JP2518735B2 - Novel transparent styrene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel transparent styrene resin composition.

More specifically, the present invention relates to a styrene composed of a styrene-based structural unit and an acrylic ester (methacrylic acid ester) -based structural unit in a specific ratio, and a structural unit having a long alkyl chain represented by a specific structural formula. The present invention relates to a styrene-based resin composition having excellent transparency, which comprises a system polymer (I) and a block copolymer (II) having an aromatic hydrocarbon polymer block and a conjugated diene polymer block.

(Prior Art and Problems) Styrene-based resins have been widely used as molding materials for household products, electric appliances, etc., because they are excellent in transparency, moldability, and rigidity.

As the field of use expands, there is a strong demand for improving the strength of styrene resins. To increase the molecular weight,
Methods have been used to optimize the molecular weight distribution, but have not yet met the market demands. In order to improve the strength of the styrene resin, a method of blending polystyrene and a rubber-like elastic material, particularly a styrene-butadiene block copolymer, is widely used as a general method.

However, this resin has a large decrease in transparency as compared with polystyrene, and there is a strong demand for improvement in the market. Further, since the styrene-butadiene block copolymer is expensive, it is required to reduce the usage amount as much as possible.

Polystyrene and rubber-like elastic blends are often used in the sheet field, but in addition to the above-mentioned reasons, improvement in moldability and improvement in deep drawability are required. Further, due to recent environmental problems, there is a demand for a resin that replaces a vinyl chloride resin. For this purpose, a resin having a low glass transition temperature is required.

Various improvements have been made on resins made of polystyrene and rubber-like elastic materials, but none of them have satisfied the market demand.

In order to break this limit, it is known to introduce a second monomer copolymerizable with the styrenic monomer to lower the heat resistance. It is expected that the object of the present invention can be obtained by blending this resin with the rubber elastic body. However, in reality, even when the rubber elastic body is blended, when the rubber elastic body is blended with polystyrene. Compared to
The strength improving effect is small and the object of the present invention cannot be achieved.

Japanese Unexamined Patent Publication (Kokai) No. 2-103207 discloses a butyl acrylate or butyl acrylate and 2-
There is a description that copolymerization of a mixture of ethylhexyl methacrylate and styrene was performed. However, the ratio of styrene monomer / acrylic acid ester (methacrylic acid ester) monomer is 70/30 to 40/60 (g / g), and the amount of styrene monomer is small, and the polymerization method is suspension polymerization. (Integral polymerization), because the polymerization temperature is as low as 75 ℃ ~ 105 ℃,
The obtained styrene resin is opaque and cannot be used for applications requiring transparency because it is opaque even when blended with a rubber-like elastic material.

(Means for Solving the Problems) In view of the present situation, the present inventors have made earnest studies, and as a result, as a second monomer copolymerizable with a styrene-based monomer, an acrylic ester (methacrylic acid) Ester) and a specific amount of a long chain alkyl chain introduced by a proper method, and a block copolymer having an aromatic hydrocarbon polymer block and a conjugated diene polymer block. A transparent styrene resin composition having excellent balance of transparency, moldability, and strength is obtained, and transparency can be obtained by molding the styrene resin composition.
The inventors have found that a sheet or film excellent in strength and moldability, and a molded product excellent in transparency and strength can be obtained, and completed the present invention.

That is, the present invention is: (1) General formula (A); (In the formula, R ₁ is hydrogen or a methyl group, and R ₂ is hydrogen or an alkyl group having 1 to 5 carbon atoms) (B); (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an alkyl group having 1 to 8 carbon atoms. However, when R ₁ is a methyl group, R ₂ has 2 to 8 carbon atoms. It is an alkyl group.) (C); (In the formula, l and n are integers of 1 to 20, m is an integer of 0 or 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are each hydrogen or 1 to 5 carbon atoms.
Is an alkyl group, a cyclohexyl group or a phenyl group. ), The structural unit (A), (B)
Is (A): 80-99.5mol% (B): 0.5-20mol% (however, (A) + (B) = 100mol%), and the structural unit ratio (C) / ((A) + (B)) = 0.01
To a vinyl aromatic hydrocarbon having at least one vinyl aromatic hydrocarbon polymer block and at least one conjugated diene-based polymer block. A resin composition comprising a block copolymer (II) having a weight ratio of styrene to a conjugated diene of 60:40 to 95: 5, the weight of the styrene polymer (I) and the block copolymer (II) The novel transparent styrene resin composition is characterized in that the ratio is 99: 1 to 20:80. Hereinafter, the present invention will be described in detail.

The amount of the structural unit (B) is in the range of 0.5 to 20 mol%. More preferably, it is in the range of 1 to 17 mol%. If it exceeds 20 mol%, the heat resistance will decrease, resulting in sheets, films,
The practical range of the molded product becomes very narrow. Further, the transparency is also deteriorated, which is not preferable. If it is less than 0.5 mol%, the effect of shortening the molding cycle is small, and a sheet, film or molded body having excellent strength cannot be obtained.

Structural unit (C) / [(A) + (B)] is 0.01 to 0.0000
It is in the range of 1. More preferably, it is in the range of 0.005 to 0.00005. If it exceeds 0.01, the effect of improving the strength becomes small, and the cost of the styrene resin and those styrene resin sheets, films, and molded products increases. Further, when less than 0.00001, the effect of improving strength is not expressed,
Sheets, films and molded products with excellent strength cannot be obtained.

The degree of polymerization of the styrene polymer (I) used in the present invention is in the range of 15 centipoise to 80 centipoise in terms of the viscosity of a 10 wt% toluene solution at 25 ° C. in consideration of the shape of the sheet, film, molded product, purpose of use and the like. And more preferably 20
It is set in the range of centipoise to 70 centipoise.

If the viscosity of the 10 wt% toluene solution is less than 15 centipoise, the strength is not improved even when the structural unit (C) of the present invention is introduced, and the molecular weight is difficult to adjust during production, which is not preferable. No excellent sheet and molded body can be obtained. On the other hand, when the viscosity exceeds 80 centipoise, the moldability and extrusion processability of the styrene-based resin are extremely lowered, and the productivity of the styrene-based polymer is deteriorated, which is not practical.

In the present invention, examples of the structural unit (A) include those having the following structures.

In the present invention, examples of the structural unit (B) include those having the structures shown below.

In the present invention, examples of the structural unit (C) include those having the following structures.

Alternatively, it may have two or more structural units of the above structural formula at random.

In the present invention, a block copolymer (II) having at least one or more vinyl aromatic hydrocarbon polymer blocks and at least one, and preferably two or more, conjugated diene-based copolymer blocks is provided. use. Here, the polymer block mainly composed of conjugated diene, the content of conjugated diene is 50 wt% or more, preferably 70 wt% or more,
A polymer block of 90% by weight or more is more preferable.
The vinyl aromatic hydrocarbon copolymerized in the polymer block containing a conjugated diene as the main component may be uniformly distributed in the polymer block or may be distributed in a taper shape. The weight ratio of vinyl aromatic hydrocarbon and conjugated diene in the block copolymer is 60:40 to 95: 5, preferably 75:25 to 9
It is 0:10. 60% by weight of vinyl aromatic hydrocarbon content
If it is less than the above range, the transparency is significantly lowered when mixed with the styrene-based polymer. On the other hand, if it exceeds 95% by weight, the strength of the styrene-based resin and the sheet, film, or molded product obtained by molding the styrene-based resin is significantly deteriorated, which is not preferable.

The weight of the vinyl aromatic hydrocarbon block of the block copolymer (II) is di-t-based on osmium tetroxide as a catalyst.
A method of oxidizing a copolymer with butyl hydroperoxide [eg, LMKOLTHOFF, et al., J. Polym. Sci. 14
29p (1946)]] or the like.

The block copolymer (II) used in the present invention is a linear block copolymer represented by the following general structural formula; (AB) _n ... A (BA) _n ... B (AB) ) _N (A is a vinyl aromatic hydrocarbon copolymer block,
B is a polymer block mainly composed of a conjugated diene. A
The boundaries between blocks and B blocks do not necessarily have to be clearly distinguished. ) Alternatively, it is a radial block copolymer represented by the following general formula.

_{[(B-A) n m +} 2 X ...... _{[(A-B) n m +} 2 X ...... _{[(B-A) n -B m} + 2 X ...... (A, B is the same as defined above And X represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride or a residue of an initiator such as a polyfunctional organolithium compound.) N in the general formulas 1 to 4 is, m is 1
Or 3.

In the block copolymer (II) used in the present invention,
The number average molecular weight of the vinyl aromatic hydrocarbon polymer block is
It is 10,000 to 70,000, preferably 15,000 to 60,000. The number average molecular weight of the polymer block mainly composed of the conjugated diene is not particularly limited, but is 500 to 200,000, preferably 1,000 to 100,000.

The block copolymer (II) used in the present invention can be basically produced by a conventionally known method, for example, Japanese Patent Publication No. 36-19286.
The methods described in JP-B No. 43-14979, JP-B-48-2423, JP-B-48-4106, JP-B-49-36957 and the like can be mentioned.

In the present invention, as the vinyl aromatic hydrocarbon, styrene, o-methylstyrene, p-methylstyrene, p
-T-methylstyrene, α-methylstyrene and the like can be used. You may use these individually or in mixture of 2 or more types. Particularly popular is styrene.

Further, the conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene,
2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-
Hexadiene or the like can be used. You may use these individually or in mixture of 2 or more types. Particularly common are 1,3-butadiene and isoprene.

In order to obtain the styrenic polymer (I) of the present invention, it is necessary to first carry out the first step of the polymerization step in the presence of a polymerization initiator composed of a specific low temperature decomposition type organic peroxide.

This low-temperature decomposition type organic peroxide has the general formula; (In the formula, l and n are integers of 1 to 20, m is an integer of 0 or 1 to 5, and R ₁ , R ₂ , R ₃ and R ₄ are each hydrogen or an alkyl group having 1 to 5 carbon atoms, It is a cyclohexyl group or a phenyl group) and has at least 3 repeating units, preferably 5 to 30 repeating units.

Examples of such an organic peroxide include those having the following repeating units.

A low temperature decomposition type organic peroxide in which two or more structural units having the above structure are randomly bonded can also be used. In the present invention, these organic peroxides having a repeating unit may be used alone or in combination of two or more.

These organic peroxides can be synthesized according to the methods described in JP-B-63-32089, JP-A-59-93725 and JP-A-59-176320.

The above-mentioned low temperature per 100 parts by weight of the monomer mixed solution in which the mixing ratio of the styrene monomer and the acrylic acid ester (methacrylic acid ester) monomer is 100/0 to 80/20 (mol% / mol%). Decomposition type organic peroxide 0.005 to 2.0 parts by weight is added,
Polymerize at temperatures below 110 ° C. At this stage, it is necessary to obtain 15% by weight or more, preferably 20% by weight or more of the styrene polymer finally obtained.
After that, it is mixed with a copolymer polymerization solution of a styrene monomer-acrylic acid ester (methacrylic acid ester) monomer polymerized by another reactor, and the composition ratio and the degree of polymerization of the target styrene resin are mixed. So that a styrene-based monomer and / or an acrylic acid ester (methacrylic acid ester) monomer are added as necessary, and polymerization is performed at an optimum polymerization temperature to obtain a styrene-based polymer. .

At this time, a polymerization solvent, for example, ethylbenzene, toluene, xylene or the like can be used. It is also possible to use an organic peroxide that is commonly used for the polymerization of styrene-based polymers together with the above-mentioned low temperature decomposable organic peroxide. Also, it can be added during the polymerization.

As the polymerization method, a bulk polymerization method or a solution polymerization method which is commonly used in the production method of a styrene-based polymer is used. Further, either a batch polymerization method or a continuous polymerization method can be used.

As the styrene monomer of the present invention, styrene, α-
Methylstyrene, p-methylstyrene, pt-butylstyrene and the like can be used. These styrene monomers can be used alone or in combination. As the acrylate (methacrylate) monomer, butyl acrylate, butyl methacrylate and the like can be used. These acrylate (methacrylate) monomers can be used alone or as a mixture.

At any stage before or after recovering the unreacted monomer and / or solvent, additives commonly used in styrene polymers, such as antioxidants, lubricants, plasticizers, colorants, antistatic agents, etc. Can be added.

In the present invention, the viscosity of a 10 wt% toluene solution, which is a measure of the degree of polymerization, is measured using an Ostwald-Cannon-Fenske viscous tube # 350 in a thermostat at 25 ° C.

The structural unit ratio (C) / [(A) + (B)] is measured by the following method.

After dissolving the styrene-based polymer in 10 times the amount of methyl ethyl ketone, the styrene-based polymer is precipitated while slowly adding the same amount of methanol. This styrene polymer is 200
Dry under reduced pressure of 5 mmHg for 30 minutes. Using the styrene-based polymer pretreated in this way, JASCO Corporation JNM
Measure ¹³ C using GX400 FT-NMR.

 The measurement and calculation are performed under the following measurement conditions.

( ¹³ C measurement) Pulse width = 9.3 μs; 45 ° pulse Data point = 32768 Repetition time = 2.0 seconds AD converter = 16 bits Accumulation count = 30,000 to 100,000 Sample concentration = 20 wt% Solvent = 1,1,2,2 , -Tetrachloroethane- (d2) Sample tube = 10mm Measuring temperature = 120 ° C The peak derived from the methylene group of the structural unit (C) is 29.4.
Appears in ppm. On the other hand, peaks derived from the carbons of the methine group and methylene group of the structural units (A) and (B) appear at 39 to 50 ppm. From the peak area ratio, the structural unit ratio (C) / [(A)
+ (B)].

The ratio of the structural units (A) and (B) is determined by the following method.

Prepare the sample using the same procedure as for ^13C measurement, and use the JNM-GX270 FT
¹ H is measured using NMR under the conditions described below.

( ¹ H measurement) Pulse width = 8.4μs Data point = 16384 Repetition time = 7.559 seconds AD converter = 16 bits Accumulation count = 1,000 Sample concentration = 10 wt% Solvent = 1,1,2,2-tetrachloroethane- (d2 ) Sample tube = 5 mm Measurement temperature = 120 ° C The peak derived from the phenyl group of the structural unit (A) is 6.2
Appears at ~ 7.4 ppm. A peak derived from hydrogen of the structural unit (B) appears at 3.4 to 3.8 ppm. The molar ratio of the structural units (A) and (B) is determined from the peak area ratio.

In order to separate the styrene-based polymer (I) and the block copolymer (II) from the styrene-based resin, the styrene-based resin is dissolved in methyl ethyl ketone, methanol is added, and the centrifugal separator is operated at 20,000 RPM for 30 minutes. After the treatment, the precipitate (block copolymer (II)) and the supernatant (styrene-based polymer (I)) are separated, and a large amount of methanol is added to the supernatant to precipitate the styrene-based polymer. 50 two precipitates
Dry in a vacuum dryer at 10 ° C and 10 mmHg. The sample thus obtained is used for the above-mentioned measurement.

The styrene resin of the present invention is obtained by blending the styrene polymer (I) and the block copolymer (II).

The weight ratio of the styrene polymer (I) to the block copolymer (II) is in the range of 99: 1 to 20 to 80. More preferably 9
It is from 5: 5 to 30:70. The weight ratio of the styrene polymer (I) is
When it exceeds 99, the reinforcing effect by the block copolymer (II) does not appear, and when the weight ratio of the styrene polymer (I) is less than 20, when the styrene resin is reworked and reused, the block copolymer (II The gel-like substance caused by II) deteriorates the quality of the styrene resin, which is not preferable. Moreover, the cost of the styrene resin is increased, which is not preferable.

The method of mixing the styrene polymer (I) and the block copolymer (II) is a known method, for example, mixing with an extruder, calender roll, Banban Lee mixer, or the like, or an injection molding machine for two polymers. It is possible to use a method in which it is supplied to a sheet extruder or a film extruder and melt-kneaded at the stage of molding a molded product.

The transparent styrenic resin composition of the present invention is a known method generally used for molding a thermoplastic resin, for example, a molded product using an injection molding machine, an extruder, a cast processing device,
Sheets and films can be obtained using a T-die processing device.

Further, after being formed into a film, a sheet or the like, it can be formed into a desired formed body. Further, an antistatic agent, a lubricant such as silicone, etc. may be applied to the surface in order to improve the surface characteristics of the obtained styrene resin molded product, particularly a film, a sheet and the like.

 The physical property test methods in the examples will be described below.

 Melt flow rate (MFR): According to ISO R1133.

 Vicat softening point (VICAT): According to ASTM D1525.

 Tensile strength: According to ASTM D638.

Impact strength: 5cm x 8.8cm x 2mm test piece is injection molded under the conditions of molding temperature = 240 ° C, molding pressure = SSP + 5kg / cm ² , mold temperature = 60 ° C, and a "fall weight type" manufactured by Toyo Seiki Using a graphic impact tester, a missile weighing 6.5 kg from a height of 20 cm is naturally dropped to determine the maximum load for destruction.

When seeking the impact strength of a sheet, 5 cm from the sheet
Take out a test piece of × 8.8 cm and measure with the same device and method as above.

Transparency: Mold the same test piece under the same molding conditions as the one-shot impact strength,
Determine visually.

(Examples) Examples of the present invention will be described below, but these do not limit the scope of the present invention.

<Production Method of Styrene Polymer (I)> Styrene Polymer-1,2,3 The styrene resin is polymerized by the apparatus shown in FIG. 1 attached.

The polymerization reactors -1, -1 'are complete mixing type reactors,
The volume is 30 each, and the volume of the reaction solution can be changed within the range of 5 to 25.

Polymerization reactors -2 and -2 'are tubular reactors with a built-in static mixer, and each has a capacity of 20.

In order to mix the polymerization solution and the polymerization initiator solution, a static mixer was installed at the inlet of the polymerization reactor-2 ', and its capacity was 1
Is. A gear pump is installed at the outlet of the polymerization reactor-1, 1'2 'and the recovery system.

Polymerization is carried out under the polymerization conditions shown in Table 1. Table 1 also shows the polymer concentration in the polymerization solution at the outlet of each reactor.

The polymerization vessel leaving the polymerization reactor-2 'is guided to a preheater. The preheater has a built-in static mixer and its capacity is 0.
8 After being heated to 240 ° C by a preheater, it is introduced to a recovery device kept at 240 ° C, devolatilized under a vacuum of 10 mmHg, and pelletized. The product is sampled 48 hours after the start of polymerization and the physical properties are evaluated. Table 2 shows the physical property evaluation results.

Styrene-based polymer-4 The styrene-based resin was polymerized by the apparatus shown in FIG. 2 attached. The polymerization reactor-1 is the same as the polymerization reactor-1 shown in FIG. The recovery device is also the same as in FIG.

91 parts by weight of styrene, 5.5 parts by weight of butyl acrylate,
A mixed solution of 2.98 parts by weight of ethylbenzene and 0.02 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane is supplied to the reactor-1 at a liquid volume of 3 / Hr. The residence time is 6 hours. Polymerize at a polymerization temperature of 135 ° C. The polymer concentration in the polymerization solution is 58% by weight. The operation is performed in the same manner as in Example 1, and the product is collected and the physical properties are measured. The physical property measurement results are shown in Table 2.

Styrene Polymer-5 A mixed solution of 97 parts by weight of styrene, 2.98 parts by weight of ethylbenzene, and 0.02 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane using the same apparatus as the styrene polymer-4. Is fed to Reactor-1 at a flow rate of 2.5 / Hr. Polymerization is carried out at a polymerization temperature of 105 ° C. for a residence time of 8 hours. The polymer concentration in the polymerization solution is 52% by weight. The operation is performed in the same manner as in Example 1, and the product is collected and the physical properties are measured. The results of measuring the physical properties are shown in Table 2.

(Production Method of Block Copolymer (II)) Block Copolymer-1,2,3 A styrene-butadiene block copolymer having a polymer structure, a styrene content, and a polystyrene block molecular weight as shown in Table 3 is prepared. Polymerize in n-hexane with n-butyllithium as the initiator.

(Examples 1 and 2 and Comparative Examples 1 and 2) Styrene-based polymers (I) and block copolymers (II) shown in Table 4 were melt-kneaded using a 25 mmφ single screw extruder, A styrene resin composition is obtained. The results of measuring the physical properties of this styrene resin composition are shown in Table 4.

(Examples 3 to 6 and Comparative Examples 3 to 6) The styrene polymer (I) and the block copolymer (II) shown in Table 5 were melt-kneaded using a 25 mmφ single screw extruder, A styrene resin composition is obtained. Using this styrene-based resin composition, a sheet having a thickness of 0.8 mm was prepared with a 30 mmφ extruder. The physical properties of this sheet are shown in Table 5.

(Examples 7 and 8 and Comparative Example 7) The styrene-based polymer (I) and the block copolymer (II) shown in Table 5 were melt-kneaded using a 25 mmφ single screw extruder to give a styrene-based resin. A resin composition is obtained. Using this styrene-based resin composition, a sheet having a thickness of 0.8 mm was prepared with a 30 mmφ extruder. This sheet was thermoformed using a hot plate pressure air forming machine.

The sheet is heated at a heating pressure of 1.0 kg / cm ² , and the molding pressure is 2.5 kg.
/ cm ² , molding time 2 seconds, mold temperature 60 ℃
The heating time at hot plate temperature 115 ° C, 120 ° C, and 125 ° C that the hinge 3R of the mold (feedback) can reproduce like the mold was calculated. The results are shown in Table 6.

(Example 9 and Comparative Examples 8 and 9) Using the styrene resin composition used in Example 5 and Comparative Example 5, injection was performed using a discharge type machine IS800B-75 (manufactured by Toshiba Machine Co., Ltd.). The tray shown in FIG. 3 was molded under the conditions of a pressure of 100 kg / cm ² and a mold temperature of 60 ° C. At this time, the minimum temperature at which the tray could be molded was determined by changing the injection temperature.

Next, drop 80 g of steel balls in the center of this tray,
The height at which cracks occurred was examined, and the breaking energy was determined.
The results are shown in Table 7.

(Effect of the Invention) In the present invention, a styrene-based structural unit consisting of a specific ratio and an acrylate ester (methacrylate ester)
Block copolymer having a styrenic polymer (I) consisting of a system structural unit and a structural unit having a long alkyl chain represented by a specific structural formula, an aromatic hydrocarbon polymer block, and a conjugated diene polymer block The styrene-based resin composition comprising (II) has excellent transparency and strength. The styrene-based resin composition of the present invention can be injection-molded at a low temperature, and the molded product is transparent and has excellent strength. In particular, the sheet formed by molding the styrene resin can be secondarily molded at a low temperature and is excellent in strength and transparency.

[Brief description of drawings]

1 and 2 are schematic explanatory views of a polymerization apparatus used in Examples of the present invention. FIG. 3 is a schematic view of a large tray formed in the example. 1, 1 ': Complete mixing reactor 2, 2': Tube reactor with built-in static mixer 3: Volatilization tank 4-1 to 2: Raw material solution feed pump 4-3: Polymerization initiator solution feed pump 4 −4: Additive solution feed pump 5, 5-1 to 4: Polymerization solution transfer pump 6: Molten resin transfer pump 7: Static mixer 8: Preheater (built-in static mixer) 9: Vacuum line 10: Melt Resin transfer line

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C08L 33/04 LJD C08L 33/04 LJD 53/02 LLX 53/02 LLX

Claims (1)

(57) [Claims] 1. General formula: (1) General formula (A); (In the formula, R ₁ is hydrogen or a methyl group, and R ₂ is hydrogen or an alkyl group having 1 to 5 carbon atoms) (B); (In the formula, R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or an alkyl group having 1 to 8 carbon atoms. However, when R ₁ is a methyl group, R ₂ has 2 to 8 carbon atoms. It is an alkyl group.) (C); (In the formula, l and n are integers of 1 to 20, m is an integer of 0 or 1 to 5, and R ₁ , R ₂ , R ₃ , and R ₄ are each hydrogen or 1 to 5 carbon atoms.
Is an alkyl group, a cyclohexyl group or a phenyl group. ), The structural unit (A), (B)
Is (A): 80-99.5mol% (B): 0.5-20mol% (however, (A) + (B) = 100mol%), and the structural unit ratio (C) / ((A) + (B)) = 0.01
To a vinyl aromatic hydrocarbon having at least one vinyl aromatic hydrocarbon polymer block and at least one conjugated diene-based polymer block. A resin composition comprising a block copolymer (II) having a weight ratio of styrene to a conjugated diene of 60:40 to 95: 5, the weight of the styrene polymer (I) and the block copolymer (II) A novel transparent styrene resin composition, characterized in that the ratio is 99: 1 to 20:80.