JPS62192438A - Base for optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled base excellent in heat resistance, mold release, mechanical strength, optical properties and transferability, by combining a copolymer based on methyl methacrylate and an N-substituted maleimide with a specified mold release. CONSTITUTION:A copolymer (A) is obtained by copolymerizing a first principal component comprising 95-50wt% methyl methacrylate and 0-20wt% aromatic vinyl compound [e.g., (alpha-methyl)styrene] with a second principal component comprising at least one member selected from among N-cyclohexylmaleimide, N-t-butylmaleimide, N-acrylmaleimide, etc. 100pts.wt component A is mixed with 0.05-2.0pts.wt. mold release comprising at least one compound (B) selected from among a fatty acid monoalcohol ester of the formula (wherein R1-2 are each a 5-20 C alkyl), stearyl alcohol, stearic acid, cetanol, glycerol stearate and an oligomer containing a perfluoroalkyl group and an oleophilic group to obtain the titled base of a heat distortion temperature >=105 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a base material for an optical information recording medium that uses a laser beam in a recording/reproducing system such as a video tape or a memory disk.

[Conventional technology]

Methacrylic resin has its inherent properties of excellent transparency,
It is currently used for optical video discs due to its weather resistance. Regarding methacrylic resin copolymers for video discs, as a prior art, JP-A-57-123208
No. 57-138601, etc. Japanese Unexamined Patent Publication No. 1983
- In the example of No. 123208, the heat distortion temperature is 92.
℃ or less, the heat deformation resistance is insufficient, and the mechanical strength is also insufficient. Also, JP-A-57-15
No. 8601 discloses a copolymer consisting of methyl methacrylate and an alkyl acrylate or argyl methacrylate having an alkyl group having 1 to 12 carbon atoms, but it does not undergo thermal deformation within the range specified by the intrinsic viscosity and heat deformation temperature. When the temperature is raised, the intrinsic viscosity decreases and the mechanical strength decreases, causing cracks when peeled from the mold, and when maintaining moldability and mechanical strength, the heat distortion temperature decreases. -10,000, heat resistance, mold releasability, transferability,
Although there is a strong requirement for mechanical strength of VC4 or less, the current situation is that it is still being used as a top fabric.

[Problems to be Solved by the Invention] In view of the current situation, the Ministry of the Invention and others have determined that the heat distortion temperature is 105°C.
As a result of intensive studies to develop a base material for next information recording media that has excellent heat resistance, mold releasability, transferability, and mechanical strength, we found that the following main ingredients are methyl methacrylate and N-f exchanged maleimide. We have discovered that an excellent base material for discs can be obtained by combining a copolymer and a specific type of release agent, and have arrived at the present invention. The present invention is characterized in that the monomer units are monomer units consisting of approximately 95 to 50 weight percent of methyl methacrylate, O to 20 weight percent of an aromatic vinyl compound, and 5 to 30 weight percent of N-substituted maleimide.
m@body (for 100 parts by weight of IJ, R,0OOR2
At least one of fatty acid monohydric alcohol, stearyl alcohol, stearic acid, cetanol, stearic acid glycerin ester, perfluoroalkyl group/lipophilic group-containing oligomer (R1 and R2 represent an alkyl group having 5 to 2 carbon atoms) This is a base material for an optical information recording medium, in which 5 to 2.0 parts by weight of a seed compound [nJα is added, and the heat deformation temperature is 105° C. or higher.

Methyl methacrylate, which is the first main component of the copolymer of the present invention (11), is necessary in terms of the weather resistance, transparency, heat resistance, and mechanical strength inherent to methacrylic resin, and is included in the copolymer [1]. The proportion of is 95-50% by weight, preferably 95-7011
It is. When the weight is more than 95 tS, the heat distortion temperature decreases,
If the ratio is less than 5°, the above-mentioned properties will be impaired, which is not preferable.

A part of methyl methacrylate is copolymerizable with other monomers 5
For example, it can be replaced with methacrylic acid alkyl esters having 2 to 5 carbon atoms, acrylic esters having 1 to 8 carbon atoms, or aromatic vinyl compounds, but even in this case, the proportion of methyl methacrylate is the same as above. Must be within the range. In particular, an aromatic vinyl compound can be used instead for the main purpose of improving the copolymerizability of N-substituted maleimide, which will be described later.

The substitute amount is preferably 20 weight tons* or less, more preferably 1
It is under a 0 weight board.

Typical examples of aromatic vinyl compounds that can be used in the present invention include styrene, o-, and m-.

p-methylstyrene, 1,3-dimethylstyrene, 2.
4-dimethylstyrene, pt-butylstyrene, α-
Methylstyrene, α-ethylstyrene, α-methyl-p
- Monovinyl aromatic hydrocarbons such as methylstyrene, alhalomonovinyl aromatic hydrocarbons such as o-, m+, p-chlorostyrene, 2,4-sibu-a-mostyrene, 2-methyl-4-chlorostyrene, etc. Can be mentioned.

Preferably, /i is at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene, and it is preferable to use α-methylstyrene, which has an auxiliary effect of improving heat resistance, or to use a base material with higher heat resistance. Preferable in manufacturing. The molar ratio of the aromatic vinyl compound to the N-substituted maleimide is preferably 2 or less, more preferably 1.5 or less.

In the present invention, N-substituted maleimide, which is the second main component, is the ninth essential component for improving heat resistance.
N-cycloalkylmaleimide), N-alkylmaleimide, N-benzylmaleimide, N-arylmaleimide and substituted derivatives thereof, the following are representative examples: , N-ethylmaleimide, N-n-butylmaleimide, N-t-butylmaleimide, N-benzylmaleimide, N-phenylmaleimide), N-(2-chlorophenyl)male(mido, N-(4-chlorophenyl) ) maleimide, N-(4-10mophenyl)maleimide, N-(2-methylphenyl)maleimide)", N-(2
-ethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-(2,4゜6-trimethylphenyl)maleimide)', N-(4-pendylphenyl)maleimide)' ,! There is 'f.

Considering the balance between hygroscopicity and heat resistance, it is preferable to use N-cyclohexylmaleimide, at-butylmaleimide, and N-arylmaleimide. In particular, when selecting N-arylmaleimide, it is desirable to use at least one selected from the group consisting of the following formula.

The N-substituted maleimide used in the present invention is 5 to 30
%, preferably 5 to 20 heavy electric currents, and 5% by weight
When the heat resistance is more than 30% by weight, the copolymerizability decreases, and there are many unreacted monomers, and the heat resistance is also reduced. This is undesirable because the mechanical properties of the base material are deteriorated.

In the present invention, the heat distortion temperature is a ratio value measured under a load of 1a56 kg based on ASTM-D648.

In the present invention, the heat deformation temperature of the resin is set to 105°C or higher because in the disk manufacturing process, when depositing aluminum, heat is applied and heat resistance is required, and in practical terms it is lower than 105°C. There is a concern that the material may deform if it is left in a vehicle or the like and exposed to high temperatures, so better heat resistance is required.

Furthermore, the present invention is characterized in that a copolymer having the above-mentioned physical properties is added as a mold release agent to R, COOR2 (R1 and R2 represent an alkyl group having 5 to 20 carbon atoms) fatty alcohol, stearyl alcohol, and stearin. At least one of acid, cetanol, stearic acid glycerin ester, and perfluoroalkyl group-hydrophilic group-containing oligomer
By adding 105 to 20 parts by weight to 100 parts by weight of the a-e copolymer, a methacrylic resin with unprecedented heat resistance and moldability with a specific heat deformation temperature of 105°C or more can be obtained, and an optical It is an interchangeable material that can be used as a disc material. The amount of mold release agent added is (
If the amount is less than 105 parts by weight, the mold releasability will be poor, and if it is more than 2.0 parts by weight, the heat distortion temperature will decrease or the mold may be contaminated, which is undesirable. More preferably α1 to α5
Parts by weight.

General formula RI COOR2 (R1 * R2 has 5 to 2 carbon atoms
Specific examples of fatty acid monohydric alcohol esters (representing an alkyl group of 0) include stearyl stearate, lauryl stearate, intridecyl stearate, stearyl balmitate, myristyl myristate, etc.
Stearic acid glycerin esters include monoesters, diesters, and triesters, and oligomers containing perfluoroalkyl groups and lipophilic groups include Unidyne (trade name) manufactured by Daikin Industries, Ltd.
DB-301, 401, 402゜502, Megafac (product name) manufactured by Dainippon Ink and Chemicals Co., Ltd. -171
, 171, 177, etc.

Although the present invention is not limited to the present invention, it is preferable that the melt flow rate of the resin in the present invention is in the range of 1 to 40 f/10 min as measured at a load IBK9 based on ASTM-D1238.

If the size is smaller than 1f710, the transferability of information from the mold will be poor.9
, and birefringence tends to increase. When the melt flow rate is greater than 40 f710 min, mechanical strength tends to decrease. Also, the residual monomer contained in the resin is preferably 1% by weight or less, more preferably 5% by weight of CL.
It is as follows. If the weight exceeds 4, depending on the molding conditions, it may easily cause silver-like defects. Further information regarding the residual monomer of N-substituted maleimide is α5
The amount of α5 weight is preferably 1% or less, preferably 1% or less. [If the amount exceeds 15% by weight, mold contamination tends to occur, and the long-term storage stability of the obtained base material tends to decrease.

The molding material of the present invention can be suitably used as a substrate for information recording media such as video discs, audio discs, and memory discs.

The molding material of the present invention can be manufactured using known acrylic resin manufacturing methods such as suspension polymerization and bulk polymerization. Maku 1
It is also possible to add ultraviolet absorbers, dyes and pigments to the co-J4 composite of the present invention, if necessary.

EXAMPLES] Hereinafter, the present invention will be specifically explained with reference to Examples. In addition,
The measurement method was as follows. Note that each characteristic value was measured by the following method.

■ Heat distortion temperature (HDT) ASTM-D648 Load 1fLi & 56 to 9 (2
64psi) ■ Melt flow rate (MFR) A13TM-D1258 Load tL8Ki9 ■ Tensile strength ASTM-D638 Dumbbell type A ■ Heat decomposition resistance Day # V17-65 type injection molding machine, cylinder temperature 280℃, cycle 50 seconds 2mX 110mX 11
Form a 0m plate and visually judge the wire.

■ Mold releasability Using the famous Dynamelta injection molding machine, the mold has a plate thickness of 1
．． 2wm, box diameter 300m, rack spacing 1゜6μm
b) A disc with a track width of 05 μm and a rack groove depth of 03 μm was used, and the cylinder temperature was 290°C, the mold temperature was 80°C, and the cycle was 45 seconds. ) was evaluated by checking the number of O ■ Light transmittance from 500 nm to 900 nm with Hitachi Spectroscopic Model 350
Measure the transmittance in the wavelength range up to t.

■ To evaluate the optical strain release property, we measured the phase difference at a distance of 50 m from the center using the same disk.

The phase point was determined using a Nippon Kogaku polarizing microscope POH model with a Leitz Herec convenser, and the sodium D line (λ = 5
89nm), tungsten lamp (λ=550n
Measure the phase difference of the transmitted light using m).

(2) Residual monomer The residual monomer in the pellet was determined by a conventional method using a gas chromatograph.90 In each of the Examples and Comparative Examples, all parts indicate parts by weight.

Example 1 Monomer rf consisting of 90 parts of methyl methacrylate, 10 parts of N-cyclohexylmaleimide, 03 parts of n-octylmercaptaf, and 1 part of azobisisobutyronitrile α
Qooos 100 parts of a copolymer of methyl methacrylate and sodium salt of 2-sulfoethyl methacrylic acid.
150 parts of pure water in which 05 parts of sodium sulfate + 7 um were dissolved, and the mixture was placed in a pressure-resistant kettle equipped with a jacket, stirrer, and thermometer, and polymerized at 80°C. After reaching the same temperature,
After cooling at 120°C for 20 minutes, filtering and washing, drying,
100 parts of the obtained solid bead polymer and 5 parts of stearic acid monoglycerol ester a were blended, and the mixture was shaped using a PCM-30 extruder manufactured by Ikegai Iron Works at 250° C. and a pressure of 1,755 Hg, and then pelletized. We conducted various evaluations using this polymer. In addition, for tensile strength measurement, Nippon Steel V17-6
Dumbbell type A molded at 250°C using a type 5 injection molding machine was used. A pellet is used to measure HDT and MFH. The overall residual rate in the pellet was 2%.

The light transmittance was 90% or more over all wavelengths, and even with zero heat decomposition resistance, no silver streak defects were observed, which was good.

Table 1 Comparative Example 1 The procedure was carried out in exactly the same manner as in Example 1 except for extrusion shaping without adding stearic acid monoglycerol ester.
The peelability was poor, with 18 defective products out of 20 shots.

Example 1B The same procedure as in Example 1 was conducted except that n-octyl mercaptan was used as ff1eα20, and the peelability was evaluated. As a result, the number of defective products out of 20 shots was 3 (slightly good). MFR was α8.

Examples 2-4. Comparative Examples 1 to 4 The composition of the monomer mixture and the type and proportion of the mold release agent shown in Table 2 were carried out in exactly the same manner as in Example 1, and the physical properties of each were evaluated. Shown in Table 2. The residual monomer in the pellet of Example 2 was α27, and in Examples 5 and 4, 400 parts of methanol was added to 100 parts of the polymer beads to 40 parts of the polymer beads obtained before drying. The pellets were washed for 1 hour at 0.degree. C. to remove unreacted monomers, and the amount of residual monomers in the pellets was reduced to 112% or less.

Comparative Example 4 was also washed with methanol in the same manner as Example 2.

Regarding optical distortion, Examples 2 to 4 all had an optical distortion of 20 degrees or less. Comparative Example 3 had a low light transmittance and could not be measured.
o The light transmittance of Examples 2 to 4 was 90% or more in all wavelength ranges measured.

Examples 5-10. Comparative Example 5 The composition of the monomer mixture was as shown in Table 3, and the type and type of release agent were as shown in Table 4. Obtained the evaluation results shown in the statement.

In Comparative Example 5, clouding occurred at the stage of specimen preparation, and the evaluation of the peelability, etc., was discontinued.

The light transmittance is 88 degrees or more in all wavelength ranges, and the optical strain is 23 degrees in Example 5 and 20 degrees or less in the others, so it can be suitably used as a base material for optical information recording media and is a friend. .

[Effect of the invention J From these results, the compositions of each example had high heat resistance;
It has excellent strength, optical properties, heat decomposition resistance, and mold release properties.
The copolymer composition of the present invention can be suitably used as a substrate for an optical information recording medium.

Claims (1)

[Claims] 1) Methyl methacrylate 95 to 50 as a monomer unit
Copolymer [I] 1 consisting of 0 to 20% by weight of aromatic vinyl compound and 5 to 30% by weight of N-substituted maleimide
00 parts by weight, R_1COOR_2(R_1, R_
2 represents an alkyl group having 5 to 20 carbon atoms), a fatty acid monohydric alcohol, stearyl alcohol, stearic acid, cetanol, stearic acid glycerin ester, and a perfluoroalkyl group/lipophilic group-containing oligomer [ II] A base material for an optical information recording medium containing 0.05 to 2.0 parts by weight and having a heat deformation temperature of 105°C or higher. 2) N-substituted maleimide is N-t-butylmaleimide,
The substrate for an optical information recording medium according to claim 1, which is at least one selected from the group consisting of N-cyclohexylmaleimide and N-arylmaleimide.