JPH0794189A - Waterproofing method for carbon rod for dry battery - Google Patents

Abstract

PURPOSE:To provide a waterproofing method which is easy to handle and safety by immersing a carbon rod for a dry battery in oil which is heated and kept at a specified temperature for a specified time, then by heating at a temperature same as or higher than the temperature of the oil. CONSTITUTION:A carbon rod for a dry battery, which is baked but not yet waterproof treated is immersed in oil or paraffin wax heated and kept at 80-150 deg.C for 3-10 minutes, then taken out. The carbon rod is heated at a temperature higher than the temperature of the oil or paraffin wax for several hours. The carbon rod having high air permeability and satisfying the blind core test can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproofing method for carbon rods for dry batteries.

[0002]

2. Description of the Related Art Carbon rods for dry batteries are usually obtained by mixing and kneading graphite powder, tar, pitch, etc., and molding them into a rod shape, followed by firing with a waterproofing agent such as oil or paraffin wax. To be Conventionally, a dry battery having a structure in which gas generated inside the battery needs to escape to the outside of the battery requires a carbon rod having an air permeability of about 10 to 20 cc / min. For manufacturing, the carbon rod for a dry battery is immersed in a waterproof solution in which a waterproofing agent such as oil or paraffin wax is dissolved in a chlorine-based solvent or a petroleum-based solvent, and then these solvents are evaporated to remove a small amount of the waterproofing agent for the dry battery. A carbon rod was thinly and uniformly impregnated, or the above method was applied to partially change the waterproof concentration of the carbon rod for a dry battery (for example, JP-A-52-13630). Also, waterproofing with only oil or paraffin wax that does not use chlorine-based solvents or petroleum-based solvents will increase the proportion of waterproofing agents contained in the carbon rods for dry batteries, resulting in extremely low air permeability or using waterproofing agents. There was a problem that it was not uniformly impregnated. The method for measuring the air permeability will be described later.

[0003]

In the conventional waterproof method, since a chlorine-based solvent or a petroleum-based solvent is used as a solvent for the waterproof liquid, handling is not easy in terms of workability and safety, and there is a step of evaporating the solvent. Therefore, there was a problem that those recovery devices were necessary. Also, waterproofing with only oil or paraffin wax that does not use chlorine-based solvents or petroleum-based solvents will increase the proportion of waterproofing agents in the carbon rods for dry batteries, and the air permeability will be extremely small, such as 0 to 5 cc / min. There was a problem that it was damaged and the waterproofing agent was not uniformly impregnated.

The present invention is to solve the above-mentioned problems, and does not use a chlorine-based solvent or a petroleum-based solvent, and does not partially change the waterproof concentration of the carbon rod for a dry battery, and waterproofs the carbon rod for a dry battery. Since the concentration can be kept constant, the carbon rod for dry batteries has no directionality and high productivity, and the air permeability is 10 to 20 cc / min. The purpose is to provide a waterproofing method for carbon rods.

[0005]

The present invention relates to a method for waterproofing a carbon rod for a dry battery, in which the carbon rod for a dry battery is immersed in oil that has been heated and kept warm or paraffin wax that has been melted and kept warm so that the oil in the carbon rod for dry battery has Alternatively, it is taken out in a state where a small amount of paraffin wax is impregnated and heated at the same temperature as the heat retention temperature of the oil or paraffin wax or a temperature higher than the heat retention temperature.

[0006]

According to the present invention, once a small amount of oil or paraffin wax is impregnated on the outer periphery of the carbon rod for a dry battery, the decrease in viscosity of the oil or the dissolved paraffin wax is utilized, which is considered to be a capillary phenomenon. Due to the diffusion effect, the excess impregnated oil or paraffin wax is discharged, and the impregnated oil or paraffin wax is uniformly dispersed.

[0007]

The present invention will be described in detail below with reference to examples. In this embodiment, the outer diameter is 8φ (SUM-
(For Type 1 dry batteries), a carbon rod for fired unsealed dry batteries was used. In this example, the waterproof property was evaluated by a blind core test and air permeability. In the blind core test, a waterproof carbon rod for a dry battery is divided into two parts in the longitudinal direction, immersed in water and taken out, and then the water repellency is observed. For example, the shaded area in Fig. 1 is where the water is soaked in without being repelled. , That is, the part not impregnated with oil or paraffin wax. Also, the air permeability is JCAS-15-197.
Based on 1 (Standard of the Carbon Society), 4kg / cm ² compressed air is added to a waterproof carbon rod for dry batteries in a water tank, and the amount of air that permeates the inside of the carbon rod for dry batteries is measured. It is expressed as the amount of air that permeates into.

(Example 1) First, a fired carbon rod for a non-waterproof dry battery is dried at 105 ° C to 110 ° C for 1 hour to remove water. Then, cool the oil to be immersed to 80 ° C so that the temperature does not change,
The dried carbon rod for a dry battery is immersed for 5 minutes in an oil (Showa Shell Sekiyu KK industrial lubricating oil Vitrea Oil) which has been heated and kept at 0 ° C. and taken out. Next, the carbon rod for a dry battery is heated for several hours while maintaining the temperature of 80 ° C.
FIG. 1 shows the result of a blind core test of a carbon rod for a dry battery, which was soaked for 5 minutes but not heated. 80 in FIG.
FIG. 3 shows the results of the blind core test of the products heated at 80 ° C. for 1 hour, and FIG. 3 at 80 ° C. for 2 hours. Further, FIG. 4 shows the time change of the air permeability when the carbon rod for a dry battery taken out from the immersion was heated at 80 ° C.

From this example, when a carbon rod for a dry battery is immersed in oil heated and kept at 80 ° C. for 5 minutes and heated at 80 ° C. which is the same temperature as the oil keeping temperature,
As is clear from the blind core test, heating for 2 hours reveals that the oil is dispersed throughout the carbon rod for a dry battery. Further, as is clear from FIG. 4, the air permeability became almost constant at 14 cc / min after heating for 2 hours. As described above, in Example 1, the optimum heating time for heating the carbon rod for a dry battery, which is immersed in the oil heated and kept at 80 ° C. for 5 minutes, at 80 ° C. which is the same temperature as the oil is It was dispersed in the entire carbon rod for use for 2 hours in which the air permeability was 10 cc / min or more. However, the heating time varies depending on the type of oil, the heating temperature, and the heating temperature of the taken out carbon rod for a dry battery.

(Example 2) A paraffin wax (made by Nippon Oil Co., Ltd. 135) was prepared by cooling a carbon rod for a dry battery, in which water was removed as in Example 1, to 100 ° C in the same manner, heating and melting it at 100 ° C, and then preserving the temperature. 10 in ° F paraffin)
Soak for a minute and remove. Next, use 15 carbon rods for this dry battery.
Heat for several hours while maintaining a temperature of 0 ° C. FIG. 5 shows 10
Fig. 6 shows the results of a blind core test of a carbon rod for a dry battery which was soaked for a minute but not heated.
FIG. 7 shows the results of the blind core test after heating at 150 ° C. for 2 hours and FIG. 8 at 150 ° C. for 3 hours. In addition, 1 carbon rod for dry batteries taken out from the immersion
FIG. 9 shows the change over time in air permeability when heated at 50 ° C.

As described above, according to this embodiment, one carbon rod for a dry battery is placed in paraffin wax which is heated and melted at 100 ° C. and kept warm.
When immersed for 0 minutes and heated at 150 ° C., which is higher than the heat retention temperature of paraffin wax, the paraffin wax is dispersed over the entire carbon rod for dry batteries when heated for 3 hours, as is apparent from the blind core test. You can see that Further, as is clear from FIG. 9, the air permeability became almost constant at 13 cc / min after heating for 2 hours. As described above, in Example 2, the optimum heating time for heating the carbon rod for a dry battery, which was immersed in the paraffin wax which had been heated and melted at 100 ° C. for 10 minutes and heated at 150 ° C. which is higher than the heat retention temperature of the paraffin wax, was The paraffin wax was dispersed in the entire carbon rod for a dry battery, and the air permeability was 10 cc / min or more for 3 hours. However, the heating time varies depending on the type of paraffin wax, the heat retention temperature after heating and melting, and the heating temperature of the taken out carbon rod for a dry battery.

If the heat retention temperature of the oil or paraffin wax is too low, the viscosity becomes high and the permeability is poor, so that impregnation requires a long time. On the other hand, when the heat retention temperature is high, deterioration due to air oxidation is severe. Therefore, the insulation temperature is 80
A temperature of ~ 150 ° C is suitable. If the impregnation time is short, the required amount of oil or paraffin wax will not be impregnated. On the contrary, if the impregnation time is long, not only the outer peripheral portion but also the central portion of the carbon rod for dry batteries will be impregnated, and the impregnated amount of the waterproofing agent will be too large. As a result, the air permeability becomes extremely small, so it is necessary to determine the optimum time according to the situation.

[0013]

INDUSTRIAL APPLICABILITY As described above, the present invention provides a method for waterproofing a carbon rod for a dry battery, which does not use a chlorine-based solvent or a petroleum-based solvent, has a large air permeability, and has no problem even in a blind core test. It provides a waterproof method for obtaining carbon rods, and is easy to handle in terms of work and safety,
It is possible to realize a waterproof method for carbon rods for dry batteries, which has features such as simple manufacturing equipment, high productivity, and environmental friendliness.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of a blind core test in Example 1 of the present invention.

FIG. 2 is a diagram showing the results of a blind core test in Example 1 of the present invention.

FIG. 3 is a diagram showing the results of a blind core test in Example 1 of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between heating time and air permeability in Example 1 of the present invention.

FIG. 5 is a diagram showing the results of a blind core test in Example 2 of the present invention.

FIG. 6 is a diagram showing the results of a blind core test in Example 2 of the present invention.

FIG. 7 is a diagram showing the results of a blind core test in Example 2 of the present invention.

FIG. 8 is a diagram showing the results of a blind core test in Example 2 of the present invention.

FIG. 9 is a characteristic diagram showing the relationship between heating time and air permeability in Example 2 of the present invention.

Claims (1)

[Claims] 1. A carbon rod for a dry battery is immersed in an oil heated and kept at 80 ° C. to 150 ° C. or a paraffin wax heated and melted and kept warm for 3 to 10 minutes, and then taken out, and then the oil or paraffin wax is obtained. A method for waterproofing a carbon rod for a dry battery, which comprises heating at a temperature equal to or higher than the heat retention temperature of.