JP6924032B2 - Polymer composition, laminated film and separator - Google Patents

Description

The present invention relates to a polymer composition, a laminated film and a separator containing a nitrogen-containing aromatic polymer and a solvent.

Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are currently widely used as batteries used in devices such as personal computers, mobile phones, and personal digital assistants.

These non-aqueous electrolyte secondary batteries represented by lithium secondary batteries have a high energy density. Therefore, when an internal short circuit or an external short circuit occurs due to damage to the battery or damage to the device using the battery, a large current may flow and the non-aqueous electrolyte secondary battery may generate heat. Therefore, the non-aqueous electrolyte secondary battery is required to ensure high safety by preventing heat generation of a certain amount or more.

As a method for ensuring the safety of the non-aqueous electrolyte secondary battery, a method of imparting a shutdown function to the non-aqueous electrolyte secondary battery is generally used. The shutdown function is a function of blocking the passage of ions between the positive electrode and the negative electrode by a separator when abnormal heat generation occurs in the non-aqueous electrolyte secondary battery to prevent further heat generation. That is, as a method for ensuring the safety of the non-aqueous electrolyte secondary battery, for example, due to an internal short circuit between the positive electrode and the negative electrode, the separator arranged between the positive electrode and the negative electrode in the battery is abnormal. When a large current flows, a method is generally used in which the current is cut off to prevent (shut down) the excessive current from flowing in the battery, thereby imparting a function of further suppressing heat generation. Here, when the operating temperature of the non-aqueous electrolyte secondary battery exceeds the normal operating temperature, the separator is melted by the generated heat, and as a result, the pores formed in the separator are closed. The shutdown is performed. It is preferable that the separator is maintained in a shut down state without being destroyed by heat even if the inside of the battery becomes a certain high temperature after the shutdown.

As the separator, a porous film containing polyolefin as a main component, which melts at, for example, about 80 to 180 ° C. when abnormal heat generation occurs, is generally used. However, since the separator containing the porous film as a main component has insufficient shape stability at high temperatures, the separator may shrink or the separator may break while the shutdown function is being executed. do. As a result, even if the shutdown function is executed, the positive electrode and the negative electrode may come into direct contact with each other, causing an internal short circuit. That is, the separator containing the porous film as a main component may not be able to sufficiently suppress abnormal heat generation due to an internal short circuit. Therefore, there is a demand for a separator that can ensure higher safety.

As a porous film having excellent heat resistance, for example, Patent Document 1 describes a porous film obtained by coating a microporous polyolefin film with a polymer composition containing an aromatic polymer such as an aromatic aramid. Has been proposed.

Japanese Patent Publication "Japanese Patent Laid-Open No. 2009-205959"

However, the porous film obtained by applying the polymer composition described in Patent Document 1 does not have sufficient performance in terms of producing a separator having a good appearance.

The present invention has been made in consideration of the above problems, and a main object thereof is a separator for a non-aqueous electrolyte secondary battery having excellent shape stability at high temperatures, and the battery is damaged or the battery is used. It is a separator for non-aqueous electrolyte secondary batteries that can ensure high safety by preventing heat generation above a certain level even when an internal short circuit or an external short circuit occurs due to damage to the equipment. It is an object of the present invention to provide a polymer composition suitable for producing a good separator.

The present inventor has diligently studied a polymer composition containing a nitrogen-containing aromatic polymer and a solvent. As a result, in order to manufacture a separator for a non-aqueous electrolyte secondary battery having a good appearance, which can ensure high safety by adjusting the filtration blockage coefficient to a specific numerical range. They have found that it is a suitable polymer composition, and have completed the present invention.

In order to solve the above problems, the polymer composition according to the present invention is a polymer composition containing a nitrogen-containing aromatic polymer and a solvent, and has a filtration blockage coefficient of 34 m ² / m ³ or less. It is characterized by that.

According to the present invention, it is possible to provide a polymer composition suitable for producing a separator for a non-aqueous electrolytic solution secondary battery. The separator is (i) excellent in shape stability at high temperature, and (ii) prevents heat generation above a certain level even when an internal short circuit or an external short circuit occurs due to damage to the battery or equipment using the battery. By doing so, high safety can be ensured and (iii) the appearance is good.

Hereinafter, an embodiment of the present invention will be described in detail. In this application, "A to B" means A or more and B or less.

The polymer composition according to the present invention is a polymer composition containing a nitrogen-containing aromatic polymer and a solvent, and has a filtration blockage coefficient of 34 m ² / m ³ or less.

First, the nitrogen-containing aromatic polymer will be described. The nitrogen-containing aromatic polymer (hereinafter, simply referred to as an aromatic polymer) is an aromatic polymer having a nitrogen atom in the main chain (a part of the main chain is composed of a nitrogen atom), and more. It is preferably an aromatic polymer having a structure represented by −C (= O) NH− in the main chain, more preferably an aromatic polyamide, and particularly preferably a total aromatic polyamide. The aromatic polyamide may be a para-oriented aromatic polyamide or a meta-oriented aromatic polyamide. However, the aromatic polyamide is more preferably a para-oriented aromatic polyamide because of its high mechanical strength and its tendency to become porous.

Specific examples of the aromatic polyamide include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (parabenzamide), poly (metabenzamide), and poly (4,4'-benz). Anilide terephthalamide), poly (paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly (metaphenylene-4,4'-biphenylenedicarboxylic acid amide), poly (paraphenylene-2,6-naphthalenedicarboxylic 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, and metaphenylene terephthalamide. Examples thereof include an amide / 2,6-dichloroparaphenylene terephthalamide copolymer. Of these, the aromatic polyamide is more preferably poly (paraphenylene terephthalamide). The aromatic polyamide may be a mixture of the above-exemplified polymers.

The aromatic polymer can be produced, for example, by reacting an aromatic diamine with a compound having a hydrolyzable reactive group that reacts with an amino group in a solvent. More specifically, an aromatic polymer having a structure represented by -C (= O) NH- as a main chain reacts with, for example, an aromatic diamine and an amino group to form -C (= O). It can be produced by reacting a compound having a hydrolyzable reactive group forming a structure represented by NH- in a solvent.

The aromatic polymer contained in the polymer composition is used as a member (heat-resistant porous layer) constituting a separator in the field of manufacturing a non-aqueous electrolytic solution secondary battery. The aromatic polymer is a heat-resistant resin, and a heat-resistant porous layer can be formed on the surface of the base material by a simple method such as coating (coating) on a base material used as a separator and drying. The thickness of the heat-resistant porous layer is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less, and particularly preferably 1 μm or more and 4 μm or less. Further, the pore diameter of the pores of the heat-resistant porous layer is preferably more than 0 and preferably 3 μm or less, and more preferably 1 μm or less. By forming a heat-resistant porous layer on the base material, the heat resistance of the separator can be improved to, for example, about 400 ° C. If necessary, the heat-resistant porous layer may contain a filler made of organic powder or inorganic powder having an average particle size of 0.01 μm or more and 1 μm or less.

A thermoplastic resin is suitable as the base material used as a separator for a non-aqueous electrolyte secondary battery. Specifically, examples of the thermoplastic resin include polyolefins such as polyethylene, polypropylene, polybutene, and ethylene-propylene copolymer, and thermoplastic polyurethane. Of these, the thermoplastic resin is more preferably polyethylene because it can prevent (shut down) an excessive current from flowing through the non-aqueous electrolyte secondary battery at a lower temperature. Examples of the polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene having a molecular weight of 1 million or more.

Examples of the aromatic diamine used as a raw material for the aromatic polymer include oxyaniline, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 3,3'-benzophenonediamine, and 3 , 3'-Methylenedianiline, 3,3'-diaminodiphenyl sulfone, 1,2-naphthylenediamine, 1,3-naphthylenediamine, 1,4-naphthylenediamine, 1,5-naphthylenediamine, 1, , 6-Naftylene diamine, 1,7-naphthylene diamine, 1,8-naphthylene diamine, 2,3-naphthylene diamine, 2,6-naphthylene diamine, 3,3'-biphenylenediamine and the like. Be done. Of these, the aromatic diamine is more preferably 1,4-phenylenediamine. Only one kind of these aromatic diamines may be used, or two or more kinds may be used in combination.

A compound having a hydrolyzable reactive group that forms a structure represented by -C (= O) NH- by reacting with an amino group, which is a raw material of an aromatic polymer (hereinafter, a reactive group-containing compound). (Referred to as) includes a compound having an acyl group. Specifically, as the reactive group-containing compound, for example, a urea bond (-NH-C (= O) NH-) is formed by reacting with an acid dianhydride, an acid dihalide, or an amino group. Examples thereof include diisocyanates to be formed. The compound having an acyl group is more preferably an aromatic compound.

Specifically, as the acid dianhydride, aromatic dianhydride is more preferable. Examples of the aromatic acid dianhydride include pyromellitic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, and 3,3', 4,4'-benzophenonetetra. Examples thereof include carboxylic acid dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, and 3,3', 4,4'-biphenyltetracarboxylic dianhydride. ..

As the acid dihalide, aromatic acid dichloride is more preferable. Examples of the aromatic acid dichloride include phthalic acid dichloride, terephthalic acid dichloride, pyromellitic acid dichloride, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid dichloride, 3,3', 4,4. '-Benzophenonetetracarboxylic acid dichloride, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropanedichloride, 3,3', 4,4'-biphenyltetracarboxylic acid dichloride, 1,2-phenylenedicarboxylic acid Acid dichloride, 1,3-phenylenedicarboxylic acid dichloride, 1,4-phenylenedicarboxylic acid dichloride, 1,2-naphthylenedicarboxylic acid dichloride, 1,3-naphthylenedicarboxylic acid dichloride, 1,4-naphthylenedicarboxylic acid dichloride , 1,5-naphthylenedicarboxylic acid dichloride, 1,6-naphthylenedicarboxylic acid dichloride, 1,7-naphthylenedicarboxylic acid dichloride, 1,8-naphthylenedicarboxylic acid dichloride, 2,3-naphthylenediccarboxylic acid dichloride , 2,6-naphthylenedicarboxylic acid dichloride, 3,3'-biphenylenedicarboxylic acid dichloride, 3,3'-benzophenone dicarboxylic acid dichloride, 3,3'-diphenylsulphon dicarboxylic acid dichloride and the like.

As the diisocyanate, aromatic diisocyanate is more preferable. Examples of the aromatic diisocyanate include 1,2-phenylenediocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, 1,2-naphthylene diisocyanate, 1,3-naphthylene diisocyanate, and 1,4-. Naftylene diisocyanate, 1,5-naphthylene diisocyanate, 1,6-naphthylene diisocyanate, 1,7-naphthylene diisocyanate, 1,8-naphthylene diisocyanate, 2,3-naphthylene diisocyanate, 2,6-naphthylene diisocyanate Examples thereof include isocyanate, 3,3'-biphenylenediisocyanate, 3,3'-benzophenone diisocyanate, 3,3'-diphenylsulphon diisocyanate and the like.

As the reactive group-containing compound, among the above-exemplified compounds, aromatic acid dihalides are more preferable, and terephthalic acid dichloride is further preferable. Only one kind of these reactive group-containing compounds may be used, or two or more kinds may be used in combination.

In the aromatic polymer, for example, the aromatic diamine and the reactive group-containing compound are mixed at −20 ° C. to 50 ° C., more preferably in a solvent in which a chloride of an alkali metal or an alkaline earth metal is dissolved. It can be obtained by reacting (polymerizing) at a reaction temperature of −10 ° C. to 40 ° C. The molar ratio of the aromatic diamine to the reactive group-containing compound (aromatic diamine / reactive group-containing compound) is usually 1.00 to 1.050, preferably 1.00 to 1.040. Yes, more preferably 1.00 to 1.030. The concentration of the chloride dissolved in the solvent is preferably 2% by weight to 10% by weight, more preferably 3% by weight to 8% by weight.

Examples of the chloride include chlorides of alkali metals such as sodium chloride and potassium chloride, and chlorides of alkaline earth metals such as magnesium chloride and calcium chloride. Of these, calcium chloride is more preferable. Only one kind of these chlorides may be used, or two or more kinds may be used in combination.

Then, by adjusting the molar ratio of the aromatic diamine to the reactive group-containing compound (aromatic diamine / reactive group-containing compound) within the above range, and by adjusting the reaction temperature within the above range, Further, by adjusting the concentration of the chloride dissolved in the solvent within the above range, an aromatic polymer having a degree of polymerization sufficient to form a heat-resistant porous layer can be obtained.

The solvent is more preferably an aprotic polar solvent. Specifically, examples of the aprotic polar solvent include organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, and N, N-dimethylformamide. Of these, N-methyl-2-pyrrolidone is more preferable as the aprotic polar solvent. Only one type of these solvents may be used, or two or more types may be used in combination.

The water content of the solvent is preferably 200 ppm to 2500 ppm, more preferably 200 ppm to 1500 ppm, and even more preferably 250 ppm to 1000 ppm. When the water content of the solvent is less than 200 ppm, the filtration blockage coefficient tends to be high. On the other hand, when the water content of the solvent exceeds 2500 ppm, the aromatic polymer in the polymer composition is precipitated when the polymer composition is stored, or the aromatic polymer has a sufficient degree of polymerization to form a heat-resistant porous layer. Inconveniences such as the inability to obtain a group polymer occur. The method for measuring the water content of the solvent will be described in detail in Examples.

The amount of the solvent used relative to the total amount of the aromatic diamine and the reactive group-containing compound, that is, the total concentration of the aromatic diamine and the reactive group-containing compound at the start of the reaction in the solvent (concentration of the raw material) is 0. It is preferably 5% by weight to 20% by weight, more preferably 1% by weight to 15% by weight, and even more preferably 3% by weight to 12% by weight.

The aromatic polymer obtained by carrying out the above reaction is, for example, an aromatic polymer having a structure represented by -C (= O) NH- in the main chain and having an intrinsic viscosity of 1.5 dL / g or more. It is 3.0 dL / g, more preferably 1.7 dL / g to 2.5 dL / g, and even more preferably 1.8 dL / g to 2.3 dL / g. The method for measuring the intrinsic viscosity will be described in detail in Examples.

The intrinsic viscosity can be controlled by adjusting the molar ratio of the aromatic diamine to the reactive group-containing compound and the water content of the solvent. When the intrinsic viscosity is less than 1.5 dL / g, the molecular weight of the aromatic polymer is small, so that the elastic modulus of the heat-resistant porous layer formed is lowered, and shrinkage is suppressed when the base material is melted by heat. The effect is low. On the other hand, when the intrinsic viscosity exceeds 3.0 dL / g, the molecular weight of the aromatic polymer becomes too large, so that the coatability when the polymer composition is coated on the substrate is lowered, and the coatability is lowered. The filtration blockage coefficient tends to be high.

Then, by carrying out the above reaction ^{, a polymer composition having a filtration occlusion coefficient of 34 m 2} / m ³ or less, that is, an aromatic polymer and a solvent are contained, and the filtration occlusion coefficient is 34 m ² / m ³ or less. A polymer composition is obtained. That is, the solvent is preferably a solvent contained in the polymer composition after the aromatic polymer is obtained by the reaction.

The filtration blockage coefficient is a numerical value that is an index of the amount of insoluble component (gel component amount) of the aromatic polymer that is not dissolved in the solvent and is contained in the polymer composition. The filtration blockage coefficient of the polymer composition is more than ^{0 m 2} / m ^{3 and preferably 34 m 2} / m ³ or less, ^{more preferably 30 m 2} / m ³ or less, and 25 m ² / m ³ or less. It is more preferable to have. When the filtration blockage coefficient exceeds 34 m ² / m ³ , the amount of gel component contained in the polymer composition is large, so that, for example, the value of the galley (air permeability) of the separator produced using the polymer composition is high. As a result, the battery characteristics of the non-aqueous electrolyte secondary battery may be deteriorated. The method for measuring the filtration blockage coefficient of the polymer composition will be described in detail in Examples.

The high or low filtration blockage coefficient can be controlled not only by the water content of the solvent used in the reaction and the intrinsic viscosity of the aromatic polymer, but also by the stirring efficiency of the reaction when producing the aromatic polymer. When the stirring efficiency is increased, the filtration blockage coefficient tends to decrease. The stirring efficiency can be adjusted by the number of rotations of the stirring blade, the amount of the reaction solution with respect to the reaction vessel, and the like, and by appropriately adjusting these conditions, a polymer composition having ^{a filtration blockage coefficient of 34 m 2} / m ^{3 or less.} Can be obtained.

In the field of manufacturing a non-aqueous electrolytic solution secondary battery, a heat-resistant porous layer is formed on the surface of the base material by, for example, coating (coating) the polymer composition on the base material and then removing the solvent. The laminated film can be easily manufactured. The method of coating (coating) the polymer composition on the substrate and the method of removing the solvent from the coated (coated) solution are not particularly limited, and known methods can be appropriately adopted. ..

The present invention also includes a laminated film produced by the above-mentioned production method. Then, by appropriately adopting a known method, a separator containing the laminated film can be easily manufactured. Further, by appropriately adopting a known method, a non-aqueous electrolytic solution secondary battery containing the separator can be easily manufactured.

Instead of using the solution of the aromatic polymer obtained by carrying out the reaction as it is as the polymer composition, (i) a solution obtained by removing a part of the solvent from the solution, (ii) the solution. A solution obtained by adding a solvent to the solution, (iii) a solution obtained by washing the solution with water, methyl alcohol, etc. to remove chloride, and (iv) evaporating a part or all of the solvent and simultaneously aroma. A solution obtained by precipitating a group polymer, removing chloride from the aromatic polymer by a method such as washing with water, and then dissolving the group polymer in a solvent can also be used as a polymer composition. Therefore, the solvent used to obtain the aromatic polymer and the solvent contained in the polymer composition may be the same as each other, or may be different from each other, but may be the same as each other. More preferred.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

The various measurement methods in this application are as follows. The physical characteristics of the aromatic polymer and the polymer composition were evaluated by the following methods.

(1) Moisture content The water content of the solvent was measured according to a conventional method using a Karl Fischer moisture content meter.

(2) An aromatic polymer solution was prepared by dissolving 0.5 g of an aromatic polymer in 100 ml of 100 ml of 96% to 98% sulfuric acid. Further, 96% to 98% sulfuric acid was prepared as a blank. For each of the aromatic polymer solution and the blank, the flow time at 30 ° C. was measured according to a conventional method using a capillary viscometer. From the obtained flow time ratio, the intrinsic viscosity was calculated by the following formula.

Intrinsic viscosity [Unit: dl / g] = ln (T / T ₀ ) / C
In the formula, T is the flow time (seconds) of the aromatic polymer solution, T ₀ is the flow time (seconds) of the blank, and C is the concentration of the aromatic polymer in the aromatic polymer solution (g / dl). ) Is shown.

(3) Filtration blockage coefficient The method for measuring the filter blockage coefficient is described on page 813 of the Revised Sixth Edition Chemical Engineering Handbook (published on February 25, 1999, published by Maruzen Co., Ltd., editor: Society of Chemical Engineers of Japan). It was calculated using the formula described in "Table 15.6 Blocked Filtration Formula" of "15.3 Filtration / Squeezing" of "15 Solid Liquid / Solid Air Separation".

Specifically, the polymer composition was filtered using a 2000 mesh (pore diameter: 14 μm) SUS filter (diameter: 25 mm) while pressurizing at 1 kgf (approximately 9.8 N). Then, the filtration blockage coefficient was calculated by the following formula.

_{t / V = K S × t} + 1 / Q 0
Filtration blockage coefficient H [Unit: m ² / m ³ ] = A × K _S
Wherein, A is the filtration area ^{(m 2),} t is the filtration time (in seconds), V is the volume filtered ^{(m 3),} _{K S} represents the slope of the graph of t / V and t , 1 / Q ₀ indicate the intercept in the graph of t / V and t.

(4) Evaluation of heat-resistant porous layer (coated surface) formed on the base material A heat-resistant porous layer was formed by applying the polymer composition to polyethylene as the base material. Then, it was visually observed and evaluated whether or not the formed heat-resistant porous layer had streaks. In the evaluation, when observing the direction orthogonal to the coating direction in the porous layer, the one having a region where two or more streaks exist is regarded as defective, and the one where there is no region where two or more streaks exist (the streaks are). One or less) was considered good.

(5) Evaluation of Appearance of Separator By applying the polymer composition to polyethylene as a base material, a laminated film as a separator having a heat-resistant porous layer was produced. Then, the appearance of the produced laminated film was visually observed and evaluated. Specifically, the heat-resistant porous layer (coated surface) formed on the base material with a good evaluation was regarded as good, and a defective one was regarded as defective.

(6) Heat-resistant basis weight The base material and the laminated film were cut into 8 cm square sample pieces, and the basis weight was calculated by the following formula.

Metsuke [Unit: g / m ² ] = Weight of sample piece (g) / (0.08 (m) x 0.08 (m))
Next, the heat resistant basis weight was calculated by the following formula.

Heat-resistant basis weight [Unit: g / m ² ] = Metsuke of laminated film-Metsuke of base material
(7) Garley (air permeability)
The garley (permeability) [unit: sec / 100 ml] of the base material and the laminated film (coated product) was measured using a garley type densometer manufactured by Toyo Seiki Seisakusho Co., Ltd. based on JIS P8117.

[Example 1]
As an aromatic polymer, poly (paraphenylene terephthalamide) (hereinafter abbreviated as PPTA), which is a total aromatic polyamide, was produced by the following method.

A 500 ml separable flask with a stirrer, thermometer, nitrogen inflow tube and powder addition port was used. After the flask is sufficiently dried by flowing nitrogen into the flask, 409.2 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) is put into the flask as a solvent, and calcium chloride as a chloride is added. (Used after vacuum drying at 200 ° C. for 2 hours) was added in an amount of 30.8 g, and the temperature was raised to 100 ° C. to completely dissolve calcium chloride. Then, the temperature of the obtained solution was returned to room temperature (25 ° C.), and the water content of the solution was adjusted to 500 ppm.

Next, 13.20 g of para-phenylenediamine (hereinafter abbreviated as PPD) as an aromatic diamine was added and completely dissolved. While maintaining the temperature of this solution at 20 ± 2 ° C. and stirring at a rotation speed of 150 rpm, 24.18 g of terephthalic acid dichloride (hereinafter abbreviated as TPC) as a reactive group-containing compound was added (molar ratio: PPD /). TPC = 1.025). However, TPC was added in three portions at intervals of about 10 minutes. After the addition of TPC was completed, the reaction between PPD and TPC was aged for 1 hour while maintaining the temperature of the solution at 20 ± 2 ° C. and stirring at a rotation speed of 150 rpm. As a result, a solution of PPTA was obtained. The obtained PPTA showed optical anisotropy. The weight of PPTA was 6.0 when the total weight of PPTA (PPD + TPC), calcium chloride and NMP was 100. That is, the concentration of PPTA in the solution of PPTA was 6.0% by weight.

A 500 ml separable flask with a stirrer, thermometer, nitrogen inflow tube and liquid inlet was used. After the flask was sufficiently dried by flowing nitrogen into the flask, 100 g of the obtained PPTA solution was weighed into the flask. Then, 300 g of NMP was added, and the mixture was stirred at a rotation speed of 300 rpm for 10 minutes. As a result, a polymer composition was obtained. The concentration of PPTA in the polymer composition was 1.5% by weight.

Next, a separator was manufactured.

A polyethylene porous film was used as a base material (thickness: 25 μm, galley: 85 seconds / 100 ml, basis weight 12 g / m ² ). Then, the porous film was fixed with an adhesive tape on a polyethylene terephthalate (PET) film having a thickness of 100 μm. Then, the polymer composition was coated on the porous film using a bar coater manufactured by Tester Sangyo Co., Ltd. Next, while fixed to the PET film, the porous film on which the coating film of the polymer composition was formed was placed in an atmosphere of 50 ° C. and 70% humidity for 1 minute to precipitate PPTA, which is an aromatic polymer. rice field. Subsequently, the porous film (porous film in which PPTA was laminated) was immersed in a water tank filled with ion-exchanged water, and the PET film was peeled off from the porous film. Then, ion-exchanged water was further passed to remove calcium chloride and NMP from the porous film. Then, the porous film was dried in an oven at 70 ° C. for 10 minutes to obtain a laminated film (coated product) as a separator.

The amount of raw materials charged is summarized in Table 1. The results of the physical property evaluation of the polymer composition and the laminated film are shown in Table 2.

[Example 2]
The same operations and reactions as in Example 1 were carried out except that the amount of TPC added was changed to 24.22 g (PPD / TPC = 1.023) to obtain a polymer composition and a laminated film. The amount of raw materials charged is summarized in Table 1. The results of the physical property evaluation of the polymer composition and the laminated film are shown in Table 2.

[Example 3]
The same operation and reaction as in Example 1 were carried out except that the stirring power was changed by changing the rotation speed when preparing the PPTA solution from 150 rpm to 75 rpm to obtain a polymer composition and a laminated film. .. The amount of raw materials charged is summarized in Table 1. The results of the physical property evaluation of the polymer composition and the laminated film are shown in Table 2.

[Example 4]
The same operation as in Example 1 except that the amounts of NMP, calcium chloride, PPD and TPC were changed to 260.4 g, 19.6 g, 8.40 g and 15.39 g, respectively (PPD / TPC = 1.025). And reaction was carried out to obtain a polymer composition and a laminated film. The amount of raw materials charged is summarized in Table 1. The results of the physical property evaluation of the polymer composition and the laminated film are shown in Table 2.

[Comparative Example 1]
The same operation and reaction as in Example 1 were carried out except that the water content of the solution was adjusted to 120 ppm and the amount of TPC was changed to 24.30 g (PPD / TPC = 1.020), and the polymer composition was formed. A product and a laminated film were obtained. The amount of raw materials charged is summarized in Table 1. Then, an attempt was made to evaluate the physical properties of the polymer composition and the laminated film. However, since the obtained PPTA solution has no fluidity, the filtration occlusion coefficient could not be calculated (unmeasurable). Also, the PPTA solution could not be applied to the substrate and therefore could not form a heat-resistant porous layer (not evaluable). Furthermore, since a heat-resistant porous layer could not be formed, a laminated film could not be obtained (measurement was impossible). The results of Comparative Example 1 are shown in Table 2.

表２に記載の結果から明らかなように、本発明に係る製造方法によって得られた芳香族重合体は、積層フィルムを含むセパレータの耐熱多孔層として好適に用いることができることが判った。

As is clear from the results shown in Table 2, it was found that the aromatic polymer obtained by the production method according to the present invention can be suitably used as a heat-resistant porous layer of a separator containing a laminated film.

The method for producing an aromatic polymer according to the present invention can be widely used, for example, in the field of producing a non-aqueous electrolyte secondary battery capable of ensuring high safety.

Claims (7)

A polymer composition containing a nitrogen-containing aromatic polymer and a solvent.
The filtration blockage coefficient is 34 m ² / m ³ or less,
The nitrogen-containing aromatic polymer is a polymer obtained by polymerizing an aromatic diamine and a compound having a hydrolyzable reactive group that reacts with an amino group, and the aromatic diamine and the amino group are used. the molar ratio of the compound having a reactive hydrolysis of the reactive groups (a compound having a reactive group hydrolysable to react with the aromatic diamine / the amino group) is Ri 1.023 to 1.050 der,
The water content of the solvent is Ru 500ppm~2500ppm der polymer composition. The polymer composition according to claim 1, wherein the nitrogen-containing aromatic polymer is a total aromatic polyamide. The polymer composition according to claim 1 or 2, wherein the solvent is an aprotic polar solvent. The polymer composition according to any one of claims 1 to 3, wherein the nitrogen-containing aromatic polymer has an intrinsic viscosity of 1.5 dL / g to 3.0 dL / g. A laminated film obtained by coating a substrate with the polymer composition according to any one of claims 1 to 4. A separator containing the laminated film according to claim 5. A non-aqueous electrolyte secondary battery containing the separator according to claim 6.