JPH053707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> This invention relates to a method for manufacturing a separator used in silver oxide batteries and the like.

<<Prior art>> For example, in a silver oxide battery, silver oxide dissolves in an alkaline electrolyte and migrates to the zinc side of the negative electrode, and zinc precipitates into dendrites or sponges during charging and discharging and penetrates the separator. There is a risk of an internal short circuit. Therefore, the ability to prevent internal short circuits is particularly important for separators for silver oxide batteries. A separator is needed that prevents internal short circuits, provides passage for ions, and is oxidation and alkali resistant.

In order to satisfy the above requirements, in general silver oxide batteries, a separator is made of a stack of multiple types of microporous or semipermeable films. Examples of the film used include cellophane and processed products thereof, polyethylene and polypropylene crosslinked or graft-polymerized by radiation treatment or chemical treatment, porous vinyl chloride membranes, porous polyethylene membranes, and the like.

Conventionally, separators made by laminating multiple types of films have been manufactured by the following method. Pull out two or more long films from the rollers, stack them closely together so that no air is trapped between them, and press them together with the rollers (usually without using adhesive). ) This polymerized film is continuously fed to a punching device and punched out with a circular punch to obtain a circular separator.

<<Problems to be Solved by the Invention>> Conventionally, a plurality of films were simply stacked and crimped and then punched out, which often resulted in poor punching. In particular, when a graft polymer film and cellophane are stacked on top of each other, misalignment is likely to occur during feeding by rollers. This is because the graft polymer film becomes sticky due to moisture in the air, and the surface that is attached to the cellophane slips, causing misalignment of feed. If a feed misalignment occurs, wrinkles will occur, resulting in poor punching. Furthermore, a slight error in the punching can cause the two films to peel off or slip, resulting in fewer separators that can be neatly punched out in a circular shape while remaining neatly stuck together. In other words, the yield was poor, and the operating rate of the punching device was also worsening due to problems.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to eliminate processing defects when stacking a cellophane film and a multilayer graft film and punching them into a predetermined shape with a punch, and to improve the running performance of a punching device. The goal is to reduce costs.

<Means for Solving the Problems> The method for manufacturing a battery separator according to the present invention involves overlapping a cellophane film and a multilayer graft film, and feeding the polymerized film while sandwiching it between embossing rollers without heating. The method is characterized in that a large number of unevenness having a depth of 0.04 to 0.07 mm is formed on the polymeric film, and the embossed polymeric film is punched into a predetermined shape.

≪Operation≫ By forming a large number of unevenness by embossing on the polymer film, which is made by overlapping a cellophane film and a multilayer graft film, the adhesion between each film is extremely high, and the films will not slip and wrinkle when being fed by a roller. This eliminates the possibility of the occurrence of scratches or peeling of the film during punching.

<<Example>> The figure shows an example of the manufacturing method according to the present invention. In the figure, 10 is cellophane film, 12
is a multilayer graft film (trade name: permion), which is wound around rollers 14 and 16, respectively, and is pulled out sequentially in the direction of the arrow, and is overlapped by overlapping rollers 18, 22, 20, and 24,
It is sandwiched between a pair of embossing rollers 26 and 28. Both films 10 and 12 are not heated before and after the overlapping and between the embossing rollers 26 and 28.

The circumferential surfaces of the embossing rollers 26 and 28 are formed with corrugated patterns corresponding to each other, and the polymeric film 10 is formed between the circumferential surfaces of the rollers 26 and 28.
and 12 and rotates in the direction of the arrow to form a large number of irregularities on the polymerized films 10 and 12 while feeding them.

After embossing, the polymerized films 10 and 12 are fed to a punching device 30, and circular separators 32 are punched out one after another by the punching device 30.

The uneven pattern formed by embossing may be linear, dot-shaped, or in any other form. However, the depth d (see figure) of the unevenness formed on the polymerized film should be in the range of 0.04 to 0.07mm, and if the depth d of the unevenness is less than 0.04mm, both films 10 and 12 will Not much effect on improving adhesion can be expected, resulting in peeling and poor punching. Moreover, if the depth d of the unevenness is larger than 0.07 mm, pinholes are likely to occur in the film 10 or 12, resulting in defects in the basic performance as a separator.

Depth d of unevenness due to embossing is 0.04 to 0.07
In the range of mm, sufficient adhesion between the films can be obtained to eliminate punching defects, and no pinholes are observed due to embossing.

<<Effects of the Invention>> As explained in detail above, according to the method for manufacturing a battery separator according to the present invention, when a cellophane film and a multilayer graft film are stacked and punched into a predetermined shape, peeling and wrinkles between the films can be prevented. etc., the occurrence of punching defects is almost eliminated,
The yield of this process is much higher than in the past, and there are almost no problems with the punching device, making it possible to reduce running costs.

Furthermore, since the embossing process applied to the separator has shallow irregularities, it is possible to eliminate pinholes.

[Brief explanation of drawings]

The figure is a process schematic diagram showing an example of the method for manufacturing a battery separator according to the present invention. DESCRIPTION OF SYMBOLS 10... Cellophane film, 12... Multilayer graft film, 26, 28... Embossing roller, 30... Punch device, 32... Separator.

Claims (1)

[Claims] 1. Layer a cellophane film and a multilayer graft film, and feed the polymerized film while sandwiching it between embossing rollers without heating to form a large number of irregularities with a depth of 0.04 to 0.07 mm on the polymerized film. A method for manufacturing a battery separator, which comprises punching the embossed polymer film into a predetermined shape.