Lithium-ion battery gaskets

Abstract

To provide a gasket for a lithium secondary battery, which is expanded, has an excellent tenacity such as an impact resistance, sealability.SOLUTION: A gasket for a lithium-ion battery is an injection molding body of a polyarylene sulfide resin composition containing a thermoplastic elastomer (B) of 1 to 40 wt.% having a reactive functional group against a polyarylene sulfide resin (A) of 100 wt.%. In the gasket for a lithium-ion battery, (a) the polyarylene sulfide resin composition use a fine particle of which a median size (D50) is 100 μm or less, the fine particle is added into a solvent of 100 times against a weight, the fine particle is stirred for three hours in a range of a temperature lower by 5 to 15°C than boiling point of the solvent, and then, the solvent of 0.45 μm after a solid liquid separation by a filtration with a filter is dried and fixed, and a remaining amount at the time becomes an amount corresponded to 40 wt.% or less of the reaction type thermoplastic elastomer (B). In the gasket for a lithium-ion battery, (b) a flow length when the injection molding is performed into a spiral flow molding of the condition that a thickness is 1 mm, a width is 10 mm with an injection pressure of by using an injection molding machine of which a temperature of 100 MPa, a cylinder is adjusted to 310°C, and a metal molding is adjusted to 130°C is 150 to 450 mm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a gasket for lithium ion batteries, and more particularly to a gasket for lithium ion batteries that is excellent in toughness such as elongation and impact resistance, and also has excellent sealing properties when used as a gasket. [Background technology]

[0002] Polyarylene sulfide resin is a resin that exhibits excellent properties such as heat resistance, chemical resistance, low water absorption, and fluidity, and taking advantage of these excellent properties, it is widely used in electrical and electronic equipment components, automotive equipment components, office automation equipment components, etc. However, polyarylene sulfide resin has issues such as poor toughness in terms of elongation and impact resistance, and poor sealing properties when used as gaskets.

[0003] Attempts to improve the toughness of polyarylene sulfide resins and use them as gaskets have been proposed, for example, a resin composition for gaskets in secondary batteries (see, for example, Patent Document 1), which comprises (A) 100 parts by mass of polyarylene sulfide resin and (B) a total of 1 to 6 parts by mass of a thermoplastic elastomer (b1) having a functional group and a thermoplastic elastomer (b2) having no functional group, wherein the thermoplastic elastomer (b1) having a functional group is an ethylene-glycidyl (meth)acrylate copolymer and the thermoplastic elastomer (b2) having no functional group is an ethylene-octene copolymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6228134 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the resin composition proposed in Patent Document 1, there is no mention of verifying whether the polyarylene sulfide resin and the thermoplastic elastomer actually react, and the basis for the reaction is not shown, so the effect of the reaction on improving toughness is unclear, and there are issues with the performance stability as a gasket.

[0006] Therefore, the present invention aims to provide a gasket for lithium ion batteries that has excellent sealing properties without impairing the inherent properties of polyarylene sulfide resin, such as heat resistance, chemical resistance, low water absorption, and fluidity. [Means for solving the problem]

[0007] As a result of intensive research to solve the above problems, the present inventors have found that a specific polyarylene sulfide resin composition has excellent toughness such as elongation and impact resistance, and can be used as an excellent gasket for lithium ion batteries, and have thus completed the present invention.

[0008] That is, the present invention relates to a gasket for a lithium ion battery, which is an injection-molded article of a polyarylene sulfide resin composition comprising 100 parts by weight of a polyarylene sulfide resin (A) and 1 to 40 parts by weight of a thermoplastic elastomer (B) having a reactive functional group, and which satisfies the following (a) and (b): (a) A polyarylene sulfide resin composition having a median diameter (D 50 ) fine particles of 100 μm or less, the fine particles are added to a solvent in an amount 100 times the weight of the fine particles, and stirred for 3 hours at a temperature range 5 to 15°C lower than the boiling point of the solvent. Subsequently, the solution obtained after solid-liquid separation by filtration through a 0.45 μm filter is dried to a solid, and the amount of residue at this time corresponds to 40% by weight or less of the reactive thermoplastic elastomer (B) blended in the polyarylene sulfide resin composition. (b) When injection molding is performed in a spiral flow mold with a wall thickness of 1 mm and a width of 10 mm at an injection pressure of 100 MPa using an injection molding machine adjusted to a cylinder temperature of 310°C and a mold temperature of 130°C, the flow length is 150 to 450 mm.

[0009] The present invention will be described in detail below.

[0010] The polyarylene sulfide resin composition constituting the gasket for a lithium ion battery of the present invention contains 100 parts by weight of a polyarylene sulfide resin (A) and 1 to 40 parts by weight of a thermoplastic elastomer (B) having a reactive functional group. The polyarylene sulfide resin composition comprises: (a) a polyarylene sulfide resin composition having a median diameter (hereinafter, D 50 (b) the fine particles are made into particles of 100 μm or less, the fine particles are added to a solvent in an amount 100 times the weight of the fine particles, the mixture is stirred for 3 hours at a temperature range 5 to 15°C lower than the boiling point of the solvent, and the solution obtained after solid-liquid separation by filtration through a 0.45 μm filter is dried to a solid, and the amount of residue at this time corresponds to 40% by weight or less of the reactive thermoplastic elastomer (B) blended in the polyarylene sulfide resin composition; and (b) the flow length is 150 to 450 mm when injection-molded into a spiral flow mold having a wall thickness of 1 mm and a width of 10 mm at an injection pressure of 100 MPa using an injection molding machine adjusted to a cylinder temperature of 310°C and a mold temperature of 130°C.

[0011] The polyarylene sulfide resin constituting the polyarylene sulfide resin composition may be any resin that belongs to the category generally referred to as polyarylene sulfide resin. Examples of the polyarylene sulfide resin include homopolymers or copolymers composed of p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfide sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, and biphenylene sulfide units. Specific examples of the polyarylene sulfide include poly(p-phenylene sulfide), polyphenylene sulfide sulfone, polyphenylene sulfide ketone, and polyphenylene sulfide ether. Among these, poly(p-phenylene sulfide) is preferred because it provides a gasket for a lithium ion battery that is particularly excellent in heat resistance and strength characteristics.

[0012] Since polyarylene sulfide resins can be used to make gaskets for lithium ion batteries that have an excellent balance between toughness and moldability, they are preferably polyarylene sulfide resins with a melt viscosity of 100 to 2500 poise, particularly 150 to 2000 poise, as measured using a high-temperature flow tester equipped with a die having a diameter of 1 mm and a length of 2 mm under conditions of a measurement temperature of 315°C and a load of 10 kg.

[0013] The polyarylene sulfide resin can be produced by a known method for producing a polyarylene sulfide resin, for example, by polymerizing an alkali metal sulfide salt and a polyhaloaromatic compound in a polar solvent. Examples of the polar organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, cyclohexylpyrrolidone, dimethylformamide, and dimethylacetamide. Examples of the alkali metal sulfide salt include anhydrous or hydrated sodium sulfide, rubidium sulfide, and lithium sulfide. The alkali metal sulfide salt may also be a product of reacting an alkali metal hydrosulfide salt with an alkali metal hydroxide. Examples of polyhaloaromatic compounds include p-dichlorobenzene, p-dibromobenzene, p-diiodobenzene, m-dichlorobenzene, m-dibromobenzene, m-diiodobenzene, 4,4'-dichlorodiphenyl sulfone, 4,4'-dichlorobenzophenone, 4,4'-dichlorodiphenyl ether, and 4,4'-dichlorodibiphenyl.

[0014] Examples of polyarylene sulfide resins include linear polyarylene sulfide resins, polyarylene sulfide resins obtained by heat treatment in oxygen to introduce crosslinks or branched structures, polyarylene sulfide resins obtained by adding a small amount of a trihalogen or higher polyhalogen compound during polymerization to introduce a slight crosslink or branched structure, polyarylene sulfide resins in which a portion of the molecular chain and / or the terminals thereof have been modified with functional groups such as carboxyl groups, carboxy metal salts, alkyl groups, alkoxy groups, amino groups, and nitro groups, and polyarylene sulfide resins obtained by heat treatment in a non-oxidizing inert gas such as nitrogen. Mixtures of these polyarylene sulfide resins are also acceptable. Among these, polyarylene sulfide resins in which a portion of the molecular chain has been modified with amino groups are preferred, as they have excellent reactivity with reactive functional groups of thermoplastic elastomers and can more easily produce polyarylene sulfide resin compositions excellent in elongation, impact resistance, and other toughness properties. The polyarylene sulfide resin may be one in which impurities such as sodium atoms, polyarylene sulfide oligomers, table salt, and sodium salt of 4-(N-methyl-chlorophenylamino)butanoate have been reduced by acid washing, hot water washing, or washing with an organic solvent such as acetone or methyl alcohol.

[0015] Examples of the reactive functional group of the thermoplastic elastomer having a reactive functional group that constitutes the polyarylene sulfide resin composition include an epoxy group, a maleic anhydride group, a carboxylic acid group, an amino group, an isocyanate group, and the like. Examples of the thermoplastic elastomer having a reactive group include modified ethylene copolymers such as ethylene-α,β-unsaturated carboxylic acid alkyl ester-maleic anhydride copolymer, ethylene-α,β-unsaturated carboxylic acid glycidyl ester copolymer, ethylene-α,β-unsaturated carboxylic acid glycidyl ester-vinyl acetate copolymer, ethylene-α,β-unsaturated carboxylic acid glycidyl ester-α,β-unsaturated carboxylic acid alkyl ester copolymer, maleic anhydride graft-modified ethylene-α-olefin copolymer, and hydrogenated styrene-butadiene-styrene block copolymers grafted with maleic anhydride. Examples of suitable polyarylene sulfide resins include those modified with maleic anhydride or its derivatives, hydrogenated styrene-butadiene block copolymers modified with maleic anhydride or its derivatives, hydrogenated styrene-isoprene block copolymers modified with maleic anhydride or its derivatives, and hydrogenated styrene-isoprene-styrene block copolymers modified with maleic anhydride or its derivatives. Furthermore, as long as they have functional groups reactive with polyarylene sulfide resins, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, acrylonitrile-butadiene rubber-based thermoplastic elastomers, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, and the like can also be used. Among these, modified ethylene copolymers are preferred because they provide polyarylene sulfide resin compositions and gaskets for lithium ion batteries with particularly excellent toughness.

[0016] The amount of the thermoplastic elastomer having a reactive functional group is preferably 1 to 40 parts by weight, particularly 5 to 30 parts by weight, per 100 parts by weight of the polyarylene sulfide resin, since this allows for the production of a gasket for a lithium ion battery that has an excellent balance between toughness such as elongation and impact resistance and moldability. If the amount of the thermoplastic elastomer having a reactive functional group is less than 1 part by weight, the polyarylene sulfide resin composition will have poor toughness, resulting in poor sealing properties for the gasket. If the amount exceeds 40 parts by weight, the polyarylene sulfide resin composition will have poor flowability, making it difficult to mold into a gasket.

[0017] The polyarylene sulfide resin composition is prepared by mixing the polyarylene sulfide resin composition as (a) with D 50 The fine particles are added to a solvent in an amount 100 times the weight of the fine particles, stirred for 3 hours at a temperature range 5 to 15°C lower than the boiling point of the solvent, and then filtered through a 0.45 μm filter to separate the solid and liquid. The solution is then dried and solidified, and the amount of residue at this stage satisfies the requirement that the amount of residue is an amount equivalent to 40% by weight or less of the reactive thermoplastic elastomer (B) blended.

[0018] Here, D of the polyarylene sulfide resin composition fine particles 50 If D exceeds 100 μm, the solvent extraction of the thermoplastic elastomer component in the polyarylene sulfide resin composition fine particles becomes unstable. 50 The method for measuring the median particle diameter D of the polyarylene sulfide composition is not particularly limited, and for example, a known method such as a microscopic method, a sieving method, a sedimentation method, a light scattering method, an inertial method, or a diffusion method can be used. 50 The light scattering method is preferred because it allows accurate and easy measurement of D. In addition, when the polyarylene sulfide composition is in the form of a resin pellet or a molded article, the pellet or molded article is 50The method for obtaining fine particles having a particle size of 100 μm or less is not particularly limited, and any known method such as dry grinding, wet grinding, or low-temperature grinding can be used. As the grinder, a roller mill, jet mill, hammer mill, pin mill, rotary mill, vibration mill, planetary mill, attritor, bead mill, or the like can be used.

[0019] The solvent used in this case is not particularly limited as long as it dissolves the thermoplastic elastomer having a reactive functional group but does not dissolve the polyarylene sulfide resin, and examples of the solvent that can be used include toluene, xylene, dichlorobenzene, trichlorobenzene, and chloronaphthalene.

[0020] When the amount of the residue is an amount equivalent to 40% by weight or less of the thermoplastic elastomer (B) having reactive functional groups incorporated therein, i.e., the weight of the residue is divided by the weight of the fine particles of the polyarylene sulfide composition to determine the proportion of the residue, and this proportion is then divided by the constituent proportion of the thermoplastic elastomer in the polyarylene sulfide resin composition, such that the proportion of the residue relative to the proportion of the thermoplastic elastomer incorporated in the polyarylene sulfide composition is 40% by weight or less, the gasket will have excellent toughness, such as elongation and impact resistance. Here, if the proportion exceeds 40% by weight, the reactivity between the polyarylene sulfide resin and the thermoplastic elastomer having reactive functional groups will be insufficient, and the affinity and compatibility between the polyarylene sulfide resin and the thermoplastic elastomer having reactive functional groups will be poor, resulting in a gasket for a lithium ion battery with poor toughness and sealing properties. The polyarylene sulfide resin composition (b) has a flow length of 150 to 450 mm when injection molded into a spiral flow mold having a wall thickness of 1 mm and a width of 10 mm at an injection pressure of 100 MPa using an injection molding machine adjusted to a cylinder temperature of 310° C. and a mold temperature of 130° C. If the flow length is less than 150 mm, the polyarylene sulfide resin composition will have poor fluidity, and if it exceeds 450 mm, flash will be more likely to occur during molding and the toughness of the gasket will be poor.

[0021] The polyarylene sulfide resin composition constituting the lithium-ion battery gasket of the present invention may contain a non-fibrous filler within the scope of the present invention. Examples of non-fibrous fillers include silicates such as wollastonite, zeolite, sericite, kaolin, mica, pyrophyllite, talc, and alumina silicate; oxides such as aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, zinc oxide, and iron oxide; carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate and barium sulfate; nitrides such as silicon nitride, boron nitride, and aluminum nitride; glass flakes, and glass beads. Among these, mica, talc, calcium carbonate, glass flakes, and glass beads are preferred. The non-fibrous filler may also be surface-treated with an isocyanate compound, a silane coupling agent, a titanate coupling agent, an epoxy compound, or the like.

[0022] The polyarylene sulfide resin composition may also contain a mold release agent to improve mold releasability and appearance when forming a molded article. Suitable mold release agents include, for example, polyethylene wax, polypropylene wax, and fatty acid amide wax. Commonly available commercial products can be used as the polyethylene wax and polypropylene wax. The fatty acid amide wax is a polycondensate of a higher aliphatic monocarboxylic acid, a polybasic acid, and a diamine. Any wax within this category can be used, such as Light Amide WH-255 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), a polycondensate of stearic acid, sebacic acid, and ethylenediamine.

[0023] Furthermore, the polyarylene sulfide resin composition may contain a silane coupling agent consisting of a trialkoxysilane coupling agent having a glycidyl group and / or a trialkoxysilane coupling agent having an amino group, since this will result in excellent toughness, etc. In this case, the silane capping agent is not particularly limited as long as it is a trialkoxysilane coupling agent having a glycidyl group or an amino group, and specific examples belonging to this category include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. The amount of the silane coupling agent to be added is preferably 0.1 to 3 parts by weight based on 100 parts by weight of the polyarylene sulfide resin.

[0024] The polyarylene sulfide resin composition may be mixed with various additives within the scope of the present invention, and may contain one or more conventional additives such as conventionally known plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organic phosphorus compounds; antioxidants; heat stabilizers; ultraviolet inhibitors; and foaming agents. Furthermore, the polyarylene sulfide resin composition may be mixed with one or more thermoplastic resins such as various thermosetting resins; thermoplastic elastomers having no reactive functional groups, epoxy resins, cyanate ester resins, phenolic resins, polyimides, silicone resins, polyesters, polyamides, polyphenylene oxides, polycarbonates, polysulfones, polyetherimides, polyethersulfones, polyetherketones, polyetheretherketones, polyamideimides, and polyalkylene oxides.

[0025] The polyarylene sulfide resin composition can be produced by a conventionally used heat-melt kneading method. Examples include heat-melt kneading methods using a single-screw or twin-screw extruder, kneader, mill, Brabender, etc., with melt kneading methods using a twin-screw extruder being particularly preferred due to its excellent kneading capabilities. Furthermore, the screws used in the twin-screw extruder preferably have two or more kneading zones. Furthermore, in order to ensure a sufficient reaction time between the polyarylene sulfide resin and the thermoplastic elastomer having a reactive functional group, a polyarylene sulfide resin composition can be obtained that is capable of providing a gasket with excellent toughness, such as impact resistance, and excellent sealing properties. Therefore, the ratio of the screw length L to the screw diameter D (L / D) is preferably 30 or more, and particularly preferably 40 or more. In addition, in order to ensure a sufficient reaction between the polyarylene sulfide resin and the thermoplastic elastomer having a reactive functional group and to easily suppress thermal decomposition of the thermoplastic elastomer, it is preferable to set the cylinder temperature in the kneading zone of the extruder to 265 to 320° C., and particularly preferably to set it to 270 to 310° C. Furthermore, in order to improve the dispersibility and distribution of the thermoplastic elastomer phase having a reactive functional group in the polyarylene sulfide resin phase of the polyarylene sulfide resin composition, and as a result, to obtain a polyarylene sulfide resin composition that can provide a gasket having excellent toughness such as impact resistance and excellent sealing properties, the peripheral speed of the screw is preferably 50 to 400 mm / sec, and particularly preferably 150 to 300 mm / sec. The residence time of the molten resin in the extruder is preferably 30 to 100 seconds, particularly preferably 30 to 80 seconds, in order to ensure a sufficient reaction time between the polyarylene sulfide resin and the thermoplastic elastomer having a reactive functional group and to facilitate suppression of thermal decomposition of the thermoplastic elastomer.

[0026] The gasket for lithium ion batteries of the present invention can be obtained as an injection-molded article using an injection molding machine, and its shape is not particularly limited as long as it has the sealing function of a gasket. Furthermore, the shape of the lithium ion battery in which the gasket for lithium ion batteries of the present invention is used is not particularly limited, and batteries of various shapes, such as sheet-type, coin-type, cylindrical, and prismatic, can be used. The gasket for lithium ion batteries of the present invention can be used as a gasket for the electrodes of a lithium ion battery, as shown in FIG. 1, and can also be used to form a sealing plate for a lithium ion battery. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide a gasket for a lithium ion battery that is excellent in elongation, toughness such as resistance to cold and thermal shock, and sealing properties, and the industrial value thereof is extremely high. [Brief explanation of the drawings]

[0028] [Figure 1] ;An example of a gasket for a lithium-ion battery. [Figure 2] ;An example of a lithium ion battery container using a lithium ion battery gasket. [Example]

[0029] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0030] The polyarylene sulfide (A), thermoplastic elastomer (B), silane coupling agent (C), and release agent (D) used in the examples and comparative examples are shown below.

[0031] <Polyarylene sulfide (A)> Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-1)): melt viscosity 580 poise. Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-2)): melt viscosity 950 poise. Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-3)): melt viscosity 1420 poise. Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-4)): melt viscosity 2710 poise. Poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-5)): melt viscosity 90 poise.

[0032] <Thermoplastic elastomer (B)> Ethylene-α,β-unsaturated carboxylic acid alkyl ester-maleic anhydride copolymer (B-1) (hereinafter simply referred to as thermoplastic elastomer (B-1)); SK global chemical Co., Ltd., (trade name) Bondine AX8390, reactive group: maleic anhydride, ethylene residue unit: α,β-unsaturated carboxylic acid alkyl ester residue unit: maleic anhydride residue unit (weight ratio) = 69.7:29:1.3. Ethylene-α,β-unsaturated carboxylic acid glycidyl ester-α,β-unsaturated carboxylic acid methyl ester copolymer (B-2) (hereinafter simply referred to as thermoplastic elastomer (B-2)): manufactured by Sumitomo Chemical Co., Ltd., (trade name) Bondfast 7M, reactive group: epoxy group, ethylene residue unit: α,β-unsaturated carboxylic acid glycidyl ester residue unit: α,β-unsaturated carboxylic acid methyl ester residue unit (weight ratio) = 67:6:27. Ethylene-α,β-unsaturated carboxylic acid alkyl ester copolymer (B'-3) (hereinafter simply referred to as thermoplastic elastomer (B'-3)); SK global chemical Co., Ltd., (product name) LOTRYL 35BA40T, reactive group: none, ethylene residue unit: α,β-unsaturated carboxylic acid alkyl ester residue unit (weight ratio) = 65:35.

[0033] <Silane coupling agent (C)> Trialkoxysilane coupling agent having an amino group (C-1): KBM-903 (trade name), manufactured by Shin-Etsu Chemical Co., Ltd.; 3-aminopropyltrimethoxysilane. Trialkoxysilane coupling agent having a glycidyl group (C-2): Shin-Etsu Chemical Co., Ltd., (trade name) KBM-403; 3-glycidoxypropyltrimethoxysilane.

[0034] <Release agent (D)> Release agent (D-1): Kyoeisha Chemical Co., Ltd. (trade name) Light Amide WH-255.

[0035] Synthesis Example 1 A 50-liter autoclave equipped with a stirrer was charged with 6214 g of Na2S·2.9H2O and 17,000 g of N-methyl-2-pyrrolidone. The mixture was gradually heated to 205°C while stirring under a nitrogen stream, and 1,355 g of water was distilled off. After cooling the mixture to 140°C, 7,172 g of p-dichlorobenzene, 11 g of 3,5-dichloroaniline, and 5,000 g of N-methyl-2-pyrrolidone were added and sealed under a nitrogen stream. The mixture was heated to 225°C over 2 hours and polymerized at 225°C for 2 hours. The temperature was then raised to 250°C over 30 minutes and further polymerized at 250°C for 3 hours. After polymerization, the mixture was cooled to room temperature and the solids were isolated using a centrifuge. The solids were washed with hot water at 170°C and dried overnight at 100°C to obtain poly(p-phenylene sulfide).

[0036] The resulting poly(p-phenylene sulfide) was dried at 240°C for 4 hours under reduced pressure using a vacuum dryer to obtain a linear amino group-containing poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-1)). The melt viscosity of PPS (A-1) was 580 poise.

[0037] Synthesis Example 2 A 50-liter autoclave equipped with a stirrer was charged with 6214 g of Na2S·2.9H2O and 17,000 g of N-methyl-2-pyrrolidone. The mixture was gradually heated to 205°C while stirring under a nitrogen stream, and 1,355 g of water was distilled off. After cooling the mixture to 140°C, 7,188 g of p-dichlorobenzene, 5 g of 3,5-dichloroaniline, and 5,000 g of N-methyl-2-pyrrolidone were added and sealed under a nitrogen stream. The mixture was heated to 225°C over 2 hours and polymerized at 225°C for 2 hours, then heated to 250°C over 30 minutes and polymerized at 250°C for another 3 hours. After polymerization, the mixture was cooled to room temperature and the solids were isolated using a centrifuge. The solids were washed with hot water at 180°C and dried overnight at 100°C to obtain poly(p-phenylene sulfide).

[0038] The resulting poly(p-phenylene sulfide) was dried at 240°C for 6 hours under reduced pressure using a vacuum dryer to obtain linear amino group-containing poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-2)). The melt viscosity of PPS (A-2) was 950 poise.

[0039] Synthesis Example 3 Poly(p-phenylene sulfide) was obtained by the same polymerization method as in Synthesis Example 1, except that 3,5-dichloroaniline was not used.

[0040] The resulting poly(p-phenylene sulfide) was cured in an air atmosphere at 240°C for 2 hours to obtain branched poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-3)). The melt viscosity of PPS (A-3) was 1420 poise.

[0041] Synthesis Example 4 Poly(p-phenylene sulfide) was obtained by the same polymerization method as in Synthesis Example 2, except that 3,5-dichloroaniline was not used.

[0042] The resulting poly(p-phenylene sulfide) was cured in an air atmosphere at 245°C for 5 hours to obtain branched poly(p-phenylene sulfide) (hereinafter referred to as PPS (A-4)). The melt viscosity of PPS (A-4) was 2710 poise.

[0043] Synthesis Example 5 A 50-liter autoclave equipped with a stirrer was charged with 6214 g of Na2S·2.9H2O and 17,000 g of N-methyl-2-pyrrolidone. The mixture was gradually heated to 205°C while stirring under a nitrogen stream, and 1,355 g of water was distilled off. After cooling the mixture to 140°C, 7,150 g of p-dichlorobenzene and 5,000 g of N-methyl-2-pyrrolidone were added and sealed under a nitrogen stream. The mixture was heated to 225°C over 2 hours and polymerized at 225°C for 2 hours. The mixture was then heated to 250°C over 30 minutes and polymerized at 250°C for another 2 hours. After polymerization, the mixture was cooled to room temperature and the solids were isolated by centrifugation. The solid content was washed with hot water at 220°C and dried at 100°C for 24 hours to obtain poly(p-phenylene sulfide) (hereinafter referred to as PPS (A3-1)).

[0044] This PPS (A3-1) was dried at 240°C for 6 hours under reduced pressure using a vacuum dryer to obtain linear poly(p-phenylene sulfide) (hereinafter referred to as PPS (A3-2)). The melt viscosity of PPS (A3-2) was 90 poise.

[0045] The evaluation and measurement methods for the obtained polyarylene sulfide resin are shown below.

[0046] ~Melt viscosity measurement of polyarylene sulfide resin~ The melt viscosity was measured using a high-performance flow tester (Shimadzu Corporation, product name CFT-500) equipped with a die having a diameter of 1 mm and a length of 2 mm, under the conditions of a measurement temperature of 315°C and a load of 10 kg.

[0047] ~D 50 Measurement of The pellets of the polyarylene sulfide resin composition obtained in the examples and comparative examples were cooled with liquid nitrogen and mechanically pulverized to obtain fine particles of the polyarylene sulfide resin composition. The D 50 Measurements were carried out.

[0048] ~Proportion of Residues Ratio to the Proportion of Thermoplastic Elastomer Blended in Polyarylene Sulfide Resin Composition~ The polyarylene sulfide composition pellets obtained in the examples and comparative examples were cooled using liquid nitrogen and mechanically pulverized to obtain 3 g of fine particles of the polyarylene sulfide composition. 3 g of the fine particles was immersed in a glass container containing 300 g of toluene (boiling point 110 ° C) and stirred at 100 ° C for 3 hours. The filtrate was then filtered through a 0.45 μm filter, and the filtrate was evaporated to dryness to recover the residue, which was then weighed. The weight was then divided by the weight (3 g) of the obtained polyarylene sulfide composition fine particles to determine the proportion of the residue. The proportion of the residue was then divided by the proportion of the thermoplastic elastomer in the polyarylene sulfide resin composition to determine the proportion of the residue relative to the proportion of the thermoplastic elastomer blended in the polyarylene sulfide composition.

[0049] ~Evaluation of the fluidity of polyarylene sulfide resin compositions~ The obtained polyarylene sulfide resin composition was injection molded into a spiral flow mold having a wall thickness of 1 mm and a width of 10 mm at an injection pressure of 100 MPa using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name SE-75S) adjusted to a cylinder temperature of 310°C and a mold temperature of 130°C. The fluidity was judged from the flow length when the molded product had a flow length of 150 mm or more, which was considered to have excellent fluidity.

[0050] ~Evaluation of tensile elongation at break~ Test pieces were prepared using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name SE-75S), and measurements were carried out using a tensile testing machine (manufactured by Shimadzu Corporation, product name Autograph AG-5000B) in accordance with ISO 527-1, 2. Pieces with a tensile elongation of 8% or more were considered to have excellent tensile elongation.

[0051] ~Evaluation of sealing performance as a gasket~ An electrolyte (Kishida Chemical, product name LBG-96533 (a 1:1 mixed solvent of ethylene carbonate and dimethyl carbonate with 1 mol% / L of lithium hexafluorophosphate added) was placed in an open-topped aluminum container. A lithium-ion battery gasket injection-molded from the polyarylene sulfide resin composition shown in FIG. 1 was attached to a sealing plate, and the sealing plate was welded to the aluminum container to seal it, producing a lithium-ion battery container shown in FIG. 2. The lithium-ion battery container was subjected to 1,000 thermal cycles, each cycle consisting of holding at 90°C for 30 minutes and then at -40°C for 30 minutes, and the interface between the metal terminal and the gasket was immersed in the test liquid. The pressure inside the lithium-ion battery container was increased to 0.2 MPa and maintained for 1 minute, and the sealing property was evaluated. ◯: When no bubbles were generated from the interface immersed in the test liquid, it was determined that the gasket had excellent sealing properties. ×: When bubbles were generated from the interface immersed in the test liquid, it was judged that the sealing property as a gasket was poor.

[0052] Example 1 100 parts by weight of the PPS (A-1) obtained in Synthesis Example 1 and 9 parts by weight of thermoplastic elastomer (B-1) were uniformly mixed in advance and charged into the hopper of a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., product name TEX-25αIII, L / D = 55) having four kneading zones. The kneading zone cylinder temperature was heated to 285°C, and the mixture was melt-kneaded at a raw material feed rate of 25 kg / hr and a screw rotation speed of 200 rpm (circumferential speed: 258 mm / sec). The molten composition flowing out of the die after a residence time of 50 seconds was cooled and then cut to produce a pellet-shaped polyarylene sulfide resin composition. The polyarylene sulfide resin composition at this time consisted of 92% by weight of PPS (A-2) and 8% by weight of thermoplastic elastomer (B-1), and the flow length of the polyarylene sulfide resin composition was 306 mm.

[0053] The polyarylene sulfide resin composition pellets were mechanically crushed under the above conditions to obtain D 50 The polyarylene sulfide resin composition particles were used to evaporate the filtrate to dryness, and the weight of the recovered residue was measured. The weight was 0.072 g (corresponding to 30 wt % of the thermoplastic elastomer (B-1)).

[0054] The polyarylene sulfide resin composition was then injection molded using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., product name: SE75S) set at a cylinder temperature of 300°C and a mold temperature of 140°C to produce a gasket for a lithium ion battery having the shape shown in Figure 1. Next, the resulting gasket was used to produce a container for a lithium ion battery shown in Figure 2, and the sealing property was evaluated, revealing that the sealing property was good.

[0055] Examples 2 to 8 Pellet-shaped polyarylene sulfide resin compositions were prepared in the same manner as in Example 1, with the blending ratios of polyarylene sulfide (A), thermoplastic elastomer (B), silane coupling agent (C), and release agent (D) and the melt-kneading conditions shown in Table 1. The polyarylene sulfide resin composition pellets were mechanically pulverized to obtain fine particles of the polyarylene sulfide resin composition. 50 All of the thicknesses were 100 μm or less. Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0056] The proportion of residue in all of the obtained polyarylene sulfide resin compositions was 40% by weight or less, and the compositions were excellent in flowability, elongation, and sealing properties as gaskets for lithium ion batteries.

[0057] [Table 1]

[0058] Comparative Examples 1 to 8 A pellet-shaped polyarylene sulfide resin composition was prepared in the same manner as in Example 1, with the blending ratios of polyarylene sulfide (A), thermoplastic elastomer (B), and silane coupling agent (C) and the melt-kneading conditions set forth in Table 2. The median diameter D of the fine particles of the polyarylene sulfide resin composition obtained by mechanically pulverizing the polyarylene sulfide resin composition pellets was 50 All of the thicknesses were 100 μm or less. Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.

[0059] The polyarylene sulfide resin compositions obtained in Comparative Examples 1, 2, 3, and 6 had residue ratios exceeding 40% by weight and were poor in elongation and sealing properties as gaskets. The polyarylene sulfide resin compositions obtained in Comparative Examples 4 and 7 were poor in fluidity and sealing properties as gaskets, and the polyarylene sulfide resin compositions obtained in Comparative Examples 5 and 8 were poor in elongation and sealing properties as gaskets.

[0060] [Table 2] [Industrial Applicability]

[0061] The present invention relates to a gasket for lithium ion batteries that has excellent toughness such as elongation and impact resistance, and also has excellent sealing properties. [Explanation of symbols]

[0062] 1; Sealing board. 2. Aluminum container. 3;Gasket for lithium-ion batteries. 4; Metal terminal.

Claims

1. An electrolyte-resistant gasket for a lithium ion battery, characterized in that it is an injection-molded article of a polyarylene sulfide resin composition comprising 100 parts by weight of a polyarylene sulfide resin (A) and 1 to 40 parts by weight of a thermoplastic elastomer (B) having a reactive functional group, and the polyarylene sulfide resin composition satisfies the following (a) and (b): (a): The polyarylene sulfide resin composition is subjected to a median diameter (D ５０ ) fine particles of 100 μm or less, the fine particles are added to a solvent in an amount 100 times the weight of the fine particles, and the mixture is stirred for 3 hours at a temperature range 5 to 15° C. lower than the boiling point of the solvent. Subsequently, the mixture is filtered through a 0.45 μm filter to separate the solid and liquid, and the resulting solution is dried to a solid. The amount of the residue at this stage is an amount equivalent to 40% by weight or less of the thermoplastic elastomer (B) blended in the polyarylene sulfide resin composition, and the solvent is selected from toluene, xylene, dichlorobenzene, trichlorobenzene, and chloronaphthalene. (b) When injection-molded into a spiral flow mold having a wall thickness of 1 mm and a width of 10 mm at an injection pressure of 100 MPa using an injection molding machine adjusted to a cylinder temperature of 310°C and a mold temperature of 130°C, the flow length is 150 to 450 mm.

2. 2. The electrolyte-resistant gasket for a lithium ion battery according to claim 1, wherein the thermoplastic elastomer (B) having a reactive functional group is a thermoplastic elastomer having at least one reactive functional group selected from the group consisting of an epoxy group, a maleic anhydride group, a carboxylic acid group, an amino group, and an isocyanate group.

3. 3. The electrolyte-resistant gasket for a lithium ion battery according to claim 1, wherein the thermoplastic elastomer (B) having a reactive functional group is a modified ethylene copolymer having a maleic anhydride group and / or a modified product of maleic anhydride or a derivative thereof, which is a hydrogenated product of a vinyl aromatic compound block copolymer.

4. The electrolyte-resistant gasket for a lithium ion battery according to any one of claims 1 to 3, further comprising a silane coupling agent (C) comprising a trialkoxysilane coupling agent having a glycidoxy group and / or a trialkoxysilane coupling agent having an amino group.

5. The electrolyte-resistant gasket for a lithium ion battery according to any one of claims 1 to 4, further comprising at least one release agent (D) selected from the group consisting of polyethylene wax, polypropylene wax, and fatty acid amide wax.

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