JP4938310B2 - Heat-shrinkable film comprising a polymer composition - Google Patents

Description

  The present invention relates to a heat-shrinkable film and a heat-shrinkable multilayer film that are particularly excellent in heat resistance, rigidity, and low-temperature shrinkability, and excellent in balance of physical properties such as transparency and impact 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.
In recent years, the demand for hot beverage PET bottles has increased, and the use in vending machines and hot warmers has increased. Heat resistance is also required for heat-shrinkable films.
The following is known as a conventional technique using a styrenic polymer having a syndiotactic structure in a heat-shrinkable film corresponding to the above-described PET bottle for hot beverages.

For example, Patent Document 1 below discloses a stretched polystyrene film containing syndiotactic polystyrene. Patent Document 2 below discloses a heat shrinkable film obtained by stretching a resin composition having a syndiotactic structure. Patent Document 3 below describes a method for producing a syndiotactic biaxially stretched film. Patent Document 4 and Patent Document 5 listed below disclose a heat-shrinkable film made of a styrene resin having a syndiotactic structure.
However, in the current situation, the techniques described in these documents do not sufficiently satisfy shrinkage characteristics, rigidity, heat resistance and transparency.
The present invention relates to a heat-shrinkable film having an excellent balance of heat resistance, low-temperature shrinkage characteristics, rigidity, transparency and the like based on the above situation.
Japanese Patent Laid-Open No. 7-020785 Japanese Patent Laid-Open No. 7-032468 JP-A-6-087158 JP 2003-94575 A JP 2003-25436 A

  An object of the present invention is to provide a heat-shrinkable film and a heat-shrinkable multilayer film that have improved heat resistance and low-temperature shrinkability and are excellent in physical properties such as rigidity, transparency, and impact resistance.

As a result of intensive studies, the present inventors have found that the above-described object can be achieved by alloying a specific copolymer, resulting in the present invention. That is, the present invention is as follows.
(1) The weight ratio of vinyl aromatic hydrocarbon units to conjugated diene units is 60/40 to 95/5, the number average molecular weight is 30,000 to 800,000 by gel permeation chromatography (GPC) measurement, and vinyl aromatic At least one vinyl aromatic hydrocarbon polymer block having a block ratio of hydrocarbon units of 10 to 95% by weight and a peak molecular weight in the molecular weight range of 5000 to 30000 is incorporated, and the vinyl aromatic hydrocarbon polymer A copolymer and / or a hydrogenated product (I) thereof, wherein 40 to 95% by weight of the block has a molecular weight of 35,000 or less;
Styrene polymer having a syndiotactic structure (II)
A heat-shrinkable film having a weight ratio of component (I) to component (II) in the range of 99.9 / 0.1 to 20/80.
(2) The (1) wherein at least one vinyl aromatic hydrocarbon polymer block having a peak molecular weight in the molecular weight range of 8000 to 27000 is incorporated in the copolymer and / or hydrogenated product (I) thereof. The heat-shrinkable film described.
(3) The vinyl aromatic hydrocarbon unit and the conjugated diene unit have a weight ratio of 60/40 to 95/5, and a number average molecular weight of 30,000 to 800,000 as measured by gel permeation chromatography (GPC). At least one vinyl aromatic hydrocarbon polymer block having a block ratio of hydrocarbon units of 10 to 95% by weight and a peak molecular weight in the molecular weight range of 5000 to 30000 is incorporated, and the vinyl aromatic hydrocarbon polymer Copolymer and / or hydrogenated product (I) thereof, styrenic polymer (II) having a syndiotactic structure, and vinyl aromatic hydrocarbon and butadiene, wherein 40 to 95% by weight of the block has a molecular weight of 35,000 or less And a block copolymer (III) comprising isoprene, and the vinyl aromatic carbon of the block copolymer (III) The hydrogen content is 50 to 85% by weight, the isoprene content is 1 to 25% by weight, the number average molecular weight is 50,000 to 500,000 as measured by gel permeation chromatography (GPC), and the block ratio of vinyl aromatic hydrocarbons Is 50 to 95% by weight, 40 to 95% by weight of the vinyl aromatic hydrocarbon polymer block in the block copolymer has a molecular weight of 35,000 or more, and the sum of component (I), component (II) and component (III) Isoprene content in the heat-shrinkable film comprising the component (I), the component (II), and the component (III) in a weight ratio of 5 to 50/1 to 50/10 to 60 with respect to 100 Is a heat-shrinkable film characterized by being 1 to 20% by weight.
(4) The heat-shrinkable film according to any one of 1 to 3 above, wherein the storage elastic modulus at 70 ° C. in the viscoelasticity measurement of the heat-shrinkable film is 1 × 10 ⁹ Pa or less.
(5) The styrenic resin (II) having a syndiotactic structure is at least one selected from the group consisting of styrene, alkyl styrene, halogenated styrene, halogenated alkyl styrene, alkoxy styrene, and vinyl benzoate. The heat-shrinkable film according to any one of (1) to (3), wherein the heat-shrinkable film is a copolymer with a styrene derivative, and a weight ratio of the styrene unit to the styrene derivative unit is 99/1 to 50/50.
(6) The heat-shrinkable film according to any one of (1) to (3), which has a melting peak at 200 to 270 ° C. in DSC measurement of the heat-shrinkable film.
(7) The heat-shrinkable film according to any one of (1) to (3), which has a cold crystallization peak at 100 to 180 ° C. in DSC measurement of the heat-shrinkable film.
(8) 0.01 to 5 at least one lubricant selected from the group consisting of fatty acid amides, paraffins, hydrocarbon resins, and fatty acids with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film. The heat-shrinkable film according to any one of (1) to (3), which is contained in parts by weight.
(9) 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film -T-pentylphenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and 2,4-bis [(octylthio) methyl] The heat-shrinkable film according to any one of (1) to (3), containing 0.05 to 3 parts by weight of at least one stabilizer selected from the group consisting of -o-cresol.
(10) At least one selected from the group consisting of benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and hindered amine-based light stabilizers with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film. The heat-shrinkable film according to any one of (1) to (3), which contains 0.05 to 3 parts by weight of an ultraviolet absorber or a light stabilizer.
(11) A heat-shrinkable multilayer film having at least one layer comprising the heat-shrinkable film according to any one of (1) to (3).

Hereinafter, the present invention will be described in detail.
The copolymer of component (I) and / or the hydrogenated product thereof (hereinafter collectively referred to as copolymer (I)) used in the present invention is a vinyl aromatic hydrocarbon unit of the copolymer. The weight ratio is 60 to 95% by weight, preferably 70 to 94% by weight, and more preferably 80 to 93% by weight. The copolymer or the like (I) may be a block copolymer or a random copolymer. The vinyl aromatic hydrocarbon content in the hydrogenated product of the copolymer may be determined from the vinyl aromatic compound content in the copolymer before hydrogenation.
Among the copolymers (I) used in the present invention, the block ratio of vinyl aromatic hydrocarbon incorporated in the block copolymer is 10 to 95% by weight, preferably 15 to 90% by weight, more preferably An amount of 25 to 85% by weight is recommended for obtaining a heat-shrinkable film having excellent shrinkage characteristics and rigidity.
Copolymers and the like (I) used in the present invention, and block copolymers and / or hydrogenated products of the component (III) used in the present invention (hereinafter collectively referred to as copolymers and the like (III) The block ratio of the vinyl aromatic hydrocarbon incorporated in the copolymer is referred to as a method of oxidatively decomposing the copolymer before hydrogenation with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et al., J. Polym.ScI.1,429 (1946)), and the vinyl aromatic hydrocarbon polymer block component obtained by the method (however, the vinyl aromatic having an average degree of polymerization of about 30 or less). Group hydrocarbon polymer component is excluded), and the value obtained from the following equation.
Block ratio (% by weight) = (weight of vinyl aromatic hydrocarbon polymer block in copolymer / weight of all vinyl aromatic hydrocarbon units in copolymer) × 100

  In the present invention, the copolymer or the like (I) is incorporated with at least one vinyl aromatic hydrocarbon polymer block having a peak molecular weight in the range of 5000 to 30000, preferably 6000 to 28000, more preferably 8000 to 27000. A copolymer having 40 to 95% by weight, preferably 45 to 90% by weight, and more preferably 50 to 85% by weight of the vinyl aromatic hydrocarbon polymer block having a molecular weight of 35,000 or less, and / or a hydrogenated product thereof. It is recommended that By using such a copolymer and / or hydrogenated product thereof, a heat-shrinkable film having excellent shrinkage characteristics and heat resistance can be obtained. In the range satisfying these requirements, at least one vinyl aromatic hydrocarbon polymer block having a molecular weight of 35,000 or more, preferably in the range of 35,000 to 150,000, may be incorporated in the block copolymer. Good.

  The copolymer or the like (III) is a block copolymer having a vinyl aromatic hydrocarbon weight ratio of 50 to 85% by weight, preferably 55 to 80% by weight, and more preferably 60 to 75% by weight. The isoprene content of the copolymer or the like (III) is 1 to 25% by weight, preferably 3 to 22% by weight, more preferably 5 to 20% by weight. Of the copolymer (III) used in the present invention, the block ratio of the vinyl aromatic hydrocarbon incorporated in the block copolymer is 50 to 95% by weight, preferably 55 to 90% by weight, more preferably In order to obtain a heat-shrinkable film excellent in impact resistance and elongation properties, it is recommended that the block copolymer has a molecular weight of 35,000 or more.

The molecular weight of the copolymer (I) and the copolymer (III) used in the present invention is 30,000 to 800,000, preferably a number average molecular weight (polystyrene equivalent molecular weight) measured by gel permeation chromatography (GPC). Is in the range of 50,000 to 500,000, more preferably 70,000 to 300,000, and may be a mixture of a plurality of block copolymers having different molecular weights. The number average molecular weight is determined by gel permeation chromatography (GPC) using a standard curve prepared using a commercially available standard polystyrene having a known weight average molecular weight and number average molecular weight (eg, “gel chromatography <basic edition”). > ”Issued by Kodansha).
In the present invention, the molecular weight of the vinyl aromatic hydrocarbon polymer block incorporated in the copolymer etc. (I) and the copolymer etc. (III) is used for quantification of the block ratio obtained by the oxidative decomposition method described above. The same vinyl aromatic hydrocarbon polymer block component as that obtained was identified by gel permeation chromatography (GPC). The molecular weight is calculated according to a conventional method by preparing a calibration curve of the peak count number and the number average molecular weight of monodisperse polystyrene by GPC using monodisperse polystyrene for gel permeation chromatography (GPC). The peak molecular weight can be determined from the gel permeation chromatogram, and the proportion of the vinyl aromatic hydrocarbon polymer block component having a molecular weight of 35,000 or less can be determined from the area ratio of the gel permeation chromatogram. The molecular weight of the vinyl aromatic hydrocarbon block incorporated in the block copolymer or the like and the amount of the component having a molecular weight of 35,000 or less are the weight of the vinyl aromatic hydrocarbon unit, the weight of the vinyl aromatic hydrocarbon unit and the conjugated diene unit. In addition, it can be controlled by changing the weight ratio, the polymerization reactivity ratio, the catalyst amount, and the like.
A preferred melt flow index (measured according to JISK-6870. Conditions are G condition, temperature 200 ° C., load 5 Kg) is 0.1 to 100 g / 10 min from the viewpoint of molding processability. Preferably 0.5 to 50 g / 10 min, more preferably 1 to 30 g / 10 min is recommended. The molecular weight and the melt flow index can be arbitrarily adjusted depending on the amount of catalyst used for the polymerization.

In the present invention, the block copolymer before hydrogenation includes at least one segment composed of a vinyl aromatic hydrocarbon homopolymer and / or a copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene, and a conjugated diene. It has at least one segment composed of a homopolymer and / or a copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene. The polymer structure of the block copolymer is not particularly limited.
(A-B) _n , A- (B-A) _n , B- (A-B) _n
[(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 units and conjugated diene units, and segment B is a conjugated diene homopolymer and / or vinyl aromatic carbonization. X is a coupling agent such as silicon tetrachloride, tin tetrachloride, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, epoxidized soybean oil, etc. Or a residue of an initiator such as a polyfunctional organolithium compound, where n, k and m are each an integer of 1 or more, generally an integer of 1 to 5. In addition, multiple bonds to X The polymer chain structure may be the same or different.)
The linear block copolymer represented by these, a radial block copolymer, or arbitrary mixtures of these polymer structures can be used. 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 the vinyl aromatic hydrocarbon units are uniformly distributed and / or a portion where the vinyl aromatic hydrocarbon units are distributed in a tapered shape may coexist in the segment. Content of vinyl aromatic hydrocarbon unit in segment A ({vinyl aromatic hydrocarbon unit in segment A / (vinyl aromatic hydrocarbon unit in segment A + conjugated diene unit)} × 100) and in segment B The vinyl aromatic hydrocarbon unit content ({vinyl aromatic hydrocarbon unit in segment B / (vinyl aromatic hydrocarbon unit in segment B + conjugated diene unit)} × 100) is related to vinyl in segment A The aromatic hydrocarbon unit content is larger than the vinyl aromatic hydrocarbon unit content in segment B. The difference in the preferred vinyl aromatic hydrocarbon unit content between segment A and segment B is preferably 5% by weight or more.

In the present invention, the copolymer before hydrogenation 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 , 1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene and the like, and styrene is particularly common. These may be used alone or in combination of two or more.
The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene. 1,3-pentadiene, 1,3-hexadiene, etc., and particularly common examples include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.
In the present invention, the copolymer before hydrogenation is 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, 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, and suitable organic alkali metal compounds are aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, one per molecule. Examples thereof include compounds containing lithium, dilithium compounds containing a plurality of lithium atoms in one molecule, trilithium compounds, and tetralithium compounds. Specifically, n-propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium, diisopropenylbenzene and sec-butyl lithium In addition, a reaction product of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene can be used. 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 copolymer (I) and the copolymer (III) 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. Further, it is desirable to replace the polymerization atmosphere with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is within a range 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 copolymer used in the present invention can be obtained by hydrogenating the copolymer obtained above before hydrogenation. 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. 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) A homogeneous hydrogenation catalyst such as a so-called organometallic complex such as an organometallic compound such as Ti, Ru, 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.
Preferred hydrogenation catalysts include 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 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 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 heat-shrinkable film having good heat resistance, heat stability and weather resistance, it exceeds 70% of the unsaturated double bonds based on the conjugated diene compound in the copolymer, preferably 75% or more, more preferably It is recommended that 85% or more, particularly preferably 90% or more, be hydrogenated. Moreover, when obtaining a heat-shrinkable film with good thermal stability, the hydrogenation rate in the copolymer is from 3 to 70%, preferably from 5 to 65%, particularly preferably from 10 to 60%. The hydrogenation rate of the aromatic double bond based on the vinyl aromatic hydrocarbon in the copolymer is not particularly limited, but the hydrogenation rate is 50% or less, preferably 30% or less, more preferably 20%. Below. The hydrogenation rate can be known by a nuclear magnetic resonance apparatus (NMR).

In the present invention, the microstructure (cis, trans, vinyl ratio) of the conjugated diene moiety in the copolymer (I) and the copolymer (III) can be arbitrarily changed by using a polar compound or the like. There is no particular limitation. Generally, the vinyl bond amount can be set in the range of 5 to 90%, preferably 7 to 80%, more preferably 8 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).
In the present invention, when a heat-shrinkable film having particularly excellent heat resistance is obtained, a copolymer hydrogenated product is used, and more than 20 ° C. in the differential scanning calorimetry (DSC) chart of the copolymer hydrogenated product. A hydrogenated copolymer having a crystallization peak in a temperature range of preferably 30 ° C. or higher, more preferably 45 to 100 ° C., particularly preferably 50 to 90 ° C. is preferable. This crystallization peak heat quantity is 3 J / g or more, preferably 6 J / g or more, more preferably 10 J / g or more. The copolymer hydrogenated product having a crystallization peak has a vinyl bond content in the copolymer before hydrogenation of less than 30%, preferably 5 to 25%, more preferably 7 to 25%, and particularly preferably 8 to It can be obtained by setting to 20%. In particular, it is recommended that the copolymer before hydrogenation contains at least one conjugated diene polymer segment having a vinyl bond content of 5 to 25%, preferably 7 to 20%, more preferably 8 to 18%. The
In the present invention, the copolymer of component (III) or the hydrogenated product thereof has at least one tan δ peak temperature in the measurement of viscoelasticity in the range of −90 ° C. to 0 ° C., preferably −90 ° C. to −10 ° C. Having the above is recommended in terms of low temperature characteristics such as elongation at low temperature.

In the present invention, the styrenic resin having a syndiotactic structure of component (II) is a syndiotactic structure, that is, a phenyl group that is a side chain with respect to a main chain formed from a carbon-carbon bond. It has a three-dimensional structure located alternately in the opposite direction, and its tacticity is quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be represented by the abundance ratio of a plurality of consecutive structural units, for example, a dyad for two, a triad for three, a pentad for five. However, the styrenic resin having a syndiotactic structure referred to in the present invention is usually 75% or more of racemic dyad, preferably 85% or more, or 30% or more, preferably 50% or more of racemic pentad. Tacticity polystyrene, poly (alkyl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate), their hydrogenated polymers and these Or a copolymer based on these. Here, as poly (alkyl styrene), poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), poly (phenyl styrene), poly (vinyl naphthalene) And poly (vinyl styrene). Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Poly (halogenated alkylstyrene) includes poly (chloromethylstyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferred styrenic resins include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tertiarybutylstyrene), poly (p-chlorostyrene), poly (M-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene, and copolymers containing these structural units. Although there is no restriction | limiting in particular about this styrene-type resin, A weight average molecular weight is 10,000 or more, Preferably it is 50,000-100,000. Furthermore, the molecular weight distribution is not limited in its breadth and width, and various types can be used. Such a syndiotactic styrene-based resin can be prepared, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum in an inert hydrocarbon solvent or in the absence of a solvent as a catalyst. (Monomers corresponding to styrene-based resins) can be polymerized (Japanese Patent Laid-Open No. 62-187708). Poly (halogenated alkylstyrene) can be obtained by the method described in JP-A-1-46912, and these hydrogenated polymers can be obtained by the method described in JP-A-1-178505.

  A preferred form of the styrene resin having a syndiotactic structure is at least one selected from the group consisting of styrene, alkyl styrene, halogenated styrene, halogenated alkyl styrene, alkoxy styrene, and vinyl benzoate. It is a copolymer with a styrene derivative. Examples of the alkyl styrene include methyl styrene, ethyl styrene, isopropyl styrene, tertiary butyl styrene, phenyl styrene, vinyl naphthalene, and vinyl styrene. Examples of the halogenated styrene include chlorostyrene, bromostyrene, and fluorostyrene. Examples of the halogenated alkyl styrene include chloromethyl styrene. Examples of alkoxystyrene include methoxystyrene and ethoxystyrene. Of these, particularly preferred styrene derivatives include p-methylstyrene, m-methylstyrene, p-tertiary butylstyrene, p-chlorostyrene, m-chlorostyrene, and p-fluorostyrene. The proportion of styrene and styrene derivative in the copolymer of styrene and styrene derivative is 1 part by weight or more and less than 50 parts by weight, preferably 1 part by weight with respect to 100 parts by weight of the total amount of styrene and styrene derivative. It is recommended that the amount be not less than 30 parts by weight, more preferably not less than 3 parts by weight and not more than 25 parts by weight, particularly preferably not less than 5 parts by weight and not more than 20 parts by weight. Excellent in properties. Among these copolymers, a copolymer of styrene and alkylstyrene is particularly preferable. Moreover, the styrene resin which has a syndiotactic structure can be used individually by 1 type or in combination of 2 or more types.

In the present invention, 0.1 to 100 parts by weight of at least one selected from the following a) to c) is added to 100 parts by weight of the total amount of component (I), component (II) and component (III). be able to.
(A) Styrene polymer (however, different from the styrene resin of component (I))
(B) at least one aliphatic unsaturated carboxylic acid selected from the group consisting of an aliphatic unsaturated carboxylic acid, an aliphatic unsaturated carboxylic acid anhydride, and an aliphatic unsaturated carboxylic acid ester, or a derivative thereof; Copolymer with aromatic hydrocarbon (c) Rubber-modified styrene polymer (a) The styrene polymer that can be used in the present invention is the above-mentioned vinyl aromatic hydrocarbon or a monomer copolymerizable therewith. Obtained by polymerizing (except for (b)). Examples of the monomer copolymerizable with the vinyl aromatic hydrocarbon include acrylonitrile and methacrylonitrile. Examples of the styrene polymer include polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer, methacrylonitrile-styrene copolymer, and the like. In addition, among styrene polymers, polystyrene obtained by polymerizing styrene includes isotactic polystyrene. The weight average molecular weight of these styrenic polymers is generally 50,000 to 1,000,000, preferably 100,000 to 500,000. These styrenic polymers can be used alone or as a mixture of two or more, and can be used as a heat resistance improver.
Component (b) that can be used in the present invention is at least one fat selected from the group consisting of aliphatic unsaturated carboxylic acids, aliphatic unsaturated carboxylic acid anhydrides, and aliphatic unsaturated carboxylic acid esters. Aliphatic unsaturated carboxylic acids used in copolymers of aromatic unsaturated carboxylic acids or their derivatives and vinyl aromatic hydrocarbons include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, etc. Examples of the aliphatic unsaturated carboxylic acid anhydride include fumaric anhydride, itaconic anhydride, maleic anhydride and the like, and examples of the aliphatic unsaturated carboxylic acid ester include the above aliphatic unsaturated carboxylic acid and Examples thereof include mono- or diesters with C1-C12, preferably C2-C12 alcohols. The content of the aliphatic unsaturated carboxylic acid and / or aliphatic unsaturated carboxylic acid derivative in the component (b) is generally 5 to 50% by weight, preferably 8 to 30% by weight, more preferably 10 to 25% by weight. is there.
In addition, the manufacturing method of a component (b) can use the well-known method of manufacturing a styrene resin, for example, a block polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method etc. In general, a polymer having a weight average molecular weight of component (b) of 50,000 to 500,000 can be used.

The rubber-modified styrenic polymer of component (c) that can be used in the present invention is obtained by polymerizing a mixture of a monomer copolymerizable with the vinyl aromatic hydrocarbon and an elastomer. As the polymerization method, suspension polymerization, emulsion polymerization, bulk polymerization, bulk-suspension polymerization and the like are generally performed. Examples of vinyl aromatic hydrocarbons include styrene, α-methyl styrene, vinyl naphthalene, and examples of monomers copolymerizable with vinyl aromatic hydrocarbons include acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, and maleic anhydride. An acid etc. are mentioned. 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 dissolved in the monomer in an amount of 3 to 50 parts by weight or 100 parts by weight of a monomer that can be copolymerized with the vinyl aromatic hydrocarbon or in the form of latex, emulsion polymerization, bulk It is used for polymerization, bulk-suspension polymerization and the like. 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 composition constituting the heat-shrinkable film of the present invention includes a copolymer of component (I), a styrene resin having a syndiotactic structure of component (II), a copolymer of component (III), and the like. In terms of the balance between shrinkage characteristics and rigidity, the weight ratio based on the sum of component (I), component (II) and component (III) as 100 is preferably 5-50 / 1-50 / 10-60. Is 10 to 45/5 to 45/20 to 55, more preferably 10 to 40/10 to 40/30 to 55.
In addition, the composition constituting the heat-shrinkable film of the present invention has a storage elastic modulus value of 70 ° C. of 1 × 10 ⁹ Pa or less in the viscoelasticity measurement of the composition in terms of the balance between heat resistance and shrinkability. , Preferably 1 × 10 ⁸ Pa or less, more preferably 1 × 10 ⁷ Pa or less. When obtaining such a heat-shrinkable film, the Vicat softening temperature of the copolymer of component (I) is 60 to 80 ° C, preferably 63 to 77 ° C, more preferably 65 to 75 ° C, and particularly preferably 67 to 73 ° C. The peak temperature of tan δ in the dynamic viscoelasticity measurement is 75 to 115 ° C, 75 to 115 ° C, preferably 80 to 105 ° C, more preferably 85 to 100 ° C, and particularly preferably 90 to 95 ° C. It is in. When using at least one vinyl aromatic hydrocarbon polymer selected from the above-mentioned a) to c) in addition to component (I), component (II) and component (III), the vinyl aromatic The hydrocarbon-based polymer has a Vicat softening temperature in the range of 55 to 85 ° C., preferably 60 to 80 ° C., more preferably 63 to 77 ° C., particularly preferably 65 to 75 ° C., and tan δ in dynamic viscoelasticity measurement. The peak temperature is 65 to 115 ° C, 70 to 110 ° C, preferably 73 to 105 ° C, more preferably 75 to 100 ° C, and particularly preferably 90 to 95 ° C.
On the other hand, when obtaining a heat-shrinkable film having particularly good heat resistance, the DSC measurement of the heat-shrinkable film is 200 to 270 ° C., preferably 210 to 265 ° C., more preferably 220 to 260 ° C., and particularly preferably 230. It has a crystal melting peak at ˜255 ° C. From the viewpoint of heat resistance, it is recommended that this melting peak calorie is 1 J / g or more, preferably 2 J / g or more, more preferably 3 J / g or more, and particularly preferably 4 J / g or more. The peak heat quantity of the heat-shrinkable film is adjusted by adjusting the copolymerization ratio, tacticity of styrene and styrene derivative of component (III), and the blending ratio of component (I), component (II) and component (III). The amount of exothermic peak can be adjusted.
The heat-shrinkable film of the present invention is 100-180 ° C., preferably 105-175 ° C., more preferably 110-170 ° C., particularly preferably 115-165 ° C. in DSC measurement of the heat-shrinkable film. Has a peak.

In the composition used for the heat-shrinkable film of the present invention, at least one selected from the group consisting of fatty acid amides, paraffins and hydrocarbon resins, and fatty acids is used as a lubricant. Addition of 0.01 to 5 parts by weight, preferably 0.05 to 4 parts by weight, and more preferably 0.1 to 3 parts by weight improves blocking resistance.
Examples of fatty acid amides include stearoamide, oleylamide, erucylamide, behenamide, mono- or bisamide of higher fatty acids, ethylene bisstearamide, stearyl oleylamide, N-stearyl erucamide, but these may be used alone or in combination of two or more. Can be used. Examples of paraffin and hydrocarbon resins include paraffin wax, microcrystalline wax, liquid paraffin, paraffin synthetic wax, polyethylene wax, composite wax, montan wax, hydrocarbon wax, and silicone oil. The above can be mixed and used.
Examples of fatty acids include saturated fatty acids, unsaturated fatty acids, N-substituted fatty acids and the like. That is, saturated fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid, hydroxystearic acid, unsaturated fatty acids such as oleic acid, erucic acid, ricinoleic acid, N-stearyl stearic acid, N-oleyl oleic acid, N- Stearyl oleic acid, N-oleyl stearic acid, N-stearyl erucic acid, N-oleyl palmitic acid, methylol stearic acid, methylol behenic acid and other substituted fatty acids, methylene bis stearic acid, ethylene biscapric acid, ethylene bis lauric acid, ethylene Saturated fats such as bis stearic acid, ethylene bisisostearic acid, ethylene bishydroxystearic acid, ethylene bisbehenic acid, hexamethylene bishydroxystearic acid, N, N'-distearyl adipic acid, N, N'-distearyl sebacic acid Acid, ethylenebisoleic acid, hexamethylenebisoleic acid, N, N′-dioleyl adipic acid, unsaturated fatty acid such as N, N′-dioleyl sebacic acid, m-xylylene bisstearic acid, N, N ′ -Although there exists distearyl isophthalic acid etc., these can be used individually or in mixture of 2 or more types.

The composition used for the heat-shrinkable film of the present invention has at least one selected from the group consisting of a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer as the ultraviolet absorber and light stabilizer. The seed ultraviolet absorber and light stabilizer are added in an amount of 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 copolymer. By adding a part, light resistance is improved.
Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone. 2-hydroxy-4-n-octoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 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) hexane 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-chlorobenzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) Benzotriazole, 2- [2′-hydroxy-3 ′-(3 ′, 4 ′, 5 ′, 6′-tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2-2′-methylenebis [4- ( , 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) propionyl Oxy} -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-hydroxyethylene) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate Emissions 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-piperidyl) imino]], 2- (3,5-ditert-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, Traxyl (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-pender 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-piperyl-methacrylate 2,2,6,6-tetramethyl-4-piperyl-methacrylate and the like.

The composition used for the heat-shrinkable film of the present invention contains 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t- as a stabilizer. Pentylphenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and 2,4-bis [(octylthio) methyl] -o- 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 of a copolymer or the like, at least one selected from the group consisting of cresol has a gel suppressing effect. Obtainable. 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 composition used for the heat-shrinkable film of the present invention includes 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- At least one phenolic stabilizer such as bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine is used as a copolymer or the like 1 0.05 to 3 parts by weight relative to 0 part 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] dioxaphosphin-6-yl] oxy] -ethyl] -ethanamine, 0.05 to 3 weight percent of at least one organic phosphate-based or organic phosphite-based stabilizer such as tris (2,4-di-t-butylphenyl) phosphite with respect to 100 weight parts of copolymer or the like. Part can be added .
Various polymers and additives can be added to the composition used for the heat-shrinkable film of the present invention depending on the purpose. As a suitable polymer, a block copolymer elastomer of vinyl aromatic hydrocarbon and conjugated diene or a hydrogenated product thereof, or a block copolymer of vinyl aromatic hydrocarbon and conjugated diene different from the block copolymer used in the present invention are used. Polymer resin or hydrogenated product thereof.

In the present invention, the block copolymer elastomer of vinyl aromatic hydrocarbon and conjugated diene or its hydrogenated product has a vinyl aromatic hydrocarbon unit content of less than 60% by weight, preferably 10 to 50% by weight. Those having the same structure as the block copolymer can be used, and by blending 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the copolymer or the like used in the present invention. Impact resistance and elongation can be improved.
In the hydrogenated block copolymer elastomer, 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. 70% or more, preferably 80% or more, more preferably 90% or more of the unsaturated double bonds based on the conjugated diene in the block copolymer elastomer may be hydrogenated, or only a part thereof is hydrogenated. It may be. When only a part is hydrogenated, the hydrogenation rate is preferably 10% or more and less than 70%, or 15% or more and less than 65%, and if desired, 20% or more and less than 60%.
In the present invention, various agents can be used for the purpose of increasing the crystallinity of the polystyrene resin having a syndiotactic structure or controlling the crystal diameter. These nucleating agents include metal salts of carboxylic acids including aluminum di (pt-butylbenzoate), and metal salts of phosphoric acid including sodium methylenebis (2,4-di-tert-butylphenol) acid phosphate. , Talc, phthalocyanine derivatives, etc., can be arbitrarily selected from known ones. In addition, these nucleating agents can be used individually by 1 type or in combination of 2 or more types.
Other 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. In addition, as an antiblocking agent, an antistatic agent, and a lubricant, for example, fatty acid amide, ethylenebisstearamide, sorbitan monostearate, saturated fatty acid ester of fatty acid alcohol, pentaerythritol fatty acid ester, etc., and as an ultraviolet absorber P-t-butylphenyl salicylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5 -Chlorobenzotriazole, 2,5-bis- [5'-t-butylbenzoxazolyl- (2)] thiophene, etc., 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 in the composition used in the present invention.

The heat-shrinkable film of the present invention is obtained by extruding the above composition from a normal T die or a ring die into a flat shape or a tube shape at 180 to 270 ° C., preferably 200 to 260 ° C. Is substantially uniaxially stretched or biaxially stretched to obtain a heat-shrinkable uniaxially or biaxially stretched film.
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 70 to 130 ° C., preferably 75 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. Stretched twice. When the stretching temperature is less than 70 ° 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 or biaxially stretched heat-shrinkable film is then subjected to a heat treatment at 90 to 160 ° C., preferably 100 to 155 ° C. for a short time, for example 3 to 60 seconds, preferably 10 to 40 seconds, if necessary. 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 70%, preferably 10 -60%, more preferably 15-50%. 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 or biaxially stretched film is a heat medium that does not hinder the properties of molded products such as 80 ° C. hot water, silicone oil, glycerin, etc. 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 rate 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. The Here, the natural shrinkage ratio of the heat shrinkable film itself is a value calculated by an equation described later after leaving the heat shrinkable film in the range of the above heat shrinkage ratio at 35 ° C. for 5 days.
Additionally, uniaxial stretching or biaxial oriented film of the present invention, tensile modulus 7000~35000Kg / cm ² in the stretching direction, preferably 7500~30000Kg / cm ^2, more preferably 8000~25000Kg / cm ^2, particularly preferably Is recommended for heat shrink wrapping materials to be 9000-20000 Kg / cm ² . When the tensile elastic modulus in the stretching direction is less than 7000 Kg / cm ² , it is not preferable because it causes settling in the shrink wrapping process and normal packaging cannot be performed, and when it exceeds 35000 Kg / cm ² , the impact resistance of the film decreases, which is not preferable.
When the heat-shrinkable 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., for several seconds to several minutes, preferably 1 in order to achieve the desired heat shrinkage rate. Heat shrink for ~ 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. You may use the composition which comprises the heat-shrinkable film of this invention for an intermediate | middle layer and both outer layers. When the block copolymer or the like of the present invention or the block copolymer composition is used for a multilayer film, the layers other than the film layer using the composition constituting the heat-shrinkable film of the present invention are not particularly limited. A composition defined in the present invention having different components and compositions, or a block copolymer other than the present invention or a block copolymer other than the present invention and a composition of the above-mentioned vinyl aromatic hydrocarbon polymer. It may be a multilayer laminate. In addition, polypropylene, polyethylene, ethylene polymer (ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, etc.), ionomer resin, nylon resin, polyester resin, poly Examples include at least one component selected from methyl methacrylate resin, ABS resin, the above-mentioned vinyl aromatic hydrocarbon polymer, and the like. Preferably, the block copolymer other than the present invention or the block copolymer other than the present invention is used. A composition of a coalescence and the vinyl aromatic hydrocarbon polymer, and the vinyl aromatic hydrocarbon polymer.
In the heat-shrinkable multilayer film preferred in the present invention, the layer comprising the heat-shrinkable film of the present invention is at least one layer of the multilayer film, and the heat shrinkage rate at 50 ° C. in the stretching direction is 5 to 70%, preferably 10 It is a heat-shrinkable multilayer film which is -60%, more preferably 15-50%.

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 thickness ratio between the inner layer and both surface layers is 5/95 to 45. / 55, preferably 10/90 to 35/65 is recommended.
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 uniaxially stretched heat-shrinkable film of the present invention is particularly excellent in heat resistance and low-temperature shrinkability, it may be deformed when heated to a high temperature in addition to a heat-shrinkable label of a plastic molded product used under high-temperature conditions. Heat-shrinkable label material of plastic molded articles, materials with extremely different coefficients of thermal expansion and water absorption from the block copolymer of the present invention, for example, polyolefins such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene Shrinkage of containers using at least one selected from polyester resins, polyamide resins, such as polyester resins, polymethacrylate resins, polycarbonate resins, polyethylene terephthalate, polybutylene terephthalate, etc. It can be suitably used as a label 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.
When the heat-shrinkable film of the present invention is used as a heat-shrinkable label material, the heat shrinkage rate at 80 ° C. in the direction orthogonal to the stretching direction is less than 20%, preferably less than 10%, more preferably 5%. Is less than.

A. Preparation of component (I) a. Copolymer A-1
Copolymer A-1 having a styrene content of 90% by weight was prepared by the following method.
After adding 0.3 parts by weight of tetramethylethylenediamine and 0.045 parts by weight of n-butyllithium to 100 parts by weight of all the monomers used, a temperature inside the polymerizer was adjusted to about 70 ° C. . Next, a cyclohexane solution (monomer concentration 20% by weight) containing 82 parts by weight of styrene and 10 parts by weight of butadiene was continuously added for polymerization for 80 minutes. Further, a cyclohexane solution (monomer concentration 20% by weight) containing 8 parts by weight of styrene was continuously added over 10 minutes for polymerization. During this time, the temperature in the polymerization vessel was adjusted to about 70 ° C., and then methanol was added to the polymerization vessel at a 1.0-fold molar ratio with respect to n-butyllithium to stop the polymerization, and 2- [1- ( 2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate was added in an amount of 0.6 part by weight to 100 parts by weight of the block copolymer composition. Thereafter, the solvent was removed to obtain a copolymer A-1.
b. Copolymer A-2
Copolymer A-1 having a styrene content of 85% by weight was prepared by the following method.
After adding 0.3 parts by weight of tetramethylethylenediamine and 0.043 parts by weight of n-butyllithium to 100 parts by weight of all monomers used, the temperature inside the polymerizer is adjusted to about 70 ° C. did. Next, a cyclohexane solution (monomer concentration: 20% by weight) containing 77 parts by weight of styrene and 15 parts by weight of butadiene was continuously added over 80 minutes for polymerization. Further, a cyclohexane solution (monomer concentration 20% by weight) containing 8 parts by weight of styrene was continuously added over 10 minutes for polymerization. During this time, the temperature in the polymerization vessel was adjusted to about 70 ° C., and then methanol was added to the polymerization vessel at a 1.0-fold molar ratio with respect to n-butyllithium to stop the polymerization, and 2- [1- ( 2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate was added in an amount of 0.6 part by weight to 100 parts by weight of the block copolymer composition. Thereafter, the solvent was removed to obtain a copolymer A-2.
c. Copolymer A-3
Copolymer A-3 having a styrene content of 90% by weight was prepared by the following method.
After adding 0.3 parts by weight of tetramethylethylenediamine and 0.043 parts by weight of n-butyllithium to 100 parts by weight of all monomers used, the temperature inside the polymerizer was adjusted to about 70 ° C. . Next, a cyclohexane solution (monomer concentration 20% by weight) containing 82 parts by weight of styrene and 10 parts by weight of butadiene was continuously added over 75 minutes for polymerization. Further, a cyclohexane solution (monomer concentration 20% by weight) containing 8 parts by weight of styrene was continuously added over 10 minutes for polymerization. During this time, the temperature in the polymerization vessel was adjusted to about 70 ° C., and then methanol was added to the polymerization vessel at a 1.0-fold molar ratio with respect to n-butyllithium to stop the polymerization, and 2- [1- ( 2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate was added in an amount of 0.6 part by weight to 100 parts by weight of the block copolymer composition. Thereafter, the solvent was removed to obtain a copolymer A-3.

d. Reference example: Copolymer A′-4
Copolymer A′-4 having a styrene content of 80% by weight was prepared by the following method.
After adding 0.3 parts by weight of tetramethylethylenediamine and 0.045 parts by weight of n-butyllithium to 100 parts by weight of all the monomers used, a temperature inside the polymerizer was adjusted to about 70 ° C. . Next, a cyclohexane solution (monomer concentration 20% by weight) containing 30 parts by weight of styrene and 20 parts by weight of butadiene was continuously added for polymerization for 50 minutes. Further, a cyclohexane solution containing 50 parts by weight of styrene (monomer concentration: 20% by weight) was continuously added over 10 minutes for polymerization. During this time, the temperature in the polymerization vessel was adjusted to about 70 ° C., and then methanol was added to the polymerization vessel at a 1.0-fold molar ratio with respect to n-butyllithium to stop the polymerization, and 2- [1- ( 2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate was added in an amount of 0.6 part by weight to 100 parts by weight of the block copolymer composition. Thereafter, the solvent was removed to obtain a copolymer A′-4.
d. Reference example: Copolymer A′-5
Copolymer A′-5 having a styrene content of 77% by weight was prepared by the following method.
A cyclohexane solution containing 32 parts by weight of styrene (monomer concentration: 20% by weight) is added to a polymerization vessel equipped with a stirrer and heated to about 70 ° C., and 0.065 parts of n-butyllithium is added to 100 parts by weight of all monomers used. And polymerized at about 70 ° C. for 1 hour. Next, a cyclohexane solution containing 20 parts by weight of styrene, 11 parts by weight of 1,3-butadiene and 12 parts by weight of isoprene (monomer concentration: 20% by weight) was continuously added over 1 hour and polymerized at about 70 ° C. for 1 hour. . Thereafter, a cyclohexane solution (monomer concentration 20% by weight) containing 25 parts by weight of styrene was further added, and polymerization was carried out at about 70 ° C. for 1 hour.
The composition of component (I) is shown in Table 1.

B. Preparation of component (II) a. Preparation of Styrene Resin B-1 Styrene resin B-1 having a syndiotactic structure was prepared by the following method.
In a well-dried and nitrogen-substituted container, put toluene, triisobutylaluminum 3.8 mmol, methylaluminoxane 16.8 mmol, and octahydrofluorenyltitanium trimethoxide 0.15 mmol so that the Ti concentration is 3 mmol / l. Prepared. After mixing each component, it stirred for 1 hour and used as a catalyst.
Also, 4.3 liters of styrene, 0.7 liters of paramethylstyrene, and triethylaluminum are put in a molar ratio of styrene / triethylaluminum = 3500/1 in a well-dried and nitrogen-reacted reactor and stirred sufficiently. did. After heating the mixture of styrene and triethylaluminum to 78 ° C., 21 ml of the catalyst prepared above was added to initiate polymerization. After 1 hour, methanol was added to stop the polymerization. The obtained polymer was washed with methanol and then dried at 200 ° C. for 2 hours. A styrene resin B-1 having a syndiotactic structure with a paramethylstyrene content of about 14% by weight and an MFR (300 ° C., 1.2 kg load) of about 25 g / 10 min was obtained.
b. Preparation of Styrene Resin B-2 Styrene resin B-1 having a syndiotactic structure was prepared by the following method.
In a well-dried and nitrogen-substituted container, put toluene, triisobutylaluminum 3.8 mmol, methylaluminoxane 16.8 mmol, and octahydrofluorenyltitanium trimethoxide 0.15 mmol so that the Ti concentration is 3 mmol / l. It was adjusted. After mixing each component, it stirred for 1 hour and used as a catalyst.
Further, 4.65 liters of styrene, 0.35 liters of paramethylstyrene, and triethylaluminum are put in a molar ratio of styrene / triethylaluminum = 3500/1 in a sufficiently dried and nitrogen-substituted reactor and sufficiently stirred. did. After heating the mixture of styrene and triethylaluminum to 78 ° C., 21 ml of the catalyst prepared above was added to initiate polymerization. After 1 hour, methanol was added to stop the polymerization. The obtained polymer was washed with methanol and then dried at 200 ° C. for 2 hours. A styrene resin B-2 having a syndiotactic structure with a paramethylstyrene content of about 14% by weight and an MFR (300 ° C., 1.2 kg load) of about 25 g / 10 min was obtained.
c. Reference Example: Preparation of Styrenic Resin B′-3 General-purpose polystyrene manufactured by Polystyrene Japan was used as B′-3.
The composition of component (II) is shown in Table 2.

C. Preparation of component (III) a. Preparation of Copolymer C-1 Copolymer C-1 having a styrene content of 770% was prepared by the following method.
A cyclohexane solution containing 27 parts by weight of styrene (monomer concentration: 20% by weight) is added to a polymerizer equipped with a stirrer and heated to about 70 ° C., and 0.065 parts of n-butyllithium is added to 100 parts by weight of all monomers used. And polymerized at about 70 ° C. for 1 hour. Next, a cyclohexane solution (monomer concentration 20% by weight) containing 18 parts by weight of styrene, 15 parts by weight of 1,3-butadiene and 15 parts by weight of isoprene was continuously added over 1 hour and polymerized at about 70 ° C. for 1 hour. . Thereafter, a cyclohexane solution (monomer concentration 20% by weight) containing 25 parts by weight of styrene was further added, and polymerization was carried out at about 70 ° C. for 1 hour.
b. Preparation of Copolymer C-2 Copolymer C-2 having a styrene content of 77% by weight was prepared by the following method.
A cyclohexane solution containing 32 parts by weight of styrene (monomer concentration: 20% by weight) is added to a polymerization vessel equipped with a stirrer and heated to about 70 ° C., and 0.065 parts of n-butyllithium is added to 100 parts by weight of all monomers used. And polymerized at about 70 ° C. for 1 hour. Next, a cyclohexane solution containing 20 parts by weight of styrene, 11 parts by weight of 1,3-butadiene and 12 parts by weight of isoprene (monomer concentration: 20% by weight) was continuously added over 1 hour and polymerized at about 70 ° C. for 1 hour. . Thereafter, a cyclohexane solution (monomer concentration 20% by weight) containing 25 parts by weight of styrene was further added, and polymerization was carried out at about 70 ° C. for 1 hour.
c. Preparation of Copolymer C-3 Copolymer C-2 having a styrene content of 75% by weight was prepared by the following method.
A cyclohexane solution containing 30 parts by weight of styrene (monomer concentration: 20% by weight) is added to a polymerization vessel equipped with a stirrer and heated to about 70 ° C., and 0.065 parts of n-butyllithium is added to 100 parts by weight of all monomers used. And polymerized at about 70 ° C. for 1 hour. Next, a cyclohexane solution containing 20 parts by weight of styrene, 10 parts by weight of 1,3-butadiene and 15 parts by weight of isoprene (monomer concentration: 20% by weight) was continuously added over 1 hour and polymerized at about 70 ° C. for 1 hour. . Thereafter, a cyclohexane solution (monomer concentration 20% by weight) containing 25 parts by weight of styrene was further added, and polymerization was carried out at about 70 ° C. for 1 hour.
d. Reference Example: Preparation of Copolymer C′-4 Copolymer C-2 having a styrene content of 78% by weight was prepared by the following method.
A cyclohexane solution containing 33 parts by weight of styrene (monomer concentration: 20% by weight) is added to a polymerization vessel equipped with a stirrer, and then heated to about 70 ° C., and 0.065 parts of n-butyllithium is added to 100 parts by weight of all monomers used And polymerized at about 70 ° C. for 1 hour. Next, a cyclohexane solution containing 20 parts by weight of styrene and 22 parts by weight of 1,3-butadiene (monomer concentration: 20% by weight) was continuously added over 1 hour and polymerized at about 70 ° C. for 1 hour. Thereafter, a cyclohexane solution (monomer concentration 20% by weight) containing 25 parts by weight of styrene was further added, and polymerization was carried out at about 70 ° C. for 1 hour.
The composition of component (III) is shown in Table 3.

D. Measurement / Evaluation Methods Measurements and evaluations described in Examples and Comparative Examples were performed by the following methods.
1) Styrene content The styrene content of the block copolymer or the like was measured using an ultraviolet spectrophotometer (device name: UV-2450; manufactured by Shimadzu Corporation).
2) Block Styrene Content and Block Ratio A method in which a block copolymer before hydrogenation is oxidatively decomposed with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et al., J. Polym. Sci). 1, 429 (1946)), the block styrene content was measured. Further, the block ratio is calculated by the following formula using the vinyl aromatic hydrocarbon polymer block component obtained by the same method (however, the vinyl aromatic hydrocarbon polymer component having an average degree of polymerization of about 30 or less is excluded). I asked for it.
Block ratio (% by weight) = (weight of vinyl aromatic hydrocarbon polymer block in block copolymer / weight of all vinyl aromatic hydrocarbon units in block copolymer) × 100
3) Peak molecular weight of block styrene The vinyl aromatic hydrocarbon polymer block component obtained in 2) was dissolved in a tetrahydrofuran solvent, and obtained by a conventional method using gel permeation chromatography (GPC). For the peak molecular weight, monodisperse polystyrene for GPC was measured by GPC, and the peak molecular weight was read from the measured chromatographic chart based on a calibration curve between the peak count number and the number average molecular weight of the monodisperse polystyrene.
4) The amount of block styrene having a molecular weight of 35000 or more and the following block styrene From the block styrene chromatograph obtained in 3), the total area of the molecular weight distribution curve is obtained, and the area of molecular weight 35000 or more and the area below is divided by the total area of the molecular weight distribution curve The value was expressed as a percentage.
5) Number average molecular weight The molecular weight of the block copolymer and the like was measured using a GPC apparatus (manufactured by Waters, USA). Tetrahydrofuran was used as a solvent, and measurement was performed at 35 ° C. The number average molecular weight was calculated | required using the calibration curve created using the commercially available standard polystyrene whose weight average molecular weight and number average molecular weight are known.

6) Crystallization peak and crystallization peak calorie of heat-shrinkable film The crystallization peak and crystallization peak calorie of the film were measured by DSC (device name: DSC3200S; manufactured by Mac Science). The temperature was raised from room temperature to 300 ° C. at a rate of 20 ° C./min, and the crystallization curve was measured to confirm the presence or absence of a crystallization peak. Moreover, when there existed a crystallization peak, the temperature at the maximum value was made into crystallization peak temperature, and the crystallization peak calorie | heat_amount was measured.
7) Dynamic viscoelasticity measurement The dynamic viscoelasticity measurement of a copolymer or the like is performed using a viscoelasticity measuring device DVE-V4 (manufactured by Rheology Co., Ltd.), with a vibration frequency of 35 Hz and a temperature rising rate of 3 ° C / min. The test piece was cut into 5 mm × 30 mm in the temperature range of −100 ° C. to 150 ° C., and the measurement was performed with the direction perpendicular to the stretching direction of the heat-shrinkable film parallel to the vibration direction of dynamic viscoelasticity.
8) Tensile elastic modulus Based on JIS K-6732, it measured about the extending | stretching direction of the film at the tensile speed of 5 mm / min. The test piece had a width of 12.7 mm and a gap between marked lines of 50 mm. The measurement temperature was 23 ° C. The unit is Kg / cm ² .
9) Elongation at break Based on JIS K-6732, it measured about the direction perpendicular | vertical to the extending | stretching direction of a film at the tensile speed of 5 mm / min. The test piece had a width of 12.7 mm and a gap between marked lines of 50 mm. The measurement temperature was 23 ° C. The unit is Kg / cm ² .
10) Haze Liquid paraffin was applied to the surface of the stretched film and measured according to ASTM D1003.
11) Shrinkage The 80 ° C shrinkage was calculated from the following equation by immersing the stretched film in 80 ° C water for 10 seconds.
Thermal contraction rate (%) = (L−L1) / L × 100,
L: Length before contraction, L1: Length after contraction.
12) Heat resistance A heat shrinkable film measuring 5 cm in the MD direction and 10 cm in the TD direction was wound around the surface of a cylinder having a weight of 350 g and allowed to stand on an iron plate at 120 ° C. for 5 minutes, and the state of the film was visually determined.
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○: There is a hole in the film ×: There is no hole in the film

Examples 1-14 and Comparative Examples 1-5
Table 4 and compositions comprising a blend composition shown in 5, setting the cylinder temperature to 260 ° C. using a 30 mm ² screw extruder to produce a sheet. Next, using a 40 mm single-screw extruder, these compositions were formed into a sheet having a thickness of 0.25 mm at 240 ° C., and then at a stretching temperature shown in Tables 4 and 5, the horizontal axis at a stretching ratio of 5 times. The film was uniaxially stretched to obtain a heat-shrinkable film having a thickness of about 60 μm. The performance of the obtained heat shrinkable film is also shown in Tables 4 and 5.

  The heat-shrinkable film of the present invention can be suitably used for beverage container packaging, cap seals and various labels that require low-temperature shrinkage and heat resistance.

Claims (11)

The vinyl aromatic hydrocarbon unit has a weight ratio of vinyl aromatic hydrocarbon unit to conjugated diene unit of 60/40 to 95/5, and a number average molecular weight of 30,000 to 800,000 as measured by gel permeation chromatography (GPC). The vinyl aromatic hydrocarbon polymer block having a block ratio of 10 to 95% by weight and having a peak molecular weight in the molecular weight range of 5000 to 30000 is incorporated, and 40 of the vinyl aromatic hydrocarbon polymer block. A copolymer and / or a hydrogenated product thereof (I) having a molecular weight of not more than 35,000 wt.
Styrene polymer having a syndiotactic structure (II)
A heat-shrinkable film having a weight ratio of component (I) to component (II) in the range of 99.9 / 0.1 to 20/80.   The heat shrink according to claim 1, wherein at least one vinyl aromatic hydrocarbon polymer block having a peak molecular weight in the molecular weight range of 8000 to 27000 is incorporated in the copolymer and / or hydrogenated product (I) thereof. Sex film. The vinyl aromatic hydrocarbon unit has a weight ratio of vinyl aromatic hydrocarbon unit to conjugated diene unit of 60/40 to 95/5, and a number average molecular weight of 30,000 to 800,000 as measured by gel permeation chromatography (GPC). The vinyl aromatic hydrocarbon polymer block having a block ratio of 10 to 95% by weight and having a peak molecular weight in the molecular weight range of 5000 to 30000 is incorporated, and 40 of the vinyl aromatic hydrocarbon polymer block. A copolymer and / or a hydrogenated product (I) thereof having a molecular weight of 35,000 or less, having a molecular weight of 35,000 or less, a styrenic polymer (II) having a syndiotactic structure, and a vinyl aromatic hydrocarbon, butadiene and isoprene. And a vinyl aromatic hydrocarbon of the block copolymer (III) The content is 50 to 85% by weight, the isoprene content is 1 to 25% by weight, the number average molecular weight is 50,000 to 500,000 by gel permeation chromatography (GPC) measurement, and the block ratio of vinyl aromatic hydrocarbon is 50 to 95% by weight, 40 to 95% by weight of the vinyl aromatic hydrocarbon polymer block in the block copolymer has a molecular weight of 35,000 or more, and the total of component (I), component (II) and component (III) The isoprene content in the heat-shrinkable film comprising the component (I), the component (II) and the component (III) is within a range of 5 to 50/1 to 50/10 to 60 when the weight ratio is 100. 1 to 20% by weight of heat shrinkable film. The heat-shrinkable film according to any one of claims 1 to 3, wherein a value at 70 ° C of a storage elastic modulus in measurement of viscoelasticity of the heat-shrinkable film is 1 x 10 ⁹ Pa or less.   Styrenic resin (II) having a syndiotactic structure is composed of styrene and at least one styrene derivative selected from the group consisting of alkylstyrene, halogenated styrene, halogenated alkylstyrene, alkoxystyrene, and vinyl benzoate. The heat-shrinkable film according to any one of claims 1 to 3, wherein the weight ratio of the styrene unit and the styrene derivative unit is 99/1 to 50/50.   The heat-shrinkable film according to any one of claims 1 to 3, which has a melting peak at 200 to 270 ° C in DSC measurement of the heat-shrinkable film.   The heat-shrinkable film according to any one of claims 1 to 3, which has a cold crystallization peak at 100 to 180 ° C in DSC measurement of the heat-shrinkable film.   0.01 to 5 parts by weight of at least one lubricant selected from the group consisting of fatty acid amides, paraffins, hydrocarbon resins, and fatty acids with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film The heat-shrinkable film according to any one of claims 1 to 3.   2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t- with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film Pentylphenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and 2,4-bis [(octylthio) methyl] -o- The heat-shrinkable film according to any one of claims 1 to 3, comprising 0.05 to 3 parts by weight of at least one stabilizer selected from the group consisting of cresol.   At least one UV absorber selected from the group consisting of benzophenone UV absorbers, benzotriazole UV absorbers, and hindered amine light stabilizers with respect to 100 parts by weight of the total amount of components constituting the heat-shrinkable film. Or the heat-shrinkable film as described in any one of Claims 1-3 which contains 0.05-3 weight part of light stabilizers.   A heat-shrinkable multilayer film having at least one layer comprising the heat-shrinkable film according to any one of claims 1 to 3.