JPH0625326A - Alkoxy-substituted styrene copolymer hydride - Google Patents

Abstract

(57) [Summary] [Object] To provide an alkoxy-substituted styrene copolymer hydride suitable for optical materials and the like. [Structure] A styrene component (a) represented by the following repeating unit (1) and an alkoxy-substituted styrene component (b) consisting of (2), (a) :( b) = 50-90: 50-
At least 5 of the aromatic nuclei of the copolymer being 10 (mol%)
Alkoxy-substituted styrene copolymer hydride having 0% hydrogenation. [Chemical 1] (In the above formula, R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ₃ represents an alkyl group having 1 to 10 carbon atoms. R ₁ , R ₂ and R ₃ may be the same or different. It may be.)

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alkoxy-substituted styrene copolymer hydride. Specifically, optical materials having high heat resistance, high hardness, and chemical resistance, transparent structural materials,
The present invention relates to an alkoxy-substituted styrene copolymer hydride that can be used as a functional resin raw material. In particular, the present invention can provide a material for an optical disk substrate which is excellent in heat resistance, low hygroscopicity, low birefringence, transparency and adhesion to an information recording film.

[0002]

2. Description of the Related Art Since optical recording using a laser can record, store, and reproduce high density information, its development has been actively made in recent years. An optical disc can be given as an example of such optical recording. In general, an optical disc basically consists of a transparent substrate and various recording media coated thereon. A colorless transparent synthetic resin is often used for a transparent substrate of an optical disk, and a typical example thereof is polycarbonate (hereinafter, referred to as “P
It is abbreviated as C]. ) Or polymethylmethacrylate (hereinafter, abbreviated as “PMMA”). Materials for
In particular, it does not have all the requirements as an optical disk substrate, and has problems to be solved. For example, PC
There is a problem of birefringence due to the aromatic ring, and also a problem of water absorption or water permeability.
On the other hand, PMMA has been pointed out for some time in terms of heat resistance, water absorption and toughness.

As described above, each of these resins has been used with its inherent problems. However, in reality, a recording medium coated on a transparent substrate made of these resins is used. In relation to, there is a new problem as described below. Conventionally, various developments have been made on recording media according to the use of optical disks. For example, a write-once type that is exclusively used for recording and reproduction is a perforated type, and a erasable type that is used for recording, reproducing, erasing, and re-recording is a phase transition type that utilizes a crystal transition phenomenon. There is known a magneto-optical type that utilizes the magneto-optical effect. The materials for these recording media are tellurium or its oxides and alloy compounds in the write-once type, and GdFe, TbFe, GdFeCo, TdFeC in the erasable type.
Inorganic materials such as rare earth-transition metal amorphous alloy compounds such as o are mainly used, and are generally formed by forming a film on a transparent substrate by a dry processing method such as sputtering under high vacuum.

The hygroscopicity and water permeability of PC and PMMA, on the one hand, cause the problem of warpage due to expansion of the substrate itself during moisture absorption, but on the other hand, the permeation of moisture through the substrate causes corrosion of the recording medium. This causes the shortening of the life of the optical disc. Further, if the heat resistance of the resin for substrates is further mentioned, there are the following problems. That is, in the case of an optical disc, particularly a write-once type and an erasable type optical disc, the temperature of the recording medium at the time of writing and erasing the recording is as high as 200 ° C. or more.
For this reason, even if this heat is not directly applied to the disk substrate, it is expected that the substrate will reach a considerably high temperature during writing and erasing of recording, and if the resin has low heat resistance, the substrate will be deformed or the groove will be deformed. Problems can occur.

On the other hand, in the optical disc production process,
A heat treatment step is often incorporated for the purpose of preventing the substrate or recording medium from changing over time, but in order to improve productivity, it is desirable to shorten the treatment time by treating at a treatment temperature as high as possible. From this perspective,
If the heat resistance of the resin is low, a high processing temperature cannot be adopted, and there is a problem that productivity cannot be increased.

From the above, PMMA having a low heat resistance is completely insufficient to withstand the high temperature in the optical disc production process or usage condition.
PC having higher heat resistance is being investigated as a transparent substrate material. Furthermore, to compensate for the drawbacks of conventional resins such as PC and PMMA, it is mainly composed of carbon and hydrogen,
And there is a method of using a transparent resin with a high softening point,
It is proposed in JP-A-63-43910 and the like.

[0007]

However, such a hydrocarbon resin having a high softening point does not leak to an example of so-called low adhesion of polyolefin and has poor adhesion to a recording film layer, and is sufficient as an optical disc. There was a problem that life could not be obtained. The inventors of the present invention have made extensive studies on the method of improving the adhesion to the recording film layer, and as a result, by introducing an alkoxy group into the cyclohexane ring of the hydrogenated styrene polymer (polyvinylcyclohexane), the adhesion to the recording film is improved. The inventors have found that the properties are remarkably improved and have reached the present invention.

[0008]

That is, the gist of the present invention comprises a styrene component (a) represented by the following repeating unit (1) and an alkoxy-substituted styrene component (b) represented by the following repeating unit (2), The molar ratio of the components (a) and (b) is (a) :( b) = 50 to 90:50.
An alkoxy-substituted styrene copolymer hydride, characterized in that at least 50% of the aromatic nucleus of the copolymer is 10 to 10 (mol%),

[0009]

[Chemical 2]

(In the above formulas, R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ₃ represents an alkyl group having 1 to 10 carbon atoms, and R ₁ , R _{2 and} R ₃ represent It may be the same or different.). Hereinafter, the present invention will be described in detail. The alkoxy-substituted styrene copolymer hydride of the present invention can be used alone as a structural material and a functional resin (and a raw material thereof), including resins for optical materials such as optical disk substrates. Here, the hydride of the alkoxy-substituted styrene copolymer of the present invention comprises a styrene component (a) represented by the repeating unit (1) and a alkoxy-substituted styrene component (b) represented by the repeating unit (2) as repeating units. And an alkoxy-substituted styrene-styrene copolymer comprising: and the constituent ratio of each component of the copolymer is component (a): component (b) = 50 to 90 mol%: 5
It is a hydrogenated aromatic nucleus of the copolymer of 0 to 10 mol%.

The degree of hydrogenation of aromatic nuclei of the copolymer is at least 50%, preferably 55% to 100%,
More preferably, it may be in the range of 70% to 100%.
When the hydrogenation of the aromatic nucleus is less than 50%, the heat resistance is low and it is not preferable. The styrene component (a) constituting the above copolymer is represented by the repeating unit (1). R ₁ in the repeating unit (1) represents hydrogen or an alkyl group having 1 to 5 carbon atoms. Specific examples thereof include styrene, α-methylstyrene, p-methylstyrene and the like, and styrene is particularly preferable.

The alkoxy-substituted styrene component (b)
Represents a repeating unit (2), and R ₂ represents a lower alkyl group as described above or hydrogen. R3
Represents an alkyl group having 1 to 10 carbon atoms. The alkoxy-substituted styrene component (b) is specifically p-methoxystyrene, p-ethoxystyrene, pn propoxystyrene, p-isopropoxystyrene, pnbutoxystyrene, p-isobutoxystyrene, p-. tert
Butoxystyrene, m-tert butoxystyrene, p
-Tert-butoxy-α-methylstyrene and the like are mentioned, and p-tert-butoxystyrene is particularly preferable.

The composition ratio (molar ratio) of each component of the above-mentioned copolymer is as described above: component (a): component (b) = 50 to 9
Although it is 0:50 to 10 (mol%), when it is used as a resin for an optical disk substrate which has a lower water absorption and a better adhesiveness to a recording film, component (a): component (b) = 60 to 9
0:40 to 10 (mol%), preferably component (a): component (b) = 70 to 85:30 to 15 (mol%).

When the component (b) is less than 10 mol%, sufficient adhesiveness to the information recording film cannot be obtained when used as a resin for optical materials such as optical disk substrates, and 50 mol% is used. If it exceeds, the water absorption rate becomes high, and the problem that the disk warps due to water absorption occurs. When the copolymer hydride of the present invention is mixed with another resin to be used as an optical material, a styrene polymer hydride, preferably a hydride in which the aromatic nucleus of the styrene polymer is at least 50% hydrogenated. 0
More than 99% by weight, preferably 5 to 99% by weight,
More preferably, 10 to 99% by weight, more than 1% by weight of the hydride of the alkoxy-substituted styrene copolymer of the present invention,
It may be mixed and added so as to be less than 100% by weight, preferably 95 to 1% by weight, more preferably 90 to 1% by weight.

In this case, the hydrogenated styrene polymer is a hydrogenated product of a conventionally known styrene polymer, preferably a styrene polymer such as styrene, α-methylstyrene or paramethylstyrene, or styrene and butadiene, It is obtained by nuclear hydrogenation of a copolymer of dienes such as isoprene or a mixture thereof. The mixing treatment may be a solution or melt blending, but the mixing method is not particularly limited as long as it is sufficiently mixed.

When the above mixture is used, the proportion of the alkoxy-substituted styrene component in the hydride of the hydroxy-substituted styrene copolymer of the present invention is 10-4.
The amount is 0 mol%, preferably 15 to 30 mol%. If it is less than 10 mol%, sufficient adhesiveness to the information recording film cannot be obtained when used as a resin for optical materials such as optical disk substrates. On the other hand, if it exceeds 40 mol%, it is not preferable because the light transmittance is lowered and the water absorption is increased.

The method for producing the styrene-alkoxy substituted styrene copolymer is not particularly limited, and examples thereof include anionic polymerization, cationic polymerization, radical polymerization and the like. Examples of the radical polymerization include bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization, and ordinary peroxides and azo compounds are used as catalysts. The anionic polymerization is carried out in a hydrocarbon medium with an alkali metal such as Na, Li, K or an organic metal catalyst such as an alkyl sodium compound or an alkyl lithium compound. The polymerization temperature is preferably lower than room temperature.

Cationic polymerization is carried out using BF ₃ , SnCl ₄ , Ti
It is carried out at a low temperature using a Lewis acid such as Cl ₄ as a catalyst. Examples of the catalyst used for hydrogenation of aromatic nuclei in the production method of the present invention include nickel, cobalt, ruthenium, rhodium, platinum, metals such as palladium, oxides, salts and complexes thereof and activated carbon, diatomaceous earth, Examples include those supported on a carrier such as alumina and silica. Among these, Raney nickel, Raney cobalt, stabilized nickel and a catalyst in which palladium, ruthenium, rhodium or platinum are supported on carbon, alumina or silica are particularly preferable from the viewpoint of reactivity.

In the nuclear hydrogenation reaction, a saturated hydrocarbon solvent such as cyclohexane, methylcyclohexane, n-octane, decalin, tetralin and naphtha or tetrahydrofuran is used as a solvent at a pressure of 50 to 250 kg / cm ² and a temperature of 100 to 250 ° C. It is preferable to use an ether solvent such as (THF). The nuclear hydrogenation rate of aromatic nuclei by the nuclear hydrogenation reaction is preferably 50% or more. When the nuclear hydrogenation rate is less than 50%, there is a problem that the heat resistance of the obtained resin is lowered and birefringence is increased, which is not preferable. Furthermore, the hydrogenation rate is preferably 70% or more.

When the copolymer of the present invention is used alone as an optical material, it has a weight average molecular weight of 50,000.
It is more than 0 and 300,000 or less. The lower limit of the molecular weight is defined by the strength of the resin. When used in mixture with a styrene polymer hydride, the weight average molecular weight of the copolymer hydride is preferably 500 to 500,000, more preferably 1000 to 100,000.
Is used. The weight average molecular weight of the hydrogenated styrene polymer is preferably 20,000 to 500,000. The lower limit of the molecular weight of the hydrogenated styrene polymer is defined by the strength of the resin.

[0021]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist. In addition, various physical properties in the following Examples and Comparative Examples are measured by the following methods. Weight average molecular weight: measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent in the same manner as polystyrene,
The polystyrene-equivalent weight average molecular weight was determined. Nuclear hydrogenation rate (%): polyvinyl cyclohexane-based resin was dissolved in THF and measured by UV absorption. Glass transition temperature (° C.): The glass transition temperature was measured at a heating rate of 16 ° C./min using a scanning differential calorimeter (DSC) manufactured by Dupont. Light transmittance of optical disk substrate (%): JIS K
It measured based on 6714.

Example 1 <Copolymerization> A 4-necked flask equipped with a reflux condenser, stirring blades, and a thermometer was sufficiently replaced with nitrogen to obtain 4.10 mol of styrene and 0.819 mol of paratertiary butoxystyrene. Then, 0.835 g of benzoyl peroxide was added as a polymerization initiator. The mixture was heated to a temperature of 75 ° C. with stirring and reacted for 7 hours. After cooling the reaction solution, 3 liters of toluene was added and diluted, and this toluene solution was dropped into a large amount of methanol to precipitate a polymer. The precipitated polymer was filtered and dried to obtain 257 g of a styrene / paratertiary butoxystyrene copolymer. From the ¹³ C-NMR spectrum, the composition ratio of the obtained copolymer was styrene / paratertiary butoxystyrene = 79/21 (molar ratio).
Met. The weight average molecular weight was 230,000 (converted to polystyrene).

<Hydrogenation> 34.0 g of this copolymer was dissolved in 425 g of tetrahydrofuran, 10 g of 5% palladium / carbon catalyst (manufactured by NE-CHEMCAT) was added, and the mixture was placed in an autoclave and uniformly stirred. Replace with hydrogen, raise the temperature to 190 ° C, and add 100 kg of hydrogen.
The pressure was increased to / cm ² G and the hydrogenation reaction was performed for 20 hours.
After cooling, the pressure was released and the hydrogenated copolymer was taken out. From the UV spectrum, the nuclear hydrogenation rate was 98%. <Molding / Filming> This copolymer is processed by a small injection molding machine.
20mm x 20mm x 1.
A 5 mm molded piece was molded.

The molded piece thus obtained was loaded into a sputtering apparatus, first evacuated to 8 × 10 ^-7 torr or less, and reactive sputtering of a Ta target was performed using a mixed gas of Ar and O ₂ to produce Ta ₂ Interference layer consisting of O ₅ (thickness 800 ◆
A) was formed. Then, Tb target and FeCo
A TbFeCo recording layer (thickness: 300A) was provided by binary co-sputtering with Ar gas using a target. Further, an Al target on which a Ti chip was placed was sputtered in Ar gas to form a reflection layer having a thickness of 300A.

<Peeling Test> Eleven parallel and vertical lines were drawn with a knife in the area of 1 cm × 1 cm at 1 mm intervals in the mirror surface of the molded piece provided with this film, and the obtained cross-cut was obtained. Stick Teraoka's adhesive tape (imide film base) on the shaped part and peel it off,
The adhesion strength was evaluated. As a result, none of 100 pieces of 1 mm × 1 mm square cross-section test pieces were peeled off. The water absorption was 0.13%.

Comparative Example 1 <Production of Hydrogenated Styrene / Paratertiary Butoxystyrene Copolymer> 0.84 mol of styrene and 0.819 of paratertiary butoxystyrene were used instead of 4.10 mol of styrene in Example 1. A hydrogenated styrene / paratertiary butoxystyrene copolymer was obtained by performing the same procedure as the copolymerization and hydrogenation reaction of Example 1 except that the amount was changed to 0.0722 mol. The composition ratio of the copolymer is styrene / para-tertiarybutylstyrene 91.5 / 8.5.
(Mole ratio), weight average molecular weight 190,000, nuclear hydrogenation rate 1
It was 00%.

<Molding / film formation> Obtained hydrogenated styrene /
The parahydroxystyrene copolymer (styrene / paratertiary butoxystyrene = 92/8 molar ratio) was treated in the same manner as in the molding / film formation of Example 1, and then in the same manner as the peeling test of Example 1. As a result of the test, 38 out of 100 sheets were peeled off.

Comparative Example 2 <Production of Hydrogenated Polystyrene> In the hydrogenation reaction of Example 1, polystyrene (trade name: Diamond, manufactured by Mitsubishi Kasei Polytech Co., Ltd.) was used instead of 35.2 g of styrene / paratertiary butoxystyrene copolymer. Rex (registered trademark) H
H-102: weight average molecular weight 250,000) 100 g of hydrogenated polystyrene (nuclear hydrogenation rate 100%, weight average molecular weight 170,000) was obtained by the same procedure as in the hydrogenation reaction of Example 1.

<Molding / Filming> The obtained hydrogenated polystyrene (nuclear hydrogenation rate 100%, weight average molecular weight 170,000) was subjected to molding / filming in the same manner as in Example 1 and a peeling test was conducted. The number was 100 out of 100.

Comparative Example 3 In place of 4.10 mol of styrene and 0.819 mol of paratertiary butoxystyrene of Example 1, 4.0 of styrene was used.
Polymerization similar to the radical polymerization of Example 1 was carried out using 8 mol and 3.34 mol of methyl methacrylate, and the obtained styrene / methyl methacrylate copolymer (styrene / methyl methacrylate = 52/48 mol ratio, Weight average molecular weight 2
80,000) is hydrogenated in the same manner as in Example 1,
A hydrogenated styrene / methyl methacrylate copolymer having a nuclear hydrogenation rate of 100% was obtained. This copolymer was molded and formed into a film in the same manner as in Example 1 and was subjected to a peeling test.
The number was 100 out of 00. The absorption rate was 0.18%. Table 1 summarizes the results of Examples and Comparative Examples.

[0031]

[Table 1]

The alkoxy-substituted styrene copolymer hydride of the present invention has excellent heat resistance and transparency, good adhesion to the information recording film, and low hygroscopicity, and is an optical material especially for optical disk substrates. Can be suitably used.

Claims (4)

[Claims] 1. A styrene component (a) represented by the following repeating unit (1) and an alkoxy-substituted styrene component (b) represented by the following repeating unit (2), wherein the component (a) and the component (b) The molar ratio of (a) :( b) = 50-
An alkoxy-substituted styrene copolymer hydride characterized in that at least 50% of the aromatic nucleus of the copolymer having a ratio of 90:50 to 10 (mol%) is hydrogenated. [Chemical 1] (In the above formula, R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ₃ represents an alkyl group having 1 to 10 carbon atoms. R ₁ , R _{2 and} R ₃ may be the same or different. It may be.) 2. The hydrogenated alkoxy-substituted styrene copolymer according to claim 1, wherein R ₃ of the repeating unit (2) is a tertiary butyl group. 3. The alkoxy-substituted styrene copolymerization product according to claim 1, wherein the molar ratio of component (a) and component (b) is (a) :( b) = 70-85: 30-15. Combined hydride. 4. An optical material comprising the alkoxy-substituted styrene copolymer hydride according to claim 1.