Heat-shrinkable multilayer film and method for producing the same

Abstract

To provide a heat-shrinkable multilayer film having antibacterial performance.SOLUTION: A heat-shrinkable multilayer film includes a base material which has a first surface and a second surface and contains a thermoplastic resin, an intermediate layer which is laminated on at least one of the first surface and the second surface of the base material and contains a thermoplastic resin, and a resin-made overcoat layer which is laminated on the intermediate layer, protects the intermediate layer and is obtained by dissolving an organic antibacterial agent, wherein a melting point of the organic antibacterial agent is 135°C or higher.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-shrinkable multilayer film and a method for producing the same. [Background technology]

[0002] BACKGROUND ART In recent years, many containers such as PET bottles and metal cans have heat-shrinkable labels attached thereto, which are heat-shrinkable films made of thermoplastic resins and have been printed on (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-161147 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, antibacterial properties have been desired in heat-shrinkable films, but no heat-shrinkable multilayer film with sufficient antibacterial properties has yet been proposed. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a heat-shrinkable multilayer film with antibacterial properties and a method for producing the same. [Means for solving the problem]

[0005] Item 1. A substrate having a first surface and a second surface and containing a thermoplastic resin; an intermediate layer containing a thermoplastic resin laminated on at least one of the first surface and the second surface of the substrate; an overcoat layer made of a resin, laminated on the intermediate layer to protect the intermediate layer and having an organic antibacterial agent dissolved therein; Equipped with A heat-shrinkable multilayer film, wherein the melting point of the organic antibacterial agent is 135°C or higher.

[0006] Item 2. The heat-shrinkable multilayer film according to Item 1, wherein the overcoat layer has a thickness of 0.5 to 3.0 μm.

[0007] Item 3. The heat-shrinkable multilayer film according to Item 1 or 2, wherein the substrate and the intermediate layer contain a styrene-based resin.

[0008] Item 4. The heat-shrinkable multilayer film according to any one of Items 1 to 3, wherein the overcoat layer contains an acrylic resin.

[0009] Item 5. The heat-shrinkable multilayer film according to any one of Items 1 to 4, wherein the intermediate layer further contains antiblocking fine particles.

[0010] Item 6. A substrate containing a thermoplastic resin having a first surface and a second surface, and a resin overcoat layer laminated on at least one of the first surface and the second surface of the substrate, protecting the substrate and having an organic antibacterial agent dissolved therein. A heat-shrinkable multilayer film, wherein the melting point of the organic antibacterial agent is 135°C or higher.

[0011] Item 7. A first material for a substrate containing a thermoplastic resin, and a second material for an intermediate layer containing a thermoplastic resin and an organic antibacterial agent having a melting point of 135 ° C. or more held in the thermoplastic resin; co-extruding the first material and the second material to form an intermediate film having the intermediate layer laminated on at least one side of the substrate; stretching the intermediate film; applying a third material for an overcoat layer, in which the organic antibacterial agent is soluble, to the surface of the intermediate film on which the second material for the intermediate layer is formed; dissolving the organic antimicrobial agent in the third material; A method for producing a heat-shrinkable multilayer film, comprising: [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a heat-shrinkable multilayer film having antibacterial properties and a method for producing the same. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing an example of a heat-shrinkable multilayer film of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of a heat-shrinkable multilayer film of the present invention. [Figure 3] FIG. 2 is a cross-sectional view showing an example of a method for producing the heat-shrinkable multilayer film of FIG. [Figure 4] 1 is a cross-sectional view showing an example of a heat-shrinkable multilayer film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, one embodiment of the heat-shrinkable multilayer film according to the present invention will be described. This heat-shrinkable multilayer film comprises a sheet-like substrate having a first side and a second side, an intermediate layer laminated on at least one of the first side and the second side of the substrate, and an overcoat layer 3 laminated on the intermediate layer. Therefore, as shown in FIG. 1, the heat-shrinkable multilayer film according to this embodiment can be configured in two ways: in which an intermediate layer 2 is laminated on both sides of a substrate 1, and an overcoat layer 3 is laminated on one of the intermediate layers 2; and in which an intermediate layer 2 is laminated on one side of a substrate 1, and an overcoat layer 3 is laminated on the intermediate layer 2, as shown in FIG. 2. Each component will be described in detail below.

[0015] <1. Base material> The substrate 1 can be made of any conventionally known thermoplastic resin material, and is not particularly limited. Examples of such materials include polyamide resin, polyester resin, polyethylene resin, polyvinyl alcohol resin, polypropylene resin, polystyrene resin, and cyclic olefin resin. However, polystyrene resin, polyester resin, and polypropylene resin are preferred because they provide favorable heat shrinkability. These resins may be used alone or in combination of two or more.

[0016] <1-1. Styrene-based resin> As the styrene-based resin, from the viewpoint of exhibiting heat shrinkability, for example, a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-isoprene-butadiene copolymer, a styrene-acrylic copolymer, etc. can be used.

[0017] The Vicat softening temperature of the styrene resin is preferably not less than 60° C., and more preferably not less than 70° C. When the styrene resin is a mixed resin containing two or more styrene resins with different Vicat softening temperatures, the Vicat softening temperature of the styrene resin refers to an apparent Vicat softening temperature calculated by adding up the products of the Vicat softening temperatures of the individual styrene resins and their blending ratios (weight ratios).

[0018] <1-2. Styrene-based elastomer> The substrate 1 may further contain a styrene elastomer, a hydrogenated styrene thermoplastic elastomer, or the like to suppress low-temperature cutting of the above-mentioned <1-1. Styrene-based resin>, and the content of the styrene elastomer relative to 100 parts by weight of the above-mentioned styrene-based resin component is preferably 15 parts by weight or less, and more preferably 10 parts by weight or less.

[0019] <1-3. Thickness of base material> The thickness of the substrate 1 is, for example, preferably 10 to 60 μm, and more preferably 15 to 50 μm.

[0020] 2. Middle Class The intermediate layer 2 contains a thermoplastic resin and an organic antibacterial agent 4. The thermoplastic resin can be selected from the same thermoplastic resin materials as those used for the substrate 1. It can also contain an antiblocking agent to provide antiblocking performance and a lubricant to provide lubricity. Details of the thermoplastic resin material are as described for the substrate 1, but the differences from the substrate 1 will be explained below.

[0021] <2-1. Styrene-based resin> The Vicat softening temperature of the styrene resin constituting the intermediate layer 2 is preferably higher than that of the styrene resin of the substrate 1 in order to suppress natural shrinkage, and is preferably 70° C. or higher, and more preferably 75° C. or higher. When this styrene resin is a mixed resin containing two or more styrene resins with different Vicat softening temperatures, the Vicat softening temperature of this styrene resin means the apparent Vicat softening temperature calculated by adding up the products of the Vicat softening temperatures of each styrene resin and the blending ratio (weight ratio).

[0022] <2-2. Organic antibacterial agents> The organic antibacterial agent is a material that is soluble in the overcoat layer 3 described below, and taking into consideration the barrel temperature during co-extrusion described below, the difference between the barrel temperature during co-extrusion and the melting point of the organic antibacterial agent is preferably 45° C. or less, and more preferably 40° C. or less. For example, it is preferable to use an antibacterial agent with a melting point of 135° C. or more, such as diiodomethyl-paratolyl sulfone, and more preferably an antibacterial agent with a melting point of 145° C. or more.

[0023] The content of the organic antibacterial agent is preferably 0.1 to 5 parts by weight (1 to 50 parts by weight in 10 wt% MB equivalent), and more preferably 0.3 to 4 parts by weight (3 to 40 parts by weight in 10 wt% MB equivalent), relative to 100 parts by weight of the thermoplastic resin component and organic antibacterial agent that make up the mid layer 2. When the content is within the above range, antibacterial performance is more easily exhibited.

[0024] The organic antibacterial agent does not have to be contained in both of the two intermediate layers 2, and may be contained in, for example, only one of the intermediate layers 2. The intermediate layer 2 contains an organic antibacterial agent, but as will be described later, a portion of the organic antibacterial agent dissolves in the overcoat layer 3 during the manufacturing process. However, not all of the organic antibacterial agent dissolves in the overcoat layer 3, and some of the organic antibacterial agent remains in the intermediate layer 2.

[0025] <2-3. Anti-blocking agents> The additionally used antiblocking agent (antiblocking fine particles) can be either organic or inorganic fine particles. Examples of organic fine particles include acrylic resin fine particles, styrene resin fine particles, styrene-acrylic resin fine particles, urethane resin fine particles, and silicone resin fine particles. These may be crosslinked or uncrosslinked, but crosslinking is preferred to enhance the heat resistance of the fine particles. Among these, acrylic resin fine particles are preferred from the viewpoint of compatibility with the styrene resin, and polymethyl methacrylate crosslinked fine particles are more preferred. Commercially available organic fine particles include, for example, Techpolymer (manufactured by Sekisui Plastics Co., Ltd.), Finesphere (manufactured by Nippon Paint Co., Ltd.), Ganz Pearl (manufactured by Aica Kogyo Co., Ltd.), and Art Pearl (manufactured by Negami Chemical Industrial Co., Ltd.).

[0026] Examples of inorganic fine particles that can be used include silica, zeolite, and alumina.

[0027] The mode particle diameter of the fine particles is, for example, preferably 1.0 to 7.0 μm, more preferably 1.2 to 6.7 μm, more preferably 1.5 to 6.5 μm, and particularly preferably 2.0 to 6.3 μm. When the mode particle diameter is within the above range, aggregation can be suppressed, and ink skipping due to poor trapping can be effectively suppressed. The mode particle diameter was measured by a known laser diffraction / scattering method or the like.

[0028] The content of the microparticles is preferably 0.01 to 0.20 parts by weight (0.1 to 2 parts by weight when converted to 10 wt% MB) and more preferably 0.03 to 0.1 parts by weight (0.3 to 1 part by weight when converted to 10 wt% MB) per 100 parts by weight of the thermoplastic resin component and organic antibacterial agent constituting the intermediate layer 2. When the content is within the above range, as described above, the unevenness formed on the surface of the intermediate layer 2 not only improves the blocking resistance of the heat-shrinkable multilayer film but also suppresses ink skipping due to poor trapping. Furthermore, the microparticles preferably have a higher hardness than the intermediate layer 2 described below.

[0029] The antiblocking agent may be contained in both intermediate layers 2, or in only one of the intermediate layers 2. For example, one intermediate layer 2 may contain an organic antibacterial agent, and the other intermediate layer 2 may contain an antiblocking agent.

[0030] <2-4. Lubricants> Examples of additional lubricants include oleamide, stearamide, and erucamide. The content of the lubricant is preferably 0.01 to 0.20 parts by weight (0.1 to 2 parts by weight in terms of 10 wt% MB) per 100 parts by weight of the thermoplastic resin components and organic antibacterial agent that make up the intermediate layer 2, and more preferably 0.03 to 0.15 parts by weight (0.3 to 1.5 parts by weight in terms of 10 wt% MB).

[0031] <2-5. Thickness> The thickness of the thermoplastic resin of the intermediate layer 2 is, for example, preferably 1 to 10 μm, and more preferably 2.0 to 6.0 μm.

[0032] <3. Overcoat layer> The overcoat layer 3 serves to protect the intermediate layer 2, and is preferably formed from a material in which the organic antibacterial agent contained in the intermediate layer 2 is soluble. As will be described later, the organic antibacterial agent contained in the intermediate layer 2 dissolves in this overcoat layer 3 during the manufacturing process of the heat-shrinkable multilayer film. As a result, the organic antibacterial agent dissolves in the overcoat layer 3 of the finished heat-shrinkable multilayer film, thereby exhibiting antibacterial function. The overcoat layer 3 can be formed from a resin material such as an acrylic resin or a cellulose resin. The thickness of the overcoat layer 3 is preferably, for example, 0.5 to 3.0 μm, and more preferably 1.0 to 2.0 μm.

[0033] Regarding the lubricity of the overcoat layer 3, from the viewpoint of protecting the intermediate layer 2, it is preferable that the static friction coefficient (μs) and dynamic friction coefficient (μd) of the combination of the overcoat layer 3 and the intermediate layer 2 be 0.7 or less. Furthermore, from the viewpoint of preventing scratches on the overcoat layer 3, it is preferable that the static friction coefficient (μs) and dynamic friction coefficient (μd) of the combination of two overcoat layers 3 be 0.5 or less.

[0034] The overcoat layer 3 may be laminated on only one of the intermediate layers 2 as described above, or may be laminated on both of the intermediate layers 2. In this case, for example, the overcoat layer 3 may be laminated only on the intermediate layer 2 containing an organic antibacterial agent.

[0035] <4. Thickness of heat-shrinkable multilayer film> The overall thickness of the heat-shrinkable multilayer film of the present invention is, for example, preferably 20 μm or more, more preferably 25 μm or more, and preferably 80 μm or less, more preferably 70 μm or less. When the overall thickness of the heat-shrinkable multilayer film is within the above range, excellent heat shrinkability, excellent converting properties such as printing or center sealing, and excellent wearability can be obtained.

[0036] <5. Other ingredients> The substrate 1, intermediate layer 2, and overcoat layer 3 may contain additives such as antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, fluorescent brighteners, and colorants, as needed.

[0037] 6. Heat shrinkage performance of heat shrinkable multilayer film The heat shrinkage percentage of the heat-shrinkable multilayer film of the present invention when immersed in 70°C hot water for 10 seconds is preferably 5% or more and preferably 30% or less. Furthermore, the heat shrinkage percentage when immersed in 80°C hot water for 10 seconds is preferably 30% or more and preferably 60% or less. Furthermore, the heat shrinkage percentage when immersed in 98°C hot water for 10 seconds is preferably 60% or more and preferably 76% or less. When the heat shrinkage percentage is within the above range, problems such as poor shrinkage do not occur, and the film can be suitably used as a heat-shrinkable multilayer film. The shrinkage direction is in the TD direction and MD, and it is particularly preferable that the shrinkage percentage in the TD direction be within the above range.

[0038] 7. Manufacturing method of heat-shrinkable multilayer film Although the method for producing the heat-shrinkable multilayer film of the present invention is not particularly limited, a method in which the substrate 1 and the intermediate layer 2 are simultaneously formed by co-extrusion is preferred. When the co-extrusion method is co-extrusion using a T-die, the lamination method may be any of a feed block method, a multi-manifold method, or a method combining these.

[0039] Specific examples of methods for producing the heat-shrinkable multilayer film of the present invention include a method in which the raw materials (first material and second material) constituting the substrate 1 and intermediate layer 2 are each fed into an extruder, extruded into a sheet through a die, cooled and solidified by a take-up roll, and then uniaxially or biaxially stretched. Examples of the stretching method include roll stretching, tenter stretching, or a combination of these. The stretching temperature varies depending on the softening temperature of the resin constituting the film and the shrinkage properties required of the heat-shrinkable multilayer film, but is preferably 65°C or higher, more preferably 70°C or higher, and preferably 120°C or lower, and more preferably 115°C or lower. In this way, an intermediate film such as that shown in FIG. 3(a) is formed.

[0040] The stretching ratio in the main shrinkage direction varies depending on the resin constituting the film, the stretching means, the stretching temperature, etc., but is preferably 2 times or more, more preferably 3 times or more, and is preferably 7 times or less, more preferably 6 times or less.

[0041] Subsequently, a coating liquid (third material) for the overcoat layer is applied to the surface of the intermediate layer 2. The coating liquid for the overcoat layer is, for example, a mixed solvent of isopropanol and acetic ester containing the above-mentioned materials, and can be applied by a method such as screen printing. When the coating liquid is applied in this manner, as shown in the enlarged view of FIG. 3(b), the organic antibacterial agent 7 contained in the intermediate layer 2 dissolves in the coating liquid, and the solvent in the coating liquid evaporates. As a result, an overcoat layer 3 containing the organic antibacterial agent dissolved therein is formed, and a heat-shrinkable multilayer film is completed.

[0042] <8. Uses of heat-shrinkable multilayer films> The uses of the heat-shrinkable multilayer film of the present invention are not particularly limited. However, since the heat-shrinkable multilayer film of the present invention has excellent perforation cutting properties, excellent drop impact resistance, and excellent transparency, it is suitably used, for example, as a base film for heat-shrinkable labels to be attached to containers such as PET bottles and metal cans.

[0043] <9. Other Embodiments of Heat-Shrinkable Multilayer Film> In the above description, the heat-shrinkable multilayer film is composed of the substrate 1, the intermediate layer 2, and the overcoat layer 3. However, the heat-shrinkable multilayer film can also be constructed by forming a second substrate by integrating the substrate 1 and the intermediate layer 2, and then forming a layer having the same configuration as the intermediate layer 2 on the surface of this second substrate 5, as shown in Fig. 4. It is also possible to form the overcoat layer 3 on only one surface of the second substrate 5.

[0044] The second substrate 5 of this heat-shrinkable multilayer film can be formed from the same material as the intermediate layer 2 described above. The thickness of this second substrate 5 can be, for example, 10 to 60 μm. A configuration consisting of a second substrate 5 with fine particles unevenly distributed on the overcoat layer 3 side and an overcoat layer 3 is also within the scope of the present invention. Specifically, the film can be produced by co-extrusion of a substrate and a layer consisting of a resin composition and an organic antibacterial agent with the same composition as described in Section <1. Substrate>. In such a case, two layers are observed in a cross-sectional photograph. Then, an overcoat layer 3 can be formed on the surface of the extruded film as described above.

[0045] <10. Features> According to the present invention, an organic antibacterial agent is dissolved in the overcoat layer 3 on the outermost surface, and therefore antibacterial properties can be exhibited in this overcoat layer 3. In addition, the overcoat layer 3 protects the intermediate layer 2, and therefore, damage to the intermediate layer 2 can be prevented.

[0046] When the intermediate layer 2 contains an antiblocking agent, it is possible to form irregularities on the surface of the intermediate layer 2, which in turn can form irregularities on the surface of the overcoat layer 3. As a result, it is possible to impart antiblocking properties to the overcoat layer 3. [Example]

[0047] Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

[0048] <1. Preparation of Examples and Comparative Examples> Heat-shrinkable multilayer films according to Examples 1 and 2 and Comparative Examples 1 to 3 were prepared as follows. Examples 1 and 2 and Comparative Examples 1 to 3 have a four-layer structure as shown in FIG. 1. Here, the intermediate layers laminated on each side of the substrate are referred to as the first intermediate layer and the second intermediate layer, respectively. In Examples 1 and 2 and Comparative Examples 1 to 3, both intermediate layers contain an antiblocking agent (AB agent). Furthermore, in Examples 1 and 2 and Comparative Examples 2 and 3, the first intermediate layer and the overcoat layer further contain antibacterial fine particles.

[0049] The components shown in Table 1 were used as raw materials for the substrate and each intermediate layer, and these were mixed in the ratios shown in Table 1 to obtain raw material compositions for the substrate and each intermediate layer according to Examples 1 and 2 and Comparative Examples 1 to 3. In addition, a mixed solution of acrylic resin-containing acetate ester and IPA was prepared as a coating liquid for the overcoat layer.

[0050] The raw material composition constituting the substrate and intermediate layer was then fed into an extruder with a barrel temperature of 160-200°C, extruded through a multilayer die at 200°C into a three-layer sheet, and cooled and solidified by a take-up roll at 50°C. The film was then stretched at a stretch ratio of 3.5x in a tenter stretching machine with a preheating zone of 102°C, a stretching zone of 89-91°C, and a heat-setting zone of 86°C, and then wound up on a winder to obtain a heat-shrinkable multilayer film with a MD direction perpendicular to the main shrinkage direction and a TD direction perpendicular to the main shrinkage direction. In Examples 1 and 2 and Comparative Examples 2 and 3, the thickness ratio of the first intermediate layer, substrate, and second intermediate layer was 1:9:1. Meanwhile, in Comparative Example 1, the thickness ratio of the first intermediate layer, substrate, and second intermediate layer was 1:6:1. A coating liquid for the overcoat layer was then applied to the first intermediate layer surface of the stretched sheet by screen printing. After screen printing, a portion of the organic antibacterial agent contained in the first intermediate layer dissolves in the overcoat layer. In this way, heat-shrinkable multilayer films having the thicknesses shown in Table 2 were produced.

[0051] [Table 1] The units of each component in the substrate and both intermediate layers are parts. The melting point of the antibacterial agent MB(a) is 160°C, and the melting point of the antibacterial agent MB(b) is 110 to 113°C.

[0052] [Table 2]

[0053] <2. Evaluation> The above Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated as follows.

[0054] <2-1. Antibacterial test> Measurement was performed according to JIS Z2801, Section 5. The strain used was Escherichia coli NBRC3972.

[0055] <2-2. Blocking> The heat-shrinkable film of each example and comparative example was cut into 30 mm x 100 mm pieces to prepare two samples. The obtained samples were stacked on top of each other, and a load of 5 kg / 100 cm was applied from above. 2 The sample was placed on a sheet and left to stand at 40°C for 48 hours. The sheet was then pulled in the shear direction at a pulling rate of 200 m / min to measure the shear peel strength and evaluate it according to the following criteria. In Table 3 described below, "outside outside" refers to the evaluation of blocking when the first intermediate layers were in contact with each other, and "inside outside" refers to the evaluation of blocking when the first intermediate layer was in contact with the second intermediate layer.

[0056] <2-3. Smoothness> Using a surface property measuring instrument (14FW, manufactured by Shinto Scientific Co., Ltd.), the static friction coefficient (μs) and dynamic friction coefficient (μd) of each combination of inside-outside and outside-outside were measured in accordance with ASTM-D1894, with the overcoat layer surface (outside) and the second intermediate layer surface (inside).

[0057] <2-4. Wet heat shrinkage rate> The films obtained in each Example and Comparative Example were cut into samples measuring 100 mm in MD x 100 mm in TD to obtain test pieces. The obtained test pieces were immersed in warm water at 70°C, 80°C, 90°C, or 98°C, or in boiling water (100°C) for 10 seconds, and the heat-shrinkable multilayer film was then removed and immersed in water at 15°C for 5 seconds, and the thermal shrinkage in the TD direction was calculated according to the following formula. The thermal shrinkage was measured using three test pieces for each Example and Comparative Example, and the average value was used. Heat shrinkage rate (%) = {(100-L) / 100} x 100 The change in the heat shrinkage rate before and after the addition of the antibacterial fine particles was also measured.

[0058] <2-5. Haze> The haze of each example and comparative example was measured using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to a method conforming to JIS Z7136. Note that the haze was measured using four test pieces for each example and comparative example, and the average value was calculated.

[0059] <2-6. Glossiness> The glossiness at an incident angle of 45° was measured for each of the examples and comparative examples using a VG-2000 model manufactured by Nippon Denshoku Industries Co., Ltd. according to a method conforming to JIS Z8741.

[0060] <2-7. Evaluation Results> The evaluation results are as follows: [Table 3]

[0061] According to the above results, the overcoat layers of Examples 1 and 2 both contain an organic antibacterial agent, and therefore exhibit antibacterial properties. Since a rating of 2.0 or higher is considered satisfactory in the antibacterial test, both Examples 1 and 2 exhibit sufficient antibacterial properties. Comparative Example 1 does not contain antibacterial microparticles, and therefore does not exhibit antibacterial properties. Furthermore, in Comparative Examples 2 and 3, the organic antibacterial agent contained in the first intermediate layer has a low melting point, which is thought to be why the antibacterial properties are lost during extrusion molding.

[0062] The heat shrinkage rates of Examples 1 and 2 were ±5% (variation in heat shrinkage rate) compared to Comparative Example 1, which did not contain antibacterial fine particles. This heat shrinkage rate is highly practical and sufficient.

[0063] From the above, Examples 1 and 2 can be used as heat-shrinkable multilayer films having antibacterial properties. [Explanation of symbols]

[0064] 1 Base material 2. Middle class 3 Overcoat layer 7. Organic antibacterial agents

Claims

1. A heat-shrinkable film, a substrate having a first surface and a second surface and containing a thermoplastic resin; an intermediate layer laminated on at least one of the first surface and the second surface of the substrate, the intermediate layer containing a thermoplastic resin and having a Vicat softening temperature higher than that of the substrate; an overcoat layer made of a resin, laminated on the intermediate layer to protect the intermediate layer and having an organic antibacterial agent dissolved therein; Equipped with the substrate contains a styrene-based resin, the intermediate layer contains a styrene-based resin and the organic antibacterial agent, the styrene-based resin contained in the substrate and the intermediate layer is formed of one or more selected from the group consisting of a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-isoprene-butadiene copolymer, and a styrene-acrylic copolymer; the overcoat layer contains an acrylic resin and has a thickness of 0.5 to 3.0 μm; the content of the organic antibacterial agent is 0.1 to 5 parts by weight based on 100 parts by weight of the thermoplastic resin component and the organic antibacterial agent constituting the intermediate layer, The organic antibacterial agent is diiodomethyl-paratolyl sulfone, The melting point of the organic antibacterial agent is 135°C or higher, The heat-shrinkable multilayer film has a heat shrinkage rate of 5% or more when immersed in 70°C hot water for 10 seconds, a heat shrinkage rate of 30% or more when immersed in 80°C hot water for 10 seconds, and a heat shrinkage rate of 60% or more when immersed in 98°C hot water for 10 seconds.

2. The heat-shrinkable multilayer film according to claim 1 , wherein the intermediate layer further contains anti-blocking particles.

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