JP2018153984A - Heat-shrinkable laminated porous film and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shrinkable laminated porous film and a coated article which can reduce the gap between the coated article and the coated article and have excellent easy-opening property when the coated article is opened. SOLUTION: A heat-shrinkable laminated porous film 1 is a pair of front and back surfaces having at least one selected from the group consisting of a copolymer resin (A) of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon as a main component. A porous layer 12 provided between the layers 111 and 112 and the pair of front and back layers 111 and 112 and containing a resin composition containing a polyolefin resin (B) and a filler (C) as a main component is provided, and at least. It is stretched in one direction. [Selection diagram] Fig. 1

Description

  The present invention relates to a heat-shrinkable laminated porous film and a coated article coated with the film. For example, the heat-shrinkable laminated porous film and the film suitably used for applications such as shrink-wrapping, shrink-bound packaging, and shrinkage labels are provided. The present invention relates to a coated article.

  At present, goods purchased by mail order etc. are various according to various goods by various packing materials such as cardboard, molding box and cushioning material in order to prevent destruction and damage of goods due to impact during transportation and transportation. Packing is done. Moreover, in such various packing materials, various devices have been made from the viewpoint of easy opening when opening a packaged article.

  In the various packing materials described above, a gap may be formed between the packed article and the packing material. For this reason, the gap between the packed article and the packing material is filled with another packing material, or the film is covered with the article and fixed in the air, so that the space between the packed article and the packing material is The gap is reduced. However, when the clearance is reduced by these, the volume of the packaged product may increase with respect to the article. In recent years, there has been a situation where simplification, weight reduction, and thinning of packaging materials are regarded as important from the viewpoint of saving exhaustible resources and improving transportation efficiency.

  In order to reduce the weight and thickness of packaging materials, studies have been made to reduce the thickness of porous materials such as polystyrene foam. For example, a shock absorbing film using a foam (for example, see Patent Document 1), and a film obtained by adding a filler and a thermal expansion microcapsule to a polyolefin resin or polystyrene resin (for example, see Patent Document 2 and Patent Document 3). ) Has been proposed.

  By the way, since the shape of the article to be packed is various, when an uneven article is covered with a film, a gap may be generated between the film and the article. For this reason, when the gap between the film and the article is not filled with a cushioning material or the like, the article may not be sufficiently protected.

  When the shape of the article to be packed is uneven, a heat-shrinkable film (heat-shrinkable label) may be used to reduce the gap between the article and the packing material. As a material for a general heat-shrinkable label, a resin composition such as polyvinyl chloride (PVC), polystyrene, and aromatic polyester is used. As such a heat-shrinkable label, a label having a foamed ink layer on a label substrate (for example, see Patent Document 4) and a label in which a void is provided in a film by filling an inorganic filler into a resin are also proposed. (For example, refer to Patent Document 5).

JP, 2006-030394, A JP-A-10-168207 JP 2014-087948 A JP 2014-219666 A JP 2009-230120 A

  However, the conventional general heat-shrinkable film does not have a porous layer, and does not have sufficient impact properties required when packing an article. In addition, the labels described in Patent Document 4 and Patent Document 5 are provided with a foamed ink layer or a cavity in the film for suppressing label cracking or imparting light shielding properties to the article, and can sufficiently protect the article from impact. It is not a thing. Moreover, since these conventional heat-shrinkable films have a high tearing strength when they are opened after coating the article, they may not be easy to open.

  The present invention has been made in view of such circumstances, can reduce the gap between the heat-shrinkable coated article, and has excellent heat-shrinkability that is excellent in easy-openability when the coated article is opened. An object is to provide a laminated porous film and a coated article.

  As a result of intensive studies, the present inventors have succeeded in obtaining a heat-shrinkable laminated porous film that can solve the above-mentioned problems of the prior art, and have completed the present invention. That is, the present invention is as follows.

  The heat-shrinkable laminated porous film according to the present invention is a pair of front and back layers whose main component is at least one selected from the group consisting of a copolymer resin (A) of a styrene hydrocarbon and a conjugated diene hydrocarbon. And a porous layer mainly composed of a resin composition containing a polyolefin resin (B) and a filler (C), which is provided between the pair of front and back layers, and is stretched in at least one direction. It is characterized by that.

  According to the heat-shrinkable laminated porous film of the present invention, a polyolefin resin and a filler are filled between a pair of front and back layers mainly composed of at least one copolymer resin of a styrene hydrocarbon and a conjugated diene hydrocarbon. Since a porous layer mainly composed of a resin composition containing an agent is provided and stretched, sufficient shrinkage characteristics are imparted to the front and back layers, and pores necessary for easily opening and buffering the porous layer Is formed and becomes porous. As a result, the heat-shrinkable laminated porous film can reduce the gap between the heat-shrinkable article and the article to be coated, and is excellent in easy-openability when opening the article covered by heat shrinkage. . The heat-shrinkable laminated porous film can be provided with a good shrinkage finish when applied to a wide variety of articles in recent years to reduce the use of depleting resources and improve transportation efficiency. It is suitable for shrink packaging, shrink-bound packaging, shrink labels, etc. that are excellent in easy-openability when the coated article is opened after coating a heat shrinkable film on a wide variety of articles. Can do.

  In the heat-shrinkable laminated porous film, the content of the filler (C) in the porous layer is preferably 40% by mass or more and 70% by mass or less.

  The heat-shrinkable laminated porous film preferably includes an adhesive layer that is provided between the front and back layers and the porous layer and contains an adhesive resin as a main component.

  In the heat-shrinkable laminated porous film, it is preferable that the polyolefin resin (B) in the resin composition contains linear low-density polyethylene.

  In the heat-shrinkable laminated porous film, the porosity is preferably 30% or more and 70% or less.

  In the heat-shrinkable laminated porous film, it is preferable that the heat shrinkage rate in the main shrinkage direction in which the shrinkage becomes maximum when immersed in warm water at 100 ° C. for 10 seconds is 50% or more.

  In the heat-shrinkable laminated porous film, the heat shrinkage rate in the orthogonal direction perpendicular to the main shrinkage direction is preferably 20% or more.

  In the heat-shrinkable laminated porous film, the delamination strength in the main shrinkage direction measured at a tensile rate of 100 mm / min is 0.8 N / 15 mm or more, and the adhesive strength is 4.01 N / 10 mm. It is preferable that there is no delamination when the adhesive tape is peeled off after the adhesive tape is applied.

  In the heat-shrinkable laminated porous film, it is preferable that the tear strength of the film based on JIS K7128 is 100 N / mm or less.

  The coated article according to the present invention is characterized in that it is at least partially coated with the heat-shrinkable laminated porous film.

  ADVANTAGE OF THE INVENTION According to this invention, the clearance gap between the coated articles after heat shrink can be reduced, and also the heat-shrinkable laminated porous film and the coated articles excellent in easy-openability when opening the coated articles can be realized.

FIG. 1 is a schematic cross-sectional view showing an example of the heat-shrinkable laminated porous film according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing another example of the heat-shrinkable laminated porous film according to the present embodiment. FIG. 3 is a schematic cross-sectional view showing another example of the heat-shrinkable laminated porous film according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. In the present specification, “to be a main component” means to allow other components to be included within a range that does not hinder the action and effect of the resin contained as the main component. In addition, the term “main component” does not limit the specific content, but it is preferably a component that occupies 50% by mass or more, and occupies 70% by mass or more. More preferably, it is a component occupying 80% by mass or more, and more preferably 100% by mass or less.

<Heat-shrinkable laminated porous film>
FIG. 1 is a schematic cross-sectional view showing an example of the heat-shrinkable laminated porous film according to the present embodiment. As shown in FIG. 1, a heat-shrinkable laminated porous film (heat-shrinkable laminated label) 1 is stretched in at least one direction, and covers various articles to be coated by heat shrinkage. The heat-shrinkable laminated porous film 1 includes a pair of front and back layers 11 mainly composed of at least one copolymer resin (A) of a styrene hydrocarbon-conjugated diene hydrocarbon, and a pair of the front and back layers 11. And a porous layer 12 mainly composed of a resin composition (B) containing a polyolefin resin (B) and a filler (C). The heat-shrinkable laminated porous film 1 has a two-type three-layer configuration in which a front and back layer 111, a porous layer 12, and a front and back layer 112 are laminated in this order. In addition, the front and back layers 111 and 112 may contain the same copolymer resin (A) as a main component, and may contain different copolymer resins (A) as a main component. The front and back layers 111 and the front and back layers 112 may have the same thickness or different thicknesses.

  FIG. 2 is a view showing another example of the heat-shrinkable laminated porous film according to the present embodiment. The heat-shrinkable laminated porous film 2 shown in FIG. 2 includes a surface layer 21, a back layer 22, and an intermediate layer 23 provided between the surface layer 21 and the back layer 22. As for the surface layer 21, the 1st surface layer 211, the front and back layer 112, and the 2nd surface layer 212 are laminated | stacked in this order. As for the back layer 22, the 1st back layer 221, the front and back layer 111, and the 2nd back layer 222 are laminated | stacked in this order. In the intermediate layer 23, the first intermediate layer 231, the porous layer 12, and the second intermediate layer 232 are laminated in this order. That is, the front and back layers 112 are provided as part of the front layer 21, the front and back layers 111 are provided as part of the back layer 22, and the porous layer 12 is provided as part of the intermediate layer 23. As described above, in the present embodiment, the front and back layers 111 and 112 are not necessarily provided on the front surface or the back surface of the heat-shrinkable laminated porous film. And provided on the front side or the back side. The first surface layer 211, the second surface layer 212, the first back layer 221, the second back layer 222, the first intermediate layer 231, and the second intermediate layer 232 can be omitted as appropriate.

  The first front layer 211 and the second front layer 212 may contain, for example, the same copolymer resin (A) as the front and back layers 111, or may contain different copolymer resins (A). Moreover, the 1st surface layer 211 and the 2nd surface layer 212 may have the same thickness, and may have different thickness. The first back layer 221 and the second back layer 222 may contain, for example, the same copolymer resin (A) as the front and back layers 111 or may contain different copolymer resins (A). . The first back layer 221 and the second back layer 222 may have the same thickness or different thicknesses. The 1st intermediate | middle layer 231 and the 2nd intermediate | middle layer 232 may contain the same resin composition as the porous layer 12, for example, and may contain a different resin composition. The first intermediate layer 231 and the second intermediate layer 232 may have the same thickness or different thicknesses.

  FIG. 3 is a view showing another example of the heat-shrinkable laminated porous film according to the present embodiment. The heat-shrinkable laminated porous film 3 shown in FIG. 3 is provided between the front and back layers 111 and the porous layer 12 in addition to the structure of the heat-shrinkable film 1 shown in FIG. And an adhesive layer 132 provided between the front and back layers 112 and the porous layer 12 and mainly composed of an adhesive resin. The heat-shrinkable laminated porous film 3 has a configuration of three types and five layers in which a front and back layer 111, an adhesive layer 131, a porous layer 12, an adhesive layer 132, and a front and back layer 112 are laminated in this order. By providing such an adhesive layer 131, delamination between the front and back layers 111 and the porous layer 12 is less likely to occur. Further, by providing the adhesive layer 132, delamination between the front and back layers 112 and the porous layer 12 is less likely to occur. The adhesive layers 131 and 132 can be omitted as appropriate. Moreover, in the heat-shrinkable laminated porous films 1 to 3 described above, other layers may be further laminated as necessary to impart various functions. The adhesive layers 131 and 132 may include the same adhesive resin as a main component, or may include different adhesive resins as a main component. Further, the adhesive layers 131 and 132 may have the same thickness or different thicknesses.

(Thickness of heat-shrinkable laminated porous film)
There is no restriction | limiting in particular about the whole thickness of a heat-shrinkable laminated porous film. The total thickness of the heat-shrinkable laminated porous film is preferably 300 μm or less, more preferably 250 μm or less, and still more preferably 200 μm or less, from the viewpoints of shrinkage characteristics and easy tearability. Further, the total thickness of the heat-shrinkable laminated porous film is preferably 50 μm or more from the viewpoints of handling properties and impact resistance of the heat-shrinkable laminated porous film.

  The lamination ratio of each layer of the heat-shrinkable laminated porous film is not particularly limited. The lamination ratio of each layer of the heat shrinking laminated film is the thickness of the porous layer relative to the total thickness of the heat shrinking laminated porous film from the viewpoint of shrinkage characteristics, porosity, rupture resistance, impact resistance and easy tearability. The ratio is preferably 50% or more, more preferably 60% or more, more preferably 90% or less, and even more preferably 85% or less. Moreover, the lamination ratio of each layer of the heat shrinking laminated film is such that the thickness of the front and back layers with respect to the total thickness of the heat shrinking laminated porous film is from the viewpoint of shrinkage properties, porosity, rupture resistance, impact resistance and easy tearability. The thickness ratio is preferably 10% or more, more preferably 15% or more, 50% or less, and more preferably 40% or less.

When the heat-shrinkable laminated porous film includes an adhesive layer, the thickness of the adhesive layer is preferably 0.5 μm or more from the viewpoint of efficiently preventing delamination between the front and back layers and the porous layer, More preferably, it is 1 μm or more, more preferably 6 μm or less, and even more preferably 5 μm or less.

(Porosity)
The porosity is a numerical value indicating the ratio of the space portion in the heat-shrinkable laminated porous film. The porosity is determined by measuring the substantial amount W1 of the heat-shrinkable laminated porous film, calculating the mass W0 when the porosity is 0% from the density and thickness of the resin composition, and calculating the following formula (1 ).
Porosity = {(W0−W1) / W0} × 100 (%) (1)

  The pores in the heat-shrinkable laminated porous film are formed by the polyolefin resin and filler contained in the porous layer. The porosity in the heat-shrinkable laminated porous film is preferably 30% or more, more preferably 32.5% or more, and 35% or more from the viewpoint of impact resistance and easy opening of the heat-shrinkable laminated porous film. Is more preferably 70% or less, more preferably 67.5% or less, and even more preferably 65% or more.

(Shrinkage factor)
The heat-shrinkable laminated porous film according to the present embodiment has a beautiful shrinkage because the heat shrinkage rate of the heat-shrinkable laminated porous film satisfies a specific range even when articles of various shapes are covered. Finishability can be realized.

  The heat-shrinkable laminated porous film is 10 seconds in 100 ° C. warm water from the viewpoint of adhesion to irregular shaped articles having a large difference between a wide part and a thin part having various shapes, and suppressing deformation of the article when shrunk. The heat shrinkage rate in the main shrinkage direction in which the shrinkage amount of the heat-shrinkable laminated porous film is maximum when immersed is preferably 50% or more, more preferably 52% or more, and 54% or more. The upper limit of the heat shrinkage rate in the main shrinkage direction is not particularly limited, and is preferably 80% or less. In addition, the heat-shrinkable laminated porous film can be used in 100 ° C. warm water from the viewpoint of adhesion to deformed articles having a large difference between a wide part and a thin part having various shapes, and suppressing deformation of the article when shrunk. When immersed for 10 seconds, the thermal shrinkage rate in the orthogonal direction perpendicular to the main shrinkage direction is preferably 20% or more, preferably 22% or more, more preferably 24% or more, and thermal shrinkage in the orthogonal direction. The upper limit of the rate is not particularly limited, and is preferably 50% or less from the viewpoint of handling properties due to a change in the dimensions of the label. The heat shrinkage rate of the heat-shrinkable laminated porous film can be adjusted within the above range by adjusting the stretching temperature and the stretching ratio.

(Tear strength)
The tear strength of the heat-shrinkable laminated porous film was measured under the conditions of preparing a test piece according to JIS-K7128, holding both ends of the test piece with a universal testing machine, and at an ambient temperature of 23 ° C. and a tensile speed of 200 mm / min. Is done. The tear strength of the heat-shrinkable laminated porous film is such that it is easy to tear when the heat-shrinkable laminated porous film is opened after the article is coated, and it is difficult to cause problems such as breaking during film molding. In view of the above, the tear strength in the main shrinkage direction and the orthogonal direction (tear strength = tensile fracture strength / thickness) is preferably 10 N / mm or more, more preferably 20 N / mm or more, and more preferably 30 N / mm It is more preferable that it is mm or more, and it is preferable that it is 150 N / mm or less.

(Tensile elongation at break)
The breaking elongation of the heat-shrinkable laminated porous film is measured under the conditions of an atmospheric temperature of 23 ° C. and a tensile speed of 100 mm / min. The heat-shrinkable laminated porous film has a tensile elongation at break in the orthogonal direction of 100% or more from the viewpoint that the heat-shrinkable laminated porous film is less likely to break during printing and bag making processes. Is preferably 120% or more, more preferably 150% or more, and preferably 800% or less. The tensile elongation at break of the heat-shrinkable laminated porous film can be adjusted by adjusting the blending of each layer, adjusting the extrusion conditions in the film forming process, adjusting the stretching conditions, adjusting the heat shrinkage ratio, adjusting the lamination ratio, etc. It can be set as the said range.

(Delamination strength)
The delamination strength of the heat-shrinkable laminated porous film is not particularly limited. The delamination strength of the heat-shrinkable laminated porous film is preferably 0.8 N / 15 mm width or more from the viewpoint of efficiently preventing delamination between the seal portion and the film layer during use and heat shrinkage.

(Delamination property)
In the heat-shrinkable laminated porous film, test pieces having an orthogonal direction of 300 mm and a main shrinkage direction of 225 mm were prepared, and cello tape (registered trademark) (model number: “LP-18”, manufactured by Nichiban Co., Ltd., adhesive strength: 4 as an adhesive tape. .01N / 10mm, tensile strength 42.1N / 10mm, width 18mm), and then the delamination state when the cello tape (registered trademark) is peeled off can be confirmed. If there is no delamination, delamination can be efficiently prevented when the tape is attached to the end of the film and peeled off and when the film is opened.

<Front and back layers>
(Copolymer resin (A))
Examples of the copolymer resin (A) of styrene hydrocarbon and conjugated diene hydrocarbon in the front and back layers include a random copolymer and a block copolymer of styrene hydrocarbon and conjugated diene hydrocarbon. Can be mentioned. Among these, as the copolymer resin (A), a block copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon is preferable. The block copolymer is a pure block in which the resin for each block is a single structural unit, a random block in which copolymer components are mixed to form a block, and the copolymer component concentration is tapered. Tapered blocks are included. Among these, as a block copolymer, it is preferable that a block part contains at least 1 sort (s) of a random block and a tapered block from a viewpoint of satisfying the viscoelastic property for providing heat shrinkability.

  Examples of the styrene hydrocarbon in the block copolymer of styrene hydrocarbon and conjugated diene hydrocarbon include styrene, o-methyl styrene, p-methyl styrene, α-methyl styrene, and the like. The homopolymer of these may be a homopolymer, these copolymers may be included, and the copolymerizable monomer other than a styrene hydrocarbon may be included in a block.

  Examples of the conjugated diene hydrocarbon include butadiene, isoprene, 1,3-pentadiene, and the like. The conjugated diene hydrocarbon block portion may be a homopolymer of these or a copolymer thereof, and contains a copolymerizable monomer other than the conjugated diene hydrocarbon in the block. Also good.

  The copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon is preferably 50% by mass or more, more preferably 60% by mass or more, and more preferably 70% by mass or more based on the mass of the entire front and back layers. More preferably. When the content of the copolymer with respect to the total mass is 50% by mass or more, the shrinkage finish, which is the effect of the copolymer of the styrene hydrocarbon and the conjugated diene hydrocarbon, can be sufficiently exhibited.

  As a block copolymer of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon, a styrene-butadiene-styrene block copolymer (hereinafter referred to as “a styrene-based hydrocarbon is styrene and a conjugated diene-based hydrocarbon is butadiene” SBS ") is preferred. SBS preferably has a styrene / butadiene mass ratio of “95% to 60% by mass” / “5% to 40% by mass”, “90% to 60% by mass” / “10% by mass. % Or more and 40% by mass or less "is more preferable. SBS melt flow rate (MFR) measurement (measuring conditions: temperature 200 ° C., load 49 N) is preferably 2 g / 10 min or more, more preferably 3 g / 10 min or more, and preferably 15 g / 10 min or less. / 10 minutes or less is more preferable.

  Examples of the styrene-butadiene-styrene block copolymer include Asaflex series (manufactured by Asahi Kasei Chemicals Corporation), Clearen series (manufactured by Denki Kagaku Kogyo Co., Ltd.), K resin (manufactured by Chevron Phillips Co., Ltd.), and Styrolux (BASF Corporation). And Finacria (manufactured by Atofina).

  As another block copolymer, a styrene-isoprene-butadiene-styrene block copolymer (hereinafter also referred to as “SIBS”) is preferable. In SIBS, the mass ratio of styrene / isoprene / butadiene is preferably “60% to 90% by mass” / “10% to 40% by mass” / “5% to 30% by mass”. More preferably, they are “60% by mass or more and 80% by mass or less” / “10% by mass or more and 25% by mass or less” / “5% by mass or more and 20% by mass or less”. Further, the measured value of melt flow rate (MFR) of SIBS (measurement conditions: temperature 200 ° C., load 49 N) is preferably 2 g / 10 min or more, more preferably 3 g / 10 min or more, and preferably 15 g / 10 min or less. 10 g / 10 min or less is more preferable. If the butadiene content and the isoprene content are within the above ranges, the crosslinking reaction of butadiene when heated inside the extruder or the like can be suppressed, the generation of gel-like materials can be suppressed, and also from the viewpoint of the raw material unit price. . As the styrene-isoprene-butadiene-styrene block copolymer, for example, a commercially available product such as Asaflex I series (manufactured by Asahi Kasei Chemicals) may be used.

  The block copolymer of styrene hydrocarbon and conjugated diene hydrocarbon may be a mixture of two or more. That is, even if the block copolymer of individual styrene hydrocarbons and conjugated diene hydrocarbons alone does not satisfy the predetermined viscoelastic properties of the heat shrinkable laminated porous film shown below, the heat shrinkable laminate after mixing A porous film satisfying a predetermined viscoelastic property can be mixed and used.

The storage elastic modulus (E ′ (0)) at 0 ° C. of the styrene hydrocarbon-conjugated diene hydrocarbon copolymer is preferably 5.0 × 10 ⁸ Pa or more, and 7.0 × 10 ⁸ Pa or more. More preferred is 1.0 × 10 ⁹ Pa or less. Styrene series hydrocarbon - As the conjugated diene storage modulus at 50 ° C. of the hydrocarbon copolymer (E '(50)), preferably not less than ^{1.5 × 10 8 Pa, 1.5 ×} 10 8 Pa or more More preferably, it is preferably 2.0 × 10 ⁹ Pa or less. In order to adjust the storage elastic modulus (E ′ (0) and (50)) at 0 ° C. and 50 ° C. of the styrene hydrocarbon-conjugated diene hydrocarbon copolymer to the above range, for example, styrene hydrocarbon The peak of loss modulus (E ″) of the conjugated diene hydrocarbon copolymer may be present in the range of −80 ° C. to 0 ° C., preferably −80 ° C. to −20 ° C., and the butadiene block The difference in molecular weight between the styrene block and the styrene block may be adjusted, and the storage elastic modulus (E ′ (90)) at 90 ° C. of the styrene hydrocarbon-conjugated diene hydrocarbon copolymer is 1.0 ×. 10 ⁷ Pa or more is preferable, 5.0 × 10 ⁷ Pa or more is more preferable, and 2.0 × 10 ⁸ Pa or less is preferable Storage elasticity of styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer at 90 ° C. Rate 1 To a 0 × 10 7 ^Pa or more, can be adjusted by the styrene block such as SBS in a state close to a pure block Thus, styrene series hydrocarbon -. Butadiene portion of the conjugated diene hydrocarbon copolymer The storage elastic modulus (E ′) at 0 ° C., 50 ° C., and 90 ° C. can be adjusted to a predetermined range by making the block structure of the block a random block and making the block structure of the styrene part close to a pure block. it can.

(Other additives)
In order to improve and adjust various physical properties of the moldability, productivity and heat-shrinkable laminated porous film, the front and back layers are within the range where the effects of the present invention are achieved, and inorganic particles such as silica, talc, and kaolin, Additives such as pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, cross-linking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, etc. It may be added.

<Porous layer>
(Polyolefin resin (B))
The polyolefin resin (B) is a polymer containing an olefin hydrocarbon such as propylene and ethylene as a monomer component. The polyolefin-based resin (B) may be an olefin hydrocarbon homopolymer or a copolymer. In the case of a copolymer, the copolymerization ratio of the olefin hydrocarbon is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.

  Examples of the polyolefin resin include polypropylene resin, polyethylene resin, and ethylene-propylene copolymer. Among these, as polyolefin resin, a polypropylene resin and a polyethylene resin are preferable. The polyethylene-based resin is a polymer containing polyethylene as a monomer component, and may be a homopolymer or a copolymer. Examples of the polyethylene resin include low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and a copolymer mainly composed of ethylene. The copolymer having ethylene as a main component may be a random copolymer or a block copolymer in the case of a copolymer. Moreover, when it is a copolymer, there is no limitation in a copolymerization component, For example, propylene, butene, hexene, etc. are mentioned. When the polyethylene resin is a copolymer, the copolymerization ratio of ethylene is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. Among these, as the polyethylene-based resin, linear low density polyethylene is preferable from the viewpoints of heat shrinkability and easy opening of the heat shrinkable laminated porous film.

  There is no particular limitation on the catalyst used for polymerizing the polyolefin resin, and a Ziegler-Natta catalyst, a metallocene catalyst, or the like can be used. There is no particular limitation on the stereoregularity, and isotactic and syndiotactic can be used. The polyolefin resin used may have any crystallinity or melting point, and blends two types of polyolefin resins having different properties within a specific range depending on the properties and applications of the resulting porous film. The polyolefin resin composition may be used.

  MFR (JIS K6922, temperature 190 ° C., load 2.16 N) of polyolefin resin can adjust the melt viscosity with other layers such as a sheet appearance defect due to the difference in viscosity during co-extrusion. Therefore, it is preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, more preferably 15 g / 10 min or less, and preferably 10 g / 10 min or less. More preferred.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyolefin resin is preferably 1.0 or more and 10.0 or less, and more preferably 2.0 or more and 6.0 or less. preferable. In the present embodiment, Mw / Mn is determined from Mw and Mn measured by gel permeation chromatography (GPC).

  The melting point of the polyolefin-based resin is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and further preferably 120 ° C. or higher, from the viewpoint of a good balance between the mechanical strength and heat resistance of the film and no reduction in stretchability. It is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, and further preferably 130 ° C. or lower. In the present embodiment, the melting point is measured using a differential scanning calorimeter (DSC) at a rate of temperature increase of 10 ° C./min in accordance with JIS K7121.

(filler)
As the filler, inorganic fillers such as inorganic particles, organic fillers such as organic particles, and other generally known fillers can be used. Examples of the inorganic filler include barium sulfate, calcium carbonate, calcium sulfate, barium carbonate, magnesium hydroxide, aluminum hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica, and talc. Of these, barium sulfate is preferred. Porous films manufactured using particles of a basic compound having a pH of more than 9 in an aqueous suspension such as calcium carbonate are limited in use in applications that often come into contact with the human body to irritate the skin. Therefore, it is preferable to use barium sulfate, which is a neutral compound having a pH of about PH6 to PH9. These fillers may be used alone or in combination of two or more.

  Examples of the organic filler include particles obtained by crosslinking a polymer compound using a crosslinking agent, such as crosslinked particles of a polymethoxysilane compound, crosslinked particles of a polystyrene compound, crosslinked particles of an acrylic compound, polyurethane Cross-linked particles of a polyester compound, cross-linked particles of a polyester compound, cross-linked particles of a fluorine-based compound, and a mixture thereof.

  In heat-shrinkable laminated porous film, polyolefin resin and filler are blended and melt-kneaded, then stretched to peel and open the interface between polyolefin resin and filler to form pores be able to. Therefore, uniform pores can be formed when the dispersibility of the filler with respect to the polyolefin resin is good. The filler may be either inorganic or organic as long as it is suitable for forming pores. When using an organic filler as the filler, it is preferable to have a polyolefin resin and a sea-island structure and to adjust the particle size of the organic filler in the range of 0.1 μm to 10 μm. In addition, when an organic filler is used, morphological control is required, and therefore an inorganic filler is preferable from the viewpoint of facilitating porosity.

  The average particle diameter of the filler is not particularly limited. The average particle diameter of the filler is 0.1 μm or more from the viewpoint of improving the dispersibility of the filler and suppressing the generation of foreign matter and pinholes produced by the aggregation of particles in the resulting porous film. 10 μm or less is preferable. Further, if the average particle size is 10 μm or less, the dispersibility of the particles is improved, and the filler can be prevented from agglomerating, and uniform voids are formed to improve stretchability and prevent the occurrence of pinholes. Can do. Further, when the average particle size is 0.1 μm or more, the dispersibility of the particles becomes good, and when the vacancies are formed, the starting interface becomes large, so that sufficient vacancies can be obtained. In order to suppress deterioration of mechanical properties such as tensile elongation, it is necessary to form uniform pores, and the shape of the filler is not particularly limited, but flat particles are used rather than rice granular particles. Is preferred. In the present embodiment, the average particle diameter is observed with a scanning electron microscope (HITACHIS-4700), the average value of the long and short diameters of the particles is defined as the particle diameter, and the number of sampling particles is defined as 100. The average value when.

  The blending ratio of the filler in the porous layer is 40 from the viewpoint that sufficient air permeability is obtained and from the viewpoint of suppressing the dispersion failure by reducing the aggregation of the filler that occurs when the polyolefin resin and the filler are mixed. The mass is preferably from 70% by mass to 70% by mass, more preferably from 42.5% by mass to 67.5% by mass, and still more preferably from 45% by mass to 65% by mass.

(Other additives)
In addition to the above components, the porous layer contains known additives such as antioxidants, heat stabilizers, antistatic agents, slip agents, antiblocking agents, particle dispersants, polyterpene resins, petroleum resins and fillers. You may make it contain in the grade which does not reduce a manufacturing process and a film characteristic.

<Adhesive resin>
The adhesive resin that is the main component of the adhesive layer is not particularly limited as long as it improves the interlayer adhesion between and the porous layer. As the adhesive resin, an adhesive resin having both a part having an affinity for the copolymer resin (A) as a main component and a part having an affinity for the polyolefin resin (B) of the porous layer Are preferably used.

  Here, “having affinity for the copolymer resin (A)” means having a chain having an affinity for the copolymer resin (A). Examples of such an affinity chain include a resin having a styrenic hydrocarbon group, or a chain having a linear or branched saturated hydrocarbon moiety as a main chain, a block chain, a graft chain, or the like.

  Further, the “part having affinity with the polyolefin resin (B)” means having a chain having affinity with the polyolefin resin (B). Examples of such an affinity chain include those having a straight chain or branched saturated hydrocarbon moiety as a main chain, a block chain, a graft chain, and the like.

  The adhesive resin is preferably a soft polyolefin resin, a copolymer of styrene hydrocarbon and conjugated diene hydrocarbon, and a hydrogenated resin thereof. Examples of the soft polyolefin resin include soft linear low density polyethylene, low crystallinity polypropylene resin, and ethylene-vinyl acetate copolymer. As the copolymer of styrene hydrocarbon and conjugated diene hydrocarbon, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-ethylene-butadiene copolymer, styrene-ethylene-propylene copolymer, Examples include styrene-ethylene-butylene copolymers.

  As a commercial product of a resin having a functional group having a high affinity with the above-described copolymer resin (A) and a functional group having a high affinity with the polyolefin resin (B), conjugated with a styrene hydrocarbon Copolymers with diene hydrocarbons and their hydrogenated resins are “Dynalon (registered trademark)” (manufactured by JSR), “Hiblur (registered trademark)” (manufactured by Kuraray), and “Tuftec (registered trademark) H”. (Manufactured by Asahi Kasei Chemicals), "Clayton (registered trademark)" (manufactured by Kraton Polymer Japan), "Septon (registered trademark)" (manufactured by Kuraray), "Tufprene (registered trademark)" (manufactured by Asahi Kasei Chemicals), acid As modified polyolefin resins, “Admer (registered trademark)” (manufactured by Mitsui Chemicals), “Modic (registered trademark)” (manufactured by Mitsubishi Chemical), “Modiper (registered trademark)” (manufactured by NOF Corporation), Tylene-vinyl acetate-maleic anhydride copolymer as “Bondaine (registered trademark)” (manufactured by Arkema), ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer, ethylene- "Bond First (registered trademark)" (manufactured by Sumitomo Chemical Co., Ltd.) as an ethyl acrylate-glycidyl methacrylate terpolymer, and "Tuftec (registered trademark) M" (manufactured by Asahi Kasei Chemicals Corporation) as an acid-modified styrene thermoplastic resin ), “Epofriend (registered trademark)” (manufactured by Daicel Corporation), and the like.

(Other additives)
In addition to the above components, the adhesive layer contains known additives such as antioxidants, heat stabilizers, antistatic agents, slip agents, antiblocking agents, particle dispersants, polyterpene resins, petroleum resins and fillers. You may make it contain in the grade which does not reduce a manufacturing process and a film characteristic.

<Method for producing heat-shrinkable laminated porous film>
The heat-shrinkable laminated porous film can be produced by a known laminated film production method. The form of the film may be either flat or tube-like, but from the viewpoint of productivity (a few products can be taken in the width direction of the raw film) and printing on the outer surface, it is flat. Is preferred. As a method for producing a flat film, for example, a resin is melted using a plurality of extruders, co-extruded from a T-die, cooled and solidified with a chilled roll, roll-stretched in the longitudinal direction, and tenter-stretched in the transverse direction. The film is obtained by annealing, cooling, and winding with a winder. Moreover, the method of cutting open the film manufactured by the tubular method and making it flat is also applicable.

  The extrusion temperature of the resin is preferably 200 ° C. or higher and 240 ° C. or lower, and more preferably 210 ° C. or higher and 230 ° C. or lower. When extruding resins, optimizing the extrusion temperature and shear conditions and controlling the dispersion of the material are also effective in bringing the various physical and mechanical properties of the heat-shrinkable laminated porous film to the desired values. It is.

  In applications such as overlapping, which shrink in two directions, the draw ratio in the machine direction (MD), which is the film flow direction, is preferably 1.5 times or more and 10 times or less, and more preferably 2 times or more and 6 times or less. The stretching ratio in the transverse direction (TD) perpendicular to the film flow direction is preferably 2 to 10 times, and more preferably 3 to 6 times. In addition, 1 time points out the case where it is not extending | stretching.

  The stretching temperature is preferably 80 ° C or higher, more preferably 85 ° C or higher, further preferably 90 ° C or higher, more preferably lower than 110 ° C, more preferably lower than 105 ° C, and still more preferably lower than 100 ° C.

  The heat treatment temperature is preferably 55 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 65 ° C. or higher, less than 85 ° C., more preferably lower than 80 ° C., and still more preferably lower than 75 ° C.

  At the time of heat treatment in the production process of the heat-shrinkable laminated porous film, a relaxation process may be included as long as the film characteristics are not deteriorated. The relaxation rate is not particularly limited with respect to the maximum stretched film width, and the upper limit is preferably 10% or less from the viewpoint of suppressing natural shrinkage over time.

  In the heat-shrinkable laminated porous film, at least one layer of the porous layer and the adhesive layer may contain a film regeneration resin that regenerates the heat-shrinkable laminated porous film generated due to trimming loss or the like. The film regeneration resin is preferably blended in the porous layer. You may make the compounding quantity of film reproduction | regeneration resin contain in the grade which does not reduce a manufacturing process and a film characteristic.

(Other processing)
In heat-shrinkable laminated porous films, surface treatment and surface processing such as corona treatment, printing, coating, and vapor deposition, and bag making and perforation processing using various solvents and heat sealing, as necessary. Can be applied.

<Molded products, labels>
The application of the heat-shrinkable laminated porous film is not particularly limited, but the heat-shrinkable laminated porous film is used as a base material and is formed by laminating a printing layer, a vapor deposition layer and other functional layers as necessary. By doing so, it can be used as various molded products such as trays, blister containers, deep-drawn containers, and packing containers.

  Further, the heat-shrinkable laminated porous film can be used as a base material for a heat-shrinkable label for transport articles. In this case, even if the article has a complicated shape such as a centered cylindrical column, a square column with a corner, a pentagonal column, a hexagonal column, etc., it is possible to adhere to the complicated shape, and it is beautiful without wrinkles and avatars. It becomes the attached label. The molded product can be produced by using a normal molding method.

  In addition to the heat-shrinkable label material used for plastic molded products that cause deformation when heated to high temperatures, the heat-shrinkable laminated porous film is a material that is extremely different from the heat-shrinkable film in terms of coefficient of thermal expansion and water absorption, For example, a package using at least one selected from metal, porcelain, glass, paper, polymethacrylate resin, polycarbonate resin, polyester resin such as polyethylene terephthalate, polybutylene terephthalate, and polyamide resin as a constituent material. It can also be suitably used as a heat-shrinkable label material.

  As a material constituting the plastic package, in addition to the above resin, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, acrylonitrile -Butadiene-styrene copolymer (ABS), (meth) acrylic acid-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, A silicone resin etc. can be mentioned. These plastic packages may be a mixture of two or more resins or a laminate.

  As described above, according to the above-described embodiment, a polyolefin resin and a filler between a pair mainly composed of at least one copolymer resin of a styrene hydrocarbon and a conjugated diene hydrocarbon. Is provided with a porous layer mainly composed of a resin composition containing, so that sufficient shrinkage characteristics are imparted and pores necessary for easy-opening and buffering are formed in the porous layer. And become porous. Thereby, the heat-shrinkable laminated porous film according to the above embodiment can reduce the gap between the heat-shrinkable article and the article to be coated, and can be easily opened when the article coated by heat-shrinking is opened. It will be excellent. The heat-shrinkable laminated porous film can be provided with a good shrinkage finish when applied to a wide variety of articles in recent years to reduce the use of depleting resources and improve transportation efficiency. It is suitable for shrink packaging, shrink-bound packaging, shrink labels, etc. that are excellent in easy-openability when the coated article is opened after coating a heat shrinkable film on a wide variety of articles. Can do.

  Hereinafter, the present invention will be described in more detail based on examples carried out in order to clarify the effects of the present invention. In addition, this invention is not limited at all by the following examples and comparative examples.

<Measurement method>
Measurement and evaluation of various physical properties in the examples were performed as follows. In the following examples, the take-up (flow) direction of the heat-shrinkable laminated porous film is referred to as the “longitudinal” direction (or MD), and the direction orthogonal to the “vertical direction” is referred to as the “lateral” direction (or TD). . In the following examples, the “lateral” direction (TD) is the main shrinkage direction of the heat-shrinkable laminated porous film, and the “longitudinal” direction (MD) is the orthogonal direction perpendicular to the main shrinkage direction.

(1) Porosity The porosity is a numerical value indicating the proportion of the space portion in the heat-shrinkable laminated porous film. The porosity is determined by measuring the substantial amount W1 of the heat-shrinkable laminated porous film, calculating the mass W0 when the porosity is 0% from the density and thickness of the resin composition, and calculating from the mass W0 and the substantial amount W1 as follows. It calculated based on Formula (1).
Porosity = {(W0−W1) / W0} × 100 (%) (1)

(2) Heat shrinkage rate The obtained film was cut into a size of 10 mm in length, 200 mm in width, 200 mm in length, and 10 mm in width, and immersed in a hot water bath at 100 ° C. for 10 seconds, respectively in the vertical direction (TD) and the horizontal direction ( The amount of shrinkage in MD) was measured. For the thermal shrinkage, the ratio of shrinkage to the original size before shrinkage was expressed as a% value in the longitudinal direction (TD) and the transverse direction (MD).

(3) Tear strength The test piece in the longitudinal direction (TD) and the transverse direction (MD) was prepared from the obtained heat-shrinkable laminated porous film in accordance with JIS-K7128, and both ends of the test piece were gripped with a universal testing machine. The tensile strength at break was measured under the conditions of an ambient temperature of 23 ° C. and a tensile speed of 200 mm / min. TD per unit thickness and MD tear strength were calculated using the following formula (2), and the average value of 5 times was measured.
Tear strength = Tensile fracture strength / Thickness (N / mm) Formula (2)

(4) Tensile rupture elongation The obtained heat-shrinkable laminated porous film was cut into a size of 120 mm in the machine direction (MD) and 15 mm in the transverse direction (TD). The cut heat-shrinkable laminated porous film is measured in accordance with JIS K7127, the tensile breaking elongation in the machine direction (MD), which is the film take-up direction at an atmospheric temperature of 23 ° C., at a tensile speed of 200 mm / min, and measured 10 times. The average value of was measured.

(5) Interlaminar peel strength The obtained film was cut into a size of 15 mm in the machine direction (MD) and 150 mm in the transverse direction (TD), and a part of one side of the end face in the transverse direction (TD) was peeled off from the porous layer. The peeled layer and the peeled layer were each sandwiched between chucks of a tensile tester, and a 180 degree peel test was performed at a test speed of 100 mm / min in the transverse direction (TD). In the region where the load obtained by the peel test shows a stable value, the average value was evaluated as the delamination strength.

(6) Delamination property The obtained heat-shrinkable laminated porous film was cut into a size of 300 mm in the machine direction (MD) and 225 mm in the transverse direction (TD), and cello tape (registered trademark) (model number: “LP-” 18 ”, manufactured by Nichiban Co., Ltd., adhesive strength: 4.01 N / 10 mm, tensile strength 42.1 N / 10 mm, width 18 mm), and then confirmed the delamination state when the cello tape (registered trademark) was peeled off evaluated. In addition to the above delamination strength evaluation, delamination properties were evaluated according to the following criteria.
○: Peel strength is 0.8 (N / 15 mm width) or more and no delamination by tape peeling ×: Peel strength is less than 0.8 (N / 15 mm width) or delamination by tape peeling

(7) Shrinkage finishing property The obtained film was cut out in a longitudinal direction (MD) of 120 mm and a transverse direction (TD) of 225 mm, folded so as to overlap with TD by 10 mm, and the overlapped portion was heat sealed to form a cylindrical film. . Next, a sample for finishing evaluation was produced by covering the cylindrical film with a 225 ml bottle up to the lower surface of the bottle. The sample for evaluation was passed for 20 seconds under the following temperature conditions without rotating in a 2.5 m long (3-zone configuration) shrinking tunnel of the hot air heating method. Evaluation was made by confirming whether there was no folds or wrinkles due to waist folding of the film shrunk on the bottle, or whether the film was insufficiently shrunk. Evaluation was performed with each sample N = 10. The temperature conditions in the shrinker were set as follows.
Temperature conditions: 1 zone / 85-90 ° C, 2 zones / 105-110 ° C, 3 zones / 145-150 ° C
Nozzle position in tunnel for injecting hot air: 1 zone / lower part of film, 2 zone / whole film, 3 zone / whole film After film coating, evaluation was made according to the following criteria.
○: Shrinkage is sufficient, and wrinkles, avatars, and lattice distortion do not occur.
X: Shrinkage is sufficient, but wrinkles, avatars, and lattice distortion are remarkably generated, or the shrinkage is not sufficient, and the coating on the bottle is insufficient.

The raw materials used in the following examples and comparative examples are as follows.
<Copolymer resin (A) of styrene-based hydrocarbon and conjugated diene-based hydrocarbon>
SBS: Styrene / butadiene copolymer containing styrene / butadiene = 84.0 wt% / 16.0 wt% as a constituent component (hereinafter also referred to as “copolymer resin A1”)
SBS: Styrene / butadiene copolymer containing styrene / butadiene = 77.0 wt% / 23.0 wt% as a constituent component (hereinafter also referred to as “copolymer resin A2”)
SBS: styrene-butadiene copolymer containing styrene / butadiene = 81.5 wt% / 18.5 wt% as a constituent component (hereinafter also referred to as “copolymer resin A3”)
<Polyolefin resin (B)>
・ Linear low density polyethylene: trade name “Novatech SF240”, manufactured by Nippon Polytechnic Co., Ltd., MFR = 2.0 g / 10 min, melting point = 126 ° C. (hereinafter also referred to as “polyolefin resin”)
<Filler (C)>
Barium sulfate, trade name “Variace B-54”, manufactured by Sakai Chemical Industry Co., Ltd., average particle size 1.1 μm (hereinafter also referred to as “filler”)
<Polyester resin>
Polyester containing 1,4-cyclohexanedimethanol: 32.0 mol%, ethylene glycol: 65.0 mol%, diethylene glycol: 3.0%, terephthalic acid: 100.0 mol% as constituent components (hereinafter referred to as “polyester”) Also referred to as “based resin B1”)
Polyester containing 1,4-cyclohexanedimethanol: 23.0 mol%, ethylene glycol: 65.0 mol%, diethylene glycol: 12.0%, terephthalic acid: 100.0 mol% as constituent components (hereinafter referred to as “polyester”) Also referred to as “based resin B2”)
-Polyester containing 1,4-butanediol: 100.0 mol%, terephthalic acid: 90.0 mol%, isophthalic acid: 10.0 mol% as constituent components (hereinafter also referred to as "polyester resin B3")
<Adhesive resin>
Functional group-containing hydrogenated styrene-butadiene copolymer (SEBC): Trade name: Dynalon 4600P, manufactured by JSR Co., Ltd. Styrene content = 20%, MFR (230 ° C., 21.2 N) = 5.5 g / 10 minutes (hereinafter, Also called “adhesive resin C1”)
Functional group-containing hydrogenated styrene-butadiene copolymer: Trade name: Dynalon 8903P, manufactured by JSR, Styrene content = 35%, MFR (230 ° C., 21.2 N) = 10 g / 10 min (hereinafter referred to as “adhesive resin C2”) Is also called)
Styrenic thermoplastic elastomer: Trade name: Hybler 7125, manufactured by Kuraray Co., Ltd. Styrene content = 20%, MFR (230 ° C., 2.16 kg) = 4 g / 10 min (hereinafter also referred to as “adhesive resin C3”)
Modified polyolefin-based thermoplastic elastomer: Trade name: Admer SF725, manufactured by Mitsui Chemicals (hereinafter also referred to as “adhesive resin C4”)

Example 1
As the front and back layers, 100 parts by mass of copolymer resin A1 was used. As a porous layer, 40 mass parts polyolefin resin and 60 mass parts filler were mixed and used. As the adhesive layer, 100 parts by mass of adhesive resin B1 was used. In order to produce a laminated film of 3 types and 5 layers of / adhesive layer / porous layer / adhesive layer /, each raw material was mixed, and then the above 3 was performed using 3 single-screw extruders and 3 types and 5 layers multi-manifold die. Co-extrusion was carried out in an equipment capable of laminating co-extrusion of a seed 5 layer laminated film. And the extruder set temperature of the adhesive layer is 210 ° C. or higher and 220 ° C. or lower and the extruder preset temperature of the porous layer is 220 ° C. or higher and 230 ° C. or lower. Layer / = 4/1/14/1/4 was coextruded, taken up with a cast roll at 60 ° C., and cooled and solidified to obtain an unstretched laminated sheet. Next, using the film tenter, the obtained unstretched deposited layer sheet was stretched at the stretching temperature shown in Table 1 below in the flow direction shown in Table 1 below. Next, after extending | stretching by the draw ratio 5 times of the width direction, it heat-processed with the heat processing temperature shown in following Table 1, and obtained the heat-shrinkable laminated porous film. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 2)
A heat-shrinkable laminated porous film was produced and evaluated in the same manner as in Example 1 except that the unstretched laminated sheet was stretched under the conditions shown in Table 1 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 3)
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Example 1 except that 100 parts by mass of the adhesive resin B2 was used instead of the adhesive resin B1. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

Example 4
A heat-shrinkable laminated porous film was produced and evaluated in the same manner as in Example 3 except that the unstretched laminated sheet was stretched under the conditions shown in Table 1 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 5)
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Example 1 except that 100 parts by mass of the adhesive resin B3 was used instead of the adhesive resin B1. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 6)
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Example 5 except that the unstretched laminated sheet was stretched under the conditions shown in Table 1 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 7)
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Example 2 except that 50 parts by mass of polyolefin resin and 50 parts by mass of filler were used as the porous layer. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 8)
An unstretched laminated sheet similar to that in Example 5 was produced. Next, using a film tenter, the obtained unstretched laminated sheet was stretched at the stretching temperature shown in Table 1 below with respect to the stretching ratio in the flow direction shown in Table 1 below, and then stretched to 5 times in the width direction. And stretched. Next, the film was relaxed by about 5% while performing heat treatment at the heat treatment temperature shown in Table 1 below to obtain a heat-shrinkable film. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

Example 9
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Example 8 except that the unstretched laminated sheet was stretched under the conditions shown in Table 1 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 2 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Comparative Example 1)
As front and back layers, 100 parts by mass of polyester-based resin C1 was used instead of copolymer resin A1, and as adhesive layers, 100 parts by mass of adhesive resin B4 was used instead of adhesive resin B1. The extruder set temperature was set to 240 ° C to 250 ° C, the extruder set temperature for the adhesive layer was set to 210 ° C to 220 ° C, and the extruder set temperature for the porous layer was set to 220 ° C to 230 ° C. Except that, an unstretched laminated sheet was obtained in the same manner as in Example 1. Next, the unstretched laminated sheet obtained using the film tenter was stretched at the stretching temperature shown in Table 4 below with respect to the stretching ratio in the flow direction shown in Table 4 below, and then the stretching ratio in the width direction was 5 times. Was stretched. Next, heat treatment was performed at a heat treatment temperature shown in Table 4 below to obtain a heat-shrinkable film. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

(Comparative Example 2)
A heat-shrinkable laminated porous film was produced and evaluated in the same manner as in Comparative Example 1 except that the unstretched laminated sheet was stretched under the conditions shown in Table 4 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

(Comparative Example 3)
A heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Comparative Example 2 except that the unstretched laminated sheet was stretched under the conditions shown in Table 4 below and the thickness was changed. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

(Comparative Example 4)
The unstretched laminated sheet was stretched under the conditions shown in Table 4 below, and a heat-shrinkable laminated porous film was prepared and evaluated in the same manner as in Comparative Example 2 except that the thickness was changed. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

(Comparative Example 5)
As the front and back layers, 85 parts by mass of polyester resin C2 and 15 parts by mass of polyester resin C3 were mixed and used. As the porous layer, 84 parts by mass of a polyester resin C1 and 15 parts by mass of a polyester resin C3 were mixed and used. After mixing each raw material, the extruder set temperature of each layer is 240 ° C., the thickness ratio of each layer is coextruded so as to be / porous layer = 1 = 1/6/1, the draw ratio in the flow direction is 1.1 times, the width A heat-shrinkable laminated porous film was obtained in the same manner as in Example 1 except that the film was stretched under the conditions shown in Table 4 below at a stretching ratio of 5.0 times in the direction. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

(Comparative Example 6)
As the front and back layers, 100 parts by mass of copolymer resin A2 was used. As the porous layer, 100 parts by mass of copolymer resin A3 was used. After mixing the raw materials, a heat-shrinkable laminated porous film was obtained in the same manner as in Comparative Example 5 except that the raw materials were stretched under the conditions shown in Table 4 below. The composition of each raw material used for the production of the heat-shrinkable laminated porous film is shown in Table 5 below, and various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 6 below.

  As can be seen from Tables 1 to 3, since the heat-shrinkable laminated porous film according to Examples 1 to 9 includes the front and back layers and the porous layer according to the above-described embodiment, it is excellent in sufficient porosity. It had heat shrinkability, good fracture resistance and delamination resistance, and easy tearability. On the other hand, the heat-shrinkable laminated porous films according to Comparative Examples 1 to 4 are both resistant to Examples 1 to 9 because the front and back layers do not contain the copolymer resin (A). The delamination property was inferior. Moreover, since the said porous layer does not contain polyolefin resin (B), the heat-shrinkable film which concerns on the comparative example 5 and the comparative example 6 was inferior to porosity and easy tearability.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is limited to the embodiments disclosed herein. The heat-shrinkable laminated porous film, which can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and a molded article using the film And heat shrinkable labels, and articles formed with the molded articles and labels should also be understood as being encompassed by the present invention.

  The present invention has the effect of reducing the gap between the heat-shrinkable coated article and the heat-shrinkable laminated porous film and the coated article excellent in easy-openability when opening the coated article. For example, it can be suitably used for shrink-wrapping, shrink-bound packaging, shrinkage labels, and the like of articles covering various shapes to be coated.

1, 2, 3 Heat-shrinkable laminated porous film 11, 111, 112 Front and back layers 12 Porous layer 21, 211, 212 Front layer 22, 221, 222 Back layer 23, 231, 232 Intermediate layer

Claims (10)

A pair of front and back layers mainly comprising at least one selected from the group consisting of a copolymer resin (A) of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon;
Provided between the pair of front and back layers, and a porous layer mainly composed of a resin composition containing a polyolefin resin (B) and a filler (C),
A heat-shrinkable laminated porous film characterized by being stretched in at least one direction.   The heat-shrinkable laminated porous film according to claim 1, wherein the content of the filler (C) in the porous layer is 40% by mass or more and 70% by mass or less.   The heat-shrinkable laminated porous film according to claim 1 or 2, further comprising an adhesive layer that is provided between the front and back layers and the porous layer and contains an adhesive resin as a main component.   The heat-shrinkable laminated porous film according to any one of claims 1 to 3, wherein the polyolefin resin (B) in the resin composition contains linear low-density polyethylene.   The heat-shrinkable laminated porous film according to any one of claims 1 to 4, wherein the porosity is from 30% to 70%.   The heat shrinkability according to any one of claims 1 to 5, wherein a heat shrinkage rate in a main shrinkage direction in which a shrinkage is maximized when immersed in warm water of 100 ° C for 10 seconds is 50% or more. Laminated porous film.   The heat-shrinkable laminated porous film according to claim 6, wherein a heat shrinkage rate in a direction orthogonal to the main shrinkage direction is 20% or more.   After applying an adhesive tape having a delamination strength of 0.8 N / 15 mm or more in the main shrinkage direction measured under a tensile speed of 100 mm / min and an adhesive strength of 4.01 N / 10 mm, the adhesive The heat-shrinkable laminated porous film according to claim 6 or 7, wherein there is no delamination when the tape is peeled off.   The heat-shrinkable laminated porous film according to any one of claims 1 to 7, wherein the tear strength of the film according to JIS K7128 is 100 N / mm or less. A coated article, at least partially coated with the heat-shrinkable laminated porous film according to any one of claims 1 to 9.

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