JPH07122269A - Manufacture of positive plate for paste type lead battery - Google Patents

Abstract

PURPOSE:To improve the strength of an unformed plate in a paste type lead battery. CONSTITUTION:After reaction by adding water and dilute sulfuric acid to lead oxide mainly composed of minium, sulfate of alkali metal or alkali earth metal and lead oxide mainly composed of lead monoxide are added to this reacting lead oxide, to produce a paste-shaped substance by kneading. The paste-shaped substance is applied to a lattice unit consisting of lead or lead alloy, to perform aging and drying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a paste type lead battery positive electrode plate.

[0002]

2. Description of the Related Art Generally, the positive electrode plate of a paste type lead battery is
A lead oxide mainly composed of lead monoxide, so-called lead powder, is kneaded with water and dilute sulfuric acid to prepare a paste, which is applied to a grid body made of lead or a lead alloy, and then aged, dried and formed. It is manufactured by Here, it is generally known that when a paste is prepared by mixing lead oxide with lead oxide mainly containing lead monoxide, so-called lead powder, the chemical conversion efficiency is increased. Was difficult.

When lead oxide is mixed, the binding force between the active material particles is lowered during the chemical conversion, so that the active material particles are easily peeled off and the life of the positive electrode plate in cycle service is shortened. In order to significantly improve the conversion efficiency by mixing lead tin oxide, the mixing ratio must be several tens% or more of the total lead oxide, resulting in a significant increase in raw material cost. Almost all of the added sulfuric acid reacts with lead monoxide to form tribasic lead sulfate as a reaction product, that is, red tin oxide hardly reacts with sulfuric acid and remains in the paste as it is. Therefore, the particles of lead tin, which have a relatively large particle size and are poor in the binding force between particles, reduce the binding force between particles of the non-active material and between the non-active material and the lattice, and particularly, The decrease in the bonding force between the unformed active material and the lattice significantly reduces the strength of the unformed electrode plate during handling. The above-mentioned problem can be solved by previously reacting lead oxide with dilute sulfuric acid and then adding it (JP-A-4-355055), but the effect is not always sufficient with this method.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to a paste type lead battery positive electrode plate which prevents a decrease in strength of an unformed electrode plate due to the mixing of lead oxide and prevents the unformed active material from falling off during handling. It is intended to provide a manufacturing method.

[0005]

In order to achieve the above object, in the present invention, lead monoxide and red lead which have been previously reacted with dilute sulfuric acid are kneaded with water or dilute sulfuric acid, and sulfuric acid is added thereto. It is characterized in that a sulfate of an alkali metal such as sodium or magnesium sulfate or an alkaline earth metal is added.

[0006]

In the present invention, red lead is added as a mixture of lead dioxide and lead sulfate after the reaction with sulfuric acid is completed. Further, since the alkali metal or alkaline earth metal sulfate is added, the paste has high ionic conductivity. Therefore, lead dioxide and the lead or lead alloy of the lattice come into contact with the interface between the applied paste and the lattice, and the atmosphere around it has high ionic conductivity. The redox reaction chemically progresses rapidly, and the resulting lead monoxide chemically bonds lead dioxide to lead or a lead alloy. The reason why the strength of the unformed electrode plate is not sufficiently obtained when the alkali metal or alkaline earth metal sulfate is not added (JP-A-4-355055) is probably that lead dioxide serves as an oxidizing agent, It seems that the reaction between the two is difficult to proceed simply by contacting with the lead or the lead alloy in the lattice. The reason for adding an alkali metal or alkaline earth metal sulfate is not only that it imparts high ionic conductivity to the paste and that these salts do not adversely affect the lead battery, but in particular, the alkali metal sulfate is This is because the pH of the paste is increased and the solubility of lead or lead alloy in the lattice is increased so that the bond strength with the paste is easily obtained.

[0007]

EXAMPLE An example of the present invention will be described. First, 0.45 kg of red lead is sufficiently dispersed in 185 ml of water. Subsequently, dilute sulfuric acid (specific gravity: 1.260 at 20 ° C.) 375
Add ml. At this time, cooling and control of the dilute sulfuric acid feeding rate are performed so that the reaction temperature becomes a substantially constant temperature of 40 to 45 ° C. Next, 6.42 g of sodium sulfate was dissolved in this slurry-like substance, and this was mixed with lead powder 2.5 having an oxidation degree of 75%.
A paste is prepared by kneading while adding to 5 kg.
This paste was applied on a flat plate made of a lead-calcium alloy and a 55D23 type lead battery grid, and then aged and dried according to a conventional method.

Table 1 shows the results of evaluation of the bond strength between the flat plate made of the lead-calcium alloy and the unformed active material after the aging and drying by the shear peeling test. For comparison with the case of the present example, when lead oxide is directly kneaded with lead monoxide (prior art), lead oxide previously reacted with dilute sulfuric acid is kneaded with lead monoxide, and sodium sulfate is not added. The case (comparative example) is shown. As can be seen from Table 1, the binding force of this example was improved to about 3 times that of the conventional example and the comparative example.

[0009]

[Table 1]

FIG. 1 shows the results of evaluating the binding strength between the 55D23 type lead battery grid made of a lead-calcium alloy and the unformed active material after aging and drying by a drop strength test. For comparison with the case of the present example, when lead oxide is kneaded with lead monoxide as it is (prior art), lead oxide previously reacted with dilute sulfuric acid is kneaded with lead monoxide and sodium sulfate is not added. The case (comparative example) is shown. As can be seen from FIG. 1, the strength of the unformed electrode plate is greatly improved in this example, and the cause is that the bonding force between the unformed active material and the lead alloy shown in Table 1 is greatly increased. It is thought that this is due to improvement.

[0011]

As described above, according to the method of manufacturing the positive electrode plate of the lead type lead acid battery of the present invention, the bonding force between the unactivated material and the lattice is significantly improved, and the strength of the unformed electrode plate is increased. Can be greatly improved, and by this, almost no loss of the unformed active material during handling of the unformed electrode mixed with lead tin can be eliminated, which is a great industrial value.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a result of a drop strength test of an unformed electrode plate in an example of the present invention.

Claims (1)

[Claims] 1. A lead oxide mainly composed of red lead, water and diluted sulfuric acid are added and reacted, and then a sulfate of an alkali metal or alkaline earth metal and lead mainly composed of lead monoxide are added. Add an oxide and knead to produce a paste-like substance,
A method for producing a paste-type lead-acid battery positive electrode plate, comprising applying the paste-like substance to a grid body made of lead or a lead alloy, aging and drying.