JP2013226711A - Shrink film and shrink label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shrink film which is a different kind laminated film having a resin layer which is constituted of a polypropylene based resin and a resin layer which is constituted of an aromatic polyester based resin, and also, has high inter-layer strength at a normal temperature and at a shrinking step, and in which inter-layer separation hardly occurs.SOLUTION: A shrink film has a laminated structure in which an (A) layer, a (B) layer and a (C) layer are laminated through no other layer in the order of the A layer/B layer/C layer. In this case, the (A) layer is a resin layer containing an aromatic polyester based resin. the (B) layer is a resin layer containing 5 to 40 wt.% of an aromatic polyester based resin, and 50 to 95 wt.% of a polyolefine based resin. The (C) layer is a resin layer containing a polypropylene based resin. The polyolefine based resin contains 35 to 75 wt.% of a constituent unit derived from ethylene, 15 to 60 wt.% of a constituent unit derived from propylene, and a constituent unit derived from butene.

Description

  The present invention relates to a shrink film. More specifically, it has a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, and is less likely to cause delamination at room temperature and during heating (during shrink processing). The present invention relates to a laminated shrink film.

  Currently, plastic bottles such as PET bottles and metal bottles such as bottle cans are widely used as containers for beverages such as tea and soft drinks. These containers are often equipped with plastic labels to give display, decoration, and functionality. For example, because of the merits of decoration, workability (followability to containers), wide display area, etc., shrink Shrink labels or the like in which a printing layer is provided on a film (heat-shrinkable film) are widely used.

  As the shrink film, there is known a heterogeneous laminated film in which different resin materials are laminated for the purpose of imparting various functions to the film. For example, a laminated structure comprising a resin layer composed mainly of an aromatic polyester resin, an intermediate layer composed mainly of an ethylene-vinyl acetate resin, and a resin layer composed mainly of a polypropylene resin. The shrink film which has is known (refer patent document 1). Since the shrink film has a resin layer made of a polypropylene resin, the specific gravity is small and light, and when used as a shrink label, it can be easily separated from a PET bottle or the like by utilizing the difference in specific gravity at the time of recovery. In addition, by having a resin layer made of an aromatic polyester-based resin, it is excellent in shrinkage characteristics and strength characteristics (waist strength), and when the layer is used as a surface layer, it is excellent in printability. . In addition, since the interlayer strength (interlayer adhesion) is improved by the intermediate layer, delamination hardly occurs.

  However, in recent years, there is a tendency to shrink the shrink label under high temperature conditions from the viewpoint of highly shrinking the label and improving the working efficiency in the mounting process on the container, and the shrink processing temperature tends to increase. (For example, shrink processing is required at 95 ° C. or higher). When shrink processing is performed under such high temperature conditions, even the shrink film described in the above-mentioned patent document has insufficient heat resistance against the processing temperature of the intermediate layer, and particularly delamination (delamination) at the center seal portion. ), And the delamination-suppressing effect during shrink processing was not sufficient. For this reason, even if it is a case where it shrink-processes on high temperature conditions, the present condition is that the heterogeneous laminated shrink film with high interlayer intensity | strength and it is hard to produce delamination. Furthermore, in addition to the high interlayer strength at the time of the above-described high-temperature shrink processing, there is currently a need for a heterogeneous laminated shrink film having a high interlayer strength even at room temperature (for example, about 23 ° C.).

International Publication No. 2009/084212 Pamphlet

  That is, an object of the present invention is a heterogeneous laminated film having a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, and at the time of shrink processing (especially high temperature shrink). It is also intended to provide a shrink film having a high interlayer strength and hardly causing delamination even during processing.

  As a result of intensive studies to achieve the above object, the present inventors have determined that the resin layer (A layer) containing the aromatic polyester resin, the aromatic polyester resin, and the polyolefin resin having a specific configuration have a specific ratio. By having at least a three-layered three-layer structure of A layer / B layer / C layer comprising a resin layer (B layer) contained in and a resin layer (C layer) containing a polypropylene resin, even at room temperature. The present inventors have found that an excellent shrink film having high interlayer strength even during heating (during shrink processing) and hardly causing delamination can be obtained.

  That is, the present invention includes a resin layer (A layer) containing an aromatic polyester resin, a resin layer (B layer) containing 5 to 40% by weight of an aromatic polyester resin, and 50 to 95% by weight of a polyolefin resin. And a resin layer (C layer) containing a polypropylene-based resin and having a laminated structure in which the layers A, B, and C layers are laminated without any other layers, and the polyolefin resin is made of ethylene. A shrink film comprising 35 to 75% by weight of a structural unit derived from 15%, 60% by weight of a structural unit derived from propylene, and a structural unit derived from butene is provided.

  Further, in the present invention, the storage elastic modulus at 30 ° C. of the resin composition constituting the B layer, determined by dynamic viscoelasticity measurement, is 350 to 950 MPa, and the storage elastic modulus at 90 ° C. is 25 to 100 MPa. A shrink film as described above is provided.

  Furthermore, this invention provides the said shrink film which has the laminated structure laminated | stacked in order of A layer / B layer / C layer / B layer / A layer without passing through another layer.

  Moreover, this invention provides the shrink label containing the said shrink film.

  Since the shrink film of the present invention has the above-described configuration, it is a heterogeneous laminated film having a resin layer composed of a polypropylene resin and a resin layer composed of an aromatic polyester resin, even at room temperature. When heated, particularly when shrink processing is performed under a high temperature condition, high interlaminar strength is exhibited and delamination hardly occurs. For this reason, the shrink label using the shrink film of the present invention as a base film can be subjected to shrink processing at a high temperature, so that it can be attached to a container requiring higher shrinkage. . Therefore, the shrink film of the present invention is useful as a base film for shrink labels to be attached to containers such as PET bottles.

FIG. 1 is an explanatory diagram (schematic diagram) illustrating a method for measuring the warming interlayer strength.

  The shrink film of the present invention comprises a resin layer containing an aromatic polyester resin (hereinafter sometimes referred to as “A layer”), 5 to 40% by weight of aromatic polyester resin, and 50 to 95 polyolefin resin. At least one resin layer (hereinafter sometimes referred to as “B layer”) containing wt% and a resin layer containing polypropylene resin (hereinafter sometimes referred to as “C layer”) are provided.

  The shrink film of the present invention is laminated in the film without any other layers in the laminated structure in which the A layer and the C layer are laminated via the B layer, that is, in the order of A layer / B layer / C layer. And at least a three-layered / three-layered structure. Furthermore, the shrink film of the present invention has a layered structure (layered structure of three types and five layers) laminated in the order of layer A / layer B / layer C / layer B / layer A without other layers. Is preferred. In the laminated structure of the above-mentioned A layer / B layer / C layer / B layer / A layer, the A layers provided on the both sides of the C layer and the B layers have the same resin composition. The layer is preferably a layer having a different resin composition as long as the effects of the present invention are not impaired. In addition, the A layers and the B layers provided one by one on both sides of the C layer may be layers having the same thickness or different thicknesses.

  Although it does not specifically limit as a shrink film of this invention, For example, 3 types 3 layer laminated film of A layer / B layer / C layer, A layer (surface layer) / B layer (intermediate layer) / C layer (center) Layer) / B layer (intermediate layer) / A layer (surface layer), and a five-layer laminated film. The shrink film of this invention may have layers other than A layer, B layer, and C layer further. Layers other than the A layer, the B layer, and the C layer are not particularly limited, but a layer that can be provided in-line in the film forming process of the laminated film is preferable. For example, an anchor coat layer, an easy adhesion layer, an antistatic layer Examples thereof include a coating layer such as an agent layer.

[A layer]
The A layer is a resin layer containing at least an aromatic polyester resin. The aromatic polyester resin is a polyester resin containing an aromatic ring in the molecule. Examples of the aromatic polyester-based resin include various polyesters composed of a dicarboxylic acid component and a diol component as essential components (that is, a structural unit (structural unit) derived from dicarboxylic acid and a structural unit derived from diol). And polyesters containing at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a polymer obtained by a condensation reaction of a diol, a copolymer, or a mixture thereof. Only 1 type may be used for the said aromatic polyester-type resin, and 2 or more types may be used for it.

  Examples of the dicarboxylic acid (dicarboxylic acid component) include terephthalic acid, isophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 5-t-butylisophthalic acid, 4,4′-biphenyldicarboxylic acid, and trans-3. , 3′-stilbene dicarboxylic acid, trans-4,4′-stilbene dicarboxylic acid, 4,4′-dibenzyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,3-naphthalene Dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,2,6,6-tetramethylbiphenyl-4,4′-dicarboxylic acid, 1,1,3-trimethyl-3-phenyl Indene-4,5-dicarboxylic acid, 1,2-diphenoxyethane-4,4′-dicarboxylic acid, diphenyl ether Aromatic dicarboxylic acids such as dicarboxylic acid, 2,5-anthracene dicarboxylic acid, 2,5-pyridinedicarboxylic acid and substituted products thereof; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid , Azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, docosanedioic acid, 1,12 -Aliphatic dicarboxylic acids such as dodecanedioic acid and substituted products thereof; 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1 , 4-Decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalene Dicarboxylic acids, such as 2,6-decahydronaphthalene dicarboxylic acid and alicyclic dicarboxylic acids such as substituted versions thereof and the like. The said dicarboxylic acid may use only 1 type and may use 2 or more types.

  Examples of the diol (diol component) include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3 -Propanediol, 1,8-octanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2,4-dimethyl-1,3-hexanediol, 1,10-decanediol, Aliphatic diols such as polyethylene glycol and polypropylene glycol; 1,2-cyclohexanedimethanol, , 3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and other alicyclic diols; 2,2-bis (4-β-hydroxy And ethylene oxide adducts of bisphenol compounds such as ethoxyphenyl) propane and bis (4-β-hydroxyethoxyphenyl) sulfone, and aromatic diols such as xylylene glycol. The diol may be used alone or in combination of two or more.

  In addition to the above, the aromatic polyester-based resin includes oxycarboxylic acids such as p-oxybenzoic acid and p-oxyethoxybenzoic acid; monocarboxylic acids such as benzoic acid and benzoylbenzoic acid; and polyvalent acids such as trimellitic acid. It may contain a structural unit derived from a carboxylic acid; a monohydric alcohol such as polyalkylene glycol monomethyl ether; a polyhydric alcohol such as glycerin, pentaerythritol, or trimethylolpropane.

  In the aromatic polyester-based resin, 50 mol% or more (particularly 70 mol% or more) in the total dicarboxylic acid component is 50 mol% or more (particularly 70 mol%) in the aromatic dicarboxylic acid component and / or the total diol component. % Or more) is preferably an aromatic diol component. Among these, from the viewpoint of shrinkage characteristics, the content of the aromatic dicarboxylic acid component in the total dicarboxylic acid component is preferably 80 mol% or more (80 to 100 mol%), more preferably 90 mol% or more (90 to 100 mol). %).

  By making the aromatic polyester resin non-crystalline, the aromatic polyester resin is less likely to cause delamination between the A layer and the B layer, and the shrinkage rate (thermal shrinkage rate) of the entire shrink film. From the viewpoint of improving the above, a modified aromatic polyester-based resin containing a modifying component (copolymerization component) is preferable, not a single repeating unit. As the modified aromatic polyester resin, for example, at least one of a dicarboxylic acid component and a diol component is composed of two or more components, that is, a modified aromatic polyester resin containing a modified component in addition to the main component. Resins are preferred. In other words, the aromatic polyester-based resin is preferably a modified aromatic polyester-based resin including a structural unit derived from at least two kinds of dicarboxylic acids and / or a structural unit derived from at least two kinds of diols.

  Among the above modified aromatic polyester resins, among the above, in polyethylene terephthalate (PET) using terephthalic acid as the dicarboxylic acid component and ethylene glycol (EG) as the diol component, a part of the dicarboxylic acid component and / or diol component A modified PET in which is replaced with a modified component (that is, another dicarboxylic acid component and / or another diol component) is preferably exemplified.

  Examples of the dicarboxylic acid component used as a modifying component (copolymerization component) of the modified aromatic polyester resin (particularly, modified PET) include cyclohexanedicarboxylic acid, adipic acid, and isophthalic acid. Examples of the diol component used as the modifying component include 2,2-dialkyl-1,3-propanediol such as 1,4-cyclohexanedimethanol (CHDM) and neopentyl glycol (NPG), and diethylene glycol. Among these, CHDM and 2,2-dialkyl-1,3-propanediol (particularly NPG) are preferable. The alkyl group in the 2,2-dialkyl-1,3-propanediol is preferably an alkyl group having 1 to 6 carbon atoms, and the two alkyl groups may be the same or different. It may be an alkyl group.

  Specifically, as the aromatic polyester-based resin, in terms of shrinkage properties, polyethylene terephthalate (PET) using terephthalic acid as a dicarboxylic acid component and ethylene glycol (EG) as a diol component; Modified aromatic polyester-based resin using terephthalic acid, ethylene glycol as the diol component, and 1,4-cyclohexanedimethanol (CHDM) as the copolymerization component (sometimes referred to as “CHDM copolymerized PET”) Modified terephthalic acid as a dicarboxylic acid component, a modified aromatic polyester-based resin using ethylene glycol as a diol component as a main component and 2,2-dialkyl-1,3-propanediol as a copolymer component (“2,2- Dialkyl-1,3-propanediol Sometimes referred to as polymerization PET ") are preferred. Among the 2,2-dialkyl-1,3-propanediol copolymerized PET, in particular, terephthalic acid is used as the dicarboxylic acid component, ethylene glycol is the main component, and neopentyl glycol (NPG) is the copolymerized component as the diol component. The modified aromatic polyester-based resin used as (sometimes referred to as “NPG copolymerized PET”) is particularly preferable. The aromatic polyester resin is particularly preferably 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (CHDM copolymerized PET) and / or 2,2-dialkyl-1,3-propanediol copolymerized polyethylene terephthalate (2 , 2-dialkyl-1,3-propanediol copolymerized PET), more preferably CHDM copolymerized PET and / or neopentyl glycol copolymerized polyethylene terephthalate (NPG copolymerized PET). Note that copolymer components other than CHDM and 2,2-dialkyl-1,3-propanediol are used for the CHDM copolymerized PET and 2,2-dialkyl-1,3-propanediol copolymerized PET, respectively. For example, diethylene glycol may be further copolymerized.

  In the modified aromatic polyester resin, the copolymerization ratio of the copolymer component (modified component) [ratio of the copolymerized dicarboxylic acid component to the total dicarboxylic acid component (ratio), or the ratio of the copolymerized diol component to the total diol component ( The ratio)] is preferably 15 mol% or more (for example, 15 to 40 mol%) from the viewpoint of optimizing the thermal deformation behavior of the A layer and reducing delamination. Among them, for example, in the case of CHDM copolymerized PET, the proportion of CHDM is preferably 20 to 40 mol% (EG is 60 to 80 mol%) in all diol components (that is, 100 mol% terephthalic acid), More preferably, it is 25-35 mol% (EG is 65-75 mol%). In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, the ratio of 2,2-dialkyl-1,3-propanediol (the ratio of NPG in the case of NPG copolymerized PET) is 15-40 mol% (EG is 60-85 mol%) is preferable in a diol component. Further, a part of the EG component (preferably 1 to 10 mol% in the total diol component) may be replaced with diethylene glycol.

  The aromatic polyester resin is preferably a substantially amorphous aromatic polyester resin, more preferably an aromatic polyester resin that is an amorphous saturated polyester resin. Although not particularly limited, the aromatic polyester-based resin becomes difficult to crystallize by being modified as described above, and can be made substantially amorphous by, for example, modification. By making the aromatic polyester-based resin amorphous, extrusion at a relatively low temperature is possible, and the flow behavior of the A layer can be brought close to the flow behavior of the B layer and the C layer. Thereby, the layer formability of the A layer at the time of extrusion processing is improved, and the adhesiveness with the B layer is improved, so that the interlayer strength at the time of shrink processing and at room temperature is improved, and delamination hardly occurs.

  The crystallinity of the aromatic polyester resin measured by the differential scanning calorimetry (DSC) method (measured at a heating rate of 10 ° C./min) is preferably 15% or less, more preferably 10% or less. . Further, the aromatic polyester-based resin is most preferably a resin that hardly shows a melting point (melting peak) when measured by the DSC method (that is, a crystallinity of 0%). The crystallinity can be calculated from the value of heat of crystal fusion obtained by DSC measurement, with a sample having a clear crystallinity measured by the X-ray method or the like as a standard. The heat of crystal melting is, for example, using a DSC (Differential Scanning Calorimetry) device manufactured by Seiko Instruments Inc. and performing a nitrogen seal at a sample amount of 10 mg and a heating rate of 10 ° C./min. It can be determined from the area of the melting peak when the temperature is raised to room temperature and then raised again. The crystallinity is preferably measured from a single resin, but when measured in a mixed state, the melting peak of the target aromatic polyester resin is subtracted from the melting peak of the resin to be mixed. You can ask for.

  The weight average molecular weight (Mw) of the aromatic polyester-based resin is preferably 15000 to 90000, more preferably 30000 to 80000, from the viewpoints of melting behavior and shrinkage behavior. In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, 50000-70000 is more preferable.

  The glass transition temperature (Tg) of the aromatic polyester resin is preferably 60 to 80 ° C, more preferably 60 to 75 ° C. The Tg can be controlled by the type of dicarboxylic acid or diol constituting the aromatic polyester resin and the copolymerization ratio of the copolymerization component (modification component) used for modification. When the Tg of the aromatic polyester resin is in the above range, the thermal deformation behavior (change in shrinkage stress with respect to temperature) is close to that of the polypropylene resin constituting the C layer. The difference in shrinkage stress generated between them becomes small, and delamination during shrink processing hardly occurs. When Tg exceeds 80 ° C., during shrink processing, the A layer shrinks rapidly at a high temperature, and the shrinkage stress difference increases with the C layer that gradually shrinks from a relatively low temperature, resulting in delamination. It may be easier.

  The glass transition temperature (Tg) can be measured by DSC (differential scanning calorimetry) based on, for example, JIS K7121. The DSC measurement is not particularly limited. For example, the DSC measurement can be performed using a differential scanning calorimeter “DSC6200” manufactured by Seiko Instruments Inc. under a temperature rising rate of 10 ° C./min.

  The IV value (intrinsic viscosity) of the aromatic polyester resin is preferably 0.70 (dl / g) or more, more preferably 0.70 to 0.90 (dl / g), from the viewpoint of interlayer strength. Preferably it is 0.75-0.85 (dl / g).

  Commercially available products may be used as the aromatic polyester-based resin, for example, “EMBRACE 21214”, “EMBRACE LV” (CHDM copolymerized PET) manufactured by Eastman Chemical (Eastman Chemical), Bell Co., Ltd. "Belpet MGG200" (2,2-dialkyl-1,3-propanediol copolymerized PET) manufactured by Polyester Products, "Belpet E02" (NPG copolymerized PET) manufactured by Bell Polyester Products, etc. are available on the market. .

  The content of the aromatic polyester resin in the A layer (that is, the total content of all the aromatic polyester resins contained in the A layer) is not particularly limited, but shrinkage characteristics (heat shrinkage rate), From the viewpoint of heat resistance, strength, chemical resistance, printability, etc., 50% by weight or more (50 to 100% by weight) is preferable, more preferably 80 to 100% with respect to the total weight (100% by weight) of the A layer. % By weight, more preferably 90 to 100% by weight.

  The layer A may contain components other than the aromatic polyester-based resin (additive components), for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, if necessary. A coloring agent, a pinning agent (alkaline earth metal) and the like may be included.

[B layer]
The B layer is a resin layer containing at least an aromatic polyester resin and a polyolefin resin. Each of the aromatic polyester resin and the polyolefin resin may be used alone or in combination of two or more.

  Examples of the aromatic polyester resin (that is, the aromatic polyester resin contained in the B layer) include the aromatic polyester resins exemplified and described as the aromatic polyester resin in the A layer. The aromatic polyester resin contained in the B layer may be the same aromatic polyester resin as the aromatic polyester resin contained in the A layer, or may be a different aromatic polyester resin. However, from the viewpoint of improving productivity and interlayer strength between the A layer and the B layer, the same aromatic polyester resin is preferable.

  The aromatic polyester resin contained in the B layer improves the heat shrinkage rate and stretchability of the B layer, prevents the B layer from spontaneous shrinkage, the flow behavior of the B layer, and the flow behavior of the A layer and the C layer. From the viewpoint of increasing the affinity between the B layer and the A layer or C layer (when the collected raw material is contained) and improving the interlayer strength, the modified aromatic polyester resin is preferable. More preferred is modified PET, still more preferred is CHDM copolymerized PET and / or 2,2-dialkyl-1,3-propanediol copolymerized PET, and still more preferred is CHDM copolymerized PET and / or NPG copolymerized PET. Polymerized PET. Note that copolymer components other than CHDM and 2,2-dialkyl-1,3-propanediol are used for the CHDM copolymerized PET and 2,2-dialkyl-1,3-propanediol copolymerized PET, respectively. For example, diethylene glycol may be further copolymerized.

  The aromatic polyester resin is preferably a substantially amorphous aromatic polyester resin, more preferably an aromatic polyester resin (particularly a modified aromatic polyester resin) which is an amorphous saturated polyester resin. ). By making the aromatic polyester-based resin amorphous, the heat shrinkage rate and stretchability of the B layer are improved, the natural shrinkage of the B layer is prevented, the flow behavior of the B layer and the flow of the A layer and the C layer This is preferable because the behavior is close and the affinity between the B layer, the A layer, and the C layer (when the collected raw material is contained in the C layer) is increased and the interlayer strength is improved. The crystallinity of the aromatic polyester resin measured by the differential scanning calorimetry (DSC) method (measured at a heating rate of 10 ° C./min) is preferably 15% or less, more preferably 10% or less. . Further, the aromatic polyester-based resin is most preferably a resin that hardly shows a melting point (melting peak) when measured by the DSC method (that is, a crystallinity of 0%).

  The weight average molecular weight (Mw) of the aromatic polyester-based resin is preferably 15000 to 90000, more preferably 30000 to 80000, from the viewpoints of melting behavior and shrinkage behavior. In the case of 2,2-dialkyl-1,3-propanediol copolymerized PET, 50000-70000 is more preferable.

  The glass transition temperature (Tg) of the aromatic polyester resin is preferably 60 to 80 ° C., more preferably 60 to 75 ° C., from the viewpoints of stretchability and interlayer strength. In addition, the IV value (intrinsic viscosity) of the aromatic polyester resin is preferably 0.70 (dl / g) or more, more preferably 0.70 to 0.90 (dl), from the viewpoints of extrusion suitability and interlayer strength. / G), more preferably 0.75 to 0.85 (dl / g).

  Commercially available products may be used as the aromatic polyester-based resin, for example, “EMBRACE 21214”, “EMBRACE LV” (CHDM copolymerized PET) manufactured by Eastman Chemical (Eastman Chemical), Bell Co., Ltd. "Belpet MGG200" (2,2-dialkyl-1,3-propanediol copolymerized PET) manufactured by Polyester Products, "Belpet E02" (NPG copolymerized PET) manufactured by Bell Polyester Products, etc. are available on the market. .

  The polyolefin resin (that is, the polyolefin resin contained in the B layer) is a polymer composed of olefin as an essential monomer component, that is, derived from the olefin in the molecule (in one molecule). It is a polymer containing at least a structural unit. The polyolefin resin includes, for example, a homopolymer of one olefin; a copolymer of two or more olefins; a copolymer of one or more olefins and one or more copolymerization components other than olefins, and the like. Can be mentioned. In addition, the form of copolymerization of the copolymer is not particularly limited, and may be, for example, a block copolymer or a random copolymer. Examples of the olefin include olefins having 2 to 20 carbon atoms such as ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, and decene (in particular, ethylene, propylene, 1-butene, 1-pentene, 4- And an α-olefin having 2 to 20 carbon atoms such as methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene). Specifically, for example, a polyethylene resin or a polypropylene resin is preferable as the polyolefin resin.

The polyethylene resin (that is, the polyethylene resin contained in the B layer) is a polymer composed of ethylene as an essential monomer component, that is, derived from ethylene in the molecule (in one molecule). It is a polymer containing at least a structural unit. The polyethylene-based resin is not particularly limited, and publicly known or commonly used polyethylene can be used. For example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene, medium density Examples include polyethylene and high density polyethylene (HDPE). Among these, low density polyethylene (including linear low density polyethylene and ultra-low density polyethylene) having a density of less than 0.930 (g / cm ³ ) is preferable, and linear low density polyethylene is particularly preferable.

  The polypropylene resin (that is, the polypropylene resin contained in the B layer) is a polymer composed of propylene as an essential monomer component, that is, derived from propylene in a molecule (in one molecule). It is a polymer containing at least a structural unit. Examples of the polypropylene resin include a propylene homopolymer (homopolypropylene); a copolymer composed of propylene and one or more olefins (olefins other than propylene) as essential monomer components (propylene copolymer). And the like). As the propylene copolymer, among them, a copolymer composed of propylene and one or more α-olefins as essential monomer components (propylene-α-olefin copolymer) is preferable. The propylene copolymer is a copolymer containing at least a structural unit derived from propylene and a structural unit derived from olefin in a molecule (in one molecule). The propylene-α-olefin copolymer is a copolymer containing at least a structural unit derived from propylene and a structural unit derived from α-olefin in the molecule (in one molecule). Examples of the α-olefin used as a copolymerization component of the propylene-α-olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-heptene. , 1-octene, 1-nonene, 1-decene and the like, such as α-olefin having 4 to 20 carbon atoms. The α-olefin may be used alone or in combination of two or more. The propylene copolymer (propylene-α-olefin copolymer or the like) may be a block copolymer or a random copolymer.

  Among the above, the polypropylene-based resin is selected from the group consisting of homopolypropylene, ethylene-propylene copolymer (also referred to as propylene-ethylene copolymer), propylene-butene copolymer, and ethylene-propylene-butene copolymer. It is preferable that the selected polypropylene resin (at least one polypropylene resin), more preferably homopolypropylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer, propylene-butene random copolymer. A polypropylene resin (at least one polypropylene resin) selected from the group consisting of a coalescence and an ethylene-propylene-butene random copolymer.

  Furthermore, the polypropylene resin preferably contains at least a structural unit derived from ethylene, a structural unit derived from propylene, and a structural unit derived from butene. The polypropylene resin is a resin containing at least an ethylene-propylene-butene copolymer; a propylene-butene copolymer and / or an ethylene-propylene-butene copolymer, and a mixed resin containing at least an ethylene-propylene copolymer. And a mixed resin containing at least a propylene-butene copolymer and / or an ethylene-propylene-butene copolymer, and an ethylene-propylene copolymer.

  From the viewpoint of improving the heat resistance and flexibility of the B layer, the polyolefin resin (that is, the polyolefin resin contained in the B layer) is, among the above, particularly the polyethylene resin and the polypropylene resin. It is preferably a mixed resin that includes (at least includes), more preferably a mixed resin that includes (at least includes) linear low-density polyethylene (LLDPE) and the polypropylene resin. When the polyolefin resin is a mixed resin containing the polyethylene resin (particularly preferably LLDPE) and the polypropylene resin, the content of the polyethylene resin (particularly LLDPE) in the polyolefin resin is not particularly limited. The amount is preferably 35 to 75% by weight, more preferably 40 to 70% by weight, based on the total weight (100% by weight) of the polyolefin resin. Further, the content of the polypropylene resin in the polyolefin resin is not particularly limited, but is preferably 15 to 60% by weight, more preferably 30 to 55% by weight with respect to the total weight (100% by weight) of the polyolefin resin. %. When mixed resin is the said composition, since the heat resistance of a B layer and a softness | flexibility improve especially, it is preferable.

  The polyolefin resin (that is, the polyolefin resin contained in the B layer) is composed of 35 to 75% by weight of structural units derived from ethylene, 15 to 60% by weight of structural units derived from propylene, and a structural unit derived from butene. At least. The structural unit derived from butene is preferably a structural unit derived from 1-butene. When the polyolefin resin is a mixed resin containing two or more kinds of polyolefin resins (mixed resin consisting only of polyolefin resins), that is, when two or more kinds of polyolefin resins are contained in the B layer, The mixed resin may contain 35 to 75% by weight of structural units derived from ethylene, 15 to 60% by weight of structural units derived from propylene, and a structural unit derived from butene. That is, the polyolefin resin contained in the B layer only needs to satisfy the above requirements as a whole, and each of the two or more polyolefin resins contained in the B layer does not need to satisfy the above requirements. In addition, the polyolefin-based resin may include a structural unit other than a structural unit derived from ethylene, a structural unit derived from propylene, and a structural unit derived from butene.

  The polyolefin-based resin contained in the B layer as a whole contains a structural unit derived from ethylene and a structural unit derived from propylene in the above proportion, and further includes a structural unit derived from butene. Is excellent in flexibility and heat resistance. For this reason, both the flexibility and heat resistance of the B layer can be achieved at a high level, and the shrink strength of the shrink film of the present invention can be obtained at both normal temperature (for example, about 23 ° C.) and warming (during shrink processing). Can be improved. Furthermore, the stretchability of the B layer becomes good.

  The content of structural units derived from ethylene in all the polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is the total of all the polyolefin resins contained in the B layer. It is 35 to 75% by weight, preferably 40 to 68% by weight, based on the weight (100% by weight). By setting the content to 35% by weight or more, the flexibility of the polyolefin resin is improved, and in particular, the interlayer strength of the shrink film at room temperature is improved. Further, when the content exceeds 75% by weight, the stretchability of the B layer is lowered, and after the unstretched film is stretched to form a shrink film, the B layer naturally shrinks and shrinks and the appearance of the shrink film Becomes defective.

  The content of the structural unit derived from propylene in all the polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is the total of all the polyolefin resins contained in the B layer. It is 15-60 weight% with respect to a weight (100 weight%), Preferably it is 30-55 weight%. By setting the content to 15% by weight or more, the heat resistance of the polyolefin resin is improved, and in particular, the interlayer strength during heating of the shrink film is improved. In addition, the stretchability of the B layer and the affinity with the C layer are improved. Furthermore, the spontaneous shrinkage of the B layer is suppressed. Furthermore, the interlayer strength at room temperature is also improved. Moreover, when the said content exceeds 60 weight%, the softness | flexibility of polyolefin resin will fall, and the interlayer strength at the time of the normal temperature of a shrink film and heating will fall.

  The content of the structural unit derived from butene in all the polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is not particularly limited, but all the components contained in the B layer The content is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and still more preferably 2 to 20% by weight based on the total weight (100% by weight) of the polyolefin resin. In particular, the content of structural units derived from 1-butene preferably satisfies the above range. When the structural unit derived from butene is not contained in the whole polyolefin resin contained in the B layer, the heat resistance of the polyolefin resin is lowered, and the interlayer strength during heating of the shrink film is lowered.

  In addition, when the polyolefin resin contained in the B layer is a mixed resin containing two or more polyolefin resins, the content of the structural unit derived from ethylene, the content of the structural unit derived from propylene, and Content of the structural unit derived from the said butene is content in mixed resin, respectively.

  According to another expression, in all monomer components (100% by weight) constituting the polyolefin-based resin contained in the B layer, 35 to 75% by weight (particularly 40 to 68% by weight) of ethylene, propylene 15 to 60% by weight (particularly 30 to 55% by weight) and butene (preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and further preferably 2 to 20% by weight) are included. preferable.

The content of the structural unit derived from ethylene, the content of the structural unit derived from propylene, and the content of the structural unit derived from butene are the composition of the polyolefin-based resin contained in the B layer (each polyolefin system). The content of each structural unit contained in the resin and the content of each polyolefin resin in all polyolefin resins contained in the B layer) can be controlled. More specifically, for example, in the polyolefin resin contained in the B layer, the content of structural units derived from ethylene is e ₁ (wt%), and the content of structural units derived from propylene is p ₁ (weight). %), And the content of the structural unit derived from butene is b ₁ (% by weight) and the content of the structural unit derived from ethylene is e ₂ (% by weight), derived from propylene Is a mixed resin composed only of a polyolefin resin (PO2) having a content of structural units of p ₂ (% by weight) and a content of structural units derived from butene of b ₂ (% by weight), When the content of PO1 in 100% by weight of the mixed resin (PO1 and PO2) is W ₁ (% by weight) and the content of PO2 is W ₂ (% by weight), the ethylene in the mixed resin Unit derived from Constituent units derived from propylene, and the content of the constituent unit derived from butenes can generally controlled as follows.
Content (% by weight) of structural unit derived from ethylene = (e ₁ × W ₁ + e ₂ × W ₂ ) / 100
Content (% by weight) of structural unit derived from propylene = (p ₁ × W ₁ + p ₂ × W ₂ ) / 100
Content (% by weight) of structural unit derived from butene = (b ₁ × W ₁ + b ₂ × W ₂ ) / 100

  The analysis / measurement of the content of the structural unit (the structural unit derived from ethylene, the structural unit derived from propylene, and the structural unit derived from butene) and the content of the structural unit is not particularly limited. For example, nuclear magnetic resonance ( NMR), gas chromatograph mass spectrometer (GCMS) and the like. In addition, analysis / measurement of other resin layers (A layer, C layer, etc.) and constituent units in the resin and the content of the constituent units can be performed in the same manner.

  It is preferable that the polyolefin resin contained in the B layer contains no or almost no reactive functional group. The reactive functional group is a functional group that reacts or interacts with the ester bond portion of the polyester (such as a hydrogen bond), and is not particularly limited. For example, a carboxyl group (including a carboxylic acid anhydride group), a hydroxyl group, Examples thereof include an oxazoline group, an isocyanate group, and an epoxy group. The polyolefin resin contains a reactive functional group means that the reactive functional group is grafted to the main chain of the polyolefin polymer, and that the reactive functional group is copolymerized in the polyolefin polymer main chain. It shall include any meaning of being introduced.

  The content of reactive functional groups in all polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is preferably less than 5% by weight, more preferably less than 2% by weight. is there. In particular, the content of a reactive functional group selected from the group consisting of a carboxyl group (including a carboxylic acid anhydride group), a hydroxyl group, an oxazoline group, an isocyanate group, and an epoxy group preferably satisfies the above range. When a polyolefin-based resin containing a certain amount of reactive functional groups (for example, 5% by weight or more) is used for the B layer, the A layer and the B layer are once firmly bonded during extrusion in the shrink film manufacturing process. In some cases, the bonded portion is peeled off by stretching, and the interlayer strength is lowered.

  The storage elastic modulus E ′ (30 ° C.) at 30 ° C. obtained by dynamic viscoelasticity measurement of all polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is not particularly limited. However, 200-500 MPa is preferable, More preferably, it is 300-450 MPa. In this specification, the “storage modulus at 30 ° C. determined by dynamic viscoelasticity measurement” may be referred to as “E ′ (30 ° C.)”. The “storage modulus” may be referred to as “E ′ (90 ° C.)”. When the above E ′ (30 ° C.) exceeds 500 MPa, the adhesiveness of the B layer at room temperature may decrease, and the interlayer strength of the shrink film at room temperature may decrease. On the other hand, if the above E ′ (30 ° C.) is less than 200 MPa, the E ′ (90 ° C.) of all the polyolefin resins contained in the B layer becomes too low, and the heat resistance of the polyolefin resin and the B layer decreases. In some cases, the interlayer strength during heating of the shrink film may decrease.

  The storage elastic modulus E ′ (90 ° C.) at 90 ° C. obtained by dynamic viscoelasticity measurement of all polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is not particularly limited. However, 30-100 MPa is preferable, More preferably, it is 30-70 MPa. When the above E ′ (90 ° C.) exceeds 100 MPa, E ′ (30 ° C.) of all polyolefin resins contained in the B layer becomes too high, and the adhesiveness of the B layer at normal temperature decreases. Thus, the interlayer strength of the shrink film at normal temperature may be reduced. On the other hand, when the above E ′ (90 ° C.) is less than 30 MPa, the heat resistance of the polyolefin resin and the B layer is lowered, and the interlayer strength during heating of the shrink film may be lowered.

  In addition, when the polyolefin resin contained in the B layer is a mixed resin containing two or more kinds of polyolefin resins, the E ′ (30 ° C.) and the E ′ (90 ° C.) are respectively in the B layer. It is a value of a mixed resin of all the polyolefin resins included.

  Although the storage elastic modulus E '(30 degreeC) in 30 degreeC calculated | required by the dynamic viscoelasticity measurement of the resin composition which comprises B layer (the whole resin composition which comprises B layer) is not specifically limited, 350- 950 MPa is preferable, and more preferably 500 to 900 MPa. When the above E ′ (30 ° C.) exceeds 950 MPa, the adhesiveness of the B layer at room temperature may decrease, and the interlayer strength of the shrink film at room temperature may decrease. On the other hand, if the above E ′ (30 ° C.) is less than 350 MPa, the E ′ (90 ° C.) of the resin composition constituting the B layer is too low, the heat resistance of the B layer is lowered, and the shrink film is heated. In some cases, the interlaminar strength decreases.

  The storage elastic modulus E ′ (90 ° C.) at 90 ° C. obtained by dynamic viscoelasticity measurement of the resin composition constituting the B layer (the whole resin composition constituting the B layer) is not particularly limited, but 25 to 25 100 MPa is preferable, and more preferably 30 to 60 MPa. When the above E ′ (90 ° C.) exceeds 100 MPa, the E ′ (30 ° C.) of the resin composition constituting the B layer becomes too high, and the adhesiveness of the B layer at normal temperature is lowered, thereby shrinking. The interlayer strength of the film at room temperature may be reduced. On the other hand, if the above E ′ (90 ° C.) is less than 25 MPa, the heat resistance of the B layer is lowered, and the interlayer strength during heating of the shrink film may be lowered.

  The E ′ (30 ° C.) and the E ′ (90 ° C.) are determined by dynamic viscoelasticity measurement. The dynamic viscoelasticity measurement is performed under the conditions of frequency: 10 Hz and heating rate: 2 ° C./min. The evaluation apparatus is, for example, Seiko Instruments Inc. “EXSTAR6000 DMS6100” manufactured by (Seiko Instruments Inc.) can be used.

  Temperature dependence (temperature-tan δ curve) of loss tangent (tan δ) determined by dynamic viscoelasticity measurement of all polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer). , Which may be referred to as “dynamic viscoelastic curve”) is not particularly limited, but tan δ is preferably less than 1 to 1 or more in a temperature range of 100 to 140 ° C. (100 ° C. or more and 140 ° C. or less). . Hereinafter, the temperature at which tan δ is less than 1 to 1 or more in the measurement temperature range of 20 ° C. to 140 ° C. is referred to as “T (tan δ ≧ 1)”. T (tan δ ≧ 1) is preferably 100 to 140 ° C., more preferably 120 to 130 ° C. T (tan δ ≧ 1) is an index of heat resistance. When T (tan δ ≧ 1) is less than 100 ° C., especially when shrink processing is performed at a high temperature (for example, a temperature of 95 ° C. or more), the heat resistance of the B layer is insufficient and delamination occurs. There is. On the other hand, when T (tan δ ≧ 1) exceeds 140 ° C., the stretchability of the B layer is lowered, and the film may be broken during the production of the shrink film.

  The T (tan δ ≧ 1) is obtained by dynamic viscoelasticity measurement. Specifically, the temperature dependence (dynamic viscoelastic curve) of tan δ is obtained by dynamic viscoelasticity measurement, and the temperature at which tan δ is less than 1 to 1 or more (tan δ = 1) in the dynamic viscoelastic curve. Is defined as T (tan δ ≧ 1). The dynamic viscoelasticity measurement is performed under the conditions of frequency: 10 Hz, temperature increase rate: 2 ° C./min, measurement temperature: 20 ° C. to 140 ° C. The evaluation apparatus is, for example, Seiko Instruments Inc. “EXSTAR6000 DMS6100” manufactured by the company can be used. When the polyolefin resin contained in the B layer is a mixed resin containing two or more polyolefin resins, the above T (tan δ ≧ 1) is a mixed resin of all the polyolefin resins contained in the B layer. Is the value of

  The melt flow rate (MFR) (temperature 230 ° C., load 2.16 kgf) of all the polyolefin resins contained in the B layer (the whole polyolefin resin contained in the B layer) is, from the viewpoint of the behavior at the time of melting, 2-10 (g / 10min) is preferable, More preferably, it is 3-6 (g / 10min). In this specification, MFR can be measured according to JIS K7210. In addition, when the polyolefin resin contained in B layer is a mixed resin containing 2 or more types of polyolefin resin, said MFR is MFR of the mixed resin of all the polyolefin resins contained in B layer.

  Commercially available products may be used as the polyolefin resin (polyolefin resin contained in the B layer). For example, “Excellen XF5010” (LLDPE, homopolypropylene (propylene homopolymer), ethylene-made by Sumitomo Chemical Co., Ltd.) Propylene random copolymer, propylene-butene random copolymer, mixed resin containing ethylene-propylene block copolymer, and ethylene-propylene-butene random copolymer); “2040FC” manufactured by Ube Maruzen Polyethylene Co., Ltd., Japan “Kernel KF380”, “Kernel KF260T”, “Kernel KS340T” manufactured by Polyethylene Co., Ltd. “Evolue SP2040” manufactured by Prime Polymer Co., Ltd. (polyethylene resin); “Wintech WFX6” manufactured by Nippon Polypro Co., Ltd. Mitsubishi Chemical ( "Zeras # 7000, # 5000" (polypropylene resin) and the like manufactured by the same company can be used.

  The content of the aromatic polyester resin in the B layer (that is, the total content of all the aromatic polyester resins contained in the B layer) is based on the total weight (100% by weight) of the B layer. 5 to 40% by weight, preferably 10 to 35% by weight, more preferably 10 to 30% by weight. When the content is less than 5% by weight, the heat resistance of the B layer decreases, the interlayer strength during heating decreases, and delamination tends to occur during shrink processing. On the other hand, when the content exceeds 40% by weight, the flexibility of the B layer is lowered and the interlayer strength at normal temperature is lowered.

  The content of the polyolefin resin in the B layer (that is, the total content of all the polyolefin resins contained in the B layer) is 50 to 95 with respect to the total weight (100% by weight) of the B layer. % By weight, preferably 60 to 90% by weight, more preferably 65 to 80% by weight. If the said content is less than 50 weight%, the softness | flexibility of B layer will fall and the interlayer intensity | strength at normal temperature will fall. On the other hand, if the content exceeds 95% by weight, the heat resistance of the B layer decreases, the interlayer strength during heating decreases, and delamination tends to occur during shrink processing. Moreover, the interlayer strength at room temperature also decreases.

  The B layer may contain a polymer plasticizer from the viewpoint of high shrinkability and stretchability. Examples of the polymer plasticizer include rosin resin (rosin, polymerized rosin, hydrogenated rosin and derivatives thereof, resin acid dimer, etc.), terpene resin (terpene resin, aromatic modified terpene resin, hydrogenated terpene resin). Terpene-phenol resins, etc.), petroleum resins (aliphatic petroleum resins, aromatic petroleum resins, alicyclic petroleum resins) and the like. Among these, petroleum resin is preferable. The polymer plasticizer may be used alone or in combination of two or more. As the polymer plasticizer, “Arcon” manufactured by Arakawa Chemical Industry Co., Ltd., “Clearon” manufactured by Yashara Chemical Co., Ltd., “Imabe” manufactured by Idemitsu Kosan Co., Ltd., etc. are commercially available.

  When the polymer plasticizer is added, the content of the polymer plasticizer (particularly petroleum resin) in the B layer is preferably 1 to 10% by weight with respect to the total weight (100% by weight) of the B layer. More preferably, it is 1 to 5% by weight. When the said content exceeds 10 weight%, the heat resistance of B layer may fall. On the other hand, when the content is less than 1% by weight, the effect of adding the polymer plasticizer may be small.

  The layer B may contain other components (additional components) as necessary, for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, colorants, pinning agents ( Alkaline earth metal) and the like.

  B layer may contain the collection | recovery raw material (recycled material) in the range which does not impair the effect of this invention. However, the recovered raw material is preferably a product (so-called self-recovered product) produced from the production of the shrink film of the present invention.

[C layer]
The C layer is a resin layer containing at least a polypropylene resin. The said polypropylene resin may use only 1 type and may use 2 or more types.

  The polypropylene resin (that is, the polypropylene resin contained in the C layer) is a polymer composed of propylene as an essential monomer component, that is, derived from propylene in a molecule (in one molecule). It is a polymer containing at least a structural unit. Examples of the polypropylene resin include a propylene homopolymer (homopolypropylene); a copolymer composed of propylene and one or more olefins (olefins other than propylene) as essential monomer components (propylene copolymer). And the like). As the propylene copolymer, among them, a copolymer composed of propylene and one or more α-olefins as essential monomer components (propylene-α-olefin copolymer) is preferable. The propylene copolymer is a copolymer containing at least a structural unit derived from propylene and a structural unit derived from olefin in a molecule (in one molecule). The propylene-α-olefin copolymer is a copolymer containing at least a structural unit derived from propylene and a structural unit derived from α-olefin in the molecule (in one molecule). Examples of the α-olefin used as a copolymerization component of the propylene-α-olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-heptene. , 1-octene, 1-nonene, 1-decene and the like, such as α-olefin having 4 to 20 carbon atoms. The α-olefin may be used alone or in combination of two or more. The propylene copolymer (propylene-α-olefin copolymer or the like) may be a block copolymer or a random copolymer.

  Among the above, the propylene copolymer is particularly preferably an ethylene-propylene random copolymer (also referred to as propylene-ethylene random copolymer) containing ethylene as a copolymerization component. In the ethylene-propylene random copolymer, the ratio of ethylene to propylene is, for example, the former / the latter (weight ratio) = 2/98 to 5/95 (preferably 3/97 to 4.5 / 95.5). You can choose from a range of Moreover, as said propylene copolymer (especially ethylene-propylene random copolymer), a thing with an isotactic index of 90% or more is preferable from a viewpoint of low temperature shrinkage | contraction property and the strength of a shrink film.

  The polypropylene resin (that is, the polypropylene resin contained in the C layer) is polymerized using a metallocene catalyst from the viewpoint of improving low temperature shrinkage at about 60 to 80 ° C. and fitability to a container during heat shrinkage. A polypropylene resin (metallocene catalyst-based polypropylene resin) obtained in this manner is preferable. As the metallocene catalyst, a known or commonly used metallocene catalyst for olefin polymerization can be used. It does not specifically limit as a polymerization method (copolymerization method) of the said polypropylene resin, Well-known polymerization methods, such as a slurry method, solution polymerization method, and a gas phase method, are mentioned.

  Among the above polypropylene resins, metallocene catalyst homopolypropylene, metallocene catalyst propylene-α-olefin copolymer (particularly metallocene catalyst propylene-α-olefin random copolymer, metallocene catalyst propylene- Ethylene random copolymer) is particularly preferred.

  The propylene content in the polypropylene resin (the polypropylene resin contained in the C layer) (that is, the content of the structural unit derived from propylene in the polypropylene resin) is the shrinkage, strength and specific gravity of the shrink film. From the viewpoint, it is preferably 50 to 100% by weight, more preferably 60 to 100% by weight, based on the total weight (100% by weight) of the polypropylene resin.

  The weight average molecular weight of the polypropylene resin is preferably 100,000 to 500,000, more preferably 200,000 to 400,000, from the viewpoint of controlling the melting behavior of the resin forming the C layer within a preferable range.

  The melting point of the polypropylene resin is preferably 100 to 150 ° C, more preferably 120 to 140 ° C. In addition, the melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) of the polypropylene resin is preferably 0.1 to 10 g / 10 min, more preferably 1 to 5 g / min from the viewpoint of controlling the melting behavior. 10 minutes. If the melting point or MFR is out of the above range, the difference in melting characteristics and thermal characteristics between the resin forming the A layer and the resin forming the C layer becomes large, and sheeting or stretching by coextrusion during shrink film production. May become difficult, and may cause a decrease in productivity such as film breakage and a decrease in shrinkage due to insufficient orientation.

  The polypropylene resin (polypropylene resin contained in the C layer) may be a commercially available product, “Wintech WFX6” (metallocene catalyst propylene-ethylene random copolymer) manufactured by Nippon Polypro Co., Ltd., Mitsubishi. “Zerasu # 7000, # 5000” manufactured by Chemical Co., Ltd. is available on the market.

  The content of the polypropylene resin in the C layer (that is, the total content of all the polypropylene resins contained in the C layer) is 40% by weight with respect to the total weight (100% by weight) of the C layer. The above (40 to 100% by weight) is preferable, more preferably 50 to 94% by weight, and still more preferably 55 to 89% by weight. When the content of the polypropylene resin in the C layer is less than 40% by weight, the shrink film may not have a low specific gravity or shrinkage characteristics may be deteriorated.

The C layer may contain a polyethylene resin for the purpose of preventing film breakage and improving shrink workability. The polyethylene resin (that is, the polyethylene resin contained in the C layer) is a polymer composed of ethylene as an essential monomer component, that is, derived from ethylene in the molecule (in one molecule). It is a polymer containing at least a structural unit. The polyethylene-based resin is not particularly limited, and publicly known or commonly used polyethylene can be used. For example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene, medium density Examples include polyethylene and high density polyethylene (HDPE). Among these, low density polyethylene (including linear low density polyethylene and ultra-low density polyethylene) having a density of less than 0.930 (g / cm ³ ) is preferable, and linear low density polyethylene is particularly preferable. Furthermore, linear low density polyethylene (metallocene catalyst system LLDPE) polymerized using a metallocene catalyst is most preferred. The said polyethylene-type resin may use only 1 type, and may use 2 or more types. Commercially available products may be used as the polyethylene resin. For example, LLDPE “2040FC” manufactured by Ube Maruzen Polyethylene Co., Ltd., “Kernel KF380”, “Kernel KF260T”, “Kernel KS340T” manufactured by Nippon Polyethylene Co., Ltd. "Evolue SP2040" manufactured by Prime Polymer Co., Ltd. is available on the market.

  The content of the polyethylene-based resin in the C layer is preferably 1 to 10% by weight, more preferably 1 to 5% by weight with respect to the total weight (100% by weight) of the C layer.

  The C layer may contain a polymer plasticizer from the viewpoint of improving the shrinkability of the shrink film. Examples of the polymer plasticizer include rosin resin (rosin, polymerized rosin, hydrogenated rosin and derivatives thereof, resin acid dimer, etc.), terpene resin (terpene resin, aromatic modified terpene resin, hydrogenated terpene resin). Terpene-phenol resins, etc.), petroleum resins (aliphatic petroleum resins, aromatic petroleum resins, alicyclic petroleum resins) and the like. Among these, petroleum resin is preferable. The polymer plasticizer may be used alone or in combination of two or more. As the polymer plasticizer, “Arcon” manufactured by Arakawa Chemical Industry Co., Ltd., “Clearon” manufactured by Yashara Chemical Co., Ltd., “Imabe” manufactured by Idemitsu Kosan Co., Ltd., etc. are commercially available.

  When the polymer plasticizer is added, the content of the polymer plasticizer (particularly petroleum resin) in the C layer is preferably 5 to 30% by weight with respect to the total weight (100% by weight) of the C layer. More preferably, it is 10 to 25% by weight. When the said content exceeds 30 weight%, a shrink film may become weak. On the other hand, when the content is less than 5% by weight, the effect of adding the polymer plasticizer may be small.

  The layer C may contain other components (additive components) as necessary, for example, lubricants, fillers, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, colorants, pinning agents ( Alkaline earth metal) and the like.

  Said C layer may contain the collection | recovery raw material within the range which does not impair the effect of this invention. When the recovered material is a self-collected product, the content of the recovered material in the C layer is 1 to 80 with respect to the total weight (100% by weight) of the C layer from the viewpoints of recyclability and shrinkage. % By weight is preferred, more preferably 1 to 60% by weight. The recovered material is a recycled material composed of non-product parts before and after commercialization, film edges, etc., remaining parts when product films are collected from intermediate products, non-standard product film scraps, and polymer scraps. Although it does not specifically limit, The said collection | recovery raw material has arisen from manufacture of the shrink film of this invention (what is called a self-collection goods).

[Shrink film]
The shrink film of the present invention has a laminated structure in which an A layer, a B layer, and a C layer are laminated in the order of A layer / B layer / C layer without any other layer (laminated structure of three types and three layers). At least. Although the shrink film of this invention is not specifically limited, 3 types 3 layer lamination shrink films of A layer / B layer / C layer and 3 types 5 layer lamination of A layer / B layer / C layer / B layer / A layer A shrink film is preferred. In addition, the above-mentioned “laminated in the order of A layer / B layer / C layer without other layers” means more specifically the order of A layer / B layer / C layer and A layer The B layer is laminated without sandwiching other layers such as an adhesive layer between both layers, and the B layer and the C layer are laminated without sandwiching other layers such as an adhesive layer between both layers. Indicates that

  The above laminated structures (for example, A layer / B layer / C layer, 3 layers, 3 layers, A layer / B layer / C layer / B layer / A layer, 3 layers, 5 layers, etc.) are co-extruded. It is preferably formed by.

  The shrink film of the present invention is an oriented film (uniaxially oriented film, biaxially oriented film or multiaxially oriented film) from the viewpoint of shrinkage characteristics. It is preferable that all the resin layers of the A layer, the B layer, and the C layer in the shrink film of the present invention are oriented. When all the resin layers are non-oriented, good shrinkage cannot be obtained. Although the shrink film of the present invention is not particularly limited, a uniaxially oriented film or a biaxially oriented film is preferable, and among these, the uniaxial direction of the film [particularly, the width direction of the film (in the case of a cylindrical shrink label, the circumferential direction of the label). Direction)] is preferred (especially a substantially monoaxially oriented film in the width direction). It may be a substantially uniaxially oriented film in the longitudinal direction that is strongly oriented in the longitudinal direction of the film (direction perpendicular to the width direction).

  In the shrink film of the present invention, the thickness of the A layer (only one layer) is not particularly limited, but is preferably 2 to 15 μm, more preferably 3 to 10 μm. If the thickness of the A layer exceeds 15 μm, the shrinkage stress of the A layer becomes too high, and delamination during shrink processing cannot be suppressed, or the shrinkage may occur rapidly and the finish may be lowered. On the other hand, if the thickness is less than 2 μm, the shrinkage may be insufficient or the strength of the shrink film may be reduced. In particular, when the shrink film of the present invention has a laminated structure of 3 types and 5 layers of A layer / B layer / C layer / B layer / A layer, from the viewpoint of preventing delamination, the thickness of the A layer (1 The thickness of the layer alone is more preferably 3 to 8 μm, still more preferably 3 to 7.5 μm. In the case of having a laminated structure of the above three types and five layers, delamination may easily occur when the thickness of the A layer exceeds 8 μm.

  In the shrink film of the present invention, the thickness of the B layer (thickness of only one layer) is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 1 to 8 μm. When the thickness of the B layer exceeds 10 μm, the stretchability of the shrink film may be lowered, and when it is less than 0.5 μm, the adhesive strength is lowered, the interlayer strength is lowered, and delamination is likely to occur.

  In the shrink film of the present invention, the thickness of the C layer (thickness of only one layer) is not particularly limited, but is preferably 10 to 70 μm, more preferably 15 to 50 μm. If the thickness of the C layer exceeds 70 μm, the thermal shrinkage rate may decrease. If the thickness of the C layer is less than 10 μm, the shrinkage stress difference with the A layer becomes too large, and delamination during shrink processing cannot be suppressed, or the shrinkage is rapid. May occur and the finish may be reduced.

  In the shrink film of the present invention, the ratio of the total A layer thickness (total thickness of all A layers in the shrink film) to the total C layer thickness (total thickness of all C layers in the shrink film) 100% is It is preferably 40 to 150%, more preferably 50 to 100%. If the total A layer thickness is too small relative to the total C layer thickness, the shrinkage of the shrink film may be insufficient (the thermal shrinkage rate will be reduced) or the shrink strength of the shrink film may be reduced and the processability may be reduced. is there. On the other hand, if the total A layer thickness is too large relative to the total C layer thickness, the contraction stress of the A layer increases, and the contraction stress difference between the A layer and the C layer becomes too large. Even if it exists, delamination may not be suppressed. In addition, since the shrink film of this invention has B layer, even if it is a case where A layer thickness is comparatively thick with respect to C layer thickness, delamination is suppressed, and shrinkage, waist strength and delamination deterrence are compatible. This is preferable.

  In the shrink film of the present invention, the ratio of the total B layer thickness (the total thickness of all B layers in the shrink film) to the total C layer thickness of 100% is preferably 5 to 100%, more preferably 10 to 50%. It is. If the total B layer thickness is too small with respect to the total C layer thickness, the adhesive strength of the B layer may decrease, the interlayer strength may decrease, and delamination may easily occur. On the other hand, if the total B layer thickness is too thick relative to the total C layer thickness, the stretchability of the shrink film may be reduced.

  Although the total thickness of the shrink film of this invention is not specifically limited, 20-100 micrometers is preferable, More preferably, it is 20-80 micrometers, More preferably, it is 20-50 micrometers.

  In the shrink film of the present invention (before shrink processing), the interlayer strength at 23 ° C. (room temperature) (sometimes referred to as room temperature interlayer strength) is preferably 1 (N / 15 mm) or more, more preferably 1.5 (N / 15 mm) or more. When the interlayer strength is less than 1 (N / 15 mm), the resin layers are peeled off during processing steps (printing process of shrink labels) such as printing and processing into a cylindrical shape, resulting in decreased productivity. May be a quality problem. In addition, the said interlayer strength means the intensity | strength between layers with the lowest interlayer strength in a shrink film in a T-type peeling test (based on JISK6854-3, tensile speed: 200 mm / min).

  The shrinkage rate of the shrink film of the present invention (before shrink processing) in the main orientation direction at 90 ° C. for 10 seconds (warm water treatment) (sometimes referred to as “thermal shrinkage rate (90 ° C., 10 seconds)”). Although not particularly limited, it is preferably 35% or more, more preferably 35 to 80%, and still more preferably 40 to 80%. When the thermal shrinkage rate (90 ° C., 10 seconds) is less than 35%, the shrink label is not sufficiently contracted in the process of heat-adhering the shrink label to the container, making it difficult to follow the shape of the container. The finish may be poor for the container. The above-mentioned “main orientation direction” is a direction mainly subjected to a stretching process (a direction having the largest thermal shrinkage), and is generally a longitudinal direction or a width direction, for example, substantially in the width direction. In the case of a film uniaxially stretched (substantially a uniaxially oriented film in the width direction), it is the width direction.

  In addition, although the thermal contraction rate (90 degreeC, 10 second) of the direction orthogonal to the main orientation direction of the shrink film (before shrink process) of this invention is not specifically limited, -5-10% is preferable.

  The haze (haze) value [conforming to JIS K 7105, converted to a thickness of 40 μm, unit:%] of the shrink film of the present invention is preferably less than 15%, more preferably less than 7%, and still more preferably less than 5%. When the haze value is 15% or more, printing is performed on the inside of the shrink film (the side that becomes the container side when the shrink label is attached to the container), and the shrink label that shows the print through the shrink film is the product. In some cases, the printing may become cloudy and the decorativeness may deteriorate. However, even if the haze value is 15% or more, it can be sufficiently used in applications other than the above-described applications that show printing through a shrink film.

  The shrink film of the present invention is preferably produced by a melt film forming method. The laminated structure is preferably formed by coextrusion (multilayer extrusion). That is, the shrink film of the present invention is preferably produced by a melt extrusion method (particularly a coextrusion method). More specifically, the shrink film of the present invention is preferably produced by forming an unstretched film (unstretched sheet) by melt extrusion (coextrusion) and then stretching the unstretched film. Further, the surface of the shrink film may be subjected to a conventional surface treatment such as a corona discharge treatment, if necessary.

  When a mixed raw material is used as a raw material for forming each resin layer (for example, A layer, B layer, C layer) of the shrink film, the mixing method of each component is not particularly limited. For example, the mixed raw material is prepared by dry blending. Alternatively, each component may be melt-kneaded using a uniaxial or biaxial kneader to obtain a mixed raw material. Moreover, you may use a master pellet (For example, what mixed the specific component with comparatively high density | concentration).

  In the melt extrusion (coextrusion), raw materials (resin or resin composition) for forming each resin layer (A layer, B layer, C layer, etc.) are respectively formed in a plurality of extruders each set to a predetermined temperature. And melt extrusion (coextrusion) from a T die, a circular die or the like. At this time, it is preferable to use a manifold or a feed block to form a predetermined layer structure. Further, if necessary, the supply amount may be adjusted using a gear pump, and it is preferable to remove foreign substances using a filter because film tearing can be reduced. The extrusion temperature varies depending on the type of raw material used and is not particularly limited. However, it is preferable that the molding temperature region of the raw material forming each resin layer is close. That is, it is preferable that the extrusion temperature of each resin layer is close. Specifically, the extrusion temperature of the raw material forming the A layer is preferably 200 to 260 ° C., the extrusion temperature of the raw material forming the B layer is 180 to 240 ° C., and the extrusion temperature of the raw material forming the C layer is 180 to 240. ° C is preferred. Moreover, it is preferable that the temperature of a junction part or die | dye shall be 200-220 degreeC. An unstretched laminated film (sheet) can be obtained by quenching the coextruded polymer using a cooling drum (cooling roll) or the like.

  Oriented films such as uniaxial orientation and biaxial orientation can be produced by stretching an unstretched laminated film. The stretching can be selected according to the desired orientation, and for example, the longitudinal direction (film production line direction; also referred to as longitudinal direction or MD direction) and the width direction (direction perpendicular to the longitudinal direction; also referred to as lateral direction or TD direction). ) Biaxial stretching, or uniaxial stretching in the longitudinal direction or the width direction. The stretching method may be any method such as a roll method, a tenter method, and a tube method. The stretching conditions in the stretching process vary depending on the type of raw material used and the required characteristics of the shrink film, and are not particularly limited. In general, it is preferably carried out at a stretching temperature of 70 to 110 ° C. (preferably 80 to 95 ° C.) at a stretching ratio of about 2 to 8 times in at least one of the longitudinal direction and the width direction. For example, the film stretched substantially uniaxially in the width direction is, for example, about 1.01 to 1.5 times (preferably 1.05 to 1.3 times) in the longitudinal direction as necessary. After stretching, it is preferable to stretch about 2 to 7 times (preferably 3 to 6.5 times, more preferably 4 to 6 times) in the width direction.

  In the shrink film of the present invention, the A layer is mainly composed of an aromatic polyester resin and is highly shrinkable. Therefore, providing the A layer improves the shrinkability (high shrinkage rate, high shrinkage stress) of the shrink film. In addition, the mounting property to the container and the finish are good. In addition, since the A layer is highly rigid, providing the A layer improves the waist strength of the shrink film. For example, the wearability when the cylindrical shrink label is attached to the container is improved. Troubles such as “bend” are unlikely to occur. Moreover, when A layer is used as a surface layer, the printability, abrasion resistance, and chemical resistance of the shrink film surface are improved. Since the C layer is mainly composed of a polypropylene resin, the shrink film has a low specific gravity by providing the C layer. In addition, rapid shrinkage of the shrink film can be suppressed and the shrinkage behavior can be moderated, and the handleability during shrink processing is improved. Since the shrink film of the present invention is formed by laminating the A layer and the C layer, it is excellent in shrinkage and workability, and it is possible to achieve both characteristics such as low specific gravity, waist strength, and printability. .

  However, the A-layer aromatic polyester resin and the C-layer polypropylene resin differ greatly in shrinkage behavior (heat shrinkage behavior) and shrinkage stress (heat shrinkage stress) (the shrinkage stress of the aromatic polyester resin is large). . For this reason, when shrink processing (thermal shrinkage processing) is applied to a laminated shrink film having an A layer and a C layer, a difference occurs in the shrinkage behavior between the A layer and the C layer. Delamination easily occurs. The above phenomenon occurs particularly noticeably at the center seal portion when the shrink film is used as a cylindrical shrink label. This is presumably because in the center seal portion, one surface side is fixed by the center seal, so that the influence of the shrinkage of the unfixed surface side resin layer is increased. On the other hand, the present inventors use a shrink film provided with a specific intermediate layer composed mainly of an ethylene-vinyl acetate resin between the A layer and the C layer, thereby delamination during shrink processing. Succeeded in improving deterrence (see International Publication No. 2009/084212 pamphlet). However, when the shrink processing conditions of the shrink film are increased (for example, 95 to 100 ° C.), the heat resistance of the intermediate layer is insufficient, the intermediate layer is softened, and the delamination inhibiting effect is reduced. was there.

  In contrast, in the shrink film of the present invention, a B layer containing an aromatic polyester resin and a polyolefin resin having a specific structural unit in a specific ratio is provided between the A layer and the C layer. Since the B layer contains a polyolefin-based resin, the flexibility is high under heating during shrink processing, thereby improving the followability to the A layer and C layer during shrink processing. In addition, since the B layer further contains an aromatic polyester resin, the heat resistance is relatively high, and the B layer does not become too soft even at high temperatures. For this reason, even when the shrink processing conditions are increased in temperature, a high interlayer strength can be maintained. Furthermore, in the present invention, as the polyolefin resin used for the B layer, a specific polyolefin resin containing a specific amount of a structural unit derived from ethylene and a structural unit derived from propylene and further having a structural unit derived from butene is used. ing. Thereby, the B layer is excellent in flexibility even at room temperature while having flexibility and heat resistance under heating. Thereby, the shrink film of this invention has high interlayer intensity | strength also at normal temperature. Therefore, the shrink film of the present invention has high interlaminar strength both at room temperature and during heating (during shrink processing), and can exhibit the characteristics that delamination hardly occurs.

  In addition, when an aromatic polyester-based resin and a polypropylene-based resin other than the specific polyolefin-based resin used in the present invention are used for the intermediate layer, a shrink film that exhibits a relatively high interlayer strength when heated is obtained. However, the shrink film has low interlaminar strength at room temperature, and there is a problem that delamination is likely to occur during manufacture or transportation of the shrink film. In addition, when a polyolefin resin other than the specific polyolefin resin used in the present invention, which is composed only of an aromatic polyester resin and LLDPE, is used for the intermediate layer, only the intermediate layer has elasticity. Therefore, the A layer is deformed into a bellows shape after stretching at the time of manufacturing the shrink film, the smoothness of the surface of the shrink film is impaired, and further, delamination occurs after the shrink processing.

[Shrink label]
The shrink film of the present invention can be preferably used as a shrink label. In the present specification, a shrink label including the shrink film of the present invention may be referred to as “shrink label of the present invention”. As a shrink label of this invention, the shrink label which has a printing layer in the at least one surface side of the shrink film (base material) of this invention is mentioned, for example. In addition to the printed layer, the shrink label of the present invention includes a protective layer, an anchor coat layer, a primer coat layer, an adhesive layer (for example, a pressure-sensitive adhesive layer, a heat-sensitive adhesive layer, etc.), a coating layer, and the like. It may have, and may have layers, such as a nonwoven fabric and paper, further. Examples of the layer structure of the shrink label of the present invention include, for example, printing layer / A layer / B layer / C layer / B layer / A layer, printing layer / A layer / B layer / C layer / B layer / A layer / printing. Layers and the like are preferred. In addition, the shrink film of this invention can also be used as a shrink label by itself even when a printing layer is not provided. In other words, the shrink label of the present invention may be a shrink label made only of the shrink film of the present invention.

  The print layer is, for example, a layer displaying a product name, an illustration, handling precautions, and the like. The printing layer is formed, for example, by applying printing ink. The coating method is preferably an off-line coating in which coating is performed using a known and commonly used printing method after forming a shrink film from the viewpoint of productivity, workability, and the like. As a printing method, a conventional method can be used, and for example, gravure printing or flexographic printing is preferable. The printing ink used for forming the printing layer contains, for example, a pigment, a binder resin, a solvent, other additives, and the like. The binder resin is not particularly limited, and for example, acrylic resin, urethane resin, polyamide resin, vinyl chloride-vinyl acetate copolymer resin, cellulose resin, nitrocellulose resin, and the like can be used. The pigment is not particularly limited. For example, white pigments such as titanium oxide (titanium dioxide), indigo pigments such as copper phthalocyanine blue, carbon black, aluminum flakes, mica (mica), and other colored pigments are used according to the application. Can be selected and used. In addition, extender pigments such as alumina, calcium carbonate, barium sulfate, silica, and acrylic beads can also be used as pigments for the purpose of adjusting gloss. As said solvent, what is normally used for printing inks, such as organic solvents, such as toluene, xylene, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and water can be used, for example. Each of the pigment, binder resin, and solvent may be used alone or in combination of two or more.

  Although the said printing layer is not specifically limited, Active energy ray-curable resin layers, such as visible light, an ultraviolet-ray, and an electron beam, may be sufficient. This is effective for preventing deformation of the film due to excessive heat.

  Although the thickness of the said printing layer is not specifically limited, For example, 0.1-10 micrometers is preferable. If the thickness is less than 0.1 μm, it may be difficult to provide a uniform printing layer, and partial “blur” may occur, resulting in a loss of decorativeness or printing as designed. May be difficult. In addition, when the thickness exceeds 10 μm, a large amount of printing ink is consumed, which increases the cost, makes it difficult to apply uniformly, makes the printed layer brittle and easily peels off. . Moreover, the rigidity of a printing layer becomes high and a printing layer may become difficult to follow shrinkage | contraction of a shrink film at the time of shrink processing.

  The shrink label of the present invention is, for example, a cylindrical shrink label of a type in which both ends of the label are sealed with a solvent or an adhesive and attached to the container, and one end of the label is attached to the container, and the label is wound After that, it can be used as a wrapping type shrink label in which the other end is overlapped with one end to form a cylinder. Among the above, the shrink film of the present invention is particularly effective for the cylindrical shrink label from the viewpoint that it is most effective in suppressing delamination (attachment delamination) at the center seal portion when the cylindrical shrink label is attached to the container. Preferably used. That is, the shrink label of the present invention is preferably a cylindrical shrink label.

  The shrink label of the present invention may be processed into a cylindrical shrink label. For example, the shrink label is formed in a cylindrical shape so that the main orientation direction is the circumferential direction. Specifically, a shrink label having a predetermined width in the main orientation direction is formed into a cylindrical shape by overlapping both ends of the main orientation direction so that the front side of the shrink label is an outer surface (outer side), and one side of the label Apply a solvent or adhesive (such as “adhesive” or the like hereinafter) such as tetrahydrofuran (THF) on the inner surface to the edge with a width of about 2 to 4 mm in a band shape, Adhere to the outer surface of the other side edge to obtain a cylindrical shrink label. In addition, it is preferable that the printing layer is not provided in the part which applies said adhesive agent etc., and the part to adhere | attach. In the above description, the “front side” of the shrink label means the side of viewing the label design (the side of the surface on which the design looks correct). In addition, the “outer surface” of the shrink label means the surface on the side that is not in contact with the container (the side opposite to the container, that is, the outside of the cylinder) when the shrink label is attached to the container. "Means the surface on the side in contact with the container (container side).

  In addition, when providing the perforation for label cutting to a cylindrical shrink label, the perforation of predetermined length and a pitch is formed in the direction orthogonal to the circumferential direction. The perforation can be applied by a conventional method (for example, a method of pressing a disk-shaped blade having a cut portion and a non-cut portion repeatedly formed around it, a method using a laser, or the like). The process stage for perforating can be appropriately selected after the printing process and before and after the cylindrical processing process.

  The center seal strength of the cylindrical shrink label is preferably 2N / 15 mm or more. If the center seal strength is less than 2 N / 15 mm, the center seal portion may be peeled off after processing or commercialization, thereby reducing productivity and causing label dropout.

  Although the shrink label of this invention is not specifically limited, It mounts | wears with containers, such as a container for drinks, and is used as a container with a label. In addition, the shrink label of this invention may be used for adherends other than a container. The shrink label of the present invention (in particular, the cylindrical shrink label) is attached to the container by, for example, placing the front side on the opposite side of the container and heat shrinking, thereby attaching a labeled container (the shrink label of the present invention). A labeled container) is obtained. Examples of the container include a soft drink bottle such as a PET bottle, a milk bottle for home delivery, a food container such as a seasoning, an alcoholic beverage bottle, a pharmaceutical container, a detergent container, a chemical container such as a spray, and a cup noodle container. Etc. are included. Although it does not specifically limit as a shape of the said container, For example, various shapes, such as bottle types, such as cylindrical shape and a square shape, and a cup type, are mentioned. The material of the container is not particularly limited, and examples thereof include plastic such as PET, glass, and metal.

  The labeled container can be produced, for example, by externally fitting a cylindrical shrink label to a predetermined container, and then thermally shrinking the cylindrical shrink label by heat treatment so as to follow and closely adhere to the container (shrink processing). Examples of the heat treatment method include a method of passing through a hot air tunnel or a steam tunnel, a method of heating with radiant heat such as infrared rays, and the like. In particular, a method of treating with steam at 80 to 100 ° C. (passing through a heating tunnel filled with steam and steam) is preferable. Moreover, 101-140 degreeC dry steam can also be used. Although the said heat processing is not specifically limited, It is preferable to implement in the temperature range from which the temperature of a shrink film will be 85-100 degreeC (especially 90-97 degreeC). Since the shrink film of the present invention can be heat-treated at a particularly high temperature, it can be used for containers that require high shrinkage. Moreover, the processing time of heat processing has preferable 4 to 20 second from a viewpoint of productivity and economical efficiency.

  Even if the shrink label (especially cylindrical shrink label) using the shrink film of the present invention is attached to a container by shrink processing (heat shrink processing), even when subjected to shrink processing under high temperature conditions, In particular, the center seal portion is preferable because delamination (mounting delamination) hardly occurs.

  EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following, for the sake of convenience, the surface layer is also referred to as the A layer, the center layer as the C layer, and the intermediate layer between the surface layer and the center layer as the B layer for convenience.

  Table 1 shows the types and contents (% by weight) of the A layer raw material, the B layer raw material, and the C layer raw material in Examples and Comparative Examples; the content of the aromatic polyester resin and polyolefin resin in the B layer ( % By weight); E ′ (30 ° C.) and E ′ (90 ° C.) of the resin composition constituting the B layer are described. Moreover, the stretch conditions (stretching temperature / stretching ratio) at the time of manufacturing the shrink film; the thickness (total layer thickness) of the obtained shrink film, the layer thickness ratio, the evaluation results, and the like are shown.

  Table 2 describes the resin used in the examples and comparative examples (manufacturer, resin name (trade name), resin configuration).

Example 1
As a raw material constituting the A layer (A layer raw material), 100% by weight of CHDM copolymerized PET (“EMBRACE LV” manufactured by Eastman Chemical Co., aromatic polyester resin (a-1)) was used.
As raw materials constituting the B layer (B layer raw material), CHDM copolymerized PET (“EMBRACE LV” manufactured by Eastman Chemical Co., aromatic polyester resin (a-1)) 10% by weight, metallocene catalyst propylene-ethylene random Copolymer ("Wintech WFX6" manufactured by Nippon Polypro Co., Ltd., polyolefin resin (b-1)) 14% by weight, polyolefin mixed resin ("Excellen XF5010" manufactured by Sumitomo Chemical Co., Ltd.), polyolefin resin (b -2)) 70 wt%, linear low density polyethylene (LLDPE) (Nippon Polyethylene "Kernel KF260T") 1 wt%, and petroleum resin (Arakawa Chemical Industries "Alcon P125") 5 % By weight was used. The polyolefin-based mixed resin (Excellen XF5010) is composed of 60% by weight of linear low density polyethylene (LLDPE), homopolypropylene (propylene homopolymer), ethylene-propylene random copolymer, propylene-butene random copolymer. , An ethylene-propylene block copolymer, and an ethylene-propylene-butene random copolymer mixed resin (the total amount of resins other than LLDPE is about 40% by weight).
As a raw material constituting the C layer (C layer raw material), metallocene catalyst propylene-ethylene random copolymer (Nippon Polypro Co., Ltd. “Wintech WFX6”, polyolefin resin (b-1)) 53 wt%, petroleum 17% by weight of resin (“Arcon P125” manufactured by Arakawa Chemical Industries, Ltd.) and 30% by weight of recovered raw material (recycled material) were used. Moreover, the said collection | recovery raw material arises from manufacture of the shrink film of a present Example (what is called collection | recovery raw material by self-collection). In the following examples and comparative examples, the recovered raw materials obtained by self-collection in the respective examples and comparative examples were used as the recovered raw materials.

The layer A raw material was charged into an extruder a heated to 220 ° C., the layer B raw material was charged into an extruder b heated to 220 ° C., and the layer C raw material was charged into an extruder c heated to 220 ° C. Melt extrusion (coextrusion) was performed using the three extruders. The resin extruded from the extruder c becomes the center layer, the resin extruded from the extruder b becomes the layers (intermediate layer) on both sides of the center layer, and the resin extruded from the extruder a becomes the layers on both sides (surface layer). Thus, after merging using a merging block and extruding from a T die (slit interval: 1 mm), it was rapidly cooled on a casting drum cooled to 25 ° C. to obtain a three-kind five-layer laminated unstretched film.
Next, the unstretched film whose thickness was adjusted was stretched 5 times at 90 ° C. in the width direction to obtain a shrink film (substantially a uniaxially oriented film in the width direction). The total thickness (total layer thickness) of the obtained shrink film was 35 μm, and the layer thickness ratio (A layer: B layer: C layer: B layer: A layer) was 3: 1: 8: 1: 3.

  In addition, content of the aromatic polyester-type resin in B layer of the said shrink film is 10 weight%, and content of polyolefin resin is 85 weight%.

Examples 2-3, Examples 7-8, Comparative Examples 1-2
As shown in Table 1, a shrink film was obtained in the same manner as in Example 1 except that the B layer material was changed.

Example 4, Comparative Examples 3-4
As shown in Table 1, a shrink film was obtained in the same manner as in Example 1 except that the B layer material and the C layer material were changed.

Examples 5-6
As shown in Table 1, a shrink film was obtained in the same manner as in Example 1 except that the A layer raw material and the B layer raw material were changed.

In addition, in the shrink film obtained by the said Examples 1-8 and Comparative Examples 1-2, content of the structural unit derived from ethylene in all the polyolefin resin (100 weight%) contained in B layer. Is in the range of 40 to 68% by weight, the content of the structural unit derived from propylene is in the range of 30 to 55% by weight, and the content of the structural unit derived from butene is in the range of 1 to 20% by weight. It was.
In the shrink film obtained in Comparative Example 3 above, the content of structural units derived from ethylene in all polyolefin resins (100% by weight) contained in the B layer is 8% by weight, derived from propylene. The content of the structural unit was 92% by weight, and the content of the structural unit derived from butene was 0% by weight.
In the shrink film obtained in Comparative Example 4, the content of structural units derived from ethylene in all polyolefin resins (100% by weight) contained in the B layer is 57% by weight, derived from propylene. The content of the structural unit was 24% by weight, and the content of the structural unit derived from butene was 0% by weight.

(Evaluation)
The shrink films obtained in Examples and Comparative Examples and the raw materials used in Examples and Comparative Examples were evaluated by the following methods.
In addition, the shrink film after forming into a film, continuing collection | recovery (self-collection) for 40 hours or more was used for evaluation.

(1) Room temperature interlayer strength (T-type peel test)
About the shrink film (before shrink process) produced by the Example and the comparative example, the normal temperature interlayer intensity | strength was measured with the following method.
From the shrink film, a rectangular sample with a width of 15 mm in the longitudinal direction of the shrink film (shrink film forming direction) and a length of 200 mm in the width direction of the shrink film (direction perpendicular to the longitudinal direction) Film width direction) × width 15 mm (longitudinal direction of shrink film)]. In the following, the long side direction of the sample refers to the width direction of the shrink film, and the width direction of the sample refers to the longitudinal direction of the shrink film.
With the long side direction of the sample (the width direction of the shrink film) as the measurement direction, a T-type peel test (based on JIS K 6854-3) was performed under the following conditions to measure the peel load between the layers.
The average value of the peeling load was the room temperature interlayer strength (N / 15 mm).
(Measurement condition)
Measuring device: Autograph manufactured by Shimadzu Corporation (AG-IS: load cell type 500N)
Temperature and humidity: Temperature 23 ± 2 ℃, humidity 50 ± 5% RH
Initial chuck interval: 40 mm
Sample width: 15mm
Number of tests: 3 times Tensile speed: 200 mm / min Stroke: 150 mm (If it broke, it was interrupted and data up to that point was obtained.)
First half deletion range: 50mm
Sensitivity: 1
The room temperature interlayer strength was evaluated by peeling the layers having the weakest interlayer strength in the laminated structure. If the room temperature interlayer strength is 1.0 (N / 15 mm) or more, it can be determined that the interlayer strength is good.

(2) Heated interlayer strength From the shrink film (before shrink processing) produced in Examples and Comparative Examples, a rectangular sample having a width of 15 mm in the longitudinal direction of the shrink film and a length of 200 mm in the width direction of the shrink film [ Length 200 mm (width direction of shrink film) × width 15 mm (length direction of shrink film)] was collected. In the following, the long side (longitudinal) direction of the sample refers to the width direction of the shrink film, and the width direction of the sample refers to the longitudinal direction of the shrink film.
Using the above samples, the heated interlayer strength was measured by the following method. In addition, in FIG. 1, explanatory drawing (schematic diagram) explaining the measuring method of warming interlayer intensity | strength is shown. In FIG. 1, 11 and 12 are chucks (gripping tools), 13 is a load detector, 21 is a sample (shrink film; A layer / B layer / C layer / B layer / A layer configuration of 3 types and 5 layers), Reference numeral 22 denotes an A layer on one side of the sample 21, 23 denotes a portion other than the A layer 22 on one side of the sample 21, and an arrow F denotes a load direction.
From the sample 21, the A layer 22 on one side was peeled from one end portion in the long side direction of the sample to a length of 120 mm in the long side direction (that is, the length of the non-peeled portion is 80 mm). . In the examples and comparative examples, the above-described peeling occurs between the A layer and the B layer. (However, if the interlayer strength between the B layer and the C layer is weaker, the sample may be peeled off between the B layer and the C layer.)
As shown in FIG. 1, the sample 21 after peeling was set on the two chucks 11 and 12 of the measuring device in the same manner as in the case of the T-type peeling test in which the long side direction of the sample was the measurement direction. One chuck 12 is set with the A layer portion (A layer 22 on one side) peeled off as described above, and the other chuck 11 is the remaining portion (other than the A layer 22 on one side) with the A layer peeled off. Part 23) was set. The chuck 12 is fixed to a measuring device. Further, the interval between the chuck 11 and the chuck 12 (chuck interval) is kept constant at 35 mm. Further, a load detector 13 (“Digital Force Gauge DPS-2R” manufactured by Imada Co., Ltd.) is connected to the chuck 11, and the long side direction of the sample 21 (direction of arrow F in FIG. 1). Can be detected. The sample 21 was set so that there was no slack in the sample portion between the chucks, and the load detected immediately after setting the sample was 0 (N / 15 mm).
Next, the measurement device on which the sample 21 is set is immersed in warm water at 95 ° C., and the load generated when the chuck interval is maintained at 35 mm (the load in the long side direction of the sample 21: the direction of arrow F in FIG. 1) ) Was measured. The average value of the load for 5 to 10 seconds after being immersed in warm water was measured, and the average value of the load was defined as the heated interlayer strength (N / 15 mm).
In the above measurement, since the sample 21 contracts (heat shrinks) in the long side direction (the main orientation direction of the shrink film) by being immersed in warm water, the sample 21 extends in the long side direction (the direction of the arrow F). Causes contraction force. At this time, when the interlayer strength of the shrink film is low, delamination occurs, and thus the detected (measured) load becomes small. The warming interlayer strength is preferably 0.5 N / 15 mm or more.
(Measurement condition)
Load detector: manufactured by Imada Co., Ltd., “Digital Force Gauge (DPS-2R)”
Chuck interval: 35mm
Sample width: 15mm
Number of tests: 3 times

(3) Thermal shrinkage in main orientation direction (90 ° C., 10 seconds)
From the shrink film (before shrink processing) obtained in the examples and comparative examples, a length of 120 mm (mark interval 100 mm) and a width of 5 mm in the measurement direction (main orientation direction: width direction of the shrink film in the examples and comparative examples) A rectangular sample was prepared.
The sample was heat-treated in warm water at 90 ° C. for 10 seconds (under no load), the difference between the marked line intervals before and after the heat treatment was read, and the thermal contraction rate (90 ° C., 10 seconds) was calculated by the following formula.
Thermal shrinkage (90 ° C., 10 seconds) (%) = (L ₀ −L ₁ ) / L ₀ × 100
L ₀ : Mark interval before heat treatment (main orientation direction)
L ₁ : Marking interval after heat treatment (main orientation direction)

(4) E ′ (30 ° C.), E ′ (90 ° C.) (dynamic viscoelasticity measurement)
Using the B layer raw material as a sample, dynamic viscoelasticity measurement was performed under the following conditions. Storage elastic moduli at 30 ° C. and 90 ° C. were respectively determined.
(Measurement equipment, measurement conditions)
Apparatus: Seiko Instruments Inc. "EXSTAR6000 DMS6100"
Frequency: 10Hz
Temperature rising rate: 2 ° C./min Measurement sample: 0.9 to 1.0 mm thick sheet formed by melting resin pellets at 200 ° C.

  As can be seen from Table 1, the shrink film (Example) of the present invention exhibited high interlayer strength at both 23 ° C. and 95 ° C. On the other hand, the shrink film (Comparative Example 1) containing no aromatic polyester-based resin in the B layer had a low warming interlayer strength and an insufficient interlayer strength at a high temperature. Moreover, there is too little content of the structural unit derived from ethylene in the shrink film (comparative example 2) and the polyolefin-type resin contained in B layer, where there is too much content of the aromatic polyester-type resin in B layer ( The shrink film (Comparative Example 3) in which the content of the structural unit derived from propylene was too high) had low room temperature interlayer strength and insufficient interlayer strength at room temperature. Furthermore, the shrink film (Comparative Example 4) that does not contain the structural unit derived from butene in the polyolefin-based resin contained in the B layer had low warming interlayer strength and insufficient interlayer strength at high temperatures.

11 Chuck (Load detection side)
12 Chuck (fixed side)
13 Load detector 21 Sample (Shrink film)
22 A layer on one side of sample 23 Part other than A layer on one side of sample F Load direction

Claims (4)

A resin layer (A layer) containing an aromatic polyester resin;
A resin layer (B layer) containing 5 to 40% by weight of an aromatic polyester resin and 50 to 95% by weight of a polyolefin resin;
A resin layer (C layer) containing a polypropylene resin,
In the order of A layer / B layer / C layer, it has a laminated structure laminated without any other layers,
A shrink film, wherein the polyolefin-based resin contains 35 to 75% by weight of a structural unit derived from ethylene, 15 to 60% by weight of a structural unit derived from propylene, and a structural unit derived from butene.   The storage elastic modulus in 30 degreeC of the resin composition which comprises the said B layer calculated | required by dynamic viscoelasticity measurement is 350-950 MPa, and the storage elastic modulus in 90 degreeC is 25-100 MPa. Shrink film.   The shrink film of Claim 1 or 2 which has a laminated structure laminated | stacked without passing through another layer in order of A layer / B layer / C layer / B layer / A layer.   The shrink label containing the shrink film of any one of Claims 1-3.

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