JPS63226880A - Unamalgamated dry cell - Google Patents

Abstract

PURPOSE:To attain the unamalgamation of a dry cell without practically impairing the cell discharge performance and stock performance by using a zinc can annealed at the specific temperature. CONSTITUTION:A zinc can 1 annealed at 250-400 deg.C is used. The annealing time may be such degree that the recrystallization of crystal grains can be sufficiently performed and is properly set within the range of 10min-2hr, for example. Accordingly, the crystal grains of the zinc can 1 are recrystallized, the distortion of the organization is removed, the crystal grains of zinc are unified, the local discharge of the zinc can is effectively prevented without performing the amalgamation process, and the zinc can can be uniformly consumed.

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a dry battery that does not have a battery, and more specifically, by improving the properties of a zinc can used as a negative electrode, it is possible to make it a battery that does not have a battery without deteriorating its performance. It also relates to dry batteries.

<Prior art> A positive electrode mixture made by kneading a mixed powder mainly composed of manganese dioxide with an electrolytic solution such as a zinc chloride solution or an ammonium chloride solution is passed through a paper separator coated with a starch paste and dried. Dry batteries that are housed inside a can are in high demand because they are cheaper than alkaline batteries and the like.

As zinc cans used in such dry batteries, those processed into a bottomed cylindrical shape by a so-called impact extrusion method are widely used.

However, for example, in the above-mentioned impact extrusion method, zinc pellets punched from a thickly rolled zinc plate are
Zinc cans are made by heating to around 0°C and then applying pressure to impact extrusion 1 in one step, so the zinc cans produced have large distortions in the internal crystal grains. and the zinc grains are unevenly distributed.

For this reason, the inner surface of the zinc can cannot be homogenized, the zinc can is likely to cause local discharge during storage or use, and the zinc can cannot be uniformly consumed and dissolved. In order to suppress this kind of local discharge in zinc cans and improve battery performance by improving uneven consumption, 3 to 5 mg of mercury is used per dry battery in current dry batteries, such as R20 type dry batteries. It is undergoing ice treatment. Such icing treatment involves adding mercury, for example, in the form of mercuric chloride (t-1gCβ2) to the starchy paste 1 to be applied to the paper separator, or electrolyzing it by mixing it into the positive electrode mixture. It is added in the same form to the liquid. This icing treatment makes it possible to homogenize the properties of the inner surface of the zinc can that is in contact with the outer surface of the positive electrode mixture, thereby suppressing the above-mentioned deterioration in performance.

<Problems to be Solved by the Invention> However, no matter what method of addition is used, if the ice treatment is performed as described above, mercury will be contained in the dry cell battery, even if only in small amounts. Nowadays, various environmental pollutions are becoming a problem, and there is a strong demand for dry batteries to be made battery-free.

Means for Solving the Problems> The gist of the dry battery of the present invention is that a zinc can annealed at 250 to 400°C is used.

The reason why the temperature of the annealing treatment is set in the above range is as follows.

That is, if the treatment temperature is lower than 250° C., the distortion of the crystal structure due to recrystallization of the crystal grains in the zinc can will not be removed and the crystal grains will not be uniform enough, and the desired effect will not be obtained. Furthermore, if the treatment temperature is higher than 400° C., the zinc can will soften due to the temperature increase and will no longer be able to maintain its shape, resulting in a significant degree of shape change.

Incidentally, the annealing time may be set to a level that allows sufficient recrystallization of the crystal grains depending on the annealing temperature, and may be appropriately set within a range of, for example, 10 minutes to 2 hours. [Effect] By using the above annealing treatment, the crystal grains of the zinc can are recrystallized, the distortion of the structure is removed, and the zinc crystal grains are made uniform, so that the above-mentioned ice It is possible to effectively prevent local discharge of zinc cans and to consume the zinc cans uniformly without chemical treatment.

<Example> Using a zinc can obtained by making cans of Zinc Berene 1~ by an impact extrusion method, this zinc can was annealed at 375 ° C. for 30 minutes, and then put into a dilute hydrochloric acid solution and subjected to the above annealing treatment. A series of steps were performed to remove the oxidized layer formed on the surface of the zinc can, followed by washing with water and drying. Using the zinc can made by this process, R20 as shown in the attached drawing
An amorphous dry battery (product A of the present invention) was produced. In this figure, 1 is a zinc can, 2 is a positive electrode mixture containing manganese dioxide as an active material, 3 is a synthetic resin upper sealing body placed at the opening of the zinc can, and 4 is press-fitted into the positive electrode mixture 2. A carbon rod, 5 a sealant, 6 a positive terminal plate, 7 a heat-shrinkable tube, and 8 a metal exterior can. Further, after annealing at 250°C for 2 hours, an R20 type non-permeable dry battery (invention product A') was assembled in the same manner as inventive product A, and then heated at 225°C for 2 hours.
After time annealing, R2 was applied to the product of the present invention in the same manner.
A type 0 non-permanent dry battery (comparative quantity B) was assembled. Next, R20 was prepared in the same manner except that a zinc can without the above annealing treatment was used.
R20, which is the same as comparative quantity C, except that the formless dry battery (comparative quantity C) was further subjected to the conventional freezing treatment with 4 mg of mercury.
Type dry cell batteries (comparative quantity D) were each made. Also, 375
Using a zinc can annealed at °C for 30 minutes in an inert gas atmosphere (e.g., nitrogen gas atmosphere), an R20 type non-toxic dry battery (invention product E) was manufactured in the same manner as the invention product A except that Had made. Furthermore, if annealing treatment is performed in such an inert gas atmosphere, an oxide layer will not be formed on the surface of the zinc can after this treatment, and the oxide layer removal treatment as in the case of product A of the present invention described above is not required. Become.

Discharge time when these six types of dry batteries were continuously discharged after manufacture at a test temperature of 20°C and a discharge resistance of 2Ω (final voltage 0.
9V), two intermittent discharges for 30 minutes each day with a discharge resistance of 2Ω (final voltage 0.9V), and a case of intermittent discharge of 4 hours a day with a discharge resistance of 10Ω (
The final voltage (1.0 V) is as shown in Table 1.

Note that the results of the discharge experiments in Table 1 and Table 2 below are the average values of five batteries for each dry cell.

Table 1 also shows the discharge time of these six types of dry batteries when they are continuously or intermittent discharged under the same conditions after being stocked at room temperature for one year, and the corrosion area of zinc cans after being stocked at room temperature for one year! (mg)
Shown in the table. In addition, the weight of each zinc can when manufacturing is approximately 1
The weight loss due to corrosion is shown as the average value of 50 batteries for each battery.

Tables 1 and 2 of Table 2 show that all of the battery performances of products A, A', and E of the present invention were as high as those of the amalgam-treated comparative weighing, and the corrosion loss after stocking was also comparable to that of the comparative weighing. It was demonstrated that the performance was kept low enough for practical use.

It is clear that similar effects can be obtained even if the present invention is applied to dry batteries using zinc cans made by other can manufacturing methods, such as deep drawing.

<Effects of the Invention> The dry cell of the present invention constructed as described above has the excellent effect of making the dry cell dry without substantially impairing battery discharge performance and stock performance. has great utility value.

[Brief explanation of the drawing]

The accompanying drawings are sectional views of essential parts of the embodiment. 1... Zinc can, 2... Positive electrode mixture.

Claims (1)

[Scope of Claims] 1. A non-toxic dry battery characterized by using a zinc can annealed at 250 to 400°C. 2. The non-toxic dry battery according to claim 1, wherein the annealing treatment is performed in an inert gas atmosphere.