JP2000294205A - Battery jar for closed multilayered secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical method of recycling a material of a secondary battery jar, of which the rapid enlarged demand is expected in the field of automobiles. SOLUTION: In a battery jar for closed secondary battery having a multilayered structure of a skin layer and a core layer, the skin layer is made of a non-recyclable resin, and the core layer is made of a recyclable resin. Further the skin layer is made of a non-recyclable resin of a crystalline polyolefin resin, and the core layer is made of a recyclable resin of an alloy resin composition mainly composed of a crystalline polyolefin resin and a polyphenylene ether resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a lead sealed battery,
The present invention relates to a member suitable for various secondary batteries such as an alkaline battery and a lithium ion secondary battery. More specifically, the present invention relates to a sealed secondary battery case using recycled resin.

[0002]

2. Description of the Related Art A driving power source for a mobile device such as a mobile personal computer, a cellular phone, a video camera, a computer backup power source, and a secondary battery such as an electric vehicle using a secondary battery itself as a driving source instead of an internal combustion engine. Are rapidly expanding. With the increasing demand for rechargeable batteries, build a recycling system to reuse used battery waste from the viewpoint of environmental protection. Also, from the viewpoint of resource saving, recycle prues and runners, and recycle unfinished molded products. Market needs such as construction of usage methods are increasing.

In particular, an enormous amount of secondary batteries are expected to be used in electric vehicles that use a secondary battery as a driving source, and hybrid vehicles that use an internal combustion engine and a secondary battery together as a driving source. There is a need for measures to recycle and treat secondary battery waste. It is anticipated that resin cells (containers) will be used in most of the secondary batteries for driving automobiles from the viewpoint of weight reduction. In the future, product recycling of resin cells (hereinafter referred to as material recycling) will be implemented in hybrid vehicles. In spite of the fact that it is indispensable that it will become an issue for electric vehicles, no method of material recycling has been studied at present.

[0004] Regarding the sandwich molding, although the technical concept of commercializing the product by using a recycled material for the core resin is known, an effective specific application of material recycling using the sandwich molding and an optimal use for the application are described. At present, there are few documents suggesting combinations of resins.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optimum method for material recycling of a battery case for a secondary battery.

[0006]

Means for Solving the Problems The present inventors diligently studied a material recycling method for a battery case for a secondary battery, and as a result, found that a sandwich molding method was effective, and reached the present invention. That is, the present invention is a battery case for a secondary battery having a multilayer structure in which a skin layer is made of a non-recycled resin (hereinafter, referred to as a virgin resin) and a core layer is made of a recycled resin. The core layer is made of a virgin resin of a crystalline polyolefin resin, or a virgin resin of an alloy composition containing a polyolefin resin and a polyphenylene ether-based resin (hereinafter abbreviated as a PPE-based resin) as main components.
An object of the present invention is to provide a secondary battery case having a multilayer structure composed of a recycled resin of an alloy resin composition composed of a base resin.

Hereinafter, the present invention will be described in detail. The crystalline polyolefin resin used in the present invention is a resin used as a usual molding material, and has a weight average molecular weight of 20.
000 or more, more preferably 3 or more.
0000 or more. For example, polypropylene,
Polyethylene, a copolymer containing propylene as a main component, a copolymer containing ethylene as a main component, and a crystalline polyolefin resin, for polypropylene, preferably has an isotack index of 90 or more, more preferably 95 or more. The above resins are referred to.

For polyethylene, the density is 0.92
It is preferably a resin of at least 0.94, and more preferably a resin of at least 0.94. The components of the propylene-based copolymer are ethylene, butene-1, hexane, octene,
Selected from 4-methylpentene-1. The component of the copolymer containing ethylene as a main component is selected from the above components excluding ethylene.

Among these crystalline polyolefin resins, preferred are polypropylene and propylene / ethylene block copolymers, which are added with a nucleating agent to increase the crystallinity from the viewpoint of imparting rigidity and high temperature creep. Is more preferred. Examples of the nucleating agent include organic and inorganic compounds, and among them, phosphorus-based, aluminum-based, and sorbitol-based nucleating agents are also included, but are not limited thereto.

The alloy resin composition comprising a crystalline polyolefin resin and a PPE resin as main components used in the present invention is characterized in that the crystalline polyolefin resin forms a matrix phase (sea) and the PPE resin forms a dispersed phase (island). It is preferable that the dispersed phase has a small particle size and is uniformly dispersed. In order to uniformly disperse the PPE-based resin in the crystalline polyolefin resin, it is necessary to add a compatibilizer to improve the compatibility between the two.

As the compatibilizer, for example, styrene-
Examples thereof include a butadiene copolymer, a styrene-isoprene copolymer, and a hydrogenated product thereof. Among them, a hydrogenated product of a styrene-butadiene copolymer is preferable, or a polyolefin resin and a PPE resin or a polystyrene-based resin (hereinafter, PS-based resin). (Abbreviated as resin) is also preferred.

If necessary, for example, a styrene-butadiene copolymer, a styrene-isoprene copolymer, or a hydrogenated product thereof may be added with an α, β-unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator. May be a mixture with a modified copolymer obtained by reacting in the absence of a molten state, a dissolved state, or a slurry state at a temperature of 80 to 350 ° C., and further, the unmodified copolymer And a mixture with a modified copolymer.

The molecular weight of the polymer used for the compatibilizer that can be used herein is not particularly limited, but the molecular weight of the styrene portion is preferably at least 5,000 (weight average molecular weight). The 1,2-vinyl bond of butadiene is preferably 2-80%. This compatibilizer contains at least one of the above-mentioned copolymers, and the compounding amount thereof is about 0.1 to 30.
It is preferably in the range of% by weight, and the compounding amount is preferably the minimum amount necessary for compatibility from the viewpoint of improving rigidity.

In the morphology of the resin composition having a sea-island structure, the ratio of the crystalline polyolefin resin to the PPE resin is such that the matrix phase (sea) is the crystalline polyolefin resin and the dispersed phase (island) is the PPE resin. From the viewpoint of imparting rigidity, a ratio near the phase transition point where the crystalline polyolefin resin can be a matrix phase is preferable. Crystalline polyolefin resin, PPE resin and PPE
The weight ratio of the resin to the system resin is preferably from 1: 3 to 3: 1, more preferably from 1: 2 to 3: 1, and particularly preferably from 1: 1 to 2: 1.

For applications requiring a flame retardant, a flame retardant may be added to the resin composition forming the skin layer and / or the core layer, if desired. For example, halogen compounds such as tris (chloroethyl) phosphate, tris (chloropyr) phosphate, decabromophenyl oxide, tetrabromobisphenol A, hexabromobenzene, hexabromocyclododecane, perchlorocyclododecane, or triphenyl phosphate, trichlene Single or two or more kinds of zyl phosphate, 1,3-bis (diphenylphospheno) benzene, bisphenol A / polycresyl phosphate, bisphenol A / poly (2,6-xylenyl) phosphate, bisphenol A / polyphenyl phosphate, etc. Can be used in combination.

The PPE resin used in the alloy composition of the present invention may be a polyphenylene ether resin (hereinafter abbreviated as PPE resin) alone, or a resin composition containing 5 to 95% by weight of a PPE resin and 95 to 5% by weight of a PS resin. Things.

The P used in the alloy resin composition of the present invention
The PE resin is composed of the following structural unit represented by Chemical Formula 1 or Chemical Formula 2, and the reduced viscosity (0.5 g / dl, chloroform solution, measured at 30 ° C.) may be in the range of 0.15 to 0.8. Preferably, more preferably, a homopolymer or a copolymer in the range of 0.2 to 0.7 can be used.

[0018]

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[0019]

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(R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ in each formula are each hydrogen, halogen, a primary or secondary lower alkyl group having 1 to 7 carbon atoms, phenyl A haloalkyl group, an aminoalkyl group, a hydrocarbonoxy group, and a halohydrocarbonoxy group in which at least two carbon atoms separate a halogen atom and an oxygen atom. May be different.)

Representative examples of the homopolymer of the PPE resin include poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether) and poly (2,6-dimethyl-1,4-phenylene ether). (2-methyl-6-phenyl-
1,4-phenylene ether) and poly (2,6-dichloro-1,4-phenylene ether). Further, 2,6-dimethylphenol and other phenols (for example, 2,3,6-trimethyl) Polyphenylene ether copolymers such as a polymer with phenol or 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 preferred, and poly (2,6-
Dimethyl-1,4-phenylene ether) is more preferred.

The method for producing the PPE resin used in the present invention is not particularly limited as long as it can be obtained by a known method. For example, US Pat. No. 3,306,874, US Pat. 325735
No. 7, No. 3257358, Japanese Patent Publication No. 52
And a method described in JP-A-17880.

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

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

Examples of the compound copolymerizable with the vinyl aromatic compound include methacrylic esters such as methyl methacrylate and ethyl methacrylate, unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile, and acid anhydrides such as maleic anhydride. And the like. Among these polymers, particularly preferred polymers are polystyrene and styrene-acrylonitrile copolymer (AS resin).
It is.

Examples of the rubber used for the rubber-modified vinyl aromatic copolymer include polybutadiene, styrene-butadiene copolymer, polyisoprene, butadiene-isoprene copolymer, natural rubber, and ethylene-propylene copolymer. be able to. In particular, polybutadiene and a styrene-butadiene copolymer are preferable. As the rubber-modified aromatic polymer, rubber-modified polystyrene (HIP
S), ABS resin is preferred.

The method for forming the battery case for a sealed secondary battery having a multilayer structure of the present invention is not particularly limited. For example, using a composite injection molding machine, an injection molding method for uniformly molding a skin layer and a core layer in a desired form, or a blow molding method using a multilayer molding extruder, or a multilayer sheet after molding, The sheet can be formed by a desired forming method such as a method of shaping the product by vacuum forming or pressure forming,
From the viewpoint of the freedom of the product shape, a particularly preferable molding method is a composite injection molding method.

In the case of using composite injection molding, it is important to examine the design of the mold (number of gates, position, etc.), control the injection of the skin and core resin, etc., and use molding conditions and equipment capable of uniformly filling the core layer. Molding.

The virgin resin referred to in the present invention means the number of times of regeneration (for example, the number of recycles of scrap materials (sprues, runners, etc.) generated during injection molding, and the remnants (trimming scraps) generated during extrusion sheet molding). ) Is less than once,
Alternatively, a recycled resin having a strength retention of Izod impact strength of 90% or more is also included.

The term “recycled resin” refers to a recycled resin that has been regenerated twice or more or has an Izod impact strength of 9%.
Collectively, less than 0% of recycled resin and recycled resin recovered from used products.

In molding the recycled resin, a virgin resin is added to the recycled resin for the purpose of improving the resin performance, or a reinforcing agent for reinforcing the performance (for example,
Elastomers for imparting toughness and inorganic fillers such as glass fibers for imparting rigidity may be additionally used. It is particularly preferable to use the above method when the resin performance of the recycled resin used is significantly reduced.

The alloy resin composition containing a crystalline polyolefin resin and a PPE-based resin as main components for forming a core layer using the recycled resin of the present invention has a high rigidity at high temperature, a high temperature creep characteristic, a dimensional stability, and a resistance to hot water permeation. Incorporating an inorganic filler for the purpose of improving the properties and gas permeation resistance can be used.

In this case, the inorganic filler is preferably in a scaly (flake) form from the viewpoint of improving hot water permeability and gas permeability resistance. For example, glass flake, mica and the like are preferable. The inorganic filler preferably has good adhesion to the resin, and preferably has been subjected to a surface treatment such as a silane coupling agent. In selecting the inorganic filler, it is preferable to consider the resistance to the electrolyte used in the sealed secondary battery.

The amount of the inorganic filler is 5 to 30% by weight.
And more preferably 10 to 20% by weight. If the amount is less than 10% by weight, the improvement in hot water permeability and gas permeability resistance is insufficient, and if it exceeds 30% by weight, impact resistance and toughness are insufficient.

The crystalline polyolefin resin used in the present invention and the alloy resin composition containing a crystalline polyolefin resin and a PPE-based resin as main components, in addition to the above-described flame retardant, are used in a range which does not impair the objects of the present invention. , Various additives such as flow additives, plasticizers, release agents, ultraviolet absorbers, antioxidants, light stabilizers, metal deactivators, and colorants can be added.

[0036]

In the battery case for a secondary battery according to the present invention, the skin layer is made of a crystalline polyolefin resin or a virgin resin of an alloy resin composition containing a crystalline polyolefin resin and a PPE resin as main components, and the core layer is made of a crystalline polyolefin resin. It is composed of a recycled resin of an alloy resin composition containing a resin and a PPE-based resin as main components. The recycled resin that forms the core layer includes
Resins mixed with an inorganic filler can be used according to the required application properties, or various performance enhancers can be added to the recycled resin before processing in order to reinforce performance degradation.

The secondary battery case of the present invention has a multilayer structure because the performance of the skin layer is most important in terms of performance such as appearance and strength. If a virgin resin is used for the skin layer,
This is because material recycling is sufficiently possible. For example, it is not an exaggeration to say that the bending stress of the product is influenced by the skin layer because the surface layer is subjected to the maximum stress under the bending load, and the surface layer also functions greatly to provide rigidity.

The same applies to the appearance. If the skin layer is made of a virgin resin, a good appearance can be obtained. The same applies to the resistance to chemicals. Performance is demonstrated. That is, the present invention is a battery case characterized by a multilayer structure upon material recycling of a recycled resin, and by disposing a virgin resin on a skin layer, a battery case with good strength, chemical resistance, and appearance is obtained. Things.

The resin constituting the battery case of the present invention is a crystalline polyolefin resin or a crystalline polyolefin resin
The alloy resin composition containing a PE resin as a main component is limited to an organic electrolytic solution used for a lithium ion secondary battery, an alkaline aqueous solution such as potassium hydroxide used for a nickel hydrogen secondary battery, and a lead sealed storage battery. This is because it has good resistance performance to sulfuric acid used for water and a good balance between cost and total performance.

Particularly, in the case of an alloy resin composition containing a crystalline polyolefin resin (matrix phase (sea)) and a PPE resin (dispersed phase (island)) as main components, the PPE resin acts as a heat-resistant filler and has a high rigidity at heat. In addition, it improves creep resistance, mechanical properties, and the like.

Since the present invention has a multilayer structure as described above, it is possible to add functions to the core resin. For example, the rigidity can be further improved by blending an inorganic filler.
In the battery case of the nickel-metal hydride secondary battery, from the viewpoint of alkali resistance, it is not possible to use an inorganic filler such as a glass fiber or a glass flake used as an additive of a resin. Since a resin in which an inorganic filler is blended only is used, there is an advantage that a normal inorganic filler can be used since it does not come into direct contact with an alkaline aqueous solution.

The thickness ratio of the skin layer and the core layer of the present invention is
It is determined by the characteristics required for the battery case.
It is selected from the range of 5 to 2 to 1.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. Tables 1 and 2 show resin combinations used in Examples and Comparative Examples, and test results. For the evaluation of the physical properties, a test piece having a sandwich structure was prepared using a sandwich molding machine and evaluated as follows.

(A) Preparation of test piece Composite injection molding machine (trade name, FS, manufactured by Nissei Plastic Industry Co., Ltd.)
(-80S12ASED) to prepare a test piece having a sandwich structure and a single-layer structure. The cylinder temperature was set to 260 ° C. for both the skin cylinder and the core cylinder. (B) Production of Alloy Resin Composition Pellets of alloy resin compositions 1 and 2 were produced using a twin-screw extruder (trade name, ZSK-40, manufactured by Werner Co.) with the materials and compounding ratios shown in Table 1. did.

(C) Production of recycled resin 40 mm single screw extruder (Thermo Plastics Industry Co., Ltd.)
), And extruding at a cylinder temperature of 300 ° C to produce pellets was repeated five times. Then
Using the re-pellet obtained in the above-mentioned step and the pellet not subjected to the above-mentioned step, single-layer test pieces were prepared using the composite injection molding machine under the condition of a cylinder temperature of 260 ° C., and the Izod impact strength (thickness: 3. 2mm, notched, AS
(Measured by a method according to TM-D256).
The retention rate of the Izod impact strength of the recycled resin of the alloy resin composition 1 was 65%, and the retention rate of the Izod impact strength of the recycled resin of the alloy resin composition 2 was 53%.

(D) Measurement of flexural strength The flexural strength was measured according to ASTM-D790. (E) Evaluation of resistance to chemicals (alkali resistance) A 3.2 mm-thick strip test piece was immersed in a 30% aqueous potassium hydroxide solution for 10 days, and changes in appearance (discoloration, presence or absence of cracks, etc.) were visually observed. Examined.

[0047]

Examples 1 to 3 and Comparative Examples 1 to 3 The virgin resin of Comparative Example 1 was used for the appearance and bending strength of the sandwich molded test piece used for the recycled resin for the core layer of Examples 1 and 2. It was almost the same as the single-layer molding test. The single-layer molded test piece using the recycled resin of the alloy resin composition 1 of Comparative Example 2 had poor appearance and greatly reduced flexural strength, and was not very practical. The single-layer molded test piece using the virgin resin of the alloy resin composition 2 containing the glass flakes of Comparative Example 3 is superior in bending strength, but has poor appearance, and has fine irregularities on the surface after the alkali resistance immersion test. And traces of melting of the surface glass flakes were observed.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

According to the present invention, a practical material recycling method for a battery case for a secondary battery, which sufficiently meets the needs of the recycling market, is provided. This technology can be said to be extremely useful especially for material recycling of battery cases of secondary batteries used in hybrid vehicles and electric vehicles, for which demand is expected to increase significantly in the future.

Claims (3)

[Claims] 1. A sealed secondary battery case having a multilayer structure of a skin layer and a core layer, wherein the skin layer is made of a non-recycled resin, and the core layer is made of a recycled resin. A sealed secondary battery case with a multilayer structure. 2. The skin layer is composed of a non-recycled resin of a crystalline polyolefin resin, and the core layer is composed of a recycled resin of an alloy resin composition containing a crystalline polyolefin resin and a polyphenylene ether-based resin as main components. The battery case for a sealed secondary battery having a multilayer structure according to claim 1, characterized in that: 3. The skin layer and the core layer are made of the same alloy resin composition containing a crystalline polyolefin resin and a polyphenylene ether-based resin as main components, the skin layer is made of a non-recycled resin, and the core layer is made of a recycled resin. The battery case for a sealed secondary battery having a multilayer structure according to claim 1.