Heat shrinkable multilayer film

Abstract

To provide a heat-shrinkable multilayer film having antibacterial performance.SOLUTION: A heat-shrinkable multilayer film has a first surface and a second surface, includes a base material containing 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, is dispersed with antibacterial fine particles and contains a thermoplastic resin, and a resin-made overcoat layer which is laminated on the intermediate layer and protects the intermediate layer, where at least a part of the antibacterial fine particles is exposed from the overcoat layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat shrinkable multilayer film. [Background technology]

[0002] 2. Description of the Related Art In recent years, many containers such as PET bottles and metal cans are equipped with heat-shrinkable labels formed by printing or the like on a heat-shrinkable film made of a thermoplastic resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-161147 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, antibacterial properties have been demanded for heat shrinkable films, but no heat shrinkable multilayer film having sufficient antibacterial properties has been proposed. The present invention has been made to solve the above problems, and has an object to provide a heat shrinkable multilayer film having antibacterial properties. [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 and having antibacterial fine particles dispersed therein, the intermediate layer being laminated on at least one of the first surface and the second surface of the substrate; a resin overcoat layer laminated on the intermediate layer to protect the intermediate layer; Equipped with A heat shrinkable multilayer film, wherein at least a portion of the antimicrobial microparticles are exposed through the overcoat layer.

[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 2, wherein the mode particle size of the antibacterial fine particles is greater than a thickness of the overcoat layer.

[0008] Item 4. The heat-shrinkable multilayer film according to any one of Items 1 to 3, wherein the substrate and the intermediate layer contain a styrene-based resin.

[0009] Item 5. The heat-shrinkable multilayer film according to any one of Items 1 to 4, wherein the overcoat layer contains an acrylic resin.

[0010] Item 6. The heat-shrinkable multilayer film according to any one of Items 1 to 5, wherein the intermediate layer further contains antiblocking fine particles.

[0011] Item 7. A substrate having a first surface and a second surface and containing a thermoplastic resin in which antibacterial fine particles are dispersed; a resin overcoat layer laminated on at least one of the first surface and the second surface of the substrate to protect the substrate; Equipped with A heat shrinkable multilayer film, wherein at least a portion of the antimicrobial microparticles are exposed through the overcoat layer. Effect of the Invention

[0012] According to the present invention, a heat-shrinkable multilayer film having antibacterial properties can be provided. [Brief description 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. [Diagram 2] 1 is a cross-sectional view showing an example of a heat-shrinkable multilayer film of the present invention. [Diagram 3] 1 is a cross-sectional view showing an example of a heat-shrinkable multilayer film of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, one embodiment of the heat shrinkable multilayer film according to the present invention will be described. This heat shrinkable multilayer film includes a sheet-like substrate having a first surface and a second surface, an intermediate layer laminated on at least one of the first surface and the second surface 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 a form in which an intermediate layer 2 is laminated on both surfaces of a substrate 1, and an overcoat layer 3 is laminated on one intermediate layer 2, or in a form in which an intermediate layer 2 is laminated on one surface of a substrate 1, and an overcoat layer 3 is laminated on the intermediate layer 2, as shown in FIG. 2. Hereinafter, each member will be described in detail.

[0015] <1. Base material> The base material 1 can be appropriately selected from conventionally known thermoplastic resin materials, and the material 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, and polystyrene resin, polyester resin, and polypropylene resin are preferred in terms of obtaining 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 60° C. or higher, and more preferably 70° C. or higher. When the styrene resin is a mixed resin containing two or more styrene resins having different Vicat softening temperatures, the Vicat softening temperature of the styrene resin means an apparent Vicat softening temperature calculated by summing the products of the Vicat softening temperatures of the respective styrene resins and the blending ratios (weight ratios).

[0018] <1-2. Styrene-based elastomer> The substrate 1 may further contain a styrene-based elastomer, a hydrogenated styrene-based thermoplastic elastomer, etc., in order to suppress low-temperature cutting of the above-mentioned <1-1. Styrene-based resin>, and as the styrene elastomer, the content of the styrene-based elastomer per 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 from 10 to 60 μm, and more preferably from 15 to 50 μm.

[0020] <2. Middle class> The intermediate layer 2 contains a thermoplastic resin and antibacterial fine particles 4. As shown in the enlarged views of Figures 1 and 2, at least a portion of the antibacterial fine particles 4 is exposed from the thermoplastic resin.

[0021] <2-1. Thermoplastic resin> The thermoplastic resin can be selected from the same resin materials as those of the substrate 1 described above. In addition, an antiblocking agent for exhibiting antiblocking performance and a lubricant for exhibiting lubricity can be additionally contained. Details of the thermoplastic resin material are as explained in the substrate 1, but the differences from the substrate 1 will be explained below. The enlarged views of Figs. 1 and 2 are schematic diagrams exaggerated to explain the role of the fine particles. This point is the same as Fig. 3 described later.

[0022] 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 the natural shrinkage rate, 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 an apparent Vicat softening temperature calculated by adding up the product of the Vicat softening temperature of each styrene resin and the blending ratio (weight ratio).

[0023] <2-2. Antibacterial particles> The antibacterial fine particles 4 may be inorganic materials containing antibacterial metal ions such as silver ions and copper ions. The mode particle diameter of such inorganic materials containing metal ions is preferably, for example, 1.0 to 15.0 μm, more preferably 3.0 to 12.0 μm, and particularly preferably 5.0 to 10.0 μm. This mode particle diameter is preferably larger than the thickness of the overcoat layer 3 described below. This makes it easier for the antibacterial fine particles 4 to be exposed from the overcoat layer 3. Furthermore, this mode particle diameter is preferably larger than the thickness of the thermoplastic resin of the intermediate layer 2. However, by adjusting the content of the antibacterial fine particles 4, the mode particle diameter can also be made smaller than the thickness of the thermoplastic resin of the overcoat layer and the intermediate layer. The mode particle diameter can be measured, for example, by a known laser diffraction / scattering method.

[0024] The content of the antibacterial fine particles 4 is, for example, preferably 0.1 to 5.0 parts by weight (1 to 50 parts by weight converted into 10 wt% MB) and more preferably 0.2 to 3.0 parts by weight (2 to 30 parts by weight converted into 10 wt% MB) relative to 100 parts by weight of the thermoplastic resin component and antibacterial fine particles constituting the intermediate layer 2. When the content is within the above range, antibacterial performance is more easily exhibited.

[0025] The antibacterial fine particles 4 do not have to be contained in both of the two intermediate layers 2, and may be contained in only one of the intermediate layers 2, for example.

[0026] <2-3. Anti-blocking agents> As the additionally used antiblocking agent (antiblocking fine particles), either organic fine particles or inorganic fine particles can be used. As the organic fine particles, organic fine particles such as acrylic resin fine particles, styrene resin fine particles, styrene-acrylic resin fine particles, urethane resin fine particles, silicone resin fine particles, etc. can be used. These may be crosslinked or not crosslinked, but it is preferable that they are crosslinked to improve the heat resistance of the fine particles. Among them, acrylic resin fine particles are preferred from the viewpoint of compatibility with the above-mentioned styrene resin, and polymethyl methacrylate crosslinked fine particles are more preferred. In addition, among the above-mentioned organic fine particles, examples of commercially available products include Techpolymer (manufactured by Sekisui Chemical Co., Ltd.), Finesphere (manufactured by Nippon Paint Co., Ltd.), Ganz Pearl (manufactured by Aica Kogyo Co., Ltd.), and Art Pearl (manufactured by Negami Chemical Industry Co., Ltd.).

[0027] As the inorganic fine particles, for example, silica, zeolite, alumina, etc. can be used.

[0028] 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.

[0029] The content of the above-mentioned fine particles is, for example, preferably 0.01 to 0.20 parts by weight (0.1 to 2 parts by weight converted into 10 wt% MB) and more preferably 0.03 to 0.1 parts by weight (0.3 to 1 part by weight converted into 10 wt% MB) relative to 100 parts by weight of the thermoplastic resin component and antibacterial fine particles 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.

[0030] 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 antibacterial fine particles 4, and the other intermediate layer 2 may contain an antiblocking agent.

[0031] <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 calculated as 10 wt% MB) and more preferably 0.03 to 0.15 parts by weight (0.3 to 1.5 parts by weight calculated as 10 wt% MB) relative to 100 parts by weight of the thermoplastic resin component and antibacterial microparticles that constitute the intermediate layer 2.

[0032] <2-5. Thickness> The thickness of the thermoplastic resin of the intermediate layer 2 is, for example, preferably from 1 to 10 μm, and more preferably from 2.0 to 6.0 μm.

[0033] <3. Overcoat layer> The overcoat layer 3 is for protecting the intermediate layer 2. The overcoat layer can be formed of a resin material such as an acrylic resin or a cellulose resin. The thickness of the overcoat layer is preferably, for example, 0.5 to 3.0 μm, and more preferably 1.0 to 2.0 μm. In particular, when the thickness of the overcoat layer 3 is smaller than the mode particle size of the antibacterial fine particles 4 described above, the antibacterial fine particles 4 are more likely to be exposed from the overcoat layer 3, and antibacterial performance is more likely to be exhibited. Furthermore, the exposure of the antibacterial fine particles 4 forms unevenness on the surface of the heat-shrinkable multilayer film, so that anti-blocking performance can be exhibited. For the anti-blocking performance, the surface roughness Rz of the heat-shrinkable multilayer film is, for example, preferably 1 to 7 μm, more preferably 1.5 to 6.5 μm, and even more preferably 2 to 6 μm.

[0034] With regard to 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. Also, 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 the overcoat layers 3 themselves be 0.5 or less.

[0035] The overcoat layer 3 may be laminated on both of the intermediate layers 2. Also, for example, the overcoat layer 3 may be laminated on the intermediate layer 2 containing the antibacterial fine particles 4.

[0036] <4. Thickness of heat shrinkable multi-layer film> The total 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 total 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.

[0037] <5. Other ingredients> The substrate 1, intermediate layer 2, and overcoat layer 3 may contain additives such as antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, fluorescent brightening agents, and colorants, as necessary.

[0038] <6. Heat shrink performance of heat shrinkable multilayer film> The heat shrinkage rate 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. The heat shrinkage rate of the heat shrinkable multilayer film when immersed in 80°C hot water for 10 seconds is preferably 30% or more and preferably 60% or less. The heat shrinkage rate of the heat shrinkable multilayer film when immersed in 98°C hot water for 10 seconds is preferably 60% or more and preferably 76% or less. When the heat shrinkage rate 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 the TD direction and the MD direction, and it is particularly preferable that the shrinkage rate in the TD direction is within the above range.

[0039] <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, it is preferable to simultaneously mold the substrate 1 and the intermediate layer 2 by a co-extrusion method. 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 using both of them.

[0040] A specific example of a method for producing the heat-shrinkable multilayer film of the present invention is a method in which the raw materials constituting the substrate 1 and intermediate layer 2 are each fed into an extruder, extruded into a sheet shape through a die, cooled and solidified by a take-up roll, and then stretched uniaxially or biaxially. Examples of the stretching method include roll stretching, tenter stretching, or a combination of these. The stretching temperature is changed depending on the softening temperature of the resin constituting the film, the shrinkage properties required for the heat-shrinkable multilayer film, etc., but is preferably 65°C or higher, more preferably 70°C or higher, and preferably 120°C or lower, more preferably 115°C or lower.

[0041] 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.

[0042] By setting such a stretching temperature and stretching ratio, in particular, the resin around the antibacterial fine particles 4 (or antiblocking agent) becomes thinner by stretching the intermediate layer 2, and unevenness due to the antibacterial fine particles 4 etc. can be generated in the intermediate layer 2.

[0043] Following this, a coating liquid for the overcoat layer is applied to the surface of the intermediate layer 2. The coating liquid for the overcoat layer can be applied by a method such as screen printing. Thereafter, for example, by drying at 15 to 30°C, the overcoat layer 3 is formed, and the heat-shrinkable multilayer film is completed. At this time, at least a part of the antibacterial fine particles 4 is exposed to the outside from the overcoat layer 3.

[0044] <8. Uses of heat shrinkable multilayer films> The uses of the heat-shrinkable multilayer film of the present invention are not particularly limited, but since the heat-shrinkable multilayer film of the present invention has excellent perforation cutting properties, excellent drop impact resistance, and excellent transparency, it is preferably used, for example, as a base film for heat-shrinkable labels to be attached to containers such as PET bottles and metal cans.

[0045] <9. Other aspects 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, but the heat-shrinkable multilayer film can be constructed by forming a second substrate by integrating the substrate 1 and the intermediate layer 2, and forming a layer having a similar structure to the intermediate layer 2 on the surface of this second substrate 5 as shown in Fig. 3. Note that the overcoat layer 3 can also be formed on both surfaces of the second substrate 5.

[0046] The second substrate 5 of this heat shrinkable multilayer film can be formed of 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 the second substrate 5 with the fine particles unevenly distributed on the overcoat layer 3 side and the overcoat layer 3 is also within the scope of the present invention. Specifically, it is possible to manufacture the film by co-extrusion of the substrate and a layer consisting of the resin composition and fine particles having the same composition as described in the section <1. Substrate>. In such a case, two layers are observed in a cross-sectional photograph. After that, the overcoat layer 3 can be formed on the surface of the extruded film.

[0047] <10.Features> According to the present invention, the intermediate layer 2 contains antibacterial fine particles 4, which are exposed from the overcoat layer 3, and thus antibacterial performance can be exhibited by the antibacterial fine particles 4. In addition, the antibacterial fine particles 4 can form irregularities on the surface of the heat-shrinkable multilayer film, thereby exhibiting anti-blocking performance.

[0048] Moreover, since the intermediate layer 2 is protected by the overcoat layer 3, the intermediate layer 2 can be prevented from being damaged. EXAMPLES

[0049] Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

[0050] <1. Preparation of Examples and Comparative Examples> Heat-shrinkable multilayer films according to Examples 1 and 2 and Comparative Example were prepared as follows. Examples 1 and 2 and Comparative Example 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 Example, both intermediate layers contain an antiblocking agent (AB agent). Furthermore, in Examples 1 and 2, the first intermediate layer further contains antibacterial fine particles.

[0051] The components shown in Table 1 were used as the raw materials constituting the substrate and each intermediate layer, and raw material compositions constituting the substrate and each intermediate layer according to Examples 1 and 2 and Comparative Example were obtained by mixing these in the ratios shown in Table 1. In addition, a mixed solution of acetate ester containing an acrylic resin and IPA was prepared as a coating liquid for the overcoat layer.

[0052] Next, the raw material composition constituting the substrate and intermediate layer was put into an extruder with a barrel temperature of 160 to 200°C, extruded from a multilayer die at 200°C into a three-layered sheet, and cooled and solidified by a take-up roll at 50°C. Next, the film was stretched at a stretch ratio of 3.5 times in a tenter stretching machine with a preheating zone of 102°C, a stretching zone of 89 to 91°C, and a heat setting zone of 86°C, and then wound up by a winding machine to obtain a heat-shrinkable multilayer film in which the direction perpendicular to the main shrinkage direction is MD and the main shrinkage direction is TD. In Examples 1 and 2, the thickness ratio of the first intermediate layer, the substrate layer, and the second intermediate layer was 1:9:1. Meanwhile, in the comparative example, the thickness ratio of the first intermediate layer, the substrate, and the second intermediate layer was 1:6:1. Next, the coating liquid for the overcoat layer was applied to the first intermediate layer surface of this stretched sheet by screen printing and dried. In this way, a heat-shrinkable multilayer film with the thickness shown in Table 2 was produced.

[0053] [Table 1] The units of each composition in the substrate and both intermediate layers are parts.

[0054] [Table 2]

[0055] <2. Evaluation> The above-mentioned Examples 1 and 2 and Comparative Example were evaluated as follows.

[0056] <2-1. Antibacterial test> Measurements were performed according to JIS Z2801, Section 5. The bacterial strains used were Escherichia coli NBRC3972 and Staphylococcus aureus NBRC12732.

[0057] <2-2. Blocking> The heat-shrinkable films of the examples and comparative examples were cut to 30 mm x 100 mm 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 then placed on a sheet and allowed to stand for 48 hours at 40° C. Thereafter, the sheet was pulled in the shear direction at a pulling speed of 200 m / min to measure the shear peel strength, and evaluated according to the following criteria.

[0058] In Table 3 described below, "outside / outside" refers to the evaluation of blocking when the first intermediate layers are in contact with each other, and "inside / outside" refers to the evaluation of blocking when the first intermediate layer is in contact with the second intermediate layer.

[0059] <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).

[0060] <2-4. Wet heat shrinkage rate> The films obtained in the Examples and Comparative Examples 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, and 98°C and boiling water (100°C) for 10 seconds, and then the heat-shrinkable multilayer film was taken out and immersed in water at 15°C for 5 seconds, and the heat shrinkage rate in the TD direction was calculated according to the following formula. The heat shrinkage rate 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 heat shrinkage rate before and after the addition of the antibacterial fine particles was also measured.

[0061] <2-5. Haze> The haze of Examples 1 and 2 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.

[0062] <2-6. Glossiness> The gloss at an incident angle of 45° was measured for Examples 1, 2 and the Comparative Example using a VG-2000 model manufactured by Nippon Denshoku Industries Co., Ltd. according to a method conforming to JIS Z8741.

[0063] <2-7.Surface roughness> Examples 1 and 2 and the comparative example were set in a Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd., and Ra, Ramax, and Rz were measured in accordance with the ISO13565-1 standard. The measurement conditions were as follows. Cutoff: 0.8mm Measurement probe drive speed: 0.3mm / sec Measurement length: 20.0mm Measurement magnification: Vertical magnification x 10,000, Horizontal magnification x 5

[0064] <2-8. Evaluation Results> The evaluation results are as follows: [Table 3]

[0065] According to the above results, both Examples 1 and 2 contain antibacterial microparticles, and therefore exhibit antibacterial performance. Since it is considered sufficient to obtain a rating of 2.0 or higher in the antibacterial test, both Examples 1 and 2 have sufficient antibacterial performance. Note that the comparative example does not contain antibacterial microparticles, and therefore does not exhibit antibacterial performance.

[0066] The lower the blocking test result, the higher the anti-blocking performance. In Examples 1 and 2 and the Comparative Example, the intermediate layers all contain an anti-blocking agent, and therefore have sufficient anti-blocking performance. In particular, in Examples 1 and 2, the first intermediate layer contains antibacterial particles in addition to the anti-blocking agent, and therefore the anti-blocking performance, particularly "outside outside," is higher than in the Comparative Example. Therefore, it can be seen that the antibacterial particles also contribute to the anti-blocking performance.

[0067] This point can also be considered from the evaluation of surface roughness, for example. That is, Example 2 uses antibacterial fine particles with a larger particle size than Example 1, and the content is also larger, so the surface roughness is larger than that of Example 1 and the comparative example.

[0068] Comparing Examples 1 and 2, Example 1 uses antibacterial fine particles with smaller particle diameters and a lower content than Example 2, resulting in smaller haze. For the same reason, the gloss is also higher.

[0069] The heat shrinkage rate of Examples 1 and 2 was ±5% (amount of change in heat shrinkage rate) compared to the comparative example not containing antibacterial fine particles. This heat shrinkage rate is highly sufficient for practical use.

[0070] From the above, Examples 1 and 2 can be used as heat-shrinkable multilayer films having antibacterial properties and antiblocking properties. [Explanation of symbols]

[0071] 1 Base material 2. Middle Tier 3 Overcoat layer 4 Antibacterial particles

Claims

1. A substrate having a first surface and a second surface and containing a thermoplastic resin; an intermediate layer containing a thermoplastic resin and having antibacterial fine particles dispersed therein, the intermediate layer being laminated on at least one of the first surface and the second surface of the substrate; a resin overcoat layer laminated on the intermediate layer to protect the intermediate layer; Equipped with A heat shrinkable multilayer film, wherein at least a portion of the antimicrobial microparticles are exposed through the overcoat layer.

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

3. The heat shrinkable multilayer film according to claim 2 , wherein the mode particle size of the antibacterial fine particles is greater than a thickness of the overcoat layer.

4. The heat-shrinkable multilayer film according to claim 1 , wherein the substrate and the intermediate layer contain a styrene-based resin.

5. The heat-shrinkable multilayer film according to claim 1 , wherein the overcoat layer contains an acrylic resin.

6. 6. The heat shrinkable multilayer film according to claim 1, wherein the intermediate layer further contains antiblocking fine particles.

7. a substrate having a first surface and a second surface and containing a thermoplastic resin in which antibacterial fine particles are dispersed; a resin overcoat layer laminated on at least one of the first surface and the second surface of the substrate to protect the substrate; Equipped with A heat shrinkable multilayer film, wherein at least a portion of the antimicrobial microparticles are exposed through the overcoat layer.

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