JPH10275608A - Separator for alkaline zinc storage battery and alkaline zinc storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for an alkaline zinc storage battery, which is formed with a directly crosslinked type PVA film (polyvinyl alcohol) excellent in short-circuit resistance for a long time and ion permeability. SOLUTION: A separator for an alkaline zinc storage battery is formed with a directly crosslinked type polyvinyl alcohol film which is obtained through the swelling process wherein a polyvinyl alcohol film is swelled by dipping it in water, the radiating process wherein electron beam is applied to the polyvinyl alcohol film swollen with water to crosslink between polymer main chains and the drying process of drying the crosslinked polyvinyl alcohol film. In the swelling process, the polyvinyl alcohol film with a degree of polymerization of 1500 or more and a degree of saponification of 98% or more is dipped in water at 20-90 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an alkaline zinc storage battery using zinc as a negative electrode and an aqueous alkaline solution as an electrolyte.
For example, the present invention relates to a separator used for a nickel zinc storage battery, a silver oxide-zinc storage battery, a manganese-zinc storage battery, an air-zinc storage battery, and the like, and an alkali zinc storage battery using the separator.

[0002]

2. Description of the Related Art Alkaline zinc storage batteries have attracted attention in the past because they have high energy density, are inexpensive, and have good characteristics such as containing no substances harmful to the environment. However, there is a problem of short-circuiting due to zinc dendrite of the negative electrode, deterioration of the negative electrode due to change in the shape of the negative electrode, and short life, and as a result, it has not yet been widely used like iron electrodes It is.

[0003] In order to solve the above-mentioned problems, improvements have been made to separators. For example, non-woven fabric separator,
Using cellophane membrane, polyvinyl alcohol (hereinafter referred to as PVA) membrane, ion exchange membrane, alkali-resistant microporous membrane, etc., alone or in combination, as a separator to prevent the occurrence of short circuit based on zinc dendrite and extend the life Has been planned.

[0004] Among them, cellophane membranes are widely used because of their excellent hydrophilicity and ion permeability. However, the cellophane film has a drawback that it undergoes oxidative decomposition in an alkaline electrolyte and gradually deteriorates, and the short-circuit resistance to zinc dendrites decreases depending on the degree of deterioration.
This defect is considered to be due to the fact that the acetal bond in the cellulose polymer chain constituting cellophane is decomposed in the alkaline electrolyte, thereby cutting the cellulose skeleton.

[0005] Further, as a material similar to a cellophane film, PV is used.
A film is used. PVA membranes are useful because they do not contain acetal bonds in the polymer main chain and are excellent in alkali resistance, oxidation resistance, and hydrophilicity. However, PVA
Is essentially soluble in aqueous alkali, so PVA
If the membrane is placed in the electrolyte for a long period of time, there is a problem that PVA gradually elutes and the mechanical strength of the PVA membrane decreases, and the short-circuit resistance also decreases.

Therefore, in order to solve the above-mentioned problems of the PVA film, (i) heat treatment to improve the orientation and crystallinity of the PVA film, and (ii) chemical treatment using aldehydes or boric acid. To have a crosslinked structure.

[0007]

However, the above (i) and (ii)
The PVA membrane treated as described above is still insufficiently functional as a separator for an alkaline zinc storage battery, and has not yet been put to practical use.

That is, when the orientation and crystallinity of the PVA film are increased by the treatment (i), the initial short-circuit resistance of the PVA film is increased, but the sheet resistance is increased and the ion permeability is decreased. There's a problem. When such a PVA film is used as a separator for an alkaline zinc storage battery, the current distribution during charging and discharging becomes non-uniform, the shape change of the negative electrode is accelerated, and the battery capacity is reduced early.

When an aldehyde is used in the treatment (ii), the PVA film is crosslinked mainly by acetal bonds, and therefore becomes unstable to alkali, and maintains short-circuit resistance for a long period of time. It becomes difficult.

On the other hand, to improve PVA, there is known a technique of bringing PVA into a water-swelled state and irradiating it with an electron beam.
1975), and no detailed study on application to a separator or optimization has been made.

The present invention provides a separator for an alkaline zinc storage battery comprising a directly crosslinked PVA membrane having excellent short-circuit resistance over a long period of time and excellent ion permeability, and further uses such a separator. It is an object to provide an alkaline zinc storage battery.

[0012]

In order to achieve the above object, an invention according to claim 1 of the present application is a separator for an alkaline zinc storage battery comprising a directly crosslinked polyvinyl alcohol film, wherein the directly crosslinked polyvinyl alcohol film is provided. Is a swelling treatment step of immersing the polyvinyl alcohol film in water and swelling, an irradiation treatment step of irradiating the water-swollen polyvinyl alcohol film with an electron beam to crosslink between polymer main chains, and a crosslinked polyvinyl alcohol film. And a swelling treatment step in which a polyvinyl alcohol film having a degree of polymerization of 1500 or more and a degree of saponification of 98% or more is immersed in water at 20 to 90 ° C. I have.

The obtained directly cross-linked polyvinyl alcohol (PVA) film has a cross-linked structure in which an external element such as a cross-linking agent such as boric acid or aldehyde is interposed, and the polymer main chains are directly linked to each other. It is considered to have a crosslinked structure formed by carbon-carbon bond or carbon-oxygen-carbon bond.

Since the PVA film having the above degree of polymerization and saponification is used in the swelling process, the PVA film swells without being dissolved in water. However, the temperature of the swelling process is 9
Above 0 ° C., dissolution of the PVA membrane occurs. When the temperature is lower than 20 ° C., swelling hardly occurs.

[0015] Since the directly crosslinked PVA membrane is crosslinked by irradiating an electron beam in the irradiation treatment step, the crosslinked structure between the polymer main chains can be formed without passing through an external element such as a crosslinking agent. The main chains are directly carbon-carbon bonded or carbon-
It is considered to be an oxygen-carbon bond. Since these bonds are stable against alkali, the direct cross-linking type PVA membrane is stable against alkaline electrolyte when used as a separator of an alkaline zinc storage battery, and has a mechanical strength over a long period of time. Will be maintained. Therefore, when a separator made of a directly crosslinked PVA membrane is used, an internal short circuit caused by zinc dendrite penetrating the separator is prevented for a long period of time.

Further, since the direct cross-linking type PVA membrane is cross-linked in the irradiation step in a state of being swollen with water in the swelling step, the gap between the molecules in the molecular chain of the amorphous part is swollen with water. It is cross-linked in a state of becoming larger. For this reason, when the direct crosslinked PVA membrane is immersed in the electrolytic solution, water easily re-permeates and is included in the membrane, and has excellent water and ion permeability and low sheet resistance. Therefore, when the direct cross-linking type PVA membrane is used as a separator of an alkaline zinc storage battery, the current distribution during charging and discharging becomes uniform, so that the shape change of the negative electrode and the growth of zinc dendrites are suppressed, and the battery life is improved.

According to a second aspect of the present invention, in the first aspect of the invention, in the irradiation treatment step, the oxygen concentration is 1000 ppm.
The electron beam of 30 to 200 Mrad is irradiated under the following atmosphere. If the oxygen concentration is high, the decomposition reaction takes precedence over the crosslinking reaction of the PVA film, so the oxygen concentration is preferably 1000 ppm or less.

According to a third aspect of the present invention, in the first aspect of the present invention, the solids remaining without being dissolved after being immersed in boiling water for 5 minutes are dried at 60 ° C. for 1 hour. (Gel fraction) is 70% or more. When the gel fraction is 70% or more, the cross-linked structure of the direct cross-linking type is sufficiently provided to exhibit its characteristics.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the value of the amount of charged electricity when the battery is immersed in an alkaline aqueous solution at 60 ° C. for 40 days and then charged until a short circuit occurs is obtained. It is 70 mAh / cm ² or more. That is, high short-circuit resistance is maintained for a long time, and the reliability of the battery is improved.

According to a fifth aspect of the present invention, in the first aspect, the sheet resistance is 200 mΩ · cm ² or less. Since the sheet resistance is low, the current distribution during charge and discharge becomes uniform, the shape change of the negative electrode and the growth of zinc dendrite are suppressed, and the battery life is improved.

According to a sixth aspect of the present invention, there is provided an alkaline zinc storage battery using a directly crosslinked polyvinyl alcohol film as a separator, wherein the directly crosslinked polyvinyl alcohol film is swelled by immersing the polyvinyl alcohol film in water. Step, an irradiation treatment step of irradiating the polyvinyl alcohol film swollen with water with an electron beam to crosslink between polymer main chains, and a drying treatment step of drying the crosslinked polyvinyl alcohol film, In the swelling process, a polyvinyl alcohol film having a degree of polymerization of 1500 or more and a degree of saponification of 98% or more is immersed in water at 20 to 90 ° C.

In this alkaline zinc storage battery, the separator maintains high short-circuit resistance for a long period of time, so that the reliability is greatly improved. In addition, since the separator has high ion permeability, cycle life characteristics are improved. improves.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, a separator is used by combining a directly crosslinked polyvinyl alcohol film and a polyolefin microporous film coated with nickel powder.

In the above-mentioned polyolefin microporous membrane disposed so as to face the positive electrode, the precipitated zinc is oxidized and dissolved on the nickel powder, so that the formation of zinc dendrites is suppressed. Further, in the direct cross-linking type PVA film arranged to face the negative electrode, the short-circuit resistance is maintained for a long period of time, so that the growth of zinc dendrites is suppressed.
Therefore, when both films act synergistically, an internal short circuit is sufficiently prevented, and the reliability of the battery is sufficiently improved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

[Preparation of Direct Crosslinkable PVA Membrane of the Present Invention] The following swelling treatment step, irradiation treatment step, and drying treatment step were performed to obtain a separator for an alkaline zinc storage battery comprising the direct crosslinkable PVA membrane of the present invention.

Swelling treatment step: P having a thickness of 10 to 25 μm
The VA film was immersed in water at 80 ° C. for 18 hours to completely swell. Irradiation treatment step: The swollen PVA film is taken out, and is kept as it is on a support made of, for example, a polyethylene terephthalate film having a thickness of, for example, 50 μm.
The film was irradiated with an electron beam. As an irradiation device, an area beam type electron beam irradiation device “Curetron” (manufactured by Nissin High Voltage Co., Ltd.) was used. The irradiation conditions were such that the oxygen concentration was 1000 ppm or less at room temperature, the acceleration voltage was 200 kV, and the total dose was 10 to 200 Mrad. Drying process: After irradiation, the PVA membrane was removed from the support and dried.

With respect to the thus obtained separator for an alkaline zinc storage battery of the present invention, various characteristics were examined.

[Gel Fraction] The gel fraction of the PVA membrane is P
After immersing the VA membrane in boiling water for 5 minutes, it refers to the weight percent of the PVA solid remaining without dissolving after drying at 60 ° C. for 1 hour. It is a measure of the degree of crosslinking of the PVA membrane. FIG. 1 shows the gel fraction (%) and electron beam irradiation dose (Mra) of the directly crosslinked PVA film of the present invention and the comparative PVA film.
d). In addition, the PVA membrane of the comparative product was obtained by omitting the swelling treatment step in the product of the present invention. As can be seen from FIG. 1, in the comparative product, the gel fraction did not increase even when the dose was increased, and was hardly crosslinked. However, in the product of the present invention, the gel fraction was 70% in the region where the dose was 30 Mrad or more.
As described above, crosslinking occurs between the polymer main chains of PVA.

[Short Resistance] The following model cells were prepared, and the short resistance of the separator was evaluated. The short-circuit resistance refers to the amount of electricity charged until a short-circuit occurs, and is referred to as an SMC value.

(Model cell) A positive electrode, a negative electrode and a short sensor shown below were prepared and arranged as a positive electrode / nonwoven fabric / cellophane / short sensor / nonwoven fabric / separator / nonwoven fabric / negative electrode. Of potassium hydroxide solution to the extent that the electrode plate is completely immersed,
A cell was constructed, and the capacity density of the positive electrode was 30 mAh / cm ² ,
The capacity density of the negative electrode was set to 120 mAh / cm ² .

Positive electrode: A sintered nickel electrode mainly composed of nickel hydroxide, and the size of the electrode plate is 2 cm × 2 cm. Negative electrode: A current collector is a punching metal of copper having a thickness of 0.1 mm, and on both surfaces thereof, 80 parts of zinc oxide powder and zinc powder 2
A mixture of 0 parts and 3 parts of polytetrafluoroethylene particles is applied, the porosity is 50%, and the electrode plate size is 2 cm × 2 cm.・ Short sensor: Zinc oxide powder 1 on copper mesh
A mixed powder of 00 parts and 3 parts of polytetrafluoroethylene particles is applied, and has a porosity of 50% and a size of 2 cm × 2 cm.

(Evaluation 1) FIG. 2 shows the direct cross-linked P of the product of the present invention.
The relationship between the short-circuit resistance (mAh / cm ² ) of the VA film and the electron beam irradiation dose (Mrad) is shown. The product of the present invention was obtained by using a PVA film having a thickness of 12 μm as a base material and setting the total dose of electron beam irradiation to 100 Mrad. As can be seen from FIG. 2, the SMC value of the product of the present invention has increased about 20 times from 100 to 2100 without irradiation. On the other hand, in the comparative PVA film, a remarkable increase in the SMC value was not observed unlike the product of the present invention.

(Evaluation 2) A major problem of the conventional PVA film and cellophane film is that they are poor in alkali resistance. Therefore, when used in a high-concentration alkaline electrolyte, the mechanical strength and short-circuit resistance are remarkable. Is to drop. Therefore,
With respect to the direct crosslinked PVA film of the present invention, the PVA film of the comparative product, and the cellophane film, the change with time of the SMC value was examined.
That is, each film was left in an 8 mol / l potassium hydroxide electrolyte at 60 ° C., and the relationship between the number of days left and the SMC value was examined. FIG. 3 shows the result. As can be seen from FIG.
In any of the films, as the number of days of standing increases, the SMC value decreases. However, the SMC value of the product of the present invention was 40 days (2 at room temperature).
Even after this, the initial value of the cellophane film (7
0 mAh / cm ² ). That is, in the present invention,
High short-circuit resistance is maintained for a long time. By the way, in a battery using a cellophane film as a separator,
Although there is a high possibility that an internal short circuit will occur with long-term storage or charge / discharge, almost no internal short circuit will occur in the initial period after the injection. Therefore, it can be said that the product of the present invention, in which the SMC value after 40 days is higher than the initial value of the cellophane film, has high reliability over a long period against an internal short circuit.

The direct crosslinked PVA membrane of the product of the present invention is
When the SMC value after 40 days was examined under the same conditions by combining a polyolefin microporous membrane coated with nickel powder having the same dimensions, it was about 930 mAh / cm ² , and the SMC value of the directly crosslinked PVA membrane shown in FIG. It was found to be about three times the value.

By the way, the improvement of the SMC value corresponds to the increase of the gel fraction.
This is thought to be due to the result blocked by the three-dimensional network structure based on direct crosslinking between the polymer main chains of the VA membrane. Therefore, in order to improve short-circuit resistance, it is desirable that the gel fraction is 70% or more.

Each of the above evaluations was carried out when the water temperature in the swelling treatment step was set at 20 ° C., 60 ° C., and 90 ° C., but almost the same results were obtained.

[Membrane permeability of zinc ion] The membrane permeability of zinc ion, which is considered to be related to the growth of zinc dendrite, was evaluated for the separator in the following manner. That is, in one of the chambers of the H-type cell divided into two by the separator, 0.0.
An 8 mol / l potassium hydroxide aqueous solution containing 5 mol / l zinc oxide and a metal zinc electrode were installed, and 8 mol / l zinc oxide was placed in the other chamber.
A 50 mol / l potassium hydroxide aqueous solution and a metal copper electrode were provided, and after charging at 50 mAh / cm ² using the metal zinc electrode as a positive electrode, the amount of zinc deposited on the metal copper electrode as a negative electrode was measured. Table 1 shows the results along with other properties.

[0038]

[Table 1]

As can be seen from Table 1, the amount of zinc deposition, that is, the amount of zinc ion permeation of the direct crosslinked PVA film of the present invention is inversely proportional to the dose of electron beam irradiation, and decreases as the degree of crosslinking increases. And about 1/10 of the cellophane film,
There is not much difference from the PVA membrane of the comparative product. On the other hand, as described above and as shown in Table 1, there is a remarkable difference in the initial SMC value between the directly crosslinked PVA film of the present invention and the PVA film of the comparative product. Considering these facts, in order to prevent the growth of zinc dendrite, rather than suppressing the membrane permeability of zinc ions, a three-dimensional network structure based on direct cross-linking between polymer main chains of the PVA membrane is required. It can be said that the formation is more effective.

As described above, the direct crosslinked PV of the product of the present invention
The A film can suppress the permeability of zinc ions similarly to the PVA film of the comparative product, and has excellent short-circuit resistance as compared with the PVA film of the comparative product.

[Area Resistance / Ion Permeability] The sheet resistance and ion permeability of the directly crosslinked PVA membrane of the product of the present invention were evaluated as follows. That is, the sheet resistance is 8
The product of the present invention was inserted between platinum electrodes with platinum black in a mol / l aqueous solution of potassium hydroxide, and the increase in electric resistance (frequency 1 kHz) was measured. The ion permeability is
An aqueous potassium hydroxide solution was placed in one chamber of the H-type cell divided into two minutes with the product of the present invention, and water was charged in the other chamber, and the pH change was measured.

By the way, in an alkaline zinc storage battery using a separator having a high sheet resistance, the current distribution at the time of charging and discharging becomes non-uniform, so that the shape change of the zinc electrode is accelerated and the capacity is reduced at an early stage. For example, the sheet resistance is 350 mΩ · c
The alkaline zinc storage battery using a PVA film m ² as a separator, the cycle life was cut 80% of the initial volume at 30 cycles. In order to expect a cycle life of 200 cycles or more, the sheet resistance needs to be about 200 mΩ · cm ² or less.

In the direct cross-linking type PVA membrane of the present invention, the sheet resistance did not increase even after cross-linking by electron beam irradiation, and the permeability of potassium ions and hydroxide ions was improved. Furthermore, it has been found that the sheet resistance and the ion permeability are controlled by the temperature conditions in the swelling process, and may be further improved.

FIG. 4 shows the temperature (° C.) and the sheet resistance (mΩ · cm ² ) at the time of swelling of the directly crosslinked PVA membrane of the present invention.
And hydroxide ion permeability (hydroxide ion diffusion coefficient: m
ol / cm ² · sec). As the temperature increases, the sheet resistance decreases and the ion permeability increases. For example, when the temperature is 80 to 90 ° C., the sheet resistance and the ion permeability are at the same level as the cellophane film which has been conventionally considered to be excellent. However, the temperature is limited to 90 ° C. due to the solubility of the PVA film in an aqueous alkaline solution.

[Cycle Life Test on Alkaline Zinc Storage Battery] The direct crosslinked PVA membrane of the product of the present invention and the P of the comparative product
Each of the VA membranes was used as a separator to form a sealed rectangular nickel-zinc storage battery shown below, and a cycle life test was performed.

(Preparation of Battery) A positive electrode, a negative electrode, a direct cross-linkable PVA film of the present invention, a PVA film of a comparative product, and the like shown below were prepared. A positive electrode / nonwoven fabric / polyolefin microporous membrane / separator / nonwoven fabric / negative electrode was prepared. To form a battery.

Positive electrode: Sintered nickel electrode mainly composed of nickel hydroxide, having an electrode plate size of 10 cm × 15 cm
It is. Negative electrode: A current collector is a punching metal of copper having a thickness of 0.1 mm, and on both surfaces thereof, 80 parts of zinc oxide powder and zinc powder 2
A mixture of 0 parts and 3 parts of polytetrafluoroethylene particles is applied, and has a porosity of 50% and a plate size of 10 cm × 15 cm. -Direct crosslinked PVA membrane of the present invention: PV with a thickness of 18 µm
The film A was used as a substrate, the temperature at the time of swelling treatment was 80 ° C., and the total dose of electron beam irradiation was 100 Mrad. Area resistance: 80 mΩ · cm ² (8 mol / l potassium hydroxide aqueous solution), hydroxide ion diffusion coefficient (25
° C): 4 × 10 ^-6 mol / sec / cm ² , 4 at 60 ° C
SMC value after alkali immersion for 0 days: 300 mAh / cm
² , gel fraction: 96%. Comparative PVA membrane: The swelling step was omitted, and the others were obtained in the same manner as the product of the present invention. Area resistance:
200 mΩ · cm ² (8 mol / l potassium hydroxide aqueous solution), hydroxide ion diffusion coefficient (25 ° C.): 1 × 10 ⁻⁶
mol / sec / cm ² , SMC value after alkali immersion at 60 ° C. for 40 days: 15 mAh / cm ² , gel fraction: 0
%.

(Cycle life test) The test temperature was 35 ° C.
Charging was performed at 0.1 C amperes and 103%, and discharging was performed using a random discharge pattern (including regenerative charging) that simulated a pattern of traveling in a city on an electric vehicle.

(Results) FIG. 5 shows the results of the cycle life test. As can be seen from FIG. 5, in the comparative battery, the capacity was reduced at an early stage, and a remarkable shape change was recognized in the zinc electrode as the negative electrode. On the other hand, in the battery of the present invention, the capacity reduction was as small as about 5% at 100 cycles, and good results were obtained.

As described above, the decrease in the capacity of the battery of the present invention is smaller than that of the battery of the comparative product in the process of obtaining the directly crosslinked PVA membrane of the product of the present invention because the hydrophilicity is lower than that of heat treatment or PVA. It is considered that the swelling treatment is performed without performing the treatment of introducing molecules having inferior properties, thereby improving the ion permeability. That is, since the direct cross-linking type PVA membrane of the present invention can maintain high short-circuit resistance for a long period of time, the reliability of the alkaline zinc storage battery of the present invention can be greatly improved. Product directly crosslinked type P
Since the VA membrane exhibits high ion permeability, the cycle life characteristics of the alkaline zinc storage battery of the present invention can be greatly improved.

[0051]

According to the first aspect of the present invention, even in an alkaline electrolyte, its mechanical strength can be maintained for a long period of time, so that an internal short circuit caused by zinc dendrite penetrating through the separator can be prevented for a long period of time. Can be prevented. In addition, since it has excellent ion permeability and low sheet resistance, the current distribution during charging and discharging can be made uniform, the shape change of the negative electrode and the growth of zinc dendrites in the alkaline zinc storage battery can be suppressed, and the battery life is improved. Can be achieved.

According to the second aspect of the present invention, the crosslinking reaction of the PVA film in the irradiation treatment step can be caused to take precedence over the decomposition reaction, and the direct crosslinking type crosslinked structure can be reliably provided. .

According to the third aspect of the present invention, it is possible to provide a direct crosslinkable crosslinked structure sufficiently to exhibit its characteristics.

According to the fourth aspect of the invention, high short-circuit resistance can be maintained for a long period of time, and the reliability of the alkaline zinc storage battery can be improved.

According to the fifth aspect of the present invention, the current distribution during charging and discharging can be made uniform, the shape change of the negative electrode and the growth of zinc dendrite can be suppressed, and the life of the alkaline zinc storage battery can be improved.

According to the invention of claim 6, since the separator maintains high short-circuit resistance for a long period of time, the reliability can be greatly improved, and since the separator has high ion permeability, Cycle life characteristics can be improved.

According to the invention of claim 7, the formation of zinc dendrite can be suppressed by the polyolefin microporous membrane,
The growth of zinc dendrites can be suppressed by the direct cross-linking type PVA film. Therefore, an internal short circuit can be sufficiently prevented by the synergistic action of both films, and the reliability of the battery can be sufficiently improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the gel fraction and the dose of electron beam irradiation for a direct crosslinked PVA film of the present invention and a comparative PVA film.

FIG. 2 is a diagram showing the relationship between the shoot resistance and the electron beam irradiation dose of the directly crosslinked PVA film of the present invention.

FIG. 3 shows a directly crosslinked PVA membrane of the product of the present invention and P of a comparative product.
It is a figure which shows the time-dependent change of the SMC value of a VA film and a cellophane film.

FIG. 4 is a diagram showing the relationship between the temperature at the time of swelling, the sheet resistance, and the hydroxide ion permeability of the directly crosslinked PVA membrane of the present invention.

FIG. 5 is a diagram showing the results of a cycle life test of the alkaline zinc storage batteries of the present invention and the comparative product.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08J 5/18 CEX C08J 5/18 CEX (72) Inventor Mitsuo Yamane 6-6 Josaicho, Takatsuki-shi, Osaka Yu Co., Ltd. Inside Asa Corporation (72) Kazuyuki Adachi 2-82, Watanabe-dori, Chuo-ku, Fukuoka City, Fukuoka Prefecture Inside Kyushu Electric Power Co., Inc. No. 1 Inside Nard Research Laboratories (72) Inventor Kazuyo Mukai 2-6-1 Nishinagasu-cho, Amagasaki-shi, Hyogo Pref.

Claims (7)

[Claims] 1. A separator for an alkaline zinc storage battery comprising a directly crosslinked polyvinyl alcohol film, wherein the directly crosslinked polyvinyl alcohol film is swelled by immersing the polyvinyl alcohol film in water and swelling. It is obtained through an irradiation treatment step of irradiating the polyvinyl alcohol film with an electron beam to crosslink between polymer main chains, and a drying treatment step of drying the crosslinked polyvinyl alcohol film. Fifteen
A separator for an alkaline zinc storage battery, characterized in that a polyvinyl alcohol film having a degree of saponification of 98 or more and 98% or more is immersed in water at 20 to 90 ° C. 2. In the irradiation process, an oxygen concentration of 1000 p
The separator for an alkaline zinc storage battery according to claim 1, wherein the separator is irradiated with an electron beam of 30 to 200 Mrad under an atmosphere of not more than pm. 3. The alkaline zinc storage battery according to claim 1, wherein the weight percentage of solids remaining without being dissolved after immersion in boiling water for 5 minutes after drying at 60 ° C. for 1 hour is 70% or more. Separator. 4. The alkali zinc according to claim 1, wherein the value of the amount of electricity charged when the battery is immersed in an alkaline aqueous solution at 60 ° C. for 40 days and then charged until a short circuit occurs is 70 mAh / cm ² or more. Storage battery separator. 5. The separator for an alkaline zinc storage battery according to claim 1, wherein the sheet resistance is not more than 200 mΩ · cm ² . 6. An alkaline zinc storage battery using a directly crosslinked polyvinyl alcohol film as a separator, wherein the directly crosslinked polyvinyl alcohol film includes a swelling treatment step of immersing the polyvinyl alcohol film in water and swelling the same. The cross-linked polyvinyl alcohol film is obtained through an irradiation treatment step of irradiating an electron beam on the crosslinked polymer main chain by irradiating an electron beam, and a drying treatment step of drying the cross-linked polyvinyl alcohol film. Degree 15
An alkaline zinc storage battery characterized in that a polyvinyl alcohol film having a degree of saponification of 98 or more and 98% or more is immersed in water at 20 to 90 ° C. 7. The alkaline zinc storage battery according to claim 6, wherein the separator is a combination of a directly crosslinked polyvinyl alcohol film and a polyolefin microporous film coated with nickel powder.