JP2001002870A - Styrenic polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having a small gel content and excellent in the balance of properties by compounding a styrene/n-butyl acrylate copolymer and a block copolymer in a specific weight ratio. SOLUTION: The composition comprises a styrene/n-butyl acrylate copolymer (A), a block copolymer (B) and 0.05-3 pts.wt., based on 100 pts.wt. of the total of the components A and B, of at least one stabilizer selected from acrylate- based, phenolic and other stabilizers, the component A/component B ratio by weight being 10/90 to 90/10. The component A comprises 80-89 wt.% of styrene and 11-20 wt.% of n-butyl acrylate and has a melt viscosity P (poise) in the range represented by equations I and II at 180-240 deg.C. The component B comprises at least two vinyl aromatic hydrocarbon polymer blocks whose weight ratio is 1.2-4.5 and at least one conjugated diene/vinyl aromatic hydrocarbon copolymer block and contains 65-85 wt.% of the vinyl aromatic hydrocarbon and 35-15 wt.% of the conjugated diene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a sheet and a film which has a small amount of gel (flash eyes) and a good balance of physical properties.

[0002]

2. Description of the Related Art A block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene having a relatively high content of a vinyl aromatic hydrocarbon is injection-molded by utilizing properties such as excellent transparency and impact resistance. It is used for applications such as extrusion molding of sheets and films. In particular, a composition comprising the block copolymer and a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid-based derivative copolymer, a composition for a film,
Due to their excellent transparency, mechanical properties and shrinkage, some further improvements have been proposed. For example, JP-A-59
JP-A-221348 discloses that the content of an aliphatic unsaturated carboxylic acid derivative is 5 to 80% by weight in order to obtain a composition having excellent mechanical properties, optical properties, stretching properties, crack resistance and the like.
In, a composition of a vinyl aromatic hydrocarbon having a Vicat softening point not exceeding 90 ° C.-a copolymer of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene with a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, JP-A-61-25819 discloses a method for obtaining a shrinkable film having excellent low-temperature shrinkage, optical properties, crack resistance, dimensional stability, etc., in which the vinyl aromatic hydrocarbon content is 95 to 20% by weight and the vicat softening is carried out. 9 points
A low-temperature shrinkable film obtained by stretching a composition of a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer not exceeding 0 ° C. and a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene block is formed. JP-A-5-104630 discloses that a Vicat softening point is 10 to obtain a transparent heat-shrinkable film having excellent stability over time and impact resistance.
It is composed of a composition of a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer not exceeding 5 ° C. and a copolymer of a vinyl aromatic hydrocarbon and a block of a conjugated diene, and has a specific heat shrink force. JP-A-6-220278 discloses a heat-shrinkable hard film having a specific structure and a molecular weight distribution in order to obtain a composition in which transparency, rigidity and low-temperature surface impact property are balanced. JP-A-7-216187 discloses a composition comprising a copolymer comprising an aromatic hydrocarbon and a conjugated diene block and a vinyl aromatic hydrocarbon- (meth) acrylate copolymer resin. In order to obtain a resin composition with excellent impact properties,
Transparent containing a block copolymer having a vinyl aromatic hydrocarbon block of a specific structure, a copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene, and a copolymer of a vinyl aromatic hydrocarbon and a (meth) acrylate ester Each of the high-strength resin compositions is described. However, a composition comprising a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene and a copolymer comprising a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative is required to form a relatively thin sheet or film. The gel level (fish eye) in the molded article at the time of manufacture and the balance of physical properties are not sufficient, and these documents do not disclose a method for improving them, and the problem is still pointed out in the market .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a styrenic copolymer composition having less gel (fish eye) in a sheet or film and having an excellent balance of physical properties. .

[0004]

SUMMARY OF THE INVENTION The present invention provides a storage elastic modulus of 30.degree. C. and a temperature at which it becomes 50%, and a temperature of 180 to 240.degree.
A composition of a specific styrene-n-butyl acrylate copolymer having a viscosity within a predetermined range and a vinyl aromatic hydrocarbon-conjugated diene block copolymer having a specific polymer structure, and further a specific By combining stabilizers, while maintaining an excellent balance of physical properties,
It has become possible to greatly reduce fish eyes (hereinafter referred to as FE).

That is, (I) the styrene content is 80 to 8
A styrene-n-butyl acrylate copolymer having 9% by weight and an n-butyl acrylate content of 11 to 20% by weight, and (II) at least two vinyl aromatic hydrocarbon polymer blocks and at least one conjugate. A block copolymer having a diene polymer block and at least one conjugated diene and a vinyl aromatic hydrocarbon copolymer block, or at least two vinyl aromatic hydrocarbon polymer blocks and at least one conjugated diene and a vinyl aromatic hydrocarbon block A block copolymer having a hydrogen copolymer block, wherein the vinyl aromatic hydrocarbon content of the block copolymer is 65 to 65.
85% by weight, the conjugated diene content is 35 to 15% by weight,
The content of the short-chain vinyl aromatic hydrocarbon polymerized portion in which the number of vinyl aromatic hydrocarbon units is 1 to 3 with respect to the total amount of the vinyl aromatic hydrocarbons constituting the block copolymer is 1 to 3.
25% by weight, the content of at least one vinyl aromatic hydrocarbon polymer block of the block copolymer is 20 to
50% by weight, wherein the weight ratio of at least two vinyl aromatic hydrocarbon polymer blocks of the block copolymer is 1.2 to
4.5 (I) and (I)
A styrene-based copolymer composition wherein the weight ratio of I) is 10/90 to 90/10, and styrene-acrylic acid n of (I)
The styrene-based copolymer composition according to (I), wherein the styrene content of the -butyl copolymer is 83 to 89% by weight and the n-butyl acrylate content is 11 to 17% by weight. 180 to 24 of butyl copolymer
A styrene-based copolymer composition having a viscosity at 0 ° C. in the range of not more than the value of the formula (1) and not less than the value of the formula (2),

(1) P = 2.91 × 10 ⁵ −2350 × T + 5 × T ² (2) P = 1.46 × 10 ⁵ −1119.2 × T + 2.256 × T ² (P: measurement temperature T ( ° C) (Pois
e)) The storage elastic modulus at 30 ° C. of the styrene-n-butyl acrylate copolymer (I) is 1.5 × 10 ^{9 to} 2.5 ×.
In the range of 10 ⁹ Pa, the storage elastic modulus at 30 ° C. of 50
%, The styrene-based copolymer composition according to any one of-, wherein the stabilizer is 2-t-amyl-6- [1- (3,5-di-t). -Amyl-2-hydroxyphenyl) ethyl] -4-t-amylphenyl acrylate is added in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the total of (I) and (II). And a styrenic copolymer composition described in (1).

Hereinafter, the present invention will be described in detail. The method for producing the styrene-n-butyl acrylate copolymer (I) used in the present invention is a known method for producing a styrene resin, for example, a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method. Etc. can be used. The styrene content in the styrene-n-butyl acrylate copolymer (I) used in the present invention is 80 to 89% by weight, preferably 83 to 89% by weight.
% By weight. If the styrene content is less than 80% by weight, the heat resistance is lowered, and when a sheet or film is formed, it is not preferable because it is fused at a low temperature. On the other hand, if the content exceeds 89% by weight, the transparency of the composition is undesirably reduced.

[0008] Styrene - a storage modulus at 30 ° C. acrylic acid n- butyl acrylate copolymer (I) is 1.5 × 10 ⁹ ~
2.5 × 10 ⁹ Pa, preferably 1.7 × 10 ⁹ to 2.
The range is 3 × 10 ⁹ Pa. If it is less than 1.5 × 10 ⁹ Pa, the rigidity decreases, and if it exceeds 2.5 × 10 ⁹ Pa, the elongation of the molded product decreases, which is not preferable. The temperature at which the storage elastic modulus reaches 50% of the storage elastic modulus at 30 ° C is in the range of 75 to 100 ° C, preferably 75 to 85 ° C. If the temperature is lower than 75 ° C., it is not preferable because the sheet and the film are easily fused at a low temperature. If the temperature exceeds 100 ° C., it is not preferable because the low-temperature shrinkage is inferior when used as a heat-shrinkable film.

The storage modulus of the styrene-n-butyl acrylate copolymer (I) is DMA983 (DUPON
T (manufactured by T Company) at a resonance frequency and a heating rate of 2 ° C./min. The viscosity at 180 to 240 ° C. of the styrene-n-butyl acrylate copolymer (I) used in the present invention is in the range of not more than the value of the formula (1) and not less than the value of the formula (2). If the viscosity exceeds the value of the formula (1), relatively small FE in the sheet or film increases, which is not preferable. If the viscosity is less than the value of the formula (2), a relatively large FE is generated, which is not preferable.

[0010] The viscosity of the styrene-n-butyl acrylate copolymer (I) is determined by Capillograph (Toyo Seiki Co., Ltd.)
(Manufactured by the company) and a share rate (SR) measured at 61 sec ⁻¹ . The measurement conditions of the capillary were such that the capillary length (L) was 10.0 mm, the capillary diameter (D) was 1.00 mm, and the barrel diameter (B) was 9.50 mm.
And is measured in a temperature range of 180 to 240 ° C. The styrene-n-butyl acrylate copolymer (I) used in the present invention has a storage elastic modulus of 30 ° C., a temperature at which it becomes 50%, and a viscosity of 180 to 240 ° C., which contain styrene and n-butyl acrylate. Amount, styrene-acrylic acid n-
It can be controlled by adjusting the amount of the molecular weight modifier of the butyl copolymer, the residence time in the polymerization vessel, the polymerization temperature, and the like.

Further, a preferred melt flow rate of styrene-n-butyl acrylate copolymer (I) (hereinafter referred to as MF)
(Referred to as R) [measured under G conditions (temperature: 200 ° C., load: 5 kg) according to JIS K-6870] in terms of molding processing, 0.1 to 20 g / 10 min, preferably 1 to 10 g.
/ 10 min. The block copolymer (II) used in the present invention is obtained by polymerizing vinyl aromatic hydrocarbon and conjugated diene in an organic solvent using an organic lithium compound as an initiator.

The vinyl aromatic hydrocarbon used in the block copolymer (II) includes styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, and α-methylstyrene. , Vinyl naphthalene, vinyl anthracene, 1,1-
There are diphenylethylene and the like, and particularly common one is styrene. These may be used alone or in combination of two or more. As the conjugated diene, 1
Diolefin having a pair of conjugated double bonds, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene , 1,3-hexadiene and the like, and particularly common ones include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

The vinyl aromatic hydrocarbon content of the block copolymer (II) is 65 to 85% by weight, preferably 70 to 85% by weight.
80% by weight, the conjugated diene content is 35 to 15% by weight, preferably 30 to 20% by weight. When the content of the vinyl aromatic hydrocarbon is less than 65% by weight and the content of the conjugated diene exceeds 35% by weight, the FE in the sheet or film increases,
Conversely, the vinyl aromatic hydrocarbon content exceeds 85% by weight,
If the content of the conjugated diene is less than 15% by weight, the elongation of the sheet is undesirably reduced. Block copolymer (I
The content of the short-chain vinyl aromatic hydrocarbon polymerized portion in which the number of vinyl aromatic hydrocarbon units is 1 to 3 with respect to the total amount of the vinyl aromatic hydrocarbon constituting I) is 1 to 25% by weight. Short chain vinyl hydrocarbon polymerized portion content is 1% by weight
If it is less than 1, the elongation of the sheet decreases, which is not preferable. On the other hand, if it exceeds 25% by weight, the deformation of the sheet or film during heating becomes large, and the dimensional stability is poor, which is not preferable.

The content of the short-chain vinyl aromatic hydrocarbon is as follows:
After dissolving the block copolymer in dichloromethane and oxidatively decomposing with ozone (O ₃ ), the obtained ozonide is obtained by reducing with lithium aluminum hydride in diethyl ether and hydrolyzing with pure water. The obtained vinyl aromatic hydrocarbon component can be quantified by performing gel permeation chromatography (GPC) measurement and calculating the area ratio of the obtained peaks.

The content of the short-chain vinyl aromatic hydrocarbon portion is determined by the weight of the vinyl aromatic hydrocarbon and the conjugated diene in the process of copolymerizing the vinyl aromatic hydrocarbon and the conjugated diene during the production of the block copolymer, It can be controlled by changing the weight ratio, the polymerization reactivity ratio, and the like. As a specific method, a mixture of a vinyl aromatic hydrocarbon and a conjugated diene is continuously supplied to a polymerization system to carry out polymerization, and / or a polar compound or a randomizing agent is used to polymerize the vinyl aromatic hydrocarbon. A method such as copolymerizing a conjugated diene can be employed. Examples of polar compounds and randomizing agents include tetrahydrofuran, diethylene glycol dimethyl ether, ethers such as diethylene glycol dibutyl ether, amines such as triethylamine, tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium salts. Alkoxide and the like.

The content of at least one vinyl aromatic hydrocarbon polymer block of the block copolymer (II) of the present invention is 20 to 50% by weight, preferably 25 to 40% by weight.
It is. If the content of all the vinyl aromatic hydrocarbon polymer blocks is less than 20% by weight, it is not preferable because the film easily fuses at a low temperature when formed into a film. If there are only less than 20% by weight of blocks and more than 50% by weight of blocks, the transparency is undesirably reduced. The content of at least one vinyl aromatic hydrocarbon polymer block of the block copolymer (II) of the present invention is 20 to 5
"0% by weight" means that at least one or more of the weight ratios (%) of one or more vinyl aromatic hydrocarbon polymer blocks constituting the block copolymer to the block copolymer is at least one. It means 20 to 50% by weight.

At least 2 of the block copolymer (II)
The weight ratio of two vinyl aromatic hydrocarbon blocks is 1.2 to
It is 4.5, preferably 1.5 to 4.0. If the weight ratio is less than 1.2, the impact resistance is undesirably reduced.
On the other hand, if it exceeds 4.5, the transparency of the sheet is undesirably reduced. The block copolymer (II) has at least 2
One vinyl aromatic hydrocarbon polymer block and at least one conjugated diene polymer block and a conjugated diene and a vinyl aromatic hydrocarbon copolymer block or at least two vinyl aromatic hydrocarbon polymer blocks and at least one conjugated diene The block copolymer having a vinyl aromatic hydrocarbon copolymer block includes, for example, those having the following general formula.

(A) A- (BA) _n (b) A- (BA) _n -B (c) linear block copolymer represented by B- (AB) _{n + 1} Or (d) [(AB) _k ] _{m + 2-} X (e) [(AB) _k- A] _{m + 2-} X (f) [(BA) _k ] _{m + 2-} X (g) [(BA) _k -B] radial block copolymer represented by _{m + 2-} X (in the above formula,
A represents a vinyl aromatic hydrocarbon polymer polymer block. B represents a conjugated diene polymer block, a conjugated diene and a vinyl aromatic hydrocarbon copolymer block, or a block in which a conjugated diene polymer, a conjugated diene and a vinyl aromatic hydrocarbon copolymer are adjacent. X represents a residue of a coupling agent or a residue of an initiator such as a polyfunctional organolithium compound. n, k and m are integers of 1 or more, generally 1 to
5 ).

Preferred MF of block copolymer (II)
R (at a temperature of 200 ° C. and a load of 5 kg under the G condition) is 0.1 to 50 g / 10 min, preferably 1 to 2 from the viewpoint of molding.
0 g / 10 min. In the composition of the present invention, the blending ratio of the styrene-n-butyl acrylate copolymer (I) and the block copolymer (II) is 10/90 by weight.
９０90/10, preferably 20/80 to 80/20. If the styrene-n-butyl acrylate copolymer (I) exceeds 90% by weight, the impact resistance of the composition decreases, and
If the amount is less than% by weight, the rigidity is undesirably reduced.

The composition of the present invention contains 2-t- as a stabilizer.
Amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] -4-t-amylphenyl acrylate was added in an amount of 0 based on 100 parts by weight of the total of (I) and (II). 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight
By adding the parts by weight, a further FE suppressing effect can be obtained. When the amount of the stabilizer is less than 0.05 part by weight, there is no effect of suppressing FE, and when added in an amount exceeding 3 parts by weight, it does not contribute to the FE suppressing effect more than the present invention. The styrene resin composition of the present invention contains n-octadecyl 3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate, 2,4-bis [(octylthio) methyl] -o
-Cresol, tetrakis [methylene-3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-
Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 2,4-bis- (n-octylthio)
At least one phenolic stabilizer such as -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine is added to 100 parts by weight of the total of (I) and (II). 0.05 to 3 parts by weight of tris- (nonylphenyl) phosphite, 2,2-methylenebis (4,
6-di-t-butylphenyl) octyl phosphite,
2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -N, N -Bis [2-[[2,4,8,10-tetrakis (1,1-
Dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -ethyl] -ethanamine, tris (2,4-di-t-butylphenyl) phosphite and the like At least one of organic phosphate and organic phosphite-based stabilizers can be added in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the total of (I) and (II).

The composition of the present invention can be produced by any conventionally known compounding method. For example, an open roll, an intensive mixer, an internal mixer, a kneader, a continuous kneader equipped with a twin-screw rotor, a melt kneading method using a general kneader such as an extruder, etc. And the like are used.

Various additives can be added to the composition of the present invention, if necessary, within a range that does not deteriorate FE and does not impair the balance of physical properties such as transparency, rigidity and impact resistance. These additives include a block copolymer elastomer of a vinyl aromatic hydrocarbon having a vinyl aromatic hydrocarbon content of 50% by weight or less and a conjugated diene, a rubber-modified styrene-based polymer, a non-rubber-modified styrene-based polymer, In addition to polyethylene terephthalate, etc., additives generally used in the compounding of plastics, for example, inorganic reinforcing agents such as glass fiber, glass beads, silica, charcoal, and talc; organic fibers; organic reinforcing such as coumarone indene resin; Agents, organic peroxides, crosslinking agents such as inorganic peroxides, titanium white,
Pigments such as carbon black and iron oxide, dyes, flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers,
Other extenders or mixtures thereof are mentioned.

The composition of the present invention may be used as it is or after being colored and molded by the same processing means as ordinary thermoplastic resins, and may be used for various purposes. For example, it can be used for containers such as OA equipment parts, daily necessities, food, miscellaneous goods, light electric parts and the like by injection molding, blow molding and the like. Especially F
Utilizing the feature of low E, it is suitable for thin films such as laminating films.

[0024]

EXAMPLES Examples of the present invention will be described below, but they do not limit the scope of the present invention. Table 1 shows styrene-n-butyl acrylate copolymers used in Examples and Comparative Examples. The copolymers of A-1 to A-4 were prepared by adding 5 kg of styrene and n-butyl acrylate in a ratio shown in Table 1 to a 10 L autoclave with a stirrer, and simultaneously adjusting the MFR to 0.3 kg of ethylbenzene. 1,
After charging a predetermined amount of 1-bis (t-butylperoxy) cyclohexane and polymerizing at 110 to 150 ° C. for 2 to 10 hours, unreacted styrene, n-butyl acrylate,
Ethylbenzene was recovered and obtained. The amount of 1,1 bis (t-butylperoxy) cyclohexane, the polymerization temperature, the polymerization residence time and the number of stirrings are shown in Table 1 at a storage elastic modulus of 30 ° C.
% And a viscosity of 180 to 240 ° C. The MFR of the obtained copolymer was JISK-6.
Based on G.870, the measurement was performed under the G condition at a temperature of 200 ° C. and a load of 5 kg.

The storage elastic modulus of the copolymer shown in Table 1 is D
Using MA983 (manufactured by DUPONT), the frequency is the resonance frequency, the heating rate is 2 ° C./min, a compression molded product having a thickness of about 3 mm and a width of about 12 mm is attached to an arm having a span of about 15 mm, and an amplitude of 0.2 mm. It was measured. The viscosity (Po
The measurement conditions for the ise) were as follows: Capillograph (manufactured by Toyo Seiki Co., Ltd.), and the shear (SR) was 61 sec ^-1.
Is the value of The measurement conditions of the capillary were such that the capillary length (L) was 10.0 mm, the capillary diameter (D) was 1.00 mm, the barrel diameter (B) was 9.50 mm, and 18
It was measured every 10 ° C. in the range of 0 to 240 ° C.

Table 2 shows the block copolymers used in the examples and comparative examples. The block copolymer was polymerized in cyclohexane solvent using n-butyllithium as an initiator and adding the monomers in the order and amount described in the polymer structure column in Table 2. After completion of the polymerization, methanol was added to stop the polymerization reaction, and then the amount of the stabilizer shown in Table 3 was added.
The solvent was distilled off to recover a block copolymer. The MFRs of the obtained block copolymers were all in the range of 5 to 10.

The content of the short-chain styrene polymerized portion in the block copolymer is determined by adding 150% oxygen / ozone (O ₃ ) at a concentration of 1.5% to a dichloromethane solution of the block copolymer.
The resulting ozonide is reduced by dropping in diethyl ether mixed with lithium aluminum hydride, and then reduced, pure water is dropped and hydrolyzed, and potassium carbonate is added and salted out. GPC measurement of the vinyl aromatic hydrocarbon component obtained by performing the filtration was performed, and the area ratio of the obtained peak was calculated. The ozone generator used was OT-31R-2 manufactured by Nippon Ozone Co., Ltd., GPC measurement was performed using chloroform as a solvent, and the column was arranged in the flow direction by Shimpack HSG-4 manufactured by Shimadzu Corporation.
0H, shimpack GPC-802, shimpa
It measured using ckGPC-801.

(Examples 1 to 6 and Comparative Examples 1 to 5) According to the composition shown in Table 3, a sheet having a thickness of 0.25 mm was formed at an extrusion temperature of 200 ° C. using a 40 mm sheet extruder. The elongation at break, the haze, the shrinkage at 80 ° C. (a measure of low-temperature shrinkage), the natural shrinkage, and the hot water fusion property (a measure of the low-temperature fusion property) were measured by the following methods. Further, a sheet having a thickness of 0.6 mm was formed under the same conditions, and the surface impact strength was measured by the following method. Further, FE was measured by the following method. Table 3 shows the performance of the obtained sheet.

(1) Tensile modulus and elongation at break: Measured at a tensile speed of 5 mm / min in the sheet extrusion direction and the direction perpendicular thereto. The test piece had a width of 12.7 mm and a distance between the marked lines of 50 mm. (2) Surface impact strength: Measured at 23 ° C. in accordance with ASTM D-1709 except that the weight was changed to a radius of 1/2 inch, and a 50% breaking value was obtained. (3) Haze: Liquid paraffin was applied to the sheet surface and measured according to ASTM D1003. (4) Shrinkage at 80 ° C .: A stretched film having a thickness of about 60 μm obtained by uniaxially stretching a sheet having a thickness of 0.25 mm five times in a direction perpendicular to the extrusion direction with a tenter stretching machine, and placing the film in hot water at 80 ° C. It was immersed for 5 minutes and calculated by the following equation. Heat shrinkage (%)
= (L-L1) / L × 100, L: length before shrinkage, L
1: Length after shrinkage.

(5) Natural shrinkage: 80 ° C. shrinkage of 40%
Was allowed to stand at 35 ° C. for 5 days and calculated by the following equation. Natural shrinkage (%) = (L2−L3) / L2 × 1
00, L2: length before standing, L3: length after standing. (6) Hot water fusion property: The stretched film was wound around a glass bottle having a diameter of about 8 cm, left in a stack of three bales in 85 ° C. warm water for 5 minutes, and the fusion state of the film was visually judged. The criterion is that ◎ indicates that no fusion has occurred, ○ indicates that fusion has occurred slightly, but will be separated immediately, and X indicates that fusion will not occur immediately. (7) FE: Extrusion temperature 2 using 40 mm sheet extruder
A sheet having a thickness of 0.3 mm is continuously formed at 35 ° C. for 6 hours, and a sheet area of 300 c after 5 minutes and 6 hours from the start of operation.
The difference in the number of FEs of 0.5 mm or more per m ² was counted and evaluated (（: difference is less than 50, Δ: difference is 50 to 1)
00, ×: difference exceeds 100).

(Comparative Example 7) The storage elastic modulus at 30 ° C. was 2.3 × 10 ⁹ Pa, and the storage elastic modulus at 30 ° C. was 50.
% Is 104 ° C and styrene content is 96% by weight
Of styrene-n-butyl acrylate copolymer of 50% by weight and 50% by weight of B-1 in Table 2 were molded in the same manner as in Example 1, and the blending characteristics were examined. As a result, the 80 ° C. shrinkage was an extremely low value of 15%.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

The sheets and films using the styrenic copolymer composition of the present invention have low FE, excellent transparency, excellent tensile modulus and elongation at break, and have low FE even as a heat-shrinkable film. In addition, the low-temperature shrinkability is good. By taking advantage of such a low FE feature, an extruded product such as a thin sheet or film can be suitably used as a wrapping film, or as a laminated film for a foam container or the like, or as a heat-shrinkable film.

[Brief description of the drawings]

FIG. 1 illustrates the values of the formulas (1) and (2) for the viscosity of a styrene-n-butyl acrylate copolymer used in the present invention in the range of 180 to 240 ° C.

Claims (5)

[Claims] (I) a styrene-n-butyl acrylate copolymer having a styrene content of 80 to 89% by weight and an n-butyl acrylate content of 11 to 20% by weight;
(II) a block copolymer having at least two vinyl aromatic hydrocarbon polymer blocks, at least one conjugated diene polymer block, at least one conjugated diene and a vinyl aromatic hydrocarbon copolymer block, or at least two A block copolymer having a vinyl aromatic hydrocarbon polymer block, at least one conjugated diene and a vinyl aromatic hydrocarbon copolymer block, wherein the block copolymer has a vinyl aromatic hydrocarbon content of 65% by weight.
And the conjugated diene content is 35 to 15% by weight, and the number of the vinyl aromatic hydrocarbon units is 1 to the total amount of the vinyl aromatic hydrocarbons constituting the block copolymer.
3, the content of the short-chain vinyl aromatic hydrocarbon polymerized portion in the range of 1 to 25% by weight, the content of at least one vinyl aromatic hydrocarbon polymer block of the block copolymer is 20 to 50% by weight, At least two of the block copolymers
Consisting of a block copolymer in which the weight ratio of the two vinyl aromatic hydrocarbon polymer blocks is 1.2 to 4.5,
A styrenic copolymer composition wherein the weight ratio of (I) and (II) is 10/90 to 90/10. 2. The styrene-n-butyl acrylate copolymer (I) according to claim 1, wherein the styrene content is 83 to 89% by weight and the n-butyl acrylate content is 11 to 17% by weight. Styrene-based copolymer composition. 3. The viscosity of the styrene-n-butyl acrylate copolymer (I) at 180 to 240 ° C. is within the range of not more than the value of the formula (1) and not less than the value of the formula (2). The styrenic copolymer composition according to claim 1 or 2, wherein (1) P = 2.91 × 10 ⁵ −2350 × T + 5 × T ² (2) P = 1.46 × 10 ⁵ −1119.2 × T + 2.256 × T ² (P: at the measurement temperature T (° C.) Melt viscosity (Pois
e)) 4. The storage elastic modulus at 30 ° C. of the styrene-n-butyl acrylate copolymer (I) is 1.5 × 10
⁹ in a range of to 2.5 × 10 ⁹ Pa, styrenic copolymer according to any temperature at which 50% of the storage modulus at 30 ° C. is of claims 1 to 3 in the range of 75 to 100 ° C. Composition. 5. As a stabilizer, 2-t-amyl-6- [1
-(3,5-Di-t-amyl-2-hydroxyphenyl) ethyl] -4-t-amylphenyl acrylate was added in an amount of 0.1 to 100 parts by weight of the total of (I) and (II).
The styrenic copolymer composition according to any one of claims 1 to 4, which is added in an amount of from 0.5 to 3 parts by weight.