CN110828748A - Imide resin film production system, imide resin film production method, and separator - Google Patents

Abstract

The present invention relates to an imide resin film production system, an imide resin film production method, and a separator. The object of the present invention is to effectively produce a high-quality imide resin film and reduce the burden of waste liquid treatment in the production process. The solution of the present invention is a production system (SYS1) for producing a porous resin film (F), the production system comprising: a film forming unit (U1) that forms a porous resin film (F) by immersing a fired Film (FB) containing polyamic acid, polyimide, polyamideimide, or polyamide, and microparticles in a first etching solution (Q1) that can dissolve or decompose the microparticles, or by heating to a temperature at which the microparticles can be decomposed, thereby removing the microparticles, wherein porous portions (A4) that penetrate in the film thickness direction are formed in the porous resin film (F); a pre-wetting unit (U2) that supplies a pre-wetting liquid (PW) that does not dissolve the porous resin film (F) to the porous resin film (F) formed by the film forming unit (U1); and a chemical etching unit (U3) that dissolves a portion of the porous resin film (F) supplied with the pre-wetting liquid (PW) using a second etching liquid (Q2) that is different from the first etching liquid (Q1).

Description

Imide resin film production system, imide resin film production method, and separator

Technical Field

The present invention relates to an imide resin film production system, an imide resin film production method, and a separator.

Background

The lithium ion battery is a secondary battery formed in the following structure: a separator is disposed between the positive electrode and the negative electrode immersed in the electrolyte, and direct electrical contact between the positive electrode and the negative electrode is prevented by the separator. During charging, lithium ions move from the positive electrode to the negative electrode through the separator, and during discharging, lithium ions move from the negative electrode to the positive electrode through the separator. In recent years, it has been known to use a separator formed of a porous polyimide film having high heat resistance and high safety as such a separator.

In order to produce the above-mentioned porous polyimide film, the following proposals are made: first, a film of polyamic acid, polyimide, polyamideimide, or polyamide containing microparticles is formed, the microparticles are removed from the film, and then a part of the film is dissolved using a chemical etching solution (for example, see patent document 1).

[ Prior art documents ]

[ patent document ]

[ patent document 1] International publication No. 2015/020101

Disclosure of Invention

[ problems to be solved by the invention ]

The above-described process for producing a polyimide film may include the following steps: a part of the film from which the fine particles have been removed is dissolved by using a chemical etching solution, and a plurality of continuous pores penetrating in the film thickness direction are enlarged. In this case, if the film repels the chemical etching solution, the chemical etching solution hardly permeates into the film, and there is a problem that the film cannot be appropriately chemically etched. In view of this problem, the following method is also considered: an alcohol such as methanol is mixed in advance in the chemical etching solution to increase the affinity of the chemical etching solution with the membrane, so that the chemical etching solution can easily permeate into the membrane. However, in this method, methanol in the mixed solution is volatilized with the lapse of the treatment time, and the concentration of the chemical etching solution is increased. Therefore, there are the following cases: even if the film is immersed at the same time, the film is excessively dissolved and the quality of the film is degraded as the time point (timing) of immersion is increased. In addition, a mixed liquid containing an alcohol as an organic matter has a high BOD value, and thus the mixed liquid is not directly introduced into a sewage as a waste liquid, which increases the burden of waste liquid treatment.

The purpose of the present invention is to provide an imide resin film production system, an imide resin film production method, and a separator, which are capable of efficiently producing a high-quality imide resin film and reducing the burden of waste liquid treatment in the production process.

[ means for solving problems ]

The 1 st aspect of the present invention is a production system for producing a porous imide resin film, the production system including: a film forming unit that forms the porous imide-based resin film by immersing a film containing polyamic acid, polyimide, polyamideimide, or polyamide, and microparticles in a first etching solution that can dissolve or decompose the microparticles, or by heating to a temperature at which the microparticles can be decomposed, thereby removing the microparticles, the porous imide-based resin film having a large number of continuous holes formed therethrough in a film thickness direction; a pre-wetting unit for supplying a pre-wetting liquid that does not dissolve the porous imide resin film to the porous imide resin film formed by the film forming unit; and a chemical etching unit that dissolves a part of the porous imide resin film supplied with the pre-wetting liquid, using a second etching liquid different from the first etching liquid.

The 2 nd aspect of the present invention is a method for producing a porous imide-based resin film, the method including the steps of: forming the porous imide-based resin film by immersing a film containing polyamic acid, polyimide, polyamideimide or polyamide, and fine particles in a first etching solution capable of dissolving or decomposing the fine particles, or by heating to a temperature capable of decomposing the fine particles, thereby removing the fine particles, the porous imide-based resin film having formed therein a large number of continuous pores penetrating therethrough in a film thickness direction; supplying a pre-wetting liquid that does not dissolve the porous imide resin film to the porous imide resin film; and dissolving a part of the porous imide resin film supplied with the pre-wetting liquid using a second etching liquid different from the first etching liquid.

The separator according to claim 3 of the present invention is formed of a porous imide resin film produced by the imide resin film production method according to claim 2.

[ Effect of the invention ]

According to the aspect of the present invention, it is possible to provide an imide resin film production system, an imide resin film production method, and a separator, which can efficiently produce a high-quality imide resin film and reduce the burden of waste liquid treatment in the production process.

Drawings

Fig. 1 is a diagram showing an example of an imide resin film production system according to an embodiment.

FIG. 2 is a diagram showing an example of a film forming unit.

FIG. 3 is a diagram showing a detailed structure of the film forming unit.

Fig. 4 is a diagram showing an example of the pre-wetting unit.

FIG. 5 is a view showing an example of a chemical etching unit.

Fig. 6(a) to (e) are views showing an example of a process for producing a porous resin film in a film forming unit.

Fig. 7 is a diagram showing an example of the pre-wet process in the pre-wet unit.

FIG. 8(a) and (b) are views showing an example of chemical etching treatment in the chemical etching unit.

Fig. 9 is a view showing an example of an imide resin film production system according to a modification.

Fig. 10 is a view showing an example of an imide resin film production system according to a modification.

Fig. 11 is a view showing an example of an imide resin film production system according to a modification.

Fig. 12 is a view showing an example of an imide resin film production system according to a modification.

Fig. 13 is a diagram showing an example of the pre-wetting unit according to a modification.

Fig. 14 is a view showing an example of an imide resin film production system according to a modification.

Fig. 15 is a schematic diagram showing an example of a lithium ion battery.

[ description of reference numerals ]

A4 porous part, F porous resin film, FA unfired to form a film, FB fired to form a film, Q1 first etching solution, Q2 second etching solution, U1 film forming unit, U2, U2A, U2B prewetting unit, U3 chemical etching unit, U4 winding unit, PW prewetting solution, SYS1, SYS2, SYS3, SYS4, SYS5, SYS6 imide resin film manufacturing system, 10 coating unit, 35, 43, 47. a transport section 53, a firing section 20, a removal section 30, 30B, a supply section 45, 52a, a winding section 60, 80, 82, 85, 87, a chemical etching section 51, a storage tank 51a, a waste liquid recovery tank 52B, a discharge section 70, a separator 100, and a lithium ion battery 200.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the directions in the drawings will be described using an XYZ coordinate system. In this XYZ coordinate system, a plane parallel to the horizontal plane is defined as an XY plane. One direction parallel to the XY plane is denoted as an X direction, and a direction orthogonal to the X direction is denoted as a Y direction. In addition, a direction orthogonal to the XY plane is denoted as a Z direction. Here, it is explained that: in the figure, the direction indicated by an arrow is a + direction, and the direction opposite to the arrow is a-direction, for each of the X direction, the Y direction, and the Z direction.

Fig. 1 is a view showing an example of an imide-based resin film production system (hereinafter referred to as a production system) SYS 1. The production system SYS1 shown in fig. 1 is a system for producing a porous resin film F (porous imide resin film). The manufacturing system SYS1 includes a film formation unit U1, a pre-wetting unit U2, and a chemical etching unit U3.

[ film-Forming Unit ]

Fig. 2 is a diagram showing an example of the film forming unit U1. Fig. 3 is a diagram showing the detailed structure of the film forming unit U1. The film forming unit U1 forms a porous resin film F in which a large number of continuous holes penetrating in the film thickness direction are formed. As shown in fig. 2, the film forming unit U1 includes a coating unit 10, a firing unit 20, and a removal unit 30. The coating unit 10 applies a predetermined coating liquid to form an unfired film FA. The coating liquid is as described later. The firing unit 20 fires the unfired film FA to form a fired film FB. The removal means 30 removes fine particles from the fired film FB by immersing the fired film FB in the first etching solution, thereby forming the porous resin film F. The first etching solution is a solution capable of dissolving or decomposing the fine particles.

As shown in fig. 2, the film forming unit U1 is configured, for example, in 2 stages, the coating unit 10 is disposed in the 2 nd layer portion, and the baking unit 20 and the removing unit 30 are disposed in the 1 st layer portion. The firing units 20 and the removal units 30 arranged in the same layer are arranged in parallel in the Y direction, for example, but the present invention is not limited to this configuration, and may be arranged in parallel in the X direction or a combined direction of the X direction and the Y direction, for example.

The hierarchical structure of the film-forming unit U1, the arrangement of the units in each layer, and the like are not limited to the above-described embodiments, and for example, the coating unit 10 and the firing unit 20 may be arranged in the 2 nd layer portion, and the removal unit 30 may be arranged in the 1 st layer portion. In addition, all the cells may be arranged in the same layer. In this case, the cells may be arranged in one row or in a plurality of rows. In addition, all the cells may be arranged in different layers.

In the film forming unit U1, the unfired film FA was formed in a band shape. On the + Y side of the coating unit 10 (forward in the conveying direction of the unfired film FA), a winding section 60 is provided for winding the strip-shaped unfired film FA into a roll. On the-Y side of the firing unit 20 (rearward in the conveying direction of the unfired film FA), a feeding section 70 is provided for feeding the unfired film FA in a roll form to the firing unit 20.

[ coating Unit ]

As shown in fig. 3, the coating unit 10 has a conveying section 11, a first nozzle 12, a second nozzle 13, a drying section 14, and a peeling section 15. The conveying unit 11 includes a conveying substrate (substrate) S, a substrate delivery roller 11a, backup rollers 11b to 11d, a substrate take-up roller 11e, and a delivery roller 11 f.

The transport base S is formed in a belt shape. The conveyed substrate S is fed from the substrate feed roller 11a, stretched over backup rollers 11b to 11d so as to have tension, and wound around a substrate winding roller 11 e. The material of the transport substrate S may be, for example, polyethylene terephthalate (PET), but is not limited to this configuration, and may be a metal material such as stainless steel.

The rollers 11a to 11f are formed in a cylindrical shape, for example, and are arranged in parallel in the X direction. The rollers 11a to 11f are not limited to being arranged parallel to the X direction, and at least 1 roller may be arranged so as to be inclined with respect to the X direction. For example, the rollers 11a to 11f may be arranged in parallel in the Z direction so that the height positions in the Z direction are the same. In this case, the transport base S moves along the horizontal plane (XY plane) while standing upright on the horizontal plane.

The substrate delivery roller 11a is disposed in a state in which the transport substrate S is wound. The backup roller 11b is disposed on the + Z side of the substrate delivery roller 11a and on the-Y side of the substrate delivery roller 11 a. The support roller 11c is disposed on the + Z side of the support roller 11b and is disposed on the + Y side of the support roller 11 b. The arrangement of these 3 rollers (the base material feed roller 11a, the backup rollers 11b, 11c) allows the conveyed base material S to be supported by the surface including the-Y-side end of the backup roller 11 b.

The backup roller 11d is disposed on the + Y side of the backup roller 11c and on the-Z side of the backup roller 11 c. In this case, the arrangement of the three backup rollers 11b to 11d allows the transport base material S to be supported by the surface including the + Z-side end of the backup roller 11 c. The support roller 11d may be disposed at a height position substantially equal to the height position (position in the Z direction) of the support roller 11 c. In this case, the transport base material S is transported from the backup roller 11c toward the backup roller 11d in the + Y direction in a state of being substantially parallel to the XY plane.

The base material take-up roll 11e is disposed on the-Z side of the backup roll 11 d. The conveyed substrate S is conveyed in the-Z direction from the backup roll 11d toward the substrate winding roll 11 e. The carry-out roller 11f is disposed on the + Y side and the-Z side of the back-up roller 11 d. The carry-out roller 11f conveys the unfired film FA formed by the drying section 14 in the + Y direction. The unfired film FA is output to the outside of the coating unit 10 by the output roller 11 f.

The rollers 11a to 11f are not limited to the cylindrical shape, and may be formed with a tapered crown (crown). In this case, it is effective for the flexibility correction of the rollers 11a to 11f, and the transport base material S or the unfired film FA described later can be uniformly brought into contact with the rollers 11a to 11 f. In addition, a radial crown may be formed on each of the rollers 11a to 11 f. In this case, it is effective to prevent the transport substrate S or the unfired film FA from meandering. Further, each of the rollers 11a to 11f may be formed with a concave crown (a portion in which the central portion in the X direction is concavely curved). In this case, since the transport base material S or the unfired film FA can be transported while applying tension in the X direction, it is effective for preventing the occurrence of wrinkles. The following roll may have a configuration having a crown of a conical shape, a radial shape, a concave shape, or the like, as described above.

The first nozzle 12 forms a coating film of a first coating liquid (hereinafter, referred to as a first coating film F1) on the conveyed substrate S. The first nozzle 12 has an ejection port 12a that ejects the first coating liquid. The ejection port 12a is formed so that, for example, the dimension in the longitudinal direction is substantially the same as the dimension in the X direction of the transport substrate S. The first nozzle 12 is disposed at the discharge position P1. The discharge position P1 is a position in the-Y direction with respect to the backup roller 11 b. The first nozzle 12 is disposed obliquely so that the discharge port 12a faces the + Y direction. Therefore, the ejection port 12a faces a portion of the conveyed substrate S supported by the-Y-side end portion of the support roller 11 b. The first nozzle 12 ejects the first coating liquid from the ejection port 12a in the horizontal direction with respect to the transport base S.

The second nozzle 13 forms a coating film of a second coating liquid (hereinafter, referred to as a second coating film F2) on the transport substrate S so as to overlap the first coating film F1. The second nozzle 13 has an ejection port 13a that ejects the second coating liquid. The ejection port 13a is formed so that, for example, the dimension in the longitudinal direction is substantially the same as the dimension in the X direction of the transport substrate S. The second nozzle 13 is disposed at the discharge position P2. The ejection position P2 is a position in the + Z direction with respect to the support roller 11 c. The second nozzle 13 is disposed so that the discharge port 13a faces the-Z direction. Therefore, the ejection port 13a faces a portion of the transport base material S supported by the + Z-side end portion of the support roller 11 c. The second nozzle 13 ejects the second coating liquid from the ejection port 13a in the direction of gravity with respect to the conveyed substrate S.

The first nozzle 12 and the second nozzle 13 may be movable in at least one of the X direction, the Y direction, and the Z direction. The first nozzle 12 and the second nozzle 13 may be provided to be rotatable about an axis parallel to the X direction. The first nozzle 12 and the second nozzle 13 may be provided as follows: the discharge device is disposed at a standby position, not shown, when the application liquid is not discharged, and is moved from the standby position to the discharge positions P1 and P2, respectively, when the application liquid is discharged. Further, a portion for performing the preliminary ejection operation of the first nozzle 12 and the second nozzle 13 may be provided.

The first nozzle 12 and the second nozzle 13 are connected to a coating liquid supply source (not shown) via a connection pipe (not shown) or the like. The first nozzle 12 and the second nozzle 13 may be provided with a holding portion (not shown) for holding a predetermined amount of the coating liquid, for example. In this case, the first nozzle 12 and the second nozzle 13 may further include a temperature control unit for controlling the temperature of the liquid held in the holding unit. The amount of each coating liquid discharged from the first nozzle 12 or the second nozzle 13, or the film thickness of the first coating film F1 or the second coating film F2 can be adjusted by the pressure, the transport speed, the position of each nozzle, the distance between the transport substrate S and the nozzle, and the like of each nozzle, each connection pipe (not shown), or a pump (not shown) connected to a coating liquid supply source (not shown).

The drying unit 14 is disposed on the + Y side of the second nozzle 13 and between the support roller 11c and the support roller 11 d. The drying section 14 dries the two-layer coating film (the first coating film F1 and the second coating film F2) applied to the transport substrate S to form an unfired film FA. The drying section 14 includes a chamber 14a and a heating section 14 b. The chamber 14a accommodates the substrate S and the heating unit 14 b. The heating unit 14b heats the first coating film F1 and the second coating film F2 formed on the transport substrate S. As the heating section 14b, for example, an infrared heater or the like can be used. The heating section 14b heats the coating film at a temperature of about 50 to 100 ℃.

The peeling section 15 is a portion for peeling the unfired film FA from the transport substrate S. In the present embodiment, the peeling of the unfired film FA is performed by manual operation by an operator, but the peeling is not limited to this configuration, and may be performed automatically by using a robot (manipulator) or the like. The unfired film FA peeled off from the transport substrate S is discharged to the outside of the coating unit 10 by the discharge roller 11f, and transported to the winding section 60. Further, the transport substrate S from which the unfired film FA has been peeled is wound around the substrate winding roll 11 e.

On the + Y side of the coating unit 10, an output port 10b for outputting the unfired film FA is provided. The unfired film FA output from the output port 10b is wound by the winding section 60. The winding portion 60 is configured such that a shaft member SF is mounted to a bearing 61. The shaft member SF winds the unfired film FA output from the output port 10b to form a roll R. The shaft member SF is detachably provided to the bearing 61. The shaft member SF is supported rotatably about an axis parallel to the X direction when mounted on the bearing 61. The winding portion 60 includes a drive mechanism (not shown) for rotating the shaft member SF mounted on the bearing 61.

In the winding section 60, the unfired film FA is wound so that the surface of the unfired film FA on the first coating film F1 side is disposed outside. For example, the unfired film FA is wound by rotating the shaft member SF in the counterclockwise direction in fig. 1 by the drive mechanism. When the shaft member SF is removed from the bearing 61 in a state where the winding body R is formed, the winding body R can be moved to another unit. In the present embodiment, the winding section 60 is disposed independently of the coating unit 10, but is not limited to this configuration. For example, the winding section 60 may be disposed inside the coating unit 10. In this case, the roll body R may be formed by winding the unfired film FA from the delivery roll 11f (or from the backup roll 11d) without disposing the delivery port 10b in the coating unit 10.

[ coating solution ]

A coating liquid as a raw material of the porous resin film F will be explained. The coating liquid 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 may be used.

In this embodiment, two kinds of coating liquids (the first coating liquid and the second coating liquid) having different particle contents can be used as the coating liquid. Specifically, the first coating liquid is prepared so that the content of fine particles in the first coating liquid is higher than that in the second coating liquid. As a result, the strength and flexibility of the unfired film FA, the fired film FB, and the porous resin film F can be ensured. Further, by providing the layer having a low fine particle content, the production cost of the porous resin film F can be reduced.

For example, in the first coating liquid, the resin material and the fine particles are contained so that the volume ratio is 19: 81 to 45: 65. In addition, in the second coating liquid, the resin material and the microparticles are contained in a volume ratio of 20: 80 to 50: 50. However, the volume ratio is set so that the content of fine particles of the first coating liquid is higher than the content of fine particles of the second coating liquid. The volume of each resin material may be determined by multiplying the mass of each resin material by the specific gravity thereof.

In the above case, for example, when the total volume of the first coating liquid is 100, the particles are uniformly dispersed when the volume of the fine particles is 65 or more, and the particles are dispersed without being aggregated with each other when the volume of the fine particles is 81 or less. Therefore, the holes can be uniformly formed in the porous resin film F. When the volume ratio of the fine particles is within this range, the releasability when the film is formed from the unfired film FA can be ensured.

For example, when the total volume of the second coating liquid is 100, the fine particles are uniformly dispersed when the volume of the fine particles is 50 or more, and when the volume of the fine particles is 80 or less, the fine particles are not aggregated and cracks or the like are not generated on the surface, so that the porous resin film F having good electrical characteristics can be stably formed.

The two coating liquids can be prepared by mixing a solvent in which fine particles are dispersed in advance and a polyamic acid, a polyimide, a polyamideimide, or a polyamide at an arbitrary ratio, for example. Further, the polyamide acid, the polyimide, the polyamideimide, or the polyamide may be prepared by polymerizing a polyamic acid, a polyimide, a polyamideimide, or a polyamide in a solvent in which fine particles are dispersed in advance. For example, it can be produced by: the polyimide is obtained by polymerizing tetracarboxylic dianhydride and diamine in an organic solvent in which fine particles are dispersed in advance to form polyamic acid, or further imidizing the polyamic acid.

The viscosity of the coating liquid is preferably set to 300 to 2000cP, more preferably 400 to 1500cP, and still more preferably 600 to 1200 cP. When the viscosity of the coating liquid is within this range, a uniform film can be formed.

In the case where the coating liquid is prepared by drying the fine particles and polyamic acid or polyimide to form the unfired film FA, when the fine particles are made of an inorganic material as described below, the fine particles and polyamic acid or polyimide are preferably mixed so that the ratio of fine particles/polyimide is 2 to 6 (mass ratio). More preferably 3 to 5 (mass ratio). When the material of the fine particles is an organic material described below, the fine particles are preferably mixed with polyamic acid or polyimide so that the ratio of fine particles/polyimide is 1 to 3.5 (mass ratio). More preferably 1.2 to 3 (mass ratio). In addition, when the non-fired film FA is produced, it is preferable to mix the fine particles with the polyamic acid or the polyimide so that the volume ratio of the fine particles to the polyimide is 1.5 to 4.5. More preferably 1.8 to 3 (volume ratio). When the mass ratio or volume ratio of the fine particles/polyimide is not less than the lower limit value in the production of the unfired film FA, pores having an appropriate density can be obtained as the separator, and when the mass ratio or volume ratio is not more than the upper limit value, the film can be stably formed without causing problems such as an increase in viscosity and cracks in the film. In the case where the resin material is polyamideimide or polyamide instead of polyamic acid or polyimide, the mass ratio is also the same as described above.

Hereinafter, each resin material will be specifically described.

< Polyamic acid >

The polyamic acid used in the present embodiment may be obtained by polymerizing any tetracarboxylic dianhydride and diamine, without particular limitation. The amount of the tetracarboxylic dianhydride and the diamine used is not particularly limited, but is preferably 0.50 to 1.50 mol, more preferably 0.60 to 1.30 mol, and particularly preferably 0.70 to 1.20 mol, based on 1 mol of the tetracarboxylic dianhydride.

The tetracarboxylic dianhydride can be appropriately selected from tetracarboxylic dianhydrides conventionally used as a raw material for synthesizing polyamic acid. The tetracarboxylic dianhydride may be an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride, but the aromatic tetracarboxylic dianhydride is preferably used from the viewpoint of the heat resistance of the polyimide resin to be obtained. The tetracarboxylic dianhydride may be used in combination of two or more.

Suitable specific examples of the aromatic tetracarboxylic acid dianhydride 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 acid dianhydride, 2, 3, 3 ', 4' -biphenyltetracarboxylic acid dianhydride, 2, 6, 6-biphenyltetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenyl) -1, 1, 1, 3, 3, 3-hexafluoropropane dianhydride, 2-bis (2, 3-dicarboxyphenyl) -1, 1, 1, 3, 3, 3-hexafluoropropane dianhydride, 3, 3 ', 4, 4' -benzophenone tetracarboxylic dianhydride, bis (3, 4-dicarboxyphenyl) ether dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 2 ', 3, 3' -benzophenone tetracarboxylic dianhydride, 4, 4- (p-phenylenedioxy) diphthalic dianhydride, 4, 4- (m-phenylenedioxy) diphthalic dianhydride, 1, 2, 5, 6-naphthalene tetracarboxylic dianhydride, 1, 4, 5, 8-naphthalene tetracarboxylic dianhydride, 2, 3, 6, 7-naphthalene tetracarboxylic dianhydride, 1, 2, 3, 4-benzene tetracarboxylic dianhydride, 3, 4, 9, 10-perylene tetracarboxylic dianhydride, 2, 3, 6, 7-anthracene tetracarboxylic dianhydride, 1, 2, 7, 8-phenanthrene tetracarboxylic dianhydride, 1, 3, 4, 3, 6, 7-anthracene tetracarboxylic dianhydride, 1, 2, 7, 8-benzene tetracarboxylic dianhydride, 9, 9-bisphthalic anhydride fluorene, 3 ', 4, 4' -diphenylsulfone tetracarboxylic dianhydride, and the like. Examples of the aliphatic tetracarboxylic acid dianhydride include ethylene tetracarboxylic acid dianhydride, butane tetracarboxylic acid dianhydride, cyclopentane tetracarboxylic acid dianhydride, cyclohexane tetracarboxylic acid dianhydride, 1, 2, 4, 5-cyclohexane tetracarboxylic acid dianhydride, and 1, 2, 3, 4-cyclohexane tetracarboxylic acid dianhydride. Among them, 3 ', 4, 4' -biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable from the viewpoint of cost, availability, and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

The diamine can be appropriately selected from diamines that have been conventionally used as a raw material for synthesizing polyamic acid. The diamine may be an aromatic diamine or an aliphatic diamine, but an aromatic diamine is preferable from the viewpoint of heat resistance of the polyimide resin to be obtained. These diamines may be used in combination of two or more.

The aromatic diamine includes a diamino compound to which about 1 or about 2 to 10 phenyl groups are bonded. Specifically, the compound is phenylenediamine and its derivatives, diaminobiphenyl compounds and their derivatives, diaminodiphenyl compounds and their derivatives, diaminotriphenyl compounds and their derivatives, diaminonaphthalene and its derivatives, aminophenylaminoindane and its derivatives, diaminotetraphenyl compounds and their derivatives, diaminohexaphenyl compounds and their derivatives, and Cardo-type fluorenediamine derivatives.

The phenylenediamine is, for example, m-phenylenediamine or p-phenylenediamine, and the phenylenediamine derivative is a diamine to which an alkyl group such as a methyl group or an ethyl group is bonded, for example, 2, 4-diaminotoluene or 2, 4-triphenylenediamine (2, 4-triphenylenediamine).

The diaminobiphenyl compound is a compound in which 2 aminophenyl groups are bonded to each other with a phenyl group. Examples thereof include 4, 4 ' -diaminobiphenyl, 4 ' -diamino-2, 2 ' -bis (trifluoromethyl) biphenyl, and the like.

The diaminodiphenyl compound is a compound in which phenyl groups of 2 aminophenyl groups are bonded to each other through other groups. The bond is an ether bond, a sulfonyl bond, a thioether bond, a bond based on an alkylene group or a derivative thereof, an imino bond, an azo bond, a phosphine oxide bond, an amide bond, a urethane (ureylene) bond or the like. The alkylene bond is a bond having about 1 to 6 carbon atoms, and the derivative group thereof is a group in which 1 or more hydrogen atoms in the alkylene group are substituted with a halogen atom or the like.

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

Among them, p-phenylenediamine, m-phenylenediamine, 2, 4-diaminotoluene, and 4, 4' -diaminodiphenyl ether are preferable from the viewpoint of cost, availability, and the like.

The diaminotriphenyl compound is a compound in which 2 aminophenyl groups and 1 phenylene group are bonded to each other through another group, and the other group may be selected from the same groups as those described for the diaminodiphenyl compound. Examples of the diaminotriphenyl compound include 1, 3-bis (m-aminophenoxy) benzene, 1, 3-bis (p-aminophenoxy) benzene, 1, 4-bis (p-aminophenoxy) benzene, and the like.

Examples of diaminonaphthalene include 1, 5-diaminonaphthalene and 2, 6-diaminonaphthalene.

Examples of aminophenylaminoindanes include 5-amino-1- (p-aminophenyl) -1, 3, 3-trimethylindane and 6-amino-1- (p-aminophenyl) -1, 3, 3-trimethylindane.

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

Examples of the Cardo-type fluorenediamine derivative include 9, 9-bisanilinofluorene and the like.

The aliphatic diamine may be, for example, an aliphatic diamine having about 2 to 15 carbon atoms, and specific examples thereof include pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, and the like.

The hydrogen atom of these diamines may be substituted with at least 1 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.

The method for producing the polyamic acid used in the present embodiment is not particularly limited, and for example, a known method such as a method of reacting an acid or a diamine component in an organic solvent can be used.

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

Examples of the organic solvent used in the reaction of the tetracarboxylic dianhydride and the diamine include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, N-dimethylacetamide, N-diethylacetamide, N-dimethylformamide, N-diethylformamide, N-methylcaprolactam, N' -tetramethylurea, lactone polar solvents such as β -propiolactone, γ -butyrolactone, γ -valerolactone, δ -valerolactone, γ -caprolactone, and ∈ -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 phenol solvents such as cresols, and these organic solvents can be used alone or in combination of 2 or more.

Among these organic solvents, nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, N-dimethylacetamide, N-diethylacetamide, N-dimethylformamide, N-diethylformamide, N-methylcaprolactam, and N, N' -tetramethylurea are preferable from the viewpoint of solubility of the resulting polyamic acid.

The polymerization temperature is generally-10 to 120 ℃ and preferably 5 to 30 ℃. The polymerization time varies depending on the composition of the raw material used, but is usually 3 to 24Hr (hours). The inherent viscosity of the organic solvent solution of polyamic acid obtained under such conditions is preferably in the range of 1000 to 10 ten thousand cP (centipoise), and more preferably in the range of 5000 to 7 ten thousand cP.

< polyimide >

The polyimide used in the present embodiment is not limited in structure or molecular weight as long as it is soluble in an organic solvent used in the coating liquid, and known polyimides can be used. The polyimide may have a functional group capable of condensation, such as a carboxyl group, in a side chain thereof, or a functional group capable of promoting a crosslinking reaction during firing.

In order to form a polyimide soluble in an organic solvent, a monomer for introducing a flexible bent structure into the main chain is used, and for example, an aliphatic diamine such as ethylenediamine, hexamethylenediamine, 1, 4-diaminocyclohexane, 1, 3-diaminocyclohexane, or 4, 4' -diaminodicyclohexylmethane; aromatic diamines such as 2-methyl-1, 4-phenylenediamine, o-tolidine, m-tolidine, 3 '-dimethoxybenzidine, and 4, 4' -diaminobenzanilide; polyoxyalkylene diamines such as polyoxyethylene diamine, polyoxypropylene diamine and polyoxybutylene diamine; a polysiloxane diamine; 2, 3, 3 ', 4' -oxydiphthalic anhydride, 3, 4, 3 ', 4' -oxydiphthalic anhydride, 2-bis (4-hydroxyphenyl) propanedibenzoate-3, 3 ', 4, 4' -tetracarboxylic dianhydride, and the like are effective. In addition, it is also effective to use a monomer having a functional group that improves solubility in an organic solvent, for example, fluorinated diamines such as 2, 2 '-bis (trifluoromethyl) -4, 4' -diaminobiphenyl and 2-trifluoromethyl-1, 4-phenylenediamine. In addition to the above-mentioned monomer for improving the solubility of polyimide, the same monomer as the monomer described in the column of < polyamic acid > may be used as long as the solubility is not hindered.

Means for producing a polyimide which can be dissolved in an organic solvent, which is used in the present invention, is not particularly limited, and for example, the following known methods can be used: a method of dissolving a polyamic acid in an organic solvent by chemical imidization or thermal imidization. Examples of such polyimide include aliphatic polyimide (fully aliphatic polyimide), aromatic polyimide, and the like, with aromatic polyimide being preferred. The aromatic polyimide may be obtained by subjecting a polyamic acid having a repeating unit represented by formula (1) to a thermal or chemical ring closure reaction, or may be obtained by dissolving a polyimide having a repeating unit represented by formula (2) in a solvent. Wherein Ar represents an aryl group.

[ chemical formula 1]

[ chemical formula 2]

< polyamideimide >

The polyamideimide used in the present embodiment is not limited in structure or molecular weight as long as it is soluble in an organic solvent used in the coating liquid, and known polyamideimides can be used. The polyamideimide may have a condensable functional group such as a carboxyl group or a functional group which can promote a crosslinking reaction at the time of firing.

The polyamideimide used in the present embodiment may be used without particular limitation as follows: a substance obtained by reacting an arbitrary trimellitic anhydride with a diisocyanate, or a substance obtained by imidizing a precursor polymer obtained by reacting an arbitrary trimellitic anhydride reactive derivative with a diamine.

Examples of the optional trimellitic anhydride or its reactive derivative include trimellitic anhydride halides such as trimellitic anhydride and trimellitic anhydride chloride, and trimellitic anhydride esters.

Examples of the diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4 ' -oxybis (phenyl isocyanate), 4 ' -diisocyanate diphenylmethane, bis [4- (4-isocyanatophenoxy) phenyl ] sulfone, and 2, 2 ' -bis [4- (4-isocyanatophenoxy) phenyl ] propane.

Examples of the diamine include the same diamines as exemplified in the description of the polyamic acid.

< polyamides >

The polyamide used in the present embodiment is preferably a polyamide obtained from a dicarboxylic acid and a diamine, and particularly preferably an aromatic polyamide.

Examples of the dicarboxylic acid 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.

Examples of the diamine include the same diamines as exemplified in the description of the polyamic acid.

< microparticles >

The fine particles used in the present embodiment may have a high sphericity and a small particle size distribution index, for example. Such fine particles have excellent dispersibility in a liquid and are not aggregated with each other. The particle diameter (average diameter) of the fine particles may be set to, for example, about 100 to 2000 nm. By using the fine particles as described above, the pore diameter of the porous resin film F obtained by removing the fine particles in the subsequent step can be made uniform. Therefore, the electric field applied to the separator formed of the porous resin film F can be made uniform.

The material of the fine particles is not particularly limited, and any known material can be used as long as it is insoluble in a solvent contained in the coating liquid and can be removed from the porous resin film F in the subsequent step. Examples of the inorganic material include silica (silica), titanium oxide, and alumina (Al)₂O₃) And the like. Examples of the organic material include organic polymer fine particles such as high molecular weight olefins (e.g., polypropylene and polyethylene), polystyrene, epoxy resins, cellulose, polyvinyl alcohol, polyvinyl butyral, polyesters, polymethyl methacrylate, and polyethers. Examples of the fine particles include colloidal silica such as (monodisperse) spherical silica particles, and calcium carbonate. In this case, the pore diameter of the porous resin film F can be made more uniform.

The particles contained in the first coating liquid and the particles contained in the second coating liquid may have the same or different specifications such as sphericity, particle size, and material. Preferably, the particle size distribution index of the fine particles contained in the first coating liquid is smaller than or the same as that of the fine particles contained in the second coating liquid. Alternatively, the sphericity of the microparticles contained in the first coating liquid is preferably smaller than or the same as that of the microparticles contained in the second coating liquid. In addition, the particles contained in the first coating liquid preferably have a smaller particle diameter (average diameter) than the particles contained in the second coating liquid, and particularly preferably, the particles contained in the first coating liquid are 100 to 1000nm (more preferably 100 to 600nm) and the particles contained in the second coating liquid are 500 to 2000nm (more preferably 700 to 2000 nm). By adopting a particle diameter smaller than the particle diameter of the fine particles contained in the second coating liquid as the particle diameter of the fine particles contained in the first coating film, the opening ratio of the pores on the surface of the porous resin film F can be made high and uniform. Further, the strength of the film can be improved as compared with the case where the porous resin film F is entirely made to have the particle diameter of the fine particles contained in the first coating liquid.

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

[ firing Unit ]

In the present embodiment, the firing unit 20 is a unit that performs a high-temperature process on the unfired film FA. The firing unit 20 fires the unfired film FA to form a fired film FB containing fine particles. The firing unit 20 includes a chamber 21, a heating unit 22, and a conveying unit 23. The chamber 21 has an input port 20a for inputting the unfired film FA and an output port 20b for outputting the fired film FB. The chamber 21 accommodates the heating unit 22 and the conveying unit 23.

An input port 20a is provided on the-Y side of the firing unit 20. The delivery unit 70 delivers the unfired film FA to the input port 20 a. The feeding portion 70 is configured to be able to mount the shaft member SF in the bearing 71. The shaft member SF can be used in common with the shaft member SF mounted on the bearing 61 of the winding portion 60 of the coating unit 10. Therefore, the shaft member SF detached from the winding portion 60 can be mounted on the bearing 71 of the feeding portion 70. With this configuration, the roll body R formed by the winding unit 60 can be disposed in the feeding unit 70. The bearing 71 and the bearing 61 of the winding portion 60 may be set to have the same height from the table surface or may be set to have different heights.

When the shaft member SF is attached to the bearing 71, it is supported so as to be rotatable about an axis parallel to the X direction. The feeding unit 70 includes a driving mechanism (not shown) for rotating the shaft member SF mounted on the bearing 71. The shaft member SF is rotated clockwise in fig. 3 by the drive mechanism, whereby the unfired film FA constituting the roll body R is fed toward the input port 20 a. In the winding section 60, since the unfired film FA is wound so that the surface of the unfired film FA on the first coating film F1 side is disposed outward, the first coating film F1 side is disposed upward when the unfired film FA is pulled out from the roll body R.

The heating unit 22 heats the unfired film FA supplied into the chamber 21. The heating unit 22 includes a plurality of heaters 22a arranged in parallel in the Y direction. As the heater 22a, for example, an infrared heater or the like can be used. The heating unit 22 is disposed over a range from the-Y side end to the + Y side end in the chamber 21. The heating unit 22 can heat the unfired film FA over substantially the entire range in the Y direction. The heating unit 22 can heat the unfired FA film at about 120 to 450 ℃. The heating temperature by the heating unit 22 is appropriately adjusted depending on the transport speed of the unfired film FA, the constituent components of the unfired film FA, and the like.

The conveying section 23 includes a conveying belt 23a, a driving roller 23b, a driven roller 23c, and tension rollers 23d and 23 e. The conveyor belt 23a is formed in an endless shape and arranged in the Y direction. The conveyor belt 23a is formed using a material having durability against the firing temperature of the unfired film FA. The conveyor belt 23a is stretched between the driving roller 23b and the driven roller 23c in a state of having tension so as to be substantially parallel to the XY plane. The unfired film FA and the fired film FB are conveyed in the + Y direction while being placed on the conveyor belt 23 a.

The driving roller 23b is disposed at the + Y-side end portion inside the chamber 21. The driving roller 23b is formed in a cylindrical shape, for example, and is disposed parallel to the X direction. The driving roller 23b is provided with a rotation driving device such as a motor. The drive roller 23b is provided with: the rotation driving device can rotate around an axis parallel to the X direction. The drive roller 23b rotates, thereby rotating the conveying belt 23a in the clockwise direction in fig. 1. The conveyor belt 23a rotates to convey the unfired film FA and the fired film FB placed on the conveyor belt 23a in the + Y direction.

The driven roller 23c is disposed at the-Y-side end portion inside the chamber 21. The driven roller 23c is formed in a cylindrical shape, for example, and is disposed parallel to the X direction. The driven roller 23c is formed with the same diameter as the driving roller 23b, and is disposed so that the position (height position) in the Z direction is substantially equal to the driving roller 23 b. The driven roller 23c is provided so as to be rotatable about an axis parallel to the X direction. The driven roller 23c rotates following the rotation of the conveying belt 23 a.

The tension roller 23d is disposed on the + Z side of the driven roller 23 c. The tension roller 23d is disposed parallel to the X direction and is provided to be rotatable about the X axis. The tension roller 23d is provided to be movable up and down in the Z direction. The tension roller 23d can nip the unfired film FA between it and the driven roller 23 c. The tension roller 23d can rotate while sandwiching the unfired film FA.

The tension roller 23e is disposed on the + Z side of the driving roller 23 b. The tension roller 23e is disposed parallel to the X direction and is provided to be rotatable about the X axis. The tension roller 23e is provided to be movable up and down in the Z direction. The tension roller 23e can nip the burned film FB between the driving roller 23b and the tension roller. The tension roller 23e can rotate while holding the burned film FB.

By the tension rollers 23d and 23e sandwiching the unfired film FA and the fired film FB between the driven roller 23c and the driving roller 23b, the tension from the outside is weakened in the portion between the 2 sandwiched positions of the unfired film FA and the fired film FB. This operation can prevent an excessive load from being applied to the unfired film FA and the fired film FB. The tension rollers 23d and 23e may be adjusted so as not to apply tension to the unfired film FA and the fired film FB disposed in the chamber 21.

The configuration of the firing unit 20 is not limited to this configuration, but is an example. For example, the baking unit 20 may be configured such that the unfired film FA and the baked film FB are not conveyed by the conveyor belt 23 a. The firing unit 20 without the conveyor belt 23a may have, for example, the following configuration: in the chamber 21, a plurality of rollers (or rod-shaped bodies) are disposed on the lower surface side of the unfired film FA and the fired film FB.

[ removal unit ]

The removal unit 30 includes a chamber 31, an etching portion 32, a cleaning portion 33, a liquid discharge portion 34, and a transport portion 35. The chamber 31 has an input port 30a for inputting the fired film FB and an output port 30b for outputting the porous resin film F. The chamber 31 accommodates the etching portion 32, the cleaning portion 33, the liquid discharge portion 34, and the transport portion 35.

The etching portion 32 etches the fired film FB to remove fine particles contained in the fired film FB, thereby forming the porous resin film F. In the etched portion 32, the fired film FB is immersed in a first etching solution Q1 capable of dissolving or decomposing fine particles, thereby removing the fine particles. The etching portion 32 is provided with a supply portion (not shown) for supplying the first etching solution Q1 and a storage portion capable of storing the first etching solution Q1. Since the inside of the etched portion 32 and the inside of the cleaning portion 33 contain different liquids, a suction roll described later may be provided at a position just before the etched portion 32. The water suction roll is disposed on at least one of the + Z side and the-Z side of the porous resin film F, and preferably on both sides.

The cleaning unit 33 cleans the etched porous resin film F. The cleaning section 33 is disposed on the + Y side of the etched section 32 (forward in the conveyance direction of the porous resin film F). The cleaning unit 33 includes a supply unit (not shown) for supplying a cleaning liquid. Further, a recovery unit (not shown) for recovering waste liquid after cleaning the porous resin film F may be provided.

The liquid discharge unit 34 removes the liquid adhering to the porous resin film F after cleaning. Pre-drying may be performed, etc. The liquid discharge unit 34 is disposed on the + Y side of the cleaning unit 33 (forward in the conveyance direction of the porous resin film F). The drainage portion 34 is provided with a suction roll and the like. By bringing the water suction roll into contact with the porous resin film F, the liquid adhering to the porous resin film F can be absorbed while the porous resin film F is conveyed. The arrangement of the water-absorbing roll with respect to the conveyance direction is not particularly limited as long as it is immediately before the discharge from the liquid discharge portion 34. The water suction roll is disposed on at least one of the + Z side and the-Z side of the porous resin film F, and preferably on both sides.

The conveying section 35 conveys the fired film FB and the porous resin film F through the etching section 32, the cleaning section 33, and the liquid discharge section 34. The conveying unit 35 has a plurality of conveying rollers 35 a. The conveying roller 35a rotatably supports the fired film FB and the porous resin film F.

The removal means 30 is not limited to the case of removing the fine particles by etching. For example, when an organic material that can be decomposed at a lower temperature than polyimide is used as the material of the fine particles, the fine particles can be decomposed by heating the fired film FB. The organic material is not particularly limited as long as it is an organic material that can be decomposed at a lower temperature than polyimide. For example, resin fine particles formed of a linear polymer or a known depolymerizable polymer are exemplified. In general, a linear polymer is a polymer in which molecular chains of the polymer are randomly cut off during thermal decomposition, and a depolymerizable polymer is a polymer in which the polymer is decomposed into monomers during thermal decomposition. Both of which decompose to low molecular weight species or CO₂But disappears from the fired film FB. In this case, the decomposition temperature of the fine particles is preferably 200 to 320 ℃, more preferably 230 to 260 ℃. When the decomposition temperature is 200 ℃ or higher, film formation can be performed even when a high boiling point solvent is used in the coating liquid, and the range of selection of firing conditions in the firing unit 20 is widened. When the decomposition temperature is lower than 320 ℃, only the fine particles can be eliminated without causing thermal damage to the fired film FB. When the fine particles are removed by heating, the above-described firing unit 20 may be used as the removal unit 30. That is, the sintering unit 20 can be used to remove the fine particles from the unfired film FA while heating the unfired film FA.

[ Pre-wetting Unit ]

Returning to fig. 1, in the manufacturing system SYS1, the pre-wetting unit U2 is provided on the rear stage side of the film forming unit U1. The pre-wetting unit U2 supplies a pre-wetting liquid to the porous resin film F formed by the film forming unit U1. The pre-wetting liquid used is a liquid that does not dissolve the porous resin film F. Fig. 4 is a diagram illustrating an example of the pre-wetting unit U2. As shown in fig. 4, the pre-wetting unit U2 has a storage section 41, a circulation section 42, and a conveying section 43. The reservoir 41 stores a pre-wetting liquid PW for impregnating the porous resin film F.

The pre-wetting liquid PW uses a material that does not dissolve the porous resin film F. The pre-wetting liquid PW has an affinity for a second etching liquid Q2 used in a chemical etching unit U3 described later. In addition, the pre-wetting liquid has affinity with the porous resin film F. The pre-wetting liquid PW contains 1% to 100% of an alcohol such as isopropyl alcohol, ethanol, n-propyl alcohol, methanol, and the like. In view of the production cost of the porous resin film F, the pre-wetting liquid PW is preferably an alcohol aqueous solution containing 1 to 50% alcohol in water. Further, in view of carrying out from the pre-wetting unit U2, the pre-wetting liquid PW further preferably contains 5% to 30% of an alcohol. The pre-wetting liquid PW may contain a surfactant. The pre-wetting liquid may contain a glycol-based substance such as ethylene glycol.

The circulation portion 42 recovers the pre-wetting liquid PW of the reservoir portion 41, and returns the recovered pre-wetting liquid PW to the reservoir portion 41. The circulation unit 42 includes a first pipe 42a, a pump 42b, and a second pipe 42 c. One end of the first pipe 42a is connected to the bottom of the reservoir 41, and the other end is connected to the input side of the pump 42 b. One end of the second pipe 42c is connected to an upper portion of the side wall of the reservoir 41, and the other end is connected to the output side of the pump 42 b. The circulation unit 42 pumps the pre-wetting liquid PW from the bottom of the reservoir 41 to the first pipe 42a by driving the pump 42b, and supplies the pre-wetting liquid PW from the upper portion of the side wall to the reservoir 41 through the pump 42b and the second pipe 42 c.

A filter for removing impurities from the pre-wet liquid PW sucked from the bottom of the reservoir 41 may be provided in a part of the first pipe 42 a. Further, a sensor (not shown) for detecting the liquid level of the pre-wetting liquid PW in the reservoir 41 may be provided, or the output of the sensor may be monitored, and when the liquid level of the pre-wetting liquid PW is lower than a preset reference value, a new pre-wetting liquid PW may be supplied to the reservoir 41 using a supply device (not shown). Further, a sensor (not shown) for detecting the concentration of the pre-wetting liquid PW in the reservoir 41 may be provided, or the output of the sensor may be monitored, and when the concentration of the pre-wetting liquid PW is lower than a preset reference value, the concentration of the pre-wetting liquid PW in the reservoir 41 may be adjusted by using an adjusting device (not shown).

The conveying unit 43 sequentially introduces the porous resin films F fed out from the film forming unit U1, and immerses the porous resin films F in the pre-wetting liquid PW in the reservoir 41 without winding. Further, the conveying unit 43 conveys the porous resin film F immersed in the pre-wetting liquid PW of the reservoir 41 to the chemical etching unit U3 without winding. The conveying section 43 has input rollers 43a and 43b, a dipping roller 43c, and output rollers 43d and 43 e. The feed roller 43a supports the porous resin film F conveyed to the pre-wetting unit U2 and guides the film in the + Y direction. The input roller 43b bends the porous resin film F guided from the input roller 43a toward the-Z side and guides the film to the impregnation roller 43c side.

The dip roller 43c is disposed in a state at least partially immersed in the pre-wetting liquid PW. The impregnation roller 43c supports the porous resin film F guided to the-Z side from the input roller 43b at the end of the-Z side, and bends it to the + Z side to be guided to the output roller 43d side. The porous resin film F is guided by the-Z-side end of the immersing roller 43c, and is immersed in the pre-wetting liquid PW. The output roller 43d bends the porous resin film F guided from the impregnation roller 43c to the + Y side and guides the film F to the output roller 43e side. The discharging roller 43e conveys the porous resin film F guided from the discharging roller 43d to the + Y side, i.e., the chemical etching unit U3 outside the pre-wetting unit U2.

The dipping time in the pre-wetting liquid PW may be adjusted by the distance or speed at which the porous resin film F moves in the pre-wetting liquid PW. For example, in the case where the immersion time in the pre-wetting liquid PW is to be extended, the conveying speed of the porous resin film F is made slow, or the porous resin film F is moved in the pre-wetting liquid PW over a long distance. When the porous resin film F is moved in the pre-wetting liquid PW over a long distance, a bank 41 that is long in the transport direction may be used, or a plurality of dip rolls 43c may be arranged in the bank 41 so as to change the height in the vertical direction, and the porous resin film F is bent upward and downward in the pre-wetting liquid PW to extend the distance that the porous resin film F passes through the pre-wetting liquid PW.

As shown in fig. 1, the manufacturing system SYS1 performs a so-called roll-to-roll process in a section extending from the film forming unit U1, the pre-wetting unit U2, and the chemical etching unit U3 to the winding unit U4. Therefore, in this interval, the respective films of the unfired film FA, the fired film FB, and the porous resin film F are continuously conveyed. The present invention is not limited to the roll-to-roll processing. For example, the following configuration is possible: the porous resin film F fed out from the film forming unit U1 is wound into a roll, and the roll is conveyed to the pre-wetting unit U2, and the porous resin film F is sequentially pulled out from the roll by the conveying section 43 and conveyed to the pre-wetting unit U2. Further, the porous resin film F fed out from the pre-wetting unit U2 may be wound into a roll and the roll may be conveyed to the chemical etching unit U3.

[ chemical etching Unit ]

Returning to fig. 1, in the manufacturing system SYS1, the chemical etching unit U3 is provided on the rear stage side (+ Y side) of the pre-wetting unit U2. Further, a winding unit U4 for winding the porous resin film F in a roll shape is provided on the + Y side (forward side in the conveyance direction of the porous resin film F) of the chemical etching unit U3. The chemical etching unit U3 uses a second etching solution different from the first etching solution to dissolve a part of the porous resin film F. FIG. 5 is a view showing an example of the chemical etching unit U3. As shown in FIG. 5, the chemical etching unit U3 includes a chemical etching section 51, a cleaning section 52, and a conveying section 53.

The chemical etching section 51 chemically etches the porous resin film F with the second etching solution Q2 to dissolve a part of the porous resin film F. The chemical etched portion 51 has a reservoir 51 a. The second etching solution Q2 is stored in the storage tank 51 a. The second etching solution Q2 is an aqueous solution containing tetramethylammonium hydroxide. The second etching solution Q2 contained less than 25% tetramethylammonium hydroxide. The reservoir tank 51a has a discharge portion 51b for discharging the second etching solution Q2. The discharge portion 51b is connected to a sewer, for example. In the present embodiment, since the second etching solution Q2 contains substantially no pre-wetting solution PW, the BOD (Biochemical Oxygen Demand) value of the second etching solution Q2 can be suppressed from increasing. Therefore, the waste liquid of the second etching liquid Q2 can be discharged into the sewer, and the burden of waste liquid treatment can be reduced. The pre-wetting liquid PW may be mixed in the second etching solution Q2 in a BOD value range in which the waste liquid can be discharged to the sewer.

The cleaning unit 52 cleans the porous resin film F after the chemical etching. The cleaning part 52 is disposed on the + Y side of the chemical etching part 51 (forward in the conveying direction of the porous resin film F). The cleaning section 52 includes a supply section 52a for supplying a cleaning liquid, and a waste liquid collection tank 52b for collecting waste liquid after cleaning the porous resin film F. The effluent collecting tank 52b has a discharge portion 52 c. The discharge portion 52c is connected to a sewer, for example. Further, since the pre-wetting liquid PW is not substantially contained in the cleaning unit 52 as in the chemical etched portion 51, the waste liquid in the cleaning unit 52 can be discharged to the sewer, and the burden of waste liquid treatment can be reduced. Thus, the advantage of feeding the pre-wetting liquid PW to the porous resin film F is that the BOD of the waste liquid from the chemical etched portion 51 is reduced, and the BOD of the waste liquid from the cleaning portion 52 is also reduced. In the present embodiment, since the pre-wetting is performed in the pre-wetting unit U2, methanol or the like is not mixed with the second etching solution Q2 and is used, and thus BOD can be significantly reduced as the second etching solution Q2 as compared with a conventional process in which pre-wetting is not performed. Further, the BOD introduced from chemical etched portion 51 to cleaning portion 52 can be reduced, and the BOD of the waste liquid in cleaning portion 52 can be reduced.

The conveying section 53 sequentially introduces the porous resin films F sent from the pre-wetting unit U2, and immerses the porous resin films F in the second etching solution Q2 of the chemical etching section 51 without winding them. The conveying unit 53 conveys the porous resin film F immersed in the second etching solution Q2 in the chemical etching unit 51 to the cleaning unit 52, and outputs the cleaned porous resin film F. The conveying unit 53 includes an input roller 53a, dipping rollers 53b and 53c, relay rollers 53d and 53e, cleaning rollers 53f and 53g, and an output roller 53 h. The input roller 53a bends the porous resin film F sent to the chemical etching unit U3 toward the-Z side and guides the film to the impregnation roller 53b side.

The immersing rollers 53b and 53c are disposed in a state where at least a part thereof is immersed in the second etching solution Q2. The impregnation roller 53c supports the porous resin film F guided to the-Z side from the input roller 53a at the end of the-Z side and guides it to the + Y side. The dipping roller 53c bends the porous resin film F guided from the dipping roller 53b to the + Z side and guides the film to the relay roller 53d side. The porous resin film F is guided to the-Z-side end of the immersing rollers 53b and 53c, and is immersed in the second etching solution Q2. In the pre-wetting unit U2, the distance (or time) for immersing the porous resin film F in the pre-wetting liquid PW is shorter than the distance (or time) for immersing the porous resin film F in the second etching liquid Q2.

The relay rollers 53d and 53e transport the porous resin film F between the chemical etching section 51 and the cleaning section 52. The relay roller 53d bends the porous resin film F guided to the + Z side from the impregnation roller 53c to the + Y side and guides the film to the relay roller 53e side. The relay roller 53e bends the porous resin film F guided to the + Y side from the relay roller 53d to the-Z side and guides the film to the cleaning roller 53F side. Since the liquids contained in the inside of the chemical etched portion 51 and the inside of the cleaning portion 52 are different from each other, a water suction roller may be provided as at least one of the relay rollers 53d and 53 e. The water suction roll is disposed on at least one of the + Z side and the-Z side of the porous resin film F, and preferably on both sides.

The cleaning rollers 53f and 53g are disposed inside the effluent collecting tank 52 b. The cleaning roller 53F supports and conveys the porous resin film F, which receives the supply of the cleaning liquid from the supply portion 52a, in the cleaning portion 52. The cleaning roller 53F supports the porous resin film F guided to the + Y side from the relay roller 53d at the end on the-Z side, and bends it to the + Y side to be guided to the cleaning roller 53g side. The cleaning roller 53g bends the porous resin film F guided from the cleaning roller 53F to the + Z side and guides the film F to the output roller 53h side. The output roller 53h bends the porous resin film F guided to the + Z side from the cleaning roller 53g in the + Y direction and outputs the film from the chemical etching unit U3.

[ winding Unit ]

As shown in fig. 1, the winding unit U4 is disposed on the downstream side in the transport direction of the porous resin film F with respect to the chemical etching unit U3. The winding unit U4 has the same configuration as the winding unit 60 described above, and is configured such that the shaft member SF is attached to the bearing BR. The shaft member SF winds the porous resin film F output from the chemical etching unit U3 to form a roll RF. The shaft member SF is detachably provided to the bearing BR. When the shaft member SF is attached to the bearing BR, it is supported so as to be rotatable about an axis parallel to the X direction. The winding unit U4 includes a drive mechanism (not shown) for rotating the shaft member SF attached to the bearing BR. The porous resin film F is wound by rotating the shaft member SF by a drive mechanism. The winding body RF can be recovered by detaching the shaft member SF from the bearing BR in a state where the winding body RF is formed.

[ production method ]

Next, an example of the operation of producing the porous resin film F using the production system SYS1 configured as described above will be described. Fig. 6(a) to (e) are views showing an example of the process of producing the porous resin film F in the film forming unit U1. First, in the film forming unit U1, the unfired film FA was formed by the coating unit 10. In the coating unit 10, the substrate delivery roll 11a is rotated to deliver the transport substrate S, and the transport substrate S is wound up by the substrate winding roll 11e after being hung on the backup rolls 11b to 11 d. Then, the transport base material S is sequentially fed from the base material feed roller 11a, and is wound by the base material winding roller 11 e.

In this state, the first nozzle 12 is disposed at the discharge position P1 with the discharge port 12a facing in the + Y direction. By this operation, the ejection port 12a is directed to a portion of the transport base material S supported by the support roller 11 b. Then, the first coating liquid is ejected from the ejection port 12 a. The first coating liquid is discharged from the discharge port 12a in the + Y direction, reaches the transport base S, and then is applied to the transport base S with the movement of the transport base S. As a result, a first coating film F1 formed from the first coating liquid is formed on the conveying substrate S (see fig. 3).

Next, the second nozzle 13 is disposed at the discharge position P2 with the discharge port 13a facing in the-Z direction. By this operation, the ejection port 13a is directed to the portion of the transport base material S supported by the support roller 11 c. Then, the second coating liquid is ejected from the ejection port 13 a. The second coating liquid is discharged from the discharge port 13a in the-Z direction, reaches the first coating film F1 formed on the transport substrate S, and is then applied to the first coating film F1 as the transport substrate S moves. As a result, as shown in fig. 6(a), a second coating film F2 formed of the second coating liquid is formed on the first coating film F1. In the first coating film F1 and the second coating film F2, the resin material a1 contains the fine particles a2 at volume ratios different from each other. In addition, the content of the fine particles is set so that the first coating film F1 is larger than the second coating film F2.

Since the first coating liquid and the second coating liquid are applied with the discharge ports 12a and 13a directed toward the portions of the transport base material S supported by the backup rollers 11b and 11c, the force acting on the transport base material S is received by the backup rollers 11b and 11c when the first coating liquid and the second coating liquid reach the transport base material S. Therefore, the occurrence of deflection, vibration, and the like of the transport substrate S can be suppressed, and the first coating film F1 and the second coating film F2 can be stably formed on the transport substrate S at a uniform thickness.

Next, when the transport substrate S moves and the laminated portion of the first coating film F1 and the second coating film F2 is introduced into the chamber 14a of the drying section 14, the first coating film F1 and the second coating film F2 are dried in the drying section 14. In the drying section 14, the first coating film F1 and the second coating film F2 are heated at a temperature of, for example, about 50 to 100 ℃. In this temperature range, the first coating film F1 and the second coating film F2 can be heated without causing warpage, deformation, or the like in the transport substrate S. The laminate of the first coating film F1 and the second coating film F2 was dried to form an unfired film FA as shown in fig. 6 (b).

In the present embodiment, the laminate refers to an unfired film including the first coating film F1 and the second coating film F2. In the case where the same resin of polyamic acid, polyimide, polyamideimide, or polyamide is used in the first coating liquid and the second coating liquid, respectively, the unfired film (or porous imide resin film) including the first coating film F1 and the second coating film F2 formed is substantially 1 layer, but the unfired film (or porous imide resin film having regions of different porosity) having different fine particle contents is formed, and therefore, the case including the case where the same resin is used in the first coating liquid and the second coating liquid is called a laminate in the present embodiment.

Next, when the transport base material S moves and the leading end portion of the unfired film FA reaches the backup roller 11d (peeling section 15), the leading end portion is peeled from the transport base material S by, for example, manual operation by an operator. In the present embodiment, since PET is used as a material of the transport substrate S, for example, when the first coating film F1 and the second coating film F2 are dried to form the unfired film FA, the film is easily peeled from the transport substrate S, and thus the peeling can be easily performed by an operator.

After the front end portion of the unfired film FA was peeled off, the transport substrate S continued to move, and the first coating film F1 was formed by the first nozzle 12. Further, the second nozzle 13 continues to form the second coating film F2, and the drying section 14 forms the unfired film FA. As a result, the unfired film FA is formed in a band shape, and the length of the unfired film FA output from the drying section 14 to the + Y side gradually increases. The operator continuously peels off the unfired film FA in the peeling section 15. When the tip of the peeled unfired film FA reaches the length of the shaft member SF reaching the winding section 60, the worker manually attaches the tip of the unfired film FA to the shaft member SF while hanging the unfired film FA on the delivery roller 11 f. Then, as the unfired films FA are sequentially formed and peeled off, the shaft member SF is rotated in the winding portion 60. By this operation, the peeled unfired film FA is sequentially output from the coating unit 10, and wound around the shaft member SF of the winding unit 60 to form the roll body R. As shown in fig. 6(c), the unfired film FA constituting the roll body R is peeled off from the transport substrate S, and the front surface and the back surface are exposed at the same time.

The operation of peeling the distal end portion of the unfired film FA, the operation of attaching the peeled distal end portion to the shaft member SF, and the like are not limited to the modes performed by manual operations by an operator, and may be performed automatically using a robot or the like, for example. In addition, in order to improve the releasability of the unfired film FA, a release layer may be formed in advance on the surface of the transport substrate S.

After the unfired film FA having a predetermined length is wound around the shaft member SF, the shaft member SF is detached from the bearing 61 together with the wound body R while cutting the unfired film FA. Then, a new shaft member SF is attached to the bearing 61 of the winding section 60, and the cut end of the unfired film FA is attached to the shaft member SF and rotated to continue forming the unfired film FA, whereby a new roll body R can be produced.

On the other hand, for example, the operator conveys the shaft member SF detached from the bearing 61 together with the winding body R to the winding portion 60, and attaches it to the bearing 61. The conveying operation and the mounting operation of the shaft member SF may be automatically performed by using a robot, a conveying device, or the like. After the shaft member SF is attached to the bearing 61, the shaft member SF is rotated to sequentially draw out the unfired film FA from the roll body R, and the unfired film FA is fed into the chamber 21 of the firing unit 20. When the front end of the unfired film FA is input to the chamber 21, the operation may be performed manually by an operator or automatically by a robot or the like.

The unfired film FA fed into the chamber 21 is placed on the conveyor belt 23a, and is conveyed in the + Y direction as the conveyor belt 23a rotates. The tension in the conveying direction can be adjusted by using the tension rollers 23d and 23 e. Then, the unfired film FA is fired by the heating unit 22 while being conveyed.

The temperature at the time of firing varies depending on the structure of the unfired film FA, and is preferably about 120 to 375 ℃, and more preferably 150 to 350 ℃. In addition, in the case where the fine particles contain an organic material, it is necessary to set the temperature lower than the thermal decomposition temperature thereof. When the coating solution contains polyamic acid, imidization is preferably completed during the firing, but the unfired film FA is made of polyimide, polyamideimide, or polyamide, and the unfired film FA is not subjected to the high-temperature treatment by the firing unit 20.

In addition, for example, in the case where the coating liquid contains polyamic acid and/or polyimide, the firing conditions may be a method of raising the temperature from room temperature to 375 ℃ over 3 hours and then holding the temperature at 375 ℃ for 20 minutes, or may be heating in stages as follows: the temperature was raised from room temperature to 375 deg.C (steps held for 20 minutes) in stages at 50 deg.C, and finally held at 375 deg.C for 20 minutes, etc. Further, the end of the unfired film FA may be fixed to a SUS template or the like to prevent deformation.

By this firing, a fired film FB is formed as shown in fig. 6 (d). In the fired film FB, the resin layer A3 imidized or high-temperature treated contains fine particles a 2. The thickness of the film formed by firing the film FB can be obtained by measuring the thickness at a plurality of positions with a micrometer, for example, and averaging the measured thicknesses. When the film is used for a separator or the like, the average film thickness is preferably 3 to 500 μm, more preferably 5 to 100 μm, and still more preferably 10 to 30 μm.

The fired film FB formed in the firing unit 20 is output from the firing unit 20, and is input to the removing unit 30 without being wound. When the leading end portion of the fired film FB is input to the removing unit 30, the operation may be performed manually by an operator or may be performed automatically by a robot or the like.

The baked film FB input to the removing unit 30 is placed on the conveying roller 35a, and is conveyed in the + Y direction as the conveying roller 35a rotates. In the removal unit 30, the fine particles a2 are first removed in the etched portion 32 as the burned film FB is carried. When silica is used as the material of the fine particles a2, for example, the fired film FB is immersed in an etching solution such as a low-concentration aqueous hydrogen fluoride solution in the etched portion 32. As a result, the fine particles a2 were dissolved in the etching solution and removed, and as shown in fig. 6(e), a porous resin film F containing porous portions a4 inside the resin layer A3 was formed.

Then, the porous resin film F is sequentially fed to the cleaning unit 33 and the liquid discharge unit 34 by the rotation of the feed roller 35 a. In the cleaning section 33, the porous resin film F is cleaned with a cleaning liquid. In the drain part 34, the porous resin film F is drained to remove the cleaning liquid. Then, the porous resin film F is output from the removal unit 30, that is, from the film formation unit U1, and is input to the pre-wetting unit U2.

The porous resin film F fed to the pre-wetting unit U2 is conveyed in the + Y direction by the feed roller 43a, and is bent to the-Z side by the feed roller 43b and stretched over the-Z side end of the dipping roller 43 c. With this configuration, the porous resin film F is immersed in the pre-wetting liquid PW in the reservoir 41, and in this state, is hung on the-Z side of the immersing roller 43c and conveyed. Fig. 7 is a diagram illustrating an example of the pre-wet process in the pre-wet unit U2. As shown in fig. 7, in the porous resin film F immersed in the pre-wetting liquid PW, the pre-wetting liquid PW penetrated into the porous portion a4 of the resin layer A3. The circulation unit 42 is configured to circulate the pre-wetting liquid PW by driving the pump 42b, discharging the pre-wetting liquid PW from the bottom of the reservoir 41 to the first pipe 42a, and feeding the pre-wetting liquid PW from the upper portion of the side wall to the reservoir 41 through the pump 42b and the second pipe 42 c. With this configuration, the pre-wetting liquid PW flows to promote the penetration into the porous portion a 4.

The porous resin film F is conveyed by the dipping roller 43c of the conveyor 43 and is thereby pulled out from the pre-wetting liquid PW. The porous resin film F drawn out from the pre-wetting liquid PW is bent by the delivery roller 43d and conveyed to the + Y side. As a result, the porous resin film F was output from the pre-wetting unit U2 and input to the chemical etching unit U3.

The porous resin film F fed to the chemical etching unit U3 is conveyed in the + Y direction by the feed roller 53a, and is stretched over the-Z-side end portions of the impregnation rollers 53b and 53 c. The porous resin film F is immersed in the second etching solution Q2 in the storage tank 51a while moving from the immersion roller 53b to the immersion roller 53 c. As a result, the porous resin film F was subjected to chemical etching treatment.

Fig. 8(a) and (b) are diagrams showing an example of the chemical etching treatment in the chemical etching unit U3. In the chemical etching treatment, as shown in fig. 8(a), the second etching liquid Q2 is introduced into the porous portion a4 of the porous resin film F so as to be sucked into the pre-wetting liquid PW. The second etching liquid Q2 permeates into the porous portion a4, and the interior of the porous portion a4 is removed. As a result, as shown in fig. 8(b), with the porous resin film F, burrs of the porous portion a4 are removed, and connectivity is ensured.

Then, the porous resin film F is conveyed to the cleaning section 52 via the relay rollers 53d and 53e, and is stretched over the-Z-side ends of the cleaning rollers 53F and 53 g. While the porous resin film F moves from the cleaning roller 53F to the cleaning roller 53g, the porous resin film F is cleaned by the cleaning liquid supplied from the supply portion 52 a. The cleaned porous resin film F was conveyed to the + Y side by the conveying roller 53h and conveyed from the chemical etching unit U3. The porous resin film F output from the chemical etching unit U3 was wound by the winding unit U4.

As described above, the manufacturing system SYS1 according to the present embodiment includes the pre-wetting unit U2 that supplies the pre-wetting liquid PW that does not dissolve the porous resin film F to the porous resin film F formed by the film forming unit U1, and thus the pre-wetting liquid PW can be attached to or permeate into the porous portion a4 by supplying the pre-wetting liquid PW to the porous resin film F. By performing the chemical etching treatment on the porous resin film F in this state, the second etching liquid Q2 permeates into the porous portion a4 to be attracted by the pre-wetting liquid PW. Therefore, the second etching solution Q2 can be reliably supplied into the porous portion a 4. As a result, the inside of the porous resin film F can be appropriately subjected to chemical etching treatment, and a high-quality imide-based porous resin film F can be efficiently produced. In addition, since the pre-wetting liquid PW was supplied to the porous resin film F by the pre-wetting unit U2 (which is a unit different from the chemical etching unit U3), it was not necessary to mix the pre-wetting liquid PW with the second etching liquid Q2 in the chemical etching unit U3. Therefore, the BOD value of the waste liquid of the second etching solution Q2 can be suppressed, and the waste liquid can be discharged to a sewage. As a result, the burden of waste liquid treatment in the process of producing the porous resin film F can be reduced.

[ modified examples ]

In the above embodiment, the porous resin film F output from the film forming unit U1 was input to the pre-wetting unit U2 without being wound, but the present invention is not limited to this configuration. Fig. 9 is a diagram illustrating an example of a manufacturing system SYS2 according to a modification. As shown in fig. 9, the manufacturing system SYS2 may be provided with a winding unit 80 that winds the porous resin film F and a delivery unit 90 that delivers the porous resin film F wound by the winding unit 80, between the film forming unit U1 and the pre-wetting unit U2.

The winding portion 80 has the same configuration as the winding portion 60 in the above embodiment, and is configured such that a shaft member SF is attached to a bearing 81. The shaft member SF winds the porous resin film F output from the film forming unit U1 to form a roll RFa. The shaft member SF is detachably provided to the bearing 81. The winding portion 80 includes a driving mechanism (not shown) for rotating the shaft member SF mounted on the bearing 81.

The feeding unit 90 has the same configuration as the feeding unit 70 in the above embodiment, and is configured to be able to attach the shaft member SF to the bearing 91. The shaft member SF can be used in common with the shaft member SF mounted on the bearing 81 of the winding portion 80. Therefore, the shaft member SF detached from the winding portion 80 can be attached to the bearing 91 of the feeding portion 90. As a result, the roll body RFa formed by the winding unit 80 can be disposed in the feeding unit 90.

Fig. 10 is a diagram illustrating an example of a manufacturing system SYS3 according to a modification. As shown in fig. 10, the manufacturing system SYS3 may include a winding unit 80 configured to wind the porous resin film F formed by the film forming unit U1, and a pre-wetting unit U2A configured to immerse the roll RFa of the porous resin film F wound by the winding unit 80 in the pre-wetting liquid PW. The manufacturing system SYS3 may include a delivery unit 90 that delivers the wound body RFa immersed in the pre-wetting liquid PW to the chemical etching unit U3.

Fig. 11 is a diagram illustrating an example of a manufacturing system SYS4 according to a modification. As shown in fig. 11, in the manufacturing system SYS4, the film forming unit U1 may include a winding unit 82 for winding the fired film FB between the firing unit 20 and the removing unit 30, and may include a removing unit 30B for immersing the roll RFb of the fired film FB wound around the winding unit 82 in the first etching solution Q1. With this configuration, the fine particles are removed from the fired film FB, the fired film FB becomes the porous resin film F, and the roll-shaped body RFa obtained by winding the porous resin film F is formed. In this case, the formed roll body RFa may be immersed in the pre-wetting unit U2A of the manufacturing system SYS3 shown in fig. 10, for example, in a wound state.

Fig. 12 is a diagram illustrating an example of a manufacturing system SYS5 according to a modification. As shown in fig. 12, the manufacturing system SYS5 may be provided with a winding unit 85 for winding the porous resin film F and a feeding unit 95 for feeding the porous resin film F wound by the winding unit 85, between the pre-wetting unit U2 and the chemical etching unit U3. The winding portion 85 has the same configuration as the winding portions 60 and 80 in the above-described embodiment, and is configured to attach the shaft member SF to the bearing 86. The shaft member SF winds the porous resin film F fed out from the pre-wetting unit U2 to form a roll RFc. The feeding unit 95 has the same configuration as the feeding unit 90 in the above embodiment, and is configured to be able to attach the shaft member SF to the bearing 96.

A common shaft member SF is used between the winding portion 85 and the feeding portion 95. Therefore, the shaft member SF detached from the bearing 86 of the winding portion 85 can be attached to the bearing 96 of the feeding portion 95. As a result, the roll-shaped body RFc formed by the winding unit 85 can be disposed in the feeding unit 95.

In the above embodiment, the configuration in which the pre-wetting unit U2 stores the pre-wetting liquid PW in the storage unit 41 and impregnates the porous resin film F was described as an example, but the present invention is not limited to this configuration. Fig. 13 is a diagram illustrating an example of the pre-wetting unit U2B according to a modification. As shown in fig. 13, the pre-wetting unit U2B may have a configuration in which the pre-wetting liquid PW is ejected or sprayed to the supply unit 45 of the porous resin film F formed by the film forming unit U1. In the example shown in fig. 13, the feeder 45 includes a supply source 45a of the pre-wetting liquid PW and a nozzle 45b that ejects or sprays the pre-wetting liquid PW supplied from the supply source 45 a. The plurality of nozzles 45b may be provided in the conveyance direction (Y direction).

The pre-wetting unit U2B has a recovery tank 46 for recovering the pre-wetting liquid PW fed to the porous resin film F. The recovery tank 46 has a discharge portion 46a that discharges the recovered pre-wetting liquid PW. The discharge portion 46a may be connected to the circulation portion 42, for example. The circulation unit 42 may be configured to return the pre-wetting liquid PW discharged from the discharge unit 46a to the supply source 45a of the supply unit 45. The pre-wetting unit U2B has a conveying section 47. The conveying unit 47 sequentially draws in the porous resin films F sent out from the film forming unit U1, and moves the porous resin films F to a position below the nozzles 45b of the supply unit 45 without winding. The conveying section 47 has an input roller 47a, feed rollers 47b, 47c, and an output roller 47 d.

The input roller 47a bends the porous resin film F conveyed to the pre-wetting unit U2B toward the-Z side and guides the film to the supply roller 47b side. The supply rollers 47b and 47c are disposed in the recovery tank 46. The feed roller 47b supports the porous resin film F guided to the-Z side from the input roller 47a at the end of the-Z side, and guides it to the + Y side. The supply roller 47c bends the porous resin film F guided from the supply roller 47b to the + Z side and conveys the film to the output roller 47d side. The porous resin film F is guided by the-Z-side end portions of the feeding rollers 47b and 47c, and is in a state of receiving the pre-wetting liquid PW fed from the nozzle 45 b.

In the above embodiment, the configuration in which the porous resin film F fed out from the chemical etching unit U3 is wound by the winding unit U4 in the production systems SYS1 to SYS5 has been described as an example, but the configuration is not limited thereto. Fig. 14 is a diagram illustrating an example of a manufacturing system SYS6 according to a modification. As shown in fig. 14, the manufacturing system SYS6 may be provided with a post-processing device (S1, S2, S3) for performing post-processing on the porous resin film F output from the chemical etching unit U3 at a stage subsequent to the chemical etching unit U3 and prior to the winding unit U4. The manufacturing system SYS6 shown in fig. 14 is provided with a drying device S1, a heating device S2, and an inspection device S3 as post-processing devices.

The drying device S1 includes an air ejection portion 49a that ejects air toward the porous resin film F.

The air ejection portions 49a may be provided in plural in the conveyance direction of the porous resin film F and in the direction orthogonal to the conveyance direction, for example. The drying device S1 can remove the liquid such as the cleaning water adhering to the porous resin film F by ejecting air from the air ejection portion 49a to the porous resin film F. The drying device S1 may not be provided.

The heating device S2 includes a chamber 49b and a heater 49 c. In the heating device S2, the porous resin film F fed into the chamber 49b is heated by the heater 49c, whereby the porous resin film F can be dried more reliably. In addition, the porous resin film F may be: even if the unfired portion remains, the unfired portion can be fired by heating with the heating device S2. The heating device S2 may not be provided.

The inspection apparatus S3 includes a film thickness inspection apparatus 49d and an image inspection apparatus 49 e. The film thickness inspection device 49d inspects the film thickness of the dried porous resin film F. The image inspection device 49e inspects the surface state of the porous resin film F after drying. The film thickness inspection device 49d and the image inspection device 49e can report to an operator or the like that there is an abnormality in the film thickness of the porous resin film F or that there is a surface abnormality due to a damage or the like by outputting the inspection results, and can also give a discrimination label that there is an abnormality or the like to the roll body that has an abnormality. In addition to the above-described post-treatment apparatus, examples of other post-treatment apparatuses include an antistatic apparatus for performing a charge removal treatment on the porous resin film F. The antistatic unit may be equipped with a static eliminator such as an ionizer (ionizer).

[ separator ]

Next, the separator 100 according to the present embodiment will be described. Fig. 15 is a schematic diagram showing an example of the lithium ion battery 200, in which a part thereof is cut. As shown in fig. 15, the lithium ion battery 200 includes a metal case 201 having a positive electrode terminal and a negative electrode terminal 202. Inside the metal case 201, a positive electrode 201a, a negative electrode 202a, and a separator 100 are provided, and these are immersed in an electrolyte solution not shown. The separator 100 is disposed between the positive electrode 201a and the negative electrode 202a, and prevents electrical contact between the positive electrode 201a and the negative electrode 202 a. As the positive electrode 201a, a lithium transition metal oxide is used, and as the negative electrode 202a, for example, lithium, carbon (graphite), or the like is used.

The porous resin film F described in the above embodiment can be used as the separator 100 of the lithium ion battery 200. In this case, for example, the surface on which the first coating film F1 is formed is on the negative electrode 202a side of the lithium ion battery, whereby the battery performance can be improved. Although the separator 100 of the rectangular lithium ion battery 200 is illustrated in fig. 15 as an example, the present invention is not limited to this configuration. The porous resin film F can be used for a separator of any type of lithium ion battery, such as a cylindrical type or a laminate type. The porous resin film F can be used as a fuel cell electrolyte film, a gas or liquid separation film, or a low dielectric constant material, in addition to a lithium ion battery separator.

The embodiments have been described above, but the present invention is not limited to the above description, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment and modification, the case where part of the porous resin film F is removed, or the case where only the chemical etching method is performed is exemplified as an example and the description is not limited to this configuration. For example, a part of the porous resin film F may be removed by a method combining a chemical etching method and a physical removal method. As the physical method, for example, the following methods can be used: dry etching based on plasma (oxygen, argon, etc.), corona discharge, etc.; a method for treating the surface of an aromatic polyimide film by dispersing a polishing agent (for example, alumina (hardness 9) or the like) in a liquid and irradiating the surface of the aromatic polyimide film with the polishing agent at a rate of 30 to 100 m/s. These methods can be applied to either before or after the removal of the fine particles from the fired film FB in the removal unit 30. As a physical method applicable only to a case where the removal of fine particles is performed, the following method may be employed: the surface of the object is pressed against a backing film (for example, a polyester film such as a PET film) wetted with a liquid, and then the porous resin film F is peeled off from the backing film without drying or after drying. The porous resin film F is peeled from the backing paper film in a state where only the surface layer of the porous resin film F remains on the backing paper film due to the surface tension or electrostatic adhesion of the liquid.

For example, in the above embodiment and modification, the case where the unfired film FA is formed using two kinds of coating liquids having different particle contents was described as an example, but the present invention is not limited to this configuration, and the unfired film may be formed using 1 kind of coating liquid. In this case, either one of the first nozzle 12 and the second nozzle 13 may not be used, and one nozzle may be omitted. In the case where one nozzle is omitted, it is preferable to omit the first nozzle 12 and use the second nozzle 13.

In the above embodiment and modification, the configuration in which 1 film-forming unit U1, pre-wetting unit U2, and chemical etching unit U3 are disposed was described as an example, but the present invention is not limited to this configuration. For example, at least one of the units may be provided in plural. In this case, for example, a plurality of cells having a small amount (for example, length) of the unfired film FA, the fired film FB, or the porous resin film F that can be processed per unit time are arranged, whereby the production efficiency of the entire production system can be improved.

In the above embodiment and modification, the case where the units of the film forming unit U1, the pre-wetting unit U2, and the chemical etching unit U3 convey the respective films of the unfired film FA, the fired film FB, and the porous resin film F in the Y direction has been described as an example, but the present invention is not limited to this configuration. For example, the film may be transported in the X direction, the Y direction, the Z direction, or a combination thereof in any unit, or the transport direction may be appropriately changed in 1 unit.

Claims (26)

1. An imide resin film production system for producing a porous imide resin film, the production system comprising:

a film forming unit that forms the porous imide-based resin film by immersing a film containing polyamic acid, polyimide, polyamideimide, or polyamide, and microparticles in a first etching solution that can dissolve or decompose the microparticles, or by heating to a temperature at which the microparticles can be decomposed, thereby removing the microparticles, the porous imide-based resin film having formed therein a large number of continuous pores that penetrate in a film thickness direction;

a pre-wetting unit that supplies a pre-wetting liquid that does not dissolve the porous imide resin film to the porous imide resin film formed by the film forming unit; and

and a chemical etching unit that dissolves a part of the porous imide resin film supplied with the pre-wetting liquid, using a second etching liquid different from the first etching liquid.

2. The imide-based resin film production system according to claim 1, wherein the pre-wetting liquid has affinity with the second etching liquid.

3. The imide-based resin film production system according to claim 1 or 2, wherein the pre-wetting liquid has affinity with the porous imide-based resin film.

4. The imide-based resin film production system according to claim 2 or 3, wherein the pre-wet liquid contains an alcohol.

5. The imide-based resin film production system according to claim 4, wherein the pre-wetting liquid contains 1% to 100% of the alcohol.

6. The imide-based resin film production system according to claim 4 or 5, wherein the pre-wetting liquid contains isopropyl alcohol or ethyl alcohol.

7. The imide-based resin film production system according to claim 2 or 3, wherein the pre-wetting liquid contains a surfactant.

8. The imide-based resin film production system according to claim 2 or 3, wherein the pre-wetting liquid contains a glycol-based substance.

9. The imide-based resin film production system according to any one of claims 1 to 8, wherein the second etching solution is an aqueous liquid containing tetramethylammonium hydroxide.

10. The imide-based resin film production system according to claim 9, wherein the second etching solution contains less than 25% of tetramethylammonium hydroxide.

11. The imide-based resin film production system according to any one of claims 1 to 10, wherein the pre-wetting liquid used in the pre-wetting unit is mixed in the second etching liquid.

12. The imide-based resin film production system according to any one of claims 1 to 11, wherein the pre-wetting unit has a storage section for storing the pre-wetting liquid to impregnate the porous imide-based resin film.

13. The imide-based resin film production system according to claim 12, wherein the pre-wetting means has a circulating portion that recovers the pre-wetting liquid in the reservoir portion and returns the recovered pre-wetting liquid to the reservoir portion.

14. The imide-based resin film production system according to claim 12 or 13, wherein the film forming means forms the porous imide-based resin film in a band shape that can be wound into a roll,

the pre-wetting unit includes a conveying section for sequentially introducing the porous imide resin films fed out from the film forming unit and immersing the porous imide resin films in the pre-wetting liquid in the storage section without winding the porous imide resin films.

15. The imide-based resin film production system according to claim 14, wherein the transport unit transports the porous imide-based resin film immersed in the pre-wetting liquid in the storage unit to the chemical etching unit without winding.

16. The imide-based resin film production system according to claim 12 or 13, wherein the film forming means forms the porous imide-based resin film in a band shape that can be wound into a roll,

the storage section can be impregnated with a roll body in which the tape-shaped porous imide resin film is wound.

17. The imide-based resin film production system according to any one of claims 1 to 11, wherein the pre-wetting unit has a supply portion that ejects or sprays the pre-wetting liquid to the porous imide-based resin film formed by the film forming unit.

18. An imide-based resin film production method, which is a method for producing a porous imide-based resin film, comprising the steps of:

forming the porous imide-based resin film by immersing a film containing polyamic acid, polyimide, polyamideimide or polyamide, and fine particles in a first etching solution capable of dissolving or decomposing the fine particles, or by heating to a temperature capable of decomposing the fine particles, thereby removing the fine particles, the porous imide-based resin film having formed therein a large number of continuous pores penetrating in a film thickness direction;

supplying a pre-wetting liquid that does not dissolve the porous imide resin film to the porous imide resin film; and the number of the first and second groups,

and dissolving a part of the porous imide resin film supplied with the pre-wetting liquid using a second etching liquid different from the first etching liquid.

19. The method for producing an imide-based resin film as claimed in claim 18, comprising the steps of: the porous imide resin film is immersed in the pre-wetting liquid stored in a storage section.

20. The method for producing an imide-based resin film as claimed in claim 19, comprising the steps of: recovering the pre-wetting liquid in the reservoir, and returning the recovered pre-wetting liquid to the reservoir.

21. The method for producing an imide-based resin film according to claim 19 or 20, comprising the steps of:

forming the porous imide resin film in a band shape that can be wound into a roll; and the number of the first and second groups,

the porous imide resin films thus formed are sequentially introduced, and the porous imide resin films are immersed in the pre-wetting liquid in the storage section without being wound.

22. The method for producing an imide-based resin film as claimed in claim 21, comprising the steps of: and transporting the porous imide resin film immersed in the pre-wetting liquid in the storage section without winding, and dissolving a part of the porous imide resin film in the second etching liquid.

23. The method for producing an imide-based resin film as claimed in claim 19, comprising the steps of: a roll body in which the tape-shaped porous imide resin film is wound is immersed in the pre-wetting liquid stored in the storage section.

24. The method for producing an imide-based resin film as claimed in claim 18, comprising the steps of: spraying or misting the pre-wetting liquid onto the porous imide resin film.

25. The imide-based resin film production method as claimed in any one of claims 18 to 24, comprising the steps of: and dissolving a part of the porous imide resin film in the second etching solution in a state where the pre-wetting solution is attached to the porous imide resin film.

26. A separator formed of a porous imide resin film produced by the imide resin film production method according to any one of claims 18 to 24.

Images