JP2005078890A - Polyamide resin composition for battery gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for a battery gasket made of polyamide resin improved in resistance to humidity and heat to enhance the endurance of a battery gasket against liquid leakage with little smear on a metal mold causing a defect at the time of molding. <P>SOLUTION: This polyamide resin composition for the battery gasket excellent in resistance to humidity and heat with little smear on a metal mold contains 0.001 to 0.1 wt.pts. of antioxidant (B) per 100 wt.pts. of polyamide (A). The antioxidant (B) is hindered phenolic antioxidant and the battery including the battery gasket uses an alkaline solution as an electrolyte. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gasket material used for a battery.

  The battery gasket is used to keep the battery airtight, liquid-tight, and insulation between the positive and negative electrodes, and plays a very important role in terms of performance and safety. Properties required for battery gasket materials include mechanical strength, heat resistance, heat and humidity resistance, creep resistance, chemical resistance, and the like, and polyamides that are excellent in balance are mainly used.

Various studies have been made to satisfy these requirements. For example, Patent Documents 1 to 3 disclose that a polyamide resin is used for a battery gasket (gasket) to keep the battery airtight, liquid-tight, and electrode insulation.
JP-A-8-162128 (page 1-3) JP-A-5-325925 (page 1-3) JP-A-9-27305 (page 1-3)

  However, due to improvement in battery performance and diversification of usage environments, requirements and performance required for gasket materials also increase, and current materials such as those described in Patent Documents 1 and 2 may be insufficient. . For example, the alkali resistance and heat-and-moisture resistance of polyamide resins do not always satisfy the required characteristics of the gasket, and embrittlement occurs at high temperatures and long-term wet heat, and liquid leakage due to gasket cracks may occur. Sex is considered enough.

  Further, since the battery gasket molded product is small and has a unique shape having a thin portion of 0.5 mm or less, molding defects such as filling failure and deformation are likely to occur due to contamination of the mold. Patent Document 3 describes that an antioxidant can be added to polyamide, but there is no mention of a specific addition amount, and according to studies by the present inventors, depending on the addition amount, a mold is used. As a result, it has been found that there is a possibility that it may become dirty and cause molding defects, and a practical gasket may not be obtained.

  The object of the present invention is to solve the above-mentioned problems, and to make a battery gasket made of a polyamide resin that has less mold contamination due to molding defects during molding, improves moisture and heat resistance, and increases the durability of the gasket against liquid leakage It is to provide materials for use.

As a result of intensive studies to solve the above problems, the present inventors have included an antioxidant in an extremely limited amount of 0.001 to 0.1 parts by weight with respect to 100 parts by weight of polyamide. The inventors have found that the problems of the present invention can be solved by significantly improving the moisture and heat resistance of the molded product while suppressing contamination of the mold during molding.
That is, the present invention
(1) (A) Polyamide resin composition for battery gasket characterized by containing 0.001 to 0.1 parts by weight of (B) antioxidant with respect to 100 parts by weight of polyamide,
(2) The polyamide resin composition for battery gaskets according to (1) above, wherein (B) the antioxidant is a hindered phenol-based antioxidant,
(3) The polyamide resin composition for battery gaskets according to (1) or (2) above, which is a battery gasket using an alkaline solution as an electrolytic solution.

  According to the present invention, there is provided a polyamide resin composition for a battery gasket that is less contaminated with a mold during molding and excellent in heat and moisture resistance.

  Next, the present invention will be described more specifically.

  The (A) polyamide resin used in the present invention is a resin mainly composed of amino acid, lactam or diamine and dicarboxylic acid. Representative examples of the raw materials include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid, lactams such as ε-caprolactam and ω-laurolactam, tetramethylenediamine, hexa Methylenediamine, nonamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, (2,2,4- or 2,4,4-) trimethylhexamethylenediamine, 5-methylnonamethylenediamine, Metaxylylenediamine, paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, Bis (4-aminosi Chlohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethylpiperazine, aliphatic, alicyclic, aromatic Diamines, and adipic acid, speric acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid Examples thereof include aliphatic, alicyclic and aromatic dicarboxylic acids such as acid, hexahydroterephthalic acid and hexahydroisophthalic acid. In the present invention, polyamide homopolymers or copolymers derived from these raw materials are used alone or It can be used in the form of a mixture.

  In the present invention, a polyamide resin particularly preferably used is a polyamide resin having a melting point of 200 ° C. or higher and excellent in heat resistance and strength. Specific examples include polycaproamide (nylon 6), polyhexamethylene azide. Pamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyhexamethylene terephthalamide (nylon 6T), poly Nonamethylene terephthalamide (nylon 9T), polyhexamethylene isophthalamide (nylon 6I), polyxylylene adipamide (nylon XD6), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6/66), polyhexa Methylene terephthalate Amide / polycaproamide copolymer (nylon 6T / 6), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), Polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene adipamide / polyhexamethylene isophthalamide / polycaproamide copolymer (nylon 66 / 6I / 6), polyhexamethylene azide Pamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide Copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / poly (2-methylpentamethylene) terephthalamide copolymer (nylon 6T / M5T), polyhexamethylene terephthalamide / polyhexamethylene sebacamide / polycaproamide copolymer (Nylon 6T / 610/6), polyhexamethylene terephthalamide / polydodecanamide / polyhexamethylene adipamide copolymer (nylon 6T / 12/66), polyhexamethylene terephthalamide / polydodecanamide / polyhexamethylene isophthalamide Examples thereof include copolymers (nylon 6T / 12 / 6I), and mixtures or copolymers thereof.

  Particularly preferred are nylon 6, nylon 66, nylon 610, nylon 6/66 copolymer and nylon 66 / 6I / 6 copolymer, and nylon 6T / 66 copolymer, nylon 6T / 6I copolymer, nylon 6T / 6 copolymer, nylon 6T. / 12 copolymer, nylon 6T / 12/66 copolymer, nylon 6T / 12 / 6I copolymer and the like, and at least one polyamide selected from copolymers having hexamethyl terephthalamide units. These polyamide resins are also practically suitable for use as a mixture depending on required properties such as moldability, heat resistance, toughness, and surface properties.

  The degree of polymerization of the polyamide resin is not particularly limited, but the relative viscosity measured at 25 ° C. using an Ostwald viscometer in a 98% concentrated sulfuric acid solution of 1% by weight of the polyamide resin is in the range of 1.9 to 4.0. The thing of the range of 2.0-3.5 is especially preferable. When the relative viscosity is within this range, the moldability and mechanical properties are excellent, which is suitable for the present invention.

  Examples of the (B) antioxidant used in the present invention include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like, and these can be used in combination. In the present invention, among the above, hindered phenol antioxidants are preferable. Further, a hindered phenol antioxidant and a phosphorus antioxidant or sulfur antioxidant can be used in combination.

  Examples of the hindered phenol antioxidant used in the present invention include 1,1,3-tris (2-methyl-1-hydroxy-5-tert-butylphenyl) butane and tetrakis (2,4-di-tert-butyl). Phenyl) 4,4′-biphenylene-diphosphonate, bis- [3,3-bis- (4′-hydroxy-3′-tert-butylphenyl) -butanoic acid] -glycol ester, 3, 9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5 , 5] undecane, 2,2′-methylenebis (6-tert-butyl-4-methylphenol), triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxy) Enyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- ( 4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), isooctyl-3- (3,5-di-t- Til-4-hydroxyphenyl) propionate, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5- Di-t-butyl-4-hydroxybenzyl) benzene, bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium, 2,4-bis [(octylthio) methyl] -O-cresol , Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine , Triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanedio Ru-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is preferably used, but in particular 3,9-bis {2- [3- (3-t-butyl-4 -Hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane, pentaerythrityl-tetrakis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), triethylene glycol-bis [ 3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxy) Rokishifeniru) propionate] is preferred.

  Examples of phosphorus antioxidants used in the present invention include trisnonylphenel phosphite, tris (2,4-di-t-butylphenyl) phosphite, bis (nonylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite. Phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol phosphite, 2,2-methylenebis (4 , 6-Di-t-butylphenyl) octyl phosphite, tetrakis (2,4-di-butylphenyl) -4,4′-biphenylene-di-phosphonite-2,4,8,10-tetraoxa-3,9 -Didiphosphaspiro [5,5] undecane is preferably used, (2,6, di -t- butyl-4-methylphenyl) pentaerythritol diphosphite, 2,4,8,10-tetraoxa-3,9 Zizi phosphatonin spiro [5,5] undecane is preferred.

  As the sulfur-based antioxidant used in the present invention, distearyl 3,3′-thiodipropionate, pentaerythrityltetrakis (3-laurylthiopropionate), 2-mercaptobenzimidazole, didodecyl 3,3′- Thiodipropionate, dioctadecyl 3,3′-thiodipropionate, ditridecyl 3,4′-thiodipropionate, 2,2-bis [[3- (dodecylthio) -1-oxopropoxy] methyl] -1 , 3-propanediyl ester is preferably used, and distearyl 3,3′-thiodipropionate and pentaerythrityltetrakis (3-laurylthiopropionate) are particularly preferable.

  The addition amount of the antioxidant is 0.001 to 0.1 parts by weight, preferably 0.001 to 0.05 parts by weight, with respect to 100 parts by weight of the polyamide resin. When the addition amount is less than 0.001 part by weight, the effect of improving the heat and moisture resistance is small, and when it exceeds 0.1 part by weight, the mold is likely to become dirty during molding, and molding defects are likely to occur, which is not preferable.

  In addition, although there is no restriction | limiting in particular in the mixture ratio in the case of using together 2 or more types of antioxidant, For example, when mix | blending a hindered phenolic antioxidant and another antioxidant, hindered phenol type with respect to the sum total of both The proportion of the antioxidant is preferably 100 to 30% by weight, and more preferably 100 to 50% by weight.

  The polyamide resin composition used in the present invention contains other components within the range not impairing the effects of the present invention, such as crystal nucleating agents (inorganic fine particles such as talc, silica and graphite, metal oxides such as magnesium oxide and aluminum oxide, caprolactam Polyamide oligomers such as dimers, weathering agents (resorcinol, salicylate, benzotriazole, benzophenone, hindered amine, etc.), mold release agents and lubricants (montanic acid and its metal salts, esters, half esters, stearyl) Alcohol, stearamide, various bisamides, bisureas, polyethylene waxes, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, metallic pigments, etc.), dyes (such as nigrosine), plasticizers (octyl p-oxybenzoate, N-butylbenzene) The Honamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agents Agent), flame retardant (eg, red phosphorus, melamine cyanurate, magnesium hydroxide, aluminum hydroxide, hydroxide, ammonium polyphosphate, brominated polystyrene, brominated PPO, brominated PC, brominated epoxy resin or Combinations of these brominated flame retardants and antimony trioxide, etc.) and other polymers (polyester, polycarbonate, polyphenylene ether, polyphenylene sulfide, polyether sulfone, ABS resin, SAN resin, polystyrene, acrylic resin, polyethylene, polypropylene) It can be added SBS, SEBS, various elastomers, etc.).

  The method for obtaining the polyamide resin composition used in the present invention is not particularly limited, and is a dry blend of polyamide resin and antioxidant, a method of adding an antioxidant during polyamide polymerization, and a polyamide resin and an antioxidant are melt-kneaded. The obtaining method is preferred.

  The method of adding an antioxidant during the above-mentioned polyamide polymerization includes the method of simultaneously charging the raw material at the initial stage of the heat treatment of the polyamide prepolymer, the method of adding in the middle of the heat treatment, the method of adding after the heat treatment and before charging the atmospheric pressure polymerization apparatus There are no particular restrictions. The antioxidant may be added as it is, or may be added after being dissolved in a small amount of solvent.

  Moreover, there is no restriction | limiting in particular in the method of melt-kneading a polyamide resin and antioxidant, What is necessary is just to be able to perform mechanical shearing in the molten state of a polyamide resin. The treatment method may be either a batch type or a continuous type, but a continuous type capable of continuous production is preferred from the viewpoint of work efficiency. Although there is no restriction | limiting also in a concrete kneading apparatus, An extruder, especially a twin-screw extruder are preferable in terms of productivity. It is also preferred to provide a vent port for the purpose of removing moisture generated during melt kneading and low molecular weight volatile components. The supply method is not particularly limited, but when a twin screw extruder is used, (A) a polyamide resin and (B) an antioxidant are mixed in advance with a blender or the like, and the mixture is fed from a feed port of the extruder. A feeding method is preferred.

  The gasket material of the present invention can be obtained by molding by a generally known plastic molding method such as press molding, injection molding, extrusion molding or blow molding.

  Since the polyamide resin composition of the present invention is particularly excellent in moisture and heat resistance, primary batteries such as nickel manganese batteries, silver oxide batteries, alkaline button batteries, zinc-air batteries, alkaline batteries, manganese dry batteries, nickel hydrogen batteries, nickel cadmium batteries The battery gasket using an alkaline solution as an electrolyte solution such as a secondary battery, etc. exhibits extremely excellent performance.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by a following example.

Evaluation method (1) General mechanical property It measured according to the following standard methods.

Tensile strength, tensile elongation It was performed according to ASTM D638. A No. 4 dumbbell-shaped test piece (test piece thickness: 1/16 inch (1.6 mm)) was used, and the test was performed at a test speed of 50 mm / min.

Bending strength and flexural modulus were performed in accordance with ASTM D790. The test was conducted at a test speed of 1 mm / min using a bending test piece (test piece thickness: 1/8 inch (3.2 mm)).

Izod impact strength It was performed in accordance with ASTM D256. The test was conducted using an impact test piece (test piece thickness: 1/8 inch (3.2 mm), mold notch).

(2) Moisture and heat resistance Measured according to ASTM D638. A No. 4 dumbbell-shaped test piece (test piece thickness: 1/16 inch (1.6 mm)) was treated at 80 ° C. and 95% RH for 500 hours, and evaluated for tensile properties and surface appearance.

(3) Alkali resistance It carried out based on ASTM D638. A No. 4 dumbbell-shaped test piece (test piece thickness: 1/16 inch (1.6 mm)) was immersed in a 10 wt% potassium hydroxide aqueous solution at 80 ° C. for 500 hours, and evaluated for tensile properties and surface appearance.

(4) Gasket durability 10 wt% potassium hydroxide aqueous solution was put into a stainless steel cylindrical container (diameter 10 mm, height 50 mm) with one side closed, and the lid shape of the polyamide resin composition obtained in the examples and reference examples A liquid leak test sample (simulated battery) sealed with a molded product (a gasket model molded product, a cylinder having a diameter of 10 mm, a height of 5 mm, and a thickness of 0.5 mm) is prepared. This was treated for 250 hours under dry heat at 80 ° C., and the liquid leakage was confirmed.

(5) Mold fouling property For strip-shaped products (12.7 mm x 2.4 mm x 0.4 mm), injection molding was performed at a cylinder temperature of 280 ° C and a mold temperature of 80 ° C, and the mold surface after 1000 shot molding was observed. Then, the degree of contamination was observed.

Judgment criteria
○: No dirt at all Δ: Slightly dirty ×: Evaluated as having large dirt.

[Reference Example 1]
Nylon 66
An equimolar salt of hexamethylenediamine and adipic acid was added, pure water having the same weight as all the raw materials added was added, the inside of the polymerization vessel was sufficiently purged with nitrogen, and heating was started while stirring. The final temperature was 270 ° C. while the can internal pressure was adjusted to 2 MPa at the maximum. The polymerization time was adjusted so as to achieve the target relative viscosity, and the molten polymer was discharged into a water bath and pelletized with a strand cutter. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours.

  The relative viscosity was measured at 25 ° C. using an Ostwald viscometer in a 98% concentrated sulfuric acid solution containing 1% by weight of polyamide resin.

[Reference Example 2]
Nylon 6
ε-Caproamide was added, pure water having the same weight as all the charged raw materials was added, the inside of the polymerization can was sufficiently purged with nitrogen, and heating was started while stirring. The final temperature was 270 ° C. while the can internal pressure was adjusted to 2 MPa at the maximum. The polymerization time was adjusted so as to achieve the target relative viscosity, and the molten polymer was discharged into a water bath and pelletized with a strand cutter. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours.

[Reference Example 3]
Nylon 66/6
Hexamethylenediamine, equimolar salt of adipic acid, and ε-caproamide were added at a weight ratio of 90:10, and pure water of the same weight as all of the charged raw materials was added. Heating was started. The final temperature was 270 ° C. while adjusting the can internal pressure to 2 MPa at the maximum. The polymerization time was adjusted so as to achieve the desired relative viscosity, and the molten polymer was discharged into a water bath and pelletized with a strand cutter. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours.

[Examples 1-14, Comparative Examples 1-2]
Each material obtained in Reference Examples 1 to 3 was dry blended in the proportions shown in Tables 1 and 2, and a test piece was injection molded at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C. with a Nissei Plastic Industrial Injection Molding Machine PS60E9ASE. Each characteristic was evaluated.

[Example 15]
Nylon 66 (ηr = 2.9) and the following IR1098 were blended at a weight ratio of 100: 0.05, respectively, and melt-kneaded at 290 ° C. using a twin screw extruder TEX-44 manufactured by Nippon Steel Works. The molten polymer was discharged into a water bath and pelletized with a strand cutter. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours. Using the dried pellets, test specimens were injection molded at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C. with a Nissei Plastic Industrial Injection Molding Machine PS60E9ASE, and each characteristic evaluation was performed.

[Example 16]
Pellets were obtained in the same manner as in Reference Example 1 except that IR1098 was further added to an equimolar salt of hexamethylenediamine and adipic acid in a weight ratio of 100: 0.1. The test piece was injection molded at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C. with a Nissei Plastic Industrial Injection Molding Machine PS60E9ASE, and each characteristic evaluation was performed.

Hindered phenol antioxidant IR1098: N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide) (Irganox 1098: manufactured by Ciba Specialty Chemicals)
GA-80: 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10 -Tetraoxaspiro [5,5] undecane (Sumilizer GA-80: manufactured by Sumitomo Chemical Co., Ltd.)
Phosphorus antioxidant PEP36: bis (2,6, di-t-butyl-4-methylphenyl) pentaerythritol phosphite (Asahi Denka Kogyo Co., Ltd.)
Sulfur-based antioxidant TP-D: pentaerythrityl tetrakis (3-lauryl thiopropionate) (Sumilizer TP-D: manufactured by Sumitomo Chemical Co., Ltd.)

Claims (3)

(A) 0.001 to 0.1 part by weight of (B) antioxidant is contained with respect to 100 parts by weight of polyamide, and a polyamide resin composition for battery gaskets. The polyamide resin composition for a battery gasket according to claim 1, wherein the antioxidant (B) is a hindered phenol-based antioxidant. The polyamide resin composition for a battery gasket according to claim 1 or 2, which is a battery gasket using an alkaline solution as an electrolytic solution.