Polyethylene-based sealant film and laminate film

Abstract

To provide a new polyethylene-based sealant film and laminated film which can be suppressed in deterioration of performances such as laminate strength, slipperiness and transparency, even if a layer added with a biomass-derived polyethylene-based resin serves as a film surface layer.SOLUTION: A substrate layer 20 has a composition comprising 5 to 50 wt.% of a biomass-derived polyethylene-based resin and 50-95 wt.% of a petroleum-derived polyethylene-based resin, an intermediate layer 30 has a composition comprising 5 to 94 wt.% of a biomass-derived polyethylene-based resin and 6 to 95 wt.% of a petroleum-derived polyethylene-based resin, a sealant layer 40 is composed of a petroleum-derived polyethylene-based resin, the area ratio in a region having a molecular weight of a molecular weight distribution curve obtained from GPC measurement of 10,000 or less of the biomass-derived polyethylene-based resin is less than 10% with respect to the total peak area, and density (d1) of the substrate layer and density (d2) of the intermediate layer satisfy d1≥d2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to polyethylene-based sealant films and laminate films containing biomass-derived polyethylene resin for reducing environmental impact. [Background technology]

[0002] The main cause of global warming is the increase in atmospheric carbon dioxide concentration, and carbon neutrality is required in various fields to reduce environmental impact. For example, synthetic resin materials that make up resin films are generally produced using petroleum and other raw materials, but in recent years, the use of biomass resources has attracted attention from the perspective of carbon neutrality.

[0003] Therefore, in the field of resin films, the development of resin films using biomass resources is progressing in response to the demand for carbon neutrality. For example, resin films containing 5% or more by mass of biomass-derived polyethylene are known (see, for example, Patent Document 1). Since biomass-derived polyethylene is manufactured using biomass-derived ethanol obtained from plant materials as a raw material, it is possible to reduce the amount of conventional petroleum (fossil fuel)-derived materials used. Therefore, by incorporating a large amount of biomass-derived polyethylene into resin films, the contribution to reducing environmental impact can be further enhanced.

[0004] However, biomass-derived polyethylene currently on the market contains a relatively large amount of low molecular weight components. When biomass-derived polyethylene is used as a material to make up a resin film, a bleed-out phenomenon may occur where the low molecular weight components of the biomass-derived polyethylene appear as a powder on the film surface. Such bleeding on the film surface causes a decrease in laminate strength. Furthermore, if a large amount of biomass-derived polyethylene is included to reduce environmental impact, the bleed-out phenomenon becomes more pronounced, leading to a problem where laminate strength tends to decrease even more easily.

[0005] Therefore, a sealant film containing a biomass-derived polyethylene resin with a bleed-out inhibitor added has been proposed (see, for example, Patent Document 2). In this sealant film, the addition of a bleed-out inhibitor makes it possible to suppress the decrease in laminate strength while still containing a biomass-derived polyethylene resin. When sealant films are used as materials for packaging, for example, properties such as slipperiness and transparency are sometimes required. However, when a lubricant (slip agent) to improve slipperiness is added to a sealant film containing a bleed-out inhibitor, the lubricant is absorbed by the bleed-out inhibitor, which leads to a decrease in the slipperiness of the film. In addition, depending on the type of bleed-out inhibitor, there were problems such as the film turning white and the transparency deteriorating.

[0006] In response to this, a sealant film has been proposed in which a layer made of petroleum-derived polyethylene resin and a layer made of biomass-derived polyethylene resin are laminated together to achieve both lamination strength and slipperiness, with the layer made of petroleum-derived polyethylene resin being the outermost layer forming the substrate laminate surface (see, for example, Patent Document 3). In this sealant film, when the heat-seal surface is made of a layer made of biomass-derived polyethylene resin, the slipperiness of the heat-seal surface deteriorates. Therefore, when manufacturing bags using this sealant film, if the heat-seal surface comes into contact with the manufacturing equipment, snagging may occur, leading to a problem of reduced processing suitability.

[0007] To address the above issues, both the front and back surfaces of the sealant film are composed of layers made of petroleum-derived polyethylene resin. However, increasing the amount of petroleum-derived polyethylene resin may decrease the proportion of biomass-derived polyethylene resin. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2012-251006 [Patent Document 2] Japanese Patent Publication No. 2013-177531 [Patent Document 3] Japanese Patent Publication No. 2016-196195 [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention has been made in view of the above points, and provides a new polyethylene-based sealant film and laminate film that can suppress a decrease in performance such as laminate strength, slipperiness, and transparency even when a layer to which biomass-derived polyethylene resin is added is used as the film surface layer. [Means for solving the problem]

[0010] In other words, the invention of claim 1 is an unstretched polyethylene film having a base layer, an intermediate layer, and a sealant layer, wherein the base layer has a composition of 5 to 50% by weight of biomass-derived polyethylene resin and 50 to 95% by weight of petroleum-derived polyethylene resin, the intermediate layer has a composition of 5 to 94% by weight of biomass-derived polyethylene resin and 6 to 95% by weight of petroleum-derived polyethylene resin, the sealant layer is made of petroleum-derived polyethylene resin, the biomass-derived polyethylene resin has an area ratio of the region with a molecular weight of 10,000 or less in the molecular weight distribution curve obtained from GPC measurement in accordance with JIS K 7252-1 (2008) that is less than 10% of the total peak area, and the density (d1) of the base layer and the density (d2) of the intermediate layer in accordance with JIS K 7112 are All values ​​are 0.919 g / cm³. 3 Furthermore, the density of the entire layer is 0.918 g / cm³. 3 Or 0.919 g / cm³ 3 Whether it satisfies, The present invention relates to a polyethylene-based sealant film characterized in that the density (d1) of the base layer and the density (d2) of the intermediate layer satisfy d1 > d2.

[0011] The invention according to claim 2 relates to a laminated film, characterized in that another resin film is laminated on the base material layer side of the polyethylene-based sealant film according to claim 1.

Effect of the Invention

[0012] According to the polyethylene-based sealant film according to the invention of claim 1, it is an unstretched polyethylene-based film having a base material layer, an intermediate layer, and a sealant layer. The base material layer has a composition of 5 to 50% by weight of a biomass-derived polyethylene-based resin and 50 to 95% by weight of a petroleum-derived polyethylene-based resin. The intermediate layer has a composition of 5 to 94% by weight of a biomass-derived polyethylene-based resin and 6 to 95% by weight of a petroleum-derived polyethylene-based resin. The sealant layer is a petroleum-derived polyethylene-based resin. The biomass-derived polyethylene-based resin has an area ratio in the region with a molecular weight of 10,000 or less in the molecular weight distribution curve obtained from GPC measurement in accordance with JIS K 7252-1 (2008) less than 10% of the total peak area. The density (d1) of the base material layer and the density (d2) of the intermediate layer in accordance with JIS K 7112 are All values ​​are 0.919 g / cm³. 3 Furthermore, the density of the entire layer is 0.918 g / cm³. 3 Or 0.919 g / cm³ 3 Whether it satisfies, Since the density (d1) of the base material layer and the density (d2) of the intermediate layer satisfy d1 > d2, even if a biomass-derived polyethylene-based resin is added to the base material layer (surface layer), a sealant film can be obtained that has no significant change in performance such as lamination strength, slipperiness, transparency, etc. compared to conventional sealant films.

[0013] According to the laminated film according to the invention of claim 2, since another resin film is laminated on the base material layer side of the polyethylene-based sealant film according to claim 1, it can contribute to reducing the environmental load while having performance comparable to conventional films.

Brief Description of the Drawings

[0014] [Figure 1]This is a schematic cross-sectional view of a polyethylene-based sealant film according to one embodiment of the present invention. [Figure 2] Figure 1 is a schematic cross-sectional view of a laminate film in which another resin film is laminated on the substrate layer side of a polyethylene-based sealant film. [Modes for carrying out the invention]

[0015] The polyethylene sealant film 10 according to one embodiment of the present invention shown in Figure 1 is an unoriented polyethylene film having a base layer 20, an intermediate layer 30, and a sealant layer 40, and from the viewpoint of carbon neutrality, the base layer 20 and the intermediate layer 30 contain biomass-derived polyethylene resin. The unoriented polyethylene film is manufactured to a predetermined thickness by a known manufacturing method such as the T-die method, in which the resins constituting each layer are melted. The sealant film 10 is suitably used for packaging bags for food packaging materials such as fresh food, processed food, and confectionery, as well as for packaging materials for detergents, cosmetics, and other pharmaceuticals. In addition, it can be used for industrial film products as appropriate.

[0016] The base layer 20 is the surface layer of the sealant film 10 and is composed of 5-50% by weight of biomass-derived polyethylene resin and 50-95% by weight of petroleum-derived polyethylene resin. The biomass-derived polyethylene resin is a polyethylene resin obtained by processing plant raw materials. Specifically, ethanol is produced from a sugar solution extracted from plant raw materials such as sugarcane through alcoholic fermentation by yeast, which is then ethyleneified, and polyethylene is produced through a known resinification process. Since this biomass-derived polyethylene resin contributes to reducing the environmental burden of the final product, increasing its weight-based blending ratio enhances its contribution to reducing the environmental burden.

[0017] It is preferable that the area ratio of the region with a molecular weight of 10,000 or less in the molecular weight distribution curve obtained from GPC (gel permeation chromatography) measurement in accordance with JIS K 7252-1 (2008) is less than 10% of the total peak area (distribution area). In GPC measurement, the biomass-derived polyethylene resin is dissolved in a suitable solvent such as dichlorobenzene, and this solution is passed through a column to separate and detect molecules by molecular weight. The area ratio of the region with a molecular weight of 10,000 or less corresponds to the proportion of low molecular weight molecules in the biomass-derived polyethylene resin. Therefore, the preferred condition for the biomass-derived polyethylene resin used is a low proportion of low molecular weight molecules (molecular weight of 10,000 or less).

[0018] Petroleum-derived polyethylene resins are known polyethylene resins produced from petroleum and other raw materials, and include linear low-density polyethylene resin (LLDPE), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). Linear low-density polyethylene resin is a random copolymer of ethylene and α-olefins having 3 to 8 carbon atoms, and is excellent in terms of tensile strength, tear resistance, impact strength, seal strength, and stress cracking resistance. High-density polyethylene is excellent in terms of tensile strength, tear resistance, impact strength, seal strength, and heat resistance. The choice of which of the above resins to use depends on the application. Low-density polyethylene is excellent in terms of transparency, flexibility, and moldability. The melt flow rate of petroleum-derived polyethylene resins is not particularly limited, but for example, as measured under the conditions of 190°C and a load of 2.16 kg as described in JIS K 7210, the MFR is 0.1 to 30 g / 10 min, preferably 1 to 10 g / 10 min.

[0019] If the proportion of biomass-derived polyethylene resin in the base layer 20 is too low, the amount of biomass-derived polyethylene resin contained in the entire sealant film 10 will be small, making it unsuitable for the purpose of contributing to reducing environmental impact. Conversely, if the proportion of biomass-derived polyethylene resin is too high, a decrease in transparency and a decrease in laminate strength due to bleed-out phenomena are more likely to occur.

[0020] The intermediate layer 30 is a layer composed of 5 to 94% by weight of biomass-derived polyethylene resin and 6 to 95% by weight of petroleum-derived polyethylene resin. The preferred conditions for the biomass-derived polyethylene resin and petroleum-derived polyethylene resin used in the intermediate layer 30 are the same as those for the biomass-derived polyethylene resin and petroleum-derived polyethylene resin used in the base layer 20. The biomass-derived polyethylene resin or petroleum-derived polyethylene resin used in the intermediate layer 30 may be the same as or different from the resin used in the base layer 20.

[0021] In the intermediate layer 30, similar to the base layer 20, if the proportion of biomass-derived polyethylene resin is too low, the amount of biomass-derived polyethylene resin contained in the entire sealant film 10 will be small, making it unsuitable for the purpose of contributing to reducing environmental impact. Conversely, if the proportion of biomass-derived polyethylene resin is too high, a decrease in transparency and a decrease in laminate strength due to bleed-out phenomena are more likely to occur.

[0022] The sealant layer 40 is the heat-sealing surface layer of the sealant film 10 and is composed of a petroleum-derived polyethylene resin. Similar to the base layer 20 and the intermediate layer 30, linear low-density polyethylene resin (LLDPE) is preferably used as the petroleum-derived polyethylene resin. Furthermore, since the sealant layer 40 does not contain biomass-derived polyethylene resin, sufficient sealing strength required for the heat-sealing surface can be ensured.

[0023] In each of the base layer 20, the intermediate layer 30, and the sealant layer 40, various additives such as lubricants, antiblocking agents, heat stabilizers, antioxidants, light stabilizers, crystal nucleating agents, and ultraviolet absorbers can be added as needed.

[0024] In the sealant film 10, there is no particular limitation on the thickness, but it is usually 20 to 200 μm, preferably 20 to 150 μm. The thickness ratio of the base material layer 20, the intermediate layer 30, and the sealant layer 40 of the sealant film 10 is in the range of 10% - 33.3%: 33.4% - 80%: 10% - 33.3%.

[0025] This sealant film 10 has a density (d1) of the base material layer 20 conforming to JIS K 7112 of 0.919 g / cm 3 or more, and the density (d1) of the base material layer 20 and the density (d2) of the intermediate layer 30 satisfy d1 ≥ d2. The density of the base material layer 20 and the intermediate layer 30 is determined according to the density and blending ratio of each resin of the biomass-derived polyethylene resin and the petroleum-derived polyethylene resin in each layer.

[0026] As described above, since the biomass-derived polyethylene contains a relatively large amount of low molecular weight components, when used as a film material, there are problems such as the low molecular weight components appearing on the film surface and the occurrence of bleed-out phenomenon. However, in the sealant film 10 of the present invention, the density (d1) of the base material layer 20 is 0.919 g / cm 3 or more, and the density (d1) of the base material layer 20 and the density (d2) of the intermediate layer 30 are d1 ≥ d2, so that the transparency of the film can be ensured and the occurrence of the bleed-out phenomenon can be appropriately suppressed.

[0027] This is considered to be because the density (d1) of the base material layer 20 is configured to be as high as 0.919 g / cm 3 or more, making it difficult for the low molecular weight components of the biomass-derived polyethylene contained in the base material layer 20 to appear on the film surface. In addition, since the density (d1) of the base material layer is configured to be not less than the density (d2) of the intermediate layer (d1 ≥ d2), the transfer of the low molecular weight components of the biomass-derived polyethylene contained in the intermediate layer 30 to the base material layer is suppressed, making it difficult to appear on the film surface.

[0028] Furthermore, since the amount of low molecular weight components bleeding due to the bleed-out phenomenon affects the transparency of the film, the sealant film 10 of the present invention can suppress the bleed-out phenomenon, thereby ensuring transparency. The transparency of the film can be evaluated, for example, by the level of the haze value measured in accordance with JIS K 7136 (2000). In the sealant film 10 of the embodiment, the haze can be set to 10% or less, and a beautiful appearance can be obtained.

[0029] As shown in Figure 2, the sealant film 10 of the present invention can also be laminated with another resin film 60 on the base layer 20 side to form a laminate film 50. The laminate film 50 is suitably used as a raw material for products such as packaging bags and sheet-like lids for packaging containers. The other resin film 60 laminated on the base layer 20 side is appropriately selected depending on the application, but when used as a product, it corresponds to the outer packaging. Therefore, suitable other resin films 60 include, for example, biaxially oriented polypropylene film (OPP film), polyester film (PET film), nylon film (Ny film), and other known films that are inexpensive, easy to process, and have excellent strength. By using these resins, the sealant film 10 on the lower layer side can be properly protected. [Examples]

[0030] [Film production] For prototypes 1-25, the sealant films were prepared by melting and kneading the raw resin based on the resin blending ratio (weight %) described below, co-extruding them using a T-die film molding machine, and cooling them with a cooling roll to produce unstretched polyethylene-based sealant films. The raw materials used to constitute each layer were blended in a ratio that totaled 100% by weight. The sealant films for each prototype were produced using the same settings, with all films having a thickness of 50 μm and a thickness ratio of 1:3:1 for the base layer, intermediate layer, and sealant layer. As reference example 1, an unstretched polyethylene-based sealant film that did not use biomass-derived polyethylene resin was produced using the same procedure.

[0031] [Materials made from biomass-derived polyethylene resins] The biomass-derived polyethylene resin used was made from the following resins (A1) to (A3). ·Resin (A1): Density 0.916g / cm 3 Biomass-derived polyethylene resin (Braskem SA "SLH218") ·Resin (A2): Density 0.918g / cm 3 Biomass-derived polyethylene resin (Braskem SA "SLL318") ·Resin (A3): Density 0.961g / cm 3 Biomass-derived polyethylene resin (Braskem SA "SGM9460")

[0032] [Materials made from petroleum-derived polyethylene resins] The petroleum-derived polyethylene resin used was made from the following resins (B1) to (B6). ·Resin (B1): Density 0.918g / cm 3 Petroleum-derived polyethylene resin (2040F, manufactured by Ube Maruzen Polyethylene Co., Ltd.) ·Resin (B2): Density 0.923g / cm 3 Petroleum-derived polyethylene resin (2540F, manufactured by Ube Maruzen Polyethylene Co., Ltd.) ·Resin (B3): Density 0.944g / cm 3 Petroleum-derived polyethylene resin (4540F, manufactured by Ube Maruzen Polyethylene Co., Ltd.) ·Resin (B4): Density 0.904g / cm 3 Petroleum-derived polyethylene resin (manufactured by Ube Maruzen Polyethylene Co., Ltd., "0540F") ·Resin (B5): Density 0.963g / cm 3 Petroleum-derived polyethylene resin ("HF560" manufactured by Nippon Polyethylene Co., Ltd.) ·Resin (B6): Density 0.898g / cm 3 Petroleum-derived polyethylene resin (KF360T manufactured by Nippon Polyethylene Co., Ltd.)

[0033] [Prototype Example 1] The sealant film of prototype example 1 was prepared using the following formulations: a base layer consisting of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); an intermediate layer consisting of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); and a sealant layer consisting of 100% by weight of resin (B1).

[0034] [Prototype Example 2] The sealant film of prototype example 2 was manufactured using the following formulations: a base layer consisting of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); an intermediate layer consisting of 94% by weight of resin (A1) and 6% by weight of resin (B5); and a sealant layer consisting of 100% by weight of resin (B1).

[0035] [Prototype Example 3] The sealant film of prototype example 3 was manufactured using the following formulation ratios: a base layer of 10% by weight of resin (A1), 70% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer of 10% by weight of resin (A1), 70% by weight of resin (B1), and 20% by weight of resin (B2); and a sealant layer of 100% by weight of resin (B1).

[0036] [Prototype Example 4] The sealant film of prototype example 4 was manufactured using the following formulation ratios: a base layer of 20% by weight of resin (A1), 60% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer of 100% by weight of resin (B1).

[0037] [Prototype Example 5] The sealant film of prototype example 5 was manufactured using the following formulations: a base layer consisting of 40% by weight of resin (A1), 25% by weight of resin (B1), and 35% by weight of resin (B2); an intermediate layer consisting of 94% by weight of resin (A1) and 6% by weight of resin (B5); and a sealant layer consisting of 100% by weight of resin (B1).

[0038] [Prototype Example 6] The sealant film of prototype example 6 was manufactured using the following formulation ratios: a base layer of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); an intermediate layer of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer of 100% by weight of resin (B1).

[0039] [Prototype Example 7] The sealant film of prototype example 7 was manufactured using the following formulations: a base layer of 50% by weight of resin (A1), 15% by weight of resin (B1), and 35% by weight of resin (B2); an intermediate layer of 94% by weight of resin (A1) and 6% by weight of resin (B5); and a sealant layer of 100% by weight of resin (B1).

[0040] [Prototype Example 8] The sealant film of prototype example 8 was manufactured using the following formulations: a base layer of 60% by weight of resin (A1) and 40% by weight of resin (B2), an intermediate layer of 94% by weight of resin (A1) and 6% by weight of resin (B5), and a sealant layer of 100% by weight of resin (B1).

[0041] [Prototype Example 9] The sealant film of prototype example 9 was manufactured using the following formulations: a base layer of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); an intermediate layer of 20% by weight of resin (A1) and 80% by weight of resin (B6); and a sealant layer of 100% by weight of resin (B1).

[0042] [Prototype Example 10] The sealant film of prototype example 10 was manufactured using the following formulations: a base layer of 5% by weight of resin (A1), 85% by weight of resin (B2), and 10% by weight of resin (B3); an intermediate layer of 20% by weight of resin (A1) and 80% by weight of resin (B6); and a sealant layer of 100% by weight of resin (B1).

[0043] [Prototype Example 11] The sealant film of prototype example 11 was manufactured using the following formulations: a base layer consisting of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); an intermediate layer consisting of 40% by weight of resin (A1) and 60% by weight of resin (B6); and a sealant layer consisting of 100% by weight of resin (B4).

[0044] [Prototype Example 12] The sealant film of prototype example 12 was manufactured using the following formulations: a base layer of 5% by weight of resin (A1), 80% by weight of resin (B1), and 15% by weight of resin (B2); an intermediate layer of 60% by weight of resin (A1) and 40% by weight of resin (B6); and a sealant layer of 100% by weight of resin (B6).

[0045] [Prototype Example 13] The sealant film of prototype example 13 was manufactured using the following formulations: a base layer consisting of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); an intermediate layer consisting of 40% by weight of resin (A1) and 60% by weight of resin (B4); and a sealant layer consisting of 100% by weight of resin (B1).

[0046] [Prototype Example 14] The sealant film of prototype example 14 was manufactured using the following formulations: a base layer of 40% by weight of resin (A1) and 60% by weight of resin (B3); an intermediate layer of 40% by weight of resin (A1), 40% by weight of resin (B1), and 20% by weight of resin (B2); and a sealant layer of 100% by weight of resin (B1).

[0047] [Prototype Example 15] The sealant film of prototype example 15 was manufactured using the following formulation ratios: 40% by weight of resin (A1) and 60% by weight of resin (B4) as the base layer, 40% by weight of resin (A1) and 60% by weight of resin (B4) as the intermediate layer, and 100% by weight of resin (B1) as the sealant layer.

[0048] [Prototype Example 16] The sealant film of prototype example 16 was manufactured using the following formulations: a base layer of 40% by weight of resin (A1) and 60% by weight of resin (B4), an intermediate layer of 94% by weight of resin (A1) and 6% by weight of resin (B5), and a sealant layer of 100% by weight of resin (B1).

[0049] [Prototype Example 17] The sealant film of prototype example 17 was manufactured using the following formulations: a base layer of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); an intermediate layer of 70% by weight of resin (A1) and 30% by weight of resin (B5); and a sealant layer of 100% by weight of resin (B1).

[0050] [Prototype Example 18] The sealant film of prototype example 18 was manufactured using the following formulations: a base layer consisting of 20% by weight of resin (A1), 20% by weight of resin (A3), 35% by weight of resin (B1), and 25% by weight of resin (B3); an intermediate layer consisting of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer consisting of 100% by weight of resin (B1).

[0051] [Prototype Example 19] The sealant film of prototype example 19 was manufactured using the following proportions: a base layer consisting of 20% by weight of resin (A1), 10% by weight of resin (A2), 10% by weight of resin (A3), and 60% by weight of resin (B2); an intermediate layer consisting of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer consisting of 100% by weight of resin (B1).

[0052] [Prototype Example 20] The sealant film of prototype example 20 was manufactured using the following formulation ratios: a base layer consisting of 20% by weight of resin (A1), 10% by weight of resin (A2), 10% by weight of resin (A3), 40% by weight of resin (B1), and 20% by weight of resin (B4); an intermediate layer consisting of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer consisting of 100% by weight of resin (B1).

[0053] [Prototype Example 21] The sealant film of prototype example 21 was manufactured using the following proportions: a base layer consisting of 20% by weight of resin (A1), 20% by weight of resin (A3), 32% by weight of resin (B1), and 28% by weight of resin (B3); an intermediate layer consisting of 20% by weight of resin (A1), 20% by weight of resin (A2), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer consisting of 100% by weight of resin (B1).

[0054] [Prototype Example 22] The sealant film of prototype example 22 was manufactured using the following formulation ratios: a base layer of 20% by weight of resin (A1), 60% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer of 20% by weight of resin (A1), 20% by weight of resin (A2), 40% by weight of resin (B1), and 20% by weight of resin (B2); and a sealant layer of 100% by weight of resin (B1).

[0055] [Prototype Example 23] The sealant film of prototype example 23 was manufactured using the following formulation ratios: a base layer of 20% by weight of resin (A1), 60% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer of 30% by weight of resin (A1), 10% by weight of resin (A3), 40% by weight of resin (B1), and 20% by weight of resin (B4); and a sealant layer of 100% by weight of resin (B1).

[0056] [Prototype Example 24] The sealant film of prototype example 24 was manufactured using the following proportions: a base layer consisting of 20% by weight of resin (A1), 60% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer consisting of 20% by weight of resin (A1), 10% by weight of resin (A2), 10% by weight of resin (A3), 40% by weight of resin (B1), and 20% by weight of resin (B4); and a sealant layer consisting of 100% by weight of resin (B1).

[0057] [Prototype Example 25] The sealant film of prototype example 25 was manufactured using the following formulations: a base layer consisting of 20% by weight of resin (A1), 60% by weight of resin (B1), and 20% by weight of resin (B2); an intermediate layer consisting of 40% by weight of resin (A1), 30% by weight of resin (B1), and 30% by weight of resin (B2); and a sealant layer consisting of 40% by weight of resin (A1) and 60% by weight of resin (B1).

[0058] [Reference example 1] The sealant film in Reference Example 1 was prepared by compounding resin (B1) at 100% by weight as the base layer, resin (B1) at 100% by weight as the intermediate layer, and resin (B1) at 100% by weight as the sealant layer.

[0059] [Fabrication of laminated films] Laminated films corresponding to prototypes 1-25 and reference example 1 were fabricated by dry laminating (adhesive layering) a 12 μm thick biaxially oriented polyester film (Futamura Chemical Co., Ltd. "FE2001") as a surface layer to the sealant films of prototypes 1-25 and reference example 1. The adhesive layer was prepared by mixing the main agent (Toyo Morton Co., Ltd., TM-329), the curing agent (Toyo Morton Co., Ltd., CAT-8B), and ethyl acetate, at a density of 1.5 g / m². 2 After applying the coating and drying at 80°C, it was bonded to the surface layer.

[0060] [GPC measurement of biomass-derived polyethylene resin] Biomass-derived polyethylene resins (resins A1-A3) were measured using gel permeation chromatography (GPC). For the measurements, in accordance with JIS K 7252-1 (2008), a Tosoh Corporation "HLC-8321GPC / HT" was used as the measuring instrument, with two columns, "TSKgel guardcolumn HHR(S)" and "GMHHR-H(S)HT," and a differential refractometer as the detector. The resin sample concentration was adjusted to 0.1 wt / vol% using o-dichlorobenzene as the eluent and completely dissolved. The column and injector temperatures were set to 145°C, and the flow rate was 1.0 mL / min. Polystyrene was used as the standard substance for molecular weight conversion, and petroleum-derived polyethylene resin (resin B1) was measured similarly for comparison.

[0061] For biomass-derived polyethylene resins (resins A1 to A3), the area ratio of the region with a molecular weight of 10,000 or less to the total peak area (distribution area) of the molecular weight distribution curve obtained from the above GCP measurement was 2.9% for resin (A1), 3.4% for resin (A2), and 7.4% for resin (A3). In contrast, for petroleum-derived polyethylene resin (resin B1), the area ratio of the region with a molecular weight of 10,000 or less to the total peak area (distribution area) of the molecular weight distribution curve was 1.9%.

[0062] [Calculation of sealant film density] For prototype examples 1-25 and reference example 1, the density of each layer (base layer, intermediate layer, sealant layer) and the total density (g / cm³) of the entire layer are as follows: 3 The density (ρ) was calculated based on the following formula (i). Note that formula (i) is the density (ρ) when multiple types of raw materials (X, Y, Z) are mixed. blend This calculates ρ X ρ is the density of raw material X. Y ρ is the density of the raw material Y. Z x is the density of raw material Z, x is the proportion of raw material X, y is the proportion of raw material Y, and z is the proportion of raw material Z.

[0063]

number

[0064] [Evaluation of sealant film performance] Using laminated films corresponding to prototype examples 1-25 and reference example 1, tests were conducted on the laminate strength (N / 15mm) and haze (%) of the sealant film, and the performance was evaluated based on the results. In the overall performance evaluation of the sealant film, a rating of "Good (〇)" was given if both the laminate strength and haze were judged as "Good," and a rating of "Unacceptable (×)" was given if either was judged as "Unacceptable." The results, along with the density of the sealant film, are shown in Tables 1-4 below.

[0065] [Measurement of Laminate Strength] The laminate strength (N / 15mm) was measured as one of the indicators of adhesive suitability, in accordance with JIS K 6854-3 (1999). In this measurement, rectangular test pieces measuring 15mm x 200mm (width direction x length direction of the film) were cut from the laminated films corresponding to prototype examples 1 to 25 and reference example 1. The sealant film and biaxially oriented polyester film, which are the non-laminate portions, were spread 180° vertically and fixed to the chuck of a tensile testing machine (Shimadzu Corporation "EZ-SX"). The laminate portion was peeled off by pulling it vertically at a test speed of 200mm / min to determine the laminate strength. The laminate strength (N / 15mm) was defined as the maximum peel force when 100mm was peeled off, and a measurement result of 7N / 15mm or higher was considered a good product.

[0066] [Measurement of haze] Haze (%) measurement is an indicator of transparency. After adjusting the sealant film at 35°C for 7 days, the measurement was performed using a haze meter (NDH-4000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7136 (2000). For prototype examples 1-25 and reference example 1, a measurement result of 10% or less was considered a good product.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

[0070] [Table 4]

[0071] [Results and Discussion] As shown in Tables 1 to 4, prototypes 1-7, 9-14, and 18-24 received an overall evaluation of "Good (〇)", while prototypes 8, 15, 16, 17, and 25 received an overall evaluation of "Unacceptable (×)". Among the prototypes that received an overall evaluation of "Unacceptable", prototypes 8, 15, 16, and 17 had insufficient lamination strength (less than 7 N / mm) and also lacked transparency due to haze exceeding 10%. Prototype 25 had sufficient lamination strength, but also lacked transparency due to haze exceeding 10%.

[0072] In prototype example 8, which received an overall evaluation of "unacceptable," the mixing ratios of the intermediate layer and sealant layer, as well as the density of each layer and the total layer, were the same as in prototype examples 2 and 7, which received an overall evaluation of "good." However, the mixing ratio of the base layer differed. Specifically, the mixing ratio of biomass-derived polyethylene resin in the base layer was 5% by weight for prototype example 2, 50% by weight for prototype example 7, while it was 60% by weight for prototype example 8. Furthermore, the mixing ratio of biomass-derived polyethylene resin in the base layer of prototype examples 1-7, 9-14, and 18-24, which received an overall evaluation of "good," all fell within the range of 5-50% by weight. From this, it was found that an excessive mixing ratio of biomass-derived polyethylene resin in the base layer reduces laminate strength and transparency (haze). It should be noted that a mixing ratio of biomass-derived polyethylene resin in the base layer of less than 5% by weight is undesirable from the perspective of reducing environmental impact. Therefore, the preferred condition for the mixing ratio of biomass-derived polyethylene resin in the base layer is considered to be 5-50% by weight.

[0073] Prototype 15, which received an overall evaluation of "Unacceptable," differed from prototype 13, which received a "Good" evaluation, in the composition of its base layer. Specifically, while the proportion of biomass-derived polyethylene resin was the same, the type of petroleum-derived polyethylene resin differed. Similarly, prototype 16 differed from prototype 5, which received a "Good" evaluation, in the composition of its base layer, specifically in the type of petroleum-derived polyethylene resin used. The density of the base layer in prototypes 15 and 16 was 0.909 g / cm³. 3 Therefore, the density of the substrate layer in prototype example 13,5 is 0.919 g / cm³. 3 It had become smaller. Also, the density of the substrate layer in prototype examples 1-7, 9-14, and 18-24, which received an overall evaluation of "Good," was 0.919 g / cm³ in all cases. 3 The above was the result. From this, it was found that a decrease in the density of the substrate layer leads to a decrease in laminate strength and transparency (haze). Therefore, the preferred density of the substrate layer is 0.919 g / cm³. 3 This is considered to be the case.

[0074] Prototype 17, which received an overall evaluation of "Unacceptable," differs from prototype 6, which received a "Good" evaluation, in the composition of its intermediate layer. The density of the intermediate layer in prototype 17 is 0.930 g / cm³. 3 The density of the substrate layer is 0.919 g / cm³. 3 Larger, the density of the intermediate layer in prototype example 6 is 0.919 g / cm³. 3 It was larger. Focusing on the relationship between the density of the base layer and the intermediate layer in each prototype example, in prototype examples 1-7, 20, and 22-24, which were rated "Good," the density of the base layer and the intermediate layer were equal, while in prototype examples 9-14 and 21, which were rated "Good," the density of the base layer was greater than the density of the intermediate layer. From this, it was found that when the density of the intermediate layer is greater than the density of the base layer, the laminate strength and transparency (haze) decrease. Therefore, it is considered preferable that the density of the base layer be greater than or equal to the density of the intermediate layer. In addition, in prototype example 16, which received an overall evaluation of "Unacceptable," the density of the intermediate layer was greater than the density of the base layer, similar to prototype example 17.

[0075] Prototype 25, which received an overall evaluation of "Unacceptable," differs from prototype 4, which received an overall evaluation of "Good," in that its sealant layer contains biomass-derived polyethylene resin. Furthermore, prototypes 1-7, 9-14, and 18-24, which all received an overall evaluation of "Good," do not contain biomass-derived polyethylene resin in their sealant layers. This indicates that the inclusion of biomass-derived polyethylene resin in the sealant layer reduces transparency (haze). Therefore, it is considered preferable not to add biomass-derived polyethylene resin to the sealant layer.

[0076] Furthermore, as can be seen from the comparison between prototype examples 1-7, 9-14, and 18-24, which received an overall evaluation of "Good," and reference example 1, which does not contain biomass-derived polyethylene resin, prototype examples 1-7, 9-14, and 18-24 obtained results comparable to reference example 1 in terms of laminate strength and transparency (haze) performance. Also, as can be seen from prototype examples 18-24, any of the biomass-derived polyethylene resins (A1) to (A3) could be suitably used. Therefore, it is considered preferable that the area ratio of the region with a molecular weight of 10,000 or less to the total peak area (distribution area) of the molecular weight distribution curve obtained from GPC measurement of biomass-derived polyethylene resin be less than 10%.

[0077] As illustrated and explained above, this sealant film containing biomass-derived polyethylene resin has a base layer composition of 5-50% by weight of biomass-derived polyethylene resin and 50-95% by weight of petroleum-derived polyethylene resin, an intermediate layer composition of 5-94% by weight of biomass-derived polyethylene resin and 6-95% by weight of petroleum-derived polyethylene resin, and the sealant layer is made of petroleum-derived polyethylene resin. The biomass-derived polyethylene resin has an area ratio of 2.5-9% of the total peak area in the region with a molecular weight of 10,000 or less in the molecular weight distribution curve obtained from GPC measurement in accordance with JIS K 7252-1 (2008), and the density (d1) of the base layer in accordance with JIS K 7112 is 0.919 g / cm³. 3Furthermore, the density of the base layer (d1) and the density of the intermediate layer (d2) satisfy d1 ≥ d2. As a result, even when biomass-derived polyethylene resin is added to the base layer (surface layer), a sealant film can be obtained that has comparable performance in terms of laminate strength, slipperiness, transparency, etc., to conventional sealant films that do not contain biomass-derived polyethylene resin in the surface layer.

[0078] Furthermore, this sealant film can be suitably used as a laminate film by laminating another resin film on the substrate layer side. Therefore, it can contribute to reducing environmental impact while possessing performance comparable to conventional films. [Industrial applicability]

[0079] The polyethylene-based sealant film and laminate film of the present invention possess performance comparable to conventional sealant films, even when the surface layer (base layer) of the sealant film contains a biomass-derived polyethylene resin. Therefore, it is expected to be used in new sealant films and the like, and is advantageous for the utilization of biomass resources. [Explanation of Symbols]

[0080] 10. Unoriented polyethylene resin film 20 Base material layer 30 Middle Class 40 sealant layer 50 Laminating Films 60 Other resin films

Claims

1. An unoriented polyethylene film having a base layer, an intermediate layer, and a sealant layer, The aforementioned substrate layer has a composition of 5 to 50% by weight of biomass-derived polyethylene resin and 50 to 95% by weight of petroleum-derived polyethylene resin. The aforementioned intermediate layer has a composition of 5 to 94% by weight of biomass-derived polyethylene resin and 6 to 95% by weight of petroleum-derived polyethylene resin. The sealant layer is made of a petroleum-derived polyethylene resin. The biomass-derived polyethylene resin is defined as having an area ratio of the region with a molecular weight of 10,000 or less in the molecular weight distribution curve obtained from GPC measurement in accordance with JIS K 7252-1 (2008) that is less than 10% of the total peak area. The density of the base layer (d1) and the density of the intermediate layer (d2) in accordance with JIS K 7112 are both 0.919 g / cm³ and the density of the entire layer is 0.918 g / cm³ or 0.919 g / cm³, or the density of the base layer (d1) and the density of the intermediate layer (d2) are d1 > d2. A polyethylene-based sealant film characterized by the following features.

2. A laminate film characterized in that another resin film is laminated on the substrate layer side of the polyethylene-based sealant film described in claim 1.

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