Release film

Abstract

To provide a release film which is excellent in releasability without using a release agent such as a silicone resin when used as process paper and release paper during manufacture of an adhesive tape, a double-sided tape and rubber or used as interleaving paper for protecting an adhesive surface.SOLUTION: A release film is formed from a thermoplastic resin, in which the thermoplastic resin contains a biomass material, a content ratio of the biomass material is 5 mass% or more with respect to a mass of the thermoplastic resin containing the biomass material, an acrylic tape is stuck to the release film, and the release strength when the acrylic tape is released from the release film is 1.5 N / 25 mm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present technology relates to a release film. [Background technology]

[0002] Release films are used as process paper or peeling paper to cover adhesive surfaces coated with adhesives of tapes to prevent them from sticking together during the production of adhesive tapes or double-sided tapes. Release films are also used as process paper to sandwich rubber or plastics during the molding of rubber or plastic sheets, preventing contact between rubbers or plastics. Furthermore, release films are also used in the electronic component field as protective sheets (so-called interleaving paper) for surfaces coated with adhesives or adhesives.

[0003] Conventionally, such release films have been produced by applying a release agent such as silicone resin to the surface of a film such as paper or resin. In addition, release agents such as silicone resin are relatively expensive, so in applications where it is difficult to use these release agents from a cost perspective, release films that have been embossed (Patent Document 1) or sand matted to impart irregularities to the surface have been used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-90631 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although silicone resins and the like have a strong release effect, the silicone components tend to migrate to the object to be protected, and when used as a release film in the electronic parts field, the migrated silicone components may cause poor conduction. Also, the surface roughness imparted by embossing has the problem of poor appearance. The purpose of this technology is to provide a release film that has excellent releasability without using a release agent such as silicone resin when used as process paper or release paper in the production of adhesive tape, double-sided tape, or rubber, or when used as interleaving paper to protect adhesive surfaces. [Means for solving the problem]

[0006] This technology is A release film formed from a thermoplastic resin, the thermoplastic resin comprises a biomass material; The content of the biomass material is 5% by mass or more relative to the mass of the thermoplastic resin containing the biomass material, and An acrylic tape is attached to the release film, and the peel strength when the acrylic tape is peeled from the release film is 1.5 N / 25 mm or less. The release film is provided. The biomass material can be a starch material. The content of the starch material may be 5% by mass or more and 60% by mass or less relative to the mass of the thermoplastic resin containing the starch material. The starch material may be potato starch. The biomass material may be a cellulosic material. The content of the cellulose material may be 5% by mass or more and 45% by mass or less. The thermoplastic resin may be a polyethylene resin. The surface roughness (Ry) on at least one surface may be 7 μm or more. The present technology provides the release film, which is a release paper used in an adhesive tape. The present technology provides a release film in which a resin layer is laminated on at least one surface of the release film. The resin layer may be formed from a thermoplastic resin. The release film may have a surface roughness (Ry) of 7 μm or more on at least one surface. [Effects of the Invention]

[0007] This technology makes it possible to provide a release film that, when used as process paper, release paper, or interleaf paper, has excellent releasability from target materials such as adhesive tape, double-sided tape, and rubber, without using a release agent such as silicone resin. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a graph showing the relationship between the blending ratio of biomass materials (corn starch, cellulose) and peel strength in a release film according to a first embodiment of the present technology. [Figure 2] 1 is a graph showing the relationship between the blending ratio of biomass materials (corn starch, cellulose) and the surface roughness in the MD direction in a release film according to a first embodiment of the present technology. [Figure 3] 1 is a graph showing the relationship between the blending ratio of biomass materials (corn starch, cellulose) and the surface roughness in the TD direction in a release film according to a first embodiment of the present technology. [Figure 4] 1 is a graph showing the correlation between peel strength and surface roughness in a biomass material (corn starch)-containing release film according to the first embodiment of the present technology. [Figure 5] 1 is a graph showing the correlation between peel strength and surface roughness in a biomass material (cellulose)-containing release film according to a first embodiment of the present technology. [Figure 6] 1 is a cross-sectional view schematically showing a release film according to a first embodiment of the present technology. [Figure 7] FIG. 3 is a cross-sectional view schematically showing a release film according to a second embodiment of the present technology. [Figure 8] 1 is a graph showing the relationship between the blending ratio of a biomass material (potato starch) and peel strength in a release film according to a first embodiment of the present technology. [Figure 9] 1 is a graph showing the relationship between the blending ratio of biomass material (potato starch) and the surface roughness Ry value in the MD direction in a release film according to a first embodiment of the present technology. [Figure 10] 1 is a graph showing the relationship between the blending ratio of biomass material (potato starch) and the surface roughness Ry value in the TD direction in a release film according to a first embodiment of the present technology. [Figure 11] 1 is a graph showing the correlation between peel strength and surface roughness in a release film containing a biomass material (potato starch) according to the first embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments for carrying out the present technology will be described below. Note that the embodiments described below are representative embodiments of the present technology, and the scope of the present technology is not limited to these embodiments.

[0010] This technology will be described in the following order. 1. First embodiment (example of single-layer release film) (1) Release film composition (2) Physical properties (3) Method of manufacturing release film 2. Second embodiment (example of multilayer release film) (1) Release film composition (2) Physical properties (3) Method of manufacturing release film 3. Uses of release film 4. Working Example

[0011] 1. First embodiment (example of single-layer release film)

[0012] (1) Release film composition The release film according to this embodiment is formed from a thermoplastic resin. That is, the release film according to this embodiment is a film formed from a thermoplastic resin. Furthermore, the thermoplastic resin contains a biomass material. To explain in more detail, as shown in FIG. 6, the release film 10 according to this embodiment is a release film having a single-layer structure having a biomass material-containing thermoplastic resin layer 11 formed from a thermoplastic resin containing a biomass material (hereinafter referred to as a biomass material-containing thermoplastic resin).

[0013] The thermoplastic resin forming the release film according to the present embodiment may be an olefin resin, a polyester resin, or a mixture of these resins. The thermoplastic resin may be a polystyrene resin.

[0014] Olefin-based resins are polymers obtained by polymerization of olefins (e.g., α-olefins) as the main monomers. The olefin-based resins may be, for example, polyethylene (PE) resins, polypropylene (PP) resins, or a combination thereof.

[0015] The polyethylene resin may be, for example, a low-density polyethylene resin (LDPE: Low Density Polyethylene), a high-density polyethylene resin (HDPE: High Density Polyethylene), a very low-density polyethylene resin (VLDPE: Very Low Density Polyethylene), a linear low-density polyethylene resin (LLDPE: Linear Low Density Polyethylene), an ethylene-vinyl acetate copolymer (EVA resin), or an ethylene copolymer, or an ultra-high molecular weight polyethylene resin (UHMW-PE: Ultra High Molecular Weight Polyethylene), or a combination thereof.

[0016] The polypropylene resin may be, for example, a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (such as an ethylene-propylene copolymer), or a combination thereof.

[0017] The olefin resin may preferably be a biomass-derived polyolefin resin (e.g., a biomass-derived polyethylene resin), such as a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0018] The olefin resin may be a metallocene-catalyzed olefin resin, i.e., the thermoplastic resin may be, for example, a metallocene-catalyzed polyethylene resin or polypropylene resin, or a combination thereof. The polystyrene-based resin may be a metallocene-catalyzed polystyrene-based resin.

[0019] The polyester resin is a polymer formed by polymerizing monomers via ester bonds. Examples of the polyester resin include polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid resin (PLA), polycarbonate resin (PC), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), and combinations of two or more of these.

[0020] Polystyrene-based resins are polymers formed by polymerization of styrene-based monomers. Examples of the polystyrene-based resin include polystyrene resin, rubber-reinforced polystyrene resin (high impact polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylate ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, and acrylonitrile-ethylene-propylene-styrene copolymer, or a combination of two or more of these.

[0021] In the present embodiment, the type of thermoplastic resin may be appropriately selected by a person skilled in the art depending on, for example, the application of the release film formed from the thermoplastic resin, and a thermoplastic resin having a low processing temperature is preferred. For example, in the case of a release film used as a release interleaf for an adhesive tape, the thermoplastic resin may be, for example, preferably an olefin resin, more preferably a polyethylene resin or a polypropylene resin, and even more preferably LLDPE or LDPE.

[0022] In this embodiment, the thermoplastic resin preferably has a melting point of 90° C. to 180° C., and more preferably has a melting point of 95° C. to 170° C. By using a thermoplastic resin with a lower melting point, the molding temperature can be lowered.

[0023] The release film according to this embodiment is a film. Examples of such a film include a non-stretched film, a uniaxially stretched film, and a biaxially stretched film.

[0024] In the release film according to this embodiment, the thermoplastic resin contains a biomass material. The biomass material is preferably a plant-derived biomass material, more specifically, a starch material and a cellulose material. The starch material and the cellulose material may be classified as waste biomass, unused biomass, or resource grain.

[0025] Examples of starch materials include starch from underground sources and starch from aboveground sources. Underground starch is starch accumulated underground, such as in rhizomes or roots. Examples of underground starches include, but are not limited to, tapioca starch (cassava starch), potato starch, sweet potato starch, arrowroot starch, and bracken starch.

[0026] Terrestrial starch refers to starch accumulated above ground, for example, starch accumulated in seeds, etc. Examples of terrestrial starches include, but are not limited to, corn starch, wheat starch, sago starch, acorn starch, and rice starch.

[0027] In this embodiment, preferably, underground starch is used. By producing the release film of this embodiment using underground starch, the releasability of the release film can be further improved.

[0028] The starch material may be a modified starch (i.e., modified starch), particularly a modified starch derived from a starch-based starch. Examples of such modified starches include physically modified starch (which is physically modified) and chemically modified starch (which is chemically modified). Examples of physically modified starches include pregelatinized starch and heat-moisture starch. Examples of chemically modified starches include acetoacetate-esterified starch, acetate-esterified starch, hydroxymethyl-etherified starch, hydroxypropyl-etherified starch, carboxymethyl-etherified starch, allyl-etherified starch, methyl-etherified starch, succinate-esterified starch, xanthogen acetate-esterified starch, nitrate-esterified starch, urea phosphate-esterified starch, phosphate-esterified starch, phosphate-crosslinked starch, formaldehyde-crosslinked starch, acrolein-crosslinked starch, and epichlorohydrin-crosslinked starch.

[0029] When the starch material is corn starch, the particle size is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of improving peelability. The upper limit of the particle size is not particularly limited, but is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0030] When the starch material is tapioca starch, the particle size is preferably 2 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of improving peelability. The upper limit of the particle size is not particularly limited, but is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less.

[0031] When the starch material is potato starch, the particle size is preferably 2 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, from the viewpoint of improving peelability. The upper limit of the particle size is not particularly limited, but is preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less.

[0032] The starch material may preferably contain equilibrium moisture, which may be, for example, preferably 10% to 15% by mass, more preferably 10% to 14% by mass, even more preferably 10% to 13% by mass, and even more preferably 11% to 13% by mass, relative to the mass of the starch material.

[0033] In this embodiment, the content of the starch material is 5% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin). The content of the starch material is preferably 60% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin). The content of the starch material is preferably 5% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 45% by mass or less, even more preferably 20% by mass or more and 40% by mass or less, and even more preferably 25% by mass or more and 35% by mass or less, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin).

[0034] Cellulosic materials can include paper, paper pulp, cotton, or ground fabric.

[0035] The particle size D50 (median diameter) of the cellulose material may be, for example, 15 μm to 150 μm, and particularly preferably 20 μm to 100 μm. The particle size D50 is determined by wet measurement using a laser diffraction particle size analyzer (SALD-3100, Shimadzu Corporation). Having the cellulose material have a particle size within the above numerical range can contribute to improving the dispersibility of the cellulose material contained in the thermoplastic resin.

[0036] According to this embodiment, the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm accounts for 65% to 100%, preferably 70% to 100%, more preferably 80% to 100%, and even more preferably 85% to 100% of the total number of cellulose fibers constituting the cellulose material. The above percentage of the number of cellulose fibers is calculated by determining the percentage of the number of cellulose fibers having a particle size of 0 μm to 9.8 μm (hereinafter referred to as the "first percentage") and the percentage of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (hereinafter referred to as the "second percentage") among the total number of cellulose fibers in the cellulose material by wet measurement using the laser diffraction particle size analyzer, and then subtracting the first percentage from the second percentage. The numerical ranges "0 μm to 9.8 μm" and "0 μm to 110.6 μm" are both numerical ranges input to the laser diffraction particle size analyzer during the wet measurement. In this embodiment, it is particularly preferred that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm account for 0% to 30%, preferably 0% to 25%, more preferably 0% to 20%, and even more preferably 0% to 15% of the total number of cellulose fibers constituting the cellulose material. The percentage of the number of cellulose fibers is calculated by determining the percentage of the number of cellulose fibers having a particle size of 0 μm to 110.6 μm (the "second percentage") and the percentage of the number of cellulose fibers having a particle size of 0 μm to 998.4 μm (hereinafter referred to as the "third percentage") among the total number of cellulose fibers in the cellulose material by wet measurement using the laser diffraction particle size analyzer, and then subtracting the second percentage from the third percentage. The numerical ranges "0 μm to 110.6 μm" and "0 μm to 998.4 μm" are both numerical ranges input to the laser diffraction particle size analyzer during the wet measurement. A cellulose material having the above particle size distribution can be produced, for example, by treating pulp with a chemical such as an acid. An example of a cellulose material having the above particle size distribution is KC Flock W400 (Nippon Paper Industries Co., Ltd.). The use of cellulose powder having the above particle size distribution provides better moldability when producing a release film. In particular, by having the number of cellulose fibers having a particle size of 9.8 μm to 110.6 μm account for 80% to 100%, and even more preferably 85% to 100%, of the total number of cellulose fibers constituting the cellulose powder, tears or the occurrence of holes in the release film obtained by molding the thermoplastic resin can be prevented.To prevent tears or the occurrence of holes in the release film, it is particularly preferable that the number of cellulose fibers having a particle size of 110.6 μm to 998.4 μm account for 0% to 20%, and even more preferably 0% to 15%, of the total number of cellulose fibers constituting the cellulose powder.

[0037] According to another preferred embodiment of the present invention, the cellulose powder may have a particle size in which 90% or more pass through a 100 mesh. In this embodiment, more preferably, the cellulose powder has a particle size in which 90% or more pass through a 100 mesh, and the apparent specific gravity of the cellulose powder may be 0.30 g / ml to 0.40 g / ml.

[0038] The particle size is measured by the standard sieve method, specifically as follows: 10 g of sample is placed on a 100-mesh standard sieve, a tray and a lid are attached to the standard sieve, and the sample is shaken for 40 minutes in a low-tap shaker. The particle size is then calculated from the sample mass (10 g) and the mass of the residue on the sieve using the following formula: Particle size (%) = [(sample mass (g) - sieve residue (g)) / sample mass (g)] × 100

[0039] The apparent specific gravity is measured as follows. That is, 10 g of sample is accurately weighed on a balance and placed in a 50 ml measuring cylinder. The bottom of the measuring cylinder is placed on a rubber sheet-covered table and tapped, taking care not to scatter the sample. This tapping operation is continued until the sample no longer clogs the cylinder. After this tapping operation, the surface of the sample is flattened and the scale (volume, ml) is read. The apparent specific gravity is then calculated using the following formula: Apparent specific gravity (g / ml) = sample (10g) / volume (ml)

[0040] The cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity) can be produced, for example, by mechanically pulverizing pulp (for example, jet mill pulverization). An example of the cellulose powder having the above particle size (or the above particle size and the above apparent specific gravity) is KC Floc 100GK.

[0041] In this embodiment, the content of the cellulose material is 5% by mass or more, preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin). The content of the cellulose material is preferably 45% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin). The content of the cellulose material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 35% by mass or less, even more preferably 10% by mass or more and 30% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin).

[0042] The thermoplastic resin containing the biomass material (biomass material-containing thermoplastic resin) may further contain other components, such as a compatibilizer and a colorant.

[0043] The compatibilizer can be used to more uniformly disperse the biomass material in the biomass-containing thermoplastic resin. The compatibilizer may be selected depending on the type of the biomass-containing thermoplastic resin. Examples of the compatibilizer include acid-modified polyolefin, acid-modified nylon, acid-modified polystyrene, acid-modified EVA, acid-modified ethylene copolymer, acid-modified acrylate, acrylic acid-modified EVA, and modified ethylene acrylate.

[0044] When the thermoplastic resin is a polyolefin-based resin, the compatibilizer is preferably an acid-modified polyolefin, and in particular may be a carboxylic acid anhydride-modified polyolefin or an olefin-based comonomer. The carboxylic acid anhydride constituting the carboxylic acid anhydride-modified polyolefin may preferably be maleic anhydride. The compatibilizer may be, for example, a maleic anhydride-grafted polyolefin resin, more particularly, one or a combination of two or more selected from the group consisting of maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene-propylene copolymer. A rubber component may be dispersed in the compatibilizer. The compatibilizer can be contained in the biomass material-containing thermoplastic resin in a content ratio of, for example, 0.1 to 10 parts by mass, more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of the biomass material-containing thermoplastic resin.

[0045] The colorant can be used to impart color to the biomass material-containing thermoplastic resin, and examples of the colorant include titanium oxide, carbon black, dyes, and pigments.

[0046] Furthermore, the other components may include, for example, antioxidants and impact-resistant additives. As the antioxidants and impact-resistant additives, various commercially available antioxidants and impact-resistant additives may be used.

[0047] (2) Physical properties When the biomass material is a starch material, the release film according to this embodiment has a peel strength of 1.5 N / 25 mm or less, preferably 1.2 N / 25 mm or less, more preferably 1.0 N / 25 mm or less, and even more preferably 0.8 N / 25 mm or less when the acrylic tape is attached to the release film and then peeled from the release film. The lower limit of the peel strength in this case is not particularly limited, but is preferably 0.35 N / 25 mm or more, more preferably 0.50 N / 25 mm or more, and even more preferably 0.60 N / 25 mm or more. For example, when the starch material is corn starch, the peel strength when an acrylic tape is attached to a release film and then peeled from the release film is 1.5 N / 25 mm or less, preferably 1.2 N / 25 mm or less, more preferably 1.0 N / 25 mm or less, and even more preferably 0.8 N / 25 mm or less. The lower limit of the peel strength in this case is not particularly limited, but is preferably 0.35 N / 25 mm or more, more preferably 0.50 N / 25 mm or more, and even more preferably 0.60 N / 25 mm or more. Furthermore, for example, when the starch material is potato starch, the peel strength when an acrylic tape is attached to a release film and then peeled from the release film is 1.5 N / 25 mm or less, preferably 1.1 N / 25 mm or less, more preferably 0.7 N / 25 mm or less, and even more preferably 0.3 N / 25 mm or less. The lower limit of the peel strength in this case is not particularly limited, but is preferably 0.03 N / 25 mm or more, more preferably 0.1 N / 25 mm or more, and even more preferably 0.2 N / 25 mm or more. In the case where the biomass material is a cellulose material, the release film according to this embodiment has a peel strength of 1.5 N / 25 mm or less, preferably 1.2 N / 25 mm or less, more preferably 0.9 N / 25 mm or less, and even more preferably 0.6 N / 25 mm or less when an acrylic tape is attached to the release film and the acrylic tape is peeled from the release film. The lower limit of the peel strength in this case is not particularly limited, but is preferably 0.03 N / 25 mm or more, more preferably 0.10 N / 25 mm or more, and even more preferably 0.20 N / 25 mm or more. Peel strength can be measured, for example, in accordance with JIS Z 0237:2000 "Test Method for Adhesive Tapes and Sheets." For example, Nitto Denko's acrylic tape "No. 31B" (tape width 25 mm) can be used as a release agent. The smaller the peel strength, the easier it is to peel, indicating excellent releasability.

[0048] In the release film according to this embodiment, at least one surface is roughened by the formation of projections and depressions caused by the biomass material contained in the thermoplastic resin.

[0049] In the release film according to this embodiment, when the biomass material is a starch material, from the viewpoint of obtaining good releasability, the surface roughness (maximum height Ry) in the MD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. Also, the surface roughness (maximum height Ry) in the TD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. For example, when the starch material is corn starch, the surface roughness (maximum height Ry) in the MD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. Also, the surface roughness (maximum height Ry) in the TD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. For example, when the starch material is potato starch, the surface roughness (maximum height Ry) in the MD direction on at least one surface is preferably 10 μm or more, more preferably 25 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more. The surface roughness (maximum height Ry) in the TD direction on at least one surface is preferably 15 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more.

[0050] Furthermore, in the release film according to this embodiment, when the biomass material is a cellulose material, from the viewpoint of obtaining good releasability, the surface roughness (maximum height Ry) in the MD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and even more preferably 30 μm or more. The surface roughness (maximum height Ry) in the TD direction on at least one surface is preferably 7 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and even more preferably 30 μm or more.

[0051] The surface roughness (maximum height Ry) of the release film according to this embodiment may be calculated, for example, in accordance with JIS B0031.

[0052] When the biomass material of the release film according to this embodiment is a starch material, from the viewpoint of obtaining good releasability, the surface roughness (arithmetic mean roughness Ra) in the MD on at least one surface is preferably 1.0 μm or more, more preferably 2.0 μm or more, even more preferably 2.5 μm or more, and even more preferably 4.0 μm or more. Also, the surface roughness (arithmetic mean roughness Ra) in the TD on at least one surface is preferably 2.0 μm or more, more preferably 3.0 μm or more, even more preferably 3.5 μm or more, and even more preferably 4.0 μm or more.

[0053] Furthermore, in the release film according to this embodiment, when the biomass material is a cellulose material, from the viewpoint of obtaining good releasability, the surface roughness (arithmetic mean roughness Ra) in the MD direction on at least one surface is preferably 2.5 μm or more, more preferably 3.5 μm or more, even more preferably 4.5 μm or more, and even more preferably 5.5 μm or more. Furthermore, the surface roughness (arithmetic mean roughness Ra) in the TD direction on at least one surface is preferably 3.0 μm or more, more preferably 3.5 μm or more, even more preferably 4.5 μm or more, and even more preferably 5.0 μm or more.

[0054] The surface roughness (arithmetic mean roughness Ra) of the release film according to this embodiment may be calculated in accordance with, for example, JIS B0031.

[0055] Furthermore, in the release film according to this embodiment, when the biomass material is a starch material, from the viewpoint of obtaining good releasability, the surface roughness (ten-point average roughness Rz) in the MD direction on at least one surface is preferably 5.0 μm or more, more preferably 10.0 μm or more, even more preferably 15.0 μm or more, and even more preferably 25.0 μm or more. Also, the surface roughness (ten-point average roughness Rz) in the TD direction on at least one surface is preferably 10.0 μm or more, more preferably 15.0 μm or more, even more preferably 17.0 μm or more, and even more preferably 25.0 μm or more.

[0056] Furthermore, in the release film according to this embodiment, when the biomass material is a cellulose material, from the viewpoint of obtaining good releasability, the surface roughness (ten-point average roughness Rz) in the MD direction on at least one surface is preferably 10.0 μm or more, more preferably 15.0 μm or more, even more preferably 20.0 μm or more, and even more preferably 25.0 μm or more. Furthermore, the surface roughness (ten-point average roughness Rz) in the TD direction on at least one surface is preferably 12.0 μm or more, more preferably 15.0 μm or more, even more preferably 20.0 μm or more, and even more preferably 25.0 μm or more.

[0057] The surface roughness (arithmetic mean roughness Rz) of the release film according to this embodiment may be calculated in accordance with, for example, JIS B0031.

[0058] The total thickness t of the release film according to this embodiment is preferably 10 μm to 150 μm, more preferably 15 μm to 100 μm, even more preferably 20 μm to 50 μm, and even more preferably 25 μm to 35 μm.

[0059] (3) Method of manufacturing release film The method for producing a release film according to this embodiment can employ a method for producing a typical petroleum-based plastic film. For example, the method for producing a release film according to this embodiment may include a kneading step in which raw materials such as a biomass material and a thermoplastic resin are mixed, and the mixed raw materials are heated and kneaded. The kneaded product obtained in this kneading step is a thermoplastic resin containing a biomass material (biomass material-containing thermoplastic resin composition). The production method may further include a molding step in which the biomass material-containing thermoplastic resin obtained in the kneading step is molded. The kneading step and the molding step will be described below.

[0060] (i) Mixing process

[0061] In the kneading step, for example, raw materials such as a biomass material and a thermoplastic resin may first be mixed. After mixing, the mixed raw materials may be heated and kneaded. In the kneading step, the materials may be heated to a temperature at which the thermoplastic resin can melt. This temperature may be appropriately selected by those skilled in the art depending on the melting point of the thermoplastic resin used. The kneading step may be performed, for example, at a temperature preferably between 100 and 250°C, more preferably between 115 and 230°C, and even more preferably between 120 and 210°C.

[0062] The mixing of raw materials such as the biomass material and the thermoplastic resin may be carried out using a mixer such as a high-temperature agitator, a Henschel mixer, a tumbler mixer, a Barbary mixer, or a kneader mixer. The mixed raw materials may be heated and kneaded using, for example, a single-screw kneading extruder or a twin-screw kneading extruder. These kneading extruders may be devices known in the art. Preferably, the kneading step includes at least a heating and kneading treatment using a twin-screw kneading extruder. As the twin-screw kneading extruder, a co-rotating twin-screw kneading extruder or a counter-rotating twin-screw kneading extruder may be used. By performing the kneading treatment using a twin-screw kneading extruder, it is possible to obtain a biomass material-containing thermoplastic resin in which the biomass material is more uniformly dispersed.

[0063] The biomass material-containing thermoplastic resin (kneaded product) obtained in the kneading step may be directly subjected to the molding step without being pelletized. This allows the pelletizing step to be omitted. The biomass material-containing thermoplastic resin (kneaded product) obtained in the kneading step may be pelletized. The pelletized biomass material-containing thermoplastic resin may be subjected to the molding step.

[0064] (ii) Molding process

[0065] In the molding step, the biomass material-containing thermoplastic resin produced in the kneading step is molded.

[0066] In the molding step, the biomass material-containing thermoplastic resin can be molded into a release film. The biomass material-containing thermoplastic resin can be molded by inflation molding, T-die molding, or calendar molding. To produce the release film, inflation molding is preferably used. The inflation molding can be performed using, for example, a ring die. In the molding process, for example, the biomass material-containing thermoplastic resin may be extruded directly through a die without being pelletized, or the pelletized biomass material-containing thermoplastic resin may be melted and then extruded through a die. The molding temperature may be appropriately selected by those skilled in the art depending on the type of biomass material-containing thermoplastic resin. For example, when the biomass material-containing thermoplastic resin is polyethylene, the temperature may be, for example, 160°C to 185°C. When the biomass material-containing thermoplastic resin is polypropylene, the temperature may be, for example, 160°C to 185°C.

[0067] 2. Second embodiment (example of multilayer release film)

[0068] (1) Release film composition A release film according to a second embodiment of the present technology has a resin layer laminated on at least one surface of the release film according to the first embodiment. That is, the resin layer may be laminated on only one surface of the release film, or the resin layer may be laminated on both surfaces of the release film. An example of a release film according to this embodiment is shown in Figure 7. As shown in Figure 7, a release film 20 according to this embodiment is composed of a biomass material-containing thermoplastic resin layer 21 containing a biomass material, which is the release film according to the first embodiment, a resin layer 22, and a resin layer 23. That is, in the release film 20 according to this embodiment, the biomass material-containing thermoplastic resin layer 21 containing a biomass material is configured as a middle layer, a resin layer 22 is laminated on one surface of the biomass material-containing thermoplastic resin layer 21 as an inner layer, and a resin layer 23 is laminated on the other surface of the biomass material-containing thermoplastic resin layer 21 as an outer layer. As shown in Figure 7, in the resin layer 22 laminated as an inner layer, the surface opposite to the side that contacts the biomass material-containing thermoplastic resin layer 21 is roughened by the biomass material contained in the thermoplastic resin layer 21 that constitutes the middle layer, resulting in a rough surface that comes into contact with an object to be protected, such as the adhesive surface of an adhesive tape. In this way, by laminating the resin layer 22 on at least one surface of the biomass material-containing thermoplastic resin layer 21, which is the release film of the first embodiment, for example, when the release film is used as a release paper for an adhesive tape, which is the object to be protected, the adhesive surface of the adhesive tape and the rough surface of the resin layer 22 are bonded together, and when the adhesive surface of the adhesive tape and the rough surface of the resin layer 22 are peeled off, the biomass material contained in the biomass material-containing thermoplastic resin layer 21 can be prevented from being transferred to the adhesive surface of the adhesive tape.

[0069] The biomass material-containing thermoplastic resin layer 21 constituting the middle layer may contain the thermoplastic resin that forms the release film according to the first embodiment. The description of the thermoplastic resin in the first embodiment applies to the thermoplastic resin that forms the biomass material-containing thermoplastic resin layer 21, so a description of the thermoplastic resin will be omitted. The biomass material-containing thermoplastic resin layer 21 contains a biomass material. The description of the type of biomass material contained in the biomass material-containing thermoplastic resin applies to the type of biomass material, so a description of the type of biomass material will be omitted.

[0070] In this embodiment, the content of the starch material is 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 35% by mass or more, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin). The content of the starch material is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin). The content of the starch material is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 55% by mass or less, even more preferably 20% by mass or more and 50% by mass or less, and even more preferably 35% by mass or more and 45% by mass or less, based on the mass of the thermoplastic resin containing the starch material (starch material-containing thermoplastic resin).

[0071] In this embodiment, the content of the cellulose material is 5% by mass or more, preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin). The content of the cellulose material is preferably 45% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin). The content of the cellulose material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 35% by mass or less, even more preferably 10% by mass or more and 30% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less, based on the mass of the thermoplastic resin containing the cellulose material (cellulose-containing thermoplastic resin).

[0072] In this embodiment, the resin layer 22 constituting the inner layer is formed from a resin. The resin forming the resin layer 22 may be a thermoplastic resin. Such a thermoplastic resin may be an olefin-based resin, a polyester-based resin, or a mixture of these resins. The thermoplastic resin may be a polystyrene-based resin. The resin forming the resin layer 22 may be of a different type from or the same type as the thermoplastic resin forming the biomass material-containing thermoplastic resin layer 21 constituting the middle layer. The resin layer 22 may be formed from a single resin or may be formed from multiple resins of different types, and is preferably formed from a single resin.

[0073] The olefin resin may preferably be a polyethylene (PE) resin or a polypropylene (PP) resin, or a combination thereof.

[0074] The polyethylene resin may preferably be a low density polyethylene resin (LDPE: Low Density Polyethylene), a high density polyethylene resin (HDPE: High Density Polyethylene), a very low density polyethylene resin (VLDPE: Very Low Density Polyethylene), a linear low density polyethylene resin (LLDPE: Linear Low Density Polyethylene), an ethylene-vinyl acetate copolymer (EVA resin), or an ultra high molecular weight polyethylene resin (UHMW-PE: Ultra High Molecular Weight Polyethylene), or a combination thereof.

[0075] The polypropylene resin may preferably be a homopolymer polypropylene resin, or a random copolymer or block copolymer polypropylene resin (such as an ethylene-propylene copolymer), or a combination thereof.

[0076] The olefin resin may preferably be a biomass-derived polyolefin resin (e.g., a biomass-derived polyethylene resin), such as a biomass polyethylene resin. The biomass polyethylene resin may be, for example, LDPE, LLDPE, or HDPE. This can reduce CO2 emissions.

[0077] The olefin resin may be a metallocene-catalyzed olefin resin, i.e., the olefin resin may be a metallocene-catalyzed polyethylene resin or polypropylene resin, or a combination thereof. The polystyrene-based resin may be a metallocene-catalyzed polystyrene-based resin.

[0078] The polyester resin may be, for example, polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid resin (PLA), polycarbonate resin (PC), polybutylene adipate terephthalate resin (PBAT), polybutylene succinate resin (PBS), polyhydroxyalkanoate resin (PHA), or a combination of two or more of these.

[0079] The polystyrene resin may be, for example, polystyrene resin, rubber-reinforced polystyrene resin (high impact polystyrene resin, HIPS), acrylonitrile-styrene copolymer (AS resin), methacrylate ester-styrene copolymer, acrylonitrile-acrylic rubber-styrene copolymer, acrylonitrile-ethylene propylene-styrene copolymer, or a combination of two or more of these.

[0080] In this embodiment, the resin layer 23 constituting the outer layer is made of a resin. The description of the resin layer 22 applies to the type of resin that forms the resin layer 23, so a description of the type of resin that forms the resin layer 23 will be omitted. The resin that forms the resin layer 23 may be the same type as the resin that forms the resin layer 22 that forms the inner layer, or may be a different type. Preferably, the resin that forms the resin layer 23 is a different type from the resin that forms the resin layer 22. Furthermore, the resin layer 23 may be made of multiple types of resin.

[0081] (2) Physical properties All of the explanations regarding the peel strength and surface roughness (Ry, Ra, Rz) of the physical properties described in 1.(2) above also apply to the second embodiment. Therefore, the peel strength and surface roughness (Ry, Ra, Rz) may be the same as those in the first embodiment. Therefore, the explanation of the peel strength and surface roughness (Ry, Ra, Rz) of the release film according to the second embodiment will be omitted.

[0082] In the second embodiment, the thickness of each of the resin layers 22 and 23 further laminated on the biomass material-containing thermoplastic resin layer 21 of the release film is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm, and even more preferably 5 μm to 10 μm. By having the thickness within this range, it is possible to prevent the biomass material contained in the biomass material-containing thermoplastic resin layer of the release film from being transferred to the adhesive surface of an adhesive tape or the like, and it is also possible to reduce the peel strength of the rough surface of the laminated resin layer and improve releasability. The total thickness t of the release film according to the second embodiment is preferably 10 μm to 100 μm, more preferably 20 μm to 70 μm, and even more preferably 30 μm to 40 μm, or 40 μm to 60 μm.

[0083] (3) Method of manufacturing release film The method for producing a release film according to the second embodiment can be the same as the method for producing a release film according to the first embodiment. For example, as shown in Fig. 7, a release film 20 having a three-layer structure in which a biomass material-containing thermoplastic resin layer 21 containing a biomass material is used as a middle layer, a resin layer 22 is used as an inner layer, and a resin layer 23 is used as an outer layer can be obtained by a method in which resins and thermoplastic resins corresponding to each layer are simultaneously molded by multi-layer inflation molding. The molding temperature is preferably higher than the melting point of the resin with the highest melting point among the resins forming each layer, and can be, for example, 160°C to 185°C. Alternatively, the layers may be molded and then bonded together, or a layer may be cast onto a previously molded layer, either singly or in combination. The method for producing the biomass-containing thermoplastic resin that forms the middle layer of biomass material-containing thermoplastic resin 21 is the same as the method for producing the biomass-containing thermoplastic resin described in 1.(3) above, and therefore will not be described here.

[0084] 3. Uses of release film

[0085] The release film according to the present technology may be used, for example, as various types of process paper, release paper, or interleaving paper, and in particular, in the manufacturing process of adhesive tape, double-sided tape, or rubber, it may be arranged and used so as to cover the adhesive surface of the adhesive tape, double-sided tape, or rubber to be manufactured. Furthermore, the release film according to the present technology can be used, for example, as a protective film for covering the adhesive layer of an adhesive sheet (pressure-sensitive adhesive sheet) for a computer hard disk drive. Furthermore, the release film according to the present technology can be used, for example, as a release film for covering the adhesive layer of an adhesive tape used for fixing portable electronic device parts, in-vehicle electronic device parts, or the like. Furthermore, the release film according to the present technology can be used, for example, as a release film for covering the adhesive layer of an adhesive sheet used to bond optical components when manufacturing display devices such as liquid crystal displays and organic EL displays, and display input devices such as touch panels.

[0086] 4. Working Example

[0087] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples. The evaluation methods and evaluation criteria used in the examples are as follows:

[0088] (1) Peel strength The peel strength of the sample film was measured in accordance with JIS Z 0237: 2000. Specifically, the peel strength was measured under the following conditions. Equipment used: Adhesive film peeling analysis device ("VPA-2" manufactured by Kyowa Interface Science Co., Ltd.) Test temperature: Room temperature (25°C) Peeling tape used: Acrylic tape (Nitto Denko "No. 31B", width 25 mm) Peeling angle: 90 degrees Peeling speed: 300mm / min

[0089] (2) Surface roughness (Ra value, Ry value, Rz value) The surface roughness of the sample film was measured in accordance with JIS B 0031. Specifically, the surface roughness was measured under the following conditions. Equipment used: Surface roughness and shape measuring instrument (Tokyo Precision Measurement Co., Ltd. "HANDYSURF E-40A") Measured in both the MD and TD directions. Evaluation: The Ra value (arithmetic mean roughness), Ry value (maximum height), and Rz value (ten-point mean roughness) were measured, and the Ry value was used for comparison and evaluation.

[0090] <Single layer release film>

[0091] [Release film containing corn starch as a biomass material] Test Example 1: Production of release film

[0092] Example 1

[0093] 5.0% corn starch (Showa Sangyo Co., Ltd.), 94.38% linear low-density polyethylene resin (LLDPE, Prime Polymer Co., Ltd., "EVOLUE SP0540"), 0.23% zinc stearate (Daikyo Kasei Kogyo Co., Ltd.), 0.06% glycerin monostearate (Riken Vitamin Co., Ltd.), and 0.033% compatibilizer were prepared. These ingredients were blended and mixed in a high-temperature mixer. The corn starch used for blending had been dried in advance. Similar treatments were used in the following examples in which corn starch was blended.

[0094] The mixture obtained by the above mixing was fed into a twin-screw extruder (manufactured by Ikegai Corporation, "PCM30"), and the mixture was subjected to a kneading treatment.

[0095] In the kneading process, the cylinder temperature and adapter temperature of the twin-screw extruder were each set to 180°C. The screw speed of the twin-screw extruder was 100 rpm, and the feeder speed was 110 rpm. After the kneading process, the mixture was extruded through the die of the twin-screw extruder to obtain strands. The obtained strands were pelletized to obtain compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 1").

[0096] The compound pellets of the biomass material-containing thermoplastic resin of Example 1 were fed into an inflation molding machine (manufactured by Placo Corporation, die Φ65, extruder diameter 55 mm) and inflation molding was performed. In this inflation molding, the cylinder temperature and die temperature from the inflation molding machine were both set to 170°C. A film with a thickness of 50 μm was obtained by extruding the molten material from the inflation molding machine. As shown in Table 1 below, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 5%.

[0097] The peel strength of the obtained film was measured in accordance with JIS Z 0237:2000. In addition, the surface roughness (Ry value, Ra value, Rz value) of the obtained film was measured in both the MD and TD directions in accordance with JIS B 0031. The measurement results are shown in Table 2 below.

[0098] [Table 1] *1: Manufactured by Showa Sangyo Co., Ltd. *2: Prime Polymer Co., Ltd., "EVOLUE SP0540" *3: Manufactured by Daikyo Chemical Industry Co., Ltd. *4: Manufactured by Riken Vitamin Co., Ltd.

[0099] [Table 2]

[0100] Example 2

[0101] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 2") were obtained in the same manner as in Example 1, except that 10% corn starch, 88.75% linear low-density polyethylene resin, 0.47% zinc stearate, 0.12% glycerin monostearate, and 0.67% compatibilizer were mixed.

[0102] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 2 in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 10%.

[0103] In Example 2, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0104] Example 3

[0105] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 3") were obtained in the same manner as in Example 1, except that 20% corn starch, 77.50% linear low-density polyethylene resin, 0.93% zinc stearate, 0.23% glycerin monostearate, and 1.33% compatibilizer were mixed.

[0106] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 3 in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 20%.

[0107] In Example 3, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0108] Example 4

[0109] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 4") were obtained in the same manner as in Example 1, except that 30% corn starch, 66.25% linear low-density polyethylene resin, 1.40% zinc stearate, 0.35% glycerin monostearate, and 2.00% compatibilizer were mixed.

[0110] A film was obtained by performing inflation molding using the biomass material-containing thermoplastic resin of Example 4 in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 30%.

[0111] In Example 4, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0112] Example 5

[0113] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 5") were obtained in the same manner as in Example 1, except that 40% corn starch, 55.00% linear low-density polyethylene resin, 1.87% zinc stearate, 0.47% glycerin monostearate, and 2.67% compatibilizer were mixed.

[0114] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 5 in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 40%.

[0115] In Example 5, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0116] Example 6

[0117] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 6") were obtained in the same manner as in Example 1, except that 50% corn starch, 43.75% linear low-density polyethylene resin, 2.33% zinc stearate, 0.58% glycerin monostearate, and 3.33% compatibilizer were mixed.

[0118] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 6 in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 50%.

[0119] In Example 6, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0120] (Comparative Example 1)

[0121] Compound pellets of a thermoplastic resin (hereinafter also referred to as "thermoplastic resin of Comparative Example 1") were obtained in the same manner as in Example 1, except that only 100% linear low-density polyethylene resin was blended.

[0122] Using the thermoplastic resin of Comparative Example 1, a film was obtained by inflation molding in the same manner as in Example 1. As shown in Table 1 above, the corn starch content relative to the mass of the thermoplastic resin was 0%.

[0123] In Comparative Example 1, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 2 above.

[0124] [Release film containing cellulose as a biomass material] Test Example 2: Production of release film

[0125] Example 7

[0126] Cellulose (Nippon Paper Industries Co., Ltd., "KC Flock W400") 5.0%, linear low-density polyethylene resin (LLDPE, Prime Polymer Co., Ltd., "EVOLUE SP0540") 94.38%, zinc stearate (Daikyo Chemical Industry Co., Ltd.) 0.17%, glycerin monostearate (Riken Vitamin Co., Ltd.) 0.04%, and compatibilizer 0.42% were prepared. These components were blended and mixed in a high-temperature mixer. Note that the cellulose used was previously dried before blending. Similar treatments were used in the following examples in which cellulose was blended.

[0127] The mixture obtained by the above mixing was fed into a twin-screw extruder (manufactured by Ikegai Corporation, "PCM30"), and the mixture was subjected to a kneading treatment.

[0128] In the kneading process, the cylinder temperature of the twin-screw extruder was set to 120°C, and the adapter temperature was set to 130°C. The screw speed of the twin-screw extruder was 100 rpm, and the feeder speed was 110 rpm. After the kneading process, the mixture was extruded through the die of the twin-screw extruder to obtain strands. The obtained strands were pelletized to obtain compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 7").

[0129] A film having a thickness of 50 μm was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 7 in the same manner as in Example 1. As shown in Table 3 below, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 5.0%.

[0130] In Example 7, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 4 below.

[0131] [Table 3] *5: "KC Flock W400" manufactured by Nippon Paper Industries Co., Ltd.

[0132] [Table 4]

[0133] Example 8

[0134] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 8") were obtained in the same manner as in Example 1, except that 10.0% cellulose, 88.75% linear low-density polyethylene resin, 0.33% zinc stearate, 0.08% glycerin monostearate, and 0.83% compatibilizer were mixed.

[0135] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 8 in the same manner as in Example 1. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 10%.

[0136] In Example 8, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 4 above.

[0137] Example 9

[0138] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 9") were obtained in the same manner as in Example 1, except that 20.0% cellulose, 77.50% linear low-density polyethylene resin, 0.67% zinc stearate, 0.17% glycerin monostearate, and 1.67% compatibilizer were mixed.

[0139] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 9 in the same manner as in Example 1. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 20%.

[0140] In Example 9, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 4 above.

[0141] Example 10

[0142] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 10") were obtained in the same manner as in Example 1, except that 30.0% cellulose, 66.25% linear low-density polyethylene resin, 1.00% zinc stearate, 0.25% glycerin monostearate, and 2.50% compatibilizer were mixed.

[0143] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 10 in the same manner as in Example 1. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 30%.

[0144] In Example 10, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 4 above.

[0145] Example 11

[0146] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 11") were obtained in the same manner as in Example 1, except that 40.0% cellulose, 55.00% linear low-density polyethylene resin, 1.33% zinc stearate, 0.33% glycerin monostearate, and 3.33% compatibilizer were mixed.

[0147] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 11 in the same manner as in Example 1. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 40%.

[0148] In Example 11, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 4 above.

[0149] The relationship between the corn starch blending ratio relative to the mass of the biomass material-containing thermoplastic resin and peel strength shown in Table 2 is plotted in FIG. 1, and the relationship between the cellulose blending ratio relative to the mass of the biomass material-containing thermoplastic resin and peel strength shown in Table 4 is also plotted in FIG. 1. Furthermore, the relationship between the corn starch blending ratio relative to the mass of the biomass material-containing thermoplastic resin and surface roughness Ry value in the MD shown in Table 2 is plotted in FIG. 2, and the relationship between the cellulose blending ratio relative to the mass of the biomass material-containing thermoplastic resin and surface roughness Ry value in the MD shown in Table 4 is also plotted in FIG. 2. Furthermore, the relationship between the corn starch blending ratio relative to the mass of the biomass material-containing thermoplastic resin and surface roughness Ry value in the TD shown in Table 2 is plotted in FIG. 3, and the relationship between the cellulose blending ratio relative to the mass of the biomass material-containing thermoplastic resin and surface roughness Ry value in the TD shown in Table 4 is also plotted in FIG. 3. From these results, the following can be seen:

[0150] The release films of Examples 1 to 11 all had a peel strength of 1.5 N / 25 mm or less, demonstrating excellent releasability. On the other hand, the release film of Comparative Example 1 did not contain a biomass material, and therefore had a peel strength of greater than 1.5 N / 25 mm, resulting in poor releasability. It can also be seen that the higher the blending ratio of the biomass material, corn starch or cellulose, the lower the peel strength and the better the releasability. These release films also had a surface roughness Ry value of 7 μm or more in both the MD and TD directions. Furthermore, it can also be seen that the higher the blending ratio of the biomass material, corn starch or cellulose, the greater the surface roughness Ry value.

[0151] [Relationship between peel strength and surface roughness]

[0152] Figure 4 shows the relationship between peel strength and surface roughness Ry value for the corn starch-containing release films in each of Examples 1 to 6 and Comparative Example 1. Figure 5 shows the relationship between peel strength and surface roughness Ry value for the cellulose material-containing release films in each of Examples 7 to 11 and Comparative Example 1. Figures 4 and 5 show that for release films containing corn starch or a cellulose material as a biomass material, there is a correlation between peel strength and surface roughness Ry value, and that as the surface roughness Ry value increases, the peel strength decreases.

[0153] <Multi-layer release film>

[0154] [Release film with resin layer] Test Example 3: Production of release film

[0155] Example 12

[0156] A three-layer film with a total thickness of 45 μm was molded using a multi-layer inflation molding machine (Hokushin Sangyo Co., Ltd., die size: 350φ, extruder diameter (inner layer: 65 mm, middle layer: 90 mm, outer layer: 65 mm), cylinder temperature: 165°C, die temperature: 184°C) according to the formulation in Table 5. The thicknesses of the inner, middle, and outer layers were 15 μm:15 μm:15 μm, respectively.

[0157] [Table 5]

[0158] In Example 12, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 6 below.

[0159] [Table 6]

[0160] The roughened inner layer surface of the obtained film had a peel strength of 0.777 N / 25 mm, a surface roughness (Ry) in the MD direction of 25 μm, and a surface roughness (Ry) in the TD direction of 27.6 μm.

[0161] <Single layer release film>

[0162] [Release film containing corn starch as a biomass material] Test Example 4: Production of release film

[0163] Example 13

[0164] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 1 in the same manner as in Example 1, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 5%.

[0165] In Example 13, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 below.

[0166] [Table 7]

[0167] Example 14

[0168] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 2, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 10%.

[0169] In Example 14, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 above.

[0170] Example 15

[0171] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 3 in the same manner as in Example 3, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 20%.

[0172] In Example 15, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 above.

[0173] Example 16

[0174] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 4 in the same manner as in Example 4, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 30%.

[0175] In Example 16, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 above.

[0176] Example 17

[0177] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 5 in the same manner as in Example 5, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 40%.

[0178] In Example 17, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 above.

[0179] Example 18

[0180] A film was obtained by inflation molding using the biomass material-containing thermoplastic resin of Example 6 in the same manner as in Example 6, except that the thickness was 30 μm. The corn starch content relative to the mass of the biomass material-containing thermoplastic resin was 50%.

[0181] In Example 18, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 7 above.

[0182] The release films of Examples 13 to 18 all had a peel strength of 1.5 N / 25 mm or less, indicating excellent releasability. Furthermore, these release films had a surface roughness Ry value of 7 μm or more in both the MD and TD directions.

[0183] [Release film containing potato starch as a biomass material] Test Example 5: Production of release film

[0184] Example 19

[0185] 5.0% potato starch (Rocket Japan Co., Ltd.), 94.38% linear low-density polyethylene resin (LLDPE, Prime Polymer Co., Ltd., "EVOLUE SP0540"), 0.23% zinc stearate (Daikyo Kasei Kogyo Co., Ltd.), 0.06% glycerin monostearate (Riken Vitamin Co., Ltd.), and 0.033% compatibilizer were prepared. These ingredients were blended and mixed in a high-temperature mixer. Note that the potato starch used for blending had been dried in advance. Similar treatments were used in the following examples in which potato starch was blended.

[0186] The mixture obtained by the above mixing was fed into a twin-screw extruder (manufactured by Ikegai Corporation, "PCM30"), and the mixture was subjected to a kneading treatment.

[0187] In this kneading process, the cylinder temperature and adapter temperature of the twin-screw extruder were each set to 180°C. The screw speed of the twin-screw extruder was 100 rpm, and the feeder speed was 110 rpm. After this kneading process, the mixture was extruded through the die of the twin-screw extruder to obtain strands. The obtained strands were pelletized to obtain compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 19").

[0188] The compound pellets of the biomass material-containing thermoplastic resin of Example 19 were fed into an inflation molding machine (Placo Corporation, die Φ65, extruder diameter 55 mm) and inflation molding was performed. In this inflation molding, the cylinder temperature and die temperature from the inflation molding machine were both set to 170°C. A film with a thickness of 50 μm was obtained by extruding the molten material from the inflation molding machine. As shown in Table 8 below, the potato starch content relative to the mass of the biomass material-containing thermoplastic resin was 5%.

[0189] In Example 19, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 9 below.

[0190] [Table 8] *6: Manufactured by Rocket Japan Co., Ltd.

[0191] [Table 9]

[0192] Example 20

[0193] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 20") were obtained in the same manner as in Example 19, except that 10% potato starch, 88.75% linear low-density polyethylene resin, 0.47% zinc stearate, 0.12% glycerin monostearate, and 0.67% compatibilizer were mixed.

[0194] Using the biomass material-containing thermoplastic resin of Example 20, inflation molding was performed in the same manner as in Example 19 to obtain a film with a thickness of 50 μm. As shown in Table 8 above, the potato starch content relative to the mass of the biomass material-containing thermoplastic resin was 10%.

[0195] In Example 20, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 9 above.

[0196] Example 21

[0197] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 21") were obtained in the same manner as in Example 19, except that 20% potato starch, 77.50% linear low-density polyethylene resin, 0.93% zinc stearate, 0.23% glycerin monostearate, and 1.33% compatibilizer were mixed.

[0198] Using the biomass material-containing thermoplastic resin of Example 21, inflation molding was performed in the same manner as in Example 19 to obtain a film with a thickness of 50 μm. As shown in Table 8 above, the potato starch content relative to the mass of the biomass material-containing thermoplastic resin was 20%.

[0199] In Example 21, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 9 above.

[0200] Example 22

[0201] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 22") were obtained in the same manner as in Example 19, except that 30% potato starch, 66.25% linear low-density polyethylene resin, 1.40% zinc stearate, 0.35% glycerin monostearate, and 2.00% compatibilizer were mixed.

[0202] Using the biomass material-containing thermoplastic resin of Example 22, inflation molding was performed in the same manner as in Example 19 to obtain a film with a thickness of 50 μm. As shown in Table 8 above, the potato starch content relative to the mass of the biomass material-containing thermoplastic resin was 30%.

[0203] In Example 22, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 9 above.

[0204] The relationship between the blending ratio of potato starch to the mass of the biomass material-containing thermoplastic resin and the peel strength shown in Table 9 is plotted in Figure 8. Also, the relationship between the blending ratio of potato starch to the mass of the biomass material-containing thermoplastic resin and the surface roughness Ry value in the MD shown in Table 9 is plotted in Figure 9. Furthermore, the relationship between the blending ratio of potato starch to the mass of the biomass material-containing thermoplastic resin and the surface roughness Ry value in the TD shown in Table 9 is plotted in Figure 10. From these results, the following can be seen:

[0205] The release films of Examples 19 to 22 all had a peel strength of 1.5 N / 25 mm or less, demonstrating excellent releasability. It can also be seen that the higher the blending ratio of potato starch, a biomass material, the lower the peel strength and the better the releasability. These release films also had a surface roughness Ry value of 7 μm or more in both the MD and TD directions. It can also be seen that the higher the blending ratio of potato starch, a biomass material, the greater the surface roughness Ry value.

[0206] [Relationship between peel strength and surface roughness]

[0207] The relationship between the peel strength and surface roughness Ry value of the potato starch-containing release films in each of the above Examples 19 to 22 is shown in Figure 11. Figure 11 shows that for release films containing potato starch as a biomass material, there is a correlation between the peel strength and the surface roughness Ry value, and that the peel strength decreases as the surface roughness Ry value increases.

[0208] [Release film containing cellulose as a biomass material] Test Example 6: Production of release film

[0209] Example 23

[0210] Using the biomass material-containing thermoplastic resin of Example 7, a film having a thickness of 30 μm was obtained by inflation molding in the same manner as in Example 1. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 5.0%.

[0211] In Example 23, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 10 below.

[0212] [Table 10]

[0213] Example 24

[0214] Using the biomass material-containing thermoplastic resin of Example 8, inflation molding was performed in the same manner as in Example 23 to obtain a film with a thickness of 30 μm. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 10%.

[0215] In Example 24, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 10 above.

[0216] Example 25

[0217] Using the biomass material-containing thermoplastic resin of Example 9, inflation molding was performed in the same manner as in Example 23 to obtain a film with a thickness of 30 μm. As shown in Table 3 above, the cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 20%.

[0218] In Example 25, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 10 above.

[0219] <Multi-layer release film>

[0220] [Release film with resin layer] Test Example 7: Production of release film

[0221] Example 26

[0222] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 26") were obtained in the same manner as in Example 1, except that 50% potato starch, 43.75% linear low-density polyethylene resin, 2.33% zinc stearate, 0.58% glycerin monostearate, and 3.33% compatibilizer were mixed. The potato starch content relative to the mass of the biomass material-containing thermoplastic resin was 50%.

[0223] A three-layer film with a total thickness of 40 μm was molded using a multi-layer inflation molding machine (Hokushin Sangyo Co., Ltd., die size: 350φ, extruder diameter (inner layer: 65 mm, middle layer: 90 mm, outer layer: 65 mm), cylinder temperature: 165°C, die temperature: 184°C) according to the formulation in Table 11. The thicknesses of the inner layer, middle layer, and outer layer were 10 μm: 15 μm: 15 μm, respectively.

[0224] [Table 11]

[0225] In Example 26, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 12 below.

[0226] [Table 12]

[0227] The peel strength of the inner layer side surface of the obtained release film, which was a rough surface, was 0.136 N / 25 mm, the surface roughness (Ry) in the MD direction was 32.8 μm, and the surface roughness (Ry) in the TD direction was 31.3 μm.

[0228] Example 27

[0229] Compound pellets of a biomass material-containing thermoplastic resin (hereinafter also referred to as "biomass material-containing thermoplastic resin of Example 27") were obtained in the same manner as in Example 1, except that 50% cellulose ("KC Flock W400" manufactured by Nippon Paper Industries Co., Ltd.), 43.75% linear low-density polyethylene resin, 2.33% zinc stearate, 0.58% glycerin monostearate, and 3.33% compatibilizer were mixed. The cellulose content relative to the mass of the biomass material-containing thermoplastic resin was 50%.

[0230] A three-layer film with a total thickness of 60 μm was molded using a multi-layer inflation molding machine (Hokushin Sangyo Co., Ltd., die size: 350φ, extruder diameter (inner layer: 65 mm, middle layer: 90 mm, outer layer: 65 mm), cylinder temperature: 165°C, die temperature: 184°C) according to the formulation in Table 13. The thicknesses of the inner layer, middle layer, and outer layer were 15 μm: 30 μm: 15 μm, respectively.

[0231] [Table 13]

[0232] In Example 27, the same evaluations as in Example 1 were carried out. The evaluation results are shown in Table 14 below.

[0233] [Table 14]

[0234] The peel strength of the inner layer side surface of the obtained release film, which was a rough surface, was 0.604 N / 25 mm, the surface roughness (Ry) in the MD direction was 19.27 μm, and the surface roughness (Ry) in the TD direction was 20.11 μm.

[0235] The configurations, methods, steps, shapes, materials, and numerical values, etc., described in the above-described embodiments and examples are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values, etc., may be used as necessary.

[0236] Furthermore, the configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and examples can be combined with each other without departing from the spirit of the present technology.

[0237] Furthermore, in this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage may be replaced with the upper or lower limit of a numerical range in another stage. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types. [Explanation of symbols]

[0238] 10 Release film 11 Biomass material-containing thermoplastic resin layer 20 Release film 21 Biomass material-containing thermoplastic resin layer 22 Resin layer 23 Resin layer

Claims

1. A release film formed from a thermoplastic resin, the thermoplastic resin is selected from an olefin-based resin, a polyester-based resin, a mixture of an olefin-based resin and a polyester-based resin, or a polystyrene-based resin; the thermoplastic resin comprises a biomass material; the biomass material is a starch material and / or a cellulosic material; The content of the biomass material is 5% by mass or more relative to the mass of the thermoplastic resin containing the biomass material, and an acrylic tape is attached to the release film, and the peel strength when the acrylic tape is peeled from the release film is 1.5 N / 25 mm or less; The surface roughness (Ry) of at least one surface measured in accordance with JIS B 0031 is 7 μm or more, The peel strength of the release film is measured in accordance with JIS Z 0237.

2. 2. The release film according to claim 1, wherein the content of the starch material is 5% by mass or more and 60% by mass or less with respect to the mass of the thermoplastic resin containing the starch material.

3. 2. The release film of claim 1, wherein the starch material is potato starch.

4. 2. The release film according to claim 1, wherein the content of the cellulose material is 5% by mass or more and 45% by mass or less.

5. The release film according to claim 1 , wherein the thermoplastic resin is a polyethylene resin.

6. The release film according to any one of claims 1 to 5, which is a release paper used in an adhesive tape.

7. The release film according to any one of claims 1 to 6, wherein a resin layer is laminated on at least one surface of the release film.

8. The release film according to claim 7 , wherein the resin layer is formed from a thermoplastic resin.

9. 9. The release film according to claim 7, wherein the surface roughness (Ry) of at least one surface thereof, measured in accordance with JIS B 0031, is 7 μm or more.

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