CN110831705A - Polymer film forming apparatus, polymer film forming method, and method for manufacturing separator - Google Patents

Polymer film forming apparatus, polymer film forming method, and method for manufacturing separator Download PDF

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Publication number
CN110831705A
CN110831705A CN201880041251.0A CN201880041251A CN110831705A CN 110831705 A CN110831705 A CN 110831705A CN 201880041251 A CN201880041251 A CN 201880041251A CN 110831705 A CN110831705 A CN 110831705A
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Prior art keywords
web
slit
coating
die
solvent
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CN201880041251.0A
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木下英树
佐久间勇
守屋豪
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Toray Industries Inc
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Toray Industries Inc
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
    • B05C5/0254—Coating heads with slot-shaped outlet
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C13/00—Means for manipulating or holding work, e.g. for separate articles
    • B05C13/02—Means for manipulating or holding work, e.g. for separate articles for particular articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/04—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material to opposite sides of the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/26—Processes for applying liquids or other fluent materials performed by applying the liquid or other fluent material from an outlet device in contact with, or almost in contact with, the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/02—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber
    • B05D7/04—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber to surfaces of films or sheets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/52—Separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
  • Cell Separators (AREA)

Abstract

The polymer film forming apparatus of the present invention is characterized by comprising: a slit die (2) having a slit (7) formed therein for applying a coating liquid of a security polymer solution to a web (1) conveyed downward, and a means for bringing a coating film formed from the coating liquid applied to the surface of the web (1) into contact with a non-solvent, the slit die (2) being provided with: of slit die tip portions (8) including an upstream die tip portion (8a) and a downstream die tip portion (8b) in a transport direction of a web (1), only the upstream die tip portion (3) is in contact with the web, and members for supporting the web (1) are disposed at positions opposite to the slit die tip portions (8) without interposing the web (1).

Description

Polymer film forming apparatus, polymer film forming method, and method for manufacturing separator
Technical Field
The present invention relates to an apparatus for forming a polymer film on one surface or both surfaces of a web by applying a coating liquid containing a polymer solution on the web using a slit die, a method for forming a polymer film, and a method for producing a separator.
Background
The technique of continuously applying a coating liquid to a long sheet (hereinafter referred to as a "web") can be used, for example, in a step of applying a slurry containing an electrode active material to a metal foil serving as an electrode collector of an electric storage device or a step of forming a composite multilayer of separators for electric storage devices.
Among the energy storage devices, a nonaqueous secondary battery (lithium ion secondary battery) using a lithium-containing transition metal oxide for the positive electrode, a lithium dopable/dedoping material for the negative electrode, and a nonaqueous electrolyte for the electrolyte has a high energy density, and is therefore used as a driving power source for portable electronic devices such as mobile phones and notebook personal computers, and electric vehicles. With the demand for smaller/lighter weight and longer-term use of these devices, a need has arisen for a lithium ion secondary battery that is capable of achieving both further reduction in weight, reduction in thickness, and increase in capacity and safety.
In order to solve the above problems, various studies have been made on a separator for a lithium ion secondary battery, in which a polymer film for imparting a function is laminated on a polyolefin microporous film.
In example 1 of patent document 1, a PVDF copolymer solution was added to a tank in which two mayer rods were arranged in parallel at the bottom, and a polypropylene microporous membrane was passed through the tank from the upper part thereof at a transport speed of 3 m/min, into the tank, and between the two mayer rods, thereby applying the PVDF copolymer solution to both surfaces, and then passed into a coagulation tank without contacting with another device, and washed and dried to obtain a polymer composite membrane separator. The PVDF layer of the high-molecular composite membrane has the following advantages: the electrode has excellent adhesiveness to the electrode and electrolyte retentivity, and can satisfactorily maintain contact between the electrode and the separator interface even without the outer covering pressure of the cylindrical can or the columnar can, and can make the film outer covering possible to achieve weight reduction. In addition, in this manufacturing method, the PVDF layer has a surface-back-surface symmetric structure, and has an advantage of having the same characteristics at the positive electrode interface and the negative electrode interface.
On the other hand, lithium ion secondary batteries in recent years are required to be further thin and have higher capacity, and silicon-based materials such as Si/C, SiO, and SiO — Si — C have been proposed for the negative electrode. The silicon negative electrode has a problem of volume expansion/contraction, and in order to absorb/alleviate the volume expansion/contraction, for example, it is required to make the polymer film at the interface on the negative electrode side thicker than the positive electrode side, and to make the positive electrode side and the negative electrode side different in thickness and different in composition by enhancing adhesion. In this case, the method for producing a polymer composite membrane separator described in patent document 1 has a problem that only a surface-back symmetric structure can be produced.
In example 1 of patent document 2, a method of applying a negative electrode slurry to both surfaces of a copper foil is proposed. In this method, the web (copper foil in this case) is conveyed in a substantially horizontal direction, the 1 st coating die is disposed above the web, the 2 nd coating die is disposed below the web and at a position downstream of the 1 st coating die, and the 1 st and 2 nd coating dies are pressed into a position further than an imaginary conveying path of the web to apply tension to the web, whereby stable double-side coating can be achieved without wobbling. In this production method, since the coating dies are disposed on the front and back surfaces, respectively, it is possible to apply the coating dies having different compositions and different thicknesses, and it is conceivable to apply the coating dies to the production of the separator. Further, when a coating die is disposed below the web, it is difficult to stably form a bead of the coating liquid. In particular, a polymer film used for imparting a separator function needs to be formed into a thin layer of 1 to 5 μm, and a coating liquid having a low viscosity of about 2000mPa · s or less is used, and therefore, it is difficult to stabilize the beads of the coating liquid.
In patent document 3, since the support portion of the uncoated surface is present on the upstream side of the discharge port of the coating die, the swing of the web can be suppressed and the gap between the discharge port and the web can be uniformly maintained, but in order to control the coating thickness or the surface state, it is necessary to adjust the difference in level between the support portion of the uncoated surface of the coating die and the discharge port portion, and it is necessary to reassemble the coating die.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 4588286
Patent document 2: japanese patent laid-open publication No. 2016-36761
Patent document 3: japanese patent No. 3162026
Disclosure of Invention
The invention aims to provide a polymer film forming device, a polymer film forming method and a diaphragm manufacturing method, wherein the coating can be selectively carried out on one side of a net or can be carried out on each side with different compositions and thicknesses when the coating is carried out on two sides, and uniform and stable coating can be realized.
The polymer film forming apparatus of the present invention for solving the above problems has the following configuration. That is to say that the first and second electrodes,
(1) a polymer film forming apparatus is characterized by comprising: a slit die having a slit formed therein to apply a coating liquid containing a polymer solution to a web conveyed downward; and a unit that brings a coating film formed from the coating liquid applied to the surface of the web into contact with a non-solvent, the slit die being provided: the device is characterized in that, of slit die leading end portions including an upstream die leading end portion and a downstream die leading end portion in a web conveying direction, only the upstream die leading end portion is in contact with the web, and a member for supporting the web is arranged at a position opposite to the slit die leading end portion without interposing the web therebetween.
(2) Preferably, the two slit dies are provided with the web being conveyed therebetween, and the two slit dies are arranged so that only the upstream-side die tip portions of the two slit dies come into contact with the web, and the upstream-side die tip portions of the two slit dies are separated from each other by 1.0mm or more in the axial direction with the web conveying direction as a coordinate axis.
(3) Preferably, an angle a between the discharging direction of the slit die and the conveying direction of the web on the side where the coating liquid is discharged and applied to the web is 90 ° < a ≦ 150 °.
(4) Preferably, the means for bringing the coating film into contact with the non-solvent is one or a combination of more than one of means for spraying the non-solvent, means for applying the non-solvent, means for immersing the coating film in the non-solvent, and means for bringing the vaporized non-solvent into contact with the coating film.
The polymer film forming method of the present invention for solving the above problems has the following configuration.
That is to say that the first and second electrodes,
(5) a method for forming a polymer film by applying a coating liquid to a web using a slit die having a slit formed therein, the method comprising: applying a coating liquid to the surface of the web to form a coating film; and a step of bringing the coating film into contact with a non-solvent to cure the coating film, the slit die being provided with: only the upstream side die tip portion of slit die tip portions included in an upstream side die tip portion and a downstream side die tip portion in a transport direction of the web is in contact with the web, and a member for supporting the web is disposed at a position opposite to the slit die tip portion without interposing the web therebetween.
(6) Preferably, the coating film is formed by applying the coating liquid to both surfaces of the web by the two slit dies, wherein the two slit dies are provided with the web therebetween, and only the upstream side die tip portions of the two slit dies are in contact with the web, and the upstream side die tip portions of the two slit dies are axially separated from each other by 1.0mm or more with respect to the web conveyance direction as a coordinate axis.
(7) Preferably, an angle a formed between the discharging direction of the slit die and the carrying direction of the web on the side where the coating liquid is discharged and applied is 90 ° < a ≦ 150 °.
(8) Preferably, in the step of curing the coating film, the coating film is brought into contact with the non-solvent by one or a combination of spraying the non-solvent, coating the non-solvent, immersing the coating film in the non-solvent, and bringing the vaporized non-solvent into contact with the coating film.
(9) Preferably, the coating liquid contains inorganic particles.
(10) Preferably, the web is a polyolefin microporous membrane.
(11) Preferably, the coating liquid contains a monomer or oligomer having a weight average molecular weight of 5000 or less.
The method for manufacturing a separator according to the present invention for solving the above problems has the following configuration. That is to say that the first and second electrodes,
(12) the method for producing a separator is characterized by forming a polymer film on a web by the polymer film forming method of the present invention.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, the polymer film formed on the web can be formed on one side or both sides of the web selectively, and can be formed with different compositions and different thicknesses on both sides by stable coating with uniformity and without coating defects such as streaks and unevenness. When the present invention is applied to a separator for a lithium ion secondary battery, a separator in which polymer films suitable for a positive electrode and a negative electrode are formed can be obtained.
Drawings
Fig. 1 is a schematic view showing one embodiment of a polymer film forming apparatus in single-side coating.
Fig. 2 is a schematic view of a coating section in one-side coating.
FIG. 3 is a view showing a conventional slot die coating method without using a backup roll.
Fig. 4 is a diagram showing a conventional slit die coating method using a backup roll.
Fig. 5a is a diagram showing the slot die inclination angle a with respect to the web in the case of single-sided coating.
Fig. 5b is a diagram showing the slot die inclination angle a with respect to the web in the case of two-sided coating.
FIG. 6 is a schematic view showing one embodiment of a polymer film forming apparatus for double-side coating.
Fig. 7 is a schematic view of the coating section in the case of double-side coating.
Fig. 8 is a diagram showing one aspect of the positional relationship of two slit dies.
Fig. 9 is a view showing the coating section of comparative example 1.
Fig. 10 is a diagram showing one aspect of the positional relationship of two slit dies.
Fig. 11 is a view showing the coating section of comparative example 2.
Detailed Description
The polymer film forming apparatus, the polymer film forming method, and the method for manufacturing the separator according to the present invention will be described below, but the present invention is not limited to this comparative example.
A polymer film forming apparatus according to an embodiment of the present invention includes: a slit die having a slit formed therein to apply a coating liquid containing a polymer solution to a web conveyed downward; and a unit that brings a coating film formed from the coating liquid applied to the web surface into contact with a non-solvent, the slit die being provided: the device is provided with a member for supporting the net, which is included in the slit die tip portions of the upstream die tip portion and the downstream die tip portion in the conveying direction of the net, and which is disposed at a position opposite to the slit die tip portion without the net interposed therebetween, and only the upstream die tip portion is in contact with the net.
A polymer film forming method according to an embodiment of the present invention is a method for forming a polymer film by applying a coating liquid to a web using a slit die having a slit formed therein, the method including:
applying a coating liquid to the surface of the web to form a coating film; and
a step of curing the coating film by bringing the coating film into contact with a non-solvent,
the slit die is configured to: only the front end of the upstream side die is in contact with the mesh, among the front ends of the slit dies included in the front end of the upstream side die and the front end of the downstream side die in the conveying direction of the mesh,
at a position opposite to the tip end of the slit die, a member for supporting the web is not disposed across the web.
The method for producing a separator according to an embodiment of the present invention is characterized in that a polymer film is formed on a web by a polymer film forming method.
The web must be conveyed downward in the coating liquid application step. This is because, regardless of whether the non-solvent contact means is spraying, slit die coating, or dipping in a non-solvent storage tank, the non-solvent inevitably scatters downward, and when the conveyance direction is upward, the non-solvent partially adheres to the uncured coating layer, resulting in unevenness of the polymer film.
The "downward direction" in the web conveying direction means a direction in which the web is conveyed downward with reference to the horizontal direction, and includes not only a vertically downward direction but also an obliquely downward direction. Conversely, the direction in which the web is conveyed upward with reference to the horizontal direction is referred to as "upward", and includes not only a direction toward the vertically upward direction but also a direction toward the obliquely upward direction. In addition, with respect to a certain reference, the side of the web in the transport direction is referred to as "downstream side", and the opposite side of the web in the transport direction is referred to as "upstream side".
The relative position of the tip of the slit die means the intersection point position of an imaginary line parallel to the slit and passing through the center of the slit and a surface of the web not coated by the slit die.
Fig. 1 is a schematic view showing a slit die 2 of an application section of a polymer film forming apparatus and its periphery in the case of applying a coating liquid to one surface of a web 1 according to an embodiment of the present invention.
Fig. 2 is a schematic view of an application section in the case of applying the coating liquid to one surface of the web 1.
With respect to the web 1 conveyed downward, the back side of the coated surface of the web 1 is supported in the coating section at a position facing the coating liquid discharge port 9 without using a member for supporting the web such as a backup roll, and only the upstream side die tip portion 8a out of the slit die tip portions 8 including the upstream side die tip portion 8a and the downstream side die tip portion 8b in the web conveyance direction 17 with reference to the slit 7 of the slit die 2 is brought into contact with the web 1 to apply the coating liquid 6, thereby forming the coating film 10 on the web 1.
When a coating liquid containing a polymer solution is applied, the following constitution is essential: only the front end of the upstream side die is brought into contact with the web 1 with reference to the slit of the slit die 2, and the web 1 is supported from the back side of the coated surface without using a support roller or the like at a position facing the coating liquid discharge port 9 of the slit die, i.e., at a facing position 15 of the front end of the slit die. When a web is coated using a slit die, a backup roll for supporting the web is disposed on the back side of the coated surface in order to ensure the uniformity of the gap, but when the web is a nonwoven fabric or a polyolefin microporous film, a part or all of the components of the coating liquid containing the polymer solution may permeate into the web to contaminate the backup roll and prevent the web from being conveyed. Further, the web is supported by the support rollers, so that the distance from the front end of the slit die is easily stabilized, but the web is easily affected by the fluctuation of the roller rotation axis, the processing accuracy, and the like. When rotational chatter occurs, the distance from the front end of the slit die changes with the rotation, and thus horizontal streaks occur, which cause uneven coating. The same is true for the processing accuracy, and the influence of the roll surface roughness and the minute scratches cannot be ignored as the thickness of the web becomes thinner. Further, when a web such as a nonwoven fabric is coated, the coating liquid may penetrate through the web, adhere to a backup roll, and be solidified, and uneven thickness, coating streaks, a slit die or a roll, and web breakage may occur.
In contrast, there is a slot die coating system shown in fig. 3 in which a support roll is not used as a member for supporting the web.
The web 1 is supported and guided by a pair of guide rollers 11 disposed at a constant interval at positions on the upstream side and the downstream side of the slit die 2 in the web conveying direction 17. This is the following way: the coating is performed by discharging a necessary amount of the coating liquid from the slit die 2 disposed between the guide rollers 11 to the web. The slit die is pressed against the web continuously conveyed between the pair of guide rollers 11, and the distance between the web and the tip of the slit die can be secured and coated by the balance between the force 22 for restoring the bent web and the force 21 for pressing the web with the coating liquid discharged from the slit die. That is, in this system, the balance between the force pressing the web and the force discharging the coating liquid is important.
If the force pressing the slit die against the web is weak, the web will not be able to be loosened, resulting in uneven coating. If the force with which the die presses the web is strong, the coating liquid discharge port of the slit die is blocked, and the coating liquid cannot be stably discharged, resulting in streaks and unevenness. In the case of coating a highly stretchable web, if the force of pressing the web with the die is too strong, the web is deformed, which causes dimensional change and curling of the coated hair (web きしまり).
In addition, when the applied coating liquid passes through the web, it is also undesirable to dispose the backup roll 20 shown in fig. 4 on the non-coated side in the case of single-side coating (not necessarily in the case of double-side coating) until the coating film is cured after the coating.
In the present invention, in order to solve the above-described problems, the web slack is eliminated by bringing only the front end portion of the upstream side die of the slit die into contact with the web, and the gap between the discharge port of the coating liquid and the web can be uniformly maintained, thereby realizing stable coating. It has also been found that by inclining the slit die with respect to the web, the gap between the downstream side of the die tip and the web can be adjusted, and a stable bead 16 of the coating liquid can be formed.
The slit die 2 is divided into an upstream side die 3 and a downstream side die 4, and a liquid reservoir of a coating liquid called a manifold 5 and a slit 7 are formed inside the slit die 2 as shown in fig. 2. The cross section of the manifold 5 may be a curved line or a straight line, or may be substantially circular or semicircular as shown in fig. 2. The manifold 5 has its cross-sectional shape in the width direction of the slit die 2. The length of its effective extension is usually the same as or slightly longer than the coating width.
The slit 7 is a flow path of the coating liquid 6 from the manifold 5 to the web 1. The slit die 2 has a cross-sectional shape in the width direction thereof, as with the manifold 5. The coating liquid outlet 9 located on the web 1 side is adjusted to a width substantially equal to the coating width by using a spacer not shown. In addition, the slit gap can be adjusted by the thickness of the spacer. The coating liquid 6 extruded from the manifold 5 of the slit die 2 passes through the slit and is discharged from a coating liquid discharge port 9 at the tip of the slit die, and a coating film is formed on the web.
As shown in fig. 5a and 5b, a virtual line parallel to the slit 7 and passing through the center of the slit 7 in a cross section viewed from the lateral side of the slit die 2 can be defined as the discharge direction 19. The angle a formed between the discharge direction 19 of the slit die 2 and the transport direction of the web 1 on the side where the coating liquid is discharged and applied to the web 1 (also referred to as "slit die inclination angle with respect to the web") is preferably 90 ° < a ≦ 150 °. The slit die is preferably inclined in such a manner that the inclination angle a18 of the slit die becomes 90 DEG < a.ltoreq.150 deg. More preferably 110 DEG-a.ltoreq.150 deg. If the inclination angle a18 of the slit die is 90 ° or less, a gap between the discharge port of the coating liquid and the web cannot be secured, and if it exceeds 150 °, it is difficult to stably hold the liquid pool.
As a means for maintaining the gap between the discharge port of the coating liquid and the web, the upstream side die tip portion of the slit die tip portion may be protruded from the downstream side die tip portion and only the upstream side die tip portion may be brought into contact with each other. Therefore, the slit die preferably has no step at the tip end portion.
In the case of both-side coating, as shown in fig. 6 and 7, two slit dies 2 can be arranged for the web 1 conveyed downward without supporting the back side of the coated surface of the web 1 by a backup roll or the like at a position facing the coating liquid discharge port 9 in the coating section. With respect to one slit die 2, only the upstream die tip portion 8a is brought into contact with the web 1 with reference to the slit 7, and the 1 st coating portion for coating the coating liquid 6 can be formed. Further, on the downstream side of the 1 st coating section, in order to coat the web surface not coated by the 1 st coating section, another slit die 2 is disposed so that only the upstream side die tip portion 8a of the slit die 2 is in contact with the web 1, and the coating liquid 6 is applied to the web 1 to form a 2 nd coating section of the coating film 10.
Preferably, two slit dies are provided with a mesh interposed therebetween, the two slit dies are arranged so that only the upstream-side die tip portions are in contact with the mesh, the upstream-side die tip portions of the two slit dies are axially separated from each other by 1.0mm or more with the web conveyance direction as a coordinate axis, and the coating liquid is applied to both surfaces of the mesh by the slit dies to form a coating film.
The two slot dies may be identical in shape. The two slot dies are preferably arranged across the web. This enables coating of different compositions and thicknesses on the respective surfaces. Preferably, the two slit dies are arranged such that only the upstream-side die tip portions of the dies are in contact with the web, and the upstream-side die tip portions of the two slit dies are axially separated from each other by 1.0mm or more with respect to the web conveying direction as a coordinate axis. This is because, since the upstream side die tip portions of the slit dies are brought into contact with each other to eliminate the slack and the wobbling of the net, if the contact points between the upstream side die tip portions of the two slit dies and the net are provided at the same positions with the net interposed therebetween, the net is pinched by the upstream side die tip portions of the slit dies, and there is a possibility that the net cannot be stably conveyed, the net may be broken, and the net may be stretched.
The distance between the two slit dies is preferably such that the downstream slit die is provided so that the coating liquid is applied to the opposite surface (referred to as "B surface") of the web even before the coating liquid applied to one surface (referred to as "a surface") of the web by the upstream slit die in the web conveying direction passes through the web. If the downstream slit die is provided at a position where the coating liquid is applied to the surface B after the coating liquid applied to the surface a has passed through the web, the coating liquid passed through the surface a may be accumulated at a contact portion where the downstream slit die and the web are in contact, and the application to the surface B may be affected. From this viewpoint, the upper limit of the distance between the two slit dies is changed depending on the web conveyance speed, the penetration time of the coating liquid to the web, and the like. For example, when the web transport speed is 100m/min and the coating liquid transmission time to the web is 150msec, the upper limit of the distance between the two slit dies is 250 mm.
Further, the time for the coating liquid to permeate through the web is longer as the thickness of the web is thicker and the porosity of the web is lower. The time for the coating liquid applied to the surface a to pass through the web varies depending on the type of web, and the upper limit of the distance between the two slit dies becomes larger as the web conveyance speed is higher. In such a case, as shown in fig. 8, a roller may be disposed between the two slits. By arranging the rollers in this manner, the transport path of the web can be changed, the angle of inclination of the slit die with respect to the web can be adjusted, and the tension of the web can be controlled.
Next, means for bringing the coating liquid applied to the surface of the web into contact with a non-solvent to cure the coating liquid will be described.
As the means for bringing the coating film into contact with the non-solvent, one or a combination of more of a means for spraying the non-solvent, a means for applying the non-solvent, a means for immersing the coating film in the non-solvent, and a means for bringing the vaporized non-solvent into contact with the coating film can be applied.
As the means for spraying the non-solvent, a spray nozzle can be used, and any of a fan type, a hollow cone type, a solid cone type, and the like can be used. In addition, when the non-solvent is water, an ultrasonic atomizer can be used. As a unit for applying the non-solvent, a slit die can be used. In this case, it is preferable to arrange the two molds so as to face each other, discharge the non-solvent from each mold at equal pressure and equal amount, and pass the web between the two molds, from the viewpoint of stable web conveyance. As the means for immersing in the non-solvent, a tank in which the non-solvent for immersing the web is stored can be used, and it is most preferable from the viewpoint of uniformly curing the polymer film. For example, as shown in fig. 1 and 6, the web 1 may be supported and guided by a guide roller 11 disposed on the upstream side in the web conveying direction 17 of the slit die 2 and an in-liquid guide roller 12 disposed on the downstream side, and the web 1 may be immersed in a non-solvent tank 14 in which a non-solvent 13 is stored.
The non-solvent may contain a good solvent or a poor solvent within a concentration range capable of curing the coating film. The ratio of the non-solvent to the good solvent or the poor solvent affects the time for curing the coating film and the pore shape of the polymer film, and therefore, it is preferable to control the solvent concentration. The resin component is solidified in a three-dimensional network by contact with the non-solvent, thereby forming a polymer film. The contact time with the non-solvent is preferably 3 seconds or more. If it is less than 3 seconds, the resin component may not be sufficiently solidified. The upper limit is not limited.
Next, a case where the mesh formed with the polymer film is used for a separator for a lithium ion secondary battery will be described. Nonwoven fabric and polyolefin microporous film were used as the web. In particular, in the case of a thin, lightweight, and high-capacity separator for a lithium ion secondary battery, a polyolefin microporous membrane is preferable.
Examples of the polyolefin forming the polyolefin microporous membrane include homopolymers of ethylene and propylene, copolymers containing olefin copolymers such as ethylene, propylene, butene, hexene, pentene, methylpentene, octene, vinyl acetate, methyl methacrylate, and styrene, and mixtures thereof. In the case of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene, the shutdown temperature can be controlled to about 120 to 150 ℃.
As the polyethylene, high-density polyethylene, medium-density polyethylene, ultrahigh molecular weight polyethylene (UHMwPE), branched low-density polyethylene, linear low-density polyethylene, and a mixture thereof can be used. Among them, from the viewpoint of pore structure control of the microporous membrane, thermal properties and strength of the membrane, high-density polyethylene, ultrahigh-molecular-weight polyethylene and a mixture thereof are preferable.
The polyolefin may contain various additives such as an amorphous heat-resistant resin, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, an anti-blocking agent, a filler, a crystal nucleating agent, a crystallization retarder and the like, within a range not to lose the effects of the present invention.
The microporous polyethylene membrane may be a single-layer membrane or may be composed of two or more layers having different molecular weights or average pore diameters. The method for producing a multilayer film composed of two or more layers can be produced, for example, by any of the following methods: a method of melting and kneading the polyethylene constituting the a layer and the b layer with a forming solvent, respectively, and supplying the obtained molten mixtures from the respective extruders to one die to integrate and co-extrude gel sheets constituting the respective components, and a method of superposing and thermally melting the gel sheets constituting the respective layers. The coextrusion method is more preferable because it is easier to obtain high interlayer adhesion strength and to form a communicating pore between layers, and therefore, it is easier to maintain high permeability and excellent productivity. In the case where the polyethylene resin layer is formed of two or more layers, the molecular weight and molecular weight distribution of at least one outermost polyethylene resin preferably satisfy the above conditions.
The polymer film referred to in the present invention is a material that provides or improves at least one of functions such as heat resistance, adhesion to an electrode material, and electrolyte permeability.
Inorganic particles may be added to the coating liquid containing the polymer solution used in the embodiment of the present invention.
Examples of the inorganic particles include calcium carbonate, calcium phosphate, amorphous silica, crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide particles, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, mica, and boehmite. In particular, when a fluorine-based resin is used as the polymer, titanium dioxide, alumina, and boehmite are preferable, and alumina is more preferable, from the viewpoints of crystal growth, cost, and easiness of purchase.
The polymer solution is a solution obtained by dissolving a polymer such as a fluorine-based resin, a polyamide imide, an aromatic polyamide resin, or the like in a solvent.
The solvent is not particularly limited as long as it can dissolve the polymer, and examples thereof include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, γ -butyrolactone, acetone, and the like.
The polymer used in the embodiment of the present invention is not particularly limited as long as it can provide electrode adhesiveness, heat resistance, and electrolyte permeability, but a fluorine-based resin is preferable from the viewpoint of heat resistance and electrode adhesiveness, and among them, one or more selected from the group consisting of a vinylidene fluoride homopolymer, a vinylidene fluoride/fluoroolefin copolymer, a vinyl fluoride homopolymer, and a vinyl fluoride/fluoroolefin copolymer is preferably used. Particularly preferred are polyvinylidene fluoride resins and polyvinylidene fluoride-hexafluoropropylene copolymers. These polymers have electrode adhesion and high affinity with nonaqueous electrolytic solutions, and have high chemical stability and physical stability with respect to nonaqueous electrolytic solutions, and therefore can sufficiently maintain affinity with electrolytic solutions even when used at high temperatures.
The molecular weight of the polyvinylidene fluoride resin is an important factor for controlling the crystallinity. The lower limit of the molecular weight is preferably 0.8X 10 in terms of the weight-average molecular weight (Mw)6The upper limit is preferably 2.0X 106. When the amount is within this range, the crystallinity of the polyvinylidene fluoride resin can be easily controlled within the above preferred range. As the polyvinylidene fluoride resin, commercially available resins can be used. Examples thereof include KF polymer W #7300 and KF polymer W #9300 (manufactured by KUREHA, Inc.).
The coating liquid used in the embodiment of the present invention may contain a monomer or oligomer having a weight average molecular weight of 5000 or less.
Examples of the monomer or oligomer having a weight average molecular weight of 5000 or less include a vinylidene fluoride monomer, a hexafluoropropylene monomer, a vinylidene fluoride oligomer, and a hexafluoropropylene oligomer. The monomer or oligomer having a weight average molecular weight of 5000 or less is contained in the fluorine-based resin during the production thereof and is difficult to completely remove. According to the present invention, the above-mentioned components are preferably contained for coating of the coating liquid.
The battery separator produced by the apparatus and the production method of the present invention can be used as a battery separator for secondary batteries such as nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, lithium ion secondary batteries, and lithium polymer secondary batteries, and is particularly suitable as a separator for lithium ion secondary batteries.
Examples
The embodiments of the present invention will be specifically described, but the present invention is not limited to these examples.
(preparation of coating liquid)
As the fluorine-based resin, a polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF/HFP: 99/1 (molar ratio) and a weight average molecular weight of 100 ten thousand) was used. The fluorine-based resin, alumina particles (average particle size 1.0 μm), and N-methyl-2-pyrrolidone were each mixed in a ratio of 4: 9: 87, and dispersing the resin component in a ball type dispersing machine after the resin component is completely dissolved. Next, the coating solution (a) was prepared by filtration using a filter having a filtration limit of 7 μm.
As the fluorine-based resin, a polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF/HFP: 99/1 (molar ratio), weight average molecular weight 100 ten thousand) and N-methyl-2-pyrrolidone were mixed in a ratio of 5: 95 by weight ratio, and then the resin component was completely dissolved, and then filtered using a filter having a filtration limit of 5 μm to prepare a coating liquid (b).
(evaluation)
The evaluation was performed by using three items of thickness variation, streak/unevenness state, and a combination of thickness variation and streak/unevenness state.
1. Thickness measurement
The formed polymer film was evaluated for the degree of variation in thickness at 3 points in the width direction and at 10 points in the conveyance direction for a total of 30 points, and the lower limit thickness of the streaks/unevenness was evaluated as follows.
The thickness measurement was carried out using a spherical probe LITEMATIC (VL-50-B0.01N) manufactured by Sanfeng corporation.
◎ is more than 0% and less than 10%
○ is more than 10% and less than 15%
△ is more than 15% and less than 20%
X: more than 20 percent.
2. Streak/uneven state
The state of the coating surface immediately after coating was visually observed, and the occurrence of streaks/unevenness was evaluated as follows.
◎ no streaking/unevenness
○ the number of stripes/unevenness is 1 to 3/100 m
△ the number of stripes/unevenness is 4-10/100 m
X: streaking/unevenness was intermittently more than 10/100 m or continuously generated (fail grade).
3. Judging from the results of thickness measurement and evaluation of streak/unevenness
◎ both of them are ◎
○, ◎ and ○ or both ○
△ contains △ (none of x)
X: one of them is X.
[ example 1]
As shown in fig. 1, the following apparatus was used: in the coating section, a support roller for supporting the web is not used at a position facing the slit die with respect to the web conveyed substantially vertically downward, and the slit die is provided such that only the upstream side die tip in the web conveying direction of the slit die tip comes into contact with the web. The coating liquid (a) was applied to one surface of the web in a thickness of 10 μm, and the coated film was cured by immersing the coated film together with the web in a non-solvent bath filled with ion-exchanged water provided for curing the coated film on the downstream side in the conveying direction of the slit die, and further subjected to a water washing step of immersing the coated film in a water washing bath filled with ion-exchanged water and a hot air drying step at 50 ℃.
At this time, a polyolefin microporous film having a thickness of 10 μm was used as a web to be coated, and the web was coated at a transport speed of 10 m/min. The thickness of the resulting polymer film was 1.5. mu.m.
Coating was performed at a level such that the slit die inclination angle a with respect to the web was 110 °, 135 °, and 150 °. As a result, as shown in table 1, stable coating without coating defects such as streaks and unevenness was achieved.
Comparative example 1
The coating section was coated under the same conditions as in example 1, except that the front end of the slit die was not in contact with the web and the slit die inclination angle a with respect to the web was changed to 90 °, 110 °, 135 °, 150 °, as shown in fig. 9. As a result, as shown in Table 1, a large number of coating defects such as streaks and unevenness were generated.
[ Table 1]
[ example 2]
As shown in fig. 6, two slit dies are provided with a mesh interposed therebetween, and the upstream slit die in the conveyance direction 17 is referred to as a slit die a, and the downstream slit die is referred to as a slit die B. For a web conveyed in a substantially vertical direction, a back-up roll for supporting the web is not used in a coating section at a position opposed to a front end portion of a slit die, a device provided with a slit die A so that a front end portion of an upstream side die of the front end portion of the slit die in a web conveying direction only comes into contact with the web is used to coat a coating liquid (a) on one side with a thickness of 10 μm, a device provided with a slit die B so that a front end portion of the upstream side die of the front end portion of the slit die in the web conveying direction only comes into contact with the web is used on a downstream side in the conveying direction of the slit die A so that a back-up roll is not used in the web conveying direction only, and a coating liquid (a) is coated on one side with a thickness of 10 μm is used to coat the coating liquid (a) on one side with the web, and the coating liquid is immersed and cured in a non-solvent bath 14 filled with ion-exchanged water provided for curing the coating liquid on the downstream side in the web conveying direction of, further, the polymer film was formed by water washing by immersing in a water washing tank filled with ion-exchanged water and hot air drying at 50 ℃.
At this time, a polyolefin microporous film having a thickness of 10 μm was used as a web to be coated, and the web was coated at a transport speed of 10 m/min. The thickness of the prepared polymer film was 1.5 μm on both sides. The distance between the slit die a and the slit die B (the slit die distance 23) was set to 15mm (see fig. 10). The coating was performed at a tilt angle a of the slit dies a and B with respect to the web of 110 °, 135 °, and 150 °. As a result, as shown in table 2, stable coating without coating defects such as streaks and unevenness was also achieved in the both-side coating.
Comparative example 2
The coating section was coated under the same conditions as in example 2 except that, as shown in fig. 11, the discharge ports of the two slit dies were disposed so as to face each other with the web therebetween, the tip portions of the two slit dies were not in contact with the web, and the angle formed by the web and the slit dies was set to 90 °, 110 °, 135 °, and 150 °.
As a result, as shown in Table 2, a large number of coating defects such as streaks and unevenness were generated.
[ Table 2]
Figure BDA0002326795440000181
[ example 3]
In example 2, a polymer film was formed by coating under the same conditions as in example 2 except that the inclination angle a of the slit die a with respect to the web was 150 °, the inclination angle a of the slit die B with respect to the web was 150 °, the coating thickness applied by the slit die a and the coating thickness applied by the slit die B were 1) the coating thickness on the slit die a side/the slit die B side was 10 μm/20 μm, and 2) the coating thickness on the slit die a side/the slit die B side was 20 μm/10 μm. The thickness of the obtained polymer film was 1) 1.5 μm/3.0 μm on the slit-die a side/the slit-die B side, and 2) 3.0 μm/1.5 μm on the slit-die a side/the slit-die B side.
As a result, as shown in table 3, even when the thicknesses of both surfaces were different, stable coating without coating defects such as streaks and unevenness was achieved.
[ Table 3]
[ example 4]
A polymer film was formed by coating under the same conditions as in example 3 except that in example 3, coating liquid (a) was used as the coating liquid for the slit die a and coating liquid (B) was used as the coating liquid for the slit die B. The thickness of the obtained polymer film was 1) 1.5 μm/1.5 μm on the slit-die a side/the slit-die B side, and 2) 3.0 μm/1.0 μm on the slit-die a side/the slit-die B side.
As a result, as shown in table 4, even when the coating liquids were of different kinds on both sides, stable coating without coating defects such as streaks and unevenness was achieved.
[ Table 4]
Figure BDA0002326795440000201
Industrial applicability
The present invention can be realized for a polymer film formed on a web: the selection of single-sided formation, two-sided formation of the web, and the stable coating with uniform and non-streaking/non-uniform coating defects to achieve two-sided formation of different compositions/different thicknesses. When the present invention is applied to a separator for a lithium ion secondary battery, a separator having polymer films formed thereon suitable for a positive electrode and a negative electrode can be obtained.
The present invention has been described in detail or with reference to specific embodiments thereof, but it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
The present application is based on the japanese patent application filed on 30/8/2017 (japanese patent application No. 2017-165241), the contents of which are incorporated herein by reference.
Description of the reference numerals
1. Net
2. Slit die
3. Upstream side die
4. Downstream side die
5. Manifold
6. Coating liquid
7. Slit
8. Front end of slit die
8a. front end of upstream side die
8b. front end of downstream side die
9. Coating liquid discharge port
10. Coating film
11. Guide roller
12. Guide roller in liquid
13. Non-solvent
14. Non-solvent tank
15. Relative position of front end of slit die
16. Liquid bead of coating liquid
17. Direction of web transport
18. Angle of inclination a of the slot die
19. Discharge direction
20. Supporting roll
21. Force of coating liquid pressing web
22. Force to restore the net
23. Distance of slot die

Claims (12)

1. A polymer film forming apparatus is characterized by comprising:
a slit die having a slit formed therein to apply a coating liquid containing a polymer solution to a web conveyed downward; and
a unit for bringing a coating film formed from the coating liquid applied to the surface of the web into contact with a non-solvent,
the slit die is configured to: only the upstream side die tip portion of the slit die tip portions included in the upstream side die tip portion and the downstream side die tip portion in the web conveying direction is in contact with the web, and
a member for supporting the web is disposed at a position opposite to the tip end portion of the slit die without interposing the web therebetween.
2. The polymer film forming apparatus according to claim 1, wherein two slit dies are provided across the web to be conveyed, the two slit dies are arranged so that only the upstream-side die tip portions are in contact with the web, and the upstream-side die tip portions of the two slit dies are separated from each other by 1.0mm or more in the axial direction with the web conveying direction as a coordinate axis.
3. The apparatus for forming a polymer film according to claim 1 or 2, wherein an angle a formed by the discharge direction of the slit die and the conveying direction of the web on the side where the coating liquid is discharged and applied to the web is 90 ° < a ≦ 150 °.
4. The polymer film forming apparatus according to any one of claims 1 to 3, wherein the means for bringing the coating film into contact with the non-solvent is a combination of one or more of a means for spraying the non-solvent, a means for applying the non-solvent, a means for immersing the coating film in the non-solvent, and a means for bringing the vaporized non-solvent into contact with the coating film.
5. A method for forming a polymer film by applying a coating liquid to a web using a slit die having a slit formed therein, the method comprising:
applying a coating liquid to the surface of the web to form a coating film; and
a step of curing the coating film by bringing the coating film into contact with a non-solvent,
the slit die is configured to: only the front end of the upstream side die is in contact with the mesh, among the front ends of the slit dies included in the front end of the upstream side die and the front end of the downstream side die in the conveying direction of the mesh,
a member for supporting the web is disposed at a position opposite to the tip end portion of the slit die without interposing the web therebetween.
6. The method for forming a polymer film according to claim 5, wherein two slit dies are provided with the web therebetween, only the upstream-side die tip portions of the two slit dies are in contact with the web, the upstream-side die tip portions of the two slit dies are axially separated from each other by 1.0mm or more with the web conveyance direction as a coordinate axis, and the coating liquid is applied to both surfaces of the web by the two slit dies to form the coating film.
7. The method for forming a polymer film according to claim 5 or 6, wherein an angle a formed by the discharge direction of the slit die and the conveying direction of the web on the side where the coating liquid is discharged and applied to the web is 90 ° < a ≦ 150 °.
8. The method for forming a polymer film according to any one of claims 5 to 7,
in the step of curing the coating film, the coating film is brought into contact with the non-solvent by one or a combination of more of spraying of the non-solvent, coating of the non-solvent, dipping of the coating film in the non-solvent, and contact of the vaporized non-solvent with the coating film.
9. The method for forming a polymer film according to any one of claims 5 to 8, wherein inorganic particles are mixed in the coating liquid.
10. The method for forming a polymer film according to any one of claims 5 to 9, wherein the web is a polyolefin microporous film.
11. The method for forming a polymer film according to any one of claims 5 to 10, wherein the coating liquid contains a monomer or oligomer having a weight average molecular weight of 5000 or less.
12. A method for producing a separator, characterized in that the polymer film is formed on the web by the polymer film forming method according to any one of claims 5 to 11.
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JPH11221512A (en) * 1997-11-18 1999-08-17 Matsushita Electric Ind Co Ltd Coating device and coating method
JP2000262953A (en) * 1999-03-18 2000-09-26 Fuji Photo Film Co Ltd Coating device
CN1835809A (en) * 2003-08-14 2006-09-20 诺信公司 Nozzle and filter arrangement and system for applying a fluid containing solid particles to a substrate
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