JPS60230354A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To increase strength and decrease moisture permeability of a synthetic resin layer with which a plate group is wrapped by forming the resin layer with two layer structure of polyolefine and thermoplastic synthetic resin such as polyethylene terephthalate. CONSTITUTION:A plate group is comprised of a positive plate 1, a separator 2, a negative plate 3, and posts 5 whose part is covered with PE resin 4 capable of hot-melt bonding. The plate group is wrapped with a sheet-shaped synthetic resin layer 6 prepared by arranging polyolefine synthetic resin having good hot- melt bonding ability and acid resistant property on its inner side and thermoplastic synthetic resin having an oxygen permeability of 200cc/m<2>.24hr.atm or less and a moisture permeability of 10g/m<2>.24hr or less on its outer side as a barrier layer. The circumference of the resin layer 6 is sealed by hot-melt bonding to form a sealed lead-acid battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sealed lead-acid battery used as a power source for portable equipment, and particularly to an improved battery.

Conventional structure and problems Sealed lead-acid batteries are widely used as a compact, portable power source because the glass mat that serves as a separator holds the electrolyte and prevents it from flowing, so the electrolyte does not overflow when charging. are doing.

Conventional sealed lead-acid batteries have a structure in which an electrode group consisting of a positive electrode plate, a negative electrode plate, and a separator is inserted into a box-shaped cell made of ABS resin, etc., and the lid is sealed by adhesive or welding. ing.

However, because of this structure, the shape and dimensions of the battery change depending on the battery voltage and capacity, making it difficult to mass-produce a wide variety of batteries at low cost. Furthermore, in the manufacturing process, there are many steps that are difficult to mechanize, such as inserting the electrode plate group, adhering the lid, etc., and fitting the safety valve, which makes mass production difficult and leads to increased manufacturing costs.

As a countermeasure to this problem, as shown in Japanese Patent Application Laid-Open No. 58-83108, a film or sheet-like synthetic resin such as polyethylene is used as the electrolytic material to wrap the electrode plate group and seal it by heat welding. , a method has been proposed in which the safety valve is also molded at the same time. However, it is difficult for such film or sheet materials to satisfy the properties required as an electrically conductive material, such as moisture permeability, oxygen permeability, acid resistance, tensile strength, and bursting strength.
This has been a major problem in commercializing this type of battery.

Purpose of the Invention The present invention solves the above-mentioned conventional problems, and uses a film-like or sheet-like synthetic resin laminated with various synthetic resin films or net-like synthetic resin fibers that have the necessary functions as an electrically conductive material. By using it, the purpose is to obtain the characteristics necessary for electrical conduction.

Structure of the Invention The present invention provides a film-like or sheet-like synthetic resin body that envelops an electrode group consisting of a positive electrode plate, a negative electrode plate, and a separator, and a polyolefin-based synthetic resin with excellent heat weldability and acid resistance on the inner surface in contact with the electrode plate group. Arranged with resin, its outer surface has an oxygen permeability of 20 CC,/rn'・24hr-atm or less and a moisture permeability of 10 f/rr? -, 24 hours or less thermoplastic synthetic resin is laminated as a barrier layer.

However, it goes without saying that the barrier properties here need only be met by the entire laminate film.

Examples of polyolefin resins include low-density polyethylene,
Medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene and their copolymers such as ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, ethylene acrylic ester copolymer , ethylene methacrylate copolymer, ethylene-propylene copolymer, and terpolymer can be used.

In addition, as the above-mentioned acid-modified products, graft polymerization and modification with unsaturated carboxylic acids or their anhydrides such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, citraconic acid, citraconic anhydride, itaconic acid, and itaconic anhydride can be used. Good too.

What has a carboxylic acid group is sodium Na.

Ionomers cross-linked with metal ions such as zinc Zn''+ can also be used.

As the barrier layer, polyvinylidene chloride (PVDC)
Laminate the film to other films or PVDC with polyester.

It is also possible to laminate polypropylene or polyamide-based films with so-called ζ-coated films, polyvinyl alcohol, saponified ethylene vinyl acetate, polyacrylic nitrite and its copolymers, and polyvinyl chloride.

In addition, it is not possible to make the film multi-layered in order to reinforce the entire film, or to laminate a so-called net-like material made of woven fabrics of stretched yarns of polyolefin, polyester, etc. to improve mechanical strength and tear strength over a wide range. It is valid.

Films or sheets can be laminated using known methods such as dry lamination using urethane-based, polyester-based, or ethylene-vinyl acetate copolymer-based resins as adhesives, or extrusion lamination. Dry lamination is preferable for polyolefin films in terms of content resistance and adhesive strength.

Sufficient tensile strength is achieved by combining films.

Bursting strength can be obtained, but these can be dramatically improved by laminating a net-like material inside.

This laminate film can be used as a single layer, or it can be further layered with a polyolefin film to create a double or triple bag structure, improving pinhole resistance when bent and increasing the flexibility of the bag. It also prevents leakage due to bag breakage.

Furthermore, by drawing and forming at least one of the films or sheets into a shape substantially similar to the electrode plate group, it is possible to further reduce the size of the battery. - The forming here may be performed by vacuum forming, vacuum pressure forming, pressure forming, plug assist forming, cold pressing, etc.

The film-like or sheet-like synthetic resin body used for electrolyte is designed to prevent deterioration of capacity life due to moisture permeation and evaporation of the electrolyte, to prevent increase in self-discharge due to permeation and intrusion of oxygen from the atmosphere, and to prevent self-discharge when left unused. It has the function of keeping the inside of the battery in a reduced pressure state by permeating and releasing small amounts of hydrogen gas generated by the process, and also has bursting strength and tensile strength that can withstand pressure fluctuations inside the battery.
Functions such as acid resistance that can withstand sulfuric acid in the electrolyte and heat weldability are required.

Description of examples Examples of the present invention will be described below along with comparative examples.

Among the electrically bonded materials in the table below, (1) is the conventional A mentioned above.
(2) is medium density polyethylene (
MDPE) used alone with a thickness of 200μ, (
3) is heat-weldable on the inner surface in contact with the electrode plate group.

90 of low density polyethylene (LDPE) with excellent acid resistance
A μ film is placed on the outside with tensile strength.

Polyethylene terephthalate (PET) with excellent bursting strength
) was laminated to a thickness of 12μ, and these are all comparative examples. Examples of the present invention are shown in (4) and after in the electrical insulation material, and (4) is made of medium density polyethylene (from the inside) in order to improve the strength of the laminate film of (3) and reduce oxygen permeability and moisture permeability. MDPE) 80
μ, polyvinylidene chloride (PvDC) 20 μ and P
Film laminated with ET12μ, (6) is (4)
In order to further increase the strength and reduce oxygen permeability and moisture permeability, high strength oriented polypropylene (O
PP) 30μ and PVDC coated - PE712
(6) is a film laminated with ethylene acrylic acid copolymer (E
AA) A film laminated with 8AP, 12μ of Ni-PET, and 20μ of PVDC-coated Ni-PET, (
'7) is oxygen permeability.

In order to further increase moisture permeability than (4), (5), and (6), we used a laminate film in which the two layers of PET and OPP on the outside of the MDPE were each coated with PVDC, and (8) was made with stretched nylon (ON )20μ, K
-OPP! : A film laminated to an intermediate layer of MDPE, (9) is linear low density polyethylene (LLDPE), which is stronger than LDPE, and PET with a thickness of 30μ to increase tensile strength and bursting strength, as well as improve bending and tearing strength. It is a film made by arranging fibers in a net shape and then laminating 2 layers of 12μ PET on top of which PVDC is further coated. (10) is an OP with 100μ of ethylene vinyl acetate copolymer (EVA) and 20μ of polyvinyl 7/l/:7-L (PVA) to lower the oxygen permeability.
Film laminated with P 201t, (11) is low temperature sealing 2, properties and pinhole resistance, DPE15
A film laminated with 15μ of saponified EVA and 712μ of PE on 0μ, (12) is a film laminated with 120μ of MDPE.
vD C3p and PVA 15 p and PvD03
Film laminated with μ and oPP2oμ, (13)
In order to improve toughness and formability, a film was laminated between tL'DPEsoμ and polybutylene terephthalate (PBT) 30μ with Burlex 30μ, an acrylonitrile/methacrylic acid copolymer manufactured by Pictron Co., Ltd., in the United States. 14) is a film laminated with ethylene methyl methacrylate copolymer (EMMA) 120, cz, CPP3oμ with PVDC cordon, and PET12μ to improve toughness, low-temperature sealability, and flexibility, and (16) is ionomer 120μ. coated with 30μ oriented polyethylene (OPE) and PvDC.
Film laminated with PET 12μ, (16) is M
DPE40p [PVDc coated 0N15μ and OP
MDP on the outside of the film laminated with P20μ
It has a double bag structure by covering it with an E40μ bag.

In addition, the tensile strength of each military material in the table is JISZ-1702.
According to the JIS P-8112 method, the bursting strength is determined according to the JIS P-8112 method.
Moisture permeability was measured by JIS Z-0208 method, and oxygen permeability was measured by ASTM D-1434-58 method.

Furthermore, as shown in FIG. 1, the positive electrode plate 1 is wrapped in a U-shaped separator 2 mainly made of glass fiber, and two negative electrode plates 3 are arranged on both sides of the separator 2. As shown in FIG. 2, a group of electrode plates, in which a pole column 6 partially covered with PE resin 4 is integrated, is wrapped with each of the above-mentioned films 6 and heat welded, and an exhaust valve 7 is provided in a part. 2V with a similar structure.

I created a sAh sealed lead-acid battery (width 150w x height 76mm x thickness 16mm). These batteries are heated to an ambient temperature of 60°C.
The batteries were allowed to stand for 4 weeks at a relative humidity of 20%, and the weight loss (f) due to moisture permeation and the remaining capacity after self-discharge due to oxygen permeation (a) were also measured.

The results show that by laminating two or three layers of PET, PP, or nylon on a PK film, the tensile strength is 2 to 6 times higher than that of the conventional PE-only film shown in (2), and the bursting strength is 2 to 6 times higher. It increases 3 to 8 times,
In a laminated film with PET fibers arranged in a net shape, the tensile strength was improved by 6 to 10 times, and the burst strength was improved by 10 to 16 times.

In addition, by coating PVDC with PET (=P P), the oxygen permeability is 1.
The moisture permeability was reduced to about 1/100 to 1/2%, which was better than the ABS resin currently used in sealed lead-acid batteries.

Furthermore, the decrease in remaining capacity and battery weight after the sealed lead-acid battery assembled with the film of the above example was left for 4 weeks at an ambient temperature of 60°C and a relative humidity of 20% was determined by the oxygen permeability of the various films of the example. In proportion to moisture permeability, the remaining capacity is 30-so% better than conventional PE-only films, and the battery weight is also reduced by about 10%, and even compared to ABS resin batteries, the remaining capacity is 10-20% better. It was excellent, and the reduction in battery weight was comparable to that of a feather.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained:
i; I can.

0) PE is used as a polyolefin film with excellent heat weldability.
By laminating two or more layers of T, i'P, nylon film or PE or PET fiber net, conventional P
It became possible to significantly improve the tensile strength and bursting strength compared to a film made only of E, and the reliability as a film for electrolyzing sealed lead-acid batteries was improved.

(2) PVDC coated L*pp, pEr, PVA.

By laminating saponified EVA, polyacrylonitrile, and their copolymer films, oxygen permeability and moisture permeability are significantly reduced, self-discharge caused by oxygen penetration is reduced, and electrolysis caused by moisture permeation and evaporation is reduced. It is possible to prevent a decrease in capacity and life due to decrease in liquid.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a group of electrode plates in an embodiment of the present invention, and FIG.
The figure is a perspective view of a sealed lead-acid battery in which the same electrode plate group is wrapped in a laminated film. 1...Positive electrode plate, 2...Separator, 3
・・・・・・Negative electrode plate, U, -, -PE resin, 6...
... Polar pillar, 6... Film, 7...
exhaust valve.

Claims (1)

[Scope of Claims] (1) A sealed lead-acid battery in which an electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a separator is wrapped in a film-like or sheet-like synthetic resin body, the electrode plate group of the synthetic resin body and A sealed lead-acid battery characterized by having a polyolefin film placed on the contacting surface and laminated with two or more layers of thermoplastic synthetic resin such as polyethylene terephthalate, polypropylene, or nylon on the outside. A sealed lead-acid battery according to claim 1. (3) The laminated film-like or sheet-like synthetic resin body has at least one layer coated with polyvinylidene chloride or is laminated with a polyvinylidene chloride film. lead-acid battery. (4) The laminated film-like or sheet-like synthetic resin body is one in which polyvinyl alcohol, saponified ethylene-vinyl acetate copolymer, polyacrylonitrile, and a copolymer thereof are laminated in at least one layer thereof. The sealed lead-acid battery described in paragraph 1. (6) The laminated film-like or sheet-like synthetic resin body is one in which net-like synthetic resin fibers are laminated on at least one layer thereof.
Sealed lead-acid batteries as described in section. (6) The sealed lead-acid battery according to any one of claims 1 to 5, wherein the film-like or sheet-like synthetic resin body has a double bag or triple bag structure.