WO2013080701A1 - Laminate porous film roll and manufacturing method thereof - Google Patents

Abstract

The purpose of the present invention is to provide a laminate porous film roll which is a laminate porous film comprising a covering layer partially laminated on at least one surface of a polyolephin resin porous film, wherein the laminate porous film roll comprises a boundary line formed linearly between the portion where the covering layer is laminated (the covering layer lamination portion) and the portion where the covering layer is not laminated (the no-covering layer portion), can be wound without wrinkles, has uniform quality, and has improved secondary workability for slits, etc.. This laminate porous film roll comprises a covering layer partially laminated on the at least one surface of the polyolephin resin porous film, and comprises at least one covering layer lamination portion X and at least one no-covering layer portion Y, wherein the film thickness Ta at the end portion of the at least one covering layer lamination portion X and the film thickness Tb in the center portion fulfill the relational expression Ta ≦ Tb, and the winding length of the film is 1000m or greater.

Description

Laminated porous film roll and method for producing the same

The present invention relates to a laminated porous film roll using a polyolefin resin porous film and a method for producing the same. The laminated porous film roll of the present invention can be used as a packaging, sanitary, livestock, agricultural, architectural, medical, separation membrane, light diffusion plate, battery separator, and in particular, a separator for a nonaqueous electrolyte battery. Can be suitably used.

The polymer porous body with many fine communication holes is used for separation membranes used for the production of ultrapure water, purification of chemicals, water treatment, waterproof and moisture-permeable films used for clothing and sanitary materials, and batteries. It is used in various fields such as battery separators.

In particular, secondary batteries are widely used as power sources for portable devices such as OA, FA, household electric appliances or communication devices. Among them, portable devices using lithium ion secondary batteries are increasing because they have a high volumetric efficiency when mounted on devices, leading to a reduction in size and weight of the devices. On the other hand, large-sized secondary batteries are being researched and developed in many fields related to energy / environmental issues, including road leveling, UPS, and electric vehicles, and are excellent in large capacity, high output, high voltage, and long-term storage. Therefore, the use of lithium ion secondary batteries, which are a kind of non-aqueous electrolyte secondary battery, is expanding.

The working voltage of a lithium ion secondary battery is usually designed with an upper limit of 4.1V to 4.2V. At such a high voltage, the aqueous solution causes electrolysis and cannot be used as an electrolyte. Therefore, so-called non-aqueous electrolytes using organic solvents are used as electrolytes that can withstand high voltages. As the solvent for the non-aqueous electrolyte, a high dielectric constant organic solvent capable of allowing more lithium ions to be present is used, and organic carbonate compounds such as propylene carbonate and ethylene carbonate are mainly used as the high dielectric constant organic solvent. in use. As a supporting electrolyte that becomes a lithium ion source in the solvent, a highly reactive electrolyte such as lithium hexafluorophosphate is dissolved in the solvent and used.

In the lithium ion secondary battery, a separator is interposed between the positive electrode and the negative electrode from the viewpoint of preventing an internal short circuit. Of course, the separator is required to have insulating properties due to its role. Moreover, it is necessary to have a microporous structure in order to provide air permeability as a lithium ion passage and a function of diffusing and holding the electrolyte. In order to satisfy these requirements, a porous film is used as a separator.

With the recent increase in battery capacity, the importance of battery safety is increasing. As a characteristic that contributes to the safety of the battery separator, there is a shutdown characteristic (hereinafter referred to as “SD characteristic”). This SD characteristic is a function that can prevent a subsequent increase in temperature inside the battery because the micropores are closed when the temperature is about 100 to 150 ° C., and as a result, ion conduction inside the battery is blocked. At this time, the lowest temperature among the temperatures at which the micropores of the laminated porous film are blocked is referred to as a shutdown temperature (hereinafter referred to as “SD temperature”). When used as a battery separator, it is necessary to have this SD characteristic.

However, in recent years, with the increase in energy density and power of lithium ion secondary batteries, the normal shutdown function does not function sufficiently, and the temperature inside the battery is the melting point of polyethylene conventionally used as a raw material for separators. There is a risk that the temperature will rise further above about 150 ° C. and the separator will break. Therefore, in order to ensure safety, a separator having both current SD characteristics and heat resistance is required.

In response to the request, a laminated porous film (Patent Document 1) is proposed in which a heat-resistant layer (a coating layer for improving heat resistance) containing an inorganic filler and a resin binder is laminated on at least one surface of a polyolefin resin porous film. Yes.

In addition, there are various sizes of separators depending on the size of the applied battery, and it has been studied to use a widely coated separator cut (slit) along the longitudinal direction, but to improve heat resistance. Since the coating layer is very hard, there is a problem that the cutting blade wears easily at the time of cutting, and there is a problem that a long and narrow scrap of resin of the base film adheres due to the cutting with the worn blade. There was a problem that a nearby coating layer peeled off. In order to solve these problems, so-called partial coating, in which a coating layer is not formed on a cut portion, has been studied (Patent Document 2).

WO2011 / 062285 JP2011-159434A

However, when the coating layer is formed on the porous film as in Patent Document 1, the corona treatment is usually applied to the surface on which the coating layer is provided in order to ensure the adhesion between the coating layer and the polyolefin porous film. Surface treatment by etc. is performed. However, polyolefin resin porous films for battery separators are very thin and porous, so that the film tends to wrinkle during and / or after surface treatment such as corona treatment, and the surface treatment is performed. There is a problem that the porous film cannot be applied neatly. In addition, since it is very thin and porous, it is easy to wrinkle the porous film in the process of providing a coating layer on the polyolefin porous film with a coating or the winding process, and before the coating liquid is coated, When wrinkles occur in the film, uniform coating cannot be performed, and the thickness of the coating layer becomes randomly non-uniform. As a result, main performances such as heat resistance and air permeability of the separator become non-uniform, and further, there arises a problem that wrinkles are likely to occur at a portion having a large thickness difference during winding. When wrinkles occur in the winding process, a large pressure is applied to the wrinkled portion of the wound product, and the performance as a separator becomes non-uniform in the same manner. Also, when a battery is combined with a positive electrode, a negative electrode, etc. This is not preferable because it adversely affects workability.

Moreover, when providing the part by which the coating layer is not laminated | stacked by partial application like patent document 2, the thickness of the boundary part of a coating part and an uncoated part can be controlled, and a beautiful boundary line can be formed. As a result, the problem of slitting has not been solved, and the problem of wrinkling at the time of winding occurs.

In particular, when a portion where the coating layer is not laminated (non-laminated portion) other than the end portion in the film width direction is provided, there is a problem that the film is wrinkled or the winding roll is deformed. Furthermore, the longer the film is wound, the more the winding roll is deformed and the non-uniformity becomes large. Therefore, it is possible to produce a film roll having a length of about 1000 m or more and a wide film roll without winding deviation and wrinkles. Have difficulty.

Therefore, in the present invention, in the laminated porous film in which the coating layer is partially laminated on at least one surface of the polyolefin resin porous film, the coating layer is not laminated on the portion where the coating layer is laminated (coating layer lamination portion). To provide a laminated porous film roll in which the boundary line of a part (non-laminated part) is formed in a straight line, wound up without wrinkles, has uniform quality, and has improved secondary workability such as slits. With the goal.

In the case of providing a non-laminated portion where a coating layer is not laminated by partial coating or the like, particularly when providing a non-laminated portion in a place other than the end in the film width direction, When we examined the cause of wrinkles and sagging, there was a shift in height at the end of the coating layer stack, and when a long film roll was manufactured in this state, compared to the surrounding area called the ear height at the end It has been found that a protruding portion having a protruding height is generated, thereby causing wrinkles and sagging in the non-laminated portion. And by controlling the height in the edge part of a coating layer lamination | stacking part, a film can be wound up, suppressing generation | occurrence | production of a wrinkle, and the film roll of about 1000 m or more long goods and wide goods can be manufactured. As a result, the present invention has been completed.

That is, the present invention
(1) A laminated porous film in which a coating layer is partially laminated on at least one surface of a polyolefin-based resin porous film, and at least one coating layer laminate portion X and at least one non-laminate portion Y are formed. A laminated porous film roll wound up, wherein the film thickness Ta at the end of at least one coating layer laminated portion X and the film thickness Tb at the central portion satisfy a relational expression of Ta ≦ Tb, and the laminated porous film is wound. The laminated porous film roll having a length of 1000 m or more,
(2) The laminated porous film roll according to (1), wherein the non-laminated portion Y is provided at an end in the film width direction,
(3) The laminated porous film roll according to (1) or (2), wherein the non-laminated portion Y is provided at a place other than the end in the film width direction,
(4) The film thickness Ta1 at one end and the film thickness Ta2 at the other end in at least one coating layer laminate portion X satisfy the relational expression | Ta1-Ta2 | ≦ 3 μm. The laminated porous film roll according to any one of (3),
(5) Any one of (1) to (4), wherein the maximum value Tmax and the minimum value Tmin of the film thickness at the ends of all the coating layer laminated portions X satisfy the relational expression (Tmax−Tmin) ≦ 3 μm 1. The laminated porous film roll according to 1,
(6) The laminated porous film roll according to any one of (1) to (5), wherein the width of at least one non-laminate portion Y is 5 mm to 100 mm,
(7) The laminated porous film roll according to any one of (1) to (6), wherein the thickness of the coating layer in the central portion of at least one coating layer laminate portion X is 0.5 μm to 50 μm,
(8) In any one of (1) to (7), the ratio of the thickness of the coating layer to the thickness of the polyolefin resin porous film in the central portion of at least one coating layer laminate portion X is 1/1 to 1/6. Or a laminated porous film roll according to claim 1,
(9) The laminated porous film roll according to any one of (1) to (8), wherein the polyolefin resin porous film has a thickness of 5 μm to 50 μm,
(10) The laminated porous film roll according to any one of (1) to (9), wherein a width of the laminated porous film is 0.3 m to 3 m,
(11) The laminated porous film roll according to any one of (1) to (10), wherein a coating layer is laminated on both surfaces of a polyolefin resin porous film,
(12) The laminated porous film roll according to any one of (1) to (11), wherein the coating layer comprises a filler and a resin binder,
(13) The coating layer is used as a laminated porous film roll according to any one of (1) to (12) and (14) a separator for a nonaqueous electrolyte battery, which are laminated by coating. It is an object of the present invention to provide a laminated porous film roll according to any one of (1) to (13).

The present invention also provides:
(15) A laminated porous film in which a coating layer is partially laminated on at least one surface of a polyolefin-based resin porous film, and at least one coating layer laminate portion X and at least one non-laminate portion Y are formed. A method for producing a wound laminated porous film roll, wherein the coating layer is formed by gravure coating and corresponds to at least one coating layer laminate portion X in the film width direction of the gravure roll used for gravure coating A method for producing a laminated porous film roll, wherein the cell depth Tc at the end of the engraving portion Z and the cell depth Td at the center satisfy the relational expression Tc ≦ Td;
(16) A laminated porous film in which a coating layer is partially laminated on at least one surface of a polyolefin-based resin porous film, and at least one coating layer laminate portion X and at least one non-laminate portion Y are formed. A method for producing a wound laminated porous film roll, wherein the coating layer is formed by gravure coating, and the shape of a gravure roll cell used for gravure coating is a symmetrical shape The production method,
(17) The method for producing a laminated porous film roll according to (15) or (16), wherein the shape of the cell is trapezoidal in the depth direction,
(18) Any one of (15) to (17), wherein the rotation direction of the gravure roll at the time of gravure coating is opposite to the conveyance direction of the substrate at the position where the paint is transferred to the substrate Or the method for producing a laminated porous film roll according to (1), and (19) when transferring the paint, the substrate is brought into contact with the gravure roll through the guide rolls arranged before and after the gravure roll without using the back roll. It is another object of the present invention to provide a method for producing a laminated porous film roll as described in (18), wherein the coating material is transferred.

In the present invention, in a laminated porous film in which a coating layer is partially laminated on at least one surface of a polyolefin resin porous film, the occurrence of wrinkles is suppressed by controlling the height at the end of the coating layer lamination part. Thus, a laminated porous film roll having a uniform quality and improved secondary workability such as slits can be provided. In particular, in the present invention, it is possible to produce a long or wide film roll of about 1000 m or more in a partially coated product, which has been difficult to manufacture.

Schematic diagram of gravure roll that can be used in one embodiment of the production method of the present invention An example of a gravure roll for partial coating in a grid pattern An example of gravure rolls for oblique coating (Small-diameter) Kiss reverse gravure coating method Reverse gravure coating method coating diagram The partially broken perspective view of the battery which accommodates the lamination | stacking porous film of this invention

Hereinafter, embodiments of the laminated porous film roll of the present invention will be described in detail.

In the present invention, the expression “main component” includes the intention to allow other components to be contained within a range that does not interfere with the function of the main component, unless otherwise specified. Although the content ratio is not specified, the main component is intended to include 50% by mass or more, preferably 70% by mass or more, particularly preferably 90% by mass or more (including 100%) in the composition. .
In addition, when “X to Y” (X and Y are arbitrary numbers) is described, it means “preferably greater than X” and “preferably smaller than Y” with the meaning of “X or more and Y or less” unless otherwise specified. Is included.

(Polyolefin resin porous film)
Examples of the polyolefin resin used in the polyolefin resin porous film include homopolymers or copolymers obtained by polymerizing ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexane and the like. Among these, a polypropylene resin and a polyethylene resin are preferable.

(Polypropylene resin)
Polypropylene resins include homopropylene (propylene homopolymer), or propylene and ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. Random copolymers or block copolymers with α-olefins may be mentioned. Among these, homopolypropylene is more preferably used from the viewpoint of maintaining the mechanical strength and heat resistance of the laminated porous film.

The polypropylene resin preferably has an isotactic pentad fraction (mmmm fraction) exhibiting stereoregularity of 80 to 99%. More preferably 83 to 98%, and still more preferably 85 to 97%. If the isotactic pentad fraction is too low, the mechanical strength of the film may be reduced. On the other hand, the upper limit of the isotactic pentad fraction is defined by the upper limit that can be obtained industrially at the present time, but this is not the case when a more regular resin is developed in the industrial level in the future. is not.
The isotactic pentad fraction (mmmm fraction) is the same direction for all five methyl groups that are side chains with respect to the main chain of carbon-carbon bonds composed of any five consecutive propylene units. Means the three-dimensional structure located at or its proportion. Signal assignment of the methyl group region is as follows. It conformed to Zambelli et al (Macromolecules 8,687, (1975)).

Further, as a polypropylene resin, it is preferable that Mw / Mn, which is a parameter indicating a molecular weight distribution, is 2.0 to 10.0. More preferred is 2.0 to 8.0, and still more preferred is 2.0 to 6.0. This means that the smaller the Mw / Mn, the narrower the molecular weight distribution. However, if the Mw / Mn is 2.0 or more, there is no problem such as deterioration of extrusion moldability, and industrial production is easy. It becomes. On the other hand, if Mw / Mn is 10.0 or less, the low molecular weight component is small and the mechanical strength of the laminated porous film is not lowered. Mw / Mn is obtained by GPC (gel permeation chromatography) method.

The melt flow rate (MFR) of the polypropylene resin is not particularly limited, but usually the MFR is preferably 0.5 to 15 g / 10 minutes, and 1.0 to 10 g / 10 minutes. It is more preferable. When the MFR is 0.5 g / 10 min or more, the resin has a high melt viscosity at the time of molding, and sufficient productivity can be ensured. On the other hand, the mechanical strength of the obtained laminated porous film can be sufficiently maintained by setting it to 15 g / 10 min or less. MFR is measured according to JIS K7210 under conditions of a temperature of 230 ° C. and a load of 2.16 kg.

The method for producing the polypropylene resin is not particularly limited, and a known polymerization method using a known polymerization catalyst, for example, a multisite catalyst represented by a Ziegler-Natta type catalyst or a metallocene catalyst. And a polymerization method using a single site catalyst.

Examples of polypropylene resins include the trade names “Novatech PP” “WINTEC” (manufactured by Nippon Polypro), “Versify” “Notio” “Toughmer XR” (manufactured by Mitsui Chemicals), “Zeras” “Thermolan” (Mitsubishi Chemical) , “Sumitomo Noblen”, “Tough Selenium” (manufactured by Sumitomo Chemical Co., Ltd.), “Prime Polypro”, “Prime TPO” (manufactured by Prime Polymer Co., Ltd.), “Adflex”, “Adsyl”, “HMS-PP (PF814)” ( Commercially available products such as “San Aroma” and “Inspire” (Dow Chemical) can be used.

The polyolefin resin porous film used in the present invention preferably has β activity.
In the polyolefin resin porous film of the present invention, the presence or absence of “β activity” is determined by holding the laminated porous film with a differential scanning calorimeter from 25 ° C. to 240 ° C. at a heating rate of 10 ° C./min for 1 minute. When the temperature was lowered from 240 ° C. to 25 ° C. at a cooling rate of 10 ° C./min and held for 1 minute, and when the temperature was raised again from 25 ° C. to 240 ° C. at a heating rate of 10 ° C./min, When the derived crystal melting peak temperature (Tmβ) is detected, it is determined to have β activity.

Further, the β activity of the porous film is calculated by the following formula using the crystal heat of fusion derived from α crystal (ΔHmα) and the crystal heat of fusion derived from β crystal (ΔHmβ) of the polypropylene resin to be detected.
β activity (%) = [ΔHmβ / (ΔHmβ + ΔHmα)] × 100
For example, when the polypropylene resin is homopolypropylene, the amount of heat of crystal melting derived from the β crystal (ΔHmβ) detected mainly in the range of 145 ° C. or higher and lower than 160 ° C., and mainly detected at 160 ° C. or higher and 170 ° C. or lower. It can be calculated from the heat of crystal melting (ΔHmα) derived from the α crystal. For example, in the case of random polypropylene copolymerized with 1 to 4 mol% of ethylene, the amount of heat of crystal melting (ΔHmβ) derived from the β crystal detected mainly in the range of 120 ° C. or more and less than 140 ° C. It can be calculated from the crystal melting calorie (ΔHmα) derived from the α crystal detected in the range of from 0 ° C. to 165 ° C.

The β activity of the polyolefin resin porous film is preferably 20% or more, and more preferably 40% or more and 60% or more. If the laminated porous film has a β activity of 20% or more, a lot of fine and uniform pores are formed by stretching, and as a result, a separator for a lithium ion battery having high mechanical strength and excellent air permeability is obtained. Can do.
The upper limit of β activity is not particularly limited, but the higher the β activity, the more effective the effect is obtained.

The presence or absence of the β activity can also be determined by a diffraction profile obtained by wide-angle X-ray diffraction measurement of a laminated porous film subjected to a specific heat treatment.
More specifically, a wide-angle X-ray diffraction measurement was performed on a laminated porous film which was subjected to heat treatment at 170 ° C. to 190 ° C., which is a temperature exceeding the melting point of the polypropylene resin, and was slowly cooled to form and grow β crystals. When a diffraction peak derived from the (300) plane of the β crystal of the resin is detected in the range of 2θ = 16.0 ° to 16.5 °, it is determined that there is β activity.
Details on the β crystal structure and wide angle X-ray diffraction of polypropylene resins can be found in Macromol. Chem. 187, 643-652 (1986), Prog. Polym. Sci. Vol. 16, 361-404 (1991), Macromol. Symp. 89, 499-511 (1995), Macromol. Chem. 75, 134 (1964), and references cited therein.

The β activity can be measured regardless of whether the polypropylene resin porous film has a single layer structure or is laminated with another porous layer.
Further, if a layer containing a polypropylene resin other than the layer made of polypropylene resin is laminated, it is preferable that both layers have β activity.

As a method for obtaining the β activity described above, a method of adding polypropylene subjected to a treatment for generating a peroxide radical as described in Japanese Patent No. 3739481, and a method of adding a β crystal nucleating agent to the composition Etc.

(Β crystal nucleating agent)
Examples of the β-crystal nucleating agent used in the present invention include the following, but are not particularly limited as long as they increase the formation / growth of β-crystals of a polypropylene resin, and two or more types thereof. May be used in combination.
Examples of the β crystal nucleating agent include amide compounds; tetraoxaspiro compounds; quinacridones; iron oxides having a nanoscale size; potassium 1,2-hydroxystearate, magnesium benzoate or magnesium succinate, magnesium phthalate, etc. Alkali or alkaline earth metal salts of carboxylic acids represented by: aromatic sulfonic acid compounds represented by sodium benzenesulfonate or sodium naphthalenesulfonate; di- or triesters of dibasic or tribasic carboxylic acids; phthalocyanine blue Phthalocyanine pigments typified by: a two-component compound comprising component A which is an organic dibasic acid and a component B which is an oxide, hydroxide or salt of a Group IIA metal of the periodic table; a cyclic phosphorus compound; Made of magnesium compound Such as the formation thereof. In addition, specific types of nucleating agents are described in JP-A No. 2003-306585, JP-A No. 06-289656, and JP-A No. 09-194650.

Commercially available products of β crystal nucleating agent are β crystal nucleating agent “NJESTER NU-100” manufactured by Shin Nippon Rika Co., Ltd. Specific examples of polypropylene resins to which β crystal nucleating agent is added include polypropylene “Bepol® B” manufactured by Aristech. -022SP ”, polypropylene manufactured by Borealis“ Beta (β) -PP BE60-7032 ”, polypropylene manufactured by Mayzo“ BNX BETAPP-LN ”, and the like.

The ratio of the β-crystal nucleating agent added to the polypropylene resin needs to be appropriately adjusted depending on the type of the β-crystal nucleating agent or the composition of the polypropylene-based resin. 0.0001 to 5.0 parts by mass of the agent is preferred. 0.001 to 3.0 parts by mass is more preferable, and 0.01 to 1.0 part by mass is still more preferable. If it is 0.0001 part by mass or more, β crystals of polypropylene resin can be sufficiently produced and grown at the time of production, and sufficient β activity can be secured even when used as a separator, and the desired air permeability performance can be obtained. can get. Addition of 5.0 parts by mass or less is preferable because it is economically advantageous and there is no bleeding of the β crystal nucleating agent on the surface of the laminated porous film.
Further, when a layer containing a polypropylene resin other than the layer made of polypropylene resin is laminated, the amount of β crystal nucleating agent added to each layer may be the same or different. The porous structure of each layer can be appropriately adjusted by changing the addition amount of the β crystal nucleating agent.

(Other ingredients)
In addition to the components described above, additives generally blended in the resin composition can be appropriately added to the polypropylene resin within a range that does not significantly impair the effects of the present invention. Examples of the additive include recycling resin, silica, talc, kaolin, calcium carbonate, and the like, which are added for the purpose of improving and adjusting molding processability, productivity, and various physical properties of the laminated porous film. Inorganic particles such as, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, Examples thereof include additives such as antioxidants, light stabilizers, ultraviolet absorbers, neutralizers, antifogging agents, antiblocking agents, slip agents, and coloring agents.

(Polyethylene resin)
In the present embodiment, a polyethylene resin porous film is suitably used as the porous film laminated with the porous film made of the polypropylene resin.
Specific examples of the polyethylene resin include ultra low density polyethylene, low density polyethylene, high density polyethylene, linear low density polyethylene, and homopolymer polyethylene such as ultra high molecular weight polyethylene having a characteristic molecular weight, as well as ethylene. A propylene copolymer or a copolymer polyethylene of a polyethylene resin and another polyolefin resin can be used. Among them, homopolymer polyethylene or copolymer polyethylene having an α-olefin comonomer content of 2 mol% or less is preferable, and homopolymer polyethylene is more preferable. There are no particular restrictions on the type of α-olefin comonomer.

The density of the polyethylene resin is preferably 0.910 to 0.970 g / cm ³ , more preferably 0.930 to 0.970 g / cm ³ , and 0.940 to 0.970 g / cm 3. ³ is more preferable. A density of 0.910 g / cm ³ or more is preferable because it can have appropriate SD characteristics. On the other hand, 0.970 g / cm ³ or less is preferable in that it can have an appropriate SD characteristic and can maintain stretchability. The density can be measured according to JIS K7112 using a density gradient tube method.

Further, the melt flow rate (MFR) of the polyethylene resin is not particularly limited, but usually the MFR is preferably 0.03 to 30 g / 10 minutes, and preferably 0.3 to 10 g / 10 minutes. It is more preferable. If the MFR is 0.03 g / 10 min or more, the melt viscosity of the resin during the molding process is sufficiently low, which is excellent in productivity and preferable. On the other hand, if it is 30 g / 10 minutes or less, since sufficient mechanical strength can be obtained, it is preferable.
MFR is measured in accordance with JIS K7210 under conditions of a temperature of 190 ° C. and a load of 2.16 kg.

The polymerization catalyst for the polyethylene resin is not particularly limited, and may be any one such as a Ziegler type catalyst, a Philips type catalyst, or a Kaminsky type catalyst. As a polymerization method of the polyethylene resin, there are a one-stage polymerization, a two-stage polymerization, or a multistage polymerization more than that, and any method of the polyethylene resin can be used.

(Porosification promoting compound)
It is preferable to add a porosity promoting compound that promotes porosity to the polyethylene resin. By adding the porosity promoting compound, a porous structure can be obtained more efficiently, and the shape and diameter of the pores can be easily controlled.
The porosity promoting compound is not limited, but specific examples include a porosity promoting compound selected from a modified polyolefin resin, an alicyclic saturated hydrocarbon resin or a modified product thereof, an ethylene copolymer, or a wax. More preferably, at least one kind is included. Among these, an alicyclic saturated hydrocarbon resin or a modified product thereof, an ethylene copolymer, or a wax, which is more effective when made porous, is more preferable, and a wax is more preferable from the viewpoint of moldability.

Examples of the alicyclic saturated hydrocarbon resin and modified products thereof include petroleum resins, rosin resins, terpene resins, coumarone resins, indene resins, coumarone-indene resins, and modified products thereof.

In the present invention, the petroleum resin is a C4 to C10 aliphatic olefin or diolefin obtained from a by-product such as naphtha pyrolysis, or an aromatic compound having C8 or more having an olefinically unsaturated bond. An aliphatic, aromatic and copolymer petroleum resin obtained by singly or copolymerizing one or more of the compounds contained therein.

Examples of petroleum resins include aliphatic petroleum resins mainly containing C5 fraction, aromatic petroleum resins mainly containing C9 fraction, copolymer petroleum resins thereof, and alicyclic petroleum resins. . Examples of the terpene resin include terpene resins and terpene-phenol resins from β-pinene, and examples of the rosin resin include rosin resins such as gum rosin and utudrodin, and esterified rosin resins modified with glycerin and pentaerythritol. The alicyclic saturated hydrocarbon resin and the modified product thereof have relatively good compatibility when mixed with a polyethylene resin, but a petroleum resin is more preferable in terms of color tone and thermal stability, and a hydrogenated petroleum resin is used. More preferably.

Hydrogenated petroleum resin is obtained by hydrogenating petroleum resin by a conventional method. Examples thereof include hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, hydrogenated copolymer petroleum resins and hydrogenated alicyclic petroleum resins, and hydrogenated terpene resins. Among hydrogenated petroleum resins, hydrogenated alicyclic petroleum resins obtained by copolymerizing and hydrogenating a cyclopentadiene compound and an aromatic vinyl compound are particularly preferable. Examples of commercially available hydrogenated petroleum resins include “ALCON” (manufactured by Arakawa Chemical Industries).

The ethylene copolymer in the present invention is a compound obtained by copolymerizing ethylene and one or more of vinyl acetate, unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, or carboxylic acid ester. It is.

The ethylene copolymer preferably has an ethylene monomer unit content of 50% by mass or more, more preferably 60% by mass or more, and still more preferably 65% by mass or more. On the other hand, regarding the upper limit, the content of ethylene monomer units is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less. If the content of the ethylene monomer unit is within a predetermined range, a porous structure can be formed more efficiently.

As the ethylene copolymer, those having an MFR (JIS K7210, temperature: 190 ° C., load: 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min are preferably used. If the MFR is 0.1 g / 10 min or more, the extrudability can be maintained satisfactorily. On the other hand, if the MFR is 10 g / 10 min or less, the strength of the film is hardly lowered, which is preferable.

The ethylene-based copolymer includes “EVAFLEX” (Mitsui DuPont, manufactured by Polychemical Co., Ltd.), “Novatech EVA” (manufactured by Nippon Polyethylene Co., Ltd.) as an ethylene-vinyl acetate copolymer, and “NUC as an ethylene-acrylic acid copolymer. "Copolymer" (Nippon Unicar), "Evaflex-EAA" (Mitsui DuPont, Polychemical), "REXPEARL EAA" (Nihon Ethylene), "ELVALOY" as an ethylene- (meth) acrylic acid copolymer (Mitsui / DuPont Polychemical Co., Ltd.), “REXPEARL EMA” (Nippon Ethylene Co., Ltd.), “REXPEARL EEA” (manufactured by Nippon Ethylene Co., Ltd.), ethylene-methyl (meth) acrylic acid co "Acrylift" as a polymer (Sumitomo Chemical) ), “Bondyne” (manufactured by Sumitomo Chemical Co., Ltd.), an ethylene-glycidyl methacrylate copolymer, an ethylene-vinyl acetate-glycidyl methacrylate terpolymer, “Bond First” (manufactured by Sumitomo Chemical Co., Ltd.) is commercially available as an ethylene-ethyl acrylate-glycidyl methacrylate terpolymer.

The wax in the present invention is an organic compound that satisfies the following properties (a) and (b).
(A) The melting point is 40 ° C to 200 ° C.
(A) The melt viscosity at a temperature 10 ° C. higher than the melting point is 50 Pa · s or less.

¡For wax, including polar or nonpolar wax, polypropylene wax, polyethylene wax and wax modifier. Specifically, polar wax, nonpolar wax, Fischer-Tropsch wax, oxidized Fischer-Tropsch wax, hydroxy stearamide wax, functionalized wax, polypropylene wax, polyethylene wax, wax modifier, amorphous wax, carnauba wax , Castor oil wax, microcrystalline wax, beeswax, carnauba wax, castor wax, plant wax, candelilla wax, Japanese wax, ouricury wax, rice bran wax bark, rice bran wax, jojoba wax, bay wax, montan wax, ozo Kelite wax, ceresin wax, petroleum wax, paraffin wax, chemically modified hydrocarbon wax, substituted amide wax, and combinations thereof Allowed and derivatives. Among these, paraffin wax, polyethylene wax, and microcrystalline wax are preferable from the viewpoint of efficiently forming a porous structure, and microcrystalline wax that can further reduce the pore diameter is more preferable from the viewpoint of SD characteristics. Examples of commercially available polyethylene wax include “FT-115” (manufactured by Nippon Seiwa), and examples of microcrystalline wax include “Hi-Mic” (manufactured by Nippon Seiwa).

The blending amount of the porosity promoting compound is 1 mass as a lower limit with respect to 100 parts by mass of the polyethylene resin contained in one layer when the interface between the polyethylene resin and the porosity promoting compound is peeled to form micropores. Part or more, preferably 5 parts by weight or more, more preferably 10 parts by weight or more. On the other hand, the upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. By setting the blending amount of the porosity promoting compound to 1 part by mass or more with respect to 100 parts by mass of the polyethylene resin, an effect of expressing a desired good porous structure can be sufficiently obtained. Moreover, the more stable moldability is securable because the compounding quantity of the said porosity promotion compound shall be 50 mass parts or less.

If necessary, a thermoplastic resin may be used in addition to the polyethylene-based resin and the porosity promoting compound as long as the thermal characteristics of the porous film, specifically, the porosity is not impaired. Other thermoplastic resins that can be mixed with the above-mentioned polyethylene resin include styrene resins such as polystyrene, AS resin, or ABS resin: polyvinyl chloride, fluorine resin, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or Ester resins such as polyarylate; ether resins such as polyacetal, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone or polyphenylene sulfide; polyamide resins such as 6 nylon, 6-6 nylon, 6-12 nylon And other thermoplastic resins.

Also, if necessary, what is called a rubber component such as a thermoplastic elastomer may be added. Examples of the thermoplastic elastomer include styrene / butadiene, polyolefin, urethane, polyester, polyamide, 1,2-polybutadiene, polyvinyl chloride, and ionomer.

In addition to the polyethylene-based resin and the porosity promoting compound, an additive or other component that is generally blended in the resin composition may be included. Examples of the additive include recycling resin, silica, talc, kaolin, carbonic acid, etc., which are added for the purpose of improving / adjusting the processability, productivity, and various physical properties of the laminated porous film. Inorganic particles such as calcium, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents And additives such as antioxidants, light stabilizers, ultraviolet absorbers, neutralizers, antifogging agents, antiblocking agents, slip agents, and coloring agents.
Among them, the nucleating agent is preferable because it has an effect of controlling the crystal structure of the polyethylene resin and reducing the porous structure at the time of stretching and opening. Examples of commercially available products include “Gelall D” (manufactured by Shin Nippon Chemical Co., Ltd.), “Adeka Stub” (manufactured by Asahi Denka Kogyo Co., Ltd.), “Hyperform” (manufactured by Milliken Chemical Co., Ltd.), or “IRGACLEAR D” (Ciba Special Chemicals). Etc.). Moreover, as a specific example of the polyethylene resin to which the nucleating agent is added, “Rike Master” (manufactured by Riken Vitamin Co., Ltd.) and the like are commercially available.

(Layer structure of polyolefin resin porous film)
In the present invention, the polyolefin-based resin porous film may be a single layer or a laminate, but is preferably laminated in two or more layers. Especially, what laminated | stacked the layer containing a polypropylene resin and the layer containing a polyethylene resin is more preferable.
The layer structure of the polyolefin resin porous film is not particularly limited as long as at least one layer containing a polypropylene resin (hereinafter referred to as “A layer”) is present. In addition, other layers (hereinafter referred to as “B layer”) can be laminated as long as they do not interfere with the function of the polyolefin resin porous film. The structure which laminated | stacked the intensity | strength maintenance layer, the heat-resistant layer (high melting temperature resin layer), the shutdown layer (low melting temperature resin layer), etc. are mentioned. For example, when used as a separator for a lithium ion battery, a low melting point resin layer that ensures the safety of the battery is laminated by closing the hole in a high temperature atmosphere as described in JP-A No. 04-181651. Is preferred.
Specific examples include a two-layer structure in which A layers / B layers are stacked, a three-layer structure in which A layers / B layers / A layers, or B layers / A layers / B layers are stacked. In addition, it is possible to adopt a form of three types and three layers in combination with layers having other functions. In this case, the order of stacking with layers having other functions is not particularly limited. Further, the number of layers may be increased as necessary to 4 layers, 5 layers, 6 layers, and 7 layers.

The physical properties of the polyolefin resin porous film of the present invention can be freely adjusted by the layer constitution, lamination ratio, composition of each layer, and production method.

(Manufacturing method of polyolefin resin porous film)
Next, although the manufacturing method of the polyolefin resin porous film of this invention is demonstrated, this invention is not limited only to the lamination | stacking porous film manufactured by this manufacturing method.

The method for producing the non-porous film is not particularly limited, and a known method may be used. For example, a method of melting a thermoplastic resin composition using an extruder, extruding from a T die, and cooling and solidifying with a cast roll. Is mentioned. Moreover, the method of cutting open the film-like thing manufactured by the tubular method and making it planar is also applicable.
There are no particular limitations on the method for making the nonporous membrane-like material, and known methods such as wet uniaxial or more stretched porous and dry uniaxial or more stretched porous may be used. As the stretching method, there are methods such as a roll stretching method, a rolling method, a tenter stretching method, and a simultaneous biaxial stretching method, and these methods are used alone or in combination of two or more to perform uniaxial stretching or biaxial stretching. Among these, sequential biaxial stretching is preferable from the viewpoint of controlling the porous structure.

Moreover, in this invention, when making a polyolefin resin porous film into a lamination, a manufacturing method is divided roughly into the following four according to the order of porous formation and lamination.
(A) A method of laminating each porous layer after laminating each porous layer or bonding with an adhesive or the like.
(B) A method of laminating each layer to produce a laminated nonporous film-like material and then making the nonporous film-like material porous.
(C) A method in which one of the layers is made porous and then laminated with another layer of a nonporous film to make it porous.
(D) A method of forming a laminated porous film by preparing a porous layer and then applying a coating such as inorganic / organic particles or depositing metal particles.
In the present invention, it is preferable to use the method (b) from the viewpoint of the simplicity of the process and productivity, and in particular, in order to ensure the interlayer adhesion between the two layers, a laminated nonporous film-like material is obtained by coextrusion. A method of forming a porous layer after preparing is particularly preferable.

Below, the detail of the manufacturing method of a polyolefin resin porous film is demonstrated.
First, a mixed resin composition of a polypropylene resin and, if necessary, a thermoplastic resin and additives is prepared. For example, raw materials such as polypropylene resin, β crystal nucleating agent, and other additives as required, preferably using Henschel mixer, super mixer, tumbler type mixer, etc., or by hand-blending all ingredients in a bag After mixing, the mixture is melt-kneaded with a single-screw or twin-screw extruder, a kneader or the like, preferably a twin-screw extruder, and then cut to obtain pellets.

The pellets are put into an extruder and extruded from a T-die extrusion die to form a film. The type of T die is not particularly limited. For example, when the laminated porous film of the embodiment of the present invention has a laminated structure of two types and three layers, the T die may be a multi-manifold type for two types and three layers or a feed block type for two types and three layers. .
The gap of the T die to be used is determined from the final required film thickness, stretching conditions, draft ratio, various conditions, etc., but is generally about 0.1 to 3.0 mm, preferably 0.5. -1.0 mm. If it is 0.1 mm or more, it is preferable from a viewpoint of production speed, and if it is 3.0 mm or less, since a draft rate becomes small, it is preferable from a viewpoint of production stability.

In extrusion molding, the extrusion temperature is appropriately adjusted depending on the flow characteristics and moldability of the resin composition, but is generally preferably 180 to 350 ° C, more preferably 200 to 330 ° C, and further preferably 220 to 300 ° C. A temperature of 180 ° C. or higher is preferable because the viscosity of the molten resin is sufficiently low and the moldability is excellent and the productivity is improved. On the other hand, by setting the temperature to 350 ° C. or lower, it is possible to suppress the deterioration of the resin composition, and hence the mechanical strength of the laminated porous film obtained.

When the β crystal nucleating agent is added, the cooling and solidification temperature by the cast roll is very important, and the ratio of β crystal of the polypropylene resin in the film can be adjusted. The cooling and solidifying temperature of the cast roll is preferably 80 to 150 ° C, more preferably 90 to 140 ° C, and still more preferably 100 to 130 ° C. It is preferable to set the cooling and solidification temperature to 80 ° C. or higher because the ratio of β crystals in the film can be sufficiently increased. Further, it is preferable to set the temperature to 150 ° C. or lower because troubles such as the extruded molten resin sticking to and wrapping around the cast roll hardly occur and the film can be efficiently formed into a film. By setting the cast roll in the above temperature range, the β crystal ratio of the polypropylene resin of the film-like material before stretching can be adjusted to 20 to 100%.

In the stretching step, uniaxial stretching may be performed in the longitudinal direction or the transverse direction, or biaxial stretching may be performed. Moreover, when performing biaxial stretching, simultaneous biaxial stretching may be sufficient and sequential biaxial stretching may be sufficient. When producing the polyolefin resin porous film of the present invention, sequential biaxial stretching is more preferable because the stretching conditions can be selected in each stretching step and the porous structure can be easily controlled.
The longitudinal direction of the film and the film is referred to as “longitudinal direction”, and the direction perpendicular to the longitudinal direction is referred to as “lateral direction”. In addition, stretching in the longitudinal direction is referred to as “longitudinal stretching”, and stretching in the direction perpendicular to the longitudinal direction is referred to as “lateral stretching”.

When sequential biaxial stretching is used, the stretching temperature needs to be changed appropriately depending on the composition of the resin composition to be used, the crystal melting peak temperature, the crystallinity, etc., but the stretching temperature in the longitudinal stretching is preferably about 0 to 130 ° C., More preferably, it is controlled in the range of 10 to 120 ° C., more preferably 20 to 110 ° C. The longitudinal draw ratio is preferably 2 to 10 times, more preferably 3 to 8 times, still more preferably 4 to 7 times. By performing longitudinal stretching within the above range, it is possible to develop an appropriate pore starting point while suppressing breakage during stretching.

On the other hand, the stretching temperature in transverse stretching is generally from 100 to 160 ° C., preferably from 110 to 150 ° C., more preferably from 120 to 140 ° C. The preferred transverse draw ratio is 2 to 10 times, more preferably 3 to 8 times, and still more preferably 4 to 7 times. By transversely stretching within the above range, the pore starting point formed by longitudinal stretching can be appropriately expanded, and a fine porous structure can be expressed.
The stretching speed in the stretching step is preferably 500 to 12000% / min, more preferably 1500 to 10,000% / min, and further preferably 2500 to 8000% / min.

The porous film thus obtained is preferably subjected to heat treatment for the purpose of improving dimensional stability. In this case, the effect of dimensional stability can be expected by setting the temperature to preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and still more preferably 140 ° C. or higher. On the other hand, the heat treatment temperature is preferably 170 ° C. or lower, more preferably 165 ° C. or lower, and further preferably 160 ° C. or lower. When the heat treatment temperature is 170 ° C. or lower, it is preferable because the heat treatment hardly melts polypropylene and maintains a porous structure. Further, during the heat treatment step, a relaxation treatment of 1 to 20% may be performed as necessary. In addition, the porous film of this invention is obtained by uniformly cooling and winding up after heat processing.

(surface treatment)
The surface treatment in the present invention means a physical and / or chemical surface modification treatment that can improve the surface adhesion of the polyolefin resin porous film. Examples thereof include, but are not limited to, corona treatment, plasma treatment, plasma treatment under atmospheric pressure, flame plasma treatment (flame treatment), and UV treatment. In the present invention, the surface treatment can be performed using known conditions and equipment that can be used in polyolefin resin porous films.

In the present invention, the polyolefin resin porous film may be surface-treated over the entire width, or may be surface-treated in stripes (partially). In the production of the laminated porous film, the non-treated portion cannot be applied by coating or the like, or even if it can be applied, it can be peeled off because it is not in close contact with the porous film of the substrate. Therefore, also in the laminated porous film of the present invention in which the coating layer is partially laminated, the porous film may be subjected to a surface treatment over the entire width.

(Laminated porous film roll)
The present invention provides a laminated porous film in which a coating layer is partially laminated on at least one surface of a polyolefin-based resin porous film, and at least one coating layer lamination portion X and at least one non-laminate portion Y are formed. The present invention relates to a laminated porous film roll wound up in a roll shape with a predetermined length in the length direction of the film.

In the present invention, it is preferable that the film thickness Ta at the end of the coating layer laminate portion X and the film thickness Tb at the center satisfy the relational expression of Ta ≦ Tb. Furthermore, it is preferable to satisfy the relational expression of Ta <Tb. In the present invention, the end portion of the covering layer stacking portion refers to a maximum value within 5 mm from the boundary between the covering layer stacking portion and the non-stacking portion.
In the present invention, it is possible to provide a film roll having a length of about 1000 m or more in which generation of wrinkles is suppressed by controlling the thickness of the film at the end portion and the central portion in the coating layer lamination portion. . When the laminated porous film roll of the present invention is used as a separator for a non-aqueous electrolyte battery, it is desirable to make the winding length as long as possible because the battery is finally manufactured in a roll shape and stacked with a positive electrode or a negative electrode. . If the film can be wound to a length of 1000 m or more, it can be used as a battery separator for manufacturing a battery, is efficient from the viewpoint of productivity, and has a quality assortment. Can do. In this respect, the winding length is preferably 1000 m or more, more preferably 1200 m or more, further preferably 1500 m or more, and particularly preferably 2000 m or more. In addition, since the longer winding length is preferable, there is no particular upper limit, but the winding length can be substantially 100,000 m or less.

In the present invention, at least one non-laminate portion Y is provided in the film width direction. The non-lamination part Y can be provided in the edge part of a film width direction, or places other than an edge part. In one embodiment of the present invention, the non-laminate portion Y can be provided at one end in the film width direction, or at a place other than the end, for example, near the center. In another embodiment of the present invention, two or more non-laminate portions Y are provided in the film width direction. For example, the non-laminate portions can be provided at both end portions or at both end portions and the vicinity of the center.

In the present invention, the width of at least one non-laminated portion Y is preferably in the range of 5 mm to 100 mm, more preferably 8 mm to 90 mm, and still more preferably 10 mm to 80 mm. If it is 5 mm or more, there is no problem in post-processing such as slits, and if it is 100 mm or less, wrinkles are less likely to occur, which is preferable.

In the present invention, the film thickness Ta1 at one end and the film thickness Ta2 at the other end of at least one coating layer laminate portion X satisfy the relational expression | Ta1-Ta2 | ≦ 3 μm. More preferred. Further, it is more preferable that the relational expression | Ta1-Ta2 | ≦ 2 μm is satisfied. By controlling the film thickness at both ends of the coating layer stacking portion X, the thickness is uniform over the entire coating layer stacking portion X, so that there is no deviation in the height of the coating layer end portion. The generation of wrinkles can be effectively suppressed.
Furthermore, in the present invention, it is more preferable that the maximum value Tmax and the minimum value Tmin of the film thickness at the ends of all the coating layer laminated portions X satisfy the relational expression of (Tmax−Tmin) ≦ 3 μm. Further, it is more preferable to satisfy the relational expression of (Tmax−Tmin) ≦ 2 μm. By setting it within this range, it is possible to more effectively suppress the generation of wrinkles.

In the present invention, the thickness of the coating layer in the central portion of at least one coating layer laminate portion X is preferably 0.5 μm to 50 μm, more preferably 1 μm to 40 μm, and further preferably 2 μm to 30 μm. If it is in the range of 0.5 μm to 50 μm, heat resistance when used as a separator for a non-aqueous electrolyte battery can be taken.
In the present invention, the polyolefin resin porous film has a thickness of preferably 5 μm to 50 μm, more preferably 8 μm to 40 μm, still more preferably 10 μm to 30 μm. When used as a separator for a non-aqueous electrolyte battery, a thin polyolefin-based resin porous film has been desired. According to the present invention, a coating layer is partially formed even if it is a thin film of 30 μm or less. The film laminated on can be rolled up for a long time while suppressing the generation of wrinkles.
In the present invention, the ratio of the thickness of the coating layer to the thickness of the polyolefin resin porous film in the central portion of at least one coating layer laminate portion X is preferably 1/1 to 1/6, more preferably 1/2. ˜1 / 5, more preferably ½ to ¼. If it is smaller than 1/1, there is no problem in conveyance of a laminated film, and generation | occurrence | production of a wrinkle can be suppressed. Moreover, if it is larger than 1/6, effects such as improvement in heat resistance by laminating the coating layer can be obtained.

In the present invention, the coating layer may be laminated on one side of the polyolefin resin porous film, or may be laminated on both sides.

In the present invention, the width of the film roll is preferably 0.3 to 3 m, more preferably 0.4 to 2.5 m, and still more preferably 0.8 to 2.5 m. According to the present invention, even if the width of the film roll is widened to increase the number of non-laminate portions, the film roll can be wound with reduced wrinkles. It can be produced efficiently by slitting in the direction.

(Method for producing laminated porous film roll)
The laminated porous film roll in the present invention can be produced by any method as long as it is a method of partially laminating a coating layer on at least one surface of a polyolefin resin porous film. It is preferable to laminate a coating layer by coating (application) on the surface of the film that has been surface-treated.

Coating methods include gravure coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, dip coater method, knife coater method, air doctor coater method, blade coater method, rod coater method, squeeze method A coater method, a cast coater method, a die coater method, a screen printing method, a spray coating method, and the like can be used, but in the present invention, the unevenness of the geometric pattern for transferring the coating liquid onto the roll ( It is particularly preferable to use a coating method using a gravure roll provided with a cell) (hereinafter also referred to as “gravure coating”).

The gravure coating method that can be used in the production method of the present invention is divided into a gravure coating method and a small-diameter gravure coating method from the size of the roll diameter, and in each method, the paint transfer position to the substrate In the above, the gravure roll is divided into a normal application method in which the gravure roll is rotated in the same direction as the base material traveling direction and a reverse method in which the gravure roll is rotated in the reverse direction. Furthermore, at a position where the coating material is transferred to the base material, a back roll system (see FIG. 5) that supports the base material with a back roll from the opposite side of the base material, and a guide roll disposed before and after the gravure roll, There is a kiss system (see FIG. 4) in which a material is brought into contact with a gravure roll to transfer a paint, which can be combined as appropriate.

Examples of the cell shape of the gravure roll that can be used in the production method of the present invention include a pyramid shape, a trapezoid shape, a lattice shape, and a diagonal shape (triangle, trapezoid). Among these, in the present invention, symmetrical cell shapes such as a pyramid shape, a lattice shape, and a trapezoid shape are preferably used.

In ordinary gravure coating, a slanted gravure roll that is asymmetrical to the left and right is often used for the reason that the transfer rate of the coating liquid can be increased. However, in the production of the laminated porous film roll of the present invention, if a left-right asymmetric oblique gravure roll is used, a lateral flow occurs in the coating liquid due to rotation, the thickness is not stabilized in the width direction, and the coating is not performed. Wrinkles may occur during construction and winding. In addition, when carrying out partial coating to provide an uncoated part to the polyolefin resin porous film that is the base material, the coating liquid protrudes into the uncoated part and the uncoated part with an accurate width Further, it is difficult to provide, and in the winding after coating, wrinkles may occur in the uncoated portion and the coated portion. At this time, wrinkles may occur because of differences in the thickness of both end portions of the laminated portion, resulting in a height shift, and in particular, the thickness of one end portion is thick and the ear height is in the state. There are many cases. In the present invention, for example, by using a gravure roll having a symmetrical cell shape such as a pyramid shape, a lattice shape, or a trapezoidal shape, it is possible to advantageously prevent a difference in thickness between both end portions of the laminated portion. In the case of performing partial coating (stripe shape or the like) for providing an uncoated portion, generation of wrinkles can be effectively suppressed.

Further, in the present invention, it is preferable to use a trapezoidal cell in the depth direction among the symmetrical cell shapes such as a pyramid shape, a lattice shape, and a trapezoidal shape (a non-limiting example is illustrated). 2). When a gravure cell having a symmetrical shape is used, the transfer rate is generally lower than that of a hatched gravure cell (see FIG. 3). However, the transfer rate can be increased by using a deep trapezoidal cell. Therefore, it is preferable.

In the present invention, the formation of the uncoated portion is a method of making the portion corresponding to the uncoated portion of the gravure roll unengraved, a method of cutting back the gravure roll to a predetermined width, or an uncoated portion. Examples include a masking method.

In the present invention, the step of applying the coating liquid to the surface of the polyolefin resin porous film is not particularly limited, and may be after extrusion molding or after the longitudinal stretching step. It may be after the transverse stretching step.

In the production method of the present invention, as described above, it is useful to use a gravure roll having a symmetrical cell shape as described above, but in order to further ensure the effect, at least one coating in the film width direction of the gravure roll is used. The cell depth Tc at the end of the engraving portion Z corresponding to the layer stack portion X and the cell depth Td at the center may satisfy the relational expression of Tc ≦ Td, and further satisfy the relational expression of Tc <Td. It is considered effective. A non-limiting example of such a gravure roll is shown in FIG. The example of the roll shown in FIG. 1B is a roll-shaped cell having a roll diameter of 60 mm, a roll width of 400 mm, and a cell depth Tc at the end of the engraving portion: 240 μm, a cell volume of 100 cm ³ / m ² , The cell depth Td at the center is 260 μm, and the cell volume is 110 cm ³ / m ² . By using such a gravure roll, it is estimated that the thickness of the film in the edge part and center part in a coating layer laminated part can be controlled effectively.

In the present invention, a preferable range of the cell depth Tc at the end of the engraving portion Z corresponding to at least one coating layer laminate portion X in the film width direction of the gravure roll to be used is a coating solution (dispersion) concentration described later. Depending on the type of the plate (lattice type, oblique line type, etc.), in the case of the oblique line type, it is 30 to 180 μm, more preferably 50 to 150 μm, and the preferred range of the cell depth Td in the center is 50 to 200 μm More preferably, it is 70 to 220 μm. Further, the preferable range of the cell volume Tcv at the end is 15 to 80 cm ³ / m ² , more preferably 30 to 60 cm ³ / m ² , depending on the concentration of the coating liquid (dispersion) as well as the depth. A preferable range of the cell volume Tdv at the center is 30 to 100 cm ³ / m ² , more preferably 40 to 120 cm ³ / m ² .
In the case of the lattice type, the thickness is 40 to 320 μm, more preferably 80 to 300 μm, and the preferable range of the cell depth Td in the center is 60 to 430 μm, more preferably 80 to 400 μm. Further, the preferable range of the cell volume Tcv at the end is 15 to 150 cm ³ / m ² , more preferably 40 to 120 cm ³ / m ² , although it depends on the coating liquid (dispersion) concentration as well as the depth. A preferable range of the cell volume Tdv at the center is 25 to 190 cm ³ / m ² , more preferably 40 to 160 cm ³ / m ² .

(Coating layer)
In the present invention, various coating layers can be used as the coating layer. In the present invention, a heat-resistant layer containing a filler and a resin binder is particularly preferable. The heat-resistant layer is a porous film formed by coating (applying) a surface of the polyolefin resin porous film with a filler-containing resin solution (dispersion) in which a filler and a resin binder are dissolved or dispersed in a solvent. Can be formed on the surface. Hereinafter, the components constituting the heat-resistant layer and a method for preparing a coating solution for forming the heat-resistant layer will be described.

(Filler)
Examples of the filler that can be used in the present invention include an inorganic filler and an organic filler, but are not particularly limited.

Examples of inorganic fillers include carbonates such as calcium carbonate, magnesium carbonate and barium carbonate; sulfates such as calcium sulfate, magnesium sulfate and barium sulfate; chlorides such as sodium chloride, calcium chloride and magnesium chloride, aluminum oxide and oxidation In addition to oxides such as calcium, magnesium oxide, zinc oxide, titanium oxide, and silica, silicates such as talc, clay, and mica can be used. Among these, barium sulfate and aluminum oxide are preferable.

Examples of organic fillers include ultra high molecular weight polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polytetrafluoroethylene, polyimide, polyether. Examples thereof include thermoplastic resins such as imide, melamine, and benzoguanamine, and thermosetting resins. Among these, cross-linked polystyrene and the like are particularly preferable.

The average particle size of the filler is preferably 0.1 μm or more, more preferably 0.2 μm or more, still more preferably 0.3 μm or more, and the upper limit is preferably 3.0 μm or less, more preferably 1.5 μm or less. It is. Setting the average particle size to 0.1 μm or more is preferable from the viewpoint of reducing the shrinkage rate of the laminated porous film to make it difficult to break the film and from the viewpoint of realizing heat resistance. On the other hand, setting the average particle size to 3.0 μm or less is preferable from the viewpoint of reducing the shrinkage rate of the laminated porous film and making it difficult to break the membrane. Moreover, it is preferable that an average particle diameter shall be 1.5 micrometers or less from a viewpoint of forming a porous layer with small layer thickness favorably, and the viewpoint of the dispersibility in the porous layer of an inorganic filler.
In the present embodiment, the “average particle diameter of the inorganic filler” is a value measured according to a method using SEM.

In the heat-resistant layer, the ratio of the filler to the total amount of the filler and the resin binder (hereinafter referred to as “F%”) is preferably 92% by mass or more, more preferably 95% by mass or more, and 98% by mass. The above is more preferable. If the F% is 92% by mass or more, it is preferable because a laminated porous film having connectivity can be produced and excellent air permeation performance can be exhibited.

(Resin binder)
As an example of a resin binder that can be used in the present invention, the filler, the polyolefin-based resin porous film can be satisfactorily bonded, is electrochemically stable, and a laminated porous film is used as a battery separator. There is no particular limitation as long as it is stable with respect to the organic electrolyte. Specifically, ethylene-acrylic acid copolymers such as ethylene-vinyl acetate copolymers (EVA, structural units derived from vinyl acetate of 20 to 35 mol%), ethylene-ethyl acrylate copolymers, fluororesins [Polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, etc.], fluorinated rubber, styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polybutadiene rubber (BR), poly Acrylonitrile (PAN), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), cyanoethyl polyvinyl alcohol, polyvinyl butyral (PVB), polyvinyl chloride Rupiroridon (PVP), poly N- vinyl acetamide, polyether, polyamide, polyimide, polyamideimide, polyaramide, crosslinked acrylic resin, polyurethane, and epoxy resin. These organic binders may be used alone or in combination of two or more. Among these, polyvinyl alcohol, polyvinylidene fluoride, styrene-butadiene rubber, carboxymethyl cellulose, and polyacrylic acid are preferable.

(Preparation method of coating solution)
In the present invention, a filler-containing resin solution (dispersion) in which the filler and the resin binder are dissolved or dispersed in a solvent is coated (applied) on the surface of the polyolefin resin porous film that has been surface-treated. By this, a heat-resistant layer can be formed on the surface of the porous film.

As the solvent, it is preferable to use a solvent in which the filler and the resin binder can be dissolved or dispersed uniformly and stably. Examples of such a solvent include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, water, ethanol, toluene, hot xylene, and hexane. In addition, in order to stabilize the inorganic filler-containing resin solution or to improve the coating property to the polyolefin resin porous membrane, the dispersion liquid contains a dispersant such as a surfactant, a thickener, a wetting agent, a disinfectant. Various additives such as foaming agents, pH adjusting agents including acids and alkalis, and the like may be added. These additives are preferably those that can be removed upon solvent removal or plasticizer extraction, but are electrochemically stable in the range of use of the lithium ion secondary battery, do not inhibit the battery reaction, and are up to about 200 ° C. If stable, it may remain in the battery (in the laminated porous film).

Examples of a method for dissolving or dispersing the filler and the resin binder in a solvent include, for example, a ball mill, a bead mill, a planetary ball mill, a vibrating ball mill, a sand mill, a colloid mill, an attritor, a roll mill, a high-speed impeller dispersion, a disperser, a homogenizer, and a high-speed Examples thereof include an impact mill, ultrasonic dispersion, a mechanical stirring method using stirring blades, and the like.

The solvent is preferably a solvent that can be removed from the dispersion applied to the polyolefin resin porous film. As a method for removing the solvent, any method that does not adversely affect the polyolefin resin porous film can be adopted without any particular limitation. As a method for removing the solvent, for example, a method in which a polyolefin resin porous film is fixed and dried at a temperature below its melting point, a method in which drying is performed at a low temperature under reduced pressure, or a resin binder is solidified by being immersed in a poor solvent for the resin binder. And a method of extracting the solvent at the same time.

In the present invention, after the surface treatment of the present invention is performed on the surface of the polyolefin resin porous film, the heat-resistant layer can be formed in-line, but after the surface treatment, the porous film is wound up and offline in a separate process. A heat-resistant layer can also be formed.

(Shape and physical properties of laminated porous film)
The total thickness of the laminated porous film obtained using the production method of the present invention is preferably 5 to 100 μm. More preferably, it is 8 to 50 μm, and still more preferably 10 to 30 μm. When it is used as a battery separator, if it is 5 μm or more, substantially necessary electrical insulation can be obtained. For example, even when a large force is applied to the protruding portion of the electrode, the battery separator is broken and short-circuited. It is difficult and safe. Moreover, since the electrical resistance of a laminated porous film can be made small if a film thickness is 100 micrometers or less, the performance of a battery can fully be ensured.

In the laminated porous film of the present invention, the porosity is preferably 30% to 70% as described above, and if it is 30% or more, it is possible to obtain a laminated porous film that secures communication and has excellent air permeability. . Moreover, if it is 70% or less, the intensity | strength of a laminated porous film will not fall easily, and it is preferable also from a viewpoint of handling.

As described above, the laminated porous film of the present invention has an air permeability measured in accordance with JIS P8117 of 2000 seconds / 100 ml or less.
In addition, when used as a battery separator, in order to provide SD characteristics, the air permeability after heating at 135 ° C. for 5 seconds is set to 10,000 seconds / 100 ml or more, and the pores are quickly closed when abnormal heat is generated. It shuts off so that troubles such as battery rupture can be avoided.

(battery)
A nonaqueous electrolyte battery containing the laminated porous film of the present invention as a battery separator will be described with reference to FIG.
Both electrodes of the positive electrode plate 21 and the negative electrode plate 22 are wound in a spiral shape so as to overlap each other via the battery separator 10, and the outside is stopped with a winding tape to form a wound body.

The wound body in which the positive electrode plate 21, the battery separator 10 and the negative electrode plate 22 are integrally wound is accommodated in a bottomed cylindrical battery case and welded to the positive and negative electrode lead bodies 24 and 25. Next, the electrolyte is injected into the battery can, and after the electrolyte has sufficiently penetrated into the battery separator 10 or the like, the positive electrode lid 27 is sealed around the opening periphery of the battery can via the gasket 26, and precharging and aging are performed. A secondary battery 20 made of a cylindrical nonaqueous electrolyte battery is produced.

As the electrolytic solution, an electrolytic solution in which a lithium salt is used as an electrolyte and this is dissolved in an organic solvent is used. The organic solvent is not particularly limited. For example, esters such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate, methyl propionate or butyl acetate, and nitriles such as acetonitrile. 1,2-dimethoxyethane, 1,2-dimethoxymethane, dimethoxypropane, 1,3-dioxolane, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran or 4-methyl-1,3-dioxolane, or sulfolane. These may be used alone or in combination of two or more.
Among them, an electrolyte obtained by dissolving lithium hexafluorophosphate (LiPF ₆₎ at a rate of 1.0 mol / L in a solvent obtained by mixing 2 parts by mass of methyl ethyl carbonate relative to ethylene carbonate 1 part by weight is preferred.

As the negative electrode, an alkali metal or a compound containing an alkali metal integrated with a current collecting material such as a stainless steel net is used. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the compound containing an alkali metal include an alloy of an alkali metal and aluminum, lead, indium, potassium, cadmium, tin or magnesium, a compound of an alkali metal and a carbon material, a low potential alkali metal and a metal oxide, and the like. Or a compound with a sulfide or the like.
When a carbon material is used for the negative electrode, the carbon material may be any material that can be doped and dedoped with lithium ions, such as graphite, pyrolytic carbons, cokes, glassy carbons, a fired body of an organic polymer compound, Mesocarbon microbeads, carbon fibers, activated carbon and the like can be used.

In this embodiment, as a negative electrode, a carbon material having an average particle size of 10 μm is mixed with a solution in which vinylidene fluoride is dissolved in N-methylpyrrolidone to form a slurry, and this negative electrode mixture slurry is passed through a 70-mesh net. After removing the large particles, uniformly apply to both sides of the negative electrode current collector made of a strip-shaped copper foil having a thickness of 18 μm and dry, and then compression-molded with a roll press machine, cut, strip-shaped negative electrode plate and We use what we did.

As the positive electrode, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, manganese dioxide, metal oxide such as vanadium pentoxide or chromium oxide, metal sulfide such as molybdenum disulfide, etc. are used as active materials. , These positive electrode active materials are combined with conductive additives and binders such as polytetrafluoroethylene as appropriate, and finished with a current collector material such as a stainless steel mesh as a core material. It is done.

In the present embodiment, a strip-like positive electrode plate produced as follows is used as the positive electrode. That is, lithium graphite oxide (LiCoO ₂ ) is added with phosphorous graphite as a conductive additive at a mass ratio of 90: 5 (lithium cobalt oxide: phosphorous graphite) and mixed, and this mixture and polyvinylidene fluoride are mixed with N Mix with a solution in methylpyrrolidone to make a slurry. This positive electrode mixture slurry is passed through a 70-mesh net to remove large particles, and then uniformly applied to both sides of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm, dried, and then compressed by a roll press. After forming, it is cut into a strip-like positive electrode plate.

[Example]
EXAMPLES Examples and comparative examples will be shown below, and the present invention will be described in more detail. However, the present invention is not limited to these.

(Polyolefin resin porous film)
As the A layer, polypropylene resin (Prime Polymer Co., Prime Polypro F300SV, density: 0.90 g / cm ³ , MFR: 3.0 g / 10 min) and β crystal nucleating agent 3,9-bis [4 -(N-cyclohexylcarbamoyl) phenyl] -2,4,8,10-tetraoxaspiro [5.5] undecane was prepared. Each raw material is blended at a ratio of 0.2 part by mass of β-crystal nucleating agent with respect to 100 parts by mass of polypropylene resin, and the same direction twin screw extruder manufactured by Toshiba Machine Co., Ltd. (caliber: 40 mmφ, L / D: 32), melted and mixed at a preset temperature of 300 ° C., cooled and solidified in a water bath, cut into strands with a pelletizer, and produced polypropylene resin composition pellets. The β activity of the polypropylene resin composition was 80%.

Next, as a mixed resin composition constituting the B layer, glycerin is added to 100 parts by mass of high-density polyethylene (manufactured by Nippon Polytechnics, Novatec HD HF560, density: 0.963 g / cm ³ , MFR: 7.0 g / 10 min). Add 0.04 parts by mass of monoester and 10 parts by mass of microcrystalline wax (Nisei Seiwa Co., Ltd., Hi-Mic 1080), melt and knead at 220 ° C. using the same type twin screw extruder and pellets A resin composition processed into a shape was obtained.

Using the two kinds of raw materials, using a separate extruder so that the outer layer is A layer and the intermediate layer is B layer, it is extruded from a die for lamination molding through a feed block of two kinds and three layers, By cooling and solidifying with a casting roll, a two-layered / three-layered film-like product of A layer / B layer / A layer was produced.
The laminated film-like product is stretched 4.6 times in the longitudinal direction using a longitudinal stretching machine, and then stretched 1.9 times in the transverse direction at 98 ° C. by a transverse stretching machine, and then subjected to heat setting / relaxation treatment. It was. As a result, a laminated porous film made of polyolefin resin having a film thickness of 20 μm and an air permeability of 450 seconds / 100 ml was obtained.

The resulting porous film made of polyolefin resin was prepared using a corona treatment device (Kasuga Denki Co., Ltd., aluminum 5 type electrode, 2 ridges x 6, line speed: 50 m / min, treatment output: 1.5 kW), Corona surface treatment was performed under the conditions of the following examples.

(Coating fluid for heat-resistant layer)
Alumina (Sumitomo Chemical Co., Sumiko Random AA-03, average particle size: 0.3 μm) 39.2 parts by mass, polyvinyl alcohol (Kuraray Co., Ltd., PVA120, saponification degree: 98.0 to 99.0, average polymerization degree) : 2000) A dispersion in which 0.8 part by mass was dispersed in 60.0 parts by mass of water was obtained.

[Example 1]
A gravure roll (roll diameter 60 mm, roll width 400 mm, lattice type, cell depth 260 μm, cell volume 110 cm ³ / m ² ) shown in FIG. 1A is applied to the base material (350 mm width) of the polyolefin resin porous film. The coating solution was continuously coated by a kiss reverse gravure coating method to form a coating layer, and a 1000 m film roll was prepared.

(Thickness)
The winding end portion of the obtained film roll was collected, and the thickness in the width direction of the film was measured using a tabletop thickness meter RC-1 manufactured by Meisen Co., Ltd., and the values of the thicknesses Ta and Tb were read. The measurement results are shown in Table 1.
(Wrinkle)
The wrinkle state of the end portion and the non-laminated portion of the clothing layer at the center portion was visually observed, and wrinkle was evaluated according to the following criteria.
◎: No wrinkles ○: Slightly wrinkled △: Partially large wrinkles ×: Many large wrinkles around the circumference

[Comparative Example 1]
1000 m as in Example 1 except that the gravure roll was changed to the roll shown in FIG. 1C (roll diameter 60 mm, roll width 400 mm, diagonal line type, cell depth: 90 μm, cell volume 40 cm ³ / m ² ). A film roll was prepared.

According to the results of Table 1, the film thickness Ta at the end of the coating layer laminated portion and the film thickness Tb at the center satisfy the relational expression of Ta ≦ Tb and the case where the relational expression is not satisfied. When compared with Comparative Example 1 in which the so-called ear height was increased, it was confirmed that a significant difference occurred in the generation of wrinkles.

Claims (19)

1. A coating layer is partially laminated on at least one surface of the polyolefin-based resin porous film, and a laminated porous film in which at least one coating layer laminate portion X and at least one non-laminate portion Y are formed is wound. A laminated porous film roll having a film thickness Ta at an end of at least one coating layer laminate portion X and a film thickness Tb at a central portion,
   Ta ≦ Tb
   The laminated porous film roll satisfying the above relational expression, and the winding length of the laminated porous film is 1000 m or more.
2. The laminated porous film roll according to claim 1, wherein the non-laminated portion Y is provided at an end in the film width direction.
3. The laminated porous film roll according to claim 1 or 2, wherein the non-laminated portion Y is provided at a place other than an end portion in the film width direction.
4. The film thickness Ta1 at one end and the film thickness Ta2 at the other end in at least one coating layer laminate X are:
   | Ta1-Ta2 | ≦ 3μm
   The laminated porous film roll according to any one of claims 1 to 3, which satisfies the following relational expression:
5. The maximum value Tmax and the minimum value Tmin of the film thickness at the end of all the coating layer laminate portions X are
   (Tmax−Tmin) ≦ 3 μm
   The laminated porous film roll according to any one of claims 1 to 4, which satisfies the relational expression:
6. The laminated porous film roll according to any one of claims 1 to 5, wherein the width of at least one non-laminated portion Y is 5 mm to 100 mm.
7. The laminated porous film roll according to any one of claims 1 to 6, wherein the thickness of the coating layer at the central portion of at least one coating layer laminate portion X is 0.5 µm to 50 µm.
8. The ratio of the thickness of the coating layer to the thickness of the polyolefin resin porous film in the central portion of at least one coating layer laminate portion X is 1/1 to 1/6. Laminated porous film roll.
9. The laminated porous film roll according to any one of claims 1 to 8, wherein the polyolefin-based resin porous film has a thickness of 5 袖 m to 50 袖 m.
10. The laminated porous film roll according to any one of claims 1 to 9, wherein the width of the laminated porous film is 0.3 m to 3 m.
11. The laminated porous film roll according to any one of claims 1 to 10, wherein coating layers are laminated on both surfaces of the polyolefin resin porous film.
12. The laminated porous film roll according to any one of claims 1 to 11, wherein the coating layer comprises a filler and a resin binder.
13. The laminated porous film roll according to any one of claims 1 to 12, wherein the coating layer is laminated by coating.
14. The laminated porous film roll according to any one of claims 1 to 13, which is used as a separator for a non-aqueous electrolyte battery.
15. A coating layer is partially laminated on at least one surface of the polyolefin-based resin porous film, and a laminated porous film in which at least one coating layer laminate portion X and at least one non-laminate portion Y are formed is wound. A method for producing a laminated porous film roll comprising:
    The coating layer is formed by gravure coating, and the cell depth Tc at the end of the engraving portion Z corresponding to at least one coating layer laminated portion X in the film width direction of the gravure roll used for gravure coating and the central portion Cell depth Td is Tc ≦ Td
    The manufacturing method of the lamination | stacking porous film roll formed by satisfy | filling the relational expression of these.
16. A coating layer is partially laminated on at least one surface of the polyolefin-based resin porous film, and a laminated porous film in which at least one coating layer laminate portion X and at least one non-laminate portion Y are formed is wound. A method for producing a laminated porous film roll comprising:
    The method for producing a laminated porous film roll, wherein the coating layer is formed by gravure coating, and a gravure roll cell used for gravure coating has a symmetrical shape.
17. The method for producing a laminated porous film roll according to claim 15 or 16, wherein the cell has a trapezoidal shape in the depth direction.
18. The rotation direction of the gravure roll at the time of gravure coating is opposite to the conveyance direction of the base material at a position where the paint is transferred to the base material. Manufacturing method of laminated porous film rolls.
19. The laminate according to claim 18, wherein when transferring the paint, the base material is brought into contact with the gravure roll via a guide roll arranged before and after the gravure roll without using a back roll, and the paint is transferred. A method for producing a porous film roll.

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