Polypropylene film, packaging material, and packaging body

Abstract

To provide a polypropylene film that inhibits the detachment of an antiblocking agent and has appropriate slip properties. [Solution] A polypropylene film comprising a core layer and a first skin layer, wherein the core layer contains polypropylene, the first skin layer contains polypropylene and an antiblocking agent, and the particle size distribution of the antiblocking agent in the first skin layer has two or more peak values.

Description

[Technical Field]

[0001] The present disclosure relates to polypropylene films, packaging materials, and packages. [Background technology]

[0002] Polypropylene film is widely used as a packaging material for food, pharmaceuticals, industrial products, etc., or as a component of industrial products. Examples of its use include a single-layer sheet made of a single layer of polypropylene film and a laminated sheet in which polypropylene film is laminated with other sheet materials. Examples of other sheet materials that can be laminated with polypropylene film include polyester resin film, vinyl chloride film, and paper.

[0003] Generally, polypropylene film is stored in roll form, but during storage, the films stick together and become difficult to peel off (blocking), which causes problems with storage and handling.Antiblocking agents are used to improve this. Patent Document 1 proposes a laminate for a gas barrier film, which includes a substrate film containing a resin and an antiblocking agent, and an inorganic oxide layer laminated on the substrate film. Patent Document 2 proposes a laminated film having a central layer, an outer layer portion, and an inner layer portion, in which the first and third layers of the inner layer portion contain an antiblocking agent. Patent Document 3 proposes a laminated film that includes a substrate containing an antiblocking agent and a release layer laminated on the substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-58265 [Patent Document 2] Japanese Patent Application Publication No. 2024-68066 [Patent Document 3] Japanese Patent Application Laid-Open No. 2024-59273 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a problem that the antiblocking agent falls off from the film. In addition, the film needs to have a suitable degree of slipperiness to make it easier to pull out the film from the roll (to improve handling). An object of the present disclosure is to provide a film material that inhibits the detachment of an antiblocking agent and has appropriate slip properties. [Means for solving the problem]

[0006] The present inventors have conducted extensive research into methods for producing films using non-petrochemical raw materials that have a small environmental impact, and as a result have found that by including an antiblocking agent so that the particle size distribution has at least two peaks, it is possible to suppress the detachment of the antiblocking agent and obtain a polypropylene film that has appropriate slip properties, thereby completing the present disclosure.

[0007] The present disclosure has the following aspects. [1] A polypropylene film comprising a core layer and a first skin layer, the core layer comprises polypropylene; the first skin layer comprises polypropylene and an antiblocking agent; the particle size distribution of the antiblocking agent in the first skin layer has two or more peak values; Polypropylene film. [2] The polypropylene film according to [1], wherein the first skin layer has a thickness of 0.5 to 5.0 μm. [3] The polypropylene film according to [1] or [2], wherein the particle size of the antiblocking agent is 0.01 to 50 μm. [4] The particle size distribution of the antiblocking agent in the first skin layer is The polypropylene film according to any one of [1] to [3], wherein a ratio A expressed as (particle diameter R1 at the largest peak a in the range of 0.1 to 2.5 μm) / (thickness T1 of the first skin layer) is 0.3 to 2.5. [5] The particle size distribution of the antiblocking agent in the first skin layer is The polypropylene film according to any one of [1] to [4], wherein a ratio B expressed as (particle diameter R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (thickness T1 of the first skin layer) is 1.0 to 6.0. [6] The particle size distribution of the antiblocking agent in the first skin layer is Ratio B represented by (particle diameter R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (thickness T1 of the first skin layer), A ratio A expressed by (particle diameter R1 at the largest peak a in the range of 0.1 to 2.5 μm) / (thickness T1 of the first skin layer) is The polypropylene film according to any one of [1] to [5], wherein B / A is 1 to 10. [7] The polypropylene film according to any one of [1] to [6], wherein the antiblocking agent comprises at least one selected from the group consisting of resin particles, higher fatty acid particles, higher fatty acid amide particles, higher fatty acid metal salt particles, silica particles, talc particles, zeolite particles, kaolinite particles, and feldspar particles. [8] Further, it has a second skin layer, The polypropylene film according to any one of [1] to [7], wherein the first skin layer, the core layer, and the second skin layer are laminated in this order. [9] the core layer comprises biomass-derived propylene units; The polypropylene film according to any one of [1] to [8], wherein the content of the biomass-derived propylene units is 10% by mass or more and 50% by mass or less relative to the total mass of the polypropylene film.

[10] At least one of the core layer and the first skin layer contains a phosphorus-based antioxidant, The polypropylene film according to any one of [1] to [9], wherein the content of the phosphorus-based antioxidant is 300 ppm by mass or more and 1000 ppm by mass or less relative to the total mass of the polypropylene film.

[11] A packaging material comprising the polypropylene film according to any one of [1] to

[10] .

[12]

[11] A package in which an item is packaged with the packaging material described in

[11] . [Effects of the Invention]

[0008] According to the present disclosure, a polypropylene film can be obtained that inhibits the antiblocking agent from falling off and has appropriate slip properties. [Brief explanation of the drawings]

[0009] [Figure 1] This is an example of particle size distribution when particle size (μm) is plotted on the horizontal axis and peak intensity (volume frequency) on the vertical axis. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. The lower and upper limits of the ranges disclosed in this specification can be combined in any way to create new ranges. As used herein, "biomass feedstock" refers to feedstocks (e.g., propylene) obtained from biomass such as corn, sugarcane, and wood. As used herein, "bionaphtha" refers to naphtha produced using biomass as a raw material. "Petroleum naphtha" refers to naphtha produced using petroleum as a raw material. In this specification, "polypropylene" is composed mainly of units based on propylene, and refers to a propylene homopolymer or a copolymer having 80 mass % or more of units based on propylene.

[0011] The propylene film of the present disclosure comprises a first skin layer and a core layer.

[0012] <Core layer> In the present disclosure, the core layer is a layer comprising polypropylene. The core layer preferably contains polypropylene (hereinafter also referred to as "first polypropylene (A)") having propylene units derived from propylene produced from biomass raw materials (hereinafter also referred to as "biomass-derived P units").

[0013] (polypropylene) The first polypropylene (A) contained in the core layer is mainly composed of units based on propylene, and is a propylene homopolymer or a copolymer having 80 mass % or more of units based on propylene. The copolymer is, for example, a copolymer having units based on propylene and units based on one or more α-olefins, such as ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-pentene-1. The proportion of propylene-based units relative to all the polypropylene units is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. It may be 100% by mass.

[0014] The content of the first polypropylene (A) relative to the total mass of the core layer is preferably 10 to 100% by mass, more preferably 15 to 100% by mass, and even more preferably 20 to 100% by mass. When the content is equal to or less than the upper limit, the effect of reducing the environmental impact obtained from the biomass-derived P units is more excellent. When the content is equal to or more than the lower limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product. In addition, the excellent physical properties obtained from the petroleum naphtha-derived P units are more easily improved.

[0015] The content of biomass-derived P units relative to the total mass of the core layer is preferably 11% by mass to 50% by mass, more preferably 11% by mass to 45% by mass, even more preferably 11% by mass to 40% by mass, and particularly preferably 11% by mass to 35% by mass. When the content of biomass-derived P units is equal to or greater than the above-mentioned lower limit, the effect of reducing the environmental load obtained by the biomass-derived P units is more excellent. Furthermore, when the content of biomass-derived P units is equal to or less than the above-mentioned upper limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product.

[0016] The first polypropylene (A) may contain biomass-derived P units, and may further contain petroleum naphtha-derived propylene units (hereinafter also referred to as "petroleum naphtha-derived P units"). It is preferable that the first polypropylene (A) contains both biomass-derived P units and petroleum naphtha-derived P units, as this results in excellent physical properties of the resulting polypropylene film.

[0017] The content of the biomass-derived P units relative to all units of the first polypropylene (A) is preferably 20 to 90 mass%, more preferably 30 to 80 mass%, and even more preferably 40 to 70 mass%. When the content of the biomass-derived P units is equal to or greater than the above lower limit, the effect of reducing the environmental load obtained by the biomass-derived P units is more excellent. When the content of the biomass-derived P units is equal to or less than the above upper limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product.

[0018] The content of the petroleum naphtha-derived P units relative to the total units of the first polypropylene (A) is preferably 10 to 80 mass%, more preferably 20 to 70 mass%, and even more preferably 30 to 60 mass%. When the content of the petroleum naphtha-derived P units is equal to or greater than the above lower limit, it becomes easier to suppress changes in color and strength over time caused by the biomass-derived P units, and therefore it becomes easier to prevent a decrease in the commercial value of the product. In addition, it becomes easier to further improve the excellent physical properties obtained by the petroleum naphtha-derived P units. When the content of the petroleum naphtha-derived P units is equal to or less than the above upper limit, it becomes even more effective to reduce the environmental impact obtained by the biomass-derived P units.

[0019] The mass ratio represented by [petroleum naphtha-derived P units] / [biomass-derived P units] is preferably 0.1 to 4, more preferably 0.2 to 2.3, and even more preferably 0.4 to 1.5. When the mass ratio is equal to or less than the upper limit, the effect of reducing the environmental load obtained by the biomass-derived P units is more excellent. When the mass ratio is equal to or more than the lower limit, it becomes easier to prevent deterioration in the physical properties of the polypropylene film caused by the biomass-derived P units, and therefore it becomes easier to prevent deterioration in the commercial value of the product.

[0020] The first polypropylene (A) may be a copolymer containing units derived from a monomer other than propylene. The total content of biomass-derived P units and petroleum naphtha-derived P units relative to the total units of the first polypropylene (A) is preferably 80% by mass or more, more preferably 85% by mass, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. It may even be 100% by mass.

[0021] The first polypropylene (A) preferably comprises propylene-based units produced from a mixture of bionaphtha and petroleum naphtha. Propylene produced from a mixture of bionaphtha and petroleum naphtha as raw naphtha is a mixture of biomass-derived propylene and petroleum naphtha-derived propylene. The ratio of bionaphtha to petroleum naphtha in the raw naphtha determines the ratio of biomass-derived propylene to petroleum naphtha-derived propylene in the produced propylene. For example, propylene (50 / 50) produced from a mixture of 50 mass% bionaphtha and 50 mass% petroleum naphtha is a mixture of 50 mass% biomass-derived propylene and 50 mass% petroleum naphtha-derived propylene. With respect to all units of the polypropylene obtained by polymerizing propylene (50 / 50), the content of biomass-derived P units is 50 mass % and the content of petroleum naphtha-derived P units is 50 mass %.

[0022] The first polypropylene (A) contained in the core layer may be one type or two or more types. The content of the first polypropylene (A) in the core layer can be designed so that the biomass-derived P unit is 10% by mass or more and 50% by mass or less relative to the mass of the polypropylene film.

[0023] (phosphorus antioxidant) The core layer may contain a phosphorus-based antioxidant. The content of the phosphorus-based antioxidant relative to the total mass of the core layer is preferably 300 ppm by mass to 1000 ppm by mass, more preferably 300 ppm by mass to 700 ppm by mass. When the content of the phosphorus-based antioxidant is equal to or greater than the lower limit, the effect of suppressing changes in color and strength over time is excellent. When the content of the phosphorus-based antioxidant exceeds the upper limit, bleed-out over time tends to cause deterioration in transparency, printing properties, etc.

[0024] Examples of phosphorus-based antioxidants include tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and tetrakis(2,4-di-t-butylphenyl)pentaerythritol diphosphite. 4,4'-diphenylenediphosnite, 2,2'-methylenebis(4,6-di-t-butylphenyl)2-ethylhexyl phosphite, 2,2'-ethylidenebis(4,6-di-t-butylphenyl)fluorophosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, 2-(2,4,6-tri-t-butylphenyl)-5-ethyl-5-butyl-1,3,2-oxaphosphorinane, 2,2',2''-nitrilo[triethyl-tris(3,3',5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diyl)phosphite, etc. Among these, tris(2,4-di-t-butylphenyl)phosphite is particularly preferred. The phosphorus-based antioxidant preferably contains tris(2,4-di-t-butylphenyl)phosphite. The proportion of tris(2,4-di-t-butylphenyl)phosphite relative to the total mass of the phosphorus-based antioxidants contained in the core layer is preferably 80 mass% or more, more preferably 85 mass% or more, even more preferably 90 mass% or more, and particularly preferably 95 mass% or more. It may even be 100 mass%.

[0025] The core layer may contain materials other than the first polypropylene (A) and the phosphorus-based antioxidant depending on quality requirements, as long as the effects of the present disclosure are not impaired. Examples of other materials include resin components such as polypropylene other than the first polypropylene (A) (hereinafter also referred to as "second polypropylene (B)") and other resins; and optional components such as pigments, dyes, lubricants, antiblocking agents, antistatic agents, UV absorbers, plasticizers, freshness-preserving agents, deodorizers, compatibilizers, resins other than polypropylene, and antioxidants other than phosphorus-based antioxidants. From the viewpoint of improving adhesion to the skin layer, it is preferable that the core layer does not contain an antiblocking agent.

[0026] (resin component) When the core layer contains a resin component other than the first polypropylene (A), the content of the resin component other than the first polypropylene (A) is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 50 to 60% by mass, relative to the total mass of the core layer. When the content is equal to or less than the upper limit, the effect of reducing the environmental impact obtained from the biomass-derived P units is more excellent. When the content is equal to or greater than the lower limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product. In addition, the excellent physical properties obtained from the petroleum naphtha-derived P units are more easily improved.

[0027] Secondary Polypropylene (B) The polypropylene contained in the core layer preferably contains, in addition to the first polypropylene (A), a second polypropylene (B) that contains petroleum naphtha-derived P units and does not contain biomass-derived P units. The second polypropylene (B) contained in the core layer is mainly composed of units based on propylene, and is a propylene homopolymer or a copolymer having 80 mass % or more of units based on propylene. The second polypropylene (B) may be a copolymer containing units derived from a monomer other than propylene. Examples of the monomer other than propylene include the same α-olefins as those described for the first polypropylene (A). The content of petroleum naphtha-derived P units relative to all units of the second polypropylene (B) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and may be 100% by mass.

[0028] The second polypropylene (B) contained in the polypropylene film of the present disclosure may be one type or two or more types. The content of the second polypropylene (B) in the polypropylene film of the present disclosure can be designed so that the biomass-derived P units in the first polypropylene (A) are 10% by mass or more and 50% by mass or less relative to the mass of the polypropylene film of the present disclosure.

[0029] (optional ingredient) When the core layer contains optional components, the total content of the optional components relative to the mass of the core layer is, for example, preferably 3 mass % or less, more preferably 2 mass % or less, and may be zero.

[0030] The thickness of the core layer is preferably 10 to 70 μm, more preferably 12 to 65 μm, and even more preferably 15 to 60 μm. When the thickness of the core layer is equal to or less than the upper limit, it is easy to suppress changes in color and strength over time caused by the biomass-derived P units, and therefore it is easy to prevent a decrease in the commercial value of the product. When the thickness of the core layer is equal to or greater than the lower limit, it is more effective in reducing the environmental load obtained by the biomass-derived P units.

[0031] <First Skin Layer> In the present disclosure, the first skin layer is a layer comprising polypropylene and an antiblocking agent. In the present disclosure, the particle size distribution of the antiblocking agent in the first skin layer has two or more peak values.

[0032] (polypropylene) The polypropylene for the first skin layer may be the same as the polypropylene described for the core layer. The first skin layer preferably contains the second polypropylene (B) and does not contain the first polypropylene (A). The content of the second polypropylene (B) relative to the total mass of the first skin layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. It may be 100% by mass. When the content of the second polypropylene (B) is equal to or less than the above upper limit, excellent physical properties are easily maintained. When the content of the second polypropylene (B) is equal to or more than the above lower limit, the excellent physical properties obtained from the petroleum naphtha-derived P units are easily improved.

[0033] (Anti-blocking agent) In the present disclosure, the first skin layer contains an antiblocking agent. The antiblocking agent forms protrusions on the surface of the polypropylene film, thereby preventing the films from adhering to each other (blocking) when the films are rolled and stacked. This prevents a deterioration in the quality of the film product due to blocking. Furthermore, the antiblocking agent forms protrusions on the surface of the polypropylene film, thereby preventing static electricity from being generated when the rolled film is unwrapped and used. This prevents a deterioration in the handleability of the film product due to static electricity.

[0034] Antiblocking agents include inorganic and organic antiblocking agents. Examples of inorganic antiblocking agents include silica particles, talc particles, zeolite particles, kaolinite particles, and feldspar particles. Examples of organic antiblocking agents include resin particles such as polymethyl methacrylate (PMMA), polysilicon resin, and crosslinked polystyrene, higher fatty acid particles, higher fatty acid amide particles, and higher fatty acid metal salt particles. The antiblocking agent may be one type or two or more types. When two or more types are used, two or more inorganic antiblocking agents may be used, an inorganic antiblocking agent and an organic antiblocking agent may be used in combination, or two or more organic antiblocking agents may be used.

[0035] In the first skin layer, the particle size of the antiblocking agent is preferably 0.01 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.3 to 20 μm. When the particle size of the antiblocking agent is equal to or less than the upper limit, the difference between the convex and smooth portions on the surface of the skin layer is small, resulting in better adhesion to the core layer. When the particle size of the antiblocking agent is equal to or greater than the lower limit, the difference between the convex and smooth portions on the surface of the skin layer is appropriate, resulting in better anti-blocking properties. In this specification, the "particle size" is not an average value but an absolute value, and can be measured by a laser diffraction / scattering method.

[0036] In the first skin layer, the average particle size of the antiblocking agent is preferably 0.1 to 10 μm, more preferably 0.2 to 6.0 μm, and even more preferably 0.4 to 4.5 μm. When the average particle size of the antiblocking agent is equal to or less than the upper limit, the adhesion to the core layer is superior. When the average particle size of the antiblocking agent is equal to or greater than the lower limit, the blocking resistance is superior. In this specification, the "average particle size of the antiblocking agent" can be measured by a laser diffraction / scattering method.

[0037] In the present disclosure, the particle size distribution of the antiblocking agent in the first skin layer has two or more peak values. Having two or more peak values ​​forms convex portions of different heights on the surface of the first skin layer, which provides blocking resistance, slipperiness, prevention of antiblocking agent removal, adhesion to the core layer, and ease of winding when rolled (excellent handling).

[0038] The first skin layer preferably contains two or more types of antiblocking agents with different average particle sizes (hereinafter, the antiblocking agent with the smaller average particle size will be referred to as the "first antiblocking agent," and the antiblocking agent with the larger average particle size will be referred to as the "second antiblocking agent.") The two or more different types of antiblocking agents may be the same or different.

[0039] Figure 1 is a schematic diagram showing the particle size distribution of two or more antiblocking agents with different average particle sizes, showing an example of particle size distribution when particle size (μm) is plotted on the horizontal axis (x-axis) and peak intensity (volume frequency) on the vertical axis (y-axis). As shown in FIG. 1, the particle size distribution has at least two particle size peaks. (Method for measuring particle size peak) The dispersion of the antiblocking agent is measured using a particle size distribution analyzer based on the laser diffraction / scattering method (e.g., Microtrac MT3300EX2 manufactured by Nikkiso Co., Ltd.), and a volumetric particle size distribution graph is created. In the present invention, the peak of the particle size distribution of the antiblocking agent is defined as follows: In the particle size distribution graph, a peak is defined as a particle that exceeds 5% of the particle frequency of the highest peak particle size. The largest peak in the range of 0.1 to 2.5 μm is defined as Peak a, and the largest peak in the range of more than 2.5 μm and up to 10 μm is defined as Peak b. The number of peaks may be more than two, but is preferably 2. If there are more than two peaks, the difference in height of the convex portions is reduced, making it easier to improve the slipperiness, but if there are two peaks, an appropriate difference in height of the convex portions is created, making it easier to further improve the anti-blocking effect.

[0040] The average particle size of the first antiblocking agent is preferably 0.1 to 2.5 μm, more preferably 0.3 to 2.4 μm, and even more preferably 0.6 to 2.2 μm. When the average particle size of the first antiblocking agent is equal to or less than the upper limit, a suitable difference in particle size occurs between the average particle size of the second antiblocking agent, resulting in a suitable difference between the convex and smooth portions of the skin layer surface, thereby improving anti-blocking properties. When the average particle size of the first antiblocking agent is equal to or greater than the lower limit, a small difference in particle size between the average particle size of the second antiblocking agent occurs, resulting in a small difference between the convex and smooth portions of the skin layer surface, thereby improving adhesion to the core layer. Furthermore, the small difference in particle size between the average particle size of the second antiblocking agent makes it easier to prevent the antiblocking agent from falling off.

[0041] The average particle size of the second antiblocking agent is preferably greater than 2.5 μm and less than 10 μm, more preferably 2.8 to 6 μm, even more preferably 2.8 to 5 μm, particularly preferably 2.9 to 4.5 μm, and most preferably 2.9 to 4.2 μm. When the average particle size of the second antiblocking agent is equal to or less than the upper limit, the difference between the average particle size of the second antiblocking agent and that of the first antiblocking agent is small, thereby reducing the difference between the convex and smooth portions of the skin layer surface, resulting in better adhesion to the core layer. Furthermore, the small difference between the average particle size of the first antiblocking agent makes it easier to prevent the antiblocking agent from falling off. When the average particle size of the second antiblocking agent is equal to or greater than the lower limit, the difference between the average particle size of the second antiblocking agent and that of the first antiblocking agent is appropriate, thereby reducing the difference between the convex and smooth portions of the skin layer surface, resulting in better anti-blocking properties.

[0042] First anti-blocking agent The average particle size of the first antiblocking agent is preferably 0.1 to 2.5 μm, more preferably 0.3 to 2.3 μm, and even more preferably 0.5 to 2.2 μm. When the average particle size of the first antiblocking agent is equal to or less than the upper limit, a suitable difference in particle size occurs between the average particle size of the second antiblocking agent, resulting in a suitable difference between the convex and smooth portions of the skin layer surface, thereby improving anti-blocking properties. When the average particle size of the first antiblocking agent is equal to or greater than the lower limit, a small difference in particle size between the average particle size of the second antiblocking agent occurs, resulting in a small difference between the convex and smooth portions of the skin layer surface, thereby improving adhesion to the core layer.

[0043] The content of the first antiblocking agent relative to the total mass of the first skin layer is preferably 0.05 to 0.7 mass%, more preferably 0.07 to 0.5 mass%, and even more preferably 0.1 to 0.3 mass%. When the content of the first antiblocking agent is equal to or less than the above upper limit, the difference between the convex and smooth portions on the surface of the skin layer becomes appropriate, which facilitates improving the anti-blocking property of the second antiblocking agent. When the content of the first antiblocking agent is equal to or greater than the above lower limit, the anti-blocking property of the first antiblocking agent becomes easy to improve, and the difference between the convex and smooth portions on the surface of the skin layer becomes small, which improves adhesion to the core layer.

[0044] The ratio A, expressed as (particle diameter R1 at the largest peak a in the range of 0.1 to 2.5 μm) / (thickness T1 of the first skin layer), is preferably 0.2 to 2.5, more preferably 0.25 to 2.0, and even more preferably 0.3 to 1.5. When the ratio A is equal to or less than the upper limit, the difference between the convex and smooth portions on the surface of the skin layer becomes appropriate, resulting in better blocking resistance. When the ratio A is equal to or greater than the lower limit, the difference between the convex and smooth portions on the surface of the skin layer becomes small, resulting in better adhesion to the core layer.

[0045] Secondary anti-blocking agent The average particle size of the second antiblocking agent is preferably greater than 2.5 μm and less than 10 μm, more preferably 2.8 to 6 μm, even more preferably 2.8 to 5 μm, particularly preferably 2.9 to 4.5 μm, and most preferably 2.9 to 4.2 μm. When the average particle size of the second antiblocking agent is equal to or less than the upper limit, the second antiblocking agent is more easily prevented from falling off the first skin layer. Furthermore, since the difference in the average particle size between the second antiblocking agent and the first antiblocking agent is small, the difference between the convex and smooth portions of the skin layer surface is small, thereby improving adhesion to the core layer. When the average particle size of the second antiblocking agent is equal to or greater than the lower limit, an appropriate difference in particle size is achieved between the second antiblocking agent and the first antiblocking agent. This results in an appropriate difference in the difference between the convex and smooth portions of the skin layer surface, improving anti-blocking properties.

[0046] The content of the second antiblocking agent relative to the total weight of the first skin layer is preferably 0.01 to 0.4% by weight, more preferably 0.02 to 0.3% by weight, and even more preferably 0.02 to 0.2% by weight. When the content of the second antiblocking agent is equal to or less than the upper limit, it is easier to prevent the second antiblocking agent from falling off the first skin layer, and it is easier to improve the anti-blocking property provided by the first antiblocking agent. The difference between the convex and smooth portions on the surface of the skin layer is reduced, thereby improving adhesion to the core layer. When the content of the second antiblocking agent is equal to or greater than the lower limit, it is easier to improve the anti-blocking property provided by the second antiblocking agent, and it is easier to achieve an appropriate difference between the convex and smooth portions on the surface of the skin layer, thereby improving the anti-blocking property.

[0047] The ratio B, expressed as (particle diameter R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (thickness T1 of the first skin layer), is preferably 0.6 to 6.0, more preferably 0.8 to 5.0, and even more preferably 1.0 to 4.5. When the ratio B is equal to or less than the upper limit, the second antiblocking agent is more easily prevented from falling off the first skin layer, and the difference between the convex and smooth portions on the skin layer surface is reduced, resulting in better adhesion to the core layer. When the ratio B is equal to or greater than the lower limit, the difference between the convex and smooth portions on the skin layer surface is appropriately large, resulting in better anti-blocking properties.

[0048] The ratio A, expressed as (particle diameter R1 at the largest peak a in the range of 0.1 to 2.5 μm) / (thickness T1 of the first skin layer), to the ratio B, expressed as (particle diameter R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (thickness T1 of the first skin layer), is preferably 1 to 10, more preferably 1.3 to 8, and even more preferably 1.5 to 7. When B / A is equal to or less than the upper limit, the second antiblocking agent is more easily prevented from falling off the first skin layer, and the difference between the convex and smooth portions on the skin layer surface is reduced, resulting in better adhesion to the core layer. When B / A is equal to or greater than the lower limit, the difference between the convex and smooth portions on the skin layer surface is appropriately large, resulting in better anti-blocking properties.

[0049] The particle size ratio, R2 / R1, expressed as (particle size R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (particle size R1 at the largest peak a in the range of 0.1 to 2.5 μm), is preferably 1 to 10, more preferably 1.3 to 8, and even more preferably 1.5 to 7. When R2 / R1 is equal to or less than the upper limit, the second antiblocking agent is more easily prevented from falling off the first skin layer, and the difference between the convex and smooth portions on the skin layer surface is reduced, resulting in better adhesion to the core layer. When R2 / R1 is equal to or greater than the lower limit, the difference between the convex and smooth portions on the skin layer surface is appropriately large, resulting in better anti-blocking properties.

[0050] The particle size difference, expressed as (particle size R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) minus (particle size R1 at the largest peak a in the range of 0.1 to 2.5 μm), expressed as R2-R1, is preferably 0.1 to 6.0, more preferably 0.1 to 4.0, and even more preferably 0.2 to 3.5. When R2-R1 is equal to or less than the upper limit, the second antiblocking agent is more easily prevented from falling off the first skin layer, and the difference between the convex and smooth portions on the skin layer surface is reduced, resulting in better adhesion to the core layer. When R2-R1 is equal to or greater than the lower limit, the difference between the convex and smooth portions on the skin layer surface is appropriately large, resulting in better anti-blocking properties.

[0051] The mass ratio expressed as (content of first antiblocking agent) / (content of second antiblocking agent) relative to the total mass of the first skin layer is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3. When this mass ratio is equal to or less than the above upper limit, it becomes easier to prevent the second antiblocking agent from falling off the first skin layer, and the difference between the convex and smooth portions on the skin layer surface becomes smaller, thereby improving adhesion to the core layer. When this mass ratio is equal to or greater than the above lower limit, it becomes easier to improve the blocking resistance provided by the second antiblocking agent, and the difference between the convex and smooth portions on the skin layer surface becomes appropriate, thereby improving blocking resistance.

[0052] (phosphorus antioxidant) The first skin layer may include a phosphorus-based antioxidant. The content of the phosphorus-based antioxidant is preferably 300 ppm by mass to 1000 ppm by mass, more preferably 300 ppm by mass to 700 ppm by mass, relative to the total mass of the first skin layer. When the content of the phosphorus-based antioxidant is equal to or greater than the lower limit, the effect of suppressing changes in color and strength over time is excellent. When the content of the phosphorus-based antioxidant exceeds the upper limit, bleed-out over time is likely to cause deterioration in transparency, printing properties, and the like.

[0053] In the present disclosure, the thickness of the first skin layer is preferably 0.5 to 5.0 μm, more preferably 0.6 to 4.5 μm, and even more preferably 0.7 to 4.0 μm. When the thickness of the first skin layer is equal to or less than the upper limit, the blocking resistance derived from the antiblocking agent is more easily improved. When the thickness of the first skin layer is equal to or more than the lower limit, the mechanical strength of the polypropylene film is more easily maintained.

[0054] <Second Skin Layer> In the present disclosure, the polypropylene film may have a second skin layer on the opposite side of the core layer from the first skin layer. The second skin layer preferably contains the second polypropylene (B) and does not contain the first polypropylene (A). The second skin layer may be the same as the first skin layer. The composition of the first skin layer and the composition of the second skin layer may be the same or different, but preferably they are the same. The thickness of the first skin layer and the thickness of the second skin layer may be the same or different, but are preferably the same.

[0055] <Characteristics of polypropylene film> The polypropylene film may be uniaxially or biaxially stretched. The stretching ratio is preferably 3 to 6 times in the MD direction and 8 to 12 times in the TD direction, for example. The density of the polypropylene film is not particularly limited, but is, for example, 0.90 to 0.92 g / cm 3 The density is a value measured using a dry density meter, a density gradient tube, etc. The thickness of the polypropylene film is not particularly limited, but is, for example, 15 μm to 80 μm.

[0056] The resistance to removal of the antiblocking agent from the polypropylene film, which can be measured by the method described in the Examples, is preferably Grade 3 or less, more preferably Grade 2 or less, and even more preferably Grade 1. When the resistance to removal of the antiblocking agent is equal to or less than the above upper limit, it is easier to prevent a decrease in the commercial value of the product, and therefore it is easier to maintain excellent physical properties.

[0057] The YI value change rate (%) of the polypropylene film of the present disclosure, which can be measured by the method described in the Examples, is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. It may even be 0%. When the YI value change rate (%) is the above upper limit or less, it is easy to suppress changes in color and strength over time caused by the biomass-derived P units, which makes it easy to prevent a decrease in the commercial value of the product and also provides a superior environmental load reduction effect obtained by the biomass-derived P units.

[0058] The strength change rate (%) in tensile strength of the polypropylene film of the present disclosure, which can be measured by the method described in the Examples, is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. It may even be 0%. When the strength change rate (%) is equal to or less than the above upper limit, it is easy to suppress a decrease in mechanical strength caused by the biomass-derived P units, which makes it easy to prevent a decrease in the commercial value of the product and also provides a superior effect of reducing the environmental load obtained by the biomass-derived P units.

[0059] The transparency change rate (%) of the polypropylene film of the present disclosure, as measured by the method described in the Examples, is preferably 8% or less, more preferably 6% or less, and even more preferably 4% or less. It may even be 0%. When the YI value change rate (%) is equal to or less than the above upper limit, it is easy to suppress changes in color and strength over time caused by the biomass-derived P units, making it easier to prevent a decrease in the commercial value of the product and providing a superior environmental load reduction effect obtained by the biomass-derived P units.

[0060] The haze value (%) of the polypropylene film of the present disclosure, which can be measured by the method described in the Examples, is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. When the haze value (%) is the above upper limit or less, the visibility of the contents or printed matter is improved when the film is laminated onto a packaging bag or printed matter, and the film product has excellent functionality.

[0061] The blocking resistance of the polypropylene film of the present disclosure, which can be measured by the method described in the Examples, is preferably no more than Grade 3, more preferably no more than Grade 2, and even more preferably Grade 1. When the blocking resistance is no more than the above upper limit, it is easier to prevent films from adhering to each other during storage and becoming difficult to peel, making it easier to maintain the quality of the product, and therefore the storage stability and handling properties are also better.

[0062] The slipperiness of the polypropylene film of the present disclosure, which can be measured by the method described in the Examples, is preferably a dynamic friction coefficient of 0.70 or less, more preferably 0.60 or less, and even more preferably 0.50 or less. When the slipperiness is equal to or less than the upper limit, the film product is easy to handle in processes such as printing and bag making, and wrinkles are easily prevented from occurring during production or molding. When the slipperiness is equal to or greater than the lower limit, the film is prevented from slipping during winding during production or molding, resulting in better work efficiency.

[0063] <Polypropylene film manufacturing method> Examples of a method for producing a polypropylene film according to the present disclosure include forming a resin composition for a core layer containing polypropylene into a sheet to obtain an unstretched sheet, and biaxially stretching the unstretched sheet to obtain a polypropylene film for a core layer; forming a resin composition for a first skin layer containing polypropylene and an antiblocking agent into a sheet to obtain an unstretched sheet, and biaxially stretching the unstretched sheet to obtain a polypropylene film for a first skin layer; and laminating and adhering the obtained polypropylene film for a core layer and the polypropylene film for a first skin layer to obtain a laminate. As the biaxial stretching method, for example, a tenter sequential biaxial stretching method is preferred. From the viewpoint of adhesion between the core layer and the skin layers, the polypropylene film manufacturing method of the present disclosure is preferably a tenter sequential biaxial stretching method using a co-extrusion die. Specifically, a method including co-extrusion of a core layer resin composition and a first skin layer resin composition to obtain a laminate is preferred. By using a co-extrusion die, the polypropylene resin for the core layer can easily follow the irregularities on the surface of the polypropylene resin for the first skin layer, resulting in better adhesion between the first skin layer and the core layer. When a second skin layer is provided, a method including co-extruding a resin composition for the core layer, a resin composition for the first skin layer, and a resin composition for the second skin layer to obtain a laminate is preferred.

[0064] (Core layer resin composition) The resin composition for the core layer contains polypropylene, and the polypropylene preferably contains the first polypropylene (A). The content of the first polypropylene (A) relative to the total mass of the core layer resin composition is preferably 10 to 100 mass%, more preferably 15 to 100 mass%, and even more preferably 20 to 100 mass%. When the content is equal to or less than the upper limit, the effect of reducing the environmental impact obtained from the biomass-derived P units is more excellent. When the content is equal to or more than the lower limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product. In addition, the excellent physical properties obtained from the petroleum naphtha-derived P units are more easily improved.

[0065] The content of the phosphorus-based antioxidant relative to the total mass of the core layer resin composition is preferably 300 ppm by mass to 1000 ppm by mass, more preferably 300 ppm by mass to 700 ppm by mass. When the content of the phosphorus-based antioxidant is equal to or greater than the lower limit, the effect of suppressing changes in color and strength over time is excellent. When the content of the phosphorus-based antioxidant exceeds the upper limit, bleed-out over time tends to cause deterioration in transparency, printing properties, and the like.

[0066] The content of resin components other than the first polypropylene (A) is preferably 5 to 90% by mass, more preferably 10 to 85% by mass, and even more preferably 15 to 80% by mass, relative to the total mass of the core layer resin composition. When the content is equal to or less than the upper limit, the effect of reducing the environmental impact achieved by the biomass-derived P units is more excellent. When the content is equal to or greater than the lower limit, changes in color and strength over time caused by the biomass-derived P units are more easily suppressed, making it easier to prevent a decrease in the commercial value of the product. In addition, the excellent physical properties achieved by the petroleum naphtha-derived P units are more easily improved.

[0067] (Resin composition for first skin layer) The resin composition for the first skin layer contains polypropylene and an antiblocking agent. The content of the second polypropylene (B) relative to the total mass of the resin composition for the first skin layer is preferably 80 mass% or more, more preferably 85 mass% or more, even more preferably 90 mass% or more, and particularly preferably 95 mass% or more. It may be 100 mass%. When the content of the second polypropylene (B) is equal to or less than the above upper limit, excellent physical properties are easily maintained. When the content of the second polypropylene (B) is equal to or more than the above lower limit, the excellent physical properties obtained from the petroleum naphtha-derived P units are easily improved.

[0068] The content of the first antiblocking agent relative to the total mass of the resin composition for the first skin layer is preferably 0.05 to 0.7 mass%, more preferably 0.07 to 0.5 mass%, and even more preferably 0.1 to 0.3 mass%. When the content of the first antiblocking agent is equal to or less than the upper limit, the blocking resistance of the second antiblocking agent is easily improved. When the content of the first antiblocking agent is equal to or more than the lower limit, the adhesion to the core layer is better.

[0069] The content of the second antiblocking agent relative to the total mass of the resin composition for the first skin layer is preferably 0.01 to 0.4 mass%, more preferably 0.02 to 0.3 mass%, and even more preferably 0.02 to 0.2 mass%. When the content of the second antiblocking agent is equal to or less than the upper limit, adhesion to the core layer is superior. When the content of the second antiblocking agent is equal to or more than the lower limit, blocking resistance is easily improved.

[0070] (Resin composition for second skin layer) The resin composition for the second skin layer may be the same as the resin composition for the first skin layer.

[0071] <Laminate> A laminate according to one embodiment of the present disclosure is a laminate in which a plurality of layers are laminated together, at least one of which is made of the polypropylene film of the present disclosure. For example, there are laminates in which multiple polypropylene films of the present disclosure are laminated together, and laminates in which one or more layers of the polypropylene film of the present disclosure are laminated with one or more layers of a material different from the polypropylene film of the present disclosure. Examples of layers made of a material different from the polypropylene film of the present disclosure include resin films other than the polypropylene film of the present disclosure, paper, and the like. Examples of methods for producing the laminate include methods of laminating with other films, such as dry lamination and hot melt lamination, among which dry lamination using gravure roll coating equipment is preferred.

[0072] ≪Packaging materials≫ The packaging material of the present disclosure comprises the polypropylene film of the present disclosure. The polypropylene film may be used as a packaging material as it is, or the polypropylene film (F) may be processed to form a packaging material by any known processing method. For example, the end portions of a polypropylene film may be bonded together using an adhesive or heat-sealed to form a bag-shaped packaging material. Alternatively, the end portion of the polypropylene film of the present disclosure may be bonded or heat-sealed to an end portion of a packaging material other than the polypropylene film of the present disclosure to form a bag-shaped packaging material.

[0073] ≪Packaging body≫ A package according to one embodiment of the present disclosure is an article packaged in the packaging material of the present disclosure. Examples of the goods include general merchandise, food, clothing, etc. As the packaging method, known packaging methods can be applied.

[0074] <Action and effect> The polypropylene film of the present disclosure contains an antiblocking agent having at least two different particle sizes in the first skin layer. While the detailed mechanism of the effect achieved by using antiblocking agents having two different particle sizes is unclear, it is presumed to be as follows: When only an antiblocking agent with a large particle size is used, sufficient antiblocking properties are obtained, but adhesion to the core layer and ease of winding (handling) when rolled up are poor. Furthermore, since only large protrusions are formed, the antiblocking agent is prone to detachment due to frictional forces generated during handling. On the other hand, when only an antiblocking agent with a small particle size is used, sufficient adhesion to the core layer and ease of winding when rolled up are obtained, but only small protrusions are formed, resulting in poor antiblocking properties. To achieve a balance between these, it is presumed that using antiblocking agents with two different particle sizes can achieve antiblocking properties and slip resistance, prevention of antiblocking agent detachment, adhesion to the core layer, and ease of winding when rolled up. Furthermore, even when the polypropylene film of the present disclosure contains polypropylene derived from biomass raw materials in the core layer, it does not reduce color or tensile strength, and has excellent adhesion to the first skin layer containing an antiblocking agent, making it difficult to peel off, thereby preventing a decrease in product value and reducing environmental impact. [Example]

[0075] The present disclosure will be specifically described below with reference to examples. However, the present disclosure is not limited to these examples. Unless otherwise specified, the unit of content, "%", is "% by mass". The measurement and evaluation methods used in each example are shown below.

[0076] (1) Anti-blocking agent does not easily come off The film surfaces were rubbed together using a Daiei Kagaku Seiki Seisakusho "RT-300" friction fastness tester to measure the shedding of the antiblocking agent. Two types of samples were prepared: one for the friction element side and one for the measurement table side. The sample for the friction element side was cut to a size of 20 mm in the width direction and 70 mm in the machine direction. The sample for the measurement table side was cut to a size of 200 mm in the width direction and 170 mm in the machine direction. The surface of each sample was rubbed back and forth 10 times under conditions of a 200 g load, a sliding distance of 120 mm, and a reciprocating speed of 30 times / min. After rubbing, the area of ​​scratches on the measurement table sample surface was confirmed using a Keyence "VHX-2000" digital microscope, and the shedding of the antiblocking agent was evaluated according to the following criteria. Grade 1: No scratches Grade 2: Scratches occur, but the area is less than 10% of the friction area Grade 3: Scratches occur, but the area is between 10% and 25% of the friction area Grade 4: Scratches occur, but the area is between 25% and 50% of the friction area Grade 5: Scratches occur over 50% of the friction area The resistance of the antiblocking agent to coming off was evaluated according to the following criteria. ○: Anti-blocking agent removal is grade 2 or less ×: When the anti-blocking agent peeling property exceeds grade 2

[0077] (2) Color The YI value of the film was measured using a spectral colorimeter / haze meter "COH7700 (product name)" manufactured by Nippon Denshoku Industries Co., Ltd. The film was stored at 23°C for 3 months, and the YI value at the start of storage (initial YI) and the YI value after 3 months (YI after 3 months) were measured, and the YI value change rate (unit: %) was calculated using the following formula. The effect of suppressing the change in color over time was evaluated according to the following criteria. YI value change rate = (YI after 3 months - initial YI) / initial YI x 100 ○: Change in YI value after 3 months at 23℃ is within 20% ×: When the rate of change in YI value after 3 months at 23°C exceeds 20%

[0078] (3) Tensile strength The tensile strength in the machine direction was measured using a tensile tester in accordance with JIS K7127. Samples were cut to a size of 15 mm in the width direction x 200 mm in the machine direction, and the test was carried out at a tensile speed of 200 mm / min. The strength was measured when the film broke. The film was stored at 90°C for one month, and the strength at the start of storage (initial strength) and the strength after one month (strength after one month) were measured, and the strength change rate (unit: %) was calculated using the following formula. The effect of suppressing the change in tensile strength over time was evaluated according to the following criteria. Strength change rate = (initial strength - strength after 1 month) / initial strength x 100 ○: Strength change rate after 1 month at 90℃ is within 20% ×: When the strength change rate after 1 month at 90℃ exceeds 20%

[0079] (4) Transparency The transparency of the film was measured using a transparency meter, "CLARITY-METER TM-1D (product name)" manufactured by Murakami Color Research Laboratory Co., Ltd. The film was stored at 23°C for 3 months, and the transparency at the start of storage (initial transparency) and after 3 months (transparency after 3 months) were measured, and the transparency change rate (unit: %) was calculated using the following formula. The effect of suppressing the change in transparency over time was evaluated according to the following criteria. Transparency change rate = (initial transparency - transparency after 3 months) / initial transparency x 100 ○: Transparency change rate within 8% after 3 months at 23℃ ×: When the rate of change in transparency after 3 months at 23°C exceeds 8%

[0080] (5) Haze The haze was measured according to the method described in JIS K 7136:2000.

[0081] (6) Blocking resistance The sample was cut to a size of 50 mm in the width direction and 50 mm in the machine direction, and two films were stacked with the measurement surfaces facing each other. A 2 kg weight was placed on the stack, and the stack was stored at 40°C and 70% RH for 24 hours, after which the degree of blocking was measured by manual peeling. Grade 1: Peels off without resistance Grade 2: Peels off with some resistance Grade 3: Peels off with considerable resistance Grade 4: Does not peel off. Once peeled off, it slides on again if reapplied. Grade 5: Does not peel off. Once peeled off, it does not slip even when re-applied. The blocking resistance was evaluated according to the following criteria. ○: Blocking degree is grade 3 or less ×: Blocking degree exceeds grade 3

[0082] (7) Slipperiness The coefficient of friction was measured using a tensile tester. Two types of samples were prepared: one on the sliding side and one on the measurement table side. The sample on the sliding side was cut to a size of 120 mm in the width direction x 70 mm in the machine direction. The sample on the measurement table side was cut to a size of 150 mm in the width direction x 200 mm in the machine direction. The sample on the sliding side was wrapped in a 63 mm square, 1.96 N sliding piece, and the friction force was measured at a friction distance of 100 mm under conditions of 23°C, 50% RH, and a tensile speed of 200 mm / min, and the dynamic friction coefficient was calculated using the following formula. Coefficient of dynamic friction = frictional force at 100mm friction / weight of sliding piece The slipperiness was evaluated according to the following criteria. ○: Coefficient of dynamic friction is 0.70 or less ×: Coefficient of dynamic friction exceeds 0.70

[0083] (8) Reducing environmental impact ○: Contains biomass-derived polypropylene, resulting in low environmental impact. ×: The product has a large environmental impact because it does not contain biomass-derived polypropylene.

[0084] (9) The content of phosphorus-based antioxidants in polypropylene films was measured by extracting the antioxidants from the films and analyzing them with HPLC-PDA.

[0085] The content of biomass-derived P units in the polypropylene film was calculated based on the content of biomass-derived P units in each raw material resin composition and the blending ratio of each raw material resin composition. It can also be measured by measuring the C14 concentration using accelerator mass spectrometry (AMS).

[0086] <Raw materials> [Raw material resin composition containing first polypropylene (A)] The following Bio-PP (A1) is a resin composition containing polypropylene obtained by polymerizing propylene produced from raw naphtha, which is a mixture of 50% by mass of bio-naphtha and 50% by mass of petroleum naphtha, and tris(2,4-di-t-butylphenyl)phosphite, a phosphorus-based antioxidant. The content of biomass-derived P units relative to the total polypropylene units is 50% by mass. Bio-PP (A1): 99.20% by mass of polypropylene, 0.10% by mass of phosphorus-based antioxidant, 0.70% by mass of additives other than phosphorus-based antioxidant.

[0087] [Raw material resin composition containing second polypropylene (B)] The following petroleum PP (B1) is a resin composition containing polypropylene obtained by polymerizing propylene produced from 100% petroleum naphtha as a raw material, and tris(2,4-di-t-butylphenyl) phosphite, a phosphorus-based antioxidant. Petroleum PP (B1): Polypropylene 99.16% by mass, phosphorus-based antioxidant 0.04% by mass, additives other than phosphorus-based antioxidant 0.80% by mass.

[0088] [First anti-blocking agent] Organic anti-blocking agent (PMMA) (particle size: 0.4-4.0 μm, average particle size: 1.8 μm, manufactured by Sankyo Chemical Industry Co., Ltd.)

[0089] [Second anti-blocking agent] Organic anti-blocking agent (PMMA) (particle size: 0.6-10 μm, average particle size: 3.0 μm, manufactured by Sankyo Chemical Industry Co., Ltd.)

[0090] Example 1 The raw resin composition was melted at 230°C in an extruder and laminated in the extruder so that the thickness ratio of the first skin layer / core layer / second skin layer was 5 / 90 / 5, and an extrusion laminate sheet was obtained from a co-extrusion die. The core layer consisted of a mixture of petroleum PP (B1) and bio-PP (A1). The laminated sheet was cooled by contact with a roll at 30°C, stretched longitudinally at 140°C to 4.7 times its original size, and then stretched transversely at 165°C to 10 times its original size, resulting in a thickness of 30 μm and a density of 0.90 g / cm. 3 A biaxially oriented polypropylene film of 1000 mm was obtained. In this example, the content of biomass-derived P units is 10 mass % and the content of phosphorus-based antioxidant is 350 ppm relative to the mass of the polypropylene film.

[0091] <Examples 2 to 9> A biaxially oriented polypropylene film was produced in the same manner as in Example 1, except that the raw material composition and thickness were changed so as to obtain the composition shown in Tables 1 and 2.

[0092] <Evaluation> Each of the polypropylene films obtained in Examples 1 to 9 was evaluated for the items shown in the table. The results are shown in Tables 2 and 3.

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] As shown in the above results, the polypropylene films of Examples 1 to 9 had a small environmental impact and showed little change in color, mechanical properties, and transparency over time. They also had excellent storage stability and handling properties, suppressed the detachment of the antiblocking agent, and were excellent in blocking resistance and slipperiness. [Industrial Applicability]

[0097] The polypropylene film of the present disclosure is a polypropylene film that inhibits the antiblocking agent from falling off and has appropriate slip properties, and is useful as an excellent packaging material.

Claims

1. A polypropylene film comprising a core layer and a first skin layer, the core layer comprises polypropylene; the first skin layer comprises polypropylene and an antiblocking agent; the particle size distribution of the antiblocking agent in the first skin layer has two or more peak values; a ratio A expressed as (particle diameter R1 at the largest peak a in the range of 0.1 to 2.5 μm) / (thickness T1 of the first skin layer) is 0.2 to 2.5, a ratio B expressed as (particle diameter R2 at the largest peak b in the range of more than 2.5 μm and not more than 10 μm) / (thickness T1 of the first skin layer) is 1.0 to 4.5, the mass ratio represented by (content of the first antiblocking agent) / (content of the second antiblocking agent) is 1 to 10; Polypropylene film.

2. The polypropylene film according to claim 1, wherein the thickness of the first skin layer is 0.5 to 5.0 μm.

3. The polypropylene film according to claim 1, wherein the particle size of the antiblocking agent is 0.01 to 50 μm.

4. 2. The polypropylene film according to claim 1, wherein the antiblocking agent comprises at least one selected from the group consisting of resin particles, higher fatty acid particles, higher fatty acid amide particles, higher fatty acid metal salt particles, silica particles, talc particles, zeolite particles, kaolinite particles, and feldspar particles.

5. Further, it has a second skin layer, The polypropylene film according to claim 1 , wherein the first skin layer, the core layer, and the second skin layer are laminated in this order.

6. the core layer comprises biomass-derived propylene units; The polypropylene film according to claim 1, wherein the content of the biomass-derived propylene units is 10% by mass or more and 50% by mass or less relative to the total mass of the polypropylene film.

7. At least one of the core layer and the first skin layer contains a phosphorus-based antioxidant, The polypropylene film according to claim 1, wherein the content of the phosphorus-based antioxidant is 300 ppm by mass or more and 1000 ppm by mass or less, relative to the total mass of the polypropylene film.

8. A packaging material comprising the polypropylene film according to any one of claims 1 to 7.

9. A package in which an article is packaged with the packaging material according to claim 8.

Images