Packaging film

Abstract

To provide a packaging film with excellent dropping properties for an oil in water dispersion type content.SOLUTION: The packaging film of the present disclosure comprises a first resin layer containing a resin composition containing a polypropylene resin and a filler dispersed in the resin composition, and a ratio Y / X of a thickness X μm of the first resin layer and an average particle diameter of Y μm is 0.02 to 3.5.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for producing a packaging body, a film for packaging material, and a laminate film and a packaging material including the same. [Background technology]

[0002] Conventionally, packaging materials have been developed for various products, such as food, beverages, medicines, chemicals, etc. In particular, plastic materials that are excellent in water resistance, oil resistance, gas barrier properties, light weight, flexibility, design properties, etc., are used as packaging materials for contents such as liquids, semi-solids, or gel-like substances.

[0003] 2. Description of the Related Art For the purpose of providing higher functionality as a packaging material for contents such as liquids, semi-solids, or gel-like substances, packaging materials having the following configurations, for example, have been proposed. · Plastic laminates made by laminating multiple types of plastic substrates Composite laminates of paper, metal foil, inorganic materials, etc. with plastic substrates Composites made of plastic substrates treated with functional compositions

[0004] As one of the above-mentioned high functions, for example, a function to suppress adhesion of the contents to the inner surface of the packaging material, that is, the remaining of the contents, is required. More specifically, lid materials for containers of yogurt, jelly, syrup, etc.; retort food packaging materials for porridge, soup, curry, pasta sauce, etc.; and film materials for storage containers for liquids, semi-solids, gel-like substances, etc., such as chemicals and medicines, are required to have excellent liquid repellency so that the contents do not easily adhere to the inner surface and slide off easily. This is to suppress the contents from adhering to the inner surface, which causes waste due to not being able to use up all the contents, the occurrence of stains due to the adhesion of the contents, and the troublesome task of discharging the contents.

[0005] In response to these demands, for example, Patent Document 1 proposes a packaging container for storing cooked food that has a resin inner surface on which an oil film made of a high-viscosity oily liquid that meets certain conditions is formed. Patent Document 2 also proposes a packaging sheet that includes polyolefin particles with an average particle size D50 of 10 to 50 μm and a melting point of 100 to 180° C. and has a heat seal layer with a surface roughness Ra of 1.00 to 7.00 μm. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-18878 A [Patent Document 2] International Publication No. 2018 / 003978 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, a package containing curry, pasta sauce, etc., in a packaging material is subjected to retort treatment, for example, at a temperature of about 120°C. In the invention described in Patent Document 1, it is assumed that an oil film is formed by spraying a high-viscosity oily liquid (see paragraph

[0032] of Patent Document 1). This oil film is insufficient in durability against heat treatment such as retort treatment. In addition, the type of high-viscosity oily liquid to be used needs to be selected according to the contents, and it is considered necessary to create different formulations. On the other hand, the packaging sheet described in Patent Document 2 has insufficient sliding properties for oil-in-water dispersion-type contents (e.g., curry). This is presumably due to the relatively rough surface of the heat seal layer (surface roughness Ra: 1.00 to 7.00 μm).

[0008] The present disclosure provides a method for producing a package having excellent sliding properties for oil-in-water dispersion-type contents. The present disclosure also provides a film for packaging material, and a laminated film and packaging material including the same. In the present disclosure, the oil-in-water dispersion-type contents refer to contents containing water and lipids, and the water content is greater than the lipid content. The term "lipid" encompasses oils that are liquid at 20°C (room temperature) and fats that are solid at 20°C. Hereinafter, the oils contained in the oil-in-water dispersion-type contents and the fats that become liquid by the heat treatment applied to the package according to the present disclosure are collectively referred to as "oil" or "oil content". [Means for solving the problem]

[0009] One aspect of the present disclosure provides a method for manufacturing a package, the method comprising the steps of: (A) A step of preparing a packaging material having an innermost layer containing a resin composition including a polypropylene resin and a filler dispersed in the resin composition, the ratio Y / X of the thickness of the innermost layer X μm to the average particle diameter Y μm of the filler being 0.02 to 3.5. (B) preparing a package having the packaging material and an oil-in-water dispersion type content hermetically contained in the packaging material. (C) A step of heat-treating the package to absorb oil contained in the contents into the innermost layer.

[0010] When the ratio Y / X of the thickness X μm of the innermost layer to the average particle diameter Y μm of the filler is 0.02 to 3.5, the innermost surface of the packaging material has moderate unevenness (for example, arithmetic mean roughness Sa: 0.3 μm or more and less than 1.0 μm). In addition, in the (C) step, the innermost layer absorbs oil, or absorbs oil and swells, thereby increasing the lipophilicity of the innermost surface, and an oil film derived from the contents is easily formed between the innermost surface and the contents. Due to the synergistic effect of the unevenness of the innermost surface and the improvement in lipophilicity due to oil absorption, the oil film is stably formed between the innermost surface and the contents (see FIG. 2(b)). The presence of the oil film between the innermost surface and the contents prevents the contents from directly contacting the innermost surface, and provides excellent sliding properties for the contents containing water. In other words, the oil film derived from the oil-in-water dispersion type contents contributes to the development of excellent sliding properties. In addition, polypropylene resin usually contains a crystalline part and an amorphous part, and the amorphous part has a higher oil absorption than the crystalline part. In addition, polypropylene resin has a heat fusion property. The innermost layer containing polypropylene resin may play a role of a sealant film.

[0011] One aspect of the present disclosure provides a film for packaging material. The film for packaging material includes a first resin layer containing a resin composition containing a polypropylene resin and a filler dispersed in the resin composition, and a ratio Y / X of a thickness of the first resin layer X μm to an average particle diameter Y μm of the filler is 0.02 to 3.5. The film for packaging material is suitably applied to the method for producing the above-mentioned package. The polypropylene resin has heat-sealing properties. The film for packaging material including the first resin layer containing the polypropylene resin may be used as a sealant film.

[0012] The arithmetic mean roughness Sa of the first surface (the innermost surface of the packaging film) of the first resin layer is, for example, 0.3 μm or more and less than 1.0 μm from the viewpoint of stable oil film formation and excellent sliding properties of the contents. From the same viewpoint, the protruding peak volume Vmp of the first surface (the innermost surface of the packaging film) of the first resin layer is, for example, 0.08 to 0.3 μm 3 / μm 2 It is.

[0013] The packaging film may have a single-layer structure consisting of only the first resin layer, or may have a multi-layer structure including the first resin layer and the second resin layer. The second resin layer is provided, for example, on the second surface (the surface opposite to the first surface) of the first resin layer.

[0014] From the viewpoint of achieving even better sliding properties, the first resin layer may further contain at least one additive selected from the group consisting of the following resin materials (i) to (vii): The amorphous portion (rubber component) contained in these resin materials has the property of absorbing oil, and promotes the formation of a stable and uniform oil film during and after step (C), thereby further improving the sliding properties of the contents. (i) Block copolymer of polypropylene and polyethylene (ii) Polyethylene and ethylene-butylene block copolymers (iii) Polyethylene and ethylene-octene block copolymers (iv) Ethylene-based elastomers (v) Propylene-based elastomers (vi) Butene-based elastomers (vii) Reactor TPO

[0015] From the viewpoint of compatibility with the polypropylene resin contained in the first resin layer, the first resin layer preferably contains at least (v) a propylene-based elastomer among the above additives. From the viewpoint of exhibiting even better sliding properties after heat treatment, it is preferable that at least one of the softening point and melting point of the above additive is 130°C or less. The softening point of the additive may be a value measured using a thermomechanical analyzer (TMA) or a value in the manufacturer's catalog. The melting point of the additive may be a value measured using a differential scanning calorimeter (DSC) or a value in the manufacturer's catalog.

[0016] The present disclosure provides a laminated film including the film for packaging material, and a packaging material including the laminated film. The laminated film according to the present disclosure includes a substrate and the film for packaging material provided on the substrate, and the first resin layer is disposed on at least one of the outermost surfaces. The packaging material according to the present disclosure is suitably used for a package in which an oil-in-water dispersion type content is contained in a sealed state and is subjected to a heat treatment. Effect of the Invention

[0017] According to the present disclosure, there is provided a method for producing a package having excellent sliding properties for an oil-in-water dispersion type content. Also, according to the present disclosure, there is provided a film for packaging material, and a laminate film and a packaging material including the same. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a schematic diagram of one embodiment of a packaging material according to the present disclosure. [Diagram 2] 2(a) to 2(c) are schematic diagrams illustrating the mechanism by which the first resin layer exhibits sliding properties for oil-in-water dispersion-type contents. [Diagram 3] FIG. 3 is a schematic diagram showing Wenzel's model. [Figure 4] FIG. 4 is a cross-sectional view that illustrates a schematic diagram of another embodiment of a packaging material according to the present disclosure. [Diagram 5] 5(a) to 5(e) are schematic diagrams illustrating a method for evaluating the slipperiness of the inner surface of a packaging material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted. In addition, the dimensional ratios of the drawings are not limited to the illustrated ratios.

[0020] <Packaging material> FIG. 1 is a cross-sectional view showing a schematic diagram of one embodiment of the packaging material according to the present embodiment. The packaging material 10 shown in FIG. 1 includes a first resin layer 1 containing a polypropylene resin as a base material, a second resin layer 2, an adhesive layer 3, and a substrate 5. The first resin layer 1 is disposed on the outermost surface of the packaging material 10, and when a package (e.g., a retort pouch) is produced using the packaging material 10, the surface F1 (first surface) of the first resin layer 1 becomes the innermost surface of the package. In this embodiment, the first resin layer 1 and the second resin layer 2 constitute a film for packaging material. The second resin layer 2 is provided on the surface F2 (second surface) opposite to the surface F1 of the first resin layer 1.

[0021] The packaging material 10 is used to store oil-in-water dispersion type contents. The lipid content of the oil-in-water dispersion type contents is, for example, 0.1% by mass or more and less than 50% by mass, and may be 0.5 to 40% by mass or 1 to 20% by mass. The oil-in-water dispersion type contents in this embodiment contain a composition in which the water content is greater than the oil content (water-rich), and oil dispersed therein. Specific examples of oil-in-water dispersion type include curry, hayashi, pasta sauce (e.g., meat sauce), and pet food. The lipid content of curry is, for example, about 0.2 to 15% by mass, and the amount of water contained in curry is, for example, about 70 to 90% by mass.

[0022] With reference to Figs. 2(a) to 2(c), the mechanism by which the first resin layer 1 exhibits the sliding property for oil-in-water dispersion-type contents will be described. As shown in Fig. 2(a), the surface F1 of the first resin layer 1 has unevenness due to the filler 1b. In addition, the polypropylene resin which is the main component of the first resin layer 1 has the property of absorbing oil and swelling under the temperature conditions of retort treatment or boiling treatment. For this reason, when the oil-in-water dispersion-type contents C are subjected to a heat treatment while in contact with the surface F1 of the first resin layer 1, the oil C contained in the contents C is absorbed into the surface F1 of the first resin layer 1 as shown by the arrows in Fig. 2(b). OA part of the oil is absorbed into the first resin layer 1. This improves the lipophilicity of the surface F1. Due to the synergistic effect of the unevenness of the surface F1 and the improvement in lipophilicity due to the oil absorption, an oil film F is formed between the surface F1 and the contents C. O An oil film F is formed between the surface F1 and the contents C. O The presence of the oil film F prevents the contents C from directly contacting the surface F1. O As a result, as shown in Figure 2(c), the content C slides off the surface F1 simply by tilting the surface F1.

[0023] FIG. 3 is a cross-sectional view showing the Wenzel model applied when the surface F1 has a relatively small roughness. In this model, an oil droplet D dropped on the surface F1 O According to the study by the present inventors, the oil film F on the surface F1 penetrates into the recesses of the surface F1, and the entire surface F1 is wet. O The above mechanism by which the oil film is easily formed can be explained by the Wenzel model. On the other hand, when the roughness of the surface F1 is relatively large, it is considered that the height of the unevenness is likely to be greater than the height of the oil film. According to the study by the present inventors, when the surface roughness of the surface F1 is too large, the contents are likely to get caught on the unevenness, and the contents are prevented from sliding down (see Comparative Examples 2 and 3).

[0024] The first resin layer 1, the second resin layer 2, the base material 5 and the adhesive layer 3 which constitute the packaging material 10 will be described below. (First Resin Layer) The first resin layer 1 is a layer that exhibits the sliding property of the oil-in-water dispersion type contents by being subjected to a heat treatment (for example, a retort treatment and a boiling treatment) in a state where it is in contact with the oil-in-water dispersion type contents. The first resin layer 1 contains a resin composition 1a containing a polypropylene resin and a filler 1b dispersed in the resin composition 1a. The content of the polypropylene resin in the resin composition 1a is, for example, 75% by mass or more, and may be 80% by mass or more or 90% by mass or more. The resin composition 1a may be substantially composed of a polypropylene resin.

[0025] Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, and modified polypropylene. The block polypropylene here is different from the block copolymer (compatibilizer) of polypropylene and polyethylene (C1) described later, and generally has a structure in which EPR (rubber component) and polyethylene are dispersed in homopolypropylene at the polymerization stage. When a combination of block polypropylene and random polypropylene is used as the polypropylene resin, the mass ratio of the block polypropylene to the random polypropylene (block polypropylene / random polypropylene) is preferably 20 / 80 to 80 / 20, more preferably 40 / 60 to 60 / 40.

[0026] The modified polypropylene is obtained by graft-modifying polypropylene with an unsaturated carboxylic acid derivative component derived from, for example, an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like. In addition, modified polypropylene such as hydroxyl group-modified polypropylene or acrylic-modified polypropylene can also be used as the polypropylene resin. Examples of the α-olefin component used to obtain the propylene-based copolymer include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-pentene.

[0027] From the viewpoint of achieving even better sliding properties, the first resin layer 1 preferably further contains at least one additive selected from the group consisting of the following resin materials (i) to (vii): Reactor TPO (reactor thermoplactic polyolefin) is a type of olefin-based thermoplastic elastomer (TPO), and is composed of polypropylene as a base resin and a rubber component finely dispersed therein, for example, by adding a high concentration of a rubber component during polymerization. (i) Block copolymer of polypropylene and polyethylene (ii) Polyethylene and ethylene-butylene block copolymers (iii) Polyethylene and ethylene-octene block copolymers (iv) Ethylene-based elastomers (v) Propylene-based elastomers (vi) Butene-based elastomers (vii) Reactor TPO

[0028] The amount of the resin components (i) to (vii) added (the total amount when multiple resin components are added) is, for example, 30 parts by mass or less, preferably 1 to 25 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 15 parts by mass, relative to 100 parts by mass of polypropylene resin. The amorphous part (rubber component) contained in the resin components (i) to (vii) has the property of absorbing oil. Therefore, these resin components form a stable and uniform oil film F. O This promotes the formation of a gap (see FIG. 2(b)), thereby further improving the sliding properties of the contents C.

[0029] From the viewpoint of compatibility with the polypropylene resin contained in the first resin layer 1, the first resin layer 1 preferably contains at least (v) a propylene-based elastomer among the above resin components (additives) (i) to (vii). From the viewpoint of exhibiting even better sliding properties after heat treatment, at least one of the softening point and melting point of the above resin component is preferably 130° C. or lower, more preferably 120° C. or lower.

[0030] Examples of the filler 1b include organic fillers such as olefin fillers and acrylic fillers, inorganic fillers such as silica fillers, and porous fillers. Examples of the olefin fillers include the Mipelon (registered trademark) series manufactured by Mitsui Chemicals, Inc. and the CS series manufactured by Sumitomo Chemical Co., Ltd. Examples of the acrylic fillers include the MX series manufactured by Soken Chemical & Chemical Co., Ltd. Examples of the silica fillers include the Smooth Master series manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., the Silo Hobbic series manufactured by Fuji Silysia Chemical Co., Ltd., and the Adma Fine SO series manufactured by Admatechs Co., Ltd.

[0031] The average particle size (Y μm) of the filler 1b can be determined as follows. <Calculation by laser diffraction particle size distribution measurement> (1) The filler is dispersed in a dispersion medium. The dispersion medium is, for example, water or an organic solvent, and an appropriate one is selected depending on the type of filler. (2) Using a laser diffraction particle size distribution analyzer (product name: MT3300EXII, manufactured by Microtrackbell), the average particle size of the filler is calculated by the laser diffraction / scattering method. <Calculation based on microscopic observation> When the above-mentioned laser diffraction particle size distribution measurement is not suitable or difficult, the average particle size of the filler may be determined using an optical microscope such as a scanning electron microscope (SEM) or a laser microscope. For any particle within the field of view of the microscope, the longest and shortest diameters of the particle are measured, and the sum is divided by 2 to determine the particle size. The particle sizes of multiple particles are measured and calculated, and the average is regarded as the average particle size. The number of the above-mentioned arbitrary particles is preferably 10 or more.

[0032] The average particle size (Y μm) of the filler 1b is, for example, 1 to 100 μm, preferably 2 to 80 μm, more preferably 3 to 50 μm, and further preferably 5 to 30 μm. When the average particle size of the filler 1b is in the above range, it is possible to impart appropriate unevenness to the surface F1 of the first resin layer 1. The content of the filler 1b in the first resin layer 1 is, for example, 0.5 to 10 parts by mass, preferably 1 to 8 parts by mass, and more preferably 2 to 8 parts by mass, relative to 100 parts by mass of the polypropylene resin. When the content of the filler 1b is in the above range, it is possible to impart appropriate unevenness to the surface F1 of the first resin layer 1.

[0033] The thickness (X μm) of the first resin layer 1 is a value determined as follows. (1) First, the packaging material 10 is fixed with an embedding resin (acrylic resin) to prepare a structure. (2) A sample for cross-sectional observation is cut out from the structure using a microtome. (3) Observe the cross section of the cut sample for cross-sectional observation using a microscope (product name: VHX-1000, manufactured by Keyence Corporation). (4) The thickness is measured at three points along the thickness direction of the first resin layer 1 where no filler 1b is present, and the average value of the thicknesses at these three points is calculated as the thickness (X μm) of the first resin layer 1.

[0034] The thickness (X μm) of the first resin layer 1 is, for example, 2 to 100 μm, preferably 4 to 70 μm, more preferably 6 to 50 μm, and even more preferably 8 to 30 μm. When the thickness of the first resin layer 1 is within the above range, both the sliding property of the contents and the heat sealability can be achieved at a high level. The first resin layer 1 contains a polypropylene resin having heat fusion properties, and can also function as a sealant film. The heat sealability refers to a property that allows heat sealing under conditions of, for example, 100 to 200° C., 0.1 to 0.3 MPa, and 1 to 3 seconds.

[0035] The ratio Y / X of the thickness X μm of the first resin layer 1 to the average particle diameter Y μm of the filler 1b is 0.02 to 3.5. When the ratio Y / X is in the above range, when the first resin layer 1 is formed, appropriate unevenness is formed on the surface F1. If the ratio Y / X is less than 0.02, the unevenness of the surface F1 is not sufficiently formed, and as a result, the expression of the sliding property becomes insufficient. On the other hand, if the ratio Y / X exceeds 3.5, the unevenness is excessively formed on the surface F1, and this unevenness may hinder the sliding of the contents. The ratio Y / X is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.3 or more. The ratio Y / X is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 1.8 or less, and may be 1.5 or less or 1.2 or less.

[0036] The arithmetic mean roughness Sa of the surface F1 of the first resin layer 1 is preferably 0.3 μm or more and less than 1.0 μm, more preferably 0.4 μm or more and less than 1.0 μm, and even more preferably 0.5 μm or more and 0.98 μm or less, from the viewpoint of exhibiting excellent sliding properties. The arithmetic mean roughness Sa of the surface F1 can be adjusted, for example, by the blending amount and average particle size of the filler 1b, and the film formation conditions (thickness, temperature, etc.) of the first resin layer 1. The value of the "arithmetic mean roughness Sa" here means a value measured under the following conditions using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation). Magnification of objective lens: 50x Cutoff: None

[0037] The volume Vmp of the protruding peaks on the surface F1 of the first resin layer 1 is preferably 0.08 to 0.3 μm from the viewpoint of exhibiting excellent sliding properties. 3 / μm 2 and more preferably 0.08 to 0.25 μm. 3 / μm 2 and more preferably 0.1 to 0.2 μm. 3 / μm 2 The protruding peak volume Vmp of the surface F1 can be adjusted, for example, by the blending amount and average particle size of the filler 1b and the film formation conditions (thickness, temperature, etc.) of the first resin layer 1. Note that the value of the "protruding peak volume Vmp" here refers to a value measured under the following conditions using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation). - Load area ratio separating the core and protruding peaks: 10%

[0038] (Second Resin Layer) The second resin layer 2 is a layer provided between the first resin layer 1 and the substrate 5. The packaging material 10 further includes the second resin layer 2, which can improve the functions of the packaging material 10 (heat sealability, heat resistance and impact resistance, oxygen and water vapor barrier properties, etc.). For example, from the viewpoint of improving the heat sealability, it is preferable that the second resin layer 2 contains a thermoplastic resin. Specific examples of the thermoplastic resin include polyolefin resin, ethylene-α,β-unsaturated carboxylic acid copolymer or its ester or ion crosslinked product, ethylene-vinyl acetate copolymer or its saponification product, polyvinyl acetate or its saponification product, polycarbonate resin, thermoplastic polyester resin, ABS resin, polyacetal resin, polyamide resin, polyphenylene oxide resin, polyimide resin, polyurethane resin, polylactic acid resin, furan resin, and silicone resin. These thermoplastic resins can be used alone or in combination of two or more.

[0039] The thickness of the second resin layer 2 can be appropriately set depending on the application of the packaging material 10. The thickness of the second resin layer 2 is, for example, 1 to 300 μm, preferably 2 to 200 μm, more preferably 5 to 150 μm, and even more preferably 10 to 100 μm.

[0040] (base material) The substrate 5 is not particularly limited as long as it serves as a support and has durability against heat treatment, and examples thereof include resin films and metal foils. Examples of resin films include films containing at least one of polyolefins (e.g., polyethylene (PE), polypropylene (PP)), acid-modified polyolefins, polyesters (e.g., polyethylene terephthalate (PET)), polyamide (PA), polyvinyl chloride (PVC), cellulose acetate, and cellophane resins. This film may be a stretched film or a non-stretched film. Examples of metal foils include aluminum foil and nickel foil. The substrate 5 may be a laminate of a plurality of substrates made of different materials, and may include a coating layer or a metal deposition layer.

[0041] The thickness of the substrate 5 can be appropriately set depending on the application of the packaging material 10. The thickness of the substrate 5 is, for example, 1 to 500 μm, and may be 10 to 100 μm.

[0042] (adhesive layer) The adhesive layer 3 bonds the packaging film (a laminate of the first resin layer 1 and the second resin layer 2) to the substrate 5. Examples of the adhesive include polyurethane resins in which a difunctional or higher isocyanate compound is allowed to react with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol.

[0043] For the purpose of promoting adhesion, the adhesive layer 3 may contain a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like, in the above-mentioned polyurethane resin. Depending on the performance required for the adhesive layer 3, the above-mentioned polyurethane resin may contain various other additives and stabilizers.

[0044] The thickness of the adhesive layer 3 is, for example, 1 to 10 μm, and may be 3 to 7 μm, from the viewpoint of obtaining the desired adhesive strength, followability, processability, etc. Various polyols may be used alone or in combination of two or more. Methods for bonding the substrate 5 and the packaging film include, for example, lamination with an adhesive and lamination by heat treatment.

[0045] (Lamination method using adhesive) As a lamination method using an adhesive, various known lamination methods can be used, such as dry lamination, wet lamination, non-solvent lamination, etc. Examples of adhesives used in these lamination methods include the following.

[0046] (Lamination method using heat treatment) Lamination methods using heat treatment can be broadly classified into the following methods. (1) A method in which an adhesive resin is extruded between a liquid-repellent film that has been previously formed and the substrate 5, and then laminated. (2) A method in which the resin layer constituting the liquid-repellent film and an adhesive resin are co-extruded and laminated with the substrate 5. (3) A method in which the laminate substrate obtained by the above method (1) or (2) is further heated and pressed with a heated roll to bond the laminate substrate. (4) The laminate substrate obtained by the above method (1) or (2) is further stored in a high-temperature atmosphere, or passed through a drying / baking furnace in a high-temperature atmosphere.

[0047] Examples of adhesive resins used in the lamination method by heat treatment include acid-modified polyolefins, etc. In the above method, the substrate 5 and the liquid-repellent film are laminated by extrusion lamination, but it is also possible to coat the substrate 5 with an acid-modified polyolefin coating agent (dissolution type, dispersion type) in advance, without extrusion lamination, and then laminate the liquid-repellent film by heat treatment.

[0048] An adhesive primer (anchor coat) can be applied to the substrate 5, and materials that can be used include polyester, polyurethane, polyallylamine, polyethyleneimine, polybutadiene, ethylene-vinyl acetate copolymer, and chlorine-vinyl acetate. The adhesive primer may contain various curing agents and additives that can be used as adhesives, if necessary.

[0049] <Manufacturing method of packaging body> The method for producing the package according to this embodiment includes the following steps. (A) A step of preparing the packaging material 10 (B) A step of preparing a package P having a packaging material 10 and an oil-in-water dispersion type content C hermetically contained by the packaging material 10. (C) A step of subjecting the package P to a heat treatment (for example, a retort treatment or a boiling treatment) to absorb the oil contained in the contents C into the first resin layer 1.

[0050] According to the manufacturing method of this embodiment, due to the synergistic effect of the unevenness of the surface F1 of the first resin layer 1 and the improvement of the lipophilicity due to the oil absorption, an oil film F is formed between the surface F1 and the contents C. O is stably formed (see Fig. 2(b)). The presence of an oil film between the surface F1 and the contents C prevents the contents C from coming into direct contact with the surface F1, and allows the contents C, including moisture, to slide off smoothly (see Fig. 2(c)).

[0051] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, in the above embodiments, a film for packaging material composed of first and second resin layers 1 and 2 has been exemplified, but the film for packaging material may be a single layer composed of only the first resin layer 1. The packaging material 20 shown in FIG. 4 includes a first resin layer 1 (film for packaging material), an adhesive layer 3, and a substrate 5.

[0052] The present disclosure relates to the following inventions: [1] (A) preparing a packaging material having an innermost layer containing a resin composition including a polypropylene resin and a filler dispersed in the resin composition, the ratio Y / X of a thickness of the innermost layer X μm to an average particle diameter Y μm of the filler being 0.02 to 3.5; (B) preparing a package having the packaging material and an oil-in-water dispersion content hermetically contained by the packaging material; (C) a step of heat treating the package to absorb oil contained in the contents into the innermost layer; A method for producing a package comprising the steps of: [2] The method for producing a package described in [1], wherein the lipid content of the oil-in-water dispersion type content is 0.1% by mass or more and less than 50% by mass. [3] A first resin layer containing a resin composition including a polypropylene resin and a filler dispersed in the resin composition; The film for packaging materials, wherein the ratio Y / X of the thickness X μm of the first resin layer to the average particle diameter Y μm of the filler is 0.02 to 3.5. [4] The packaging film according to [3], wherein the first surface of the first resin layer, which is the innermost surface of the packaging film, has an arithmetic mean roughness Sa of 0.3 μm or more and less than 1.0 μm. [5] The volume Vmp of the protruding peaks on the first surface of the first resin layer that constitutes the innermost surface of the packaging film is 0.08 to 0.3 μm 3 / μm 2 The film for packaging materials according to [3] or [4], [6] The packaging film according to any one of [3] to [5], further comprising a second resin layer provided on a second surface of the first resin layer. [7] The film for packaging materials according to any one of [3] to [6], wherein the first resin layer further contains at least one additive selected from the group consisting of the following resin materials (i) to (vii): (i) Block copolymer of polypropylene and polyethylene (ii) Polyethylene and ethylene-butylene block copolymers (iii) Polyethylene and ethylene-octene block copolymers (iv) Ethylene-based elastomers (v) Propylene-based elastomers (vi) Butene-based elastomers (vii) Reactor TPO [8] The packaging film according to [7], wherein the first resin layer contains the (v) propylene-based elastomer. [9] The film for packaging materials according to [7] or [8], wherein at least one of the softening point and melting point of the additive is 130°C or lower.

[10] A substrate; The packaging film according to any one of claims 3 to 9 provided on the substrate; Equipped with A laminate film having the first resin layer disposed on at least one outermost surface.

[11]

[10] A packaging material comprising the laminated film described in the above.

[12] The packaging material according to

[11] , which is used for a package in which an oil-in-water dispersion type content is contained in a sealed state and subjected to a heat treatment.

[13] The packaging material according to

[12] , wherein the lipid content of the oil-in-water dispersion type content is 0.1% by mass or more and less than 50% by mass. EXAMPLES

[0053] The present disclosure will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0054] The following materials were prepared: <Polypropylene resin (A)> A1: Random PP resin (propylene-ethylene random copolymer, product name "Prime Polypro F744NP", manufactured by Prime Polymer Co., Ltd.) A2: Block PP resin (propylene-ethylene block copolymer, product name "Prime Polypro BC5FA", manufactured by Prime Polymer Co., Ltd.) A3: Block PP resin (propylene-ethylene block copolymer, product name "Prime Polypro BC3HF", manufactured by Prime Polymer Co., Ltd.)

[0055] <Filler (B)> B1: Olefin filler (average particle size: 2 μm, product name "CS18", manufactured by Sumitomo Chemical Co., Ltd.) B2: Olefin filler (average particle size: 10 μm, product name "Mipelon PM-1010", b-PP masterbatch, manufactured by Mitsui Chemicals, Inc.) B3: Olefin filler (average particle size: 30 μm, product name "Mipelon XM-220", manufactured by Mitsui Chemicals, Inc.) B4: Olefin filler (average particle size: 60 μm, product name "Mipelon XM-330", manufactured by Mitsui Chemicals, Inc.) B5: Silica filler (average particle size: 2 μm, product name "Smooth Master S PE2000", manufactured by Dainichiseika Color & Chemicals Co., Ltd.) B6: Silica filler (average particle size: 8 μm, product name "Silo Hobic 4004", manufactured by Fuji Silysia Chemical Co., Ltd.) B7: Acrylic filler (average particle size: 30 μm, product name "MX-3000", manufactured by Soken Chemical & Engineering Co., Ltd.) The average particle size of the filler can be determined by measuring the length in the longitudinal direction and the length in the transverse direction for any 10 particles, summing the measured lengths, dividing the sum by 2, and averaging the values ​​obtained.

[0056] <Additives (C)> C1: Block copolymer of polypropylene and polyethylene C2: Polyethylene and ethylene-butylene block copolymer C3: Polyethylene and ethylene-octene block copolymer C4: PE elastomer (product name "Tafmer A4085S", manufactured by Mitsui Chemicals, Inc.) C5a: PP elastomer (product name "Tufmer PN3560", manufactured by Mitsui Chemicals, Inc.) C5b: PP elastomer (product name "Tufmer PN2060", manufactured by Mitsui Chemicals, Inc.) C5c: PP elastomer (product name "Tufmer PN2070", manufactured by Mitsui Chemicals, Inc.) C5d: PP elastomer (product name "Tufmer XM7070", manufactured by Mitsui Chemicals, Inc.) C6: PB-based elastomer (product name "Tafmer BL4000", manufactured by Mitsui Chemicals, Inc.) C7: Reactor TPO (product name "Catalloy C200F", manufactured by Basell)

[0057] <Production of packaging materials> (Examples 1 to 42 and Comparative Examples 1 to 5) Using a co-extruder, a two-layered film (sealant film) for packaging material was produced, which had a first resin layer having the composition shown in Tables 1 to 8 and a second resin layer made of A3 (block PP resin). The obtained film and a 38 μm thick PET film (product name "Embret", manufactured by Unitika Ltd.) as a substrate were dry laminated using a polyurethane adhesive (manufactured by Mitsui Chemicals, Inc.) and aged at 50° C. for 5 days to obtain a packaging material. In the examples and comparative examples except Comparative Example 3, the film was formed so that the total thickness of the first resin layer and the second resin layer was 60 μm. In Comparative Example 3, the film was formed so that the first resin layer was 150 μm thick and the second resin layer was 50 μm thick.

[0058] <Measurement of arithmetic mean roughness Sa> The arithmetic mean roughness Sa of the first resin layer was measured under the following conditions using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation). Magnification of objective lens: 50x Cutoff: None

[0059] <Measurement of protruding peak volume Vmp> The protruding peak volume Vmp of the first resin layer was measured under the following conditions using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation). - Load area ratio separating the core and protruding peaks: 10%

[0060] <Slip resistance evaluation> (Evaluation of residual liquid after retort processing) The packaging materials obtained in the examples and comparative examples were evaluated for slipping after retort processing by the method shown in Fig. 5(a) to Fig. 5(e). First, two pieces of packaging material 30 were prepared by cutting the packaging material to 150 mm length x 138 mm width. The two packaging materials 30 were stacked so that the first resin layer of each was on the inside, and the three sides were sealed using a heat sealer. As shown in Fig. 5(a), a pouch was produced in which a sealed portion 30a was formed on three sides and one side was open. The heat sealing of the three sides was performed under conditions of 190°C, 0.03 MPa, and 2 seconds, and the width of the sealed portion 30a was 10 mm. Next, 180 g of curry (product name "Bon Curry Gold Medium Spicy", lipid content 7.0 g / 180 g, manufactured by Otsuka Foods Co., Ltd.) was poured from the opening of the pouch (see Fig. 5(b)). After that, the opening (the remaining side) was sealed using a heat sealer. As shown in Fig. 5(c), a sealed portion 30b was formed on the remaining side, and a package P was produced in which all four sides were sealed and the contents C were contained. The opening was heat sealed under conditions of 190°C, 0.03 MPa, and 2 seconds, and the width of the sealed portion 30b was 10 mm.

[0061] The package P was placed in a high-temperature, high-pressure cooking and sterilizing device (manufactured by Hitachi Capital Corporation), and then retort-treated with high-temperature steam. The retort-treatment was carried out under the following conditions. Pressure: 0.2MPa ·Temperature 121℃ Processing time: 30 minutes After the retort treatment, the package P was subjected to a hot water bath treatment at 100°C for 5 minutes. After these heat treatments, the top of the package P was cut to form a spout (see FIG. 5(d)). Next, the pouch was turned upside down and the spout was held in a position tilted 45° from the horizontal for 10 seconds, allowing the contents C to be discharged into the container 50, and the amount discharged was weighed using the balance 60 (see FIG. 5(e)). The residual liquid volume (%) was calculated from the weighed amount discharged using the following formula. Residual liquid amount (%)={(180-discharge amount) / 180}×100 The measurement was carried out three times, and the residual liquid amount was evaluated based on the average residual liquid amount of the three measurements according to the following evaluation criteria. Tables 1 to 8 show the residual liquid amount and the results of the residual liquid evaluation. A: Average residual liquid volume is less than 6.5% B: Average residual liquid amount is 6.5% or more and less than 8.0% C: Average residual liquid amount is 8.0% or more and less than 10.0% D: Average residual liquid amount is 10.0% or more

[0062] (Appearance evaluation after retort processing) In the residual liquid evaluation, the behavior of the curry when it was discharged from the pouch was visually observed, and the appearance was evaluated according to the following evaluation criteria. The results are shown in Tables 1 to 8. A: It appears to slide off cleanly, with almost no adhesion to the film. B: Slippage is observed and adhesion to the film is small. C: Some sliding can be seen, but the film remains attached. D: No signs of slipping.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] [Table 4]

[0067] [Table 5]

[0068] [Table 6]

[0069] [Table 7]

[0070] [Table 8] [Industrial Applicability]

[0071] According to the present disclosure, there is provided a method for producing a package having excellent sliding properties for an oil-in-water dispersion type content. Also, according to the present disclosure, there is provided a film for packaging material, and a laminate film and a packaging material including the same. [Explanation of symbols]

[0072] 1...first resin layer (innermost layer), 1a...resin composition, 1b...filler, 2...second resin layer, 3...adhesive layer, 5...substrate, 10, 20...packaging material (laminated film), C...contents, C O …Oil, F1…Surface (first surface, innermost surface), F2…Surface (second surface), F O ...oil film, P...packaging body

Claims

[Claim 1] A first resin layer containing a resin composition including a polypropylene resin and a filler dispersed in the resin composition, A packaging film, wherein a ratio Y / X of a thickness X μm of the first resin layer to an average particle diameter Y μm of the filler is 0.02 to 3.5.

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