JPS636996B2 - - Google Patents

Description

[Detailed description of the invention]

In so-called alkaline batteries that use an alkaline electrolyte mainly composed of sodium hydroxide or potassium hydroxide, the present invention eliminates alkaline liquid leaking from inside the battery by spraying a cresol lead solution on the battery sealing part and its surroundings. inspect,
The object of the present invention is to provide a method that can easily determine a leaking battery and the degree of leakage thereof. As an example, a button-type silver oxide battery will be described. In recent years, button-type silver oxide batteries have come into widespread use as power sources for electronic wristwatches, and among the various characteristics of the batteries, there is a strong demand for improved leakage resistance. Conventionally, the method for determining leakage of this type of battery is 10
The battery was magnified with a ~20x microscope, and leakage was visually determined by the presence or absence of alkali wetting or white carbonate crystals in or around the sealing part. However, such visual determination not only differs from person to person, but also dust and foreign objects attached to the battery are often incorrectly determined as leaking fluid. In other examples, a litmus test paper moistened with water was brought into contact with the sealing part, and leakage was determined based on the discoloration of the paper.
In this example, if too much water is applied to the litmus paper, water droplets will come into contact between the positive and negative terminals of the battery, causing electrolysis of the water, which will cause problems such as discoloration of the litmus paper due to the pH change. It was hot. The present invention provides a method for determining leakage of alkaline batteries that improves the above-mentioned drawbacks by spraying a cresol red solution in the form of ultrafine mist onto the battery sealing part. This will be explained in detail below using examples. Cresol Red is an indicator that has two PH color change ranges. Here, in order to detect alkali (basic compounds), the color change from yellow to red in the high PH color change range (PH 7.2 to 8.8). The purpose is to determine whether there is a leak. Cresol Red dissolves in water and ethanol, but it is well known that it is more soluble in ethanol. It is also well known that the discoloration of cresol red due to alkali is sharper when the concentration of cresol red is low. Here, we first determined through experiments a mixed solvent composition of water and ethanol that has high alkali detection sensitivity and is less likely to cause the electrolysis of water as in conventional examples. Table 1 shows the results. Experiments were conducted using various mixed water and ethanol solvents at a cresol concentration of 0.05% by weight, which has high alkali detection sensitivity. The indicator solution was intentionally brought into contact with both the positive and negative terminals of the battery, the location where electrolysis occurred was designated, and the time until the cresol indicator changed color was measured.

[Table] From the above experiment, it can be seen that a composition in which the cresol changes color within 30 seconds to 90 seconds is suitable. This is because if electrolysis occurs in 30 seconds or less, the time required for determination is too short, and if the composition takes 90 seconds or more, the alkali detection sensitivity of cresol is poor. Based on the above experiment, the weight ratio of ethanol in the solvent is
Cresol red concentration 0.0001 with a composition of 30-70%
When the detection sensitivity in alkali was investigated at a concentration of ~1% by weight, the best detection sensitivity (ease of understanding discoloration) was found to be in the range of 0.001 to 0.5% by weight. From these experiments, the cresol red concentration
It was found that a mixed solvent composition of 0.001 to 0.5% and a water:ethanol weight ratio of 70:30 to 30:70 is suitable for the intended leakage test. Apply these solutions to a silver oxide battery SR44W using a commercially available sprayer.
When sprayed on the sealing part and its surrounding area, the results shown in Table 2 below were obtained.

【table】

[Table] In Table 2, ○ indicates normal, △ indicates minute liquid leakage, and × indicates liquid leakage. K ⁺ was detected by spectroscopic analysis of the sealing part and surrounding area of the battery. This result shows that the method of the present invention provides a judgment that is stricter than visual inspection (x20) and extremely close to the results of spectroscopic analysis. Regarding spraying, various mist conditions were tested, and the detection sensitivity was highest for the smallest possible mist. This is thought to be because the probability of short circuit due to the indicators of the positive and negative electrodes is reduced. Furthermore, although we have described SR44W as an experimental example, similar results were obtained with cylindrical alkaline batteries and other mercury batteries, providing an easy and highly accurate method for determining leakage with no individual differences in determination. can.

Claims (1)

[Claims] 1. Spraying a cresol red solution on and around the battery sealing part of a sealed alkaline battery that mainly uses sodium hydroxide or potassium hydroxide aqueous solution as an electrolyte, and determining whether or not the sprayed solution changes color. A method for determining leakage of alkaline batteries, characterized by determining leakage of batteries. 2 The cresol dissolved concentration of the cresol red solution is 70:30 to 30 in weight ratio of water and ethanol.
The method for determining leakage of alkaline batteries according to claim 1, wherein the amount is 0.001 to 0.5% by weight based on the mixed solvent of 70%.