JP5057753B2 - Heat shrinkable film - Google Patents

Description

  The present invention relates to a heat-shrinkable film and a heat-shrinkable multilayer film excellent in physical property balance such as rigidity, low-temperature elongation, low-temperature shrinkage, and solvent resistance.

  A block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene, which has a relatively high vinyl aromatic hydrocarbon content, is used for injection molding applications, sheets, films, etc. by utilizing characteristics such as transparency and impact resistance. It is used for extrusion molding applications. In particular, heat-shrinkable films using block copolymer resins composed of vinyl aromatic hydrocarbons and conjugated dienes are the residual monomers and plasticizers of vinyl chloride resins used in the past, and the generation of hydrogen chloride during incineration. Since there is no problem, it is used for food packaging, cap seals, labels, etc. Properties required for heat-shrinkable films include natural shrinkage, low-temperature shrinkage, transparency, mechanical strength, suitability for packaging machines, and the like. So far, various studies have been made to improve these characteristics and obtain a good balance of physical properties.

  For example, a heat-shrinkable film having a specific Tg in a block copolymer segment composed of a vinyl aromatic hydrocarbon and a conjugated diene is disclosed in order to obtain a heat-shrinkable film having excellent shrinkage characteristics and environmental damage resistance. (For example, refer to Patent Document 1). Further, in order to obtain a heat-shrinkable film having excellent shrinkage characteristics and environmental destruction resistance, a heat-shrinkable film comprising a block copolymer composition comprising a vinyl aromatic hydrocarbon having a specific structure and a conjugated diene is disclosed. (For example, Patent Document 2). Further, in order to obtain a polymer composition excellent in transparency, rigidity, impact resistance, natural shrinkage resistance, and the like, and a heat shrinkable film produced using the polymer composition, an aromatic hydrocarbon having a specific structure and a conjugated diene are used. A block copolymer and a composition thereof are disclosed (for example, Patent Document 3). In addition, in order to obtain a heat-shrinkable film excellent in transparency, rigidity, impact resistance and natural shrinkage resistance, a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene having specific storage elastic modulus behavior is disclosed. (For example, refer to Patent Document 4). In addition, in order to obtain a heat-shrinkable (multi-layer) film with low natural shrinkage while maintaining good low-temperature shrinkability, vinyl aroma that satisfies the relationship of the loss tangent value obtained by specific dynamic viscoelasticity measurement to temperature A block copolymer comprising a group hydrocarbon and a conjugated diene is disclosed (for example, see Patent Document 5). In addition, in order to obtain a heat-shrinkable film excellent in natural shrinkage resistance, elongation and perforation, a block copolymer comprising a vinyl aromatic hydrocarbon having a specific vinyl aromatic hydrocarbon polymer block and a conjugated diene Is disclosed (for example, see Patent Document 6).

However, these vinyl aromatic hydrocarbons and block copolymers composed of conjugated dienes or compositions of the block copolymers and vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymers are rigid, low-temperature compositions. The balance of physical properties such as elongation, low temperature shrinkage and solvent resistance and the elongation at the time of printing when the film is thinned are not sufficient, and these documents do not disclose how to improve them, and still remain on the market. The problem is pointed out.
JP-A-60-224520 JP 60-224522 A JP-A-7-216186 JP-A-11-158241 WO02 / 38642 publication JP 2003-313259 A

  An object of this invention is to provide the heat-shrinkable film and heat-shrinkable multilayer film which are excellent in physical property balance, such as rigidity, low temperature elongation, low temperature shrinkage, and solvent resistance.

  As a result of intensive studies, the inventors of the present invention include a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene, or a hydrogenated product (I) thereof and a polyolefin-based polymer (II) composition, and a specific storage elasticity. The present inventors have found that the above object can be achieved by forming a heat-shrinkable film with a material having a modulus (E ′) behavior and a loss elastic modulus (E ″) behavior, and the present invention has been achieved.

That is, the present invention
[1] A block copolymer having a vinyl aromatic hydrocarbon content of 65 to 95% by weight and a conjugated diene content of 5 to 35% by weight or a hydrogenated product (I) thereof and a polyolefin polymer ( II) is a material comprising a composition having a weight ratio of 99.9 / 0.1 to 50/50, and a storage elastic modulus (E ′) at 50 ° C. of 0.9 × 10 ^{9 to} 1.8 × In the range of 10 ⁹ Pa, the ratio (E-50 / E25) of the storage elastic modulus (E-50) at −50 ° C. to the storage elastic modulus (E25) at 25 ° C. is in the range of 1-1.75, and A heat-shrinkable film formed of a material having a peak elastic modulus (E ″) temperature of 60 ° C. or higher and 110 ° C. or lower;
[2] The composition further contains at least one polymer (III) of the following (i) to (iv), and the content of the polymer (III) in the composition is 0.1 to 80 wt. %, The heat-shrinkable film according to [1] above, (i) a block copolymer comprising a vinyl aromatic hydrocarbon not containing component (I) and a conjugated diene, or a hydrogenated product thereof (ii) vinyl aroma A copolymer comprising an aromatic hydrocarbon and an aliphatic unsaturated carboxylic acid derivative (iii) a vinyl aromatic hydrocarbon polymer (iv) a rubber-modified styrene polymer;
[3] The heat shrinkability according to the above [1] or [2], wherein the storage elastic modulus (E ′) at 50 ° C. of the material is in the range of 1.0 × 10 ^{9 to} 1.65 × 10 ⁹ Pa. the film;
[4] A ratio (E-50 / E25) of a storage elastic modulus (E-50) at −50 ° C. and a storage elastic modulus (E25) at 25 ° C. of the material is in the range of 1 to 1.6. 1]-[3] heat shrinkable film;
[5] The heat-shrinkable film according to any one of [1] to [4], wherein at least one peak temperature of the loss elastic modulus (E ″) of the material is 75 ° C. or higher and 105 ° C. or lower;
[6] The above [1] to [1], wherein the material contains 0.01 to 5 parts by weight of at least one lubricant selected from fatty acid amide, paraffin, hydrocarbon resin and fatty acid with respect to 100 parts by weight of the material. [5] The heat-shrinkable film according to any one of the above;
[7] The material is 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl with respect to 100 parts by weight of the material. Selected from acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 2,4-bis [(octylthio) methyl] -o-cresol The heat-shrinkable film according to any one of the above [1] to [5], comprising 0.05 to 3 parts by weight of at least one stabilizer.
[8] The material is at least one ultraviolet absorber or light stabilizer selected from a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer with respect to 100 parts by weight of the material. 0.05 to 3 parts by weight of the heat-shrinkable film according to any one of the above [1] to [5];
[9] A heat-shrinkable multilayer film comprising the heat-shrinkable film according to any one of [1] to [8] as at least one layer;
[10] The heat-shrinkable multilayer film according to [9], wherein the heat shrinkage rate at 80 ° C. in the stretching direction is 10 to 80%;
[11] A heat-shrinkable multilayer film comprising the heat-shrinkable film according to any one of [1] to [8] as an intermediate layer, and an outer layer having a Vicat softening temperature 3 to 15 ° C. higher than that of the intermediate layer.

  According to the present invention, it is possible to obtain a heat-shrinkable film and a heat-shrinkable multilayer film excellent in physical property balance such as rigidity, low-temperature elongation, low-temperature shrinkage and solvent resistance.

  Hereinafter, the present invention will be described in detail.

The present invention relates to a block copolymer having a vinyl aromatic hydrocarbon content of 65 to 95% by weight and a conjugated diene content of 5 to 35% by weight or a hydrogenated product thereof (I) (hereinafter referred to as component (I). )) And polyolefin polymer (II) (hereinafter also referred to as component (II)) in a weight ratio of 99.9 / 0.1 to 50/50, Alternatively, a composition comprising component (I), component (II), and at least one of the following polymers (III) (i) to (iv) (hereinafter sometimes referred to as component (III)): The present invention relates to a heat shrinkable film as a material.
(I) Block copolymer comprising vinyl aromatic hydrocarbon and conjugated diene not containing component (I) or hydrogenated product thereof (ii) Copolymer comprising vinyl aromatic hydrocarbon and aliphatic unsaturated carboxylic acid derivative Compound (iii) Vinyl aromatic hydrocarbon polymer (iv) Rubber-modified styrenic polymer [Component (I)]
The content of the vinyl aromatic hydrocarbon of component (I) used in the present invention is in the range of 65 to 95% by weight, preferably 70 to 93% by weight, more preferably 75 to 90% by weight. The amount ranges from 5 to 35% by weight, preferably from 7 to 30% by weight, more preferably from 10 to 25% by weight. When the vinyl aromatic hydrocarbon content is 65 to 95% by weight and the conjugated diene content is 5 to 35% by weight, the heat-shrinkable film is excellent in rigidity and low temperature elongation. In addition, you may grasp | ascertain the vinyl aromatic hydrocarbon content of a hydrogenated block copolymer by the vinyl aromatic compound content of the block copolymer before hydrogenation.

  The peak molecular weight of the component (I) measured by gel permeation chromatography (GPC) is 30,000 to 1,000,000, preferably 50,000 to 850,000, and more preferably 80,000 to 700,000.

  Furthermore, the molecular weight distribution of component (I) preferably has at least one peak molecular weight in the range of 30,000 to 200,000 and in the range of more than 200,000 and less than 1,000,000.

Component (I) of the present invention comprises at least one segment composed of a vinyl aromatic hydrocarbon homopolymer and / or a copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene, a conjugated diene homopolymer, and / or Or it has at least one segment comprised from the copolymer which consists of a vinyl aromatic hydrocarbon and a conjugated diene. The polymer structure of component (I) is not particularly limited. For example, the general formula (AB) _n , A- (BA) _n , B- (AB) _{n + 1}
[(A−B) _k ] _{m + 1} −X, [(A−B) _k −A] _{m + 1} −X
[(B−A) _k ] _{m + 1} −X, [(B−A) _k −B] _{m + 1} −X
(In the above formula, segment A is a vinyl aromatic hydrocarbon homopolymer and / or a copolymer comprising vinyl aromatic hydrocarbon and conjugated diene, and segment B is a conjugated diene homopolymer and / or vinyl aromatic hydrocarbon. X is a copolymer of a conjugated diene, for example, X is a residue or polyvalent of a coupling agent such as silicon tetrachloride, tin tetrachloride, 1,3 bis (N, N-glycidylaminomethyl) cyclohexane, epoxidized soybean oil, etc. It represents a residue of an initiator such as a functional organolithium compound, where n, k, and m are integers of 1 or more, generally an integer of 1 to 5. In addition, the structure of a polymer chain that is bonded to X by a plurality May be the same or different.), And a linear block copolymer or a radial block copolymer represented by the following formula, or any mixture of these polymer structures can be used. Further, in the radial block copolymer represented by the above general formula, at least one A and / or B may be bonded to X.

  In the present invention, the vinyl aromatic hydrocarbon in the copolymer of vinyl aromatic hydrocarbon and conjugated diene in segment A and segment B may be distributed uniformly or in a tapered (gradual decrease) form. Good. In the copolymer, a plurality of portions where vinyl aromatic hydrocarbons are uniformly distributed and / or portions where tapes are distributed may coexist in the segment. Vinyl aromatic hydrocarbon content in segment A ({vinyl aromatic hydrocarbon in segment A / (vinyl aromatic hydrocarbon in segment A + conjugated diene)} × 100) and vinyl aromatic carbon in segment B The relationship between the hydrogen content ({vinyl aromatic hydrocarbon in segment B / (vinyl aromatic hydrocarbon in segment B + conjugated diene)} × 100) is greater with the vinyl aromatic hydrocarbon content in segment A. , Greater than the vinyl aromatic hydrocarbon content in segment B. The difference in the preferred vinyl aromatic hydrocarbon content between segment A and segment B is preferably 5% by weight or more.

  In the present invention, component (I) can be obtained by polymerizing a vinyl aromatic hydrocarbon and a conjugated diene in a hydrocarbon solvent using an organolithium compound as an initiator.

  Examples of the vinyl aromatic hydrocarbon used in the present invention include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, 1, Examples include 1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and a particularly common one is styrene. These may be used alone or in combination of two or more.

  As the conjugated diene, a diolefin having a pair of conjugated double bonds can be used. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1, Examples include 3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and particularly common examples include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

  In component (I) of the present invention, (b) a copolymer block comprising isoprene and 1,3-butadiene, (b) a copolymer block comprising isoprene and vinyl aromatic hydrocarbon, and (c) isoprene and 1, At least one polymer block selected from the group (a) to (c) of a copolymer block comprising 3-butadiene and vinyl aromatic hydrocarbon may be incorporated, and the weight ratio of butadiene to isoprene is 3 / 97 to 90/10, preferably 5/95 to 85/15, more preferably 10/90 to 80/20. A hydrogenated block copolymer composed of a block copolymer having a weight ratio of butadiene to isoprene of 3/97 to 90/10 can form a gel in thermoforming and processing if the hydrogenation ratio is 50% by weight or less. Few.

  Component (I) of the present invention can be obtained, for example, by anion living polymerization using an initiator such as an organic alkali metal compound in a hydrocarbon solvent. Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and cycloheptane. In addition, alicyclic hydrocarbons such as methylcycloheptane, and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene can be used. These may be used alone or in combination of two or more.

  As the polymerization initiator, aliphatic hydrocarbon alkali metal compounds, aromatic hydrocarbon alkali metal compounds, organic amino alkali metal, which are generally known to have anionic polymerization activity for conjugated dienes and vinyl aromatic compounds. A compound or the like can be used. Examples of the alkali metal include lithium, sodium, potassium, and the like. Suitable organic alkali metal compounds are aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, and one lithium per molecule. And dilithium compounds, trilithium compounds, and tetralithium compounds containing a plurality of lithium atoms in one molecule. Specifically, n-propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium, diisopropenylbenzene and sec-butyl lithium Examples of the reaction product include a reaction product of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene. Furthermore, organic alkali metal compounds disclosed in US Pat. No. 5,708,092, British Patent 2,241,239, US Pat. No. 5,527,753, etc. are also used. be able to. These may be used alone or in combination of two or more.

  In the present invention, the polymerization temperature for producing the block copolymer before hydrogenation is generally -10 ° C to 150 ° C, preferably 40 ° C to 120 ° C. The time required for the polymerization varies depending on the conditions, but is usually within 10 hours, particularly preferably 0.5 to 5 hours. The polymerization atmosphere is preferably replaced with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is carried out within a range of pressure sufficient to maintain the monomer and solvent in the liquid layer within the above polymerization temperature range. Furthermore, care must be taken not to mix impurities, such as water, oxygen, carbon dioxide, etc., that inactivate the catalyst and living polymer into the polymerization system.

  The hydrogenated block copolymer of component (I) of the present invention can be obtained by hydrogenating the block copolymer before hydrogenation obtained above. The hydrogenation catalyst is not particularly limited and is conventionally known (1) A supported heterogeneous hydrogenation in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like. A catalyst, (2) a so-called Ziegler-type hydrogenation catalyst using an organic acid salt such as Ni, Co, Fe, Cr or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum, (3) Ti, Ru, A homogeneous hydrogenation catalyst such as a so-called organometallic complex such as an organometallic compound such as Rh or Zr is used. Specific examples of the hydrogenation catalyst include Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-337970, Japanese Patent Publication No. 1-53851, The hydrogenation catalyst described in Japanese Utility Model Publication No. 2-9041 can be used. A preferred hydrogenation catalyst is a mixture with a titanocene compound and / or a reducing organometallic compound.

  As the titanocene compound, compounds described in JP-A-8-109219 can be used. Specific examples thereof include (substitution) such as biscyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride. Examples thereof include compounds having at least one ligand having a cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton. Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

  The hydrogenation reaction is generally carried out in a temperature range of 0 to 200 ° C, more preferably 30 to 150 ° C. The pressure of hydrogen used for the hydrogenation reaction is 0.1 to 15 MPa, preferably 0.2 to 10 MPa, and more preferably 0.3 to 7 MPa. The hydrogenation reaction time is usually 3 minutes to 10 hours, preferably 10 minutes to 5 hours. The hydrogenation reaction can be any of a batch process, a continuous process, or a combination thereof.

  In the hydrogenated block copolymer of the present invention, the hydrogenation rate of the unsaturated double bond based on the conjugated diene can be arbitrarily selected according to the purpose and is not particularly limited. When obtaining a hydrogenated block copolymer having good thermal stability and weather resistance, it exceeds 70% of the unsaturated double bond based on the conjugated diene compound in the hydrogenated block copolymer, preferably 75% or more. It is recommended that 85% or more, particularly preferably 90% or more, is hydrogenated. When obtaining a hydrogenated block copolymer having good thermal stability, the hydrogenation rate is preferably 3 to 70%, alternatively 5 to 65%, particularly preferably 10 to 60%. The hydrogenation rate of the aromatic double bond based on the vinyl aromatic hydrocarbon in the hydrogenated block copolymer is not particularly limited, but the hydrogenation rate is 50% or less, preferably 30% or less, more preferably Is preferably 20% or less. The hydrogenation rate can be known by a nuclear magnetic resonance apparatus (NMR).

  In the present invention, the microstructure (ratio of cis, trans, vinyl) of the conjugated diene portion of the hydrogenated block copolymer can be arbitrarily changed by the use of the aforementioned polar compound or the like, and is not particularly limited. In general, the vinyl bond amount can be set in the range of 5 to 90%, preferably 10 to 80%, more preferably 15 to 75%. In the present invention, the amount of vinyl bonds means the total amount of 1,2-vinyl bonds and 3,4-vinyl bonds (however, when 1,3-butadiene is used as the conjugated diene, 1,2-vinyl bonds are used. Binding amount). The amount of vinyl bonds can be grasped by a nuclear magnetic resonance apparatus (NMR).

[Component (II)]
The polyolefin polymer of component (II) of the present invention is at least one polymer selected from polypropylene resins, polyethylene polymers and the like, for example, polyethylene, ethylene copolymers (ethylene-vinyl acetate copolymer). Copolymers, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-methacrylic acid copolymers, etc., or other copolymer systems of ethylene and unsaturated fatty acids Derivatives, ethylene ionomer resins, ethylene-α olefin copolymers, etc.), modified polymers having a carboxylic acid group added thereto, polybutene-1 copolymers, etc. Are listed. Among them, preferably, a polypropylene resin (including random copolymers and these alicyclic saturated hydrocarbon resins, petroleum resins, tempen resins, and resins modified with rosins), high density polyethylene, linear low density polyethylene (L / LDPE), ultra-low density polyethylene, ionomer resin (for example, ethylene), and the like.

[Component (III)]
Component (III) of the present invention is at least one selected from the following i) to iv). (I) a block copolymer or a hydrogenated product thereof comprising a vinyl aromatic hydrocarbon and a conjugated diene different from the block copolymer or the hydrogenated product (I);
(Ii) a copolymer comprising a vinyl aromatic hydrocarbon and an aliphatic unsaturated carboxylic acid derivative (iii) a vinyl aromatic hydrocarbon polymer,
(Iv) Rubber-modified styrenic polymer (i) Block copolymer or hydrogenated product thereof (i) A block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene different from the hydrogenated product (I) or hydrogenated product thereof The polymer structure of the product (hereinafter sometimes referred to as component (i)) (for hydrogenated products, the polymer structure before hydrogenation) is represented by the general formula:
(Ab-Bb) _n , Ab- (Bb-Ab) _n , Bb- (Ab-Bb) _{n + 1}
(Wherein n is an integer of 1 or more, generally 1 to 5), or a linear block copolymer represented by the general formula:
[(Ab−Bb) _k ] _{m + 2} −X, [(Ab−Bb) _k −Ab] _{m + 2} −X,
[(Bb−Ab) _k ] _{m + 2} −X, [(Bb−Ab) _k −Bb] _{m + 2} −X
(In the above formula, Ab is a polymer block mainly composed of vinyl aromatic hydrocarbon, and Bb is a polymer mainly composed of conjugated diene. The boundary between the Ab block and Bb block is not always clearly distinguished. X is a residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, 1,3 bis (N, N-glycidylaminomethyl) cyclohexane, epoxidized soybean oil, or a polyfunctional organolithium compound. Indicating the residue of the initiator, k and m are integers of 1 to 5), or a mixture of arbitrary polymer structures of these block copolymers. The preferred vinyl aromatic hydrocarbon content of component (i) is 10% by weight or more and less than 65% by weight, more preferably 15 to 60% by weight. The molecular weight of component (i) is such that the number average molecular weight (polystyrene equivalent molecular weight) measured by gel permeation chromatography (GPC) is 30,000 to 500,000, preferably 50,000 to 500,000, more preferably 70,000 to 300,000. It may be a mixture of a plurality of block copolymers with different molecular weights. The number average molecular weight can be arbitrarily adjusted according to the amount of catalyst used in the polymerization.

(Ii) a vinyl aromatic hydrocarbon of a copolymer (hereinafter sometimes referred to as component (ii)) comprising a vinyl aromatic hydrocarbon and an aliphatic unsaturated carboxylic acid derivative used in the present invention is the above-mentioned The aliphatic unsaturated carboxylic acid derivatives are acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, etc. of the number of C ₁ -C ₁₃ preferably carbon C ₂ -C ester derivative of the alcohol and acrylic acid ₁₃ or methacrylic acid or carbon atoms similarly C ₁ -C ₁₃ preferably C ₂ ~C _13,,, and more preferably ester derivatives of alcohols with methacrylic acid C ₃ -C ₁₃ are also alpha, beta-unsaturated dicarboxylic acids, such as fumaric acid, itaconic acid, maleic acid, or In which the mono- or diester derivatives with alcohols of these dicarboxylic acids with C ₂ -C ₁₃ is selected at least one. These are generally composed mainly of the esters, and the amount thereof is preferably 50 mol% or more, more preferably 70 mol% or more. The type is preferably composed mainly of esters such as ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate and octyl acrylate. As the production method of component (ii), 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 or the like can be used, and the weight average molecular weight is generally From 50,000 to 500,000 polymers can be used.

  Particularly preferred as component (ii) is a copolymer mainly composed of styrene and n-butyl acrylate, wherein the total amount of n-butyl acrylate and styrene is 50% by weight or more, more preferably n-acrylate. An aliphatic unsaturated carboxylic acid ester-styrene copolymer in which the total amount of butyl and styrene is 60% by weight or more. A heat-shrinkable film using an aliphatic unsaturated carboxylic acid ester-styrene copolymer mainly composed of n-butyl acrylate and styrene has good shrinkage.

  The (iii) vinyl aromatic hydrocarbon polymer used in the present invention (hereinafter sometimes referred to as component (iii)) is obtained by polymerizing a vinyl aromatic hydrocarbon or a monomer copolymerizable therewith ( However, the component (ii) is excluded). Vinyl aromatic hydrocarbons mainly refer to styrene monomers, specifically styrene, α-alkyl substituted styrenes such as α-methyl styrenes, nuclear alkyl substituted styrenes, nuclear halogen substituted styrenes, etc. It is sufficient to select at least one selected from the above, depending on the purpose. Examples of the monomer copolymerizable with the vinyl aromatic hydrocarbon include acrylonitrile and maleic anhydride. Examples of the vinyl aromatic hydrocarbon polymer include polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer, styrene-maleic anhydride copolymer, etc., and particularly preferred vinyl aromatic hydrocarbons. An example of the polymer is polystyrene. These vinyl aromatic hydrocarbon polymers generally have a weight average molecular weight of 50,000 to 500,000. Moreover, these vinyl aromatic hydrocarbon polymers can be used alone or as a mixture of two or more, and can be used as a rigidity improving agent.

  The (iv) rubber-modified styrenic polymer used in the present invention (hereinafter sometimes referred to as component (iv)) is obtained by polymerizing a mixture of a monomer and an elastomer copolymerizable with a vinyl aromatic hydrocarbon. As the polymerization method, suspension polymerization, emulsion polymerization, bulk polymerization, bulk-suspension polymerization and the like are generally performed. Examples of the monomer copolymerizable with the vinyl aromatic hydrocarbon include α-methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, maleic anhydride and the like. As the copolymerizable elastomer, natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber, high styrene rubber or the like is used.

  These elastomers are generally 3 to 50 parts by weight with respect to 100 parts by weight of vinyl aromatic hydrocarbon or a monomer copolymerizable therewith, or dissolved in latex or emulsion-like, bulk polymerization, bulk-suspension polymerization in latex form. Etc. A particularly preferable rubber-modified styrene polymer is an impact-resistant rubber-modified styrene polymer (HIPS). The rubber-modified styrenic polymer can be used as an agent for improving rigidity, impact resistance and slipperiness. A polymer having a weight average molecular weight of 50,000 to 500,000 can be used. The addition amount of the rubber-modified styrenic polymer is preferably 0.1 to 10 parts by weight in consideration of maintaining transparency.

  The MFR of component (i) to (iv) used in the present invention (temperature 200 ° C., load 5 Kg under G condition) is 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, from the viewpoint of molding. 1-30 g / 10 min is recommended.

[Composition]
Composition of component (I) and component (II) of the present invention, or composition of component (I), component (II) and component (III) (hereinafter sometimes referred to as “composition of the present invention”) The weight ratio of component (I) to component (II) is 99.9 / 0.1 to 50/50, preferably 99/1 to 45/55, more preferably 95/5 to 40. / 60. When the weight ratio of component (I) to component (II) is in the range of 99.9 / 0.1 to 50/50, the solvent resistance is excellent.

  The content of component (III) in the composition of the present invention (that is, assuming that component (I), component (II) and component (III) are 100% by weight) is 0.1 to 80% by weight, preferably 1 to 70%. % By weight, more preferably 5 to 60% by weight. When the content of component (III) is in the range of 0.1 to 80% by weight, the balance between rigidity and elongation is excellent.

  The composition of the present invention can be produced by any conventionally known blending method. For example, an open roll, an intensive mixer, an internal mixer, a kneader, a continuous kneader with a twin-screw rotor, a melt-kneading method using a general mixer such as an extruder, a solvent after each component is dissolved or dispersed and mixed For example, a method of removing heat by heating is used.

[material]
The material of the present invention includes the above-described composition of the present invention, and may contain various additives described later in addition to the composition of the present invention.

The material of the present invention has a storage elastic modulus (E ′) at 50 ° C. of 0.9 × 10 ^{9 to} 1.8 × 10 ⁹ Pa, preferably 1.0 × 10 ^{9 to} 1.65 × 10 ⁹ Pa, More preferably, it is 1.05 × 10 ^{9 to} 1.55 × 10 ⁹ Pa. When the storage elastic modulus (E ′) at 50 ° C. is in the range of 0.9 × 10 ^{9 to} 1.8 × 10 ⁹ Pa, the physical property balance between rigidity and elongation is excellent. The storage elastic modulus (E ′) at 50 ° C. is to adjust the vinyl aromatic hydrocarbon content of component (I), component (I) and component (II), or component (I), component (II) and It can be controlled by measuring the storage elastic modulus (E ′) of each component (III) at 50 ° C. in advance and adjusting the weight ratio.

  The ratio (E-50 / E25) of the storage elastic modulus (E-50) at -50 ° C and the storage elastic modulus (E25) at 25 ° C in the material of the present invention is 1-1.75, preferably 1-1.6. More preferably, it is in the range of 1 to 1.5. When E-50 / E25 is in the range of 1-1.75, the rigidity and the low temperature elongation are excellent. E-50 / E25 is the storage elastic modulus (E-50) at -50 ° C. and 25 ° C. of each component of component (I) and component (II) or component (I), component (II) and component (III). It can be controlled by measuring the storage elastic modulus (E25) in advance and adjusting the weight ratio, but the storage elastic modulus (E-50) of component (I) at −50 ° C. and storage elastic modulus at 25 ° C. It is preferable to use the component (I) that has no inflection in the range of the rate (E25) or has few inflections. Alternatively, it can be controlled by measuring in advance the storage elastic modulus (E-50) at -50 ° C. and the storage elastic modulus (E25) at 25 ° C. of the plurality of components (I) and adjusting the weight ratio.

  Here, the example of the method of controlling the storage elastic modulus (E ') of a component (I) is shown below. When vinyl aromatic hydrocarbons are homopolymerized and the polymerization is completed, a mixture of vinyl aromatic hydrocarbon and conjugated diene is charged at once and polymerization is continued. Vinyl aromatic hydrocarbon / conjugated diene ratio gradually changes. A vinyl aromatic hydrocarbon-conjugated diene block copolymer having a hydrocarbon / conjugated diene copolymer portion can be obtained. In addition, when a uniform mixture of vinyl aromatic hydrocarbon and conjugated diene is continuously charged, vinyl aromatic carbon having a vinyl aromatic hydrocarbon / conjugated diene copolymer part with a uniform ratio of vinyl aromatic hydrocarbon / conjugated diene. A hydrogen-conjugated diene block copolymer can be obtained. Whereas the storage elastic modulus (E ') behavior of block copolymers with vinyl aromatic hydrocarbon / conjugated diene copolymer part with gradually changing vinyl aromatic hydrocarbon / conjugated diene ratio is decreasing The behavior of the storage elastic modulus (E ′) of a block copolymer having a vinyl aromatic hydrocarbon / conjugated diene copolymer portion having a uniform vinyl aromatic hydrocarbon / conjugated diene ratio changes abruptly. Therefore, after homopolymerizing vinyl aromatic hydrocarbons, a mixture of vinyl aromatic hydrocarbon and conjugated diene is charged and polymerization is continued, and a uniform mixture of vinyl aromatic hydrocarbon and conjugated diene is continuously charged. By appropriately adopting the method and adjusting the vinyl aromatic hydrocarbon content of the block copolymer together, it becomes possible to obtain a polymer having an arbitrary viscoelastic property of component (I). Any vinyl aromatic hydrocarbon homopolymer-vinyl aromatic hydrocarbon / conjugated diene copolymer part-vinyl aromatic hydrocarbon homopolymer (SS / BS) can be produced by the above-described method. it can.

  The peak temperature of the loss elastic modulus (E ″) of the material of the present invention is 60 ° C. or higher and 110 ° C. or lower, preferably 75 ° C. or higher and 105 ° C. or lower, more preferably 80 ° C. or higher and 100 ° C. or lower. When the peak temperature of the loss modulus (E ″) is 60 ° C. or higher and 110 ° C. or lower, the low temperature shrinkability is excellent. The peak temperature of the loss elastic modulus (E ″) is the peak temperature of the loss elastic modulus (E ″) of each component of the component (I) and the component (II), or the component (I), the component (II) and the component (III). Can be controlled by measuring in advance and adjusting the weight ratio. The peak temperature of the loss modulus (E ″) of component (I) can be controlled by adjusting the ratio of vinyl aromatic hydrocarbon and conjugated diene in the copolymer block of vinyl aromatic hydrocarbon and conjugated diene. As the vinyl aromatic hydrocarbon content increases, the peak temperature of the loss modulus (E ″) increases, and when the vinyl aromatic hydrocarbon content decreases, the peak temperature of the loss modulus (E ″) decreases.

  In the material of the present invention, at least one selected from fatty acid amide, paraffin, hydrocarbon resin and fatty acid as a lubricant is added in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 100 parts by weight of the material of the present invention. By adding -4 parts by weight, more preferably 0.1-3 parts by weight, the heat-shrinkable film has good blocking resistance.

  Examples of fatty acid amides include stearoamide, oleyl amide, erucyl amide, behen amide, mono- or bisamide of higher fatty acids, ethylene bis stearoamide, stearyl oleylamide, N-stearyl erucamide, etc. Two or more types can be mixed and used.

  Examples of the paraffin and hydrocarbon resins include paraffin wax, microcrystalline wax, liquid paraffin, paraffin synthetic wax, polyethylene wax, composite wax, montan wax, hydrocarbon wax, silicone oil, etc. Two or more types can be mixed and used.

  Examples of fatty acids include saturated fatty acids and unsaturated fatty acids. That is, there are saturated fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid and hydroxystearic acid, and unsaturated fatty acids such as oleic acid, erucic acid and ricinoleic acid. These may be used alone or in combination of two or more. Can be used.

  In the material of the present invention, as a UV absorber and a light stabilizer, at least one UV absorber and a light stabilizer selected from a benzophenone UV absorber, a benzotriazole UV absorber and a hindered amine light stabilizer, By adding 0.05 to 3 parts by weight, preferably 0.05 to 2.5 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the material of the present invention, Light resistance is improved.

  Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2,2'-dihydroxy-4-methoxy-benzophenone, 2,2'-dihydroxy-4,4 '. -Dimethoxy benzophenone, 2-hydroxy-4-n-octoxy benzophenone, 2,2 ', 4,4'-tetrahydroxy benzophenone, 4-dodecyloxy-2-hydroxy benzophenone, 3,5-di-t- Butyl-4-hydroxybenzoyl acid, n-hexadecyl ester, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxyphenoxy) butane, 1, 6-bis (4-benzoyl-3-hydroxyphenoxy) hexa And the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl-phenyl) benzo Triazole, 2- (2′-hydroxy-3′-t-butyl-5′-methyl-phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t- Butyl-phenyl) -5-chloro-benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amyl) Phenyl) benzotriazole, 2- [2′-hydroxy-3 ′-(3 ′, 4 ′, 5 ′, 6′-tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotria 2-2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- [2-hydroxy-3, 5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2-hydroxy-4-octyloxyphenyl) -2H-benzotriazole, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) phenol and the like.

  Examples of hindered amine light stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) separate, bis (1,2,6,6,6-pentyl-4-piperidyl) separate, 1- [2- {3- (3,5-di-tert-butyl-4-hydroxydiphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxydiphenyl) ) Propionyloxy} -2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triasaspiro [4,5] decane- 2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) succinate) -4-hydroxy-2,2,6,6- Tetramethyl pipette Jin polycondensate thereof.

  Also, poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4 -Piperidyl) imino] hexamethylene [[2,2,6,6-tetramethyl-4-piperidyl] imino]], poly [6-morpholino-s-triazine-2,4-diyl] [(2,2, 6,6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6,6-tetramethyl-4-biperidyl) imino]], 2- (3,5-di-tert-butyl- 4-Hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), tetraxy (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tet Laxi (1,2,2,6,6, -pentamethyl-4-piperidyl) 1,2,3,4, -butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1,2 , 2,6,6-pentamethyl-4-piperidinol and a condensate of tridecyl alcohol.

  Furthermore, a condensate of 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and tridecyl alcohol, 1,2,3,4-butanetetracarboxylic Acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β, β-tetramethyl-3,9- (2,4,8,10-tetraoxaspiro [5,5] Undecane) condensate with diethanol, 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and β, β, β, β-tetramethyl-3,9 -Condensation with (2,4,8,10-tetraoxaspiro [5,5] undecane) diethanol, N, N'-bis (3-aminopropyl) ethylenediamine · 2,4-bis [N-butyl- N- (1,2,2,6,6-Pendame Tyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, dibutylamine, 1,3,5-triazine, N, N-bis (2,2,6,6-tetramethyl -4-pipericyl-1,6-hexamethylenediamine / N-2,2,6,6-tetramethy-4-piperidyl) butylamine polycondensate, 1,2,2,6,6-tetramethyl-4- Pipericyl-methacrylate, 2,2,6,6-tetramethyl-4-pipericyl-methacrylate and the like.

  In the material of the present invention, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate is used as a stabilizer. By adding 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight, a gel suppressing effect can be obtained. If the stabilizer is less than 0.05 parts by weight, there is no effect of suppressing the gel, and even if added over 3 parts by weight, it does not contribute to the gel suppression effect of the present invention or more.

  The materials of the present invention include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5 -Methylbenzyl) -4-methylphenyl acrylate, 2,4-bis [(octylthio) methyl] -o-cresol, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2,4-bis- (n-octylthio) -6 At least one phenolic stabilizer such as (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine is added in an amount of 0.05 to 100 parts by weight of the material of the present invention. 3 parts by weight, 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] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis] (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphine-6-yl] oxy] -ethyl] -ethanamine, tris (2,4-di-t-butyl At least one organic phosphate-based or organic phosphite-based stabilizer such as phenyl) phosphite can be added in an amount of 0.05 to 3 parts by weight based on 100 parts by weight of the material of the present invention. Thereby, the gel suppression effect can be obtained.

  Various additives can be added to the material of the present invention depending on the purpose. Suitable additives include softeners such as coumarone-indene resins, terpene resins, oils, and plasticizers. Various stabilizers, pigments, antiblocking agents, antistatic agents, lubricants and the like can also be added. Examples of the antiblocking agent, antistatic agent and lubricant include fatty acid amide, ethylene bis-stearamide, sorbitan monostearate, saturated fatty acid ester of fatty acid alcohol, pentaerythritol fatty acid ester, etc. -T-butylphenyl salicylate, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzo Triazole, 2,5-bis- [5′-t-butylbenzoxazolyl- (2)] thiophene, and the like, compounds described in “Practical Handbook for Additives for Plastics and Rubber” (Chemical Industry Co., Ltd.) can be used. . These are generally used in the range of 0.01 to 5% by weight, preferably 0.05 to 3% by weight.

[Heat shrinkable film]
The heat-shrinkable film of the present invention is a heat-shrinkable uniaxial or biaxially stretched film, and the material is changed from a normal T die or an annular die into a flat shape or a tube shape at 150 to 250 ° C, preferably 170 to 220 ° C. A method of extruding the obtained unstretched material substantially uniaxially or biaxially, or creating a raw sheet before stretching as a first inflation step, and in a fluid as a second inflation step It can be manufactured by a method of obtaining a heat-shrinkable film again by an inflation method.

  For example, in the case of uniaxial stretching, in the case of a film or sheet, it is stretched in the extrusion direction with a calendar roll or the like, or in a direction perpendicular to the extrusion direction with a tenter or the like, and in the case of a tube, in the extrusion direction or circumferential direction of the tube. Stretch. In the case of biaxial stretching, in the case of a film or sheet, the extruded film or sheet is stretched in the longitudinal direction with a metal roll or the like and then stretched in the transverse direction with a tenter or the like. The tubes are stretched simultaneously or separately in the circumferential direction of the tube, that is, in a direction perpendicular to the tube axis.

  In the present invention, the stretching temperature is 60 to 130 ° C., preferably 70 to 120 ° C., more preferably 80 to 110 ° C., and the stretching ratio is 1.5 to 8 times, preferably 2 to 6 in the machine direction and / or the transverse direction. It is preferable to stretch it twice. When the stretching temperature is less than 60 ° C., it is difficult to obtain a desired heat-shrinkable film by breaking at the time of stretching, and when it exceeds 130 ° C., it is difficult to obtain a product having good shrinkage characteristics. The draw ratio is selected within the above range so as to correspond to the shrinkage required by the application. However, when the draw ratio is less than 1.5 times, the heat shrinkage is small and is not preferable for heat shrink packaging. A draw ratio exceeding twice is not preferable for stable production in the drawing process. In the case of biaxial stretching, the stretching ratios in the longitudinal direction and the transverse direction may be the same or different. The uniaxially stretched or biaxially stretched heat-shrinkable film is then subjected to heat treatment at 60 to 160 ° C., preferably 80 to 155 ° C. for a short time, for example, 3 to 60 seconds, preferably 10 to 40 seconds. It is also possible to implement means to prevent natural contraction below.

  In order to use the heat-shrinkable film thus obtained as a heat-shrinkable packaging material or a heat-shrinkable label material, the heat shrinkage rate at 80 ° C. in the stretching direction is 5 to 80%, preferably 10 It is -75%, More preferably, it is 15-70%. When the heat shrinkage ratio is within such a range, a heat shrinkable film having an excellent balance between the heat shrinkage ratio and the natural shrinkage ratio can be obtained. In the present invention, the heat shrinkage rate at 80 ° C. is a measure of low temperature shrinkage, and a uniaxially stretched film or a biaxially stretched film is a heat medium that does not impair the characteristics of molded products such as 80 ° C. hot water, silicone oil, and glycerin. It is the thermal shrinkage rate in each stretching direction of the molded product when immersed in the interior for 10 seconds. In the present invention, it is recommended that the natural shrinkage ratio of the heat-shrinkable film itself is 2.5% or less, preferably 2.0% or less, more preferably 1.5% or less, within the range of the heat shrinkage rate. Is done. Here, the natural shrinkage rate of the heat-shrinkable film itself is a value calculated by an equation described later after leaving a heat-shrinkable film in the range of the heat shrinkage rate at 35 ° C. for 5 days.

  Furthermore, the uniaxially stretched or biaxially stretched film of the present invention needs to have a tensile elastic modulus in the stretching direction of 700 to 3000 MPa, preferably 1000 to 2500 MPa as a heat shrink wrapping material. When the tensile elastic modulus in the stretching direction is less than 700 MPa, the shrink wrapping process is not preferable because normal packaging cannot be performed, and when it exceeds 3000 MPa, the impact resistance of the film is lowered.

  When the uniaxially stretched or biaxially stretched film of the present invention is used as a heat-shrinkable packaging material, a temperature of 130 to 300 ° C., preferably 150 to 250 ° C., is used for several seconds to several minutes in order to achieve the desired heat shrinkage rate. Preferably, the heat shrinkage can be performed by heating for 1 to 60 seconds.

  The heat-shrinkable film of the present invention may be a multilayer laminate having at least two layers, preferably at least three layers. Specific examples of the usage form as the multilayer laminate include those disclosed in Japanese Patent Publication No. 3-5306. The heat shrinkable film of the present invention preferably has a heat shrinkage rate of 80 ° C. in the stretching direction of 10 to 80%. When the heat shrinkage is within this range, a heat shrinkable film excellent in the balance between the heat shrinkage and the natural shrinkage can be obtained.

  The heat-shrinkable film of the present invention may be used for the intermediate layer or both outer layers. When the heat-shrinkable film of the present invention is used for a multilayer film, the layers other than the film layer using the heat-shrinkable film of the present invention are not particularly limited, and the heat-shrinkable film of the present invention having different constituent components and compositions. Or the multilayer laminated body which combined the heat-shrinkable film other than this invention may be sufficient. When the heat-shrinkable film of the present invention is used as the middle layer, the Vicat softening temperature of the outer layer film is 3 to 15 ° C., preferably 5 to 12 ° C. higher than that of the middle layer.

  The thickness of the heat-shrinkable film and heat-shrinkable multilayer film of the present invention is 10 to 300 μm, preferably 20 to 200 μm, more preferably 30 to 100 μm, and the ratio of the thicknesses of both surface layers and inner layers of the multilayer film is 5/95. It is recommended to be ~ 45/55, preferably 10/90 to 35/65.

  The heat-shrinkable film of the present invention can be used for various uses such as packaging of fresh foods, confectionery, clothing, stationery, etc. by making use of the characteristics. As a particularly preferred application, letters and designs are printed on a uniaxially stretched film of a block copolymer defined in the present invention, and then the surface of a packaged object such as a plastic molded product, a metal product, a glass container, or a porcelain is thermally contracted. It can be used as a material for so-called heat-shrinkable labels that are used in close contact.

  In particular, since the heat-shrinkable film of the present invention is excellent in rigidity and low-temperature elongation, in addition to the heat-shrinkable label material of a plastic molded product that is deformed when heated to a high temperature, the coefficient of thermal expansion, water absorption, etc. Material very different from block copolymer, for example, polyolefin resin such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene, polyester such as polymethacrylate resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate It can be suitably used as a heat-shrinkable label material for a container using at least one selected from a base resin and a polyamide resin as a constituent material. The material constituting the plastic container in which the heat-shrinkable film of the present invention can be used is polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile in addition to the above resins. Copolymer, Styrene-maleic anhydride copolymer, Acrylonitrile-butadiene-styrene copolymer (ABS), Methacrylate-butadiene-styrene copolymer (MBS), Polyvinyl chloride resin, Polyvinyl chloride resin , Phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin and the like. These plastic containers may be a mixture of two or more resins or a laminate.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited by the following examples. In addition, the measured value and evaluation which are shown to an Example were performed with the following method.
(1) Dynamic viscoelasticity: Using a viscoelasticity measuring / analyzing apparatus DVE-V4 manufactured by BM Co., Ltd., a test piece having a thickness of about 1 mm obtained by compression-molding pellets with a hot press, a vibration frequency of 35 Hz and a temperature rising rate of 3 ° C. The temperature range of −50 ° C. to 150 ° C. is measured under the conditions of / min, and the storage elastic modulus (E ′) at 50 ° C., the storage elastic modulus (E-50) at −50 ° C., and the storage elastic modulus at 25 ° C. ) And the peak temperature of the loss modulus (E ″).
(2) Hydrogenation rate: Measured with a nuclear magnetic resonance apparatus (device name: DPX-400; manufactured by BRUKER, Germany) using a block copolymer hydrogenated product.
(3) Tensile modulus (standard stiffness): A test piece was cut out from a stretched film into a strip shape having a width of 10 mm in the MD and TD directions and a gap of 100 mm between the marked lines. The measurement temperature was 23 ° C., the tensile speed was 10 mm / min, and the tensile modulus was obtained by a conventional method. In addition, the average value of MD and TD direction was made into the value of the tensile elasticity modulus.
(4) Elongation at −5 ° C. The test piece was cut out in a strip shape from the stretched film to a length of 15 mm in the MD direction and 40 mm between the marked lines. The measurement temperature was −5 ° C. and the tensile speed was 100 mm / min.
(5) 80 ° C. shrinkage rate: The stretched film (TD direction) was immersed in 80 ° C. warm water for 10 seconds, and calculated according to the following formula.

80 ° C. thermal shrinkage (%) = (L−L1) / L × 100
Here, L indicates the length before contraction, and L1 indicates the length after contraction.
(6) Natural shrinkage rate This is a value calculated by the following equation after allowing the stretched film (TD direction) to stand at 35 ° C. for 5 days.

Natural shrinkage (%) = (L2−L3) / L2 × 100
Here, L2 indicates the length before being left, and L3 indicates the length after being left. The smaller the natural shrinkage rate, the better the natural shrinkage.
(7) Vicat softening temperature (VSP)
This is a value measured according to ASTM D-1525 (load: 1 Kg, temperature increase rate: 2 ° C./min) using a compression-molded material with a thickness of 3 mm as a test piece.
(8) Solvent resistance Methyl ethyl ketone / isopropyl alcohol (ratio 45/55) is applied to a stretched film or sheet 15 cm in MD × 15 cm in TD with a brush and dried at 30 ° C. for 7 days. Judgment was made by the retention of elongation in the MD direction. The test piece was cut out in a strip shape from the stretched film to a length of 15 mm in the MD direction and 40 mm between the marked lines. The tensile speed was 200 mm / min.

<Criteria>
○: Retention rate of 60% or more ×: Retention rate of less than 60% In this example, first, the block copolymers shown in Table 1 or hydrogenated products A-1 to A-7 thereof are shown in Table 4 as component (I). And component (III). Next, the polyolefin polymers B-1 to B-3 shown in Table 2 were used as the component (II) shown in Table 4, and styrene-n-butyl acrylate copolymers C-1 and C-2 shown in Table 3 were used. Polystyrene C-3 and C-4 were used as component (III) shown in Table 4.

<Examples 1-5 and Comparative Examples 1-3>
According to the formulation shown in Table 4, using a 40 mm extruder, it was molded into a sheet having a thickness of 0.25 mm at 200 ° C., and then the stretching temperature was 85 ° C., and the stretching ratio was increased to 5 times on the horizontal axis using a tenter. The film was uniaxially stretched to obtain a heat-shrinkable film having a thickness of about 50 μm. Table 4 shows the film performance of this heat-shrinkable film. The performance of the heat shrinkable film of the present invention is excellent in rigidity represented by tensile modulus, low temperature shrinkage represented by 80 ° C. shrinkage, natural shrinkage, −5 ° C. elongation, and solvent resistance. I understand.
<Example 6>
A three-layer sheet having the materials shown in Table 5 as an intermediate layer and front and back layers was extruded from a T-die, stretched 1.2 times in the longitudinal direction, and formed into a sheet having a thickness of 0.25 mm. Subsequently, the film was stretched 5 times in the transverse direction by a tenter to obtain a heat-shrinkable film having a thickness of 60 μm. The thickness ratio (%) between the middle layer and the surface layer / back layer was 15 (surface layer) / 70 (middle layer) / 15 (back layer). The performance of the obtained three-layer heat-shrinkable film is shown in Table 5. In addition, 0.2 parts by weight of ADK STAB LA-32 (manufactured by Asahi Denka Kogyo Co., Ltd.) with respect to 100 parts by weight of the front and back layer material as an ultraviolet absorber, and stearamide as a lubricant with respect to 100 parts by weight of the material of the front and back layers 0.2 part by weight was added. Table 5 shows the measurement results.

  The heat-shrinkable film of the present invention has a good balance of physical properties such as rigidity, low-temperature elongation, low-temperature shrinkage and solvent resistance, and is particularly excellent in rigidity, low-temperature elongation and solvent resistance. It can be suitably used for beverage container packaging, cap seals and various labels.

Claims (11)

A block copolymer having a vinyl aromatic hydrocarbon content of 65 to 95% by weight and a conjugated diene content of 5 to 35% by weight or a hydrogenated product thereof (I) and a polyolefin polymer (II) A material comprising a composition having a weight ratio of 99.9 / 0.1 to 50/50,
When the storage elastic modulus (E ′) at 50 ° C. is in the range of 0.9 × 10 ^{9 to} 1.8 × 10 ⁹ Pa, the storage elastic modulus (E-50) at −50 ° C. and the storage elastic modulus at 25 ° C. (E25 ) Ratio (E-50 / E25) is in the range of 1 to 1.75 and the loss elastic modulus (E ″) has a peak temperature of 60 ° C. or higher and 110 ° C. or lower. Heat shrinkable film. The composition further contains at least one polymer (III) of the following (i) to (iv), and the content of the polymer (III) in the composition is 0.1 to 80% by weight. The heat-shrinkable film according to claim 1.
(I) Block copolymer comprising vinyl aromatic hydrocarbon and conjugated diene not containing component (I) or hydrogenated product thereof (ii) Copolymer comprising vinyl aromatic hydrocarbon and aliphatic unsaturated carboxylic acid derivative Combined (iii) Vinyl aromatic hydrocarbon polymer (iv) Rubber modified styrene polymer The heat-shrinkable film according to claim 1 or 2, wherein the storage elastic modulus (E ') at 50 ° C of the material is in the range of 1.0 x 10 ^{9 to} 1.65 x 10 ⁹ Pa.   The ratio (E-50 / E25) of the storage elastic modulus (E-50) at -50 ° C and the storage elastic modulus (E25) at 25 ° C of the material is in the range of 1 to 1.6. The heat-shrinkable film according to any one of the above.   The heat-shrinkable film according to any one of claims 1 to 4, wherein at least one peak temperature of loss modulus (E ") of the material is 75 ° C or higher and 105 ° C or lower.   The material according to any one of claims 1 to 5, wherein the material contains 0.01 to 5 parts by weight of at least one lubricant selected from fatty acid amide, paraffin, hydrocarbon-based resin and fatty acid with respect to 100 parts by weight of the material. The heat-shrinkable film described in 1.   The material is 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, based on 100 parts by weight of the material. At least one selected from -t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 2,4-bis [(octylthio) methyl] -o-cresol The heat-shrinkable film according to any one of claims 1 to 5, comprising 0.05 to 3 parts by weight of a seed stabilizer.   The material contains at least one ultraviolet absorber or light stabilizer selected from a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer in an amount of 0.1 part by weight based on 100 parts by weight of the material. The heat-shrinkable film according to any one of claims 1 to 5, comprising 05 to 3 parts by weight.   A heat-shrinkable multilayer film comprising the heat-shrinkable film according to claim 1 as at least one layer.   The heat-shrinkable multilayer film according to claim 9, wherein the heat shrinkage rate at 80 ° C. in the stretching direction is 10 to 80%.   A heat-shrinkable multilayer film having the heat-shrinkable film according to any one of claims 1 to 8 as an intermediate layer and an outer layer having a Vicat softening temperature 3 to 15 ° C higher than that of the intermediate layer.