Method for manufacturing a packaging body, film for packaging materials, and laminated film and packaging material comprising the same.

Abstract

A packaging body manufacturing method according to the present disclosure includes: (A) a step for preparing a packaging material comprising an innermost layer that contains a resin composition including a polypropylene resin and that also contains a filler dispersed in the resin composition, the ratio X / Y between the thickness of the innermost layer, X μm, and the average particle diameter of the filler, Y μm, being 0.02 to 3.5; (B) a step for producing a packaging body that has the packaging material and oil-in-water type content housed by being hermetically sealed in the packaging material; and (C) a step for heat-treating the packaging body so that the oil included in the content is absorbed into the innermost layer.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing a packaging body, a film for packaging materials, and a laminated film and packaging material comprising the same. [Background technology]

[0002] Conventionally, packaging materials have been developed for a wide range of products, including food, beverages, pharmaceuticals, and chemicals, tailored to the specific contents of each product. In particular, plastic materials with excellent water resistance, oil resistance, gas barrier properties, lightweight nature, flexibility, and aesthetic appeal are used for packaging liquids, semi-solids, or gel-like substances.

[0003] To provide higher functionality as a packaging material for liquids, semi-solids, or gel-like substances, packaging materials with the following configurations have been proposed, for example. • A plastic laminate made by layering multiple types of plastic substrates. • Composite laminates of paper, metal foil, inorganic materials, etc., and plastic substrates • A composite material in which a plastic substrate has been treated with a functional composition.

[0004] One of the high-performance features mentioned above is the ability to prevent contents from adhering to the inner surface of the packaging material, that is, to suppress the residue of contents. More specifically, lids for containers of yogurt, jelly, syrup, etc.; packaging materials for retort foods such as porridge, soup, curry, and pasta sauce; and film materials for storage containers of liquids, semi-solids, and gel-like substances such as chemicals and pharmaceuticals are required to have excellent liquid-repellent properties that make it difficult for contents to adhere to the inner surface and allow them to slide off easily. This is to prevent waste caused by contents adhering to the inner surface and being unable to use all of the contents, to prevent soiling due to adhesion of contents, and to reduce the effort required for disposing of the contents.

[0005] In response to these requirements, for example, Patent Document 1 proposes a packaging container for containing cooked food having a resin inner surface and an oil film made of a high-viscosity oily liquid that satisfies predetermined conditions formed on the inner surface. Furthermore, Patent Document 2 proposes a packaging sheet comprising a heat-seal layer containing polyolefin particles with an average particle size D50 of 10 to 50 μm and a melting point of 100 to 180°C, and a surface roughness Ra of 1.00 to 7.00 μm. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-18878 [Patent Document 2] International Publication No. 2018 / 003978 [Overview of the project] [Problems that the invention aims to solve]

[0007] Incidentally, packaging materials containing curry, pasta sauce, etc., are subjected to retort processing at temperatures of around 120°C, for example. 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 Patent Document 1, paragraph

[0032] ). This oil film has insufficient durability against heat treatment such as retort processing. Furthermore, it is necessary to select the type of high-viscosity oily liquid to be used 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 dispersed contents (for example, curry). This is presumed to be due to the relatively rough surface of the heat seal layer (surface roughness Ra: 1.00~7.00 μm).

[0008] This disclosure provides a method for manufacturing a packaging material that exhibits excellent sliding properties for oil-in-water dispersed contents. This disclosure also provides a film for packaging materials, a laminated film equipped therewith, and a packaging material. In this disclosure, "oil-in-water dispersed contents" means contents containing water and lipids, where the water content is greater than the lipid content. "Lipids" is a concept that includes oils that are liquid at 20°C (room temperature) and fats that are solid at 20°C. Hereinafter, the oil contained in the oil-in-water dispersed contents and the fats that become liquid by the heat treatment applied to the packaging material according to this disclosure will be collectively referred to as "oil" or "oil content". [Means for solving the problem]

[0009] One aspect of this disclosure provides a method for manufacturing a package. This manufacturing method includes the following steps: (A) A process of preparing a packaging material having an innermost layer containing a resin composition containing polypropylene resin and a filler dispersed in the resin composition, wherein the ratio Y / X of the thickness of the innermost layer X μm to the average particle size Y μm of the filler is 0.02 to 3.5. (B) A process for producing a package having the above-mentioned packaging material and an oil-in-water dispersion type contents contained in a sealed state by the above-mentioned packaging material. (C) A process of heat-treating the above packaging to allow the oil contained in the contents to be absorbed into the innermost layer.

[0010] The ratio Y / X of the thickness X μm of the innermost layer to the average particle size Y μm of the filler is 0.02 to 3.5, which gives the innermost surface of the packaging material an appropriate level of unevenness (for example, arithmetic mean roughness Sa: 0.3 μm or more and less than 1.0 μm). Furthermore, in step (C), the innermost layer absorbs oil, or swells after absorbing oil, increasing the lipophilicity of the innermost surface, making it easier for an oil film derived from the contents to form 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 above oil film is stably formed between the innermost surface and the contents (see Figure 2(b)). The presence of an oil film between the innermost surface and the contents suppresses direct contact between the contents and the innermost surface, and also provides excellent sliding properties for contents containing moisture. In other words, the oil film derived from the oil-in-water dispersed contents contributes to the development of excellent sliding properties. Polypropylene resin typically contains both crystalline and amorphous regions, with the amorphous region having higher oil absorption than the crystalline region. Furthermore, polypropylene resin is heat-sealable. The innermost layer containing the polypropylene resin may function as a sealant film.

[0011] One aspect of this disclosure provides a film for packaging materials. This film for packaging materials comprises a first resin layer containing a resin composition comprising a polypropylene resin and a filler dispersed in the resin composition, 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. This film for packaging materials is suitably applied to the above-mentioned method for manufacturing packaging. The polypropylene resin is heat-sealable. The film for packaging materials comprising 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 (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 a similar viewpoint, the volume Vmp of the protruding peaks on the first surface (innermost surface of the packaging film) of the first resin layer is, for example, 0.08 to 0.3 μm. 3 / μm 2 That is the case.

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

[0014] From the perspective of further improving the sliding property, the first resin layer may further contain at least one additive selected from the group consisting of the following resins (i) to (vii). The amorphous part (rubber component) contained in these resin materials has the property of absorbing oil, and in step (C) and thereafter, it promotes the formation of a stable and uniform oil film, thereby further improving the sliding property of the content. (i) Block copolymer of polypropylene and polyethylene (ii) Block copolymer of polyethylene and ethylene-butylene (iii) Block copolymer of polyethylene and ethylene-octene (iv) Ethylene-based elastomer (v) Propylene-based elastomer (vi) Butene-based elastomer (vii) Reactor TPO

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

[0016] The present disclosure provides a laminated film including the above-described film for packaging materials and a packaging material made of this laminated film. The laminated film according to the present disclosure includes a base material and the above-described film for packaging materials provided on the base material, 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 heat-treated.

Advantages of the Invention

[0017] According to the present disclosure, a method for manufacturing a package excellent in the slipperiness of an oil-in-water dispersion type content is provided. Further, according to the present disclosure, a film for packaging materials, a laminated film including the same, and a packaging material are provided.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an embodiment of a packaging material according to the present disclosure. [Figure 2] FIGS. 2(a) to 2(c) are schematic views for explaining a mechanism by which the first resin layer exhibits slipperiness with respect to an oil-in-water dispersion type content. [Figure 3] FIG. 3 is a schematic view showing the Wenzel model. [Figure 4] FIG. 4 is a cross-sectional view schematically showing another embodiment of a packaging material according to the present disclosure. [Figure 5] FIGS. 5(a) to 5(e) are schematic views for explaining a method for evaluating the slipperiness of the inner surface of a packaging material.

Embodiments for Carrying out the Invention

[0019] Hereinafter, embodiments 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 overlapping descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the ratios shown in the drawings.

[0020] <Packaging Material> Figure 1 is a schematic cross-sectional view showing one embodiment of the packaging material according to this embodiment. The packaging material 10 shown in Figure 1 comprises a first resin layer 1 containing polypropylene resin as a base material, a second resin layer 2, an adhesive layer 3, and a base material 5. The first resin layer 1 is located on the outermost surface of the packaging material 10, and when a package (for example, a retort pouch) is made 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 packaging material film is composed of the first resin layer 1 and the second resin layer 2. 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 contain oil-in-water dispersion contents. The lipid content of the oil-in-water dispersion 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 contents in this embodiment include 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 dispersions include curry, Hayashi rice, pasta sauce (e.g., meat sauce), and pet food. The lipid content in curry is, for example, about 0.2 to 15% by mass, and the water content in curry is, for example, about 70 to 90% by mass.

[0022] Referring to Figures 2(a) to 2(c), the mechanism by which the first resin layer 1 exhibits sliding properties for oil-in-water dispersed contents will be explained. As shown in Figure 2(a), the surface F1 of the first resin layer 1 has irregularities caused by the filler 1b. Furthermore, 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 or boiling treatment. Therefore, when the oil-in-water dispersed contents C are subjected to heat treatment while in contact with the surface F1 of the first resin layer 1, the oil C contained in the contents C will swell, as schematically shown by the arrows in Figure 2(b). OA portion of it 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 oil absorption, an oil film F is formed between the surface F1 and the contents C. O A stable oil film F is formed between the surface F1 and the contents C. O The presence of the oil film F suppresses direct contact between the contents C and the surface F1, and also prevents the contents C from coming into direct contact with the surface F1. O The contents C become slippery at the interface. Therefore, as shown in Figure 2(c), the contents C slide off the surface F1 simply by tilting the surface F1.

[0023] Figure 3 is a cross-sectional view showing Wenzel's model, which is applied when the surface roughness of F1 is relatively small. In this model, an oil droplet D is dropped onto the surface F1. O The oil penetrates into the recesses of surface F1, and the entire surface F1 is wet. According to the inventors' studies, an oil film F O The above mechanism that facilitates the formation of this can be explained by Wenzel's model. On the other hand, when the surface roughness of surface F1 is relatively large, the height of the irregularities tends to be higher than the height of the oil film. According to our research, if the surface roughness of surface F1 is too large, the contents tend to get caught on the irregularities, and the sliding of the contents is inhibited (see Comparative Examples 2 and 3).

[0024] The following describes the first resin layer 1, the second resin layer 2, the base material 5, and the adhesive layer 3 that constitute the packaging material 10. (First resin layer) The first resin layer 1 is a layer that exhibits the sliding properties of the oil-in-water dispersion contents when subjected to heat treatment (e.g., retort treatment and boiling treatment) while in contact with the contents. The first resin layer 1 contains a resin composition 1a containing polypropylene resin and a filler 1b dispersed in the resin composition 1a. The polypropylene resin content 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 polypropylene resin.

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

[0026] Modified polypropylene can be obtained by graft-modifying polypropylene with unsaturated carboxylic acid derivative components, such as unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids. Alternatively, modified polypropylenes such as hydroxyl-modified polypropylene and acrylic-modified polypropylene can be used as the polypropylene resin. Examples of α-olefin components used to obtain propylene copolymers include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-pentene.

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

[0028] The addition amount of the resin components in (i) to (vii) above (when adding a plurality of resin components, the total amount) 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 still more preferably 3 to 15 parts by mass with respect to 100 parts by mass of the polypropylene resin. The amorphous part (rubber component) contained in the resin components of (i) to (vii) has the property of absorbing oil. Therefore, these resin components promote the formation of a stable and uniform oil film F O (see Fig. 2(b)), thereby further improving the slipperiness of the content 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) propylene-based elastomer among the resin components (additives) in (i) to (vii) above. From the viewpoint of exhibiting more excellent slipperiness after heat treatment, at least one of the softening point and melting point of the resin component is preferably 13℃ or lower, and more preferably 120℃ 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 filler 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 filler include the MX series manufactured by Soken Chemical & Engineering Co., Ltd. Examples of the silica filler include the Smooth Master series manufactured by Dainichi Seika Kogyo Co., Ltd., the Cylohbic series manufactured by Fuji Silysia Chemical Ltd., and the Admafine SO series manufactured by Admatechs Co., Ltd.

[0031] The average particle size (Yμm) of filler 1b can be determined as follows. <Calculated using laser diffraction particle size distribution measurement> (1) Disperse the filler in a dispersion medium. The dispersion medium may be, for example, water or an organic solvent, and an appropriate one should be selected depending on the type of filler. (2) Using a laser diffraction particle size distribution analyzer (product name: MT3300EXII, manufactured by Microtrac Bell), the average particle size of the filler is calculated by laser diffraction and scattering. <Calculation based on microscopic observation> If the above-described laser diffraction particle size distribution measurement is unsuitable or difficult, the average particle diameter of the filler may be determined using an optical microscope such as a scanning electron microscope (SEM) or laser microscope. For any particle within the field of view of the microscope, the lengths of the longest and shortest diameters of the particle are measured, and the sum of these lengths divided by 2 is taken as the particle diameter. The particle diameters of multiple particles are measured and calculated, and their average is considered as the average particle diameter. It is preferable that the number of arbitrary particles is 10 or more.

[0032] The average particle size (Yμm) of filler 1b is, for example, 1 to 100 μm, preferably 2 to 80 μm, more preferably 3 to 50 μm, and even more preferably 5 to 30 μm. Having the average particle size of filler 1b within this range allows for appropriate unevenness to be imparted to the surface F1 of the first resin layer 1. The content of 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, per 100 parts by mass of polypropylene resin. Having the content of filler 1b within this range allows for appropriate unevenness to be imparted to the surface F1 of the first resin layer 1.

[0033] The thickness (X μm) of the first resin layer 1 is the value obtained as follows: (1) First, the packaging material 10 is fixed with embedding resin (acrylic resin) to prepare the structure. (2) A sample for cross-sectional observation is cut from the structure using a microtome. (3) Observe the cross-section of the sample cut out for cross-sectional observation using a microscope (product name: VHX-1000, manufactured by Keyence Corporation). (4) Measure the thickness of the first resin layer 1 at three locations where filler 1b is not present, along the thickness direction of the first resin layer 1, and calculate the average of the thicknesses at these three locations as the thickness of the first resin layer 1 (X μm).

[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. By having the thickness of the first resin layer 1 within the above range, both the sliding properties of the contents and the heat sealability can be achieved at a high level. The first resin layer 1 contains a polypropylene resin that has heat-sealing properties and can also function as a sealant film. Heat sealability refers, for example, to the property that heat sealing is possible under conditions of 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 size Y μm of the filler 1b is 0.02 to 3.5. When the ratio Y / X is within the above range, an appropriate amount of unevenness is formed on the surface F1 when the first resin layer 1 is formed. If the ratio Y / X is less than 0.02, the unevenness of the surface F1 is not sufficiently formed, resulting in insufficient sliding properties. On the other hand, if the ratio Y / X exceeds 3.5, excessive unevenness is 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, even more preferably 1.8 or less, and may also 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 amount and average particle size of the filler 1b, and the film formation conditions of the first resin layer 1 (thickness and temperature, etc.). The value of "arithmetic mean roughness Sa" as used herein refers to the measurement value obtained using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation) under the following conditions. • Objective lens magnification: 50x • Cut-off: None

[0037] From the viewpoint of exhibiting excellent sliding properties, the volume Vmp of the protruding peaks F1 on the surface of the first resin layer 1 is preferably 0.08 to 0.3 μm. 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 volume Vmp of the protruding peaks on surface F1 can be adjusted, for example, by the amount and average particle size of filler 1b, and the film formation conditions of the first resin layer 1 (thickness and temperature, etc.). The value of "volume Vmp of the protruding peaks" referred to here means the measurement value obtained using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation) under the following conditions. • 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 base material 5. By further comprising the second resin layer 2 in the packaging material 10, the functionality of the packaging material 10 (heat sealability, heat resistance and impact resistance, oxygen and water vapor barrier properties, etc.) can be improved. For example, from the viewpoint of improving heat sealability, it is preferable that the second resin layer 2 contains a thermoplastic resin. Specific examples of thermoplastic resins include polyolefin resins, ethylene-α,β unsaturated carboxylic acid copolymers or their esters or ion crosslinked products, ethylene-vinyl acetate copolymers or their saponified products, polyvinyl acetate or its saponified products, polycarbonate resins, thermoplastic polyester resins, ABS resins, polyacetal resins, polyamide resins, polyphenylene oxide resins, polyimide resins, polyurethane resins, polylactic acid resins, furan resins, and silicone resins. These thermoplastic resins can be used individually or in combination of two or more.

[0039] The thickness of the second resin layer 2 can be appropriately set according to the application of the packaging material 10. For example, the thickness of the second resin layer 2 is 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 base material 5 is not particularly limited as long as it serves as a support and has durability against heat treatment, and examples include resin films and metal foils. Examples of resin films include films containing at least one of polyolefins (e.g., polyethylene (PE), polypropylene (PP), etc.), acid-modified polyolefins, polyesters (e.g., polyethylene terephthalate (PET), etc.), polyamides (PA), polyvinyl chloride (PVC), cellulose acetate, and cellophane resin. This film may be a stretched film or an unstretched film. Examples of metal foils include aluminum foil and nickel foil. The base material 5 may be a laminate of multiple base materials of different materials, and may include a coating layer or a metal vapor deposition layer.

[0041] The thickness of the base material 5 can be set appropriately depending on the application of the packaging material 10. For example, the thickness of the base material 5 may be 1 to 500 μm, or it may be 10 to 100 μm.

[0042] (adhesive layer) The adhesive layer 3 adheres the packaging film (a laminate of the first resin layer 1 and the second resin layer 2) to the substrate 5. Examples of adhesives include polyurethane resins obtained by reacting a bifunctional or higher isocyanate compound with a main component such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol.

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

[0044] The thickness of the adhesive layer 3 is, for example, 1 to 10 μm, or 3 to 7 μm, from the viewpoint of obtaining the desired adhesive strength, conformability, and processability. Various polyols may be used individually or in combination of two or more. As a method of bonding the substrate 5 and the packaging film, for example, lamination with adhesive and lamination by heat treatment can be mentioned.

[0045] (Lamination method using adhesive) Various known lamination methods using adhesives can be used, including dry lamination, wet lamination, and non-solvent lamination. Examples of adhesives used in these lamination methods include the following:

[0046] (Lamination method using heat treatment) The following are some of the main methods for lamination using heat treatment. (1) A method of laminating an adhesive resin by extruding it between a pre-formed liquid-repellent film and a substrate 5. (2) A method of co-extruding a resin layer constituting a liquid-repellent film with an adhesive resin and laminating it with a substrate 5. (3) A method of bonding laminate substrates obtained by the method of (1) or (2) above by further heating and pressing them with a hot roll. (4) A method of further storing the laminate substrate obtained by the method of (1) or (2) above in a high-temperature atmosphere, or passing it through a drying and baking furnace in a high-temperature atmosphere.

[0047] Adhesive resins used in heat-treated lamination methods include acid-modified polyolefins. In addition, although the above method involves laminating the substrate 5 and the liquid-repellent film by extrusion lamination, it is also possible to pre-coat the substrate 5 with an acid-modified polyolefin-based coating agent (dissolved type, dispersed type) without performing extrusion lamination, and then laminate the liquid-repellent film by heat treatment.

[0048] The substrate 5 may also be provided with an adhesive primer (anchor coat), and suitable materials for this primer include polyester, polyurethane, polyallylamine, polyethyleneimine, polybutadiene, ethylene-vinyl acetate copolymer, and chlorine-vinyl acetate. The adhesive primer may also contain various curing agents and additives that can be used as adhesives, as needed.

[0049] <Manufacturing method for packaging> The manufacturing method for the packaging according to this embodiment includes the following steps. (A) Process of preparing the packaging material 10 (B) A process for producing a package P having a packaging material 10 and an oil-in-water dispersion type contents C contained in a sealed state by the packaging material 10. (C) A process in which the oil contained in the contents C is absorbed into the first resin layer 1 by heat treatment (e.g., retort treatment or boiling treatment) of the packaging P.

[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 lipophilicity due to oil absorption, an oil film F is formed between the surface F1 and the contents C. O A stable layer is formed (see Figure 2(b)). The presence of an oil film between the surface F1 and the contents C prevents the contents C from directly contacting the surface F1, and also provides excellent sliding properties for the contents C containing moisture (see Figure 2(c)).

[0051] Although 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 packaging film composed of first and second resin layers 1 and 2 was exemplified, but the packaging film may be a single layer consisting only of the first resin layer 1. The packaging material 20 shown in Figure 4 comprises a first resin layer 1 (packaging film), an adhesive layer 3, and a base material 5. [Examples]

[0052] The present disclosure will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0053] 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.)

[0054] <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 "Miperon 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 Dainichi Seika Kogyo Co., Ltd.) • B6: Silica filler (average particle size: 8 μm, product name "Silohobic 4004", manufactured by Fuji Silicia Chemical Co., Ltd.) • B7: Acrylic filler (average particle size: 30 μm, product name "MX-3000", manufactured by Soken Chemical Co., Ltd.) The average particle size of the filler can be determined by measuring the length in the vertical and horizontal directions of any 10 particles, dividing the sum of these lengths by 2, and averaging the resulting values.

[0055] <Additive (C)> • C1: Block copolymer of polypropylene and polyethylene • C2: Block copolymer of polyethylene and ethylene-butylene • C3: Block copolymer of polyethylene and ethylene-octene • C4: PE-based elastomer (product name "Toughmer A4085S", manufactured by Mitsui Chemicals, Inc.) • C5a: PP-based elastomer (product name "Toughmer PN3560", manufactured by Mitsui Chemicals, Inc.) • C5b: PP-based elastomer (product name "Toughmer PN2060", manufactured by Mitsui Chemicals, Inc.) • C5c: PP-based elastomer (product name "Toughmer PN2070", manufactured by Mitsui Chemicals, Inc.) • C5d: PP-based elastomer (product name "Toughmer XM7070", manufactured by Mitsui Chemicals, Inc.) • C6: PB-type elastomer (product name "Toughmer BL4000", manufactured by Mitsui Chemicals, Inc.) • C7: Reactor TPO (product name "Catalloy C200F", manufactured by Basell)

[0056] <Manufacturing of packaging materials> (Examples 1-42 and Comparative Examples 1-5) Using a co-extruder, a two-layer packaging film (sealant film) was prepared, comprising a first resin layer with the composition shown in Tables 1-8 and a second resin layer made of A3 (block PP resin). The obtained film and a 38 μm thick PET film (product name "Emblet," manufactured by Unitika Ltd.) 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 all examples except Comparative Example 3, the films were prepared so that the total thickness of the first and second resin layers was 60 μm. In Comparative Example 3, the first resin layer was 150 μm thick and the second resin layer was 50 μm thick.

[0057] <Measurement of arithmetic mean roughness Sa> The arithmetic mean roughness Sa of the first resin layer was measured using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation) under the following conditions. • Objective lens magnification: 50x • Cut-off: None

[0058] <Measurement of the volume Vmp of the protruding peak> The volume Vmp of the protruding peak of the first resin layer was measured using a laser microscope (product name "OLS-4000", manufactured by Olympus Corporation) under the following conditions. • Load area ratio separating the core and protruding peaks: 10%

[0059] <Slip resistance evaluation> (Evaluation of residual liquid after retort processing) The slipperiness of the packaging materials obtained in the examples and comparative examples was evaluated after retort processing using the methods shown in Figures 5(a) to 5(e). First, two pieces of packaging material 30 were prepared by cutting the packaging material to 150 mm in length and 138 mm in width. The two pieces of packaging material 30 were stacked so that the first resin layer of each was on the inside, and three sides were sealed using a heat sealer. As shown in Figure 5(a), a pouch was made in which sealed portions 30a were formed on three sides and one side was open. The heat sealing of the three sides was performed under the conditions of 190°C, 0.03 MPa, and 2 seconds, and the width of the sealed portion 30a was set to 10 mm. Next, 180 g of curry (product name "Bon Curry Gold Medium Spicy", fat content 7.0 g / 180 g, manufactured by Otsuka Foods Co., Ltd.) as the contents C was poured into the opening of the pouch (see Figure 5(b)). After that, the opening (the remaining side) was sealed using a heat sealer. As shown in Figure 5(c), a seal portion 30b was formed on the remaining side, and a package P was created in which all four sides were sealed and the contents C was contained. The opening was heat-sealed under the conditions of 190°C, 0.03 MPa, and 2 seconds, and the width of the seal portion 30b was set to 10 mm.

[0060] After placing packaged material P into a high-temperature, high-pressure cooking and sterilization device (manufactured by Hitachi Capital Corporation), it was subjected to retort processing with high-temperature steam. The retort processing was carried out under the following conditions. • Pressure: 0.2 MPa ·Temperature 121℃ Processing time: 30 minutes After retort processing, the packaging P was heated in a water bath at 100°C for 5 minutes. After these heat treatments, the top of the packaging P was cut to form a spout (see Figure 5(d)). Next, the pouch was turned upside down, and the spout was held at a 45° angle from the horizontal plane for 10 seconds to discharge the contents C into container 50, and the amount discharged was weighed using a scale 60 (see Figure 5(e)). From the weighed amount, the residual liquid volume (%) was calculated using the following formula. Residual liquid amount (%)={(180-discharge amount) / 180}×100 Measurements were taken three times, and the residual liquid volume was evaluated based on the average of the three measurements according to the evaluation criteria below. Tables 1-8 show the residual liquid volume and the results of the residual liquid evaluation. A: Average residual liquid volume is less than 6.5% B: Average residual liquid volume is 6.5% or more but less than 8.0% C: Average residual liquid volume is 8.0% or more but less than 10.0% D: Average residual liquid volume is 10.0% or more

[0061] (Appearance evaluation after retort processing) In the residual liquid evaluation described above, the discharge behavior of the curry when it was discharged from the pouch was visually observed, and an appearance evaluation was performed according to the evaluation criteria below. The results are shown in Tables 1 to 8. A: It slides off cleanly, and there is almost no adhesion to the film. B: It appears to slide off easily, and there is little adhesion to the film. C: It appears to be sliding down, but it remains attached to the film. D: No signs of falling were observed.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] [Table 5]

[0067] [Table 6]

[0068] [Table 7]

[0069] [Table 8] [Industrial applicability]

[0070] This disclosure provides a method for manufacturing a packaging material that has excellent sliding properties for oil-in-water dispersed contents. Furthermore, this disclosure provides a film for packaging materials, a laminated film incorporating the same, and a packaging material. [Explanation of Symbols]

[0071] 1...First resin layer (innermost layer), 1a...Resin composition, 1b...Filler, 2...Second resin layer, 3...Adhesive layer, 5...Base material, 10,20...Packaging material (laminated film), C...Contents, C O ...Oil content, F1...Surface (first surface, innermost layer), F2...Surface (second surface), F O ...oil film, P...packaging body

Claims

1. (A) A step of preparing a packaging material comprising an innermost layer containing a resin composition containing polypropylene resin and a filler dispersed in the resin composition, wherein the ratio Y / X of the thickness X μm of the innermost layer to the average particle diameter Y μm of the filler is 0.3 to 3.5, (B) A step of producing a package having the packaging material and an oil-in-water dispersion type contents contained in a sealed state by the packaging material, (C) A step of heat-treating the packaging to allow the oil contained in the contents to be absorbed into the innermost layer, Includes, A method for manufacturing a package, wherein the innermost layer of the packaging material has a surface that constitutes the innermost surface of the packaging material and has a protruding peak volume Vmp of 0.08 to 0.3 μm³ / μm².

2. A method for producing a packaging according to claim 1, wherein the lipid content of the oil-in-water dispersion contents is 0.1% by mass or more and less than 50% by mass.

3. A packaging film comprising a first resin layer containing a resin composition comprising a polypropylene resin and a filler dispersed in the resin composition, The ratio Y / X of the thickness X μm of the first resin layer to the average particle size Y μm of the filler is 0.3 to 3.

5. The volume Vmp of the protruding peaks on the first surface of the first resin layer, which constitutes the innermost surface of the packaging film, is 0.08 to 0.3 μm. ３ / μm ２ This is a film used for packaging materials.

4. The packaging film according to claim 3, wherein the arithmetic mean roughness Sa of the first surface of the first resin layer, which constitutes the innermost surface of the packaging film, is 0.3 μm or more and less than 1.0 μm.

5. The packaging film according to any one of claims 3 to 4, further comprising a second resin layer provided on the second surface of the first resin layer.

6. The packaging film according to any one of claims 3 to 5, wherein the first resin layer further contains at least one additive from the group consisting of the following resin materials (i) to (vii). (i) Block copolymer of polypropylene and polyethylene (ii) Block copolymer of polyethylene and ethylene-butylene (iii) Block copolymer of polyethylene and ethylene-octene (iv) Ethylene-based elastomers (v) Propylene-based elastomers (vi) Butene-based elastomers (vii) Reactor TPO

7. The packaging film according to claim 6, wherein the first resin layer contains the (v) propylene elastomer.

8. The packaging film according to claim 6 or 7, wherein at least one of the softening point and melting point of the additive is 130°C or lower.

9. Substrate and A packaging film according to any one of claims 3 to 8 provided on the substrate, Equipped with, A laminated film in which the first resin layer is disposed on at least one of its outermost surfaces.

10. A packaging material comprising the laminated film described in claim 9.

11. The packaging material according to claim 10, used in a packaging body in which an oil-in-water dispersion type contents are contained in a sealed state and subjected to heat treatment.

12. The packaging material according to claim 11, wherein the lipid content of the oil-in-water dispersion is 0.1% by mass or more and less than 50% by mass.

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