JP6739947B2 - Alkaline battery separator and alkaline battery - Google Patents

Description

The present invention relates to an alkaline battery separator and an alkaline battery, for example, an alkaline battery separator used in various alkaline batteries such as an alkaline manganese battery, a silver oxide battery, a mercury battery, and a zinc-air battery, and an alkaline battery using the separator. It is a thing.

Conventionally, as a characteristic required for a separator for separating a positive electrode active material and a negative electrode active material in the alkaline battery, an internal short circuit due to contact between the positive electrode active material and the negative electrode active material or a needle-shaped conductive metal oxide Prevents internal short circuit due to crystals (dendrites) and has durability that does not cause contraction and deterioration with respect to positive electrode active materials such as manganese dioxide, nickel oxyhydroxide, and silver oxide, and electrolytes such as potassium hydroxide. It is possible to maintain a sufficient amount of electrolytic solution for a long period of time so as to cause an electrolysis reaction, and not interfere with ionic conduction.

In the production of the separator, fibrillizable cellulosic fibers such as mercerized pulp, cotton linter pulp, polynosic fibers, and solvent-spun cellulosic fibers are beaten as necessary to fibrillate the fibers before use. The fibrillated cellulose fibers can give the separator compactness and prevent the occurrence of internal short circuits due to dendrites.

As an alkaline battery separator using such a fibrillizable cellulose fiber, Patent Document 1 and Patent Document 2 prevent an internal short circuit when a battery is assembled by controlling the average pore diameter of the separator. Alkaline battery separators have been proposed.

As the solvent-spun cellulose fibers used in the separator described in Patent Document 1 or 2 above, regenerated cellulose fibers called Lyocell (registered trademark) or Tencel (registered trademark) are currently known, and are resistant to mercerized pulp or dissolved pulp. Similar to the alkaline cellulose pulp, by fibrillating and blending the fibers, a separator having excellent shielding properties for both polar active materials can be obtained.

JP, 2014-26877, A Japanese Patent Publication No. 2005-525675

In a conventional alkaline battery separator, a separator obtained by mixing synthetic fibers and cellulose fibers has durability to an electrolytic solution and a bipolar active material and retention of the electrolytic solution, but when the pore size of the separator is large, a bipolar electrode is used. There is a problem that the shielding property is insufficient in terms of preventing an internal short circuit due to contact with an active material and an internal short circuit due to needle-like crystals (dendrites) of a conductive metal oxide. In order to deal with this, a means of beating cellulose fibers capable of being fibrillated to be blended or a synthetic fiber having a small fineness is blended when manufacturing a separator.

Also, when used as a separator, the separator may be laminated in several layers to reduce the apparent pore diameter, or may be used in combination with a separate material having a small pore diameter such as cellophane (registered trademark) film or polyethylene porous membrane. Etc. are taken.

However, although Patent Document 1 or Patent Document 2 proposes a separator having excellent shielding properties, which focuses on the average pore size of the separator, it has a good balance between the shielding properties and the liquid retention properties, and exhibits good performance as a separator. As shown, there have been cases where further improvement of the shielding property is required in recent years.
As described above, it has been difficult to realize a separator having a further liquid-blocking property and further having a shielding property, which has recently been demanded.

The present invention has been made for the purpose of solving the above-mentioned problems, and solves the above problems, while having a high liquid retaining property, as in recent years, the demand is increasing, and a separator having a further shielding property. For example, the following configuration is provided as one means for realizing the above.
That is, a wet non-woven fabric containing at least alkali-resistant cellulose fibers and alkali-resistant synthetic fibers and bound with a binder component, wherein the wet non-woven fabric has a maximum pore size of 15 to 35 μm, an average pore size of 1 to 10 μm, and 40 mass. The alkaline battery separator is characterized by having a liquid retention rate of 450 to 700% when immersed in a 40% by weight KOH aqueous solution and a swelling rate of 45 to 55% when immersed in a 40% by mass KOH aqueous solution.

And, for example, the alkali-resistant cellulose fiber is characterized by containing at least fibrillated solvent-spun cellulose fiber and non-fibrillated cellulose.

Further, for example, the alkali-resistant synthetic fibers are characterized by containing non-acetalized polyvinyl alcohol fibers and acetalized polyvinyl alcohol fibers. Alternatively, the non-fibrillated cellulose contains at least regenerated cellulose fibers.
Further, the alkaline battery is characterized by using the alkaline battery separator having the above configuration.

According to the present invention, it is possible to provide an alkaline battery separator and an alkaline battery having improved reliability for preventing an internal short circuit.

FIG. 2 is a central vertical cross-sectional view of an alkaline battery using the alkaline battery separator according to the embodiment of the present invention.

Embodiments of the present invention will be described below in detail with reference to the drawings. Examples of the present embodiment, for example, a liquid retention property that can improve the shielding performance and discharge performance capable of preventing an internal short circuit due to a dendrite of a metal oxide, a separator that simultaneously satisfies the swelling rate, specifically, A wet non-woven fabric comprising alkali-resistant cellulose fibers, alkali-resistant synthetic fibers and a binder component, having a maximum pore size of 15 to 35 μm, an average pore size of 1.0 to 10.0 μm, and a liquid retention when immersed in 40% by mass KOH. Provided is a separator for alkaline batteries, which has a swelling ratio of 450 to 700% and a swelling ratio of 45 to 55% when immersed in 40 mass% KOH.

As described above, in order to improve the shielding property of the separator, it is very important to control not only the average pore size but also the maximum pore size.
The maximum pore size of the separator of this embodiment is 15.0 to 35.0 μm. If the maximum pore size exceeds 35.0 μm, the shielding property of the separator cannot be improved. If the maximum pore size is less than 15.0 μm, the separator may be too dense and the resistance value when the battery is assembled may increase.

In this embodiment, in order to control the maximum pore size, the aspect ratio of the tensile strength of the wet-laid nonwoven fabric represented by the following formula 1 is controlled.
Formula 1: {tensile strength in non-woven fabric flow direction (MD)}/{tensile strength in non-woven fabric flow direction (CD) orthogonal to the non-woven fabric flow direction}

In this embodiment, the aspect ratio of tensile strength is used as an index of the orientation of the nonwoven fabric.
Generally, in the manufacturing method of a wet type nonwoven fabric, the fibers are easily oriented in the MD direction, and the tensile strength in the MD direction is stronger than the tensile strength in the CD direction.
As described above, if the fiber orientation is strengthened, the average pore size can be reduced, but the maximum pore size cannot be controlled.

In the present embodiment, the maximum pore size is controlled within the range of 15.0 to 35.0 μm by setting the aspect ratio of tensile strength within the range of 1.0 to 2.5.
If the aspect ratio of the tensile strength is less than 1.0, the bending rigidity of the separator in the MD direction may be biased, and the workability of the separator may deteriorate during battery production.
If the aspect ratio of the tensile strength exceeds 2.5, it may be difficult to reduce the maximum pore size of the separator and the bending rigidity of the separator in the CD direction may be uneven, which may deteriorate the workability of the separator during battery production. is there.
As described above, the aspect ratio of tensile strength is an important index that affects not only the maximum pore diameter of the separator but also the workability when used in a battery.

Then, for example, at the time of papermaking, the aspect ratio of the tensile strength is realized by controlling the ratio (J/W ratio) of the flow velocity J (m/min) of the raw material slurry and the operating speed W (m/min) of the papermaking wire. it can.

Furthermore, the separator of the present embodiment is characterized in that the average pore diameter is 10 μm or less. If the average pore size of the separator is larger than 10 μm, sufficient shielding effect against dendrite growth cannot be obtained, and sufficient shielding performance to withstand intermittent discharge cannot be obtained. Therefore, the average pore size of the separator is 10 μm or less. It is preferable to have.
On the other hand, if the average pore size is less than 1 μm, the separator may be too dense and the resistance value when the battery is assembled may increase. The constituent material is important for controlling the average pore size.

Next, the raw material fibers used for papermaking will be described in detail.
Regenerated cellulose fibers capable of fibrillation can be divided into very fine fibrils having a diameter of 1 μm or less when beaten. In particular, solvent-spun cellulose fibers capable of fibrillation have a high degree of crystallinity, the internal structure of the fiber is composed of a crystalline portion of cellulose and an amorphous portion, the crystalline portion is amorphous. The fibers are bonded to each other via the vias.

When this fiber is beaten, the amorphous part is broken, the crystalline part is separated from the fiber, and fibrils having a diameter of 1 μm or less are generated. The separator made of this fibrillated material has a very dense structure. In addition, since this fibril is a cellulose having a very high degree of crystallinity, the rigidity is also high, the fibril itself does not flatten even when pressed in the papermaking process, and maintains a cross-sectional shape close to a circle, and the fibrils have contact points. A paper layer is formed by the entanglement and hydrogen bonding of. Therefore, the separator containing the fibrillated product has a very dense paper quality, but has little ion channel redundancy and excellent ion permeability.

Hereinafter, the structure of the separator according to the present embodiment, which will be described in more detail, is characterized by containing a fibrillated product of a solvent-spun cellulose fiber capable of fibrillation as a part of the alkali-resistant cellulose fiber. ..

By subjecting the solvent-spun cellulose fibers to a treatment (beating) by applying a shearing force, the fibers are made fine, and a non-woven fabric is formed from the finely made fibers, whereby a very dense sheet can be obtained.
The micronized cellulose fiber has a short fiber length as compared with synthetic fiber and the like, easily fills a gap between sheets, and improves the shielding property of the separator.

The CSF value (ml), which represents the degree of beating of solvent-spun cellulose fibers, gradually decreases after beating and shows 0 ml. When the beating is further performed after the CSF value shows 0 ml, the CSF value starts to rise.

The CSF value of the fibrillated solvent-spun cellulose fiber used in the present embodiment is preferably such that the CSF value is decreased to 10 to 0 ml and the CSF value is increased to 100 ml or less.
When the lowered CSF value is larger than 10 ml, the denseness of the separator due to the fibrillated product cannot be sufficiently obtained. On the other hand, when the CSF value that has turned to an increase exceeds 100 ml, the fibers become too fine and are not suitable as a battery separator raw material.

The content of the fibrillated product in the solvent-spun cellulose fiber can be increased or decreased according to the characteristics required for the separator, but if the content is less than 5% by mass, the denseness of the separator, which is the greatest feature of the fibrillated product, is impaired. When the content is more than 30% by mass, the ion permeability of the separator tends to be impaired due to excessive blending of the fibrillated product. Therefore, in order to realize both the shielding property and the electrical property at a high level, the content is 5 to 30% by mass. The range of% is desirable.

Further, the range of CSF value showing the degree of beating is preferably 10 to 0 ml. If the CSF is larger than 10 ml, the denseness of the separator due to the fibrillated product cannot be sufficiently obtained.
The denseness of the fibrillated product mainly contributes to the reduction of the average pore diameter and improves the shielding property of the separator.

Further, as other alkali-resistant cellulose fibers to be blended in addition to the fibrillated product of solvent-spun cellulose fibers, non-fibrillated cellulose, that is, non-fibrillated regenerated cellulose fibers such as copper ammonia rayon and viscose rayon, mercerized pulp, and cotton. It is at least one selected from non-fibrillated cellulose pulps such as linter pulp and dissolving pulp, and can be contained up to 30 to 70% by mass of the separator together with the fibrillated product of solvent-spun cellulose fibers.

Alkali-resistant cellulose pulp, similarly to solvent-spun cellulose fibers, fine fibrils are generated by beating, which contributes to improving the shielding properties of the separator, but has lower rigidity than solvent-spun cellulose fibers, and more than solvent-spun cellulose fibers. In recent years, it has been found that the ion permeability of the separator is likely to be lowered. Therefore, in the present embodiment, it is preferable to use the non-fibrillated alkali-resistant cellulose pulp.

When the content rate of the alkali-resistant cellulose fibers is less than 30% by mass, the liquid retention rate of the separator is reduced, and when it exceeds 70% by mass, hydrogen bonding sites between the alkali-resistant cellulose fibers increase, and the denseness of the separator becomes too high. Eventually, the ion permeability will be impaired.

The 40% by mass KOH liquid retention rate of the alkaline battery separator of the present embodiment is preferably 450% or more. If the liquid retention rate of the 40% mass KOH aqueous solution is less than 450%, there is a problem that the high rate discharge characteristics are deteriorated. The higher the liquid retention rate is, the more preferable. However, there is an upper limit to the amount of the electrolytic solution that can substantially retain the liquid, and it is considered that the upper limit is about 700%.
By setting the content of the alkali-resistant cellulose fiber to 30 to 70% by mass, the liquid retention rate of the separator can be set to 450 to 700%.

Non-fibrillated regenerated cellulose fibers are particularly preferable among the above alkali-resistant cellulose fibers because they improve the liquid retention of the separator.
The content of the non-fibrillated regenerated cellulose fiber can be increased or decreased according to the characteristics required for the separator, but if the content is less than 10% by mass, the liquid retention property of the separator, which is the greatest feature of the non-fibrillated regenerated cellulose fiber. When the content is more than 40% by mass, the unfilled regenerated cellulose fibers are excessively blended, and the swelling of the separator in the electrolytic solution tends to be too large. The range of 10 to 40% by mass is desirable for achieving a high level.

In addition, as the alkali-resistant synthetic fiber used in the alkaline battery, it is preferable to contain acetalized polyvinyl alcohol fiber (hereinafter referred to as vinylon fiber) and unacetalized polyvinyl alcohol fiber (hereinafter referred to as PVA fiber).
These fibers are preferable not only in alkali resistance but also in bending rigidity of the separator.

The content of vinylon fiber and PVA fiber can be increased or decreased according to the characteristics required for the separator, but if the content is less than 10% by mass, the flexural rigidity of the separator, which is the greatest feature of the polyvinyl alcohol fiber, is impaired. Also, the swelling rate tends to be too large, and when the content rate is more than 50% by mass, the liquid retention of the electrolytic solution tends to decrease due to excessive blending of the polyvinyl alcohol fiber, and thus the liquid retention The range of 10 to 50 mass% is desirable in order to realize high bending rigidity.

In addition, PVA fibers are more preferable than vinylon fibers because they have a lower melting point and are excellent in heat attraction between the separators in the battery manufacturing process.
The 40% by mass KOH swelling ratio of the alkaline battery separator of the present embodiment is preferably 45 to 55%.
When the swelling rate is less than 45%, the internal resistance when used in an alkaline battery increases. Further, when the swelling ratio exceeds 55%, the volume occupied by the separator in the battery case increases and the filling amount of the negative electrode agent decreases.
As one means for achieving 40% by mass KOH swelling ratio of the alkaline battery separator of 30 to 45%, the total content of the vinylon fiber used as the alkali resistant synthetic fiber and the PVA fiber is 10 to 50% by mass. There is something to do.

Other alkali resistant synthetic fibers used in alkaline batteries include polyamide fibers (hereinafter referred to as PA fibers), polypropylene fibers (hereinafter referred to as PP fibers), polyethylene fibers (hereinafter referred to as PE fibers), PP/PE composite fibers. , PP/modified PP composite fiber, PA/modified PA composite fiber, PP synthetic pulp, PE synthetic pulp, and may contain up to 20 to 50% by mass of the separator including vinylon fiber and PVA fiber.

When the alkali-resistant synthetic fiber is less than 20% by mass, the dimensional stability of the separator is impaired when impregnated with the alkaline electrolyte, and when it exceeds 50% by mass, the denseness of the separator is impaired and an internal short circuit is likely to occur. Further, since the liquid retaining property of the separator is lowered, there is a problem that the high rate discharge characteristic of the alkaline battery is deteriorated.

By setting the content of the binder component to 5 to 20% by mass, a dense separator having excellent dimensional stability in the electrolytic solution and exhibiting good ion permeability can be obtained.
As the binder component, polyvinyl alcohol binder fiber (hereinafter referred to as PVA binder fiber) which is soluble in hot water at 60 to 90° C. is often adopted.

The alkali resistance of the alkali resistant cellulose fiber and the alkali resistant synthetic fiber in the present embodiment means that decomposition by alkali is unlikely to occur when used in an alkaline battery.
Specifically, the contraction rate after immersing in a 40% by mass potassium hydroxide aqueous solution at 70° C. for 8 hours is 10% or less, and the weight reduction rate is 10% or less.
The separator using the fiber whose weight reduction rate exceeds 10% contains the fiber which is dissolved in the 40 mass% potassium hydroxide aqueous solution, and after the battery is assembled, it is gradually decomposed by the electrolytic solution to generate gas. appear. Due to the influence of this gas, the internal pressure of the battery rises and liquid leakage may occur in some cases.

The thickness of the alkaline battery separator of the present embodiment is preferably 60 to 140 μm. When the thickness of the separator is less than 60 μm, the distance between the positive electrode and the negative electrode becomes short, so that the possibility of an internal short circuit increases, and the retention amount of the alkaline electrolyte becomes insufficient, so that the high rate discharge characteristic deteriorates. When it exceeds 140 μm, the distance between the electrodes becomes long, so that the internal resistance of the battery becomes high. In addition, the volume occupied by the separator in the battery case increases, and the amount of the electrode active material inserted into the battery decreases, which may reduce the discharge capacity.

In addition, the 40% by mass KOH liquid retention rate of the alkaline battery separator of the present embodiment is preferably 450% or more. If the liquid retention of the 40% by mass KOH aqueous solution is less than 450%, there is a problem that the high rate discharge characteristics are deteriorated. The higher the liquid retention rate is, the more preferable. However, there is an upper limit to the amount of the electrolytic solution that can substantially retain the liquid, and it is considered that about 700% is the upper limit.

Next, a method for manufacturing the alkaline battery separator of the present embodiment will be described. The production of the separator of this embodiment is performed in the following steps.
(1) The solvent-spun cellulose fibers capable of fibrillation described above are dispersed in water and beaten to a predetermined CSF value by a beater or a refiner for papermaking such as a refiner.
(2) One or more of the above-mentioned non-fibrillated regenerated cellulose fibers are mixed with this.

(3) Further, if necessary, one kind or two or more kinds of non-fibrillated cellulose pulp are mixed.
(4) Further, as the alkali resistant synthetic fiber having excellent dimensional stability in the alkaline electrolyte, vinylon fiber and PVA fiber are mixed, and if necessary, other alkali resistant synthetic fiber is mixed.
(5) Then, fibers that serve as a binder component such as PVA binder fibers are added and mixed to obtain a raw material.

(6) Papermaking is performed on this raw material by using a cylinder paper machine, a short-net paper machine, a fourdrinier paper machine, or a combination of these paper machines. The wet non-woven fabric may be a single layer or a multi-layer, and in the case of a multi-layer, not only the combination paper machine but also a cylinder paper machine, a short-net paper machine, and a fourdrinier paper machine. A plurality of layers may be laminated after the wet nonwoven fabric is manufactured independently.
As a layered combination of each layer, the same paper layers formed by each paper machine, or two layers or three layers that can be combined with layers formed by different types of paper machines, the shielding property and the liquid retaining property of the separator. Various combinations are possible without impairing it.

The papermaking method using the inclined shortdrinier paper machine and the fourdrinier paper machine in the present embodiment, by increasing or decreasing the flow rate of the fiber slurry liquid fed onto the paper making net, the orientation of the fibers in the longitudinal and transverse directions of the separator. It is possible to freely control the strength and bending strength of the separator in the longitudinal and lateral directions, and at the time of battery manufacturing, it is possible to design by considering the workability of the separator. is there.

Hereinafter, specific examples of the alkaline battery separator according to the embodiment of the present invention and the alkaline battery using the separator will be described in detail. The present invention is not limited to the contents described in these embodiments.

(Test method)
Each measured value of the separator according to the example, the comparative example and the conventional example was measured by the following method.
(1) Alkali decomposition resistance test of fiber The fiber is dipped in a 40 mass% potassium hydroxide aqueous solution at 70° C. and left standing for 8 hours. After that, the mass when washed and dried with ion-exchanged water was measured, and the weight reduction rate was calculated by the following formula to obtain the decomposition rate (%).
Decomposition rate (%) = (1-mass after decomposition/mass before decomposition) x 100

(2) Beating Degree Measured according to CSF (Canadian Standard Freeness, Canadian Standard Freeness) "JIS P8121-2 Pulp-Freeness Test Method-Part 2: Canadian Standard Freeness Method".
(3) Thickness The thickness of two stacked separators is measured at equal intervals using a dial thickness gauge G type (measurement reaction force 2N, probe: φ10 mm), and 1/2 of that is measured per sheet. And the average value of the measurement points was taken as the thickness (μm) of the separator.

(4) Basis Weight The area and mass of the separator were measured to determine the mass (g) per separator area (m ² ).
(5) Maximum Pore Size, Average Pore Size Porous Materials, Inc. Using CFP-1200-AEXL-ESA manufactured by, it was measured by the method specified in ASTM F316-03 and JIS K3832.
GALWICK(
It was measured using Porous Materials, Inc.).

(6) Aspect ratio of tensile strength A test piece having a size of 15×250 mm is taken in the machine direction (MD) and the width direction (CD), and a universal tensile tester or something similar thereto is used, and the interval between the tips is 180 mm, and every minute. The test piece was pulled at a speed of about 200 mm, the tensile strength was measured, and the aspect ratio was calculated by the following formula.
Aspect ratio = tensile strength in machine direction (MD)/tensile strength in width direction (CD)

(7) Liquid retention rate The separator was cut into a square of 50 mm x 50 mm, the mass after drying was measured, and then the separator was immersed in a 40 mass% KOH aqueous solution for 10 minutes. This test piece was stuck on a glass plate tilted at an angle of 45 degrees and fixed for 3 minutes, an excess 40% by mass KOH aqueous solution was allowed to flow down and removed, and the mass of the retained test piece was measured. The liquid retention rate (%) was calculated by the formula.
Liquid retention rate (%)=(W2-W1)/W1×100
W1=mass before immersion W2=mass after immersion

(8) Swelling rate
Similar to the thickness measurement, two separators having a length of 500 mm and having no wrinkles in the width (CD) direction are taken, and the rough surface sides of these separators are overlapped and fixed so that both ends do not move. After that, dip it in a 40% by mass KOH aqueous solution for 30 minutes, and after dipping, measure the thickness at 5 points at roughly equal intervals from the inside of the paper edge by 15 mm or more, take the average value, and divide by the number of stacked sheets. The thickness per sheet was calculated by the following formula. The measurement was performed using a dial thickness gauge G type (measurement reaction force 2N, probe: φ10 mm).
Swelling rate=A2-A1/A1×100
A1 = average thickness before immersion A2 = average thickness after immersion

(9) Ionic resistance A separator is inserted between platinum electrodes (platinum-plated electrodes with a diameter of 20 mm and having a diameter of 20 mm) that are immersed in a 40% by mass KOH aqueous solution and are parallel to each other at intervals of about 2 mm. The increase in electrical resistance between the electrodes was defined as the ionic resistance (mΩ) of the separator. The electric resistance between the electrodes was measured at a frequency of 1000 Hz using an LCR meter.

(10) Hydrogen gas generation amount The amount of hydrogen gas generated by adding a separator and KOH electrolytic solution (adding zinc oxide) to a commercially available zinc alloy powder for a negative electrode of an alkaline manganese battery and leaving it at 70° C. for 10 days (zinc The volume (μl) of hydrogen gas generated per 1 g was measured. In the measurement of each separator, the zinc alloy powder:separator:KOH electrolytic solution had a mass ratio of 1:0.05:1, and was similar to FIG. 2 disclosed in JP-A-2008-171767. The amount of hydrogen gas generated was measured using the device.

(11) Discharge test A. Production of Battery Using the separators of the present example and the comparative example, the positive electrode can 2, the positive electrode mixture 3, the separator 4, the gelled negative electrode 5, the negative electrode current collector 6, the resin sealing body 7, and the negative electrode terminal shown in FIG. 30 alkaline manganese batteries 1 (LR6) each composed of the plate 8 and the resin exterior material 9 were manufactured.
In FIG. 1, 1 is an alkaline manganese battery, 2 is a cylindrical positive electrode can with a bottom, and a positive electrode terminal 2a is formed at one end. A cylindrical positive electrode mixture 3 made of manganese dioxide and graphite is press-fitted into the positive electrode can 2. Reference numeral 4 denotes a cylindrically wound separator of the present embodiment, in which a gelled negative electrode 5 in which a mercury-free zinc alloy powder and an alkaline electrolyte are mixed is filled.

Reference numeral 6 denotes a negative electrode current collector, 7 denotes a resin sealing body that closes the opening of the positive electrode can 2, and a negative electrode terminal plate 8 also serving as a negative electrode terminal is welded to the head portion of the negative electrode current collector 6 on the resin sealing body 7. Has been done. On the positive electrode terminal side of the cylindrically wound separator 4, the end of the separator is adhered or fused and sealed to prevent contact between the negative electrode and the positive electrode. Reference numeral 9 denotes a resin exterior material, which is packaged in close contact with the outer peripheral surface of the positive electrode can 2 with the positive electrode terminal 2a and the negative electrode terminal plate 8 exposed.

B. Discharge test method High-rate load discharge test that measures the time (minutes) to a final voltage of 0.9V with a load of 2Ω, and light load that measures the time (hours) to a final voltage of 0.9V with a load of 100Ω. A discharge test was performed, and the average value (sample number n=10) was calculated.
In the intermittent discharge test, 10 batteries were each discharged for 5 minutes/day under a load of 3.9Ω, and the batteries that dropped to 0.9 V or less within 50 days were counted as defective.

The results of the alkali decomposition resistance test of the fibers are described below.

As shown in Table 1, solvent-spun cellulose fibers, rayon, softwood dissolving pulp, hardwood dissolving pulp, cotton linter, mercerized softwood pulp, and mercerized hardwood pulp are preferred as alkali-resistant cellulose fibers because of their low alkali decomposition rate.
Further, polypropylene fiber (PP fiber), polyethylene fiber (PE fiber), PP/PP composite fiber, PP/PE composite fiber, acetalized polyvinyl alcohol fiber (vinylon fiber), non-acetalized polyvinyl alcohol fiber (PVA fiber), polyamide Fiber (PA fiber) has a low alkali decomposition rate and is preferable as an alkali-resistant synthetic fiber.

Using the above alkali resistant cellulose fibers and alkali resistant synthetic fibers, separators of the following examples, comparative examples and conventional examples were produced.
Below, each example, a comparative example, and a prior art example are described in detail.
Unless otherwise specified, the CSF value of solvent-spun cellulose fibers refers to the CSF value in the middle of descending.

[Example 1]
15% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml which started to rise. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 25% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) 25 as alkali resistant synthetic fiber 25 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed.

The mixed raw material was laminated and paper-made at a J/W ratio of 1.6 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 100.0 μm and a basis weight of 30.0 g/m ² . This separator has an aspect ratio of tensile strength of 1.5, a maximum pore diameter of 22.0 μm, an average pore diameter of 2.4 μm, a swelling ratio of 51.0%, a liquid retention rate of 585%, an ionic resistance of 13.5 mΩ, and a gas generation amount of 110 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 141 minutes, a 100Ω discharge time of 244 hours, and no defective intermittent discharge.

[Example 2]
5% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 3 mm) was beaten to a CSF value of 10 ml. 30% by mass of viscose rayon fiber (fineness 0.8 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 25% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 20 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 1.9 with an inclined short-line paper machine to obtain a two-layer separator having a thickness of 60.0 μm and a basis weight of 20.0 g/m ² .

This separator has an aspect ratio of tensile strength of 2.0, a maximum pore diameter of 35.0 μm, an average pore diameter of 8.0 μm, a swelling rate of 53.0%, a liquid retention rate of 638%, an ionic resistance of 14.0 mΩ, and a gas generation amount of 96 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 145 minutes, a 100Ω discharge time of 239 hours, and no defective intermittent discharge.

[Example 3]
30% by mass of solvent-spun cellulose fibers (fineness: 3.3 dtex, fiber length: 5 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 100 ml, which started to rise. 15% by mass of viscose rayon fiber (fineness 1.7 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) 15 as alkali resistant synthetic fiber 15 20% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed.

This mixed raw material was laminated and paper-made at a J/W ratio of 1.6 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 140.0 μm and a basis weight of 45.0 g/m ² . This separator has an aspect ratio of tensile strength of 1.8, a maximum pore diameter of 15.0 μm, an average pore diameter of 1.1 μm, a swelling rate of 51.0%, a liquid retention rate of 571%, an ionic resistance of 13.9 mΩ, and a gas generation amount of 114 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 155 minutes, a 100Ω discharge time of 258 hours, and the number of defective intermittent discharges was 0.

[Example 4]
20 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 5 mm) were beaten to a CSF value of 8 ml. 10% by mass of viscose rayon fiber (fineness 0.8 dtex. fiber length 4 mm) as alkali resistant cellulose fiber, 30% by mass of hardwood dissolving pulp and vinylon fiber (fineness 0.6 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 10 % By mass and PVA fiber (fineness 1.1 dtex. fiber length 2 mm) 10% by mass and PP fiber (fineness 0.8 dtex. fiber length 5 mm) 10% by mass, PVA binder fiber as binder component (fineness 1.1 dtex. fiber length 3 mm) ) 10% by weight were mixed. This mixed raw material was laminated and paper-made with a fourdrinier/cylinder combination paper machine at a J/W ratio of 2.1 to obtain a two-layer separator having a thickness of 95.0 μm and a basis weight of 30.0 g/m ² .

This separator has an aspect ratio of tensile strength of 2.4, a maximum pore diameter of 33.0 μm, an average pore diameter of 8.1 μm, a swelling rate of 53.0%, a liquid retention rate of 622%, an ionic resistance of 12.4 mΩ, and a gas generation amount of 94 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 149 minutes, a 100Ω discharge time of 238 hours, and no defective intermittent discharge.

[Example 5]
20 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 5 ml. 40% by mass of viscose rayon fiber (fineness 0.6 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) and PVA fiber (fineness) as alkali resistant synthetic fiber. 1.1 mass/fiber length 2 mm) 10 mass% PP/modified PP composite fiber (fineness 0.8 dtex.fiber length 5 mm) 10 mass%, PVA binder fiber (fineness 1.1 dtex.fiber length 3 mm) 10 mass% as a binder component % Was mixed.

This mixed raw material was laminated and paper-made with a J/W ratio of 0.7 by an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 120.0 μm and a basis weight of 40.0 g/m ² . This separator has an aspect ratio of tensile strength of 1.6, a maximum pore diameter of 19.0 μm, an average pore diameter of 6.2 μm, a swelling ratio of 54.0%, a liquid retention rate of 674%, an ionic resistance of 12.8 mΩ, and a gas generation amount of 119 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 142 minutes, a 100Ω discharge time of 241 hours, and a defective number of intermittent discharges of 0.

[Example 6]
15 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 5 mm) were beaten to a CSF value of 2 ml. 15% by mass of viscose rayon fiber (fineness 3.3 dtex. fiber length 4 mm) as alkali resistant cellulose fiber and 20% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 2 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 20% by mass of 1.1 dtex. fiber length 2 mm), 10% by mass of PP/modified PE composite fiber (fineness 0.8 dtex. fiber length 5 mm), and 20% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component. % Was mixed.

This mixed raw material was laminated and paper-made at a J/W ratio of 0.6 with a tilted short-net/circle-net combination paper machine to obtain a two-layer separator having a thickness of 125.0 μm and a basis weight of 39.0 g/m ² . This separator has an aspect ratio of tensile strength of 1.8, a maximum pore diameter of 26.0 μm, an average pore diameter of 7.6 μm, a swelling rate of 45.0%, a liquid retention rate of 451%, an ionic resistance of 13.7 mΩ, and a gas generation amount of 86 μl/ It was g.
The alkaline battery manufactured using this separator had a 2Ω discharge time of 156 minutes, a 100Ω discharge time of 251 hours, and a defective number of intermittent discharges of 0.

[Example 7]
25% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 2 mm) were beaten to a CSF value of 0 ml. 25% by weight of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by weight of softwood dissolving pulp, 10% by weight of mercerized hardwood pulp, and vinylon fiber (fineness 0 as fineness of alkali resistant synthetic fiber. 6 dtex. fiber length 2 mm) 5% by mass, PVA fiber (fineness 1.1 dtex. fiber length 2 mm) 10% by mass, PA fiber (fineness 0.6 dtex. fiber length 3 mm) 10% by mass, PVA binder fiber as a binder component ( A fineness of 1.1 dtex and a fiber length of 3 mm) was mixed in an amount of 5% by mass.
This mixed raw material was laminated and paper-made at a J/W ratio of 1.3 with a tilted shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 74.0 μm and a basis weight of 24.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.4, a maximum pore diameter of 17.0 μm, an average pore diameter of 4.2 μm, a swelling rate of 55.0%, a liquid retention rate of 700%, an ionic resistance of 12.6 mΩ, and a gas generation amount of 122 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 149 minutes, a 100Ω discharge time of 246 hours, and a defective number of intermittent discharges of 0.

[Example 8]
20% by mass of solvent-spun cellulose fibers (fineness: 1.7 dtex; fiber length: 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 30 ml which started to rise. 10% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of cotton linter pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 25 25% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 1.2 with an inclined short-strip paper machine to obtain a separator having a thickness of 112.0 μm and a basis weight of 36.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.1, a maximum pore diameter of 24.0 μm, an average pore diameter of 5.5 μm, a swelling rate of 46.0%, a liquid retention rate of 502%, an ionic resistance of 13.1 mΩ, and a gas generation amount of 108 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 155 minutes, a 100Ω discharge time of 252 hours, and a defective number of intermittent discharges of 0.

[Example 9]
20% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm:) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 50 ml which started to rise. 30% by mass of viscose rayon fiber (fineness 0.8 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 15% by mass of mercerized softwood pulp, and PVA fiber (fineness 1.1 dtex. fiber length 2 mm) as alkaline resistant synthetic fiber. 10% by mass, 15% by mass of PE fiber (fineness 3.3 dtex. fiber length 5 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 2.0 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 83.0 μm and a basis weight of 27.0 g/m ² .

This separator has an aspect ratio of tensile strength of 2.3, a maximum pore diameter of 30.0 μm, an average pore diameter of 3.7 μm, a swelling rate of 53.0%, a liquid retention rate of 668%, an ionic resistance of 11.5 mΩ, and a gas generation amount of 101 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 141 minutes, a 100Ω discharge time of 240 hours, and a defective number of intermittent discharges of 0.

[Example 10]
10% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 75 ml which started to rise. 30% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 25% by mass of hardwood pulp and vinylon fiber (fineness 0.6 dtex. fiber length 3 mm) 10% as alkali resistant synthetic fiber. %, PVA fiber (fineness 1.1 dtex. fiber length 2 mm) 10% by mass, and PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) 15% by mass as a binder component. This mixed raw material was laminated and paper-made at a J/W ratio of 1.1 with a tilted shortnet/tilted shortnet combination paper machine to obtain a two-layer separator having a thickness of 94.0 μm and a basis weight of 32.0 g/m ² . ..

This separator has an aspect ratio of tensile strength of 1.2, a maximum pore diameter of 28.0 μm, an average pore diameter of 1.7 μm, a swelling ratio of 53.0%, a liquid retention rate of 645%, an ionic resistance of 13.4 mΩ, and a gas generation amount of 118 μl/ It was g.
The alkaline battery manufactured using this separator had a 2Ω discharge time of 139 minutes, a 100Ω discharge time of 241 hours, and the number of defective intermittent discharges was 0.

[Comparative Example 1]
2 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to 0 ml in CSF value. 33% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of hardwood dissolving pulp, and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 20 20% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 15% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 1.8 with a slanted dash/cylinder paper machine to obtain a two-layer separator having a thickness of 57.0 μm and a basis weight of 19.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.7, maximum pore diameter of 42.0 μm, average pore diameter of 7.8 μm, swelling ratio of 48.0%, liquid retention rate of 570%, ionic resistance of 17.0 mΩ, gas generation amount of 104 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 129 minutes, a 100Ω discharge time of 228 hours, and a defective intermittent discharge count of 10.

[Comparative Example 2]
35 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to 0 ml in CSF value. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 20% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 20% by mass of 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. The mixed raw material was laminated and paper-made at a J/W ratio of 2.0 with a Fourdrinier/Shortnet paper machine to obtain a two-layer separator having a thickness of 117.0 μm and a basis weight of 37.6 g/m ² .

This separator has an aspect ratio of tensile strength of 2.4, a maximum pore diameter of 13.0 μm, an average pore diameter of 1.6 μm, a swelling rate of 46.0%, a liquid retention rate of 558%, an ionic resistance of 25.0 mΩ, and a gas generation amount of 99 μl/ It was g. The alkaline battery produced using this separator had a 2Ω discharge time of 109 minutes, a 100Ω discharge time of 193 hours, and a defective number of intermittent discharges of 0.

[Comparative Example 3]
20 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 20 ml. 20% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of hardwood dissolving pulp, and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 15 20% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 15% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 1.6 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 143.0 μm and a basis weight of 46.0 g/m ² . ..

This separator has an aspect ratio of tensile strength of 1.8, a maximum pore diameter of 34.0 μm, an average pore diameter of 13.0 μm, a swelling ratio of 50.0%, a liquid retention rate of 570%, an ionic resistance of 11.2 mΩ, and a gas generation amount of 101 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 133 minutes, a 100Ω discharge time of 226 hours, and a defective number of intermittent discharge of 8.

[Comparative Example 4]
20% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 150 ml which started to rise. 20% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 10% by mass of hardwood dissolving pulp, and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 15 20% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 15% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 1.3 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 42.0 μm and a basis weight of 14.0 g/m ² . ..

This separator has an aspect ratio of tensile strength of 1.6, a maximum pore diameter of 17.0 μm, an average pore diameter of 0.9 μm, a swelling ratio of 49.0%, a liquid retention rate of 566%, an ionic resistance of 24.6 mΩ, and a gas generation amount of 89 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 116 minutes, a 100Ω discharge time of 199 hours, and a defective intermittent discharge count of 0.

[Comparative Example 5]
20% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was beaten to a CSF value of 2 ml. 45% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 10% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 15% by mass of 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed.

This mixed raw material was laminated and paper-made at a J/W ratio of 0.6 with a tilted shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 155.0 μm and a basis weight of 50.0 g/m ² . .. This separator has an aspect ratio of tensile strength of 1.7, a maximum pore diameter of 20.0 μm, an average pore diameter of 9.4 μm, a swelling rate of 54.0%, a liquid retention rate of 664%, an ionic resistance of 14.4 mΩ, and a gas generation amount of 125 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 130 minutes, a 100Ω discharge time of 211 hours, and no defective intermittent discharge.

[Comparative Example 6]
20% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was beaten to a CSF value of 2 ml. 5% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 5% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 20 20% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 15% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed.

This mixed raw material was laminated and paper-made at a J/W ratio of 1.7 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 120.0 μm and a basis weight of 39.0 g/m ² . .. This separator has an aspect ratio of tensile strength of 1.8, maximum pore diameter of 32.0 μm, average pore diameter of 7.0 μm, swelling rate of 46.0%, liquid retention rate of 511%, ionic resistance of 12.4 mΩ, gas generation amount of 114 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 121 minutes, a 100Ω discharge time of 208 hours, and a defective number of intermittent discharges of 0.

[Comparative Example 7]
25 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 5 ml. 35% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 15% by mass of hardwood dissolving pulp, and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 10 10% by mass of PP fiber (fineness 3.3 dtex. fiber length 5 mm) and PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 0.9 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 138.0 μm and a basis weight of 44.0 g/m ² . ..

This separator has an aspect ratio of tensile strength of 1.6, a maximum pore diameter of 34.0 μm, an average pore diameter of 8.1 μm, a swelling ratio of 59.0%, a liquid retention rate of 754%, an ionic resistance of 24.4 mΩ, and a gas generation amount of 141 μl/ It was g. The alkaline battery produced using this separator had a 2Ω discharge time of 118 minutes, a 100Ω discharge time of 207 hours, and three defective intermittent discharges.

[Comparative Example 8]
15% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 5 ml. 10% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 20% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 20% by mass of 1.1 dtex. fiber length 2 mm), 15% by mass of PP fiber (3.3 dtex. fiber length 5 mm), and 20% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component. This mixed raw material was paper-made at a J/W ratio of 1.2 by an inclined short-strip paper machine to obtain a separator having a thickness of 88.0 μm and a basis weight of 28.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.1, a maximum pore diameter of 33.0 μm, an average pore diameter of 8.9 μm, a swelling ratio of 42.0%, a liquid retention rate of 434%, an ionic resistance of 10.8 mΩ, and a gas generation amount of 87 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 123 minutes, a 100Ω discharge time of 216 hours, and one defective intermittent discharge.

[Comparative Example 9]
20 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 8 ml. 20% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 20% by mass of hardwood dissolving pulp, and PVA fiber (fineness 1.1 dtex. fiber length 2 mm) as alkaline resistant synthetic fiber 5 15% by mass of PP fiber (3.3 dtex. fiber length 5 mm) and 20% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was laminated and paper-made at a J/W ratio of 1.4 with an inclined shortnet/cylinder combination paper machine to obtain a two-layer separator having a thickness of 100.0 μm and a basis weight of 33.0 g/m ² . ..

This separator has an aspect ratio of tensile strength of 1.5, a maximum pore diameter of 19.0 μm, an average pore diameter of 11.2 μm, a swelling rate of 53.0%, a liquid retention rate of 607%, an ionic resistance of 11.3 mΩ, and a gas generation amount of 93 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 108 minutes, a 100Ω discharge time of 196 hours, and no defective intermittent discharge.

[Comparative Example 10]
20 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 8 ml. 10% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 30% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 30% by mass of 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. The mixed raw material was subjected to paper making with a J/W ratio of 0.5 by a tilted braid paper machine to obtain a separator having a thickness of 104.0 μm and a basis weight of 34.0 g/m ² .
This separator has an aspect ratio of tensile strength of 2.2, a maximum pore diameter of 31.0 μm, an average pore diameter of 7.5 μm, a swelling ratio of 45.0%, a liquid retention rate of 475%, an ionic resistance of 13.1 mΩ, and a gas generation amount of 109 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 126 minutes, a 100Ω discharge time of 224 hours, and two defective intermittent discharges.

[Comparative Example 11]
30% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml, which started to rise. 35% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber, 15% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) as alkali resistant synthetic fiber, and PVA as binder component. 20% by mass of binder fiber (fineness 1.1 dtex. fiber length 3 mm) was mixed. This mixed raw material was subjected to papermaking with a cylinder paper machine at a J/W ratio of 2.1 to obtain a separator having a thickness of 71.0 μm and a basis weight of 23.0 g/m ² .
This separator has an aspect ratio of tensile strength of 2.3, a maximum pore size of 22 μm, an average pore size of 6.2 μm, a swelling rate of 52.0%, a liquid retention rate of 616%, an ionic resistance of 12.4 mΩ, and a gas generation rate of 117 μl/g. there were.
I tried to make an alkaline battery using this separator, but because the blending ratio of the alkali-resistant synthetic fiber was small and the bottom part could not be fused when trying to form it by heat fusion, the discharge test I haven't gone.

[Comparative Example 12]
30% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 4 mm) was further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml, which started to rise. 30% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali-resistant cellulose fiber and 19% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali-resistant synthetic fiber and PVA fiber (fineness) 19% by mass of 1.1 dtex. fiber length 2 mm) and 2% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 2.2 by an inclined short-net paper machine to obtain a separator having a thickness of 111.0 μm and a basis weight of 35.0 g/m ² .

This separator has an aspect ratio of tensile strength of 2.4, a maximum pore diameter of 24.0 μm, an average pore diameter of 5.6 μm, a swelling rate of 54.0%, a liquid retention rate of 648%, an ionic resistance of 10.5 mΩ, and a gas generation amount of 122 μl/ It was g.
An attempt was made to use this separator to manufacture an alkaline battery, but since the compounding ratio of PVA binder fiber, which is a binder component, was low, the separator strength was low, and defective tube molding occurred. Therefore, the discharge test was not conducted.

[Comparative Example 13]
Twenty-five mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml which started to rise. 20% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 15% by mass of vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant synthetic fiber and PVA fiber (fineness) 15 mass% of 1.1 dtex.fiber length 2 mm) and 25 mass% of PVA binder fiber (fineness 1.1 dtex.fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 1.7 with an inclined short-strip paper machine to obtain a separator having a thickness of 115.0 μm and a basis weight of 39.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.9, a maximum pore diameter of 17.0 μm, an average pore diameter of 5.0 μm, a swelling ratio of 42.0%, a liquid retention rate of 532%, an ionic resistance of 22.4 mΩ, and a gas generation amount of 94 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 114 minutes, a 100Ω discharge time of 215 hours, and a defective number of intermittent discharges of 0.

[Comparative Example 14]
15% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml which started to rise. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 25% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) 25 as alkali resistant synthetic fiber 25 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 0.4 by an inclined short-strip paper machine to obtain a separator having a thickness of 50.0 μm and a basis weight of 15.0 g/m ² .

This separator has an aspect ratio of tensile strength of 3.1, maximum pore diameter of 28.0 μm, average pore diameter of 11.8 μm, swelling rate of 51.0%, liquid retention rate of 586%, ionic resistance of 17.6 mΩ, gas generation rate of 131 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 124 minutes, a 100Ω discharge time of 233 hours, and a defective intermittent discharge count of 9.

[Comparative Example 15]
15% by mass of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 10 ml which started to rise. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 25% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) 25 as alkali resistant synthetic fiber 25 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 2.0 by an inclined short-net paper machine to obtain a separator having a thickness of 160.0 μm and a basis weight of 50.0 g/m ² .

This separator has an aspect ratio of tensile strength of 2.0, a maximum pore diameter of 18.0 μm, an average pore diameter of 8.4 μm, a swelling rate of 52.0%, a liquid retention rate of 603%, an ionic resistance of 24.1 mΩ, and a gas generation amount of 129 μl/ It was g.
The alkaline battery produced using this separator had a 2Ω discharge time of 122 minutes, a 100Ω discharge time of 194 hours, and two defective intermittent discharges.

[Comparative Example 16]
Twenty-five mass% of the solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were further beaten even after the CSF value showed 0 ml, and beaten to a CSF value of 50 ml, which started to rise. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 15% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkaline resistant synthetic fiber 25 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. This mixed raw material was paper-made at a J/W ratio of 1.0 by an inclined short-strip paper machine to obtain a separator having a thickness of 105.0 μm and a basis weight of 31.0 g/m ² .

This separator has an aspect ratio of tensile strength of 0.7, a maximum pore diameter of 12.0 μm, an average pore diameter of 2.6 μm, a swelling ratio of 52.0%, a liquid retention rate of 596%, an ionic resistance of 13.5 mΩ, and a gas generation amount of 110 μl/ It was g. An attempt was made to make an alkaline battery using this separator, but the T/Y ratio was too small, so there was no stiffness, and a defect occurred during cylinder molding, so the discharge test was not conducted.

[Comparative Example 17]
15 mass% of solvent-spun cellulose fibers (fineness 1.7 dtex. fiber length 4 mm) were beaten to a CSF value of 5 ml. 15% by mass of viscose rayon fiber (fineness 1.1 dtex. fiber length 3 mm) as alkali resistant cellulose fiber and 25% by mass of hardwood dissolving pulp and vinylon fiber (fineness 1.1 dtex. fiber length 3 mm) 25 as alkali resistant synthetic fiber 25 10% by mass of PVA fiber (fineness 1.1 dtex. fiber length 2 mm) and 10% by mass of PVA binder fiber (fineness 1.1 dtex. fiber length 3 mm) as a binder component were mixed. The mixed raw material was subjected to paper making with a J/W ratio of 3.8 using an inclined short-strip paper machine to obtain a separator having a thickness of 100.0 μm and a basis weight of 29.0 g/m ² .

This separator has an aspect ratio of tensile strength of 4.5, a maximum pore size of 37.0 μm, an average pore size of 9.8 μm, a swelling rate of 51.0%, a liquid retention rate of 584%, an ionic resistance of 13.1 mΩ, and a gas generation rate of 108 μl/ It was g. The alkaline battery produced using this separator had a 2Ω discharge time of 151 minutes, a 100Ω discharge time of 252 hours, and a defective intermittent discharge count of 9.

[Conventional example 1]
In International Publication WO 2012/036025 (Patent Document 3), a separator has a laminated structure composed of at least two layers of a coarse layer and a dense layer, and alkali-resistant cellulose fibers constituting the coarse layer are provided in a specific ratio. In addition, by forming from a plurality of types of cellulose fibers having a specific CSF difference, and by setting the CSF of the entire alkali-resistant cellulose fiber to a specific value, while achieving liquid retention by the high CSF cellulose fiber, It is possible to reduce the maximum pore size present in the separator by the low cellulose fiber, while not only effectively suppressing the generation of dendrite while ensuring the liquid retention required for alkaline batteries, it is possible to improve the impact resistance of the separator. Have been described.

The separator of Conventional Example 1 is the separator described in Example 10 of International Publication WO 2012/036025, which is publicly known before the application of the present application, and is solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 2 mm) 15 The mass% was beaten to a CSF value of 150 ml. 30% by mass of mercerized hardwood pulp beaten to 705 ml as an alkali-resistant cellulose fiber, vinylon fiber (fineness 0.3 dtex. fiber length 2 mm) 40% by mass as an alkali-resistant synthetic fiber, and PVA binder fiber (as a binder component ( A fine layer having a fineness of 1.1 dtex and a fiber length of 3 mm (15 mm) was mixed to form a rough layer.

On the other hand, 50% by mass of solvent-spun cellulose fiber (fineness 1.7 dtex. fiber length 2 mm) was beaten to a CSF value of 125 ml. 35% by mass of vinylon fiber (fineness: 0.3 dtex. fiber length: 2 mm) as an alkali-resistant synthetic fiber and 15% by mass of PVA binder fiber (fineness: 1.1 dtex: fiber length: 3 mm) as a binder component were mixed to form a dense layer. The two types of mixed raw materials were laminated with a cylinder multi-layer paper machine at a J/W ratio of 1.7 to form a laminated paper to obtain a separator having a thickness of 90.0 μm and a basis weight of 28.0 g/m ² .

This separator has an aspect ratio of tensile strength of 1.8, a maximum pore diameter of 61.0 μm, an average pore diameter of 12.0 μm, a swelling ratio of 38%, a liquid retention rate of 512%, an ionic resistance of 13.4 mΩ, and a gas generation amount of 127 μl/g. there were.
The alkaline battery manufactured using this separator had a 2Ω discharge time of 135 minutes, a 100Ω discharge time of 226 hours, and two defective intermittent discharges.

Table 2 shows the physical properties of the separators of the examples, comparative examples, and conventional examples described above and the evaluation results of alkaline batteries.
Regarding the value of CSF in Table 2, the value with * indicates the value obtained as a result of further refining after the CSF reached 0 mm.

Hereinafter, each example, comparative example, and conventional example will be described in detail.
Each of the examples has an aspect ratio of tensile strength of 1.0 to 2.5, a maximum pore diameter of 15.0 to 35.0 μm, an average pore diameter of 1.0 to 10.0 μm, and a liquid retention rate of 450 to 700%. .. Comparing the battery test result of each example with the battery test result of the conventional example, two defects due to intermittent discharge occurred in the conventional example, but none in the example. Further, the light load discharge time at 100Ω in each example is longer than the conventional example.
That is, it can be seen that the separator of the present embodiment is a good separator having both the shielding property, which has been said to be a contradictory property up to now, and the discharge performance.

In the alkaline battery using the separator of Comparative Example 1, ten defective intermittent discharge occurred. It is considered that this is because the content of the fibrillated solvent-spun cellulose fiber was as small as 2% by mass, and the maximum pore diameter exceeded 35 μm.
On the other hand, the separator of Comparative Example 2 has a high ionic resistance of 25 mΩ, and the alkaline battery using this separator has shorter discharge times for both light load discharge and high rate load discharge than the conventional example.

It is considered that this is because the content of the fibrillated solvent-spun cellulose fiber was set to 35% by mass, so that the maximum pore size was set to less than 15 μm.

From each of the Examples and Comparative Examples 1 and 2, it is understood that the content of the fibrillated solvent-spun cellulose fiber is preferably 5 to 30% by mass.

In the separator of Comparative Example 3, the solvent-spun cellulose fiber has a CSF value of 20 ml. Therefore, the average pore diameter of the separator was 13.0 μm, and the alkaline battery using this separator had eight intermittent discharge defects.
The separator of Comparative Example 4 has a CSF value of 150 ml in which the CSF value of the solvent-spun cellulose fiber has turned to an increase. Therefore, the ionic resistance of the separator was increased, and the discharge time of the alkaline battery using this separator was shortened.

From each of the Examples and Comparative Examples 3 and 4, the average pore diameter of the separator is preferably 1.0 to 10.0 μm, and the CSF value of the fibrillated solvent-spun cellulose fiber is 10 to 0 ml as a means for achieving this. It can be seen that it is preferable to set the CSF value that has turned to an increase to 0 to 100 ml.
In the separator of Comparative Example 5, the content of the non-fibrillated regenerated cellulose fiber was 45% by mass, the swelling ratio of the separator was large, and the amount of the injected negative electrode agent was reduced during the production of the alkaline battery. The battery discharge time has become shorter.

In the separator of Comparative Example 6, the content of the non-fibrillated regenerated cellulose fiber was less than 5% by mass, the liquid retention rate of the separator was low, and the discharge time of the alkaline battery using this separator was shortened.
From each of the Examples and Comparative Examples 5 and 6, it is understood that the content of the non-fibrillated regenerated cellulose fiber is preferably 10 to 40% by mass.
The alkaline battery using the separator of Comparative Example 7 has three intermittent discharge defects. It is considered that this is because the total content of the cellulose fibers was as high as 75% by mass, and the gas generation amount of the separator increased.

On the other hand, the separator of Comparative Example 8 has a small total content of cellulose fibers of 25% by mass and a large total content of synthetic fibers of 55% by mass. Therefore, it is considered that the liquid retention rate of the separator was reduced and the discharge time of the alkaline battery was shortened.
From each of the Examples and Comparative Examples 7 and 8, it is understood that the total content of the alkali-resistant cellulose fibers is preferably 30 to 70% by mass.

The separator of Comparative Example 9 has a small total content of vinylon fibers and PVA fibers of 5% by mass. Therefore, the swelling rate of the separator is as large as 53%. For this reason, the amount of the injected negative electrode agent was reduced during the production of the alkaline battery, and the discharge time of the alkaline battery using this separator was shortened.

The separator of Comparative Example 10 has a large total content of vinylon fibers and PVA fibers of 60% by mass. For this reason, the hydrophobicity of the separator was strengthened and the amount of retained liquid was reduced, resulting in a shorter discharge time of the alkaline battery.
From each of the Examples and Comparative Examples 9 and 10, it is understood that the total content of vinylon fiber and PVA fiber is preferably 10 to 50% by mass.

In the separator of Comparative Example 11, the total content of synthetic fibers was as small as 15% by mass, and the bottom of the cylinder could not be thermally attracted during the molding of the separator cylinder during battery production. Therefore, no battery test was conducted.
From each of the Examples and Comparative Examples 8 and 11, it is understood that the total content of the synthetic fibers is preferably 20 to 50% by mass.

In the separator of Comparative Example 12, the strength of the sheet was weak, and the separator was broken during the tubular molding of the separator during battery production. This is because the content of the binder component is as small as 2% by mass. Further, the battery test was not conducted because the separator was damaged during the cylinder molding.

The separator of Comparative Example 13 had a low liquid retention rate, and the discharge time of the alkaline battery using this separator was short. This is because the content of the binder component is as high as 25% by mass.

From each of the Examples and Comparative Examples 12 and 13, it is understood that the content of the binder component is preferably 5 to 20% by mass.

The separator of Comparative Example 14 has a thickness of 50 μm and a basis weight of 15.0 g/m ² . Since the separator has a small basis weight and a low density, the separator is insufficient in denseness and has a large maximum pore diameter of 28.0 μm and an average pore diameter of 11.8 μm, and an alkaline battery using this separator has a defective intermittent discharge of 9%. Occurred individually.

The separator of Comparative Example 15 has a thickness of 160 μm and a basis weight of 50.0 g/m ² . Therefore, the discharge time of the alkaline battery using this separator was shortened.
The bending rigidity of the separator of Comparative Example 16 was low, and a defect occurred during the molding of the separator cylinder during battery production. Therefore, no battery evaluation was performed. It is considered that this is because the aspect ratio of tensile strength became less than 1.0.

The maximum pore size of the separator of Comparative Example 17 is as large as 62 μm. It is considered that this is because the aspect ratio of tensile strength is 4.5. Nine defects occurred during intermittent discharge of an alkaline battery using this separator.
From each of Examples, Comparative Example 16 and Comparative Example 17, the maximum pore size is preferably 15 to 35 μm, and in order to realize these, the aspect ratio of the tensile strength of the separator is set to 1.0 to 2.5. It turns out that is preferable.

When an alkaline battery was manufactured using the separator of Conventional Example 1, when the electrolytic solution was impregnated, the curl of the separator, which is considered to be due to the difference in the expansion and contraction degree of each layer in the electrolytic solution, was generated in the inner direction of the cylinder. .. Therefore, the workability of the step of injecting the gelled negative electrode into the cylinder of the separator is poor.

As described above, according to the present embodiment, it is possible to provide a separator having a controlled maximum pore diameter and high shielding property. Further, by controlling the aspect ratio of the tensile strength, it becomes a separator having appropriate bending rigidity as a separator for alkaline batteries, and the reliability of the alkaline battery using the separator of the present embodiment in preventing internal short circuit is improved. In addition, the workability of the separator during battery production can be improved.

Further, the multi-layer separator of the present embodiment is made of the same raw material for each layer, and since there is no difference between the front and the back of the separator, it does not warp (curl) when immersed in an alkaline electrolyte.
Further, by setting the CSF value of the solvent-spun cellulose fiber to 10 to 0 ml and the CSF value that has turned to an increase to 0 to 100 ml, a separator having a more suitable shielding property as an alkaline battery separator can be obtained.
Then, by using the non-fibrillated regenerated cellulose fiber as the alkali resistant cellulose fiber other than the solvent-spun cellulose fiber, the liquid retaining property of the separator can be further improved.

Further, by adopting vinylon fiber or PVA fiber as the alkali-resistant synthetic fiber, a separator having a good swelling rate while exhibiting good liquid retention and improved thermal fusion bonding property between the separators can be realized. By using this separator in an alkaline battery, workability in the battery manufacturing process is improved. Further, an alkaline battery having a high electrolyte retaining property and excellent discharge characteristics can be obtained.

Claims (2)

A wet non-woven fabric containing at least 30 to 70% by mass of alkali resistant cellulosic fibers and 20 to 50% by mass of alkali resistant synthetic fibers, which is settled with a binder component of 5 to 20% by mass ,
As the alkali resistant cellulose fiber, contains 5 to 30% by mass of fibrillated solvent-spun cellulose fiber and 10 to 40% by mass of non-fibrillated regenerated cellulose fiber,
As the alkali-resistant synthetic fiber, containing 10 to 50 mass% non-acetalized polyvinyl alcohol fiber and / or acetalized polyvinyl alcohol fiber,
The wet-type nonwoven fabric has a maximum pore size of 15 to 35 μm,
Average pore size 1 to 10 μm,
The liquid retention rate when immersed in a 40 mass% KOH aqueous solution is 450 to 700%,
The swelling rate when immersed in a 40 mass% KOH aqueous solution is 45 to 55%,
An alkaline battery separator having a thickness of 60 to 140 μm . An alkaline battery comprising the alkaline battery separator according to claim 1.

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