JPH11228783A - Block copolymer composition and heat-shrinkable film therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition excellent in transparency, stiffness and impact resistance and also excellent in blocking resistance and printing property by blending specific amounts of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, a vinyl aromatic hydrocarbon-based polymer, an aliphatic monoamide and an aliphatic bisamide. SOLUTION: (A) A block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene in an amount of 20-100 pts.wt., 0-80 pts.wt. of (B) vinyl aromatic hydrocarbon-based polymer, 0.01-0.2 pt.wt. of (C) an aliphatic monoamide, based on 100 pts.wt. of the sum of components A and B, and 0.01-0.3 pts.wt. of (D) an aliphatic bisamide, based on 100 pts.wt. of the sum of components A and B, are blended, A block copolymer containing a vinyl aromatic hydrocarbon and a conjugated diene in a weight ratio of 60-90:40-10 and having a number average molecular weight of 40,000-500,000 is used as the component A. Vinyl aromatic hydrocarbon polymers, vinyl aromatic hydrocarbon/(meth)acrylic acid (ester) copolymers or rubber-modified styrene-based polymers are used as the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition containing a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene having excellent transparency, rigidity, impact resistance, blocking resistance and printability. And a heat-shrinkable film obtained by stretch-molding the same.

[0002]

2. Description of the Related Art When a vinyl aromatic hydrocarbon and a conjugated diene are subjected to block copolymerization in an organic solvent using alkyl lithium as an initiator by living anionic polymerization, the weight ratio of the vinyl aromatic hydrocarbon and the conjugated diene or the method of addition is determined. It is known that the structure of the copolymer can be diversified by a method such as changing, and block copolymers having various physical properties can be obtained. A block copolymer is generally a polymer having excellent impact resistance and transparency. When the content of the conjugated diene in the block copolymer is large, the block copolymer becomes a thermoplastic elastomer. When the content of is increased, it exhibits properties as a thermoplastic plastic. Various production methods utilizing these excellent characteristics are disclosed in JP-B-36-19.
No. 286, Japanese Patent Publication No. 48-4106, and the like. Further, in addition to these excellent properties, they have excellent compatibility with various kinds of vinyl aromatic hydrocarbon polymers, so that they are used for reinforcement.
No. 388, JP-B-47-43618, JP-B-51-27701, and the like.

[0003]

These copolymers and copolymer compositions are processed into containers, films, sheets and the like by injection molding or extrusion molding, and are used after being printed as necessary. However, since it contains a conjugated diene component, there is a problem that the adhesiveness is high and blocking between molded articles is likely to occur. In order to solve this problem, JP-A-52-130885 discloses a method of adding silica gel and JP-A-1-304146 discloses a method of adding a hydrocarbon wax. Although the printability is improved, there is a disadvantage that the printability is poor. In particular, when a heat-shrinkable film is printed and used as a label for covering a PET bottle or the like, it is necessary to satisfy both physical properties of blocking resistance and printability, and a heat-shrinkable film satisfying both of these properties is required. The development of was desired.

[0004]

[Means for Solving the Problems] Under these circumstances,
The present inventors have conducted intensive studies, as a result of adding a specific amount of a fatty acid monoamide and a fatty acid bisamide to a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene or a copolymer composition containing the same, transparency,
The present inventors have found that a block copolymer composition having excellent rigidity and impact resistance, and also excellent in blocking resistance and printability and a heat-shrinkable film thereof can be obtained, and have completed the present invention.

That is, the present invention provides the following (a), (b),
The present invention relates to a block copolymer composition comprising (c) and (d) and a heat-shrinkable film thereof. (A) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 6
0 to 90:40 to 10, and the number average molecular weight is 4
20 to 100 parts by weight of a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon having a molecular weight of 000 to 500,000, and (b) at least one vinyl aromatic selected from the following (i) to (iv): 0 to 80 parts by weight of an aromatic hydrocarbon polymer, (i) a vinyl aromatic hydrocarbon polymer, (ii) a copolymer of a vinyl aromatic hydrocarbon and (meth) acrylic acid, and (iii) a vinyl aromatic hydrocarbon. (Iv) rubber-modified styrene-based polymer (provided that (i)
In i) and (iii), the weight ratio of the vinyl aromatic hydrocarbon to the comonomer copolymerized with the vinyl aromatic hydrocarbon is from 5 to 99:95 to 1. (C) Fatty acid monoamide is the sum of (a) and (b) 100
0.01 to 0.2 parts by weight per part by weight, (d) The fatty acid bisamide is the sum of (a) and (b) 100
0.01 to 0.3 parts by weight per part by weight.

Preferably, the structure of the block copolymer (a) is a block copolymer represented by at least one selected from the following formulas (a) to (e): It relates to a combined composition. (B) A- (B) n (b) AC- (B) n (c) A- (CB) m (d) A- (CB) m- (B) n (e) A- (CA) n (where A is a polymer chain of a vinyl aromatic hydrocarbon,
B is a copolymer chain of a vinyl aromatic hydrocarbon and a conjugated diene;
Represents a polymer chain of a conjugated diene. M is an integer of 2 or more;
n shows the integer of 1 or more. )

Further, the present invention relates to a heat-shrinkable film obtained by stretching the above block copolymer composition.

Hereinafter, the present invention will be described in detail. The vinyl aromatic hydrocarbon used in the production of the block copolymer (a) of the vinyl aromatic hydrocarbon and the conjugated diene used in the present invention includes styrene, o-methylstyrene, p-
Methylstyrene, p-tert-butylstyrene, 2,
4-dimethylstyrene, 2,5-dimethylstyrene, α
-Methylstyrene, vinylnaphthalene, vinylanthracene and the like, and particularly common one is styrene.

The conjugated diene used in the production of the block copolymer (a) used in the present invention is 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 are 1,3-butadiene and isoprene.

The weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is from 60 to 90:40 to 10, preferably from 70 to 85:30 to 15. When the weight ratio of the vinyl aromatic hydrocarbon is less than 60%, the transparency and rigidity of the block copolymer exceed 90%.

The number average molecular weight of the block copolymer (a) used in the present invention is from 40,000 to 500,000,
Particularly preferably, it is 80,000 to 300,000.
If it is less than 40,000, sufficient rigidity and impact resistance of the block copolymer composition cannot be obtained, and if it exceeds 500,000, workability is undesirably reduced. The number average molecular weight of the block copolymer in the present invention is determined by gel permeation chromatography (hereinafter referred to as GPC).
).

The block ratio of the vinyl aromatic hydrocarbon in the block copolymer (a) is not particularly limited, but is preferably 70 to 100% by weight, particularly preferably 75 to 100% by weight. If the block ratio is less than 70% by weight, transparency and rigidity are undesirably reduced. The block ratio of the vinyl aromatic hydrocarbon was determined by the following equation. Block rate (%) = (W1 / W0) × 100,
Here, W1 represents the weight of the block polymer chain of the vinyl aromatic hydrocarbon in the block copolymer, and W0 represents the total weight of the vinyl aromatic hydrocarbon in the block copolymer. In the above formula, W1 represents a block copolymer as described in a known document "Rubber Chemistry and Technology (Y. TANAKA,
et. al. , RUBBERCHEMISTRY AN
D TECHNOLOGY,) ", 58 , p. 16 (198
5) Ozonization by the method described in 5), and the obtained vinyl aromatic hydrocarbon polymer component was subjected to GPC measurement to determine the molecular weight corresponding to each peak of the chromatogram using a standard polystyrene and a styrene oligomer. From
Those having a number average molecular weight exceeding 3,000 were quantitatively determined from the peak area. An ultraviolet spectroscopic detector whose wavelength was set to 254 nm was used as a detector.

The structure of the block copolymer (a) is preferably represented by at least one selected from the following formulas (a) to (e). (B) A- (B) n (b) AC- (B) n (c) A- (CB) m (d) A- (CB) m- (B) n (e) A- (CA) n (where A is a polymer chain of a vinyl aromatic hydrocarbon,
B is a copolymer chain of a vinyl aromatic hydrocarbon and a conjugated diene;
Represents a polymer chain of a conjugated diene. M is an integer of 2 or more;
n shows the integer of 1 or more. )

In the above general formula, A represents a polymer chain of a vinyl aromatic hydrocarbon, that is, a block polymer chain of a vinyl aromatic hydrocarbon, and is obtained by polymerizing one or more vinyl aromatic hydrocarbons. be introduced. When a plurality of A's are present in the general formula, their molecular weights may be the same or different. The composition of the polymerized chain of A, for example, the monomer type of vinyl aromatic hydrocarbon and the arrangement state of the monomer type may be the same or different.

In the above formula, B represents a copolymer chain of a vinyl aromatic hydrocarbon and a conjugated diene. When a plurality of Bs are present in the general formula, their molecular weights may be the same or different. Further, the composition of the copolymer chain of B, for example, monomer species of vinyl aromatic hydrocarbon or monomer species of conjugated diene,
Alternatively, the arrangement of the monomer species may be the same or different. B is introduced by copolymerizing the vinyl aromatic hydrocarbon and the conjugated diene. At this time, the molecular weight and composition of the copolymer chain of B are controlled mainly by the amount and method of addition of the monomer under certain polymerization conditions. The copolymer chain of B may be in an arrangement state in which the distribution density is gradient between the aromatic hydrocarbon and the conjugated diene.

In the above general formula, C represents a polymer chain of a conjugated diene, that is, a block polymer chain of a conjugated diene, and is introduced by polymerizing one or more of the above conjugated dienes. When a plurality of Cs are present in the general formula, their molecular weights may be the same or different. Further, the composition of the polymer chain of the conjugated diene, for example, the monomer species of the conjugated diene and the arrangement state of the monomer species may be the same or different.

Next, the production of the block copolymer (a) of the present invention will be described. The block copolymer (a) can be produced by polymerizing monomers of a vinyl aromatic hydrocarbon and a conjugated diene in an organic solvent using an organic lithium compound as an initiator. Examples of the organic solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; or benzene and toluene. And aromatic hydrocarbons such as ethylbenzene and xylene.

The organic lithium compound is a compound in which one or more lithium atoms are bonded in a molecule, for example, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium,
Monofunctional organic lithium compounds such as tert-butyl lithium, and polyfunctional organic lithium compounds such as hexamethylene dilithium, butadienyl dilithium, and isoprenyl dilithium can be used.

As the vinyl aromatic hydrocarbon and the conjugated diene used in the present invention, those described above can be used, and one or two or more of them can be used for polymerization. In the living anionic polymerization using the above-mentioned organolithium compound as an initiator, almost all of the vinyl aromatic hydrocarbon and the conjugated diene subjected to the polymerization reaction are converted into a polymer.

In the present invention, the molecular weight of the block copolymer (a) can be controlled by the amount of the initiator relative to the total amount of the monomers.

The block ratio of the vinyl aromatic hydrocarbon in the block copolymer (a) can be controlled by the amount of the randomizing agent added when the vinyl aromatic hydrocarbon and the conjugated diene are copolymerized. Tetrahydrofuran (THF) is mainly used as a randomizing agent, but other ethers, amines, thioethers, phosphoramides, alkylbenzene sulfonates, potassium or sodium alkoxides, and the like can also be used.

Suitable ethers include, besides THF, dimethyl ether, diethyl ether, diphenyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether and the like. As amines, tertiary amines, for example, trimethylamine,
In addition to triethylamine and tetramethylethylenediamine, cyclic amines and the like can also be used. In addition, triphenylphosphine, hexamethylphosphoramide, potassium or sodium alkyl benzene sulfonate, potassium or sodium butoxide and the like can also be used as a randomizing agent.

The amount of the randomizing agent to be added is preferably 0.001 to 10 parts by weight based on 100 parts by weight of the total charged monomers. The timing of addition may be before the start of the polymerization reaction or before the polymerization of the copolymer chain -B-. Further, they can be added as needed.

In addition, the block ratio can also be increased by mechanically continuously feeding the vinyl aromatic hydrocarbon and the conjugated diene to the polymerization vessel, or by alternately adding the vinyl aromatic hydrocarbon and the conjugated diene to the polymerization vessel little by little. Can control.

The block copolymer thus obtained can be treated with a polymerization terminator such as water, alcohol and carbon dioxide.
It is inactivated by adding an amount sufficient to inactivate the active end. As a method of recovering the copolymer from the obtained block copolymer solution, a method of precipitating with a poor solvent such as methanol, a method of evaporating the solvent with a heating roll or the like (drum drying method), a method of concentrating with a concentrator Any method such as a method of removing the solvent with a vented extruder after concentrating the solution, a method of dispersing the solution in water, blowing steam and removing the solvent by heating to recover the copolymer (steam stripping method), etc. The method can be adopted.

The polymer (b) used in the present invention is:
(I) a vinyl aromatic hydrocarbon polymer, (ii) a copolymer comprising a vinyl aromatic hydrocarbon and (meth) acrylic acid,
It is at least one polymer selected from (iii) a copolymer comprising a vinyl aromatic hydrocarbon and a (meth) acrylate and (iv) a rubber-modified styrene polymer.

As the vinyl aromatic hydrocarbon polymer (i), a homopolymer or a copolymer of two or more vinyl aromatic hydrocarbons described above is used. Particularly common is polystyrene.

The copolymer (ii) comprising a vinyl aromatic hydrocarbon and (meth) acrylic acid can be obtained by polymerizing the vinyl aromatic hydrocarbon and (meth) acrylic acid. One or two or more of each monomer can be selected and used.

Examples of the (meth) acrylic acid include acrylic acid and methacrylic acid.

The copolymer (iii) comprising a vinyl aromatic hydrocarbon and a (meth) acrylate is obtained by polymerizing the vinyl aromatic hydrocarbon and the (meth) acrylate. Can be used by selecting one or more of each monomer.

Examples of the (meth) acrylate include methyl acrylate, ethyl acrylate, and acrylic acid-n-
Butyl, isobutyl acrylate, hexyl acrylate,
Examples thereof include (2-ethyl) hexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and (2-hydroxy) ethyl methacrylate.

The copolymer (ii) or (iii) has a weight ratio of vinyl aromatic hydrocarbon and (meth) acrylic acid or vinyl aromatic hydrocarbon and (meth) acrylate of 5 to 99:95. ~ 1, preferably 40-99:
It is obtained by polymerizing a monomer mixture of 60 to 1, more preferably 70 to 99:30 to 1.

The rubber-modified styrenic polymer (iv) is
It is obtained by polymerizing a mixture of a vinyl aromatic hydrocarbon or a monomer copolymerizable therewith with various elastomers. As the vinyl aromatic hydrocarbon, those described in the above (a) for producing the block copolymer are used, and as a monomer copolymerizable therewith, (meth)
Acrylic acid, (meth) acrylic acid ester and the like are used. As the elastomer, butadiene rubber, styrene-butadiene rubber, styrene-butadiene block copolymer elastomer, chloroprene rubber, natural rubber, and the like are used. Particularly preferred rubber-modified styrene polymers include impact-resistant rubber-modified styrene resins (HIP
S).

In the present invention, the weight ratio of the block copolymer (a) to the vinyl aromatic hydrocarbon polymer (b) is from 20 to 100: 0 to 80, preferably from 40 to 10
0: 0 to 60, particularly preferably 50 to 100: 0.
~ 50. If the amount of the block copolymer (a) is less than 20 parts by weight, the impact resistance and the shrinkage of the heat-shrinkable film are insufficient.

The fatty acid monoamide (c) used in the present invention includes saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, and erucic acid. Amides, unsaturated fatty acid monoamides such as ricinoleic acid amide, N-stearylstearic acid amide, N-oleyloleic acid amide, N-stearyloleic acid amide, N-
Substituted amides such as oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, methylol stearic acid amide, and methylol behenic acid amide.

The amount of the fatty acid monoamide (c) is 0.01 to 100 parts by weight per 100 parts by weight of the sum of the block copolymer (a) and the vinyl aromatic hydrocarbon polymer (b).
0.2 parts by weight, preferably 0.02 to 0.15 parts by weight, more preferably 0.02 to 0.12 parts by weight. If the amount is less than 0.01 part by weight, the lubricity is insufficient, the blocking resistance is deteriorated, and the film adheres. In addition, the printability deteriorates. On the other hand, if it exceeds 0.2 parts by weight, it bleeds out on the film surface and the appearance deteriorates (whitens), so that it cannot be put to practical use.

The fatty acid bisamide (d) used in the present invention includes methylene bisstearic acid amide,
Ethylene biscaprate amide, ethylenebislaurate amide, ethylenebisstearate amide, ethylenebisisostearate amide, ethylenebishydroxystearate amide, ethylenebisbehenate amide, hexamethylenebisstearate amide,
Saturated fatty acid bisamides such as hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N, N'-distearyl adipate amide, N, N'-distearyl sebacic acid amide, ethylene bisoleic acid amide, hexamethylene Unsaturated fatty acid bisamides such as bisoleic acid amide, N, N'-dioleyl adipic acid amide, N, N'-dioleyl sebacic acid amide, m-xylylene bis stearic acid amide, N, N'-distearyl isophthalate And aromatic bisamides such as acid amide.

The amount of the fatty acid bisamide (d) is 0.01 to 100 parts by weight per 100 parts by weight of the sum of the block copolymer (a) and the vinyl aromatic hydrocarbon polymer (b).
0.3 parts by weight, preferably 0.02 to 0.2 parts by weight, and more preferably 0.02 to 0.15 parts by weight. If the amount is less than 0.01 part by weight, the lubricity is insufficient, the blocking resistance is deteriorated, and the film adheres. On the other hand, if it exceeds 0.3 parts by weight, the printability deteriorates, so that it cannot be put to practical use.

The fatty acid monoamide of (c) and (d)
When the content of the fatty acid bisamide is within the above range, good blocking resistance and printability can be obtained, but it is more preferable that the weight ratio of (c) to (d) is 15 to 80:85 to 20. (However, the sum of both is 100.)

Various additives can be added to the block copolymer composition shown in the present invention as needed. Examples of the additives include various stabilizers, processing aids, light resistance improvers, softeners, plasticizers, pigments, and the like.

As the stabilizer, 2-tert-butyl-6
-(3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2-
[1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 2,6-di-tert-butyl-4-methylphenol, etc. Examples include phenolic antioxidants and phosphorus-based antioxidants such as trisnonylphenylphosphite. As the processing aid, the light resistance improver, the softener, the plasticizer, the pigment, and the like, generally known ones can be mentioned.

The composition of the present invention comprises (a) a block copolymer, (b) a vinyl aromatic hydrocarbon-based polymer, and (c)
Can be obtained by mixing the fatty acid monoamide of (d) and the fatty acid bisamide of (d), and the mixing method may be any known method. For example, dry blending may be performed using a Henschel mixer, a ribbon blender, a super mixer, a V blender, or the like, and the pellets may be melted and extruded with an extruder. Among them, melt mixing is preferred. When additives are blended as necessary, for example, these additives may be further blended in the above-mentioned (a) to (d) at a predetermined ratio, and the same mixing method as described above may be employed.

The heat-shrinkable film of the present invention can be formed into a uniaxially, biaxially or multiaxially stretched sheet or film extruded by the above-mentioned block copolymer composition by a known method, for example, a T-die method or a tubular method. Can be obtained. Examples of uniaxial stretching include a method of stretching the extruded sheet with a tenter in a direction perpendicular to the direction of extrusion, and a method of stretching the extruded tubular film in a circumferential direction. As an example of biaxial stretching, after stretching the extruded sheet in the extrusion direction with a roll,
Examples thereof include a method of stretching in a direction perpendicular to the extrusion direction with a tenter or the like, and a method of simultaneously or separately stretching the extruded tubular film in the extrusion direction and the circumferential direction.

In the present invention, the stretching temperature is from 60 to 120.
C is preferred. If the temperature is lower than 60 ° C., the sheet or film is broken at the time of stretching, and if the temperature is higher than 120 ° C., good shrinkage characteristics cannot be obtained, which is not preferable. The stretching ratio is not particularly limited, but is preferably 1.5 to 8 times. 1.
If it is less than 5 times, the heat shrinkage will be insufficient, and if it exceeds 8 times, it is not preferable because stretching is difficult. When these films are used as heat-shrinkable labels or packaging materials, the heat shrinkage must be at least 20% at 80 ° C.
If it is less than 20%, a high temperature is required at the time of shrinkage, which adversely affects the coated article, which is not preferable. The thickness of the film is preferably from 10 to 300 μm.

As a use of the heat-shrinkable film of the present invention, a heat-shrinkable label, a heat-shrinkable cap seal, and the like are particularly preferable, but the heat-shrinkable film can also be suitably used as a packaging film.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. However, the present invention is not limited by the following examples.

The method for producing the block copolymers P1, P2, and P7 of (a) used in the examples of the present invention and the block copolymers P3 to P6 used in the comparative examples will be described below. Styrene and butadiene were polymerized using cyclohexane as a solvent, n-butyllithium as an initiator, and tetrahydrofuran as a randomizing agent to produce a block copolymer having structural characteristics as shown in Table 1.

[Preparation of Block Copolymer P1] 65 liters of cyclohexane and 7.
After adding 8 g of tetrahydrofuran and 3.5 kg of styrene, stirring and adding 114 ml of n-butyllithium (10% cyclohexane solution) at a temperature of 30 ° C., the temperature was raised, and polymerization was carried out at 45 ° C. for 1 hour. . Subsequently, 7.38 kg of styrene and 1.87 of butadiene were used.
kg was added and polymerized at 70 ° C. for 1 hour. Subsequently, 7.38 kg of styrene and 1.87 kg of butadiene were further added, and polymerized at 70 ° C. for 1 hour. Thereafter, an excess of methanol was added to the polymerization solution to stop the polymerization, and the solvent was removed.
It was dried to obtain the target block copolymer P1.

[Preparation of Block Copolymer P2] 65 liters of cyclohexane and 7.
8 g of tetrahydrofuran and 3.08 kg of styrene were charged, 118 ml of n-butyllithium (10% cyclohexane solution) was added at a temperature of 30 ° C. while stirring, and then the temperature was raised and polymerized at 45 ° C. for 1 hour. Was. Subsequently, 310 g of butadiene was added and polymerized at 60 ° C. for 1 hour. Subsequently, 7.92 kg of styrene and 1.23 kg of butadiene were added, and polymerized at 70 ° C. for 1 hour.
Subsequently, 310 g of butadiene was added and polymerized at 70 ° C. for 1 hour. Subsequently, 7.92 kg of styrene and 1.23 kg of butadiene were further added, and polymerized at 70 ° C. for 1 hour. Thereafter, the same operation as described above was performed to obtain a target block copolymer P2.

[Production method of block copolymers P7 and P3 to P6] In a 100-liter polymerization vessel, 65 liters of cyclohexane, 7.8 g of tetrahydrofuran and 10.3 k
After adding 120 g of n-butyllithium (10% cyclohexane solution) at a temperature of 30 ° C. with stirring while charging g of styrene, the temperature was raised and polymerization was carried out at 45 ° C. for 1 hour. Subsequently, 5.5 kg of butadiene was added,
Polymerization was performed at 70 ° C. for 1 hour. Subsequently, styrene 6.
2 kg was added, and polymerization was carried out at 70 ° C. for 1 hour. afterwards,
By operating in the same manner as above, the desired block copolymer P7 was obtained. By changing the weight ratio of styrene and butadiene, the same operation as P1 was performed to obtain P3 to P6. The number average molecular weight (Mn) was adjusted by the amount of n-butyllithium added, and the block ratio was adjusted by the amount of tetrahydrofuran added.

Next, examples of the block copolymer composition and the heat-shrinkable film thereof of the present invention and comparative examples are shown below.

Examples 1 to 5 and Comparative Examples 1 to 10
After mixing the block copolymer (a), the polymer (b) shown in Table 2, and the components (c) and (d) shown in Table 2 with a Henschel mixer according to the blending recipes in Tables 3 to 5, respectively. Then, the mixture was melted and pelletized by an extruder to produce a block copolymer composition. Tables 3 to 5 show the physical properties of the injection molded articles and the physical properties of the films of the respective block copolymers. In addition, the film is first formed at a temperature of 210 ° C. and a thickness of 0.3.
mm sheet was extruded and then uniaxially stretched 5 times at a temperature of 95 ° C. using a biaxial stretching device manufactured by Toyo Seiki Seisaku-sho, Ltd. Film thickness is 6
0 μm. Examples 1 to 5 in Table 3 and Tables 4 and 5
By comparison of Comparative Examples 1 to 10, the block copolymer composition of the present invention is excellent in transparency, rigidity and impact resistance,
It turns out that it is excellent in blocking resistance and printability.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[Method of Measuring Structural Features and Properties] Table 1
The structural characteristics and physical properties shown in Nos. To 5 were measured by the following methods. (1) Number average molecular weight: measured by the GPC method under the following conditions. Measuring machine; Showa Denko Co., Ltd. “SHODEX SY”
STEM-21 "column; polymer laboratory (POLYMER)
LABORATORY INC. "PL gel"
MIXED-B ", three solvents; tetrahydrofuran quantification; standard curve prepared using polystyrene. (2) Tensile modulus; measured in accordance with JIS K-6871. The test piece used was No. 1 and the test speed was F.
The higher the tensile modulus, the higher the rigidity. (3) Izod impact strength; JIS K6
871. No. 2 A was used as a test piece. The higher the Izod impact strength, the higher the impact resistance. (4) Coefficient of static friction; a film cut into 10 cm x 6.4 cm on a thread of a friction measuring device (AN type) manufactured by Toyo Seiki Seisaku-sho, Ltd .;
After setting the cut film to m, the friction angle X
(°) was measured, and the value of tanX was taken as the static friction coefficient.
The smaller the coefficient of static friction, the higher the lubricity. (5) Blocking resistance; four films cut into a size of 35 mm × 50 mm are prepared. This film is overlaid, SUS plates are applied from both sides, and tightened with bolts. After being immersed in warm water of 80 ° C. for 30 minutes, the superposed film is taken out. The film was shifted sideways with a finger, and the ease of movement was evaluated according to the following scale. ○: easily move. Δ: hard to move. ×: Does not move. (6) Ink peeling rate: The film was coated with ink "STR722 (yellow)" manufactured by Dainichi Seika Co., Ltd., air-dried for 2 hours, and then adhered to a cellophane tape and peeled off. The peeling rate was calculated and evaluated. The lower the ink release rate, the better the printability. Ink peeling rate (%) = (area where ink was peeled off) / (area of ink-applied surface to which cellophane tape was applied) × 100 (7) Heat shrinkage; dipped film in hot water of 80 ° C. for 30 seconds, It was calculated from the equation. Heat shrinkage (%) = (L1−L2) / L1 × 100, where L1 is the length before shrinkage (stretching direction) and L2 is the length after shrinking (stretching direction). The films used for the measurement of these physical properties were obtained by cutting the stretched films prepared in the above Examples and Comparative Examples into predetermined sizes.

[0059]

The block copolymer composition of the present invention is excellent in transparency, rigidity, impact resistance, blocking resistance, and printability. It is suitable for use as various packaging films such as cap seals. In addition, various molded products can be obtained by injection molding or injection hollow molding, or formed into films / sheets by extrusion molding, inflation molding, etc., and used for various purposes as they are or by secondary processing such as vacuum pressure molding. It is also possible.

Claims (3)

[Claims] 1. The following (a), (b), (c) and (d)
The block copolymer composition which mix | blended. (A) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 6
0 to 90:40 to 10, and the number average molecular weight is 4
20 to 100 parts by weight of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene having a molecular weight of 000 to 500,000, and (b) at least one vinyl aromatic selected from the following (i) to (iv): 0 to 80 parts by weight of an aromatic hydrocarbon polymer, (i) a vinyl aromatic hydrocarbon polymer, (ii) a copolymer of a vinyl aromatic hydrocarbon and (meth) acrylic acid, and (iii) a vinyl aromatic hydrocarbon. (Iv) rubber-modified styrene-based polymer (provided that (i)
In i) and (iii), the weight ratio of the vinyl aromatic hydrocarbon to the comonomer copolymerized with the vinyl aromatic hydrocarbon is from 5 to 99:95 to 1. (C) Fatty acid monoamide is the sum of (a) and (b) 100
0.01 to 0.2 parts by weight per part by weight, (d) The fatty acid bisamide is the sum of (a) and (b) 100
0.01 to 0.3 parts by weight per part by weight. 2. The structure of the block copolymer (a) is a block copolymer represented by at least one selected from the following formulas (a) to (e). Item 7. The block copolymer composition according to Item 1. (B) A- (B) n (b) AC- (B) n (c) A- (CB) m (d) A- (CB) m- (B) n (e) A- (CA) n (where A is a polymer chain of a vinyl aromatic hydrocarbon,
B is a copolymer chain of a vinyl aromatic hydrocarbon and a conjugated diene;
Represents a polymer chain of a conjugated diene. M is an integer of 2 or more;
n shows the integer of 1 or more. ) 3. A heat-shrinkable film obtained by molding the block copolymer composition according to claim 1 or 2.