples of the resin composition of the present invention are listed below.

1. Copolymer of 60 parts by weight of methyl methacrylate and 40 parts by weight of cyclohexyl methacrylate (MW=120
,000) Per 100 parts by weight, 4゜41-thiobis(3-methyl-6-tert-butylphenol) o, ziht part, tricresyl phosphate 0.5KCff
The maximum temperature of 10% reduction (hereinafter referred to as 10% reduction temperature) under heating conditions of 10℃/min in the atmosphere is 30%.
A resin composition at 6°C.

2. Copolymer of 807Ai parts of methyl methacrylate and 20 parts of α-methylstyrene (MW: 180.000
) Stearyl β-(3,5
- 0.6 tR part of ditertiary-butyl-4-hydroxyphenylnopropionate, 0.6 tR part of stearamide.
A resin composition containing 5 parts by weight and having a 10% weight loss temperature of 292°C.

3. 70 parts by weight of methyl methacrylate and tertiary
Copolymer consisting of 25 parts by weight of butyl methacrylate and 5 parts by weight of butyl acrylate (MW=130,000)
0.4 parts by weight of stearyl β-(3,5-ditertiary-butyl-4-hydroxyphenylnopropionate) per 100 parts by weight, 0.2 parts by weight of AO-501 (manufactured by Adeka Argus), 2- A resin composition containing 0.5 parts by weight of ethylhexyl acid phosphate and having a 10% weight loss temperature of 270°C.

4. Copolymer of 50 parts by weight of methyl methacrylate and 50 parts by weight of cyclohexyl methacrylate (MW=120
,000) Stearyl β-
(3,5-ditertiary-butyl-4-hydroxyphenyl)propylene 4-) 0.6 electric resistance stitch, 0.3 parts by weight of ethylene bisstearamide, 2,4-ditertiary-butylphenyl phosphite o, 2 mfk parts , 0.0005 parts by weight of Brilliant Green was added to the resin composition, and the temperature was 306°C.

5. Homopolymer of cyclohexyl methacrylate
(MW = 200,000) For 100 heavy duty parts, triphenyl phosphite 03-ffi amount, AO-
30 (manufactured by Adeka Argus) 04 parts by weight, AO-23
(Manufactured by Adeka Argus) 0.2 parts by weight, JF-77 (
Shokuno Kagaku) 0.02 overlapping part, stearamide 0
．． 3 parts by weight of a resin composition having a 10% reduction temperature of 296°C.

6. Copolymer of 95 parts by weight of methyl methacrylate and 5 parts by weight of butyl acrylate (MW = 180,000
), 1.0 parts by weight of 2,4.6-)dinitrometacresol, 1,1.3-)lis(2-methyl-4-hydroxy-5-tert-butylphenyl)butane ( 13 = JR Department, methylallyl alcohol 0
1 made by adding 5 parts by weight of JF-79 (manufactured by Shokuno Kagaku)
Resin composition with 0% weight loss temperature of 282°C.

7. Copolymer of 75 parts by weight of methyl methacrylate and 25 parts by weight of α-methylstyrene (MW=140ρ00) 1
00 parts by weight, 0.5 parts by weight of MARK 1500 (manufactured by Adeka Argus), 4.41-thiobis(3-
1. A resin composition having a weight loss temperature of 276° C. and containing 0.2 parts by weight of methyl-6-tert-butylphenol.

The information recording medium base of the present invention can be formed by injection molding, compression molding,
It may be molded by extrusion molding or any of a variety of similar molding methods. However, injection molding is most preferred. Generally, when molding individual fat compositions, considerable heating is required, but it is desirable that the resin used for the base of the present invention be sufficiently stable against heating during molding.

The material used as the recording layer when making a DRAW type recording medium using the base of the present invention efficiently absorbs the recording laser source, changes optical properties with moderate laser output, and achieves high quality recording and playback. In order to obtain a signal, any material may be used as long as it has an excellent surface smoothness and smoothness, is mechanically and chemically stable, and can withstand long-term use. For example, IFe, Oo, Ni, Pd, Pt,
Ou% Ag5Au%CdN Hg N A1% Ga
% Engineeringn5Si, Ge, 5nSPb.

Metals such as Sb, Bi, Se, 'I'e, etc. or two of them
An alloy thin film with an M force of 1 or more, a metal compound thin film such as a metal oxide, sulfide, halide, carbon-containing substance, etc., an organic compound thin film such as a dye or pigment, or a metal, a metal compound, or an organic substance in an organic polymer layer. A thin film, etc., dispersed or dissolved in

As the metal oxide, Inor % MOor %
5bOx.

The metal sulfides such as TeOx include 5e-S, 5e
-To-8, Ge-8, etc., MgJ', etc. are used as the metal halide, and -Te-C etc. are used as the carbon-containing substance.

Further, as the dye, brilliant green, fluorescein, polyester yellow, cyanine color chart, etc. are used as the laser) °0 absorbing material.

As the organic polymer used in the dispersion system, thermoplastic polymers are generally used, but either water-soluble or hydrophobic polymers may be used.

For example, polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyamide, polycarbonate resin, methacrylic resin, phenol resin, epoxy resin, gelatin derivative, cellulose derivative, sugar derivative, etc. can be used.

After recording information in bits on the information recording medium using the information recording medium base of the present invention, methods for reading out this information include reading out by reflection or transmission of the original that is captured, or static reading. Any method is possible, including one that reads out capacitance,
From the point of view of effectiveness as an information recording system, the most preferable method is to read out the information using the reflection of the tube. In this case, there are two possible methods: one in which information is written from the substrate side and one in which information is written from the recording layer side. However, in the present invention, separation of the recording layer and the substrate is promoted by disassembling the substrate. It is preferable to use a method of writing from the substrate side using a high-energy source because it is most effective when writing. Furthermore, when writing or reading from the substrate, it is preferable that the substrate has sufficient transparency and small birefringence.

In the case of following the most preferred embodiment and usage mode as described above (that is, a method in which molding is performed by injection molding, and reading is performed from the substrate side using a laser source, causing thermal decomposition of the substrate), the present invention The base should have the following physical properties (particularly preferred):

1) It has good transparency, and has a transmittance of 70% or more, more preferably G185% or more, for the wavelength of the light source used.

Phantom: Good homogeneity and birefringence i of 60 degrees or less, more preferably 20 degrees or less.

3) Good fluidity properties, 60℃ above 10% weight loss temperature
Melt flow rate force at low humidity) ISOlR-
11,33 Test method 5 Kgfσ] under weighting, 1,! 7
/10 minutes or more, preferably 5,9/10 minutes or more, more preferably f:j 109/10 minutes or more.

The above-mentioned physical properties are effective for an example of the RAW recording material as described above, and the scope of the present invention is not limited thereto.

For example, if the writing and reading side is not from the substrate side but from the recording layer side, the transparency and birefringence of the substrate will not be a problem, so items 1) and 2 above are unnecessary.

Also, when creating a resin base by a method other than injection molding,
Melt flow rate may not be an issue;
In this case, item 3) is unnecessary.

If the recording medium base of the present invention is used, further improvement in sensitivity can be expected for any information recording medium in which the recording layer is blown away or evaporated by absorption of high energy. However, it has a simpler structure than information recording media in which a layer that decomposes due to high energy absorption is formed between the recording layer and the substrate, which is expected to have similar effects, and the adhesiveness of the film etc. There is no need to take this into consideration, and it is expected to be advantageous in terms of production and cost.

EXAMPLES Hereinafter, the present invention will be specifically explained according to Examples, but the embodiments of the present invention are not limited thereby.

Example 1 40 parts by weight of a copolymer (weight average molecular weight 210,000) of methyl methacrylate) 60 ffiden M, cyclohexyl methacrylate (weight average molecular weight 210,000), 4,4゛-thiobis(3-methyl) -6-tert-butylphenol) 0.2 parts and 0.5 parts by weight of ethylene bisstearamide were added, and the pelletized resin composition (10% h reduction; wet temperature 306°C) was injection molded, 3001
A disk having a diameter of 1+1φ and a thickness of 1.2 mm was prepared.

A reflective recording thin film was provided on the disc by vapor depositing Kl to a film thickness of 50A.

The relative scanning speed between the recording medium manufactured in this way and the He-Na laser beam 6 focused to a beam diameter of 1.2 μm is set to l Q Iff /sec, and a 200 fisec pulse is generated by an acousto-optic device to form pits. A written record was made.

Using the same yC system as used for recording, playback was performed in continuous wave mode with a He-Na laser power of 0.3 mW, the recording threshold was 5 mW, and the playback signal contrast ratio at 20 mW was A preferred value of 0.4 was obtained.

Comparative Example 1 In Example 1, a recording medium was manufactured in the same manner as in Example 1, except that an acrylic resin plate with a thickness of 1 or 2 thick [Mitsubishi Rayon L Co., Ltd.] was used as the base, and other conditions were the same as in Example 1. and recorded and played back. Recording threshold is 8 mW, 20 mW
The reproduced signal contrast ratio was 0.4.

Comparative Example 2 A polycarbonate resin plate with a thickness of 1 or 2 mm was used as the base in Example 1 to achieve smoothness of 9B [Panlite AD manufactured by Hotujin Kasei Co., Ltd.
-5000 was injection molded, and the rest were Example 1.
A recording medium was manufactured in the same manner as described above, and recording and reproduction were performed. The recording threshold was lomW, and the reproduction signal contrast ratio at 20 mW was 0.4.

Example 2 The disk used in Example 1 was subjected to plasma discharge treatment and alkali treatment to make the surface hydrophilic, and a gelatin solution containing colloidal silver particles was applied by dipping until the dry film thickness was 0.
．． A transparent physical development nucleus layer of 0.05 μm was provided.

What is the aqueous gelatin dispersion solution of colloidal silver particles, which are physical development nuclei? It was obtained by reducing iM acid silver with dextrin, the weight ratio of silver to gelatin was 32%, and the particle size of colloidal particles was about 30 OA. On this layer containing physical development nuclei, a fine grain silver iodobromide gelatin emulsion (silver iodide 3 monomer, average grain size 0.05 μm) was coated as a metal compound so that the silver weight was 3 g/11? A sample was obtained.

Without exposing this sample to light, use a developer with the following composition at a temperature of 4.
After developing at 0°C for 2 minutes, the emulsion layer was peeled off and washed with warm water at 37°C.

(Developer) As a result, when observed through the support, a silver mirror with metallic luster was generated, and the reflectance at 633 g and IH was 50%.

When recording and reproducing were performed in the same manner as in Practical Example 1, the recording threshold was 3 mW, and the reproduced signal contrast ratio at 10 mW was 0.65, giving good results corresponding to an S/N ratio of 40 dB or more.

Comparative Example 3 In Example 2, a recording medium was manufactured in the same manner as in Example 2 except that a polycarbonate resin plate having an excellent smoothness and a thickness of 1 to 2 mm was used as the base, and recording and reproduction were performed.

The recording threshold was as high as 8 mW.

Agent Yoshimi Kuwahara

Claims (1)

[Claims] Consisting essentially of a polymer containing 10% by weight or more of methacrylic acid ester, 10% under heating conditions of 10°C/min in the atmosphere
A base for an information recording medium, characterized in that it is molded from a resin composition having a weight loss temperature of 310° C. or lower.