JP2013216024A - Heat-shrinkable multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shrinkable multilayer film having superior low-temperature shrinkability, stiffness, elongation, transparency and peel strength.SOLUTION: A heat-shrinkable multilayer film includes an adhesive layer between a surface layer and an intermediate layer and is stretched uniaxially at the least. The surface layer contains at least one kind of polyester resin. The intermediate layer contains a block copolymer comprising: at least one polymer block A based on a vinyl aromatic hydrocarbon; and at least one conjugated diene polymer block B. The adhesive layer contains a block copolymer mixture of 50-80 mass% of a block copolymer (A) comprising the vinyl aromatic hydrocarbon and conjugated diene with 20-50 mass% of the block copolymer (B) comprising a different vinyl aromatic hydrocarbon and conjugated diene. The block copolymer (A) has 30-50 mass% of the vinyl aromatic hydrocarbon content and 50-70 mass% of the conjugated diene content and has 30,000-70,000 peak molecular weight by GPC and contains a vinyl aromatic hydrocarbon polymer block having at least one peak molecular weight of 10,000-30,000. The block copolymer (B) has 30-50 mass% of the vinyl aromatic hydrocarbon content and 50-70 mass% of the conjugated diene content and has the peak molecular weight by GPC of >70,000 and ≤130,000 and contains the vinyl aromatic hydrocarbon polymer block having at least one peak molecular weight of 10,000-30,000.

Description

  The present invention relates to a heat-shrinkable laminated film.

A block copolymer consisting of a vinyl aromatic hydrocarbon and a conjugated diene, which has a relatively high vinyl aromatic hydrocarbon content, uses properties such as transparency and impact resistance, It is used for extrusion molding applications such as films.
In particular, heat-shrinkable films using block copolymers composed of vinyl aromatic hydrocarbons and conjugated dienes have problems with residual monomers in conventional vinyl chloride resins, residual plasticizers, and hydrogen chloride during incineration. It is used for food packaging, cap seals, labels, etc.

As heat-shrinkable films for shrinkable labels, polyester-based heat-shrinkable films are mainly used.
Polyester-based heat-shrinkable films are excellent in low-temperature shrinkability, have a low natural shrinkage rate, and have a good rigidity. However, they have drawbacks in shrinkage finishing properties such as shrinkage unevenness.

  Conventionally, various studies have been made to obtain a heat-shrinkable film satisfying properties such as natural shrinkage, low-temperature shrinkage, transparency, mechanical strength, and packaging machine suitability.

Patent Document 1 discloses that the outer surface layer is made of a polyester resin and the intermediate layer is a styrene resin as a shrink label that is excellent in heat resistance, low temperature shrinkage, and solvent resistance and is less likely to cause delamination of the base film at low cost. A laminated film made of a composite resin of a resin and a polyester resin is disclosed.
Patent Document 2 discloses a surface layer (S layer) mainly composed of a polyester resin as a heat-shrinkable laminated film having excellent rupture resistance, rigidity, and shrink finish, and suppressing natural shrinkage and delamination. A laminated film having an intermediate layer (M layer) mainly composed of a styrene resin and an adhesive layer (AD layer) mainly composed of an adhesive resin is disclosed.

  Patent Document 3 discloses a polyolefin-based resin and a polylactic acid as a heat-shrinkable laminated film suitable for uses such as a shrinkage label, which is excellent in low-temperature shrinkage, low strength and shrinkage finish, and can be regenerated. A laminated film composed of a (I) layer mainly composed of a mixed resin composition composed of a resin and a modifier, and a (II) layer composed mainly of a polylactic acid resin. A laminated film is disclosed. Patent Document 4 includes a heat-shrinkable multilayer film having excellent wear resistance and a heat-shrinkable multilayer label using the film as a base material, and contains a wear-resistant layer and a polyester resin. A heat-shrinkable multilayer film is disclosed in which a surface layer, an intermediate layer containing a polystyrene resin, and a back layer containing a polyester resin are laminated in this order.

  In Patent Document 5, heat shrinkage properties, transparency, excellent interlayer adhesion at room temperature, hardly peeled even when processed at high temperature, and heat shrinkability that suppresses whitening that occurs when a film is bent during processing, etc. As a laminated film, a heat-shrinkable multilayer film using a resin composition containing a polyester-based resin as a surface layer, an intermediate layer, and a composition having different composition ratios of a polyester-based resin and a polystyrene-based resin as an adhesive layer is disclosed.

JP 2004-170715 A JP 2006-315416 A JP 2008-44365 A JP 2009-154500 A JP 2010-264657 A

  However, any of the conventional heat-shrinkable laminated films as described above still has room for improvement in terms of low-temperature shrinkage, rigidity, elongation, transparency and peel strength, such as shrink wrap, shrink-bound wrap and shrink labels. It does not have sufficient characteristics as a heat-shrinkable laminated film used in the above.

  The problem to be solved by the present invention is to provide a heat-shrinkable laminated film excellent in low-temperature shrinkage, rigidity, elongation, transparency and peel strength.

  As a result of intensive studies in order to solve the problems of the prior art relating to the heat-shrinkable film as described above, the present inventors have obtained a specific block copolymer as an intermediate layer and an adhesive layer of the heat-shrinkable laminated film. It has been found that a heat-shrinkable laminated film that is used and uses a polyester-based resin as a surface layer thereof can solve the above problems, and has completed the present invention.

That is, the present invention is as follows.
[1]
A heat-shrinkable laminated film including an adhesive layer between the surface layer and the intermediate layer and stretched in at least a uniaxial direction,
The surface layer includes at least one polyester-based resin;
The intermediate layer includes a block copolymer comprising at least one polymer block A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B of conjugated diene,
The adhesive layer comprises 50 to 80% by mass of a block copolymer (A) composed of a vinyl aromatic hydrocarbon and a conjugated diene, and 20 to 50% by mass of a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene. A block copolymer mixture comprising a polymer (B),
The block copolymer (A) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, and has a peak molecular weight of 30,000 to 70,000 as measured by GPC. Having at least one peak molecular weight of the aromatic hydrocarbon polymer block in the range of 10,000 to 30,000,
The block copolymer (B) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, the peak molecular weight by GPC measurement is more than 70,000 and not more than 130,000, A heat-shrinkable laminated film having at least one peak molecular weight of the vinyl aromatic hydrocarbon polymer block in the range of 10,000 to 30,000.
[2]
The heat according to [1], wherein the block copolymer mixture includes 55 to 75% by mass of the block copolymer (A) and 25 to 45% by mass of the block copolymer (B). Shrinkable laminated film.
[3]
The adhesive layer includes the block copolymer mixture, and a block copolymer (C) composed of a vinyl aromatic hydrocarbon and a conjugated diene,
The block copolymer (C) has a vinyl aromatic hydrocarbon content of 60 to 95% by mass and a conjugated diene content of 5 to 40% by mass, and has a peak molecular weight of 50,000 to 500,000 as measured by GPC. Having at least one peak molecular weight of the aromatic hydrocarbon polymer block in the range of 10,000 to 100,000,
The heat shrinkage according to [1] or [2], wherein the adhesive layer has a vinyl aromatic hydrocarbon content of more than 50% by mass and 80% by mass or less, and a conjugated diene content of 20% by mass to less than 50% by mass. Laminated film.
[4]
The heat according to any one of [1] to [3], wherein the block copolymer (B) is a block copolymer obtained from the block copolymer (A) using a non-halogen coupling agent. Shrinkable laminated film.
[5]
[1] to [4], wherein the intermediate layer further includes 0.1 to 80% by mass of at least one vinyl aromatic hydrocarbon polymer selected from the group consisting of the following (a) to (c). ] The heat-shrinkable laminated film according to any one of the above.
(A) Styrenic polymer (b) At least one kind of aliphatic hydrocarbon selected from vinyl aromatic hydrocarbons and aliphatic unsaturated carboxylic acids, aliphatic unsaturated carboxylic acid anhydrides and aliphatic unsaturated carboxylic acid esters Copolymer with saturated carboxylic acid or derivative thereof (c) Rubber-modified styrenic polymer [6]
The polyester resin is composed of a dicarboxylic acid component and a diol component,
The dicarboxylic acid component and the diol component each include a main component in an amount of 60 to 100 mol% with respect to the total amount (100 mol% of each), and the total amount of the other components is the dicarboxylic acid component. The total amount (100 mol%) of the diol component and the total amount (100 mol%) of the diol component (10 mol%) is 10 to 40 mol%, according to any one of [1] to [5] Heat shrinkable laminated film.
[7]
The heat-shrinkable laminate according to [6], wherein the main component of the dicarboxylic acid is terephthalic acid, the main component of the diol component is ethylene glycol, and the other component is 1,4-cyclohexanedimethanol. the film.
[8]
The amount of the 1,4-cyclohexanedimethanol is 10 to 40 mol% based on the total (200 mol%) of the total amount (100 mol%) of the dicarboxylic acid component and the total amount (100 mol%) of the diol component. The heat-shrinkable laminated film according to [6] or [7], wherein
[9]
The heat-shrinkable laminated film according to any one of [1] to [8], wherein the intermediate layer further contains 3 to 30% by mass of a polyester resin.

  According to the present invention, it is possible to provide a heat-shrinkable laminated film that is excellent in low-temperature shrinkage, rigidity, elongation, transparency, and peel strength.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Heat-shrinkable laminated film]
The heat-shrinkable laminated film of the present embodiment is a heat-shrinkable laminated film including an adhesive layer between the surface layer and the intermediate layer and stretched at least in a uniaxial direction,
The surface layer includes at least one polyester-based resin, and the intermediate layer includes at least one polymer block A mainly composed of vinyl aromatic hydrocarbon and at least one polymer block B of conjugated diene. A block copolymer consisting of
The adhesive layer comprises 50 to 80% by mass of a block copolymer (A) composed of a vinyl aromatic hydrocarbon and a conjugated diene, and 20 to 50% by mass of a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene. A block copolymer mixture comprising a polymer (B),
The block copolymer (A) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, and has a peak molecular weight of 30,000 to 70,000 as measured by GPC. Having at least one peak molecular weight of the aromatic hydrocarbon polymer block in the range of 10,000 to 30,000,
The block copolymer (B) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, the peak molecular weight by GPC measurement is more than 70,000 and not more than 130,000, A heat-shrinkable laminated film having at least one peak molecular weight of a vinyl aromatic hydrocarbon polymer block in the range of 10,000 to 30,000.

  The heat-shrinkable laminated film of the present embodiment is excellent in low-temperature shrinkage, rigidity, elongation, and transparency, and is particularly a film that does not easily peel due to external stress because the peel strength between the intermediate layer and the surface layer of the film is large. is there. And since the heat-shrinkable laminated film of this embodiment is excellent in low-temperature shrinkage, rigidity, elongation, transparency, and peel strength, heat-shrinkability that can be suitably used as shrink-wrapping, shrink-bound packaging, shrinkable labels, etc. It is a laminated film.

The heat-shrinkable laminated film of the present embodiment includes a surface layer, an intermediate layer, and an adhesive layer as described below, and is a film having an adhesive layer between the surface layer and the intermediate layer, and is at least uniaxial. It is a film stretched in the direction.
As such a film, the thermal shrinkage rate (80 ° C. shrinkage rate) in 10 seconds in 80 ° C. warm water in the main shrinkage direction is preferably 30% or more, and more preferably 40% or more.
In the present embodiment, the “main shrinkage direction” refers to the larger direction of the shrinkage rate among the transverse direction and the longitudinal direction of the heat-shrinkable laminated film. Further, the main shrinkage direction is a direction with a larger stretch ratio that is stretched in at least a uniaxial direction.
In the present embodiment, the heat shrinkage rate can be measured by the method described in the following examples.

(Surface layer)
The surface layer constituting the heat-shrinkable laminated film of this embodiment contains at least one polyester resin.
The polyester-based resin imparts rigidity and elongation to the film, and suppresses natural shrinkage while imparting low-temperature shrinkage.

  In the present embodiment, the surface layer means the outermost layer of the heat-shrinkable laminated film.

As a polyester-type resin contained in a surface layer, what was comprised from the dicarboxylic acid component and the diol component is preferable.
Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and sebacic acid. It is done.
Examples of the diol component include ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, and polyethylene glycol. , Polytetramethylene glycol, 1,4-cyclohexanedimethanol and the like.
The polyester resin is preferably composed of terephthalic acid and ethylene glycol.
The polyester resin is not limited to a simple substance, and may be a blend of two or more polyester resins.

Since the crystallinity of the resulting polyester-based resin is lowered, it is preferable to use a mixture of the dicarboxylic acid component and / or the diol component.
When the polyester-based resin is a mixture system, the dicarboxylic acid component and the diol component include the dicarboxylic acid component and the diol component as main components in an amount of 60 to 100 mol% with respect to each total amount (100 mol% each). In order to make use of the advantages of the main component and to lower the crystallinity, each of the other components other than the main component includes a total amount of dicarboxylic acid components (100 mol%) and a diol component. It is preferable that it is 10-40 mol% with respect to the sum total (200 mol%) of the total amount (100 mol%) of this, and it is more preferable that it is 20-35 mol%.

Among them, when the dicarboxylic acid component is a mixture system, terephthalic acid is used as a main component, and as other components, at least selected from the group consisting of isophthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, and adipic acid One type is preferably used.
When the diol component is a mixture system, ethylene glycol is used as a main component, and other components include 1,4-butanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, and 1,4-cyclohexanedimethanol. It is preferable to use at least one selected from the group consisting of, more preferably 1,4-cyclohexanedimethanol.

As the polyester resin, it is preferable that the dicarboxylic acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and the other components are 1,4-cyclohexanedimethanol.
In this case, the amount of 1,4-cyclohexanedimethanol is preferably 10 to 40 mol% and more preferably 20 to 35 mol% with respect to a total of 200 mol%.
By using ethylene glycol and 1,4-cyclohexanedimethanol in such an amount range, the crystallinity of the resulting polyester resin is almost lost, and the fracture resistance is improved.
Examples of such a polyester resin include commercially available “PETG6763” (manufactured by Eastman Chemical Co.), “SKYREEN PETG” (manufactured by SK Chemical Co., Ltd.), and the like.

The method for producing the composition constituting the surface layer is not particularly limited, and a known method can be used.
For example, a melt kneading method using a general mixer such as an open roll, a Banbury mixer, a single screw extruder, a twin screw extruder, a kneader, a multi-screw extruder, etc., after dissolving or dispersing and mixing each component, A method of removing the solvent by heating can be applied.
In particular, a melt kneading method using an extruder is preferable from the viewpoints of productivity and good kneading properties.

(Middle layer)
The intermediate layer constituting the heat-shrinkable laminated film of this embodiment comprises at least one polymer block A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B of conjugated diene. Includes block copolymers.
As the polymer block A mainly composed of vinyl aromatic hydrocarbons, “mainly composed” means containing more than 90% by mass of vinyl aromatic hydrocarbons. An aromatic hydrocarbon homopolymer block or a copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene containing more than 90% by mass of a vinyl aromatic hydrocarbon can be mentioned.
Examples of the conjugated diene polymer block B include a copolymer block of vinyl aromatic hydrocarbon and conjugated diene, or a conjugated diene homopolymer block containing 10 to 90% by mass of vinyl aromatic hydrocarbon.

  In the present embodiment, the intermediate layer means a layer other than the surface layer and the adhesive layer in the heat-shrinkable laminated film.

When a random copolymer portion of vinyl aromatic hydrocarbon and conjugated diene is present in polymer block A mainly composed of vinyl aromatic hydrocarbon and polymer block B of conjugated diene, the copolymerized vinyl The aromatic hydrocarbon may be distributed uniformly in the polymer block A or the polymer block B, or may be distributed in a taper (gradual decrease).
In the random copolymer portion of the vinyl aromatic hydrocarbon and the conjugated diene, a plurality of portions where the vinyl aromatic hydrocarbon is uniformly distributed and / or portions where the vinyl aromatic hydrocarbon is distributed in a tapered shape may coexist.

  When the block copolymer contained in the intermediate layer is plural in one or both of the polymer block A and the polymer block B, the plurality of polymer blocks are different in molecular weight, composition, type and the like. It may be a thing.

  The block copolymer contained in the intermediate layer can be synthesized by a conventionally known method. For example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-1779, Japanese Patent Publication No. 48-2423, Vinyl aromatic carbonization using an anionic polymerization initiator such as an organolithium compound in a hydrocarbon solvent as disclosed in JP-B-49-36957, JP-B-57-49567, JP-B-58-11446, etc. It can be synthesized by a method of block copolymerization of hydrogen and conjugated diene.

Examples of the polymer structure of the block copolymer contained in the intermediate layer include linear block copolymers such as the following (i) to (iii).
A- (BA) _n (i)
A- (BA) _n -B (ii)
B− (A−B) _{n + 1} (iii)
Here, A is a polymer block A mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block B of conjugated diene.
The boundary between the polymer block A and the polymer block B does not necessarily need to be clearly distinguished.
n is an integer greater than or equal to 1, and is generally 1-5.
Further, examples of the polymer structure of the block copolymer contained in the intermediate layer include those having the following structures (iv) to (vii) in addition to the linear block copolymer.
[(A−B) _k ] _m −X (iv)
[(A−B) _k −A] _m −X (v)
[(BA) _k ] _m -X (vi)
[(B−A) _k −B] _m −X (vii)
Here, A and B are the same as in formulas (i) to (iii), and k and m are integers of 1 or more, and are generally 1 to 5.
X represents, for example, a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride, or a residue of an anionic polymerization initiator such as a polyfunctional organolithium compound. As the block copolymer, a radial block copolymer is used. Mixtures or mixtures of any polymer structures of these block copolymers can be used.

Examples of the vinyl aromatic hydrocarbon include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, 1,1. -Diphenylethylene etc. are mentioned, Styrene is preferable.
As a vinyl aromatic hydrocarbon, only 1 type may be used and 2 or more types may be mixed and used for it.

The conjugated diene is a diolefin having a pair of conjugated double bonds. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples thereof include butadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3-butadiene and isoprene are preferable.
As a conjugated diene, only 1 type may be used and 2 or more types may be mixed and used.

When 1,3-butadiene and isoprene are used in combination as the conjugated diene, the isoprene content is preferably 10% by mass or more and 25% by mass or more based on the total mass of 1,3-butadiene and isoprene. Is more preferable, and it is further more preferable that it is 40 mass% or more.
When the isoprene content is 10% by mass or more, thermal decomposition does not occur during molding at high temperature and the molecular weight does not decrease, so that a block copolymer having a good balance between appearance characteristics and mechanical strength can be obtained.

  When manufacturing the block copolymer contained in an intermediate | middle layer, it is preferable to make it react in a hydrocarbon solvent using an anionic polymerization initiator.

As the anionic polymerization initiator, an organic lithium compound can be used, and examples thereof include an organic monolithium compound, an organic dilithium compound, an organic polylithium compound, and the like. Specifically, ethyllithium, n-propyllithium, isopropyl Examples include lithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexamethylenedilithium, butadienyldilithium, and isoprenyldilithium.
As an anionic polymerization initiator, only 1 type may be used and 2 or more types may be mixed and used.

Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, and octane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; benzene, Aromatic hydrocarbons such as toluene, ethylbenzene, xylene and the like can be mentioned.
As a hydrocarbon solvent, only 1 type may be used and 2 or more types may be mixed and used.

When producing block copolymers, adjustment of the polymerization rate, change of the microstructure of the polymerized conjugated diene part (cis, trans, vinyl ratio), adjustment of the reaction ratio of vinyl aromatic hydrocarbon and conjugated diene For the purpose, a polar compound and / or a randomizing agent can be used.
Examples of polar compounds and randomizing agents include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether; amines such as triethylamine and tetramethylethylenediamine; thioethers; phosphines; phosphoramides; alkylbenzene sulfonates; Examples thereof include sodium alkoxide.

The polymerization temperature of the block copolymer is generally −10 ° C. to 150 ° C., preferably 40 ° C. to 120 ° C.
Although the time required for the polymerization varies depending on the conditions, it is generally within 48 hours, and the polymerization can be carried out in 1 to 10 hours by selecting particularly favorable conditions.
Moreover, it is preferable that the atmosphere of the system at the time of polymerization is in a state where it is substituted with an inert gas such as nitrogen gas.
The pressure at which the polymerization is performed is particularly limited as long as the pressure is sufficient to maintain the vinyl aromatic hydrocarbon and conjugated diene as monomers and the hydrocarbon solvent as a reaction solvent in the liquid layer at the polymerization temperature. It is not something.
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 vinyl aromatic hydrocarbon content in the block copolymer is preferably 50 to 95% by mass, more preferably 55 to 95% by mass, and still more preferably 60 to 95% by mass.
When the content of the vinyl aromatic hydrocarbon in the block copolymer is 50 to 95% by mass, the composition constituting the intermediate layer is excellent in the balance between elongation and rigidity and excellent in transparency. it can.

The block ratio of the vinyl aromatic hydrocarbon polymer block incorporated in the block copolymer is preferably 10 to 98% by mass, more preferably 15 to 95% by mass, and still more preferably 20 to 90% by mass.
When the block ratio is 10 to 98% by mass, the balance between rigidity and elongation of the heat-shrinkable laminated film of the present embodiment is excellent.

  The block ratio of the vinyl aromatic hydrocarbon block is the mass ratio of the vinyl aromatic hydrocarbon and the conjugated diene in the step of copolymerizing at least a part of the vinyl aromatic hydrocarbon and the conjugated diene during the production of the block copolymer. It can be controlled by adjusting the polymerization reactivity ratio and the like.

  As a specific method, (a) a mixture of a vinyl aromatic hydrocarbon and a conjugated diene is continuously supplied to a polymerization system for polymerization, and / or (b) a polar compound and / or a randomizing agent is added. And a method of copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene.

The block ratio of the vinyl aromatic hydrocarbon polymer block of the block copolymer is determined by a method in which the block copolymer is oxidatively decomposed with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1,429 (1946)], and the vinyl aromatic hydrocarbon polymer block component (excluding vinyl aromatic hydrocarbon polymer components having an average degree of polymerization of about 30 or less) was determined. Can be calculated by the following equation.

Vinyl aromatics in block copolymers.
Mass block ratio of hydrocarbon polymer block (%) = ――――――――――――――――――――――――― × 100
Total vinyl in block copolymer
Aromatic hydrocarbon mass

The peak molecular weight by GPC measurement of the vinyl aromatic hydrocarbon polymer block in the block copolymer is preferably from 50,000 to 200,000, more preferably from 7,000 to 180,000.
When the peak molecular weight is 50,000 to 200,000, excellent rigidity and elongation can be obtained, and molding processability and transparency can be improved.

The peak molecular weight of the vinyl aromatic hydrocarbon polymer block of the block copolymer is determined by a method in which the block copolymer is oxidatively decomposed with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1, 429 (1946)] can be obtained by analyzing the vinyl aromatic hydrocarbon polymer block component by gel permeation chromatography (GPC).
Specifically, after GPC curve is obtained by applying vinyl aromatic hydrocarbon polymer block component to GPC, monodisperse polystyrene is measured by GPC, and a calibration curve is created from the peak count and the molecular weight of monodisperse polystyrene. The peak molecular weight can be determined by calculation according to a conventional method (“gel permeation chromatography”, pages 81 to 85 (1976, issued by Maruzen, Japan).
The peak molecular weight means the molecular weight at which the first derivative of the amount of change in the height of the vertical axis when the horizontal axis in the molecular weight distribution curve is the molecular weight is zero.

The peak molecular weight of the block copolymer as measured by GPC is preferably 30,000 to 1,000,000, more preferably 40,000 to 800,000, and even more preferably 50,000 to 600,000.
The peak molecular weight is preferably 30,000 or more from the viewpoint of improving the mechanical strength of the composition constituting the intermediate layer of the heat-shrinkable laminated film of the present embodiment, and has good workability and heat. From the viewpoint of ensuring compatibility with the plastic resin, it is preferably 1 million or less.

  The peak molecular weight of the block copolymer can also be determined by analyzing by GPC as described above except that the block copolymer is used as a sample.

The block copolymer is obtained as a solution in the synthesis step, and is separated from the solution by removing the catalyst residue as necessary.
As a method for separating the solvent, for example, a polar solvent which is a poor solvent for the block copolymer, such as acetone or alcohol, is added to the solution after polymerization or after hydrogenation by a conventionally known method. , A method of precipitating and recovering the block copolymer, a method of charging the block copolymer solution into hot water with stirring, removing the solvent by steam stripping, and further heating the solution directly. And a method of distilling off the solvent.
If necessary, stabilizers such as various phenol stabilizers, phosphorus stabilizers, sulfur stabilizers, and amine stabilizers may be added to the block copolymer.

The intermediate layer constituting the heat-shrinkable laminated film of this embodiment may further contain a vinyl aromatic hydrocarbon-based polymer in the block copolymer described above.
A heat-shrinkable laminated film having excellent rigidity can be obtained by combining a vinyl aromatic hydrocarbon polymer with a block copolymer.
The content of the vinyl aromatic hydrocarbon polymer is preferably 0.1 to 80% by mass, more preferably 0.3 to 75% by mass as the resin component constituting the intermediate layer. More preferably, it is -70 mass%.

As the vinyl aromatic hydrocarbon polymer, it is preferable to use at least one selected from the group consisting of the following (a) to (c).
(A) Styrenic polymer (b) At least one aliphatic unsaturated hydrocarbon selected from a vinyl aromatic hydrocarbon, an aliphatic unsaturated carboxylic acid, an aliphatic unsaturated carboxylic acid anhydride, and an aliphatic unsaturated carboxylic acid ester Copolymer with saturated carboxylic acid or derivative thereof (c) Rubber-modified styrene polymer

(A) A styrenic polymer is a polymer obtained by polymerizing a copolymerizable monomer and styrene (excluding (b)), and as a monomer copolymerizable with styrene, α- Examples include methylstyrene and acrylonitrile.
Examples of the styrenic polymer include polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer, and polystyrene is preferable.
(A) As a manufacturing method of a styrene-type polymer, the well-known method of manufacturing a styrene-type resin, for example, a block polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method etc. can be used.

The weight average molecular weight of the styrene polymer is generally 50,000 to 500,000.
Only one kind of styrenic polymer may be used, or two or more kinds of styrenic polymers may be mixed and used as a rigidity improving agent.

(B) a vinyl aromatic hydrocarbon and at least one aliphatic unsaturated carboxylic acid selected from an aliphatic unsaturated carboxylic acid, an aliphatic unsaturated carboxylic acid anhydride, and an aliphatic unsaturated carboxylic acid ester, or a derivative thereof In the copolymer, the aliphatic unsaturated carboxylic acid derivative includes an aliphatic unsaturated carboxylic acid anhydride and an aliphatic unsaturated carboxylic acid ester.
Examples of the aliphatic unsaturated carboxylic acid include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid and the like.
Examples of the aliphatic unsaturated carboxylic acid anhydride include fumaric anhydride, itaconic anhydride, maleic anhydride and the like.
Examples of the aliphatic unsaturated carboxylic acid ester include mono- or diesters of an aliphatic unsaturated carboxylic acid and an alcohol having C1 to C12, preferably C2 to C12.
Examples of the aliphatic unsaturated carboxylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) Examples include acrylic acid esters such as hexyl acrylate, methacrylic acid esters, fumaric acid, itaconic acid, maleic acid, and the like, and α, β unsaturated dicarboxylic acid monoesters or diesters of C1-C12 alcohols.

  The content of the aliphatic unsaturated carboxylic acid and / or the aliphatic unsaturated carboxylic acid derivative is generally 5 to 50% by mass, preferably 8 to 30% by mass, and more preferably 10 to 25% by mass.

  (B) As a manufacturing method of a copolymer, 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. can be used.

(B) The weight average molecular weight of the copolymer is generally 50,000 to 500,000.
(B) A copolymer may use only 1 type and may mix and use 2 or more types.

  (B) Among the copolymers of vinyl aromatic hydrocarbon and aliphatic unsaturated carboxylic acid ester, the styrene-aliphatic unsaturated carboxylic acid ester copolymer can improve the low temperature shrinkage as the copolymer. preferable.

Among the aliphatic unsaturated carboxylic acid ester-styrene copolymers, particularly preferred are copolymers mainly composed of styrene and n-butyl acrylate, and the total amount of styrene and n-butyl acrylate. Is preferably 50% by mass or more, and more preferably a styrene-aliphatic unsaturated carboxylic acid ester copolymer in which the total amount of styrene and n-butyl acrylate is 60% by mass or more.
A heat-shrinkable laminated film further using an aromatic hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer mainly composed of styrene and n-butyl acrylate as an intermediate layer has good shrinkage.

Examples of the (c) rubber-modified styrenic polymer include those obtained by polymerizing a mixture of a monomer copolymerizable with a 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 the monomer copolymerizable with the vinyl aromatic hydrocarbon include α-methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, maleic anhydride and the like.
Examples of the copolymerizable elastomer include natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber, and high styrene rubber.
The elastomer is generally 3 to 50 parts by mass with respect to 100 parts by mass of the vinyl aromatic hydrocarbon and copolymerizable monomer, and is dissolved in this monomer or becomes a latex to form emulsion polymerization, bulk polymerization, bulk- Used for suspension polymerization and the like.

Preferred examples of the rubber-modified styrene polymer (c) include an impact-resistant rubber-modified styrene polymer (HIPS).
(C) The rubber-modified styrenic polymer can be used as an agent for improving rigidity and elongation.

(C) The weight average molecular weight of the rubber-modified styrenic polymer is generally 50,000 to 500,000.
(C) One type of rubber-modified styrenic polymer may be used, or two or more types may be mixed and used.

  The content of the rubber-modified styrenic polymer is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the block copolymer in consideration of maintaining transparency.

The vinyl aromatic hydrocarbon polymer preferably has a melt flow rate (MFR, temperature 200 ° C. under G condition, load 5 kg) of 0.1 to 100 g / 10 min, more preferably from the viewpoint of molding. It is 0.5-50 g / 10min, More preferably, it is 1-30 g / 10min.
In the case of an intermediate layer containing a block copolymer and a vinyl aromatic hydrocarbon polymer, other resins and / or additives may be blended as necessary.

From the viewpoint of improving rigidity, the intermediate layer may preferably contain 3 to 30% by mass, more preferably 3 to 20% by mass, as a resin component constituting the intermediate layer.
As the polyester resin, the same polyester resin contained in the surface layer may be used, or different polyester resins may be used.

As a polyester resin contained in the intermediate layer, a film may be produced by blending into the intermediate layer from the beginning, and crystallization can be made difficult to proceed, so when mixed from the surface layer in the film manufacturing process Is also included.
In this case, as a final content, 3 to 30% by mass of a polyester-based resin may be included in the intermediate layer as a resin component constituting the intermediate layer.
Further, the content of the polyester resin contained in the intermediate layer is 30% by mixing the polyester resin in the intermediate layer with the polyester resin used in the surface layer in the film production process. Even if it is a case where it becomes% or more, if it is in the range of the summary of this invention, there is no problem.
In the case of an intermediate layer containing a block copolymer and a polyester-based resin, other resins and / or additives may be blended as necessary.

The method for producing the composition constituting the intermediate layer is not particularly limited, and a known method can be used.
For example, a melt kneading method using a general mixer such as an open roll, a Banbury mixer, a single screw extruder, a twin screw extruder, a kneader, a multi-screw extruder, etc., after dissolving or dispersing and mixing each component, A method of removing the solvent by heating can be applied.
In particular, a melt kneading method using an extruder is preferable from the viewpoints of productivity and good kneading properties.
The melt-kneading temperature is preferably from 100 to 350 ° C., taking into consideration the softening temperature of the vinyl aromatic hydrocarbon polymer used, if necessary, the melt viscosity, the thermal deterioration of the block copolymer, etc., and 150 to 350 ° C. Is more preferable, and 180-330 degreeC is further more preferable.
The melt kneading time (or the average residence time of the melt kneading step) is 0.2 considering the degree of kneading (dispersibility), productivity, deterioration of block copolymer, vinyl aromatic hydrocarbon polymer, etc. -60 minutes are preferred, 0.5-30 minutes are more preferred, and 1-20 minutes are even more preferred.

(Adhesive layer)
The heat-shrinkable laminated film of the present embodiment is a film that is laminated in the order of an intermediate layer, an adhesive layer, and a surface layer, and the adhesive layer is formed between the intermediate layer and the surface layer.

  In this embodiment, an adhesive layer is a layer which provides the peeling prevention function of the surface layer and intermediate | middle layer of a heat-shrinkable laminated film.

The adhesive layer constituting the heat-shrinkable laminated film of the present embodiment includes a block copolymer (A) composed of vinyl aromatic hydrocarbon and conjugated diene, and a block copolymer composed of vinyl aromatic hydrocarbon and conjugated diene ( B) and a block copolymer mixture.
In a block copolymer mixture, 50-80 mass% of block copolymers (A) and 20-50 mass% of block copolymers (B) are included.
Preferably, the block copolymer mixture contains 55 to 75% by mass of the block copolymer (A) and 25 to 45% by mass of the block copolymer (B).
By including the block copolymer (A) and the block copolymer (B) in such an amount in the adhesive layer, a heat-shrinkable laminated film having excellent delamination strength between the surface layer and the intermediate layer can be obtained.

The block copolymer (A) is a polymer having a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass.
Preferably, the vinyl aromatic hydrocarbon content is 32 to 48 mass%, the conjugated diene content is 52 to 68 mass%, and the vinyl aromatic hydrocarbon content and the conjugated diene content are within such ranges. The heat-shrinkable laminated film having excellent delamination strength between the surface layer and the intermediate layer can be obtained.

  The peak molecular weight of the block copolymer (A) by GPC measurement is 30,000 to 70,000, preferably 35,000 to 65,000. The peak molecular weight of the vinyl aromatic hydrocarbon polymer block is 10,000. ˜30,000, preferably 10,000 to 27,000, more preferably 12,000 to 25,000.

The block copolymer (B) is a polymer having a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass.
Preferably, the vinyl aromatic hydrocarbon content is 32 to 48 mass%, the conjugated diene content is 52 to 68 mass%, and the vinyl aromatic hydrocarbon content and the conjugated diene content are within such ranges. The heat-shrinkable laminated film having excellent delamination strength between the surface layer and the intermediate layer can be obtained.

  The peak molecular weight by GPC measurement of the block copolymer (B) is more than 70,000 and not more than 130,000, preferably 75,000 to 125,000, and the peak molecular weight of the vinyl aromatic hydrocarbon polymer block is It has at least one in the range of 10,000 to 30,000, preferably 10,000 to 27,000, more preferably 12,000 to 25,000.

  The block copolymer (A) has a peak molecular weight of 30,000 to 70,000 as measured by GPC, and the vinyl aromatic hydrocarbon polymer block has at least one peak molecular weight in the range of 10,000 to 30,000. A block copolymer having a peak molecular weight of more than 70,000 and not more than 130,000 according to GPC measurement of the polymer (B), and a vinyl aromatic hydrocarbon polymer block having a peak molecular weight in the range of 10,000 to 30,000. By using a mixture, it is possible to obtain a heat-shrinkable laminated film excellent in film formability and delamination strength between the surface layer and the intermediate layer.

The peak molecular weights of the block copolymer (A) and the block copolymer (B) can be determined by GPC measurement.
Specifically, after obtaining the GPC curve by applying the block copolymer (A) or the block copolymer (B) to GPC, using a calibration curve prepared from the peak count number and molecular weight of the monodisperse polystyrene by GPC. The peak molecular weight can be determined by calculating according to a conventional method (“gel permeation chromatography”, pages 81 to 85 (1976, issued by Maruzen, Japan).
The peak molecular weight means the molecular weight at which the first derivative of the amount of change in the height of the vertical axis when the horizontal axis in the molecular weight distribution curve is the molecular weight is zero.
The peak molecular weight of the vinyl aromatic hydrocarbon polymer block of the block copolymer (A) and the block copolymer (B) is also analyzed by GPC in the same manner as described above except that the vinyl aromatic hydrocarbon polymer block is used as a sample. Can be obtained.

The block copolymer (A) and the block copolymer (B) were each obtained by polymerizing vinyl aromatic hydrocarbons using an organic lithium compound as an anionic polymerization initiator in a hydrocarbon solvent, for example. A polymer and a conjugated diene can be polymerized, and the method can be produced by repeating these operations.
The peak molecular weight of the block copolymer can be adjusted by controlling the amount of the organolithium compound.

The block copolymer mixture can be obtained by mixing two types of block copolymers (A) and block copolymers (B).
As such a mixing method, after completion of each polymerization reaction, the reaction solution is mixed and water, alcohol, acid or the like is added to deactivate the active species, or after completion of each polymerization reaction, the reaction solution is separated separately. And a method of separating the polymerization solvent by, for example, steam stripping and drying the resulting mixed solution.
The block copolymer (A) and the block copolymer (B) may be obtained by blending the block copolymer obtained by separating and drying the polymerization solvent separately from each reaction solution with a roll or the like. .

The block copolymer mixture can also be obtained by the following method.
After the block copolymer (A) is polymerized, a copolymer product obtained by adding a predetermined amount of a suitable coupling agent to the organolithium compound in the polymerization system is converted into the block copolymer (B). And the obtained block copolymer (B) can be obtained by mixing with the block copolymer (A).
In the block copolymer mixture obtained by such a method, the molecular weight and molecular weight distribution of the polymer block portion mainly composed of vinyl aromatic hydrocarbon are the same in the block copolymer (A) and the block copolymer (B). Therefore, it can be set as the heat-shrinkable laminated film excellent in the delamination strength of the surface layer and the intermediate layer.

  The block copolymer (A) and the block copolymer (B) can be produced by a conventionally known method in the same manner as the block copolymer used for the intermediate layer, the kind of vinyl aromatic hydrocarbon, the kind of conjugated diene, The kind of the hydrocarbon solvent, the kind of the organic lithium compound, the kind of the polar compound and the randomizing agent can be the same as the block copolymer used for the intermediate layer.

When the block copolymer (B) is obtained by coupling reaction of the block copolymer (A), examples of the coupling agent include difunctional diglycidyl ether and di (glycidyloxy) (methyl). Epoxy compounds such as phenylsilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethoxymethylsilane, triethoxysilane, tetramethoxysilane, alkoxysilicon compounds such as tetraethoxysilane, methyl benzoate, ethyl benzoate, etc. Ester compounds, vinyl allenes such as divinylbenzene, silicon halide compounds such as dichlorodimethylsilane and phenylmethyldichlorosilane, tin compounds such as dichlorodimethyltin and tetrachlorotin, and ketones such as tetrachlorosilane Containing compounds, and the like.
Among these, bifunctional coupling agents are preferably used, and non-halogen coupling agents are preferably used from the viewpoint of heat discoloration during processing.
A coupling agent may use only 1 type and may mix and use 2 or more types.

In the present embodiment, the adhesive layer may include a block copolymer mixture including the block copolymer (A) and the block copolymer (B), and the block copolymer (C).
The block copolymer (C) is a polymer having a vinyl aromatic hydrocarbon content of 60 to 95% by mass and a conjugated diene content of 5 to 40% by mass, preferably a vinyl aromatic hydrocarbon content of 63 to It is a polymer comprising 90% by mass and a conjugated diene content of 10 to 37% by mass.

The block copolymer (C) has a peak molecular weight of 50,000 to 500,000, preferably 70,000 to 300,000 as measured by GPC, and is a vinyl aromatic hydrocarbon polymer constituting the block copolymer (C). The block has a peak molecular weight in the range of 10,000 to 100,000, preferably in the range of 20,000 to 80,000.
The vinyl aromatic hydrocarbon content of the adhesive layer containing the block copolymer (C) is more than 50% by mass and 80% by mass or less, preferably 53 to 75% by mass, and the conjugated diene content is 20% by mass or more. It is less than 50% by mass, preferably 25 to 47% by mass.
When the vinyl aromatic hydrocarbon content is in the range of more than 50% by mass and 80% by mass or less when the block copolymer (C) is mixed and used in the adhesive layer, the film has excellent rigidity and peel strength.

  In the present embodiment, the block copolymer mixture is preferably 1 to 60% by mass, the block copolymer (C) is 40 to 99% by mass, more preferably the block copolymer mixture is 3 to 55% by mass, It contains 45 to 97% by mass of the polymer (C), more preferably 5 to 50% by mass of the block copolymer mixture, and 50 to 95% by mass of the block copolymer (C).

The block copolymer (C) can be produced by a conventionally known method in the same manner as the block copolymer used for the intermediate layer. The type of vinyl aromatic hydrocarbon, the type of conjugated diene, the type of hydrocarbon solvent, organolithium The same type of block copolymer used for the intermediate layer can be used for the type of compound and the type of polar compound and randomizing agent.
Moreover, you may use the same block copolymer as the block copolymer used for an intermediate | middle layer as a block copolymer (C).

  In the block copolymer mixture, additives optionally used in the intermediate layer can be used, and the method for producing the composition constituting the adhesive layer is not particularly limited, and examples of the intermediate layer are illustrated. Any known method can be used.

  In this embodiment, you may mix | blend other resin and / or an additive with a surface layer, an intermediate | middle layer, and an adhesive layer as needed.

  As other resin in this embodiment, polyolefin resin, an acrylic resin, polycarbonate resin etc. are mentioned, for example.

Examples of the additive in the present embodiment include those commonly used in thermoplastic resin compositions, such as calcium carbonate, magnesium carbonate, magnesium hydroxide, calcium sulfate, barium sulfate, silica, clay, talc, mica. , Wollastonite, Montmorillonite, Zeolite, Alumina, Titanium oxide, Magnesium oxide, Zinc oxide, Slug wool, Glass fiber and other inorganic fillers; Carbon black, Iron oxide and other pigments; Stearic acid, Behenic acid, Zinc stearate, Lubricants such as calcium stearate, magnesium stearate, ethylene bisstearamide; mold release agents; paraffinic process oil, naphthenic process oil, aromatic process oil, and paraffin.
Additives include softeners and plasticizers such as organic polysiloxanes and mineral oils, antioxidants such as hindered phenol antioxidants, phosphorus thermal stabilizers, hindered amine light stabilizers, and benzotriazole ultraviolet absorbers. In addition, flame retardants, antistatic agents, reinforcing agents such as organic fibers, glass fibers, carbon fibers, and metal whiskers, colorants, and the like are also used, and are disclosed in “Rubber / plastic compounding chemicals” (edited by Rubber Digest). Things are also used.

(Configuration of heat-shrinkable laminated film)
The heat shrinkable laminated film of the present embodiment is not particularly limited as long as it has at least a three-layer structure having an adhesive layer between the surface layer and the intermediate layer.
The laminated configuration in the present embodiment is a three-type configuration including a surface layer / adhesive layer / intermediate layer. The thickness ratio of the surface layer and the intermediate layer constituting the heat-shrinkable laminated film is preferably 1/2/1 to 1/12/1 as surface layer / intermediate layer / surface layer, 1/4 / It is more preferable that it is 1-1 / 8/1.
The thickness of the adhesive layer is preferably 10 to 150% of the thickness of the surface layer from the viewpoint of adhesive effect and transparency.
The preferred layer structure is 3 layers and 5 layers of surface layer / adhesive layer / intermediate layer / adhesive layer / surface layer. In the case of five layers, the structure may be a surface layer / adhesive layer / intermediate layer / adhesive layer / back layer. In this case, the surface layer used for the front layer and the back layer may be the same or different. Good.

[Method for producing heat-shrinkable laminated film]
The heat-shrinkable laminated film of this embodiment can be produced by co-extruding materials constituting the intermediate layer, the surface layer and the adhesive layer using an extruder equipped with a T die. In extruding, an existing method such as a T-die method or a tubular method may be employed.
In addition, even if the material constituting the intermediate layer, the material constituting the surface layer, and the material constituting the adhesive layer are separately formed into sheets, and then laminated using a press method, a roll nip method, etc., the heat shrinkage of this embodiment Can be produced.

Specifically, the heat-shrinkable laminated film of the present embodiment is obtained by melt-extruding the material constituting the intermediate layer, the material constituting the surface layer, and the material constituting the adhesive layer, and the melt-extruded resin is a cooling roll, Cool with air, water, etc., and then reheat with an appropriate method such as hot air, hot water, infrared, etc., and stretch in at least one axial direction or biaxial direction by roll method, tenter method, tubular method, etc. Can be manufactured.
The stretching temperature needs to be changed depending on the softening temperature of the resin constituting the heat-shrinkable laminated film and the use required for the heat-shrinkable laminated film, but is generally 60 to 130 ° C., preferably 70 ~ 120 ° C.
The draw ratio in the main shrinkage direction is appropriately determined in the range of 2 to 7 times depending on the film composition, stretch means, stretch temperature, and target product form.
Whether to use uniaxial stretching or biaxial stretching is determined depending on the intended use of the product.

Even in applications that require shrinkage characteristics in almost one direction, such as labels for PET bottles, it is effective in terms of improving the finish to stretch in the vertical direction without impairing the shrinkage characteristics. It is.
When used for a PET bottle label, the stretching temperature is typically 60 to 90 ° C. As the draw ratio is increased, the fracture resistance is improved, but the shrinkage ratio is increased accordingly. Therefore, in order to obtain a good shrinkage finish, it is preferably 1.03 to 1.5 times.

In this embodiment, it is preferable that the thermal contraction rate for 10 seconds in 70 ° C. warm water in the main contraction direction is 5% or more.
The shrinkage rate in the non-main shrinkage direction for PET labels is preferably 10% or less, more preferably 5%, and further preferably 3% or less in 10 seconds of 80 ° C. hot water.
When the shrinkage rate exceeds the upper limit, in the label application, shrinkage in the vertical direction becomes remarkable after shrinkage, resulting in dimensional deviation and appearance problems.
Moreover, after extending | stretching, shrinkage | contraction can be provided and hold | maintained by cooling a film rapidly within the time when the molecular orientation of a film does not ease.
The method described in the Example mentioned later is applicable about the measuring method of the shrinkage | contraction rate in the hot water of the main shrinkage | contraction direction of a heat-shrinkable laminated film.

  The heat-shrinkable laminated film of this embodiment preferably has a haze value measured in accordance with ASTM D1003 of 10% or less, more preferably 7% or less, and even more preferably 5% or less.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. This invention is not restrict | limited by the Example mentioned later. In addition, the measuring method and evaluation method used in a present Example are as follows.

(1) Styrene content It calculated from the absorption intensity of 262 nm using the ultraviolet spectrophotometer (Hitachi UV200).

(2) Peak molecular weight and number average molecular weight of block copolymer by GPC measurement 10 mg of block copolymer was dissolved in 10 mL of tetrahydrofuran (THF), and the resulting solution was subjected to gel permeation chromatography (GPC) measurement to obtain monodisperse polystyrene. From the calibration curve prepared for, the peak molecular weight and the number average molecular weight were determined. The measurement conditions for GPC are shown below.
Monodisperse polystyrene: TSK standard polystyrene (manufactured by Tosoh Corporation)
Column: TSK gel super multipore HZ-M (manufactured by Tosoh Corporation)
Column temperature: 42 ° C
Solvent: THF
Flow rate: 2mL / min
Measuring device: HLC-8220 (manufactured by Tosoh Corporation)
Detector: RI

(3) Block ratio A method of oxidatively decomposing a block copolymer with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1,429 (1946)] was quantified and determined from the following formula.

Mass of styrene block Block ratio (%) = ――――――――――――――――――― × 100
Total styrene mass

(4) Peak molecular weight of styrene block The styrene block component obtained by the same method as in (3) above was measured and determined by the same method as in (2) above.

(5) Melt flow rate (MFR)
Based on ASTM D1238, the measurement was performed under the conditions of 200 ° C. and a load of 5 kg.

(6) 80 ° C. Shrinkage The stretched film was immersed in 80 ° C. warm water for 10 seconds, and calculated according to the following formula.
80 ° C. Shrinkage (%) = (L−L1) / L × 100
Here, in the TD direction (main contraction direction), L indicates the length before contraction, and L1 indicates the length after contraction.

(7) Tensile modulus (Rigidity standard)
As a test piece, the width in the MD and TD directions from the stretched film is 10 mm, and the gap between the marked lines is 100.
What was cut into strips to a length of mm was used.
The measurement temperature was 23 ° C., the tensile speed was 10 mm / min, and the measurement was performed according to JIS K-6732. The average value in the MD and TD directions was taken as the value of tensile elastic modulus (MPa).

(8) 23 degreeC elongation As a test piece, what was cut out to the length which makes a width | variety 15 mm in MD direction from a stretched film and 40 mm between marked lines was used.
Measurement temperature is 23 ° C., tensile speed is 100 mm / m
The measurement was performed in accordance with JIS K-6732. The higher the value of 23 ° C. elongation, the better.

(9) Haze value (a measure of transparency)
Liquid paraffin was applied to the stretched film surface and measured according to ASTM D1003.

(10) Peel strength Measure the strength at which the layer including the surface layer of the stretched film is used as the release layer, and the layer including the intermediate layer is used as the layer to be peeled and peeled at a width of 1 cm in the MD direction and a peel rate of 150 mm / min in the 180 degree direction did. The larger the value, the stronger and more desirable the peel strength.

<Manufacture of block copolymer>
(Block copolymer A-1)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 37 parts by mass of styrene, 0.145 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 45 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 63 parts by mass of 1,3-butadiene at 65 ° C. for 75 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-1.

(Block copolymer A-2)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 45 parts by mass of styrene, 0.125 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 50 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 55 parts by mass of 1,3-butadiene at 65 ° C. for 65 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-2.

(Block copolymer A-3)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 20 parts by mass of styrene, 0.107 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 25 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 80 parts by mass of 1,3-butadiene at 65 ° C. for 95 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-3.

(Block copolymer A-4)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 58 parts by mass of styrene, 0.155 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 65 minutes.
Next, a cyclohexane solution containing 42 parts by mass of 1,3-butadiene was continuously supplied at 65 ° C. for 55 minutes for polymerization.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-4.

(Block copolymer A-5)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 38 parts by mass of styrene, 0.243 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 45 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 62 parts by mass of 1,3-butadiene at 65 ° C. for 75 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-5.

(Block copolymer A-6)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 48 parts by mass of styrene, 0.099 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 55 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 52 parts by mass of 1,3-butadiene at 65 ° C. for 70 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 part by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-6.

(Block copolymer A-7)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 31 parts by mass of styrene, 0.284 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 40 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 69 parts by mass of 1,3-butadiene at 65 ° C. for 80 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer A-7.

  Table 1 shows the styrene content (% by mass) of the block copolymers A-1 to A-7, the peak molecular weight (10,000) of the block copolymer, and the peak molecular weight (10,000) of the styrene block.

(Block copolymer B-1)
After completion of the same polymerization reaction as in A-1, dimethyldimethoxysilane as a coupling agent was added to the polymerization vessel in an equivalent amount to n-butyllithium to cause a coupling reaction, and then 2- [1- (2 -Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate with respect to 100 parts by mass of the block copolymer, Block copolymer B-1 was obtained.

(Block copolymer B-2)
After completion of the same polymerization reaction as in A-2, an equivalent amount of dimethyldimethoxysilane as a coupling agent to n-butyllithium was added to the polymerization vessel to cause a coupling reaction, and then 2- [1- (2 -Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate with respect to 100 parts by mass of the block copolymer, Block copolymer B-2 was obtained.

(Block copolymer B-3)
After completion of the polymerization reaction similar to A-3, an equivalent amount of dimethyldimethoxysilane as a coupling agent to n-butyllithium was added to the polymerization vessel to cause a coupling reaction, and then 2- [1- (2 -Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate with respect to 100 parts by mass of the block copolymer, Block copolymer B-3 was obtained.

(Block copolymer B-4)
After completion of the same polymerization reaction as in A-4, an equivalent amount of dimethyldimethoxysilane as a coupling agent was added to the polymerization vessel with respect to n-butyllithium, and a coupling reaction was performed, followed by 2- [1- (2 -Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate with respect to 100 parts by mass of the block copolymer, Block copolymer B-4 was obtained.

(Block copolymer B-5)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 19 parts by mass of styrene, 0.049 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 25 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 62 parts by mass of 1,3-butadiene at 65 ° C. for 75 minutes.
Next, a cyclohexane solution containing 19 parts by mass of styrene was continuously supplied at 65 ° C. for 25 minutes for polymerization.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer B-5.

(Block copolymer B-6)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 48 parts by mass of styrene, 0.07 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 60 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 52 parts by mass of 1,3-butadiene at 65 ° C. for 65 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer B-6.

(Block copolymer B-7)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 11 parts by mass of styrene, 0.08 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously supplying at 65 ° C. for 15 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 35 parts by mass of 1,3-butadiene at 65 ° C. for 45 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 10 parts by mass of styrene at 65 ° C. for 15 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 34 parts by mass of 1,3-butadiene at 65 ° C. for 45 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 10 parts by mass of styrene at 65 ° C. for 15 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-di-t-pentylphenyl acrylate was added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer to obtain block copolymer B-7.

  Table 2 shows the styrene content (% by mass) of the block copolymers B-1 to B-7, the peak molecular weight (10,000) of the block copolymer, and the peak molecular weight (10,000) of the styrene block.

(Block copolymer C-1)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 25 parts by mass of styrene, 0.067 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 30 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 36 parts by mass of 1,3-butadiene and 14 parts by mass of styrene at 65 ° C. for 65 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 25 parts by mass of styrene at 65 ° C. for 30 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-Di-t-pentylphenyl acrylate was added in an amount of 0.5 parts by mass with respect to 100 parts by mass of the block copolymer. Then, after solvent removal, it pelletized and the block copolymer C-1 was obtained.

(Block copolymer C-2)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 29 parts by mass of styrene, 0.058 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 35 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 27 parts by mass of 1,3-butadiene and 16 parts by mass of styrene at 65 ° C. for 55 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 28 parts by mass of styrene at 65 ° C. for 35 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-Di-t-pentylphenyl acrylate was added in an amount of 0.5 parts by mass with respect to 100 parts by mass of the block copolymer. Then, after removing the solvent, it was pelletized to obtain a block copolymer C-2.

(Block copolymer C-3)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 32 parts by mass of styrene, 0.053 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 40 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 12 parts by mass of 1,3-butadiene and 24 parts by mass of styrene at 65 ° C. for 50 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 32 parts by mass of styrene at 65 ° C. for 40 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-Di-t-pentylphenyl acrylate was added in an amount of 0.5 parts by mass with respect to 100 parts by mass of the block copolymer. Then, after removing the solvent, it was pelletized to obtain a block copolymer C-3.
Table 3 shows the styrene content (% by mass) of the block copolymers C-1 to C-3, the peak molecular weight (10,000) of the block copolymer, and the peak molecular weight (10,000) of the styrene block.

(Block copolymer D-1)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 10 parts by mass of styrene, 0.052 parts by mass of n-butyllithium and tetramethylethylenediamine 0.3 times that of n-butyllithium Mole was added and polymerization was carried out by continuously supplying at 65 ° C. for 15 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 13 parts by mass of 1,3-butadiene and 52 parts by mass of styrene at 65 ° C. for 80 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 25 parts by mass of styrene at 65 ° C. for 35 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-Di-t-pentylphenyl acrylate was added in an amount of 0.5 parts by mass with respect to 100 parts by mass of the block copolymer. Then, after solvent removal, it pelletized and the block copolymer D-1 was obtained.

(Block copolymer D-2)
Using an autoclave equipped with a stirrer, in a nitrogen gas atmosphere, in a cyclohexane solution containing 12 parts by mass of styrene, 0.047 parts by mass of n-butyllithium and 0.3 times that of tetramethylethylenediamine with respect to n-butyllithium Mole was added and polymerization was carried out by continuously feeding at 65 ° C. for 18 minutes.
Next, polymerization was performed by continuously supplying a cyclohexane solution containing 9 parts by mass of 1,3-butadiene and 66 parts by mass of styrene at 65 ° C. for 85 minutes.
Next, polymerization was carried out by continuously supplying a cyclohexane solution containing 13 parts by mass of styrene at 65 ° C. for 20 minutes.
After completion of the reaction, methanol was added to the polymerizer in an equimolar amount with respect to n-butyllithium, and then 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4 as a stabilizer. , 6-Di-t-pentylphenyl acrylate was added in an amount of 0.5 parts by mass with respect to 100 parts by mass of the block copolymer. Then, after removing the solvent, it was pelletized to obtain a block copolymer D-2.

  Table 4 shows the styrene content (mass%) of the block copolymers D-1 and D-2, the number average molecular weight (10,000), and the block ratio (%) of the block copolymer.

<Production of vinyl aromatic hydrocarbon polymer>
Vinyl aromatic hydrocarbon polymers E-1 and E-2 were prepared.
To a 10 L autoclave with a stirrer, 5 kg of styrene and n-butyl acrylate were added at the ratio shown in Table 5 below, and at the same time, 0.3 kg of ethylbenzene and 1,1 bis (t-butylperoxy to adjust MFR ) A predetermined amount of cyclohexane was charged, polymerized at 110 to 150 ° C. for 2 to 10 hours, and then unreacted styrene, n-butyl acrylate and ethylbenzene were collected and produced by a vent extruder.
The MFR of the obtained E-1 was 3.0 g / 10 min. The MFR of E-2 was 2.6 g / 10 min.
Table 5 shows the styrene content (% by mass) of the vinyl aromatic hydrocarbon polymers E-1 and E-2.

[Examples 1-9, Comparative Examples 1-8]
The block copolymers (A), (B), and (C) shown in Tables 6 and 7 are used as the adhesive layer, and the block copolymers (C) and (D) shown in Tables 6 and 7 are used as the intermediate layer. Using a polymer, a polyester resin as a surface layer (copolymerized polyester consisting of 100 mol% of dicarboxylic acid component, 70 mol% of glycol component, 30 mol% of 1,4-cyclohexanedimethanol, refractive index 1.568, trade name PETG6763, manufactured by Eastman Chemical Co.) was used.
The amount of extrusion was melted with an extruder set in the range of 210 ° C. to 230 ° C. at a ratio of intermediate layer: adhesive layer: surface layer = 7: 1: 2, merged at the die, and 3 layers and 5 layers (Laminate ratio (surface layer: adhesive layer: intermediate layer: adhesive layer: surface layer) = 1: 0.5: 7: 0.5: 1), cooled with a cast roll, and with a thickness of 0.3 mm An unstretched film was obtained.
In Comparative Example 8, an unstretched film was prepared with two layers and three layers of intermediate layer: surface layer = 7: 3 (lamination ratio (surface layer: intermediate layer: surface layer) = 1.5: 7: 1.5).
This unstretched film was stretched 1.3 times in the machine direction (MD) at 70 ° C., and then stretched 4.5 times in the perpendicular direction (TD) at 90 ° C. to produce a film having a thickness of about 50 μm.
The block copolymers (A) and (B) used for the adhesive layer were mixed in the form of a solution and then pelletized after solvent removal.
The physical property results of the obtained film are shown in Table 8 and Table 9. As is clear from the results shown in Tables 8 and 9, the heat-shrinkable laminated films of the present embodiment (Examples 1 to 9) are excellent in low-temperature shrinkage, rigidity, elongation, transparency, and peel strength, and are shrink-wrapped. It was found to be suitable for shrink-bound packaging and shrink labels.

  The heat-shrinkable laminated film of the present invention has industrial applicability as shrink wrap, shrink-bound wrap, shrink labels, and the like.

Claims (9)

A heat-shrinkable laminated film including an adhesive layer between the surface layer and the intermediate layer and stretched in at least a uniaxial direction,
The surface layer includes at least one polyester-based resin;
The intermediate layer includes a block copolymer comprising at least one polymer block A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B of conjugated diene,
The adhesive layer comprises 50 to 80% by mass of a block copolymer (A) composed of a vinyl aromatic hydrocarbon and a conjugated diene, and 20 to 50% by mass of a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene. A block copolymer mixture comprising a polymer (B),
The block copolymer (A) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, and has a peak molecular weight of 30,000 to 70,000 as measured by GPC. Having at least one peak molecular weight of the aromatic hydrocarbon polymer block in the range of 10,000 to 30,000,
The block copolymer (B) has a vinyl aromatic hydrocarbon content of 30 to 50% by mass and a conjugated diene content of 50 to 70% by mass, the peak molecular weight by GPC measurement is more than 70,000 and not more than 130,000, A heat-shrinkable laminated film having at least one peak molecular weight of the vinyl aromatic hydrocarbon polymer block in the range of 10,000 to 30,000.   The heat according to claim 1, wherein the block copolymer mixture comprises 55 to 75 mass% of the block copolymer (A) and 25 to 45 mass% of the block copolymer (B). Shrinkable laminated film. The adhesive layer includes the block copolymer mixture, and a block copolymer (C) composed of a vinyl aromatic hydrocarbon and a conjugated diene,
The block copolymer (C) has a vinyl aromatic hydrocarbon content of 60 to 95% by mass and a conjugated diene content of 5 to 40% by mass, and has a peak molecular weight of 50,000 to 500,000 as measured by GPC. Having at least one peak molecular weight of the aromatic hydrocarbon polymer block in the range of 10,000 to 100,000,
The heat-shrinkable laminate according to claim 1 or 2, wherein the adhesive layer has a vinyl aromatic hydrocarbon content of more than 50% by mass and 80% by mass or less, and a conjugated diene content of 20% by mass to less than 50% by mass. the film.   The heat according to any one of claims 1 to 3, wherein the block copolymer (B) is a block copolymer obtained from the block copolymer (A) using a non-halogen coupling agent. Shrinkable laminated film. 5. The intermediate layer according to claim 1, wherein the intermediate layer further contains 0.1 to 80% by mass of at least one vinyl aromatic hydrocarbon polymer selected from the group consisting of the following (a) to (c). The heat-shrinkable laminated film according to any one of the above.
(A) Styrenic polymer (b) At least one kind of aliphatic hydrocarbon selected from vinyl aromatic hydrocarbons and aliphatic unsaturated carboxylic acids, aliphatic unsaturated carboxylic acid anhydrides and aliphatic unsaturated carboxylic acid esters Copolymer with saturated carboxylic acid or derivative thereof (c) Rubber-modified styrene polymer The polyester resin is composed of a dicarboxylic acid component and a diol component,
The dicarboxylic acid component and the diol component each include a main component in an amount of 60 to 100 mol% with respect to the total amount (100 mol% of each), and the total amount of the other components is the dicarboxylic acid component. It is 10-40 mol% with respect to the sum total (200 mol%) of the total amount (100 mol%) of this, and the total amount (100 mol%) of the said diol component, As described in any one of Claims 1 thru | or 5 Heat shrinkable laminated film.   The heat-shrinkable laminate according to claim 6, wherein the main component of the dicarboxylic acid is terephthalic acid, the main component of the diol component is ethylene glycol, and the other component is 1,4-cyclohexanedimethanol. the film.   The amount of the 1,4-cyclohexanedimethanol is 10 to 40 mol% based on the total (200 mol%) of the total amount (100 mol%) of the dicarboxylic acid component and the total amount (100 mol%) of the diol component. The heat-shrinkable laminated film according to claim 6 or 7, wherein   The heat-shrinkable laminated film according to any one of claims 1 to 8, wherein the intermediate layer further comprises 3 to 30% by mass of a polyester-based resin.