JP7404641B2 - Resin films for packaging materials, packaging materials, and packaging bodies - Google Patents

Description

The present invention achieves both the rigidity and impact resistance required when the resin film for packaging is used as a packaging material alone or laminated with other base materials, and also has bending resistance at low temperatures. The present invention relates to a resin film for packaging material, a packaging material, and a packaging body that can be applied.

Packaging materials are used as packaging bags for packaging foodstuffs, medical products, etc., and the contents of these packaging bags have various states such as liquid, powder, paste, and solid. Films used for such packaging materials generally include resin film packaging using films of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyamide, polyester, etc. It is often used.

Physical properties required for packaging materials include suitability for filling when filling the contents, no damage to the bag when external force is applied to the packaging material, ease of opening the packaging material, and transparency to see the contents. Good physical properties and productivity during manufacturing are required.

In terms of the mechanical strength of packaging materials, strength as a packaging material is sometimes given by laminating a base material with excellent barrier properties and mechanical strength to a resin film for packaging materials. When adhesives are used for packaging, there are issues in terms of product stability, reduced production efficiency, and environmental impact, as the packaging material manufacturing process increases.

In order to solve these problems, a method is being developed to impart multifunctionality to films by coextruding multiple resins with different properties, such as polyamide resins such as nylon, in addition to polyolefin resins such as polyethylene and polypropylene. It is used. By applying such a construction method, a resin film having desired characteristics can be formed in one step.

For example, Patent Document 1 discloses a laminated film characterized by having a polyamide resin layer, an olefin resin layer, and a rubber elastic layer between them, and suppressing warpage, using a coextrusion water-cooled inflation method.

JP2013-22893A

However, in the method described in Patent Document 1, the polyamide resin, which is required for packaging materials with low flexibility, is laminated as a single layer, resulting in a decrease in the flexibility of the multilayer film. If the bending resistance decreases, pinhole defects will increase in the film due to bending fatigue.
In addition, if the polyamide layer is located as the outermost layer of a laminated multilayer film, there is a concern that dimensional stability may decrease due to moisture absorption in the polyamide layer. There are concerns about changes in slipperiness due to agent transfer.

Furthermore, as in the method of Patent Document 1, in order to laminate a polyamide resin and a polyolefin resin having different material properties, a method using an adhesive resin that facilitates mutual adhesion is adopted. However, by making the film multi-layered, the structure of the equipment becomes more complicated and the amount of materials used increases when extrusion molding is used, and the number of control items for stable quality increases, making it difficult to maintain quality. .

In view of the above, the present invention has developed a resin film for packaging materials that combines polyolefin resin with thermoplastic resins having different properties to achieve both rigidity and impact resistance, and has excellent bending resistance even in sub-zero low-temperature environments. The purpose of the present invention is to provide packaging materials and packaging bodies.

In order to achieve the above object, the resin film for packaging materials according to claim 1 of the present invention comprises:
A resin film made of a polyolefin resin and a polyamide resin ,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo flex tester,
The thickness of the resin film is 20 μm or more,
The polyamide resin is characterized in that the amount of the polyamide resin in the resin film is 5% by mass or more and less than 30% by mass.

Moreover, the invention of claim 2 is:
A resin film made of polyolefin resin and polystyrene resin,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo Flex Tester,
The thickness of the resin film is 20 μm or more,
The polystyrene resin accounts for 5% by mass or more and 10% by mass or less in the resin film.
This is a resin film for packaging material characterized by the following .

The invention of claim 3 is:
A resin film made of a polyolefin resin and an elastomer resin ,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo flex tester,
The thickness of the resin film is 20 μm or more,
The elastomer resin accounts for 5% by mass or more and less than 30% by mass in the resin film,
This is a resin film for packaging material characterized by the following .

The invention of claim 4 is:
The resin film for packaging material according to claim 3, wherein the elastomer resin is an ethylene-based elastomer resin .

The invention of claim 5 is:
As the first step,
A step of mixing polyolefin resin and polyamide resin,
Melting and kneading the mixture of the polyolefin resin and the polyamide resin at a screw rotation speed of 30 rpm or more and 200 rpm or less ;
forming the melt-kneaded mixture into pellets,
As the second step,
A step of mixing the same polyolefin resin as in the first step into the pellets so that the total amount of the polyamide resin blended is 5% by mass or more and less than 30% by mass;
forming a mixture of the pellets and the polyolefin resin into a film having a thickness of 20 μm or more using an extruder,
The present invention is characterized by producing a resin film for packaging materials that has less than 40 pinholes when subjected to bending fatigue 1000 times at a rate of 40 cycles per minute at a temperature of -10°C using a Gelbo Flex Tester. This is a method for producing a resin film for packaging materials.

According to the resin film for packaging materials of the present invention, the thermoplastic resin blended with the polyolefin resin has the property of absorbing external impact when formed into a thin molded product such as a film. Therefore, by superimposing this thermoplastic resin on a hard material or an easily stretchable material, it is possible to impart good rigidity, impact resistance, and bending resistance. Furthermore, by mixing resins with different properties and molding them into a single layer to reduce the number of layers, it is possible to shorten the manufacturing process and simplify the manufacturing equipment. Furthermore, the amount of materials used can be reduced, resulting in physical properties required for packaging materials. It is possible to maintain stable manufacturing control and quality control while maintaining

FIG. 2 is a schematic diagram showing one form of resin dispersion in the resin film for packaging materials of the present invention. FIG. 3 is a schematic diagram showing another form of resin dispersion in the resin film for packaging materials of the present invention.

Embodiments of the present invention will be described below. Note that each drawing is a schematic view, and the size, shape, etc. of each part are appropriately exaggerated for easy understanding. In addition, each of the embodiments shown below exemplifies a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention is that the material, shape, structure, etc. of the component parts are It is not specified by the following. Furthermore, the technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

As shown in FIG. 1, the resin film 1 for packaging materials of the present invention contains at least one type of thermoplastic resin selected from polyamide resin, polystyrene resin, and elastomer resin dispersed in the olefin resin as the main component. This is a thermoplastic resin composition. FIG. 1 schematically shows how the dispersed phase thermoplastic resin 3 is spherically dispersed in the olefin resin 2. In FIG. Further, FIG. 2 schematically shows how the dispersed phase thermoplastic resin 3 is dispersed in the shape of a flat ellipsoid.

As the main material of the olefin resin 2 constituting the resin film 1 for packaging materials, any general thermoplastic resin can be used, but an extrusion molding machine capable of heating at a high temperature exceeding 300°C can be used. Because it is formed into a film by the following methods, it must have appropriate flexibility as a packaging material and have good processability.

From this, low-density polyethylene (LDPE), which is mainly composed of olefin resin, linear low-density polyethylene (LLDPE), which is a copolymer of α-olefin and ethylene, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), ) and polypropylene and cycloolefin polymers having homopolymers, random copolymers, block copolymers, etc., cycloolefin copolymers obtained by copolymerizing cycloolefins and olefins, and ethylene vinyl acetate copolymers obtained by copolymerizing the olefins and vinyl acetate, Ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methacrylic acid copolymer (EBA) obtained by modifying the side chains of olefins. It is possible to select a single unit or a plurality of them and use them as appropriate from EMAA) and the like.

The dispersed phase thermoplastic resin 3 is a resin that forms a dispersed phase with respect to the main constituent olefin resin in the resin film for packaging materials according to the present invention.
The particles in the dispersed state (dispersed phase) of the dispersed phase thermoplastic resins 3 and 6 when viewed from the width direction of the resin films 1 and 4 for packaging materials or from the film flow direction are spherical as shown in FIG. It may be formed, or it may not be spherical as shown in FIG. Furthermore, the dispersed phase may have a co-continuous structure.

When a polyamide resin is selected as the dispersed phase thermoplastic resin 3, the polyamide resin is a polymer having a chain skeleton formed by polymerizing a plurality of monomers via an amide bond (-NH-CO-). It is a combination. Preferred polyamides for the thermoplastic resin include, for example, polyamide 6, polyamide 66, polyamide 11, polyamide 610, polyamide 612, polyamide 614, polyamide 12, polyamide 6T, polyamide 6I, polyamide 9T, polyamide M5T, polyamide 1010, polyamide 1012. , polyamide 10T, polyamide MXD6, polyamide 6T/66, polyamide 6T/6I, polyamide 6T/6I/66, polyamide 6T/2M-5T, polyamide 9T/2M-8T, and the like. Note that these polyamides may be used alone or in combination of two or more.

When polystyrene resin is selected for the dispersed phase thermoplastic resin 3, the polystyrene resin is a polymer obtained by polymerizing styrene monomer. Preferred polystyrenes include, for example, polystyrene, amorphous general-purpose polystyrene (GPPS) polymerized using polystyrene as the main raw material, and high impact polystyrene (High Impact polystyrene, which is made by adding rubber to GPPS to provide impact resistance).
Styrene AcryloNitrile resin (SAN), which is made by polymerizing styrene and acrylonitrile and has chemical resistance.Acrylonitrile has both the impact resistance of rubber and the chemical resistance of acrylonitrile. - Butadiene styrene resin (ABS) and the like may be mentioned.

When selecting an elastomer resin for the dispersed phase thermoplastic resin 3, the elastomer resin is preferably an olefin thermoplastic elastomer or a styrene thermoplastic elastomer.

Specific olefin thermoplastic elastomers include, for example, ethylene-propylene copolymer (Ethylene-Propylene Rubber, EPR), ethylene-1-butene copolymer (Ethylene-1-Butene Rubber, EBR), ethylene-1 -Pentene copolymer, ethylene-1-octene copolymer (Ethylene-1-Octene Rubber, EOR), propylene-1-butene copolymer (Propylene-1-Butene Rubber, PBR), propylene-1-pentene copolymer Polymer, propylene-1-octene copolymer (Propylene-1-Octene Rubber, POR), and the like. Among these, EOR, EBR, and EPR are preferred, and EBR and EOR are particularly preferred.

Specific styrene thermoplastic elastomers include, for example, styrene-butadiene-styrene copolymer (Styrene-Butadiene-Styrene rubber, SBS) and styrene-isoprene-styrene copolymer (Styrene-Isoprene-Styrene rubber, SIS). ) , Styrene-Ethylene/Butylene-Styrene rubber (SEBS), Styrene-Ethylene/Propylene-Styrene copolymer (SEPS) ) etc. Among these, SEBS is preferred.

In addition to the above-mentioned olefin resin 2 and dispersed phase thermoplastic resin 3, things that can be added to the resin include a compatibilizer that improves the compatibility between the two, a nucleating agent, an antioxidant, a heat stabilizer, a weathering agent, and a light stabilizer. agent, plasticizer, ultraviolet absorber, antistatic agent, flame retardant, slip agent, anti-blocking agent, anti-fog agent, lubricant, pigment, dye, dispersant, copper damage inhibitor, neutralizing agent, anti-foaming agent, weld Examples include strength modifiers, natural oils, synthetic oils, waxes, and the like. These may be used alone or in combination of two or more depending on the desired characteristics.

The compatibilizer is not particularly limited, but has good compatibility with both the main component thermoplastic resin and the dispersed phase thermoplastic resin, or has good compatibility with one of the thermoplastic resins and is compatible with one of the thermoplastic resins. Examples include a compatibilizer having a reactive group capable of reacting with a plastic resin, and a reactive group capable of reacting with both the main constituent thermoplastic resin and the dispersed phase thermoplastic resin.

For example, when the main component thermoplastic resin is an olefin resin and the dispersed phase thermoplastic resin is a polyamide, the compatibilizer added to the olefin resin layer is a molecule provided with a reactive group that can react with the polyamide resin. A thermoplastic resin having a structure is preferable.
The above-mentioned compatibilizing agent is generally known, and is a compatibilizing agent that forms a hydrogen bond with the amide group in the nylon molecule, such as ethylene-vinyl acetate copolymer (EVA) or maleic anhydride-modified polyethylene. Those containing a "C=O" double bond are preferred.

The nucleating agent and reinforcing filler include talc, silica, clay, montmorillonite,
Metals such as calcium carbonate, lithium alumina carbonate, titanium oxide, aluminum, iron, silver, and copper; hydroxides such as aluminum hydroxide and magnesium hydroxide; celluloses such as cellulose microfibrils and cellulose acetate; glass fibers and polyethylene terephthalate fibers. , fibrous fillers such as nylon fibers, polyethylene naphthalate fibers, aramid fibers, vinylon fibers, and polyarylate fibers, and carbons such as carbon nanotubes.

Examples of the antioxidant include phenolic compounds, organic phosphite compounds, thioether compounds, and the like.

Examples of the heat stabilizer include hindered amine compounds.

Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, benzoate compounds, and the like.

Examples of the antistatic agent include nonionic compounds, cationic compounds, anionic compounds, and the like.

Examples of the flame retardant include halogen compounds, phosphorus compounds, nitrogen compounds, inorganic compounds, boron compounds, silicone compounds, sulfur compounds, red phosphorus compounds, and the like.

Examples of the flame retardant aid include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, clay silicates, and the like.

The thickness of the resin film 1 for packaging material is preferably 20 μm or more. If the thickness is less than 20 μm, good impact resistance may not be obtained, and depending on the molding method, there may be problems such as unstable thickness accuracy or unstable behavior of the film when conveyed by rolls.

The blending ratio (mass ratio) of the dispersed phase thermoplastic resin 3 is preferably 5% by mass or more and less than 30% by mass, particularly preferably 5% by mass or more and 10% by mass or less. If the blending ratio is 30% by mass or more, the functions of the olefin resin 2, which is the main component, cannot be fully expressed, and the physical properties required as a packaging material cannot be satisfied. Furthermore, due to an increase in the blending amount of the dispersed phase thermoplastic resin 3, there is a concern that the film forming cost may increase depending on the type of material. Furthermore, if the blending ratio is less than 5% by mass, the thermoplastic resin will not function as a dispersed phase for the olefin resin that is the main component, making it difficult to meet the required physical properties such as rigidity and impact resistance in the laminated film. Can not.

The specific rigidity of the thermoplastic resin film 1 is based on the method described in JIS K 7127:1999, and the tensile modulus is preferably 350 MPa or more. For example, if it is less than 350 MPa, when the resin film 1 for packaging material is used as a packaging material, there is a possibility that the self-supporting property in the form of a bag may be reduced.

As for concrete impact resistance of the thermoplastic resin film 1, it is preferable that the breaking energy at room temperature is 8.6×10 ⁻³ J/μm or more. If it is less than 0.8×10 ⁻³ J/μm, when the resin film 1 for packaging material is used as a packaging material, there is a risk that it will be damaged when subjected to a drop impact.

In addition, the bending resistance of the resin film 1 for packaging materials is such that the number of pinholes is 40 when bending fatigue is applied 1000 times at a rate of 40 cpm (cycle per minute) in an environment of -10°C. It is preferable that it is less than 1.
If the number of pinholes is 40 or more when bending fatigue is applied 1000 times at a speed of 40 cpm, when the thermoplastic resin film 1 is used as a packaging material, it may be bent at the same part many times during transportation. Therefore, the probability of pinholes occurring increases, and this probability is even higher in a harsh sub-zero environment than at room temperature.

The method for producing the resin film 1 for packaging materials of this embodiment is not particularly limited, and any known method may be used.

The molding method includes, for example, a first step in which the olefin resin 2 and the dispersed phase thermoplastic resin 3 are melt-kneaded and pelletized (made into pellets), and the composition obtained in the first step and the olefin resin are melt-kneaded and pelletized. It is possible to form a film by using an extrusion molding machine, a feed block or a multi-manifold, and a T-die to form a film, or a film forming method using an inflation method as the second step.

The first step is a step of melt-kneading the olefin resin 2 and the dispersed phase thermoplastic resin 3.
In the first step, for example, a single-screw extruder, a twin-screw extruder, a kneader, a mixer, etc. can be used. These devices may be used alone or in combination of two or more. Furthermore, when two or more types are used, they may be operated continuously or batchwise. Furthermore, each raw material may be mixed all at once, or may be added in multiple portions and kneaded. The kneading temperature in the first step is not particularly limited, but is preferably 190°C or higher and 350°C or lower.

The second step is a step of performing extrusion film formation while melt-kneading the composition obtained in the first step and the olefin resin 2. Using multiple extrusion molding machines, the composition obtained in the first step, the product obtained by melt-kneading the olefin resin 2, and another thermoplastic resin are coextruded to form a layer structure of two or more layers. It's good to get it.

Regarding the method of cooling the film, it is possible to use the same method as the above-mentioned molding machine. For example, in the T-die method, an air cooling method such as an air chamber, a vacuum chamber, an air knife, etc., a water cooling method such as dipping a cooling roll into a cold water pan, etc. can be applied. There are no particular restrictions on the cooling method, but when providing an uneven shape to the film surface by shaping, nip rolls formed by processing silicone rubber, NBR rubber, Teflon (registered trademark), etc. Particularly preferred is a method in which a cooling roll formed by cutting metal is used to cool the molten resin by flowing it into the contact portion of the nip roll and the cooling roll to which a pressure of 0.1 MPa or more is applied.

In addition, the resin film 1 for packaging materials obtained by the present invention can be used as a single film or laminated with other base materials, and can be made into a bag as a packaging body, but regarding the format thereof, There are no particular restrictions.

Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

<Example 1>
[1] First step (generation of thermoplastic resin composition)
As resins used for olefin resin 2, linear low density polyethylene resin (density 0.93 g/cm ³ , MFR (Melt Flow Rate) 3.2) and low density polyethylene resin (density 0.924 g/cm ³ , MFR1) were used. 0) at a ratio of 95:5, and as the dispersed phase thermoplastic resin 3, a polyamide resin (nylon 6 resin, "A1030BRF" manufactured by Unitika Co., Ltd., density 1.13 g/cm ³ , MVR ( Melt Volume Rate), (250°C, 5kg) 70cm ³ ) were dry-blended and then put into a twin-screw melt-kneading extruder under the conditions of a kneading temperature of 250°C, an extrusion speed of 3.4kg/h, and a screw rotation speed of 30 rpm. The mixture was melt-kneaded and passed through a pelletizer to obtain pellets as the first step composition.

[2] Second step (formation of evaluation film)
The pellets obtained in [1] above, linear low density polyethylene resin (density 0.93 g/cm ³ , MFR 3.2) and low density polyethylene resin (density 0.924 g/cm ³ , MFR 1.0) The mixture was dry-blended in a ratio of 95:5 so that the blended amount of dispersed phase thermoplastic resin 3 was 10% by mass of the entire formed film in the second step. This was put into a single-screw extruder, and a film with a thickness of 115 μm was formed by T-die casting at a molding temperature of 250°C.

<Example 2>
In the same manufacturing method as in Example 1, polystyrene resin (“HF-77” manufactured by PS Japan Co., Ltd., density 1.05 g/cm ³ , MFR (200° C., 5 kg) 7.5) was used as the dispersed phase thermoplastic resin 3. The film of Example 2 was obtained.

<Example 3>
In the same manufacturing method as in Example 1, a film was formed using an elastomer resin (ethylene-based elastomer "A4070S" manufactured by Mitsui Chemicals, Inc., density 0.87 g/cm ³ , melting point 55 ° C.) as the dispersed phase thermoplastic resin 3. , the film of Example 3 was obtained.

<Example 4>
The same [1] first step as in Example 1 was carried out under the conditions of a kneading temperature of 250°C, an extrusion speed of 3.4 kg/h, and a screw rotation speed of 90 rpm. The film of Example 4 was obtained using the manufacturing method of the steps.

<Example 5>
The same [1] first step as in Example 1 was carried out under the conditions of a kneading temperature of 250°C, an extrusion speed of 3.4 kg/h, and a screw rotation speed of 200 rpm. The film of Example 5 was obtained using the process manufacturing method.

<Example 6>
In the same manufacturing method as in Example 1, the film of Example 6 was obtained with a film thickness of 50 μm.

<Example 7>
In the same manufacturing method as in Example 1, a film of Example 7 was obtained with a film thickness of 20 μm.

<Example 8>
In the same manufacturing method as in Example 1, the film of Example 8 was obtained by forming a film such that the polyamide resin content of the dispersed phase thermoplastic resin 3 was 5% by mass.

<Comparative example 1>
A film was formed using polyvinyl chloride resin ("BZV9887P-RH" manufactured by RIKEN TECHNOS Co., Ltd.) as the dispersed phase thermoplastic resin 3 in the same production method as in Example 1 under the conditions of a kneading temperature of 180 ° C., and Comparative Example 1 obtained the film.

<Comparative example 2>
In the same manufacturing method as in Example 1, a film of Comparative Example 2 was obtained by forming a film using a polyurethane resin ("E398" manufactured by Nippon Miractran Co., Ltd., A hardness 98) as the dispersed phase thermoplastic resin 3.

<Comparative example 3>
The first step [1] as in Example 1 was carried out under the conditions of a kneading temperature of 250°C, an extrusion speed of 3.4 kg/h, and a screw rotation speed of 15 rpm, and the second step [2] as in Example 1 was carried out. A film of Comparative Example 3 was obtained using the manufacturing method.

<Comparative example 4>
In the same manufacturing method as in Example 1, a film of Comparative Example 4 was obtained with a film thickness of 15 μm.

<Comparative example 5>
In the same manufacturing method as in Example 1, a film was formed so that the amount of polyamide resin in the dispersed phase thermoplastic resin 3 was 0% by mass, and a film of Comparative Example 5 was obtained.

<Comparative example 6>
In the same manufacturing method as in Example 1, a film was formed so that the polyamide resin content of the dispersed phase thermoplastic resin 3 was 2% by mass, and a film of Comparative Example 6 was obtained.

<Comparative example 7>
A film of Comparative Example 7 was obtained by using the same manufacturing method as in Example 1 so that the polyamide resin content of the dispersed phase thermoplastic resin 3 was 30% by mass.

<Comparative example 8>
In the same manufacturing method as in Example 1, a film was formed so that the polyamide resin content of the dispersed phase thermoplastic resin 3 was 50% by mass, and a film of Comparative Example 8 was obtained.

<Comparative example 9>
In the same manufacturing method as in Example 1, a film was formed so that the polyamide resin content of the dispersed phase thermoplastic resin 3 was 100% by mass, and a film of Comparative Example 9 was obtained.

The tensile modulus and impact resistance of the resin films 1 for packaging materials obtained in Examples 1 to 8 and Comparative Examples 1 to 9 were evaluated, and the bending resistance was evaluated in a -10°C environment. Furthermore, the shape of the dispersed phase was observed using a scanning electron microscope.

(Tensile modulus evaluation)
For tensile modulus evaluation, the film was cut into 15 mm width x 100 mm, and the distance between the chucks was 50 mm and the tensile speed was 300 mm/min, using a tensile tester (AGS-500NX) manufactured by Shimadzu Corporation, in accordance with JIS K 7127:1999. The tensile modulus was measured using Regarding the evaluation, those in which the product of the tensile modulus and the cross-sectional area of the film was 350 MPa or more were rated "O", and the others were rated "x".

(Impact resistance rate evaluation)
In the impact resistance evaluation, the film was cut to a width of 100 mm, and the breaking energy was measured using a film impact tester (model R) manufactured by Toyo Seiki Seisakusho Co., Ltd. at a measurement temperature of 23°C, a weight of 3.0 J, and a 1/2 inch warhead. was measured. Those with a breaking energy of 8.6×10 ⁻³ J/μm or more were rated “〇”, and the others were rated “×”.

(Low temperature bending resistance evaluation)
In the low-temperature bending resistance evaluation, the film was cut to a width of 210 mm x length of 297 mm, the measurement temperature was -10°C, and bending fatigue was applied 1000 times at a speed of 40 cpm using a GELBO Flex Tester manufactured by Tester Sangyo Co., Ltd. The number of pinholes per area of width 195 mm x length 282 mm was measured using penetrating liquid spray. Those with 40 or less pinholes were rated “〇”, and the others were rated “×”.

(comprehensive evaluation)
As an overall evaluation, if all of the evaluations regarding the thermoplastic resin film were evaluated as "○", the overall evaluation was evaluated as "〇", and if there was at least one evaluation as "x", it was evaluated as "x".

The evaluation results of the resin films for packaging materials of each of the Examples and Comparative Examples are listed in Table 1.

From Table 1, Examples 1 to 8 satisfied the overall evaluation of "○" or higher.
On the other hand, in Comparative Examples 1 and 2, since the dispersed phase thermoplastic resin material is soft, the elastic modulus is low, the impact resistance is poor, and the number of pinholes is large, so the overall evaluation is "x".
In Comparative Example 3, the dispersed phase thermoplastic resin was not sufficiently dispersed due to the low rotational speed of the extruder, and was rated "x" in all items.
In Comparative Example 4, since the film thickness was thin, the elastic modulus and impact resistance were low.
In Comparative Examples 5 and 6, since the amount of dispersed phase thermoplastic resin added was small, the elastic modulus and impact resistance were low, and the overall score was "x".
In Comparative Examples 7 and 8, since the amount of dispersed phase thermoplastic resin added was large, interfacial peeling occurred between the olefin resin/dispersed phase thermoplastic resin, and the items other than elastic modulus and impact resistance were marked "x". be.
Comparative Example 9 had a large number of pinholes and was rated "poor" in terms of bending resistance because it was composed of a single layer of polyamide with poor bending resistance.

1 Resin film for packaging material 2 Olefin resin 3 Dispersed phase thermoplastic resin

Claims (5)

A resin film made of a polyolefin resin and a polyamide resin ,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo flex tester,
The thickness of the resin film is 20 μm or more,
The polyamide resin accounts for 5% by mass or more and less than 30% by mass in the resin film.
A resin film for packaging material characterized by: A resin film made of polyolefin resin and polystyrene resin ,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo flex tester,
The thickness of the resin film is 20 μm or more,
The polystyrene resin accounts for 5% by mass or more and 10 % by mass or less in the resin film.
A resin film for packaging material characterized by: A resin film made of a polyolefin resin and an elastomer resin ,
The number of pinholes is less than 40 when bending fatigue is applied 1000 times at a rate of 40 cycles per minute at a temperature of -10 ° C using a Gelbo flex tester,
The thickness of the resin film is 20 μm or more,
The elastomer resin accounts for 5% by mass or more and less than 30% by mass in the resin film,
A resin film for packaging material characterized by: The resin film for packaging materials according to claim 3, wherein the elastomer resin is an ethylene-based elastomer resin. As the first step,
A step of mixing polyolefin resin and polyamide resin,
Melting and kneading the mixture of the polyolefin resin and the polyamide resin at a screw rotation speed of 30 rpm or more and 200 rpm or less ;
forming the melt-kneaded mixture into pellets,
As the second step,
A step of mixing the same polyolefin resin as in the first step into the pellets so that the total amount of the polyamide resin blended is 5% by mass or more and less than 30% by mass;
forming a mixture of the pellets and the polyolefin resin into a film having a thickness of 20 μm or more using an extruder,
The present invention is characterized by producing a resin film for packaging materials that has less than 40 pinholes when subjected to bending fatigue 1000 times at a rate of 40 cycles per minute at a temperature of -10°C using a Gelbo Flex Tester. A method for producing a resin film for packaging material.