JPS5858783B2 - dry battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a synthetic resin cylinder for the exterior of a dry battery, and aims to improve leakage resistance and storage stability.

As shown in Fig. 1, the dry battery is made of a positive mixture 3 made of a mixture of manganese dioxide and acetylene black moistened with an electrolyte, which is placed inside a zinc can 1 through a separator 2 coated with glue.
The carbon rod 4 is planted in the center of the depolarization mixture 3, the top cover paper 5 is placed on the top surface of the depolarization mixture 3, and then the opening of the zinc can 1 is filled with polyethylene or the like. It is closed with a sealing body 6 made of synthetic resin to form a unit cell.

A cathode terminal plate 7 that comes into contact with the bottom of the zinc can 1 separately from this
The periphery of the zinc can 1 and the lower end of the insulating tube 8 that covers the outside of the zinc can 1 are rolled together to form a kelp-like body, the unit cell is inserted into this, and the anode terminal plate 9 is attached to the head of the carbon rod 4. After the upper end of the insulating tube 8 and the periphery of the anode terminal plate 9 were wrapped together, an outer tube 10 made of metal or heat-shrinkable resin tube was attached to the outside of the insulating tube 8.

In this structure, when the dry battery is stored or discharged, the electrolyte leaks out of the zinc can 1 through the contact surface between the zinc can 1 and the sealing body 6, or through the pinholes on the side of the zinc can that are removed by the discharge. In order to prevent this leaked electrolyte from coming out of the dry battery, an insulating tube 8 is placed outside the zinc can 1.

As shown in Fig. 2, a conventional insulating cylinder is made by winding absorbent paper such as kraft paper or filter paper in a spiral shape around a core (not shown) to form an inner cylinder 21, then polyethylene, A synthetic resin film 22 made of polypropylene, polystyrene, polyvinyl chloride, etc. and coated with an adhesive such as polyvinyl acetate emulsion on the lower surface is spirally wound so that the overlapping line of the inner cylinder 21 is approximately in the center. Turn.

The outer tube 28 is formed by winding liquid-absorbent paper coated with an adhesive over the layer ζ in a spiral shape so that the overlap of the synthetic resin film 22 is approximately in the center. Therefore, a laminated structure integrated with the adhesive described above is used.

In this insulating cylinder, the inner cylinder 21 has the function of absorbing and retaining the electrolyte that has come out of the zinc can 1, and the synthetic resin film 22 has the function of preventing the electrolyte absorbed by the inner cylinder 21 from seeping out. The outer cylinder 23 has a function of absorbing the electrolytic solution coming out from the helical overlap of the synthetic resin film 22.

However, in the conventional insulating tube, when the synthetic resin film 22 is wound in a spiral shape, the overlap between the adjacent films,
Furthermore, the adhesion between the synthetic resin film 22 and the contact surfaces of the inner cylinder 21 and outer cylinder 23 is weak, and the electrolyte may leak to the outside of the dry battery.

In particular, when a non-polar material such as polyethylene or polypropylene is used as the synthetic resin film 22, the adhesion between the films is incomplete.
The electrolytic solution absorbed by the synthetic resin film 22 easily penetrates the joints of the synthetic resin film 22 and comes out to the outside.

The electrolytic solution that has leaked out of the synthetic resin film 22 is temporarily absorbed by the outer cylinder 23, but if the amount of leakage is large and the metal outer cylinder 10 is placed outside the outer cylinder 23,
If the outer tube 10 is corroded by the electrolyte and is made of a synthetic resin tube with printing on the inner surface, the printing ink on the outer tube 10 will be discolored by the electrolyte, damaging the appearance of the battery. Furthermore, there is the disadvantage that leaked electrolyte corrodes equipment that uses dry batteries.

In order to improve the adhesion of synthetic resin films and eliminate the above-mentioned drawbacks, the film surface may be subjected to oxidation relief using a dichromic acid mixture, corona discharge, or flame, or to physical processing such as embossing or sandblasting. In addition, methods such as coating the film surface with inorganic powder have been attempted, but it has not been possible to obtain a sufficient adhesive effect to prevent leakage of the electrolyte.

The present invention solves the above-mentioned conventional drawbacks by using a synthetic resin tube in which a metal vapor-deposited film is formed on at least the outer rough surface layer of a stretched thermoplastic resin film containing a filler to reduce moisture permeability. It has been resolved.

In other words, when a thermoplastic film containing a filler is heated and stretched and then cooled in this state, many fine voids or cracks are generated in the film, and the surface is roughened to a shape suitable for adhesion. A synthetic resin film with high strength can be obtained.

Fillers include white clay, talc, asbestos, barium sulfate,
Calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, magnesium oxide, diatomite, silicon oxide, gypsum, etc. are used, and these particles have a particle size of about 0.5 to 30μ.
A film with high uniformity can be obtained by using a fine powder of a certain degree.

The filler is preferably added to the synthetic resin in an amount of about 0.5 to 65 weights or about 5 to 60 weights, more preferably about 25 to 50 weights.

Voids or cracks, which work together with fillers to improve adhesion, are generated as a function of filler addition rate, stretching ratio, stretching temperature, etc., but when quantified using porosity, A ratio of about 10 to 30 vol. has desirable adhesion and mechanical performance.

Thermoplastic synthetic resins include polyolefin resins such as homopolymers such as ethylene, propylene, and budene-1, or copolymers thereof, polyamide resins, polyester resins such as polyethylene terephthalate, and polyvinyl resins such as polyvinyl chloride. Among these, crystalline polyolefin resins are preferred because they have excellent electrolyte resistance and are highly effective in improving strength and other physical properties based on molecular orientation by stretching.

To form a metal vapor deposited film on the surface of the stretched film,
io'~10-2mmH? When a metal such as aluminum or silver is heated to a temperature above its melting point under a moderately high degree of vacuum and a cooled stretched film is exposed to the generated metal vapor, the metal vapor adheres to the film surface and becomes fine particles. The film is solidified, and a uniform metal vapor deposited film with a thickness of several microns to several microns is formed on the surface of the film.

As mentioned above, stretched films containing fillers have a rough surface with many fine voids or cracks on the film surface, so the metal vapor deposited film is formed in close contact with the film and there is no fear of peeling. .

In order to prevent scratches from occurring on the metal-deposited film during handling, the surface of the metal-deposited film is further coated with polyamide resin, polyurethane resin, epoxy resin, etc.
It is preferable to apply and form a protective film such as polyvinyl chloride resin.

As shown in FIG. 3, the synthetic resin film 30 according to the present invention is a film whose surface is roughened (hereinafter referred to as roughened) by uniaxially or biaxially stretching a thermoplastic synthetic resin film containing an appropriate amount of fine filler. A metal vapor deposited film 32 is formed on the surface of a single layer (referred to as a surface layer) 31, and a protective coating 33 is further provided on the metal vapor deposited film 32.

Alternatively, as shown in FIG. 4, roughened layers 31 are bonded to both sides of a base layer 34 made of a thermoplastic film, and a metal vapor deposited film 32 and a protective coating 33 are formed on the surface of one roughened layer 31.
It is made of a laminated structure.

The base layer 34 is made of the same synthetic resin as the rough surface layer 31, and a biaxially stretched film is preferable because it generally has greater mechanical strength and less permeation of moisture and oxygen than an unstretched film. .

The laminate of the rough surface layer 31 and the base material layer 34 shown in FIG. 4 can be obtained by stacking the respective stretched films of the rough surface layer 31 and the base material layer 34 and joining them by means such as dry lamination, or It is manufactured by extrusion laminating a molten synthetic resin containing a filler on the surface of the base material layer 34 stretched in one direction, and stretching the obtained laminate.

In order to improve the bonding between the rough surface layer 31 and the base material layer 34, a small amount of fine filler, for example, about 0.1 to 20 weight φ, may be added to the base material layer 34 before stretching.

On both sides of a 40 μ thick base layer film made by extruding molten polypropylene with a melt index (M・■) of 0.8 and stretching it 5.5 times in the machine direction, 70% polypropylene with an M・■ of 4.0 by weight, A molten composition prepared by mixing 15 parts by weight of talc and 15 parts by weight of titanium oxide was extruded and laminated, and these were stretched 7.5 times in the transverse direction to form a 20 μ thick rough film on each side of the base layer film. A surface layer film is formed, and then a metal vapor deposited film of aluminum having a thickness of about 5 μm is formed on one surface of this rough surface layer by a conventional method.

The reason why a metal vapor deposited film is formed on at least the outer rough surface layer of the stretched film is that when a metal vapor deposit film is formed on the inner rough surface layer, the electrolyte that leaks out reacts with the metal vapor deposit film, causing pinholes. occurs and moisture permeability decreases.

Therefore, it is necessary to form a metal vapor deposition film on the outer rough surface layer.

When a metal vapor deposited film is formed on the outside, the leaked electrolyte stops inside the stretched film and does not reach the metal vapor deposited film, so that the properties unique to the metal vapor deposited film can be maintained for a long period of time.

The results of measuring the mechanical properties and gas permeation of the film A according to the present invention and the unstretched polypropylene film B obtained in this manner show that the tensile properties etc. are good as in the following film A according to the present invention. When the film is wound, the film can be wound tightly, and the overlap between the films and the overlap between the synthetic resin film and the absorbent paper can be firmly adhered to each other. Since it is small, the electrolyte blocking effect is enhanced, and it is also possible to effectively prevent evaporation of battery moisture during storage, thereby suppressing performance deterioration due to storage.

Furthermore, since the amount of oxygen permeation is small, the storage life of the dry battery is improved.

In other words, when storing a dry battery, the zinc electrode is placed in an electrolyte (
It self-depletes by causing the reaction shown in equation 1), but in the presence of oxygen, the hydrogen in equation (1) is consumed by the following equation (2), so the reaction in equation (1) is accelerated. Ru.

The generated Zn reacts with the electrolytes NH and Ct to produce poorly soluble zinc diamine chloride Zn(NHa)2C12 as shown in equation (3), and when this product accumulates, it Internal resistance increases and battery performance deteriorates.

Therefore, a battery using the film according to the present invention can effectively prevent oxygen from entering and improve the shelf life of dry batteries.

The synthetic resin cylinder according to the present invention can be used alone in the form of a cylinder wrapped with a synthetic resin film 30 as shown in Figs. 3 and 4, or as shown in Figs. 5 to 7. It is also possible to use a combination of the synthetic resin film 30 and the absorbent paper 35.

The dry batteries shown in FIGS. 5 and 6 are made of a zinc can 41 in which a separator 36, a depolarization mixture 37, a carbon rod 38, a top cover paper 39, etc. are filled, and the opening is closed with a synthetic resin sealing body 40. On the outside, absorbent paper 35 made of kraft paper is spirally wound into a cylindrical shape, and a wide synthetic resin film 30 shown in FIG. The upper end of the composite body is wrapped around the periphery of the anode terminal plate 43, and the lower end thereof is wrapped around the periphery of the cathode terminal plate 44.

The liquid-absorbing paper 35 has both the function of absorbing and retaining the electrolytic solution leaked outside the zinc can 41 and the function of firmly wrapping the anode terminal plate 43 and the cathode terminal plate 44 of the composite body 42. ing.

The synthetic resin film 30 is made by applying an adhesive such as polyvinyl acetate, ethylene-vinyl acetate copolymer, or synthetic rubber to the rough surface layer 31 on the side where the metal vapor deposited film 32 is not formed, and processing this into a cylindrical shape. Wrap it around the outside of the absorbent paper 35 and glue it.

Further, a desired design or trademark is printed on the surface of the metal vapor deposited film 32 disposed on the outer surface, and a protective film 33 made of synthetic resin is further formed thereon.

This protective coating 33 prevents the metal vapor deposited film 32 from being scratched when the upper and lower ends of the composite body are rolled up.

As shown in FIG. 7, the metal vapor deposited film 32 and the protective coating 33 are not formed on the overlapping parts on both sides of the synthetic resin film 30, but if the rough surface layers 31 at the overlapping parts are adhered to each other, leakage can be prevented. effective.

The following Table 2 shows the results of a leakage test for a single-type dry cell C of the present invention shown in FIG. 5 and a conventional dry cell of the same type using the insulating tube shown in FIG.

The leakage rate in the table indicates the rate at which leakage was observed outside the dry cell when each sample dry cell was continuously discharged.

It can be seen that under such severe discharge conditions, conventional dry cell batteries often leak electrolyte to the outside, but dry cell C according to the present invention has a small leakage rate and is excellent in leakage resistance.

Table 3 shows the rate of deterioration of the discharge capacity when the sample batteries C and D were stored at 45°C.

From this table, it can be seen that the dry battery C according to the present invention has excellent storage stability because the amount of moisture dissipated within the battery and the amount of oxygen gas intruded are extremely small.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view of a conventional battery, FIG. 2 is an enlarged sectional view of an insulating tube used in the battery, FIGS. 3 and 4 are enlarged sectional views of a synthetic resin film according to the present invention, and FIG. FIGS. 6 and 7 are half-cut sectional views of the dry battery according to the invention, and are enlarged sectional views of essential parts of the battery. 30...Synthetic resin film, 31...
Rough surface layer, 32... Metal vapor deposited film, 33...
- Protective coating, 34... base material layer.

Claims (1)

[Claims] 1. A synthetic resin cylinder with a metal vapor-deposited film formed on at least the outer rough surface layer of a stretched film made of a thermoplastic synthetic resin containing a filler to reduce moisture permeability is attached to a zinc can containing a power generation element. A dry battery that is wrapped and fastened on the outside.