JP2021187988A - Para-type wholly aromatic copolyamide resin, manufacturing method of its resin coating liquid, and laminated porous film formed by coating the resin coating liquid - Google Patents

Abstract

To provide a laminated porous film containing a para-type wholly aromatic copolyamide resin excellent in balance between high solubility to a solvent and coating viscosity of a coating liquid, and between shrinkage rate of a laminate film, transmittance, supportability of inorganic particle, and adhesion with an electrode.SOLUTION: A laminated porous film is obtained by coating, on a polyolefin porous sheet, a coating liquid in which a synthetic latex and inorganic particles are contained in a para-type wholly aromatic copolyamide resin containing 3,3'oxydiphenylene diamine, or 3,4'-oxydiphenylene diamine, or 4,4'oxydiphenylene diamine, or a mixture thereof in the range of 20 to 80 mol% to a total diamine component and having the weight average molecular weight of 45,000 to 120,000.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a para-type total aromatic copolyamide resin and a para-type total aromatic copolyamide resin coating liquid, and a laminated porous film coated with a para-type total aromatic copolyamide resin. More specifically, a coating liquid obtained by adding inorganic particles and synthetic latex to a para-type total aromatic copolyamide resin solution composed of a specific diamine component is prepared, and the coating liquid is used to prepare a para-type total aromatic copolyamide laminated film. Is related to a laminated porous film laminated on a polyamide porous sheet.

A porous membrane of polyolefin such as polyethylene or polypropylene is used for the separator used in the lithium ion battery. If something goes wrong with the battery, the temperature inside the battery may rise. The porous polyolefin membrane closes as the temperature rises and shuts down the battery (shutdown function).

When the temperature rises further and exceeds the melting point of the polyolefin, the porous membrane shrinks, short-circuiting the battery and short-circuiting. After that, it is accompanied by a decomposition reaction of the electrolytic solution and the positive electrode, causing a thermal runaway reaction and igniting.

In order to prevent this thermal runaway reaction, various proposals have been made to impart heat resistance to the porous polyolefin membrane. For example, heat resistance has been enhanced by a technique of coating polyvinylidene fluoride, a water-based acrylic resin, or the like together with inorganic particles such as alumina.
However, the heat resistance required for batteries, such as charging in a shorter time, is increasing year by year. Therefore, an aramid resin is used instead of these resins (Patent Document 1).

However, in order to coat an aramid resin typified by polyparaphenylene terephthalamide, it is necessary to dissolve it in a solvent, and therefore it is necessary to reduce the molecular weight of the aramid resin. However, since the aramid resin has a strong intramolecular interaction, there are problems that crystals are easily precipitated, the stability of the coating liquid is poor, and the productivity is poor.
Therefore, a method of forming finely divided para-type aramid fibers or para-type aramid resin fillers and mixing them with the coating liquid has been proposed (Patent Documents 2 and 3).

However, it is difficult to make a thin film with these fibers and fillers, and it is not feasible. Further, when these aramid resins are coated, there is a problem that the surface is slippery, the adhesiveness between the electrode and the separator is poor when assembling the battery, and the productivity is poor.
From this point of view, a method of increasing the adhesiveness with an electrode and suppressing shrinkage by using a resin having a low glass transition temperature without using a heat-resistant resin has been implemented (Patent Document 4).

However, these resins are not preferable because the glass transition temperature is low and rapid deterioration occurs when the temperature reaches a higher temperature. Therefore, the fact is that no porous membrane having heat resistance and satisfying the contradictory requirements of adhesiveness to a separator has been found so far.

Japanese Unexamined Patent Publication No. 2007-299612 Publication No. 109321127 of China Japanese Unexamined Patent Publication No. 2019-79807 Japanese Unexamined Patent Publication No. 2016-32934

An object of the present invention is to solve the problems in the prior art, such as high solubility in a solvent, coating viscosity of a coating liquid, shrinkage rate of a laminated film, transmittance, supportability of inorganic particles, and adhesion to an electrode. It is an object of the present invention to provide a laminated porous film containing a para-type total aromatic copolyamide resin having an excellent balance of properties.

As a result of diligent studies to solve the above problems, the present inventor has dissolved a para-type total aromatic copolyamide resin containing a second component in a diamine of a para-type total aromatic polyamide resin in a solvent. We have found that the above problems can be solved by dispersing the synthetic latex resin in the resin solution, and have completed the present invention.

That is, according to the present invention.
1. 1. The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. Para-type total aromatic copolyamide resin, characterized by being 000,
2. 2. The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. The para-type total aromatic copolyamide resin of 000 is redissolved in an N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAc) solution containing an inorganic salt at a ratio of 2 to 12% by mass, and further glass transition is performed. It is characterized in that 10 to 400 parts of a latex having a temperature of 0 ° C. or lower is mixed with 100 parts of a para-type total aromatic copolyamide resin, and 200 to 950 parts of inorganic particles are mixed with 100 parts of a para-type total aromatic copolyamide resin. Manufacturing method of para-type total aromatic copolyamide resin coating liquid,
3. 3. The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. The para-type total aromatic copolyamide resin of 000 is redissolved in an N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAc) solution containing an inorganic salt at a ratio of 2 to 12% by mass, and further glass-transferred. Para that is made by mixing 10 to 400 parts of latex having a temperature of 0 ° C. or less with 100 parts of para-type total aromatic copolyamide resin, and 200 to 950 parts of inorganic particles with 100 parts of para-type total aromatic copolyamide resin. A laminated porous film formed by coating a mold total aromatic copolyamide resin coating liquid on a polyolefin porous sheet having a thickness of 10 μm or less to a thickness of 2 to 15 μm.
4. The laminated porous membrane according to 3 above, wherein the heat shrinkage rate during heat treatment at 150 ° C. for 60 minutes is 10.0% or less.
5. The laminated porous film according to 3 or 4 above, wherein the polyolefin porous sheet is a nonwoven fabric or a porous film.
6. A laminated separator using the laminated porous membrane according to any one of 3 to 5 above.
7. A non-aqueous secondary battery using the laminated separator according to the above 6.
8. An electric double layer capacitor using the laminated separator according to the above 6.
Is provided.

According to the present invention, a laminated film made of a para-type total aromatic copolyamide resin having excellent solubility in a solvent, supportability of inorganic particles, and adhesiveness, and a laminated porous film on which the laminated film is laminated are obtained. Therefore, it can be suitably used for applications such as a laminated separator used in a lithium ion battery.

Hereinafter, the present invention will be described in detail.

<Para-type all-aromatic copolyamide resin>
The para-type total aromatic copolyamide resin in the present invention is a polymer in which one or more divalent aromatic groups represented by the chemical formula (1) are directly linked by an amide bond. A benzene ring is bonded to the aromatic group constituting the para-type total aromatic copolyamide resin at the para position, and _{the aromatic group of Ar 1} in the chemical formula (1) is 20 to 80 mol% in the chemical formula (2). Any one of 3,3'oxydiphenylenediamine, 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine represented by (4), or a mixture thereof. It is a para-type total aromatic copolyamide resin contained as a second component of diamine. _{Ar 2} in the chemical formula (1) will be described in detail in the following [Raw material for para-type total aromatic copolyamide resin].

<Manufacturing method of para-type total aromatic copolyamide resin>
The para-type total aromatic copolyamide resin in the present invention can be produced according to a conventionally known method. For example, it can be obtained by reacting an aromatic dicarboxylic acid dichloride (hereinafter, also referred to as "acid chloride") component and an aromatic diamine component in an amide-based polar solvent by low-temperature solution polymerization, surface polymerization, or the like.

[Raw material for para-type total aromatic copolyamide resin]
(Aromatic dicarboxylic acid dichloride component)
_{Examples of the aromatic dicarboxylic acid chloride component (Ar 2} in the chemical formula (1)) used in the production of the para-type total aromatic copolyamide resin include terephthalic acid dichloride. In addition, those having a functional group such as 2-fluoro-terephthalic acid chloride, 2-chloro-terephthalic acid dichloride, 2-cyano-terephthalic acid dichloride may be used. From the viewpoint of economic rationality, terephthalic acid dichloride is preferable.

(Aromatic diamine component)
As the aromatic diamine component used in the production of the para-type total aromatic copolyamide resin, para-phenylenediamine is used as the one satisfying the above chemical formula (1). Further, as another aromatic ring, 2-fluoro-para-phenylenediamine, 2-chloro-para-phenylenediamine, 2-cyano-para-phenylenediamine and the like may be used. From the viewpoint of economic rationality, para-phenylenediamine is preferable. This is the first component.

Further, as those satisfying the above chemical formulas (2) to (4), either 3,3'oxydiphenylenediamine, 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine. Use one or a mixture of these. This is the second component.

The second component is used by mixing with the first component. The ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, preferably 30 to 70 mol%. When the ratio of the second component is larger than 80 mol%, crystals of the polymer are precipitated and the solution becomes unstable. Further, when the ratio is smaller than 20 mol%, the film strength of the obtained polymer is lowered.

[Polymerization solvent]
Examples of the solvent for polymerizing the para-type total aromatic copolyamide resin include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and the like. Organic polar amide solvents such as N-methylcaprolactam (NMC), water-soluble ether compounds such as tetrahydrofuran and dioxane, water-soluble alcohol compounds such as methanol, ethanol and ethylene glycol, water-soluble ketone compounds such as acetone and methyl ethyl ketone, Examples thereof include water-soluble nitrile compounds such as acetonitrile and propionitrile. These solvents can be used alone or as a mixed solvent of two or more kinds. The solvent used is preferably dehydrated and preferably has a water content of less than 100 ppm.

In the production of the para-type total aromatic copolyamide resin used in the present invention, N-methyl-2-pyrrolidone is used from the viewpoints of versatility, harmfulness, handleability, solubility in the para-type total aromatic copolyamide resin, and the like. It is preferable to use (NMP), N, N-dimethylacetamide (DMAc).

Further, it is preferable that the content of water in the solvent used in the present invention is 100 ppm or less. If it is 100 ppm or more, the reaction rate of the monomer decreases and the desired degree of polymerization is not reached, which is not preferable.

[Molecular weight of polymer]
The weight average molecular weight (Mw) of the para-type total aromatic copolyamide resin needs to be 45,000 to 120,000. When the weight average molecular weight (Mw) is less than 45,000, the resin cannot support the inorganic particles after being mixed with the inorganic particles and then coated on the porous polyolefin sheet, resulting in powder falling. On the other hand, when the weight average molecular weight exceeds 120,000, the viscosity of the coating liquid becomes too high and the productivity deteriorates.

The molecular weight of the polymer is adjusted by the molar ratio of diamine and acid chloride at the time of polymerization. A polymer having a molecular weight of 150,000 or more is isolated into threads by the coagulation method described later, and then acid or alkali. The molecular weight of the polymer may be adjusted to the above range by immersing it in an aqueous solution and heating it to hydrolyze it. In this case, alkali is preferable because it is an irreversible reaction and can reduce the molecular weight more efficiently.

[Other polymerization conditions, etc.]
The concentration of the polymer is preferably 2 to 12% by mass. When the concentration of the polymer is less than 2% by mass, the viscosity is too low, and the process is not stable when the polymer is later solidified and the polymer is isolated, which is not preferable. Further, if it exceeds 12% by mass, the polymer is not completely dissolved and precipitates, which is not preferable.

In order to improve the solubility of the total aromatic copolyamide polymer produced, an appropriate amount of a generally known inorganic salt may be added before, during, or at the end of the polymerization. Examples of such an inorganic salt include chlorides of alkali metals such as lithium chloride, sodium chloride and calcium chloride, and chlorides of alkaline earth metals such as magnesium chloride and calcium chloride. Of these, lithium chloride and calcium chloride are preferable.

Further, the end of the para-type total aromatic copolyamide resin can also be sealed. When the end is sealed with an end-capping agent, for example, phthalic acid chloride and its substitution product, aniline and its substitution product and the like can be used as the end-sealing agent.
Further, in order to capture the generated acid such as hydrogen chloride, an aliphatic or aromatic amine, a quaternary ammonium salt or the like can be used in combination.

After completion of the reaction, if necessary, a basic inorganic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide and the like may be added to carry out the neutralization reaction.
After the neutralization reaction, the precipitated salt is preferably removed via a filtration process.

Since the polymer solution obtained by the above method can maintain a solution state at 0 to 80 ° C., this solution can be used as it is as a coating liquid for a porous polyolefin sheet. It is also possible to make a solid by immersing the polymer solution obtained in the present invention in a poor solvent and solidifying it.
When it is made into a solid, it is made into a solid by the following method and redissolved in a solvent.

[Coagulation method]
The method for preparing the polymer solution (dope) containing the para-type total aromatic copolyamide resin and the solvent is not particularly limited, and a known method can be adopted.
Solvents used to prepare the polymer solution (dope) include, for example, N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylcaprolactam. (NMC) and the like can be mentioned. Further, the solvent used may be one type alone or a mixed solvent in which two or more types are mixed. Further, the solvent used for the polymerization of the para-type total aromatic copolyamide resin may be used as it is.

The polymer concentration in the polymer solution (dope), that is, the concentration of the para-type total aromatic copolyamide resin is preferably in the range of 2.0% by mass or more and 12% by mass or less. When the polymer concentration in the polymer solution (dope) is less than 2.0% by mass, the entanglement of the polymer is small, so that the required viscosity cannot be obtained at the time of solidification, and the discharge stability is lowered. On the other hand, when the polymer concentration exceeds 12% by mass, the viscosity of the dope rapidly increases, so that the discharge stability is lowered and solidification tends to be difficult.

[Coagulation bath]
In the production method of the present invention, the polymer is wet-coagulated as described above, and the composition of the coagulating liquid is preferably a poor solvent for the para-type total aromatic copolyamide resin. The composition of the coagulant does not necessarily have to be single, and may be, for example, a mixed solution of NMP and water. From the viewpoint of solvent recovery efficiency, the coagulation bath composition (NMP / water) preferably has a high NMP concentration, and preferably has an NMP concentration of 30% or more. More preferably, it is 35% or more.

[Other processes]
After the solid matter is pulled up from the coagulation liquid, the solid matter formed by coagulation in the coagulation bath is washed with water to gradually remove the solvent. Therefore, the temperature of the washing bath is preferably 60 ° C. or lower.
After washing with water, it may be dried at a temperature of 100 ° C. or higher and then cut, or it may be left as a solid. When treating with an acid or an alkali in order to reduce the molecular weight, the cut or solid substance can be immersed in an aqueous solution of an acid or an alkali and heated.

[Redissolution]
Next, the polymer having a weight average molecular weight (Mw) adjusted to 45,000 to 120,000 is dissolved in a solvent and redissolved. The solvent used is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylcaprolactum (NMC). be able to. Further, the solvent used may be one type alone or a mixed solvent in which two or more types are mixed. Of these, N-methyl-2-pyrrolidone (NMP) is preferable.

For redissolution, a known mixer can be used, a uniaxial mixer, a ribbon mixer, a planetary mixer, or the like can be used. For example, considering that the thread is used without being cut, it is preferable to select a planetary mixer. For dissolution, the solvent is put into a mixer, and then threads or cut threads, a powdery polymer, or a solid polymer is dispersed in the solvent. Warm while dispersing. The temperature is preferably 60 ° C. or higher. 80 ° C. or higher is more preferable because the melting time can be shortened. After raising the temperature, it is preferable to mix a metal halide salt such as lithium chloride, calcium chloride, or lithium bromide because the solubility is enhanced.
The para-type total aromatic copolyamide resin solution obtained by isolating the polymer after polymerization or isolating the polymer after polymerization and then dissolving it in a solvent again is applied to a porous polyolefin sheet by the following method.

[Adjustment of coating liquid]
A coating solution is prepared using a polymer solution obtained by polymerization or a polymer solution that is coagulated and redissolved after polymerization. The solvent used is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylcaprolactum (NMC). be able to. Further, the solvent used may be one type alone or a mixed solvent in which two or more types are mixed. Of these, N-methyl-2-pyrrolidone (NMP) is preferable. The polymer concentration of the coating liquid is preferably 2% by mass or more and 12% by mass or less. When the concentration of the polymer is less than 2% by mass, the amount of the polymer is small and powder falling may occur, which is not preferable. On the other hand, when the polymer concentration exceeds 12% by mass, the viscosity of the coating liquid becomes too high, and the productivity deteriorates, which is not preferable.

Synthetic latex is mixed with this polymer solution. By mixing the synthetic latex, the obtained laminated porous film is placed between the electrodes and pressed, so that no deviation occurs in the battery assembly process. Further, since the adhesiveness to the excellent electrode is good, the heat resistance can be improved.

As the synthetic latex to be used, latex such as acrylonitrile-butadiene-based latex, styrene-butadiene-based latex, acrylate-based latex and copolymers thereof can be used. The glass transition temperature of latex is preferably 0 ° C. or lower. If the temperature exceeds 0 ° C., the glass is in a glass state at room temperature, and the adhesiveness in the battery manufacturing process after coating is poor, which is not preferable. The moisture content of the latex is preferably 65% or less. If it exceeds 65%, the para-type total aromatic copolyamide resin tends to precipitate in the solvent, which is not preferable. More preferably, it is 50% or less.

Conventionally, polyparaphenylene terephthalamide (PPTA) has been used when coating a para-type total aromatic copolyamide resin. (Patent Document 1). At that time, it has been used as a low degree of polymerization in order to make it soluble in a solvent at the time of polymerization, but the stability of the solution is poor and it is necessary to apply the solution immediately after preparing the aramid resin solution. Therefore, it is difficult to mix other resin components and the like that impair the stability of the solution, and it is not possible to use latex containing water in particular.

Further, when PPTA fiber is used, it is necessary to take measures such as forming it into a pulp-like shape or a shortcut fiber and further making it finer, and further, it is necessary to take measures such as forming a filler.
In addition, a binder resin was used to hold them together, but it was difficult to make a thin film with a fiber diameter or less.

Since the para-type total aromatic copolyamide resin of the present invention is easily and stably dissolved in a solvent, it can be thinned. Furthermore, by mixing latex or the like with a solvent in which this para-type all-aromatic copolyamide resin is dissolved, a obtained laminated porous film is placed between the electrodes, and sufficient adhesive strength is provided in the battery assembly process of pressing. It is possible to show and show excellent process passability. In addition, since the adhesiveness to the electrode is excellent, when the shrinkage stress of the polyolefin porous membrane is generated due to the temperature rise, the adhesive force with the electrode resists the shrinkage stress, and as a result, it is possible to reduce the shrinkage. It becomes.

The synthetic latex is added little by little while stirring the para-type total aromatic copolyamide resin solution. The synthetic latex needs to be mixed with 100 parts of the para-type total aromatic copolyamide resin in an amount of 10 to 400 parts in terms of solid content, more preferably 20 to 300 parts, still more preferably 50 to 250 parts. ..

If the amount of the synthetic latex is less than 10 parts, the adhesive effect is lost, which is unsuitable. If the amount exceeds 400 parts, the para-type total aromatic copolyamide resin dissolved in the solvent is precipitated, which is unsuitable.

At this time, a nonionic, anionic, or cationic surfactant may be added as a dispersant, if necessary. More preferably, it is a nonionic surfactant.
A synthetic latex is added to and dispersed in a polymer solution in which this para-type total aromatic copolyamide resin is dissolved in a solvent, and then inorganic particles are further mixed to complete a coating liquid.

Inorganic particles include wet or dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, aluminum hydroxide, boehmite, magnesium hydroxide, magnesium carbonate, zinc carbonate, zinc oxide, antimony oxide, etc. Celium oxide, zirconium oxide, tin oxide, lanthanum oxide, magnesium oxide, barium carbonate, zinc carbonate, basic carbonate, barium sulfate, calcium sulfate, lead sulfate, zinc sulfide, mica, mica titanium, talc, clay, kaolin, huh Examples include lithium carbonate and calcium fluoride.

The content of the inorganic particles is 200 to 950 parts with respect to 100 parts of the polymer. When the content of the inorganic particles is less than 200 parts, collisions between the particles that resist the contraction stress when the olefin film contracts are less likely to occur, which is not preferable. On the other hand, when the content of the inorganic particles exceeds 950 parts, the amount of the polymer is too small with respect to the inorganic particles, so that the particles are not supported and fall off, so-called powder dropping occurs, which is not preferable. The content of the inorganic particles is preferably 230 to 900 parts, more preferably 400 to 900 parts.

The polymer concentration of the polymer solution in which the para-type total aromatic copolyamide resin used in the coating liquid is dissolved in a solvent is 2% by mass or more and 12% by mass or less. It is preferably 4% by mass or more and 10% by mass or less, and more preferably 4% by mass or more and 8% by mass or less. When the polymer concentration is less than 2% by mass, the amount of the polymer is small and powder dropping may occur, which is not preferable. On the other hand, when the polymer concentration exceeds 12% by mass, the viscosity of the coating liquid becomes too high, and the productivity deteriorates, which is not preferable.

[Coating]
In the present invention, the para-type total aromatic copolyamide resin coating liquid is coated on a polyolefin porous sheet having a thickness of 10 μm or less to a thickness of 2 to 15 μm to obtain a laminated porous film.

The amount of coating on the porous polyolefin sheet is preferably ^{20 to 80 g / m 2.} Examples of the coating method include a doctor knife method, a knife coater method, a gravure coater method, a screen printing method, a spray method, a roll coater method, a comma coater method, and a Meyerbar method.

In the present invention, the sheet coated with the aromatic copolyamide polymer composition on the surface is dried by a dryer. The drying temperature is preferably 50 to 100 ° C. More preferably, it is 60 to 80 ° C. If the temperature exceeds 100 ° C., the porosity of the obtained polyolefin porous membrane may melt and close the pores, which is not preferable. If the temperature is 50 ° C. or lower, the production rate is lowered, which is not preferable.

After drying, it may be immersed in a coagulating solution of a poor solvent in order to remove the residual solvent. Examples of the coagulation method include a method of spraying the coagulation liquid and a method of immersing the coagulation liquid in the coagulation liquid. The coagulating liquid may be any liquid capable of coagulating the polymer composition, but in the present invention, water is preferable, and impurities are removed by an ion exchange resin, a reverse osmosis membrane, a filter, or a composite facility in which these are arranged in series. The removed pure water is preferable. The conductivity of this pure water is preferably 1.0 μS / cm or less. From the viewpoint of solvent recovery and from the viewpoint of forming the structure of the laminated film, it is preferable that water contains 0 to 30% by mass of the solvent used in the polymer composition.

[Laminated porous membrane]
The thickness of the laminated film in the laminated porous film is 2 to 15 μm. If the thickness of the laminated film exceeds 15 μm, the electrode area in the battery volume is reduced, and the electric capacity is reduced, which is not preferable. Further, if the thickness is less than 2 μm, the laminated film as the heat-resistant layer is too thin, so that the shrinkage stress of the separator cannot be resisted and low shrinkage cannot be realized. The thickness of the laminated film is preferably 3 to 12 μm, more preferably 3 to 10 μm.
Further, the shrinkage rate of the laminated porous film having the heat-resistant laminated film is preferably 10% or less in the treatment at 150 ° C. for 1 hour. It is more preferably 7% or less, still more preferably 5% or less.

Assuming that the temperature rises due to an abnormality in the battery, there is a possibility that the temperature will rise to 150 ° C if the temperature rise rate is high after the shutdown function that closes the pores of the olefin film is activated at around 100 ° C. .. At this time, if the shrinkage rate is larger than 10%, the separator shrinks and short-circuits at the time of this temperature rise, which causes further temperature rise and thermal runaway reaction, which is not preferable because it causes the battery to ignite. When the shrinkage rate is 10% or less in the treatment of 150 ° C. × 1 hour, even if the temperature is raised to 150 ° C., it is preferable because the time until the temperature of the battery starts to be lowered can be secured without causing a short circuit until the temperature drops.

In the laminated porous membrane thus obtained, it is important that the difference in air permeability (△ air permeability) between the laminated membrane and the polyolefin porous sheet is 25 to 120 seconds / 100 cc. When the difference in air permeability (Δair permeability) is smaller than 25 seconds / 100 cc, the structure of the laminated film becomes loose and low shrinkage cannot be achieved, and powder drops occur, which makes it unsuitable as a separator. On the other hand, when the difference in air permeability (△ air permeability) is larger than 120 seconds / 100 cc, a separator with low shrinkage and no powder falling can be obtained, but the movement of lithium ions between the positive electrode and the negative electrode is hindered. However, the battery performance is reduced.

[Use]
The resin coating liquid can be used as a coating liquid for a laminated separator. The resin can also be molded into other woven fabrics, non-woven fabrics, etc. and applied to heat-resistant filter applications. In addition, since it can be easily redissolved in a solvent, it can be applied to varnish applications.

Further, the laminated porous film having the laminated film formed from the above coating liquid is used for improving the heat resistance of the battery using the olefin laminated separator. Further, the heat resistance of the laminated film made of the para-type total aromatic copolyamide resin, latex, and inorganic particles obtained in the present invention can be used up to 450 ° C. It can be used. Further, the laminated separator using these can be used for a capacitor such as a non-aqueous secondary battery and an electric double layer capacitor.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples and Comparative Examples. In addition, each physical property in the example was measured by the following method.

(1) Molecular Weight The weight average molecular weight (Mw) and the molecular weight polydispersity (Mw / Mn) were measured by gel permeation chromatography (GPC) under the following measurement conditions.
Equipment name: High performance liquid chromatograph LC-20A series Column oven: CTO-20A
Mobile phase: NMP
Autosampler: SIL-20AHT
LC workstation: LC solution
Flow rate: 0.3 ml / min Differential refractometer detector: RID-10A
Oven temperature: 60 ° C
Molecular weight standard sample: Polystyrene

(2) Viscosity The viscosity was measured under the condition of a temperature of 20 ° C. using a TVB-10 type manufactured by Toki Sangyo.

(3) Thickness of Laminated Membrane The polyolefin porous sheet and the laminated porous membrane as the base material are punched out to a size of 10 cm × 10 cm, the thickness of each is measured at 9 points, and the average value is calculated. Was calculated.
Thickness of laminated film = (average value of thickness of laminated porous film)-(average value of thickness of porous polyolefin sheet)

(4) Heat shrinkage rate at 150 ° C. The obtained laminated porous membrane is cut out to a certain size, the section is sandwiched between papers and placed in a dryer set at a temperature of 150 ° C. for 60 minutes, and heat is generated from the dimensional change before and after heat drying. The shrinkage rate was measured. The shrinkage rate was measured in two directions, a direction parallel to the substrate feeding direction (MD) and a vertical direction (TD), and the average value was taken as the heat shrinkage rate.

(5) Air permeability The air permeability of the base material and the laminated film was measured according to JIS P8117 (Garley type air permeability measurement method). Here, the "Δ air permeability" is a value obtained by subtracting the air permeability of the base material from the air permeability of the laminated film.

(6) Powder drop The laminated film and the black imitation paper were overlapped and rubbed up and down 10 times, and it was visually judged whether or not particles remained on the black imitation paper at that time.

(7) Adhesive A cast film was prepared by dissolving a polyvinylidene fluoride resin solution in N-methyl-2-pyrrolidone so that the total solid content concentration was 45% by mass. It was cut out into a rectangular shape of 320 mm × 520 mm to form a pseudo electrode plate.

A laminated porous film coated with a para-type total aromatic copolyamide resin, latex, and inorganic particles was cut out to a size of 10 cm × 10 cm, and the surface of the laminated film was centered so as to be in contact with the polyvinylidene fluoride film. Arranged. A vinyl chloride plate having a size of 10 cm × 10 cm, a thickness of 1 mm, and a weight of 15 g was attached to the surface of the laminated porous film on the side of the polyolefin porous sheet. The pseudo electrode plate was tilted at 45 degrees, and it was confirmed whether or not the laminated porous membrane pieces slipped off. Good adhesion when it does not slip off. If the position deviates by 1 cm or more, it is judged that the adhesiveness is poor.

<Example 1>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP), 8 g of calcium chloride, 3.0428 g of para-phenylenediamine, and 5.6343 g of 3,4'-diaminodiphenyl ether (DAPE) having a water content of 100 ppm or less were placed in a reaction vessel at room temperature. It was added, dissolved and mixed in a nitrogen atmosphere, and then 11.1972 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, 16.23 g of an NMP slurry solution of 22.5% calcium hydroxide was added, and the polymerization was terminated by performing a neutralization reaction to obtain a polymer solution of a para-type total aromatic copolyamide resin.

[Creation of coating liquid]
NMP was added to the obtained polymer solution so that the polymer concentration became 4% by mass, and 150 parts of acrylic copolymer latex (Polytron Z865 manufactured by Asahi Kasei) was added to the resin solution with respect to 100 parts of the polymer in terms of solid content. Added with stirring. After stirring uniformly, alumina (Sumika Corundum AA03 manufactured by Sumitomo Chemical Co., Ltd.) was added to 100 parts of the polymer so as to be 400 parts (polymer / alumina = 20/80) to prepare a coating liquid for lamination.

[Coating of coating liquid]
A polyolefin porous sheet having a film thickness of 10 μm and an air permeability of 170 seconds / 100 cc was coated using a Meyer bar. After coating, it was immersed in water, solidified and dried to obtain a laminated porous film. The thickness of the obtained laminated porous membrane was 14.2 μm.

<Example 2>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 50 parts of the acrylic copolymerized latex was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 3>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 250 parts of the acrylic copolymer latex was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 4>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 230 parts of alumina was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 5>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 900 parts of alumina was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 6>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 2.2821 g of para-phenylenediamine, and 4.2258 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 8.4407 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, the polymerization was terminated by performing a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide to obtain a para-type total aromatic copolyamide resin solution.

[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 7>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 3.0428 g of para-phenylenediamine, and 5.6343 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 10.9115 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, the polymerization was terminated by performing a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide to obtain a para-type total aromatic copolyamide resin solution.

[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 8>
[Polymerization of para-type total aromatic copolyamide resin]
The procedure was the same as in Example 1 except that 5.3926 g of para-phenylenediamine, 2.4963 g of 3,4'-DAPE, and 12.4024 g of terephthalic acid dichloride were added.
[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 9>
[Polymerization of para-type total aromatic copolyamide resin]
The procedure was the same as in Example 1 except that 1.1093 g of para-phenylenediamine, 8.2164 g of 3,4'-DAPE, and 10.2054 g of terephthalic acid dichloride were added.
[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 10>
[Polymerization of para-type total aromatic copolyamide resin]
The procedure was carried out in the same manner as in Example 1 except that 5.6343 g of 4,4'-DAPE was added instead of 3,4'-DAPE.
[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Example 11>
[Polymerization of para-type total aromatic copolyamide resin]
The same procedure as in Example 1 was carried out except that 2,81715 g of 4,4'-DAPE and 2.81715 g of 3,3'-DAPE were added instead of 3,4'-DAPE.
[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 1>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less and 5.4464 g of para-phenylenediamine are placed in a reaction vessel at room temperature, dissolved and mixed in a nitrogen atmosphere, and then terephthalic acid chloride is added while stirring. 9.4074 g was added and polymerized. The polymer was precipitated and a dissolution dope could not be obtained.

<Comparative Example 2>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The procedure was carried out in the same manner as in Example 1 except that the acrylic copolymerized latex was not added.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 3>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 800 parts of the acrylic copolymer latex was added to the polymer. The polymer settled and could not be coated.

<Comparative Example 4>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 5.3250 g of para-phenylenediamine, and 9.8601 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 17.7975 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Then, the polymerization was terminated by carrying out a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide. The polymer settled and the coating liquid could not be prepared.

<Comparative Example 5>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 2.2821 g of para-phenylenediamine, and 4.2258 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 8.5650 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, the polymerization was terminated by performing a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide to obtain a para-type total aromatic copolyamide resin solution.

[Creation of coating liquid]
The procedure was carried out in the same manner as in Example 1 except that the polymer concentration was set to 1%.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 6>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 6.2924 g of para-phenylenediamine, and 1.2946 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 12.8640 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, polymerization was carried out by performing a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide. The polymer settled and the coating liquid could not be prepared.

<Comparative Example 7>
[Polymerization of para-type total aromatic copolyamide resin]
200 g of N-methyl-2-pyrrolidone (NMP) having a water content of 100 ppm or less, 0.5388 g of para-phenylenediamine, and 8.9784 g of 3,4'-DAPE were placed in a reaction vessel at room temperature and dissolved and mixed in a nitrogen atmosphere. Then, 9.9127 g of terephthalic acid chloride was added with stirring. Subsequently, the polymerization reaction was carried out at 85 ° C. for 60 minutes to obtain a transparent and viscous polymer solution. Next, the polymerization was terminated by performing a neutralization reaction using an NMP slurry solution of 22.5% calcium hydroxide to obtain a para-type total aromatic copolyamide resin solution.

[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 8>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The procedure was carried out in the same manner as in Example 1 except that 100 parts of alumina was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 9>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
The same procedure as in Example 1 was carried out except that 1000 parts of alumina was added to 100 parts of the polymer.
[Coating of coating liquid]
It was carried out in the same manner as in Example 1.

<Comparative Example 10>
[Polymerization of para-type total aromatic copolyamide resin]
It was carried out in the same manner as in Example 1.
[Creation of coating liquid]
It was carried out in the same manner as in Example 1.
[Coating of coating liquid]
The same procedure as in Example 1 was carried out except that a stainless steel bar having a diameter of 20 mm was used instead of using the Meyer bar without providing a clearance.
The results are shown in Tables 1 and 2.

According to the present invention, a laminated film made of a para-type all-aromatic copolyamide resin having high solubility in a solvent, supportability of inorganic particles, high heat resistance, and excellent adhesiveness at the time of battery assembly, and the laminated film are laminated. Since the laminated porous membrane can be obtained, its industrial value is extremely large.

Claims (8)

The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. A para-type total aromatic copolyamide resin characterized by being 000. The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. The para-type total aromatic copolyamide resin of 000 is redissolved in an N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAc) solution containing an inorganic salt at a ratio of 2 to 12% by mass, and further glass transition is performed. It is characterized in that 10 to 400 parts of a latex having a temperature of 0 ° C. or lower is mixed with 100 parts of a para-type total aromatic copolyamide resin, and 200 to 950 parts of inorganic particles are mixed with 100 parts of a para-type total aromatic copolyamide resin. A method for producing a para-type all-aromatic copolyamide resin coating liquid. The diamine component that constitutes the para-type total aromatic copolyamide resin is
Para-phenylenediamine, the first ingredient, and
It contains the second component, 3,3'oxydiphenylenediamine, or 3,4'oxydiphenylenediamine, or 4,4'oxydiphenylenediamine, or a mixture thereof.
A para-type total aromatic polyamide resin in which the ratio of the second component to the total amount of the first component and the second component is 20 to 80 mol%, and the weight average molecular weight of the resin is 45,000 to 120. The para-type total aromatic copolyamide resin of 000 is redissolved in an N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAc) solution containing an inorganic salt at a ratio of 2 to 12% by mass, and further glass-transferred. Para that is made by mixing 10 to 400 parts of latex having a temperature of 0 ° C. or less with 100 parts of para-type total aromatic copolyamide resin, and 200 to 950 parts of inorganic particles with 100 parts of para-type total aromatic copolyamide resin. A laminated porous film formed by coating a mold total aromatic copolyamide resin coating liquid on a polyolefin porous sheet having a thickness of 10 μm or less to a thickness of 2 to 15 μm. The laminated porous film according to claim 3, wherein the heat shrinkage rate during heat treatment at 150 ° C. for 60 minutes is 10.0% or less. The laminated porous film according to claim 3 or 4, wherein the polyolefin porous sheet is a nonwoven fabric or a porous film. A laminated separator using the laminated porous membrane according to any one of claims 3 to 5. A non-aqueous secondary battery using the laminated separator according to claim 6. An electric double layer capacitor using the laminated separator according to claim 6.