JP6870405B2 - Heat-shrinkable laminated porous film and coated article - Google Patents

Description

The present invention relates to a heat-shrinkable laminated porous film and a coated article coated with the film, and the heat-shrinkable laminated porous film and the film are preferably used for applications such as shrinkage packaging, shrinkage binding packaging, and shrinkage label. Concerning covered coated articles.

Currently, goods purchased by mail order, etc. are various according to various packing materials such as corrugated cardboard, molded boxes and cushioning materials in order to prevent destruction and damage of the goods due to impact during transportation and transportation. It is packed. Further, in such various packing materials, various measures have been taken from the viewpoint of easy opening when opening the packed article.

In the various packing materials described above, a gap may be formed between the packed article and the packing material. Therefore, 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 packed article and the packing material are separated from each other. The gap is reduced. However, the reduction of the gap by these may increase the volume of the packaged product with respect to the article. Further, in recent years, from the viewpoint of saving depleting resources and improving transportation efficiency, simplification, weight reduction and thinning of packaging materials have been emphasized.

In order to reduce the weight and thickness of the packaging material, studies are being made to reduce the thickness of porous materials such as Styrofoam. For example, a shock absorbing film using a foam (see, for example, Patent Document 1) and a film obtained by adding a filler and heat-expanding microcapsules to a polyolefin-based resin or polystyrene-based resin (see, for example, Patent Documents 2 and 3). ) Has been proposed.

By the way, since the shape of the article to be packed is various, when the article having unevenness is covered with a film, a gap may be generated between the film and the article. Therefore, if 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 general heat-shrinkable label material, 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 base material (see, for example, Patent Document 4) and a label in which a cavity is provided in a film by filling a resin with an inorganic filler are also proposed. (See, for example, Patent Document 5).

JP-A-2016-030394 Japanese Unexamined Patent Publication No. 10-168207 Japanese Unexamined Patent Publication No. 2014-07948 Japanese Unexamined Patent Publication No. 2014-219666 Japanese Unexamined Patent Publication No. 2009-230120

However, conventional general heat-shrinkable films do not have a porous layer and do not have sufficient impact resistance required for packing articles. Further, the labels described in Patent Document 4 and Patent Document 5 are provided with a cavity of a foamed ink layer or a film for suppressing label cracking or imparting a light-shielding property to an article, and can necessarily sufficiently protect the article from impact. It's not a thing. In addition, these conventional heat-shrinkable films may not be easy to open because they have high tear strength when they are opened after coating the article.

The present invention has been made in view of such circumstances, and can reduce the gap between the coated article and the coated article after heat shrinkage, and has excellent heat shrinkage property when opening the coated article. It is an object of the present invention to provide a laminated porous film and a coated article.

As a result of diligent studies, the present inventors have succeeded in obtaining a heat-shrinkable laminated porous film capable of solving 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 containing 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. And a porous layer provided between the pair of front and back layers and containing a resin composition containing a polyolefin resin (B) and a filler (C) as a main component, and stretched in at least one direction. It is characterized by that.

According to the heat-shrinkable laminated porous film according to the present invention, a polyolefin-based resin and a filling are formed between a pair of front and back layers containing at least one of a copolymer resin of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon as a main component. Since a porous layer containing a resin composition containing an agent as a main component is provided and stretched, sufficient shrinkage characteristics are imparted to the front and back layers, and the pores required for easy opening and cushioning are exhibited in the porous layer. Is formed and becomes porous. As a result, the heat-shrinkable laminated porous film can reduce the gap between the article to be coated by heat shrinkage, and is excellent in easy-opening property when opening the article coated by heat shrinkage. .. The heat-shrinkable laminated porous film can also have good shrinkage finish when applied to a wide variety of articles in recent years for reducing the use of depleting resources and improving transportation efficiency. After coating a heat-shrinkable film on a wide variety of articles to form a coated article, it is suitably used for shrinkage packaging, shrinkage binding packaging, shrinkage label, etc., which are excellent in easy-to-open when opening the coated article. Can be done.

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.

In the heat-shrinkable laminated porous film, it is preferable to provide an adhesive layer provided between the front and back layers and the porous layer and containing an adhesive resin as a main component.

In the heat-shrinkable laminated porous film, it is preferable that the polyolefin-based 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, which maximizes the amount of shrinkage when immersed in warm water at 100 ° C. for 10 seconds, is 50% or more.

In the heat-shrinkable laminated porous film, the heat-shrinkability in the direction orthogonal 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 under the condition of a tensile speed of 100 mm / min is 0.8 N / 15 mm or more, and the adhesive strength is 4.01 N / 10 mm. After the adhesive tape is attached, it is preferable that there is no delamination when the adhesive tape is peeled off.

In the heat-shrinkable laminated porous film, the tear strength of the film conforming to JIS K7128 is preferably 100 N / mm or less.

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

According to the present invention, it is possible to reduce the gap between the coated article and the coated article after heat shrinkage, and to realize a heat-shrinkable laminated porous film and a coated article having excellent easy-opening property when opening the coated article.

FIG. 1 is a schematic cross-sectional view showing an example of a 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 addition, in this specification, "as a main component" means that it is allowed to contain other components as long as it does not interfere with the action and effect of the resin contained as the main component. The term "main component" does not limit the specific content, but preferably is a component having a content of 50% by mass or more with respect to the entire constituent components, and occupies 70% by mass or more. It is more preferably a component, further preferably a component occupying 80% by mass or more, and a component occupying a range of 100% by mass or less.

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

FIG. 2 is a diagram 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. In the surface layer 21, the first surface layer 211, the front and back layers 112, and the second surface layer 212 are laminated in this order. In the back layer 22, the first back layer 221 and the front and back layers 111 and the second back layer 222 are laminated in this order. In the intermediate layer 23, the first intermediate layer 231 and 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 a part of the surface layer 21, the front and back layers 111 are provided as a part of the back layer 22, and the porous layer 12 is provided as a part of the intermediate layer 23. As described above, in the present embodiment, the front and back layers 111 and 112 do not necessarily have to be provided on the front surface or the back surface of the heat-shrinkable laminated porous film, with respect to the porous layer 12 of the heat-shrinkable laminated porous film 1. It may be provided on the front surface side or the back surface side. The first surface layer 211, the second surface layer 212, the first back layer 221 and the second back layer 222, the first intermediate layer 231 and the second intermediate layer 232 can be omitted as appropriate.

The first surface layer 211 and the second surface 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). Further, the first surface layer 211 and the second surface layer 212 may have the same thickness or may have different thicknesses. 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). .. Further, the first back layer 221 and the second back layer 222 may have the same thickness or may have different thicknesses. The first intermediate layer 231 and the second intermediate layer 232 may contain, for example, the same resin composition as the porous layer 12, or may contain different resin compositions. Further, the first intermediate layer 231 and the second intermediate layer 232 may have the same thickness or may have different thicknesses.

FIG. 3 is a diagram showing another example of the heat-shrinkable laminated porous film according to the present embodiment. The thermosetting 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 configuration of the thermosetting film 1 shown in FIG. 1, and contains an adhesive resin as a main component. An adhesive layer 132 provided between the front and back layers 112 and the porous layer 12 and having an adhesive resin as a main component is provided. The heat-shrinkable laminated porous film 3 has a structure of 3 types and 5 layers in which the front and back layers 111, the adhesive layer 131, the porous layer 12, the adhesive layer 132 and the front and back layers 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. Further, in the heat-shrinkable laminated porous films 1 to 3 described above, other layers may be further laminated in order to impart various functions, if necessary. The adhesive layers 131 and 132 may contain the same adhesive resin as a main component, or may contain different adhesive resins as a main component. Further, the adhesive layers 131 and 132 may have the same thickness or may have different thicknesses.

(Thickness of heat-shrinkable laminated porous film)
There is no particular limitation on the overall thickness of the heat-shrinkable laminated porous film. The overall thickness of the heat-shrinkable laminated porous film is preferably 300 μm or less, more preferably 250 μm or less, still more preferably 200 μm or less, from the viewpoint of shrinkage characteristics and easy tearability. The overall thickness of the heat-shrinkable laminated porous film is preferably 50 μm or more from the viewpoint of handleability 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-shrinkable laminated porous film is the thickness of the porous layer with respect to the total thickness of the heat-shrinkable laminated porous film from the viewpoint of shrinkage characteristics, porosity, fracture resistance, impact resistance and easy tearability. The ratio is preferably 50% or more, more preferably 60% or more, preferably 90% or less, and more preferably 85% or less. The lamination ratio of each layer of the heat-shrinkable laminated porous film is the thickness of the front and back layers with respect to the total thickness of the heat-shrinkable laminated porous film from the viewpoints of shrinkage characteristics, porosity, fracture resistance, impact resistance and easy tearability. The thickness ratio is preferably 10% or more, more preferably 15% or more, more preferably 50% or less, and even 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. It is more preferably 1 μm or more, more preferably 6 μm or less, and even more preferably 5 μm or less.

(Vacancy rate)
The porosity is a numerical value indicating the ratio of the space portion in the heat-shrinkable laminated porous film. For the porosity, the actual amount W1 of the heat-shrinkable laminated porous film was measured, the mass W0 when the porosity was 0% was calculated from the density and thickness of the resin composition, and the following formula (1) was obtained from the calculated value. ) Is calculated.
Pore ratio = {(W0-W1) / W0} x 100 (%) ... Equation (1)

The pores in the heat-shrinkable laminated porous film are formed by the polyolefin resin and the 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 property of the heat-shrinkable laminated porous film. Is more preferable, 70% or less is preferable, 67.5% or less is more preferable, and 65% or more is further preferable.

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

The heat-shrinkable laminated porous film is used in warm water at 100 ° C. for 10 seconds from the viewpoint of adhesion to irregularly shaped articles having a large difference between thick and thin parts of various shapes and suppressing deformation of the articles when contracted. The heat shrinkage in the main shrinkage direction, which maximizes the shrinkage of the heat-shrinkable laminated porous film when immersed, is preferably 50% or more, more preferably 52% or more, and more preferably 54% or more. Is particularly preferable, and the upper limit of the heat shrinkage rate in the main shrinkage direction is not particularly limited, and is preferably 80% or less. Further, the heat-shrinkable laminated porous film is used in warm water at 100 ° C. from the viewpoint of adhesion to a deformed article having a large difference between a thick part and a thin part having various shapes and suppressing deformation of the article when it shrinks. The heat shrinkage in the orthogonal direction orthogonal to the main shrinkage direction when immersed for 10 seconds is preferably 20% or more, preferably 22% or more, more preferably 24% or more, and heat 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 handleability due to a change in label size. 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 is measured under the conditions of preparing a test piece in accordance with JIS-K7128, grasping both ends of the test piece with a universal testing machine, an atmospheric temperature of 23 ° C., and a tensile speed of 200 mm / min. Will be 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 coating the article, and problems such as breakage during film molding are unlikely to occur. From this point of view, the tear strength (tear strength = tensile fracture strength / thickness) in the main contraction direction and the orthogonal direction is preferably 10 N / mm or more, more preferably 20 N / mm or more, and more preferably 30 N / mm. It is more preferably mm or more, and more preferably 150 N / mm or less.

(Tension breaking elongation)
The elongation at break 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 defects such as breakage of the heat-shrinkable laminated porous film are less likely to occur during processes such as printing and bag making. Is more preferable, 120% or more is more preferable, 150% or more is further preferable, and 800% or less is preferable. The tensile elongation at break of the heat-shrinkable laminated porous film can be adjusted by appropriately adjusting the composition of each layer, the extrusion conditions in the film forming process, the stretching conditions, the heat shrinkage rate, the stacking ratio, and the like. It can be in the above 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 or more from the viewpoint of efficiently preventing delamination between the seal portion and the film layers during use and heat shrinkage.

(Delaminability)
For the heat-shrinkable laminated porous film, a test piece having a orthogonal direction of 300 mm and a main shrinkage direction of 225 mm was prepared, and cellophane tape (registered trademark) as an adhesive tape (model number: "LP-18", manufactured by Nichiban Co., Ltd., adhesive strength: 4) was prepared. After attaching 0.01N / 10mm, tensile strength 42.1N / 10mm, width 18mm), the delamination state when the cellophane 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 the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon in the front and back layers include a random copolymer and a block copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon. Can be mentioned. Among these, as the copolymer resin (A), a block copolymer of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon is preferable. As block copolymers, pure blocks in which the resin for each block is a single constituent unit, random blocks in which copolymer components are mixed to form blocks, and copolymer component concentrations are tapered. Includes tapered blocks and the like. Among these, as the block copolymer, it is preferable that the block portion contains at least one of a random block and a tapered block from the viewpoint of satisfying the viscoelastic property for imparting heat shrinkage.

Examples of the styrene-based hydrocarbon in the block copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon include styrene, o-methylstyrene, p-methylstyrene and α-methylstyrene. The styrene-based hydrocarbon block portion may be a homopolymer thereof or a copolymer thereof, and may contain a copolymerizable monomer other than the styrene-based hydrocarbon in the block.

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

The copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more with respect to the total mass of the front and back layers. Is more preferable. 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-based hydrocarbon and the conjugated diene-based 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 in which the styrene-based hydrocarbon is styrene and the conjugated diene-based hydrocarbon is butadiene (hereinafter, "" Also referred to as "SBS") is preferred. The mass ratio of styrene / butadiene of SBS is preferably "95% by mass or more and 60% by mass or less" / "5% by mass or more and 40% by mass or less", and "90% by mass or more and 60% by mass or less" / "10% by mass". % Or more and 40% by mass or less ”is more preferable. The melt flow rate (MFR) measured value of SBS (measurement conditions: temperature 200 ° C., load 49N) is preferably 2 g / 10 minutes or more, more preferably 3 g / 10 minutes or more, and preferably 15 g / 10 minutes or less, 10 g. / 10 minutes or less is more preferable.

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

As the other 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% by mass or more and 90% by mass or less" / "10% by mass or more and 40% by mass or less" / "5% by mass or more and 30% by mass or less". , "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". The measured value of SIBS melt flow rate (MFR) (measurement conditions: temperature 200 ° C., load 49N) is preferably 2 g / 10 minutes or more, more preferably 3 g / 10 minutes or more, and preferably 15 g / 10 minutes or less. More preferably, 10 g / 10 minutes or less. When the butadiene content and the isoprene content are within the above ranges, the cross-linking reaction of butadiene when heated inside an extruder can be suppressed, the generation of gel-like substances can be suppressed, and it is also preferable from the viewpoint of the unit price of raw materials. .. As the styrene-isoprene-butadiene-styrene block copolymer, for example, a commercially available product such as Asaflex I series (manufactured by Asahi Kasei Chemicals Co., Ltd.) may be used.

The block copolymer of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon may be a mixture of two or more types. That is, even if the block copolymers of individual styrene-based hydrocarbons and conjugated diene-based hydrocarbons alone do not satisfy the predetermined viscoelastic properties of the heat-shrinkable laminated porous film shown below, the heat-shrinkable laminated film is laminated after mixing. It is also possible to mix and use a porous film that satisfies a predetermined viscoelastic property.

The storage elastic modulus (E'(0)) of the styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer at 0 ° C. ^{is preferably 5.0 × 10 8} Pa or more, and 7.0 × 10 ⁸ Pa or more. more preferably, also less preferred 1.0 × ¹⁰ 9 Pa. 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, also 2.0 × ¹⁰ 9 Pa or less. In order to adjust the storage elasticity (E'(0) and (50)) of the styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer at 0 ° C. and 50 ° C. within the above range, for example, styrene-based hydrocarbon. The peak loss elasticity (E ″) of the −conjugate diene hydrocarbon copolymer may be present in the range of −80 ° C. or higher and 0 ° C. or lower, preferably −80 ° C. or higher and −20 ° C. or lower, and a butadiene block. The difference in molecular weight between the styrene block and the styrene block may be adjusted. Further, the storage elastic coefficient (E'(90)) of the styrene hydrocarbon-conjugated diene hydrocarbon copolymer at 90 ° C. 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. Styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer has storage elasticity at 90 ° C. the rate to a 1.0 × 10 7 ^Pa or more, can be adjusted by a state close styrene block pure blocks such SBS Thus, styrene-based hydrocarbon -. conjugated diene hydrocarbon copolymerization By making the block structure of the butadiene part of the coalescence a random block and making the block structure of the styrene part close to a pure block, the storage elasticity (E') at 0 ° C., 50 ° C., and 90 ° C. is set within a predetermined range. Can be adjusted.

(Other additives)
On the front and back layers, inorganic particles such as silica, talc, and kaolin, in order to improve and adjust various physical properties of the mold processability, productivity, and heat-shrinkable laminated porous film, as long as the effects of the present invention are exhibited. Additives such as pigments such as titanium oxide and carbon black, flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, cross-linking agents, lubricants, nucleating agents, plasticizers, and anti-aging agents as appropriate. It may be added.

<Perforated layer>
(Polyolefin-based resin (B))
The polyolefin-based resin (B) is a polymer containing an olefin hydrocarbon such as propylene or ethylene as a monomer component. The polyolefin-based resin (B) may be a homopolymer of an olefin hydrocarbon 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, ethylene-propylene copolymer and the like. Among these, polypropylene resin and polyethylene resin are preferable as the polyolefin resin. 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-based resin include low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and a copolymer containing ethylene as a main component. The copolymer containing ethylene as a main component may be a random copolymer or a block copolymer when it is a copolymer. Further, in the case of a copolymer, the copolymerization component is not limited, and examples thereof include propylene, butene, and hexene. When the polyethylene-based 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 viewpoint of heat-shrinkability and easy-opening property of the heat-shrinkable laminated porous film.

The catalyst used when polymerizing the polyolefin-based resin is also not particularly limited, and a Ziegler-Natta-based catalyst, a metallocene-based catalyst, or the like can be used. Further, the stereoregularity is not particularly limited, and isotactics and syndiotactics can be used. Further, the polyolefin-based resin used may have any crystallinity or melting point, and two types of polyolefin-based resins having different properties are blended in a specific range depending on the physical properties and use of the obtained porous film. The polyolefin-based resin composition obtained may be used.

The MFR (JIS K6922, temperature 190 ° C., load 2.16N) of the polyolefin resin can adjust the melt viscosity with other layers such as, and the sheet appearance failure due to the viscosity difference is less likely to occur during coextrusion. Therefore, it is preferably 0.5 g / 10 minutes or more, more preferably 1.0 g / 10 minutes or more, and preferably 15 g / 10 minutes or less, and preferably 10 g / 10 minutes or less. More preferred.

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to 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 this embodiment, Mw / Mn is obtained from Mw and Mn measured by gel permeation chromatography (GPC).

The melting point of the polyolefin resin is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 120 ° C. or higher, from the viewpoint of having a good balance between the mechanical strength and heat resistance of the film and preventing deterioration of stretchability. It is preferable, 150 ° C. or lower is preferable, 140 ° C. or lower is more preferable, and 130 ° C. or lower is further preferable. In the present embodiment, the melting point is measured using a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min in accordance with JIS K7121.

(filler)
As the filler, an inorganic filler such as inorganic particles, an organic filler such as organic particles, and various 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. A porous film produced by using particles of a high basic compound having a pH of more than 9 in an aqueous suspension such as calcium carbonate is irritating to the skin, so its use is restricted in applications where it often comes into contact with the human body. Therefore, it is preferable to use barium sulfate or the like, which is a neutral compound having a pH of 6 or more and a pH of about 9. These fillers may be used alone or in combination of two or more.

Examples of the organic filler include particles obtained by cross-linking a polymer compound with a cross-linking agent, for example, cross-linked particles of a polymethoxysilane-based compound, cross-linked particles of a polystyrene-based compound, cross-linked particles of an acrylic compound, and polyurethane. Examples thereof include crosslinked particles of a system compound, crosslinked particles of a polyester compound, crosslinked particles of a fluorine compound, and a mixture thereof.

In the heat-shrinkable laminated porous film, a polyolefin resin and a filler are blended, melt-kneaded, and then stretched to peel off and open the interface between the polyolefin resin and the filler to form pores. be able to. Therefore, if the dispersibility of the filler with respect to the polyolefin resin is good, uniform pores can be formed. As the filler, either an inorganic type or an organic type may be used as long as it is a filler suitable for forming pores. When an organic filler is used 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 or more and 10 μm or less. Further, since morphology control is required when an organic filler is used, an inorganic filler is preferable from the viewpoint of facilitating porosity.

The average particle size of the filler is not particularly limited. The average particle size of the filler is 0.1 μm or more from the viewpoint that the dispersibility of the filler is good and the generation of foreign substances and pinholes generated by the agglomeration of particles in the obtained porous film is suppressed. It is preferably 10 μm or less. Further, when the average particle size is 10 μm or less, the dispersibility of the particles is good, the agglomeration of the filler can be prevented, uniform pores are formed, the stretchability is improved, and the occurrence of pinholes is prevented. Can be done. Further, when the average particle size is 0.1 μm or more, the dispersibility of the particles is good, and when forming the pores, the interface serving as the starting point becomes large, so that sufficient pores 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 it is better to use flat particles than rice granular particles. Is preferable. In the present embodiment, the average particle size is defined by observing the particles with a scanning electron microscope (HITACHI S-4700), the average value of the major axis and the minor axis of the particles is the particle size, and the number of sampled particles is 100. The average value of the time.

The mixing ratio of the filler in the porous layer is 40 from the viewpoint of obtaining sufficient air permeability and from the viewpoint of reducing the aggregation of the filler that occurs when the polyolefin resin and the filler are mixed and suppressing the dispersion failure. It is preferably mass% or more and 70 mass% or less, more preferably 42.5 mass% or more and 67.5 mass% or less, and further preferably 45 mass% or more and 65 mass% or less.

(Other additives)
In addition to the above components, known additives such as antioxidants, heat stabilizers, antistatic agents, slip agents, blocking inhibitors, particle dispersants, polyterpene resins, petroleum resins and fillers are added to the porous layer. It may be contained to the extent that the manufacturing process and film characteristics are not deteriorated.

<Adhesive resin>
The adhesive resin, which is the main component of the adhesive layer, is not particularly limited as long as it improves the interlayer adhesiveness between the adhesive layer and the porous layer. As the adhesive resin, an adhesive resin having a portion having an affinity for the copolymer resin (A), which is the main component of the porous layer, and a portion having an affinity with the polyolefin resin (B) of the porous layer. Is preferably used.

Here, "having an affinity for the copolymer resin (A)" means having a chain having an affinity for the copolymer resin (A). Examples of such a chain having an affinity include a resin having a styrene-based 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 “site having an affinity with the polyolefin resin (B)” means having a chain having an affinity with the polyolefin resin (B). Examples of such an affinity chain include those having a linear or branched saturated hydrocarbon moiety as a main chain, a block chain, a graft chain, or the like.

Further, as the adhesive resin, a soft polyolefin resin, a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, a hydrogenated resin thereof, and the like are preferable. Examples of the soft polyolefin-based resin include soft linear low-density polyethylene, low-crystalline polypropylene-based resin, and ethylene-vinyl acetate copolymer. Examples of the copolymer of the styrene-based hydrocarbon and the conjugated diene-based hydrocarbon include a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-ethylene-butadiene copolymer, and a styrene-ethylene-propylene copolymer. Examples thereof include a styrene-ethylene-butylene copolymer.

As a commercially available product of a resin having a functional group having a high affinity with the above-mentioned copolymer resin (A) and having a functional group having a high affinity with the polyolefin resin (B), it is conjugated with a styrene-based hydrocarbon. "Dynaron (registered trademark)" (JSR), "Hybler (registered trademark)" (Kurare), "Tough Tech (registered trademark) H" as a copolymer with diene hydrocarbon and its hydrogenated resin. (Asahi Kasei Chemicals), "Clayton (Registered Trademark)" (Clayton Polymer Japan), "Septon (Registered Trademark)" (Kurare), "Tough Prene (Registered Trademark)" (Asahi Kasei Chemicals), Acid As modified polyolefin resins, "Admer (registered trademark)" (manufactured by Mitsui Chemicals), "Modic (registered trademark)" (manufactured by Mitsubishi Chemicals), "Modiper (registered trademark)" (manufactured by Nichiyu), ethylene-acetate "Bondain (registered trademark)" (manufactured by Alchema) as a vinyl-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate ternary copolymer, ethyl ethylene-acrylate -Glysidyl methacrylate ternary copolymer "Bond First (registered trademark)" (manufactured by Sumitomo Chemical Co., Ltd.), acid-modified styrene-based thermoplastic resin "Tough Tech (registered trademark) M" (manufactured by Asahi Kasei Chemicals Co., Ltd.), " Epofriend (registered trademark) "(manufactured by Daicel) and the like.

(Other additives)
In addition to the above components, known additives such as antioxidants, heat stabilizers, antistatic agents, slip agents, antiblocking agents, particle dispersants, polyterpene resins, petroleum resins and fillers are used in the adhesive layer. It may be contained to the extent that the manufacturing process and film characteristics are not deteriorated.

<Manufacturing method of heat-shrinkable laminated porous film>
The heat-shrinkable laminated porous film can be produced by a known method for producing a laminated film. The form of the film may be either flat or tubular, but from the viewpoint of productivity (several pieces can be taken as a product in the width direction of the raw film) and printing on the outer surface is possible, the film is flat. Is preferable. As a method for producing a flat film, for example, the resin is melted using a plurality of extruders, co-extruded from a T-die, cooled and solidified by a chilled roll, rolled in the vertical direction, and tentered in the horizontal direction. , Annealing, cooling, and winding with a winder to obtain a film. Further, a method of cutting open a film produced by the tubular method to make it flat can also be applied.

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 the resin, optimizing the extrusion temperature and shear conditions and controlling the dispersion state 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. Is.

In applications such as for overlapping, which are contracted in two directions, the stretch ratio in the longitudinal 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. Further, the stretching ratio in the lateral direction (TD) orthogonal to the film flow direction is preferably 2 times or more and 10 times or less, and more preferably 3 times or more and 6 times or less. In addition, 1 times means the case which is not stretched.

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

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

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

In the heat-shrinkable laminated porous film, at least one of the porous layer and the adhesive layer may contain a film reclaimed resin that regenerates the heat-shrinkable laminated porous film generated from trimming loss or the like. The reclaimed film resin is preferably blended in the porous layer. The blending amount of the film recycled resin may be contained so as not to deteriorate the manufacturing process and the film characteristics.

(Other processing)
In the heat-shrinkable laminated porous film, if necessary, surface treatment and surface treatment such as corona treatment, printing, coating, and thin film deposition, as well as bag making and perforation processing using various solvents and heat seals, etc. are performed. Can be applied.

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

In addition, the heat-shrinkable laminated porous film can be used as a base material for heat-shrinkable labels for transported articles. In this case, even if the article has a complicated shape such as a centrally constricted cylinder, a square pillar with a corner, a pentagonal pillar, or a hexagonal pillar, it can be adhered to the complicated shape and is beautiful without wrinkles and avatars. It will be the attached label. The molded product can be produced by using a normal molding method.

The heat-shrinkable laminated porous film is a heat-shrinkable label material used for plastic molded products that deforms when heated to a high temperature, as well as a material whose heat expansion rate and water absorption are extremely different from those of the above-mentioned heat-shrinkable film. For example, a package using at least one selected from metal, porcelain, glass, paper, polymethacrylic acid ester resin, polycarbonate resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, and polyamide resin as a constituent material. It can also be suitably used as a heat-shrinkable label material.

In addition to the above resins, the materials constituting the plastic package include rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, and 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, Silicone resin and the like can be mentioned. These plastic packages may be a mixture of two or more kinds of resins or a laminate.

As described above, according to the above-described embodiment, the polyolefin-based resin and the filler are sandwiched between a pair containing at least one of a copolymer resin of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon as a main component. Since a porous layer containing a resin composition containing a resin composition as a main component is provided and stretched, sufficient shrinkage characteristics are imparted to the porous layer, and pores necessary for exhibiting easy-opening property and cushioning property are formed in the porous layer. To make it porous. As a result, the heat-shrinkable laminated porous film according to the above embodiment can reduce the gap between the film and the article to be covered by heat shrinkage, and can be easily opened when the article covered by heat shrinkage is opened. Will be excellent. The heat-shrinkable laminated porous film can also have good shrinkage finish when applied to a wide variety of articles in recent years for reducing the use of depleting resources and improving transportation efficiency. After coating a heat-shrinkable film on a wide variety of articles to form a coated article, it is suitably used for shrinkage packaging, shrinkage binding packaging, shrinkage label, etc., which are excellent in easy-to-open when opening the coated article. Can be done.

Hereinafter, the present invention will be described in more detail based on examples carried out to clarify the effects of the present invention. The present invention is not limited to the following examples and comparative examples.

<Measurement method>
The measurement and evaluation of various physical properties in the examples were carried out as follows. In the following examples, the take-back (flow) direction of the heat-shrinkable laminated porous film is described as the "vertical" direction (or MD), and the direction orthogonal to the "vertical direction" is described as the "horizontal" direction (or TD). .. Further, in the following examples, the "horizontal" direction (TD) is the main shrinkage direction of the heat-shrinkable laminated porous film, and the "longitudinal" direction (MD) is the orthogonal direction orthogonal to the main shrinkage direction.

(1) Pore ratio The pore ratio is a numerical value indicating the ratio of the space portion in the heat-shrinkable laminated porous film. For the porosity, the real amount W1 of the heat-shrinkable laminated porous film is measured, the mass W0 when the porosity is 0% is calculated from the density and thickness of the resin composition, and the mass W0 and the real amount W1 are as follows. Calculated based on equation (1).
Pore ratio = {(W0-W1) / W0} x 100 (%) ... Equation (1)

(2) Heat shrinkage rate The obtained film is cut into sizes 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 in the horizontal direction (TD) and horizontal direction ( The amount of shrinkage in MD) was measured. For the heat shrinkage rate, the ratio of the amount of shrinkage to the original size before shrinkage was expressed as a% value in the vertical direction (TD) and the horizontal direction (MD).

(3) Tear strength The obtained heat-shrinkable laminated porous film was prepared into vertical (TD) and horizontal (MD) test pieces in accordance with JIS-K7128, and both ends of the test piece were gripped with a universal testing machine. The tensile breaking strength was measured under the conditions of an atmospheric temperature of 23 ° C. and a tensile speed of 200 mm / min. The TD and MD tear strengths per unit thickness were calculated using the following formula (2), and the average value of 5 times was measured.
Tear strength = tensile fracture strength / thickness (N / mm) ・ ・ ・ Equation (2)

(4) Stretch Break Elongation The obtained heat-shrinkable laminated porous film was cut into a size of 120 mm in the vertical direction (MD) and 15 mm in the horizontal direction (TD). The cut out heat-shrinkable laminated porous film was measured for tensile elongation at break in the longitudinal 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) Delamination strength The obtained film was cut into a size of 15 mm in the vertical direction (MD) and 150 mm in the horizontal direction (TD), and one side of the end face in the horizontal direction (TD) was partially peeled from the porous layer. The peeled layer and the layer to be peeled were 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 lateral (TD) direction. In the region where the load obtained in the peeling test showed a stable value, the average value was evaluated as the delamination strength.

(6) Delamination property The obtained heat-shrinkable laminated porous film is cut into a size of 300 mm in the vertical direction (MD) and 225 mm in the horizontal direction (TD), and cellophane tape (registered trademark) as an adhesive tape (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 confirm the delamination state when the cellophane tape (registered trademark) is peeled off. evaluated. In addition to the above delamination strength evaluation, the delamination property was evaluated according to the following criteria.
〇: Peeling strength is 0.8 (N / 15 mm width) or more and there is no delamination by tape peeling ×: Peeling strength is less than 0.8 (N / 15 mm width) or there is delamination by tape peeling

(7) Shrinkage Finishing property The obtained film was cut out in the vertical direction (MD) of 120 mm and the horizontal direction (TD) of 225 mm, folded so as to overlap the TD by 10 mm, and the overlapped portion was heat-sealed to form a cylindrical film. .. Next, a cylindrical film was placed on a 225 ml bottle up to the bottom surface of the bottle to prepare a sample for finish evaluation. The evaluation sample was allowed to pass the temperature of each zone in the tunnel in 20 seconds under the following temperature conditions without rotating in the contraction tunnel having a length of 2.5 m (3-zone configuration) by the hot air heating method. The bottle was evaluated by confirming that there were no creases or wrinkles due to the shrinkage of the film that had shrunk in the bottle, and that the shrinkage was insufficient. Evaluation was performed on each sample N = 10. The temperature conditions inside 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 the tunnel for injecting hot air: 1 zone / lower part of film, 2 zones / entire film, 3 zones / entire film After film coating, evaluation was performed according to the following criteria.
◯: Sufficient shrinkage does not cause wrinkles, avatars, or grid distortion.
X: Sufficient shrinkage, but wrinkles, avatars, and lattice distortions occur significantly, or shrinkage is not sufficient and the coating on the bottle is insufficient.

The raw materials used in each of 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 "Novatec SF240", manufactured by Nippon Polyech, MFR = 2.0 g / 10 minutes, melting point = 126 ° C (hereinafter, also referred to as "polyolefin resin")
<Filler (C)>
-Barium sulfate, trade name "Variace B-54", manufactured by Sakai Chemical 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 constituents (hereinafter, "polyester"). Also called "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 constituents (hereinafter, "polyester"). Also called "based resin B2")
-Polyester containing 1,4-butanediol: 100.0 mol%, terephthalic acid: 90.0 mol%, and 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, JSR styrene content = 20%, MFR (230 ° C., 21.2N) = 5.5 g / 10 minutes (hereinafter, Also called "adhesive resin C1")
-Functional group-containing hydrogenated styrene-butadiene copolymer: Trade name: Dynalon 8903P, JSR styrene content = 35%, MFR (230 ° C., 21.2N) = 10 g / 10 minutes (hereinafter, "adhesive resin C2") Also called)
-Styrene-based thermoplastic elastomer: Product name: Hybler 7125, manufactured by Kuraray Co., Ltd. Styrene content = 20%, MFR (230 ° C, 2.16 kg) = 4 g / 10 minutes (hereinafter, also referred to as "adhesive resin C3")
-Modified polyolefin-based thermoplastic elastomer: Product name: Admer SF725, manufactured by Mitsui Chemicals, Inc. (hereinafter, also referred to as "adhesive resin C4")

(Example 1)
As the front and back layers, 100 parts by mass of the copolymer resin A1 was used. As the porous layer, 40 parts by mass of a polyolefin resin and 60 parts by mass of a filler were mixed and used. As the adhesive layer, 100 parts by mass of the 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 /, after mixing each raw material, the above 3 is used by 3 single-screw extruders and 3 types 5-layer multi-manifold base. The seed five-layer laminated film was co-extruded in a facility capable of laminating and co-extruding. And the extruder set temperature of the adhesive layer is 210 ° C or higher and 220 ° C or lower, and the extruder set temperature of the porous layer is 220 ° C or higher and 230 ° C or lower. The layer was co-extruded so as to have a layer of 4/1/14/1/4, taken up with a cast roll at 60 ° C., and cooled and solidified to obtain an unstretched laminated sheet. Next, using a film tenter, the obtained unstretched analysis layer sheet was stretched at the stretching temperature shown in Table 1 below at the stretching ratio in the flow direction shown in Table 1 below. Next, after stretching at a stretching ratio of 5 times in the width direction, heat treatment was performed at the heat treatment temperatures shown in Table 1 below to obtain a heat-shrinkable laminated porous film. The composition of each raw material used for producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 prepared 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 producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 3)
A thermosetting 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 as the adhesive layer. The composition of each raw material used for producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 prepared 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 producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Example 5)
A thermosetting 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 as the adhesive layer. The composition of each raw material used for producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 a polyolefin resin and 50 parts by mass of a filler were used as the porous layer. The composition of each raw material used for producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 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 for 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 heat-shrinkable film was obtained by relaxing by about 5% while performing the heat treatment at the heat treatment temperature shown in Table 1 below. The composition of each raw material used for producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the 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 producing the heat-shrinkable laminated porous film is shown in Table 2 below, and the various evaluation results of the obtained heat-shrinkable laminated porous film are shown in Table 3 below.

(Comparative Example 1)
As the front and back layers, 100 parts by mass of the polyester resin C1 was used instead of the copolymer resin A1, and as the adhesive layer, 100 parts by mass of the adhesive resin B4 was used instead of the adhesive resin B1. The extruder set temperature of the adhesive layer was set to 240 ° C or higher and 250 ° C or lower, the extruder set temperature of the adhesive layer was set to 210 ° C or higher and 220 ° C or lower, and the extruder set temperature of the porous layer was set to 220 ° C or higher and 230 ° C or lower. An unstretched laminated sheet was obtained in the same manner as in Example 1 except for the above. Next, the unstretched laminated sheet obtained by using the film tenter was stretched at the stretching temperature shown in Table 4 below for the stretching ratio in the flow direction shown in Table 4 below, and then the stretching ratio in the width direction was 5 times. It was stretched at. Next, heat treatment was performed at the heat treatment temperatures shown in Table 4 below to obtain a heat-shrinkable film. The composition of each raw material used for producing 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 prepared 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 producing 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)
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 producing 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 producing 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 the polyester resin C1 and 15 parts by mass of the polyester resin C3 were mixed and used. After mixing each raw material, co-extrude each layer so that the set temperature of the extruder is 240 ° C. and the thickness ratio of each layer is / intermediate layer / = 1/6/1. except that stretched under the conditions shown in table 4 in draw ratio 5.0 times the direction in the same manner as in example 1 to give a heat-shrinkable product Sofu Irumu. The formulation of the raw materials used for producing the heat-shrinkable product Sofu Irumu shown in the following Table 5 shows the various evaluation results of the resulting heat-shrinkable product Sofu Irumu in Table 6 below.

(Comparative Example 6)
As the front and back layers, 100 parts by mass of the copolymer resin A2 was used. As the intermediate layer , 100 parts by mass of the copolymer resin A3 was used. After mixing each raw material, except that stretched under the conditions shown in Table 4 in the same manner as in Comparative Example 5 to give a heat-shrinkable product Sofu Irumu. The formulation of the raw materials used for producing the heat-shrinkable product Sofu Irumu shown in the following Table 5 shows the various evaluation results of the resulting heat-shrinkable product Sofu Irumu in Table 6 below.

As can be seen from Tables 1 to 3, the heat-shrinkable laminated porous film according to Examples 1 to 9 includes a front and back layer and a porous layer according to the above embodiment, and thus is excellent in sufficient porosity. It had heat shrinkage, good fracture resistance and delamination resistance, and was easily torn. On the other hand, since the front and back layers of the heat-shrinkable laminated porous films according to Comparative Examples 1 to 4 do not contain the copolymer resin (A), they are all resistant to Examples 1 to 9. The delamination property was inferior. Further, the heat-shrinkable films according to Comparative Examples 5 and 6 were inferior in porosity and easy tearability because the intermediate layer did not contain the polyolefin resin (B).

Although the present invention has been described above in relation to the most practical and preferred embodiments at the present time, the present invention is limited to the embodiments disclosed in the present specification. A heat-shrinkable laminated porous film that can be appropriately changed within the scope of the claims and the gist of the invention that can be read from the entire specification, or within a range that does not contradict the idea, and a molded product using the film. And the heat-shrinkable label, as well as the molded article and the article to which the label is attached, must also be understood as included in the present invention.

The present invention has an effect that the gap between the coated article and the coated article after heat shrinkage can be reduced, and the heat-shrinkable laminated porous film and the coated article having excellent easy-opening property when opening the coated article can be realized. However, for example, it can be suitably used for shrink wrapping, shrinkage bundling wrapping, shrinkage label, and the like of articles having a wide variety of shapes to be covered.

1,2,3 Heat-shrinkable laminated porous film 11,111,112 Front and back layer 12 Porous layer 21,21,122 Surface layer 22,221,222 Back layer 23,231,232 Intermediate layer

Claims (10)

A pair of front and back layers containing at least 50% by mass or more of at least one selected from the group consisting of a copolymer resin (A) of a styrene-based hydrocarbon and a conjugated diene-based hydrocarbon.
A porous layer provided between the pair of front and back layers and containing 50% by mass or more of a resin composition containing a polyolefin resin (B) and a filler (C).
Adhesiveness provided between the front and back layers and the intermediate layer and having a portion having an affinity for the copolymer resin (A) and a portion having an affinity for the polyolefin resin (B). With an adhesive layer containing 50% by mass or more of resin ,
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 according to claim 1 or 2, wherein the adhesive resin contains at least one selected from a soft polyolefin-based resin, a copolymer of a styrene-based hydrocarbon and a conjugated diene hydrocarbon, and a hydrogenated resin thereof. Shrinkable laminated porous film. The heat-shrinkable laminated porous film according to any one of claims 1 to 3, wherein the polyolefin-based 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 pore ratio is 30% or more and 70% or less. The heat shrinkage according to any one of claims 1 to 5, wherein the heat shrinkage in the main shrinkage direction, which maximizes the amount of shrinkage when immersed in warm water at 100 ° C. for 10 seconds, is 50% or more. Laminated porous film. The heat-shrinkable laminated porous film according to claim 6, wherein the heat-shrinkability in the orthogonal direction orthogonal to the main shrinkage direction is 20% or more. After attaching an adhesive tape having a delamination strength of 0.8 N / 15 mm or more in the main contraction direction and an adhesive strength of 4.01 N / 10 mm measured under the condition of a tensile speed of 100 mm / min, 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 by the following measuring method based on JIS K7128 is 100 N / mm or less.
<Measurement method of tear strength>
A test piece in the direction orthogonal to the main shrinkage direction and the main shrinkage direction of the heat-shrinkable laminated porous film was prepared, both ends of the test piece were grasped by a universal testing machine, and the atmospheric temperature was 23 ° C. and the tensile speed was 200 mm / min. The tensile breaking strength in the above is measured, the main contraction direction per unit thickness and the orthogonal tear strength orthogonal to the main contraction direction are calculated using the following formula, and the average value of 5 times is taken as the tear strength.
Tear strength = tensile fracture strength / thickness (N / mm) A coated article, characterized in that at least a part thereof is coated with the heat-shrinkable laminated porous film according to any one of claims 1 to 9.

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