JP7172694B2 - Laminated films, heat-shrinkable laminated films, packaging materials, molded products, containers - Google Patents

Description

The present invention is suitable for food packaging materials, beverage packaging materials, pharmaceutical and medical packaging materials, chemical packaging materials, cosmetic packaging materials, toiletry packaging materials, industrial packaging materials, agricultural material packaging materials, and the like. Laminated films, heat-shrinkable laminated films, packaging materials, molded articles, and containers that can be used for

Currently, most beverages such as tea, juice, and coffee are sold in containers such as PET bottles, and in recent years, alcoholic beverages such as wine have also been sold in PET bottles. As diversity increases, heat-shrinkable films are becoming more important to differentiate products from other products and improve visibility. Moreover, heat-shrinkable films are used not only for beverages but also for various applications ranging from foods, toiletries, medical products, chemicals, and industrial products.

For the above applications, polyester-based heat-shrinkable films, which are rigid at room temperature, excellent in heat resistance and solvent resistance, and low in natural shrinkage, are mainly used. However, the polyester-based heat-shrinkable film has the problem that it shrinks more rapidly than the polystyrene-based heat-shrinkable film. In addition, shrink films are often provided with perforations for the purpose of easily peeling the shrink label from the container after use. may not be easily removed from the

On the other hand, polystyrene-based heat-shrinkable films having excellent low-temperature shrinkability are also widely used. However, the polystyrene heat-shrinkable film has a low low-temperature elongation, and there is a problem that the label attached to the container is broken when accidentally dropped during refrigerated storage. In addition, polystyrene heat-shrinkable film has insufficient solvent resistance, so when printing with ordinary organic solvent-based gravure ink, the film curls and the amount of solvent remaining on the label increases, resulting in printing problems. In many cases, blocking occurred later and an organic solvent odor was generated.

As a means for solving the above problems, for example, Patent Document 1 discloses a heat transfer layer having front and back layers containing a polyester resin on both sides of an intermediate layer containing a block copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon. Shrink laminated films are disclosed. Further, Patent Document 2 discloses a heat-shrinkable laminate film having a surface layer containing a polyester resin as a main component, an intermediate layer containing a styrene resin as a main component, and an adhesive layer. , a mixture containing a resin used for a surface layer and an intermediate layer, a laminated film using a soft styrene resin, a modified styrene resin, or the like is disclosed. Furthermore, in Patent Document 3, a layer containing a polyester resin and a polystyrene resin is provided between a layer containing a polyester resin as a main component and a layer containing a polyester resin and a polystyrene resin. A heat-shrinkable laminated film having

JP 2005-131824 A JP 2006-15745 A JP 2010-264657 A

However, the heat-shrinkable laminated film disclosed in Patent Document 1 may cause peeling between the surface layer and the back layer due to rubbing between the films during transportation or scratching with human nails, etc. There were some troubles. Also, in the heat-shrinkable laminated films disclosed in Patent Documents 2 and 3, one layer adjacent to the adhesive layer has good interlayer adhesive strength, but the interlayer adhesive strength to the other adjacent layer is low. In some cases, the adhesive strength is lowered, and further improvement of the interlayer adhesive strength has been required.

The present invention has been made to solve the above problems, and comprises a resin composition that exhibits high interlaminar adhesive strength in both a layer containing a polyester-based resin as a main component and a layer containing a polystyrene-based resin as a main component. An object of the present invention is to provide a laminated film having layers. Another object of the present invention is to provide a heat-shrinkable laminated film excellent in heat-shrinkability, transparency, and interlayer adhesion, a packaging material using the heat-shrinkable laminated film, and a molded article or container fitted with the packaging material.

As a result of intensive studies, the present inventors succeeded in obtaining a laminated film and a heat-shrinkable film that can solve the above-described problems of the prior art, and completed the present invention.

That is, the present invention provides a (I) layer made of a resin composition containing a polyester resin (A) as a main component, a (II) layer made of a resin composition containing a polystyrene resin (B) as a main component, a polyurethane-based At least three layers in which (III) layers made of a resin composition containing a resin component (C-1) and a polystyrene resin component (C-2) are adjacent in the order of (I)/(III)/(II) It is a laminated film having

In the laminated film, the polyester resin (A) preferably contains a terephthalic acid residue as a dicarboxylic acid residue.

In the laminated film, the polyester resin (A) preferably contains an ethylene glycol residue as a diol residue.

In the laminated film, the polyester-based resin (A) preferably contains a 1,4-cyclohexanedimethanol residue as a diol residue.

In the laminated film, the content of the aromatic vinyl hydrocarbon in the polystyrene-based resin (B) is preferably 50% by mass or more.

In the laminated film, the polystyrene resin (B) is preferably an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer.

In the laminated film, the main component of the isocyanate constituting the polyurethane resin component (C-1) is preferably an aromatic isocyanate.

In the laminated film, when the polystyrene resin component (C-2) is 100% by mass, the content of the aromatic vinyl hydrocarbon in the polystyrene resin component (C-2) is 1% by mass or more and 50% by mass. The following are preferable.

In the laminated film, it is preferable that the interlayer peel strength is 0.5 N/10 mm width or more at a test speed of 50 mm/min by a T-type peel method in an environment of 23° C. and 50% RH.

In the laminated film, when the resin composition constituting the (III) layer is 100% by mass, the polyurethane resin component (C-1) is 10% by mass or more and 80% by mass or less, and the polystyrene resin It is preferable that the component (C-2) is 10% by mass or more and 80% by mass, and the total of the above (C-1) and the above (C-2) is 50% by mass or more and 100% by mass or less.

The present invention provides a heat-shrinkable laminated film obtained by stretching the laminated film according to any one of the above in at least one direction, wherein the heat shrinkage rate in the main shrinkage direction when immersed in hot water at 100 ° C. for 10 seconds is It is a heat-shrinkable laminate film with a shrinkage ratio of 30% or more.

The present invention is a packaging material using the heat-shrinkable laminated film.

The present invention is a molded article or container fitted with the packaging material.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to obtain a laminated film having an adhesive layer exhibiting high interlaminar adhesive strength in both a layer containing a polyester-based resin as a main component and a layer containing a polystyrene-based resin as a main component. It can be suitably used for packaging materials, beverage packaging materials, pharmaceutical and medical packaging materials, chemical packaging materials, cosmetic packaging materials, toiletry packaging materials, industrial packaging materials, agricultural material packaging materials, etc. . In addition, by stretching the laminated film in at least one direction, it is possible to obtain a heat-shrinkable laminated film having excellent heat-shrinkable properties, transparency, and interlayer adhesion. .

Hereinafter, the laminated film of the present invention, the heat-shrinkable laminated film of the present invention, the packaging material, the molded product, and the container will be described as examples of embodiments of the present invention. However, the scope of the present invention is not limited to the embodiments described below.

In this specification, the term “main component” refers to a component that accounts for 50% by mass or more when the total of the components constituting each layer is 100% by mass, preferably 60% by mass or more, and 70% by mass. % or more is more preferable.
In addition, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less", "preferably larger than X" and "preferably smaller than Y" ” is included.
In addition, the upper limit and lower limit of the numerical range in this specification, even if slightly deviating from the numerical range specified by the present invention, as long as it has the same effect as within the numerical range, the present invention shall be included in the equivalent range of

<Laminated film>
The laminated film of the present invention includes a (I) layer made of a resin composition containing a polyester resin (A) as a main component, a (II) layer made of a resin composition containing a polystyrene resin (B) as a main component, a polyurethane At least three layers (III) made of a resin composition containing a resin component (C-1) and a polystyrene resin component (C-2) are adjacent in the order of (I) / (III) / (II) It is a laminated film having layers.

<(I) Layer>
In the present invention, the layer (I) is a layer made of a resin composition containing a polyester resin (A) as a main component.

(Polyester resin (A))
The type of the polyester resin (A) used in the present invention is not particularly limited as long as it is a resin having an ester bond in its main chain. For example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polytrimethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene succinate, polybutylene succinate, polylactic acid, poly-ε -Polyester resins such as caprolactam and the like can be mentioned. Among them, polyester-based resins derived from both a dicarboxylic acid residue and a polyhydric alcohol residue, such as polyethylene terephthalate and polybutylene terephthalate, are preferred.

The polyester-based resin (A) that can be suitably used in the present invention is a polyester-based resin derived from a dicarboxylic acid residue and a diol residue.
Examples of dicarboxylic acid residues are terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbenedicarboxylic acid, 4,4-biphenyldicarboxylic acid. , orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4-diphenyletherdicarboxylic acid, 4,4-di phenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, aromatic dicarboxylic acids such as ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3-cyclohexanedicarboxylic acid, 1, Examples include residues derived from aliphatic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid or ester derivatives thereof. These dicarboxylic acid residues may be used singly or in combination of two or more. Among them, it is preferable that the polyester-based resin (A) contains a terephthalic acid residue as a dicarboxylic acid residue.

Examples of diol residues are ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, spiroglycol, 2,2 , 4,4-tetramethyl-1,3-cyclobutanediol and isosorbide. These diol residues may contain one type alone or two or more types. Among them, the polyester-based resin (A) preferably contains an ethylene glycol residue or a 1,4-cyclohexanedimethanol residue as a diol residue.

In the present invention, at least one of the dicarboxylic acid residue and the diol residue is more preferably a mixture of two or more residues. In the present specification, in the two or more kinds of residues, the main residue, i.e., the one with the highest mass (mol%) is the first residue, and the second residue is the one with a smaller amount than the first residue. Let the following residues (that is, the second residue, the third residue, . . . ) be used. By making the dicarboxylic acid residue and the diol residue into such a mixture system, the crystallinity of the obtained polyester-based resin (A) can be lowered, so that the progress of crystallization can be suppressed, which is preferable.

Preferred mixtures of diol residues include, for example, the ethylene glycol residue as the first residue and 1,3-propanediol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and polytetramethylene as the second residue. a residue derived from at least one selected from the group consisting of glycol, 1,4-cyclohexanedimethanol, spiroglycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and isosorbide, preferably 1 , 4-cyclohexanedimethanol residue as the second residue.

A preferred mixture of dicarboxylic acid residues includes, for example, a terephthalic acid residue as the first residue and isophthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid and adipic acid as the second residue. A residue derived from at least one selected from the group consisting of, preferably, an isophthalic acid residue is used as the second residue.

The content of the total amount of dicarboxylic acid residues and diol residues below the second residue is the sum of the total amount (100 mol%) of the dicarboxylic acid residues and the total amount (100 mol%) of the diol residues ( 200 mol %), it is 10 mol % or more, preferably 20 mol % or more, and 40 mol % or less, preferably 35 mol % or less. When the content of residues having two residues or less is 10 mol % or more, the crystallinity of the resulting polyester can be kept low. On the other hand, if the content of the two residues or less is 40 mol % or less, the advantage of the first residue can be utilized.

For example, when the dicarboxylic acid residue is a terephthalic acid residue, the first residue of the diol residue is an ethylene glycol residue, and the second residue is a 1,4-cyclohexanedimethanol residue, the second residue The content of 1,4-cyclohexanedimethanol residues is the total amount (100 mol%) of terephthalic acid residues, which are dicarboxylic acid residues, and the content of ethylene glycol residues and 1,4-cyclohexanedimethanol residues. 10 mol% or more, preferably 15 mol% or more, more preferably 25 mol% or more, and 40 mol% or less, preferably 38 mol%, based on the total (200 mol%) of the total amount (100 mol%) The range is 35 mol % or less, and more preferably 35 mol % or less. By using an ethylene glycol residue and a 1,4-cyclohexanedimethanol residue as the diol residue within this range, the crystallinity of the obtained polyester is almost eliminated and the fracture resistance can be improved. Therefore, the polyester-based resin (A) preferably contains an ethylene glycol residue as a diol residue. Further, in the laminated film, the polyester-based resin (A) preferably contains a 1,4-cyclohexanedimethanol residue as a diol residue.

Furthermore, in the above example, when the dicarboxylic acid residue consists of a terephthalic acid residue as the first residue and an isophthalic acid residue as the second residue, the isophthalic acid residue and the diol residue are dicarboxylic acid residues. The content of 1,4-cyclohexanedimethanol residues is the total amount of terephthalic acid residues and isophthalic acid residues (100 mol%) and the total amount of ethylene glycol residues and 1,4-cyclohexanedimethanol residues. 10 mol% or more, preferably 15 mol% or more, more preferably 25 mol% or more, and 40 mol% or less, preferably 38 mol% or less, relative to the total (200 mol%) of (100 mol%); More preferably, it is in the range of 35 mol % or less.

The refractive index (n1) of the polyester resin (A) is preferably 1.560 or more and 1.580 or less, preferably 1.565 or more and 1.574 or less.

The intrinsic viscosity (IV) of the polyester resin (A) is 0.5 dl/g or more, preferably 0.6 dl/g or more, more preferably 0.7 dl/g or more, and 1.5 dl/g or less. , preferably 1.2 dl/g or less, more preferably 1.0 dl/g or less. When the intrinsic viscosity (IV) is 0.5 dl/g or more, deterioration of film strength characteristics and heat resistance can be suppressed. On the other hand, when the intrinsic viscosity is 1.5 dl/g or less, it is possible to prevent breakage due to an increase in drawing tension.

Examples of commercially available polyester-based resins (A) include "PETGcopolyester" (manufactured by Eastman Chemical Co.), "Embrace" (manufactured by Eastman Chemical Co.), and "PETGSKYGREEN" (manufactured by SK Chemical Co.).

From the viewpoint of imparting heat resistance, etc., it is also preferable to use at least one of a polyethylene terephthalate-based copolymer and a polybutylene terephthalate-based copolymer as the polyester resin (A). It is also preferable to use a mixture of a polyethylene terephthalate-based copolymer and a polybutylene terephthalate-based copolymer as the polyester-based resin (A).

In imparting heat shrinkability, the heat shrink behavior can be adjusted by using at least one of the polyethylene terephthalate-based copolymer and the polybutylene terephthalate-based copolymer. That is, since the glass transition temperature (Tg) of the polyethylene terephthalate-based copolymer and the Tg of the polybutylene terephthalate-based copolymer are greatly different, the temperature range in which the thermal shrinkage rate increases can be expanded by mixing the two. , As a result, rapid shrinkage from the start of heat shrinkage can be suppressed.

Crystallinity can also be controlled by using at least one of the polyethylene terephthalate-based copolymer and the polybutylene terephthalate-based copolymer. Therefore, inhibition of thermal shrinkage due to excessive crystallization can be suppressed, and sufficient shrinkage can be imparted while imparting heat resistance.

Further, as the polyester resin (A) used in the present invention, in addition to the polyester resin derived from the dicarboxylic acid residue and the diol residue, a carboxylic acid residue and an alcohol residue are contained in one molecule. It is also possible to use a polyester resin obtained by polymerizing a monomer possessed in the above. In particular, polylactic acid and poly-ε-caprolactam are preferably used because they impart rigidity, low-temperature shrinkability, and low natural shrinkage.

The (I) layer of the laminated film of the present invention is preferably the outermost layer from the viewpoints of maintaining the rigidity of the film, suppressing natural shrinkage, and improving solvent resistance. When layer (I) is the outermost layer, the film curls when printed with a conventional organic solvent-based gravure ink, and the amount of solvent remaining on the label increases, causing blocking after printing. It is preferable because it is less likely to generate an organic solvent odor.

When the (I) layer of the laminated film of the present invention is the outermost layer, a method of blending an incompatible resin into the layer constituting the outermost layer of the film for the slipperiness of the film and blocking prevention, or an anti-blocking It is preferable to add what is called an agent.

Examples of the antiblocking agent include inorganic particles such as silica, talc, and calcium carbonate, inorganic oxides, carbonates, and organic particles such as crosslinked acrylic, crosslinked polyester, crosslinked polystyrene, and silicone. . Further, organic particles having a multi-layered structure polymerized in multiple stages can also be used. Among them, silica and organic particles are preferably used.

Since the anti-blocking agent roughens the film surface to develop slipperiness and anti-blocking properties, the transparency and glossiness of the film are impaired unless an appropriate addition amount and type are selected. The same applies to the laminated film in which the (I) layer is the outermost layer. The amount of the antiblocking agent added is preferably 0.01% by mass or more and 2% by mass or less, based on the mass of the entire resin composition constituting the layer (I) (100% by mass), and preferably 0.015%. It is more preferably 1.5% by mass or less, and even more preferably 0.02% by mass or more and 1% by mass or less. If the amount of the antiblocking agent added is too small, the antiblocking agent is difficult to deposit on the film surface, making it difficult to form irregularities on the film surface, making it difficult to exhibit sufficient slipperiness and blocking resistance. On the other hand, if it is too large, the film surface tends to be excessively uneven, the transparency is hindered due to surface roughening, and the film roll tends to be unwound due to excessive lubricity.

The shape of the anti-blocking agent is not particularly limited, but (I) from the viewpoint of suppression of aggregation in the layer, uniform dispersion, suppression of diffuse reflection of transmitted light, and unevenness formed on the film surface. A spherical one is preferably used. The particle size of the antiblocking agent is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 8 μm or less, and even more preferably 1 μm or more and 6 μm or less. If the particle size of the anti-blocking agent is too small, it is difficult to deposit on the surface, and even the anti-blocking agent deposited on the surface is difficult to impart sufficient unevenness to exhibit slipperiness and anti-blocking properties. On the other hand, if the particle size of the anti-blocking agent is too large, when the film of the present invention is printed to enhance the design, ink loss tends to occur, which is undesirable because the appearance of the printed pattern is impaired. Although the particle size distribution of the anti-blocking agent is not particularly limited, it is preferable that the particle size distribution is narrow because of the adverse effects caused by the size of the particle size. If the particle size distribution is too wide, it is not preferable because it may include particles outside the range of particle sizes that are preferably used as described above.

<(II) layer>
In the present invention, the (II) layer is a layer made of a resin composition containing polystyrene resin (B) as a main component.

(Polystyrene resin (B))
The type of polystyrene resin (B) used in the present invention is not particularly limited as long as it is a resin having an aromatic vinyl hydrocarbon. Aromatic vinyl hydrocarbons include, for example, polystyrene, poly(p-, m- or o-methylstyrene), poly(2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene) , polyalkylstyrene such as poly(pt-butylstyrene); poly(o-, m- or p-chlorostyrene), poly(o-, m- or p-bromostyrene), poly(o-, m - or p-fluorostyrene), polyhalogenated styrenes such as poly(o-methyl-p-fluorostyrene); polyhalogenated substituted alkylstyrenes such as poly(o-, m- or p-chloromethylstyrene); (p-, m- or o-methoxystyrene), polyalkoxystyrenes such as poly (o-, m- or p-ethoxystyrene); polys such as poly (o-, m- or p-carboxymethylstyrene) carboxyalkylstyrene; polyalkyletherstyrene such as poly(p-vinylbenzylpropyl ether); polyalkylsilylstyrene such as poly(p-trimethylsilylstyrene); and polyvinylbenzyldimethoxyphosphide. The polystyrene-based resin (B) may contain homopolymers and copolymers of these aromatic vinyl hydrocarbons and/or copolymerizable monomers other than the aromatic vinyl hydrocarbons. In the present invention, from the viewpoint of the rigidity of the laminated film, the content of the aromatic vinyl hydrocarbon in the polystyrene resin (B) is preferably 50% by mass or more.

From the viewpoint of shrinkage properties, the polystyrene resin (B) is preferably an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer. Examples of conjugated diene hydrocarbons include butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene. When the polystyrene resin (B) is an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, the conjugated diene hydrocarbon block is a homopolymer, copolymer and / Or a copolymerizable monomer other than the conjugated diene hydrocarbon may be included in the block.

One of the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymers preferably used in the layer (II) of the present invention is one in which the aromatic vinyl hydrocarbon is styrene and the conjugated diene hydrocarbon is butadiene. , and styrene-butadiene block copolymers (SBS). SBS preferably has a styrene/butadiene mass% ratio of about (95-60)/(5-40), more preferably (93-60)/(7-40), and (90- More preferably, it is about 60)/(10 to 40). Furthermore, the measured melt flow rate (MFR) of SBS (measurement conditions: temperature 200° C., load 49 N) is 2 g/10 minutes or more, preferably 3 g/10 minutes or more, and 15 g/10 minutes or less, preferably It is desirable to be 10 g/10 minutes or less, more preferably 8 g/10 minutes or less.

A styrene-isoprene-butadiene block copolymer (SIBS) is also preferably used as the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer preferably used in the layer (II) of the present invention. In SIBS, the mass% ratio of styrene/isoprene/butadiene is preferably (60-90)/(5-40)/(5-30), (60-85)/(10-30)/( 5 to 25), more preferably (60 to 80)/(10 to 25)/(5 to 20). Furthermore, the melt flow rate (MFR) measurement value of SIBS (measurement conditions: temperature 200 ° C., load 49 N) is 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and 15 g / 10 minutes or less, preferably It is desirable to be 10 g/10 minutes or less, more preferably 8 g/10 minutes or less. If the butadiene content is high and the isoprene content is low, the butadiene heated in the extruder or the like causes a cross-linking reaction, which may increase the amount of gel. On the other hand, when the content of butadiene is low and the content of isoprene is high, the cross-linking reaction of butadiene may be suppressed, and the formation of gel may be suppressed.

The polystyrene resin (B) used in layer (II) of the present invention is not limited to a single substance, and may be a mixture of two or more. For example, when the polystyrene resin (B) is a mixture of SBS and SIBS, the mass% ratio of SBS/SIBS is preferably about (90 to 10)/(10 to 90), and (80 to 20 )/(20 to 80), and more preferably (70 to 30)/(30 to 70).
Further, when general-purpose polystyrene (GPPS) is contained in the polystyrene resin (B) used in the (II) layer of the present invention, the Tg (peak temperature of loss elastic modulus E″) of GPPS is as high as about 100°C. Therefore, from the viewpoint of heat shrinkability, the content of GPPS to be mixed should be 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less of the total amount of resins constituting the layer (II). is desirable.

In addition, the (II) layer of the present invention may be a resin composition containing a polystyrene resin (B) as a main component, and the (II) layer may be mixed with a resin other than the polystyrene resin (B). can also Examples of such resins will be described later, but from the viewpoint of adding as a recycled resin generated from trimming loss such as the edge of the laminated film, it is possible to mix the polyester resin (A) used in the layer (I) described above. more preferred.

When the polystyrene resin (B) of the present invention is an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, the refractive index (n2) of the block copolymer measured according to JIS K7142 is (II) It is desirable that the refractive index (n1) of the polyester resin (A) that can be preferably mixed in the layer is within the range of ±0.02, preferably ±0.015. That is, from the preferable refractive index (n1) of the polyester resin (A) described above, the refractive index (n2) of the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer used is 1.540 or more and 1.600. The following is preferable, more preferably 1.550 or more and 1.590 or less, and still more preferably 1.555 or more and 1.585 or less. Thus, when the difference between the refractive index (n2) of the polystyrene-based resin (B) and the refractive index (n1) of the polyester-based resin (A) is adjusted within a predetermined range, and kneaded to form a film. Also in, a film having good transparency can be obtained.

In the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, the refractive index (n2) is adjusted to approximately the desired value by appropriately adjusting the composition ratio of the styrene hydrocarbon and the conjugated diene hydrocarbon. can. Therefore, by adjusting the composition ratio of the aromatic vinyl hydrocarbon and the conjugated diene hydrocarbon corresponding to the refractive index (n1) of the polyester resin (A) that can be preferably mixed in the (II) layer ( A refractive index (n2) within the range of n1)±0.02 is obtained. This predetermined refractive index may be adjusted by using the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer alone, or by mixing two or more resins.

In the present invention, the storage elastic modulus (E′) of the polystyrene resin (B) used for the layer (II) at a vibration frequency of 10 Hz, a strain of 0.1%, and 0° C. is 1.00×10 ⁹ Pa or more. is preferable, and 1.50×10 ⁹ Pa or more is more preferable. The storage modulus (E′) at 0° C. represents the stiffness of the film, that is, the stiffness of the film. By having a storage elastic modulus (E′) of 1.00×10 ⁹ Pa or more, a film having transparency and rigidity can be obtained. This storage modulus (E') can be adjusted by the content of the aromatic vinyl hydrocarbon in the polystyrene resin (B) used in the layer (II). Therefore, in the present invention, from the viewpoint of the rigidity of the laminated film, the content of the aromatic vinyl hydrocarbon in the polystyrene resin (B) is preferably 50% by mass or more.

When the polystyrene resin (B) uses a mixture of an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, or a mixture of the copolymer and another resin, it is responsible for breaking resistance. Good results can be obtained by appropriately selecting the copolymer or resin and the copolymer or resin responsible for rigidity. That is, by combining an aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbon copolymer having high fracture resistance and an aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbon copolymer having high rigidity, By mixing aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbon copolymers having fracture resistance with other types of resins having high rigidity, these aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbons The total composition of the copolymers, or mixtures thereof with other types of resins, can be adjusted to meet the desired refractive index (n2) and storage modulus at 0°C (E').

Pure block SBS and random block SBS are preferred as the aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer capable of imparting breakage resistance. Among them, the storage modulus (E′) at 0° C. is 1.00×10 ⁸ Pa or more and 1.00×10 ⁹ Pa or less, and at least one peak temperature of the loss modulus (E″) is −20. It is particularly preferable to have viscoelastic properties below 0° C. If the storage elastic modulus at 0° C. is 1.0×10 ⁸ Pa or more, stiffness is imparted by increasing the blend amount of the resin responsible for rigidity. On the other hand, at the peak temperature of the loss modulus (E″), the temperature on the low temperature side mainly shows fracture resistance. Although this property varies depending on the stretching conditions, if the peak temperature of the loss elastic modulus (E″) does not exist below −20° C. in the state before stretching, it is difficult to impart sufficient film breakability to the laminated film. may become.

In addition, as a resin capable of imparting rigidity, an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer having a storage modulus (E′) at 0° C. of 2.00×10 ⁹ Pa or more, such as a block structure controlled aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, polystyrene (GPPS), aromatic vinyl hydrocarbon and aliphatic unsaturated carboxylic acid ester copolymer.

As an aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbon copolymer with a controlled block structure, a styrene-butadiene block copolymer has a storage modulus (E′) of 2.00×10 ⁹ at 0° C. Pa or more SBS is mentioned. The styrene-butadiene composition ratio of the SBS that satisfies this is preferably adjusted to about styrene/butadiene=(95-80)/(5-20).

The structure of the block copolymer and the structure of each block portion are preferably random blocks and tapered blocks. More preferably, the loss modulus (E″) peak temperature is at 40° C. or higher, and more preferably, the loss elastic modulus (E″) peak temperature is 40° C. or lower to control the shrinkage properties. There is no temperature. When the peak temperature of the loss elastic modulus (E″) does not appear to exist up to 40° C., the storage elastic modulus characteristics are almost the same as those of polystyrene, so it is possible to impart rigidity to the film. The peak temperature of the loss modulus (E″) preferably exists in the range of 40° C. or higher and 90° C. or lower. This peak temperature is a factor that mainly affects the shrinkage rate, and if this temperature is in the range of 40° C. or higher and 90° C. or lower, the natural shrinkage and low-temperature shrinkage rate do not significantly decrease.

A method of polymerizing an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer that satisfies the above viscoelastic properties will be described below. Generally, after charging a portion of the aromatic vinyl hydrocarbon or conjugated diene hydrocarbon to complete the polymerization, a mixture of the aromatic vinyl hydrocarbon monomer and the conjugated diene hydrocarbon monomer is charged to continue the polymerization reaction. As a result, the conjugated diene hydrocarbon having higher polymerization activity is preferentially polymerized, and finally a block composed of a single aromatic vinyl hydrocarbon monomer is produced.

For example, if styrene is first homopolymerized, and after the polymerization is completed, a mixture of styrene and butadiene monomers is charged to continue the polymerization, the styrene/butadiene monomer ratio gradually changes between the styrene block and the butadiene block. A styrene-butadiene block copolymer having copolymer moieties is obtained. By providing such sites, a polymer having the above viscoelastic properties can be obtained. In this case, the two peaks attributed to the butadiene block and the styrene block as described above cannot be clearly confirmed, and apparently there is only one peak. In other words, in a block structure such as SBS, which is a random block in which pure blocks and butadiene blocks clearly exist, the Tg attributed to the butadiene blocks mainly exists at 0 ° C. or lower, so the storage elastic modulus at 0 ° C. ( It becomes difficult to make E') equal to or greater than a predetermined value.

The polystyrene resin (B) has a weight average molecular weight (Mw) of 100,000 or more, preferably 150,000 or more, and 500,000 or less, preferably 400,000 or less, more preferably 300,000 or less. 000 or less is desirable. If the weight average molecular weight (Mw) of the polystyrene resin (B) is 100,000 or more, it is preferable because there is no defect such as deterioration of the film. Furthermore, if the polystyrene resin (B) has a molecular weight of 500,000 or less, it is preferable because there is no need to adjust the flow characteristics and there is no drawback such as a decrease in extrudability.

When a copolymer of an aromatic vinyl hydrocarbon and an aliphatic unsaturated carboxylic acid ester is used as the polystyrene resin (B), the aliphatic unsaturated carboxylic acid ester to be copolymerized with the aromatic vinyl hydrocarbon is methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate. Preferably, it is a copolymer of styrene and butyl (meth)acrylate, more preferably, the aromatic vinyl hydrocarbon is in the range of 70% by mass or more and 90% by mass or less, and Tg (loss elastic modulus E'' of 50° C. or higher and 90° C. or lower, and a melt flow rate (MFR) measured value (measurement conditions: temperature of 200° C., load of 49 N) of 2 g/10 min or higher and 15 g/10 min or lower. Incidentally, the (meth)acrylate means acrylate and/or methacrylate.

The content in the (II) layer of the copolymer of the aromatic vinyl hydrocarbon and the aliphatic unsaturated carboxylic acid ester is not particularly limited as long as it does not exceed the range defined by the present invention, but (II ) It is adjusted in the range of 20% by mass or more and 70% by mass or less with respect to the total amount of the resin composition constituting the layer. By mixing at 70% by mass or less, the rigidity of the film can be greatly improved, and good breakage resistance can be maintained. In addition, when mixed in an amount of 20% by mass or more, sufficient rigidity can be imparted to the film.

Further, when the polyester resin (A) is mixed in the layer (II), a compatibilizer for the polyester resin (A) and the polystyrene resin (B) may be used in the layer (II). preferable.

(Compatibilizer)
The (II) layer of the film of the present invention further contains a compatibilizer that promotes compatibilization of the polyester resin (A) and the polystyrene resin (B), and the compatibilizer is the following (a) (a) styrene-based copolymer containing oxazoline group (b) styrene-maleic anhydride copolymer (c) polyester-based elastomer or modified polyester-based elastomer (d) polystyrene elastomer or modified polystyrene elastomer (e) polyurethane resin-polystyrene resin copolymer (f) graft copolymer having different trunk and branch components, wherein the trunk component or branch component of the graft copolymer is , a polyester-based resin, or a resin composition consisting of a polystyrene-based resin

The content of the compatibilizer in the (II) layer is not particularly limited as long as it does not exceed the range defined by the present invention. % by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less. If the content of the compatibilizing agent is within the above range, expected uniformity in thickness and improvement in interlayer adhesive strength can be expected, and significant deterioration in transparency can be prevented.

<(III) Layer>
In the present invention, the layer (III) is a layer made of a resin composition containing a polyurethane resin component (C-1) and a polystyrene resin component (C-2).

(Polyurethane resin component (C-1))
The polyurethane-based resin component (C-1) is a polymer component in which isocyanate and polyol are bonded via urethane bonds. Further, a copolymer component having a repeating unit of a hard segment in which an isocyanate and a chain extender are bonded via a urethane bond and a soft segment in which an isocyanate and a polyol are bonded via a urethane bond can also be used. These polymer units may be used singly or in combination of two or more.

Examples of the isocyanate component constituting the polyurethane resin component (C-1) include 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylene hexamethylene diisocyanate, lysine methyl ester diisocyanate, and methylene diisocyanate. , isopropylene diisocyanate, lysine diisocyanate, 1,5-octylene diisocyanate, dimer acid diisocyanate and other aliphatic isocyanates; 4,4′-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, methyl alicyclic isocyanates such as cyclohexane diisocyanate and isopropylidenedictohexyl-4,4'-diisocyanate; 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1, Aromatic isocyanates such as 5-naphthylene diisocyanate (NDI), xylene diisocyanate (XDI), triphenylmethane triisocyanate, tris(4-phenylisocyanate) thiophosphate, tolidine diisocyanate, p-phenylene diisocyanate, diphenylether diisocyanate, diphenylsulfone diisocyanate etc. Among them, from the viewpoint of adhesion with the layer (I) made of the resin composition containing the polyester resin (A) as the main component, the main component of the isocyanate constituting the polyurethane resin component (C-1) is aromatic. An isocyanate is preferred.

Examples of the polyol component constituting the polyurethane-based resin component (C-1) include polyester-based polyols, polyester-ether-based polyols, polyether-based polyols, and polycarbonate-based polyols.

Examples of the polyester-based polyols include polyester polyols obtained by the condensation reaction of dicarboxylic acid ester compounds or acid anhydrides and diols, polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone, and the like. mentioned. Examples of the dicarboxylic acid constituting the polyester-based polyol include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid; Alicyclic dicarboxylic acids such as hydrophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid can be mentioned. The above diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl- 1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8 -octanediol, 1,9-nonanediol, 2,2-dimethylolheptane, etc., and these may be used in combination of two or more.

Further, as the polyester ether-based polyol, the aliphatic dicarboxylic acid, the aromatic dicarboxylic acid, the aliphatic dicarboxylic acid, and ester compounds thereof, or acid anhydrides, diethylene glycol, glycols such as propylene oxide adducts, etc. Alternatively, a condensation reaction product with a mixture of these may be used.

Examples of polyether-based polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide and tetrahydrofuran, respectively, and copolymerized polyethers thereof. .

Examples of polycarbonate polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl- 1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, neopentyl glycol, 1,3-octanediol, 1,9 -nonanediol, 2,2-dimethylolheptane, and polycarbonate polyols obtained by reacting one or more of polyhydric alcohols such as diethylene glycol with ethylene carbonate, diethyl carbonate, and the like. A copolymer of polycaprolactone polyol and polyhexamethylene carbonate may also be used.

As the chain extender component constituting the polyurethane resin component (C-1), a low-molecular-weight polyol is used, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2- methyl-1,4-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 2,2-dimethylolheptane, diethylene glycol, 1,4-cyclohexanediol Aliphatic polyols such as methanol and glycerin; and aromatic glycols such as 1,4-dimethylolbenzene, bisphenol A.sub.2, ethylene oxide adducts of bisphenol A.sub.2 and propylene oxide adducts.

(Polystyrene resin component (C-2))
The polystyrene resin component (C-2) is a polymer component containing an aromatic vinyl hydrocarbon. Aromatic vinyl hydrocarbons include, for example, polystyrene, poly(p-, m- or o-methylstyrene), poly(2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene) , polyalkylstyrene such as poly(pt-butylstyrene); poly(o-, m- or p-chlorostyrene), poly(o-, m- or p-bromostyrene), poly(o-, m - or p-fluorostyrene), polyhalogenated styrenes such as poly(o-methyl-p-fluorostyrene); polyhalogenated substituted alkylstyrenes such as poly(o-, m- or p-chloromethylstyrene); (p-, m- or o-methoxystyrene), polyalkoxystyrenes such as poly (o-, m- or p-ethoxystyrene); polys such as poly (o-, m- or p-carboxymethylstyrene) carboxyalkylstyrene; polyalkyletherstyrene such as poly(p-vinylbenzylpropyl ether); polyalkylsilylstyrene such as poly(p-trimethylsilylstyrene); and polyvinylbenzyldimethoxyphosphide. The polystyrene-based resin component (C-2) may contain homopolymers and copolymers of these aromatic vinyl hydrocarbons and/or copolymerizable monomers other than aromatic vinyl hydrocarbons.

Further, from the viewpoint of improving the adhesive strength with the (II) layer, the polystyrene resin component (C-2) is an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer or a hydrogenated product thereof. is preferred. Examples of conjugated diene hydrocarbons include butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene. Further, when the polystyrene resin component (C-2) is a hydrogenated aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer, the above-exemplified hydrogenated conjugated diene hydrocarbon and Copolymers of aromatic vinyl hydrocarbons are preferred.
When the polystyrene-based resin component (C-2) is an aromatic vinyl hydrocarbon-conjugated diene-based hydrocarbon copolymer or its hydrogenated product, the conjugated diene-based hydrocarbon block or its hydrogenated product block is , homopolymers, copolymers, and/or copolymerizable monomers other than the conjugated diene hydrocarbons or hydrogenated products thereof may be contained in the blocks.

Examples of aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymers preferably used as the polystyrene resin component (C-2) include styrene-butadiene-styrene copolymers and styrene-ethylene-butylene-styrene copolymers. coalescence, styrene-ethylene-propylene-styrene copolymer, styrene-ethylene-propylene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-(ethylene-propylene)-styrene copolymer, styrene-isobutylene- Examples include styrene copolymers, and modified products thereof (for example, modified with maleic anhydride or amine) and hydrogenated products are also preferably used.

In addition, from the viewpoint of adhesion with the layer (II) made of a resin composition containing the polystyrene resin (B) as the main component, the aromatic vinyl hydrocarbon constituting the polystyrene resin component (C-2) is contained. The amount is preferably 1% by mass or more and 50% by mass or less when the polystyrene resin component (C-2) is taken as 100% by mass.

The (III) layer in the present invention is not particularly limited as long as it is a layer made of a resin composition containing a polyurethane resin component (C-1) and a polystyrene resin component (C-2). , When the resin composition constituting the layer (III) is 100% by mass, the polyurethane resin component (C-1) is 10% by mass or more and 80% by mass or less, and the polystyrene resin component (C-2 ) is 10% by mass or more and 80% by mass, and the total of the above (C-1) and the above (C-2) is preferably 50% by mass or more and 100% by mass or less. When the polyurethane resin component (C-1) is 10% by mass or more, it is preferable because the adhesive strength with the layer (I) is improved, and the polyurethane resin component (C-1) is 80% by mass or less. In this case, the adhesive strength with the (II) layer is improved, which is preferable. Further, when the polystyrene resin component (C-2) is 10% by mass or more, it is preferable because the adhesive strength with the layer (II) is improved, and the polystyrene resin component (C-2) is 80% by mass or less. is preferable because the adhesive strength with the layer (I) is improved. Furthermore, when the total of (C-1) and (C-2) is 50% by mass or more, the adhesive strength to both layers (I) and (II) is improved, and This is preferable because the difference in adhesive strength becomes smaller.

As the resin composition containing the polyurethane-based resin component (C-1) and the polystyrene-based resin component (C-2), the polyurethane-based resin component (C-1) and the polystyrene-based resin component (C-2) and a resin composition containing a copolymer of the polyurethane resin component (C-1) and the polystyrene resin component (C-2), good too. In the case of a copolymer of the polyurethane resin component (C-1) and the polystyrene resin component (C-2), the copolymerization mode may be a block copolymer or a random copolymer. It may be a graft copolymer.

<Other ingredients>
In the laminated film of the present invention, the resin composition constituting each layer may contain other resins other than the main component resin within a range that does not impair the effects of the present invention.
Other resins include polyolefin resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polyester resins, polycarbonate resins, polyamide resins, fluorine resins, polymethyl Pentene-based resin, polyvinyl alcohol-based resin, cyclic olefin-based resin, polylactic acid-based resin, polybutylene succinate-based resin, polyacrylonitrile-based resin, polyether-based resin, cellulose-based resin, polyimide-based resin, polyurethane-based resin, polyphenylene sulfide resins, polyphenylene ether resins, polyvinyl acetal resins, polybutadiene resins, polybutene resins, polyamideimide resins, polyamide bismaleimide resins, polyarylate resins, polyetherimide resins, polyetheretherketone resins, Examples include polyetherketone-based resins, polyethersulfone-based resins, polyketone-based resins, polyacetal-based resins, polysulfone-based resins, aramid-based resins, and the like.
In addition, a thermoplastic elastomer may be contained, and examples of thermoplastic elastomers that may be contained include styrene-based thermoplastic elastomers, amide-based thermoplastic elastomers, ester-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and urethane-based elastomers. Thermoplastic elastomers, dynamically vulcanized thermoplastic elastomers, vinyl chloride thermoplastic elastomers, acrylic thermoplastic elastomers, lactic acid thermoplastic elastomers, fluorine thermoplastic elastomers, silicone thermoplastic elastomers, ionomers, and these blends, alloys, modified products, dynamically crosslinked products, block copolymers, graft copolymers, random copolymers, core-shell type multi-layer structure rubbers, and the like.

In addition to the components described above, additives commonly used in resin compositions may be appropriately added to the resin composition constituting each layer within a range that does not significantly impair the effects of the present invention. Examples of the additives include recycled resin generated from trimming loss such as selvage, silica, talc, kaolin, and calcium carbonate, which are added for the purpose of improving and adjusting molding processability, productivity, and various physical properties of laminated films. Inorganic particles such as titanium oxide, pigments such as carbon black, flame retardants, weather stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, cross-linking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, Additives such as antioxidants, light stabilizers, ultraviolet absorbers, neutralizers, anti-fogging agents, anti-blocking agents, slip agents, and colorants are included.

<Layer structure of laminated film>
The laminated film of the present invention is a laminated film having at least three layers in which the (I) layer, the (II) layer, and the (III) layer are adjacent in the order of (I)/(III)/(II). If there is, the layer structure is not particularly limited.

A preferred lamination structure in the present invention is, for example, a three-layer structure consisting of (I)/(III)/(II), and another (IV) layer further laminated, (I)/(III)/ (II)/(IV), (IV)/(I)/(III)/(II) having a four-layer structure, and (I)/(III)/(II) having another layer (I) )/(I), a 3-kind 4-layer construction consisting of (II)/(I)/(III)/(II) having another (II) layer, and another 1 (I) / (III) / (II) / (III) having a layer (III) layer, a three-kind four-layer structure consisting of (III) / (I) / (III) / (II), (II )/(III)/(I)/(III)/(II) or (I)/(III)/(II)/(III)/(I). There are no restrictions on the number of layers or the types of layers ((IV) layer, (V) layer, (VI) layer, etc.) other than the layers (I) to (III).
Each layer may be laminated by co-extrusion, or may be laminated by pressing or laminating films obtained in separate processes. In addition, non-woven fabric, paper, metal, etc. may be laminated as the other layers described above.

A preferred lamination structure in the present invention is a three-kind five-layer structure of (I)/(III)/(II)/(III)/(I), with the layer (I) being the outermost layer. By adopting this layer structure, it is possible to obtain a laminated film that is excellent in rigidity and surface gloss and that suppresses delamination. In the case of a heat-shrinkable laminated film, we have developed a heat-shrinkable laminated film that is suitable for applications such as shrink packaging, shrink binding packaging, and shrink labels that achieves good shrinkage characteristics and suppresses delamination. You can get it easily.

In the laminated film of the present invention, the total thickness is not particularly limited, but from the viewpoint of application to packaging materials, it is preferably 5 μm or more and 1 mm or less, more preferably 10 μm or more and 800 μm or less, and 15 μm or more and 600 μm or less. is more preferable. In the case of a heat-shrinkable laminate film, the thickness is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more and 150 μm or less, and even more preferably 15 μm or more and 70 μm or less.

In the laminated film of the present invention, the thickness of each layer and the lamination ratio are not particularly limited, but from the viewpoint of maintaining the rigidity of the film, the lamination ratio is (I) / (III) / (II) = 20 to 80% / 1 to 50. %/20 to 80% (provided that the total lamination ratio of the layers (I), (II) and (III) is 100%).

In the film of the present invention, the thickness ratio between the (I) layer and the (II) layer is 2 or more, preferably 3 or more, and more preferably 4 or more when the (I) layer is 1. and is 12 or less, preferably 10 or less, more preferably 8 or less. In addition, the thickness of the (III) layer is 10% or more, preferably 15% or more, and 150% or less, preferably 100% or less, more preferably 80% or less of the total thickness of the (I) layer. Thickness is desirable. A good adhesion effect can be obtained if the thickness of the (III) layer is 10% or more of the total thickness of the (I) layers, and 150% or less, i.e. 1 of the total thickness of the (I) layers. If the thickness is 0.5 times or less, the transparency is not greatly reduced.

Although the total thickness of the film of the present invention is not particularly limited, it is preferably thinner from the viewpoint of keeping raw material costs as low as possible. is more preferably 50 μm or less, and most preferably 45 μm or less.

Another embodiment of the present invention is a heat-shrinkable laminated film obtained by stretching the above laminated film in at least one direction, wherein the film shrinks in the main shrinking direction when immersed in hot water at 100°C for 10 seconds. It is a heat-shrinkable laminated film having a rate of 30% or more.
In the present specification, "at least one direction" refers to either or both of the longitudinal direction and the transverse direction when the flow direction (MD) of the laminated film from the extruder is the longitudinal direction and the perpendicular direction (TD). The "main shrinkage direction" means the direction in which the heat shrinkage rate is large when immersed in hot water at 100°C for 10 seconds, out of the longitudinal direction and the transverse direction.

<Method for manufacturing laminated film and heat-shrinkable laminated film>
The laminated film of the present invention and the heat-shrinkable laminated film of the present invention can be produced by appropriately changing the conditions in a conventionally known production method, and the production method is not particularly limited, but the above ( I) Adjacent the resin composition constituting the layer, the resin composition constituting the layer (II), and the resin composition constituting the layer (III) in the order of (I) / (III) / (II) A laminated film can be produced by laminating simultaneously or sequentially as follows. Then, the laminated film can be heated and stretched in at least one axial direction to produce a more heat-shrinkable laminated film.

The form of the laminated film of the present invention and the heat-shrinkable laminated film of the present invention is not particularly limited, and may be planar or tubular. From the standpoint of printability on the inner surface, etc., a planar form is preferred. As a method for producing a planar film, for example, a method of obtaining a laminated film by melting the resin and resin composition used in each layer using a plurality of extruders, coextrusion from a T-die, and cooling and solidifying with a chilled roll. I can give an example. In addition, the obtained laminated film is stretched in the longitudinal direction with a roll and in the transverse direction with a tenter, and then annealed, cooled, and optionally subjected to corona discharge treatment, etc., so as to be uniaxially or biaxially stretched. A method for manufacturing a film having a thickness of 100 mm can be exemplified.
A method of cutting open a film produced by a tubular method to produce a planar film can also be applied. Moreover, the laminated film can also be produced sequentially by film-forming the resins constituting each layer separately and then laminating them by using a press method, a roll nip method, or the like.

The laminated film is cooled by cooling rolls, air, water, etc., and then reheated by a suitable method such as hot air, warm water, infrared rays, etc., and is subjected to roll stretching, tenter stretching, tubular stretching, long-distance stretching, etc. It is simultaneously or sequentially uniaxially or biaxially stretched. In the biaxial stretching, the stretching in the MD and TD directions may be carried out simultaneously, but sequential biaxial stretching in which one of them is carried out first is effective, and either MD or TD may be carried out first. The stretching temperature needs to be changed depending on the softening temperature of the resin constituting the film and the application required for the heat-shrinkable laminated film. It is controlled in the range of ℃ or less. The draw ratio in the main shrinkage direction (preferably TD) is 2 times or more, preferably 3 times or more, and more preferably 4 times or more depending on the film constituents, stretching means, stretching temperature, and desired product form, It is appropriately determined within the range of 7 times or less, preferably 6 times or less. Further, whether to use uniaxial stretching or biaxial stretching is determined depending on the intended use of the product.

Even in the case of applications requiring almost unidirectional shrinkage properties, such as labels for containers made of polyester resin, stretching in the vertical direction within a range that does not impair the shrinkage properties is also effective. The stretching temperature is typically in the range of 60°C or higher and 90°C or lower. Furthermore, regarding the draw ratio, the larger the size, the better the breakage resistance, but the heat shrinkage rate increases accordingly, making it difficult to obtain a good shrinkage finish. The following are particularly preferred.

In addition, the laminated film of the present invention can be imparted with shrinkability and retained by cooling the film immediately after stretching within a time period during which the molecular orientation of the stretched film is not relaxed.

<Shrinkage properties of heat-shrinkable laminated film>
It is important that the heat-shrinkable laminated film of the present invention has a heat shrinkage rate of 30% or more in the main shrinkage direction when immersed in hot water at 100°C for 10 seconds. Also, the thermal shrinkage in the main shrinkage direction when immersed in hot water at 100° C. for 10 seconds is preferably 40% or more, more preferably 50% or more. Also, it is preferably 90% or less, more preferably 80% or less.
The main shrinkage direction is preferably the perpendicular direction (TD) from the extruder when the flow direction (MD) of the heat-shrinkable film from the extruder is the longitudinal direction and the perpendicular direction (TD). A shrink label for a container needs to shrink in a relatively short period of time (several seconds to ten and several seconds) in the shrink processing process. The heat shrinkage rate is an index for judging the feasibility of adapting a heat shrinkable film for shrinkable label applications. That is, the shrinking machine that is most commonly used industrially for labeling containers is generally called a steam shrinker that uses steam as a heating medium for shrinking. From the viewpoint of the influence of heat on the object to be coated, it is necessary to heat-shrink the material sufficiently in as short a time as possible.
Considering such industrial productivity, if the heat shrinkage rate in the main shrinkage direction when immersed in hot water at 100 ° C. for 10 seconds is 30% or more, it should be sufficiently adhered to the coated objective within the shrink processing time. It is important because it can be determined that

In addition, the heat shrinkage rate in the main shrinkage direction when immersed in hot water at 80°C for 10 seconds is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. . Moreover, it is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.
Further, the thermal shrinkage in the main shrinkage direction when immersed in hot water at 70°C for 10 seconds is preferably 10% or more and 50% or less, more preferably 10% or more and 40% or less, and 10% or more and 30% or less. % or less.
Also, the heat shrinkage in the main shrinkage direction when immersed in hot water at 50° C. for 10 seconds is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less.

In the heat-shrinking process, the heat-shrinkable laminated film may be slightly shrunk (pre-shrunk) at a low temperature before the heat-shrinkable laminated film is completely covered on the object to fix the position of the film on the object to be covered. In this case, when the shrinkage ratio at each temperature is within the preferred range described above, the film can be gradually shrunk onto the object to be coated from a lower temperature, which is preferable.

When the heat shrinkage ratio in the main shrinkage direction when immersed in hot water at 80°C for 10 seconds is 20% or more, heat shrinkage is sufficient even at the neck and top surface of the container, which is preferable.
In addition, since the heat shrinkage force is increased by setting the lower limit of the heat shrinkage in the main shrinkage direction when immersed in hot water at 70 ° C. for 10 seconds to 10% or more, the laminated film can be used as the above container label, for example. It is preferable because the film does not move up in the direction of the top surface in the heat shrinking process. On the other hand, by setting the upper limit of the thermal shrinkage rate in the main shrinkage direction when immersed in hot water at 70° C. for 10 seconds to 50% or less, it is preferable to prevent rapid thermal shrinkage in a low temperature range.
In addition, if the thermal shrinkage rate in the main shrinkage direction when immersed in hot water at 50°C for 10 seconds is 5% or less, the natural shrinkage rate of the film can be kept small, so winding tightening occurs when the film is wound into a roll and stored. Also, it is preferable because it does not cause appearance defects such as uneven roll end faces.

Therefore, if the thermal shrinkage rate when immersed in warm water of 80°C, 70°C, and 50°C for 10 seconds is within the above range, the laminated film is temporarily fixed to the container, for example, in a low temperature range around 70°C. and in a high temperature range exceeding 70 ° C and around 100 ° C, shrinkage occurs rapidly, and as a result, at a predetermined position, the body of the container as well as the body is very Abnormalities such as wrinkles and burrs do not occur even when the thin neck and top surface are placed, and uniform shrinkage can be obtained, resulting in a beautiful shrink finish.

When the heat-shrinkable laminated film of the present invention is used as a label for polyester resin containers, the heat shrinkage in the orthogonal direction when immersed in hot water at 80°C for 10 seconds is preferably 20% or less, preferably 10%. It is more preferably 8% or less, more preferably 8% or less. The heat shrinkage in the orthogonal direction when immersed in hot water at 70° C. for 10 seconds is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. If the shrinkage ratio in the orthogonal direction exceeds 10%, shrinkage in the vertical direction becomes remarkable after shrinkage in label applications, which may cause dimensional deviation and defects in appearance.

<Transparency>
The transparency of the heat-shrinkable laminated film of the present invention is evaluated by the haze value measured according to JIS K7105, and the haze value is preferably 10% or less, more preferably 8% or less. % or less is more preferable. If the haze value is 10% or less, good transparency can be obtained, and beautiful printing and the like can be achieved.

<Tensile breaking elongation>
(Room temperature tensile breaking elongation)
The heat-shrinkable laminated film of the present invention has a tensile elongation at break of 100% in a direction perpendicular to the main shrinkage direction, which is measured in accordance with JISK7127 under conditions of an ambient temperature of 23°C and a tensile speed of 200 mm/min. It is preferable that it is above. It is more preferably 150% or more, still more preferably 200% or more. If the tensile elongation at break in a 23° C. environment is within the above range, problems such as breakage of the film-like material are less likely to occur during processes such as printing and bag making, which is preferable. Moreover, it is less likely that the bag will break or the like from the portion in close contact with the covering, which is preferable. The direction perpendicular to the main shrinkage direction is preferably the take-up (flow) direction (or MD) of the film-like material.
In order to make the tensile elongation at break at an ambient temperature of 23°C within the above range, it can be adjusted by appropriately adjusting the composition, adjusting the extrusion conditions in the film forming process, adjusting the stretching conditions, and adjusting the heat shrinkage rate. .

(Low temperature tensile breaking elongation)
The heat-shrinkable laminated film of the present invention has a tensile elongation at break of 100% in a direction perpendicular to the main shrinkage direction, which is measured in accordance with JISK7127 under conditions of an ambient temperature of 0°C and a tensile speed of 100 mm/min. It is preferably 150% or more, more preferably 200% or more. If the tensile elongation at break in a 0° C. environment is within the above range, problems such as breakage of the film-like material during processes such as printing and bag making are less likely to occur, which is preferable. Moreover, it is less likely that the bag will break or the like from the portion in close contact with the covering, which is preferable. The direction perpendicular to the main shrinkage direction is preferably the take-up (flow) direction (or MD) of the film-like material.
In order to make the tensile elongation at break at an ambient temperature of 0°C within the above range, it can be adjusted by appropriately adjusting the composition, adjusting the extrusion conditions in the film forming process, adjusting the stretching conditions, and adjusting the heat shrinkage rate. .

(Cryogenic tensile breaking elongation)
The heat-shrinkable laminated film of the present invention has a tensile elongation at break of 100 in a direction orthogonal to the main shrinkage direction, measured in accordance with JISK7127 under conditions of an ambient temperature of -10°C and a tensile speed of 100 mm/min. % or more. It is more preferably 150% or more, still more preferably 200% or more. If the tensile elongation at break at -10°C is within the above range, problems such as film breakage during processes such as printing and bag making are less likely to occur, and breakage resistance is ensured even on high-speed lines. can be maintained, which is preferable. Moreover, it is less likely that the bag will break or the like from the portion in close contact with the covering, which is preferable. The direction perpendicular to the main shrinkage direction is preferably the take-up (flow) direction (or MD) of the film-like material.
In order to make the tensile elongation at break at an ambient temperature of -10 ° C. within the above range, adjustment of the composition, adjustment of extrusion conditions in the film forming process, adjustment of stretching conditions, adjustment of heat shrinkage, etc. are adjusted as appropriate. can.

<Tensile modulus>
From the viewpoint of the stiffness of the film (rigidity at room temperature), the heat-shrinkable laminated film of the present invention has a tensile modulus of elasticity in a direction orthogonal to the main shrinkage direction of the film (hereinafter also referred to as "perpendicular direction") at an ambient temperature of 23 ° C. is preferably 1500 MPa or more, more preferably 1600 MPa or more, and even more preferably 1700 MPa or more. The upper limit of the tensile modulus in the direction perpendicular to the film is not particularly limited, but considering the upper limit of the tensile modulus of heat-shrinkable films that are commonly used, the upper limit is preferably about 2500 MPa to 3000 MPa. If the tensile modulus of elasticity in the direction perpendicular to the film is 1500 MPa or more, the stiffness (rigidity at room temperature) of the film as a whole is high. This is preferable because problems such as oblique covering with a labeling machine or the like and a tendency to lower the yield due to bending of the film or the like do not occur.

<Shrinkage stress>
The heat-shrinkable laminated film of the present invention preferably has a maximum shrinkage stress of 10 MPa or less, preferably 8 MPa or less, more preferably 6 MPa or less in the main shrinkage direction of the film when immersed in silicone oil at 80° C. for 10 seconds. On the other hand, the lower limit of the maximum shrinkage stress in the main shrinkage direction of the film is preferably 0.5 MPa or more from the viewpoint of maintaining the adhesion between the bottle and the heat-shrinkable film. If the maximum shrinkage stress in the main shrinkage direction of the film is 10 MPa or less, when the label is attached with the vapor shrinker, the temperature unevenness in the shrinker hardly causes the portions with different shrinkage behavior of the film to occur. Since avatars and the like are less likely to occur, the shrinkage finish tends to be good.

<Delamination strength>
The interlayer peel strength of the laminated film of the present invention is evaluated using a method of peeling at a test speed of 50 mm/min by a T-peel method in an environment of 23° C. and 50% RH. Generally, there are a 180-degree peel method and a T-type peel method in the peel test, but as a result of evaluation and confirmation by the present inventors, the T-type peel method has a higher delamination strength than the 180-degree peel method. A tendency to be calculated low was observed. In the present evaluation, we conducted extensive studies so as to achieve high delamination strength even with the T-peel method, in which the strength is calculated to be low. The interlayer peel strength of the laminated film of the present invention is preferably 0.5 N/10 mm width or more, more preferably 0.6 N/10 mm width or more, and even more preferably 0.7 N/10 mm width or more. The delamination strength of the heat-shrinkable laminated film of the present invention is evaluated using a method of peeling at a test speed of 50 mm/min by a T-peel method in an environment of 23° C. and 50% RH. The delamination strength is preferably 1.0 N/15 mm width or more, more preferably 1.2 N/15 mm width or more, and even more preferably 1.4 N/15 mm width or more.

<Packaging materials>
The heat-shrinkable laminated film of the present invention can be used for various purposes. Preferably, a printed layer is formed on one side or both sides of the film and attached to a glass container or a plastic container such as a PET bottle. Packaging materials such as heat shrinkable labels can be formed.

In general, a print layer is formed on the front and/or back surface of a heat-shrinkable film used for labels by a known method such as gravure printing, flexographic printing, offset printing, bar coating, or the like. The printing ink used to form the printed layer is not particularly limited, and can be appropriately selected according to the printing method. Foaming ink etc. can be mentioned.

Packaging materials for labels are processed into a flat shape or a cylindrical shape depending on the items to be packaged, and are used for packaging. For cylindrical containers such as PET bottles that require printing, first print the required image on one side of a wide flat film wound up on a roll, then cut it to the required width and cut the printed surface into It may be folded inward and center-sealed (the shape of the sealed portion is so-called envelope-sticking) to form a cylindrical shape. As the center sealing method, there are a sealing method using an organic solvent, a method using heat sealing, a method using an adhesive, and a method using an impulse sealer. Considering the appearance, it is preferable to use the sealing method using an organic solvent.

<Molded product, container>
The heat-shrinkable laminated film of the present invention is excellent in mechanical strength such as film stiffness (rigidity at room temperature), fingerprint whitening resistance, shrink finish, transparency, and remanufacturing additive properties, and also has natural shrinkage and shrinkage stress. When attached to a molded product or container, even a molded product or container with a complicated shape (for example, a cylinder with a constricted center, a square prism with corners, a pentagonal prism, a hexagonal prism, etc.) It can be used as a packaging material that can be brought into close contact and that can be worn beautifully without wrinkles, patters, or the like. Therefore, objects to which the heat-shrinkable laminated film of the present invention is attached include molded products or containers of various shapes, such as bottles, bottles (blow bottles), trays, lunch boxes, side dish containers, and dairy product containers. be done.
In particular, when the heat-shrinkable laminated film of the present invention is used as a shrinkable label for food containers (for example, PET bottles for soft drinks or foods, glass bottles, preferably PET bottles), complicated labeling as described above is required. Even if it has a shape, it is possible to adhere to the shape, and it is particularly excellent in that a container with a beautiful label attached without wrinkles or burrs can be obtained.

The heat-shrinkable laminated film of the present invention can be used not only as a heat-shrinkable label material for plastic containers, but also in materials such as metal, porcelain, glass, etc., which are extremely different from the heat-shrinkable film of the present invention in terms of coefficient of thermal expansion, water absorption, etc. Use at least one selected from paper, polyolefin resins such as polyethylene, polypropylene, and polybutene, polymethacrylate resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polyamide resins as constituent materials. It can be suitably used as a packaging material for a heat-shrinkable label for a wrapped package (container).

In addition to the resins mentioned above, the plastic container to which the packaging material of the present invention is attached may be made of polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer. Polymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), methacrylate-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenolic resin, urea resin, Examples include melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, and the like. These plastic containers may be mixtures or laminates of two or more resins.

The contents of the present invention will be described in more detail below with reference to examples, but the present invention is not limited by these examples. Various measurements and evaluations of the films shown in this specification were carried out as follows. Here, the machine direction (MD) of the film from the extruder is called the longitudinal direction, and the transverse direction (TD) is called the transverse direction.

(1) Haze Measurement Based on JISK7136, the haze values of the heat-shrinkable laminated films sampled in Examples and Comparative Examples were measured.

(2) 23°C tensile strength at break, tensile elongation at break (MD)
The resulting heat-shrinkable laminated film was cut into a size of 120 mm in MD and 15 mm in TD, and according to JISK7127, at a tensile speed of 200 mm / min and an ambient temperature of 23 ° C., the MD tensile strength and tensile elongation at break of the film were measured. The degree was measured and the average value of 10 measurements was determined.

(3) 23°C tensile strength at break, tensile elongation at break (TD)
The resulting heat-shrinkable laminated film was cut into a size of 120 mm in TD and 15 mm in MD. The degree was measured and the average value of 10 measurements was determined.

(4) Tensile breaking strength at 0°C, tensile breaking elongation (MD)
The obtained heat-shrinkable laminated film was cut into a size of 120 mm in MD and 15 mm in TD, and the tensile breaking strength in the pulling direction (MD) of the film at an ambient temperature of 0 ° C. at a tensile speed of 100 mm / min according to JISK7127, The tensile elongation at break was measured, and the average value of 10 measurements was taken.

(5) -10 ° C tensile strength at break, tensile elongation at break (MD)
The obtained heat-shrinkable laminated film was cut into a size of 120 mm in MD and 15 mm in TD, and according to JISK7127, the tensile breaking strength in the pulling direction (MD) of the film at an ambient temperature of -10 ° C. at a tensile speed of 100 mm / min. , the tensile elongation at break was measured, and the average value of 10 measurements was measured.

(6) Heat shrinkage The obtained heat-shrinkable laminated film was cut to a size of 10 mm MD and 200 mm TD, immersed in a hot water bath at 50 ° C., 70 ° C., 80 ° C., and 100 ° C. for 10 seconds, and the shrinkage of TD was measured. It was measured. The thermal shrinkage rate is expressed as a percentage of the amount of shrinkage to the original size before shrinkage. In addition, the obtained heat-shrinkable film was cut into a size of 200 mm in MD and 10 mm in TD, and the heat shrinkage rate of MD was measured under the same measurement conditions as the heat shrinkage rate measurement of TD.

(7) Peeling strength between layers The peeling strength between layers of the laminated films sampled in Examples and Comparative Examples and the heat-shrinkable laminated film was measured. The measurement was performed in an environment of 23° C. and 50% RH by a method of peeling at a test speed of 50 mm/min by a T-type peeling method. Then, the delamination strength was calculated by peeling from the TD of the laminated film. For the calculation of the delamination strength, the average value when the load obtained in the delamination test became constant to some extent was used as the delamination strength.

The raw materials used in each example and comparative example are as follows.
<Polyester resin (A)>
Copolyester, trade name: SKYGREEN PETG S2008 (manufactured by SK Chemicals), hereinafter abbreviated as "a-1".
Copolyester, trade name: EmbreceLV (manufactured by Eastman Chemical Co.), hereinafter abbreviated as "a-2".
<Polystyrene resin (B)>
・Styrene/butadiene = 82% by mass/18% by mass, storage modulus E′ (0°C): 2.14 × 10 ⁹ Pa, loss modulus E″ peak temperature of 74°C, styrene-butadiene copolymer, hereinafter It is called "b-1".
· Styrene-butadiene copolymer, trade name: Asaflex 830 (manufactured by Asahi Kasei Chemicals), hereinafter referred to as "b-2".
<Polyurethane resin>
· Ether-based polyurethane-based thermoplastic elastomer, trade name: Elastollan 1195A10TR (manufactured by BASF), hereinafter referred to as "TPU-1".
· Ether-based polyurethane-based thermoplastic elastomer, trade name: Elastollan ET-385-10 (manufactured by BASF), hereinafter referred to as "TPU-2".
Ester-based polyurethane-based thermoplastic elastomer, trade name: Elastollan C85A10 (manufactured by BASF), hereinafter referred to as "TPU-3".
Ester-based polyurethane-based thermoplastic elastomer, trade name: Elastollan ET595-10U (manufactured by BASF), hereinafter referred to as "TPU-4".
<Resin composition containing polyurethane resin component (C-1) and polystyrene resin component (C-2)>
- A copolymer of the following polyurethane-based resin component and the following polystyrene-based resin component was used.
"Polyurethane-based resin component": urethane-based thermoplastic elastomer composed of 4,4'-diphenylmethane diisocyanate (MDI), adipic acid, and 1,4-butanediol, "polystyrene-based resin component": styrene/conjugated diene-based Hydrocarbon hydrogenated product = 32 mass% / 68 mass% styrene-hydrogenated conjugated diene hydrocarbon copolymer, "polyurethane resin component" / "polystyrene resin component" = 45 mass% / 55 mass% %, hereinafter referred to as “D-1”.

<Experimental example 1>
100% by mass of the polyester resin "a-1" is introduced into a twin-screw extruder with a set temperature of 210 ° C., melt-kneaded, and the molten resin is cast from a T die (mouthpiece) with a cast roll set at 72 ° C. It was taken off and solidified by cooling to obtain a film with a thickness of 200 µm.

<Experimental example 2>
100% by mass of polystyrene resin "b-1" is introduced into a twin-screw extruder with a set temperature of 210 ° C., melted and kneaded, and the molten resin is cast from a T die (mouthpiece) with a cast roll set to 70 ° C. It was taken off and solidified by cooling to obtain a film with a thickness of 200 µm.

<Experimental example 3>
65% by mass of polyester resin "a-2" and 35% by mass of polystyrene resin "b-2" are introduced into a twin-screw extruder with a set temperature of 210 ° C., melt-kneaded, and the molten resin is passed through a strand die. The strands were collected from the granules, cooled and solidified in a water tank, and then compound pellets were obtained with a pelletizer. Hereinafter, the pellet (mixture of polyester resin and polystyrene resin) is referred to as "CPD-1".

<Experimental example 4>
Using two pieces of Upilex 50S (manufactured by Ube Industries, Ltd.) as protective films, 5 g of the copolymer "D-1" of the polyurethane resin component and the polystyrene resin component was sandwiched between the protective films, and the temperature was 210 ° C. and the pressure was It was pressed for 3 minutes with a hot press machine set at 20 MPa to obtain a film with a thickness of 200 μm.

<Experimental example 5>
A film with a thickness of 200 μm was obtained in the same manner as in Experimental Example 4 except that “D-1” used in Experimental Example 4 was changed to “TPU-1”.

<Experimental example 6>
A film with a thickness of 200 μm was obtained in the same manner as in Experimental Example 4, except that "D-1" used in Experimental Example 4 was changed to "TPU-4".

<Experimental example 7>
A film with a thickness of 200 μm was obtained in the same manner as in Experimental Example 4 except that “D-1” used in Experimental Example 4 was changed to “CPD-1”.

<Example 1>
Using the "a-1" film obtained in Experimental Example 1, the "D-1" film obtained in Experimental Example 4, the "b-1" film obtained in Experimental Example 2, and the protective film used in Experimental Example 4 Then, the protective film / "a-1" film / "D-1" film / "b-1" film / protective film are laminated in this order, and pressed at a temperature of 210 ° C. and a pressure of 0.2 MPa for 10 seconds. The protective film was peeled off to obtain a laminated film. When trying to peel the obtained laminated film by hand, the "a-1" film / "D-1" film was adhered so strongly that it could not be peeled off, so the "D-1" film / "b-1"'' was evaluated for delamination strength between films. Table 1 summarizes the results.

<Comparative Example 1>
A laminate film was obtained in the same manner as in Example 1, except that the "D-1" film used in Example 1 was changed to the "TPU-1" film obtained in Experimental Example 5. When trying to peel the obtained laminated film by hand, the "a-1" film / "D-1" film was adhered so strongly that it could not be peeled off, so the "D-1" film / "b-1"'' was evaluated for delamination strength between films. Table 1 summarizes the results.

<Comparative Example 2>
A laminate film was obtained in the same manner as in Example 1, except that the "D-1" film used in Example 1 was changed to the "TPU-4" film obtained in Experimental Example 6. When trying to peel the obtained laminated film by hand, the "a-1" film / "D-1" film was adhered so strongly that it could not be peeled off, so the "D-1" film / "b-1"'' was evaluated for delamination strength between films. Table 1 summarizes the results.

<Comparative Example 3>
A laminate film was obtained in the same manner as in Example 1, except that the "D-1" film used in Example 1 was changed to the "CPD-1" film obtained in Experimental Example 7. When trying to peel the obtained laminated film by hand, the "a-1" film / "D-1" film was adhered so strongly that it could not be peeled off, so the "D-1" film / "b-1"'' was evaluated for delamination strength between films. Table 1 summarizes the results.

<Example 2>
Lamination of (I) layer / (III) layer / (II) layer / (III) layer / (I) layer using three single screw extruders (manufactured by Mitsubishi Heavy Industries) and a three-kind five-layer multi-manifold die In a facility capable of co-extrusion, 100% by mass of the polyester resin "a-1" is introduced into the single-screw extruder that forms the (I) layer, and polystyrene is added to the single-screw extruder that forms the (II) layer. 100% by mass of the resin "b-1" is introduced, and 100% by mass of the copolymer "D-1" of the polyurethane resin component and the polystyrene resin component is introduced into the single screw extruder that forms the (III) layer. Then, after melt mixing at a set temperature of 210 ° C. for each extruder, the thickness of each layer is (I) layer / (III) layer / (II) layer / (III) layer / (I) layer = 25 µm / 5 µm / 140 µm /5 .mu.m/25 .mu.m, taken up with cast rolls at 70.degree. Next, with a film tenter manufactured by Kyoto Kikai Co., Ltd., after stretching 5.0 times in the horizontal uniaxial direction at a preheating temperature of 97 ° C. and a stretching temperature of 88 ° C., heat treatment was performed at 76 ° C. to produce a heat-shrinkable laminated film with a thickness of 40 μm. got Table 2 shows the evaluation results of the obtained film.

<Comparative Example 4>
Same as Example 2, except that 100% by mass of "D-1" used in Example 2 was changed to 100% by mass of "TPU-1" and introduced into a single screw extruder for forming layer (III). A heat-shrinkable laminated film having a thickness of 40 μm was obtained by the method of . Table 2 shows the evaluation results of the obtained film.

<Comparative Example 5>
Same as Example 2 except that 100% by mass of "D-1" used in Example 2 was changed to 100% by mass of "TPU-2" and introduced into the single screw extruder for forming the (III) layer. A heat-shrinkable laminated film having a thickness of 40 μm was obtained by the method of . Table 2 shows the evaluation results of the obtained film.

<Comparative Example 5>
Same as Example 2, except that 100% by mass of "D-1" used in Example 2 was changed to 100% by mass of "TPU-3" and introduced into a single screw extruder for forming layer (III). A heat-shrinkable laminated film having a thickness of 40 μm was obtained by the method of . Table 2 shows the evaluation results of the obtained film.

<Comparative Example 6>
Same as Example 2, except that 100% by mass of "D-1" used in Example 2 was changed to 100% by mass of "TPU-4" and introduced into a single screw extruder for forming layer (III). A heat-shrinkable laminated film having a thickness of 40 μm was obtained by the method of . Table 2 shows the evaluation results of the obtained film.

<Comparative Example 7>
100% by mass of "D-1" used in Example 2 was changed to 100% by mass of "CPD-1", and the same as in Example 2 except that it was introduced into a single-screw extruder that forms the (III) layer. A heat-shrinkable laminated film having a thickness of 40 μm was obtained by the method of . Table 2 shows the evaluation results of the obtained film.

It can be seen from Table 1 that the laminated film of the present invention obtained in Example 1 has a higher peel strength than Comparative Examples 1-3. In addition, this is due to the fact that the layer (III) is composed of a resin composition containing a polyurethane-based resin component (C-1) and a polystyrene-based resin component (C-2) defined in the present invention. do.
On the other hand, in the laminated films obtained in Comparative Examples 1 and 2, the (III) layer was composed only of a polyurethane-based resin and did not contain the polystyrene-based resin component (C-2) defined by the present invention. Although there was sufficient adhesive strength between the layers I) and layers (III), the interlayer adhesive strength between the layers (III) and (II) was very low, showing almost no adhesive strength.
In the laminated film obtained in Comparative Example 3, the (III) layer is composed of a mixture of a polyester resin and a polystyrene resin, and does not contain the polyurethane resin component (C-1) specified by the invention. Therefore, the interlayer adhesive strength between the (III) layer/(II) layer was insufficient.
Also, from Table 2, it can be seen that the heat-shrinkable laminated film of the present invention obtained in Example 2 is a heat-shrinkable laminated film having higher peel strength than those of Comparative Examples 4-8. In addition, it was found that the heat-shrinkable laminated film of the present invention obtained in Example 2 can sufficiently achieve functions as a heat-shrinkable film in terms of transparency, impact resistance, rigidity, and heat-shrink properties. .

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, the invention is not limited to the embodiments disclosed herein. However, it can be appropriately changed within the scope not contrary to the gist of the invention that can be read from the claims and the entire specification, or the idea, and the laminated film and heat-shrinkable laminated film that involve such changes are also within the technical scope of the present invention. should be understood as encompassed by

The laminated film of the present invention and the heat-shrinkable laminated film of the present invention are excellent in interlayer adhesion, shrinkability, breakage resistance, impact resistance, and rigidity. It can be suitably used for medical packaging materials, chemical packaging materials, cosmetic packaging materials, toiletry packaging materials, industrial packaging materials, agricultural material packaging materials, etc., and is suitable as packaging materials for these applications. can be used.

Claims (12)

(I) layer made of a resin composition containing polyester resin (A) as a main component, (II) layer made of a resin composition containing polystyrene resin (B) as a main component, polyurethane resin component (C-1 ) and a polystyrene-based resin component (C-2), the heat-shrinkable laminate having at least three adjacent layers in the order of (I)/(III)/(II) A heat-shrinkable laminated film having a heat shrinkage rate of 30% or more in the main shrinkage direction when immersed in hot water at 100°C for 10 seconds . 2. The heat-shrinkable laminated film according to claim 1, wherein said polyester resin (A) contains a terephthalic acid residue as a dicarboxylic acid residue. 3. The heat-shrinkable laminated film according to claim 1, wherein the polyester resin (A) contains an ethylene glycol residue as a diol residue. The heat-shrinkable laminated film according to any one of claims 1 to 3, wherein the polyester resin (A) contains a 1,4-cyclohexanedimethanol residue as a diol residue. The heat-shrinkable laminated film according to any one of claims 1 to 4, wherein the polystyrene resin (B) has an aromatic vinyl hydrocarbon content of 50% by mass or more. The heat-shrinkable laminated film according to any one of claims 1 to 5, wherein the polystyrene resin (B) is an aromatic vinyl hydrocarbon-conjugated diene hydrocarbon copolymer. The heat-shrinkable laminated film according to any one of claims 1 to 6, wherein the main component of the isocyanate constituting the polyurethane resin component (C-1) is an aromatic isocyanate. The content of the aromatic vinyl hydrocarbon in the polystyrene resin component (C-2) is 1% by mass or more and 50% by mass or less when the polystyrene resin component (C-2) is 100% by mass. The heat-shrinkable laminated film according to any one of claims 1 to 7. When the resin composition constituting the layer (III) is 100% by mass, the polyurethane resin component (C-1) is 10% by mass or more and 80% by mass or less, and the polystyrene resin component (C-2) is 10% by mass or more and 80% by mass, and the sum of (C-1) and (C-2) is 50% by mass or more and 100% by mass or less, any one of claims 1 to 8 The heat-shrinkable laminated film according to 1. The heat-shrinkable laminated film according to any one of claims 1 to 9, wherein the interlayer peel strength is 0 at a test speed of 50 mm / min by the T-peel method in an environment of 23 ° C. 50% RH. A heat-shrinkable laminated film having a width of 5 N/10 mm or more. A packaging material using the heat-shrinkable laminated film according to any one of claims 1 to 10 . A molded article or container fitted with the packaging material according to claim 11 .