JP4753574B2 - Heat shrink film - Google Patents

Description

  The present invention is a heat-shrinkable film suitable for heat-shrinkable films, having a good balance of physical properties such as natural shrinkage, low-temperature shrinkage, rigidity, transparency and impact resistance, in particular, having a uniform film thickness and excellent film-forming stability. And a heat-shrinkable multilayer film.

  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, the following document 1 discloses a method for producing a heat-shrinkable film in order to improve heat shrinkability, after preheating the styrene-butadiene block copolymer within the melting point range and then stretching. The following document 2 discloses a styrene-based resin shrink film in which a specific orientation relaxation stress is maintained in a biaxially stretched film of a styrene / butadiene block copolymer in order to improve shrinkage characteristics.
In the following document 3, in order to obtain a composition having excellent mechanical properties, optical properties, stretching properties, crack resistance properties, etc., the content of the aliphatic unsaturated carboxylic acid derivative is 5 to 80% by weight, and the Vicat softening point is 90 ° C. A composition comprising a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer and a copolymer comprising a block of vinyl aromatic hydrocarbon and a conjugated diene, which does not exceed 1 is disclosed.

Reference 4 below discloses a heat-shrinkable film having a specific Tg in a block copolymer segment composed of a vinyl aromatic hydrocarbon and a conjugated diene in order to obtain a heat-shrinkable film having excellent shrinkage characteristics and environmental destruction resistance. It is disclosed. Reference 5 below discloses a heat-shrinkable film comprising a composition of a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene having a specific structure in order to obtain a heat-shrinkable film having excellent shrinkage properties and environmental destruction resistance. It is disclosed.
In the following document 6, in order to obtain a shrink film excellent in low-temperature shrinkage, optical properties, crack resistance properties, dimensional stability, etc., the vinyl aromatic hydrocarbon content is 95 to 20% by weight, and the Vicat softening point is 90 ° C. Disclosed is a low-temperature shrinkable film obtained by stretching a composition of a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer and a copolymer comprising vinyl aromatic hydrocarbon and a conjugated diene block. Yes.

In the following document 7, in order to improve the natural shrinkability at room temperature, a composition of a block copolymer comprising a styrene hydrocarbon and a conjugated diene hydrocarbon and a random copolymer having a specific Tg containing a styrene hydrocarbon is disclosed. A polystyrene-based heat-shrinkable film is disclosed. Reference 8 below discloses a vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative whose Vicat softening point does not exceed 105 ° C. in order to obtain a transparent heat-shrinkable film having excellent temporal stability and impact resistance of the film. A heat-shrinkable hard film characterized by a specific heat-shrinking force is disclosed in a composition of a copolymer and a copolymer comprising a block of vinyl aromatic hydrocarbon and conjugated diene.
Reference 9 below provides a copolymer comprising vinyl aromatic hydrocarbon and conjugated diene blocks having a specific structure and molecular weight distribution, and a vinyl aromatic in order to obtain a composition that balances transparency, rigidity, and low-temperature impact. Compositions with hydrocarbon- (meth) acrylic ester copolymer resins are disclosed. To obtain a resin composition excellent in transparency and impact resistance in the following Document 10, a block copolymer having a vinyl aromatic hydrocarbon block vinyl aromatic hydrocarbon and a conjugated diene copolymer block having a specific structure; A transparent high-strength resin composition containing a copolymer of vinyl aromatic hydrocarbon and (meth) acrylic acid ester is disclosed.

In Patent Document 11 below, in order to obtain a shrink film excellent in low-temperature shrinkage, optical properties, crack resistance properties, dimensional stability, etc., the vinyl aromatic hydrocarbon content is 95 to 20% by weight, and the Vicat softening point is 90. Multilayer low temperature shrinkage having at least one composition of vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer not exceeding ℃ and copolymer comprising vinyl aromatic hydrocarbon and conjugated diene block A film is disclosed.
In Patent Document 12 below, in order to obtain a shrink film excellent in natural shrinkage, strength, surface characteristics, waist strength, low temperature shrinkage, etc., both outer layers have a specific butadiene unit content in styrene-butadiene-styrene type block copolymer. Disclosed is a multilayer polystyrene-based heat-shrinkable film having at least three layers comprising a mixture of a polymer and a styrene-butyl acrylate, and an intermediate layer comprising a mixture of a styrene-butadiene-styrene block copolymer having a specific butadiene unit content and a styrene-butyl acrylate. Yes.

In Patent Document 13 below, in order to obtain a heat-shrinkable film excellent in any of the properties of natural shrinkage, heat-resistant fusion, transparency, and shrinkage finish, a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon are used. A block copolymer consisting of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon, with a blend comprising a block copolymer, a copolymer of vinyl aromatic hydrocarbon and an aliphatic unsaturated carboxylic acid ester as an intermediate layer A heat-shrinkable polystyrene-based laminated film is disclosed in which a mixed polymer containing a coalescence as a main component is used as front and back layers.
Patent Document 14 listed below discloses a styrene having a specific Vicat softening point in order to obtain a heat-shrinkable film having no heat-shrinkability at low temperatures, shrinkage finish, natural shrinkage, heat, and no blocking between films. -A multilayer heat-shrinkable polystyrene system having a specific heat shrinkage ratio mainly composed of a (meth) acrylic acid ester copolymer and the inner and outer layers of a styrene-conjugated diene block copolymer having a specific Vicat softening point. A film is disclosed.

The following Patent Document 15 is characterized by a specific molecular weight distribution and a residual monomer amount in order to obtain a resin composition and film having a low processing property, storage stability, odor, and excellent rigidity and impact resistance, and a multilayer film. A copolymer resin composed of a styrene monomer and a (meth) acrylic acid ester monomer, a block copolymer resin composed of styrene and a conjugated diene, and a layer mainly composed of a high-impact polystyrene resin composition A (multilayer) heat shrinkable film is disclosed.
However, these vinyl aromatic hydrocarbons and block copolymers composed of conjugated dienes, or the composition of the block copolymer and vinyl aromatic hydrocarbon-aliphatic unsaturated carboxylic acid derivative copolymer are naturally shrinkable. , Low temperature shrinkage, rigidity, transparency, blocking resistance, hot water fusion resistance and impact resistance balance and insufficient fish eye (FE) due to gel, and homogenization of heat shrink film thickness However, these documents do not disclose how to improve them, and problems in the market are still pointed out.

JP 57-34921 A JP 58-108112 A JP 59-221348 A JP-A-60-224520 JP 60-224522 A JP-A-61-25819 JP-A-4-52129 JP-A-5-104630 JP-A-6-220278 JP 7-216187 A JP 61-41544 A JP 2000-185373 A JP 2000-6329 A JP 2002-46231 A JP 2002-201324 A

  An object of the present invention is to provide a heat-shrinkable film and a heat-shrinkable multilayer film that are excellent in the balance of physical properties such as natural shrinkage, low-temperature shrinkage, rigidity, transparency, and impact resistance, and that have particularly small thickness unevenness.

As a result of intensive studies, the present inventors have found that the above object can be achieved by defining conditions for producing a specific composition as a heat-shrinkable film, and have reached the present invention.
That is, the present invention
1. In a method for producing a heat-shrinkable film obtained by stretching a composition comprising component (I) to component (III), an “advanced capillary extrusion rheometer” manufactured by Rosand Co., Ltd. is used. extrusion city at a speed 10 mm / min, the production of heat-shrinkable film melt tension at the time of 60 m / sec velocity in the melt tension measurement of the composition is characterized in that extruded at a temperature range of a 2.0~7.5gf Method.
However, when the total weight ratio of the composition is 100 parts by weight, (I) / (II) / (III) is 40 to 65/40 to 65/6 to 15 parts by weight, and the Vicat softening point Is 70-78 degreeC.
(I) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 85/15 to 95/5, the number average molecular weight is 30,000 to 500,000 according to gel permeation chromatography (GPC) measurement, and the Vicat softening temperature is 65 to A block copolymer or a hydrogenated product thereof, characterized by being 80 ° C.
(II) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 65/35 to 78/22, the number average molecular weight is 30,000 to 500,000 according to gel permeation chromatography (GPC) measurement, and the Vicat softening temperature is 68 to A block copolymer or a hydrogenated product thereof, characterized by being 82 ° C.
(III) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 30/70 to 50/50, and the number average molecular weight by gel permeation chromatography (GPC) measurement is 30,000 to 200,000. Block copolymer or hydrogenated product thereof.

2. The method for producing a heat-shrinkable film according to the above 1, wherein the vinyl aromatic hydrocarbon content in the composition is in the range of 75 to 83% by weight,
3. The method for producing a heat-shrinkable film according to the above 1 or 2, wherein the isoprene content in the composition is in the range of 0.5 to 10% by weight,
4). The heat shrinkable film according to any one of the above 1 to 3, having a heat shrinkage rate of 5 to 60% at 65 ° C. in the stretching direction and a tensile elastic modulus of 7000 to 30000 Kg / cm 2 in the stretching direction. Film production method ,
5. 0.5 to 200 parts by weight of at least one vinyl aromatic hydrocarbon polymer selected from the following a) to c) is added to 100 parts by weight of the composition: A method for producing the heat-shrinkable film according to any one of the above,
a) Styrene polymer b) Aliphatic unsaturated carboxylic acid ester-styrene copolymer c) Rubber-modified styrene polymer

6). Any one of 1 to 5 above, wherein 0.01 to 5 parts by weight of at least one lubricant selected from fatty acid amides, paraffin hydrocarbon resins, and fatty acids are added to 100 parts by weight of the composition. A method for producing a heat-shrinkable film according to claim 1 ,
7). 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, 2-t-butyl with respect to 100 parts by weight of the composition At least one stable selected from -6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 2,4-bis [(octylthio) methyl] -o-cresol The method for producing a heat-shrinkable film according to any one of 1 to 6, wherein 0.05 to 3 parts by weight of an agent is added,
8). 0.05-3 of at least one UV absorber or light stabilizer selected from benzophenone UV absorbers, benzotriazole UV absorbers, and hindered amine light stabilizers with respect to 100 parts by weight of the composition. The method for producing a thermoplastic film according to any one of 1 to 7 above, characterized by adding parts by weight,

  The heat-shrinkable film of the present invention has small thickness unevenness and excellent physical property balance such as natural shrinkage, low-temperature shrinkage, rigidity, transparency, and impact resistance.

  Hereinafter, the present invention will be described in detail. Component (I) used in the present invention has a weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 85/15 to 95/5, preferably 87/13 to 93/12. When the ratio between the vinyl aromatic hydrocarbon and the conjugated diene is 85/15 or more, a heat-shrinkable film having excellent rigidity can be obtained, and when the ratio is 95/5 or less, a heat-shrinkable film having improved impact resistance can be obtained. In addition, when component (I) is a block copolymer hydrogenated product, the vinyl aromatic hydrocarbon content may be grasped by the vinyl aromatic compound content of the block copolymer before hydrogenation. The number average molecular weight of the component (I) measured by gel permeation chromatography (GPC) is 30,000 to 500,000, preferably 50,000 to 300,000, and more preferably 80,000 to 200,000. When the number average molecular weight is in the range of 30,000 to 500,000, the moldability is excellent. The Vicat softening temperature of component (I) is 65 to 80 ° C, preferably 68 to 78 ° C, more preferably 70 to 76 ° C. When the Vicat softening temperature is in the range of 65 to 80 ° C., it is excellent in natural shrinkage and low temperature shrinkage.

  Component (II) used in the present invention has a weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 65/35 to 75/25, preferably 68/32 to 73/27. When the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is in the range of 65/35 to 75/25, the balance between impact resistance and rigidity is excellent. In addition, when component (II) is a block copolymer hydrogenated product, the vinyl aromatic hydrocarbon content may be grasped by the vinyl aromatic compound content of the block copolymer before hydrogenation. The number average molecular weight of the component (II) measured by gel permeation chromatography (GPC) is 30,000 to 500,000, preferably 50,000 to 300,000, and more preferably 80,000 to 200,000. When the number average molecular weight is in the range of 30,000 to 500,000, the moldability is excellent. The Vicat softening temperature of component (II) is 68-82 ° C, preferably 70-78 ° C. When the Vicat softening temperature is in the range of 68 to 82 ° C, it is excellent in natural shrinkage and low temperature shrinkage.

Component (III) used in the present invention has a weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 30/70 to 50/50, preferably 33/67 to 46/54, more preferably 36/64 to 42. / 58 range. When the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is in the range of 30/70 to 50/50, the balance between impact resistance and rigidity is excellent. When component (III) is a hydrogenated block copolymer, the vinyl aromatic hydrocarbon content may be determined from the vinyl aromatic compound content of the block copolymer before hydrogenation. The number average molecular weight of the component (III) as measured by gel permeation chromatography (GPC) is 30,000 to 200,000, preferably 40,000 to 150,000, and more preferably 50,000 to 100,000. When the number average molecular weight is in the range of 30,000 to 200,000, the moldability is excellent.
The number average molecular weight of the block copolymer or its hydrogenated product used in the present invention may be a mixture of a plurality of block copolymers having different molecular weights, and the number average molecular weight of the non-hydrogenated copolymer may be determined by gel permeation chromatography. The molecular weight is specified by graphy (GPC). The molecular weight of monodisperse polystyrene for gel permeation chromatography (GPC) is prepared by GPC and a calibration curve is created between the peak count and the number average molecular weight of the monodisperse polystyrene. >"Kodansha").

A preferred melt flow rate (measured according to JISK-6870. The conditions are G conditions, temperature 200 ° C., load 5 Kg) of the block copolymer or hydrogenated product used in the present invention is 0.01 to 100 g / 10 min, 0.05 to 50 g / 10 min, and more preferably 0.5 to 30 g / 10 min are recommended. The number average molecular weight and melt flow rate (hereinafter sometimes abbreviated as MFR) can be arbitrarily adjusted depending on the amount of catalyst used for the polymerization.
The Vicat softening point of the block copolymer used in the present invention or its hydrogenated product and composition was measured according to ASTM D-1525 using a compression molded product with a thickness of 3 mm (load: 1 kg, ascending (Temperature rate: 2 ° C./min). The adjustment of the Vicat softening temperature increases, for example, when the number average molecular weight is increased, and can be increased by increasing the content of vinyl aromatic hydrocarbons.

The block copolymer used in the present invention or a hydrogenated product thereof 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, It has at least one segment composed of a conjugated diene homopolymer and / or a copolymer of vinyl aromatic hydrocarbon and conjugated diene. The polymer structure of the block copolymer hydrogenated product is not particularly limited.
(AB) _n , A- (BA) _n , B- (AB) _{n + 1}
[(A−B) _k ] _{m + 1} −X, [(A−B) _k −A] _{m + 1} −X
[(BA) _k ] _{m + 1} -X, [(BA) _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.) A linear block copolymer hydrogenated product, a radial block copolymer hydrogenated product represented by the following formula, or any mixture of these polymer structures may be used. Further, in the hydrogenated 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 the vinyl aromatic hydrocarbon and the conjugated diene in the segment A and the segment B may be distributed uniformly or in a tapered (gradual decrease) form. Good. In the hydrogenated product of 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, the block copolymer or the block copolymer before hydrogenation is obtained by polymerizing a vinyl aromatic hydrocarbon and a conjugated diene in a hydrocarbon solvent using an organolithium compound as an initiator. Can do. 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.
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 block copolymer or hydrogenated product used in the present invention, (i) a copolymer block composed of isoprene and 1,3-butadiene, (ii) a copolymer block composed of isoprene and vinyl aromatic hydrocarbon, and (Iii) At least one polymer block selected from the group (i) to (iii) of a copolymer block comprising isoprene, 1,3-butadiene and vinyl aromatic hydrocarbon may be incorporated, and butadiene The block copolymer having a weight ratio of isoprene to isoprene of 3/97 to 90/10, preferably 5/95 to 85/15, more preferably 10/90 to 80/20, or a hydrogenated product thereof, Is less than 50% by weight, there is little gel formation in thermoforming and processing.

  The block copolymer used in the present invention or the block copolymer before hydrogenation thereof 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, 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 used in 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 used in 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%, preferably 75% or more, more preferably 85% of the unsaturated double bond based on the conjugated diene compound in the polymer. % Or more, particularly preferably 90% or more is recommended to be hydrogenated. Further, 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 copolymer is not particularly limited, but the hydrogenation rate is 50% or less, preferably 30% or less, more preferably 20%. The following is preferable. The hydrogenation addition 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 hydrogenated block copolymer can be arbitrarily changed by the use of the above-mentioned polar compound and 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).

  In the present invention, when a heat-shrinkable film having particularly excellent hot water fusion properties is obtained, it is 20 ° C. or higher, preferably 30 ° C. or higher, more preferably, in the differential scanning calorimetry (DSC) chart of the block copolymer hydrogenated product. A block copolymer hydrogenated product having a crystallization peak in the temperature range of 45 to 100 ° C., particularly preferably 50 to 90 ° C. is preferred. The crystallization peak heat quantity is 3 J / g or more, preferably 6 J / g or more, more preferably 10 J / g or more. The hydrogenated block copolymer having a crystallization peak has a vinyl bond content in the block copolymer before hydrogenation of less than 30%, preferably 8 to 25%, more preferably 10 to 25%, particularly preferably. It can be obtained by setting to 12 to 20%. In particular, it is recommended that the block copolymer before hydrogenation contains at least one conjugated diene polymer segment having a vinyl bond content of 8 to 25%, preferably 10 to 20%, more preferably 10 to 18%. Is done.

The weight ratio of the composition comprising the component (I) / (II) / (III) of the block copolymer or its hydrogenated product used in the present invention is 40 to 65/40 to 65/6 to 15 with the total being 100. , Preferably 35-60 / 35-60-60-12. When the composition ratio of the component (I) / (II) / (III) is within the range specified in the present invention, the natural shrinkage, the low temperature shrinkage, and the transparency are excellent.
The Vicat softening temperature of the composition comprising the component (I) / (II) / (III) of the block copolymer or its hydrogenated product used in the present invention is in the range of 70 to 78 ° C., preferably 72 to 77 ° C. is there. When the Vicat softening temperature of the composition is in the range of 70 to 78 ° C., the natural shrinkage and the low temperature shrinkability are excellent.

The vinyl aromatic hydrocarbon content in the composition comprising the components (I) / (II) / (III) of the block copolymer or its hydrogenated product used in the present invention is 75 to 83% by weight, preferably 77. It is in the range of ˜81% by weight. When the vinyl aromatic hydrocarbon content in the composition is in the range of 75 to 83% by weight, the balance between rigidity and impact resistance is excellent.
The isoprene content in the composition comprising the component (I) / (II) / (III) of the block copolymer or hydrogenated product used in the present invention is 0.5 to 10% by weight, preferably 1 to 8%. % By weight. When the isoprene content in the composition is in the range of 0.5 to 10% by weight, the fish eye (FE) in the film is small and good.

The Vicat softening temperature of the composition can be obtained by adjusting the Vicat softening temperature of the block copolymer or its hydrogenated product or adjusting the component ratio, and the vinyl aromatic hydrocarbon and isoprene in the composition are block copolymer weights. It can be obtained by adjusting the amount of vinyl aromatic hydrocarbon or isoprene in the coalescence or its hydrogenated product, or by adjusting the component ratio.
The block copolymer used in the present invention or a hydrogenated product thereof (hereinafter referred to as component (A)) is a block copolymer with a vinyl aromatic hydrocarbon polymer (hereinafter referred to as component (B)). It can be used as a composition. The weight ratio of component (A) to component (B) is 0.5 to 200 parts by weight, preferably 1 to 150 parts by weight, more preferably 3 to 100 parts by weight of component (A). 100 parts by weight. By combining the component (A) and the component (B) at such a weight ratio, a block copolymer composition excellent in rigidity, blocking resistance and natural shrinkage can be obtained.

As the vinyl aromatic hydrocarbon polymer used in the present invention, at least one selected from the following a) to c) can be used.
a) Styrene polymer b) Aliphatic unsaturated carboxylic acid ester-styrene copolymer c) Rubber-modified styrene polymer a) The styrene polymer used in the present invention is styrene or a monomer copolymerizable therewith. Those obtained by polymerization (excluding b). Examples of the monomer copolymerizable with styrene include α-methylstyrene, acrylonitrile, maleic anhydride and the like. Examples of the styrenic polymer include polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer, and styrene-maleic anhydride copolymer. Particularly preferable styrene polymer is polystyrene. I can give you. A polymer having a weight average molecular weight of 50,000 to 500,000 can be generally used. These styrenic polymers can be used singly or as a mixture of two or more, and can be used as a rigidity improving agent.

  B) Aliphatic unsaturated carboxylic acid ester of aliphatic unsaturated carboxylic acid ester-styrene copolymer used in the present invention is methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, acrylic C1 to C12, preferably C2 to C12 alcohol and acrylic acid, such as acid hexyl, or methacrylic acid and C1 to C12, preferably C2 to C12 alcohol and acrylic acid. It is at least one selected from mono- or diesters of α, β-unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and the like and alcohols having C1-C12, preferably C2-C12. The content of the aliphatic unsaturated carboxylic acid ester in the aliphatic unsaturated carboxylic acid ester-styrene copolymer is generally 5 to 50% by weight, preferably 8 to 30% by weight, and more preferably 10 to 25% by weight. is there. Further, it is recommended that the Vicat softening point in the aliphatic unsaturated carboxylic acid ester-styrene copolymer is 50 to 95 ° C, preferably 60 to 90 ° C, more preferably 65 to 85 ° C. The Vicat softening temperature is a value measured according to ASTM D-1525 (load: 1 Kg, heating rate: 2 ° C./min) using a test piece compression-molded to a thickness of 3 mm.

A preferred aliphatic unsaturated carboxylic acid ester-styrene copolymer is a copolymer mainly composed of n-butyl acrylate and styrene, and the total amount of n-butyl acrylate and styrene is 50% by weight or more, more preferably An aliphatic unsaturated carboxylic acid ester-styrene copolymer in which the total amount of n-butyl acrylate 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 and natural shrinkage.
In addition, the above-mentioned vinyl aromatic hydrocarbons other than styrene may be copolymerized in b) within the range in which the characteristics of the present invention are maintained. b) As a method for producing an aliphatic unsaturated carboxylic acid ester-styrene copolymer, 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 is used. be able to. These aliphatic unsaturated carboxylic acid ester-styrene copolymers generally have a weight average molecular weight of 50,000 to 500,000.

The c) rubber-modified styrenic polymer used in the present invention is obtained by polymerizing a mixture of a monomer copolymerizable with a vinyl aromatic hydrocarbon and an elastomer. As a 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.

As the vinyl aromatic hydrocarbon polymer used in the present invention, in particular, MFR (temperature 200 ° C. under G condition, load 5 kg) is 0.1 to 100 g / 10 min from the point of molding, preferably 0.5 to 50 g / 10 min and 1-30 g / 10 min are recommended.
In the heat-shrinkable film of the present invention, at least one selected from fatty acid amides, paraffins and hydrocarbon resins, and fatty acids as a lubricant is 0.01 to 5 parts by weight, preferably 0.05, based on 100 parts by weight of the heat-shrinkable film. By adding -4 parts by weight, more preferably 0.1-3 parts by weight, blocking resistance is improved.
Examples of fatty acid amides include stearoamide, oleyl amide, erucyl amide, behen amide, mono- or bisamide of higher fatty acids, ethylene bis stearoamide, stearyl oleyl amide, 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.
The heat shrinkable film of the present invention has at least one ultraviolet absorber and light stabilizer selected from benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and hindered amine light stabilizers as ultraviolet absorbers and light stabilizers. Is added in an amount of 0.05 to 3 parts by weight, preferably 0.05 to 2.5 parts by weight, and more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the heat-shrinkable film. .

  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 heat shrinkable film 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 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-t-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 a total of 100 parts by weight of (I) and (II) 0.05 to 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] dioxaphosphine-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 0.05 to 3 parts by weight of at least one organic phosphate-based or organic phosphite-based stabilizer such as (di-t-butylphenyl) phosphite can be added to 100 parts by weight of the heat-shrinkable film.

Various polymers and additives can be added to the heat shrinkable film of the present invention depending on the purpose.
The heat-shrinkable film of the present invention contains a vinyl aromatic hydrocarbon and conjugated diene block copolymer different from the block copolymer or hydrogenated product used in the present invention and / or a hydrogenated product thereof. A block copolymer having a hydrocarbon content of 60 to 95% by weight, preferably 65 to 90% by weight and having the same structure as that of the hydrogenated block copolymer of the present invention can be used. Alternatively, impact resistance, rigidity, elongation and the like can be improved by blending 5 to 90 parts by weight, preferably 10 to 80 parts by weight, with respect to 100 parts by weight of the hydrogenated product.

  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. 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.

The heat-shrinkable film of the present invention is obtained by extruding a block copolymer or a hydrogenated product thereof from a normal T die or an annular die into a flat shape or a tube shape, and substantially unaxially stretching the obtained unstretched product or 2 Although it is obtained by axial stretching, the sheet extrusion temperature when producing the heat-shrinkable film is within a temperature range in which the melt tension at a speed of 60 m / sec in the melt tension measurement is 2.0 to 7.5 gf. It is necessary to manufacture. The melt tension at a speed of 60 m / sec is 2.0 to 7.5 gf, preferably 2.3 to 7.3 gf, more preferably 2.5 to 7.0 gf, and particularly preferably 2.7 to 6.7 gf. . When the melt tension at a speed of 60 m / sec is in the range of 2.5 to 7 gf, the thickness of the heat shrinkable film is uniform. The extrusion temperature from the T die or the annular die is not particularly limited as long as it is within the range of the melt tension defined in the present invention. The melt tension is a value measured by using “Advanced Capillary Extrusion Rheometer” manufactured by Rosand Inc. at an orifice diameter of 1 mm and an extrusion speed of 10 mm / min. Whether the heat-shrinkable film of the present invention is a single layer or a multilayer film, it is manufactured within the range of the melt tension defined in the present invention.

  For example, when the heat-shrinkable film of the present invention is a uniaxially stretched film, the film or sheet is stretched in the extrusion direction with a calender roll or the like, or is stretched in the direction perpendicular to the extrusion direction with a tenter or the like. The film is stretched in the extrusion direction or circumferential direction. 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 film is preferably stretched at a stretching temperature of 60 to 110 ° C., preferably 80 to 100 ° C., and stretched in the machine direction and / or the transverse direction at a draw ratio of 1.5 to 8 times, preferably 2 to 6 times. When the stretching temperature is less than 60 ° C., it is difficult to obtain a desired heat-shrinkable film by breaking during stretching, and when it exceeds 110 ° 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 a biaxially stretched film, the stretch 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 105 ° C., preferably 80 to 95 ° 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 65 ° C. in the stretching direction is 5 to 60%, preferably 10 to 55. %, More preferably 15 to 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 65 ° 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 properties of molded products such as 65 ° C. hot water, silicone oil, glycerin, etc. It is the heat shrinkage rate in each stretching direction of the molded product when immersed in the interior for 5 minutes. 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.

Furthermore, the uniaxially stretched or biaxially stretched heat-shrinkable film of the present invention requires a tensile elastic modulus in the stretching direction of 7000-30000 Kg / cm ² , preferably 10,000-25000 Kg / cm ² as a heat-shrinkable packaging material. is there. 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 30000 Kg / cm ² , the impact resistance of the film is lowered.
When the uniaxially stretched or biaxially stretched 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. is used for several seconds in order to achieve the desired heat shrinkage rate. Heat shrinkage can be achieved by heating for several minutes, preferably 1 to 60 seconds.

  The heat shrink 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 may be used for the intermediate layer and both outer layers. When the heat shrinkable film of the present invention is used as an intermediate 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 intermediate layer. The Vicat softening temperature is 3 to 15 ° C. than the middle layer, and the multilayer film composed of the outer layer film is excellent in the balance between the natural shrinkage and the low temperature shrinkage.

  When the heat-shrinkable film of the present invention is used for a multilayer film, the layers other than the heat-shrinkable film layer of the present invention are not particularly limited, and the block copolymer other than that used in the present invention and / or its hydrogenated product or the present invention. A multilayer laminate obtained by combining a composition of a block copolymer other than the invention and / or a hydrogenated product thereof with the vinyl aromatic hydrocarbon polymer may be used. 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, but preferably a block copolymer other than that used in the present invention and / or hydrogenation thereof. Or a block copolymer other than those used in the present invention and / or a hydrogenated product thereof, and a composition of the vinyl aromatic hydrocarbon polymer, and the vinyl aromatic hydrocarbon polymer.

In the heat-shrinkable multilayer film preferred in the present invention, the heat-shrinkable film layer of the present invention is at least one layer of the multilayer film, and the heat shrinkage rate at 80 ° C. in the stretching direction is 10 to 80%, preferably 15 to 70%. The heat shrinkable multilayer film is more preferably 20 to 60%.
The heat shrinkable multilayer film of the present invention has a heat shrinkage rate of 65 ° C. in the stretching direction of 5 to 60%, preferably 10 to 55%, more preferably 15 to 50%, and a tensile elastic modulus in the drawing direction of 7000. It is also possible to obtain a heat-shrinkable multilayer film of ˜30000 Kg / cm ² , preferably 10,000 to 25000 Kg / cm ² .

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, the uniaxially stretched heat-shrinkable film of the present invention is excellent in low-temperature shrinkage, rigidity, and natural shrinkage. Therefore, in addition to the heat-shrinkable label material of a plastic molded product that is deformed when heated to a high temperature, A material whose water absorption is very different from that of the block copolymer of the present invention, for example, polyolefin resin such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene, polymethacrylate resin, polycarbonate resin, polyethylene terephthalate It can be suitably used as a heat-shrinkable label material for containers using at least one selected from polyester resins such as polybutylene terephthalate and polyamide resins as constituent materials.

The material constituting the plastic container in which the heat shrinkable film of the present invention can be used includes polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer in addition to the above resins. Polymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), methacrylate ester-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, polyvinyl chloride resin, A phenol resin, a urea resin, a melamine resin, an epoxy resin, an unsaturated polyester resin, a silicone resin, etc. can be mentioned. 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 65 ° C. in the direction orthogonal to the stretching direction is less than 20%, preferably 15% or less. Therefore, uniaxial stretching as a heat-shrinkable label in the present invention means that the heat shrinkage rate at 65 ° C. in the drawing direction is 5 to 60% and the heat shrinkage rate in the direction orthogonal to the drawing direction is less than 20%. This refers to performing a stretching process.

Examples of the present invention will be described below, but these do not limit the scope of the present invention. Table 1 shows block copolymers or hydrogenated products thereof, and Table 2 shows styrene-n-butyl acrylate copolymers and general-purpose polystyrene (GPPS) as vinyl aromatic hydrocarbon polymers.
(Preparation of block copolymer or hydrogenated products A-1 to A-9 thereof)
The block copolymer before hydrogenation has styrene content (% by weight) and MFR (g / 10 min) shown in Table 1 using n-butyllithium in a cyclohexane solvent as a catalyst and tetramethylethylenediamine as a randomizing agent. A block copolymer was produced. The styrene content was the addition amount of styrene and butadiene (including isoprene when isoprene is included), and the molecular weight and MFR were adjusted by the catalyst amount. In preparing the block copolymer, a monomer diluted with cyclohexane to a concentration of 20% by weight was used.
The hydrogenation catalyst was charged with 1 liter of dried and purified cyclohexane in a nitrogen-substituted reaction vessel, 100 mmol of bis (η5-cyclopentadienyl) titanium dichloride was added, and 200 mmol of trimethylaluminum was added while stirring sufficiently. The hydrogenation catalyst which added the n-hexane solution containing and made it react at room temperature for about 3 days was used.

1) Block copolymer A-1
Using an autoclave equipped with a stirrer, 0.056 parts by weight of n-butyllithium and 0.05 parts by weight of tetramethylethylenediamine were added to a cyclohexane solution containing 3 parts by weight of 1,3-butadiene under a nitrogen gas atmosphere at 70 ° C. Polymerized for 20 minutes. Next, a cyclohexane solution containing 12 parts by weight of styrene and 2 parts by weight of 1,3-butadiene was continuously added for 15 minutes to polymerize at 70 ° C., and then the process of holding for 5 minutes was repeated 5 times.
Next, a cyclohexane solution containing 27 parts by weight of styrene was added and polymerized at 70 ° C. for 35 minutes. Next, after adding 0.3 part by mass of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as a stabilizer to 100 parts by mass of the block copolymer, the solvent was removed. A hydrogenated block copolymer was obtained.

2) Hydrogenated block copolymer A-2 to A-6, A-8, A-9
Block copolymer hydrogenated products A-2 to A-6, A-8, and A-9 were prepared in the same manner as A-1.
3) Block copolymer hydrogenated product A-7
A hydrogenated catalyst was added to the block copolymer solution obtained in the same manner as the block copolymer A-1, except that 0.08 parts by weight of n-butyllithium of the block copolymer A-1 was block copolymerized. 100 ppm of titanium was added per 100 parts by weight of the coalescence, and a hydrogenation reaction was performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Thereafter, methanol was added, and then 0.3 parts by mass of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as a stabilizer was added to 100 parts by mass of the block copolymer. Thereafter, the solvent was removed to obtain a hydrogenated block copolymer. The hydrogenation rate of the block copolymer hydrogenated product A-7 was adjusted by the amount of hydrogen so that the hydrogenation rate was 97%.

(Preparation of aliphatic unsaturated carboxylic acid ester-styrene copolymer)
Styrene-n-butyl acrylate copolymers B-1 and B-2 were added to a 10 L autoclave equipped with a stirrer with 5 kg of styrene and n-butyl acrylate or methyl methacrylate in the ratio shown in Table 2, and simultaneously with ethylbenzene 0 .3 kg and a predetermined amount of 1,1 bis (t-butylperoxy) cyclohexane to adjust MFR, and after polymerization at 110 to 150 ° C. for 2 to 10 hours, unreacted styrene and acrylic acid n- Butyl and ethylbenzene were recovered and produced. The MFR of B-1 obtained was 3.0 g / 10 min, and the MFR of B-2 was 2.6 g / 10 min.

(Measurement and evaluation method)
The measurement and evaluation described in Examples and Comparative Examples were performed by the following methods.
1) Styrene content The styrene content of the block copolymer hydrogenated product was measured using an ultraviolet spectrophotometer (device name: UV-2450; manufactured by Shimadzu Corporation).
2) Number average molecular weight The molecular weight of the hydrogenated block copolymer 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.
3) Hydrogenation rate The hydrogenation rate was measured with a nuclear magnetic resonance apparatus (device name: DPX-400; manufactured by BRUKER, Germany) using a block copolymer hydrogenated product.
4) Melt tension Using an "Advanced Capillary Extrusion Rheometer" manufactured by Rosand, the measurement was performed at an extrusion speed of 10 mm / min using an orifice inner diameter of 2 mm.
5) 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 block copolymer or a hydrogenated product thereof compression-molded to a thickness of 3 mm as a test piece.

6) Shrinkage The 65 ° C shrinkage was calculated by the following formula after immersing the stretched film in 65 ° C silicone oil for 5 minutes.
Thermal contraction rate (%) = (L−L1) / L × 100,
L: Length before contraction, L1: Length after contraction.
Moreover, the 80 degreeC shrinkage rate of the heat-shrinkable multilayer film was immersed in 80 degreeC warm water for 10 second, and was computed by following Formula.
7) Natural shrinkage rate This is a value calculated by the following formula after leaving a stretched film having a shrinkage rate of 40% measured at 80 ° C for 5 days at 35 ° C.
Natural shrinkage (%) = (L2−L3) / L2 × 100,
L2: length before being left, L3: length after being left.
The smaller the natural shrinkage rate, the better the natural shrinkage.
Further, the natural shrinkage ratio of the heat-shrinkable multilayer film was calculated by the following formula after leaving the heat-shrinkable multilayer film having an 80 ° C. shrinkage of 30% at 35 ° C. for 5 days.

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) Puncture impact strength Measured according to JISP-8134. The unit is Kg · cm.
10) Haze
Liquid paraffin was applied to the surface of the sheet before stretching and measured according to ASTM D1003.
11) Blocking property Two heat-shrinkable multilayer films measuring 5 cm in length and 5 cm in width were overlapped, applied with a weight of 100 g / cm ² G, and allowed to stand at 40 ° C. for 7 days, and the blocking state of the film was visually determined.
<Criteria>
○: Blocking is not recognized.
X: Blocking is recognized.

12) Warm water fusing property The stretched film was wrapped around a glass bottle having a diameter of about 8 cm, and left in 70 ° C. warm water for 5 minutes, and the fused state of the film was visually determined. Judgment criteria are that ◎ is not fused at all, ◯ is slightly fused but leaves immediately, and × is fused and does not leave immediately.
13) Film formation stability Using a dial gauge, the stretched film is measured for a total thickness of 30 points or more, at least 15 points at regular intervals in the full width (horizontal) direction and at least 15 points in the machine (vertical) direction. The average value is calculated. Next, the value of 1/2 of the difference between the maximum value and the minimum value is expressed as a percentage of the previously calculated average value, and this is displayed with a sign of ±.
○ Film thickness unevenness is within ± 20%.
X Film thickness unevenness exceeds ± 20% or film breakage occurs.

[Examples 1-6, Comparative Examples 1-4]
The heat-shrinkable film performance was measured using the block copolymers shown in Table 1: A-1 to A-9, styrene-n-butyl acrylate copolymers: B-1, B-2, and general-purpose polystyrene: B. -3 (A & M Styrene Co., Ltd., A & M Polystyrene 685) was molded into a sheet having a thickness of 0.25 mm at a temperature shown in Table 3 using a 40 mm extruder, and then a stretching temperature. Was stretched at 105 ° C. using a tenter and stretched uniaxially at a stretch ratio of 5 times on the horizontal axis using a tenter and heat shrinkability of about 60 μm in thickness. A film was obtained. Table 3 shows the film performance of the heat-shrinkable film. The performance of the heat-shrinkable film of the present invention is as follows: rigidity represented by tensile modulus, low-temperature shrinkage represented by 80 ° C. shrinkage, natural shrinkage, impact resistance represented by puncture impact strength, hot water fusion Property, transparency represented by Haze, and good film-forming stability. In addition, the sheet | seat and film performance shown in Table 3 were performed by said method.

[Example 7]
A three-layer sheet having the blended composition shown in Table 4 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 4. 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 layers as an ultraviolet absorber, and stearamide as a lubricant with respect to 100 parts by weight of the composition of the front and back layers. 0.2 part by weight was added.

  The heat-shrinkable film of the present invention is excellent in film formation stability, transparent, rigid, natural shrinkage, low-temperature shrinkage, hot water fusion property and impact resistance, so that the film is thinned and dimensional stability And low temperature shrinkage can be achieved at the same time, and can be suitably used for beverage container packaging, cap seals and various labels.

Claims (8)

In a method for producing a heat-shrinkable film obtained by stretching a composition comprising component (I) to component (III), the composition is subjected to an orifice using a “Advanced Capillary Extrusion Rheometer” manufactured by Rosand. diameter 1 mm, extrusion City an extrusion rate of 10 mm / min, the heat melt tension at the time of 60 m / sec velocity in the melt tension measurement of the composition is characterized in that extruded at a temperature range of a 2.0~7.5gf A method for producing a shrink film.
However, when the total weight ratio of the composition is 100 parts by weight, (I) / (II) / (III) is 40 to 65/40 to 65/6 to 15 parts by weight, and the Vicat softening point Is 70-78 degreeC.
(I) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 85/15 to 95/5, the number average molecular weight is 30,000 to 500,000 according to gel permeation chromatography (GPC) measurement, and the Vicat softening temperature is 65 to A block copolymer or a hydrogenated product thereof, characterized by being 80 ° C.
(II) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 65/35 to 78/22, the number average molecular weight is 30,000 to 500,000 according to gel permeation chromatography (GPC) measurement, and the Vicat softening temperature is 68 to A block copolymer or a hydrogenated product thereof, characterized by being 82 ° C.
(III) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 30/70 to 50/50, and the number average molecular weight by gel permeation chromatography (GPC) measurement is 30,000 to 200,000. Block copolymer or hydrogenated product thereof. The method for producing a heat-shrinkable film according to claim 1, wherein the vinyl aromatic hydrocarbon content in the composition is in the range of 75 to 83% by weight. The method for producing a heat-shrinkable film according to claim 1 or 2, wherein the content of isoprene in the composition is in the range of 0.5 to 10% by weight. The method for producing a heat-shrinkable film according to any one of claims 1 to 3, wherein the heat shrinkage rate at 65 ° C in the stretching direction is 5 to 60% and the tensile elastic modulus in the stretching direction is 7000 to 30000 Kg / cm2. . 5 to 200 parts by weight of at least one vinyl aromatic hydrocarbon polymer selected from the following a) to c) is added to 100 parts by weight of the composition. The manufacturing method of the heat-shrinkable film in any one of.
a) Styrene polymer b) Aliphatic unsaturated carboxylic acid ester-styrene copolymer c) Rubber-modified styrene polymer 6. The composition according to claim 1, wherein 0.01 to 5 parts by weight of at least one lubricant selected from fatty acid amides, paraffin hydrocarbon resins, and fatty acids is added to 100 parts by weight of the composition. A method for producing a heat-shrinkable film according to claim 1. 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, 2-t-butyl with respect to 100 parts by weight of the composition At least one stable selected from -6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 2,4-bis [(octylthio) methyl] -o-cresol 0.05-3 weight part of agents are added, The manufacturing method of the heat-shrinkable film in any one of Claims 1-6 characterized by the above-mentioned. 0.05-3 of at least one UV absorber or light stabilizer selected from benzophenone UV absorbers, benzotriazole UV absorbers, and hindered amine light stabilizers with respect to 100 parts by weight of the composition. The method for producing a thermoplastic film according to any one of claims 1 to 7, wherein a part by weight is added.