JP2021174709A - Method for manufacturing laminate separator for nonaqueous electrolyte secondary battery, and laminate separator for nonaqueous electrolyte secondary battery - Google Patents

Abstract

To materialize a laminate separator which is suppressed from being curled, or not curled.SOLUTION: A method for manufacturing a laminate separator for a nonaqueous electrolyte secondary battery according to an embodiment of the present invention comprises the step of adjusting a temperature for heating a raw sheet or film having a polyolefin porous film and a porous layer during a falling-rate drying period, thereby making control so that a laminate separator for a nonaqueous electrolyte secondary battery satisfies a particular formula.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery and a laminated separator for a non-aqueous electrolytic solution secondary battery.

Non-aqueous electrolyte secondary batteries, especially lithium-ion secondary batteries, are widely used as batteries for personal computers, mobile phones, mobile information terminals, etc. due to their high energy density, and have recently been developed as in-vehicle batteries. It has been done. The development of a separator is underway as a member of the non-aqueous electrolyte secondary battery.

By the way, Patent Document 1 discloses a microporous membrane made of polyethylene resin, and it is said that it can also be used as a separator for a non-aqueous electrolyte battery.

Japanese Unexamined Patent Publication No. 2004-016930

As a separator, a laminated separator in which a porous layer containing a resin is laminated on a base material is also known. However, in the above-mentioned prior art, only the manufacturing method of the base material is disclosed, and from the viewpoint of realizing a manufacturing method suitable for the laminated separator, a curl amount suppressed, or a laminated separator without curl. There was room for improvement.

One aspect of the present invention is to realize a laminated separator having a reduced amount of curl or no curl.

As a result of diligent research conducted by the present inventor in order to solve the above-mentioned problems, the curl of the obtained laminated separator is improved by adjusting the temperature during the reduction drying period so that the laminated separator satisfies a specific formula. We have found what we can do and have completed the present invention. The present invention includes the following aspects.

<1> A method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery, which comprises a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film. A step of controlling the laminated separator for a non-aqueous electrolytic solution secondary battery to satisfy the following formula (1) by adjusting the temperature at which the separator raw material provided with the polyolefin porous film and the porous layer is heated. A method for manufacturing a laminated separator for a non-aqueous electrolyte secondary battery, including the above.
_{100 × (T L1 -T L0)} / T L0 -100 × (T B1 -T B0) / T B0 <22 ··· (1)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL1 : The length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB1 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.

<2> The laminated separator for a non-aqueous electrolytic solution secondary battery according to <1>, wherein the laminated separator for a non-aqueous electrolytic solution secondary battery is further controlled to satisfy the following formula (2) during the rate reduction drying period. Manufacturing method.
_{100 × (T L2 -T L0)} / T L0 -100 × (T B2 -T B0) / T B0 <36 ··· (2)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL2 : Length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB2 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.

<3> The non-aqueous electrolyte secondary according to <1> or <2>, wherein the laminated separator for the non-aqueous electrolyte secondary battery is further controlled to satisfy the following formula (3) during the rate reduction drying period. A method for manufacturing a laminated separator for a battery.
_{100 × (T L3 -T L0)} / T L0 -100 × (T B3 -T B0) / T B0 <60 ··· (3)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
T _L3: nonaqueous electrolyte pulling TD direction stacked separator for secondary batteries 23 ° C. tensile stress in the TD direction when the 120MPa length.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
T _B3: for a non-aqueous electrolyte secondary battery porous polyolefin was peeled from the laminate separator membrane by pulling in the TD direction at 23 ° C. tensile stress in the TD direction when the 120MPa length.

<4> The resin is a resin selected from the group consisting of (meth) acrylate-based resins, fluororesins, polyamide-based resins, polyimide-based resins, polyester-based resins, and water-soluble polymers. <1> The method for producing a laminated separator for a non-aqueous electrolyte secondary battery according to any one of <3>.

<5> The method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery according to <4>, wherein the polyamide resin is an aramid resin.

<6> A laminated separator for a non-aqueous electrolytic solution secondary battery, comprising a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film, and satisfying the following formula (1).
_{100 × (T L1 -T L0)} / T L0 -100 × (T B1 -T B0) / T B0 <22 ··· (1)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL1 : The length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB1 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.

<7> The laminated separator for a non-aqueous electrolyte secondary battery according to <6>, which further satisfies the following formula (2).
_{100 × (T L2 -T L0)} / T L0 -100 × (T B2 -T B0) / T B0 <36 ··· (2)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL2 : Length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB2 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.

<8> The laminated separator for a non-aqueous electrolyte secondary battery according to <6> or <7>, which further satisfies the following formula (3).
_{100 × (T L3 -T L0)} / T L0 -100 × (T B3 -T B0) / T B0 <60 ··· (3)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
T _L3: nonaqueous electrolyte pulling TD direction stacked separator for secondary batteries 23 ° C. tensile stress in the TD direction when the 120MPa length.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
T _B3: for a non-aqueous electrolyte secondary battery porous polyolefin was peeled from the laminate separator membrane by pulling in the TD direction at 23 ° C. tensile stress in the TD direction when the 120MPa length.

<9> The resin is a resin selected from the group consisting of (meth) acrylate-based resins, fluororesins, polyamide-based resins, polyimide-based resins, polyester-based resins, and water-soluble polymers. <6> The laminated separator for a non-aqueous electrolyte secondary battery according to any one of <8>.

<10> The laminated separator for a non-aqueous electrolytic solution secondary battery according to <9>, wherein the polyamide resin is an aramid resin.

According to one aspect of the present invention, it is possible to provide a laminated separator with a reduced amount of curl or no curl.

It is a schematic diagram for demonstrating the principle of curl generation. It is a figure for demonstrating the classification of a drying period. It is the schematic of the curl amount measuring apparatus in an Example. FIG. 3 is an enlarged view of CC'in FIG. 3 viewed from a direction perpendicular to the plane of the laminated separator 10. FIG. 6 is a cross-sectional view taken along the line DD'viewed from the CC'direction of the laminated separator 10 of FIG.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments may be appropriately combined. The obtained embodiments are also included in the technical scope of the present invention.

Unless otherwise specified in the present specification, "A to B" representing a numerical range means "A or more and B or less". Further, in the present specification, the MD direction is intended to be the transport direction of the original separator. Further, the TD direction is intended to be a direction horizontal to the surface of the original separator and perpendicular to the MD direction.

[1. Principle of curl generation]
The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention includes a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film. In the present specification, the laminated separator for a non-aqueous electrolyte secondary battery is also simply referred to as a "laminated separator". Further, the polyolefin porous film is also simply referred to as "porous film". In the present specification, the original separator material means a long and wide laminated separator before cutting.

The raw separator and the laminated separator can be obtained, for example, by applying a coating liquid containing a resin to at least one surface of a porous film as a base material and then drying it. This drying causes the porous layer to shrink, which can result in curls in the laminated separator.

FIG. 1 is a schematic diagram for explaining the principle of curl generation. When the separator raw fabric 10a provided with the porous layer 2 on the porous film 1 is dried, the porous layer 2 easily shrinks as the solvent evaporates. Therefore, the porous layer 2 side like the separator raw fabric 10b. Curl to. As the drying progresses further, the balance between the shrinkage rate of the porous layer 2 and the shrinkage rate of the porous film 1 is optimized, and curl is eliminated as in the case of the original separator 10c. However, if the drying progresses excessively, the shrinkage of the porous film 1 becomes larger than that of the porous layer 2, and the film curls toward the porous film 1 side like the separator raw fabric 10d. From this, the present inventor has found that by optimizing the drying conditions, it is possible to realize a laminated separator in which the amount of curl is suppressed or there is no curl.

In addition, the drying period of general materials is classified into three stages. FIG. 2 is a diagram for explaining the classification of the drying period. The shape of the curve shown in FIG. 2 is just an example. First, as the drying time progresses, there is a heating period in which the surface temperature of the material rises and the moisture content begins to gradually decrease. Next, a constant drying period comes, in which the surface temperature of the material is almost constant, but the moisture content decreases. After that, the surface temperature of the material rises again, and a reduced drying period comes in which the moisture content approaches the equilibrium moisture content.

In the case of a laminated separator, the amount of curl increases when the difference between the shrinkage rate of the porous film and the shrinkage rate of the porous layer during this drying period is large. In particular, the present inventor has found that the phenomenon in which the curl on the porous layer side is once eliminated and then the curl on the porous film side tends to occur during the lapse rate drying period. From this, the present inventor has focused on adjusting the temperature at which the separator raw fabric is heated during the lapse rate drying period.

Furthermore, the present inventor has conducted extensive research, and the difference between the tensile elongation of the laminated separator in the tensile test and the tensile elongation of the porous film peeled from the laminated separator reflects the curl amount. It was found that the difference in tensile elongation can be controlled by adjusting the temperature during the rate reduction drying period. Based on these, the present inventor has completed the manufacturing method according to one embodiment of the present invention, which will be described later.

[2. Manufacturing method of laminated separator for non-aqueous electrolyte secondary battery]
The method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention is a non-aqueous electrolysis method comprising a polyolefin porous film and a porous layer containing a resin on at least one surface of the polyolefin porous film. A method for producing a laminated separator for a liquid secondary battery, wherein the temperature at which the separator raw material including the polyolefin porous film and the porous layer is heated during the rate reduction drying period is adjusted to control the temperature of the non-aqueous electrolytic solution. The step of controlling the laminated separator for a secondary battery so as to satisfy the following formula (1) is included.
_{100 × (T L1 -T L0)} / T L0 -100 × (T B1 -T B0) / T B0 <22 ··· (1)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL1 : The length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB1 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.

Wherein _{(1), 100 × (T} L1 -T L0) / T L0 represents the tensile elongation of the laminated separator. _{Further, 100 × (T B1 -T B0} ) / T B0 represents the tensile elongation of the porous film is peeled off from the laminated separator. That is, the left side of the equation (1) represents the difference in tensile elongation. In the present specification, the difference in tensile elongation represented by the left side of this formula (1) is also referred to as "80 MPa tensile elongation difference". The present inventor has found that when the difference in tensile elongation at 80 MPa is less than 22%, a laminated separator with a reduced amount of curl or no curl can be obtained. Then, by adjusting the temperature during the lapse rate drying period as described above, the difference in tensile elongation of 80 MPa can be controlled. The 80 MPa tensile elongation difference is more preferably 20% or less, and further preferably 18% or less.

Further, it is preferable to control the laminated separator for the non-aqueous electrolytic solution secondary battery so as to further satisfy the following formula (2).
_{100 × (T L2 -T L0)} / T L0 -100 × (T B2 -T B0) / T B0 <36 ··· (2)
_TL0 and _TB0 are as described above. T _L2 represents the length of the TD direction when the tensile stress to pull the TD direction laminated separator 23 ° C. is 100 MPa. T _B2 represents the length of the TD direction when peeled porous film by pulling in the TD direction at 23 ° C. tensile stress from the laminated separator is 100 MPa. In the present specification, the difference in tensile elongation represented by the left side of this formula (2) is also referred to as "100 MPa tensile elongation difference". The 100 MPa tensile elongation difference is more preferably 35% or less, and further preferably 30% or less.

Further, it is preferable to control the laminated separator for the non-aqueous electrolytic solution secondary battery so as to further satisfy the following formula (3).
_{100 × (T L3 -T L0)} / T L0 -100 × (T B3 -T B0) / T B0 <60 ··· (3)
_TL0 and _TB0 are as described above. T _L3 has a tensile stress to pull the TD direction laminated separator 23 ° C. is the length of the TD direction when the 120 MPa. T _B3 has a tensile stress to pull the TD direction at 23 ° C. The porous film was peeled from the laminate separator is the length of the TD direction when the 120 MPa. In the present specification, the difference in tensile elongation represented by the left side of this formula (2) is also referred to as "120 MPa tensile elongation difference". The difference in tensile elongation at 120 MPa is more preferably 55% or less, and even more preferably 50% or less.

<Manufacturing method of polyolefin porous film>
The porous film contains a polyolefin resin as a main component and has a large number of pores connected to the inside thereof, so that gas and liquid can pass from one surface to the other. The proportion of the polyolefin-based resin in the porous film is 50% by volume or more, more preferably 90% by volume or more, and further preferably 95% by volume or more of the entire porous film.

The method for producing the porous film is not particularly limited. For example, a sheet-shaped polyolefin resin composition is prepared by kneading a polyolefin resin, a pore-forming agent such as an inorganic filler or a plasticizer, and optionally an antioxidant or the like, and then extruding the resin. Then, the pore-forming agent is removed from the sheet-shaped polyolefin resin composition with an appropriate solvent. Then, the polyolefin resin composition from which the pore-forming agent has been removed is stretched to produce a polyolefin porous film.

The said polyolefin resin, and more preferably a weight average molecular weight are included high molecular weight component of ^{5 × 10 5 ~15 × 10 6} . In particular, it is more preferable that the polyolefin resin contains a high molecular weight component having a weight average molecular weight of 1 million or more because the strength of the separator for a non-aqueous electrolytic solution secondary battery is improved.

The polyolefin-based resin, which is a thermoplastic resin, is, for example, a homopolymer or a homopolymer obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Coalescence is mentioned. Examples of the homopolymer include polyethylene, polypropylene, and polybutene. Further, as the copolymer, for example, an ethylene-propylene copolymer can be mentioned.

Of these, polyethylene is more preferable because it can prevent an excessive current from flowing at a lower temperature. Preventing this excessive current from flowing is also called shutdown. Examples of the polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), ultra-high molecular weight polyethylene having a weight average molecular weight of 1 million or more, and the like. Of these, ultra-high molecular weight polyethylene having a weight average molecular weight of 1 million or more is more preferable.

The inorganic filler is not particularly limited, and examples thereof include an inorganic filler, specifically calcium carbonate and the like. The plasticizer is not particularly limited, and examples thereof include low molecular weight hydrocarbons such as liquid paraffin.

Specific examples of the method for producing a porous film include a method including the following steps.

(I) A step of kneading an ultra-high molecular weight polyethylene, a low molecular weight polyethylene having a weight average molecular weight of 10,000 or less, a pore-forming agent such as calcium carbonate or a plasticizer, and an antioxidant to obtain a polyolefin resin composition.

(Ii) A step of rolling the obtained polyolefin resin composition with a pair of rolling rollers and gradually cooling the obtained polyolefin resin composition while pulling it with winding rollers having different speed ratios to form a sheet.

(Iii) A step of removing the pore-forming agent from the obtained sheet with an appropriate solvent.

(Iv) A step of stretching a sheet from which the pore-forming agent has been removed at an appropriate stretching ratio.

The film thickness of the porous film is preferably 4 to 40 μm, more preferably 5 to 30 μm, and even more preferably 6 to 15 μm.

The weight weight of the porous film can be appropriately determined in consideration of strength, film thickness, weight and handleability. However, to be able to increase the weight energy density and volume energy density of the nonaqueous electrolyte secondary battery, wherein the fabric weight is preferably 4~20g / ^{m 2,} in 4~12g / ^{m 2} More preferably, it is more preferably 5 to 10 g / m ² .

The air permeability of the porous film is preferably 30 to 500 s / 100 mL, and more preferably 50 to 300 s / 100 mL in terms of Gale value. When the porous film has the air permeability, sufficient ion permeability can be obtained.

The porosity of the porous film is preferably 20 to 80% by volume so that the retention amount of the electrolytic solution can be increased and the function of reliably blocking the flow of an excessive current at a lower temperature can be obtained. More preferably, it is 30 to 75% by volume. Further, the pore diameter of the pores of the porous film shall be 0.3 μm or less so that sufficient ion permeability can be obtained and particles can be prevented from entering the positive electrode and the negative electrode. Is preferable, and it is more preferably 0.14 μm or less.

<Manufacturing method of porous layer>
The porous layer can be formed on one or both sides of the porous film. The porous layer is preferably an insulating porous layer.

A porous layer can be formed by using the coating liquid obtained by dissolving or dispersing the resin in a solvent and dispersing the filler. It can be said that the solvent is a solvent for dissolving the resin and a dispersion medium for dispersing the resin or the filler. Examples of the coating liquid forming method include a mechanical stirring method, an ultrasonic dispersion method, a high-pressure dispersion method, a media dispersion method, and the like.

Examples of the method for forming the porous layer include a method in which a coating liquid is applied to the surface of the porous film and then the solvent is removed.

It is preferable that the resin is insoluble in the electrolytic solution of the battery and is electrochemically stable in the range of use of the battery.

Specifically, the resin includes, for example, polyolefin; (meth) acrylate resin; fluorine-containing resin; polyamide resin; polyimide resin; polyester resin; rubbers; melting point or glass transition temperature of 180 ° C. or higher. Resins; water-soluble polymers; polycarbonates, polyacetals, polyether ether ketones and the like.

Among the above-mentioned resins, (meth) acrylate-based resins, fluorine-containing resins, polyamide-based resins, polyimide-based resins, polyester-based resins, and water-soluble polymers are preferable.

Examples of the fluororesin include polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and fluororesin. Vinylidene-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetra Examples thereof include fluoroethylene copolymers, ethylene-tetrafluoroethylene copolymers, and fluoropolymers among the fluororesins having a glass transition temperature of 23 ° C. or lower.

As the polyamide-based resin, aramid resins such as aromatic polyamide and totally aromatic polyamide are preferable.

Specific examples of the aramid resin include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (parabenzamide), poly (metabenzamide), and poly (4,4'-benzanilide terephthalamide). Amide), poly (paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly (metaphenylene-4,4'-biphenylenedicarboxylic acid amide), poly (paraphenylene-2,6-naphthalenedicarboxylic acid amide), Poly (metaphenylene-2,6-naphthalenedicarboxylic acid amide), poly (2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2 , 6-Dichloroparaphenylene terephthalamide copolymer and the like. Of these, poly (paraphenylene terephthalamide) is more preferable.

As the polyester-based resin, aromatic polyesters such as polyarylate and liquid crystal polyesters are preferable.

Examples of rubbers include styrene-butadiene copolymers and their hydrides, methacrylate copolymers, acrylonitrile-acrylic acid ester copolymers, styrene-acrylic acid ester copolymers, ethylene propylene rubber, polyvinyl acetate and the like. Can be mentioned.

Examples of the resin having a melting point or a glass transition temperature of 180 ° C. or higher include polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.

Examples of the water-soluble polymer include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, polymethacrylic acid and the like.

As the resin used for the porous layer, only one type may be used, or two or more types may be used in combination.

Examples of the filler include organic fine particles and inorganic fine particles. Examples of the organic fine particles include the above-mentioned fine particles made of a resin. Examples of the inorganic fine particles include calcium carbonate, talc, clay, kaolin, silica, hydrotalcite, diatomaceous earth, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, aluminum hydroxide, boehmite, magnesium hydroxide, and oxidation. Examples thereof include fine particles made of inorganic substances such as calcium, magnesium oxide, titanium oxide, titanium nitride, alumina (aluminum oxide), aluminum nitride, mica, zeolite and glass. These inorganic fine particles are insulating fine particles. Only one type of the fine particles may be used, or two or more types may be used in combination.

Among the above fine particles, fine particles made of an inorganic substance are preferable, and fine particles made of an inorganic oxide such as silica, calcium oxide, magnesium oxide, titanium oxide, alumina, mica, zeolite, aluminum hydroxide, or boehmite are more preferable, and silica is more preferable. , At least one fine particle selected from the group consisting of magnesium oxide, titanium oxide, aluminum hydroxide, boehmite and alumina is more preferable, and alumina is particularly preferable.

The content of the fine particles in the porous layer is preferably 10 to 99% by weight, more preferably 20 to 95% by weight of the porous layer. By setting the content of the fine particles in the above range, sufficient ion permeability can be obtained, and the mechanical properties and heat resistance of the porous layer can be improved.

The solvent is preferably a solvent that does not adversely affect the substrate, dissolves the resin uniformly and stably, and disperses the filler uniformly and stably. Examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, acetone, alcohols (isopropyl alcohol, ethanol, etc.) and water, and a mixture of two or more of these. Examples include a solvent.

The coating liquid may appropriately contain a dispersant, a plasticizer, a surfactant, a pH adjuster and the like as components other than the resin and the filler.

As a method for applying the coating liquid, a conventionally known method can be adopted, and specific examples thereof include a gravure coater method, a dip coater method, a bar coater method, and a die coater method.

When the coating liquid contains an aramid resin, the aramid resin can be precipitated by giving humidity to the coated surface. As a result, a porous layer may be formed.

The method for preparing the aramid resin is not particularly limited, and examples thereof include a condensation polymerization method of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide. In that case, the resulting aramid resin is substantially made up of repeating units in which the amide bond is bonded at the para position of the aromatic ring or a similar orientation position. The orientation position according to the para position is an orientation position extending coaxially or parallelly in the opposite direction, for example, 4,4'-biphenylene, 1,5-naphthalene, 2,6-naphthalene, or the like.

Specific methods for preparing a solution of poly (paraphenylene terephthalamide) include, for example, a method including the steps shown in (1) to (4) below.

(1) N-Methyl-2-pyrrolidone is charged in a dried flask, calcium chloride dried at 200 ° C. for 2 hours is added, and the temperature is raised to 100 ° C. to completely dissolve the calcium chloride.

(2) After returning the temperature of the solution obtained in (1) to room temperature, para-phenylenediamine is added to completely dissolve the para-phenylenediamine.

(3) While maintaining the temperature of the solution obtained in (2) at 20 ± 2 ° C., terephthalic acid dichloride is divided into 10 parts and added every 5 minutes.

(4) Poly (paraphenylene terephthalamide) was obtained by aging the solution obtained in (3) for 1 hour while maintaining the temperature at 20 ± 2 ° C., and then stirring under reduced pressure for 30 minutes to remove air bubbles. ) Is obtained.

It may include a step of cleaning the porous film and the porous layer after precipitation. When the porous layer contains an aramid resin, for example, water, an aqueous solution, or an alcohol-based solution is preferably used as the cleaning liquid.

<Drying process>
The method for producing a laminated separator may include a drying step of drying the porous layer after washing. In the drying step, the temperature may be adjusted at least during the reduced drying period. The temperature during the lapse rate drying period is preferably more than 100 ° C, more preferably more than 100 ° C and 120 ° C or less, further preferably 105 to 120 ° C, and particularly preferably 105 to 115 ° C. preferable.

In the drying step, it may be heated stepwise at a plurality of different temperatures. You may heat at a lower temperature than the lapse rate drying period before reaching the lapse rate drying period, that is, in the heating period and the constant rate drying period. Further, the temperature may be increased in the order of heating period, constant rate drying period and reduced rate drying period. The temperature during the heating period is preferably less than 100 ° C, more preferably 90 ° C or higher and lower than 100 ° C. The temperature during the constant drying period is preferably 90 to 110 ° C, more preferably 95 to 105 ° C, and even more preferably 95 to 100 ° C.

For example, the method for producing a laminated separator may include a first drying step, a second drying step, and a third drying step as the drying step. The first drying step, the second drying step, and the third drying step may correspond to the above-mentioned heating period, constant rate drying period, and reduced rate drying period, respectively.

Examples of the drying means include hot air drying and roller heating. In roller heating, the separator raw fabric is dried by bringing the separator raw fabric into contact with the heated roller. Examples of the method of heating the rollers include a method of supplying a heat medium to the inside of the rollers and circulating the heat medium. In this case, the heating temperature described above represents the temperature of the heat medium. Further, by using different types of heat media, the separator raw material can be heated at different temperatures. As the heat medium, for example, hot water, oil, steam or the like is used. For example, hot water may be supplied to the low temperature roller and steam may be supplied to the high temperature roller.

For example, a first heating roller group, a second heating roller group, and a third heating roller group may be used as the means for drying. These may be made to correspond to the above-mentioned heating period, constant rate drying period and reduced rate drying period.

[3. Laminated Separator for Non-Aqueous Electrolyte Secondary Battery]
The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention includes a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film, and has the above-mentioned formula (1). ) Satisfies. Further, it is preferable that the laminated separator further satisfies the above-mentioned formulas (2) and / or formulas (3).

The porous layer may be arranged between the porous film and at least one of the positive electrode and the negative electrode as a member constituting the non-aqueous electrolyte secondary battery. The porous layer may be arranged between the porous film and at least one of the positive electrode and the negative electrode so as to be in contact with them. The porous layer arranged between the porous film and at least one of the positive electrode and the negative electrode may be one layer or two or more layers. The porous layer is preferably an insulating porous layer.

When the porous layer is laminated on one side of the porous film, the porous layer is preferably laminated on the surface of the porous film facing the positive electrode. More preferably, the porous layer is laminated on the surface in contact with the positive electrode.

The film thickness of the porous layer is preferably in the range of 0.5 μm to 10 μm, and more preferably in the range of 1 μm to 8 μm, from the viewpoint of ensuring battery safety and high energy density. .. When the thickness of the porous layer is 0.5 μm or more per layer, internal short circuits due to damage of the non-aqueous electrolyte secondary battery can be sufficiently suppressed, and the amount of the electrolytic solution retained in the porous layer. Will be sufficient. On the other hand, when the film thickness of the porous layer is 10 μm or less per layer, the permeation resistance of lithium ions is suppressed in the non-aqueous electrolytic solution secondary battery, so that deterioration of rate characteristics and cycle characteristics can be suppressed. Further, since the increase in the distance between the positive electrode and the negative electrode can be suppressed, the decrease in the internal volumetric efficiency of the non-aqueous electrolyte secondary battery can be suppressed.

The weight weight of the porous layer can be appropriately determined in consideration of the strength, film thickness, weight and handleability of the porous layer. Weight basis weight of the porous layer, the porous per Soisso is preferably 0.5~10.0g / ^{m 2,} more preferably from 0.5~8.0g / ^{m 2,} 0.5 It is more preferably ~ 5.0 g / m ^2. By setting the weight of the porous layer in these numerical ranges, the weight energy density and the volumetric energy density of the non-aqueous electrolyte secondary battery can be increased. When the weight of the porous layer exceeds the above range, the non-aqueous electrolyte secondary battery tends to be heavy.

The porosity of the porous layer is preferably 20 to 90% by volume, more preferably 30 to 80% by volume so that sufficient ion permeability can be obtained. The pore size of the pores of the porous layer is preferably 1.0 μm or less, and more preferably 0.5 μm or less. By setting the pore diameter of the pores to these sizes, the non-aqueous electrolyte secondary battery can obtain sufficient ion permeability.

[4. Non-aqueous electrolyte secondary battery parts, non-aqueous electrolyte secondary batteries]
In the member for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention, a positive electrode, the above-mentioned laminated separator for a non-aqueous electrolytic solution secondary battery, and a negative electrode are arranged in this order. Further, the non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention includes the above-mentioned laminated separator for the non-aqueous electrolytic solution secondary battery. The shape of the non-aqueous electrolyte secondary battery is not particularly limited, and may be a thin plate (paper) type, a disk type, a cylindrical type, a prismatic type such as a rectangular parallelepiped, or the like.

As a method for manufacturing the non-aqueous electrolyte secondary battery, a conventionally known manufacturing method can be adopted. For example, a member for a non-aqueous electrolytic solution secondary battery is formed by arranging a positive electrode, a laminated separator, and a negative electrode in this order. Here, the porous layer may exist between the polyolefin porous film and at least one of the positive electrode and the negative electrode. Next, the member for the non-aqueous electrolyte secondary battery is placed in a container that serves as a housing for the non-aqueous electrolyte secondary battery. After filling the container with a non-aqueous electrolytic solution, the container is sealed while reducing the pressure. This makes it possible to manufacture a non-aqueous electrolyte secondary battery.

<Positive electrode>
The positive electrode in one embodiment of the present invention is not particularly limited as long as it is generally used as a positive electrode of a non-aqueous electrolyte secondary battery. For example, as the positive electrode, a positive electrode sheet having a structure in which an active material layer containing a positive electrode active material and a binder is formed on a positive electrode current collector can be used. The active material layer may further contain a conductive agent.

Examples of the positive electrode active material include materials capable of doping and dedoping metal ions such as lithium ions and sodium ions. Specific examples of the material include a lithium composite oxide containing at least one transition metal such as V, Mn, Fe, Co and Ni.

Examples of the conductive agent include carbonaceous materials such as natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers and calcined organic polymer compounds. Only one type of the conductive agent may be used, or two or more types may be used in combination.

Examples of the binder include fluororesins such as polyvinylidene fluoride (PVDF), acrylic resins, and styrene-butadiene rubber. The binder also has a function as a thickener.

Examples of the positive electrode current collector include conductors such as Al, Ni and stainless steel. Of these, Al is more preferable because it is easy to process into a thin film and is inexpensive.

As a method for producing the positive electrode sheet, for example, a method of press-molding a positive electrode active material, a conductive agent and a binder on a positive electrode current collector; a positive electrode active material, a conductive agent and a binder using an appropriate organic solvent. Is formed into a paste, the paste is applied to the positive electrode current collector, dried, and then pressurized to be fixed to the positive electrode current collector; and the like.

<Negative electrode>
The negative electrode in one embodiment of the present invention is not particularly limited as long as it is generally used as a negative electrode of a non-aqueous electrolyte secondary battery. For example, as the negative electrode, a negative electrode sheet having a structure in which an active material layer containing a negative electrode active material and a binder is formed on a negative electrode current collector can be used. The active material layer may further contain a conductive agent.

Examples of the negative electrode active material include materials capable of doping and dedoping metal ions such as lithium ions and sodium ions. Examples of the material include carbonaceous materials. Examples of carbonaceous materials include natural graphite, artificial graphite, cokes, carbon black and pyrolytic carbons.

Examples of the negative electrode current collector include Cu, Ni and stainless steel. Cu is more preferable because it is difficult to form an alloy with lithium and it is easy to process it into a thin film.

As a method for manufacturing the negative electrode sheet, for example, a method of press-molding the negative electrode active material on the negative electrode current collector; after making the negative electrode active material into a paste using an appropriate organic solvent, the paste is used as the negative electrode current collector. A method of applying the paste to the negative electrode, drying it, and then pressurizing it to fix it to the negative electrode current collector; and the like. The paste preferably contains the above-mentioned conductive agent and binder.

<Non-aqueous electrolyte>
The non-aqueous electrolytic solution according to the embodiment of the present invention is not particularly limited as long as it is a non-aqueous electrolytic solution generally used for a non-aqueous electrolytic solution secondary battery. As the non-aqueous electrolytic solution, for example, a non-aqueous electrolytic solution obtained by dissolving a lithium salt in an organic solvent can be used. Examples of lithium salts include LiClO ₄ , LiPF ₆ , _{LiAsF 6} , LiSbF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , Li ₂ B ₁₀ Cl. _10. Lower aliphatic carboxylic acid lithium salt and LiAlCl _{4 and the} like can be mentioned. Only one type of the lithium salt may be used, or two or more types may be used in combination.

Examples of the organic solvent constituting the non-aqueous electrolyte solution include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and a fluorine group introduced into these organic solvents. Fluoroorganic solvent and the like can be mentioned. Only one kind of the organic solvent may be used, or two or more kinds may be used in combination.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

〔Measuring method〕
Various measurements in Examples and Comparative Examples were performed by the following methods.

<Difference in tensile elongation in the TD direction>
A test piece (A) having an MD direction of 5 mm and a TD direction of 55 mm was cut out from the laminated separators obtained in Examples and Comparative Examples. The length (mm) of this test piece (A) in the TD direction was _{defined as TL0} .

The test piece (A) was pulled in the TD direction at a tensile speed of 10 mm / min at 23 ° C. using a tensile strength tester, and the length in the TD direction when the tensile stress reached 80 MPa was measured. The length of the TD direction at this time is (mm) was _{T L1.}

Similarly, a release tape was attached to the porous layer side of the laminated separator obtained in Examples, and the release tape was peeled off to obtain a polyolefin porous film from which the porous layer was removed. This polyolefin porous film was cut out in an MD direction of 5 mm and a TD direction of 55 mm to obtain a test piece (B). The length (mm) of this test piece (B) in the TD direction was _{defined as TB0} .

The test piece (B) was pulled in the TD direction at a tensile speed of 10 mm / min at 23 ° C. using a tensile strength tester, and the length in the TD direction when the tensile stress reached 80 MPa was measured. The length of the TD direction at this time is (mm) was _{T B1.}

The resulting _{T L0, T L1, T B0} , was determined 80MPa tensile elongation differences using the following formulas _{T B1} a (1 ').
80MPa tensile elongation difference _{(%) = 100 × (T} L1 -T L0) / T L0 -100 × (T B1 -T B0) / T B0 (1 ')
Similarly, the test piece (A) was pulled in the TD direction, and the length in the TD direction when the tensile stress reached 100 MPa was measured. The length of the TD direction at this time is (mm) was _{T L2.} Further, the test piece (B) was pulled in the TD direction, and the length in the TD direction when the tensile stress reached 100 MPa was measured. The length of the TD direction at this time is (mm) was _{T B2.}

The resulting _{T L0, T L2, T B0} , was determined 100MPa tensile elongation differences using the following formulas _{T B2} (2 ').
100MPa tensile elongation difference _{(%) = 100 × (T} L2 -T L0) / T L0 -100 × (T B2 -T B0) / T B0 (2 ')
Further, in the same manner, the test piece (A) was pulled in the TD direction, and the length in the TD direction when the tensile stress reached 120 MPa was measured. The length of the TD direction at this time is (mm) was _{T L3.} Further, the test piece (B) was pulled in the TD direction, and the length in the TD direction when the tensile stress reached 120 MPa was measured. The length (mm) in the TD direction at this time was defined as _TB3 .

The resulting _{T L0, T L3, T B0} , was determined 120MPa tensile elongation differences using the following formulas _{T B3} a (3 ').
100MPa tensile elongation difference _{(%) = 100 × (T} L3 -T L0) / T L0 -100 × (T B3 -T B0) / T B0 (3 ')
<Curl amount>
FIG. 3 is a schematic view of a measuring device used for measuring the curl amount W of the laminated separator 10. The measuring device 6 includes a core 101, rollers 102a and 102b, a stopper 103, and a weight 104.

The rollers 102a and 102b are arranged parallel to each other. The rollers 102a and 102b have diameters equal to each other. C is a contact point between the roller 102a and the laminated separator 10. C'is a contact point between the roller 102b and the laminated separator 10. The distance between CC'is 1 m.

The method of measuring the curl amount will be described below. First, the laminated separators 10 obtained in Examples and Comparative Examples were slit so as to have a length of 66.6 mm in the TD direction, and cut out in the MD direction. Then, the laminated separator 10 was wound around the core 101 with the porous film side facing up.

Next, the laminated separator 10 was unwound from the core 101 so as to pass through the rollers 102a and 102b in this order. After that, the core 101 was fixed with a stopper 103 so as not to rotate. A weight 104 was attached to the tip of the laminated separator 10, that is, the end opposite to the core 101.

FIG. 4 is an enlarged view of the CC'between FIG. 3 viewed from a direction perpendicular to the plane of the laminated separator 10. The center between CC'is DD'as shown in FIG. DD'is the place where the amount of curl is the largest between CC'.

FIG. 5 is a cross-sectional view of the laminated separator 10 of FIG. 4 as viewed from the CC'direction. FIG. 5 illustrates a laminated separator 10 curled on the porous film side, which is the upper surface side. The laminated separator 10'shown by the broken line assumes a shape when the laminated separator 10 is not curled, and the length of the laminated separator 10 at this time in the TD direction is defined as W1. Further, the length of the portion having the largest curl amount projected from the direction perpendicular to the surface of the laminated separator 10 is defined as W2. W1 and W2 can be similarly defined in the laminated separator curled on the porous layer side.

The curl amount W was calculated from the following formula with respect to the laminated separators obtained in Examples and Comparative Examples.
Curl amount W = W1-W2
When a 150 g weight 104 is used so that the tension applied to the laminated separator 10 is 22 N / m, and when a 500 g weight 104 is used so that the tension is 74 N / m, the tension is 90 N / m. The amount of curl was measured in the case where the weight 104 of 610 g was used so as to be. These curl amounts are also referred to as "22 N / m curl amount", "74 N / m curl amount", and "90 N / m curl amount", respectively. The curl amount measurement environment was a temperature of 21 ° C., a relative humidity of 57%, and a dew point of 12.6 ° C.

[Comparative Example 1]
<Preparation of coating liquid>
2200 g of N-methyl-2-pyrrolidone (NMP) and 151 g of calcium chloride powder were added to a 3 liter separable flask having a stirring blade, a thermometer, a nitrogen inflow pipe and a powder addition port. Then, the contents of the separable flask were heated to 100 degrees Celsius to completely dissolve the calcium chloride powder. Then, after cooling the contents of the separable flask to room temperature, 68.23 g of para-phenylenediamine was added to completely dissolve the contents. Then, 124.97 g of terephthalic acid dichloride was added to the separable flask, and the mixture was stirred at 20 degrees Celsius for 1 hour. This gave a 6 weight percent solution of poly (paraphenylene terephthalamide) (PPTA). To 100 g of the obtained PPTA solution, 300 g of NMP was added to obtain a 1.5 weight percent solution of PPTA. To the obtained 1.5 wt% solution, 6 g of alumina C (manufactured by Aerosil Japan) and 6 g of advanced alumina AA-03 (manufactured by Sumitomo Chemical Co., Ltd.) were added, and the mixture was stirred for 240 minutes. Further, 0.73 g of calcium carbonate was added, and the mixture was stirred for 240 minutes to obtain a slurry coating liquid.

<Manufacturing of laminated separator>
A slurry coating liquid was continuously applied onto a polyethylene porous film having a film thickness of 10 μm. Subsequently, the formed coating film was guided to an atmosphere of 50 ° C. and a relative humidity of 70% to precipitate PPTA. Next, calcium chloride and the solvent were removed by washing the coating film on which PPTA was precipitated with water. Then, the coating film is continuously dried by using the first heating roller group at 95 ° C., the second heating roller group at 95 to 100 ° C., and the third heating roller group at 90 to 100 ° C. in order. As a result, a laminated separator wound body was obtained. Mainly, the first heating roller group corresponds to the heating period, the second heating roller group corresponds to the efficient drying period, and the third heating roller group corresponds to the lapse rate drying period.

[Example 1]
A laminated separator wound body was obtained in the same manner as in Comparative Example 1 except that the temperature of the third heating roller group was changed to 108 to 110 ° C.

[Example 2]
A laminated separator wound body was obtained in the same manner as in Comparative Example 1 except that the temperature of the third heating roller group was changed to 111 to 113 ° C.

[Example 3]
A laminated separator wound body was obtained in the same manner as in Comparative Example 1 except that the temperature of the third heating roller group was changed to 114 to 115 ° C.

[Example 4]
A laminated separator wound body was obtained in the same manner as in Comparative Example 1 except that the temperature of the third heating roller group was changed to 117 to 118 ° C.

〔Measurement result〕
The measurement results are shown in Table 1 below.

In Examples 1 to 4 in which the lapse rate drying temperature was adjusted so that the 80 MPa tensile elongation difference was less than 22%, the curl amount was suppressed as compared with Comparative Example 1 in which the 80 MPa tensile elongation difference was 22%. .. The larger the tension applied when measuring the curl amount, the smaller the curl amount. That is, it is difficult to observe the difference in the amount of curl between the examples. On the other hand, the smaller the tension applied when measuring the curl amount, the larger the curl amount tends to be. That is, it is easy to observe the difference in the amount of curl between the examples. In Examples 1 to 4, the curl amount is larger than that in Comparative Example 1 when a relatively small tension of 22 N / m is applied and when a relatively large tension of 74 N / m or 90 N / m is applied. You can see that it is suppressed. When manufacturing a lithium ion secondary battery, the laminated separator can be laminated with an electrode under various tension conditions depending on the battery shape, such as a cylindrical type, a square type, or a laminated type. As shown in Table 1, the laminated separators of Examples 1 to 4 have small curls even under various tension conditions. That is, it can be said that the laminated separator according to the embodiment of the present invention is excellent in processing suitability when manufacturing a lithium ion secondary battery.

One aspect of the present invention can be used for producing a laminated separator for a non-aqueous electrolytic solution secondary battery in which the amount of curl is suppressed or is not curled.

1 Porous film (polyolefin porous film)
2 Porous layer 10, 10'laminated separator (laminated separator for non-aqueous electrolyte secondary battery)
10a to d Separator original fabric

Claims (10)

A method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery, comprising a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film.
The laminated separator for a non-aqueous electrolytic solution secondary battery satisfies the following formula (1) by adjusting the temperature at which the original sheet of the separator provided with the polyolefin porous film and the porous layer is heated during the rate reduction drying period. A method for manufacturing a laminated separator for a non-aqueous electrolytic solution secondary battery, which comprises a step of controlling such as.
_{100 × (T L1 -T L0)} / T L0 -100 × (T B1 -T B0) / T B0 <22 ··· (1)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL1 : The length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB1 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa. The method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 1, wherein the laminated separator for a non-aqueous electrolytic solution secondary battery is further controlled to satisfy the following formula (2) during the rate reduction drying period. ..
_{100 × (T L2 -T L0)} / T L0 -100 × (T B2 -T B0) / T B0 <36 ··· (2)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL2 : Length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB2 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa. The laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 1 or 2, wherein the laminated separator for a non-aqueous electrolytic solution secondary battery is further controlled to satisfy the following formula (3) during the rate reduction drying period. Production method.
_{100 × (T L3 -T L0)} / T L0 -100 × (T B3 -T B0) / T B0 <60 ··· (3)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
T _L3: nonaqueous electrolyte pulling TD direction stacked separator for secondary batteries 23 ° C. tensile stress in the TD direction when the 120MPa length.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
T _B3: for a non-aqueous electrolyte secondary battery porous polyolefin was peeled from the laminate separator membrane by pulling in the TD direction at 23 ° C. tensile stress in the TD direction when the 120MPa length. The resin according to claims 1 to 3, wherein the resin is selected from the group consisting of a (meth) acrylate-based resin, a fluororesin, a polyamide-based resin, a polyimide-based resin, a polyester-based resin, and a water-soluble polymer. The method for producing a laminated separator for a non-aqueous electrolyte secondary battery according to any one item. The method for producing a laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 4, wherein the polyamide resin is an aramid resin. A laminated separator for a non-aqueous electrolytic solution secondary battery, comprising a polyolefin porous film and a porous layer containing a resin on at least one side of the polyolefin porous film, and satisfying the following formula (1).
_{100 × (T L1 -T L0)} / T L0 -100 × (T B1 -T B0) / T B0 <22 ··· (1)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL1 : The length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB1 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 80 MPa. The laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 6, further satisfying the following formula (2).
_{100 × (T L2 -T L0)} / T L0 -100 × (T B2 -T B0) / T B0 <36 ··· (2)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
_TL2 : Length in the TD direction when the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
_TB2 : The length in the TD direction when the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolytic solution secondary battery is pulled in the TD direction at 23 ° C. and the tensile stress becomes 100 MPa. The laminated separator for a non-aqueous electrolyte secondary battery according to claim 6 or 7, further satisfying the following formula (3).
_{100 × (T L3 -T L0)} / T L0 -100 × (T B3 -T B0) / T B0 <60 ··· (3)
_TL0 : Length of the laminated separator for a non-aqueous electrolyte secondary battery in the TD direction.
T _L3: nonaqueous electrolyte pulling TD direction stacked separator for secondary batteries 23 ° C. tensile stress in the TD direction when the 120MPa length.
_TB0 : Length in the TD direction of the polyolefin porous film peeled from the laminated separator for a non-aqueous electrolyte secondary battery.
T _B3: for a non-aqueous electrolyte secondary battery porous polyolefin was peeled from the laminate separator membrane by pulling in the TD direction at 23 ° C. tensile stress in the TD direction when the 120MPa length. The resin according to claims 6 to 8, wherein the resin is one or more selected from the group consisting of (meth) acrylate-based resins, fluororesins, polyamide-based resins, polyimide-based resins, polyester-based resins, and water-soluble polymers. The laminated separator for a non-aqueous electrolyte secondary battery according to any one of the items. The laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 9, wherein the polyamide resin is an aramid resin.

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