Methods for manufacturing films, laminates, and resin composition films

Abstract

Provided is a film, at least one surface of which is A surface, the A surface being a surface having a skewness Ssk of -5 to 0, a load area proportion Smr2 of 70-98%, and a projection height Spk of 1-100 nm.　The film has no coarse projections, has a given recess structure, and is excellent in terms of release property, rigidity, and heat resistance.

Description

Technical Field

[0001] The present invention relates to a film, a laminate, and a method for producing a resin composition film having excellent releasability, rigidity, and heat resistance.

Background Art

[0002] Films are used in various applications such as packaging, surface protection, support in the manufacturing process of other members, sanitary products, agricultural products, building products, medical products, and capacitors. Among them, films used for surface protection or support (hereinafter sometimes referred to as surface protection films or support films) are used in the manufacturing process of optical members and electronic materials, and are therefore called process films. In recent years, with the increasing requirements for higher performance and higher quality of optical members and electronic materials, the required characteristics and quality of such process films have also been increasing.

[0003] Particularly, when forming a resin composition film for optical applications using a support film, a high degree of control of the surface shape of the support film is required. For example, Patent Document 1 describes an example in which the antiglare property of an optical film is improved and glare is suppressed by forming a phase-separated structure on the surface of a support film and transferring it.

[0004] In addition, the support film is required to have surface smoothness from the viewpoint of suppressing indentation transfer. However, if the surface smoothness is too high, the slipperiness of the resin composition film formed on the support film becomes low, and there may be a case where the quality is inferior due to the generation of foreign matter and wrinkles due to scratching of the surface. For example, Patent Document 2 describes an example in which fine particles are added to the surface of a polyethylene terephthalate (PET) film and controlled to a specific surface roughness to improve the slipperiness of an optical film and reduce defects.

[0005] In addition, Patent Document 3 describes an example in which, by controlling specific equipment and conditions in the casting process after melt-extruding a polymer, the depth of the valleys on the film surface and the valley-side void volume are kept low, and the high-temperature withstand voltage characteristics are improved. ​ [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-173546 [Patent Document 2] Japanese Patent Publication No. 2005-307038 [Patent Document 3] Patent No. 6115687 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the method described in Patent Document 1 above resulted in a large uneven surface structure on the transferred resin composition film, which sometimes led to inferior optical properties and quality. Furthermore, the method described in Patent Document 2 had the problem of insufficient slipperiness due to the low height of the protrusions on the surface of the transferred resin composition film. Furthermore, the method described in Patent Document 3 resulted in a high height of the protrusions on the surface, and a large depth of depressions on the surface of the transferred resin composition film, which sometimes led to inferior optical properties and quality.Therefore, the object of the present invention is to solve the above-mentioned problems. In other words, the object is to provide a film that, when used as a process film in the manufacturing process of a resin composition film, can achieve both improved optical properties and quality of the resulting resin composition film and good handling. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the film of the present invention has the following configuration: When a surface is defined as surface A, where the skewness Ssk is between -5 and 0, the load area ratio Smr2 is between 70% and 98%, and the protrusion height Spk is between 1 nm and 100 nm, at least one surface is surface A. The biaxially stretched material comprises at least one of an olefin-based elastomer resin and a polypropylene block copolymer. It's film.

[0009] The laminate of the present invention has the following configuration: The laminate has a resin composition layer on surface A of the film.

[0010] The present invention's method for producing a resin composition film has the following configuration: The method for producing a resin composition film comprises at least the following steps 1 to 3 in this order.

[0011] Step 1: A step of applying a coating agent containing a resin composition to the A-side of the film. Step 2: A step of solidifying the coating agent containing the resin composition to form a resin composition layer and a laminate. Step 3: A step of peeling the resin composition layer from the laminate to obtain a resin composition film.

[0012] In the present invention, it is preferable that the maximum valley depth Sv of surface A is 20 nm or more and 400 nm or less.

[0013] In the present invention, it is preferable that the coefficient of dynamic friction μd between one surface and the other surface of the film is 0.20 or more and 0.80 or less.

[0014] The film of the present invention preferably has a Young's modulus in the film MD direction of 130°C of 100 MPa or more and 200 MPa or less.

[0015] The film of the present invention preferably has a melting peak at 160°C or higher when heated from 30°C to 260°C using a differential scanning calorimeter (DSC).

[0016] The film of the present invention preferably has an internal haze of 0.01% to 1.5% after heating at 130°C for 10 minutes.

[0017] The film of the present invention preferably has a surface free energy of surface A of 15 mN / m or more and 35 mN / m or less.

[0018] In the present invention, it is preferable that the surface layer having surface A is mainly composed of an olefin resin.

[0019] The film of the present invention contains at least one of an olefin-based elastomer resin and a polypropylene block copolymer. nothing.

[0020] The film of the present invention is preferably used as a process film.

Advantages of the Invention

[0021] According to the present invention, when used as a process film in the manufacturing process of a resin composition film, it is possible to provide a film that can achieve both improved optical properties and quality of the obtained resin composition film and good handling properties. In addition, since the film of the present invention also has excellent heat resistance and release properties, the film of the present invention can be widely and preferably used as a film for industrial materials, particularly as a process film such as a protective film or a support film.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram conceptually showing the load area ratio Smr2 and the peak height Spk of the protrusion.

Embodiments for Carrying Out the Invention

[0023] When the film of the present invention has a skewness Ssk of -5 or more and 0 or less, a load area ratio Smr2 of 70% or more and 98% or less, and a peak height Spk of the protrusion of 1 nm or more and 100 nm or less, and a surface is defined as surface A, at least one side is surface A. By having surface A on at least one side of the film, the smoothness and handling properties of the resin composition film obtained by applying a coating containing the resin composition on this surface A, solidifying it, and peeling it off can be enhanced. Hereinafter, the skewness Ssk, the load area ratio Smr2, and the peak height Spk of the protrusion may be simply referred to as Ssk, Smr2, and Spk, respectively.

[0024] Ssk is a parameter defined in ISO 25178-2:2012 and is also called skewness. Details of its measurement conditions are shown in the examples. Generally, when Ssk > 0, there are many fine peaks, and when Ssk < 0, there are many fine valleys. The vast majority of industrial films have a protruding structure on the film surface to ensure smoothness, and films with recessed structures between these protrusions are very rare. In the film of the present invention, it is important that there are many recessed structures (valleys) relative to the protruding structures (peaks), which corresponds to Ssk being 0 or less.

[0025] A Ssk value greater than 0 indicates that the film surface has more protruding structures than recessed structures. Therefore, for example, when used as a support film, fewer protrusions are transferred to the resin composition film obtained by applying a coating containing a resin composition to the film, solidifying it, and then peeling it off. This can result in insufficient slipperiness in the resulting resin composition film and poor handling. On the other hand, a Ssk value less than -5 indicates that the film surface has extremely few protrusions. Therefore, the slipperiness during film formation and processing as a support film may be low, resulting in reduced handling.

[0026] To make the Ssk between -5 and 0, for example, the raw material composition of the film is set within the range described later, and the film-forming conditions are also set within the range described later. In particular, the Ssk can be reduced by including at least one of an olefin-based elastomer resin and a polypropylene block copolymer in the film in addition to the main component resin, performing initial longitudinal stretching at a temperature above the softening temperature of the olefin-based elastomer resin and polypropylene block copolymer formed in the main component resin, and then performing a second longitudinal stretch at a temperature above the softening temperature of the main component resin.

[0027] In the film of the present invention, from the viewpoint of transferring and forming protrusions on a resin composition film obtained by applying a coating agent containing a resin composition to surface A, solidifying it, and peeling it off, the skewness Ssk of surface A is preferably -0.001 or less, more preferably -0.01 or less. Furthermore, from the viewpoint of increasing the height of the protrusions in the resin composition film obtained by the above method and improving handling properties, the Ssk of surface A is preferably -3 or more, more preferably -1.5 or more, and even more preferably -0.5 or more.

[0028] Smr2 is a parameter specified in ISO 25178-2:2012, and its detailed measurement conditions are shown in the examples. As shown in Figure 1, a conceptual diagram illustrating the load area ratio Smr2 and the protruding peak height Spk, Smr2 (indicated by 1) is the load area ratio at the point where the load curve intersects the boundary line between the protruding valley and the core, when the equivalent line (indicated by 3) is the straight line with the gentlest slope when the load curve is drawn with a load area ratio difference ΔSmr of 40% in the central part of the load curve for the roughness curve (indicated by 2), and the core is defined as the area between the two height positions where the equivalent line intersects the vertical axis at load area ratios of 0% and 100%, representing the proportion of the protruding valley. Note that the load curve is the load curve for the surface and is expressed as a function of the load area ratio at the cutting level.

[0029] Generally, a higher Smr2 value indicates smaller core valleys and finer surface indentations on the film, while a lower Smr2 value indicates larger core valleys and coarser surface indentations. When Smr2 is greater than 98%, the indentation depth on the film surface is insufficient. Therefore, for example, when used as a support film, the height of the protrusions transferred to the resin composition film obtained by applying a coating containing the resin composition to the film, solidifying it, and then peeling it off will be low, resulting in insufficient slipperiness of the resulting resin composition film and poor handling. On the other hand, when Smr2 is less than 70%, the core valleys are extremely large, there are few flat core areas, and the film surface has a wavy shape. Therefore, for example, when used as a support film as described above, the transparency of the resulting resin composition film may be impaired.

[0030] To achieve an Smr2 of 70% or more, for example, one can increase the amount of olefin-based elastomer resin in the film, use an olefin-based elastomer with a lower softening temperature, increase the initial longitudinal stretching ratio during longitudinal stretching, or lower the initial longitudinal stretching temperature.

[0031] In the film of the present invention, a coating agent containing a resin composition is applied to surface A, solidified, and peeled off to obtain a resin composition film. From the viewpoint of transferring and forming protrusions of appropriate height on the resulting film to improve handling, the Smr2 of surface A is preferably 95% or less, and more preferably 92% or less. Furthermore, from the viewpoint of the smoothness of the resin composition film obtained by the above method, the Smr2 of surface A is preferably 80% or more, and more preferably 85% or more.

[0032] Spk is a parameter specified in ISO25178-2:2012, and detailed measurement conditions are shown in the examples. As shown in Figure 1, a conceptual diagram illustrating the load area ratio Smr2 and the protruding peak height Spk, Spk (indicated by 4) is the average height of the protruding peaks above the core, where the equivalent straight line (indicated by 3) is the straight line with the gentlest slope when the secant line of the load curve drawn with a load area ratio difference ΔSmr of 40% in the central part of the load curve for the roughness curve (indicated by 2) is drawn, and the core is defined as the area between the two height positions where the equivalent straight line intersects the vertical axis at load area ratios of 0% and 100%.

[0033] If the Spk is greater than 100 nm, the protrusions on the film surface become coarse. Therefore, for example, when used as a support film, if a coating agent containing a resin composition is applied to the film, solidified, and peeled off, coarse depressions may be formed in the resulting resin composition film. These depressions can become the starting point for peeling defects when the resin composition film is peeled off, potentially leading to peeling defects and film rupture.

[0034] To achieve a Spk of 1 nm to 100 nm, for example, a method can be used in which the raw material composition of the film is within the range described later, and the film-forming conditions are within the range described later. In particular, the Spk value can be lowered by including branched polypropylene resin to reduce the size of spherulites formed during casting, lowering the extrusion temperature and the temperature of the casting drum to improve cooling during casting, and increasing the preheating temperature during longitudinal / transverse stretching to perform high-magnification stretching at low temperatures and uniformly.

[0035] In the film of the present invention, from the viewpoint of improving the smoothness of the resin composition film obtained by applying a coating agent containing a resin composition to surface A, solidifying it, and peeling it off, the Spk of surface A is preferably 70 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. Furthermore, the lower the Spk of surface A, the better, but from the viewpoint of feasibility, the lower limit is 1 nm.

[0036] From the viewpoint of achieving both smoothness and handling properties of the resin composition film obtained when the film of the present invention is used as a support film, the maximum valley depth Sv (hereinafter sometimes simply referred to as Sv) of surface A is preferably 20 nm or more and 400 nm or less. From the viewpoint of smoothness of the resin composition film, the Sv of surface A is more preferably 300 nm or less, and even more preferably 250 nm or less. Furthermore, from the viewpoint of handling properties of the resin composition film, the Sv of surface A is more preferably 30 nm or more, even more preferably 40 nm or more, and particularly preferably 50 nm or more. Sv is a parameter specified in ISO 25178-2:2012 and indicates the depth of the deepest pit from the average surface (the surface where the height is the average value, corresponding to the baseline). The detailed measurement conditions are shown in the examples.

[0037] When Sv is 20 nm or higher, it is possible to prevent the recess depth of surface A from becoming excessively low. Therefore, for example, when used as a support film as described above, protrusions of sufficient height are formed on the resulting resin composition film, improving the slipperiness and handling properties of the resin composition film. On the other hand, when Sv is 400 nm or less, the size of the recess on surface A can be suppressed. Therefore, for example, when used as a support film, large recesses are not formed on the resin composition film obtained by applying a coating agent containing the resin composition to surface A of the film, solidifying it, and peeling it off, thereby improving the smoothness of the resin composition film. Furthermore, the transparency of the support film is also excellent, reducing problems when inspecting it with a defect inspection machine while it is bonded to the substrate.

[0038] To achieve a Sv of 20 nm to 400 nm, for example, a method can be used in which the raw material composition of the film is within the range described later, and the film-forming conditions are within the range described later. In particular, the Sv can be reduced by lowering the viscosity of the olefin-based elastomer resin and polypropylene block copolymer, or by pre-compounding the olefin-based elastomer resin and polypropylene block copolymer with the resin that is the main component of each layer's raw material to finely disperse the rubber domains.

[0039] From the viewpoint of improving quality, the film of the present invention preferably has a dynamic friction coefficient μd (hereinafter sometimes simply referred to as μd) between one surface and the other surface of 0.20 or more and 0.80 or less. From the above viewpoint, the μd between one surface and the other surface is more preferably 0.70 or less, and even more preferably 0.60 or less. Furthermore, the lower the μd between one surface and the other surface, the better, and there is no particular lower limit, but from the viewpoint of feasibility it is about 0.20. By setting μd to 0.80 or less, the slipperiness of the film is improved, so the generation of wrinkles and scraped foreign matter during film transport is suppressed and quality is improved.

[0040] To achieve a μd difference of 0.20 to 0.80 between one surface and the other, for example, a method can be used in which the raw material composition of the film is within the range described later, and the film-forming conditions are within the range described later. In particular, it is effective to include branched polypropylene resin and reduce the size of the spherulites formed during casting to create fine protrusions on the stretched film surface. In this case, increasing the amount of branched polypropylene resin can lower the μd difference between one surface and the other.

[0041] The film of the present invention may be coated with a resin composition and dried in a high-temperature oven at approximately 130°C. From the viewpoint of reducing the occurrence of wrinkles in such a high-temperature oven, it is preferable that the Young's modulus in the MD direction of the film at 130°C (hereinafter sometimes simply referred to as the Young's modulus in the MD direction) is 100 MPa or more and 200 MPa or less. From the above viewpoint, the Young's modulus in the MD direction is more preferably 120 MPa or more, and even more preferably 140 MPa or more. The higher the Young's modulus in the MD direction of the film at 130°C, the better, and there is no particular limit, but 200 MPa is the upper limit in terms of feasibility. The MD direction of the film refers to the direction parallel to the direction in which the film is formed, and is also referred to as the film formation direction or longitudinal direction. The TD direction of the film refers to the direction perpendicular to the MD direction of the film within the film plane, and is also referred to as the width direction. The Young's modulus can be measured by heating the film at 130°C for 1 minute and then performing a tensile test of the film at a tensile speed of 300 mm / min, and the detailed measurement conditions will be described later.

[0042] If the film's MD direction is unknown, the MD direction shall be defined as the direction perpendicular to the film's principal orientation direction. Here, the principal orientation direction refers to the direction that shows the highest value when measuring the Young's modulus in each direction from 0° to 175°, with any direction being defined as 0°, at 5° intervals relative to that arbitrary direction within the film plane. When the Young's modulus in the film's MD direction is 100 MPa or higher, for example, when used as a support film, the film's elongation is suppressed when a coating containing a resin composition is applied and solidified in a high-temperature process, and the resulting wrinkle formation is also reduced.

[0043] To achieve a Young's modulus of 100 MPa or more and 200 MPa or less in the MD direction of the film at 130°C, a method can be used in which the raw material composition of the film is within the range described below, and the film formation conditions are within the range described below. In particular, it is effective to use raw materials with a high degree of crystallinity, increase the preheating temperature during longitudinal / transverse stretching, and perform high-magnification stretching at low temperatures and uniformly.

[0044] From the viewpoint of improving heat resistance, the film of the present invention preferably has a melting peak at 160°C or higher when heated from 30°C to 260°C using a differential scanning calorimeter (DSC), more preferably at 165°C or higher, and even more preferably at 168°C or higher. A higher melting peak temperature is preferable, and there is no particular upper limit, but the upper limit is substantially 220°C. Here, "having a melting peak at 160°C or higher" includes not only the case where there is one melting peak and that melting peak is 160°C or higher, but also the case where there are multiple melting peaks and at least one of them is in the range of 160°C or higher.

[0045] When the melting peak temperature is 160°C or higher, for example, when used as a support film, film breakage and deterioration of flatness can be reduced when the coating containing the resin composition is applied and then solidified in a high-temperature process. To make the melting peak temperature 160°C or higher, the raw material composition of the film can be set within the range described later, and the film-forming conditions can be set within the range described later. In particular, using a high-melting-point resin in the inner layer of the film to improve the heat resistance of the inner layer is effective.

[0046] From the viewpoint of transparency, the film of the present invention preferably has an internal haze (hereinafter sometimes simply referred to as haze) of 0.01% or more and 1.5% or less after heating at 130°C for 10 minutes. From the above viewpoint, the haze after heating at 130°C for 10 minutes is more preferably 1.0% or less, and even more preferably 0.7% or less. The lower the haze after heating at 130°C for 10 minutes, the better, and there are no particular limitations, but from the viewpoint of feasibility, it is 0.01%. The haze can be measured with a known haze meter, and the detailed measurement conditions are shown in the examples.

[0047] The haze after heating at 130°C for 10 minutes is 1.5% or less. For example, when used as a support film, the transparency of the support film is maintained even after passing through the high-temperature transport process described above, reducing defects when inspected with a defect inspection machine while bonded to an adherend. The film of the present invention may contain various additives such as antioxidants, and such films are particularly susceptible to loss of transparency when subjected to high temperatures, such as 130°C or higher, as the additives such as antioxidants bleed out to the film surface. Therefore, the advantage of keeping the haze within the above range is particularly significant for such films.

[0048] To achieve a haze of 0.01% to 1.5% after heating at 130°C for 10 minutes, for example, a method can be used in which the raw material composition of the film is within the range described below, and the film-forming conditions are within the range described below. In particular, it is effective to include branched polypropylene resin to reduce the size of spherulites formed during casting, to lower the extrusion temperature and the temperature of the casting drum to increase cooling during casting, and to increase the preheating temperature during longitudinal / transverse stretching and to perform stretching at a low temperature to achieve uniform stretching. It is also effective to use raw materials with high stereoregularity and low cold xylene soluble portion (CXS) to increase crystallinity, and to perform heat treatment and relaxation after longitudinal and transverse stretching.

[0049] In the present invention, the surface free energy of the A-surface of the film is preferably 15 mN / m or more and 35 mN / m or less, from the viewpoint of facilitating the peeling of the resin composition film formed on the surface of the A-layer when the film is used as a support film. From the above viewpoint, the surface free energy of the A-surface is more preferably 32 mN / m or less, and even more preferably 29 mN / m or less. A lower surface free energy is preferable as it results in better release properties, but from the viewpoint of feasibility, 15 mN / m is the lower limit. By having a surface free energy of 35 mN / m or less, for example, when used as a support film, when a coating agent containing the resin composition is applied to the A-surface, solidified, and then peeled off to obtain a resin composition film, the peeling of the resin composition film becomes smoother, and the occurrence of film breakage and peeling marks during peeling is reduced. The surface free energy can be measured using four types of liquids as measuring liquids: water, ethylene glycol, formamide, and methylene iodide, with a known contact angle meter. The detailed measurement conditions are shown in the examples.

[0050] To set the surface free energy of surface A to 15 mN / m or more and 35 mN / m or less, for example, a method can be used in which the raw material composition of the film is within the range described later, and the film-forming conditions are within the range described later. In particular, it is effective to make the main component of the film surface layer corresponding to surface A (the film itself in the case of a single-layer structure, the same applies hereinafter) a polyolefin resin, or to provide a release coating layer on surface A, but from the viewpoint of component migration to the dendritic composition film and cost, it is more preferable to make the main component of the film surface layer corresponding to surface A a polyolefin resin.

[0051] The thickness of the film of the present invention is not particularly limited and can be adjusted as appropriate depending on the application, but is preferably 0.5 μm to 100 μm from the viewpoint of handling. When used as a release film, the upper limit of the thickness is more preferably 60 μm or less, even more preferably 50 μm or less, and most preferably 40 μm or less. The lower limit is more preferably 4 μm or more, even more preferably 8 μm or more, and most preferably 11 μm or more. The thickness can be adjusted by the screw rotation speed of the extruder, the width of the unstretched sheet, the film formation speed, the stretching ratio, etc., within a range that does not degrade other physical properties.

[0052] Next, the raw materials for the film of the present invention will be described, but the invention is not necessarily limited thereto.

[0053] The components constituting the film of the present invention are not particularly limited, but it is preferable that the main component is a thermoplastic resin. Examples of thermoplastic resins include, in addition to the polypropylene resin described later, polyolefin resins such as polystyrene (PS) resin, styrene-based elastomer resin, polymethylpentene (PMP) resin, cyclic olefin (COP) resin, and cyclic olefin copolymer (COC) resin; polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, and polyethylene narephthalate (PEN) resin; polysulfone (PSU) resin, polyethersulfone (PES) resin, and poly Polysulfone resins such as phenylsulfone (PPSU) resin, polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, polyphenylene sulfide sulfone resin, polyphenylene sulfide ketone sulfone resin, and other polyarylene sulfide resins, polyether ketone (PEK) resin, polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyether ether ketone ketone (PEEKK) resin, polyether ketone ether ketone ketone (PEKEKK) resin, and other polyaryl ether ketone resins, polytetrafluoroethylene (PTFE) resin (also called tetrafluoroethylene resin), polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin (also called tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) resin (also called tetrafluoroethylene-hexafluoropropylene copolymer resin), and tetrafluoroethylene-ethylene copolymer (ETFE) resin. Fluorine resins such as tetrafluoroethylene-ethylene copolymer resin, polychlorotrifluoroethylene (PCTFE) resin (also known as trifluoroethylene chloride resin), polyvinylidene fluoride (PVDE) resin (also known as vinylidene fluoride resin), vinylidene fluoride-tetrafluoroethylene-hexafluoropyrene copolymer resin, polyacetal resin, liquid crystal polymer (LCP) resin, polycarbonate (PC) resin, polyarylate (PAR) resin, acrylic resin, polymethyl methacrylate (PMMA),Examples of raw materials include polyurethane resin (PU), polyurethane acrylate resin, cellulose, cellulose derivatives (e.g., acetylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, etc.), petroleum resin, terpene resin, terpene phenol resin, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, low-crystalline or amorphous ethylene-α-olefin copolymer, ethylene-propylene-diene polymer, crystalline polypropylene, polypropylene, propylene-ethylene copolymer (random copolymer and / or block copolymer), propylene-α-olefin copolymer, propylene-ethylene-α-olefin copolymer, polybutene, 4-methyl-1-pentene-α-olefin copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-n-butyl (meth)acrylate copolymer, ethylene-vinyl acetate copolymer, etc. Modified forms, derivatives, and copolymers with other compounds of these raw materials can also be used. Furthermore, these raw materials may be used individually or in mixtures of two or more types. From the viewpoint of adjusting Ssk to 0 or less, it is preferable to use polyolefin resins or polyester resins that are easily biaxially stretched, and it is preferable to include at least one set of mutually immiscible components so as to create a microphase separation structure with an average domain diameter of 5 μm or less before stretching.

[0054] Furthermore, the film of the present invention may also contain various additives, such as weathering agents, transparency agents, crystal nucleating agents, antioxidants, heat stabilizers, lubricants, antistatic agents, antiblocking agents, fillers, viscosity modifiers, color inhibitors, leveling agents, surfactants, and mold release agents, to the extent that they do not impair the objectives of the present invention.

[0055] In the present invention, from the viewpoint of release properties and cost, it is preferable that the surface layer having side A of the film is mainly composed of an olefin resin. In order to improve release properties, PET films and the like are sometimes coated with a release resin such as silicone resin, but when the film is bonded to and peeled off the substrate, the resin components such as silicone resin may migrate to the substrate and cause contamination. On the other hand, although olefin resins have relatively low release properties, they migrate to the substrate very little, so they are preferably used for the surface layer having side A. In the present invention, "surface layer having side A" refers to the outermost layer on the side A if the film has a laminated structure, and the film itself if the film has a single-layer structure. "The surface layer having side A is mainly composed of an olefin resin" means that the proportion of olefin resin in the total components constituting the surface layer having side A is greater than 50% by mass and 100% by mass or less (hereinafter, "main component" can be interpreted similarly). Furthermore, if the film has a laminated structure and both sides are A-sides, then if at least one of the surface layers having A-sides satisfies the above requirements, it can be considered that "the surface layer having A-sides is mainly composed of olefin resin." The content of olefin resin in the surface layer having A-sides is more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, even more preferably 96% by mass or more and 100% by mass or less, particularly preferably 97% by mass or more and 100% by mass or less, and most preferably 98% by mass or more and 100% by mass or less.

[0056] Here, an olefin resin refers to a resin in which, when the total constituent units of the resin are set to 100 mol%, olefin units are present in amounts exceeding 50 mol% but not exceeding 100 mol%. Specific examples of olefin resins include polyethylene, polypropylene, polybutene, polymethylpentene, and copolymers thereof. If multiple types of olefin resins are present, the olefin resin content shall be calculated by summing all olefin resins. That is, in addition to cases where one type of olefin resin is present in amounts exceeding 50% by mass, even if individual olefin resins are less than 50% by mass, if the sum of all olefin resins exceeds 50% by mass, the resin can be considered to "mainly composed of olefin resins."

[0057] The film of the present invention preferably has an olefin resin as its main component, not only in the surface layer having side A, but also in the film as a whole, from the viewpoint of release properties, flexibility, and cost. The amount of olefin resin in the total components constituting the film is more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, even more preferably 96% by mass or more and 100% by mass or less, particularly preferably 97% by mass or more and 100% by mass or less, and most preferably 98% by mass or more and 100% by mass or less. Specific examples of olefin resins include polyethylene resin, polypropylene resin, polybutene resin, polymethylpentene resin, and copolymers thereof.

[0058] From the viewpoint of transparency and heat resistance, the film of the present invention preferably contains 95% by mass or more and 100% by mass or less of polypropylene resin in the resin constituting the film. From the above viewpoint, it is more preferably 96% by mass or more, even more preferably 97% by mass or more, and particularly preferably 98% by mass or more. Here, polypropylene resin refers to a resin in which, when the total constituent units constituting the resin are set to 100 mol%, propylene units are contained in amounts exceeding 50 mol% and not exceeding 100 mol%.

[0059] In the film of the present invention, the surface layer having surface A is mainly composed of polypropylene resin, and more preferably the polyethylene resin content is 3% by mass or less of the total layer. From the viewpoint of film quality, the polyethylene resin content in the surface layer having surface A is more preferably 2% by mass or less, even more preferably 1% by mass or less, and most preferably 0.5% by mass or less. Matte rough polypropylene films are often formed by blending polypropylene resin and polyethylene resin to create a rough surface. However, this method may result in an increase in fish eyes caused by polyethylene resin, an increase in foreign matter due to abrasion of the film surface, and other deteriorations in quality. Therefore, it is preferable to keep the polyethylene resin content in the surface layer having surface A within the above range.

[0060] From the viewpoint of suppressing the formation of coarse protrusions on the surface of surface A and forming a recessed structure of a predetermined depth, the film of the present invention preferably contains at least two or more resins from among polypropylene resin, branched polypropylene resin, low-crystallinity polyolefin resin, polymethylpentene resin, and rubber domain-containing resin.

[0061] The polypropylene resin (hereinafter sometimes referred to as polypropylene resin A) in the film of the present invention preferably has a melting point of 155°C or higher, more preferably 160°C or higher, even more preferably 163°C or higher, and most preferably 165°C or higher. A melting point of 155°C or higher for the polypropylene resin increases the heat resistance when it is made into a film. Therefore, for example, when used as a release film, when the film goes through a heat-applied process after being bonded to the adherend, the softening of the film and the accompanying elongation in the tensile direction are reduced, thereby suppressing deformation of the adherend.

[0062] A linear polypropylene resin is preferred as the polypropylene resin A.

[0063] Furthermore, the polypropylene resin A more preferably has a melt flow rate (MFR) of 1 to 10 g / 10 min, more preferably 1 to 8 g / 10 min, and particularly preferably 2 to 5 g / 10 min, at 230°C and under a load of 21.18 N. Using such a polypropylene resin improves film-forming properties and film strength. In order to achieve a melt flow rate (MFR) of 1 to 10 g / 10 min or the above preferred values, methods such as adjusting the hydrogen gas concentration during polymerization, selecting catalysts and / or co-catalysts, and selecting compositions as appropriate are preferably employed.

[0064] Polypropylene resin A may contain copolymer components (copolymer units) of other unsaturated hydrocarbons, to the extent that it does not impair the objectives of the present invention. Examples of such copolymer components include ethylene, 1-butene, 1-pentene, 3-methylpentene-1, 3-methylbutene-1, 1-hexene, 4-methylpentene-1, 5-ethylhexene-1, 1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, and 5-methyl-2-norbornene. The copolymerization amount is 1 mol% or less from the viewpoint of dimensional stability. Furthermore, polypropylene resin A may be blended with resins containing propylene and the above copolymer components, to the extent that it does not impair the effects of the present invention.

[0065] The branched-chain polypropylene resin in the film of the present invention (hereinafter sometimes referred to as branched-chain polypropylene resin B) is known to act as a nucleating agent for linear polypropylene resins, and by refining the spherulites of the cast film after melt extrusion, the formation of coarse protrusions in the stretched film can be suppressed.

[0066] When branched-chain polypropylene resin B is included, the upper limit of the branched-chain polypropylene resin B content in the layer is more preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 30% by mass or less, and most preferably 25% by mass or less, when the total components of the layer are considered as 100% by mass. Furthermore, the lower limit of the branched-chain polypropylene resin B content is more preferably 0.1% by mass or more, even more preferably 1% by mass or more, even more preferably 4% by mass or more, and most preferably 10% by mass or more.

[0067] From the viewpoint of extrusion stability, the MFR of branched polypropylene resin B, measured at 230°C and under a load of 21.18N, is preferably 0.5 g / 10 min to 9 g / 10 min. The lower limit of the MFR of branched polypropylene resin B measured under the same conditions is more preferably in the range of 2 g / 10 min, and even more preferably 6 g / 10 min or higher. In order to achieve an MFR of branched polypropylene resin B of 0.5 g / 10 min to 9 g / 10 min or the above preferred values, methods such as adjusting the hydrogen gas concentration during polymerization, selecting catalysts and / or co-catalysts, and selecting their compositions as appropriate are preferably employed.

[0068] From the viewpoint of stretch uniformity, the melt tension of branched polypropylene resin B is preferably 3 gf or more and 40 gf or less. The lower limit of the melt tension is more preferably 4 gf, and even more preferably 6 gf. The upper limit is more preferably 30 gf, and even more preferably 25 gf. In order to achieve the above values ​​for melt tension, methods such as controlling the average molecular weight, molecular weight distribution, and degree of branching in the polypropylene resin are employed. In particular, when long-chain branching is present, the melt tension can be dramatically increased, and by adjusting the molecular chains of the long-chain branching and the degree of branching, it can be adjusted to a desirable value.

[0069] While several types of branched-chain polypropylene resin B are commercially available, such as Ziegler-Natta catalyst systems and metallocene catalyst systems, metallocene catalyst systems are more preferable due to their lower levels of low and high molecular weight components and narrower molecular weight distribution.

[0070] The film of the present invention contains a low-crystallinity polyolefin resin (hereinafter referred to as low-crystallinity polyolefin resin C), which reduces the crystallinity of the cast film after melt extrusion, and as a result, suppresses the formation of coarse protrusions on the film after stretching. Compared to polypropylene resin A, low-crystallinity polyolefin resin C preferably has lower stereoregularity of the polymer molecular structure and / or lower crystallinity. Means for reducing crystallinity include copolymerization with a comonomer, for example. Low-crystallinity polyolefin resins may include resins without a melting point, but in the case of resins with a melting point, the melting point of low-crystallinity polyolefin resin C is preferably lower than that of polypropylene resin A, more preferably 50°C to 135°C, more preferably 60°C to 130°C, even more preferably 60°C to 120°C, and most preferably 60°C to 100°C. It is also preferable to have a laminated film in which a low-crystallinity polyolefin resin with a melting point of 50°C to 135°C or within the above preferred range is contained in at least one surface layer.

[0071] When transporting the preheating / stretching rolls, the melting point of the low-crystallinity polyolefin resin C is preferably 50°C or higher, from the viewpoint of preventing melting of the film surface and adhesion to the rolls. Furthermore, from the viewpoint of partially melting and roughening the film surface during stretching, the melting point of the low-crystallinity polyolefin resin C is preferably 135°C or lower. When the film has a laminated structure and at least one surface layer contains low-crystallinity polyolefin resin C, the upper limit of the low-crystallinity polyolefin resin C content in the surface layer containing low-crystallinity polyolefin resin C is more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 40% by mass or less, and most preferably 25% by mass or less, when the total components of the layer are taken as 100% by mass. Furthermore, the lower limit of the low-crystallinity polyolefin resin C content is more preferably 5% by mass or more, even more preferably 15% by mass or more, and most preferably 20% by mass or more. As the low-crystallinity polyolefin resin C, a low-crystallinity polypropylene resin compatible with polypropylene resin A is preferred, and examples include copolymers of propylene and α-olefins, and polypropylene resins with low stereoregularity. For example, commercially available products such as "Wintec" (registered trademark) manufactured by Nippon Polypropylene Co., Ltd., which is a polypropylene random copolymer, and "Elmodu" (registered trademark) manufactured by Idemitsu Kosan Co., Ltd., which is a low-stereoregularity polypropylene resin, can be appropriately selected and used.

[0072] The film of the present invention contains a rubber domain-forming resin (hereinafter sometimes referred to as rubber domain-forming resin D). ru. Here, the term "rubber domain-forming resin" refers to a resin that, when blended with polypropylene resin A, can form rubber domains within the film. Examples include resins that contain rubber domains, such as polypropylene block copolymers, and thermoplastic elastomers that do not completely miscible with polypropylene resin A but form rubber domains within the matrix of polypropylene resin A. In this configuration, the rubber domains are stretched more than the matrix resin during longitudinal stretching, thus forming a recessed structure on the film surface. The rubber domain-forming resin D is a resin that can form rubber domains within the film. olefin-basedIt is at least one of an elastomer and a polypropylene block copolymer. 。 Because of its high affinity with polypropylene resin A, Olefin-based Elastomers are preferred. In particular, thermoplastic elastomers are elastomers that soften and become fluid when heated, and return to a rubbery state when cooled. The preferred upper limit of the Vicat softening temperature for rubber domain-forming resin D is preferably 130°C or lower, more preferably 122°C or lower, and even more preferably 110°C or lower. The preferred lower limit of the Vicat softening temperature is preferably 50°C or higher, more preferably 65°C or higher, even more preferably 80°C or higher, and most preferably 90°C or higher.

[0073] When rubber domain-forming resin D is included, the upper limit of the rubber domain-forming resin D content in the layer containing the rubber domain-forming resin is more preferably 35% by mass or less, even more preferably 25% by mass or less, even more preferably 17% by mass or less, and most preferably 12% by mass or less, when the total components of the layer are considered as 100% by mass. The lower limit of the rubber domain-forming resin D content is more preferably 1% by mass or more, even more preferably 4% by mass or more, even more preferably 6% by mass or more, and most preferably 8% by mass or more.

[0074] The polypropylene resin A, branched polypropylene resin B, low-crystallinity polyolefin resin C, and rubber domain-forming resin D used in the film of the present invention may also contain various additives, such as nucleating agents, antioxidants, heat stabilizers, lubricants, antistatic agents, antiblocking agents, fillers, viscosity modifiers, and anticoloring agents, as long as the objectives of the present invention are not impaired.

[0075] Among these, the selection of the type and amount of antioxidant is important from the viewpoint of antioxidant bleed-out. Specifically, such antioxidants should be sterically hindered phenolic types, and at least one of them should preferably be a high molecular weight type with a molecular weight of 500 or more. Various specific examples can be given, but for example, it is preferable to use 2,6-di-t-butyl-p-cresol (BHT: molecular weight 220.4) in combination with 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene (e.g., BASF's "Irganox"® 1330: molecular weight 775.2) or tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (e.g., BASF's "Irganox"® 1010: molecular weight 1,177.7).

[0076] The polypropylene resin A used in the film of the present invention may contain a nucleating agent, to the extent that it does not contradict the objectives of the present invention. Specific examples include α-nucleating agents (such as dibenzylidene sorbitol and sodium benzoate), β-nucleating agents (such as potassium 1,2-hydroxystearate, magnesium benzoate, amide compounds such as N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide, and quinacridone compounds). However, excessive addition of the above-mentioned nucleating agents may cause a decrease in stretchability and a reduction in transparency and strength due to void formation, so the amount added is usually 0.5 parts by mass or less, preferably 0.1 parts by mass or less, and more preferably 0.05 parts by mass or less, when the polypropylene resin A is 100 parts by mass.

[0077] In the film of the present invention, it is preferable that the surface layer having side A (or the film itself in the case of a single-layer structure) does not contain organic or inorganic particles. Because polypropylene resin has low affinity for organic and inorganic particles, particles may fall off and contaminate the process or product. In addition, high-hardness particles may form coarse protrusions that transfer unevenness to the resin layer of optical components, which can be an obstacle when used as a protective or support film for products requiring high quality, such as display components.

[0078] The film of the present invention is made using the above-mentioned resin and then biaxially stretched. ru The biaxial stretching can be achieved by any of the following methods: simultaneous inflation biaxial stretching, simultaneous stentor biaxial stretching, or sequential stentor biaxial stretching. Among these, sequential stentor biaxial stretching is preferred because it allows for control over film formation stability, thickness uniformity, and high rigidity and dimensional stability of the film.

[0079] Next, one aspect of the film manufacturing method of the present invention will be described, using some aspects as examples, but the film manufacturing method of the present invention is not necessarily limited thereto.

[0080] First, 50 parts by mass of polypropylene resin A, 20 parts by mass of branched polypropylene resin B, 20 parts by mass of low-crystallinity polyolefin resin C, and 10 parts by mass of rubber domain-forming resin D were supplied from a weighing hopper to a twin-screw extruder, and melt-kneaded at 260°C, and extruded from the die in strand form. The extruded resin composition was cooled and solidified in a 25°C water bath, cut into chips, and a resin composition for the surface layer (I) was obtained. The resin composition for the surface layer (I) was supplied to a single-screw extruder, and A1 and B1 were dry-blended in a 95:5 (mass ratio) ratio and supplied to a single-screw melt extruder for the inner layer (II), and melt-extruded at 200-280°C, more preferably 220-280°C, and even more preferably 240-270°C. Then, after removing foreign matter and modified polymers using a filter installed in the middle of the polymer tube, the material is laminated in a multi-manifold type composite T-die to form a 2-type 3-layer structure of I-layer / II-layer / I-layer, and extruded onto a casting drum to obtain a laminated unstretched sheet with an I-layer / II-layer / I-layer structure. In this case, the laminate thickness ratio is preferably in the range of 1 / 8 / 1 to 1 / 60 / 1.

[0081] Furthermore, the casting drum preferably has a surface temperature of 10 to 45°C, more preferably 15 to 35°C, and even more preferably 15 to 25°C. A two-layer laminated structure of layer I / layer II is also acceptable, in which case the layer I side is in close contact with the casting drum. Any of the following methods can be used for contact with the casting drum: electrostatic application, contact using the surface tension of water, air knife method, press roll method, or underwater casting method. However, the air knife method is preferred because it provides good flatness and allows for control of surface roughness. The air temperature of the air knife is preferably 10 to 30°C, and the blown air velocity is preferably 130 m / s to 150 m / s. It is also preferable to appropriately adjust the position of the air knife so that air flows downstream of the film formation to prevent vibration of the film.

[0082] The obtained unstretched sheet is introduced into the longitudinal stretching process. In the longitudinal stretching process, a two-stage stretching is performed, in which initial longitudinal stretching is carried out at a low temperature and low magnification, followed by longitudinal stretching at a high temperature and high magnification, thereby efficiently forming a recessed structure on the surface of the I layer. First, for the initial longitudinal stretching, by preheating at a temperature higher than the softening temperature of the rubber domain-forming resin D and stretching at a low magnification, the rubber domains can be effectively stretched to a greater extent than the matrix resin, and a recessed structure can be formed on the film surface. For this initial longitudinal stretching, it is preferable to preheat the unstretched sheet by bringing it into contact with multiple metal rolls maintained at 80°C to 130°C, preferably 90°C to 120°C, and more preferably 100°C to 110°C, and stretching it in the longitudinal direction at a magnification of 1.1 to 3.0 times, preferably 1.3 to 2.5 times, between rolls with a difference in peripheral speed.

[0083] Subsequently, obtaining a longitudinally uniaxially oriented film by longitudinally stretching at a high magnification at a temperature higher than the initial longitudinal stretching temperature is preferable in order to stabilize transverse stretching and reduce haze. More specifically, it is preferable to preheat the sheet by contacting it with a metal roll that is kept at a temperature higher than the preheating temperature for initial longitudinal stretching, and between 110°C and 150°C, preferably between 115°C and 140°C, and even more preferably between 120°C and 140°C, and then stretch the sheet between rolls with a difference in peripheral speed. The total stretching magnification for the two-stage stretching is preferably 3.5 to 7 times, more preferably 4.5 to 5.5 times, and even more preferably 4.5 to 5.0 times. If the total stretching magnification is less than 3 times, the orientation of the resulting film may be weak, and the strength may decrease.

[0084] Next, the longitudinally uniaxially oriented film is guided to a tenter, the ends of the film are held with clips, and after preheating, it is transversely stretched to 7 to 13 times its original width. It is important not to disturb the recessed structure formed on the film surface by preheating the longitudinally uniaxially oriented film at a low temperature and then transversely stretching it. For this reason, the preheating and stretching temperatures are 120°C to 175°C, preferably 120°C to 165°C, and more preferably 140°C to 160°C. Furthermore, it is particularly preferable that the stretching temperature is lower than the preheating temperature, preferably 3°C or more lower, more preferably 5°C or more lower, and even more preferably 10°C or more lower.

[0085] In the subsequent heat treatment and relaxation process, the film is held taut in the width direction with clips and relaxed at a temperature of 140°C to 175°C, preferably 140°C to less than 170°C, more preferably 150°C to less than 170°C, and even more preferably 160°C to less than 170°C, while being heat-set. After that, the film is guided to the outside of the tenter through a cooling process at 80°C to 100°C while still held taut in the width direction with clips, the clips at both ends in the width direction of the film are released, the film edges are slit in the winder process, and the film product roll is wound up. By performing heat setting under the above conditions, residual stress in the film can be relieved and the thermal shrinkage rate can be reduced.

[0086] The film obtained as described above can be used in a variety of industrial applications, such as packaging films, surface protection films, support films, sanitary products, agricultural products, building materials, medical products, and capacitor films. In particular, it is preferable for process film applications because it does not have coarse protrusions, has a predetermined recessed structure, and has excellent release properties, rigidity, heat resistance, and slipperiness. Here, process film includes protective films that protect the film during transport, support films used as supports when manufacturing resin composition films, and cover films that cover the side of the resin composition film that is not used as a support film when forming the resin composition film on the support film.

[0087] Next, the laminate of the present invention and the method for manufacturing the resin composition film of the present invention will be described. The laminate of the present invention has a resin composition layer on surface A of the film of the present invention. The film of the present invention does not have coarse protrusions, has a predetermined recessed structure, and has excellent release properties, rigidity, and heat resistance. By forming a laminate on surface A of the film, it is possible to easily manufacture a resin composition film obtained by peeling off the resin composition layer. Furthermore, the method for manufacturing the resin composition film of the present invention comprises at least the following steps 1 to 3 in this order. Step 1: A step of applying a coating agent containing the resin composition to surface A of the film according to any one of claims 1 to 10. Step 2: A step of solidifying the coating agent containing the resin composition to form a resin composition layer and forming a laminate. Step 3: A step of peeling off the resin composition layer from the laminate to obtain a resin composition film.

[0088] The following describes an example of a method for producing a resin composition film of the present invention, using a method for producing a polyurethane acrylate film as an example, but the invention is not necessarily limited to this.

[0089] The film obtained by the method described above is wound into a roll and introduced into a bar coater. A coating agent made of a resin composition prepared by mixing 50 parts by mass of commercially available urethane acrylate (viscosity of 600,000 mPa·s at 25°C, weight-average molecular weight Mw 1,600, glass transition temperature of 10°C), 50 parts by mass of commercially available methyl ethyl ketone, and 3 parts by mass of commercially available 1-hydroxycyclohexyl phenyl ketone is applied to side A of the film to a thickness of 1 μm to 100 μm. This is then introduced into a hot air dryer and heated at 50°C to 150°C to remove the solvent. Subsequently, ultraviolet light is irradiated using a UV lamp under a nitrogen atmosphere to cure the coating agent on the film, obtaining a laminate consisting of a resin composition layer made of polyurethane acrylate and the film. The laminate is wound up to obtain a roll with the laminate having the resin composition layer on side A of the film wound up. The laminate is unwound from this laminate roll and the resin composition layer is peeled off from the film to obtain a resin composition film made of polyurethane acrylate.

[0090] Other examples of resin composition films include dendritic composition films made of cellulose acetate propionate. A coating agent is prepared by mixing 100 parts by mass of commercially available cellulose acetate propionate (acetyl group substitution degree + propionyl group substitution degree = 2.5, weight-average molecular weight = 180,000, Mw / Mn = 3.0), 8 parts by mass of triphenyl phosphate, 2 parts by mass of ethyl phthalyl ethyl glycolate, 360 parts by mass of methylene chloride, 60 parts by mass of ethanol, 0.5 parts by mass of Chinuvin 109 (manufactured by Ciba Japan Co., Ltd.), and 0.5 parts by mass of Chinuvin 171 (manufactured by Ciba Japan Co., Ltd.), and applying this coating agent to side A of the film to a film thickness of 1 μm to 100 μm. This is introduced into a hot air dryer and heated at 10°C to 50°C to remove the solvent and cure the coating on the film, obtaining a laminate consisting of a resin composition layer made of cellulose acetate propionate and a film. The laminate is wound up to obtain a roll in which the laminate having the resin composition layer on side A of the film is wound up. The laminate is unwound from this laminate roll and the resin composition layer is peeled off from the film to obtain a resin composition film made of cellulose acetate propionate.

[0091] Another example is a resin composition film made of polyetherimide. A coating agent is prepared by mixing 15 parts by mass of commercially available polyetherimide resin (SABIC Corporation, trade name "ULTEM" (registered trademark) 1010, Vicat softening point temperature 215°C) with 85 parts by mass of N-methyl-2-pyrrolidone, and applying the mixture to side A of a film to a thickness of 1 μm to 100 μm. This is then introduced into a hot air dryer and heated at 50°C to 150°C to remove the solvent and cure the coating agent on the film, obtaining a laminate consisting of a resin composition layer made of polyetherimide and a film. The laminate is wound up to obtain a roll in which the laminate having the resin composition layer on side A of the film is wound up. The laminate is unwound from this laminate roll and the resin composition layer is peeled off from the film to obtain a resin composition film made of polyetherimide. [Examples]

[0092] The present invention will be described in detail below with reference to examples. The evaluation methods for each property and the resins used in the production of the film are as follows.

[0093] (Evaluation methods for each characteristic) (1) Film thickness The thickness was measured using a micro-thickness gauge (manufactured by Anritsu Corporation). Specifically, a 10 cm square sample was taken from the film, and the thickness of five arbitrarily selected points was measured. The average value was then calculated and defined as the film thickness.

[0094] (2) Skewness Ssk, load area ratio Smr2, protruding peak height Spk, maximum valley depth Sv Each parameter was measured and calculated in accordance with ISO 25178 (2012). However, the measurements were performed using a scanning white light interference microscope "VS1540" (manufactured by Hitachi High-Tech Science Corporation; measurement conditions and equipment configuration are described later). Furthermore, the captured image was interpolated (fully interpolated) using the included analysis software, and after surface correction using a polynomial fourth-order approximation, the measured electro-magnetic surface was obtained by processing with a median filter (3 x 3 pixels). The S-filter Nesting Index was set to 0.445. Measurements were performed on both sides of a 5cm x 5cm square piece of film. The intersection of the diagonals was designated as the first measurement point (point 1). Points 2, 3, 4, and 5 were designated clockwise, 1 cm away from each of the four corners from the starting point. Point 6 was the midpoint of the line segment connecting points 2 and 3, point 7 was the midpoint of the line segment connecting points 3 and 4, point 8 was the midpoint of the line segment connecting points 4 and 5, and point 9 was the midpoint of the line segment connecting points 5 and 2. A total of nine measurement points were determined from points 1 to 9, and measurements were taken at each point. From the measurement results, Ssk, Smr2, Spk, and Sv were determined for each measurement position according to the procedure described above. For each parameter, the average of the five values ​​obtained (excluding the 1st and 2nd largest values ​​and the 8th and 9th largest values) was adopted as the Ssk, Smr2, Spk, and Sv of the film. Table 2 shows the Ssk, Smr2, Spk, and Sv values ​​for side A of the film. If both sides of the film are A-sides, the value for the side with the lower Spk is listed. For films without an A-side, the value for the side with the lower Spk is listed. Furthermore, for films without an A-side and with equal Spk on both sides, the value for the side with the lower Ssk is listed.

[0095] <Measurement conditions and equipment configuration> Objective lens: 10x Telescope tube: 1x Zoom lens: 1x Wavelength filter: 530nm white Measurement mode: Wave Measurement software: VS-Measure 10.0.4.0 Analysis software: VS-Viewer 10.0.3.0 Measurement area: 561.1μm×561.5μm Pixel count: 1,024 x 1,024.

[0096] (3) Coefficient of dynamic friction between one surface and the other surface μd The film was cut to a width of 6.5 cm and a length of 12 cm, and measured using a slip tester manufactured by Toyo Seiki Kogyo Co., Ltd., in accordance with JIS K 7125 (1999), at 25°C and 65% RH. The measurement was performed with the direction perpendicular to the main orientation as the measurement direction, and different surfaces were overlapped. The same measurement was performed five times for each sample, and the average value obtained was calculated to determine the coefficient of dynamic friction (μd) of the sample.

[0097] (4) Young's modulus at 130°C The Young's modulus at 130°C was determined using an Orientec Co., Ltd. film strength and elongation measuring device (AMF / RTA-100). The film, still in its chuck, was placed in an oven heated to 130°C for 1 minute, and then a tensile test was performed on the film at a tensile speed of 300 mm / min. The film was cut into rectangular pieces with dimensions of 25 cm in the measurement direction (perpendicular to the principal orientation axis) and 1 cm in the direction perpendicular to the measurement direction. The original length was 100 mm, and the length was stretched at a tensile speed of 300 mm / min, and measured according to the method specified in JIS Z 1702 (1994).

[0098] (5) Melting peak temperature A sample of film or 5 mg of raw material was placed in an aluminum pan and measured using a differential scanning calorimeter (RDC220, Seiko Electronics Industries, Ltd.). The temperature was increased from 20°C to 260°C at a rate of 10°C / min under a nitrogen atmosphere, held for 5 minutes, then cooled from 260°C to 20°C at a rate of 10°C / min, and then increased again from 20°C to 260°C at a rate of 10°C / min (second run). The temperature at the peak of the melting curve that appeared on the highest temperature side observed was defined as the melting peak temperature.

[0099] (6) Internal haze after heat treatment The film was cut to a width of 3.0 cm and a length of 6.0 cm, and the test piece was sandwiched between pieces of paper. After heating in an oven maintained at 130°C for 10 minutes with no load, the sample was removed, cooled to room temperature, and used as the sample. A haze meter (HGM-2DP) manufactured by Suga Test Instruments Co., Ltd. was used for measurement. The internal haze after heat treatment was determined from the measurement values ​​obtained when the sample was inserted into a quartz cell with an optical path length of 1 cm filled with tetralin.

[0100] (7) Evaluation of the slipperiness of a resin composition film obtained by coating a film, solidifying it, and peeling it off. A coating made from a resin composition prepared by mixing 50 parts by mass of commercially available urethane acrylate (viscosity 600,000 mPa·s at 25°C, weight-average molecular weight Mw 1,600, glass transition temperature 10°C), 50 parts by mass of commercially available methyl ethyl ketone, and 3 parts by mass of commercially available 1-hydroxycyclohexyl phenyl ketone was applied to side A of a 21cm x 30cm film to a thickness of 45μm. This was then introduced into a hot air dryer and heated at 80°C to remove the solvent. Subsequently, the coating on the film was cured by irradiation with ultraviolet light using a UV lamp under a nitrogen atmosphere, and the resin composition layer was peeled off to obtain a resin composition film made of polyurethane acrylate. If both sides of the film were side A, the coating was applied to the side with the lower Spk and the resin composition film was obtained by the same procedure. For films without a side A, the coating was applied to the side with the lower Spk and the resin composition film was obtained by the same procedure. Furthermore, for films that did not have an A-side and had equal Spk values ​​on both sides, the coating agent was applied to the side with the smaller Ssk value, and a resin composition film was obtained by the same procedure. This was repeated five times to obtain five resin composition films. Using a slip tester manufactured by Toyo Seiki Kogyo Co., Ltd., the dynamic friction coefficient μd was measured by the method described in (3) when the resin composition films were rubbed together in the longitudinal direction with the surfaces that had been in contact with each other, in accordance with JIS K 7125 (1999), at a load of 200g, 25℃, and 65%RH. The samples were rectangles with a width of 80mm and a length of 200mm, and five sets (10 sheets) were cut out. When cutting out the samples, one set was cut out from one resin composition film, and the area 2cm from the edge of the resin composition film was not used. Five measurements were taken, and the average value was adopted as the value of the dynamic friction coefficient μd of the resin composition film. Based on the value of the dynamic friction coefficient μd of the resin composition film, the slipperiness (effect of imparting slipperiness to the film) of the resin composition film was evaluated according to the following criteria. Excellent: μd is 0.50 or less. Good: μd is greater than 0.50 and less than or equal to 0.55. Acceptable: μd is greater than 0.55 and less than or equal to 0.60. Unacceptable: μd is greater than 0.60.

[0101] (8) Evaluation of the transparency of the resin composition film obtained by coating, solidifying, and peeling off a film. Two resin composition films were obtained by the method described in (7). The obtained resin composition films were sampled in a 100 mm wide, 100 mm long square. The side of the resin composition film that was in contact with the film was designated as the P side, and the other side as the Q side. The two films were stacked so that the P side and the Q side were in contact, and then sandwiched between two acrylic plates (100 mm wide, 100 mm long). A load of 3 kg was applied, and the film was left undisturbed for 24 hours in a 23°C atmosphere. After 24 hours, the Q side that was in contact with the P side was visually observed, and the smoothing effect on the process film was evaluated according to the following criteria. Excellent: Clean and in the same condition as before the load was applied. Good: Immediately after the load is released, slight irregularities are observed, but after 10 minutes, the irregularities disappear. Acceptable: Slight irregularities can still be observed 10 minutes after the load is released. Unacceptable: Strong unevenness is observed during transfer.

[0102] (9) Surface free energy Four types of liquids—water, ethylene glycol, formamide, and methylene iodide—were used as measurement solutions. The static contact angle of each liquid with respect to the A-side of film was determined using a CA-D contact angle meter manufactured by Kyowa Interface Science Co., Ltd. The static contact angle was measured 30 seconds after dropping each liquid onto the A-side of film. The obtained contact angles and the components of the surface tension of each liquid were substituted into the following equations, and the resulting system of equations was solved for γSd, γSp, and γSh. For films with A-sides on both sides, the side with the lower Spk value was evaluated. For films without an A-side, the side with the lower Spk value was evaluated. For films without an A-side and with equal Spk values ​​on both sides, the side with the lower Ssk value was evaluated.

[0103] (γSd·γLd) 1 / 2 +(γSp·γLp) 1 / 2 +(γSh·γLh) 1 / 2 =γL(1+COSθ) / 2 However, γS = γSd + γSp + γSh γL = γLd + γLp + γLh γS, γSd, γSp, and γSh represent the surface free energy, dispersion force component, polar force component, and hydrogen bonding component of the film surface, respectively, while γL, γLd, γLp, and γLh represent the surface free energy, dispersion force component, polar force component, and hydrogen bonding component of the measurement liquid used, respectively. Here, the surface tension of each liquid used was the value proposed by Panzer (J. Panzer, J. Colloid Interface Sci., 44, 142 (1973)).

[0104] (10) Vicat softening temperature Test samples were prepared by press-molding each raw material to a thickness of 3 mm, and the Vicat softening temperature of each raw material was evaluated in accordance with ASTM D1525 using a heat distortion tester (Yasuda Seiki Seisakusho Co., Ltd. "148-6 series").

[0105] (Resins, etc., used in the manufacture of film) A1: Polypropylene resin (manufactured by Prime Polymer Co., Ltd., MFR: 3.0g / 10 min, melting point: 164℃) A2: Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., MFR: 7.5g / 10 min, melting point: 163℃) A3: Polypropylene resin (manufactured by Prime Polymer Co., Ltd., MFR: 3.0g / 10 min, melting point 161℃) A4: Polypropylene resin (manufactured by Prime Polymer Co., Ltd., MFR: 4.0g / 10 min, melting point 166℃) B1: Branched polypropylene resin (WAYMAX® MFX6, manufactured by Nippon Polypropylene Co., Ltd., MFR: 3.0g / 10 mins) B2: Branched-chain polypropylene resin (WAYMAX® MFX3, manufactured by Nippon Polypropylene Co., Ltd., MFR: 8.0g / 10 mins) B3: Branched polypropylene resin (Borealis "Daploy" (registered trademark), WB140HMS, MFR: 2.1g / 10 min) C1: Random polypropylene resin (WFW4M, "WINTEC" (registered trademark), manufactured by Nippon Polypropylene Co., Ltd., MFR: 7.0g / 10 min, melting point 135℃) C2: Polypropylene resin (L-MODU, S901, manufactured by Idemitsu Kosan Co., Ltd., melting point 80℃) D1: Thermoplastic elastomer resin (WELNEX® RFX4V, manufactured by Nippon Polypropylene Co., Ltd., Vicat softening temperature: 100℃) D2: Block polypropylene resin (Sumitomo Chemical Co., Ltd. "Noblen" (registered trademark) AW564, Vicat softening temperature: 101℃) D3: Thermoplastic elastomer resin (WELNEX® RFX4VM, manufactured by Nippon Polypropylene Co., Ltd.; Vicat softening temperature: 115℃) D4: Thermoplastic elastomer resin (Toughmer® XM7070, manufactured by Mitsui Chemicals, Inc.; Vicat softening temperature: 67°C) Polyester A: A polyester resin with an intrinsic viscosity of 0.68 obtained by the following procedure. Procedure: Starting with 100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol, 0.09 parts by mass of magnesium acetate tetrahydrate was added as a catalyst to the reactor. The reaction was started at 150°C, and the reaction temperature was gradually increased with the distillation of methanol until it reached 230°C after 3 hours. After 4 hours, the transesterification reaction was substantially completed. To this reaction mixture, 0.04 parts by mass of ethyl acid phosphate was added, followed by 0.04 parts by mass of antimony trioxide, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually increased from 230°C to 280°C. Meanwhile, the pressure was gradually reduced from atmospheric pressure until it reached 0.3 mmHg. After the start of the reaction, the reaction was stopped when the intrinsic viscosity reached 0.68 by changing the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure. Polyester B: A polyester resin with an intrinsic viscosity of 0.67 obtained by the following procedure. Procedure: The same method as for producing polyester A was used, except that after adding 0.04 parts by mass of ethyl phosphate, 0.3 parts by mass of synthetic calcium carbonate particles dispersed in ethylene glycol with an average particle size of 0.7 μm and a particle size distribution of 1.70, and 0.04 parts by mass of antimony trioxide were added, and the polycondensation reaction was stopped when the intrinsic viscosity reached 0.66. Polyester C: A polyester resin with an intrinsic viscosity of 0.67 obtained by the following procedure. Procedure: The same method as for the production of polyester B was used, except that the added particles were amorphous silica particles with an average particle size of 1.4 μm and a particle size distribution value of 2.5, and the amount added was 0.1 parts.

[0106] (Example 1) A1 was supplied from a weighing hopper to a twin-screw extruder in the following quantities: 50 parts by mass of A1, 20 parts by mass of B1, 20 parts by mass of C1 (a low-crystallinity polyolefin resin), and 10 parts by mass of D1 (a rubber domain-forming resin). The mixture was melt-kneaded at 260°C and extruded from the die in strand form. The extruded resin composition was cooled and solidified in a 25°C water bath, cut into chips, and obtained the resin composition for the surface layer (I). The resin composition for the surface layer (I) was supplied to a single-screw extruder, and A1 and B1 were dry-blended in a 95:5 (mass ratio). This mixture was then supplied to a single-screw melt extruder for the inner layer (II), and melt-extruded at 260°C in each case. Next, foreign matter was removed from each molten resin composition using a 20 μm cut sintered filter. Then, the surface layer (I) / inner layer (II) / surface layer (I) were laminated in a thickness ratio of 1 / 24 / 1 using a feed block type composite T die, and the resulting material was extruded onto a casting drum with a surface temperature controlled to 20°C, where it was pressed tightly against the drum using an air knife. Subsequently, compressed air was injected onto the side of the sheet on the casting drum opposite the casting drum surface to cool it, obtaining an unstretched sheet. Next, the unstretched sheet was preheated to 90°C using ceramic rolls, and an initial stretch of 1.3 times in the longitudinal direction was performed between 90°C rolls with a difference in peripheral speed (this stretching in the longitudinal direction is sometimes called longitudinal stretching). Subsequently, the film after initial stretching was preheated to 140°C, and a second longitudinal stretching was performed at a magnification of 3.5 times. Next, the film, after longitudinal stretching, was gripped at both ends in the width direction with clips and introduced into a tenter-type stretcher. After preheating at 160°C for 3 seconds, it was stretched to 9.8 times its width in the width direction at 150°C, and then heat-treated at 165°C while allowing 10% relaxation in the width direction. After a cooling process at 100°C, the film was guided to the outside of the tenter, the clips at both ends in the width direction of the film were released, and the film was wound onto a core to obtain a biaxially oriented polypropylene film with a thickness of 12 μm. The physical properties and evaluation results of the obtained biaxially oriented polypropylene film are shown in Table 1.

[0107] [Table 1]

[0108] (Examples 2-4, 6-7, Comparative Examples 1, 2, 4, 6) Except for the composition of each layer, layer configuration, lamination ratio, and film formation conditions being as shown in Table 1, the same procedure as in Example 1 was followed to obtain films with the thicknesses shown in Table 1. The physical properties and evaluation results of the obtained films are also shown in Table 1. The film thickness was adjusted by adjusting the discharge amount during extrusion.

[0109] (Example 5) As raw materials, 65 parts by mass of the polypropylene raw material A1, 20 parts by mass of the low-crystallinity polyolefin raw material C1, and 15 parts by mass of the rubber domain-containing raw material D1 were dry-blended and supplied to a single-screw uniscrew melt extruder for single layers. Melt extrusion was performed at 260°C, and after removing foreign matter with a 20 μm cut sintered filter, the material was discharged onto a casting drum with a surface temperature controlled to 20°C and pressed tightly against the casting drum with an air knife. Subsequently, compressed air was injected onto the uncooled drum surface of the sheet on the casting drum to cool it and obtain an unstretched sheet. Next, the sheet was preheated to 125°C with ceramic rolls, and an initial stretch of 1.2 times in the longitudinal direction of the film was performed between rolls at 125°C with a difference in peripheral speed. Subsequently, it was preheated to 138°C, and a second stage of longitudinal stretching was performed at 3.4 times. Next, the film was introduced into a tenter stretcher with its ends held by clips. After preheating at 168°C for 3 seconds, it was stretched to 7.5 times its original length at 163°C, and then heat-treated at 173°C while allowing 16% slack in the width direction. After a cooling process at 100°C, the film was guided to the outside of the tenter, the clips at the film ends were released, and the film was wound onto a core to obtain a single-layer film with a thickness of 22 μm. The physical properties and evaluation results of the obtained film are shown in Table 1.

[0110] (Comparative Example 3) Coating solution X was prepared by dissolving 5.65 parts by mass of acrylic resin having polymerizable unsaturated groups in its side chains, 1.2 parts by mass of cellulose acetate propionate, 4 parts by mass of a polyfunctional acrylic UV-curable compound, 2.77 parts by mass of an acrylic UV-curable compound, and 0.53 parts by mass of a photoinitiator in a mixed solvent of 25 parts by mass of methyl ethyl ketone (MEK) and 12.15 parts by mass of 1-butanol. Then, coating solution X was coated onto one side of a biaxially oriented PET film that had been treated for easy adhesion using the Meyer bar coating method, and dried at 95°C for 2 minutes to form a coating layer with a thickness of 7 μm. Furthermore, ultraviolet light from a high-pressure mercury lamp (manufactured by I-Graphics Co., Ltd.) was irradiated for about 10 seconds (cumulative light intensity of about 400 mJ / cm²). 2 The film was obtained by irradiation and UV curing treatment. The physical properties and evaluation results of the obtained film are shown in Table 1.

[0111] (Comparative Example 5) Mixed raw material pellets were prepared by dry blending 70 parts by mass of A3 and 30 parts by mass of D1. The mixed raw material pellets were fed from the hopper into a single-screw extruder A and melted, and then extruded as a single-layer resin layer from a single-layer die. The extruded resin layer was cooled and solidified on a cooling drum controlled at 35°C while being pressed with the air pressure of an air knife to obtain an unstretched film with a thickness of 900 μm. The obtained unstretched film was subjected to simultaneous biaxial stretching using a Bruckner batch-type biaxial stretcher "KAROIV". Using the following equipment settings and stretching ratio of the unstretched film as stretching conditions, a film with a total thickness of approximately 100 μm was obtained. The physical properties and evaluation results of the obtained film are shown in Table 1. Equipment settings: Preheating temperature 165°C, preheating time 2 minutes, stretching temperature (longitudinal and transverse stretching temperatures) 165°C, stretching speed 100% / second. Stretching and heat treatment conditions for unstretched film: After simultaneous biaxial stretching to 3.3 times its original length in the longitudinal direction and 3.3 times its original length in the transverse direction, the film was relaxed to 3 times its original length in the longitudinal direction and 3 times its original length in the transverse direction in an oven at a set temperature of 170°C, and then heat-set for 20 seconds.

[0112] (Comparative Example 7) Anhydrous magnesium chloride, decane, and 2-ethylhexyl alcohol were mixed and heated. Phthalic anhydride was added to the heated solution and the mixture was further stirred. After the solution cooled, it was added dropwise to titanium tetrachloride cooled to -20°C. The mixture was then heated, diisobutyl phthalate was added and stirred, and a solid was obtained by filtration. The obtained solid was washed with decane and hexane to obtain a titanium catalyst for use in propylene polymerization.

[0113] Propylene polymerization was carried out using the above-mentioned titanium catalyst, triethylaluminum as a co-catalyst, and hydrogen as a chain transfer agent. After deactivating the obtained product, it was thoroughly washed with propylene monomer to obtain a polypropylene resin. The MFR of this polypropylene resin was 2.5 g / 10 min, and the mesopentade fraction (mmmm) was 0.980.

[0114] To the obtained polypropylene resin, 99.7% by mass was mixed with 0.1% by mass of BHT and 0.2% by mass of Irganox-1010 as antioxidants. The mixture was then kneaded and pelletized at a temperature of 260°C to obtain a polypropylene resin composition.

[0115] The aforementioned polypropylene resin composition was supplied at 100% by mass to a single-screw melt extruder and melt extruded at 250°C. Foreign matter was removed using a 25 μm cut sintered filter. The shear rate applied to the T-die during extrusion was 300 sec. -1The molten polypropylene resin composition extruded from the T-die was brought into close contact with four consecutive cast drums to obtain a molten sheet. The diameters of the consecutive cast drums were the same, and they were designated CD1, CD2, CD3, and CD4 from upstream of the apparatus. The film path was such that each surface of the cast sheet alternately contacted each cast drum. The surface temperatures of CD1 and CD2 were 30°C, and the surface temperatures of CD3 and CD4 were 90°C. The time that the molten sheet was in close contact with each cast drum (CD1, CD2, CD3, and CD4) was 0.4 seconds. An air knife and edge spot air were used to bring the sheet into close contact with the first cast drum, CD1. The air temperature of the air knife was adjusted to 30°C. Furthermore, the ambient temperature of the casting process was also adjusted to 30°C. Next, the cast sheet was preheated using a heated roll, heated to a film temperature of 145°C, and then stretched 5.5 times in the longitudinal direction. The longitudinal stretching speed at this stage was 2,000,000% / min, and the neck-down ratio was 98%. Next, the ends were held with clips and stretched 10 times in the width direction at a stretching speed of 30,000% / min at 155°C. Furthermore, heat treatment was performed at 158°C for 7 seconds to allow 12% relaxation in the width direction. After that, after simmering to room temperature, one side of the film was subjected to a heat treatment of 25 W·min / m². 2 Corona discharge treatment was applied at the specified treatment strength, and the edges of the film, held with clips, were cut and removed. The side in contact with CD1, which underwent corona discharge treatment, was designated as surface A, and the other side in contact with CD2, which was not treated with corona discharge, was designated as surface B. The film with the edges removed was wound up on a winding machine to obtain a biaxially oriented polypropylene film with a thickness of 2.5 μm.

[0116] Note that since Example 5 and Comparative Examples 5 and 7 have a single-layer structure, there is no distinction between the surface layer (I) and the inner layer (II). However, in Table 1, the film compositions of Comparative Examples 5 and 7 are listed in the Surface Layer (I) column. [Industrial applicability]

[0117] The film of the present invention can be used in a variety of industrial applications, including packaging films, surface protection films, support films, sanitary products, agricultural products, building materials, medical products, and capacitor films. In particular, because it does not have large protrusions, has a predetermined recessed structure, and has excellent release properties, rigidity, and heat resistance, it can be preferably used as a support film (especially as a process film in the manufacturing process of resin composition films). [Explanation of Symbols]

[0118] 1:Smr2 2: Roughness curve 3: Equivalent Line 4:Spk

Claims

1. A biaxially oriented film in which, when a surface having a skewness Ssk of -5 or more and 0 or less, a load area ratio Smr2 of 70% or more and 98% or less, and a protruding peak height Spk of 1 nm or more and 100 nm or less is designated as surface A, at least one of the surfaces is surface A, and the surface layer having surface A is mainly composed of an olefin resin and also contains at least one of an olefin elastomer resin and a polypropylene block copolymer.

2. The biaxially oriented film according to claim 1, wherein the maximum valley depth Sv of surface A is 20 nm or more and 400 nm or less.

3. The biaxially oriented film according to claim 1 or 2, wherein the coefficient of dynamic friction μd between one surface and the other surface is 0.20 or more and 0.80 or less.

4. A biaxially oriented film according to any one of claims 1 to 3, wherein the Young's modulus in the MD direction of the film at 130°C is 100 MPa or more and 200 MPa or less.

5. A biaxially oriented film according to any one of claims 1 to 4, having a melting peak at 160°C or higher when heated from 30°C to 260°C using a differential scanning calorimeter (DSC).

6. A biaxially oriented film according to any one of claims 1 to 5, wherein the internal haze after heating at 130°C for 10 minutes is 0.01% or more and 1.5% or less.

7. The biaxially oriented film according to any one of claims 1 to 6, wherein the surface free energy of surface A is 15 mN / m or more and 35 mN / m or less.

8. The biaxially oriented film according to any one of claims 1 to 7, wherein the surface layer having surface A is mainly composed of polypropylene resin.

9. A biaxially oriented film according to any one of claims 1 to 8, used in a process film.

10. A laminate having a resin composition layer on the A-surface of a biaxially oriented film according to any one of claims 1 to 9.

11. A method for producing a resin composition film comprising at least the following steps 1 to 3 in this order. Step 1: A step of applying a coating agent containing a resin composition to the A-side of the biaxially oriented film according to any one of claims 1 to 9. Step 2: A step of solidifying the coating agent containing the resin composition to form a resin composition layer and a laminate. Step 3: Step of peeling the resin composition layer from the laminate to obtain a resin composition film.

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