JP2014189357A - Non-contact type support device and method for producing film-like base material with coating layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact type support device which supports a film-like base material by floatation due to gas jetting toward the conveying surface of the film-like base material and to provide a method for producing a film-like base material with a coating layer using the non-contact type support device.SOLUTION: A non-contact type support device to support a long film-like base material being conveyed in a fixed direction at a non-contact state comprises: a gas supply part to supply a gas; and a jetting part having a jetting surface to jet the gas supplied from the gas supply part toward one surface of the film-like base material. Openings having a maximum opening diameter of 5 μm or more and 150 μm or less are formed at the jetting surface and the gas permeability of the jetting surface is 15 ml/cm/sec or more and 350 ml/cm/sec or less.

Description

  The present invention relates to a non-contact type support device that supports a film-like base material in a non-contact state by ejecting gas toward one side of the film-like base material, and a coating layer using the non-contact type support device The present invention relates to a method for producing a film-like substrate.

  Conventionally, there has been known a non-contact type support device that jets gas toward one side of a film-like base material to support the film-like base material in a non-contact state. A thin metal plate having a large number of pores formed on the ejection surface of the support device is disclosed by winding a string-like object having a thickness of φ0.2 to 5.0, and Patent Document 2 discloses A non-contact type support device is disclosed in which a conical or polygonal slit-like projecting opening is formed so that the opening ratio does not exceed 3%.

  By the way, the demand for lithium ion secondary batteries that are small and light, have high energy density, and can be repeatedly charged and discharged is expected to increase in the future from the viewpoint of environmental friendliness. Lithium ion secondary batteries have a high energy density and are used in the fields of mobile phones and laptop computers. However, with the expansion and development of applications, further improvements in performance are required, such as lowering resistance and increasing capacity. And cost reduction is also required.

  Under such a background, it has been performed to enhance the function of a separator that is a member used in a lithium ion secondary battery. For example, for the purpose of imparting heat resistance to a separator for a secondary battery, a film A coating agent containing alumina having a heat resistance function is applied to the surface of the separator base material, which is a shaped base material, and dried to provide a heat resistant functional layer on the surface of the separator base material. .

JP-A-8-245028 JP 2000-16649 A

  In fields where high performance and high reliability are required, such as lithium ion secondary batteries, when a coating layer having a predetermined function is provided on a film-like substrate, it is also applied in order to fully exhibit its functions. The uniformity of the construction layer is very important.

  When supporting a film-like substrate provided with a coating layer by a conventional non-contact type support device, if the coating layer is undried, the coating layer is caused by an air flow from the ejection portion of the non-contact type support device. It was difficult to form a uniform coating layer on the film-like substrate.

  An object of the present invention is to provide a non-contact type support device capable of stably supporting a film-like substrate with a coating layer in a non-contact state without roughening the coating layer of the undried film-like substrate, and the non-contact type It is providing the manufacturing method of the film-form base material with a coating layer using a support apparatus.

  As a result of intensive studies, the inventor makes the coating layer of the film-like substrate rough by specifying the ejection surface of the non-contact support device that ejects gas toward one side of the film-like substrate. The present invention has been completed by finding that a film-like substrate with a coating layer can be supported without contact, and a film-like substrate with a coating layer having a uniform thickness can be produced. .

That is, according to the present invention,
(1) A non-contact type support device that supports a long film-like substrate conveyed along a certain direction in a non-contact state, from a gas supply unit that supplies gas, and the gas supply unit An ejection portion having an ejection surface for ejecting the supplied gas toward one surface of the film-like substrate, and an opening having a maximum aperture diameter of 5 μm or more and 150 μm or less is formed on the ejection surface, A non-contact support device, wherein the air permeability of the ejection surface is 15 ml / cm ² / sec or more and 350 ml / cm ² / sec or less,
(2) A method for producing a film-like base material using the non-contact support device according to (1), wherein the transporting step conveys a long film-like base material along a certain direction; A coating layer forming step of forming a coating layer by applying a coating agent on one or both sides of the film-like substrate being conveyed; and a drying step of drying the coating layer on the film-like substrate. The transporting step supports the film-like substrate on which the coating layer is formed by the non-contact type support device after the coating layer forming step and before the drying step. A method for producing a film-like substrate with a coating layer, comprising the coating layer and the film-like substrate, comprising a process part that is conveyed in a state of being carried out,
(3) The method for producing a film-like substrate with a coating layer according to (2), wherein the pressure inside the ejection part is controlled to 50 Pa or more and 1000 Pa or less,
(4) The coating agent has a coating layer according to (2) or (3), wherein the viscosity at a temperature of 23 ° C. and a shear rate region of 1000 (1 / s) is 2 cP or more and 80 cP or less. A method for producing a film-like substrate,
Is provided.

  According to the present invention, a non-contact type support device capable of stably supporting a film-like substrate with a coating layer in a non-contact state without roughening the coating layer of the undried film-like substrate and the non-contact type The manufacturing method of the film-form base material with a coating layer using a support apparatus can be provided. And the coating layer of the film-form base material with a coating layer obtained by this manufacturing method is excellent in uniformity, and can exhibit the function of a coating layer effectively.

It is a lineblock diagram showing the whole coating device concerning an embodiment. It is a figure which shows the structure of the chamber doctor coating device which concerns on embodiment. It is a figure which shows the cell pattern formed in the surrounding surface of the gravure roll of the chamber doctor coating device which concerns on embodiment. It is a figure which shows the structure of the non-contact-type support apparatus which concerns on embodiment.

  Hereinafter, the non-contact support device of the present invention will be described. A non-contact type support device of the present invention includes a gas supply unit that supplies a gas, and an ejection unit that has an ejection surface that ejects the gas supplied from the gas supply unit toward one side of a film-like substrate. Then, gas is ejected from the ejection surface toward one surface of the film-like substrate, and the film-like substrate is supported in a non-contact state. In addition, the said ejection surface has many small opening parts in the one surface.

  As members constituting the ejection surface of the non-contact type support device, a metal plate such as punching metal, a material in which a string-like material such as metal wire or fiber is wound or knitted, a porous metal plate, a porous synthetic material, etc. Although a resin board, a nonwoven fabric, etc. are mentioned, they may be used independently and may be used in combination. When used in combination, the member positioned on the outermost surface constituting the ejection surface of the non-contact support device is not particularly limited as long as it is within the range of the maximum opening diameter and air permeability of the ejection portion of the present invention.

  Among them, the non-woven fabric can be obtained from the market with the maximum opening diameter and air permeability within the scope of the present invention, and the non-woven fabric can be easily non-contacted by winding the non-woven fabric around the ejection surface of the existing non-contact type supporting device. It is preferable because the ejection surface of the support device can be adjusted to the maximum opening diameter and air permeability within the scope of the present invention. Nonwoven fabrics are preferred because they have little variation in opening diameter and can reduce the effect of coating layer roughness.

  The maximum opening diameter of the opening on the ejection surface of the non-contact type support device was measured using a through pore distribution measuring device (ROROLUX 1000, manufactured by Nippon Bell Co., Ltd.) in accordance with ASTM F316-86. Five test pieces of 25 mmφ were arbitrarily taken out from the member used for the ejection surface of the non-contact support device, and the average value of the five maximum opening diameters obtained by the above measurement was taken as the maximum opening diameter.

  If the measurement is difficult due to the thick member used on the ejection surface of the non-contact type support device, use a Hitachi scanning electron microscope (S-3400N, manufactured by Hitachi High Technology Co., Ltd.). And 10 arbitrary visual fields were observed, and an average value of 10 points of the maximum aperture diameter of each visual field was defined as the maximum aperture diameter. As measurement conditions, the maximum aperture diameter and the observation magnification of the electron microscope were set to have the following relationship.

When the maximum aperture diameter is 10 μm or more and less than 20 μm, the observation magnification of the electron microscope is 500 times. When the maximum aperture diameter is 20 μm or more and less than 40 μm, the observation magnification of the electron microscope is 250 times. When the maximum aperture diameter is 40 μm or more and less than 80 μm, the observation magnification of the electron microscope is 125 When the maximum aperture diameter is 80 μm or more and less than 150 μm, the observation magnification of the electron microscope is 60 times. The maximum aperture diameter is 150 μm or less, preferably 100 μm or less, more preferably 70 μm or less, further preferably 40 μm or less, and more preferably 5 μm or more, preferably It is 15 μm or more, more preferably 25 μm or more.

  Within this range, the film-like substrate can be stably supported in a non-contact state while suppressing the roughness of the coating layer of the film-like substrate.

  The measurement of the air permeability of the ejection surface of the non-contact type support device is based on JIS L 1096 A method (Fragile type method) using a Fragile type air permeability tester (AP-360S, manufactured by Daiei Kagaku Seiki Seisakusho). I went. A five-point test piece was arbitrarily taken out from the material used for the ejection surface of the non-contact support device, and the average value of the five points of the air permeability obtained by the above measurement was taken as the air permeability.

The air permeability is 350 ml / cm ² / sec or less, preferably 200 ml / cm ² / sec or less, more preferably 100 ml / cm ² / sec or less, further preferably 70 ml / cm ² / sec or less, and 15 ml / cm ² / Sec or more, preferably 25 ml / cm ² / sec or more, more preferably 35 ml / cm ² / sec or more.

  Within this range, the film-like substrate can be stably supported in a non-contact state while suppressing the roughness of the coating layer of the film-like substrate.

  In addition, the shape of the non-contact type support device is not particularly limited as long as it is a structure capable of transporting a film-like base material in a non-contact manner. The shape such as can be selected.

    The pressure inside the ejection part of the non-contact type support device is preferably 50 Pa or more, more preferably 100 Pa or more, preferably 1000 Pa or less, more preferably 800 Pa or less, still more preferably 500 Pa or less, particularly preferably 300 Pa or less. is there.

  The pressure inside the ejection part of the non-contact type support device can be measured by a pressure gauge (digital pressure sensor AP-C30, manufactured by Keyence Corporation) connected to the ejection part of the non-contact type support device.

  By setting the pressure inside the ejection part of the non-contact type support device within the above range, it is possible to stably transport the film substrate while suppressing the roughness of the coating layer of the film substrate before drying. It becomes. If the pressure is less than the lower limit, it is difficult to stably float the film-like substrate, and the coating layer and the ejection surface of the non-contact support device may come into contact with each other and the coating layer may be damaged. If the pressure exceeds the upper limit value, the coating layer of the base material tends to be rough due to the airflow from the ejection surface of the non-contact type support device, and is closest to the non-contact type support device. In the coating layer forming step, the film-like substrate is likely to vibrate, and it becomes difficult to uniformly apply the coating agent to the film-like substrate.

  In the case of producing a film-like substrate with a coating layer using the non-contact type support device of the present invention, the effect of the present invention can be exhibited even if the number of non-contact type support devices arranged is one. It is preferable to use a plurality of non-contact type support devices because the stability of material conveyance can be further improved and the coating agent can be uniformly applied to the film-like substrate. In the case of using a plurality of non-contact type support devices, in the upstream non-contact type support device upstream of the base material transport direction and the downstream non-contact type support device downstream of the base material transport direction closest to the upstream non-contact type support device, The downstream non-contact type support device is configured such that the downstream non-contact type support device has a surface opposite to the surface of the film-like substrate opposite to the ejection surface of the upstream non-contact type support device. It is preferable to arrange the ejection surfaces to face each other.

  The non-contact type support device of the present invention is used to form a coating layer on one side or both sides of a film-like substrate, and particularly preferably used to form a coating layer on both sides of a film-like substrate. When forming a coating layer on both surfaces of a film-like substrate using the non-contact support device of the present invention, the vibration of the film-like substrate due to the influence of wind or the like in the drying process is suppressed and applied to the film-like substrate. In addition to being able to coat the coating agent uniformly, it is preferable because the film-like substrate with a double-sided coating layer can be produced with a simple facility with a single drying step for drying the coating layer.

  Next, the coating agent applied to the film-like substrate used in the present invention will be described. In order to impart a function to the film-like substrate, the film-like substrate is usually coated with a coating agent containing a substance that imparts functionality. The viscosity of the coating agent is preferably 2 cP or more, more preferably 5 cP or more, particularly preferably 15 cP or more, preferably 80 cP or less, more preferably from the viewpoint of forming a uniform coating layer on the film-like substrate. 50 cP or less, particularly preferably 25 cP or less. The viscosity of the coating agent is a viscosity measured at a temperature of 23 ° C. and a shear rate region of 1000 (1 / s) using a viscosity / viscoelasticity measuring device (Rheostress HAAKE RS6000, manufactured by Eihiro Seiki Co., Ltd.).

  When the viscosity of the coating agent is less than the lower limit, when the film-like substrate with the coating layer is supported by the non-contact type support device, it is undried by the air current from the ejection surface of the non-contact type support device. When the coating layer is easily roughened and the viscosity of the coating agent exceeds the upper limit, it is difficult to uniformly apply the coating agent to the film-like substrate.

  The coating agent contains a substance that imparts functionality, a solvent, and other substances as necessary. The substance imparting functionality to the separator can be appropriately selected according to the function to be imparted to the film-like base material. For example, when it is desired to impart heat resistance to the film-like base material, the coating agent has a heat-resistant substance. When a coating agent containing is selected and it is desired to impart adhesiveness to the film-like substrate, a coating agent containing an adhesive substance in the coating agent is selected.

  As the heat resistant substance, for example, inorganic particles and organic particles can be used. As inorganic particles, oxide particles such as aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, BaTiO2, ZrO, alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; sharing of silicone, diamond, etc. Bonding crystal particles; sparingly soluble ionic crystal particles such as barium sulfate, calcium fluoride, and barium fluoride; clay fine particles such as talc and montmorillonite are used. These particles may be subjected to element substitution, surface treatment, solid solution, or the like, if necessary, or may be a single or a combination of two or more.

  The organic particles have a melting temperature of preferably 130 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 180 ° C. or higher. Specifically, cross-linked polymethyl methacrylate, cross-linked polystyrene, cross-linked polydivinylbenzene, styrene-divinylbenzene copolymer cross-linked product, polyimide, polyamide, polyamideimide, melamine resin, phenol resin, benzoguanamine-formaldehyde condensate, etc. Examples thereof include crosslinked polymer particles, heat-resistant polymer particles such as polysulfone, polyacrylonitrile, polyaramid, polyacetal, and thermoplastic polyimide. The organic resin (polymer) constituting these organic particles is a mixture, modified body, derivative, or copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the materials exemplified above. Polymer) or a crosslinked product (in the case of the above-mentioned heat-resistant polymer).

  The adhesive substance usually has a glass transition temperature of 10 ° C. or higher, preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and usually 110 ° C. or lower, preferably 100 ° C. or lower, more preferably 90 ° C. or lower. A particulate polymer is used. When the glass transition temperature of the particulate polymer is equal to or higher than the lower limit, the softening of the particulate polymer can be suppressed at the time of storage, transportation and handling of the film-like substrate, and blocking can be prevented. Moreover, the heat resistance of a contact bonding layer improves by using a particulate polymer with a high glass transition temperature. Moreover, when the glass transition temperature of a particulate polymer is below the said upper limit, when bonding a film-like base material to a target object, a particulate polymer can be easily softened with a heat | fever.

  The average particle size (volume average D50 average particle size) of the substance imparting functionality is usually 0.1 μm or more, preferably 0.2 μm or more, and usually 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less. It is. By setting the average particle diameter in the above range, it becomes easy to obtain a film having a predetermined thickness that is uniform in controlling the dispersion state.

  The solvent is not particularly limited as long as the solid content in the coating agent can be uniformly dispersed. As the solvent, either water or an organic solvent can be used. Organic solvents include toluene, xylene, methylene chloride, chloroform, pyridine, acetone, dimethylformamide, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, n-butyl phthalate, tetrahydrofurfuryl alcohol, ethyl acetate, carbon disulfide, cyclohexane, cyclopentane, methyl Examples include cyclohexane and N-methylpyrrolidone. These solvents can be used alone or as a mixed solvent.

  Examples of other substances include, but are not limited to, binders, thickeners, and surfactants.

  Examples of the binder include a diene polymer, an acrylic polymer, a fluorine polymer, a silicone polymer, and a maleimide-maleic anhydride copolymer. Examples of the thickener include water-soluble polysaccharides such as carboxymethylcellulose, sodium polyacrylate, polyethyleneimine, polyvinyl alcohol, and polyvinylpyrrolidone.

   The solid content concentration of the coating agent is not particularly limited as long as it is a concentration that provides a viscosity at which the coating agent can be applied, but is usually 10% by mass or more and 60% by mass or less.

  The mixing device for uniformly mixing and adjusting the coating agent is not particularly limited as long as it can uniformly mix the above components. A ball mill, sand mill, pigment disperser, crusher, ultrasonic disperser, homogenizer, planetar Lee mixer etc. can be used.

  It does not specifically limit as a elongate film-form base material used by this invention, A resin film, a resin porous film, a metal film, a metal porous film, a nonwoven fabric etc. can be used. Among these, a resin porous film is preferably used in the present invention, and among them, a secondary battery separator substrate is preferably used in the present invention.

  The width of the film-like substrate is not particularly limited, but is usually 300 mm or more and 5000 mm or less in the TD direction. The thickness of the film-like substrate is usually 0.5 μm or more and 1000 μm or less, and when the film-like substrate is a secondary battery separator substrate, it is preferably 1 μm or more, more preferably 5 μm or more, Preferably it is 50 micrometers or less, More preferably, it is 30 micrometers or less, More preferably, it is 20 micrometers or less.

  The length of the film substrate in the substrate conveyance direction (MD direction) is not particularly limited, but is usually 10 times or more the width of the film substrate.

  The strength of the film-like substrate is not particularly limited, but when the film-like substrate is a secondary battery separator substrate, the tensile elastic modulus in the substrate transport direction is usually in the range of 400 MPa to 2000 MPa. . Since the strength of the separator base material is weak, when the force more than necessary is applied, the separator base material is deformed and wrinkles are generated or the coating layer is easily damaged. The tensile modulus of the base material is determined by using a tensile tester (Autograph AGS-5KNG, manufactured by Shimadzu Corporation) at 23 ° C., 50 mm between chucks, 5 mm sample width, 12 μm sample thickness, and 50 mm / min speed. This is a value calculated from the slope at a stress of 10 to 25 MPa in the stress-strain curve when measured by.

  In the present invention, the method for applying the coating agent to the film-like substrate is not particularly limited, and a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, etc. Can be used. Of these, the gravure method is preferable, and the gravure method includes a direct method in which the gravure roll advances in the same direction as the substrate conveyance direction and a reverse method in which the gravure roll advances in the reverse direction, and the backup roll is pressed against the gravure roll. There is a kiss method that does not have a backup roll. A combination of these methods can also be employed. Among them, the reverse kiss method is preferable because the coating agent can be uniformly applied to the film-like substrate even when applied at high speed.

  Further, the sealing unit includes a coating unit having a sealed chamber for supplying the coating agent to the gravure roll, and a coating agent supply means for supplying the coating agent in a coating agent liquid reservoir formed in the sealed chamber. In addition to sealing the downstream part of the gravure roll rotation direction of the coating liquid reservoir, the doctor blade for removing the excess coating agent adhering to the gravure roll, and the seal sealing the upstream part of the gravure roll rotation direction of the coating liquid reservoir It is preferable to use a so-called chamber doctor system including a plate. In the case of the chamber doctor method, it is difficult for air bubbles to be mixed into the coating layer and the coating amount is stable, so that the coating agent can be uniformly applied to the substrate.

  The cell pattern of the gravure roll is preferably a continuous one, and for example, a concave portion having a helical ring shape or a concave portion having a continuous geometric pattern such as a turtle shell type or a lattice type may be used.

  In this invention, the tension | tensile_strength of a film-form base material at the time of conveying a film-form base material is normally controlled to 10 N / m or more and 1000 N / m or less. In particular, when the film substrate is a separator substrate for a secondary battery, the tension of the separator substrate is preferably 15 N / m or more, more preferably 30 N / m or more, further preferably 50 N / m or more, preferably Is controlled to 150 N / m or less, more preferably 130 N / m or less, and still more preferably 100 N / m or less.

  The tension of the film-like substrate is measured using a tension detector (formal displacement tension detector LX-015TD-909, manufactured by Mitsubishi Electric Corporation). The place where the tension of the film-like base material is measured is between the base material unwinding or feeding drive roll upstream in the base material transport direction and the base material winding or take-up drive roll downstream in the base material transport direction. Although there is no particular limitation on the measured tension, there is no particular limitation. Specifically, the substrate feeding (or unwinding) driving roll upstream of the substrate transport direction and the substrate feeding (or unwinding) driving are described above. The tension | tensile_strength of the film-form base material between the contact type guide rolls downstream in the base material conveyance direction nearest to the roll was measured. In the case where the drive roll for feeding the substrate is not used, the unwinding drive roll for the substrate and the contact guide roll downstream in the substrate transport direction closest to the unwind drive roll for the substrate In the meantime, the tension of the film-like substrate is measured.

  The drive roll is a roll that rotates itself by the power of a motor or the like, and the contact-type guide roll is not a roll that rotates itself by the power of a motor or the like. The roll rotates with the contact of the roll.

  The drive roll is roughly divided into a drive roll for feeding and taking out a base material, and a drive roll for feeding and taking up a base material. Examples of the driving roll for feeding and taking out the base material include a nip roll that sandwiches and transports the base material between the rolls, and a suction roll that grips and transports the base material by suction from a porous hole on the roll surface. Examples of the drive rolls for unwinding and winding the substrate include drive rolls for unwinding and winding the substrate in which the shaft rotates to unwind and wind the substrate.

  The tension of the film-like substrate can be adjusted by adjusting the rotational speed of the drive roll for unwinding or feeding the substrate upstream in the transport direction of the substrate and the drive roll for winding or pulling the substrate downstream in the transport direction of the substrate. .

  In addition, it is possible to carry out from unwinding to winding of the film-like substrate using only the drive roll for unwinding the substrate and the drive roll for winding the substrate. It is preferable to use a drive roll for feeding or taking out the substrate. When using a drive roll for feeding and taking out a base material, a drive roll for feeding the base material and a drive roll for taking up the base material are arranged at the most upstream and downstream, respectively, with respect to the transport direction of the base material. A drive roll for feeding the substrate is arranged downstream of the roll in the substrate conveyance direction, and a drive roll for taking up the substrate is arranged upstream of the substrate take-up drive roll in the conveyance direction of the substrate. The place for measuring the tension of the film-like substrate in this case is performed between the drive roll for feeding the substrate upstream in the substrate conveyance direction and the drive roll for taking the substrate downstream in the substrate conveyance direction.

  When the tension of the film-like substrate is within the above range, the vibration of the film-like substrate can be suppressed, and the coating agent can be uniformly applied to the film-like substrate. If the tension of the film-like substrate is less than the lower limit, the vibration of the film-like substrate becomes large and it becomes difficult to uniformly apply the coating agent to the film-like substrate. In particular, when the film-shaped substrate is a separator substrate for a secondary battery, when the tension exceeds the upper limit, the film-shaped substrate may be stretched and wrinkled to damage the coating layer.

    The thickness of the coating layer on one side of the film-like substrate before drying is appropriately set according to the thickness of the coating layer of the film-like substrate after drying, but is usually 0.1 μm or more and 200 μm or less. Is the thickness.

  Examples of the drying step include drying with warm air, hot air, and low-humidity air, and drying methods by irradiation with (far) infrared rays or electron beams. Of these, drying with warm air is preferable because the coating layer can be efficiently dried and the film-like substrate is unlikely to shrink. The temperature of the hot air is appropriately set depending on the type of solvent used, the drying time, and the like. However, since the film-like substrate may cause thermal shrinkage, it is usually 100 ° C. or lower, preferably 80 ° C. or lower, more preferably It is 60 degrees C or less.

  The thickness of the coating layer on one side of the film-like substrate after drying is not particularly limited, and is usually 0.1 μm or more and 50 μm or less. When the film-like substrate is a secondary battery separator substrate, it can be set as appropriate according to the functions required of the secondary battery separator, but if it is too thin, a uniform coating layer cannot be formed, and the thickness If the amount is too large, the capacity per volume (mass) in the battery is reduced, so that it is preferably 0.3 μm or more, more preferably 1 μm or more, preferably 20 μm or less, more preferably 10 μm or less.

  In the method of the present invention, a secondary battery separator base material with a coating layer is obtained using a secondary battery separator base material as a film-like base material, and the secondary battery separator base material with a coating layer is used. When manufacturing a secondary battery, there are no particular restrictions on how it is used.For example, a positive electrode and a negative electrode are overlapped via a separator, and this is wound into a battery container according to the shape of the battery. Then, a secondary battery can be obtained by a method in which an electrolytic solution is poured into a battery container and sealed. If necessary, an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like can be inserted to prevent an increase in pressure inside the battery and overcharge / discharge. The shape of the battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape and the like.

  With reference to FIGS. 1-4, one Embodiment of the coating device using the non-contact support apparatus of this invention is described. FIG. 1 is a block diagram showing the entire coating apparatus for producing a film-like substrate with a coating layer using the non-contact support apparatus of the present invention. As shown in FIG. 1, the coating apparatus 1 includes a substrate unwinding drive roll 2 around which a separator substrate 100 that is a long film-shaped substrate is wound, a suction roll 8 that is a substrate feeding drive roll, Chamber doctor coating device 3 for applying a coating agent to one surface of separator substrate 100, and chamber doctor coating device for applying a coating agent to the other surface of separator substrate 100 4, a non-contact support device 5 that supports the separator substrate 100 in a non-contact manner, a drying furnace 6 that dries the coating agent applied to the separator substrate 100, a suction roll 9 that is a substrate take-up drive roll, and A base material take-up drive roll 7 for winding up a separator base material (heat-resistant separator) 100 coated with a coating agent is provided.

  The chamber doctor coating apparatus 3 applies a coating agent to one surface of the separator substrate 100, and comes into contact with the conveyed separator substrate 100 so that the coating agent is applied to the surface of the separator substrate 100. A gravure roll 10 for transferring the coating, and a coating chamber 11 for applying a coating agent to the gravure roll 10. The coating agent is supplied to the coating chamber 11 from a coating agent supply device (not shown).

  As shown in FIG. 2, the chamber doctor coating device 3 rotates the gravure roll 10 in the direction opposite to the conveying direction of the separator base material 100 while bringing the gravure roll 10 into contact with the separator base material 100, thereby separating the separator A coating agent is applied to one surface of the substrate 100. The gravure roll 10 has, for example, a roll main body 10a composed of a steel pipe or the like, and rotating shafts 10b provided at both ends of the roll main body 10a. A predetermined cell pattern 10c (see FIG. 3) such as a symmetrical lattice pattern is formed on the peripheral surface of the roll body 10a.

  The coating chamber 11 includes a liquid reservoir 11 a in which an opening extending in the direction of the rotation axis 10 b of the gravure roll 10 is formed on a surface facing the peripheral surface of the gravure roll 10. An upper blade 11b made of a plate member made of polyethylene, reinforced polyester, or the like is attached to the upper end edge of the opening of the coating chamber 11, that is, the opening edge downstream in the rotation direction of the gravure roll. A lower blade 11c made of a plate member formed of polyethylene, reinforced polyester, or the like is attached to the lower end edge of the opening, that is, the opening edge upstream in the rotation direction of the gravure roll.

  The tip of the upper blade 11b and the tip of the lower blade 11c are pressed against the peripheral surface of the gravure roll 10, respectively, to seal the upper and lower edges of the opening so that the liquid reservoir 11a is sealed. Configured to maintain. The upper blade 11b is applied to the peripheral surface of the gravure roll 10 by scraping off the excess coating agent applied to the peripheral surface of the gravure roll 10 in the liquid reservoir 11a according to the rotation of the gravure roll 10. It has a function of uniformly setting the thickness of the coating layer. The lower blade 11c scrapes off bubbles existing in the coating pattern 10c of the gravure roll 10 in accordance with the rotation of the gravure roll 10 and effectively prevents the bubbles from entering the liquid pool 11a in the coating chamber 11. It has a function to do. The chamber doctor coating device 4 applies a coating agent to the other surface of the separator substrate 100. Since the configuration is the same as the configuration of the chamber doctor coating device 3, the configuration is explained. Omitted.

  The non-contact support device 5 has a configuration in which a non-woven fabric 32 is attached to a conveyance surface having a plurality of small openings for ejecting air to form an ejection surface 30 (see FIG. 4). The non-contact support device 5 supports the separator base material 100 in a non-contact manner while changing the transport direction, and transports the separator base material 100 to the drying furnace 6.

  The drying furnace 6 can perform drying by circulating hot air, and can set the temperature and air volume of the hot air. In the drying furnace 6, the coating layer applied to the separator substrate 100 is dried while the separator substrate 100 is supported by a floating support and conveyed. That is, hot air having a pressure of 50 to 350 Pa and a wind speed of 10 to 25 m / s is ejected from the floating nozzles 60 arranged above and below the separator substrate 100 to support the separator substrate 100 in a floating manner. The coated layer is dried.

  Next, the manufacturing method of a heat-resistant separator is demonstrated. The separator substrate 100 unwound from the substrate unwinding drive roll 2 by the suction roll 8 is conveyed to the chamber doctor coating device 3 via the guide roll 20. At this time, the unwinding drive roll 2 adjusts the speed by tension control so as to match the feed speed of the suction roll 8. In the chamber doctor coating apparatus 3, a coating agent is applied to one surface of the separator base material 100. The separator base material 100 on which the coating agent is applied on one surface is supported by the guide roll 20 on the other surface on which the coating agent is not applied, and is conveyed to the chamber doctor coating device 4. In the chamber doctor coating device 4, the coating agent is applied to the other surface of the separator substrate 100.

  Here, in the gravure roll 10 of the chamber doctor coating apparatuses 3 and 4, when a symmetrical grid pattern is formed as the cell pattern 10 c, the coating agent is applied to the separator substrate 100 by the gravure roll 10. When coating is performed, a force in the left-right direction hardly acts on the separator substrate 100 from the gravure roll 10. Therefore, when applying to the separator base material 100 in the chamber doctor coating devices 3 and 4, the separator base material 100 is unlikely to vibrate in the width direction of the separator base material.

  The separator base material 100 coated with the coating agent on both sides is conveyed to the drying furnace 6 via the non-contact type support device 5. Here, since the non-contact type support device 5 has the non-woven fabric 32 attached to the base material transport surface to form the ejection surface 30, the air pressure per area can be made uniform, and the air ejected from the non-contact type support device 5. The surface roughness of the coating layer coated on the separator substrate 100 can be suppressed. In the drying furnace 6, the coating layer is dried. Here, since there is a non-contact type support device 5 that supports the separator base material 100 in a non-contact manner while changing the transport direction of the separator base material 100 between the drying furnace 6 and the chamber doctor coating device 4, drying is performed. The vibration generated in the separator base material 100 in the furnace 6 can be prevented from being directly transmitted to the chamber doctor coating device 4, and the occurrence of uneven coating can be prevented. The separator base material 100 (heat-resistant separator) after drying of the coating agent is taken up by the suction roll 9 through the guide roll 20 and taken up by the base material take-up drive roll 7. At this time, the base material take-up drive roll 7 adjusts the speed by tension control so as to match the take-up speed of the suction roll 9.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples. The measuring method of various measured values in this invention is shown below.
(Maximum diameter of ejection surface of non-contact type support device)
The maximum opening diameter of the opening on the ejection surface of the non-contact type support device was measured using a through pore distribution measuring device (ROROLUX 1000, manufactured by Nippon Bell Co., Ltd.) in accordance with ASTM F316-86. Five test pieces of 25 mmφ were arbitrarily taken out from the member used for the ejection surface of the non-contact support device, and the average value of the five maximum opening diameters obtained by the above measurement was taken as the maximum opening diameter.
(Air permeability of ejection surface of non-contact type support device)
The measurement of the air permeability of the ejection surface of the non-contact type support device is based on JIS L 1096 A method (Fragile type method) using a Fragile type air permeability tester (AP-360S, manufactured by Daiei Kagaku Seiki Seisakusho). I went. A five-point test piece was arbitrarily taken out from the material used for the ejection surface of the non-contact support device, and the average value of the five points of the air permeability obtained by the above measurement was taken as the air permeability.
(Pressure inside the ejection part of the non-contact type support device)
The pressure inside the ejection part of the non-contact type support device was measured by a pressure gauge (digital pressure sensor AP-C30, manufactured by Keyence Corporation) connected to the ejection part of the non-contact type support device.
(Viscosity of coating agent)
The viscosity of the coating agent applied to the separator substrate is set to a temperature of 23 ° C. and a shear rate region of 1000 (1 / s) using a viscosity / viscoelasticity measuring device (Rheostress HAAKE RS6000, manufactured by Eihiro Seiki Co., Ltd.). Measured.
(Evaluation of coating layer uniformity)
For the uniformity of the coating layer, a heat resistant layer is formed using a device in which a blue laser focus displacement meter (LT-9510VM, manufactured by Keyence Corporation) is attached to a high-precision shape measurement system (KS-100, manufactured by Keyence Corporation). A test piece having a size of 50 mm × 50 mm was prepared from the film-like substrate, and the total thickness of the test piece was measured. The difference between the largest film thickness in the MD direction and the smallest film thickness (μm) in the MD direction was calculated. The value was applied to the following criteria A to D, and the uniformity of the separator coating layer was evaluated.

A: The difference between the maximum thickness and the minimum thickness is less than 0.2 μm B: The difference between the maximum thickness and the minimum thickness is 0.2 μm or more and less than 0.3 μm C: The difference between the maximum thickness and the minimum thickness is 0.3 μm or more and less than 0.5 μm D: The difference between the maximum thickness and the minimum thickness is 0.5 μm or more (heat resistance evaluation)
A test piece having a size of 50 mm × 50 mm is prepared from a film-like substrate on which a heat-resistant layer is formed. The test piece is placed in a dryer and heated at 150 ° C. for 60 minutes under nitrogen. From the length of the test piece before and after heating. The heat shrinkage rate was calculated. The value was applied to the following criteria A to D, and the heat resistance of the film-like substrate was evaluated.

  In addition, the value of the heat shrinkage rate was the value of the largest shrinkage rate of the test piece, and the evaluation was performed according to the following criteria. A small heat shrinkage rate indicates excellent heat resistance. For example, when a secondary battery is created using a secondary battery separator substrate for a film-like substrate, the secondary battery has battery characteristics such as cycle characteristics. Excellent.

A: The heat shrinkage rate is less than 1% B: The heat shrinkage rate is 1% or more and less than 5% C: The heat shrinkage rate is 5% or more and less than 10% D: The heat shrinkage rate is 10% or more (Adhesion evaluation)
A film-like base material on which an adhesive layer is formed is cut out to a size of 50 mm × 50 mm, and this is overlaid with an electrode having an electrode active material layer of a size of 40 mm × 40 mm, and 90 ° C., 0.5 MPa, After pressing in seconds, the test piece was cut into a size of 10 mm × 10 mm.
Using a peel tester consisting of a weighted measuring machine (digital force gauge ZP-5N, manufactured by Imada Co., Ltd.) and a measuring stand (electric measuring stand MX2-500N, manufactured by Imada Co., Ltd.), the electrode of the test piece was used as a test bench. In the fixed state, one end of the separator was pulled in the vertical direction at a pulling speed of 50 mm / min, and the stress was measured. The measurement was performed three times, and the average value was applied to the following criteria A to D to obtain an adhesive evaluation value.

A: 100 N / m or more B: 75 N / m or more, less than 100 N / m C: 50 N / m or more, less than 75 N / m D: Less than 50 N / m

(Coating equipment)
The coating apparatus shown in FIGS. 1-4 was used. The ejection surface of the non-contact type support device is a non-woven fabric made of polyester having a maximum opening diameter of 25 μm and an air permeability of 55 ml / cm ² / sec, and the non-contact type support device has one configuration. The coating part was a chamber doctor type, and the gravure roll used had a concave part of a symmetrical lattice continuous pattern in the cell pattern.
(Creation of coating agent)
100 parts of alumina particles (volume average D50 average particle size 0.45 μm) as a heat-resistant substance, 1.5 parts of an aqueous solution of maleimide-maleic anhydride copolymer as a binder based on solid content, and ion-exchanged water An aqueous dispersion A was obtained by mixing so that the solid content concentration was 40% by mass. Further, 4 parts of the aqueous dispersion A and 0.2 part of a polyethylene glycol type surfactant were mixed to produce a coating agent A containing a heat-resistant substance. Moreover, the viscosity of the coating agent A was 23 cP.
(Production and evaluation of heat-resistant film)
As a film-like substrate, a separator substrate for a secondary battery made of polyethylene (thickness 12 μm, MD direction elastic modulus 1057 MPa, air permeability 230 s / 100 cc) is used, and the thickness of the heat-resistant layer of the film-like substrate is 3 μm. The film-like substrate position with respect to the gravure roll is adjusted so that the tension of the film-like substrate is 100 N / m, the coating speed is 100 m / min, the pressure inside the ejection part of the non-contact type support device is 250 Pa, the temperature of the drying furnace Under the condition of an air temperature of 50 ° C., the coating agent A was applied to both sides of the film-like substrate and dried to obtain a film A having a heat-resistant layer having a thickness of 3 μm on both sides of the film-like substrate. . Table 1 shows the evaluation of the uniformity of the heat-resistant layer of film A and the evaluation of heat resistance.

  In addition, evaluation of the uniformity of the coating layer of the separator in a table | surface is the coating layer coated with the downstream gravure roll downstream of a base material conveyance direction among the two gravure rolls which coat both surfaces of a film-form base material. The evaluation of the coating layer applied by the upstream gravure roll upstream in the substrate conveyance direction was “A”.

(Production and evaluation of heat-resistant film)
In Example 1, the film B was formed in the same manner as in Example 1 except that the ejection surface of the non-contact support device was a non-woven fabric made of polyester having a maximum opening diameter of 70 μm and an air permeability of 200 ml / cm ² / sec. Obtained. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of film B and the evaluation of heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Production and evaluation of heat-resistant film)
In Example 1, a film C was obtained in the same manner as in Example 1 except that the pressure inside the ejection part of the non-contact support device was set to 800 Pa. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of film C and the evaluation of heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Production and evaluation of heat-resistant film)
In Example 2, a film D was obtained in the same manner as in Example 1 except that the pressure inside the ejection portion of the non-contact support device was set to 800 Pa. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film D and the evaluation of the heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Production and evaluation of heat-resistant film)
In Example 1, a film E was obtained in the same manner as in Example 1 except that the pressure inside the ejection part of the non-contact support device was set to 100 Pa. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film E and the evaluation of the heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Production and evaluation of heat-resistant film)
In Example 2, a film F was obtained in the same manner as in Example 1 except that the pressure inside the ejection part of the non-contact support device was set to 100 Pa. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film F and the evaluation of the heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Creation of coating agent)
A coating agent B containing a heat-resistant substance was produced in the same manner as in Example 1 except that the amount of ion-exchanged water added in Example 1 was changed so that the solid content concentration was 30% by mass. Moreover, the viscosity of the coating agent B was 5 cP.
(Production and evaluation of heat-resistant film)
A film G was obtained in the same manner as in Example 1, except that the coating agent B was used in place of the coating agent A in Example 1. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film G and the evaluation of the heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Creation of coating agent)
In Example 1, coating agent C containing a heat-resistant substance was produced in the same manner as in Example 1 except that the amount of ion-exchanged water added was changed so that the solid content concentration was 50% by mass. Moreover, the viscosity of the coating agent C was 50 cP.
(Production and evaluation of heat-resistant film)
A film H was obtained in the same manner as in Example 1 except that the coating agent C was used in place of the coating agent A in Example 1. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film H and the evaluation of the heat resistance. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

(Creation of coating agent)
In Example 1, 100 parts of a particulate adhesive substance of a crosslinked polymer of butyl acrylate / methacrylic acid / styrene (glass transition temperature 76 ° C., volume average particle diameter D50 0.15 μm), maleimide as a binder A coating agent D containing an adhesive substance was obtained by mixing an aqueous solution of maleic anhydride copolymer in an amount of 4 parts on the basis of the solid content and ion-exchanged water so that the solid content concentration was 20%. Moreover, the viscosity of the coating agent D was 15 cP.
(Manufacture and evaluation of adhesive films)
A film I was obtained in the same manner as in Example 1 except that the coating agent D was used in place of the coating agent A in Example 1. Table 1 shows the evaluation of the uniformity of the adhesive layer of film I and the evaluation of adhesiveness. The evaluation of the coating layer applied by the upstream gravure roll was “A”.

Comparative Example 1

(Production and evaluation of heat-resistant film)
A film J was obtained in the same manner as in Example 1, except that the ejection surface of the non-contact type support device was a metal mesh plate having a maximum opening diameter of 770 μm and an air permeability of 500 ml / cm ² / sec. . Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film J and the evaluation of the heat resistance.

Comparative Example 2

(Production and evaluation of heat-resistant film)
In Example 1, the film K was formed in the same manner as in Example 1 except that the ejection surface of the non-contact type support device was a non-woven fabric made of polyester having a maximum opening diameter of 3 μm and an air permeability of 10 ml / cm ² / sec. Obtained. During the conveyance of the film-like substrate, the film-like substrate may come into contact with the ejection surface of the non-contact support device. Table 1 shows the evaluation of the uniformity of the heat-resistant layer of the film K and the evaluation of the heat resistance.

  From the results in Table 1, the coating layers of the heat-resistant films of Examples 1 to 8 in which the maximum opening diameter of the ejection portion of the ejection surface of the non-contact support device and the air permeability are within the scope of the present invention are both uniform. It turns out that it is excellent in heat resistance. Further, the coating layer of the adhesive film of Example 9 in which the maximum opening diameter of the opening portion of the ejection surface of the non-contact type support device and the air permeability are within the scope of the present invention is excellent in uniformity on both sides and the adhesiveness. It turns out that it is excellent.

  On the other hand, the coating layer of the heat-resistant film of Comparative Examples 1 and 2 in which the maximum opening diameter of the ejection portion of the ejection surface of the non-contact support device and the air permeability are out of the scope of the present invention is inferior in uniformity and heat resistance is also inferior. I understand that.

DESCRIPTION OF SYMBOLS 1 ... Coating apparatus, 2 ... Drive roll of base material unwinding, 3, 4 ... Chamber doctor coating apparatus, 5 ... Non-contact type support apparatus, 6 ... Drying furnace, 7 ... Drive roll of base material winding, 8 A drive roll (suction roll) for feeding a substrate, 9 ... a drive roll (suction roll) for taking a substrate, 10 ... a gravure roll, 11 ... a coating chamber, 100 ... a separator substrate.

Claims (4)

A non-contact type support device that supports a long film-like substrate conveyed along a certain direction in a non-contact state,
A gas supply unit for supplying gas;
An ejection part having an ejection surface for ejecting the gas supplied from the gas supply part toward one side of the film-like substrate;
An opening having a maximum opening diameter of 5 μm or more and 150 μm or less is formed on the ejection surface,
The non-contact support device according to claim 1, wherein the air permeability of the ejection surface is 15 ml / cm ² / sec or more and 350 ml / cm ² / sec or less. A method for producing a film-like substrate using the non-contact support device according to claim 1,
A transporting process for transporting a long film-shaped substrate along a certain direction;
A coating layer forming step of forming a coating layer by applying a coating agent on one or both sides of the film-like substrate being conveyed;
Drying the coating layer on the film-like substrate,
The transporting step transports the film-like substrate on which the coating layer has been formed supported by the non-contact support device after the coating layer forming step and before the drying step. The manufacturing method of the film-form base material with a coating layer provided with the said coating layer and the said film-form base material characterized by including the process part to do.   The method for producing a film-like substrate with a coating layer according to claim 2, wherein the pressure inside the ejection part is controlled to 50 Pa or more and 1000 Pa or less.   The film-form substrate with a coating layer according to claim 2 or 3, wherein the coating agent has a temperature of 23 ° C and a viscosity in a shear rate region 1000 (1 / s) of 2 cP or more and 80 cP or less. A method of manufacturing the material.

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