WO2024070442A1

WO2024070442A1 - Film, laminated film, and film production method

Info

Publication number: WO2024070442A1
Application number: PCT/JP2023/031447
Authority: WO
Inventors: 一仁宮宅; 竜太竹上
Original assignee: 富士フイルム株式会社
Priority date: 2022-09-26
Filing date: 2023-08-30
Publication date: 2024-04-04

Abstract

The present invention addresses the problem of providing a film in which, when a functional layer is disposed on one surface of the film while conveying the film, and the resultant film is wound and then subsequently fed out, an unevenness defect is unlikely to occur on a surface of the functional layer. A film according to the present invention comprises a resin substrate and a resin layer, wherein the resin layer has protrusions on a surface thereof, and the ratio of the height of the protrusions to the long diameter of the protrusions is not more than 0.70.

Description

Film, laminated film, and film manufacturing method

The present invention relates to a film, a laminated film, and a method for producing a film.

Films with excellent smoothness and slipperiness are used in a variety of applications. Films with the above properties are used, for example, as films for touch panels, films for optical components, substrates for molding, substrates for decorative films, and substrates for photosensitive layers.

Films having the above properties are often produced by providing particle-derived protrusions on at least one surface of the film.
For example, Patent Document 1 describes the production of a biaxially oriented film by applying a coating liquid in which acrylic particles are dispersed in water to one surface of a thermoplastic resin film (resin substrate).
Furthermore, Patent Document 2 describes a method of obtaining a film by applying a coating liquid containing a solvent and resin particles to one surface of a polyester film (resin substrate).

JP 2005-015539 A JP 2014-223784 A

On the other hand, when providing a layer (functional layer) for realizing a specific function to such a film, the functional layer is often formed while the film is being transported. Also, the film on which the functional layer has been formed is generally wound up into a roll after the functional layer has been formed, and then unwound when the film is to be used.

The inventors have found that when a functional layer is formed on the film described in

Patent Documents

1 and 2 while it is being transported, and the resulting film is wound up, uneven defects may occur on the surface of the functional layer when the film is unwound. If uneven defects such as those described above occur on the surface of the functional layer, they will affect the function of the functional layer and things formed using the functional layer, and so it has been desirable to prevent their occurrence.

Therefore, the present invention aims to provide a film in which a functional layer is placed on one surface of a film while the film is being transported, the resulting film is wound up, and then the film is unwound, such that unevenness defects are less likely to occur on the surface of the functional layer.
Another object of the present invention is to provide a laminated film including a film and a functional layer, and a method for producing the film.

The inventors conducted extensive research to solve the above problems, and as a result, completed the present invention. In other words, they discovered that the above problems can be solved by the following configuration.

[1] A film including a resin substrate and a resin layer,
the resin layer has protrusions on its surface,
A film, wherein the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less.
[2] The film according to [1], wherein the protrusions contain a non-polyester resin.
[3] The film according to [1] or [2], wherein the protrusions contain at least one of an acrylic resin and a styrene resin.
[4] The film according to any one of [1] to [3], wherein the resin layer is a single coating layer.
[5] The film according to any one of [1] to [4], wherein the resin layer contains at least one binder selected from the group consisting of acrylic resins, urethane resins, and olefin resins.
[6] The film according to [5], wherein the binder contains a resin having an acid group.
[7] The film according to any one of [1] to [6], wherein the resin layer is a crosslinked film.
[8] The film according to any one of [1] to [7], wherein the resin layer has a thickness of 0.01 to 1 μm.
[9] The film according to any one of [1] to [8], wherein the protrusions are present in an area of ^10,000 μm2 on the surface of the resin layer, and the number of the protrusions is 50 or more.
[10] The film according to any one of [1] to [9], wherein the ratio of the major axis of the protrusions to the minor axis of the protrusions is greater than 1.60.
[11] A laminated film comprising the film according to any one of [1] to [10] and a functional layer,
The resin layer, the resin substrate, and the functional layer are provided in this order,
The laminate film, wherein the functional layer is one selected from the group consisting of a decorative layer, a photosensitive resin layer, an inorganic layer, and a release layer.
[12] A step of forming a layer on at least one surface of a resin substrate using a composition containing non-crosslinked resin particles A, a resin B, and a solvent;
and stretching the resin base material on which the layer is formed while heating it at a temperature Y, wherein the method for producing a film satisfies the following

requirements

1 and 2.
Requirement 1: The value obtained by subtracting the glass transition temperature of the non-crosslinked resin particles A from the temperature Y is from -20 to 50°C.
Requirement 2: When the resin B is present in the form of particles in the composition, the particle diameter of the particulate resin B is smaller than the particle diameter of the non-crosslinked resin particles A.
[13] The method for producing a film according to [12], wherein the resin substrate is a uniaxially oriented resin substrate obtained by stretching an unstretched resin substrate.
[14] The method for producing a film according to [12] or [13], wherein the resin B is a resin having an acid group, and the composition further contains a crosslinking agent.
[15] The method for producing a film according to any one of [12] to [14], wherein the non-crosslinked resin particles A have a glass transition temperature of 70 to 140° C.
[16] The method for producing a film according to any one of [12] to [15], wherein the glass transition temperature of the resin B is −50 to 105° C.
[17] The method for producing a film according to any one of [12] to [16], wherein, in the composition, when the resin B is present in a particulate form, the particle diameter of the resin B is Db μm and the particle diameter of the non-crosslinked resin particles A is Da, the relationship of formula (1) is satisfied.
Formula (1) 7 × Db < Da

According to the present invention, a functional layer is placed on one surface of a film while the film is being transported, and the resulting film is wound up and then unwound, thereby providing a film in which unevenness defects are less likely to occur on the surface of the functional layer.
According to the present invention, a laminated film including a film and a functional layer can be provided. Furthermore, according to the present invention, a method for producing a film can be provided.

FIG. 1 is a cross-sectional view showing an example of the configuration of a film of the present invention. 1 is an observation image of the surface of a biaxially oriented film produced by a method similar to that of the example. 1 is an observation image of the surface of a biaxially oriented film produced by a method similar to that of the comparative example.

The present invention will be described in detail below.
The following description of the configuration may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

The following describes the meaning of each description in this specification.
In this specification, a numerical range expressed using "to" means a range including the numerical values described before and after "to" as the lower and upper limits. In the numerical ranges described in stages in this specification, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In addition, in the numerical ranges described in this specification, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the examples.
In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified.
In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.
As used herein, a combination of two or more preferred aspects is a more preferred aspect.

In this specification, the term "longitudinal direction" refers to the longitudinal direction of a film during its production, and is synonymous with the terms "conveyance direction" and "machine direction."
In this specification, the "width direction" refers to a direction perpendicular to the longitudinal direction. In this specification, "perpendicular" is not limited to strictly perpendicular, but includes approximately perpendicular. "Approximately perpendicular" means that the direction intersects within a range of 90°±5°, preferably within a range of 90°±3°, and more preferably within a range of 90°±1°.
In this specification, the "major axis" refers to the longest diameter of a protrusion in the in-plane direction when the protrusion is observed on the surface of the film. More specifically, the major axis is defined as the distance between two parallel lines selected so as to have the maximum distance between them, among two parallel lines circumscribing the shape of the protrusion in the in-plane direction when the protrusion is observed.
In this specification, the "minor diameter" refers to the longest diameter of a protrusion in the in-plane direction in a direction perpendicular to the longest diameter (major diameter) of the protrusion when the protrusion is observed on the surface of a film. More specifically, the minor diameter is defined as the distance between two parallel lines selected so as to be the shortest distance between the two parallel lines that are perpendicular to the two parallel lines that give the major diameter and circumscribe the shape of the protrusion in the in-plane direction.

[film]
The film of the present invention (hereinafter also simply referred to as "the film") is a film comprising a resin substrate and a resin layer, in which the resin layer has protrusions on its surface, and the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less.
The structure of the present film will be described with reference to the drawings.
1 is a cross-sectional view showing an example of the configuration of the present film. The film 1 of the present invention includes a resin layer 2 and a resin substrate 3, and has a first main surface 4 and a second main surface 5. The second main surface 5 is one of the surfaces of the resin layer 2, and the resin layer 2 has protrusions 6 on the surface that is the second main surface 5. A functional layer (not shown) can be provided on the first main surface 4. The ratio of the height of the protrusions 6 to the major axis of the protrusions 6 is 0.70 or less.

While the film is being transported, a functional layer is placed on one surface of the film, and the resulting film is then wound up and unwound. The details of the mechanism by which unevenness defects are less likely to occur on the surface of the functional layer when the film is then unwound are not entirely clear, but the inventors speculate as follows.
When a film is transported, the film comes into contact with other members such as a transport roll, etc. From the viewpoint of transportability of the film, when protrusions are provided on the surface of the film, it is conceivable that the protrusions on the surface of the film or a part of the film including the protrusions may fall off as particles due to an impact or the like caused by contact between the surface of the film having the protrusions and another member such as a transport roll.
If the particles fall off as described above, the particles may adhere to the surface of the film opposite to the side having the protrusions when the film is wound before the functional layer is formed. In this state, if a functional layer is formed on the surface of the film opposite to the side having the protrusions, the adhered particles may become foreign matter and form convex portions in the functional layer. Furthermore, if the particles that have become foreign matter in the functional layer fall off from the functional layer, they may form concave portions in the functional layer.
In addition, when the particles fall off as described above, the particles may adhere to the surface of the film having the protrusions. In this state, when the film obtained by forming the functional layer is wound up, the particles migrate to the surface of the functional layer, and when the film is unwound, the particles adhere to the surface of the functional layer, and the functional layer may form a convex portion. In addition, the pressure acting when winding and during storage may push the particles into the functional layer, forming a concave portion in the functional layer.
On the other hand, when the film obtained by forming the functional layer is wound in a state where the particles are likely to be generated as described above, the particles may migrate to the surface of the functional layer. When the film is unwound in such a state, the particles may adhere to the surface of the functional layer, and convex portions may be formed on the functional layer.

This film includes a resin substrate and a resin layer, and the resin layer has protrusions on its surface. With the above-mentioned configuration, not only are the parts constituting the protrusions attached to the resin substrate as in

Patent Documents

1 and 2, but the parts constituting the protrusions are also held by the resin layer, and it is considered that the parts constituting the protrusions are less likely to fall off as particles.
In addition, in this film, the ratio of the height of the protrusion to the major axis of the protrusion is 0.70 or less. In the above-mentioned configuration, the protrusion is relatively flat, and the contact area between the bottom surface of the protrusion and the resin layer is considered to be large. In this case, the part constituting the protrusion is less likely to fall off as particles, and as a result, it is considered that unevenness defects are less likely to occur on the surface of the functional layer.

In the following, when a functional layer is placed on one surface of the film while the film is being transported, and the resulting film is then wound up and unwound, unevenness defects are unlikely to occur on the surface of the functional layer, which is also referred to as "unevenness defects are suppressed."

〔composition〕
The structure of this film will now be described.
The film includes at least a resin substrate and a resin layer, and the resin layer has protrusions on its surface, and the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less. The ratio of the height of the protrusions to the major axis of the protrusions will be described later.
The film also has a first major surface and a second major surface.
Of the two main surfaces of the present film, the first main surface is a surface on which a functional layer, which will be described later, can be formed. That is, after the present film is produced, a functional layer is formed on the first main surface to produce a laminated film having the film and the functional layer.
Of the two main surfaces of the resin substrate, the second main surface opposite to the first main surface is one of the surfaces of the resin layer. That is, the resin layer constitutes the outermost layer of the present film. In other words, the present film is a film including a resin substrate and a resin layer, and has protrusions on the surface of the resin layer opposite to the resin substrate side.

The present film is not limited to having the above-mentioned configuration, so long as it has at least the above-mentioned resin substrate and resin layer and satisfies the above-mentioned ratio regarding the protrusions.
For example, the present film may have another layer, such as a primer layer, provided between the resin layer and the resin substrate.

The layers of this film are explained in detail below.

<Resin Layer>
The resin layer is a layer formed on one surface of the resin substrate. The resin layer is continuously formed on one surface of the resin substrate. In addition, protrusions are formed on the surface of the resin layer opposite to the surface facing the resin substrate.
By virtue of having the above-mentioned resin layer, the present film improves the transportability of the film and the laminated film, while suppressing unevenness defects.

The resin layer may be provided directly on the surface of the resin substrate, or may be provided on the surface of the resin substrate via another layer, but it is preferable to provide the resin layer directly on the surface of the resin substrate, as this provides better adhesion.

The resin layer is not particularly limited as long as it is a layer member having protrusions on at least one surface, but preferably contains a binder. The binder contained in the resin layer is preferably a non-polyester resin other than polyester resin. In addition, the resin layer may contain additives other than the substance constituting the protrusions and the non-polyester resin.
In this specification, the term "binder" refers to a component that contains a resin other than the substance that constitutes the protrusions.
In addition, the resin layer is preferably a single layer in that irregularity defects can be suppressed. In addition, as described later, the resin layer is preferably a coating layer formed using a composition containing non-crosslinked resin particles A, a resin B, and a solvent. The term "coating layer" refers to a layer formed by a process that includes at least a process of forming a liquid composition by coating.
It is also preferable that the resin layer is a single layer and a coated layer.

(protrusion)
The material constituting the protrusions is not particularly limited, and may be one type alone or a combination of two or more types. In addition, the material constituting the protrusions may be the same as or different from the binder.

Examples of the protrusions present on the surface of the resin layer include protrusions formed by particles, which will be described later. Protrusions formed by organic particles are preferred because they can suppress irregularity defects and the ratio of the height of the protrusion to the major axis of the protrusion is likely to be 0.70 or less. Details of the mechanism by which irregularity defects can be suppressed when the protrusions are formed by organic particles are not clear, but it is speculated as follows. That is, when the present film comes into contact with a contacted object on the second main surface, the force received by the protrusions is absorbed by the deformation of the protrusions, and as a result, it is speculated that the material constituting the protrusions is less likely to fall off, and as a result, irregularity defects can be suppressed.
As the organic particles, resin particles are preferred. As the resin constituting the resin particles, for example, non-polyester resins can be mentioned, and styrene resin, urethane resin, acrylic resin, and silicone resin are preferred. Among them, the organic particles preferably contain at least one selected from the group consisting of styrene resin, acrylic resin, and urethane resin, and more preferably contain at least one selected from the group consisting of styrene resin and acrylic resin, in that the ratio of the height of the protrusion to the major axis of the protrusion is likely to be 0.70 or less.
In other words, the protrusions preferably contain the resin that constitutes the above-mentioned resin particles.

In this specification, the styrene resin means a resin containing structural units derived from styrene.
Examples of the styrene resin constituting the resin particles include homopolymers consisting of styrene, and styrene copolymers such as styrene-acrylic copolymers containing styrene-derived structural units and acrylate or methacrylate-derived structural units. The styrene resin preferably contains 50 mol % or more of styrene-derived structural units relative to the total structural units.
The urethane resin constituting the resin particles is not limited as long as it is a polymer having a urethane bond, and known urethane resins such as reaction products of an isocyanate compound and a polyol compound can be used.
In the present specification, the term "acrylic resin" refers to a resin containing structural units derived from acrylate or methacrylate. The acrylic resin preferably contains 50 mol % or more of structural units derived from acrylate or methacrylate based on the total structural units.

The resin particles may be crosslinked resin particles having a crosslinked structure, but are preferably non-crosslinked resin particles having no crosslinked structure. Examples of the crosslinked resin particles include crosslinked urethane resin particles made of a urethane resin having a crosslinked structure. Examples of the non-crosslinked resin particles include non-crosslinked styrene resin particles made of a non-crosslinked styrene resin and non-crosslinked acrylic resin particles made of a non-crosslinked acrylic resin.
The resin particles may be used alone or in combination of two or more kinds. That is, two or more kinds of non-crosslinked resin particles may be used in combination. Also, non-crosslinked resin particles and crosslinked resin particles may be used in combination. When non-crosslinked resin particles and crosslinked resin particles are used in combination, it is preferable that the height of the protrusions formed by the non-crosslinked resin particles is greater than the height of the protrusions formed by the crosslinked resin particles.

An example of a commercially available styrene resin particle is Nipol (registered trademark) UFN1008 (manufactured by Zeon Corporation).
Commercially available urethane resin particles include, for example, Art Pearl (registered trademark) C-1000T and MM110SMA (manufactured by Negami Chemical Industrial Co., Ltd.).
An example of a commercially available acrylic resin particle is MP1000 (manufactured by Soken Chemical & Engineering Co., Ltd.).

(binder)
In terms of being highly effective in suppressing unevenness defects during long-term storage, the resin layer preferably contains a non-polyester resin as a binder.
The non-polyester resin contained as a binder in the resin layer is not particularly limited as long as it is a resin other than a polyester resin, but examples thereof include an acrylic resin, a urethane resin, an olefin resin, a polyvinyl alcohol resin, and an acrylonitrile butadiene resin. From the viewpoint of obtaining a superior effect of the present invention, an acrylic resin, a urethane resin, or an olefin resin is preferred, and a urethane resin is more preferred.
Here, it is presumed that since the acrylic resin and olefin resin are insufficiently compatible with the polyester resin preferably used for the resin substrate, foreign matter caused by impurities such as oligomers precipitated from the polyester resin is unlikely to occur even after long-term storage. In addition, it is presumed that for urethane resins with high hydrophobicity (i.e., urethane resins with SP values sufficiently different from those of polyester resins), unevenness defects during long-term storage can be suppressed for the same reason as for acrylic resins and olefin resins.
The acrylic resin, olefin resin, and urethane resin are not particularly limited, and known resins can be used.
The non-polyester resin contained as a binder in the resin layer is also preferably a resin having an acid group.

The olefin resin may be any resin containing a structural unit derived from an olefin in the main chain. The olefin is not particularly limited, but is preferably an alkene having 2 to 6 carbon atoms, more preferably ethylene, propylene, or hexene, and even more preferably ethylene.
The olefin-derived structural units contained in the olefin resin preferably account for 50 to 99 mol %, and more preferably 60 to 98 mol %, of all the structural units in the olefin resin.

As the olefin resin, an acid-modified olefin resin is preferred in that it can suppress unevenness defects during long-term storage. Examples of the acid-modified olefin resin include copolymers obtained by modifying the above-mentioned olefin resin with an acid-modifying component such as an unsaturated carboxylic acid or its anhydride. That is, the olefin resin is preferably an olefin resin having an acid group.
Examples of the acid-modified component include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, and crotonic acid, as well as half esters and half amides of unsaturated dicarboxylic acids. From the viewpoint of dispersion stability of the resin, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred.

The acid group contained in the acid-modified olefin resin includes a carboxyl group, a sulfo group, and a phosphoric acid group, which are acid groups corresponding to the above-mentioned acid-modified component, and the carboxyl group is preferred. The acid group may form an acid anhydride or may be neutralized with at least one selected from an alkali metal, an organic amine, and ammonia.
The acid-modified olefin resin may contain only one type of structural unit having an acid group, or may contain two or more types.

Commercially available acid-modified olefin resins include, for example, the ZAIXXEN (registered trademark) series, such as ZAIXXEN AC, A, L, NC, and N (manufactured by Sumitomo Seika Chemicals Co., Ltd.), the CHEMIPEARL (registered trademark) series, such as CHEMIPEARL S100, S120, S200, S300, S650, and SA100 (manufactured by Mitsui Chemicals, Inc.), and the HI-TECH (registered trademark) series, such as HI-TECH S3121 and S3148K (manufactured by Mitsui Chemicals, Inc.). Examples of such an adhesive include the Arrowbase (registered trademark) series (manufactured by Unitika Ltd.), such as Arrowbase SE-1013, SE-1010, SB-1200, SD-1200, SD-1200, DA-1010, and DB-4010 (manufactured by Toho Chemical Industries, Ltd.), Hardlen AP-2, NZ-1004, and NZ-1005 (manufactured by Toyobo Co., Ltd.), and Sepolsion G315 and VA407 (manufactured by Sumitomo Seika Chemicals Co., Ltd.).
In addition, the acid-modified olefin resins described in paragraphs [0022] to [0034] of JP-A-2014-076632 can also be preferably used.

The acrylic resin is a resin containing a structural unit derived from a (meth)acrylate, and may be copolymerized with a vinyl monomer such as styrene. The acrylic resin is not particularly limited, but preferably contains a structural unit derived from a (meth)acrylate having an alkyl group with 1 to 12 carbon atoms, and more preferably contains a structural unit derived from a (meth)acrylate having an alkyl group with 1 to 8 carbon atoms.
In terms of suppressing unevenness defects during long-term storage, the acrylic resin preferably has an acid-modified component. The acrylic resin preferably contains a structural unit derived from (meth)acrylic acid. That is, the acrylic resin is preferably an acrylic resin having an acid group.
The (meth)acrylic acid may form an acid anhydride, or may be neutralized with at least one selected from an alkali metal, an organic amine, and ammonia.
When an aqueous dispersion of an acrylic resin is used to produce the resin layer, an aqueous dispersion containing an acrylic resin and a dispersant can be preferably used.
The amount of the (meth)acrylate-derived structural unit contained in the acrylic resin is preferably 50 to 100 mol % based on all the structural units of the acrylic resin.
The acid value of the acrylic resin is preferably 30 mgKOH/g or less, more preferably 20 mgKOH/g or less. The lower limit of the acid value is not particularly limited and is, for example, 0 mgKOH/g, but is preferably 2 mgKOH/g or more from the viewpoint of coating as a water dispersion.
When an acrylic resin having a solubility parameter (SP value) far from that of the polyester resin is used, the compatibility between the acrylic resin and the polyester resin becomes insufficient, and as a result, the effect of suppressing unevenness defects during long-term storage can be further improved. Such an acrylic resin can be obtained by adjusting the acid value to be within the above range and by containing a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, for example.

The urethane resin is not limited as long as it is a polymer having a urethane bond, and known urethane resins such as reaction products of an isocyanate compound and a polyol compound can be used.
When an aqueous dispersion containing a urethane resin is used to produce a resin layer, the aqueous dispersion preferably contains a urethane resin having an acidic group (e.g., a carboxyl group) or contains a urethane resin and a dispersant, which improves the film-forming properties of the resin layer.
The urethane resin can be adjusted to a desired SP value by adjusting at least one of the structure of the raw polyol compound, the hydrophobicity or hydrophilicity of the raw polyol, the structure of the raw isocyanate compound, and the hydrophobicity or hydrophilicity of the raw isocyanate compound. By using a urethane resin adjusted to have high hydrophobicity in this way, the compatibility between the urethane resin and the polyester resin becomes insufficient, and as a result, the effect of suppressing unevenness defects during long-term storage can be further improved.
Among urethane resins, urethane resins having a polyester structure (polyester-based urethane resins) are preferred because they are highly hydrophobic and can further improve the effect of suppressing unevenness defects during long-term storage.

Commercially available urethane resins include, for example, Hydran (registered trademark) AP-40N, HW-312B, and HW-350 (all manufactured by DIC Corporation), Takelac (registered trademark) W-5030 and W-6020 (all manufactured by Mitsui Chemicals, Inc.), Adeka Bontitor (registered trademark) HUX-524 (manufactured by ADEKA Corporation), and Superflex (registered trademark) 210 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

The resin layer may contain one kind of non-polyester resin as a binder, or may contain two or more kinds of non-polyester resins.
The content of the binder in the resin layer is preferably from 30 to 99.8% by mass, and more preferably from 50 to 99.5% by mass, based on the total mass of the resin layer, in that irregularity defects can be further suppressed.

In addition, the binder contained in the resin layer is preferably crosslinked by a crosslinking agent or the like described below. That is, the resin layer is preferably a crosslinked film. When the resin layer is a crosslinked film, the entire resin layer may be crosslinked, or the resin layer may have a region that is not crosslinked.
An example of the resin layer being a crosslinked film is a method in which, when protrusions are formed using non-crosslinked resin particles by the method described below, non-crosslinked resin particles and a binder are crosslinked with a crosslinking agent to form a crosslinked film. When non-crosslinked resin particles and a binder are crosslinked with a crosslinking agent or the like, in the resulting protrusions, a chemical bond is formed between the resin particles and the binder, so that the substances constituting the protrusions are more unlikely to fall off, unevenness defects can be further suppressed, and solvent resistance is also excellent. In addition, when the resin layer is a crosslinked film, precipitation of oligomers is suppressed, and unevenness defects during long-term storage can be suppressed. When non-crosslinked resin particles and a binder are crosslinked with a crosslinking agent or the like, the protrusions may contain only a crosslinked resin, or may contain a crosslinked resin and a non-crosslinked resin.

(Additive)
The resin layer may contain additives other than the above-mentioned substances constituting the protrusions and the binder.
Examples of additives contained in the resin layer include surfactants, waxes, dispersants, antioxidants, UV absorbers, colorants, reinforcing agents, plasticizers, antistatic agents, flame retardants, rust inhibitors, and fungicides.

The resin layer preferably contains a surfactant, since this improves the smoothness of the areas of the second principal surface other than where the protrusions are present. By improving the smoothness of the above-mentioned areas of the second principal surface and reducing the surface roughness of the second principal surface due to factors other than the presence of the protrusions, it is possible to control the physical properties, including the ratio of the protrusion height to the major axis of the protrusions and the protrusion height, within a desired range, and to further suppress unevenness defects.

The surfactant is not particularly limited, and examples thereof include silicone-based surfactants, fluorine-based surfactants, and hydrocarbon-based surfactants. Hydrocarbon-based surfactants are preferred because they can suppress charging on the second principal surface.

The silicone surfactant is not particularly limited as long as it has a silicon-containing group as a hydrophobic group, and examples thereof include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane.
Commercially available silicone surfactants include, for example, BYK (registered trademark)-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, and BYK-349 (all manufactured by BYK Corporation), as well as KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The fluorosurfactant is not particularly limited as long as it has a fluorine-containing group as a hydrophobic group, and examples thereof include perfluorooctanesulfonic acid and perfluorocarboxylic acid.
Commercially available fluorine-based surfactants include, for example, Megafac (registered trademark) F-114, F-410, F-440, F-447, F-553, and F-556 (all manufactured by DIC Corporation), and Surflon (registered trademark) S-211, S-221, S-231, S-233, S-241, S-242, S-243, S-420, S-661, S-651, and S-386 (manufactured by AGC Seimi Chemical Co., Ltd.).
Furthermore, from the viewpoint of improving environmental compatibility, preferred fluorine-based surfactants are surfactants derived from alternative materials to compounds having a linear perfluoroalkyl group having 7 or more carbon atoms, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).

Examples of the hydrocarbon surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.
Examples of anionic surfactants include alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, alkyl phosphates, and fatty acid salts.
Examples of the nonionic surfactant include polyalkylene glycol mono- or dialkyl ethers, polyalkylene glycol mono- or dialkyl esters, and polyalkylene glycol monoalkyl esters and monoalkyl ethers.
Cationic surfactants include primary to tertiary alkylamine salts and quaternary ammonium compounds.
Amphoteric surfactants include surfactants having both anionic and cationic moieties in the molecule.

Commercially available anionic surfactants include, for example, Rapisol (registered trademark) A-90, A-80, BW-30, B-90, and C-70 (all manufactured by NOF Corp.), NIKKOL (registered trademark) OTP-100 (all manufactured by Nikko Chemical Co., Ltd.), Kohacool (registered trademark) ON, L-40, and Phosphanol (registered trademark) 702 (all manufactured by Toho Chemical Industry Co., Ltd.), and Viewlite (registered trademark) A-5000 and SSS (all manufactured by Sanyo Chemical Industries, Ltd.).
Examples of commercially available nonionic surfactants include Naroacty (registered trademark) CL-95 and HN-100 (product names: manufactured by Sanyo Chemical Industries, Ltd.), Lysolex BW400 (product name: manufactured by Kokyu Alcohol Kogyo Co., Ltd.), EMALEX (registered trademark) ET-2020 (all manufactured by Nippon Emulsion Co., Ltd.), and Surfynol (registered trademark) 104E, 420, 440, 465, and Dynol (registered trademark) 604, 607 (all manufactured by Nissin Chemical Industry Co., Ltd.).

As the hydrocarbon surfactant, at least one of an anionic surfactant and a nonionic surfactant is preferred, with anionic surfactants being more preferred, in that a coating layer with a smooth surface can be formed without impeding the dispersion of the resin. In other words, as the surfactant, an anionic hydrocarbon surfactant is more preferred in terms of improving surface smoothness.

The anionic hydrocarbon surfactant preferably has a plurality of hydrophobic end groups in terms of further improving smoothness. The hydrophobic end group may be a part of the hydrocarbon group of the hydrocarbon surfactant. For example, a hydrocarbon surfactant having a branched chain structure at its end will have a plurality of hydrophobic end groups.
Examples of anionic hydrocarbon surfactants having multiple hydrophobic end groups include sodium di-2-ethylhexyl sulfosuccinate (having four hydrophobic end groups), sodium di-2-ethyloctyl sulfosuccinate (having four hydrophobic end groups), and branched alkylbenzene sulfonate (having two hydrophobic end groups).

The surfactant may be used alone or in combination of two or more kinds.
The content of the surfactant is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, and further preferably 0.5 to 2% by mass, based on the total mass of the resin layer, in terms of superior surface smoothness.

The wax is not particularly limited, and may be either natural or synthetic wax. Examples of natural waxes include carnauba wax, candelilla wax, beeswax, montan wax, paraffin wax, and petroleum wax. In addition, the slip agent described in [0087] of WO 2017/169844 can also be used.
The wax content is preferably 0 to 10% by mass based on the total mass of the resin layer.

(thickness)
The resin layer can be formed, for example, by applying a particle-containing composition onto one surface of the resin substrate as described below. In this case, the thickness of the resin layer is often 0.001 to 1 μm, and is more preferably 0.01 to 1 μm, and even more preferably 0.02 to 1 μm, in that irregularity defects in the formed functional layer are suppressed when a laminate film produced using the present film is stored for a long period of time.
The resin layer may be formed by co-extruding the resin used to form the resin substrate and the resin used to form the resin layer. In this case, the thickness of the resin layer is often 1 to 10 μm.
The thickness of the resin layer is preferably from 10 to 500 nm, more preferably from 20 to 250 nm, and even more preferably from 20 to 100 nm, from the viewpoints of manufacturability of the resin layer and reduction of haze.
The thickness of the resin layer is measured by preparing a sample having a cross section perpendicular to the main surface of the film and using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). More specifically, the thickness of the resin layer is measured at any five points in the resin layer of the sample where no protrusions are formed, and the arithmetic average value is taken as the thickness.

The method for forming the resin layer will be explained in detail in the "Resin layer formation process" below.

<Resin substrate>
The resin substrate is a film-like object containing a resin as a main component. Here, the term "main component" refers to the component that is contained in the largest amount (by mass) among all the components contained in the film-like object.

The resin contained as the main component in the resin substrate is not particularly limited, and any known resin can be used. Since the present film has a characteristic in the resin layer, unevenness defects can be suppressed regardless of the type of resin substrate.
Examples of the resin contained in the resin substrate include polyester resin, carbonate resin, fluororesin, polyimide resin, triacetyl cellulose resin, polyether resin, olefin resin, acrylic resin, styrene resin, vinyl chloride resin, vinyl alcohol resin, and nylon resin. In terms of heat resistance and transparency, polyester resin, carbonate resin, fluororesin, polyimide resin, triacetyl cellulose resin, polyether resin, or olefin resin is preferred, and in terms of moldability and versatility, polyester resin is more preferred.
The resin substrate is preferably a resin substrate containing the above-mentioned preferred resin as a main component, that is, the resin substrate is preferably a polyester substrate, a polycarbonate substrate, a fluororesin substrate, a polyimide substrate, a triacetyl cellulose substrate, a polyether substrate, or a polyolefin substrate, and more preferably a polyester substrate.
The resin substrate may contain two or more kinds of resins. For example, a polyester substrate may contain one kind of polyester resin alone, or may contain two or more kinds of polyester resins.

The resin substrate is preferably a biaxially oriented resin substrate, more preferably a biaxially oriented polyester substrate, i.e., the present film is also preferably a biaxially oriented film.
"Biaxial orientation" means a property of having molecular orientation in two axial directions. The molecular orientation is measured using a microwave transmission type molecular orientation meter (e.g., MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.). The angle between the two axial directions is preferably within the range of 90°±5°, more preferably within the range of 90°±3°, and even more preferably within the range of 90°±1°.
The molecular orientation changes when the film is stretched, and a biaxially oriented resin substrate can be produced by performing biaxial stretching.

The resin substrate is preferably substantially free of particles. "Substantially free of particles" is defined as the particle content being 50 ppm by mass or less, preferably 10 ppm by mass or less, and more preferably below the detection limit, relative to the total mass of the resin substrate when the resin substrate is quantitatively analyzed for elements derived from particles by fluorescent X-ray analysis. This is because even if particles are not actively added to the resin substrate, contaminant components derived from foreign matter, raw resin, or dirt adhering to the line or equipment in the manufacturing process of the resin substrate may peel off and be mixed into the resin substrate. Examples of particles include the particles used in forming the resin layer described above.

The following mainly describes the polyester resin contained in the polyester base material and the polyester base material, but as mentioned above, the resin base material of this film is not limited to a polyester base material.

(Polyester resin)
The polyester resin is a polymer having an ester bond in the main chain, and is usually formed by polycondensation of a dicarboxylic acid compound and a diol compound, which will be described later.
The polyester resin is not particularly limited, and known polyester resins can be used. Examples of the polyester resin include polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), and copolymers thereof, with PET, PEN, and copolymers thereof being preferred, and PET being more preferred.

The intrinsic viscosity of the polyester resin is preferably 0.50 dl/g or more and less than 0.80 dl/g, and more preferably 0.55 dl/g or more and less than 0.70 dl/g.
The melting point (Tm) of the polyester resin is preferably from 220 to 270°C, and more preferably from 245 to 265°C.
The glass transition temperature (Tg) of the polyester resin is preferably from 65 to 90°C, and more preferably from 70 to 85°C.

The method for producing the polyester resin is not particularly limited, and any known method can be used. For example, the polyester resin can be produced by polycondensing at least one dicarboxylic acid compound and at least one diol compound in the presence of a catalyst.

-catalyst-
The catalyst used in the production of the polyester resin is not particularly limited, and any known catalyst that can be used in the synthesis of polyester resins can be used.
Examples of the catalyst include alkali metal compounds (e.g., potassium compounds, sodium compounds), alkaline earth metal compounds (e.g., calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, germanium compounds, and phosphorus compounds. Among these, titanium compounds are preferred from the standpoint of catalytic activity and cost.
The catalyst may be used alone or in combination of two or more. It is preferable to use at least one metal catalyst selected from potassium compounds, sodium compounds, calcium compounds, magnesium compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and germanium compounds in combination with a phosphorus compound, and it is more preferable to use a titanium compound in combination with a phosphorus compound.

The titanium compound is preferably an organic chelate titanium complex, which is a titanium compound having an organic acid as a ligand.
Examples of organic acids include citric acid, lactic acid, trimellitic acid, and malic acid.
As the titanium compound, the titanium compounds described in paragraphs [0049] to [0053] of Japanese Patent No. 5575671 can also be used, and the contents of the above publication are incorporated herein by reference.

-Dicarboxylic acid compound-
Examples of the dicarboxylic acid compound include dicarboxylic acids such as aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, as well as dicarboxylic acid esters such as methyl ester compounds and ethyl ester compounds of these dicarboxylic acids. Among these, aromatic dicarboxylic acids or aromatic methyl dicarboxylates are preferred.

Examples of the aliphatic dicarboxylic acid compound include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, and ethylmalonic acid.
Examples of the alicyclic dicarboxylic acid compound include adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid.

Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylindanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, and 9,9'-bis(4-carboxyphenyl)fluorene acid.
Among these, terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferred, and terephthalic acid is more preferred.

A single dicarboxylic acid compound may be used, or two or more may be used in combination. When terephthalic acid is used as the dicarboxylic acid compound, terephthalic acid may be used alone, or may be copolymerized with other aromatic dicarboxylic acids such as isophthalic acid or aliphatic dicarboxylic acids.

-Diol compound-
Examples of the diol compound include an aliphatic diol compound, an alicyclic diol compound, and an aromatic diol compound, and an aliphatic diol compound is preferable.

Examples of the aliphatic diol compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and neopentyl glycol, with ethylene glycol being preferred.
Examples of the alicyclic diol compound include cyclohexanedimethanol, spiroglycol, and isosorbide.
Examples of aromatic diol compounds include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis(4-hydroxyphenyl)fluorene.
The diol compound may be used alone or in combination of two or more kinds.

-End-capping agent-
In the production of the polyester resin, a terminal capping agent may be used as necessary. By using the terminal capping agent, a structure derived from the terminal capping agent is introduced into the terminal of the polyester resin.
The terminal blocking agent is not limited, and any known terminal blocking agent can be used. Examples of the terminal blocking agent include oxazoline compounds, carbodiimide compounds, and epoxy compounds.
For the terminal blocking agent, reference can also be made to the contents described in paragraphs [0055] to [0064] of JP2014-189002A, the contents of which are incorporated herein by reference.

- Manufacturing conditions -
The reaction temperature is not limited and may be appropriately set depending on the raw materials. The reaction temperature is preferably 260 to 300° C., more preferably 275 to 285° C.
The pressure is not limited and may be appropriately set depending on the raw materials. The pressure is preferably 1.33×10 ⁻³ to 1.33×10 ⁻⁵ MPa, and more preferably 6.67×10 ⁻⁴ to 6.67×10 ⁻⁵ MPa.

The method described in paragraphs [0033] to [0070] of Japanese Patent No. 5575671 can also be used to synthesize polyester resin, and the contents of the above publication are incorporated herein by reference.

The content of the polyester resin in the polyester base material is preferably 85% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the total mass of the polymer in the polyester base material.
The upper limit of the content of the polyester resin is not limited, and can be appropriately set within the range of 100% by mass or less based on the total mass of the polymer in the polyester base material.

When the polyester base material contains polyethylene terephthalate, the content of polyethylene terephthalate is preferably 90 to 100 mass% relative to the total mass of the polyester resin in the polyester base material, more preferably 95 to 100 mass%, even more preferably 98 to 100 mass%, and particularly preferably 100 mass%.

The resin substrate may contain components other than resin (e.g., catalysts, unreacted raw material components, particles, water, etc.).

The thickness of the resin substrate is preferably 300 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. The lower limit of the thickness is not particularly limited, but from the viewpoint of improving strength and processability, it is preferably 3 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more.
The thickness of the resin substrate is measured according to the method for measuring film thickness described below.

The film may further comprise layers other than the above-mentioned resin layer and resin substrate, but it is preferable that the film has a layer structure consisting of a resin layer and a resin substrate.

[Physical properties, etc.]
Next, the physical properties of the present film will be described.

<Physical properties of resin layer>
(Ratio of protrusion height to major axis of protrusion)
In the present film, the resin layer has protrusions on its surface, and the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less.
The ratio of the height of the protrusion to the major axis of the protrusion is defined as a value measured as follows.
A scanning electron microscope is used to observe an area of ^10,000 μm2 on the resin layer surface (second main surface), and the protrusion with the longest major axis in the area is selected. The ratio of the height of the selected protrusion measured by non-contact surface shape measurement using an optical interferometer to the major axis of the selected protrusion measured by the scanning electron microscope is defined as the ratio of the height of the protrusion to the major axis of the protrusion.

The ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less, preferably 0.60 or less, and more preferably 0.30 or less. When in the above range, irregularity defects can be further suppressed and winding properties are also excellent.
Although there is no particular lower limit, in terms of excellent transportability and suppression of variation in protrusion height, the ratio of the protrusion height to the major axis of the protrusions is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.05 or more.

The ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film can be adjusted, for example, by the type and average particle size of the particles used in producing the resin layer, the thickness of the resin layer, and the heat treatment during and after the resin layer formation step described below. A method for producing a film that allows the above adjustment to be performed more easily will be described in detail later.
The ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film is measured according to the method described in the Examples section below.
It should be noted that dust, foreign matter, and dirt adhering from the line or equipment during the manufacturing process of the resin substrate that are present on the surface of the resin layer are not included in the protrusions on the surface of the resin layer.

(Protrusion height, major diameter, minor diameter of protrusion on resin layer surface)
The resin layer of the present film functions as a transport surface in the present film or in a laminate film obtained by forming a functional layer on the first main surface. In terms of excellent transportability, the protrusion height on the resin layer surface of the present film is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.25 μm or more, particularly preferably 0.3 μm or more, and most preferably 0.33 μm or more.
On the other hand, if the protrusions on the resin layer surface are too large, the material constituting the protrusions is likely to fall off during transportation. In addition, during storage of the laminated film in a roll, transfer marks may be formed on the functional layer. In these respects, the protrusion height on the resin layer surface is preferably 5 μm or less, more preferably 4.0 μm or less, and even more preferably 3.5 μm or less. In terms of winding properties, the lower limit is preferably 0.1 μm or more, and more preferably 0.3 μm or more.
That is, in terms of being able to further suppress unevenness defects and being able to provide excellent transportability, the height of the protrusions on the resin layer surface is preferably within the range defined by the above lower limit and upper limit.
In this specification, the "protrusion height on the resin layer surface" refers to the protrusion height obtained by observing an area of ^10,000 μm2 on the resin layer surface (second main surface) using a scanning electron microscope, and performing non-contact surface shape measurement using an optical interferometer on the protrusion with the longest major axis in the above area.

In addition, in terms of excellent transportability and the ability to further suppress unevenness defects, it is preferable that the protrusion height of the second main surface is 0.3 to 5.0 μm and the thickness of the resin layer is 10 to 500 nm (more preferably 20 to 100 nm).

The major axis of the protrusions on the surface of the resin layer of the present film is preferably from 0.1 to 20 μm, more preferably from 0.5 to 10 μm, and even more preferably from 1 to 8 μm.
The minor axis of the protrusions on the surface of the resin layer of the present film is preferably from 0.1 to 20 μm, more preferably from 0.3 to 10 μm, and even more preferably from 1 to 8 μm.
The ratio of the major axis of the protrusions to the minor axis of the protrusions is preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.6 or more, and particularly preferably more than 1.6. The upper limit of the ratio of the major axis of the protrusions to the minor axis of the protrusions is 5.0.
The major axis and minor axis of the protrusions on the surface of the resin layer can be adjusted in accordance with the above-mentioned method for adjusting the ratio of the protrusion height to the major axis of the protrusions.
The major axis and minor axis of the protrusions on the surface of the resin layer are measured according to the method described in the Examples section below.

(Number of protrusions)
On the resin layer surface of the present film, the number of protrusions is preferably 50 or more per observation area of ^10,000 μm2, more preferably 80 or more, and even more preferably 200 or more. The number of protrusions is preferably 20,000 or less, more preferably 15,000 or less, and even more preferably 13,000 or less.
In this specification, the "number of protrusions" refers to the total number of protrusions found in an area of ^10,000 μm2 of the resin layer surface (second main surface) observed using a scanning electron microscope.
In the measurement method described later in the Examples section, protrusions having a major axis of 0.01 μm or more can be recognized as protrusions.

(Average surface roughness Sa of resin layer surface)
In terms of being able to further suppress unevenness defects, the resin layer surface has an average surface roughness Sa of preferably 1 to 15 nm, more preferably 1 to 10 nm, and even more preferably 1 to 8 nm.
The surface average roughness Sa of the resin layer surface can be adjusted, for example, by selecting the average particle size and content of the particles used in producing the resin layer, the thickness of the resin layer, and the types of non-polyester resin and additives (surfactants, etc.) that can be contained in the resin layer. When the resin layer is formed by in-line coating, the above adjustment can be made more easily.

The surface average roughness Sa of the resin layer surface is determined by measuring the surface of the resin layer side of this film using an optical interferometer (for example, Hitachi High-Tech's Vertscan 3300G Lite) under the same conditions as those used to measure the protrusion height when determining the ratio of the protrusion height to the major axis of the protrusion, and then analyzing the data using the built-in data analysis software. When measuring the surface average roughness Sa, measurements are taken five times at different measurement positions, and the average of the obtained measurements is taken as the measured surface average roughness Sa.

(Surface Free Energy of Resin Layer Surface)
The surface free energy of the second main surface of the present film is preferably 25 to 65 mJ/m ^{2, more preferably 25 to 56 mJ/m 2} , even more preferably 25 to 45 mJ/m ² , and particularly preferably 35 to 45 mJ/m ² ^, in terms of improving the winding property during transport and the excellent effect of suppressing unevenness defects during long-term storage. By having the surface free energy of the resin layer surface within the above range, it is possible to suppress impurities such as oligomers generated from the resin substrate from passing through the resin layer and precipitating on the surface of the resin layer surface. As a result, when a laminate film manufactured using the present film is wound into a roll and stored for a long period of time, it is possible to suppress particles derived from impurities such as oligomers generated on the transport surface (second main surface) from adhering to the functional layer surface of the laminate film and causing unevenness defects.
The surface free energy of the resin layer surface can be adjusted, for example, by selecting the non-polyester resin and additives contained in the resin layer.
The surface free energy of the resin layer surface of the present film can be determined by the method described in the Examples section below.

<Physical Properties of First Principal Surface>
(Maximum protrusion height Sp, average surface roughness Sa of the first main surface)
In order to make the functional layer smooth, it is preferable that the first main surface is as smooth as possible. Specifically, the maximum projection height Sp of the first main surface is preferably 1 to 60 nm, more preferably 1 to 50 nm, and even more preferably 1 to 30 nm.
The first main surface has an average surface roughness Sa of preferably 0 to 10 nm, more preferably 0 to 5 nm, and even more preferably 0 to 2 nm.

The maximum projection height Sp and average surface roughness Sa of the first main surface can be adjusted by, for example, selecting the type of resin and the type of additive constituting the resin substrate so as to form a smooth film without substantially including particles in the resin substrate.
The maximum projection height Sp and surface average roughness Sa of the first main surface of the film are obtained by measuring the first main surface under the same conditions as those for measuring the projection height when determining the ratio of the projection height to the major axis of the projection using an optical interferometer (e.g., "Vertscan 3300G Lite" manufactured by Hitachi High-Technologies Corporation), and then analyzing the results using the built-in data analysis software. In measuring the maximum projection height Sp and surface average roughness Sa, measurements are taken five times at different measurement positions on the first main surface, and the average values of the obtained measurements are taken as the respective measured values.

(Surface Free Energy of First Principal Surface)
The surface free energy of the first main surface of the present film is preferably from 25 to 65 mJ/m ² , and more preferably from 30 to 45 mJ/m ² , from the viewpoint of preventing static electricity when the present film is wound up.
The surface free energy of the first main surface can be adjusted by selecting the type of resin forming the resin substrate and additives, etc.

The surface free energy of the first main surface of this film can be measured according to the method for measuring the surface free energy of the second main surface described above.

<Thickness>
The thickness of the present film is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. The lower limit of the thickness is not particularly limited, but from the viewpoint of excellent handleability, it is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more.
The thickness of the film is the arithmetic average of thicknesses measured at five different points in the same direction using a stylus film thickness meter.

[Film manufacturing method]
The method for producing the present film may include a method having a stretching step of stretching a resin substrate and a step of forming a resin layer having protrusions.
The stretching carried out in the stretching step may be uniaxial or biaxial, but is preferably biaxial, i.e., the resulting film is preferably a biaxially oriented film.
The method for producing the film of the present invention may be, for example, the following form.
forming a layer on at least one surface of a resin substrate using a composition containing non-crosslinked resin particles A, a resin B, and a solvent;
and stretching the resin substrate on which the layer is formed while heating it at a temperature Y. The method satisfies

requirements

1 and 2 described below.
According to the above-mentioned manufacturing method, the present film can be obtained. That is, the present film can be obtained, which includes at least a resin substrate and a resin layer, the resin layer has protrusions on its surface, and the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less. In other words, according to the above-mentioned manufacturing method, the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film can be easily adjusted to 0.70 or less.

Below, a representative method for producing the present film will be described in which the stretching step is a biaxial stretching step, and the present film, which is a biaxially oriented film, is obtained. That is, an embodiment in which the resin substrate is a stretched resin substrate will be described, but the method for producing the present film is not limited to the embodiment below. Note that the preferred embodiment of the steps in the above manufacturing method is the same as the preferred embodiment below.

[Method of manufacturing biaxially oriented film]
The method for producing the film of the present invention may include a method having a biaxial stretching step of biaxially stretching an unstretched resin substrate, and a step of forming a resin layer having protrusions.

The biaxial stretching may be simultaneous biaxial stretching in which longitudinal stretching and transverse stretching are performed simultaneously, or sequential biaxial stretching in which longitudinal stretching and transverse stretching are performed in two or more stages. Examples of the order of sequential biaxial stretching include longitudinal stretching and transverse stretching, longitudinal stretching, transverse stretching and longitudinal stretching, longitudinal stretching, longitudinal stretching and transverse stretching, and transverse stretching and longitudinal stretching, with longitudinal stretching and transverse stretching being preferred.

The following describes the first embodiment as an example of the manufacturing method for this film.

First Embodiment
The first embodiment of the method for producing the film includes:
A step of stretching an unstretched resin substrate to obtain a uniaxially stretched resin substrate (hereinafter also referred to as a "longitudinal stretching step");
A step of forming a layer on at least one surface of the uniaxially stretched resin substrate using a composition containing non-crosslinked resin particles A, a resin B, and a solvent (hereinafter also referred to as a "layer forming step");
The method includes a step of stretching the uniaxially stretched resin substrate on which the above-mentioned layer is formed while heating it at a temperature Y (hereinafter, also referred to as a "transverse stretching step"), and satisfies the following

requirements

1 and 2.
Requirement 1: The value obtained by subtracting the glass transition temperature of the non-crosslinked resin particles A from the temperature Y is -20 to 50°C.
Requirement 2: When resin B is present in the composition in the form of particles, the particle diameter of the particulate resin B is smaller than the particle diameter of the non-crosslinked resin particles A.
According to the above-mentioned manufacturing method, the present film, which is a biaxially oriented film, can be obtained. That is, the present film includes at least a biaxially oriented resin substrate and a resin layer, the resin layer has protrusions on its surface, and the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less. In other words, according to the above-mentioned manufacturing method, the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film can be easily adjusted to 0.70 or less.
Each step will be described in detail below.

<Longitudinal Stretching Process>
The resin substrate to be subjected to the longitudinal stretching step is preferably an unstretched resin substrate.
The resin substrate used in the longitudinal stretching step is as described above in the section "Resin Substrate", including preferred embodiments. The unstretched resin substrate can be prepared, for example, by an extrusion molding step described later.

The longitudinal stretching can be carried out, for example, by conveying an unstretched resin substrate in the longitudinal direction while applying tension between two or more pairs of stretching rolls disposed in the conveying direction.
The stretching ratio in the longitudinal stretching step is appropriately set depending on the application, but is preferably 2.0 to 5.0 times, more preferably 2.5 to 4.0 times, and even more preferably 2.8 to 4.0 times.
The stretching speed in the longitudinal stretching step is preferably 800 to 1500%/sec, more preferably 1000 to 1400%/sec, and even more preferably 1200 to 1400%/sec. Here, the "stretching speed" refers to a value obtained by dividing the length Δd of the resin substrate in the conveying direction stretched in one second in the longitudinal stretching step by the length d0 of the resin substrate in the conveying direction before stretching, expressed as a percentage.
In the longitudinal stretching step, it is preferable to heat the unstretched resin substrate. This is because the longitudinal stretching becomes easier by heating. The heating temperature in the longitudinal stretching step can be appropriately set depending on the type of resin constituting the resin substrate. For example, in the case of a polyester substrate, the heating temperature is preferably 70 to 120°C, more preferably 80 to 110°C, and even more preferably 85 to 100°C.
Here, the "temperature" in each step of the manufacturing method according to the present embodiment means the surface temperature of the film-like member measured using a non-contact thermometer (e.g., a radiation thermometer). The surface temperature of the film-like member is determined by measuring the temperature of the center of the film-like member in the width direction five times and calculating the average of the obtained measurement values.

<Layer Forming Step>
In the layer formation process, a layer is formed on the surface of the uniaxially stretched resin substrate obtained in the longitudinal stretching process using a composition containing non-crosslinked resin particles A, resin B, and a solvent (hereinafter also referred to as "composition A1").
In this case, when the resin B contained in the composition A1 is present in particulate form, the above-mentioned requirement 2 is satisfied for the non-crosslinked resin particles A and the resin B. That is, when the resin B is present in particulate form in the composition A1, the particle size of the particulate resin B is smaller than the particle size of the non-crosslinked resin particles A. By satisfying the above requirement 2, it is easy to adjust the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film to the above range on the surface of the layer formed in this embodiment.
When the resin B is present in a particulate form, it is also preferable that the particle diameter of the resin B is Db μm and the particle diameter of the non-crosslinked resin particles A is Da, so that the relationship of the following formula (1) is satisfied.
Formula (1) 7 × Db < Da
It is also preferable that Da and Db satisfy the relationship of the following formula (2).
Formula (2) Da<50×Db
It is also preferable that Da and Db simultaneously satisfy the relationships of formula (1) and formula (2). When at least one of formula (1) and formula (2) is satisfied, the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer of the present film is easily adjusted within the above range on the surface of the layer formed in the present embodiment.
In addition, when the composition A1 contains a plurality of types of non-crosslinked resin particles A and resin B, it is preferable that each combination of non-crosslinked resin particles A and resin B satisfies at least one of the above formula (1) and formula (2).

The layer formed in the layer forming step is the same as the layer described in detail above in the section <Resin layer>, except that it is specified as a resin layer including protrusions formed by organic particles.
The layer forming step may, for example, be a method in which a coating film is formed on the surface of a longitudinally stretched uniaxially stretched resin substrate using the composition A1, and then dried as necessary.

First, a method for forming a layer using composition A1 will be described.
The composition A1 can be prepared, for example, by mixing the non-crosslinked resin particles A, the resin B, a solvent, and additives that are added as necessary.
The non-crosslinked resin particles A are preferably selected from the non-crosslinked resin particles described above in the section "Resin Layer." In particular, the non-crosslinked resin particles A preferably have a glass transition temperature of 70 to 140° C.
Resin B is preferably selected from the non-polyester resins contained as binders described in the section "Resin Layer" above. In particular, Resin B is preferably a resin having an acid group. Resin B preferably has a glass transition temperature of -50 to 105°C.
The glass transition temperatures of the non-crosslinked resin particles A and the resin B can be determined by differential scanning calorimetry, and a detailed measurement method will be described in the Examples section below. When commercially available products are used as the non-crosslinked resin particles A and the resin B, the glass transition temperatures listed as catalog values of the commercially available products may be used.

The average particle size of the non-crosslinked resin particles A contained in the composition A1 is not particularly limited, but is preferably from 1 nm to 3 μm, and more preferably from 10 nm to 2 μm, in terms of better transportability and suppression of transfer marks.
For the average particle size of the non-crosslinked resin particles A, if there is a catalog value of the manufacturer, etc., this can be used.

The non-crosslinked resin particles A contained in the composition A1 may be used alone or in combination of two or more kinds.
When composition A1 contains two or more types of non-crosslinked resin particles A having different particle diameters, the layer to be formed preferably contains at least one type of non-crosslinked resin particles A having an average particle diameter within the above range, and it is more preferable that all of the two or more types of non-crosslinked resin particles A having different particle diameters are non-crosslinked resin particles A having average particle diameters within the above range.

The shape of the non-crosslinked resin particles A is not particularly limited, and examples include rice grain-like, spherical, cubic, spindle-like, scaly, aggregated, and irregular shapes. "Aggregated" refers to a state in which primary particles are aggregated.

The content of non-crosslinked resin particles A in composition A1 is preferably 0.1 to 30% by mass, more preferably 1 to 25% by mass, and even more preferably 1 to 20% by mass, based on the total mass of the components (solid content) other than the solvent in composition A1, from the viewpoints of transportability and coatability.

The solvent includes, for example, water and ethanol.
Composition A1 may contain one type of solvent alone, or may contain two or more types of solvents.
The content of the solvent is preferably from 80 to 99.5% by mass, and more preferably from 90 to 99.0% by mass, based on the total mass of the composition A1.
That is, in the composition A1, the total content of the solid contents is preferably from 0.5 to 20 mass %, and more preferably from 1 to 10 mass %, based on the total mass of the composition A1.

The materials constituting the non-crosslinked resin particles A contained in the composition A1, the resin B (binder) and the additives, including their preferred embodiments, are as described in detail above in the section <Resin Layer>.
With respect to each component other than the solvent and the non-crosslinked resin particles A in composition A1, it is preferable to adjust the content of each component in the coating liquid so that the content of each component relative to the total mass of the solid content of composition A1 is the same as the preferred content of each component relative to the total mass of the resin layer described above.

Composition A1 may contain a crosslinking agent, and preferably composition A1 contains a crosslinking agent.
The crosslinking agent is not particularly limited, and any known crosslinking agent can be used.
Examples of the crosslinking agent include melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds, with oxazoline compounds or carbodiimide compounds being preferred. Commercially available products include, for example, Carbodilite V-02-L2 (manufactured by Nisshinbo Co., Ltd.) and Epocross K-2020E (manufactured by Nippon Shokubai Co., Ltd.). For details of the epoxy compounds, isocyanate compounds, and melamine compounds, reference can be made to the descriptions in [0081] to [0083] of JP 2015-163457 A. The crosslinking agents described in [0082] to [0084] of WO 2017/169844 A can also be preferably used. For the carbodiimide compounds, reference can be made to the descriptions in [0038] to [0040] of JP 2017-087421 A.
For oxazoline-based compounds, carbodiimide-based compounds, and isocyanate-based compounds, the crosslinking agents described in [0074] to [0075] of WO 2018/034294 can also be preferably used.
The content of the crosslinking agent is preferably 0 to 50% by mass based on the total mass of the solid content of the composition A1.

The method for applying composition A1 is not particularly limited, and any known method can be used. Examples of application methods include spray coating, slit coating, roll coating, blade coating, spin coating, bar coating, and dip coating.

In the layer forming step, it is preferable to apply an in-line coating method in which the composition A1 is applied to one surface of the uniaxially stretched resin substrate while conveying the uniaxially stretched resin substrate. By applying the in-line coating method, the heating time of the resin substrate in the manufacturing process is shortened, and no heat history is applied, so that the occurrence of distortion in the manufactured film and laminated film can be suppressed.
In the present embodiment, the longitudinal stretching step is followed by the layer forming step, followed by the transverse stretching step, whereby the uniaxially stretched resin substrate and the formed layer are simultaneously transversely stretched, thereby improving the adhesion between the resin substrate and the formed resin layer.

<Transverse stretching process>
In this embodiment, when a transverse stretching step is performed in which the uniaxially stretched resin substrate having the above-mentioned layer is stretched in the width direction (hereinafter also referred to as “transverse stretching”), the uniaxially stretched resin substrate is heated at a specific temperature Y.
The temperature Y at that time satisfies the above-mentioned requirement 1 between the glass transition temperature of the non-crosslinked resin particles A contained in the composition A1. That is, the value obtained by subtracting the glass transition temperature of the non-crosslinked resin particles A from the temperature Y is −20 to 50° C. By satisfying the requirement 1, the non-crosslinked resin particles A are easily deformed in the transverse stretching direction during transverse stretching, and the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer formed in this embodiment is easily adjusted to the above-mentioned range.
In addition, the uniaxially stretched resin substrate is preferably continuously heated at a temperature Y while being transversely stretched in the transverse stretching step. The temperature Y refers to the surface temperature of the uniaxially stretched resin substrate.

In the transverse stretching step, it is preferable to preheat the uniaxially stretched resin substrate before transverse stretching. By increasing the temperature of the uniaxially stretched resin substrate by preheating, the uniaxially stretched resin substrate can be easily transversely stretched. The preheating temperature in the transverse stretching step can be appropriately set depending on the type of resin constituting the resin substrate. For example, in the case of a polyester substrate, the preheating temperature is preferably 80 to 120°C, more preferably 90 to 110°C.
The stretching ratio in the width direction of the uniaxially stretched resin substrate in the transverse stretching step (transverse stretching ratio) is not particularly limited, but is preferably larger than the stretching ratio in the longitudinal stretching step. The stretching ratio in the transverse stretching step is preferably 3.0 to 6.0 times, more preferably 3.5 to 5.0 times, and even more preferably 3.5 to 4.5 times.
When the transverse stretching step is carried out in a stretching section of a stretching machine, the transverse stretching ratio is calculated from the ratio (L1/L0) of the resin substrate width L1 at the time of discharge from the stretching section to the resin substrate width L0 at the time of entry into the stretching section.
The stretching speed in the transverse stretching step is preferably from 8 to 45%/sec, more preferably from 10 to 30%/sec, and even more preferably from 15 to 20%/sec.

The manufacturing method according to the present embodiment may include other steps in addition to the longitudinal stretching step, the layer forming step, and the transverse stretching step.
The manufacturing method according to the present embodiment may include at least one step selected from the group consisting of an extrusion molding step of extruding a molten resin containing a raw material resin into a film shape to form an unstretched resin substrate, a heat setting step of heating and heat setting the biaxially stretched resin substrate, a heat relaxation step of heating the resin substrate heat-set by the heat setting step at a temperature lower than that of the heat setting step to heat relax the resin substrate heat-relaxed by the heat relaxation step, a cooling step of cooling the resin substrate heat-relaxed by the heat relaxation step, and an expansion step of expanding the heat-relaxed resin substrate in the width direction during the cooling step.
Each step will be described below.

<Extrusion molding process>
The extrusion molding process is a process in which a molten resin containing a raw material resin is extruded into a film shape by an extrusion molding method to form an unstretched resin substrate. The raw material resin is the same as the resin described in the above <Resin substrate> section, and a polyester resin is preferable.

The extrusion molding method is a method in which a molten raw material resin is extruded using an extruder, for example, to mold the raw material resin into a desired shape.
The melt extruded from the extrusion die is cooled to be formed into a film. For example, the melt is brought into contact with a casting roll, and cooled and solidified on the casting roll, whereby the melt can be formed into a film. In cooling the melt, it is preferable to further blow air (preferably cold air) on the melt.

<Heat setting process>
In the manufacturing method according to the present embodiment, it is preferable to carry out a heat setting step as a heat treatment for the resin substrate that has been transversely stretched in the transverse stretching step.
In the heat setting step, the biaxially oriented resin substrate obtained in the transverse stretching step can be heat set by heating. By crystallizing the resin through heat setting, shrinkage of the resin substrate can be suppressed.
The surface temperature (heat setting temperature) of the resin substrate in the heat setting step is not particularly limited and can be appropriately selected depending on the type of resin, but is preferably less than 240° C., more preferably 235° C. or less, and even more preferably 230° C. or less. The lower limit is not particularly limited, but is preferably 190° C. or more, more preferably 200° C. or more, and even more preferably 210° C. or more. When the resin substrate is a polyester substrate, the above temperature range is preferable.
The heating time in the heat setting step is preferably from 5 to 50 seconds, more preferably from 5 to 30 seconds, and even more preferably from 5 to 10 seconds.

<Heat relaxation step>
In the heat relaxation step, the resin substrate heat-fixed in the heat setting step is preferably heat-relaxed by heating at a temperature lower than that in the heat setting step, which can relax residual distortion of the resin substrate.
The surface temperature of the resin substrate in the heat relaxation step (heat relaxation temperature) is preferably at least 5° C. lower than the heat setting temperature, more preferably at least 15° C. lower, even more preferably at least 25° C. lower, and particularly preferably at least 30° C. lower. That is, the heat relaxation temperature is preferably 235° C. or lower, more preferably 225° C. or lower, even more preferably 210° C. or lower, and particularly preferably 200° C. or lower.
The lower limit of the heat relaxation temperature is preferably 100° C. or higher, more preferably 110° C. or higher, and even more preferably 120° C. or higher.

<Cooling process>
The manufacturing method according to the present embodiment preferably includes a cooling step of cooling the thermally relaxed resin substrate.
The cooling rate of the resin substrate in the cooling step is not particularly limited, but in order to reduce thermal shrinkage and impart dimensional stability, the cooling rate of the resin substrate in the cooling step is preferably more than 500° C./min and less than 4000° C./min, more preferably 700 to 3000° C./min, and particularly preferably 1000 to 2500° C./min.

<Expansion process>
It is also preferable that the cooling step includes a step of expanding the thermally relaxed resin substrate in the width direction.
The expansion rate in the width direction of the resin substrate due to the expansion step, i.e., the ratio of the resin substrate width at the end of the cooling step to the resin substrate width before the start of the cooling step, is preferably 0% or more, more preferably 0.001% or more, and even more preferably 0.01% or more.
The upper limit of the expansion rate is not particularly limited, but is preferably 1.3% or less, more preferably 1.2% or less, and even more preferably 1.0% or less.

The production method according to this embodiment may include a winding step of winding up the biaxially oriented resin substrate obtained through the above steps to obtain a roll-shaped biaxially oriented resin substrate.
The conveying speed of the resin substrate in each step other than the longitudinal stretching step in the production method according to the present embodiment is not particularly limited, but is preferably 50 to 200 m/min, more preferably 80 to 150 m/min, in terms of productivity and quality.

The method for producing this film is not particularly limited as long as it is a method for producing a film that includes a resin layer and a resin substrate, in which the resin layer has protrusions on its surface, and in which the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less, and may be a production method other than that of the first embodiment described above.

For example, the film may be produced by co-extruding a molten resin containing the raw resin for forming the unstretched resin substrate and a particle-containing molten resin containing particles and a resin (preferably a non-polyester resin) for forming the resin layer to form a laminate in which the unstretched resin substrate and the resin layer are laminated, and then stretching the laminate (preferably biaxially stretching).

For the manufacturing method of this film, the contents of [0113] to [0169] in the specification of International Publication No. 2020/241692 can be referred to, and the contents are incorporated into the specification of this application.
In the present film manufacturing method specifically described above, a combination of two or more preferred embodiments is a more preferred embodiment.

[Laminated film]
The laminated film of the present invention is a laminated film comprising the present film and a functional layer, and comprises, in this order, a resin layer including protrusions, a resin substrate, and a functional layer. That is, the functional layer is provided on a surface (first main surface) of the present film opposite to the resin layer side of the resin substrate.
While the present film is being transported, a functional layer is placed on one surface of the present film, and the resulting film is then wound up and then unwound, and therefore unevenness defects are unlikely to occur on the surface of the functional layer, so that the laminated film of the present invention is unlikely to have unevenness defects in the functional layer.
The type of the functional layer is not particularly limited, and examples thereof include a decorative layer, a photosensitive resin layer, a magnetic layer, a peeling layer, an adhesive layer, a conductive layer, a refractive index adjustment layer, a hard coat layer, and a visibility layer. A preferred example is one selected from the group consisting of a decorative layer, a photosensitive resin layer, and a peeling layer. It is also preferred that the laminated film is for optical use. Examples of functional layers used in the optical laminated film include a decorative layer, a photosensitive resin layer, an adhesive layer, a refractive index adjustment layer, a hard coat layer, and a visibility layer.
More specific examples of the laminated film include a decorative film in which the functional layer is a decorative layer, a photosensitive transfer film in which the functional layer is a photosensitive resin layer and is used as a support for a dry film resist, a release film in which the functional layer is a release layer (e.g., a protective film for a dry film resist, a release film for producing a ceramic green sheet, a release film for producing a semiconductor process, a release film for a process), an adhesive film in which the functional layer is an adhesive layer (e.g., an adhesive film for producing a semiconductor process), a film for a transparent conductive substrate in which the functional layer is a transparent conductive layer, a transfer film in which the functional layer is an inorganic layer (e.g., a hard coat film in which the inorganic layer is a hard coat layer, a base film in which the inorganic layer is a magnetic layer or a ceramic green sheet), a photosensitive transfer film for forming an etching resist film in which the functional layer is a photosensitive resin layer and a visibility layer, and a photosensitive transfer film for forming a protective film for a touch panel in which the functional layer is a photosensitive resin layer and a refractive index adjustment layer.

There are no particular limitations on the method for laminating the functional layer on the surface of the present film, but it is preferable to form the functional layer by applying a coating liquid containing the material that constitutes the functional layer to the surface (first main surface) of the present film, and from the viewpoint of superior productivity, it is more preferable to apply a coating liquid for the functional layer to the surface of the present film while transporting the present film, and then form the functional layer by heating the coating film.

The laminated film may have layers other than the present film and the functional layer. An example of a layer other than the present film and the functional layer is a base layer containing a binder resin, which is provided for the purpose of improving adhesion between the present film and the functional layer.

When a decorative layer is laminated on the present film as a functional layer, the decorative layer preferably contains a colorant and a binder. When the decorative layer is used for forming a decorative pattern, the decorative layer is preferably a colored photosensitive resin layer. As the colored photosensitive resin layer, a photosensitive resin layer formed from the photosensitive resin composition described in WO 2017/208849 is preferable. The colored photosensitive resin layer is preferably a layer having a pigment as a colorant, and more preferably a layer having, for example, a pigment, a binder polymer, a polyfunctional acrylate, and a photopolymerization initiator.
Preferred examples of the pigment include inorganic pigments (including pigments containing metal particles such as silver) and organic pigments. A decorative film (laminate film) obtained by laminating the present film and a decorative layer can suppress unevenness defects, and therefore can be preferably applied to fields where suppression of color unevenness is required.

When a photosensitive resin layer is laminated on the present film as a functional layer, a photosensitive resin layer containing a photosensitive resin is provided, and a decorative layer, a refractive index adjustment layer, and/or a visibility layer may be further laminated thereon.
The photosensitive resin layer is not particularly limited, but is preferably a negative type. Specifically, the binder polymer, ethylenically unsaturated compound, or photopolymerization initiator described in International Publication No. 2018/105313 is preferably used. The photosensitive resin layer is more preferably a layer having an alkali-soluble acrylic resin having a cyclic structure, a polyfunctional acrylate, and an oxime-based photopolymerization initiator or a bisimidazole-type photopolymerization initiator.

When the photosensitive resin layer is a dry film resist for forming an electrode protective film for a touch panel, it is preferable that a refractive index adjustment layer is laminated separately from the photosensitive resin layer. A preferred form of the refractive index adjustment layer is the second curable transparent resin layer described in JP 2014-108541 A. The refractive index of the refractive index adjustment layer is preferably 1.6 or more, and the refractive index adjustment layer preferably contains metal oxide particles with a high refractive index, such as titanium oxide and zirconium oxide.

If the photosensitive resin layer is a dry film resist for forming an etching resist used to form fine patterns of 50 μm or less, it is preferable that a visibility layer is laminated separately from the photosensitive resin layer. The presence of the visibility layer allows the pattern latent image to be visible in the process of checking it.

When a release layer is laminated as a functional layer on the present film, the release layer contains at least a resin as a release agent.
The resin contained in the release layer is not particularly limited, and examples thereof include silicone resin, fluororesin, alkyd resin, acrylic resin, various waxes, and aliphatic olefin. When the release film is a release film for producing a ceramic green sheet as described below, silicone resin is preferred from the viewpoint of releasability of the ceramic green sheet. It is also preferred that the release layer is a cured layer obtained by curing the components contained in the release layer.
A release film or protective film (laminate film) formed by laminating this film with a release layer can suppress unevenness defects, and is therefore preferably applicable to release films for the production of ceramic green sheets and release films for the production of semiconductors, which have recently required stricter levels of smoothness.

When an adhesive layer is laminated on this film as a functional layer, a known adhesive can be used for the adhesive layer. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Acrylic-based adhesives are preferred because of their excellent optical transparency and adhesive properties.

When a magnetic layer is laminated on the film as a functional layer, the magnetic layer preferably contains ferromagnetic particles and a binder. Preferred examples of the ferromagnetic particles include ferromagnetic particles containing one or more metals selected from the group consisting of iron, cobalt, nickel, aluminum, yttrium, and calcium.

When a hard coat layer is laminated on the present film as a functional layer, a known hard coat layer can be used. The hard coat layer may be an inorganic layer made of an inorganic material, an organic layer made of an organic material, or a hybrid layer containing an inorganic material and an organic material. It is also preferable that the hard coat layer is a cured layer.

[Application]
The film can be used in a variety of applications.
Examples of the laminate film using the present film include the laminate film described above. The laminate film described above can be used for each purpose by a commonly used method.
For example, when the laminated film is a release film, it is preferably used as a release film (carrier film) for producing a ceramic green sheet. The ceramic green sheet produced using the release film can be suitably used for producing a ceramic capacitor, which is required to have a multi-layered internal electrode due to miniaturization and large capacity.
Furthermore, as described above, a release film having the present film may be used as a protective film for a dry film resist, a release film for process manufacturing such as for semiconductor processing, and the like.

The method for producing a ceramic green sheet using the release film is not particularly limited and can be carried out by a known method. For example, the method for producing a ceramic green sheet includes a method of applying a prepared ceramic slurry to the release layer surface of the release film and drying and removing the solvent contained in the ceramic slurry.
The method of applying the ceramic slurry is not particularly limited, and for example, a known method can be applied, such as a method in which a ceramic slurry in which ceramic powder and a binder are dispersed in a solvent is applied by a reverse roll method, and the solvent is removed by heating and drying. The binder is not particularly limited, and examples thereof include polyvinyl butyral. The solvent is also not particularly limited, and examples thereof include ethanol and toluene.

The present invention will be described in further detail below with reference to examples.
The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[Film Preparation]
First, the procedure for producing the films used in the examples will be described.
The physical properties of each film and the methods for measuring the physical properties of the materials used in producing the films will be described later.

Example 1
<Extrusion molding process>
Pellets of polyethylene terephthalate were produced using a titanium compound (citric acid chelate titanium complex, VERTEC AC-420, Johnson Matthey) described in Japanese Patent No. 5575671 as a polymerization catalyst. The obtained pellets were dried until the moisture content was 50 ppm or less, and then charged into the hopper of a twin-screw kneading extruder described in Japanese Patent No. 6049648, and then melted and extruded at 280 ° C. The melt was passed through a filter (hole diameter 3 μm) and then extruded from a die onto a cooling drum at 25 ° C. to obtain an unstretched resin substrate made of polyethylene terephthalate. The extruded melt was brought into close contact with the cooling drum by an electrostatic application method.
The polyethylene terephthalate constituting the unstretched resin substrate had a melting point (Tm) of 258°C and a glass transition temperature (Tg) of 80°C.

<Longitudinal Stretching Process>
The unstretched resin substrate was subjected to a longitudinal stretching process by the following method.
The preheated unstretched resin substrate was stretched in the longitudinal direction at a stretch ratio of 3.4 and a stretching speed of 1300%/sec while maintaining the surface temperature at 90° C., to obtain a uniaxially stretched resin substrate.

<Layer Forming Step>
The following composition A-1 (corresponding to composition A1) was applied to one side of a longitudinally stretched uniaxially stretched resin substrate (polyester substrate) using a bar coater, and the formed coating film was dried with hot air at 100° C. to form a layer on one side of the uniaxially stretched resin substrate. In this process, the coating amount of composition A-1 was adjusted so that a resin layer having a thickness described below would be formed in the finally produced biaxially oriented film.

(Composition A-1)
Composition A-1 was prepared by mixing the components shown below. The prepared composition A-1 was filtered using a filter with a pore size of 6 μm (F20, manufactured by Mahle Filter Systems Co., Ltd.) and subjected to membrane degassing (2x6 Radial Flow Superphobic, manufactured by Polypore Co., Ltd.), and the obtained composition A-1 was applied to one surface of a uniaxially stretched resin substrate.
Resin 1 (urethane resin, Takelac (registered trademark) W-605, manufactured by Mitsui Chemicals, Inc.) solid content concentration 25% by mass aqueous dispersion: 157 parts by mass Anionic hydrocarbon surfactant (Lapisol (registered trademark) A-90, di-2-ethylhexyl sodium sulfosuccinate, manufactured by NOF Corporation) solid content concentration 1% by mass aqueous dilution: 56 parts by mass Particle 1 (non-crosslinked styrene resin particles (styrene copolymer), Nipol (registered trademark) UFN1008, manufactured by Zeon Corporation, average particle size 1.9 μm) solid content concentration 10% by mass aqueous dispersion: 8 parts by mass Water: 779 parts by mass

<Transverse stretching process>
The resin substrate that had been subjected to the longitudinal stretching step and the layer forming step was subjected to transverse stretching under conditions of a stretch ratio of 4.2 times and a stretching speed of 50%/sec while maintaining a surface temperature (temperature Y) of 120°C, thereby obtaining a biaxially oriented film.

The obtained biaxially oriented film was subjected to a heat setting process using a tenter at 227°C for 6 seconds. After the heat setting process, the film was subjected to a heat relaxation process at 190°C under conditions such that the heat relaxation rate Lr was 4%. In the heat relaxation process, the distance between the tenter gripping members gripping both ends of the film (tenter width) was narrowed to reduce the film width compared to the end of the heat setting process. The heat relaxation rate Lr below was calculated from the film width L2 at the end of the heat relaxation process relative to the film width L1 at the start of the heat relaxation process, using the formula Lr = (L1 - L2) / L1 x 100.

Thereafter, the film was cooled at a cooling rate of 1500° C./min. In the cooling step, the film width was expanded so that the expansion rate ΔL was 0.6%. In the cooling step, an expansion step was carried out in which the tenter width was expanded to expand the film width compared to the end of the heat relaxation step.
The cooling rate described below was calculated by dividing the temperature difference ΔT (°C) between the film surface temperature measured when the film was carried into the cooling section and the film surface temperature measured when the film was carried out of the cooling section by the cooling time ta, where ta is the residence time of the film from when it was carried into the cooling section of the stretching machine to when it was carried out.
The expansion rate ΔL was calculated from the film width L3 at the end of the cooling step relative to the film width L2 at the start of the cooling step by the formula ΔL=(L3-L2)/L2×100.

The obtained biaxially oriented film was continuously cut along the conveying direction at positions 20 cm from both ends in the width direction of the film to trim both ends of the film. Next, the film was subjected to extrusion processing (knurling) in the region up to 10 mm in the width direction from both ends, and then the film was wound up under a tension of 40 kg/m.
The thickness of the obtained biaxially oriented film was 31 μm, the thickness of the resin layer was 60 nm, the width was 1.5 m, and the roll length was 7000 m. Protrusions having the shapes shown in Table 1 were formed on the surface of the resin layer.

[Examples 2 to 5]
Instead of the composition A-1 used in the layer formation step, compositions A-2 to A-5, the components of which were changed as shown in the table below, were used, and the stretching temperature (temperature Y) in the transverse stretching step was changed as shown in the table below, but the same procedure as in Example 1 was used to obtain a biaxially oriented film. The amounts of the components of compositions A-2 to A-5 were adjusted so that the solid content concentration was the same as that of each component of composition A-1. Details of the protrusions on the surface of the resin layer are shown in the table below.
The notations in the table are as follows:
Resin 2 (urethane resin, Hydran (registered trademark) AP-40N, manufactured by DIC Corporation)
Resin 3 (urethane resin, Superflex (registered trademark) 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Resin 4 (ester resin, Vylonal (registered trademark) MD-1480, manufactured by Toyobo Co., Ltd., acid value 3 KOHmg/g)

Example 6
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition A-6 below was used instead of the composition A-1 used in the layer formation step. Details of the protrusions on the resin layer surface are shown in the table below.
(Composition A-6)
Composition A-6 was prepared by mixing the components shown below. The prepared composition A-6 was subjected to filtration and membrane degassing in the same manner as composition A-1, and then the obtained composition A-6 was applied to the surface of a uniaxially stretched resin substrate.
Resin 1 (urethane resin, Takelac (registered trademark) W-605, manufactured by Mitsui Chemicals, Inc.) solid content concentration 25% by mass aqueous dispersion: 157 parts by mass Anionic hydrocarbon surfactant (Rapisol (registered trademark) A-90, manufactured by NOF Corporation) solid content concentration 1% by mass aqueous dilution: 36 parts by mass Particle 1 (non-crosslinked styrene resin particles, Nipol (registered trademark) UFN1008, manufactured by Zeon Corporation) solid content concentration 20% by mass aqueous dispersion: 11.2 parts by mass Crosslinker 1 (carbodiimide compound, Carbodilite V-02-L2, manufactured by Nisshinbo Chemical Inc.) solid content 25% by mass aqueous solution: 32.2 parts by mass Water: 622 parts by mass

[Examples 7 to 19]
Instead of the composition A-6 used in the layer formation step, compositions A-7 to A-19 were used, the components of which were changed as shown in the table below, and the stretching temperature (temperature Y) in the transverse stretching step was changed as shown in the table below, but the same procedure as in Example 6 was used to obtain a biaxially oriented film. Note that the amount of each component in compositions A-7 to A-19 was adjusted so that each component had the same solid content concentration as composition A-6. Details of the protrusions on the resin layer surface are shown in the table below.
The notations in the table are as follows:
Resin 5 (copolymer of methyl methacrylate/styrene/2-ethylhexyl acrylate/2-hydroxyethyl methacrylate/acrylic acid = 59:8:26:5:2 (mass ratio), Tg 34°C, acid value 10 mmol/g)
Resin 8 (aqueous dispersion of acid-modified olefin resin particles, ZAIKXEN (registered trademark) NC, manufactured by Sumitomo Seika Chemicals Co., Ltd.)
Particles 2 (non-crosslinked polymethyl methacrylate (PMMA) resin particles, MP1000, manufactured by Soken Chemical & Engineering Co., Ltd., average particle size 0.4 μm)
Particles 3 (non-crosslinked styrene/acrylic copolymer resin particles, MP5000, manufactured by Soken Chemical & Engineering Co., Ltd., average particle size 0.4 μm)
Particles 4 (non-crosslinked styrene/acrylic copolymer resin particles, methyl methacrylate/styrene mass ratio 70/30 copolymer resin particles, average particle size 0.37 μm)
Particles 5 (non-crosslinked acrylic resin particles, methyl methacrylate/ethyl acrylate/acrylic acid copolymer resin particles having a mass ratio of 78/20/2, average particle diameter 0.35 μm)
Crosslinking agent 2 (oxazoline compound, EPOCROS (registered trademark) WS-700, manufactured by Nippon Shokubai Co., Ltd.)

Example 20
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition A-20 was used instead of the composition A-1 used in the layer formation step. Details of the protrusions on the resin layer surface are shown in the table below.
(Composition A-20)
Composition A-20 was prepared by mixing the components shown below. The prepared composition A-19 was subjected to filtration and membrane degassing in the same manner as composition A-1, and the obtained composition A-20 was applied to the surface of a uniaxially stretched resin substrate.
Resin 3 (urethane resin, Superflex (registered trademark) 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) solid content concentration 35% by mass aqueous dispersion: 58 parts by mass Resin 5 (copolymer of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 59: 8: 26: 5: 2 (mass ratio)) solid content concentration 19% by mass aqueous dispersion: 105.8 parts by mass Anionic hydrocarbon surfactant (Lapisol (registered trademark) A-90, manufactured by NOF Corporation) solid content concentration 1% by mass water dilution: 12 parts by mass Particle 1 (non-crosslinked styrene resin particle, Nipol (registered trademark) UFN1008, manufactured by Zeon Corporation) solid content concentration 20% by mass aqueous dispersion: 11.2 parts by mass Crosslinker 2 (oxazoline compound, Epocross (registered trademark) WS-700, manufactured by Nippon Shokubai Co., Ltd.) solid content concentration 25% by mass aqueous solution: 32.2 parts by mass Water: 567 parts by mass

Example 21
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition A-21 below was used instead of the composition A-1 used in the layer formation step. Details of the protrusions on the resin layer surface are shown in the table below.
(Composition A-21)
Composition A-21 was prepared by mixing the components shown below. The prepared composition A-21 was subjected to filtration and membrane degassing in the same manner as composition A-1, and then the obtained composition A-21 was applied to the surface of a uniaxially stretched resin substrate.
Resin 3 (urethane resin, Superflex (registered trademark) 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 35% solids concentration aqueous dispersion: 115 parts by mass Anionic hydrocarbon surfactant (Rapisol (registered trademark) A-90, manufactured by NOF Corporation) 1% solids concentration aqueous dilution: 36 parts by mass Particle 1 (non-crosslinked styrene resin particles, Nipol (registered trademark) UFN1008, manufactured by Zeon Corporation) 20% solids concentration aqueous dispersion: 11.2 parts by mass Particle 2 (PMMA resin particles, MP1000, manufactured by Soken Chemical & Engineering Co., Ltd.) 5% solids concentration aqueous dispersion: 179.2 parts by mass Crosslinker 2 (oxazoline compound, Epocross (registered trademark) WS-700, manufactured by Nippon Shokubai Co., Ltd.) 25% solids concentration aqueous solution: 32.2 parts by mass Water: 622 parts by mass

Example 22
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition A-22 was used instead of the composition A-1 used in the layer formation step. Details of the protrusions on the resin layer surface are shown in the table below.
(Composition A-22)
Composition A-22 was prepared by mixing the components shown below. The prepared composition A-22 was subjected to filtration and membrane degassing in the same manner as composition A-1, and then the obtained composition A-22 was applied to the surface of a uniaxially stretched resin substrate.
Resin 6 (urethane resin, Elastron (registered trademark) H3DF, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with a solid content of 28% by mass in aqueous solution: 72 parts by mass Resin 5 (copolymer of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 59: 8: 26: 5: 2 (mass ratio)) with a solid content of 19% by mass in aqueous dispersion: 105.8 parts by mass Anionic hydrocarbon surfactant (Rapisol (registered trademark) A-90, manufactured by NOF Corporation) with a solid content of 1% by mass in water dilution: 12 Parts by weight Particle 1 (non-crosslinked styrene resin particles, Nipol (registered trademark) UFN1008, manufactured by Zeon Corporation) 20% by weight aqueous dispersion: 11.2 parts by weight Particle 2 (PMMA resin particles, MP1000, manufactured by Soken Chemical & Engineering Co., Ltd.) 5% by weight aqueous dispersion: 134.4 parts by weight Crosslinker 3 (blocked isocyanate compound, Duranate (registered trademark) WM44-L70, manufactured by Asahi Kasei Corporation) 70% by weight dipropylene glycol dimethyl ether solution: 11.5 parts by weight Water: 597 parts by weight The solid content contained in Resin 6 was dissolved in water and did not exist as particles.

Example 23
A biaxially oriented film was obtained in the same manner as in Example 22, except that composition A-23, the components of which were changed as shown in the table below, was used instead of composition A-22 used in the layer formation step. The amount of each component in composition A-23 was adjusted so that the solid content concentration of each component was the same as that of composition A-22. Details of the protrusions on the resin layer surface are shown in the table below.

[Comparative Examples 1 and 2]
Except for using the following composition C-1 or C-2 instead of the composition A-1 used in the layer formation step, and changing the stretching temperature (temperature Y) in the transverse stretching step as shown in the table below, a biaxially oriented film was obtained in the same manner as in Example 1. The coating amount of compositions C-1 and C-2 was adjusted to 6 g/ ^m2 .
In the biaxially oriented films obtained in Comparative Examples 1 and 2, protrusions derived from

particles

4 or 6 were formed on the surface of the resin substrate, but no continuous resin layer was formed. Details of the protrusions on the surface of the biaxially oriented film are shown in the table below.
(Composition C-1)
Particles 4 (non-crosslinked styrene/acrylic copolymer resin particles, methyl methacrylate/styrene copolymer resin particles having a mass ratio of 70/30) in water dispersion with a solid content of 0.4% by mass: 157 parts by mass. Aqueous solution of nonionic surfactant (Naroacty CL95, manufactured by Sanyo Chemical Industries, Ltd.) with a solid content of 1% by mass: 70 parts by mass (Composition C-2).
Particles 6 (non-crosslinked acrylic resin particles, methyl methacrylate/ethyl acrylate/acrylic acid copolymer resin particles in a mass ratio of 78/20/2, average particle diameter 0.12 μm) in water dispersion adjusted to a solid content concentration of 0.4 mass %: 157 parts by mass

Comparative Example 3
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition C-3 shown below was used instead of the composition A-1 used in the layer forming step.
In the biaxially oriented film obtained in Comparative Example 3, a continuous resin layer was formed on the surface of the resin substrate, but no protrusions were formed. When an attempt was made to wind up the biaxially oriented film obtained in Comparative Example 3, a winding shift occurred and it was not possible to wind it up properly, so an evaluation of forming a subsequent functional layer was not performed.
(Composition C-3)
Resin 1 (urethane resin, Takelac (registered trademark) W-605, manufactured by Mitsui Chemicals, Inc.) solid content concentration 25% by mass aqueous dispersion: 81 parts by mass Resin 5 (copolymer of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 59: 8: 26: 5: 2 (mass ratio)) solid content concentration 19% by mass aqueous dispersion: 105.8 parts by mass Anionic hydrocarbon surfactant (Rapisol (registered trademark) A-90, manufactured by NOF Corporation) solid content concentration 1% by mass water dilution: 12 parts by mass Crosslinker 2 (oxazoline compound, Epocross (registered trademark) WS-700, manufactured by Nippon Shokubai Co., Ltd.) solid content concentration 25% by mass aqueous solution: 32.2 parts by mass Water: 622 parts by mass

Comparative Example 4
A biaxially oriented film was obtained in the same manner as in Example 1, except that the composition C-4 below was used instead of the composition A-1 used in the layer formation step, and the stretching temperature (temperature Y) in the transverse stretching step was changed as shown in the table below. Details of the protrusions on the resin layer surface are shown in the table below.
(Composition C-4)
Resin 7 (acrylic resin, methyl methacrylate / stearyl methacrylate / hydroxyethyl methacrylate / methacrylic acid copolymer in a mass ratio of 47 / 26 / 20 / 7) solid content concentration 20 mass% water dispersion: 165 parts by mass Fluorosurfactant (Surflon (registered trademark) S-211, manufactured by AGC Seimi Chemical Co., Ltd.) solid content concentration 1 mass% water dilution: 30 parts by mass Particle 7 (crosslinked acrylic particles, manufactured by Nippon Shokubai Co., Ltd., product name MX100W) solid content concentration 10 mass% water dispersion: 23.7 parts by mass Crosslinker 2 (oxazoline compound, Epocross (registered trademark) WS-700, manufactured by Nippon Shokubai Co., Ltd.) solid content concentration 25 mass% aqueous solution: 56.8 parts by mass Water: 750 parts by mass

Fig. 2 shows an image of the resin layer surface of a biaxially oriented film produced by a method similar to that of Example 1, and Fig. 3 shows an image of the resin layer surface of a biaxially oriented film produced by a method similar to that of Comparative Example 4, observed by SEM.
As shown in Figure 2, the protrusions present on the resin layer surface of the biaxially oriented film produced by a method similar to the Examples are observed to have a small ratio of the height of the protrusion to the long diameter of the protrusion, as described below. On the other hand, from Figure 3, it is observed that the protrusions present on the resin layer surface of the biaxially oriented film produced by a method similar to the Comparative Example have a clear outline, a shape close to a sphere, and a large ratio of the height of the protrusion to the long diameter of the protrusion, as described below.

[Methods for measuring physical properties, etc.]
[Thickness of resin layer]
The thickness of the resin layer was measured by the following procedure.
First, the obtained film was cut with a microtome to expose a cross section along the thickness direction of the film. The exposed film cross section was subjected to a milling treatment with Ar ions to smooth the film cross section, and then Pt was vapor-deposited on the film cross section to obtain a sample for observation. The observation sample was observed with a SEM ("S-4800" manufactured by Hitachi High-Technologies Corporation), and the thickness of the resin layer in the film cross section was measured by the method described above.

[Film thickness]
The thickness was measured by the continuous stylus film thickness meter according to the method described above.

〔Glass-transition temperature〕
The glass transition temperatures (Tg) of the particles and resins used in the examples and comparative examples were measured using a differential scanning calorimeter according to the following procedure.
Specifically, a differential scanning calorimeter (TA Instruments DSC2500) was used, and 5 mg of powder sample was placed in the sealed pan of the differential scanning calorimeter, and measurements were performed in the range of -50 to 300°C at a heating rate of 5°C/min. The temperature modulation conditions were ±0.5°C/min and a period of 60 seconds. The Tg was determined by using the measurement results during the second heating cycle, and the peak value in the curve obtained by first-order differentiation of the reversing heat flow was adopted as the Tg. In addition, when the particles or resin used in the examples and comparative examples were dispersions or solutions, the powder obtained by drying at a high temperature in the range of 100 to 300°C and lower than the thermal decomposition temperature of the resin was used as the powder sample.

[Protrusion height, protrusion long diameter and protrusion short diameter]
The resin layer surface of the film was marked with a felt pen, and then platinum was vapor-deposited to obtain a sample for observation. From the vertical direction of the surface of the sample, an SEM ("S4700", manufactured by Hitachi High-Tech Corporation) was used to image the vicinity of the mark on the resin layer surface at low magnification. Among the protrusions present in the observation area (measurement field of view) of 100 μm × 100 μm, the protrusion with the longest major axis was selected, and the image was taken at an increased magnification to measure the major axis (maximum diameter in the in-plane direction) and minor axis of the protrusion.
Next, the mark portion was measured under the following measurement conditions using an optical interferometer (Vertscan 3300G Lite, manufactured by Hitachi High-Tech Corporation) to confirm the distribution of the protrusions. The distribution was compared with the results of observation using the SEM to identify the protrusions observed using the SEM. After identifying the protrusions, the cross section of the protrusions was observed by two-dimensional analysis, and the height of the protrusions was measured.
From the measured major axis and height of the projections, the ratio of the height of the projections to the identified major axis of the projections was calculated.
(Measurement condition)
Measurement mode: WAVE mode Objective lens: 50x Measurement area: 186μm x 155μm

Using the above method, the major axis of the protrusions and the height corresponding to the protrusions were measured in 10 different observation areas on the resin layer surface of the sample, and the ratio of the height of the protrusions to the major axis of the protrusions was calculated. The arithmetic average value of the ratios obtained for each observation area was adopted as the ratio of the height of the protrusions to the major axis of the protrusions, and is shown in the table as "Ratio A".
The major axis and minor axis of the projections obtained for each observation area, and the arithmetic mean values of the heights corresponding to the projections were adopted as the projection height, major axis, and minor axis, respectively. The ratio of the major axis of the projection to the minor axis of the projection (ratio of major axis of the projection/minor axis of the projection) was calculated from the major axis of the projection and the minor axis of the projection obtained.

[Number of protrusions]
In the sample prepared when measuring the above-mentioned protrusion height, protrusion major axis, and protrusion minor axis, the vicinity of the mark on the resin layer surface was observed using a SEM ("S4700", manufactured by Hitachi High-Tech Corporation). The observation was performed in the observation region (measurement field) of the above-mentioned area, and the number of existing protrusions was counted. The number of protrusions was counted in 10 different observation regions on the resin layer surface, and the arithmetic average value was calculated to obtain the number of protrusions.

[Surface free energy]
The surface free energy of the surface of the film on the resin layer side (second main surface) was measured by the following method.
Using a contact angle meter (DROPMASTER-501, manufactured by Kyowa Interface Science Co., Ltd.), droplets were dropped onto the resin layer surface of the produced film at 25° C., and the contact angle was measured 1 second after the droplets attached to the surface. 2 μL of purified water, 1 μL of methylene iodide, and 1 μL of ethylene glycol were used as droplets, and the surface free energy (unit: mJ/m ² ) was calculated from each measured contact angle by the Kitazaki-Hata method.
The "surface free energy" obtained by the above method is the sum of the polar component and the hydrogen bond component of the surface free energy.

[evaluation]
The laminated films shown below were produced and evaluated. That is, while the films obtained in each of the Examples and Comparative Examples were transported, a functional layer was placed on one surface of the film, and the obtained film (laminated film) was wound up, and then when it was unwound, the surface of the functional layer was evaluated for irregularity defects.
[Preparation and Evaluation of Release Film]
<Preparation of Coating Solution for Forming Release Layer>
With reference to Production Example 1 of JP 2015-195291 A, hexamethylene diisocyanate, dimethylorganopolysiloxane, and dipentaerythritol pentaacrylate (Aronix (registered trademark) M-400, manufactured by Toa Gosei Co., Ltd.) were reacted to synthesize a curable silicone compound (A1). Next, 100 parts by mass of the curable silicone compound (A1) and 5 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (manufactured by IGM Resins B.V., product name "Omnirad 127") as a photopolymerization initiator (B1) were diluted to a solid content concentration of 20% by mass with a mixed solvent of isopropyl alcohol and methyl ethyl ketone (mass ratio 3:1) to obtain a coating liquid for forming a release layer.

<Preparation of Release Film>
The film rolls prepared in each Example and Comparative Example were left for one week under an environment of 25°C temperature and 50% RH. The film rolls were unwound after the standing, and the release layer forming composition prepared in the above procedure was applied to the surface opposite to the surface of the film having the resin layer while being conveyed, and dried at 80°C for one minute. The coating amount was adjusted so that the thickness of the release layer after curing was 1 μm. Thereafter, ultraviolet light was irradiated (irradiation amount: 250 mJ/cm ² ) to cure the release agent layer forming coating liquid to form a release layer, and a release film (laminated film) was obtained.
The obtained release film was evaluated as follows.

(Winding ability)
The obtained release film was transported at a line speed of 100 m/min and tension of 7 kg/m, and was wound around a 6-inch (1 inch = 2.54 cm) diameter ABS (acrylonitrile-butadiene-styrene) resin core while being pressed with a contact roll at a pressure of 30 kg/m, and a release film having a longitudinal length of 7000 m was wound into a roll. The rubber hardness of the contact roll measured using a type A durometer was 60 degrees.
The roll of the released film thus taken up was visually observed, and the winding properties at high speed were evaluated based on the observation results and on the following evaluation criteria.
(Windability Evaluation Criteria)
A: No misalignment was observed at all.
B: A small amount of winding misalignment occurred, but was within the acceptable level.
C: Winding deviation occurred.

(Solvent resistance)
The surface of the resin layer of the obtained release film was rubbed 5 times vertically and 5 times horizontally with a load of 1000 g/ ^cm2 using a cloth soaked in a mixed solution of methyl ethyl ketone and toluene (mass ratio 1:1). Thereafter, the surface of the resin layer was visually observed, and the solvent resistance was evaluated based on the dissolution state of the resin layer. The evaluation criteria are as follows.
A: The resin layer was not dissolved at all.
B: The resin layer was partially dissolved.
C: The resin layer was completely dissolved.

(Unevenness defects (rating 1))
The release film was unwound from the release film roll that had been subjected to the high-speed winding evaluation. The unwound release film was visually inspected for the release layer surface under a three-wavelength fluorescent lamp, and the presence or absence of irregularity defects was confirmed by observing the reflected light of the fluorescent lamp.
(Assessment criteria for unevenness defects)
A: No irregularity defects were found on the surface of the release layer. B: Irregularity defects were found on the surface of the release layer.

(Unevenness Defects (Evaluation 2))
The release film was evaluated for unevenness defects in the same manner as in the unevenness defects (evaluation 1), except that a film roll was used in which the period of leaving in the release film production process was changed to 3 months.
(Assessment criteria for unevenness defects)
A: No irregularity defects were found on the release layer surface. B: 1 to 5 irregularity defects were found on the release layer surface. C: 6 or more irregularity defects were found on the release layer surface.

The evaluation results for the above release films are shown in Table 1.
As described above, the above evaluation was not performed in Comparative Example 3, and therefore the evaluation column is marked with "-".

From the results in Table 1, it was confirmed that when the film contains a resin layer and the ratio of the height of the protrusions to the major axis of the protrusions on the surface of the resin layer (ratio A) is 0.70 or less, unevenness defects in the functional layer can be suppressed.
On the other hand, in Comparative Examples 1 and 2 which did not include a resin layer, and in Comparative Example 4 in which the ratio of the height of the protrusions to the major axis of the protrusions on the resin layer surface was more than 0.70, unevenness defects in the functional layer could not be suppressed.
From a comparison of Examples 1 to 4 and 9 with Example 5, it was confirmed that when the resin layer contains at least one binder selected from the group consisting of acrylic resin, urethane resin, and olefin resin, unevenness defects during long-term storage are further suppressed.
From a comparison of Examples 6 to 22 with Examples 1 to 5, it was confirmed that when the composition used to form the resin layer contains a crosslinking agent, that is, when the resin layer is a crosslinked film, the resin layer has excellent solvent resistance.

[Preparation and evaluation of decorative film]
Using the film produced in Example 22 as a support, a transfer film for decoration (decorative film) was produced by the following procedure.
The thermoplastic (non-photosensitive) resin layer coating liquid described in [0106] of WO 2017/208849 was applied to the surface opposite to the resin layer side of the film produced in Example 22, and dried at 80 ° C. to form a thermoplastic (non-photosensitive) resin layer. Next, the underlayer coating liquid described in [0189] of WO 2021/261412 was applied and dried at 120 ° C. to form a underlayer. On top of that, the photosensitive resin layer forming composition described in [0202] of WO 2021/261412 was applied and dried at 90 ° C. to form a photosensitive resin layer (decorative layer). The thickness of the underlayer was 1.6 μm, and the thickness of the photosensitive resin layer was 2.0 μm.
The decorative transfer film was produced while the film was being transported.

The resulting decorative transfer film was wound up under the same conditions as the release film, and the surface of the unwound decorative transfer film (the surface of the decorative layer opposite the support) was evaluated in the same manner as the release layer (irregularity defects (Evaluation 1)). As a result, no irregularity defects were found in the decorative layer.
In addition, when a decorative pattern was formed using the obtained transfer film for decoration by referring to the description of paragraph [0109] of WO 2017/208849, a pattern with a good shape could be formed.

[Preparation and evaluation of functional material films]
The following ceramic slurry was applied to a thickness of 1 μm on the surface opposite the resin layer of the film produced in Example 22, and dried at 80° C. for 1 minute to produce a film with a ceramic green sheet (functional material film).
The above-mentioned film with the ceramic green sheet was produced while the film was being transported.
(Preparation of ceramic slurry)
A mixture was prepared by mixing 100 parts by mass of barium titanate powder (BaTiO ₃ ; Sakai Chemical Industry Co., Ltd., product name "BT-03"), 8 parts by mass of polyvinyl butyral resin (Sekisui Chemical Co., Ltd., product name "S-LEC (registered trademark) B·K BM-2") as a binder, 4 parts by mass of dioctyl phthalate (Kanto Chemical Co., Ltd., dioctyl phthalate, deer grade 1) as a plasticizer, and 135 parts by mass of a mixture of toluene and ethanol (mass ratio 6:4). Zirconia beads were added to the mixture and dispersed in the barium titanate powder mixture by a ball mill to prepare a dispersion. The zirconia beads were removed from the obtained dispersion to prepare a ceramic slurry.

The resulting film with ceramic green sheet was wound up under the same conditions as the release film, and the ceramic green sheet of the unwound film with ceramic green sheet was then evaluated in the same way as the release layer (irregularity defects (evaluation 1)). As a result, no irregularity defects were found in the ceramic green sheet.

Claims

A film including a resin substrate and a resin layer,
the resin layer has protrusions on its surface,
A film, wherein the ratio of the height of the protrusions to the major axis of the protrusions is 0.70 or less.
The film of claim 1, wherein the protrusions include a non-polyester resin.
The film of claim 1, wherein the protrusions include at least one of an acrylic resin and a styrene resin.
The film according to claim 1, wherein the resin layer is a single coating layer.
The film according to claim 1, wherein the resin layer contains at least one binder selected from the group consisting of acrylic resins, urethane resins, and olefin resins.
The film according to claim 5, wherein the binder comprises a resin having an acid group.
The film according to claim 1, wherein the resin layer is a crosslinked film.
The film according to claim 1, wherein the resin layer has a thickness of 0.01 to 1 μm.
The film according to claim 1 , wherein the number of the protrusions is 50 or more per 10,000 μm 2 area on the surface of the resin layer.
The film of claim 1, wherein the ratio of the major axis of the protrusions to the minor axis of the protrusions is greater than 1.60.
A laminated film comprising the film according to any one of claims 1 to 10 and a functional layer,
The resin layer, the resin substrate, and the functional layer are provided in this order,
The functional layer is one selected from the group consisting of a decorative layer, a photosensitive resin layer, an inorganic layer, and a release layer.
forming a layer on at least one surface of a resin substrate using a composition containing non-crosslinked resin particles A, a resin B, and a solvent;
and stretching the resin substrate on which the layer is formed while heating it at a temperature Y, wherein the following requirement 1 and requirement 2 are satisfied.
Requirement 1: The value obtained by subtracting the glass transition temperature of the non-crosslinked resin particles A from the temperature Y is -20 to 50°C.
Requirement 2: When the resin B is present in the form of particles in the composition, the particle diameter of the particulate resin B is smaller than the particle diameter of the non-crosslinked resin particles A.
The method for producing a film according to claim 12, wherein the resin substrate is a uniaxially stretched resin substrate obtained by stretching an unstretched resin substrate.
The method for producing a film according to claim 12 or 13, wherein the resin B is a resin having an acid group, and the composition further contains a crosslinking agent.
The method for producing a film according to claim 12 or 13, wherein the glass transition temperature of the non-crosslinked resin particles A is 70 to 140°C.
The method for producing a film according to claim 12 or 13, wherein the glass transition temperature of resin B is -50 to 105°C.
The method for producing a film according to claim 12 or 13, wherein, in the composition, when the resin B is present in a particulate form, the particle diameter of the resin B is Db μm and the particle diameter of the non-crosslinked resin particles A is Da, the relationship of formula (1) is satisfied.
Formula (1) 7 × Db < Da