JP2002069257A - Hydrogenated styrene polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogenated styrene polymer composition easy in mold release without damaging the transparency. SOLUTION: This hydrogenated styrene polymer composition contains 10-10,000 ppm compound having a repeated unit represented by formula (A) and a kinematic viscosity not less than 1 mm2/s but less than 50 mm2/s in a hydrogenated styrene polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a hydrogenated styrenic polymer composition. More specifically, the present invention relates to a hydrogenated styrene-based polymer composition suitable for optical disc applications having excellent transparency and releasability.

[0002]

2. Description of the Related Art Conventionally, polycarbonate has been exclusively used as a material for optical disks such as CDs and DVDs because of its excellent transparency, heat resistance and impact resistance. In recent years, the wavelength of an optical pickup has been shortened with the increase in the capacity of a magneto-optical disk (MOD) and the capacity of a DVD. Since polycarbonate has an aromatic ring in the main chain, it has a high intrinsic birefringence and tends to cause optical anisotropy in a molded product. Further, since the shorter the wavelength of light, the more easily the optical anisotropy is affected, a hydrogenated styrene-based polymer has been proposed as one of the materials for solving such a problem. For example, Japanese Patent Publication No. 7-114030
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses an optical disk having a substrate made of hydrogenated polystyrene resin. The resin has a feature that it has a high light transmittance, a very low birefringence and a low water absorption as compared with a polycarbonate resin, and has favorable characteristics as an optical disk material. In order to further improve the brittleness of such resins, styrene-conjugated diene block copolymers in which styrene is block-copolymerized with conjugated dienes such as isoprene and butadiene to introduce a rubber component are used in optical disk substrates and other products. Has been disclosed so far for use in optical applications. For example, Japanese Patent No. 2668945 describes conditions of molecular weight and softening temperature for satisfying heat resistance during processing into an optical disk.

Generally, when molding optical disk materials such as polycarbonate into an optical disk, Japanese Patent Application Laid-Open No.
As disclosed in JP-A-92-92 and the like, a releasing agent such as glycerin monostearate is added to reduce factors such as disk release failure, thereby improving the releasing property and stabilizing the process. On the other hand, at present, little is known about the releasability of hydrogenated styrene-based polymers.

[0004]

As described above, the hydrogenated styrenic polymer has little knowledge about the mold release properties and mold release agents for optical disc molding. In general, when a copolymer component such as a conjugated diene is included to improve toughness, the modulus becomes low, so that the releasability is poor, and the above-described mold release failure and the optical disk warp occur, thereby hindering the stabilization of the process. There are concerns. Glycerin monostearate used in polycarbonate has a problem such as the mold being stained during molding due to low molecular weight, and the mold is not stained, and the mold releasability of the hydrogenated styrene polymer is improved. In addition, a polymer composition that does not impair the transparency of the optical disk has been desired.

[0005]

In view of such circumstances, we have considered that a hydrogenated styrenic polymer composition in which a polysiloxane having a specific kinematic viscosity range is added in a specific concentration range can be separated without impairing the transparency of the disk. It was found that the moldability was improved. That is, the present invention provides a hydrogenated styrene-based polymer, which may be copolymerized with a hydrogenated conjugated diene component, having a kinematic viscosity of 1 mm ² / s or more and less than 50 mm ² / s, represented by the following formula (A):

[0006]

Embedded image

[R ¹ and R ² are the same or different and each have 1 carbon atom.
It is an aliphatic hydrocarbon group having 10 to 10 or less or an aromatic hydrocarbon group having 6 to 10 carbon atoms. ] Is a hydrogenated styrene-based polymer composition which may be copolymerized with a hydrogenated conjugated diene component containing a compound having a repeating unit of 10 to 10,000 ppm.

In the present invention, a polymer composition wherein the proportion of the hydrogenated conjugated diene component in the hydrogenated styrene-based polymer is 30% by weight or less, and the reduced viscosity of the hydrogenated styrene-based polymer is 0% The composition also includes a hydrogenated styrene-based polymer composition having a haze value of from 2 to 15 dL / g to 1.5 dL / g and a 2 mm-thick molded plate having a haze value of 3% or less. Further, a polymer composition in which these hydrogenated styrene-based polymer compositions are used for optical disks is also included.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrogenated styrenic polymer used in the present invention refers to a polymer in which styrenes are the main component of the monomer, in which the aromatic ring is replaced by the number of moles corresponding to a double bond. The hydrogenation rate is 90 mol% or more as a hydrogenation ratio based on the total number of moles of the double bond and the aromatic ring in the copolymer component. Such styrenes include styrene, α-methylstyrene, p
-Methylstyrene, vinylnaphthalene and the like.
Of these, styrene is most preferred in view of availability and polymer properties. These may be used alone or in combination of two or more. The styrenic polymer used for hydrogenation may be obtained by copolymerizing components other than styrenes. Examples of such components include conjugated dienes. Conjugated dienes include butadiene, isoprene, 2,3-dimethylbutadiene, 2,3-pentadiene, 2,3-hexadiene and the like. Among these, polymerization activity,
Isoprene and 1,3-butadiene are preferably used from the viewpoint of economy. These may be used alone or in combination of two or more. The proportion of the conjugated diene component after hydrogenation is preferably 30% by weight or less, more preferably 27% by weight or less, and further preferably 25% by weight or less. By copolymerizing the conjugated diene component to the styrene polymer used for hydrogenation, the toughness of the hydrogenated styrene polymer can be improved,
If the proportion of the conjugated diene component exceeds 30% by weight after hydrogenation, the heat resistance of the hydrogenated styrene-based polymer is undesirably deteriorated. The weight fraction of such hydrogenated conjugated diene component is ¹ H
-NMR and ¹³ C-NMR can be used for the measurement.

[0010] When the conjugated diene component is copolymerized with a styrene-based polymer, a random copolymer, a block copolymer and the like can be mentioned as a bonding mode. A random copolymer is one in which each copolymer component is arranged without substantial regularity to form a molecular chain. The block copolymer is one in which the molecular chain blocks of each component are bonded in one molecular chain. Among these bonding modes, a block copolymer is preferable from the viewpoint of heat resistance.

A method for producing a hydrogenated styrene-based polymer is obtained by first synthesizing a styrene-based polymer to be a prepolymer and then hydrogenating the styrene-based polymer. The method for producing the styrene polymer is not particularly limited, and a general radical polymerization method, an anion polymerization method, a cationic polymerization method, or the like is preferably used.

The method for hydrogenating the styrene-based polymer is not particularly limited as long as it can efficiently hydrogenate aromatic and C ＝ C double bonds. In general, the hydrogenation is carried out in an inert solvent in the presence of a hydrogenation catalyst at an elevated temperature under hydrogen pressure. The inert solvent is preferably a saturated hydrocarbon having 5 to 14 carbon atoms such as hexane, heptane, octane, dodecane, cyclohexane, cycloheptane, cyclodecane, and methylcyclohexane, and among them, cyclohexane and methylcyclohexane are most preferred. Used for As the hydrogenation catalyst, a solid catalyst in which a metal of Group VIII such as nickel, palladium, platinum, cobalt, ruthenium, and rhodium or a compound thereof is supported on a porous carrier such as carbon, alumina, silica, silica alumina, and diatomaceous earth, or vanadium and chromium , Manganese, iron, ruthenium, cobalt, nickel, palladium, etc., halides of the group IV to VIII, acetylacetonate complex, carboxylate complex, naphthate complex, trifluoroacetate complex,
A homogeneous catalyst such as a stearate complex may be used. Among them, those in which nickel, palladium, and platinum are supported on silica, silica alumina, and diatomaceous earth have high activity and are preferably used. These hydrogenation catalysts may be used alone or in combination.

The hydrogenation rate of the copolymer in the present invention is 90
Mol% or more. Here, the hydrogenation rate is defined as the hydrogenation rate with respect to the total number of moles of the double bond and the aromatic ring in the copolymer, where 1 mole of the aromatic ring is replaced by the number of moles corresponding to the double bond. Refers to. For example, in the case of a copolymer using styrene, those in which the unhydrogenated styrene portion remains a phenyl group are calculated as 3 moles of a double bond. Usually, the double bond derived from the conjugated diene moiety is much more easily hydrogenated than the aromatic ring, and is almost completely hydrogenated in the present invention. On the other hand, when the aromatic ring is unhydrogenated, most of the ring remains the aromatic ring, but there are a few cases where the ring is partially hydrogenated to form a double bond.

After the completion of the hydrogenation reaction, the catalyst can be removed by a known post-treatment method such as centrifugation or filtration. In the present invention, the residual metal catalyst component in the resin must be as small as possible.
pm or less, more preferably 1 ppm or less, and even more preferably 500 ppb or less. From the polymer solution from which the hydrogenation catalyst has been removed, the intended hydrogenated styrene-based polymer can be obtained by a method such as evaporation of the solvent, stripping, and reprecipitation.

The molecular weight of the hydrogenated styrenic polymer of the present invention is a reduced viscosity (ηsp) which is a representative measure of the molecular weight.
/ C). Considering the mechanical strength and molding processability of the molding material, the concentration is 0.5 g / dL.
In toluene solution at a reduced viscosity measured at 30 ° C. of 0.15
It is preferably in the range of dL / g to 1.5 dL / g, more preferably 0.2 dL / g to 1.0 dL / g.
, More preferably 0.3 dL / g or more and 0.8 d
L / g. If the reduced viscosity is less than 0.15 dL / g, the mechanical strength is insufficient. If the reduced viscosity is more than 1.5 dL / g, the melt viscosity is too high, the fluidity is insufficient, and molding becomes difficult, which is not preferable.

The glass transition temperature of the hydrogenated styrenic polymer in the present invention is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 130 ° C. or higher. When the glass transition temperature is lower than 110 ° C., heat resistance is poor, and the glass is easily deformed by heat when writing or reading information with a laser, which is not preferable.

The hydrogenated styrenic polymer composition of the present invention is defined by the following formula (A):

[0018]

Embedded image

[R ¹ and R ² are the same or different and each have 1 carbon atom.
It is an aliphatic hydrocarbon group having 10 to 10 or less or an aromatic hydrocarbon group having 6 to 10 carbon atoms. ] As a repeating unit. The structure of such a compound may have a linear or branched molecular chain. In the formula (A), R ¹ and R ² are the same or different and are an aliphatic hydrocarbon group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms. For example, methyl group, ethyl group,
Normal propyl group, isopropyl group, normal butyl group, isobutyl group, tert-butyl group, neopentyl group, cyclohexyl group, methylcyclohexyl group, 2-
Ethylhexyl, phenyl, benzyl, 2-methylphenyl, 2,6-dimethylphenyl, 2,4
6-trimethylphenyl group, naphthyl group and the like. Among these compounds, polydimethylsiloxane is preferably used from the viewpoint of availability.

Kinematic viscosity at 25 ° C. under normal pressure is used as an index of the molecular weight of a compound having the above formula (A) as a repeating unit. The compound used in the present invention has a kinematic viscosity of 1 mm ² / s
Not less than 50 mm ² / s. Preferably 2m
m ² / s or more and less than 45 mm ² / s, more preferably 5 mm ² / s or more and less than 40 mm ² / s. If the kinematic viscosity is less than 1 mm ² / s, problems such as foaming during mixing with the resin, stains on the mold and the like occur, and the kinematic viscosity is 50 mm ² / s
Above, the compatibility with the styrenic polymer becomes difficult, and the transparency of the molded product deteriorates, which is not preferable. Such compounds may be mixtures. There is a correlation between the kinematic viscosity of such compounds and the average molecular weight.
The relationship between the kinematic viscosity at 5 ° C. and the average molecular weight is described in J. Am. Che
m. Sci. Part A, VOL 3, 2947 (196
5) and the like.

The method for producing the hydrogenated styrene polymer composition in the present invention may be any method as long as the compound having the above-mentioned formula (A) as a repeating unit can be uniformly mixed. The compound may be produced by adding and kneading such a compound in a molten state of the polymer, or may be produced by adding the compound to a hydrogenated styrene-based polymer solution after the hydrogenation step and removing the solvent.

The proportion of the compound of the formula (A) in the hydrogenated styrenic polymer composition of the present invention is from 10 ppm to 10,000 ppm. More preferably 100p
pm to 5000 ppm, more preferably 500 ppm
ppm or more and 3000 ppm or less. If the proportion of the compound of the above formula (A) is less than 10 ppm, the desired effect of improving the releasability cannot be obtained, and if it exceeds 10,000 ppm, undesired haze is generated in the molded product as an optical material, which is both undesirable. If necessary, a release agent other than the above formula (A) may be added. Preferred examples of the release agent include fatty acid ester-based release agents, fatty acid-based release agents, and fatty acid amide-based release agents. In the present invention, good releasability is defined as having a small releasing force.

It is preferable to add a stabilizer to the composition of the present invention in order to improve the thermal stability during melt molding. As a stabilizer, for example, Irganox 245, 24
5FF, 259, 565, 565FL, 1010, 10
10FP, 1010FF, 1010DD, 1035F
F, 1076, 1076FF, 1076FD, 109
8, 1222, 1330, 1425WL, 3114, 5
057, 1520L, 1520LR, 1135, 114
1 (manufactured by Ciba Specialty Chemicals), Sumilizer BHT, BHT-P, MDP-S, BBM-S,
WX-R, WX-RA, WX-RC, NW, GA-80
(Manufactured by Sumitomo Chemical Co., Ltd.)
An acrylate compound having a partially hindered phenol group, such as Sumilizer GS, GM (manufactured by Sumitomo Chemical Co., Ltd.);
HP136 (Ciba Specialty Chemicals)
Benzofuranone compounds such as Irgafos 168, 1
Phosphite compounds such as 68FF, 12 (manufactured by Ciba Specialty Chemicals), Sandstub P-EPQ (manufactured by Clariant), Irganox E201, E
17, vitamin E-based compounds such as E120 (manufactured by Ciba Specialty Chemicals), Irganox PS80
0FL, PS802FL (made by Ciba Specialty Chemicals), Sumilizer TPL-R, TPM, TP
Examples thereof include sulfur compounds such as S, TP-D, and MB (manufactured by Sumitomo Chemical Co., Ltd.), and amine compounds such as Sumilizer 9A (manufactured by Sumitomo Chemical Co., Ltd.). Any of these and any combination can be used, and among them, those containing a hindered phenol group-containing acrylate compound or a benzofuranone-based compound are preferable. Such a stabilizer is used in an amount of from 500 ppm to 50,000 ppm, preferably from 1,000 ppm to 30,000 ppm, more preferably from 2,000 ppm to 20,000 ppm, based on the polymer. When the amount of the stabilizer exceeds 50,000 ppm, it causes haze or coloring of the hydrogenated styrene-based polymer, and when the amount of the stabilizer is less than 500 ppm, the effect becomes insufficient, which is not preferable. If necessary, conventionally known additives such as a plasticizer, an ultraviolet absorber, a light stabilizer, an antistatic agent, a processing stabilizer, and a flame retardant can be added.

The transparency of the hydrogenated styrenic polymer composition of the present invention is determined based on the haze value of a 2 mm thick molded plate. Such a haze value is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less.
If the haze value exceeds 3%, the S / N ratio decreases when reading with a laser beam, which makes it difficult to read. In order to reduce the haze value to 3% or less, as described above, among the compounds represented by the formula (A), the kinematic viscosity is 50 mm.
It can be achieved by a method using less than ² / s, maintaining the ratio of the compound of the above formula (A) at 10,000 ppm or less, or maintaining the ratio of the stabilizer at 50,000 ppm or less.

The optical disk in the present invention is a CD, D
An information recording medium on which data is read and / or written by laser light such as VD. When manufacturing such an optical disk, the pit or land-groove shape is transferred onto the disk surface by injection molding or the like. For example, when producing a disk of the hydrogenated styrene-based polymer composition by injection molding, the injection temperature is 230 ° C. or higher and 380 ° C.
It is below ° C. Preferably 250 ° C. or more and 360 ° C. or less,
More preferably, it is 270 ° C or more and 340 ° C or less. If the injection temperature is lower than 230 ° C., the fluidity of the resin is poor and pits and land-grooves cut on the stamper cannot be transferred satisfactorily. On the other hand, when the temperature exceeds 380 ° C., a part of the hydrogenated styrene-based polymer causes a decrease in molecular weight due to thermal deterioration, and the mechanical strength of the obtained molded product is undesirably reduced. On the other hand, the temperature of the mold is not less than 60 ° C and not more than 150 ° C. Preferably it is 65 to 145 ° C, more preferably 70 to 140 ° C. If the mold temperature is less than 60 ° C., pits and land-grooves cannot be transferred satisfactorily. If the mold temperature exceeds 150 ° C., the molded product is softened, causing problems such as warpage and sticking to the mold. .

[0026]

The use of the hydrogenated styrenic polymer composition of the present invention has improved the releasability without lowering the transparency of the molded article than the conventional hydrogenated styrenic polymer. This is expected to stabilize the process by reducing mold release defects. At the same time, it is possible to rapidly perform disk formation without warpage, and the polymer composition is suitable for disk use.

[0027]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to these examples.

The items measured in Examples, Reference Examples and Comparative Examples were measured by the following methods. 1) Hydrogenation rate, stabilizer content, conjugated diene component weight fraction: J
Using EX-270 manufactured by EOL, NMR measurement was performed at room temperature using deuterated chloroform as a solvent and tetramethylsilane as an internal standard. 2) Release agent content: Using EX-270 manufactured by JEOL,
Using deuterated chloroform as a solvent, NMR measurement was performed at room temperature without using an internal standard. 3) Glass transition temperature (Tg): TAInstrumen
ts Model 2920 DSC, temperature rise rate 20 ° C
/ Min. 4) Molecular weight: Using Shodex GPC system 11,
The measurement was performed using monodisperse polystyrene as a standard polymer and THF as an eluent. 5) Reduced viscosity: of a toluene solution having a concentration of 0.5 g / dL,
The reduced viscosity ηsp / C at 30 ° C. was measured. 6) Light transmittance: An ultraviolet-visible spectrometer (UV-240) manufactured by Shimadzu Corporation was used. 7) Haze value: An automatic digital haze meter NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used. 8) Release force measuring method: Molding was performed using a small injection molding machine M50-B manufactured by Meiki Seisakusho Co., Ltd., and using resin dried at 100 ° C. overnight overnight. In the above molding machine,
When a mold with two 50 mm x 100 mm x 2 mm plates carved is installed and molded at a resin temperature of 335 ° C and a mold temperature of 120 ° C, it is necessary to remove the molded plate from the mold with an automatic pin. The hydraulic pressure was used as the releasing force, and the average value of the values measured ten times was used as the measured value.

For the kinematic viscosity, the quality inspection value of the purchase manufacturer was used as it was.

REFERENCE EXAMPLE 1 A polystyrene GP158K manufactured by BASF AG was subjected to a hydrogenation reaction as follows using a nickel catalyst supported on silica (purchased from Aldrich, nickel supported at 65% by weight) in a cyclohexane solvent. went.

A 10 L stainless steel autoclave with a magnetic stirring blade was used as a reaction vessel. In a container, 750 g of the polystyrene, 2,200 g of cyclohexane (purchased from Wako Pure Chemical Industries), 1500 g of methyl tertiary butyl ether (purchased from Kanto Kagaku), 118 g of the nickel catalyst supported on silica alumina were charged.
Then, after replacing with hydrogen gas, 180 ° C., hydrogen pressure 10M
A hydrogenation reaction was performed at Pa for 160 minutes. After the container was cooled to around normal temperature, the inside of the container was returned to normal pressure, and the inside of the container was replaced with nitrogen to obtain a cyclohexane solution of hydrogenated polystyrene containing a nickel catalyst supported on silica alumina. This solution was filtered under a nitrogen pressure of 0.4 MPa with a membrane filter having a pore diameter of 0.1 μm to remove the nickel catalyst supporting silica-alumina, thereby obtaining 4200 g of a colorless and transparent hydrogenated polystyrene cyclohexane solution. A part of the obtained hydrogenated polystyrene cyclohexane solution was collected and subjected to various analyses. ^{From 1} H-NMR analysis, the hydrogenation rate was 99.0.
%Met. The glass transition temperature is 148 ° C from DSC measurement.
Met. From GPC measurement, the weight average molecular weight (Mw) in terms of polystyrene was 180,000. Concentration 0.5
The reduced viscosity ηsp / C measured at 30 ° C. in a g / dL toluene solution was 0.50 dL / g.

Example 1 2.2 g of polydimethylsiloxane (manufactured by Toray Dow Corning Silicone Co., Ltd.) having a kinematic viscosity of 20 mm ² / s at 25 ° C. was added to 12 kg of the hydrogenated polystyrene cyclohexane solution obtained by the method of Reference Example 1, and stable. After dissolving 17 g of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) as an agent, cyclohexane is removed by heating under reduced pressure, pelletized, and hydrogenated styrene polymer composition 2 k
g was obtained.

The obtained hydrogenated styrene polymer composition contained 1100 ppm of polydimethylsiloxane (manufactured by Toray Dow Corning Silicone Co., Ltd.), 5600 ppm of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), and had a reduced viscosity of 0 ppm. It was .50 dL / g. The ratio of the conjugated diene component was 0% by weight.

The hydrogenated styrene polymer composition was injection molded at a cylinder temperature of 335 ° C. and a mold temperature of 120 ° C. The release force for releasing this molded product from the mold is 0.91 MPa
Thus, the molded product could be taken out without difficulty. The haze of the obtained molded plate having a thickness of 2 mm was 0.3%.

Comparative Example 1 After 17 g of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) was dissolved as a stabilizer in 12 kg of the hydrogenated polystyrene cyclohexane solution obtained by the method of Reference Example 1, cyclohexane was removed by heating and reducing the pressure.
Pellets were obtained to obtain 2 kg of a hydrogenated polystyrene composition.

Sumidizer GS (manufactured by Sumitomo Chemical Co., Ltd.) in the obtained hydrogenated styrene-based polymer composition was 5600 ppm.
And the reduced viscosity of the composition was 0.50 dL / g.
The ratio of the conjugated diene component was 0% by weight.

The hydrogenated styrene polymer composition was injection molded at a cylinder temperature of 335 ° C. and a mold temperature of 120 ° C. The release force for releasing this molded product from the mold is 0.96 MPa.
And a phenomenon in which the molded piece was difficult to remove was observed. The haze of the obtained 2 mm-thick molded plate was 0.1%.

Comparative Example 2 22 g of polydimethylsiloxane having a kinematic viscosity of 20 mm ² / s at 25 ° C. (manufactured by Toray Dow Corning Silicone Co., Ltd.) was added to 12 kg of the hydrogenated polystyrene cyclohexane solution obtained by the method of Reference Example 1, and as a stabilizer After dissolving 17 g of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), cyclohexane is removed by heating and depressurizing, pelletized, and hydrogenated styrene polymer composition 2
kg.

The obtained hydrogenated styrenic polymer composition contained 11,000 ppm of polydimethylsiloxane (manufactured by Toray Dow Corning Silicone Co., Ltd.), 5600 ppm of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), and had a reduced viscosity of 0%. It was .50 dL / g. The ratio of the conjugated diene component was 0% by weight.

The hydrogenated styrene polymer composition was injection molded at a cylinder temperature of 335 ° C. and a mold temperature of 120 ° C. The release force for releasing this molded product from the mold is 0.67 MPa.
Thus, the molded product could be taken out without difficulty. Also,
The haze of the obtained molded plate having a thickness of 2 mm was 83%.

Comparative Example 3 2.2 kg of a polydimethylsiloxane having a kinematic viscosity of 50 mm ² / s at 25 ° C. was added to 12 kg of the hydrogenated polystyrene cyclohexane solution obtained by the method of Reference Example 1.
g, and 17 g of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) as a stabilizer, and then cyclohexane was removed by heating under reduced pressure to form pellets, thereby obtaining 2 kg of a hydrogenated styrene polymer composition.

The obtained hydrogenated polystyrene composition contained 1100 ppm of polydimethylsiloxane (manufactured by Toray Dow Corning Silicone Co., Ltd.), 5600 ppm of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), and had a reduced viscosity of 0.50 dL / g. The ratio of the conjugated diene component was 0% by weight.

The hydrogenated styrene polymer composition was injection molded at a cylinder temperature of 335 ° C. and a mold temperature of 120 ° C. The release force for releasing this molded product from the mold is 0.58 MPa.
Thus, the molded product could be taken out without difficulty. The haze of the obtained 2 mm thick molded plate was 87%.

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) (C08L 53/02 (C08L 53/02 83:04) 83:04) (72) Inventor Shunichi Matsumura Sunrise in Iwakuni City, Yamaguchi Prefecture 2-1 Town No.1 Teijin Limited Iwakuni Research Center F-term (reference) 4J002 BC021 BC051 BP011 CP032 GS02 5D029 KA13

Claims (5)

[Claims] 1. A method according to claim 1, wherein the hydrogenated styrene-based polymer which may be copolymerized with a hydrogenated conjugated diene component has a kinematic viscosity of 1 mm ²
A compound having a repeating unit of the following formula (A) of not less than 50 mm ² / s and not more than 50 mm ² / s,
A hydrogenated styrenic polymer composition containing at most ppm. Embedded image [R ¹ and R ² are the same or different and are an aliphatic hydrocarbon group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms. ] 2. The hydrogenated styrene-based polymer composition according to claim 1, wherein the proportion of the hydrogenated copolymerized conjugated diene component in the hydrogenated styrene-based polymer is 30% by weight or less. 3. In a toluene solution having a concentration of 0.5 g / dL,
The hydrogenated styrene-based polymer composition according to claim 1 or 2, wherein the reduced viscosity of the hydrogenated styrene-based polymer measured at 30 ° C is 0.15 dL / g or more and 1.5 dL / g or less. 4. The method according to claim 1, wherein the haze value of the 2 mm-thick molded plate is 3% or less.
Item 6. The hydrogenated styrenic polymer composition according to item 1. 5. The hydrogenated styrenic polymer composition according to claim 1, which is used for an optical disk substrate.