JPH0982294A - Battery housing case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case having a high electrolyte resistant characteristic, ensuring a good balance between moldability and heat resistance, and further having good appearance by forming the case out of polyphenylene ether resin composition containing the prescribed amount of polyolefine. SOLUTION: A battery case used for housing at least one organic electrolyte battery is formed out of polyphenylene ether resin composition. The composition in this case is made to contain an amount of polyolefine between 0.1wt.% and 4.0wt.%. As a result, the organic electrolyte resistant characteristic of the battery housing case is further improved. Also, the battery housing case comes to have a good balance between thin-walled moldability and heat resistance, good appearance and high flame resistance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a battery case for accommodating an organic electrolyte battery. More specifically, the present invention relates to a battery case made of a polyphenylene ether resin composition, which has a good fluidity and a good appearance.

[0002]

2. Description of the Related Art As a typical example of an organic electrolyte battery, there is a lithium ion battery which is currently receiving attention. A lithium-ion battery is a secondary battery that uses an electrolytic solution composed of an organic solvent and a solute, in which the negative electrode is made of specific carbon such as coke, graphite, or polyacene, and the positive electrode is made of a light metal oxide such as lithium cobalt oxide, lithium nickel oxide, or lithium manganate. Is. This lithium-ion battery has a high energy density that other batteries do not have, and is characterized by low self-discharge.

Recently, in order to meet the contradictory requirements of downsizing and weight saving and extension of device driving time, at least one lithium ion battery to be housed is housed in a case, and a battery pack connected in series is used for a wireless device, a mobile phone, a video device. It is widely used as a backup power source for portable devices such as cameras and personal computers and word processors. Recently, as the battery technology has advanced, the battery design may be performed at a high temperature setting of about 100 ° C., and the case itself that houses the battery is required to have heat resistance. ing.

Conventionally, the material of the case for accommodating the battery is, for example, rubber-modified styrene-acrylonitrile copolymer (hereinafter ABS), polycarbonate (hereinafter PC), PC.
/ ABS is used. ABS has a heat distortion temperature (HDT: ASTM-D648) of about 90 ° C., and there is concern about its heat resistance from the maximum temperature during battery use.

Although the heat distortion temperature of PC and PC / ABS is 100 ° C. or higher, there is a problem with the organic electrolytic solution resistance property, so when the organic electrolytic solution leaks from the battery to the battery pack, the portion in contact with the electrolytic solution is It causes problems such as swelling, dissolution, and cracks, and adversely affects peripheral equipment. The same applies to ABS. A battery pack including a battery case made of styrene-modified polyphenylene oxide is disclosed in Japanese Patent Publication No. 6-82547. Further, styrene-modified polyphenylene oxide (hereinafter referred to as modified polyphenylene ether in the present invention) has no problem with respect to heat resistance, and also with respect to organic electrolyte resistance characteristics, other resin materials such as ABS, PC, PC / ABS, etc. It is disclosed that it is more stable than.

However, in recent years, the battery case itself has become thinner due to the demands for smaller size and lighter weight of the battery pack itself and for cost reduction, and thin wall formability of the material itself has been required. In many cases, the battery case itself is installed outside the device, and its appearance is becoming an important characteristic. The modified polyphenylene ether resin, the organic electrolyte resistance characteristics, heat resistance is almost no problem, thin-wall moldability, it is necessary to improve the appearance characteristics, further impart flame retardancy while maintaining these characteristics. Is required.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to improve the organic electrolyte resistance property from the conventional one, and to have a good balance of thin-wall moldability and heat resistance and an excellent appearance, and a battery having excellent flame retardancy. To provide the case.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a battery case made of a polyphenylene ether resin composition containing a specific amount of polyolefin has a conventional case. As a result, they have found that they are superior in organic electrolytic solution resistance, superior in heat resistance and thin-wall moldability, excellent in appearance and flame retardancy as compared with those of the present invention, and completed the present invention.

That is, according to the present invention, in a battery case accommodating at least one organic electrolyte battery, the battery case is made of a polyphenylene ether resin composition, and the resin composition is 0.1 to 40% by weight of polyolefin. A battery case, characterized by containing. Less than,
The present invention will be described in detail.

The battery case of the present invention is a resin composition obtained by mixing a polyolefin and a compatibilizing agent in a resin composition containing a polyphenylene ether resin and a polystyrene resin as main components, wherein It is a molded product using a resin composition containing 40% by weight. It does not impair the characteristics of conventional polyphenylene ether-based resins, and has organic electrolyte resistance characteristics, thin-wall moldability, appearance characteristics, and, if necessary, flame retardancy. It also has excellent characteristics.

The polyphenylene ether resin (hereinafter referred to as PPE resin) used in the present invention comprises a constitutional unit represented by the following general formula 1, and has a reduced viscosity (0.5 g / dl, chloroform solution, measured at 30 ° C.) of 0.15. It is preferably a homopolymer and / or a copolymer in the range of 0.20 to 0.60.

[0012]

Embedded image

(R1, R2, R3 and R4 are respectively
Hydrogen, a halogen, a primary or secondary lower alkyl group having 1 to 7 carbon atoms, a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbon oxy group or at least two carbon atoms each being a halogen atom and an oxygen atom. It is selected from the group consisting of separated halohydrocarbonoxy groups and may be the same or different from each other. ) Specific examples of this PPE resin include, for example, poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), poly (2- Methyl-6-phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4)
-Phenylene ether) and the like, and further 2,6-dimethylphenol and other phenols (for example, 2,
Also included are polyphenylene ether copolymers such as polymers with 3,6, -trimethylphenol and 2-methyl-6-butylphenol). Among them, poly (2,6-
Dimethyl-1,4-phenylene ether), a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol is preferable, and poly (2,6-dimethyl-
1,4-phenylene ether) is more preferable.

The method for producing the PPE resin used in the present invention is as follows:
The method is not particularly limited, and known methods such as US Pat. No. 3,306,874 and US Pat.
No. 875, U.S. Pat. No. 3,257,357,
U.S. Pat. No. 3,257,358, JP-B-52-17
The methods described in JP-A-8802628, JP-A-50-51197, JP-A-63-152628 and the like can be mentioned.

The PPE resin used in the present invention is, in addition to the above-mentioned PPE resin, a PPE resin and an α, β-unsaturated carboxylic acid or its derivative melted in the presence or absence of a radical generator. 8 in state, dissolved state, and slurry state
It may be a modified PPE resin (0.01 to 10% by weight is grafted or added) obtained by reacting at a temperature of 0 to 350 ° C., and further at an arbitrary ratio of the PPE resin and the modified PPE resin described above. It may be a mixture of.

The polystyrene resin (hereinafter referred to as PS resin) used in the present invention is generally a vinyl aromatic polymer,
It refers to a rubber-modified aromatic polymer. As the vinyl aromatic polymer, in addition to styrene, o-methylstyrene, p-
Nuclear alkyl-substituted styrene such as methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene and p-tert-butylstyrene, α-alkyl substituted such as α-methylstyrene and α-methyl-p-methylstyrene Examples thereof include polymers such as styrene, copolymers of one or more of these with at least one or more of other vinyl compounds, or copolymers of two or more of these.

Examples of the compound copolymerizable with the vinyl aromatic compound include methacrylates such as methyl methacrylate and ethyl methacrylate, acrylonitrile,
Examples thereof include unsaturated nitrile compounds such as methacrylonitrile, and acid anhydrides such as maleic anhydride. Among these polymers, particularly preferable polymers are polystyrene and styrene-acrylonitrile copolymer (hereinafter referred to as AS resin).

The rubber used for the rubber-modified vinyl aromatic polymer is preferably polybutadiene, styrene-butadiene copolymer, polyisoprene, butadiene-isoprene copolymer, natural rubber or ethylene-propylene copolymer. As the modified vinyl aromatic polymer, rubber modified polystyrene (hereinafter HIPS) and ABS resin are preferable.

The PPE resin composition used in the present invention is preferably a mixture of the above PPE resin and PS resin in an amount of 20 to 90% by weight. More preferably, 20
~ 90% by weight. If it is out of this range, the organic electrolyte solution resistance, moldability and heat resistance are extremely adversely affected and the battery cannot be used as a battery case. The polyolefin used in the present invention is preferably a polyolefin having a number average molecular weight of 20,000 or more, which is used as a general molding material, and examples thereof include high density polyethylene, ultra high molecular weight high density polyethylene, low density polyethylene and linear low molecular weight polyethylene. Density polyethylene, ultra-low density polyethylene with a density of less than 0.90, isotactic polypropylene, and copolymerization of two or more compounds selected from ethylene, propylene, other α-olefins, unsaturated carboxylic acids or their derivatives. Coalescing, for example ethylene / butene-1 copolymer,
Ethylene- (meth) acrylic acid copolymer, ethylene-
(Meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, propylene / ethylene (random, block) copolymer, propylene / 1-hexene copolymer, propylene / 4-methyl-1- Examples thereof include a pentene copolymer, poly (4-methyl-1-pentene), and polybutene-1. These can be used alone or in combination of two or more. Among these polyolefins, polyethylene is preferable, and low density polyethylene, linear low density polyethylene, and high density polyethylene are preferable.

The content of the polyolefin is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight. If it exceeds 40% by weight, not only the molded product is liable to peel off and the appearance is deteriorated, but also the heat resistance is lowered, and further, flame retardance cannot be easily imparted as desired. On the other hand, if it is less than 0.1% by weight, no effect can be seen in terms of thin-wall moldability and appearance, which are the objects of the present invention.

Further, in order to improve the compatibility between the PPE resin and the polyolefin, it is preferable to use various compatibilizing agents such as thermoplastic elastomers in combination. The thermoplastic elastomer may be any elastomer having a glass transition temperature of less than 30 ° C., for example, styrene-butadiene copolymer, styrene-isoprene copolymer, ethylene-propylene copolymer, ethylene- Examples thereof include vinyl acetate copolymers, thermoplastic urethane elastomers, fluoroelastomers and the like. Of these, a styrene-butadiene copolymer is particularly preferable.

Further, if necessary, for example, even if the unsaturated portion (for example, butadiene portion) in the structure of styrene-butadiene copolymer or the like is saturated by hydrogenation by a known method, α, β -Unsaturated carboxylic acid or
A modified elastomer obtained by reacting the derivative with or without a radical generator in a molten state, a dissolved state, or a slurry state at a temperature of 80 to 350 ° C. may be used. It may be a mixture of an elastomer and the hydrogenated elastomer or modified elastomer.

The amount of the compatibilizer (thermoplastic elastomer) compounded is preferably in the range of 0.1 to 30% by weight. On the contrary, if the blending amount exceeds 30% by weight, the compatibility is deteriorated and the peeling phenomenon and the physical properties are deteriorated. In addition, a flame retardant can be added to the PPE resin composition used in the present invention as desired. For example, a halogen compound such as tris (chloroethyl) phosphate, tris (chloropyr) phosphate, decabromodiphenyl oxide, tetrabromobisphenol A, hexabromobenzene, hexabromocyclododecane, perchlorocyclododecane, or
Triphenyl phosphate, tricresyl phosphate, 1,3-bis (diphenylphosphono) benzene, bisphenol A / polycresyl phosphate, bisphenol A / poly (2,6-xylenyl) phosphate, bisphenol A / polyphenyl phosphate, etc. They can be used alone or in combination of two or more.

Among them, phosphoric acid ester flame retardants are preferable, and among them, bisphenol A.polycresyl phosphate, bisphenol A.poly (2,6-xylenyl) phosphate, and bisphenol A.polyphenyl phosphate are resistant to organic electrolyte. It is excellent and particularly preferable. The amount added is not particularly limited, but is preferably 30% by weight or less. If it exceeds 30% by weight, the heat resistance and the organic electrolyte resistance required for the battery case are remarkably deteriorated, and the flame retardant bleeds out into the molded case to cause poor appearance.

A filler may be added to the PPE resin composition used in the present invention in order to improve mechanical properties, dimensional accuracy, heat resistance and the like within a range that does not impair the effects of the invention. . This filler is not particularly limited as long as it satisfies the required characteristics of the battery case, those conventionally used in thermoplastic resins, for example, inorganic salts,
Glass, carbon, metal, ceramic, mica, wood powder,
Any one of talc, asbestos and the like can be appropriately selected and used according to required characteristics.

Further, the form of the filler is not particularly limited, but may be any of powder form, granular form, fibrous form, flaky form, whisker form, and the like, if desired. A filler that has been subjected to surface treatment with a coupling agent or convergence treatment with a sizing agent can also be used.
The filler may be added in the required amount depending on the required characteristics of the battery case, such as heat resistance, appearance, dimensional accuracy, rigidity and strength. However, if the addition amount exceeds 50% by weight, defective filling occurs due to insufficient resin amount and the formability is extremely deteriorated.

In addition, various additives such as a fluidity improver, a plasticizer, a release agent, an ultraviolet absorber, an ultraviolet inhibitor, an antioxidant, etc. are added to the PPE resin composition within a range not impairing the effects of the present invention. Light stabilizers, antistatic agents, dyes and pigments, etc. can be added in desired amounts. The method for producing the PPE resin composition used in the present invention is not particularly limited, and it can be produced by kneading using a kneader such as an extruder, a heating roll, a kneader, a Banbury mixer.

Further, the method of molding the battery case of the present invention is not particularly limited, and an injection molding method, a blow molding method, a compression molding method or the like which is commonly used can be used. Also,
At the time of molding, it is more preferable to coat the mold with a heat insulating layer or temporarily apply a voltage to keep the mold temperature at a high temperature because the surface of the molded body becomes smooth and the appearance is improved.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
Will be explained. The physical properties are evaluated from each material.
Mold a piece (3 mmt) and add it to the organic electrolyte 240
Evaluation was carried out after immersion in time. At this time, as an organic electrolyte,
1.0M: LiPF₆Propylene carbonate containing
To: methyl ethyl carbonate = 1: 1 mixed solution, and
1.0M: LiPF₆Ethylene carbonate containing
To: diethyl carbonate = 1: 1 mixed solution was used. (1) Weight change rate A test that was left for 240 hours in an atmosphere of 25 ° C and 50% RH
Use the test piece as a blank in an atmosphere of 25 ° C and 50% RH
Represents the weight change of the test piece after immersion for 240 hours in percentage.
Was. (2) Tensile strength retention rate Even after standing for 240 hours in an atmosphere of 25 ° C and 50% RH
Is used as a blank, and is used in an atmosphere of 25 ° C and 50% RH for 2
Expressed as a percentage, the tensile strength retention after 40 hours immersion
Was. The measurement is conducted under the atmosphere of 25 ° C. and 50% RH according to ASTM-
It carried out according to D638. (3) Appearance evaluation (gloss evaluation) A test after immersion for 240 hours in an atmosphere of 25 ° C. and 50% RH.
The gloss value of the test piece is measured with a gonio-gloss meter (manufactured by Suga Test Instruments Co., Ltd.)
Measured. (4) Flammability 1/16 in for the blended flame retardant in the examples.
After immersion for 240 hours using Titanium Zaku test pieces, UL-9
According to the vertical combustion test method specified in 4
The interval was measured. (5) Heat resistance (deflection temperature under load) After allowing to stand naturally for 24 hours in an atmosphere of 25 ° C and 50% RH 1
/ 4 in Titanium Zaku test piece is compliant with ASTM-D648
Based on a load of 18.6 kg / cm²It was measured at. (6) Thin-wall formability (spiral flow length) A spiral groove is formed with a width of 1 cm and a thickness of 0.1 cm.
Cylinder temperature 290 ℃, mold temperature 8
0 ° C, injection pressure (gauge pressure) 90 kg / cm ²Shot at
After molding, the flow length was measured.

[0030]

Examples 1 to 3 As PPE resin, 3 in chloroform
Poly (2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity [η] of 0.52 measured at 0 ° C.
%, Asahi Kasei Polystyrene 685 (hereinafter abbreviated as GP685) [Asahi Kasei Kogyo KK, trade name] 10% by weight,
Styrene-butadiene copolymer (abbreviated as SBCa below)
5% by weight of [Asaflex 805: manufactured by Asahi Chemical Industry Co., Ltd.], 5% by weight of styrene-butadiene copolymer (hereinafter abbreviated as SBCb) [Sorprene T406: manufactured by Nippon Elastomer Co., Ltd.] , Hydrogenated styrene-butadiene copolymer (hereinafter abbreviated as HTR) (styrene weight%: 60, hydrogenation rate of polybutadiene part = 99.
9% to 8% by weight, low density polyethylene (hereinafter LDP
(Abbreviated as E) [Suntech M1804: Asahi Kasei Corp.
Made, trade name], high density polyethylene (hereinafter abbreviated as HDPE) [Suntech J751: manufactured by Asahi Kasei Kogyo Co., Ltd., trade name], polypropylene (hereinafter abbreviated as PP) [ace polypro M1600: manufactured by Asahi Kasei Kogyo Co., Ltd., product 10% by weight each of which was melt-kneaded with a PCM-30 twin-screw extruder [manufactured by Ikegai Tekko KK] at a cylinder temperature of 280 ° C. to obtain pellets.

The obtained pellets were heated at a cylinder temperature of 280.
Injection molding at ℃, mold temperature 80 ℃, dumbbell piece, 1/4
Intitanium Zaku and 1/16 intitanium Zaku were obtained.

[0032]

[Examples 4 to 6] PPE, GP685, LDPE, HD
A test piece was obtained by pelletizing in the same manner as in Example 1 except that the amount of PE was changed, and then similarly molding.

[0033]

[Comparative Example 1] 60% by weight of PPE resin and 2 of GP685
2 wt%, SBCa 5 wt%, SBCb 5 wt%,
The HTR was set to 8% by weight, pelletized in the same manner as in Example 1, and molded in the same manner to obtain a test piece.

[0034]

[Comparative Example 2] 0.05% by weight of LDPE and 7.
A test piece was obtained by pelletizing in the same manner as in Comparative Example 1 except that the content was changed to 95% by weight, and then similarly forming.

[0035]

Comparative Example 3 22% by weight of PPE resin and 1 of GP685
Pelletizing was performed in the same manner as in Comparative Example 1 except that 0% by weight and LDPE were changed to 50% by weight, and the same molding was performed to obtain a test piece.

[0036]

[Table 1]

As is clear from Table 1, Examples 1 to 6 show excellent characteristics as battery cases as compared with Comparative Examples 1 to 3 by adding a required amount of polyolefin.

[0038]

[Table 2]

[0039]

Examples 7 to 11 55% by weight of PPE resin, GP68
5% by weight, 8% by weight of LDPE, 2% by weight of SBCa, 2% by weight of SBCb, 5% by weight of HTR and 8% by weight of each of the phosphate esters A to E shown in Table 2 were used. Pelletizing was carried out in the same manner as in No. 1, and the same molding was carried out to obtain a test piece.

[0040]

[Table 3]

As is clear from Table 3, Examples 7 to 11
Shows excellent characteristics as a battery case while maintaining flame retardancy.

[0042]

EFFECTS OF THE INVENTION The battery case of the present invention has improved resistance to organic electrolyte solution as compared with the conventional case.
Excellent balance of thin moldability and heat resistance and excellent appearance.
It is also excellent in flame retardancy.

Claims (1)

[Claims] 1. A battery case containing at least one organic electrolyte battery, wherein the battery case comprises a polyphenylene ether resin composition, and the resin composition contains 0.1 to 40% by weight of polyolefin. Battery case characterized by.