TW202438314A - Biaxially aligned polypropylene film and laminate thereof - Google Patents

Abstract

Provided is a biaxially oriented polypropylene film having exceptional thermal dimensional stability and mechanical strength, the biaxially oriented polypropylene film having exceptional workability when a vapor deposition layer, a coat layer, or another function layer is provided thereon, while also having exceptional adhesion to the function layer. This biaxially oriented polypropylene film has a base-material layer A composed of a polypropylene resin composition, and a surface layer B composed of a polypropylene resin composition, wherein the surface layer B is provided to one surface of the base-material layer A, and the following requirements (1) to (4) are met. (1) The surface layer B contains 25-85 mass% of a polypropylene resin having a melting point of 130-158 DEG C. (2) The wet tensile strength of the surface layer B is 36 mN/m or greater. (3) The sum of the thermal contraction rate in the longitudinal direction of the biaxially oriented polypropylene film at 150 DEG C and the thermal contraction rate in the width direction thereof at 150 DEG C is 0.0-25.0%. (4) The average three-dimensional roughness SRa of the surface layer B is 10 nm or greater.

Description

Biaxially aligned polypropylene film and laminate thereof

The present invention relates to a biaxially aligned polypropylene film and a laminate thereof.

Conventionally, biaxially oriented polypropylene films have been widely used as packaging materials for foods, fiber products, etc. due to their excellent transparency and mechanical properties. However, it is known that biaxially oriented polypropylene films lack slipperiness, may cause adhesion between films, and may have poor workability when processing the films, so anti-blocking agents are added.

When printing on biaxially aligned polypropylene film, the transfer of printing ink from the printing roller to the film surface and the adhesion of printing ink to the film surface are sought to be improved from the viewpoint of color development and fading of printing. However, since polypropylene resin is non-polar, the surface energy is small, and the adhesion of biaxially aligned polypropylene film to the vapor deposition layer, coating layer, printing ink, etc. is not sufficient.

As a film having improved adhesion to printing ink, for example, Patent Document 1 discloses that an anti-adhesive agent is blended in the film to provide a surface layer having a predetermined surface roughness and wet tension.

Furthermore, in the case where an aluminum vapor-deposited film is provided on the surface layer, a film having excellent adhesion to the aluminum vapor-deposited film is disclosed in Patent Document 2, for example, in which an anti-adhesive agent is formulated in the film to provide a surface layer having a relatively small surface roughness and a predetermined wet tension. [Prior Art Document] [Patent Document]

[Patent Document 1] International Publication No. 2018/142983. [Patent Document 2] International Publication No. 2022/004340.

[The problem that the invention wants to solve]

However, when the film described in Patent Document 1 has an aluminum vapor-deposited film on the surface layer, the adhesion to the aluminum vapor-deposited film is poor. Furthermore, the film described in Patent Document 2 has unstable elongation in the longitudinal direction and poor film-forming properties, and the obtained film has not only poor appearance but also unstable physical properties.

The purpose of the present invention is to provide a biaxially oriented polypropylene film having excellent thermal dimensional stability and mechanical strength and excellent appearance, which has excellent workability when a functional layer such as a vapor deposition layer or a coating layer is provided on the film, and also has excellent adhesion between the film and the functional layer. [Means for solving the problem]

As a result of intensive research to achieve the purpose, the present invention has solved the above-mentioned problem by providing a biaxially aligned polypropylene film having a base layer A composed of a polypropylene resin composition and a surface layer B composed of a polypropylene resin composition on one side of the base layer A, and controlling the composition of the polypropylene resin composition of the surface layer B and the film forming conditions. That is, the present invention is composed of the following configuration. [1] A biaxially oriented polypropylene film comprising a substrate layer A composed of a polypropylene resin composition and a surface layer B composed of a polypropylene resin composition; the surface layer B is provided on one side of the substrate layer A and satisfies the following (1) to (4): (1) the surface layer B contains 25% by mass or more and 85% by mass or less of a polypropylene resin having a melting point of 130°C or more and 158°C or less. (2) the wet tension of the surface layer B is 36 mN/m or more. (3) the sum of the heat shrinkage rate at 150°C in the length direction and the heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less. (4) The three-dimensional average roughness SRa of the surface layer B is greater than 10 nm. [2] The biaxially oriented polypropylene film as described in [1] above, wherein the surface resistance of the surface layer B is greater than 14.0 LogΩ. [3] The biaxially oriented polypropylene film as described in [1] or [2] above, wherein the Martens hardness of the surface layer B is less than 248 N/ ^mm2 . [4] The biaxially oriented polypropylene film as described in any one of [1] to [3] above, wherein the sum of the tensile modulus in the length direction and the tensile modulus in the width direction of the biaxially oriented polypropylene film is greater than 6.0 GPa and less than 10.0 GPa. [5] A biaxially oriented polypropylene film as described in any one of the above [1] to [4], wherein the other side of the above substrate layer A has a surface layer C, and the above surface layer C is composed of a polypropylene resin composition containing an anti-blocking agent. [6] A biaxially oriented polypropylene film as described in the above [5], wherein the three-dimensional average roughness SRa of the above surface layer C is greater than 15 nm. [7] A laminated body, wherein a functional layer is provided on the surface layer B of the biaxially oriented polypropylene film as described in any one of the above [1] to [6]. [8] A laminated body, which is a laminated body of the biaxially oriented polypropylene film as described in any one of the above [1] to [6] and a non-stretched polyolefin film. [9] A laminate, which is a laminate of the laminate described in [7] and a non-stretched polyolefin film, wherein the non-stretched polyolefin film is further provided on the functional layer. [Effect of the Invention]

According to the present invention, a biaxially oriented polypropylene film having excellent thermal dimensional stability and mechanical strength can be obtained. Furthermore, a biaxially oriented polypropylene film can be stably obtained, and when a functional layer such as a vapor deposition layer or a coating layer is provided on the film, the workability is excellent, and the film has excellent adhesion to the functional layer. Furthermore, when the biaxially oriented polypropylene film of the present invention is provided with a layer composed of metal and/or metal oxide, a laminate having high gas barrier properties can be obtained.

The biaxially aligned polypropylene film of the present invention comprises a substrate layer A composed of a polypropylene resin composition and a surface layer B composed of a polypropylene resin composition. The biaxially aligned polypropylene film of the present invention preferably further comprises a surface layer C. Specifically, the surface layer B is preferably provided on one side of the substrate layer A and the surface layer C is preferably provided on the other side of the substrate layer A.

Furthermore, the biaxially oriented polypropylene film of the present invention satisfies the following (1) to (4). In addition, in the following, "the biaxially oriented polypropylene film of the present invention" may be simply described as "film". (1) The surface layer B contains 25% by mass or more and 85% by mass or less of a polypropylene resin having a melting point of 130°C or more and 158°C or less. (2) The wet tension of the surface layer B is 36 mN/m or more. (3) The sum of the heat shrinkage rate at 150°C in the length direction and the heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less. (4) The three-dimensional average roughness SRa of the surface layer B is 10 nm or more.

(1) Substrate layer A Preferably, the thermal dimensional stability, mechanical strength and transparency of the biaxially oriented polypropylene film of the present invention are improved by using substrate layer A. Substrate layer A is composed of a polypropylene resin composition having a polypropylene homopolymer as a main component. In addition, the "main component" in the present invention means that 70% by mass or more of the entire substrate layer A is a polypropylene homopolymer, more preferably 80% by mass or more of the entire substrate layer A is a polypropylene homopolymer, further preferably 90% by mass or more of the entire substrate layer A is a polypropylene homopolymer, and particularly preferably 95% by mass or more of the entire substrate layer A is a polypropylene homopolymer.

(Polypropylene homopolymer) The polypropylene homopolymer used in the substrate layer A is a polypropylene polymer that does not substantially contain α-olefin components other than propylene, and specifically, is a polypropylene (co)polymer having α-olefin components other than propylene at a rate of less than 1 mol% and propylene at a rate of more than 99 mol% as constituent units. In addition, in the present specification, not only polypropylene homopolymers that do not contain α-olefin components other than propylene at all, but also polypropylene copolymers having α-olefin components other than propylene at a rate of less than 1 mol% and propylene at a rate of more than 99 mol% as constituent units are included in the polypropylene homopolymer. Even when α-olefin components other than propylene are included, the content of α-olefin components other than propylene (the total amount of ethylene and α-olefins having 4 or more carbon atoms) is, as described above, less than 1 mol%, preferably less than 0.3 mol%, more preferably less than 0.2 mol%, and further preferably less than 0.1 mol%. If it is within the above range, the crystallinity is easily improved. As the α-olefin component having more than 4 carbon atoms, for example, 1-butene, 1-pentene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 5-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, etc. The polypropylene homopolymer can also use two or more different polypropylene homopolymers.

Various suitable physical properties of the polypropylene homopolymer are described below. However, when two or more different polypropylene homopolymers are used, it is preferred that the mass average of the physical properties of the polypropylene homopolymers be within the numerical range described below.

The polypropylene homopolymer used in the substrate layer A preferably has a melting point of 160°C to 175°C, more preferably 164°C to 173°C, and further preferably 166°C to 171°C. If the melting point is above 160°C, the thermal dimensional stability and mechanical strength can be improved. If the melting point is below 175°C, it is easy to suppress the increase in the cost of polypropylene manufacturing, and it becomes less likely to break during film making. By mixing a crystallization nucleating agent in the aforementioned polypropylene resin, the melting point can also be further increased. The melting point is measured by a differential scanning calorimeter (DSC). 1 mg to 10 mg of the sample is placed in an aluminum pan and melted at 230°C for 5 minutes in a nitrogen atmosphere. The temperature is then lowered to 30°C at a scanning rate of -10°C/min, and then maintained for 5 minutes. The temperature is then raised at a scanning rate of 10°C/min. The main peak temperature of the endothermic peak accompanying the melting is observed.

The polypropylene homopolymer used in the substrate layer A preferably has a meso-pentaunit fraction ([mmmm]%) as an indicator of stereoregularity of 95.0% to 99.9%, more preferably 97.0% to 99.7%, further preferably 97.5% to 99.5%, and particularly preferably 98.0% to 99.3%. If it is 95.0% or more, the crystallinity of the polypropylene resin will be improved, and the melting point, crystallinity, and crystal orientation of the crystals in the substrate layer A will be improved, which can improve the thermal dimensional stability and mechanical strength. If it is 99.9% or less, it is easy to suppress the cost of polypropylene manufacturing and become less prone to breakage during film making. The meso-pentaunit fraction is measured by nuclear magnetic resonance (the so-called NMR (Nuclear Magnetic Resonance) method).

The melt flow rate (MFR) of the polypropylene homopolymer used in the substrate layer A is preferably 4.0 g/10 min to 30 g/10 min, more preferably 4.5 g/10 min to 25 g/10 min, even more preferably 4.8 g/10 min to 22 g/10 min, particularly preferably 5.0 g/10 min to 20 g/10 min, and most preferably 5.5 g/10 min to 10 g/10 min, when measured under condition M (230°C, 2.16 kgf) of JIS K 7210 (1995). If the MFR of the polypropylene resin is 4.0g/10min or more, the amount of low molecular weight components in the polypropylene resin constituting the substrate layer A increases, so the orientation crystallization of the polypropylene resin is further promoted, the crystallinity in the substrate layer A becomes easier to increase, and the entanglement between the polypropylene molecular chains in the amorphous part becomes less, so that the thermal dimensional stability and mechanical strength can be improved. Furthermore, if the MFR of the polypropylene resin is 30g/10min or less, it is easy to maintain the film forming properties of the film.

The polypropylene homopolymer used in the substrate layer A preferably has a weight average molecular weight (Mw) of 180,000 to 500,000. If Mw is less than 180,000, the melt viscosity is low, so there is a risk of instability during casting and poor film forming properties. If Mw exceeds 500,000, the amount of components with a molecular weight of less than 100,000 decreases, and there is a risk of reduced thermal shrinkage at high temperatures. Mw is more preferably 190,000 to 400,000, further preferably 200,000 to 380,000, and particularly preferably 210,000 to 350,000.

The number average molecular weight (Mn) of the polypropylene homopolymer used in the substrate layer A is preferably 20,000 to 200,000. If it is less than 20,000, the melt viscosity is low, so there is a risk of instability during casting and poor film forming properties. If it exceeds 200,000, there is a risk of reduced thermal shrinkage at high temperatures. Mn is more preferably 30,000 to 120,000, further preferably 40,000 to 110,000, particularly preferably 50,000 to 100,000, and most preferably 60,000 to 90,000.

The polypropylene homopolymer used in the substrate layer A preferably has an Mw/Mn of 2.8 or more and 10 or less, which is an indicator of molecular weight distribution. It is more preferably 3.0 or more and 8.0 or less, further preferably 3.2 or more and 6.0 or less, and particularly preferably 3.5 or more and 5.0 or less. If the Mw/Mn of the polypropylene homopolymer is 2.8 or more, since the ratio of low molecular weight components of the polypropylene resin constituting the substrate layer A increases, the orientation crystallization of the polypropylene resin is further promoted, the crystallinity in the substrate layer A becomes easier to increase, and the entanglement of the polypropylene molecular chains in the amorphous part becomes less, thereby being able to improve the thermal dimensional stability and mechanical strength. In addition, the molecular weight distribution of polypropylene homopolymer can be adjusted by polymerizing components of different molecular weights in a multi-stage series of equipment, or blending components of different molecular weights in an offline mixer, or polymerizing with catalysts with different properties, or using a catalyst that can achieve the desired molecular weight distribution.

(Other than polypropylene homopolymer) The propylene resin composition constituting the substrate layer A may also contain additives and other resins other than polypropylene homopolymer. Examples of additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, antifogging agents, flame retardants, inorganic or organic fillers, etc. Examples of other resins include polyolefin resins other than the polypropylene homopolymer used in the substrate layer A, and various elastomers. These components can also be polymerized stepwise using a multi-stage reactor, or blended with polypropylene resin using a Henschel mixer, or the masterbatch prepared in advance using a melt mixer can be diluted with polypropylene to a predetermined concentration, or the total amount can be melt-kneaded in advance for use. If the polypropylene resin used in the substrate layer A is a single substance, a surfactant can be added to reduce the surface resistance value when the surface resistance value is too large.

(2) Surface layer B When a functional layer such as a vapor deposition layer or a coating layer is preferably provided on the surface layer B, the adhesion of the functional layer becomes higher, and it is also preferred to further impart slip and anti-adhesion properties. In addition, the so-called functional layer is a layer having at least one function of coating, design, water vapor barrier, oxygen barrier, thermal conductivity, low dielectric, high dielectric, heat resistance, etc., for example, vapor deposition layer, coating layer, printing layer, etc. Surface layer B contains 25% by mass to 85% by mass of a polypropylene resin having a melting point of 130°C to 158°C. That is, the polypropylene resin composition constituting the surface layer B includes 25 mass % or more and 85 mass % or less of a polypropylene resin having a melting point of 130°C or more and 158°C or less. Furthermore, the surface layer B preferably includes a polypropylene resin having a melting point of 159°C or more and 175°C or less. On the other hand, in the surface layer B, it is preferred that the polypropylene resin having a melting point of 129°C or less is less, specifically, preferably 20 mass % or less, more preferably 10 mass % or less, further preferably 5 mass % or less, particularly preferably 1 mass % or less, and most preferably 0 mass % (excluding polypropylene resins below 129°C). In addition, in the following, the polypropylene resin with a melting point of 159°C to 175°C used in the surface layer B is sometimes referred to as a "high melting point polypropylene resin", the polypropylene resin with a melting point of 130°C to 158°C is sometimes referred to as a "medium melting point polypropylene resin", and the polypropylene resin with a melting point of 129°C or less is sometimes referred to as a "low melting point polypropylene resin". The melting point of the polypropylene resin used in the surface layer B is classified as a high melting point polypropylene resin, a medium melting point polypropylene resin, or a low melting point polypropylene resin based on the value obtained by rounding off the first decimal place. The high melting point polypropylene resin, the medium melting point polypropylene resin, and the low melting point polypropylene resin may be each made of only one type of polypropylene resin, or may be made of two or more different types of polypropylene resins.

By including 25 mass % or more and 85 mass % or less of the medium melting point polypropylene resin in the surface layer B, the adhesion with the vapor deposition layer, the coating layer, etc. can be improved. By having a melting point of 158°C or less, the adhesion with the functional layer can be improved. By having a melting point of 130°C or more, the productivity when the film is formed can be ensured, and the roughness of the film surface can be suppressed. The medium melting point polypropylene resin preferably has a melting point of 134°C or more and 150°C or less, and more preferably 138°C or more and 143°C or less. By having a content of 25 mass % or more of the medium melting point polypropylene resin, the adhesion with the vapor deposition layer, the coating layer, etc. can be improved. By making the content of the medium-melting point polypropylene resin less than 85 mass%, the film can ensure productivity during film making and can suppress the roughening of the film surface. The surface layer B preferably contains 30 mass% to 80 mass% of the medium-melting point polypropylene resin, and more preferably contains 35 mass% to 75 mass%.

On the other hand, in order to maintain the thermal dimensional stability and mechanical strength of the biaxially stretched polypropylene film, the surface layer B preferably contains a high melting point polypropylene resin having a higher melting point than the medium melting point polypropylene resin. The melting point of the high melting point polypropylene resin is preferably 160°C to 170°C, more preferably 161°C to 165°C. Furthermore, the surface layer B preferably contains 15% to 75% by mass of the high melting point polypropylene resin, more preferably 20% to 70% by mass, and further preferably 25% to 65% by mass.

When the surface layer B further comprises a high melting point polypropylene resin, the total amount of the high melting point polypropylene resin and the medium melting point polypropylene resin relative to the total resin contained in the surface layer B is preferably 60 mass % to 100 mass %, more preferably 70 mass % to 100 mass %, further preferably 80 mass % to 100 mass %, further preferably 90 mass % to 100 mass %, particularly preferably 95 mass % to 100 mass %, and most preferably 98 mass % to 100 mass %.

Various suitable physical properties of the medium-melting point polypropylene resin and the high-melting point polypropylene resin are described below. However, when two or more different polypropylene resins are used as the medium-melting point polypropylene resin, it is preferred that the mass average of the physical properties of each polypropylene resin be within the numerical range described below, and when two or more different polypropylene resins are used as the high-melting point polypropylene resin, it is preferred that the mass average of the physical properties of each polypropylene resin be within the numerical range described below.

The melt flow rate (MFR; 230°C, 2.16kgf) of the medium melting point polypropylene resin is preferably 2.0g/10min to 10g/10min, more preferably 3.0g/10min to 8.0g/10min, and further preferably 4.0g/10min to 7.0g/10min. The melt flow rate (MFR; 230°C, 2.16kgf) of the high melting point polypropylene resin is preferably 2.0g/10min to 10g/10min, and more preferably 3.0g/10min to 6.0g/10min. Furthermore, the difference between the MFR of the medium-melting point polypropylene resin and the MFR of the high-melting point polypropylene resin is preferably 2.0 g/10 minutes or less, more preferably 1.5 g/10 minutes or less.

The weight average molecular weight (Mw) of the medium melting point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 190,000 to 320,000, further preferably 200,000 to 300,000, and particularly preferably 230,000 to 260,000. If Mw is less than 180,000, the melt viscosity is low, so there is a risk of instability during casting and poor film forming properties. If Mw exceeds 500,000, the amount of components with a molecular weight of less than 100,000 becomes too small, so there is a risk of reduced thermal shrinkage at high temperatures.

The Mw of the high melting point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 210,000 to 400,000, further preferably 240,000 to 350,000, and particularly preferably 270,000 to 320,000. If the Mw is less than 180,000, the melt viscosity is low, so there is a risk of instability during casting and poor film forming properties. If the Mw exceeds 500,000, the amount of components with a molecular weight of less than 100,000 becomes too small, so there is a risk of reduced thermal shrinkage at high temperatures. Furthermore, it is preferred that the Mw of the high melting point polypropylene resin is greater than the Mw of the medium melting point polypropylene resin.

The number average molecular weight (Mn) of the medium melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, further preferably 40,000 to 70,000, and particularly preferably 45,000 to 55,000. If Mn is less than 20,000, the casting may be unstable due to the low melt viscosity, and the film forming property may be deteriorated. If Mn exceeds 200,000, the thermal shrinkage rate at high temperature may be reduced.

The Mn of the high melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, further preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000. If Mn is less than 20,000, the casting may be unstable due to the low melt viscosity, and the film forming property may be deteriorated. If Mn exceeds 200,000, the thermal shrinkage rate at high temperature may be reduced. Furthermore, it is preferred that the Mn of the high melting point polypropylene resin is greater than the Mn of the medium melting point polypropylene resin.

The molecular weight distribution (Mw/Mn) of the medium melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, further preferably 3.5 to 9.0, particularly preferably 4.0 to 8.0, and most preferably 4.5 to 6.0. The molecular weight distribution (Mw/Mn) of the high melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, further preferably 3.5 to 9.0, particularly preferably 3.7 to 8.0, and most preferably 4.0 to 6.0. Furthermore, it is preferred that the Mw/Mn of the high melting point polypropylene resin is greater than the Mw/Mn of the medium melting point polypropylene resin.

High melting point polypropylene resin, medium melting point polypropylene resin, and low melting point polypropylene resin are obtained by polymerizing raw material propylene using a known catalyst such as a Ziegler-Natta catalyst and a metallocene catalyst. In order to obtain a medium melting point polypropylene resin having a melting point of 130°C to 158°C, ethylene and/or an α-olefin having more than 4 carbon atoms may be copolymerized, and a polypropylene resin having a reduced stereoregularity due to the catalyst used may be used. However, a medium melting point polypropylene resin can be obtained even if ethylene and/or an α-olefin having more than 4 carbon atoms is not copolymerized. The content of α-olefin components other than propylene in the medium-melting point polypropylene-based resin (the total amount of ethylene and α-olefins having 4 or more carbon atoms) is preferably 0 mol % to 15 mol %, more preferably 2 mol % to 10 mol %.

The surface layer B may contain additives and other resins other than the polypropylene resin. Examples of additives include anti-adhesives, antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc. From the perspective of imparting slip and anti-adhesive properties to the surface layer B, the surface layer B preferably contains an anti-adhesive. Examples of other resins include polyolefin resins other than the polypropylene resin used in the surface layer B, and various elastomers. These components can also be polymerized gradually using a multi-stage reactor, or can be blended with a polypropylene resin using a Henschel mixer, or can be diluted with polypropylene in a predetermined concentration using a masterbatch prepared using a melt kneading machine, or can be melt-kneaded in advance for use. The total amount of the high melting point polypropylene resin and the medium melting point polypropylene resin is preferably 70% to 100% by mass, more preferably 80% to 100% by mass, further preferably 90% to 100% by mass, particularly preferably 95% to 100% by mass, and most preferably 98% to 100% by mass relative to the total resin contained in the surface layer B.

As an anti-adhesive agent, it is possible to appropriately select from inorganic and organic particles. Among these particles, silicon compounds are particularly preferred. Examples of silicon compounds include: silicon dioxide, silicates, and compounds having a main skeleton composed of siloxane bonds. Porous silicon dioxide microparticles are particularly preferred. When porous silicon dioxide is used, the pore volume is preferably 0.8 mL/g to 2 mL/g, and more preferably 1.1 mL/g to 1.8 mL/g. The shape of the particles may be spherical or amorphous, and amorphous particles are preferred. The preferred average particle size of the particles is from 1 μm to 5 μm, and more preferably from 2 μm to 4 μm. The average particle size is obtained by taking a photo with a scanning electron microscope and measuring the Feret diameter in the horizontal direction using an image analysis device, and the average value is set. The content of the anti-adhesive agent is preferably 100 ppm to 10,000 ppm in the total mass of the surface layer B, more preferably 300 ppm to 6,000 ppm, further preferably 800 ppm to 4,000 ppm, and particularly preferably 1,200 ppm to 2,700 ppm. By setting it within the above range, the three-dimensional average roughness and Martens hardness of the surface layer B can be set within the predetermined range described later. When the concentration is above 100ppm, the film has excellent slip and anti-blocking properties. When the concentration is below 10000ppm, it is unlikely to cause a decrease in light transmittance due to excessive addition of anti-blocking agent, the anti-blocking agent penetrating the functional layer when the functional layer is laminated, or the anti-blocking agent overflowing from the surface layer B causing the functional layer formed near the surface layer B to become detached, and it is unlikely to cause a decrease in barrier properties and poor adhesion.

When the surface layer B contains an anti-adhesive agent, the shedding rate of the anti-adhesive agent in the surface layer B is preferably 10% or less, more preferably 8% or less, further preferably 6% or less, and particularly preferably 4% or less. If the shedding rate is 10% or less, it is possible to suppress contamination of the guide roller in post-processing such as coating and evaporation. Furthermore, it is possible to suppress the generation of voids caused by the shedding of the anti-adhesive agent, and obtain a laminate having excellent gas barrier properties after evaporation of metal and/or metal oxide. The lower limit of the shedding rate is not particularly limited, but is, for example, 0.3% or more.

(3) Surface layer C Surface layer C is an arbitrarily set layer, which is mainly used to exhibit sliding and anti-adhesion properties. The melting point of the polypropylene resin used in surface layer C is preferably above 150°C in order to maintain thermal dimensional stability, mechanical strength, and productivity. In addition, as long as the polypropylene resin has a melting point of 175°C or less, it is economically easy to obtain and can inhibit the anti-adhesion agent from falling off from surface layer C.

The surface layer C is preferably composed of a polypropylene resin composition including a polypropylene resin having a melting point of 150°C to 175°C and an anti-blocking agent. The polypropylene resin having a melting point of 150°C to 175°C may be only one type of polypropylene resin or two or more different types of polypropylene resins. In the surface layer C, the total amount of the polypropylene resin having a melting point of 150°C to 175°C and the anti-blocking agent is preferably 90% by mass to 100% by mass, more preferably 95% by mass to 100% by mass, and further preferably 98% by mass to 100% by mass. The melting point of the polypropylene resin used in the surface layer C is preferably 154°C to 170°C, more preferably 158°C to 165°C.

The polypropylene resin having a melting point of 150°C to 175°C is preferably a polypropylene homopolymer (a polypropylene homopolymer containing no α-olefin components other than propylene and/or a polypropylene copolymer having less than 1 mol % of α-olefin components other than propylene and more than 99 mol % of propylene as constituent units).

Various suitable physical properties of a polypropylene resin having a melting point of 150°C to 175°C are described below. However, when two or more different polypropylene resins having a melting point of 150°C to 175°C are used, it is preferred that the mass average of the physical properties of the polypropylene resins be within the numerical range described below.

The weight average molecular weight (Mw) of the polypropylene resin with a melting point of 150°C to 175°C used in the surface layer C is preferably 180,000 to 500,000. If Mw is less than 180,000, the casting may be unstable due to the low melt viscosity, and the film-forming property may be poor. If Mw exceeds 500,000, the amount of components with a molecular weight of less than 100,000 will decrease, and there is a risk of a decrease in the thermal shrinkage rate at high temperatures. Mw is more preferably 190,000 to 400,000, further preferably 230,000 to 380,000, and particularly preferably 270,000 to 350,000.

The polypropylene resin having a melting point of 150°C to 175°C used for the surface layer C preferably has a number average molecular weight (Mn) of 20,000 to 200,000. If Mn is less than 20,000, the casting may be unstable due to low melt viscosity, and the film-forming property may be poor. If Mn exceeds 200,000, the thermal shrinkage rate at high temperature may be reduced. Mn is more preferably 30,000 to 80,000, more preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000.

The polypropylene resin having a melting point of 150°C to 175°C used for the surface layer C preferably has an Mw/Mn as an index of molecular weight distribution of 2.8 to 10, more preferably 3.2 to 8.0, further preferably 3.5 to 7.0, and particularly preferably 4.0 to 6.0.

The surface layer C may contain additives and other resins other than the polypropylene resin having a melting point of 150°C to 175°C. Examples of additives include anti-blocking agents, antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc. From the perspective of imparting slip and anti-blocking properties to the surface layer C, the surface layer C preferably contains an anti-blocking agent. Examples of other resins include polyolefin resins other than the polypropylene resin having a melting point of 150°C to 175°C, various elastomers, etc. These components can also be polymerized stepwise using a multi-stage reactor, or can be blended with a polypropylene resin using a Henschel mixer, or can be diluted with polypropylene in a predetermined concentration using a masterbatch prepared using a melt kneading machine, or can be melt-kneaded in advance for use. Of the total resins contained in the surface layer C, the polypropylene resin having a melting point of 150°C to 175°C preferably accounts for 80% to 100% by mass, more preferably 90% to 100% by mass, further preferably 95% to 100% by mass, and particularly preferably 98% to 100% by mass.

As an anti-adhesive agent, it is possible to appropriately select from inorganic and organic particles. Among these particles, silicon compounds are particularly preferred. Examples of silicon compounds include: silicon dioxide, silicates, and compounds having a main skeleton composed of siloxane bonds. Porous silicon dioxide microparticles are particularly preferred. When porous silicon dioxide is used, the pore volume is preferably 0.8 mL/g to 2 mL/g, and more preferably 1.1 mL/g to 1.8 mL/g. The anti-adhesive agent contained in the surface layer C is preferably the same as the anti-adhesive agent contained in the surface layer B. The particle shape may be spherical or amorphous, and it is preferred to use amorphous particles. The preferred average particle size of the particles is 1 μm to 5 μm, more preferably 2 μm to 4 μm. The average particle size is obtained by taking a picture with a scanning electron microscope, and using an image analyzer to measure the horizontal Feret diameter, which is set as the average value. The content of the anti-adhesive agent in the total mass of the surface layer C is preferably 100 ppm to 10,000 ppm, more preferably 300 ppm to 6,000 ppm, further preferably 800 ppm to 4,000 ppm, and particularly preferably 1,500 ppm to 3,000 ppm. By setting it within the above range, the three-dimensional average roughness and Martens hardness of the surface layer C can be set within the predetermined range described later. When the content is above 100ppm, the film has excellent slip and anti-blocking properties. When the content is below 10000ppm, it is not easy to reduce the light transmittance due to excessive addition of anti-blocking agent, the anti-blocking agent will penetrate the functional layer when the functional layer is laminated, or the anti-blocking agent overflowing from the surface layer C will cause the functional layer formed near the surface layer C to become detached, and it is not easy to reduce the barrier property and poor adhesion. The content of the anti-blocking agent in the surface layer C is preferably greater than the content of the anti-blocking agent in the surface layer B.

When the surface layer C contains an anti-adhesive agent, the shedding rate of the anti-adhesive agent in the surface layer C is preferably 10% or less, more preferably 8% or less, further preferably 6% or less, and particularly preferably 4% or less. As long as the shedding rate is 10% or less, it is possible to suppress contamination of the guide roller in post-processing such as coating and evaporation. Furthermore, it is possible to suppress the generation of voids caused by the shedding of the anti-adhesive agent, and obtain a laminate having excellent gas barrier properties after evaporation of metal and/or metal oxide. The lower limit of the shedding rate is not particularly limited, but is, for example, 0.3% or more.

(4) Layer structure and thickness structure of biaxially oriented polypropylene film The biaxially oriented polypropylene film of the present invention has a surface layer B on one side of a substrate layer A, and the surface layer B may be directly laminated on the surface of the substrate layer A, or another layer may be interposed between the substrate layer A and the surface layer B. Furthermore, when the other side of the substrate layer A has a surface layer C, the surface layer C may be directly laminated on the surface of the substrate layer A, or another layer may be interposed between the substrate layer A and the surface layer C. For example, the biaxially oriented polypropylene film of the present invention may be a two-layer structure of only surface layer B/substrate layer A, a three-layer structure of only surface layer B/substrate layer A/surface layer C, or a multi-layer structure of more than four layers including layers other than substrate layer A, surface layer B, and surface layer C. As a four-layer structure, for example: surface layer B/intermediate layer D/substrate layer A/surface layer C. By providing the intermediate layer D, the adhesion between substrate layer A and surface layer B can be further improved.

The overall thickness of the biaxially oriented polypropylene film of the present invention is preferably 5 μm to 100 μm, more preferably 10 μm to 80 μm, and further preferably 18 μm to 50 μm. Within the above range, the film has sufficient rigidity and is suitable as a substrate for packaging and industrial use.

The thickness of the surface layer B is preferably 0.3 μm to 10 μm, more preferably 0.5 μm to 3 μm, and further preferably 0.8 μm to 2 μm. If the thickness is 0.3 μm or more, the adhesion between the surface layer B and the functional layer can be improved, and it is suitable as a packaging and industrial base material that needs to be given a functional layer that is subjected to evaporation processing, coating processing, etc. If the thickness of the surface layer B is thicker than 10 μm, there is a risk that the thickness ratio of the base layer A will become relatively low, and as a result, there is a risk that the rigidity and thermal dimensional stability of the film will be reduced.

When the surface layer C is provided, the thickness of the surface layer C is preferably 0.3 μm to 10 μm, more preferably 0.5 μm to 5 μm, and further preferably 0.8 μm to 3 μm. When the thickness is 0.3 μm or more, the slip and processability of the film can be easily ensured. When the thickness of the surface layer C is thicker than 10 μm, the thickness ratio of the base layer A may become relatively low, and as a result, the rigidity and thermal dimensional stability of the film may be reduced.

The thickness of the substrate layer A is preferably 5 μm to 90 μm, more preferably 10 μm to 50 μm, and further preferably 15 μm to 30 μm. A thickness of 5 μm or more can improve the thermal dimensional stability and mechanical strength of the film. When the thickness of the substrate layer A is thicker than 90 μm, the thermal dimensional stability and mechanical strength can be improved, but there is a risk that the effect will be saturated.

The biaxially oriented polypropylene film of the present invention can be obtained by the following method: the polypropylene resin composition constituting each layer such as the substrate layer A and the surface layer B is melt-extruded by respective extruders, co-extruded from a die, cooled by a cooling roller to form an unstretched sheet, and the unstretched sheet is stretched in the length direction (MD (Machine Direction)) and the width direction (TD (Transverse Direction)), and then heat-fixed.

The melt extrusion temperature is preferably about 200°C to 280°C. In order to obtain a film with good appearance without disturbing the layers when the A layer and the B layer are co-extruded within this temperature range, it is preferably carried out in a manner that the difference between the MFR of the substrate layer A and the MFR of the surface layer B (hereinafter referred to as the MFR difference) is 5.0 g/10 minutes or less. If the MFR difference is greater than 5.0 g/10 minutes, the layers become disturbed and the appearance is likely to be poor. It is more preferably 4.0 g/10 minutes or less, and further preferably 3.0 g/10 minutes or less. Furthermore, when the surface layer C is provided, it is preferably carried out in a manner that the difference between the largest MFR and the smallest MFR of the three polypropylene resin compositions constituting the base layer A, the surface layer B, and the surface layer C is 5.0 g/10 minutes or less, and more preferably 3.0 g/10 minutes or less.

The surface temperature of the cooling roll is preferably 25°C to 50°C, more preferably 30°C to 45°C. If the cooling roll temperature is 50°C or less, the crystallization of the unstretched sheet and the growth of spherulites can be suppressed, thereby increasing the stretching ratio and obtaining a film with a high tensile modulus of elasticity. Furthermore, the occurrence of large concavities and convexities on the surface of the spherulites can be suppressed, and a film with an appropriate surface roughness can be obtained.

The lower limit of the stretch ratio in the longitudinal direction (MD) is preferably 3.5 times or more, more preferably 4 times or more. If it is 3.5 times or more, the thickness unevenness can be reduced. The upper limit of the stretch ratio in the MD is preferably 8 times or less, more preferably 7 times or less. If it is 8 times or less, it is not easy to cause breakage in the subsequent TD stretching and it is easy to produce.

The lower limit of the stretching temperature of MD is preferably 120°C or higher, more preferably 130°C or higher, and further preferably 135°C or higher. If it is above 120°C, the thickness unevenness is unlikely to increase, and the surface roughness of the film is unlikely to occur. When the stretching temperature of MD is high, it is unlikely that gaps will form around the anti-adhesive particles, and the roll contamination during processing caused by the fall of the anti-adhesive particles on the film surface can be prevented. Furthermore, good gas barrier properties can be obtained when aluminum vapor deposition is performed.

The upper limit of the stretching temperature in MD is preferably 150°C or less, more preferably 145°C or less, and further preferably 140°C or less. If the stretching temperature in MD is too high, the film starts to stick to the stretching rollers in MD, causing stick-slip, and there is a risk of unevenness and surface roughness in the film. Furthermore, if the stretching temperature in MD is increased, there is a risk that the film sticks to the stretching rollers and cannot be stretched.

The lower limit of the stretch ratio in the width direction (TD) is preferably 6 times or more, more preferably 7 times or more, and further preferably 8 times or more. If it is 6 times or more, the thickness unevenness is not easy to become large. The upper limit of the TD stretch ratio is preferably 15 times or less, more preferably 13 times or less, and further preferably 11 times or less. If it exceeds the above ratio, there is a risk of increased thermal shrinkage or more cracking during stretching.

When the mesopentamer component ratio of the polypropylene homopolymer constituting the substrate layer A is not high, the preheating temperature for TD stretching is preferably set to be 1°C to 5°C higher than the stretching temperature. When the mesopentamer component ratio of the polypropylene homopolymer constituting the substrate layer A is high, in order to quickly raise the preheating temperature for TD stretching to near the stretching temperature, the preheating temperature for TD stretching is preferably set to be 7°C to 20°C higher than the stretching temperature. The lower limit of the TD stretching temperature is preferably 150°C or higher, more preferably 152°C or higher, further preferably 154°C or higher, and particularly preferably 156°C or higher. If it is above 150°C, it is easy to soften sufficiently, and it is not easy to break or the thermal shrinkage rate becomes high. The upper limit of the TD stretching temperature is preferably 170° C. or lower, more preferably 168° C. or lower, and further preferably 166° C. or lower.

In order to reduce the thermal shrinkage rate, the heat fixation temperature is preferably high, more preferably 160°C or higher, and further preferably 162°C or higher. If it is above 160°C, the thermal shrinkage rate is not easy to increase, and it is not necessary to perform a long treatment to reduce the thermal shrinkage rate. The upper limit of the thermal fixation temperature is preferably below 180°C, and more preferably below 175°C. If it is below 180°C, it is not easy to cause the melting of low molecular components, the reduction of orientation due to recrystallization, and the surface roughness and whitening of the film.

It is better to relax (relax) during heat fixation. The lower limit of the relaxation rate is preferably 2% or more, more preferably 3% or more, and further preferably 5% or more. If it is 2% or more, the thermal shrinkage rate is less likely to increase. The upper limit of the relaxation rate is preferably 10% or less, more preferably 8% or less. If it is 10% or less, the thickness unevenness is less likely to increase.

Furthermore, in order to reduce the thermal shrinkage rate, the film produced in the above steps can be temporarily rolled into a roll and then annealed off-line.

The film obtained in this way can be subjected to corona discharge, plasma treatment, flame treatment, etc. as necessary, and then wound up with a winder to obtain the biaxially aligned polypropylene film roll of the present invention.

In addition, the method for manufacturing the biaxially aligned polypropylene film of the present invention is not limited to the above-mentioned manufacturing method.

(5) Various properties of the biaxially oriented polypropylene film of the present invention (Haze) The haze of the biaxially oriented polypropylene film of the present invention is preferably 8% or less, more preferably 5% or less, further preferably 4% or less, and particularly preferably 3% or less. If it is within the above range, it is easy to use in applications requiring transparency. The haze tends to deteriorate when the stretching temperature or heat setting temperature is too high, when the cooling roll temperature is high and the cooling speed of the unstretched (original film) sheet is slow, or when there are too many low molecular weight components with a molecular weight of less than 100,000. It can be set within the above range by adjusting these conditions.

(Tensile elastic modulus) The tensile elastic modulus of the biaxially oriented polypropylene film of the present invention in the length direction is preferably 1.0 GPa or more, more preferably 1.5 GPa or more, further preferably 1.8 GPa or more, and particularly preferably 2.0 GPa or more. The upper limit is not particularly limited, for example, it is 5.0 GPa or less. The tensile elastic modulus of the biaxially oriented polypropylene film of the present invention in the width direction is preferably 3.0 GPa or more, more preferably 3.2 GPa or more, and further preferably 3.5 GPa or more. The upper limit is not particularly limited, for example, it is 10 GPa or less. The sum of the tensile modulus in the length direction and the width direction of the biaxially oriented polypropylene film of the present invention is preferably 5.8 GPa to 12.0 GPa, and more preferably 6.0 GPa to 10.0 GPa. As long as the tensile modulus is within the above range, the toughness will be enhanced, and the film can still be used even if the thickness is thin, thereby reducing the cost. In addition, the so-called "length direction" in the biaxially oriented polypropylene film of the present invention is the direction corresponding to the traveling direction in the film manufacturing step, and the so-called "width direction" is the direction orthogonal to the traveling direction in the aforementioned film manufacturing step, and the same applies below.

(Heat shrinkage rate) The heat shrinkage rate of the biaxially oriented polypropylene film of the present invention in the longitudinal direction at 150°C is preferably 15.0% or less, more preferably 9.0% or less, further preferably 7.0% or less, and particularly preferably 5.0% or less. The lower limit of the heat shrinkage rate in the longitudinal direction at 150°C is preferably 0% or more. As long as it is within the above range, it can be used even in applications that may be exposed to high temperatures. Furthermore, even in the case where there is a functional layer in the film laminate, the reduction in the barrier properties of the functional layer can be suppressed, and as a result, the barrier properties of the laminate can be improved. The heat shrinkage rate of the biaxially oriented polypropylene film of the present invention in the width direction at 150°C is preferably less than 20.0%, more preferably less than 10.0%, and further preferably less than 8.0%. The lower limit of the heat shrinkage rate in the width direction at 150°C is preferably more than 0%. As long as it is within the above range, it can be used even in applications that may be exposed to high temperatures. Furthermore, even if there is a functional layer in the film laminate, the reduction in the barrier properties of the functional layer can be suppressed, and as a result, the barrier properties of the laminate can be improved. The sum of the heat shrinkage rates of the biaxially oriented polypropylene film of the present invention in the length direction and the width direction at 150°C is less than 25.0%, preferably less than 23.0%, more preferably less than 20.0%, further preferably less than 15.0%, and particularly preferably less than 12.0%. The lower limit of the sum of the heat shrinkage rates in the length direction and the width direction at 150°C is more than 0%. As long as it is within the above range, it can be used even in applications that may be exposed to high temperatures. Furthermore, even if there is a functional layer in the film laminate, the reduction in the barrier properties of the functional layer can be suppressed, and as a result, the barrier properties of the laminate can be improved.

(Wet tension) The wet tension of the surface layer B of the biaxially oriented polypropylene film of the present invention is 36mN/m or more, preferably 38mN/m or more, and more preferably 40mN/m or more. If the wet tension is 36mN/m or more, the adhesion with the functional layer will be improved. To set the wet tension to 36mN/m or more, it is better to perform physical and chemical surface treatment such as corona treatment and flame treatment. For the corona treatment, it is better to use a preheating roll and a treatment roll to discharge in the air. If the wet tension is too high, the sliding and anti-adhesion properties will deteriorate, so it is better to be 46mN/m or less.

The surface wetting tension of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 36 mN/m or more, more preferably 38 mN/m or more, and further preferably 40 mN/m or more, similarly to the surface layer B, when other materials are further layered on the surface layer C. If the wetting tension is too high, the sliding property and the anti-adhesion property will deteriorate, so it is preferably 46 mN/m or less. When other materials are not layered on the surface of the surface layer C, it is preferably 32 mN/m or less from the viewpoint of sliding property and anti-adhesion property.

(Surface resistance) The surface resistance of the surface layer B of the biaxially oriented polypropylene film of the present invention is preferably 14 LogΩ or more, more preferably 14.5 LogΩ or more, and further preferably 15 LogΩ or more. If the film contains additives such as antistatic agents and impurities, the surface resistance will be less than 14 LogΩ, so the adhesion will be poor. If the surface resistance is 14 LogΩ or more, it is better in terms of adhesion with the functional layer. The upper limit of the surface resistance of the surface layer B is not particularly limited, but it is 18 LogΩ or less in manufacturing.

The surface resistance value of the surface layer C of the biaxially aligned polypropylene film of the present invention is preferably 14 LogΩ or more, more preferably 14.5 LogΩ or more, and further preferably 15 LogΩ or more. If the film contains additives such as antistatic agents and impurities, the surface resistance value will become less than 14 LogΩ, so there will be a situation where the adhesion is deteriorated. If the surface resistance value is 14 LogΩ or more, it is better in terms of adhesion with the functional layer. The preferred upper limit of the surface resistance value of the surface layer C is not particularly limited, but it is 18 LogΩ or less in manufacturing.

(Martens hardness) The Martens hardness of the surface layer B of the biaxially oriented polypropylene film of the present invention is preferably 248 N/mm ² or less, more preferably 245 N/mm ² or less, further preferably 230 N/mm ² or less, and particularly preferably 210 N/mm ² or less. When the Martens hardness of the surface layer B is 248 N/mm ² or less, the adhesion between the surface layer B and the functional layer is improved. And even if the ratio of the thickness of the surface layer B to the thickness of the entire film is reduced, it is still easy to improve the adhesion. By setting a polypropylene resin, in which the surface layer B contains 25 mass % to 85 mass % of a polypropylene resin with a melting point of 130°C to 158°C, the Martens hardness can be set to 248 N/mm ² or less. Furthermore, the Martens hardness can be reduced by reducing the orientation crystallization of the molecular chain by adjusting the film forming conditions such as reducing the film stretching ratio. The lower limit of the Martens hardness of the surface layer B is preferably 150 N/mm ² or more, and more preferably 165 N/mm ² or more.

The Martens hardness of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 250 N/mm ² or more, more preferably 260 N/mm ² or more, and further preferably 270 N/mm ² or more. The upper limit of the Martens hardness of the surface layer C is preferably 350 N/mm ² or less, and more preferably 300 N/mm ² or less. The Martens hardness of the surface layer B is measured using a dynamic ultra-micro hardness tester under the conditions described in the embodiments described below. The Martens hardness of the surface layer C is also measured by the same method.

(Three-dimensional average roughness) The three-dimensional average roughness SRa of the surface layer B of the biaxially oriented polypropylene film of the present invention is 10 nm or more, preferably 10 nm or more and 100 nm or less, more preferably 13 nm or more and 90 nm or less, further preferably 15 nm or more and 80 nm or less, particularly preferably 17 nm or more and 70 nm or less, and most preferably 19 nm or more and 50 nm or less. If the three-dimensional average roughness of the surface layer B is 10 nm or more, the film has good slippage and can suppress the occurrence of wrinkles during post-processing such as rolling and evaporation. Furthermore, if the three-dimensional average roughness is 100 nm or less, the film has good transparency and can suppress the deterioration of workability due to excessive slippage of the film during post-processing such as rolling and evaporation.

The three-dimensional average roughness SRa of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 15 nm to 100 nm, more preferably 20 nm to 70 nm, and further preferably 30 nm to 50 nm. If the three-dimensional average roughness of the surface layer C is 15 nm or more, the film has good slippage and can suppress the occurrence of wrinkles during post-processing such as rolling and evaporation. Furthermore, if the three-dimensional average roughness is 100 nm or less, the film has good transparency and can suppress the deterioration of workability due to excessive slippage of the film during post-processing such as rolling and evaporation.

(6) Laminated body with functional layers The biaxially oriented polypropylene film of the present invention is not limited to packaging use, but can be used for industrial purposes. Furthermore, when the gas barrier property and designability of the biaxially oriented polypropylene film of the present invention are to be improved, it can be a laminated body with functional layers such as a vapor deposition layer, a coating layer, and a printing layer.

The material of the evaporated layer is preferably metal and/or metal oxide, more preferably aluminum, _Al2O3 , _SiOx (X _＜ 2), a mixture of _Al2O3 and _SiO2 , or a mixture of Al and _SiO2 , and more preferably aluminum or a mixture of Al and _SiO2 . The thickness of the evaporated layer is preferably 5nm to 40nm, more preferably _10nm to 30nm.

When the gas barrier property is to be improved, it is preferred to deposit and/or coat the biaxially aligned polypropylene film of the present invention. In the production of the deposited layer, there is no particular limitation as long as it is a known production method such as a PVD method (Physical Vapour Deposition) such as a vacuum evaporation method, a sputtering method, an ion coating method, or a CVD method (Chemical Vapor Deposition) method, but the physical evaporation method is preferred, and the vacuum evaporation method is more preferred. For example, in the vacuum evaporation method, aluminum _{, Al2O3} , _SiOx (X＜ ₂ ), a mixture of _Al2O3 and _SiO2 , a mixture of Al and _SiO2 , etc. can be used as the evaporation material, and the known methods such as resistance heating, high-frequency induction heating, and electron beam heating can be used as the heating method. Furthermore, as a reactive gas, oxygen, nitrogen, water vapor, etc. can be introduced, and reactive evaporation using means such as adding ozone and ion assistance can also be adopted. Furthermore, the manufacturing conditions can be changed as long as they are within the scope that does not damage the purpose of the present invention, such as applying a bias to the biaxially aligned polypropylene film of the present invention, or increasing or decreasing the temperature of the biaxially aligned polypropylene film of the present invention. The same applies to other manufacturing methods such as sputtering and CVD.

When the gas barrier property is to be improved, the coating layer material may include polyvinylidene chloride, nylon, butanediol-vinyl alcohol copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, etc. The coating layer preferably has a coating weight of 0.03 g/ ^m2 to 3 g/ ^m2 , more preferably 0.1 g/ ^m2 to 0.3 g/ ^m2 after drying.

The upper limit of the oxygen gas permeability of the evaporated film provided with the evaporated layer at a temperature of 23°C and a relative humidity of 65% is preferably 50mL/m ² /day/MPa, more preferably 39mL/m ² /day/MPa, further preferably 30mL/m ² /day/MPa, and particularly preferably 25mL/m ² /day/MPa. If the upper limit of the oxygen gas permeability is 50mL/m ² /day/MPa, the preservation of substances and foods that are deteriorated by oxygen is excellent. The lower limit of the oxygen gas permeability of the evaporated film at a temperature of 23°C and a relative humidity of 65% is not particularly limited, but from the perspective of productivity, it is preferably 0.1mL/m ² /day/MPa.

(7) Heat-sealable laminate The biaxially oriented polypropylene film of the present invention or the laminate in which the biaxially oriented polypropylene film is provided with a vapor deposition layer and/or a coating layer can be processed into a packaging bag as a heat-sealable laminate with a heat-sealable film laminated thereon when used for packaging, etc. Examples of heat-sealable films include: unstretched films, uniaxially stretched films, and biaxially stretched films made of low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, and polyester. Particularly preferred are unstretched films or uniaxially stretched films made of any one of low-density polyethylene, linear low-density polyethylene, and polypropylene. The surface on which the heat-sealable film is laminated may be the surface layer B side or the reverse surface layer B side. The heat-sealable film is preferably laminated via an adhesive layer. As adhesives, ester adhesives, urethane adhesives, acrylic adhesives, polyethyleneimine adhesives, etc. can be used. As a lamination method, dry lamination, extrusion lamination, co-extrusion, etc. can be applied. The packaging bag made by processing the biaxially oriented polypropylene film of the present invention or the laminated volume of the biaxially oriented polypropylene film provided with a vapor deposition layer and/or a coating layer and provided with a heat-sealable film is a packaging container with excellent filling and packaging suitability and storage suitability for various items such as beverages, pharmaceuticals, detergents, shampoos, oils, toothpastes, adhesives, and adhesives.

As an example of the layer structure of the heat-sealable laminate of the present invention, if the boundary of the layer structure is represented by /, for example: OPP/contact/LLDPE, OPP/contact/CPP, OPP/contact/Al/contact/CPP, OPP/contact/Al/contact/LLDPE, OPP/PE/Al/contact/LLDPE, OPP/contact/Al/PE/LLDPE, PET/contact/OPP/contact/LLDPE, PET/contact/OPP/PE/LLDPE, PET/contact/OPP/contact/Al/contact/LLDPE, PET/contact/Al/contact/OPP/contact/LLDPE, PET/contact/Al/contact/OPP/contact/LLDPE, PET/contact/Al/contact/OPP/PE/ LLDPE, PET/PE/Al/PE/OPP/PE/LLDPE, PET/OPP/CPP, PET/OPP/Al/CPP, PET/Al/OPP/CPP, OPP/PET/LLDPE, OPP/PET/PE/LLDPE, OPP/PET/CPP, OPP/Al/PET/ Connect to /LLDPE, OPP / Connect to /Al / Connect to /PET/PE/LLDPE, OPP/PE/LLDPE, OPP/PE/CPP, OPP/PE/Al/PE, OPP /PE/Al/PE/LLDPE, OPP/bond/OPP/bond/LLDPE, OPP/bond/general OPP/bond/LLDPE, OPP/bond/EVOH/bond/LLDPE, OPP/bond/EVOH/bond/CPP, OPP/bond/aluminum or inorganic oxide vaporized OPP/bond/LLDPE, general OPP/bond/aluminum or inorganic oxide vaporized OPP/bond/LLDPE, OPP/bond/aluminum or inorganic oxide vaporized general OPP/bond/LLDPE, OPP/bond/aluminum or inorganic oxide vaporized PET/bond/LLDPE, OPP/bond/aluminum vaporized OPP/bond/OPP/bond/LLDPE, OPP/connect/aluminum vapor-coated PET/connect/OPP/connect/LLDPE, OPP/connect/aluminum vapor-coated OPP/PE/LLDPE, OPP/connect/aluminum vapor-coated PET/PE/LLDPE, OPP/PE/aluminum vapor-coated OPP/PE/LLDPE, OPP/PE/aluminum vapor-coated PET/PE/LLDPE, OPP/connect/aluminum vapor-coated OPP/connect/CPP, OPP/connect/aluminum vapor-coated PET/connect/CPP, PET/connect/aluminum vapor-coated PET/connect/OPP/connect/LLDPE, CPP/connect/OPP/connect/LLDPE, OPP/connect/aluminum vapor-coated LLDPE, OPP/connect/aluminum vapor-coated CPP, etc. In addition, the abbreviations used in the above-mentioned layer structures are as follows: "Aluminum evaporation" means that aluminum is evaporated on the film; "Inorganic oxide evaporation" means that inorganic oxide is evaporated on the film; "Aluminum or inorganic oxide evaporation" means that aluminum or inorganic oxide is evaporated on the film. OPP (oriented polypropylene): biaxially oriented polypropylene film of the present invention PET (polyethylene terephthalate): stretched polyethylene terephthalate film LLDPE (linear low density polyethylene): unstretched linear low density polyethylene film PE (polyethylene): polyethylene film other than LLDPE CPP (cast polypropylene): unstretched polypropylene film General OPP: stretched polypropylene film that has been on the market Al: aluminum foil EVOH (Ethylene Vinyl Alcohol): ethylene-vinyl alcohol copolymer film Adhesive: adhesive layer that connects films to each other

This case claims the benefit of the priority of Japanese Patent Application No. 2023-012345 filed on January 30, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-012345 filed on January 30, 2023 are used for reference and are cited in this case. [Example]

Hereinafter, the present invention will be described by way of embodiments, but the present invention is not limited to these embodiments.

(Measurement method) The raw materials used in the examples and comparative examples and the physical properties of the obtained films were measured using the following methods. In addition, the following 1) to 4) were the physical properties of the polypropylene resin used in each layer, 5) to 17) were the physical properties of the biaxially aligned polypropylene film, and 18) to 21) were the physical properties of the biaxially aligned polypropylene film with other layers such as functional layers stacked on it.

1) Melting point Using a differential scanning calorimeter (DSC) manufactured by SII, 10 mg of the sample was placed in an aluminum pan and melted at 230°C for 5 minutes under a nitrogen atmosphere. The temperature was then lowered to 30°C at a scanning rate of -10°C/min, maintained for 5 minutes, and the temperature was raised at a scanning rate of 10°C/min. The main peak temperature of the endothermic peak accompanying the melting was set as the melting point.

2) Meso pentad fraction (mmmm) The meso pentad fraction was determined using ¹³ C-NMR (Carbon-13 nuclear magnetic resonance). The meso pentad fraction was calculated according to the method described in "Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973)". ¹³ C-NMR measurement was performed using "AVANCE500" manufactured by BRUKER, with 200 mg of the sample dissolved in a mixture of o-dichlorobenzene and heavy benzene (8:2 by volume) at 135°C and at 110°C.

3) Melt flow rate (MFR) Measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kgf.

4) Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) Gel permeation chromatography (GPC) was used to determine the molecular weight and molecular weight distribution of polypropylene resins based on monodisperse polystyrene standards. The measurement conditions for the column, solvent, etc. used in the GPC measurement are as follows. Solvent: 1,2,4-trichlorobenzene Column: TSKgel GMHHR-H(20)HT×3 Flow rate: 1.0ml/min Detector: RI (Refractive Index) Measurement temperature: 140℃

The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/ _Mn ) are defined by the following formulas based on the molecular weight (M _i ) of each elution position of the GPC curve obtained by the molecular weight calibration curve. Number average molecular weight: Mn = Σ(N _i・M _i )/ΣN _i Weight average molecular weight: Mw = Σ(N _i・M _i ² )/Σ(N _i・M _i ) Molecular weight distribution: Mw/Mn When the baseline is unclear, the baseline is set from the elution peak on the high molecular weight side (the elution peak closest to the standard substance) to the lowest position at the foot of the mountain on the high molecular weight side.

5) Thickness The cross section of the film fixed with the modified urethane resin was cut out using a microtome and observed using a differential interference microscope to measure the thickness of each layer.

6) Haze The haze of the film was measured at 23°C using a haze meter (300A manufactured by Nippon Denshoku Industries) in accordance with JIS K 7105. The measurement was performed twice and the average value was calculated.

7) Appearance The film surface was illuminated with a bromine light (VIDEO LIGHT VLG301 100V 300W manufactured by LPL) at about 45 degrees, and the appearance of the film was evaluated by visual observation according to the following criteria. A: No unevenness was observed in appearance that would cause problems for the product. B: Many uneven transparency caused by sticking and slipping of the stretching rollers in the longitudinal direction were observed. C: Many uneven transparency caused by sticking and slipping of the stretching rollers in the longitudinal direction were observed, which was a level that could not be adopted as a product.

8) Tensile modulus Use a razor to cut a sample of 10 mm in width and 180 mm in length from the film as a sample. The sample was measured in accordance with JIS K 7127. After being placed in an atmosphere of 23°C and a relative humidity of 65% for 12 hours, the sample was measured at 23°C and a relative humidity of 65% with a chuck distance of 100 mm and a tensile speed of 200 mm/min. The average value of the five measurement results was calculated as the tensile modulus in the length direction. As a measuring device, Autograph AG5000A manufactured by Shimadzu Corporation was used. Furthermore, a sample with a length of 180 mm in width and 10 mm in length was cut from the film using a razor, and the tensile modulus in width was obtained using the same measurement method as the tensile modulus in length.

9) Thermal shrinkage rate Measured in accordance with JIS Z 1712 using the following method. Cut the film into 20 mm width and 200 mm length in the length direction and width direction respectively, and hang it in a hot air oven at 150°C for 5 minutes. Measure the length after heating, and take the ratio of the length after shrinkage to the original length as the thermal shrinkage rate.

10) Wet tension (mN/m) According to JIS K 6768 (1999), the film was aged at 23°C and 50% relative humidity for 24 hours, and the wet tension of the surface layer B and the surface layer C was measured.

11) Surface resistance value In accordance with JIS K 6911 (1995), the film was aged at 23°C and 65% relative humidity for 24 hours, and the surface resistance values of surface layer B and surface layer C were measured.

12) Martens hardness The obtained film was cut into about 2 cm squares to prepare the sample, and the opposite side of the measurement surface was fixed with an adhesive on a glass plate with a thickness of about 1 mm, and then placed in an atmosphere of 23°C and a relative humidity of 50% for 12 hours for humidity adjustment. The Martens hardness of the surface layer B and the surface layer C of the above sample was measured using a dynamic ultra-micro hardness tester (DUH-211 manufactured by Shimadzu Corporation) in accordance with the method of ISO14577-1 (2002) under the following measurement conditions. The measurement was performed 10 times by changing the position of the film, and the average value of 8 points excluding the maximum and minimum points was obtained. <Test conditions> (settings) Test environment: temperature 23℃, relative humidity 50% Test mode: load-unload test Used indenter: 115 degree angle between edges, triangular cone indenter Indenter elastic modulus: 1.140×106N/mm ² indenter Poisson's ratio: 0.07 Cf-Ap,As correction: Yes (conditional) Test force: 0.10mN Load speed: 0.0050mN/sec Load holding time: 5sec Unloading holding time: 0sec

13) Three-dimensional average roughness SRa Using a contact-type three-dimensional surface roughness meter (manufactured by Kosaka Laboratory Co., Ltd.: Model ET-4000A), the average roughness SRa of surface layer B and surface layer C was measured by the stylus method under the following conditions. Stylus tip radius: 0.5μm Stylus pressure: 50μN Cutoff value: 800μm Measurement length: 500μm Measurement speed: 0.1μm/sec Measurement interval: 5μm

14) Anti-blocking agent shedding rate Using a universal tensile tester (STM-T-50BP manufactured by Toyo Baldwin), a weight of 0.5 kg (contact surface: 63 mm × 63 mm) mounted with velveteen fabric was overlapped with the measuring surface of the film, and a friction test was performed under the following conditions. Temperature: 23℃ Relative humidity: 50% Number of frictions: 5 times in a row for the part to be evaluated Tensile speed: 200mm/min After the above treatment, observation was performed using a table microscope ("TM3030Plus Miniscope" manufactured by Hitachi, Ltd.) at a magnification of 600 times, and the amount of all anti-adhesive agents observed and the amount of anti-adhesive agents that fell off the film were calculated. The anti-adhesive agent shedding rate was calculated using the following formula. Anti-adhesive agent shedding rate (%) = (the amount of anti-adhesive agents that fell off the film) / (the total amount of anti-adhesive agents observed and the amount of anti-adhesive agents that fell off the film) × 100

15) Dynamic friction coefficient Two films were prepared, and the surface layer B of one film was overlapped with the surface layer C of the other film. The coefficient of dynamic friction was measured in accordance with JIS K 7125 (1999) using a universal tensile tester STM-T-50BP (manufactured by Toyo Baldwin) at 23°C and a relative humidity of 50%.

16) Contamination of the guide roller After passing a 500m long film through the film using a slitter (NS-SLITTER FN-105 manufactured by Nishimura Seisakusho Co., Ltd.), the contamination of the guide roller was evaluated, and A was considered acceptable. A: No contamination of the guide roller. B: Slight contamination of the guide roller in some areas. C: The entire surface of the guide roller is contaminated.

17) Wrinkles on film roll The biaxially oriented polypropylene film was rolled up into a film roll with a width of 600 mm and a roll length of 1500 m using a cutter. The wrinkles on the surface of the film roll were visually evaluated according to the following criteria, and an A rating was considered acceptable. A+: No wrinkles. A: Although there are slight wrinkles, the wrinkles disappear when a tension of about 5 N/m is applied to the film being drawn out. B: Although there are slight wrinkles, the wrinkles disappear when a tension of about 20 N/m is applied to the film being drawn out. C: There are obvious wrinkles, and the wrinkles do not disappear even when a tension of about 20 N/m is applied to the film being drawn out.

18) Coating suitability Butanediol vinyl alcohol copolymer (Nichigo G-Polymer (registered trademark) OKS-8049Q manufactured by Mitsubishi Chemical Co., Ltd.) was dissolved in a 15% aqueous solution of isopropyl alcohol to prepare a coating liquid having a solid content concentration of 5%. The film was cut from the film roll obtained by the production method described in 17) above, and the prepared coating liquid was dropped onto the surface layer B and the surface layer C of the cut film, and the coating was performed using a winding rod #3 in such a manner that the coating amount became 0.2 g/ ^m2 in terms of solid content. Thereafter, the solution was fully volatilized using a dryer, and the shrinkage (cissing) of the coating layer was evaluated visually. The visual evaluation on the surface layer B is rated as A or above, and it is considered acceptable. However, when a functional layer is also provided on the surface layer C, it is preferred that the visual evaluation on both the surface layer B and the surface layer C is rated as A or above. A+: No shrinkage of the coating layer. A: The shrinkage of the coating layer is less than 90%, but there is slight shrinkage. B: There is shrinkage of part of the coating layer, and the shrinkage ratio is less than 90%. C: There is shrinkage of the coating layer on the entire surface.

19) Adhesion of aluminum vapor-deposited film The film was fed out from the film roll obtained by the manufacturing method described in 17) above, and vapor-deposited to a thickness of 30 nm on the surface layer B of the fed film using a small vacuum vapor-depositing device (VWR-400/ERH manufactured by ULVAC KIKO), thereby obtaining a vapor-deposited film having an aluminum vapor-deposited film on the surface layer B. CELLOTAPE (registered trademark) manufactured by NICHIBAN with a width of 18 mm was attached to the aluminum vapor-deposited film of the vapor-deposited film, and the adhesion of the aluminum vapor-deposited film was evaluated by the 90° peeling method, with A being judged as acceptable. A: No peeling of the aluminum vapor-deposited film. B: The aluminum vapor coating peeled off locally. C: The aluminum vapor coating peeled off on the entire surface.

20) Oxygen permeability of aluminum vapor-deposited film According to the electrolytic sensor method (Appendix A) of JIS K 7126-2, the oxygen permeability of the vapor-deposited film produced by the production method described in 19) above was measured at a temperature of 23°C and a relative humidity of 65% using an oxygen permeability measuring device (OX-TRAN 2/20 manufactured by MOCON). In addition, the oxygen permeability was measured in the direction of oxygen penetrating from the substrate layer A side to the aluminum vapor-deposited layer.

21) Lamination strength The lamination strength is measured by the following procedure. Procedure 1) The preparation of the laminate of the biaxially oriented polypropylene film and the unstretched polyethylene film is carried out using a continuous dry laminator as described below. The adhesive is gravure coated on the surface layer B side of the biaxially oriented polypropylene film obtained in the embodiment and the comparative example in such a manner that the coating amount during drying becomes 2.8 g/ ^m2 , and then guided to a drying zone for drying at 80°C for 5 seconds. It is then bonded to the sealant film between the rollers arranged on the downstream side (roller pressure: 0.2 MPa, roller temperature: 50°C). The obtained laminated film was aged at 40°C for 3 days in a rolled state. The adhesive was a urethane adhesive obtained by mixing 28.9% by mass of a main agent (TM569 manufactured by Toyo-Morton Co., Ltd.), 4.00% by mass of a hardener (CAT10L manufactured by Toyo-Morton Co., Ltd.), and 67.1% by mass of ethyl acetate, and the sealant film was a non-oriented polyethylene film (LIX (registered trademark) L4102, thickness 40 μm) manufactured by Toyobo Co., Ltd. Procedure 2) Determination of laminate strength The laminated film obtained above was cut into strips with the longitudinal direction of the biaxially oriented polypropylene film as the long side, and the strips were cut into strips with a length of 200 mm and a width of 15 mm. The peel strength was measured at a T-shaped peeling speed of 200 mm/min at 23°C and a relative humidity of 65% using a tensile tester (Tensilon, manufactured by ORIENTEC). The measurement was performed three times, and the average value was set as the laminate strength.

(Raw material resin) The details of the polypropylene resins PP-1 to PP-6 used as raw materials in the following examples and comparative examples are shown in Table 1. The anti-blocking agent masterbatch (hereinafter referred to as MB-1) uses PP-3 shown in Table 1 as the polypropylene resin, and as the anti-blocking agent (AB agent), porous silica particles with an average particle size of 2.9 μm and a pore volume of 1.6 mL/g are used. The content of the anti-blocking agent in MB-1 is 5.0 mass %.

[Table 1] PP-1 PP-2 PP-3 PP-4 PP-5 PP-6 Copolymerization amount of components other than propylene (mol %) 0 0 0 0 5.2 3 Copolymer components - - - - Ethylene, butene Ethylene MFR(g/10min) 7.5 2.5 5.6 3.2 6.0 7.0 [mmmm](%) 98.0 98.0 98.4 93.8 - - Tm(℃) 169 167 163 159 140 125 M 240,000 320,000 300,000 310,000 250,000 220,000 Mn 64,900 82,100 54,500 58,500 49,000 84,600 Mw/Mn(－) 3.7 3.9 5.5 5.3 5.1 2.6 ΔHc(J/g) 84 75 98 93 53 64

(Example 1) For the base layer A, PP-1 was mixed at a ratio of 70% by mass and PP-2 was mixed at a ratio of 30% by mass. For the surface layer B, PP-3 was mixed at a ratio of 26% by mass, PP-4 was mixed at a ratio of 20% by mass, PP-5 was mixed at a ratio of 50% by mass, and MB-1 was mixed at a ratio of 4% by mass. For the surface layer C, PP-3 was mixed at a ratio of 25% by mass, PP-4 was mixed at a ratio of 70% by mass, and MB-1 was mixed at a ratio of 5% by mass. The base layer A was extruded using a 45 mm extruder, the surface layer B was extruded using a 25 mm extruder, and the surface layer C was extruded using a 20 mm extruder. The raw resins were melted at 250°C and co-extruded into sheets from a T-die. The surface layer B was cooled and solidified by contacting a cooling roller at 30°C, and then stretched 4.5 times in the longitudinal direction (MD) at 135°C. Next, the film was clamped at both ends in the width direction with clips in a tenter, preheated at 173°C, stretched 8.2 times in the width direction (TD) at 164°C, relaxed by 6.7% in the width direction (TD), and heat-fixed at 171°C to obtain a laminate consisting of three layers: surface layer B/substrate layer A/surface layer C. The surface of the surface layer B of the laminate was subjected to a corona treatment using a corona treatment machine manufactured by Softal Corona & Plasma GmbH under the condition of applying a current value of 0.75A, and then taken up by a winder to obtain a biaxially oriented polypropylene film. The overall thickness of the obtained biaxially oriented polypropylene film is 20μm (the thickness of the surface layer B/substrate layer A/surface layer C is 1.3μm/17.7μm/1.0μm).

(Example 2 to Example 4, Comparative Example 1 to Comparative Example 2, Comparative Example 5 to Comparative Example 6) Except that the raw material composition of the surface layer B was changed as described in Table 2, a biaxially oriented polypropylene film was obtained under the same conditions as in Example 1. In addition, for Example 4 and Comparative Example 6, the raw material composition of the surface layer C was also changed as described in Table 2.

(Example 5) Except that the surface layer C was also subjected to a corona treatment, a biaxially aligned polypropylene film was obtained under the same conditions as in Example 1.

(Comparative Example 3) A biaxially oriented polypropylene film was obtained under the same conditions as in Example 1 except that the raw material composition of the surface layer B was changed as shown in Table 2, and PP-5, a polypropylene resin with a melting point of 140°C, was changed to PP-6, a polypropylene resin with a melting point of 125°C. However, during the longitudinal stretching, the film adhered to the stretching roller and the stretching starting point was unstable, so that the film could not be stretched uniformly, and thus a biaxially oriented polypropylene film could not be obtained stably.

(Comparative Example 4) Except that the raw material composition was the same as that of Comparative Example 3, the manufacturing conditions were changed as shown in Table 2, and the stretching temperature in the longitudinal direction was reduced by 10°C to 125°C. The biaxially oriented polypropylene film was obtained in the same manner as in Example 1.

(Comparative Example 7) Except that the raw material composition of the substrate layer A was changed as shown in Table 2, only PP-4, which is a polypropylene resin with a melting point of 159°C, was used in the raw material of the substrate layer A, and the manufacturing conditions were changed as shown in Table 2, a biaxially oriented polypropylene film was obtained under the same conditions as in Example 1.

(Comparative Example 8) A biaxially aligned polypropylene film was obtained under the same conditions as in Example 1 except that the surface layer B was not subjected to the corona treatment.

The raw material composition of each layer of the film of the example and the comparative example, the thickness of each layer, and the film production conditions are shown in Table 2, and various physical properties and various evaluations of the film of the example and the comparative example are shown in Table 3.

[Table 2] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Comparison Example 6 Comparative Example 7 Comparative Example 8 Substrate layer A raw material PP-1 Quality% 70 70 70 70 70 70 70 70 70 70 70 0 70 PP-2 Quality% 30 30 30 30 30 30 30 30 30 30 30 0 30 PP-4 Quality% 0 0 0 0 0 0 0 0 0 0 0 100 0 thickness μm 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 Surface layer B raw material PP-3 Quality% 26 twenty one 61 25 26 56 0 26 26 46 49.7 26 26 PP-4 Quality% 20 0 0 17 20 20 6 20 20 50 0 20 20 PP-5 Quality% 50 75 35 50 50 20 90 0 0 0 50 50 50 PP-6 Quality% 0 0 0 0 0 0 0 50 50 0 0 0 0 MB-1 Quality% 4 4 4 8 4 4 4 4 4 4 0.3 4 4 AB agent content Mass ppm 2000 2000 2000 4000 2000 2000 2000 2000 2000 2000 150 2000 2000 thickness μm 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 With or without corona surface treatment - have have have have have have have have have have have have without Surface layer C raw material PP-3 Quality% 25 25 25 25 25 25 25 25 25 25 25 25 25 PP-4 Quality% 70 70 70 67 70 70 70 70 70 70 74.7 70 70 MB-1 Quality% 5 5 5 8 5 5 5 5 5 5 0.3 5 5 AB agent content Mass ppm 2500 2500 2500 4000 2500 2500 2500 2500 2500 2500 150 2500 2500 thickness μm 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 With or without corona surface treatment - without without without without have without without without without without without without without Film making conditions Molten resin temperature ℃ 250 250 250 250 250 250 250 250 250 250 250 250 250 Cooling roller temperature ℃ 30 30 30 30 30 30 30 30 40 30 30 30 30 Lengthwise extension ratio times 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Lengthwise elongation temperature ℃ 135 135 135 135 135 135 135 135 125 135 135 135 135 Width direction elongation ratio times 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 Width direction extension preheating temperature ℃ 173 173 173 173 173 173 173 173 167 173 173 168 173 Width direction extension temperature ℃ 164 164 164 164 164 164 164 164 163 164 164 155 164 Heat fixation temperature ℃ 171 171 171 171 171 171 171 171 169 171 171 165 171 Width direction relaxation rate % 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 Film making properties - A A A A A A B C A A A A A

[Table 3] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Comparison Example 6 Comparative Example 7 Comparative Example 8 Membrane properties thickness μm 20 20 20 20 20 20 20 20 20 20 20 20 20 Fog % 2.4 2.8 2.1 4.2 2.4 1.9 4.5 - 2.0 2.7 2.7 2.4 2.4 Appearance - A A A A A A B B A A A A A Tensile modulus of elasticity (length direction) GPa 2.0 2.1 2.1 2.0 2.0 2.5 2.6 - 2.2 2.4 2.4 1.9 2.0 Tensile modulus (width direction) GPa 4.0 3.9 4.3 4.0 4.0 4.9 4.5 - 4.3 4.8 4.8 3.8 4.0 Sum of tensile elastic modulus GPa 6.0 6.0 6.4 6.0 6.0 7.4 7.1 - 6.5 7.2 7.2 5.7 6.0 150℃ thermal shrinkage (length direction) % 4.3 4.4 4.1 4.4 4.3 4.8 4.6 - 4.7 4.2 4.2 10.1 4.3 150℃ thermal shrinkage (width direction) % 7.3 7.1 6.9 7.4 7.3 5.8 7.8 - 6.3 7.3 7.3 18.4 7.3 The sum of thermal shrinkage at 150℃ % 11.6 11.5 11.0 11.8 11.6 10.6 12.4 - 11.0 11.5 11.5 28.5 11.6 Wet tension (layer B) mN/m 40 40 40 40 41 40 40 - 41 41 41 42 Under 30 Wet tension (C layer) mN/m Under 30 Under 30 Under 30 Under 30 41 Under 30 Under 30 - Under 30 Under 30 Under 30 Under 30 Under 30 Surface resistance (layer B) LogΩ 15.2 15.3 15.0 15.2 15.0 15.6 15.5 - 15.8 15.3 15.3 15.9 15.2 Surface resistance (C layer) LogΩ 15.1 15.4 15.3 15.4 15.3 15.5 15.2 - 15.4 15.1 15.5 15.4 15.5 Martens hardness (B layer) N/ ^mm2 188 175 199 190 188 250 164 - 170 278 182 231 188 Martens hardness (C layer) N/ ^mm2 280 279 284 281 280 283 290 - 285 280 280 295 280 3D average roughness SRa (B layer) nm 15 19 twenty one 31 17 32 28 - 15 19 9 50 15 3D average roughness SRa (C layer) nm 36 35 36 44 37 20 47 - 38 36 9 84 36 Anti-adhesion agent peeling rate (B layer) % 2.5 3.2 1.0 6.8 2.5 0.0 11.0 - 11.0 0.8 1.1 7.8 2.5 Anti-adhesive agent peeling rate (C layer) % 2.4 1.9 2.8 3.0 2.7 2.5 2.4 - 5.2 2.2 0.7 2.4 2.2 Dynamic friction coefficient (B layer/C layer) - 0.48 0.49 0.45 0.39 0.50 0.42 0.50 - 0.47 0.49 1 or more 0.47 0.40 Processing evaluation Dirty guide roller - A A A B A A - - B A A A A Wrinkles of membrane roll - A A A A A A - - A A C A A Coating suitability (B layer) - A A A A A A - - A A A A C Coating suitability (C layer) - C C C C A C - - C C C C C Adhesion of aluminum vapor-coated film (layer B) - A A A A A C - - B C A A C Oxygen permeability of aluminum vapor-deposited membrane mL/m ² /day/MPa twenty two 19 25 28 twenty two 48 - - 40 58 39 65 86 Laminated strength (longitudinal) (layer B) N/15mm 2.9 3.0 2.7 3.0 3.1 1.3 - - 2.9 1.1 2.9 2.7 1.0

The biaxially oriented polypropylene film obtained in Examples 1 to 5 has less dirt on the guide roll during post-processing, less wrinkles on the obtained film roll, and less shrinkage of the coating liquid on the B layer of the film cut from the film roll. Furthermore, when the aluminum vapor-deposited layer is evaporated, the aluminum vapor-deposited layer has excellent adhesion, and the oxygen permeability of the aluminum vapor-deposited film is low and the gas barrier property is excellent. Moreover, when the non-stretched polyethylene film is laminated, the lamination strength of the aforementioned biaxially oriented polypropylene film and the non-stretched polyethylene film is high. In contrast, the film of Comparative Example 1 has low lamination strength because the amount of polypropylene resin with a melting point of 130°C to 158°C is small in the surface layer B. Furthermore, when an aluminum vapor-deposited film is provided on the surface layer B, not only is the adhesion with the aluminum vapor-deposited film poor, but the oxygen permeability of the aluminum vapor-deposited film is high and the gas barrier property is poor. The film of Comparative Example 2 has unstable elongation in the longitudinal direction and poor film-making properties because the amount of polypropylene resin with a melting point of 130°C to 158°C is large in the surface layer B. The elongation in the longitudinal direction is uneven, resulting in a poor appearance of the biaxially oriented polypropylene film. Therefore, although the physical properties of the biaxially oriented polypropylene film were measured, the various evaluations of the lamination process, coating process, and evaporation process were estimated to be very poor, so these processing evaluations were not performed. Since the film of Comparative Example 3 was changed from PP-5, a polypropylene resin with a melting point of 140°C, to PP-6, a polypropylene resin with a melting point of 125°C in the resin composition of the surface layer B of Example 1, the elongation in the longitudinal direction became more unstable than that of Comparative Example 2, and the film forming property was poor. Since it was not possible to stably obtain a biaxially oriented polypropylene film, and since the stretching rollers in the longitudinal direction had a lot of stretching unevenness, and the appearance of the film was very poor, the physical property measurement and processing evaluation of the biaxially oriented polypropylene film were not performed. Regarding Comparative Example 4, unlike Comparative Example 3, a biaxially oriented polypropylene film was obtained by lowering the stretching temperature in the longitudinal direction, but when an aluminum vapor-deposited film was provided on the surface layer B, not only was the adhesion with the aluminum vapor-deposited film poor, but the oxygen permeability of the aluminum vapor-deposited film was high, and the gas barrier property was poor. Regarding Comparative Example 5, since the polypropylene resin with a melting point of 130°C to 158°C is not mixed in the surface layer B, the lamination strength is low. Furthermore, when an aluminum vapor-deposited film is provided on the surface layer B, not only is the adhesion with the aluminum vapor-deposited film poor, but the oxygen permeability of the aluminum vapor-deposited film is very high, and the gas barrier property is significantly poor. Regarding Comparative Example 6, since the amount of anti-adhesive agent mixed in the surface layer B and the surface layer C is small, the three-dimensional average roughness of the two surface layers is very small, and wrinkles will appear on the film roll when the film roll is rolled up. As a result, the workability is poor when aluminum vapor-deposited. Since the raw material of the substrate layer A of the film of Comparative Example 7 is set to a polypropylene resin with a melting point of 159°C, the sum of the thermal shrinkage rates at 150°C is high. Then, due to the high thermal shrinkage rate at 150°C, when an aluminum vapor-deposited film is provided on the surface layer B, the barrier properties of the aluminum vapor-deposited film are reduced, and as a result, the gas barrier properties of the aluminum vapor-deposited film are significantly poor. Regarding Comparative Example 8, since the surface layer B is not subjected to a corona treatment, the lamination strength is low. Furthermore, when a coating layer is provided on the surface layer B, shrinkage occurs. Furthermore, when an aluminum vapor-deposited film is provided on the surface layer B, not only is the adhesion with the aluminum vapor-deposited film poor, but the oxygen permeability of the aluminum vapor-deposited film is also very high, and the gas barrier property is significantly poor. [Industrial Applicability]

The biaxially oriented polypropylene film of the present invention is excellent in terms of thermal dimensional stability and mechanical strength. When a vapor deposition layer or a coating layer is provided on the biaxially oriented polypropylene film, the workability is excellent, and the adhesion with the vapor deposition layer or the coating layer is excellent. Therefore, it can be used as a substrate film for various processing. In particular, when the biaxially oriented polypropylene film of the present invention is provided with a layer composed of metal and/or metal oxide, a film with high gas barrier properties can be obtained, so it is suitable. Such a processed film can be used for food packaging, labeling, industrial film, etc., and is useful in industry.

Claims (9)

A biaxially oriented polypropylene film comprises: a substrate layer A composed of a polypropylene resin composition, and a surface layer B composed of a polypropylene resin composition; The surface layer B is provided on one side of the substrate layer A, and satisfies the following (1) to (4): (1) The surface layer B contains 25% by mass or more and 85% by mass or less of a polypropylene resin having a melting point of 130°C or more and 158°C or less; (2) The wet tension of the surface layer B is 36 mN/m or more; (3) The sum of the heat shrinkage rate at 150°C in the length direction and the heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less; (4) The three-dimensional average roughness SRa of the surface layer B is greater than 10 nm. The biaxially aligned polypropylene film as recited in claim 1, wherein the surface resistance value of the surface layer B is greater than 14.0 LogΩ. The biaxially aligned polypropylene film as recited in claim 1 or 2, wherein the Martens hardness of the surface layer B is less than 248 N/mm ² . The biaxially aligned polypropylene film as claimed in claim 1 or 2, wherein the sum of the tensile modulus of elasticity in the length direction and the tensile modulus of elasticity in the width direction of the biaxially aligned polypropylene film is greater than or equal to 6.0 GPa and less than or equal to 10.0 GPa. The biaxially aligned polypropylene film as recited in claim 1 or 2, wherein a surface layer C is provided on the other side of the substrate layer A, and the surface layer C is composed of a polypropylene resin composition containing an anti-blocking agent. The biaxially aligned polypropylene film as recited in claim 5, wherein the three-dimensional average roughness SRa of the surface layer C is greater than 15 nm. A laminate is formed by providing a functional layer on the surface layer B of the biaxially aligned polypropylene film as described in claim 1 or 2. A laminate is a laminate of a biaxially aligned polypropylene film and a non-stretched polyolefin film as described in claim 1 or 2. A laminate is a laminate of the laminate as described in claim 7 and a non-stretched polyolefin film, wherein the non-stretched polyolefin film is further provided on the functional layer.