Adhesive for lead film, and method for producing porous imide-based resin film

Abstract

To provide an adhesive for a lead film which can prevent a lead film from being easily peeled from a resin film, and a method for producing a porous imide-based resin film.SOLUTION: An adhesive for a lead film for bonding a lead film to the end of a resin film, in which at least one of the resin film and the lead film has porosity, contains a solvent, and solvent-soluble polyimide that is soluble in the solvent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an adhesive for a lead film and a method for producing a porous imide-based resin film. [Background technology]

[0002] A lead film is attached to the tip of a roll of resin film, and the lead film is used to introduce the resin film into various devices. The lead film is attached to the tip of the resin film via a double-sided adhesive tape, a pressure sensitive adhesive, or an adhesive (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6755200 Summary of the Invention [Problem to be solved by the invention]

[0004] The lead film is required to be firmly attached to the resin film. For example, when the resin film is subjected to a heating treatment or etching treatment, the lead film is exposed to a heating atmosphere or a melting atmosphere when introduced into these devices. In such cases, the lead film may peel off from the resin film, which may cause problems when introducing the resin film into various devices.

[0005] An object of the present invention is to provide an adhesive for a lead film that can prevent the lead film from easily peeling off from the resin film, and a method for producing a porous imide-based resin film. [Means for solving the problem]

[0006] In one aspect of the present invention, there is provided an adhesive for a lead film, in which at least one of a resin film and a lead film is porous, and which is for adhering a lead film to an end of a resin film, the adhesive comprising a solvent and a solvent-soluble polyimide that is soluble in the solvent.

[0007] In one embodiment of the present invention, there is provided a method for producing a porous imide-based resin film, comprising: a first step of applying a coating liquid containing fine particles onto a substrate and then drying the coating liquid to form an unsintered film; a second step of baking the unsintered film to remove the fine particles to form a porous imide-based resin film; and a third step of performing a chemical etching process to dissolve a portion of the porous imide-based resin film, the third step including, prior to the second step, adhering a lead film to the unsintered film using the lead film adhesive described above.

[0008] In one embodiment of the present invention, there is provided a method for producing a porous imide-based resin film, comprising: a first step of applying a coating liquid containing fine particles onto a substrate and then drying the coating liquid to form an unsintered film; a second step of sintering the unsintered film to remove the fine particles to form a porous imide-based resin film; and a third step of performing a chemical etching process to dissolve a portion of the porous imide-based resin film, the method including, prior to the third step, adhering a lead film to the porous imide-based resin film using the above-described lead film adhesive. Effect of the Invention

[0009] According to the aspect of the present invention, the adhesive strength between the resin film and the lead film is increased, and the durability against heat and chemicals is also improved, so that the lead film can be prevented from peeling off from the resin film. In addition, since the adhesive for lead films of the above aspect is used, a porous imide-based resin film can be efficiently produced. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an example of a state in which a resin film and a lead film are bonded with an adhesive according to an embodiment. FIG. [Diagram 2]1 is a cross-sectional view showing a state in which a porous resin film and a lead film are bonded together. FIG. [Diagram 3] 1 is a cross-sectional view showing a state in which a resin film and a porous lead film are bonded to each other. FIG. [Figure 4] 1 is a cross-sectional view showing a state in which a porous resin film and a porous lead film are bonded to each other; [Diagram 5] FIG. 1 is a diagram showing an example of a production system for a porous imide-based resin film. [Figure 6] FIG. 2 is a diagram showing a schematic configuration of an unbaked film forming unit. [Figure 7] FIG. 13 is a diagram showing a state in which a lead film is adhered to an unfired film roll. [Figure 8] FIG. 2 is a diagram showing a schematic configuration of a firing / particle removal unit. [Figure 9] FIG. 13 is a diagram showing a state in which a lead film is adhered to a porous resin film roll. [Figure 10] FIG. 2 is a diagram showing a schematic configuration of an etching unit. [Figure 11] FIG. 2 is a diagram showing a configuration of a slitter. [Figure 12] 1 is a flowchart showing an example of a flow of a method for producing a porous imide-based resin film according to an embodiment. [Figure 13] 1A to 1C are diagrams illustrating an example of a process for producing a porous imide-based resin film. [Figure 14] 1A to 1C are diagrams illustrating an example of a process for producing a porous imide-based resin film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to this embodiment. In addition, in the drawings, in order to make each configuration of the embodiment easier to understand, some parts are enlarged or emphasized, or some parts are simplified, and the actual structure, shape, scale, etc. may differ. In addition, the directions in the drawings will be described using the XYZ coordinate system. The horizontal plane is the XY plane. One direction on the horizontal plane is written as the X direction. On the horizontal plane, the direction perpendicular to the X direction is written as the Y direction. The direction perpendicular to the X direction and the Y direction is written as the Z direction. In addition, in each of the X direction, the Y direction, and the Z direction, the direction indicated by the arrow is the + direction, and the direction opposite to the direction indicated by the arrow is the - direction.

[0012] 1 is a perspective view showing a state in which a resin film and a lead film are bonded with an adhesive according to an embodiment. An adhesive B for the lead film bonds an end (leading end portion) of the resin film R and an end (rear end portion) of the lead film RF. In this embodiment, the adhesive B bonds a surface Ra of the resin film R and a back surface RFb of the lead film RF, but the back surface Rb of the resin film R and a surface RFa of the lead film RF may also be bonded. At least one of the resin film R and the lead film RF may be porous.

[0013] [Resin film] The resin film R may be a single layer film or a laminated film. The resin film R has porosity with a plurality of holes P formed therein, but may not have porosity. The holes P may penetrate from the surface Ra to the back surface Rb of the resin film R. Examples of the material of the resin film R include known resins such as polyethylene terephthalate (PET), polypropylene (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polycarbonate (PC), polystyrene (PS), polyacrylonitrile (PAN), polyethersulfone (PES), polyphenylsulfone (PPSU), polybenzimidazole (PBI), polyamide-imide (PAI), polyamide-based resins, and polyimide-based resins. The resin may also be a copolymer resin, such as an ethylene-vinyl acetate copolymer or an ethylene-methacrylic acid copolymer. The porous imide-based resin film and its manufacturing method will be described later.

[0014] [Lead film] The lead film RF may be a single-layer film or a laminated film, like the resin film R. The lead film RF may be porous with a plurality of holes formed therein, or may not be porous. The holes may penetrate from the front surface RFa to the back surface RFb of the lead film RF. Examples of the material of the lead film RF include the same resin as that of the resin film R described above.

[0015] [glue] The adhesive B contains a solvent-soluble polyimide and a solvent. During bonding, the solvent is removed and the solvent-soluble polyimide solidifies, thereby bonding the resin film R and the lead film RF. The bonding method may involve applying adhesive B to the lead film RF or the resin film R to bond them together, or applying adhesive B to both the lead film RF and the resin film R to bond them together. The adhesive B may be applied using an application device or may be applied manually.

[0016] Examples of the solvent-soluble polyimide include polyetherimide, polyamideimide, and aromatic polyimide. The solvent-soluble polyimide may be a two-component polyimide. For example, the polyetherimide may be p-phenylenediamine-2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride polyimide, 2,2-bis[4-(4-aminophenoxy)phenyl]propane-3,3',4,4'-biphenyltetracarboxylic dianhydride polyimide, and the like. Furthermore, the solvent-soluble polyimide may be a three-component polyimide or a four-component polyimide produced by copolymerizing monomers in any ratio. In particular, polyetherimide is preferred.

[0017] The solvent is preferably an aprotic polar solvent, such as N,N-dimethylacetamide (sometimes called "DMAc" or "dimethylacetamide"), cyclopentanone, methyl benzoate, etc. These may be used alone or in a mixture in any weight ratio. For example, when a mixed solvent of DMAc and cyclopentanone is used, a mixed solvent containing 4% by weight to 100% by weight of DMAc and 0% by weight to 96% by weight of cyclopentanone is preferred. When a mixed solvent of DMAc and methyl benzoate is used, a mixed solvent containing 4% by weight to 100% by weight of DMAc and 0% by weight to 96% by weight of methyl benzoate is preferred.

[0018] By using the adhesive B containing the above-mentioned solvent-soluble polyimide and solvent, separation of the lead film RF and the resin film R becomes difficult. In particular, when manufacturing a porous imide-based resin film, a baking process at 400°C or higher and an etching process in which the film passes through a hydrofluoric acid bath and an alkaline layer are performed. Even in such cases, the lead film RF and the resin film R do not separate, and contamination of the porous imide-based resin film by elution from the adhesive B can be prevented.

[0019] 2 to 4 are diagrams showing an embodiment of the lead film RF and resin film R bonded by adhesive B according to the present invention. Fig. 2 is an enlarged cross-sectional view of a portion where the porous resin film R and the lead film RF are bonded by adhesive B. Holes P1 are formed in the resin film R, and when the front surface Ra of the resin film R and the back surface RFb of the lead film RF are bonded by adhesive B, the adhesive B penetrates into the holes P1 to improve the adhesive strength (anchor effect), thereby firmly bonding the resin film R and the lead film RF.

[0020] Fig. 3 is an enlarged cross-sectional view of a portion where the resin film R and the porous lead film RF are bonded with the adhesive B. Contrary to the embodiment shown in Fig. 2, a hole P2 is formed in the lead film RF, and when the back surface RFb of the lead film RF and the front surface Ra of the resin film R are bonded with the adhesive B, the adhesive B enters the hole P2, improving the adhesive strength, and the lead film RF and the resin film R are firmly bonded together.

[0021] 4 is an enlarged cross-sectional view of a portion where a porous resin film R and a porous lead film RF are bonded with adhesive B. A hole P1 is formed in the resin film R, and a hole P2 is formed in the lead film RF. When the front surface Ra of the resin film R and the back surface RFb of the lead film RF are bonded with adhesive B, the adhesive B penetrates into both the hole P1 and the hole P2, and the adhesive strength is further improved compared to the embodiment shown in FIG. 2 and FIG. 3, and the resin film R and the lead film RF are bonded more firmly.

[0022] FIG. 5 is a diagram showing an example of a porous imide-based resin film manufacturing system 1 according to the present embodiment. As shown in FIG. 5, the manufacturing system 1 manufactures a porous imide-based resin film F. The manufacturing system 1 includes an unbaked film forming unit 2, a baking / particle removing unit 3, an etching unit 4, a slitter 5, and a system control device (not shown). The system control device controls the entire manufacturing system 1. FIG. 6 is a diagram showing a schematic configuration of the unbaked film forming unit 2 of the manufacturing system 1. The unbaked film forming unit 2 applies a coating liquid containing fine particles onto a substrate S and dries the coating liquid to form a strip-shaped unbaked film FA (imide-based resin film). Details of the unbaked film forming unit 2 will be described later.

[0023] In this embodiment, the unfired film forming unit 2, the firing / particle removal unit 3, the etching unit 4, and the slitter 5 are arranged spaced apart from one another. In such a manufacturing system 1, intermediate products being manufactured are wound in a roll shape and transported between the unfired film forming unit 2 and the firing / particle removal unit 3, between the firing / particle removal unit 3 and the etching unit 4, and between the etching unit 4 and the slitter 5, as will be described in detail later. Note that among the unfired film forming unit 2, the firing / particle removal unit 3, and the etching unit 4, units whose processes are performed before and after each other may be provided consecutively.

[0024] FIG. 7 is a diagram showing a state in which the lead film RF is bonded to the unsintered film roll FAr. FIG. 7 shows a state in which the unsintered film FA is unwound from the unsintered film roll FAr using the lead film RF. As shown in FIG. 7, when the unsintered film roll FAr (see FIG. 6) wound in a roll shape in the unsintered film forming unit 2 is fed into the firing / particle removing unit 3, the lead film RF and the unsintered film FA are bonded with the adhesive B, and the unsintered film FA is unwound from the unsintered film roll FAr using the lead film RF and fed into the firing / particle removing unit 3. The adhesive B is applied to one or both of the lead film RF and the unsintered film FA, and then the two are bonded together. The application of the adhesive B may be performed manually by an operator, or may be performed using a device or the like.

[0025] FIG. 8 is a diagram showing a schematic configuration of the firing / particle removal unit 3. As shown in FIG. 8, the firing / particle removal unit 3 fires the unfired film FA to remove particles, thereby forming a band-shaped porous imide-based resin film F (imide-based resin film). In the firing / particle removal unit 3, the porous imide-based resin film F is wound around the winding roller 37r to generate a porous resin film roll Fr (see FIG. 8). The lead film RF may be wound around the winding roller 37r together with the porous imide-based resin film F as it is, or the porous imide-based resin film F may be cut after being guided to the core part of the winding roller 37r. In this case, the porous imide-based resin film F after cutting the lead film RF is wound around the winding roller 37r to generate a porous resin film roll Fr. Details of the firing / particle removal unit 3 will be described later.

[0026] FIG. 9 is a diagram showing a state where the lead film RF is bonded to the porous resin film roll Fr. FIG. 9 shows a state where the porous imide-based resin film F is unwound from the porous resin film roll Fr using the lead film RF. As shown in FIG. 9, when the porous resin film roll Fr wound in a roll shape in the baking / particle removing unit 3 is put into the etching unit 4, the lead film RF and the porous imide-based resin film F are bonded with the adhesive B, and the porous imide-based resin film F is unwound from the porous resin film roll Fr using the lead film RF and put into the etching unit 4. The adhesive B is applied to one or both of the lead film RF and the porous imide-based resin film F, and then the two are bonded together. The adhesive B may be applied manually by an operator, or a device or the like may be used.

[0027] FIG. 10 is a diagram showing a schematic configuration of the etching unit 4. As shown in FIG. 10, the etching unit 4 performs a chemical etching process to dissolve a part of the porous imide-based resin film F. In the etching unit 4, the part of the hole A4 of the porous imide-based resin film F is etched, and a finished roll Fm of the porous imide-based resin film F is generated. The lead film RF may be taken up on the take-up roller 48r together with the porous imide-based resin film F. Also, the lead film RF may be cut after the porous imide-based resin film F is guided to the core part of the take-up roller 48r. After the lead film RF is cut, the porous imide-based resin film F is taken up by the take-up roller 48r to generate a finished roll Fm of the porous imide-based resin film F. Details of the etching unit 4 will be described later.

[0028] Fig. 11 is a diagram showing the configuration of the slitter 5. As shown in Fig. 11, the slitter 5 cuts the porous imide-based resin film F into a strip shape having a predetermined product width. When the porous imide-based resin film F is unwound from the finished product roll Fm and fed into the slitter 5, a lead film RF may be used at the tip of the porous imide-based resin film F before feeding into the slitter 5, or the tip of the porous imide-based resin film F may be held by an operator and fed into the slitter 5 without using a lead film RF. Details of the slitter 5 will be described later.

[0029] [Coating solution] Here, the porous imide-based resin film F produced by the production system 1 will be described. The coating liquid that is the raw material of the porous imide-based resin film F contains a predetermined resin material, fine particles, and a solvent. Examples of the predetermined resin material include polyamic acid, polyimide, polyamideimide, and polyamide. As the solvent, an organic solvent capable of dissolving these resin materials is used.

[0030] The coating liquid is prepared, for example, by mixing a solvent in which fine particles have been previously dispersed with polyamic acid, polyimide, polyamideimide, or polyamide in an arbitrary ratio. Alternatively, the coating liquid may be prepared by polymerizing polyamic acid, polyimide, polyamideimide, or polyamide in a solvent in which fine particles have been previously dispersed. For example, the coating liquid can be produced by polymerizing tetracarboxylic dianhydride and diamine in an organic solvent in which fine particles have been previously dispersed to form polyamic acid, or further imidizing to form polyimide.

[0031] The final viscosity of the coating liquid is preferably 100 to 7000 cP, more preferably 300 to 5000 cP, and even more preferably 500 to 3000 cP. If the viscosity of the coating liquid is within this range, a uniform film can be formed.

[0032] In the coating liquid, when the fine particles and the polyamic acid or polyimide are dried to form an unsintered film FA, if the material of the fine particles is an inorganic material described below, the fine particles and the polyamic acid or polyimide are mixed so that the ratio of the fine particles to the polyimide is 1 to 4 (mass ratio). It is more preferable to set it to 1.2 to 3 (mass ratio). If the material of the fine particles is an organic material described below, the fine particles and the polyamic acid or polyimide are mixed so that the ratio of the fine particles to the polyimide is 0.5 to 2 (mass ratio). It is more preferable to set it to 0.6 to 1.5 (mass ratio). In addition, the fine particles and the polyamic acid or polyimide are mixed so that the volume ratio of the fine particles to the polyimide is 0.6 to 2.7 when the unsintered film FA is formed. It is more preferable to set it to 0.8 to 2 (volume ratio). If the mass ratio or volume ratio of the fine particles / polyimide in the unsintered film FA is equal to or greater than the lower limit, a pore density suitable for a separator can be obtained, and if it is equal to or less than the upper limit, a stable film can be formed without problems such as an increase in viscosity or cracks in the film. The mass ratio is the same as above when the resin material is polyamideimide or polyamide instead of polyamic acid or polyimide.

[0033] Each resin material will be specifically described below. <Polyamic acid> The polyamic acid used in the present embodiment is not particularly limited, and may be any one obtained by polymerizing any tetracarboxylic dianhydride and diamine. The amount of tetracarboxylic dianhydride and diamine used is not particularly limited, but it is preferable to use 0.50 to 1.50 mol of diamine per 1 mol of tetracarboxylic dianhydride, more preferably 0.60 to 1.30 mol, and particularly preferably 0.70 to 1.20 mol.

[0034] The tetracarboxylic dianhydride can be appropriately selected from tetracarboxylic dianhydrides that have been used as a synthetic raw material for polyamic acid. The tetracarboxylic dianhydride may be an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride, but it is preferable to use an aromatic tetracarboxylic dianhydride from the viewpoint of the heat resistance of the resulting polyimide resin. Two or more kinds of tetracarboxylic dianhydrides may be used in combination.

[0035] Specific examples of suitable aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2,6,6-biphenyltetracarboxylic dianhydride, carboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3',4,4'-benzophenone tetracarboxylate carboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4-(p-phenylenedioxy)diphthalic dianhydride, 4,4-(m-phenylenedioxy)diphthalic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Examples of the aliphatic tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, and 1,2,3,4-cyclohexane tetracarboxylic dianhydride.Among these, 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferred in terms of cost, availability, etc. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

[0036] The diamine can be appropriately selected from diamines that have been used as a synthetic raw material for polyamic acid. The diamine may be an aromatic diamine or an aliphatic diamine, but from the viewpoint of the heat resistance of the resulting polyimide resin, an aromatic diamine is preferred. These diamines may be used in combination of two or more kinds.

[0037] Examples of aromatic diamines include diamino compounds having one or about 2 to 10 phenyl groups bonded thereto, specifically phenylenediamine and its derivatives, diaminobiphenyl compounds and their derivatives, diaminodiphenyl compounds and their derivatives, diaminotriphenyl compounds and their derivatives, diaminonaphthalene and its derivatives, aminophenylaminoindan and its derivatives, diaminotetraphenyl compounds and their derivatives, diaminohexaphenyl compounds and their derivatives, and cardo-type fluorenediamine derivatives.

[0038] The phenylenediamines include m-phenylenediamine, p-phenylenediamine, etc., and the phenylenediamine derivatives include diamines to which alkyl groups such as methyl groups and ethyl groups are bonded, such as 2,4-diaminotoluene and 2,4-triphenylenediamine.

[0039] Diaminobiphenyl compounds are compounds in which two aminophenyl groups are bonded together via the phenyl groups, such as 4,4'-diaminobiphenyl and 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl.

[0040] Diaminodiphenyl compounds are compounds in which two aminophenyl groups are bonded to each other via another group. The bond can be an ether bond, a sulfonyl bond, a thioether bond, a bond by an alkylene or its derivative group, an imino bond, an azo bond, a phosphine oxide bond, an amide bond, a ureylene bond, or the like. The alkylene bond has about 1 to 6 carbon atoms, and the derivative group has one or more hydrogen atoms of the alkylene group substituted with a halogen atom or the like.

[0041] Examples of the diaminodiphenyl compound include 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl methane, 3,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 2,2-bis(p-aminophenyl)propane, 2,2'-bis(p-aminophenyl)hexafluoropropane, 4-methyl-2,4-bis(p-aminophenyl)-1-pentene, 4-methyl-2,4-bis(p-aminophenyl) p-aminophenyl)-2-pentene, iminodianiline, 4-methyl-2,4-bis(p-aminophenyl)pentane, bis(p-aminophenyl)phosphine oxide, 4,4'-diaminoazobenzene, 4,4'-diaminodiphenylurea, 4,4'-diaminodiphenylamide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and the like.

[0042] Among these, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, and 4,4'-diaminodiphenyl ether are preferred in view of cost, availability, and the like.

[0043] The diaminotriphenyl compound is a compound in which two aminophenyl groups and one phenylene group are bonded via other groups, and the other groups are selected from the same groups as those of the diaminodiphenyl compound. Examples of the diaminotriphenyl compound include 1,3-bis(m-aminophenoxy)benzene, 1,3-bis(p-aminophenoxy)benzene, and 1,4-bis(p-aminophenoxy)benzene.

[0044] Examples of diaminonaphthalenes include 1,5-diaminonaphthalene and 2,6-diaminonaphthalene.

[0045] Examples of aminophenylaminoindanes include 5 or 6-amino-1-(p-aminophenyl)-1,3,3-trimethylindan.

[0046] Examples of diaminotetraphenyl compounds include 4,4'-bis(p-aminophenoxy)biphenyl, 2,2'-bis[p-(p'-aminophenoxy)phenyl]propane, 2,2'-bis[p-(p'-aminophenoxy)biphenyl]propane, and 2,2'-bis[p-(m-aminophenoxy)phenyl]benzophenone.

[0047] Examples of the cardo-type fluorenediamine derivatives include 9,9-bisanilinefluorene.

[0048] The aliphatic diamine may preferably have, for example, about 2 to 15 carbon atoms, and specific examples thereof include pentamethylenediamine, hexamethylenediamine, and heptamethylenediamine.

[0049] The diamine may be a compound in which a hydrogen atom of the diamine is substituted with at least one substituent selected from the group consisting of a halogen atom, a methyl group, a methoxy group, a cyano group, a phenyl group, and the like.

[0050] There is no particular limitation on the means for producing the polyamic acid used in the present embodiment, and for example, a known method such as a method of reacting an acid and a diamine component in an organic solvent can be used.

[0051] The reaction between tetracarboxylic dianhydride and diamine is usually carried out in an organic solvent. The organic solvent used in the reaction between tetracarboxylic dianhydride and diamine is not particularly limited as long as it can dissolve tetracarboxylic dianhydride and diamine and does not react with tetracarboxylic dianhydride and diamine. The organic solvent can be used alone or in combination of two or more kinds.

[0052] Examples of organic solvents used in the reaction between tetracarboxylic dianhydride and diamine include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, and N,N,N',N'-tetramethylurea; lactone-based polar solvents such as β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, and ε-caprolactone; dimethyl sulfoxide; acetonitrile; fatty acid esters such as ethyl lactate and butyl lactate; ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dioxane, tetrahydrofuran, methyl cellosolve acetate, and ethyl cellosolve acetate; and phenolic solvents such as cresols. These organic solvents can be used alone or in combination of two or more. There is no particular restriction on the amount of organic solvent used, but it is preferable that the content of the produced polyamic acid is 5 to 50 mass %.

[0053] Among these organic solvents, nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, and N,N,N',N'-tetramethylurea are preferred from the viewpoint of the solubility of the produced polyamic acid.

[0054] The polymerization temperature is generally -10 to 120°C, preferably 5 to 30°C. The polymerization time varies depending on the raw material composition used, but is usually 3 to 24 hours. The intrinsic viscosity of the organic solvent solution of polyamic acid obtained under such conditions is preferably in the range of 1,000 to 100,000 cP (centipoise), more preferably 5,000 to 70,000 cP.

[0055] <Polyimide> The polyimide used in this embodiment is not limited in structure or molecular weight, and any known soluble polyimide can be used as long as it is soluble in the organic solvent used in the coating liquid. The polyimide may have a condensable functional group such as a carboxyl group or a functional group that promotes a crosslinking reaction or the like during baking in the side chain.

[0056] In order to make the polyimide soluble in an organic solvent, it is effective to use a monomer for introducing a flexible, bent structure into the main chain, for example, an aliphatic diamine such as ethylenediamine, hexamethylenediamine, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, or 4,4'-diaminodicyclohexylmethane; an aromatic diamine such as 2-methyl-1,4-phenylenediamine, o-tolidine, m-tolidine, 3,3'-dimethoxybenzidine, or 4,4'-diaminobenzanilide; a polyoxyalkylene diamine such as polyoxyethylenediamine, polyoxypropylenediamine, or polyoxybutylenediamine; a polysiloxane diamine; 2,3,3',4'-oxydiphthalic anhydride, 3,4,3',4'-oxydiphthalic anhydride, or 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride; or the like. It is also effective to use a monomer having a functional group that improves the solubility in an organic solvent, for example, a fluorinated diamine such as 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl or 2-trifluoromethyl-1,4-phenylenediamine. Furthermore, in addition to the monomer for improving the solubility of the polyimide, the same monomer as that described in the polyamic acid column above can be used in combination, as long as the solubility is not impaired.

[0057] There is no particular limitation on the means for producing the polyimide soluble in an organic solvent used in this embodiment, and for example, a known method such as chemically imidizing or thermally imidizing a polyamic acid and dissolving it in an organic solvent can be used. Examples of such polyimides include aliphatic polyimides (all aliphatic polyimides) and aromatic polyimides, and aromatic polyimides are preferred.

[0058] <Polyamide-imide> The polyamideimide used in this embodiment is not limited to a specific structure or molecular weight, and any known soluble polyamideimide can be used as long as it is soluble in an organic solvent used in the coating solution. The polyamideimide may have a condensable functional group such as a carboxyl group or a functional group that promotes a crosslinking reaction or the like during baking in the side chain.

[0059] The polyamideimide used in the present embodiment is not particularly limited and may be one obtained by reacting any trimellitic anhydride with a diisocyanate, or one obtained by imidizing a precursor polymer obtained by reacting any reactive derivative of trimellitic anhydride with a diamine.

[0060] Examples of the optional trimellitic anhydride or reactive derivative thereof include trimellitic anhydride, trimellitic anhydride halides such as trimellitic anhydride chloride, and trimellitic anhydride esters.

[0061] Examples of diisocyanates include metaphenylene diisocyanate, p-phenylene diisocyanate, 4,4'-oxybis(phenylisocyanate), 4,4'-diisocyanatediphenylmethane, bis[4-(4-isocyanatephenoxy)phenyl]sulfone, and 2,2'-bis[4-(4-isocyanatephenoxy)phenyl]propane.

[0062] The diamine may be the same as those exemplified in the description of the polyamic acid.

[0063] <Polyamide> As the polyamide, polyamides obtained from dicarboxylic acids and diamines are preferred, and aromatic polyamides are particularly preferred.

[0064] Dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, phthalic acid, isophthalic acid, terephthalic acid, and diphenic acid.

[0065] The diamine may be the same as those exemplified in the description of the polyamic acid.

[0066] <Fine particles> Next, the fine particles will be described. For example, fine particles having a high sphericity and a small particle size distribution index are used. Such fine particles have excellent dispersibility in liquid and do not aggregate with each other. The particle size (average diameter) of the fine particles can be set to, for example, about 5 to 3000 nm. By using such fine particles, the pore size of the porous imide-based resin film F obtained by removing the fine particles in a later process can be made uniform. Therefore, the electric field applied to the separator formed by the porous imide-based resin film F can be made uniform.

[0067] The material of the fine particles is not particularly limited, and any known material can be used as long as it is insoluble in the solvent contained in the coating liquid and can be removed from the porous imide-based resin film F in a later process. For example, inorganic materials include metal oxides such as silica (silicon dioxide), titanium oxide, and alumina (Al2O3). Organic materials include organic polymer fine particles such as high molecular weight olefins (polypropylene, polyethylene, etc.), polystyrene, epoxy resins, cellulose, polyvinyl alcohol, polyvinyl butyral, polyester, polymethyl methacrylate, and polyether. Examples of fine particles include colloidal silica such as (monodisperse) spherical silica particles, calcium carbonate, and the like. In this case, the pore size of the porous imide-based resin film F can be made more uniform.

[0068] The coating liquid may contain various additives such as a release agent, a dispersant, a condensation agent, an imidizing agent, a surfactant, etc., in addition to the predetermined resin material, fine particles, and a solvent, as necessary.

[0069] [Unbaked film forming unit] As shown in FIG. 6, the unsintered film forming unit 2 is provided with a substrate supply section 21, a coating section 22, a drying section 23, a separation section 24, a substrate winding section 25, and a product winding section 26 on the floor surface 8. The substrate supply section 21 unwinds the substrate S extending in a strip shape. Here, the material of the substrate S may be, for example, polyethylene terephthalate (PET), but is not limited to this material and may be a metal material such as stainless steel. The substrate S is set on the supply roller 21r in the state of a substrate roll Sr wound in a roll shape. The substrate supply section 21 unwinds the substrate S from the substrate roll Sr.

[0070] The substrate S is unwound from the substrate roll Sr by being wound up by, for example, a winding roller 25r provided in a substrate winding section 25 described later. The substrate S is fed at a predetermined feed speed to the coating section 22, the drying section 23, and the substrate winding section 25 via a plurality of intermediate rollers. The coating section 22 applies a coating liquid containing fine particles onto the substrate S supplied from the substrate supply section 21. The coating section 22 forms a band-shaped unfired film FA on the substrate S by ejecting a coating liquid prepared in advance, for example, from a nozzle, onto the substrate S fed at a predetermined speed. Here, the configuration for applying the coating liquid onto the substrate S in the coating section 22 is not limited in any way, and various known configurations can be adopted.

[0071] The substrate S on which the unsintered film FA is formed in the coating section 22 is supplied to the drying section 23. The drying section 23 removes the solvent contained in the unsintered film FA. The drying section 23 may be configured to sequentially pass the unsintered film FA through a plurality of drying furnaces having different heating temperatures. By passing through the drying section 23, the solvent is removed from the unsintered film FA on the substrate S. The substrate S and the unsintered film FA that have passed through the drying section 23 are sent to the separation section 24. The separation section 24 separates the substrate S from the unsintered film FA. The substrate S separated in the separation section 24 is sent to the substrate winding section 25. The unsintered film FA separated from the substrate S in the separation section 24 is sent to the product winding section 26.

[0072] The substrate winding section 25 winds the substrate S around a core set on a winding roller 25r. The winding roller 25r is driven to rotate at a preset predetermined number of rotations by a motor (not shown). The product winding section 26 winds the unsintered film FA separated from the substrate S around a core set on a winding roller 26r. The winding roller 26r is driven to rotate at a preset predetermined number of rotations by a motor (not shown). In this manner, an unsintered film roll FAr around which the unsintered film FA is wound is generated. The generated unsintered film roll FAr is transported to the firing / particle removal unit 3, for example, by manual work using an operator or a transport cart, a manipulator, an overhead crane, or the like.

[0073] [Baking / particle removal unit] As shown in FIG. 8, the firing / particle removal unit 3 is provided on the floor surface 8 with an unwinding section 31, a firing furnace 33, a first etching section 34, a cleaning section 35, a drying section 36, and a winding section 37. The unwinding section 31 unwinds the unsintered film FA extending in a strip shape from the unsintered film roll FAr. The unsintered film roll FAr on which the unsintered film FA is wound in a roll shape is set on an unsintered film roll FAr on an unsintered film roll FA. The unsintered film FA is unwound from the unsintered film roll FAr by being wound up, for example, by a winding roller 37r provided in a winding section 37 described later.

[0074] The unsintered film FA is sent at a predetermined feeding speed to the winding section 37 via the firing furnace 33, the first etching section 34, the cleaning section 35, and the drying section 36. In this embodiment, the unsintered film FA is sent at a predetermined feeding speed by, for example, a conveyor 34C (not shown) provided in the first etching section 34 described later in addition to the winding roller 37r.

[0075] The baking furnace 33 bakes the unbaked film FA to imidize the resin material in the coating liquid, and forms a baked film FB containing fine particles. The baking furnace 33 heats the unbaked film FA, for example, in a chamber, to about 120°C to 450°C, for example, with an infrared heater while feeding the unbaked film FA at a predetermined feed rate. The first etching unit 34 performs etching on the baked film FB, removes the fine particles contained in the baked film FB, and forms a porous imide-based resin film F. The first etching unit 34 removes the fine particles by, for example, immersing the baked film FB in an etching solution capable of dissolving or decomposing the fine particles. For example, a hydrofluoric acid solution is used as the etching solution. The first etching unit 34 immerses the baked film FB in an etching tank (not shown) in which an etching solution is stored, while feeding the baked film FB at a predetermined feed rate. As a result, the fine particles contained in the baked film FB are dissolved and removed.

[0076] When the fine particles are removed in this manner, cavities are formed in the areas where the fine particles were present, forming a porous imide-based resin film F. In addition, in the first etching section 34, for example, a conveyor that supports and transports the fired film FB from below may be provided.

[0077] The cleaning section 35 cleans the porous imide-based resin film F formed through the first etching section 34 with a cleaning liquid. The method used for cleaning the porous imide-based resin film F in the cleaning section 35 is not limited to the above-mentioned method. The drying section 36 dries the cleaned porous imide-based resin film F. The drying section 36 volatilizes the cleaning liquid remaining in the porous imide-based resin film F by, for example, heating the porous imide-based resin film F that has passed through the cleaning section 35. Here, at least one of the cleaning section 35 and the drying section 36 may be provided with a conveyor that supports and transports the porous imide-based resin film F from below.

[0078] The winding section 37 winds the porous imide-based resin film F around a core set in the winding roller 37r. The winding roller 37r is driven to rotate at a preset rotation speed by a motor (not shown). In this manner, a porous resin film roll Fr is produced on which the porous imide-based resin film F is wound. The produced porous resin film roll Fr is transported to the etching unit 4, for example, by manual work using a worker or a transport cart, a manipulator, an overhead crane, or the like.

[0079] [Etching unit 4] As shown in FIG. 10, the etching unit 4 includes an unwinding section 41, a second etching section 42, a cleaning section 43, a drying section 44, a re-baking furnace 45, an inspection section 46, a measurement section 47, and a winding section 48 on the floor surface 8. The unwinding section 41 unwinds the porous imide-based resin film F extending in a strip shape from the porous resin film roll Fr. The porous resin film roll Fr on which the porous imide-based resin film F is wound in a roll shape is set on the unwinding roller 41r of the unwinding section 41. The unwinding section 41 unwinds the porous imide-based resin film F from the porous resin film roll Fr. The porous imide-based resin film F is unwound from the porous resin film roll Fr by being wound, for example, by a winding roller 48r provided in the winding section 48 described later.

[0080] The unwound porous imide-based resin film F is fed at a predetermined speed through a second etching section 42, a cleaning section 43, a drying section 44, a re-baking furnace 45, an inspection section 46, and a measurement section 47 to a winding section 48. In this embodiment, the porous imide-based resin film F is fed at a predetermined speed by a winding roller 48r.

[0081] The second etching unit 42 performs chemical etching on the porous imide-based resin film F. When the fine particles contained in the porous imide-based resin film F are removed by the etching process in the first etching unit 34, the fine particles are released, forming minute burr-like irregularities protruding from the periphery of the holes on the surface of the porous imide-based resin film F. The second etching unit 42 performs chemical etching to smooth out the irregularities on the periphery of the holes.

[0082] The etching solution used in the chemical etching in the second etching unit 42 is, for example, an aqueous sodium hydroxide solution or an aqueous TMAH (tetramethylammonium hydroxide) solution. The second etching unit 42 immerses the porous imide-based resin film F in an etching tank (not shown) in which an etching solution is stored, while feeding the porous imide-based resin film F at a predetermined feed speed. As a result, the irregularities around the holes formed in the porous imide-based resin film F are dissolved or softened, and the surface of the porous imide-based resin film F is smoothed. Note that the second etching unit 42 may be provided with a conveyor that supports and transports the porous imide-based resin film F from below.

[0083] The cleaning unit 43 cleans the porous imide-based resin film F that has passed through the second etching unit 42 with a cleaning liquid. The method used for cleaning the porous imide-based resin film F in the cleaning unit 43 is not limited to this configuration. The drying unit 44 dries the cleaned porous imide-based resin film F by various known methods. The drying unit 44 volatilizes the cleaning liquid remaining in the porous imide-based resin film F by, for example, heating the porous imide-based resin film F that has passed through the cleaning unit 43. At least one of the cleaning unit 43 and the drying unit 44 may be provided with a conveyor that supports and transports the porous imide-based resin film F from below.

[0084] The re-baking furnace 45 re-baks the porous imide-based resin film F. The re-baking furnace 45 imidizes the resin components and the like remaining in the porous imide-based resin film F that were not imidized in the above-mentioned baking furnace 33. The re-baking furnace 45 heats the porous imide-based resin film F, for example, to about 300°C to 400°C, for example, with an infrared heater or the like, while feeding the porous imide-based resin film F at a predetermined feed speed, for example, within a chamber.

[0085] The inspection unit 46 inspects the quality of the porous imide-based resin film F that has been through the re-firing furnace 45. The inspection unit 46, for example, inspects the porous imide-based resin film F for foreign matter. The inspection unit 46 may inspect, for example, the occurrence of pinholes in the porous imide-based resin film F. For example, the inspection unit 46 photographs the porous imide-based resin film F with a camera (not shown) while irradiating the porous imide-based resin film F with light from a lighting device (not shown). The inspection unit 46 performs image analysis on the photographed image (video) and determines whether the occurrence of foreign matter and pinholes falls within the inspection criteria. Note that the inspection contents and inspection methods in the inspection unit 46 are not limited to those described above.

[0086] The measuring unit 47 measures the dimensions of the porous imide-based resin film F. For example, the measuring unit 47 measures the film thickness of the porous imide-based resin film F. The measuring unit 47 may measure other dimensions, such as the width of the porous imide-based resin film F. The measuring unit 47 determines whether the measured dimensions of the porous imide-based resin film F are within the dimensional standards. The measurement contents and measurement methods in the measuring unit 47 are also not limited to those described above. In addition, the inspection by the inspection unit 46, the results of the measurement by the measuring unit 47, the inspection standards, and handling in the case where the results are outside the measurement standards are not particularly limited.

[0087] The winding section 48 winds the porous imide-based resin film F around a core set in the winding roller 48r. The winding roller 48r is driven to rotate at a preset rotation speed by a motor (not shown). In this manner, a finished roll Fm is produced in which the porous imide-based resin film F is wound. The produced finished roll Fm is transported to the slitter 5, for example, by manual work using a worker or a transport cart, a manipulator, an overhead crane, or the like.

[0088] [Slitter] 11, the slitter 5 cuts the strip-shaped porous imide-based resin film F that has passed through the etching unit 4 to a predetermined width. The slitter 5 includes an unwinding section 51, a cutting section 52, a product winding section 53, and a surplus winding section 54. An unwinding roller 51r of the unwinding section 51 unwinds the strip-shaped porous imide-based resin film F from the finished product roll Fm.

[0089] The cutting unit 52 cuts the strip-shaped porous imide-based resin film F into multiple strips in the stretching direction (longitudinal direction) of the film. The cutting unit 52 divides the strip-shaped porous imide-based resin film F into multiple pieces in the width direction. The cutting unit 52 cuts the porous imide-based resin film F with a disk-shaped cutter 52c, for example, while feeding the strip-shaped porous imide-based resin film F in the stretching direction of the strip-shaped porous imide-based resin film F.

[0090] At this time, the porous imide-based resin film F is cut out from the widthwise middle part of the porous imide-based resin film F formed with a predetermined width in accordance with the product width. The porous imide-based resin film Fp having the predetermined product width cut out from the widthwise middle part of the porous imide-based resin film F may be one strip or two or more strips. In addition, both ends in the widthwise direction of the porous imide-based resin film F are not used as a product and are cut off from the porous imide-based resin film Fp as surplus porous imide-based resin film Fy.

[0091] The product winding section 53 winds up the porous imide-based resin film Fp having a predetermined product width cut out from the cutting section 52. In this embodiment, for example, two strips of porous imide-based resin film Fp are cut out from the porous imide-based resin film F before cutting. For this reason, two product winding sections 53 are provided. The product winding section 53 winds up the porous imide-based resin film Fp on a core set in a winding roller 53r. The winding roller 53r is driven to rotate at a predetermined rotation speed set in advance by a motor (not shown). In this manner, a product roll Fpr in which the porous imide-based resin film Fp is wound is produced.

[0092] The surplus winding section 54 winds up the surplus porous imide-based resin film Fy cut off from the porous imide-based resin film F before cutting. The surplus winding section 54 winds up the surplus porous imide-based resin film Fy on a core set in the winding roller 54r. The winding roller 54r is driven to rotate at a preset predetermined number of rotations by a motor (not shown). In this way, a surplus roll Fyr is generated around which the surplus porous imide-based resin film Fy is wound. The surplus porous imide-based resin film Fy can be used as a lead film RF. The product roll Fpr and the surplus roll Fyr generated in the slitter 5 in this way are carried out from the slitter 5, for example, by manual work using an operator or a transport cart, a manipulator, an overhead crane, or the like.

[0093] [Method for producing porous imide-based resin film] Next, a method for producing a porous imide-based resin film F using the production system 1 configured as above will be described. Fig. 12 is a diagram showing an example of the flow of a method for producing a porous imide-based resin film F according to an embodiment. Figs. 13 and 14 are diagrams showing an example of a manufacturing process of a porous imide-based resin film. The method for producing a porous imide-based resin film F in this embodiment includes a first step S1 of forming an unbaked film FA, a second step S2 of forming a porous imide-based resin film F, a third step S3 of performing a chemical etching process, and a fourth step S4 of cutting the porous imide-based resin film F into a plurality of strips.

[0094] In the first step S1 of forming the unsintered film FA, a strip-shaped unsintered film FA is formed in the unsintered film forming unit 2 shown in FIG. 6. In the unsintered film forming unit 2, first, the substrate supply unit 21 unrolls the substrate S extending in a strip shape. The leading end of the unsintered substrate S is fixed to a core attached to the winding roller 25r of the substrate winding unit 25 via a plurality of intermediate rollers 28. Next, the winding roller 25r is rotated at a predetermined number of revolutions by a motor (not shown). Then, the substrate supply unit 21 sends out the strip-shaped substrate S in its stretching direction.

[0095] In the coating unit 22, a coating liquid containing a resin material A1 and fine particles A2 is applied onto the substrate S supplied from the substrate supply unit 21. As a result, as shown in FIG. 13(A), a strip-shaped unfired film FA containing the resin material A1 and fine particles A2 is formed on the substrate S. The substrate S on which the unfired film FA has been formed in the coating unit 22 is sequentially dried under predetermined drying conditions in a drying furnace of the drying unit 23. By passing through the drying furnace of the drying unit 23, the solvent is removed from the unfired film FA on the substrate S.

[0096] In the separation section 24, the substrate S that has passed through the drying section 23 is separated from the unsintered film FA. The substrate S separated in the separation section 24 is taken up by the take-up roller 25r of the substrate take-up section 25. As shown in FIG. 13(B), the unsintered film FA separated from the substrate S in the separation section 24 is taken up by the take-up roller 26r of the product take-up section 26. In this manner, an unsintered film roll FAr around which the unsintered film FA is wound is produced. The produced unsintered film roll FAr is removed from the take-up roller 26r and transported to the unwinding section 31 of the firing / particle removal unit 3.

[0097] In the second step S2 of forming the porous imide-based resin film F, the unsintered film FA is sintered in the sintering / particle removing unit 3 shown in FIG. 8 to remove the particles A2, thereby forming a strip-shaped porous imide-based resin film F. In the sintering / particle removing unit 3, first, the unwinding section 31 unwinds the unsintered film FA extending in a strip shape from the unsintered film roll FAr. A lead film RF (see FIG. 7), not shown, is attached to the tip of the unsintered film FA. Then, the lead film is guided to the winding section 37 through the sintering furnace 33, the first etching section 34, the cleaning section 35, and the drying section 36. The tip of the lead film is fixed to a core attached to the winding roller 37r of the winding section 37. Then, the winding roller 37r is rotated at a predetermined number of revolutions by a motor, not shown. Then, the unsintered film FA is sent out from the winding section 37 in its stretching direction. The lead film may be removed after the unfired film FA is guided to the core attached to the winding roller 37r.

[0098] In the firing furnace 33, the unfired film FA is fired to form a fired film FB containing fine particles A2 inside the imidized or high-temperature treated resin layer A3, as shown in FIG. 13(C). In the first etching section 34, the fired film FB is etched to remove the fine particles A2 contained in the fired film FB, forming a porous imide-based resin film F. In the first etching section 34, the fine particles A2 are removed, for example, by immersing the fired film FB in an etching solution capable of dissolving or decomposing the fine particles A2. When the fine particles A2 are removed in this manner, holes A4 are formed in the areas where the fine particles A2 were present, and a porous imide-based resin film F is formed, as shown in FIG. 14(A).

[0099] In the cleaning section 35, the porous imide-based resin film F formed through the first etching section 34 is cleaned with a cleaning liquid. In the drying section 36, the porous imide-based resin film F after cleaning is dried. In the winding section 37, the porous imide-based resin film F that has passed through the drying section 36 is wound around a core set in a winding roller 37r. In this manner, a porous resin film roll Fr is produced around which the porous imide-based resin film F is wound. The produced porous resin film roll Fr is transported to the etching unit 4.

[0100] In the third step S3 of the chemical etching process, a chemical etching process is performed in the etching unit 4 shown in FIG. 10 to dissolve a part of the porous imide-based resin film F. First, the unwinding section 41 unwinds the porous imide-based resin film F extending in a strip shape from the porous resin film roll Fr. A lead film RF (see FIG. 9), not shown, is attached to the tip of the porous imide-based resin film F. Then, the lead film is guided to the winding section 48 through the second etching section 42, the cleaning section 43, the drying section 44, the re-baking furnace 45, the inspection section 46, and the measurement section 47. The tip of the lead film is fixed to a core attached to the winding roller 48r of the winding section 48. Then, the winding roller 48r is rotated at a predetermined number of revolutions by a motor, not shown. Then, the porous imide-based resin film F is sent out from the winding roller 48r in its stretching direction. The lead film may be removed once the porous imide-based resin film F has been guided to the core attached to the winding roller 48r.

[0101] In the second etching section 42, chemical etching is performed on the porous imide-based resin film F sent out from the unwinding section 41. By performing chemical etching, the second etching section 42 smoothes out burr-like irregularities that are generated around the periphery of the hole A4 of the porous imide-based resin film F due to the escape of the fine particles A2 when the fine particles A2 contained in the porous imide-based resin film F are removed by the etching process in the first etching section 34, as shown in FIG.

[0102] In the cleaning section 43, the porous imide-based resin film F that has passed through the second etching section 42 is cleaned with a cleaning solution. In the drying section 44, the porous imide-based resin film F after cleaning is dried. In the re-baking furnace 45, the porous imide-based resin film F that has passed through the drying section 44 is re-baked. In the re-baking furnace 45, the porous imide-based resin film F is heated in a heating section (not shown) while being fed at a predetermined feed rate within a chamber. In the re-baking furnace 45, the porous imide-based resin film F is heated to, for example, about 300°C to 400°C.

[0103] In the inspection section 46, the quality of the porous imide-based resin film F that has passed through the re-firing furnace 45 is inspected. The inspection section 46, for example, inspects the porous imide-based resin film F for foreign matter. Next, in the measurement section 47, the dimensions of the porous imide-based resin film F are measured. The measurement section 47 measures, for example, the film thickness of the porous imide-based resin film F. The porous imide-based resin film F that has passed through the measurement section 47 is wound around a core set on a winding roller 48r in the winding section 48. The winding roller 48r is driven to rotate at a predetermined number of rotations set in advance by a motor (not shown). In this way, a finished product roll Fm in which the porous imide-based resin film F is wound is produced. The produced finished product roll Fm is transported to the slitter 5.

[0104] In the fourth step S4 of cutting the porous imide-based resin film F into multiple strips, the porous imide-based resin film F is cut into multiple strips by a slitter 5 shown in FIG. 11. First, the unwinding section 51 unwinds the porous imide-based resin film F extending in a strip shape from the finished roll Fm. The unwound porous imide-based resin film F is guided to the cutting section 52. In the cutting section 52, the strip-shaped porous imide-based resin film F is cut into multiple strips in the stretching direction of the film. In the cutting section 52, the porous imide-based resin film F is cut by a disk-shaped cutter 52c while feeding the strip-shaped porous imide-based resin film F in its stretching direction.

[0105] The porous imide-based resin film Fp having a predetermined product width cut out from the cutting section 52 is guided to the product winding section 53. In the product winding section 53, the porous imide-based resin film Fp is wound around a core set on a winding roller 53r that is driven to rotate at a predetermined rotation speed. In this manner, a product roll Fpr in which the porous imide-based resin film Fp is wound is produced.

[0106] Furthermore, the surplus porous imide-based resin film Fy separated from the uncut porous imide-based resin film F is guided to the surplus portion winding section 54. The surplus porous imide-based resin film Fy is wound up in the surplus portion winding section 54. In this manner, a surplus roll Fyr around which the surplus porous imide-based resin film Fy is wound is produced. The product roll Fpr and surplus roll Fyr produced in this manner by the slitter 5 are conveyed out of the slitter 5. EXAMPLES

[0107] Next, an embodiment will be described. An unfired film was prepared, and the unfired film and the lead film were bonded with the adhesive according to the present embodiment. The adhesive, unfired film, and lead film used were as follows.

[0108] (glue) A solvent-soluble polyimide, polyetherimide (20 wt % solids in DMAc solution), was diluted four times with cyclopentanone to prepare an adhesive. (Unfired film) The following varnish was used as a coating solution and applied to a polyethylene terephthalate (PET) film substrate using a coating device to form a film. The film was then heated at 90°C in a drying oven to remove the solvents (DMAc and cyclopentanone), and the unsintered composite film was peeled off from the substrate to obtain an unsintered composite film with a thickness of 40 μm. (varnish) A silica dispersion (containing 0.5% by mass of dispersant relative to silica) was added to the polyamic acid solution so that the amount of polyamic acid was 30% by mass and the amount of silica was 70% by mass relative to the total amount of polyamic acid and silica. Organic solvents (1) and (2) were then added so that the solvent composition in the entire varnish was organic solvent (1):organic solvent (2)=90:10, and the mixture was stirred to prepare a varnish. The polyamic acid solution, organic solvent, dispersant, and fine particles used were as follows. Polyamic acid solution: reaction product of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether (solid content 20% by mass (organic solvent: N,N-dimethylacetamide)) Organic solvent (1): N,N-dimethylacetamide (DMAc) Organic solvent (2): Gamma-butyrolactone Dispersant: Polyoxyethylene secondary alkyl ether dispersant Fine particles: Silica with an average particle size of 300 nm (Lead film) The lead film was made of a porous imide resin film.

[0109] (Adhesion between unfired film and lead film) The adhesive was applied to the unfired film, and the unfired film was bonded to the porous imide-based resin film of the lead film, and the solvent of the adhesive was removed to bond the unfired film and the lead film together. Thereafter, in order to evaluate the adhesive strength of the adhesive, the degree of adhesion between the unfired film and the lead film was evaluated.

[0110] (Adhesion evaluation and results) The unfired film was transported while bonded to the lead film, and an evaluation was conducted to see whether the unfired film and lead film could be transported without peeling off through a 400°C baking furnace and a hydrofluoric acid bath (baking / particle removal unit). As a result, there was little volumetric shrinkage in the baking furnace, and the unfired film was not damaged by shrinkage stress. Furthermore, in the hydrofluoric acid bath, the solvent-soluble polyimide was not dissolved by hydrofluoric acid, and the adhesion between the lead film and unfired film was maintained.

[0111] As described above, the adhesive according to the present embodiment firmly bonds the lead film and the resin film, so that the lead film is prevented from peeling off from the resin film even when exposed to a heated atmosphere or immersion in a chemical, and therefore, when manufacturing a porous imide-based resin film, the lead film and the resin film are prevented from breaking, so that the porous imide-based resin film can be manufactured efficiently.

[0112] Although the embodiments and examples have been described above, the technical scope of the present invention is not limited to the above-mentioned embodiments. It is clear to those skilled in the art that various modifications or improvements can be made to the above-mentioned embodiments. Furthermore, forms with such modifications or improvements are also included in the technical scope of the present invention. Furthermore, one or more of the requirements described in the above-mentioned embodiments may be omitted. Furthermore, the requirements described in the above-mentioned embodiments may be combined as appropriate. Furthermore, the execution order of each process shown in this embodiment can be realized in any order, as long as the output of the previous process is not used in the subsequent process. Furthermore, even if the operations in the above-mentioned embodiments are described using "first," "next," "followed," etc. for convenience, it is not essential to carry them out in this order. [Explanation of symbols]

[0113] 2...Unbaked film forming unit, 3...Baking and particle removal unit, 4...Etching unit, 5...Slitter, F, Fp, Fp1, Fp2...Porous imide resin film, FA...Unbaked film, FB...Baked film, S...Substrate, R...Resin film, RF...Lead film, P1, P2...Hole, B...Adhesive

Claims

1. At least one of a resin film and a lead film has porosity, and the lead film is bonded to an end of the resin film, An adhesive for a lead film comprising a solvent and a solvent-soluble polyimide that is soluble in the solvent.

2. The adhesive for lead films according to claim 1 , wherein the resin film is an imide-based resin film.

3. 2. The adhesive for lead films according to claim 1, wherein the lead film is a porous imide-based resin film.

4. 2. The adhesive for lead films according to claim 1, wherein the solvent-soluble polyimide is a polyetherimide.

5. The adhesive for a lead film according to claim 1 , wherein the solvent includes an aprotic polar solvent.

6. The adhesive for lead films according to claim 5 , wherein the aprotic polar solvent is dimethylacetamide.

7. 7. The adhesive for lead films according to claim 6, wherein the solvent is a mixture of dimethylacetamide and cyclopentanone.

8. 8. The adhesive for lead films according to claim 7, wherein the solvent is 4% by weight to less than 100% by weight of dimethylacetamide and 96% by weight or less of cyclopentanone.

9. 7. The adhesive for lead films according to claim 6, wherein the solvent is a mixture of dimethylacetamide and methyl benzoate.

10. 10. The adhesive for lead films according to claim 9, wherein the solvent is 4% to less than 100% by weight of dimethylacetamide and 96% or less by weight of methyl benzoate.

11. A first step of applying a coating liquid containing fine particles onto a substrate and then drying the coating liquid to form an unfired film; a second step of baking the unbaked film to remove the fine particles to form a porous imide-based resin film; A third step of performing a chemical etching treatment to dissolve a part of the porous imide-based resin film, A method for producing a porous imide-based resin film, comprising, prior to the second step, adhering a lead film to the unsintered film using the lead film adhesive according to claim 1 .

12. The method for producing a porous imide-based resin film according to claim 11, further comprising removing the lead film from the fired film produced in the second step.

13. A first step of applying a coating liquid containing fine particles onto a substrate and then drying the coating liquid to form an unfired film; a second step of baking the unbaked film to remove the fine particles to form a porous imide-based resin film; A third step of performing a chemical etching treatment to dissolve a part of the porous imide-based resin film, A method for producing a porous imide-based resin film, comprising, prior to the third step, adhering a lead film to the porous imide-based resin film using an adhesive for lead films according to any one of claims 1 to 4.

14. The method for producing a porous imide-based resin film according to claim 13, further comprising removing the lead film from the porous imide-based resin film that has been subjected to the third step.

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