JPH0146993B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to alkaline batteries such as silver oxide batteries, mercury batteries, and alkaline manganese batteries, and provides an alkaline battery that prevents leakage of alkaline electrolyte and has good storage performance. Alkaline batteries generally have a sealing structure as shown in FIGS. 1 and 2, in which an insulating packing 2 and a sealant 4 are placed between a cathode sealing plate 1 containing a cathode active material 5 and an anode container 3. The anode container 3 is formed by caulking the upper side of the anode container 3 inward to seal it. Polyamide, asphalt pitch, microcrystalline wax, fluorine resin, silicone oil, etc. have been used as sealants, and have achieved some degree of effectiveness. However, even with the use of these sealants, a fully satisfactory sealing effect could not be obtained. In particular, when a leaking battery was disassembled, the copper surface of the sealing portion of the cathode sealing plate was found to be amalgamated. In other words, this shows that alkali is passing over the copper surface. As a result of extensive research to solve the above conventional drawbacks, we have found that a sealant can be obtained by addition or condensation polymerization of an epoxy monomer or epoxy resin and an amine or polyamine so that an amine group remains at the end of the molecule. Epoxy adduct polyamide amines are suitable, especially as shown in the chemical formula below:
It has been discovered that apoxy adduct polyamide amine, which is obtained by polymerizing an epoxy resin containing a bisphenol A group in its molecular main chain with an amine, is particularly suitable. The epoxy adduct polyamide amine also improves the spread of the encapsulant on the copper surface. That is, in order to reduce the surface energy of the sealant and improve its wettability so as to sufficiently penetrate the irregularities of the cathode sealing plate, the above-mentioned epoxy adduct polyamide amine was mixed with isopropyl alcohol having a boiling point of 80°C to 150°C. To prevent liquid leakage, dilute the solution with a mixed solvent containing alcohol and at least one type of aromatic hydrocarbon such as toluene or xylene to a viscosity of 20 to 4000 cps, apply it to the cathode sealing plate, and dry it. I have come to find out what is good for me. The reason why the boiling point is set to 80°C to 150°C and the viscosity is set to 20 to 4000cps is as follows. That is, if the boiling point is less than 80°C, the solvent will scatter quickly, and if it exceeds 150°C, the solvent will remain in the sealant, resulting in insufficient drying. Furthermore, the viscosity
If it is less than 20cps, the sealing layer will be thinner and the leakage rate will be poor, and if it exceeds 4000cps, the sealing layer will be thicker.
Assembly becomes difficult. Therefore, the boiling point is 80℃~150℃,
Preferably, the viscosity is between 20 cps and 4000 cps. Next, the present invention will be specifically explained based on examples. (Example 1) 100 parts of epoxy adduct polyamide amine, which is a polycondensate of bisphenol A type epoxy and diamine, having an actual weight average molecular weight of about 380, was mixed with a mixed solvent of 7 parts of toluene and 3 parts of isopropyl alcohol.
The solution was diluted with 150 parts to a viscosity of 20 cps (at 25°C) and applied to a cathode sealing plate and dried to produce 50 alkaline batteries using the sealant as a sealant. (Example 2) 100 parts of the same epoxy adduct polyamide amine as in Example 1 was mixed with 100 parts of the same solvent to a viscosity of 1250 cps (25
Fifty alkaline batteries were manufactured using a sealant diluted to 100°C (°C) and applied to a cathode sealing plate and dried. (Example 3) 100 parts of the same epoxy adduct polyamide amine as in Example 1 was mixed with 70 parts of the same solvent to a viscosity of 4000 cps (25
Fifty alkaline batteries were manufactured using a sealant diluted to 100°C (°C) and applied to a cathode sealing plate and dried. (Example 4) 100 parts of the same epoxy adduct polyamide amine as in Example 1 was diluted with 90 parts of a mixed solvent of 7 parts of xylene and 3 parts of butanol to a viscosity of 1200 cps (at 25°C), which was applied to a cathode sealing plate and dried. Fifty alkaline batteries were manufactured using this as a sealant. (Comparative Example) Fifty alkaline batteries were manufactured using asphalt pitch as a sealant. The batteries of each example were tested at a temperature of 45°C and a humidity of 90% for 1500 hrs.
Table 1 shows the results of visual inspection for leakage after standing for a period of time. In addition, if the viscosity exceeds 4000 cps,
The assembly dimensions of the battery were out of specification, the sealant protruded, and it was not possible to conduct a leakage test. In addition, we found that when the viscosity was less than 20 cps, some liquid leaked during assembly, and some leaked 100% after several tens of hours.

[Table] From the above results, it is important to have a layer of epoxy adduct polyamide amine on the copper surface of the cathode sealing plate to prevent copper amalgamation in order to prevent leakage of alkaline batteries. Because of its low viscosity, it is easy to displace air bubbles on the uneven surface of the cathode sealing plate to be coated, and because it has good fluidity, it is possible to spread the liquid and apply a thin film. In addition, by coating the cathode sealing plate with a low viscosity and drying it, the copper surface of the cathode sealing plate is filled with a layer of epoxy adduct polyamide amine, which prevents amalgamation of the copper surface and reduces leakage. I was able to create a battery. As described above, the present invention has great industrial value in that it can provide an alkaline battery with less leakage.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional alkaline battery, and FIG. 2 is an enlarged sectional view of a sealed portion of the battery. 1...Cathode sealing plate, 2...Insulating packing, 3
... Anode container, 4 ... Sealing agent (layer of epoxy adduct polyamide amine), 5 ... Cathode active material.

Claims (1)

[Claims] 1 Epoxy adduct polyamide amine, which is a polycondensate of bisphenol A type epoxy resin and diamine, is reduced to a viscosity of 20 to 20 with a mixed solvent of alcohol and aromatic hydrocarbon with a boiling point of 80 to 150 °C.
A method for producing an alkaline battery, which comprises applying a solution diluted to 4000 cps on a cathode sealing plate and drying it, and interposing a layer of epoxy adduct polyamide amine between the cathode sealing plate and insulating packing.