JPS5843867B2 - Method for manufacturing separators for dry batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a separator for dry cell batteries, and is aimed at improving the separator manufacturing process, the paper hole dry cell manufacturing process, and battery characteristics.

Conventional dry battery separator (J1) After applying a sizing solution made by dispersing starch and a small amount of binder material in water or alcohol to kraft paper using a roller or the like, the paper is
It was manufactured by passing it through a hot air atmosphere at 20°C and drying it.

In such separators, the starch is only adhered to the paper by a small amount of binder, so the adhesion between the paper and the glue is poor, and the glue is removed when the separator is cut or inserted into the zinc can. The particles fell off the paper or were scattered as dust, which was unfavorable in terms of battery characteristics and the environment.

In addition, in recent years, dry batteries have been developed by transferring the electrolyte in the battery mixture to the separator side, instead of using glue-type dry batteries that heat the paste to form a paste. The mainstream is now shifting to paper-hole dry cells that can be turned into gels.

In a paper-hole dry cell, in order to achieve sufficient gelation of starch, the concentration of the electrolyte must be made high or the amount of the electrolyte must be made considerably abundant.

However, the former reduces the battery's high-load discharge performance, and the latter makes the battery mixture too soft, making the battery manufacturing process difficult, and an increase in the amount of electrolyte leads to a relative reduction in the amount of depolarizer. This results in a reduction in capacity.

As described above, in conventional separators, the gelation of starch is insufficient even with the electrolyte composition and amount of electrolyte that provides good battery performance, resulting in large voltage and current drops during storage and long-term discharge, especially in light It has the disadvantage that internal impedance increases significantly during load discharge.

In addition, as a separator using conventional pregelatinized starch, starch is mixed into boiling water and the starch is gelled.
There was one in which a separator was formed by making a viscous paste and applying it to kraft paper.

However, with separators manufactured in this way, the starch particles collapse due to excessive gelation of starch, and the viscosity of the size liquid itself becomes extremely high, making the coating process difficult, and the condition of the size liquid Since the starch is swollen and water is bound to the starch particles, the starch is prone to spoilage and the sizing solution has poor storage stability.

Furthermore, the drying efficiency in the drying process of the separator after applying this size liquid was also poor because the starch retained water.

In addition, the starch swells in the size liquid state, meaning that the particles swell and become larger and more fragile.

When applying using a size liquid application roller as shown in b and c, the starch particles collide with each other or are under pressure due to stirring by the roller until the size liquid is applied, which may cause the starch particles to break. However, a rapid increase in the viscosity of the paste occurred, making it difficult to control the manufacturing process.

In addition, in dry batteries using separators coated with broken starch particles, the starch loses its ability to retain electrolyte, and the electrolyte in the separator migrates to the mixture side during storage. Satisfactory results were not obtained.

The present invention (manufacture of a separator that has good characteristics as a separator and has excellent battery characteristics and paper-type dry battery manufacturing by gelling and gelatinizing starch at the same time as drying the fiber base material when manufacturing the J separator) The present invention provides a method.

An example of this will be described below.

3 parts of starch is added to a solution of a small amount, for example 2 parts by weight, of polyvinyl alcohol as a binder dissolved in 60 parts by weight of water.
The viscosity of the size liquid in which 8 parts by weight was dispersed was adjusted to within the range of 5 to 60 seconds by Ford cup measurement of 8 mm diameter, and the size liquid was applied to kraft paper, which is a fibrous material, using the device shown in the figure. Apply on one side.

The size liquid 5 injected into the patch 1 is pumped up by a roller C, and the excess size liquid is removed by a roller A, thereby determining the amount of size liquid to be applied.

Next, the size liquid on the roller C is transferred to one side of the rolled craft paper 3 that passes between the rollers C and B, and the application is completed.

The paper is passed through a drying and gelling step 2 of the glue before the moisture in the applied glue is absorbed into the kraft paper 3 side or evaporated, and then the paper is wound up with a take-up reroller 4.

The conditions in the drying and gelling steps and the form of the drying heat source shown in FIG. 2 are as follows.

(a) 70' (, -130°C) One side of Laurani Kraft paper that is not coated with the size liquid is brought into contact with it for 2 seconds or more to gel the starch. The starch is gelatinized and the separator is dried by heating to a temperature higher than that temperature.

(b) Blow hot air at 150 to 2508 C for 2 seconds or more from one side of the kraft paper on which the size liquid is not applied, and heat the size liquid to a temperature higher than the starch gelling temperature to pregelatize the starch and Dry the separator.

In this case, if hot air is blown onto the side to which the glue is applied, the water required for gelatinization of starch will be released more quickly and the gelatinization efficiency will deteriorate.

(C) A temperature atmosphere of 200 to 300° C. is created by infrared heaters arranged so as to face each other, and kraft paper coated with a size liquid is passed between the heaters.

The infrared heaters are placed on both sides of the separator, and placing more infrared heaters on the non-coated side is particularly effective in gelatinizing the starch.

Here, each heat source) is necessary to give the temperature required to gelatinize the starch. Normal starch gelatinizes at 50 to 70°C, but with a heating roller (470°C
Starch itself can be brought to pregelatinization humidity at 80 to 130°C, 150°C to 2500°C with hot air, and Gj 200'C to 300°C with an infrared heater.

Starch cannot be pregelatinized below the above lower limit temperature, and above the upper limit humidity the temperature of the separator rises too rapidly, causing the applied paste to boil, causing unevenness on the surface and the paper. The shrinkage of the separator is severe, and the separator is often wrinkled.

The separator thus obtained was cut according to the size of the dry battery, and placed so that the glue layer was in contact with the zinc can side.
An anode mixture consisting of 46 parts by weight of manganese dioxide, 11 parts by weight of acetylene black, 10 parts by weight of zinc chloride, 3 parts by weight of ammonium chloride, and 30 parts by weight of water was filled inside the separator, and a carbon rod was inserted into the center of the mixture. After that, the paper hole dry battery is manufactured by sealing the battery.

The paper hole dry battery separator formed in this way is
Since the starch is pregelatinized after the size solution is applied, unlike the conventional method of using a gelatinized starch solution, the size solution has good storage stability and is relatively easy to dry after application.

Furthermore, starch particles are almost never broken during the process of applying the size solution.

Furthermore, by gelatinizing the starch during drying, the adhesion between the starches and the paper is good, and the adhesive will peel off when cutting the separator or inserting it into a zinc can.
There are no problems with the environment or battery characteristics.

State of starch in the glue layer formed on one side of the separator t
1. In the conventional drying force method (1) when the starch particles are not pregelatinized and a gelatinized starch paste is applied, almost all the starch is in a state close to disintegration; Particle outlines are unclear.

However, in the present invention, the starch is gelatinized at the same time as the fiber and wood base material is dried, and as the starch gelatinization progresses, the water necessary for gelatinization decreases due to evaporation during drying, so the degree of gelatinization is reduced. (disintegration of starch) occurs, and starch particles that are easily gelatinized and those that are difficult to gelatinize are mixed in gelatinized and non-gelatinized forms to form a glue layer.

Therefore, when dry batteries are stored at high temperatures, ungelatinized starch forms a good gel layer, and when stored at room temperature or low temperatures, gelatinized starch forms a good gel layer, so they can be used in various environments. A compatible dry cell battery can be formed.

For comparison, Table 1 shows the conventional paper-hole dry cell A1 using a non-gelatinized glue layer, the conventional dry cell B1 using an isolation layer in which gelatinized starch is coated on one side of paper, and the product C of the present invention at room temperature. Table 2 shows the voltage and current values when stored at 45°C and 2Ω continuous discharge immediately after battery manufacture, at room temperature, and at 45°C.
shows the duration after storage at (end voltage 0.9V).

Furthermore, Table 3 shows the change in internal impedance during 500Ω continuous discharge when measured at a high frequency of IKHz.

As described above, the present invention can provide a separator that is excellent in the production of paper-hole dry batteries, and can provide dry batteries that use this separator with excellent discharge performance and storage performance.

[Brief explanation of drawings]

The figure is a schematic diagram showing the manufacturing process of a separator in an example of the present invention. 1... Batch, 2... Drying and gelling process, 3... Kraft paper, 4... Winding roll, 5... Glue liquid.

Claims (1)

[Scope of Claims] 1. A separator for a dry battery, characterized in that after applying a starch-based sizing liquid to one side of a fibrous base material, the starch is gelatinized simultaneously with drying of the fibrous base material. Production method. 2 Drying of the fibrous base material and gelation of starch
2. The method for producing a separator for a dry battery according to claim 1, which is performed by heating the fibrous base material from the non-size coating surface using a roller heated to 130°C. 3. The dry battery separator according to claim 1, which is achieved by drying the fibrous base material and gelling the starch, or by blowing hot air at 150 to 250°C onto the surface of the fibrous base material to which no glue has been applied. manufacturing method. 4 Drying of the fibrous base material and gelation of starch
2. The method of manufacturing a dry battery separator according to claim 1, wherein the fibrous base material is passed between opposing infrared heaters maintained in a temperature atmosphere of ~300°C.