JP5938982B2 - Non-aqueous secondary battery separator - Google Patents

Description

The present invention relates to a separator for a non-aqueous secondary battery.

Non-aqueous secondary batteries such as lithium-ion secondary batteries, which use lithium-containing transition metal oxides typified by lithium cobaltate as the positive electrode and carbon materials that can be doped or dedoped with lithium as the negative electrode, have high energy density. It is important as a power source for portable electronic devices typified by mobile phones because of its characteristics, and demand for these portable electronic devices is increasing with the rapid spread of these portable electronic devices.

In addition, many automobiles that are environmentally conscious, such as hybrid cars, have been developed, but lithium ion secondary batteries having a high energy density have attracted a great deal of attention as one of the power sources to be mounted.

Many lithium ion secondary batteries are composed of a laminate of a positive electrode, a separator containing an electrolytic solution, and a negative electrode. The separator is responsible for preventing a short circuit between the positive electrode and the negative electrode as a main function, but as required characteristics, there are mobility, strength, durability, and the like of lithium ions.

At present, various types of polyolefin porous membranes have been proposed as films suitable for lithium ion secondary battery separators. Among polyolefin porous membranes, polyethylene porous membranes satisfy the above-mentioned required characteristics, and have a function of preventing thermal runaway by shutting off current from hole blockage due to high temperatures, a so-called shutdown function, as a safety function at high temperatures. It is widely used as a separator for lithium ion secondary batteries.

However, even if the pores of the porous membrane are blocked due to temperature rise and the current is interrupted once, if the battery temperature exceeds the melting point of polyethylene constituting the porous membrane and exceeds the heat resistance limit of polyethylene, the porous The membrane itself melts and the shutdown function is lost. As a result, a short circuit between the electrodes may cause thermal runaway of the battery, which may cause damage to a device incorporating the lithium ion secondary battery. For this reason, in order to ensure further safety, there is a demand for a separator that can maintain a shutdown function even at high temperatures.

Therefore, conventionally, a separator for a non-aqueous secondary battery using a heat-resistant porous layer such as polyamideimide as described in Patent Document 1 and Patent Document 2 has been proposed.

However, there is a concern that, by placing importance on heat resistance and laminating a heat-resistant porous layer, the air permeability is lower than that of a single polyolefin porous membrane, and as a result, battery characteristics are adversely affected.
Moreover, when laminating | stacking a heat resistant porous layer by application | coating, there exists a possibility that peeling and a nonuniformity may be produced, without fully ensuring adhesiveness with a polyethylene porous membrane.

Japanese Patent No. 4364940 JP 2005-285739 A

The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a separator for a non-aqueous secondary battery with improved air permeability and adhesion.

In order to achieve the above object, a nonaqueous secondary battery separator according to the present invention is a nonaqueous secondary battery separator having a heat-resistant porous layer on at least one surface of a polyolefin porous membrane, The heat-resistant porous layer has a number average molecular weight (Mn) of 30200 or more and a Z average molecular weight (Mz) of 1002000 or more.

The separator for non-aqueous secondary batteries according to the present invention can have both good air permeability and adhesion.

When the heat-resistant porous layer used in the separator for a non-aqueous secondary battery according to the present invention is made of polyamideimide, it can have both better air permeability and adhesion.

When the heat-resistant porous layer used in the separator for a non-aqueous secondary battery according to the present invention contains an inorganic filler, it can have both better air permeability and adhesion.

ADVANTAGE OF THE INVENTION According to this invention, the separator for non-aqueous secondary batteries which improved air permeability and adhesiveness can be provided.

Hereinafter, preferred embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.
The separator for nonaqueous secondary batteries of this embodiment has a heat resistant porous layer on at least one surface of the polyolefin porous membrane.

1. Polyolefin Porous Membrane The polyolefin porous membrane used as the base material of the composite membrane of the present embodiment is not particularly limited, and any known material may be used by any manufacturing method.

Examples of the polyolefin used in the polyolefin porous membrane include crystalline homopolymers or copolymers obtained by polymerizing ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and the like. In this case, these homopolymers or copolymers can be used alone, but two or more of them may be used in combination.

The polyolefin porous membrane used in the present embodiment usually has a porosity of 30 to 95%, an air permeability at a film thickness of 25 μm of 2000 seconds / 100 cc or less, preferably 800 seconds / 100 cc or less, and an average through-hole diameter. A porous film having mechanical properties of 0.005 to 1 μm, a tensile breaking strength of 80 MPa or more, preferably 100 MPa or more, and a puncture strength of 3000 mN or more, preferably 5500 mN or more is desirable.

The thickness of the polyolefin porous membrane is appropriately selected, but is usually about 0.1 to 50 μm, preferably about 1 to 25 μm. If the thickness is less than 0.1 μm, it is difficult to put it to practical use due to insufficient mechanical strength of the film, and if it exceeds 50 μm, the effective resistance becomes too large.

2. 2. Heat resistant porous layer 2-1. Heat Resin Resin The resin constituting the heat resistant porous layer of the present embodiment has an affinity for the electrolytic solution and, at the same time, has an affinity for the electrolytic solution and battery reaction when used for a separator for a non-aqueous secondary battery. In contrast, it is necessary to be stable, the permeation resistance is lower than that of the polyolefin porous membrane, and sufficient heat resistance is required.

Examples of materials that meet such requirements include polyimide, polyether ether ketone, polyamide, polyamide imide, polyether sulfide, polyether imide, polysulfone, and polyphenylene sulfide. When both are satisfied, polyamideimide is preferred.

In general, polyamideimide resin is synthesized by an ordinary method such as an acid chloride method using trimellitic acid chloride and diamine or a diisocyanate method using trimellitic anhydride and diisocyanate. preferable.

The acid component used for the synthesis of the polyamideimide resin is trimellitic anhydride (chloride), but a part of it can be replaced with another polybasic acid or its anhydride. For example, tetracarboxylic acids such as pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, biphenylethertetracarboxylic acid, ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, Aliphatic dicarboxylic acids such as oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), 1,4 -Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 4,4'-dicyclohexylmethanedicarboxylic acid, alicyclic dicarboxylic acids such as dimer acid, terephthalic acid, Le acid, diphenyl sulfone dicarboxylic acid, diphenylether dicarboxylic acid, and aromatic dicarboxylic acids such as naphthalene dicarboxylic acid. Among these, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid are preferable from the viewpoint of the resistance to electrolytic solution, and dimer acid, dicarboxypolybutadiene having a molecular weight of 1000 or more and dicarboxypoly (acrylonitrile) from the shutdown characteristics. Butadiene) and dicarboxypoly (styrene-butadiene) are preferred.

Examples of the diamine (diisocyanate) component used in the synthesis of the polyamideimide resin include aliphatic diamines such as diphenylmethane diisocyanate, ethylenediamine, propylenediamine, and hexamethylenediamine, and diisocyanates thereof, 1,4-cyclohexanediamine, and 1,3-cyclohexanediamine. Alicyclic diamines such as dicyclohexylmethane diamine, and diisocyanates thereof, m-phenylene diamine, p-phenylene diamine, 4,4′-diaminodiphenyl methane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, Aromatic diamines such as benzidine, xylylenediamine, naphthalenediamine, and diisocyanates of these may be mentioned. Diphenyl methane diisocyanate is preferable from the point.

The polyamide-imide resin is stirred in a polar solvent such as N, N′-dimethylformamide, N, N′-dimethylacetamide, N-methyl-2-pyrrolidone and γ-butyrolactone while heating to 60 to 230 ° C. Can be manufactured easily. In this case, amines such as triethylamine and diethylenetriamine, alkali metal salts such as sodium fluoride, potassium fluoride, cesium fluoride, sodium methoxide, and the like can be used as a catalyst as necessary.

Polyamideimide has a molecular weight that varies depending on reaction conditions such as temperature and solid content concentration during synthesis and storage conditions, and by adjusting these, it is possible to obtain a polyamideimide having a desired molecular weight range. In general, the higher the temperature and the longer the reaction time, the higher the average molecular weight. Conversely, when the synthesis is performed at a low temperature in a short time, the average molecular weight decreases. By using these, it is possible to adjust the ratio of the number average molecular weight and the Z average molecular weight.

The heat-resistant porous layer of the present embodiment needs to satisfy number average molecular weight (Mn) = 30200 or more and Z average molecular weight (Mz) 1002000 or more. Moreover, it is necessary to melt | dissolve in the organic solvent for the convenience of apply | coating. The type of organic solvent is not particularly limited as long as it does not deteriorate the polyolefin porous membrane of the base material, but is mainly N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DAMc), N-2. -Methylpyrrolidone (NMP) etc. are used in terms of solubility. Moreover, as a preferable molecular weight, the number average molecular weight (Mn) = 35400 or more, the Z average molecular weight (Mz) is 2895400 or more, more preferably the number average molecular weight (Mn) is 42,000 or more and less than 100,000, and the Z average molecular weight (Mz) is 5908700 or more and 30000000. Is less than. When Mn and Mz exceed these values, not only the synthesis is difficult, but also the formation of a porous film becomes practically difficult due to an increase in components insoluble in the solvent. When the number average molecular weight is lowered, there is a possibility that the air permeability as a separator is reduced due to clogging of unreacted residues and low molecular weight resin into the pores of the base material, and the Z average molecular weight (Mz ) Decreases, the strength of the heat-resistant porous layer decreases, and the heat-resistant porous layer peels easily during film formation and after film formation.

2-2. Porous method As a method of forming the heat-resistant porous layer on at least one surface of the polyolefin porous membrane, in addition to the phase separation method which is a production method generally used for the production method of a separation membrane, an extraction method, Although the use of a stretching method, a charged particle irradiation method or the like can be considered, it is not preferable to damage the polyolefin porous membrane during the formation process or to inhibit the properties of the polyolefin porous membrane by the formation.
Therefore, as a method that does not impair the mechanical properties and material permeation properties of the polyolefin porous membrane without exposure to temperatures exceeding the melting point of the polyolefin and without chemical or radiation deterioration, for example, the following resin A porous method by phase separation can be used.

That is, a resin dissolved in a good solvent is applied to at least one surface of a polyolefin porous membrane, phase-separated by contacting with a coagulating liquid containing a poor solvent, and then dried to cover at least the surface with a porous resin. This is a method for producing a multilayered porous membrane.
At that time, the resin is usually applied by a conventional casting or coating method, for example, a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater or the like.

The solvent of the coating solution is appropriately selected according to the properties of the heat resistant resin, as shown below. For example, when the heat-resistant resin is polyamideimide, examples of the good solvent include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DAMc), N-2-methylpyrrolidone (NMP), and the like. However, it is not particularly limited. When moisture is present, it is preferably removed by treatment with heated and dehydrated molecular sieve.

The concentration of the heat-resistant resin in the coating solution is not particularly limited as long as the viscosity is suitable for film formation, but is generally in the range of 1 to 20% by weight.

In the separator for a non-aqueous secondary battery of this embodiment, a phase separation agent may be mixed with the coating liquid in order to make the pore structure of the porous layer made of a heat resistant resin appropriate. The concentration of the phase separation agent is preferably 5 to 50% by weight.

Examples of the phase separation agent include polypropylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, 1,3-butanediol, 1,4-butanediol, glycerin, polyvinylpyrrolidone, and the like. Any material that is soluble and can be used as a poor solvent for the heat-resistant resin can be used.

Examples of the poor solvent include alcohols such as methanol and ethanol, benzene, methyl isobutyl ketone, dimethylformamide, water, and the like, and alcohols and water are preferable.

The coagulation liquid is composed of a mixture of a good solvent and a poor solvent. The proportion of the poor solvent is preferably 30 to 80% by weight. In addition, when a phase separation agent is used in the coating liquid, it is preferable in terms of the process to add the phase separation agent to the coagulation liquid so that the amount ratio of the good solvent and the phase separation agent in the coating liquid is equivalent. .

Next, the outline of the porosity forming method by phase-separating the coating layer will be described by taking polyamideimide as a heat resistant resin as an example.

As described above, the coating film after coating causes phase separation of the heat-resistant resin from the solution by a method using a coagulation liquid containing a poor solvent. For example, a mixed liquid of water and N-2-methylpyrrolidone is used as the coagulation liquid. This is a method of bringing this into contact with a coating film. At this time, the surface porosity can be increased by humidifying the coating film before bringing it into contact with the coagulation liquid. By soaking in the coagulation liquid after humidification, the solvent removal proceeds after the heat-resistant resin solution has sufficiently phase separated, and the surface layer structure is less likely to become dense. The humidification is preferably performed at a relative humidity of 60 to 100%. The phase-separated coating is subsequently washed with water and dried to complete the porous step.

  In the present embodiment, the heat resistant porous layer preferably contains an inorganic filler. The inorganic filler is not particularly limited, and specifically, oxide ceramics such as aluminum oxide, silicon dioxide, zirconia, magnesia, ceria, yttria, zinc oxide, iron oxide, silicon nitride, titanium nitride, boron nitride. Nitride ceramics such as silicon carbide, calcium carbonate, aluminum sulfate, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, asbestos, zeolite, Examples thereof include ceramics such as calcium silicate, magnesium silicate, diatomaceous earth, and silica sand, and ceramics such as glass fiber.

These may be used alone or in combination. Such an inorganic filler is preferably highly crystalline from the viewpoints of impurity elution and durability. In view of cost and versatility, aluminum oxide, silicon dioxide, and zirconia are more preferable.

In this embodiment, the average particle diameter of the inorganic filler is preferably in the range of 0.1 to 2 μm. When the average particle diameter of the inorganic filler exceeds 2 μm, the short circuit resistance at high temperature of the heat resistant porous layer is lowered, which is not preferable.
Further, there is a problem that it hinders the formation of the heat-resistant porous layer with an appropriate thickness. In addition, when the average particle size of the inorganic filler is less than 0.1 μm, not only does the coating film strength decrease and the problem of powder falling occurs, but using such a small one is substantially from the viewpoint of cost. Have difficulty.

In this embodiment, it is preferable that content of the inorganic filler in a heat resistant porous layer is 30 to 95 weight%. If the content of the inorganic filler is less than 30% by weight, the effect of improving the heat resistance by the inorganic filler may not be sufficiently obtained, which is not preferable. On the other hand, if the content of the inorganic filler exceeds 95% by weight, the heat-resistant porous layer may be excessively densified and ion permeability may be reduced, or the heat-resistant porous layer may become brittle and handling properties may be reduced. This is not preferable.

The inorganic filler in the heat-resistant porous layer is present in a state of being trapped by the heat-resistant resin when the heat-resistant porous layer is in the form of a porous film. In such a case, it may be present in the constituent fibers or fixed to the nonwoven fabric surface or the like with a binder such as a resin.

Examples are shown below, but the present invention is not limited thereto.
[Measuring method]
Each value in this example was determined according to the following method.

(1) Air permeability evaluation A test piece of 100 × 100 mm was collected, and the air permeability was measured according to JISL8117. The evaluation is based on the air permeability (second / 100 cc) of the polyolefin porous film laminated with the heat resistant porous layer, and the polyolefin porous film (film thickness 16 μm, air permeability) not laminated with the heat resistant porous layer. It was expressed as a value obtained by subtracting the air permeability of 200 seconds / 100 cc).

(2) Peel test A cross-cut tape peel test was performed on the heat-resistant porous layer in accordance with JIS D0202-1988. The cellophane tape was adhered to the heat-resistant porous layer with the belly of the finger, and then the tape was peeled from the separator. Judgment is the number of squares in which the heat-resistant porous layer did not peel out of 100 squares, that is, the non-peeling ratio, and the case where the heat-resistant porous layer peels off in all 1 square is 0, heat-resistant porous The case where the layer did not peel in all 100 squares was expressed as 100.

(3) Measurement of molecular weight The number average molecular weight (Mn) and the Z average molecular weight (Mz) were measured using GPC (gel permeation chromatograph) method. Mn and Mz are described, for example, in “Revised Polymer Synthesis Chemistry” (Publisher: Kagaku Dojin, 1981), pages 9 to 12, and are usually gel permeation chromatography ( Hereinafter, it is referred to as “GPC”). Specifically, acetone is added to the polyamide-imide resin, and the filtrate obtained by filtering the resulting precipitate is dried. 0.01 g of the obtained dried filtrate is weighed and dissolved in 10 g of DMF. The solution thus obtained was measured by gel permeation chromatography (GPC method) and detected by a differential refractometer. As main GPC measurement conditions, “HLC-82020” manufactured by Tosoh Corporation was used. In addition, “TSKgel 2500” and “TSKgel 3000” manufactured by Tosoh Corp. are used in combination as the reference side column, and two “TSKgelGMHHR-M” manufactured by Tosoh Corp. are used in combination for the sample side column, 1 ml / min, sample injection volume was 100 μl, and column temperature was 50 ° C.

Moreover, polystyrene was used as a calibration curve preparation sample, and Mn and Mz were measured using numerical values calculated using this apparatus. Mn and Mz are defined by the following formulas (1) and (2), respectively, assuming that ni polymer molecules having a molecular weight of Mi exist in a unit volume.
Mn = ΣniMi / Σni (1)
Mz = Σni (Mi) ³ / Σni (Mi) ² (2)
That is, Mn is sensitively influenced by the low molecular weight contained in the polymer compound. On the other hand, Mz can be estimated from the equation that the contribution of a high molecular weight substance is greatly received. Therefore, Mz is a value that more specifically indicates the presence of a high molecular weight body.

(4) Evaluation of film state The following method was used to evaluate the film state.
The polyamideimide used in each example and comparative example was diluted with N-methyl-2-pyrrolidone so as to have a viscosity of 1000 mPa · s, and 200 mm square, 16 μm thick, Gurley air permeability using a bar coater. It was applied to a polyolefin porous membrane having a value of 200 seconds / 100 cc to a thickness of 2 μm, and after gently dipping in water / N-methyl-2-pyrrolidone = 50/50 at 60 ° C. for about 30 seconds, In the process of obtaining a porous polyamideimide film, which is a heat-resistant porous layer laminated on the polyolefin porous film by gently moving to a water bath and taking it out after 5 minutes, visually check the peeling state of the film, The case where peeling was observed in more than half of the area was rated as x, and the case where peeling was hardly confirmed was marked as ◯.

[Example 1]
Add trimellitic anhydride, 4,4'-diphenylmethane diisocyanate in the same molar amount, and potassium fluoride to 0.01 mol% with respect to trimellitic anhydride in a 2 L separable flask under nitrogen atmosphere. After adding N-methyl-2-pyrrolidone to a solid content of 32% by weight, the mixture was stirred at 180 ° C. for 7 hours to synthesize polyamideimide having the molecular weight described in Example 1 of Table 1.
This polyamideimide is diluted with N-methyl-2-pyrrolidone so that the viscosity becomes 1000 mPa · s, and coated on a 16 μm porous polyolefin film using a bar coater, and water / N— at 60 ° C. Methyl-2-pyrrolidone = heat-resistant porous layer laminated on the polyolefin porous layer by gently immersing in 50/50 for about 30 seconds, then moving gently to a 20 ° C water bath and taking out after 5 minutes A porous polyamideimide film was obtained.

[Example 2]
The material was the same as in Example 1, and the polyamideimide having the molecular weight described in Example 2 in Table 1 was synthesized by stirring at 190 ° C. for 9.5 hours. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Example 3]
The material was the same as in Example 1, and the polyamideimide having the molecular weight described in Example 3 in Table 1 was synthesized by stirring at 200 ° C. for 10.5 hours. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Example 4]
In the same manner as in Example 1, after stirring at 120 ° C. for 4 hours, the material was stirred at 180 ° C. for 24 hours to synthesize polyamideimide having the molecular weight described in Example 4 of Table 1. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Example 5]
In the same manner as in Example 1, the material was stirred at 120 ° C. for 4 hours, then at 180 ° C. for 31 hours, and then stirred at room temperature for about 2 weeks to obtain the polyamideimide having the molecular weight described in Example 5 of Table 1. Synthesized. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Comparative Example 1]
The material was a solid content of 15% by weight and the reaction time was stirred at 160 ° C. for 2 hours in the same manner as in Example 1 to synthesize the polyamideimide having the molecular weight described in Comparative Example 1 of Table 1. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Comparative Example 2]
In the same manner as in Example 1, the polyamideimide having the molecular weight described in Comparative Example 2 in Table 1 was synthesized by stirring the solid content at 15% by weight and the reaction time at 180 ° C. for 2 hours. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Comparative Example 3]
In the same manner as in Example 1, the solid content was 30 w%, the reaction time was stirred at 100 ° C. for 1 hour, and then stirred at 185 ° C. for 6 hours to synthesize the polyamideimide having the molecular weight described in Comparative Example 3 in Table 1. did.
A porous polyamideimide film laminated on the polyolefin porous film was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Comparative Example 4]
In the same manner as in Example 1, the polyamideimide having the molecular weight described in Comparative Example 4 in Table 1 was synthesized by stirring for 7 hours at 170 ° C. with a solid content of 25% by weight. A porous polyamideimide film laminated on the polyolefin porous material was obtained in the same manner as in Example 1 except that this polyamideimide was used.

[Example 6]
After adding commercially available silicon dioxide (particle size: 0.1 μm) to the polyamideimide prepared in Example 1 so as to have a weight of 20 w% with respect to the polyamideimide, the viscosity is set to 1000 mPa · s. After diluting with N-methyl-2-pyrrolidone, it was coated on a 16 μm porous polyolefin film with a thickness of 2 μm using a bar coater, and in water / N-methyl-2-pyrrolidone = 50/50 at 60 ° C. After soaking gently for about 30 seconds, it was gently moved to a 20 ° C. water bath and taken out after 5 minutes to obtain a porous polyamideimide-silicon dioxide mixed film laminated on the polyolefin porous material.

[Example 7]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Example 2 was used instead of the polyamideimide used in Example 6 Got.

[Example 8]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Example 3 was used instead of the polyamideimide used in Example 6 Got.

[Example 9]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Example 4 was used instead of the polyamideimide used in Example 6 Got.

[Example 10]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Example 5 was used instead of the polyamideimide used in Example 6 Got.

[Comparative Example 5]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Comparative Example 1 was used instead of the polyamideimide used in Example 6 Got.

[Comparative Example 6]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Comparative Example 2 was used instead of the polyamideimide used in Example 6 Got.

[Comparative Example 7]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Comparative Example 3 was used instead of the polyamideimide used in Example 6 Got.

[Comparative Example 8]
A porous polyamideimide-silicon dioxide mixed film laminated on a polyolefin porous film in the same manner as in Example 6 except that the polyamideimide produced in Comparative Example 4 was used instead of the polyamideimide used in Example 6 Got.

[Example 11]
After adding commercially available aluminum oxide (particle size: 0.1 μm) to the polyamideimide prepared in Example 1 so as to have a weight of 20 w% with respect to the polyamideimide, the viscosity is 1000 mPa · s. After diluting with N-methyl-2-pyrrolidone, it was coated on a 16 μm porous polyolefin film with a thickness of 2 μm using a bar coater, and in water / N-methyl-2-pyrrolidone = 50/50 at 60 ° C. After soaking gently for about 30 seconds, it was gently moved to a 20 ° C. water bath and taken out after 5 minutes to obtain a porous polyamideimide-aluminum oxide mixed film laminated on the polyolefin porous material.

[Example 12]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Example 2 was used instead of the polyamideimide used in Example 11 Got.

[Example 13]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Example 3 was used instead of the polyamideimide used in Example 11 Got.

[Example 14]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Example 4 was used instead of the polyamideimide used in Example 11 Got.

[Example 15]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Example 5 was used instead of the polyamideimide used in Example 11 Got.

[Comparative Example 9]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Comparative Example 1 was used instead of the polyamideimide used in Example 11 Got.

[Comparative Example 10]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide prepared in Comparative Example 2 was used instead of the polyamideimide used in Example 11 Got.

[Comparative Example 11]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Comparative Example 3 was used instead of the polyamideimide used in Example 11 Got.

[Comparative Example 12]
A porous polyamideimide-aluminum oxide mixed film laminated on a polyolefin porous film in the same manner as in Example 11 except that the polyamideimide produced in Comparative Example 4 was used instead of the polyamideimide used in Example 11 Got.

As shown in Table 1, Table 2, and Table 3, in Examples 1 to 15, in Comparative Examples 1 to 12, the improvement in air permeability and the improvement in adhesion due to clogging reduction were confirmed. These properties were found to be low.

INDUSTRIAL APPLICABILITY The present invention can be effectively used as a technique for improving the characteristics of a nonaqueous secondary battery separator.

Claims (3)

On at least one surface of the polyolefin porous membrane, a separator for a nonaqueous secondary battery having a heat-resistant porous layer, the heat resistant porous layer made of port Riamidoimi de, number average molecular weight of the polyamide-imide A separator for a non-aqueous secondary battery, wherein (Mn) is 30200 or more and 42000 or less and a Z average molecular weight (Mz) is 1002000 or more and 5908700 or less . The separator for a non-aqueous secondary battery according to claim 1, wherein the heat-resistant porous layer contains an inorganic filler. Nonaqueous secondary battery separator according to claim 1 or 2, wherein the average through-pore size of the porous polyolefin membrane is 0.005 to 1 [mu] m.