JP2000294218A - Alkaline battery separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator free from the self-discharge even at a high temperature, superior in the capacity retainability, and simultaneously, remark ably reducing the lowering of reliability of the battery caused by the short circuit. SOLUTION: In a separator for alkaline battery, including a sheet-like nonwoven fabric (A) prepared by sulfonating the fiber composed of a polyolefin resin, a BET specific surface area of the fiber composed of the polyolefin resin is 0.5 m2/g or more. A diameter of the fiber composed of the polyolefin resin forming the sheet-like nonwoven fabric (A) is 1-10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator made of non-woven sulfonated polyolefin used for an alkaline battery, and particularly to an alkaline secondary battery. The present invention relates to an extremely small and highly reliable sulfonated polyolefin nonwoven fabric separator, and is suitably used for, for example, an alkaline battery for a battery of an electric vehicle, a power tool or the like.

[0002]

2. Description of the Related Art Conventionally, self-discharge is relatively large in an alkaline battery typified by a nickel-hydrogen battery, and its suppression has been regarded as important.

Further, it is known that these self-discharges are caused by nitrate groups, and studies on reducing the amount of the self-discharges are widely conducted.

[0004] It is known that these nitrate groups are generated by oxidizing ammonia mixed as an impurity. However, such ammonia is easily mixed in a manufacturing process of an alkaline battery, and the mixing of ammonia is completely prevented. It was difficult to prevent. Therefore, it was necessary to remove ammonia before it was oxidized and turned into nitrate.

[0005] In view of the above, studies have been made in a direction in which mixed ammonia is trapped by the separator. For example, JP-A-10-116600 discloses a separator in which the trapping rate of ammonia is improved by ion exchange with a carboxyl group by optimizing a graft method of a vinyl monomer.

However, the above-mentioned ammonia trap is basically a trap by an acidic group such as carboxylic acid, and the amount of the trap is limited. Further, the separator subjected to the hydrophilic treatment with the vinyl monomer has a problem in heat resistance. For example, in a relatively high temperature environment of 60 ° C. or higher, the acidic group is dropped off and the ammonia trapping property is maintained. Even that was difficult.

As a separator having good heat resistance, a separator obtained by sulfonating a polyolefin-based material is known.
3, 1987) discloses that when a sulfonated polypropylene nonwoven fabric is used, self-discharge is smaller than that of a conventional polyamide-based separator, and a high capacity retention rate is exhibited. However, such a separator is used for the purpose of preventing nitrogen-based impurities from being eluted from the separator, and is not intended to actively trap ammonia.

In order to improve the performance of ammonia trapping, introduction of a large amount of sulfonic acid groups has been studied. However, conventional polyolefin resin fibers have a high acid resistance, and if the conditions for sulfonation are increased, the fibers will be hardened. Sulfonic acid groups are intensively introduced into the fiber surface, and as a result of the decrease in strength, separation of the sulfonated portion occurs, and as a result, it was difficult to increase the amount of sulfonic acid groups. For example, in Japanese Unexamined Patent Publication No. 7-278963, the total sulfur content is 800 ppm at the maximum even when fibers which are very easily sulfonated are mixed.
(0.8 mg per 1 g of separator), and it is stated that there is a decrease in strength, and it is shown that only 10 ppm or less of sulfur is present in the examples (when practical strength is maintained). I have.

This is because a resin having a high intrinsic viscosity, that is, a high-molecular-weight polyolefin resin is used in a conventionally used polyolefin nonwoven fabric. Such fibers made of a polyolefin resin having a high intrinsic viscosity, such as spunbond fibers of polypropylene and composite sheath fibers of polypropylene / polyethylene, have been widely used as raw materials for separators because of their easy spinning. Is coming. However,
The above-mentioned fiber has a problem that the acid resistance is high, a sulfonic acid group can be introduced only in a small amount, a sulfonating agent hardly penetrates into the fiber, and a sulfur atom is not introduced into the fiber. Almost never.

[0010] Further, by minimizing the fiber constituting the separator to prevent the passage of the electrode active material and reduce the probability of battery short-circuit, the use of split fibers represented by JP-A-8-284019 and the like is described. Is being studied. But,
When such ultrafine fibers are highly sulfonated to enhance ammonia trapping properties, the strength is extremely reduced,
As a result, there has been a problem that the fiber is cut inside the battery, a pinhole is generated, and a short circuit occurs.

As described above, no satisfactory separator has been obtained as a separator for an alkaline battery which maintains a good ammonia trapping property and has a small amount of self-discharge, and at the same time, has a high effect of preventing short-circuiting of the battery. Met.

[0012]

In view of this situation, the present inventors have found that even under high temperatures, self-discharge is small, the capacity retention is good, and at the same time, the reliability of the battery due to short-circuit is extremely reduced. In order to obtain a small separator, the relationship between the change in the molecular structure of the polyolefin resin and the ammonia trapping performance when sulfonating the polyolefin non-woven fabric was investigated.

As a result, the present inventors have found that when a fiber made of a polyolefin resin is sulfonated to increase the specific surface area of the fiber to 0.5 m ² / g or more, a large number of pores are formed. Formed and found to significantly improve the ammonia trapping performance of the fiber.

Regarding the above findings, the details of the mechanism are unknown at present. However, the present inventors have found that the above-mentioned pores are not pores of the order of μm as seen in the gap between fibers, but have an average diameter of several micrometers. It is an extremely microscopic pore of about nm, and it is presumed that it became possible to specifically trap ammonia.

Further, the present inventors have found that the above-mentioned ammonia trapping performance is further improved by making the fiber diameter specific small.

It has also been found that by laminating a nonwoven fabric made of reinforcing fibers on the above nonwoven fabric, the strength of the whole separator can be improved without impairing the ammonia trapping performance of the above nonwoven fabric.

The present inventors have further studied based on the above findings and considerations, and have completed the present invention.

[0018]

That is, the present invention relates to a separator for an alkaline battery comprising a sheet-like nonwoven fabric (A) obtained by sulfonating a fiber comprising a polyolefin resin, wherein the separator comprises the polyolefin resin. An object of the present invention is to provide a separator for an alkaline battery, wherein the specific surface area of the fiber by the BET method is 0.5 m ² / g or more.

In a preferred embodiment of the separator for an alkaline battery according to the present invention, the sheet-shaped nonwoven fabric (A) comprises a polyolefin resin having a fiber diameter of 1 to 1.
0 μm.

In a preferred embodiment of the separator for an alkaline battery according to the present invention, a sheet-like nonwoven fabric (B) obtained by sulfonating a fiber made of a polyolefin resin having a fiber diameter of 10 to 50 μm is used as the sheet-like nonwoven fabric (A). It is formed by laminating.

In a preferred embodiment of the alkaline battery separator of the present invention, the total sulfur content per 1 g of the alkaline battery separator is 1 mg or more.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The polyolefin resin used in the separator for an alkaline battery of the present invention is not particularly limited. For example, hydrocarbon resins such as polyethylene, polypropylene, polybutene, polystyrene, and ethylene-propylene copolymer can be used. This is a fiber composed of the above resin. Particularly, in the case of polypropylene, in the sulfuric acid treatment described below, it is possible to perform the treatment under a very wide temperature condition of 90 to 150 ° C., and the handling is extremely easy in industrial production, which is preferable.

The specific surface area of the sheet-like nonwoven fabric (A) used for the alkaline battery separator of the present invention is 0.5 m ^2.
/ It is necessary g or more, more preferably as long as 1 m ² / g or more, particularly preferably equal to 2m ² / g or more. This is for exhibiting sufficient ammonia trap performance.

Regarding the average pore size of the sheet-like nonwoven fabric (A) used in the separator for an alkaline battery of the present invention,
Although the details thereof are unknown at present, it is preferable that the size is such that ammonia can be adsorbed, and it is preferably in the range of about 0.5 nm to 10 nm, and more preferably in the range of about 1 to 5 nm. Can be

The limiting viscosity (IV) of the polyolefin resin of the sheet-like nonwoven fabric (A) used for the separator for an alkaline battery of the present invention is IV = 0.1 to 1.2 (dl /
g), preferably in the range of 0.2 to 1.0 (d
1 / g), more preferably 0.3 to 0.9.
(Dl / g) is particularly preferable. This is because, when a polyolefin-based resin having an optimum intrinsic viscosity in the above range is subjected to an ammonia treatment described later, a large amount of micropores are developed in the resin, and a resin material having good ammonia trapping performance can be obtained.

The fiber diameter of the polyolefin resin fibers of the sheet-like nonwoven fabric (A) used in the alkaline battery separator of the present invention is preferably in the range of 1 μm to 10 μm, and is preferably 2 μm to 9 μm. More preferred. Can be used optimally. When the fiber diameter is less than 1 μm, the fiber density becomes too high, and a problem arises that the permeability of gas generated at the end of charging cannot be sufficiently maintained.
If it exceeds μm, the amount of micropores is small and sufficient ammonia trapping performance cannot be exhibited. If the fiber diameter is in the above range, gas permeability can be sufficiently maintained, and at the same time,
This has a sufficient effect on the blocking properties of the electrode active material.

The method for sulfonating the fiber made of the polyolefin resin used for the separator for an alkaline battery of the present invention is not particularly limited.
A gas phase treatment method using O ₃ gas, SO ₂ gas or the like, a liquid phase treatment method using sulfuric acid, fuming sulfuric acid, and the like are suitably used.

Among them, in order to form micropores efficiently, a gas phase treatment method using SO ₃ gas treatment or a liquid phase treatment method using sulfuric acid is preferable, and a liquid layer treatment method using sulfuric acid is particularly preferable.

Incidentally, in the gas phase treatment method by SO ₃ gas treatment, 0.5 to 30% by volume of SO ₃ gas can be used, and 2 to 20% by volume is optimal. Regarding the processing temperature, the processing can be performed at room temperature, and the processing can be performed at 15 to 40 ° C. The liquid phase treatment with sulfuric acid is the method of most efficiently forming micropores, and is a method of immersing in concentrated sulfuric acid in the range of 90 ° C to 150 ° C.

At this time, the details of the mechanism for forming micropores and the mechanism for trapping ammonia in micropores are unknown, but the present inventors presume as follows. (1) In the sulfonation step, the crystal structure of the polyolefin polymer is disturbed, and micro gaps are formed. (2) The sulfur atoms introduced in the sulfonation step crosslink the polyolefin resin to form a “microcrosslinked structure”. (3) By being fixed by crosslinking, microscopic gaps are not lost even by thermal motion of molecules, and fine pores are fixed. (4) The interaction between the sulfur atoms forming the crosslinks and ammonia is strong, and the ammonia adsorbed in the micropores is firmly fixed without being desorbed.

The separator for an alkaline battery according to the present invention is characterized in that the sheet-like nonwoven fabric (A) has a fiber diameter of 10 to 50 μm.
It is preferable to laminate the sheet-like nonwoven fabric (B) obtained by sulfonating the fiber made of the polyolefin resin. Such a sheet-like nonwoven fabric (B) has a fiber diameter of 10 to 50.
By being composed of a fiber made of a polyolefin-based resin having a thickness of μm, it is possible to exhibit appropriate strength and wettability even when sulfonated. Therefore, by laminating the sheet-like nonwoven fabric (A) having excellent ammonia trapping performance and the sheet-like nonwoven fabric (B) having excellent strength, it becomes possible to obtain an alkaline battery separator having both of these properties.

The fiber diameter of the polyolefin resin fibers of the sheet-like nonwoven fabric (B) used in the separator for an alkaline battery of the present invention is preferably 10 to 50 μm, and is preferably 1 to 50 μm.
More preferably, it is 5 to 40 μm. When sulfonating the sheet-like nonwoven fabric (A) and (B) after laminating,
This is because the strength maintenance rate of the sheet-like nonwoven fabric (B) is further increased. That is, when the intrinsic viscosity and the fiber diameter in the above ranges are simultaneously satisfied, the layer B becomes a strength retaining layer having extremely high strength, and it becomes much easier to simultaneously sulfonate both layers under the same conditions.

The limiting viscosity of the polyolefin resin constituting the nonwoven fabric sheet (B) is 1.0 [dl /
g] and more preferably more than 1.5 [dl / g]. If the intrinsic viscosity exceeds 1.0 [dl / g],
Even when the sheet-like nonwoven fabric (B) is sulfonated after being laminated with the sheet-like nonwoven fabric (A), the sheet-like nonwoven fabric (B) is less likely to be sulfonated than the sheet-like nonwoven fabric (A), so that the original strength of the nonwoven fabric can be easily maintained. is there. In other words, the difference in the sulfonation characteristics of both the sheet-like nonwoven fabrics (A) and (B) means that the layer A requiring strong sulfonation is more strongly sulfonated and the layer B imparts hydrophilicity. The operation of minimum sulfonation for the purpose of sulphonation can be simultaneously achieved by one sulphonation.

The fiber shape of the polyolefin resin fiber of the sheet-like nonwoven fabric (B) used in the separator for an alkaline battery of the present invention is not particularly limited.
Continuous fibers, discontinuous fibers, long fibers, short fibers, and the like are used. Among them, continuous fibers obtained by a spun bond or melt blow method can be effectively used. Furthermore, the parallel type (Side-
by-Side), Sheath-Core
A composite fiber of polyethylene / polypropylene, represented by, for example, can also be used effectively, and it is possible to maintain the strength by melting and bonding the polyethylene component.
It is also effective to mix ultrahigh molecular weight polyethylene having an elongation of 2 to 10%.

In the alkaline battery separator of the present invention, the sheet-like nonwoven fabric (A) and the sheet-like nonwoven fabric (B) are used.
Are preferably laminated. By laminating both, the strength of the sheet-like nonwoven fabric (B) supports the sheet-like nonwoven fabric (A), and in addition to the ammonia trapping property of the sheet-like nonwoven fabric (A), a separator for an alkaline battery having excellent strength is obtained. Because it can be done.

The important thing in the above-mentioned lamination is that
That is, the fibers forming the sheet-like nonwoven fabric (A) are uniformly distributed in the plane direction of the separator. This is because by uniformly distributing, ammonia that has passed through the separator layer by diffusion can be trapped without escape.

That is, as long as the above is achieved, the method of laminating the sheet-like nonwoven fabrics (A) and (B) is not particularly limited. The present invention can be applied to a method of forming a layer, a method of fusing with heat, and laminating and integrating. In addition, the sheet-like nonwoven fabric (A) or (B) may have a thickness of 2
More than one layer may be laminated.

In the present invention, immediately after melt-spinning the fibers of the sheet-like nonwoven fabric (A), the sheet-like nonwoven fabric (B)
And a method of solidifying the sheet-like nonwoven fabric (B) on the sheet-like nonwoven fabric (A) and conversely, a method of solidifying the sheet-like nonwoven fabric (B) on the sheet-like nonwoven fabric (A). This is because the strength of the sheet-like nonwoven fabric (B) can be further maintained.

The basis weight of the sheet-like nonwoven fabric (A) used in the separator for an alkaline battery of the present invention is 1 m in apparent area of the separator because it plays a role of an ammonia trap.
^The basis weight based on ² is preferably 10 g / m ² or more.

The required weight of the sheet-like nonwoven fabric (B) used in the separator for an alkaline battery of the present invention is determined by the strength required of the separator. Therefore, it is preferably 5 g / m ² or more.

The total sulfur content per 1 g of the alkaline battery separator of the present invention is preferably 1 mg or more, and
g or more is more preferable. This is for maintaining the ammonia trap performance. Ammonia trap performance can be controlled by changing the degree of sulfonation.
This is because, by increasing the amount of sulfur atoms forming the crosslinked structure, the interaction with ammonia becomes stronger, and as a result, the utilization rate of micropores is improved. The total amount of micropores does not increase sharply even if the degree of crosslinking is increased.

For the alkaline battery separator of the present invention, the trapping rate of ammonia was measured by the following test method. 8N potassium hydroxide solution 100 in an eggplant type flask
A separator having 0 cc and a dry weight of 1.0 g was charged, the air inside the separator was removed by vacuum degassing, and the separator was completely immersed in the liquid. After degassing under vacuum, 0.1 cc of a 1N aqueous ammonia solution was added, and the ammonia concentration was reduced to 3%.
× 10 ^-4 (mol). Completely stoppered, 45 ° C
, And then left for 72 hours to measure the amount of residual ammonia. The measurement of the ammonia concentration is performed according to JIS-K010.
The measurement was performed by an absorption spectrophotometric method according to 2.42.2. To re-measure the ammonia-trapped separator, first rinse the separator with pure water, then immerse it in 1N hydrochloric acid 200 times the weight of the separator for 10 hours or more,
After washing again with water and drying under vacuum at 60 ° C. and 2 Pa for 20 hours for regeneration, the amount of ammonia trap was measured.
The amount of ammonia trap was expressed in terms of mmol per 1 g of separator.

The capacity retention of the alkaline battery separator of the present invention was measured by the following method. A paste-type nickel hydroxide positive electrode, a paste-type hydrogen storage alloy negative electrode, and a separator were spirally wound to produce an SC-size sealed battery. An aqueous solution of potassium hydroxide to which lithium hydroxide was added was used as the electrolyte. After preservation at 45 ° C. for 6 hours as an initial activation treatment for preparation, “0.2
After charging at C for 6 hours, discharging at 0.2 C (discharge end voltage 1.
0V) "for 7 cycles. Subsequently, measurement was carried out according to the following procedures 1 to 4, and the capacity retention was determined by the calculation method of 5. 1. After charging at 0.2C for 6 hours (1 hour rest), 0.2
Measure discharge capacity at C discharge (1.0 V cutoff) (= C
0). 2. Charge at 0.2C for 6 hours and 168 at 45 ° C
Save time. 3. After the storage period, 0.2C discharge (final voltage 1.0)
(= C1). Discharge started after cooling at 20 ° C for 6 hours. 4.1. The discharge capacity was measured under the same conditions (0.2 C charge / discharge) as in (C2). 5. Capacity retention (%) = C1 × 2 / (C0 + C2) × 1
[0099] The 0.2 C discharge means an operation at a current corresponding to the discharge in the rated capacity of 5 hours.

As a supplement, the relationship between the capacity retention and the self-discharge amount is expressed by the following equation. Capacity retention (%) = 100-Self-discharge amount (%)

The "specific surface area" indicating the micropore amount of the separator of the present invention was measured by the following method. Measure the adsorption isotherm of nitrogen gas at liquid nitrogen temperature,
B. E. FIG. T. It was calculated by the method. Specifically, the relative pressure (P / P0) was 0.1 to 0.35 after measuring the adsorption isotherm using Carlo Elba's Soapmatic.
Using data in the range of B. E. FIG. T. The specific surface area was determined by estimating the amount of nitrogen gas adsorbed on the monolayer by the method. Using the data of the total pore volume and the specific surface area obtained by the above measurement, the diameter of the cylinder when the pore was approximated to a cylinder (a cylindrical pore model) was defined as the average pore diameter. B. E. FIG.
T. The method for obtaining the specific surface area by the method is described in detail in Keicho Tominaga, "Adsorption", Kyoritsu Shuppan, 1965.

The intrinsic viscosity (IV) in the present invention was measured by the following method. The solvent uses tetralin,
Using a Ubbelohde viscometer, 135 ± 0.1
The measurements were performed at a temperature of ° C. To the tetralin used, 0.2% by weight of BHT (2,4-di-t-butyl-p-cresol) was added in advance to prevent oxidative deterioration when dissolving the separator. The liquid in which the separator was dissolved was subjected to measurement after being filtered with a glass filter. The concentration of the solution in the separator was 1 [g / 1000 cc]. The Huggins constant (k ′) is k ′ = 0.35
Was used. The measurement was carried out according to Experimental Chemistry Course 8 Polymer Chemistry (above), Chapter 5, “Viscosity”, The Chemical Society of Japan, May 15, 1963.

The strength of the separator of the present invention is 5 cm in width,
Using a 15 cm long sample, JISL1068
According to (Testing method for tensile strength of fabric)
m, and the tensile speed in the longitudinal (MD) direction was measured with a tensile speed of 30 cm / min using a Tensilon RTM-100 tester.

The functional group content of the separator in the present invention is as follows:
The amount of ion exchange was measured by the following method. 1/1
The separator was immersed in a 0 N KOH (potassium hydroxide) solution, and the amount of KOH consumed by neutralization was determined by titration with a hydrochloric acid normal solution. The measurement was performed after degassing in vacuum to remove bubbles inside the separator and completely bringing the separator into contact with the KOH solution. To confirm the neutralization point, a phenolphthalein indicator was used. The ion exchange amount was represented by the amount (mmol) of the functional group per 1 g of the separator.

The measurement of the total sulfur content in the present invention was carried out by a flask combustion method. Basic Analysis Chemistry, 11th
Vol., The Japan Society for Analytical Chemistry (Kyoritsu Publishing), pp. 34-43, 19
The measurement was carried out according to the method described in September 1965.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments.

Example 1 A polypropylene resin was formed into a non-woven fabric at the same time as fiberization by a melt blow method. Specifically, it is extruded from the orifice at a temperature of 200 ° C., and the single hole discharge amount is 0.5 g /
min. And 230 ° C at 0.4 kg / cm ²
To make a non-woven fabric on the collection conveyor, which was taken up as a B layer. Further, another polypropylene resin was formed into a non-woven fabric at the same time as fiberization by a melt blow method.
Extruded at a temperature of 0 ° C., the single hole discharge rate is 0.5 g / mi
n. And Furthermore, it was made to be thin by an air flow of 250 ° C. at 0.6 kg / cm ² and made into a nonwoven fabric (A layer) on a collection conveyor. At this time, the A layer and the B layer are laminated by placing the created B layer on the collection conveyor,
And integrated by hot pressing. Further, the mixture was treated with 95% concentrated sulfuric acid at 130 ° C. for 10 minutes to obtain a separator. The separator was incorporated in the battery, and the capacity retention was measured. Table 1 shows various physical properties of the separator and the capacity retention of the battery.

Example 2 A polypropylene resin was converted into a fiber and a nonwoven fabric by a technique called spunbonding. Specifically, 240
The polypropylene resin melted at ℃ was extruded from a nozzle, stretched by an air jet, and formed into a non-woven fabric on a collection conveyor. (B layer) Further, another polypropylene resin is formed into a non-woven fabric at the same time as fiberization using a melt blow method (A layer).
After stacking the layers, use 90% concentrated sulfuric acid at 120 ° C for 10
This was treated for minutes to obtain a separator. Table 1 shows various physical properties of the separator and the capacity retention ratio when the battery was included.

Example 3 In the same manner as in Example 2, a nonwoven fabric was prepared by laminating and integrating a nonwoven fabric formed by a spun bond method and a nonwoven fabric formed by a melt blow method, and further treated with 97% concentrated sulfuric acid at 95 ° C. for 240 minutes. I got The separator was incorporated in the battery, and the capacity retention was measured. Table 1 shows various physical properties of the separator and the capacity retention of the battery.

Example 4 A nonwoven fabric obtained by previously collecting the melt blown layer (layer A) used in Example 1 alone and then laminating two melt blown layers (layer A) in the same manner as in Example 1 It was created. Further, a sulfonation treatment was performed under the same conditions as in Comparative Example 1 to obtain a separator. Incorporate the separator into the battery,
The capacity retention was measured. Table 1 shows various physical properties of the separator and the capacity retention of the battery.

Comparative Example 1 Commercially available polypropylene nonwoven fabric (Asahi Kasei ELTAS PO30)
30) were layered together, hot-pressed at 130 ° C. and integrated, and further subjected to sulfonation at 130 ° C. for 10 minutes using 95% concentrated sulfuric acid to obtain a separator. The separator was incorporated in the battery, and the capacity retention was measured. Table 1 shows various physical properties of the separator and the capacity retention of the battery.

Comparative Example 2 A polypropylene resin melted at 240 ° C. was extruded from a nozzle by a spun bond method, stretched by an air jet, and formed into a nonwoven fabric on a collection conveyor. Further, a sulfonation treatment was performed under the same conditions as in Comparative Example 1 to obtain a separator. The separator was incorporated in the battery, and the capacity retention was measured. Table 1 shows various physical properties of the separator and the capacity retention of the battery.

[0057]

[Table 1]

[0058]

As described above, the present invention makes it possible to produce a separator having good ammonia trapping performance, and to reduce the self-discharge of the battery. Furthermore, by realizing the optimum combination of the trap layer and the reinforcing layer made of ultrafine fibers, problems of both particle permeation and fiber cutting did not occur, the probability of short circuit of the battery was reduced, and the reliability of the battery was improved.

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Claims (4)

[Claims] 1. An alkaline battery separator comprising a sheet-like nonwoven fabric (A) obtained by sulfonating fibers of a polyolefin resin, wherein the fibers of the polyolefin resin have a specific surface area of 0. 5
m ² / g or more, a separator for an alkaline battery. 2. A fiber comprising a polyolefin resin constituting the sheet-like nonwoven fabric (A) has a fiber diameter of 1 to 10.
The alkaline battery separator according to claim 1, wherein the thickness is μm. 3. A sheet-like nonwoven fabric (B) obtained by sulfonating fibers of a polyolefin resin having a fiber diameter of 10 to 50 μm on the sheet-like nonwoven fabric (A). 3. The separator for an alkaline battery according to 1 or 2. 4. The alkaline battery separator according to claim 1, wherein the total amount of sulfur per gram of the alkaline battery separator is 1 mg or more.