JP3864153B2 - Alkaline battery separator and alkaline battery - Google Patents

Description

  The present invention relates to an alkaline battery separator that can be suitably used for an alkaline secondary battery such as a nickel-cadmium battery, a nickel-zinc battery, or a nickel-hydrogen battery, and an alkaline battery using the separator. More specifically, the present invention relates to a separator for an alkaline battery having a thin thickness that is excellent in alkali resistance, oxidation resistance, dendrite durability, and cut resistance, and capable of increasing the capacity, and an alkaline battery using the separator.

Alkaline secondary batteries are excellent in charge / discharge characteristics and overcharge / discharge characteristics, and can be used repeatedly with a long life, and thus are widely used in electronic devices and the like. Usually, a separator for separating an anode active material and a cathode active material is used in an alkaline secondary battery. The characteristics required for this separator are the prevention of internal short circuit due to contact between the anode active material and the cathode active material, and excellent alkali resistance and charge / discharge without causing shrinkage or alteration to the electrolyte such as potassium hydroxide. It has oxidation resistance during the accompanying oxidation-reduction reaction, and holds a sufficient amount of electrolyte necessary to generate an electromotive reaction, permeates the gas generated by the electrode reaction, and hinders ion conduction. Therefore, the internal resistance can be reduced and the occupation ratio when incorporated in the battery is small, and the amount of the anode active material and the cathode active material can be increased.
In addition to the tensile strength that can counter the tension of the battery manufacturing process and the mechanical properties such as the cut-resistant strength against burrs of the pole material during winding, the alkaline battery separator has running stability in a group winding configuration. Is also required.

2. Description of the Related Art In recent years, alkaline secondary batteries have been “miniaturized” and “increased in capacity” as electronic devices have become lighter and smaller. In response to these demands, attempts have been made to increase the amount of positive electrode active material and negative electrode active material by lowering the basis weight of the separator and reducing the thickness, thereby increasing the capacity of the battery. However, in general, when the weight of the separator is lowered and the thickness is reduced, the liquid retention property is lowered. Therefore, when charging and discharging are repeated, there arises a problem that the life of the separator is shortened due to liquid drainage (dry out). Furthermore, the through-holes in the thickness direction are increased due to the lower density of the separator, the dendrite durability is lowered, and a short circuit is likely to occur between the positive electrode and the negative electrode. In particular, in the case of a dry nonwoven fabric, if the basis weight is lowered and the thickness is reduced, the uniformity of the sheet is remarkably impaired, and there is a problem that a short circuit is likely to occur between the positive electrode and the negative electrode. The dendrite is a phenomenon in which metal ions dissolved in the electrolyte during discharge grow on the surface of the metal electrode during charging, and are particularly likely to occur during overcharging.
On the other hand, in a wet nonwoven fabric, if the basis weight is lowered and the thickness is reduced, mechanical strength such as tensile strength is remarkably lowered, and there is a problem that a group winding configuration cannot be achieved.

  As an alkaline battery separator, a polyamide fiber non-woven fabric that is easily wetted with an electrolyte, has a large amount of liquid retention, and has a low electrical resistance in a state containing the electrolyte is used. The alkaline secondary battery using this polyamide fiber nonwoven fabric has a feature of excellent discharge characteristics at a large current. However, the polyamide fibers constituting the polyamide fiber nonwoven fabrics conventionally used are aliphatic polyamide fibers such as nylon 6 and nylon 66, which are chemically resistant although they have excellent alkali resistance and electrolyte retention. There is a drawback in that it lacks stability and is oxidized in the electrolytic solution to cause decomposition. Therefore, an alkaline secondary battery using such a nonwoven fabric composed of aliphatic polyamide fibers as a nonwoven fabric for battery separators has a large self-discharge due to the decomposition of the nonwoven fabric, and the alkaline secondary battery that is repeatedly charged and discharged particularly at high temperatures. The secondary battery has a problem that the cycle life is shortened.

On the other hand, separators made of polyolefin fiber nonwoven fabric are used in alkaline secondary batteries that require durability at relatively high temperatures. Since the polyolefin fiber nonwoven fabric is hydrophobic, it has a drawback that it is difficult to wet with the electrolyte solution and its liquid retention amount is small. Therefore, there is a problem in that the non-woven fabric for alkaline battery separator has high electric resistance, and the rapid charge and large current discharge of the battery are inferior to the polyamide fiber non-woven fabric.
Further, there is a problem that the electrolytic solution held between the fibers is pushed out from the inside of the separator by the gas pressure of oxygen gas generated from the positive electrode during charging. Further, since the positive electrode expands due to repeated charge and discharge, if the liquid retention of the alkaline battery separator is insufficient, the separator may be dried out.

  The nonwoven fabric for alkaline battery separator may be subjected to a surfactant treatment or the like. However, the surfactant has a problem with the electrolytic solution resistance, and when it is used in a cycle, a certain period has passed. There is a problem that the surfactant is liberated, and it has not sufficiently improved the liquid absorbability and liquid retention of the electrolytic solution.

  Therefore, as a method of improving the liquid absorbency and liquid retention of an alkaline battery separator made of a polyolefin fiber nonwoven fabric, a method of sulfonation by treating with hot concentrated sulfuric acid, fuming sulfuric acid, or chlorosulfuric acid (Patent Document) 1 and Patent Document 2), a method of treating with a reaction gas containing sulfur trioxide (see Patent Document 3), a method of graft polymerization of a group having a hydrophilic group such as acrylic acid and methacrylic acid (Patent Document 4 and Patent Document) 5), and a method of sulfonating a nonwoven fabric composed of sea-island type composite fibers capable of generating polypropylene ultrafine fibers (see Patent Document 6) has been proposed. There are problems such as extremely worsening, lowering the basis weight, and reducing the thickness, making it difficult to produce industrially stable.

Moreover, as a measure to prevent the burrs of the positive and negative electrode plates from penetrating the separator and causing the electrodes to short-circuit each other or to tear the separator by the edge of the electrode plate, nylon 6 fiber and nylon 66 fiber are mainly used. Has been proposed (see Patent Document 7 and Patent Document 8), but as described above, aliphatic polyamide fibers lack chemical stability and are oxidized in the electrolyte. Since it has a defect that causes decomposition, it does not have satisfactory performance as a separator for alkaline batteries.
Furthermore, a battery separator (see Patent Document 9 and Patent Document 10) composed of a non-woven fabric mainly composed of a specific aromatic polyamide is proposed as an alkaline battery separator having excellent electrolyte solution retention and oxidation resistance. However, the burrs of the positive and negative electrode plates still penetrate the separator and short-circuit each other, or the separator is torn by the edge of the electrode plate.

  On the other hand, a separator made of a sheet containing high-strength polyolefin fibers has also been proposed (see Patent Document 11 and Patent Document 12). However, since polyolefin fibers are hydrophobic as described above, they are wet with respect to the electrolyte. There is a drawback that the amount of liquid to be retained is small. In addition, when the hydrophilic treatment described above is performed in order to improve the liquid absorbency or liquid retention of the electrolyte, the separator has a large strength reduction or appearance even though it contains high strength fibers. However, there is a problem that it is difficult to produce industrially stably when trying to reduce the thickness by reducing the weight per unit area.

  In addition, a separator (see Patent Document 13) made of a sheet that includes polyparaphenylenebenzobisoxazole fibers for reinforcement and is entangled three-dimensionally has also been proposed. Therefore, it is necessary for the water flow to be three-dimensionally entangled with each other. As a result, in a low-weight separator, a short circuit due to a pinhole may occur. Further, since the pore diameter is increased, there is a problem that a dendrite short circuit is likely to occur.

  Furthermore, a separator made of a wet nonwoven fabric containing high strength fibers of 20 g / d or more and having a thickness of 120 μm or less (see Patent Document 14) has been proposed. In order to reduce the diameter, it is necessary to reduce the fineness of the fibers constituting the non-woven fabric. Especially in the case of a separator of 100 μm or less, the pore diameter cannot be reduced without using ultrafine fibers of 0.1 dtex or less. The problem of generating is included.

Japanese Patent Laid-Open No. 56-3973 JP 58-175256 A Japanese Patent Laid-Open No. 1-132042 Japanese Patent Laid-Open No. 5-234777 JP-A-6-196141 Japanese Patent Laid-Open No. 10-326607 JP 2000-100409 A JP 2001-266832 A JP-A-9-259856 JP 2002-151041 A JP 2000-353509 A Japanese Patent Laid-Open No. 2001-155709 JP 2002-151043 A JP 2002-25529 A

  The present invention solves the above-mentioned problems, and an object of the present invention is to provide a separator for an alkaline battery that is excellent in alkali resistance, oxidation resistance, dendrite durability and cut resistance, and that can be thinned and increased in capacity. It is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found that 60 mol% or more of the dicarboxylic acid component is an aromatic carboxylic acid component and 60 mol% or more of the diamine component is carbon. By comprising at least a thermoplastic polyamide fiber composed of a diamine component which is an aliphatic alkylene diamine of 6 to 12, and a para-aromatic polyamide fiber, alkali resistance, oxidation resistance, dendrite durability and cut resistance The inventors have found that a separator for an alkaline battery having excellent properties can be obtained, and have completed the present invention based on these findings.

  That is, the present invention relates to a drawn yarn of thermoplastic polyamide fiber, a para-aromatic polyamide fiber, an undrawn yarn of thermoplastic polyamide fiber, a fiber comprising an ethylene-vinyl alcohol copolymer, and an ethylene-vinyl alcohol copolymer. A separator for an alkaline battery comprising a nonwoven fabric containing at least one binder fiber selected from the group consisting of a composite fiber as a single component, wherein the thermoplastic polyamide fiber has an aromatic carboxylic acid content of 60 mol% or more of the dicarboxylic acid component. It is a separator for alkaline batteries composed of a dicarboxylic acid component that is an acid component and a diamine component in which 60 mol% or more of the diamine component is an aliphatic alkylenediamine having 6 to 12 carbon atoms.

The separator for alkaline batteries of the present invention is a diamine in which 60 mol% or more of the dicarboxylic acid component is an aromatic carboxylic acid component and 60 mol% or more of the diamine component is an aliphatic alkylenediamine having 6 to 12 carbon atoms. A thermoplastic polyamide fiber composed of a component, preferably having a fineness of 0.01 to 2.0 dtex, and synthesized from a 1,9-nonanediamine component and a 2-methyl-1,8-octanediamine component By comprising a nonwoven fabric composed of at least a plastic polyamide and a para-aromatic polyamide fiber having a fineness of 0.5 to 2.0 dtex, the separator has a high strength retention after treatment with a KMnO4 + KOH mixed aqueous solution, and has a leak resistance. It has excellent low-rate life and high-rate discharge characteristics, and requires high-current discharge and high capacity. It can be suitably used as a separator for alkaline batteries being.
Further, the basis weight is 20 to 75 g / m ² , the thickness is 50 to 200 μm, the tensile strength is 1000 N / m or more, the average pore diameter is 5 to 30 μm, the maximum pore diameter is 50 μm or less, and the cut strength is 100 mN · m ² / g. With the above, it is possible to further increase the capacity.

Hereinafter, the alkaline battery separator of the present invention will be described in detail.
The alkaline battery separator of the present invention is a diamine in which 60 mol% or more of the dicarboxylic acid component is an aromatic carboxylic acid component and 60 mol% or more of the diamine component is an aliphatic alkylenediamine having 6 to 12 carbon atoms. It is composed at least of a thermoplastic polyamide fiber composed of components and a para-aromatic polyamide fiber, and satisfies the physical property values required for alkali resistance and cut resistance of the separator It is.

  That is, by using a thermoplastic polyamide fiber that has excellent chemical stability such as alkali resistance and oxidation resistance and has low electrical resistance in a state containing an electrolytic solution, self-discharge and cycle due to degradation and decomposition of the fiber The discharge characteristics at a large current are improved without adversely affecting the service life, and further, the use of para-aromatic polyamide fibers in combination prevents shorting due to separator burrs and edge damage. With such a fiber configuration, the separator softens even when the battery temperature exceeds 180 ° C. in a nickel-cadmium battery for a power tool or a nickel-hydrogen battery particularly requiring high-rate discharge characteristics. It is possible to prevent the battery life from being shortened, for example, the deformation hardly occurs and the permeability of oxygen generated from the positive electrode to the negative electrode does not deteriorate.

Subsequently, each constituent fiber used in the present invention will be described in detail.
In the polyamide constituting the thermoplastic polyamide fiber used in the present invention, 60 mol% or more of the dicarboxylic acid component is an aromatic dicarboxylic acid, and 60 mol% or more of the diamine component is an aromatic alkylenediamine having 6 to 12 carbon atoms. .

As the aromatic dicarboxylic acid component, terephthalic acid is most preferable from the viewpoint of the heat resistance and chemical resistance of the separator. Isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid Acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, dibenzoic acid, 4,4′-oxydibenzoic acid, diphenylmethane-4,4′-dicarboxylic acid, diphenylsulfone One or more aromatic dicarboxylic acids such as -4,4'-dicarboxylic acid and 4,4'-biphenyldicarboxylic acid can be used in combination.
The content of the aromatic dicarboxylic acid is 60 mol% or more of the dicarboxylic acid component, and preferably 75 mol% or more. When the content of the aromatic dicarboxylic acid is less than 60 mol%, the physical properties such as alkali resistance, oxidation resistance, and strength of the resulting fiber are lowered, and the alkaline battery separator of the present invention is used. I can't get it.

Examples of dicarboxylic acids other than the aromatic dicarboxylic acid include malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, Aliphatic dicarboxylic acids such as trimethyladipic acid, pimelic acid, azelaic acid, sebacic acid and suberic acid; and alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid These acids can be used not only in one kind but also in two kinds or more.
In particular, the dicarboxylic acid component is preferably composed of 100% aromatic dicarboxylic acid in terms of the strength, chemical resistance, heat resistance, etc. of the separator for alkaline batteries.
Furthermore, polyvalent carboxylic acids such as trimetric acid, trimesic acid, pyromellitic acid and the like can be contained within a range where fiberization and nonwoven fabric formation are easy.

Further, 60 mol% or more of the diamine component is composed of alkylene diamine having 6 to 12 carbon atoms, and examples of the aliphatic alkylene diamine include 1,6-hexanediamine, 1,8-octanediamine, and 1,9-nonanediamine. 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,2,4- Linear or side of trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, etc. Examples include aliphatic diamines having a chain.
The content of the aliphatic alkylene diamine is 60 mol% or more of the diamine component, but is preferably 75 mol% or more, particularly 90 mol% or more, from the viewpoint of heat resistance. When the content of the aliphatic diamine component is less than 60 mol%, the oxidation resistance, strength, etc. of the resulting fiber are lowered, and the alkaline battery separator of the present invention cannot be obtained.
Among these, 1,9-nonanediamine is preferable from the viewpoint of heat resistance and chemical resistance, and the combined use of 1,9-nonanediamine and 2-methyl-1,8-octanediamine is more preferable. And 60-100 mol% of the diamine component consists of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, and the molar ratio of 1,9-nonanediamine and 2-methyl-1,8-octanediamine. Is preferably 99: 1 to 40:60, and particularly preferably 90:10 to 45:55.

Further, in the thermoplastic polyamide used in the present invention, it is preferable that 10% or more of the end groups of the molecular chain are sealed with a terminal blocking agent, and that 40% or more of the ends are sealed. More preferably, 70% or more of the ends are sealed. By sealing the ends of the polyamide, the strength, alkali resistance, oxidation deterioration resistance, and the like of the obtained alkaline battery separator are excellent. In addition, in calculating | requiring a terminal blocking rate, it can calculate | require by measuring the number of the terminal blocked | closed with the carboxyl group terminal, amino group terminal, and terminal blocker which exist in polyamide, respectively. The number of each terminal group is preferably determined from the integral value of the characteristic signal corresponding to each terminal group by ¹ H-NMR in terms of accuracy and simplicity.

  The end capping agent is not particularly limited as long as it is a monofunctional compound having reactivity with the amino group or carboxyl group at the end of the polyamide, but it is monolithic from the viewpoints of reactivity and stability of the capping end. Carboxylic acid and monoamine are preferred.

  The method for producing the polyamide is not particularly limited, and any production method known as a method for producing crystalline polyamide can be used. For example, it can be produced by a solution polymerization method using an acid chloride and a diamine as raw materials, an interfacial polymerization method, a melt polymerization method using a dicarboxylic acid and a diamine as raw materials, a solid phase polymerization method, or a melt extruder polymerization method.

  As a method for producing a thermoplastic polyamide fiber, it can be spun by a conventionally known general melt spinning method, and a spinning raw yarn once wound can be used as an undrawn yarn, which is wet-heat drawn or dried. A drawn yarn can be obtained by hot drawing. At this time, the intrinsic viscosity of the polymer is preferably 0.5 to 1.5 dl / g. When the intrinsic viscosity of the polymer is less than 0.5 dl / g, the spinnability at the time of spinning is poor, and even if the fiber can be made into fibers, the fiber strength and chemical resistance of the obtained fiber are low. Not satisfied as a battery separator. On the other hand, if the intrinsic viscosity of the polymer exceeds 1.5 dl / g, fibers suitable for alkaline battery separators may not be obtained. Further, a surfactant may be added at the fiberization stage for the purpose of improving the single fiber dispersibility in forming a nonwoven fabric by a wet papermaking method. Each of the obtained fibers can be cut into a desired fiber length to obtain a thermoplastic polyamide fiber for use in the alkaline battery separator of the present invention.

  Also, when producing thermoplastic polyamide fibers with a fineness of less than 0.1 dtex, it is difficult to obtain ultrafine fibers by simply spinning thermoplastic polyamide, and therefore spinning multicomponent fibers containing thermoplastic polyamide as one component is spun. In addition, it is preferable to employ a method of removing or dividing other components of the obtained multicomponent fiber. Among them, it is preferable to employ a method in which sea-island fibers containing thermoplastic polyamide as island components are spun and then the sea components in the sea-island fibers are removed. The polymer that is composite-spun or mixed-spun with the thermoplastic polyamide is not particularly limited as long as it is a thermoplastic polymer that can be removed without substantially impairing the performance of the thermoplastic polyamide. For example, an easily alkali-reducing polyester that can be removed with an alkaline aqueous solution can be mentioned, and it is preferable to use an easily alkali-reducing polyester from the viewpoints of spinnability, weight loss processability, cost, and the like.

Next, the para-type aromatic polyamide fiber used in the present invention will be described.
Examples of the para-aromatic polyamide fiber used in the alkaline battery separator of the present invention include polyparaphenylene terephthalamide, polyparabenzamide, polyparaamide hydrazide, polyparaphenylene terephthalamide-3,4-diphenyl ether terephthalamide, and the like. The fiber which consists of these resin can be mentioned.
As a method for producing such a para-aromatic polyamide fiber, a known liquid crystal spinning method may be employed. That is, it can be fiberized by a dry-wet spinning method in which an anisotropic solution of a para-aromatic polyamide polymer is spun from a die through an air gap into a coagulation bath, and then washed and neutralized. Crystallinity and crystal orientation are further improved by heat-treating the obtained fiber under high temperature and high tension, and a highly strong para-aromatic polyamide fiber can be obtained.

  In the alkaline battery separator of the present invention, at least a part of the separator is preferably thermally bonded by fusion of the thermoplastic polyamide fibers. To make such a configuration, the thermoplastic polyamide fibers are drawn yarn and undrawn yarn. It is particularly preferable that it is composed of That is, by using the drawn yarn of the thermoplastic polyamide fiber as the main fiber and the undrawn yarn of the thermoplastic polyamide fiber as the binder fiber, the adhesiveness by heat bonding is extremely good because they are similar fibers, and It is also very excellent in terms of heat resistance.

The fineness of the thermoplastic polyamide fiber used for the alkaline battery separator of the present invention is preferably 0.01 to 2.0 dtex, more preferably 0.04 to 1.0 dtex, and further preferably 0.08 to 0.7 dtex. . When the fineness is less than 0.01 dtex, not only is it very difficult to industrially produce yarn, but the fiber dispersibility becomes poor when producing a nonwoven fabric by, for example, a wet papermaking method, resulting in a desired uniform ground. In some cases, a separator having a combination cannot be obtained. On the other hand, when the fineness exceeds 2.0 dtex, the pore diameter is increased, and it is not preferable because a short circuit is likely to occur in terms of durability of the dendrite. .
More specifically, it is preferable to blend both ultrafine fibers having a fineness of 0.05 to 0.1 dtex and ultrafine fibers of 0.5 to 1.0 dtex. For example, a thin nonwoven fabric with a low basis weight is used as a separator. In that case, it is preferable to increase the blending amount of ultrafine fibers of 0.05 to 0.1 dtex to reduce the pore diameter, and the average fiber diameter of the fibers constituting the separator is 1 to 7 μm. Most preferred. The fineness of the unstretched yarn of the thermoplastic polyamide fiber serving as the adhesive component is also preferably within the fineness range described above, and fineness is more advantageous for improving the adhesive strength.

  On the other hand, the fineness of the para-aromatic polyamide fiber is preferably 0.5 to 2.0 dtex, more preferably 1.0 to 1.8 dtex, and further preferably 1.3 to 1.7 dtex. Para aromatic polyamide fibers are mainly blended for the purpose of reinforcing the burrs and edges of the electrode plates, improving the dimensional stability of the separator at high temperatures, and improving the alkali resistance and oxidation resistance of the separator. When the fineness is less than 0.5 dtex, the single fiber strength decreases, and the separator is easily damaged by burrs and edges of the electrode plate. On the other hand, when the fineness exceeds 2.0 dtex, the pore diameter is increased, which is not preferable because a short circuit easily occurs in terms of durability of the dendrite. Therefore, it is stronger to use para-aromatic polyamide fibers with the largest possible fineness within the above fineness range, so the effect of reinforcing the burrs and edges of the electrode plate is greater, while improving the dendrite durability. For the purpose of illustration, it is preferable to adjust by using super fine fibers of thermoplastic polyamide fibers.

  The fiber lengths of the thermoplastic polyamide fiber and para-aromatic polyamide fiber used in the present invention are preferably 3 to 20 mm, more preferably 5 to 15 mm. When the fiber length is less than 3 mm, the tensile strength of the separator is low, and there is a concern that a separator breakage trouble may occur in the battery manufacturing process. When the fiber length exceeds 20 mm, for example, when a nonwoven fabric is produced by a wet papermaking method, the dispersibility of the fiber becomes poor, and a desired separator having a uniform texture cannot be obtained.

  The blending ratio of the thermoplastic polyamide fiber and the para-aromatic polyamide fiber is preferably 95: 5 to 70:30, more preferably 90:10 to 75:25, and still more preferably 85:15 to 80:20. If the blending ratio of the para-aromatic polyamide fiber is less than 5%, it is not preferable because the separator is easily damaged by burrs and edges of the electrode plate, and a short circuit is likely to occur. Further, when the blending ratio of the thermoplastic polyamide fiber is less than 70%, the electrolyte solution retention is disadvantageous, and the blending ratio of the para-aromatic polyamide fiber exceeds 30%, so that the pore diameter becomes large. Moreover, since it becomes very expensive as a separator, it is not preferable in that it cannot be substantially used as a separator for an alkaline battery.

As described above, the alkaline battery separator of the present invention is most preferably substantially composed of drawn and undrawn thermoplastic polyamide fibers, and para-aromatic polyamide fibers. Depending on the automatic group winding construction machine, when the separator has a possibility of breaking without being able to resist its tension, a binder fiber of about several to 30% may be blended for the purpose of improving the tensile strength. . The binder fiber used at this time basically needs to be selected from components that do not significantly reduce the battery performance due to decomposition or the like when the separator is incorporated into the alkaline secondary battery, For example, a single fiber made of an ethylene-vinyl alcohol copolymer or a composite fiber containing an ethylene-vinyl alcohol copolymer as one component is used.
In the present invention, when the ethylene-vinyl alcohol copolymer fiber is used, the blending ratio is preferably 30% or less, more preferably 3 to 20%, and further preferably 5 to 15%. When the blending ratio exceeds 30%, especially in nickel-cadmium batteries and nickel-hydrogen batteries for power tools that require high-rate discharge characteristics, when the battery temperature exceeds 180 ° C, the softening deformation of the separator In some cases, causing problems such as short battery life.
Furthermore, synthetic fiber pulp may be used to reduce the pore diameter for the purpose of improving the dendrite durability. However, in this case as well, basically, when a separator using the synthetic fiber pulp is incorporated into the alkaline secondary battery, the components and the mixing ratio are selected so that the synthetic fiber pulp does not significantly deteriorate the battery performance due to decomposition or the like. There is a need to.

Next, the manufacturing method of the nonwoven fabric which comprises the alkaline battery separator of this invention is demonstrated.
The separator for an alkaline battery of the present invention can be produced by a known method such as a wet papermaking method, a card method, a cross layer method, an airlaid method using the various fibers described above.

However, in the card method and the cross layer method, fibers having a long fiber length can be used, but it is difficult to form a nonwoven fabric having a uniform texture, and a spotted pattern is observed when observed with transmitted light. For this reason, in order to obtain the space | gap diameter required in order to prevent a short circuit, you have to make a high fabric weight.
Furthermore, a method of increasing the separator strength by entanglement three-dimensionally using means such as a needle punch method or a hydroentanglement method may be inferior in dendrite durability resulting from an increase in pore diameter caused by entanglement. The airlaid method can use fibers with a short fiber length and can be made into a non-woven fabric having a uniform texture compared to the card method or the cross-layer method, but especially when the basis weight is low, In some cases, the pore size becomes large and it is difficult to obtain a desired separator.

  On the other hand, the wet papermaking method has an advantage that the production speed is higher than that of the above method, and fibers having different fiber diameters or a plurality of types of fibers can be mixed at an arbitrary ratio in the same apparatus. In other words, the fiber form can be selected from a wide range of staples, pulps, etc., and the usable fiber diameter can be used from ultrafine fibers having a diameter of 5 μm or less to thick fibers. Is obtained.

  Then, as a manufacturing method of the separator for alkaline batteries of this invention, manufacturing with the wet papermaking method is desirable. For example, the above-mentioned thermoplastic polyamide drawn yarn, undrawn yarn, and para-aromatic polyamide fiber are dispersed in water of a pulper to form a slurry. The dispersed slurry is transferred to a chest and the concentration of the dispersed slurry is adjusted to prepare a uniform papermaking slurry. The papermaking slurry is made by using a paper machine having at least one wire selected from a circular net, a long net, a slanted short net, etc., and wetted with a dryer such as a Yankee dryer or an air-through dryer, and then dried. And manufacturing a wet nonwoven fabric.

  Next, in order to improve the electrolyte solution affinity of the wet nonwoven fabric (raw fabric) thus obtained, it is desirable to perform a hydrophilic treatment. Examples of the hydrophilic treatment include corona discharge treatment, atmospheric pressure plasma treatment, fluorination treatment, and surfactant treatment.

  In the corona discharge treatment, an appropriate gap is provided between an electrode connected to a high voltage generator and a metal roll covered with silicon rubber, and a high voltage corona is generated by applying a voltage of several thousand to several tens of thousands of volts at a high frequency. The raw cloth obtained by the above method is run at an appropriate speed during this interval, and the surface of the raw cloth is reacted with ozone generated by corona or nitric oxide to generate carboxyl groups, hydroxyl groups, and peroxide groups. This is a surface modification method for improving the affinity of the electrolytic solution for the raw cloth.

  Atmospheric pressure plasma treatment consists of helium, argon, and oxygen in a plasma reactor having a dielectric-coated electrode in which a solid dielectric such as polyimide, mica, ceramic, or glass is disposed on the surface of at least one of the opposing electrodes. This is a surface modification method that improves the affinity of the electrolyte by introducing a gas composition to be activated, performing plasma excitation under atmospheric pressure, and oxidizing and etching the surface of the raw cloth located between the opposing electrodes .

  Fluorine treatment is performed by bringing a mixed gas of fluorine gas diluted with nitrogen gas or argon gas and one kind of gas such as oxygen gas, carbon dioxide gas, and sulfur dioxide gas into contact with the raw cloth, carboxyl groups on the surface, This is a surface modification method for improving the affinity of an electrolyte by generating a carbonyl group and a hydroxyl group.

  The surfactant treatment is a method of impregnating a raw cloth in a solution of a nonionic surfactant such as polyoxyethylene alkyl ether or polyoxyethylene alkylphenol ether, or applying or spraying this solution, followed by drying. For example, the surface modification method improves the affinity of the electrolyte on the surface of the base fabric.

  Among them, in the present invention, corona discharge treatment can be most suitably used from the viewpoints of affinity with the electrolytic solution, technical ease, treatment speed, and the like.

By using the non-woven fabric obtained by the above production method, a separator for an alkaline battery can be obtained by processing into a desired shape such as a bag-like body or a spiral body. The basis weight of the separator for an alkaline battery of the present invention is not limited, but in order to enable the capacity of the target alkaline secondary battery to be increased, the basis weight is preferably 75 g / m ² or less, 50 g / m ² or less is more preferable. On the other hand, 20 g / m ² or more is preferable from the viewpoint of leak resistance.

  Also, the thickness of the alkaline battery separator is not particularly limited, but the internal resistance can be reduced, the amount of active material can be increased, or the electrode plate length can be increased to increase the capacity of the target alkaline secondary battery. Therefore, the thickness is preferably 200 μm or less, and more preferably 100 μm or less. On the other hand, the thickness is preferably 50 μm or more from the viewpoint of leak resistance.

  The thickness of the separator for an alkaline battery is adjusted by performing a heat calender treatment with a combination of rolls such as rubber-rubber, steel-steel, steel-rubber, cotton-steel, and cotton-cotton. The thermal calendar process may be performed before the hydrophilic treatment or may be performed after the hydrophilic treatment.

  The tensile strength of the alkaline battery separator is preferably 1000 N / m or more, more preferably 1100 to 6000 N / m, and particularly preferably 1200 to 4000 N / m in order to counter the tension of the automatic group winding machine. . If the tensile strength is less than 1000 N / m, the separator can break up without being able to resist the tension of the automatic group winding machine at the time of battery production, and the group winding can be stably configured such that the width becomes narrow and a short circuit occurs. It may disappear.

The pore diameter of the alkaline battery separator is related to the leak resistance and the dendritic resistance characteristics. Leakage resistance and dendritic resistance properties depend on the basis weight and thickness of the separator, and can be used as a separator for alkaline batteries even when the average pore diameter exceeds 30 μm and the maximum pore diameter exceeds 50 μm. Moreover, in order to achieve a low weight per unit area and low thickness in order to achieve a large current discharge, the average pore diameter is preferably 30 μm or less and the maximum pore diameter is preferably 50 μm or less. When the minimum pore diameter exceeds 30 μm, the dendritic resistance properties deteriorate, and when the maximum pore diameter exceeds 50 μm, the process defect rate tends to deteriorate. Further, when the average pore diameter is less than 5 μm, the resistance between the positive electrode and the negative electrode is increased, so that there is a case where high capacity and large current discharge cannot be realized.
On the other hand, the cut-resistant strength is preferably 100 mN · m / g or more, and more preferably 120 to 140 N · m / g. When the cut-resistant strength is less than 100 mN · m / g, the separator is liable to be damaged by burrs and edges of the electrode plate, and a short circuit is likely to occur, which is not preferable.

Further, the alkali resistance and oxidation resistance of the alkaline battery separator greatly affect the cycle life of the battery. While there is a demand for higher capacity and higher output of the battery, the temperature inside the battery due to the charge / discharge cycle tends to increase further, and the deterioration due to the decomposition of the separator in the high temperature alkaline aqueous solution that occurs at that time The liquid retainability and the function as a protective film for dendrite growth of the active material or cadmium are lowered, and this is a factor for accelerating the deterioration of the cycle life.
As an index of alkali resistance and oxidation resistance of the separator for an alkaline battery of the present invention, an aqueous KMnO 4 + KOH solution is used, and the strength retention of the separator after immersion for 1 hour at room temperature (about 23 ° C.) is 80% or more and 1 at 50 ° C. It is preferable that the strength retention of the separator after time immersion is 70% or more, and the strength retention of the separator after immersion for 1 hour at 80 ° C. is 30% or more.
When the strength retention after immersion at 80 ° C. for 1 hour is less than 30%, not only the strength of the separator is lowered, but as a result, the liquid retention of the separator is lowered due to fiber deterioration, and the pore diameter is expanded. The cycle life may be reduced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. In addition, each characteristic value and performance in an Example were measured with the following measuring method.

[Weight per unit g / m ² ]
Measured according to JIS P 8124.

[Thickness μm]
Measurement was performed according to JIS P 8118.

[Tensile strength N / m]
Measured according to JIS P 8113.

[Pore diameter μm]
The maximum pore diameter and the average pore diameter were measured using “Palm Porometer CFP-1100AEXL” manufactured by Porous Materials Inc.

[Alkali resistance, oxidation resistance%]
As evaluation of alkali resistance and oxidation resistance, the strength retention (%) of the separator after the KMnO 4 + KOH mixed aqueous solution treatment was calculated. The strength retention of the separator is a mixture of a 5% KMnO 4 aqueous solution (250 cc) and a 30% KOH aqueous solution (50 cc) with the tensile strength of the untreated separator measured according to JIS P 8113 as F1 (N / m). After immersing in an aqueous solution at room temperature (23 ± 2 ° C.), 50 ± 2 ° C., and 80 ± 2 ° C. for 1 hour, the sample taken out was washed with water and dried until reaching the neutralization point. Using the tensile strength of the separator measured according to P8113 as F2 (N / m), the strength retention (%) after the KMnO4 + KOH aqueous solution treatment was obtained by the following formula, and used as an index of alkali resistance and oxidation resistance.
Strength retention (%) = (F2 / F1) × 100

[Cutting strength mN · m ² / g]
Using a “Handy Compression Tester KES-G5” manufactured by Kato Tech, attach a stainless steel jig (width 8 mm flat blade) to the separator sample at a speed of 0.2 mm / sec. The force required for the measurement was measured and defined as the cut-resistant strength.

[Liquid retention g / g]
A separator sample of 50 mm × 50 mm was immersed in a 35% KOH aqueous solution for 30 minutes under the condition of a bath ratio of 1/100, and the separator sample mass was measured after the natural liquid was drained for 30 seconds after the immersion, and 35 retained in the separator. The liquid retention amount was calculated by dividing the mass of the% KOH aqueous solution by the original separator sample mass.

[Liquid absorption speed sec]
The edge part of the separator sample was immersed in 35% KOH aqueous solution, and the time required for the 35% KOH aqueous solution to be sucked up to a height of 25 mm was measured.

[Penetration strength mN · m ² / g]
Using a “Handy Compression Tester KES-G5” manufactured by Kato Tech Co., Ltd., a stainless steel jig (needle with a 1 mm diameter ball attached to the tip) is attached to this, and perpendicular to the separator sample at a speed of 0.2 mm / sec. The force required for piercing and penetrating was measured to determine penetration strength.

・ Manufacture of thermoplastic polyamide fiber [Thermoplastic polyamide fiber A]
A polyamide having a dicarboxylic acid component of 100 mol% terephthalic acid, a diamine component of 50 mol% of 1,9-nonanediamine, and 50 mol% of 2-methyl-1,8-octanediamine was synthesized (ultimate viscosity 0.73 dl / g, End-capping rate of 91%), drawn yarn of thermoplastic polyamide fiber with a fineness of 0.7 dtex (thermoplastic polyamide fiber A)
Got.

[Thermoplastic polyamide fiber B]
Using the same thermoplastic polyamide as the thermoplastic polyamide fiber A, an unstretched thermoplastic polyamide fiber (thermoplastic polyamide fiber B) having a fineness of 1.6 dtex was obtained.

[Thermoplastic polyamide fiber C]
The sea-island fiber (sea-island ratio = 45/55) which uses the same thermoplastic polyamide as the thermoplastic polyamide fiber A as an island component and the sea component as an easily alkali-reducible polyester copolymerized with 2.5 mol% of 5-sodium sulfoisophthalic acid. , 16 islands) were subjected to alkali weight reduction to completely remove sea components, and a drawn thermoplastic polyamide fiber (thermoplastic polyamide fiber C) having a fineness of 0.08 dtex was obtained.

Thermoplastic polyamide fiber A (fiber length 10 mm) 40 mass%, thermoplastic polyamide fiber B (fiber length 10 mm) 40 mass%, and para-aromatic polyamide fiber (manufactured by Toray DuPont, “Kevlar 49”, fineness 1. (5 dtex, fiber length 6 mm) 20% by mass were mixed together, disaggregated in pulper water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 66.6 g / m ² . A separator for an alkaline battery having a thickness of 164 μm was obtained.

Thermoplastic polyamide fiber B (fiber length 10 mm) 40 mass%, thermoplastic polyamide fiber C (3 mm) 55 mass%, and para-aromatic polyamide fiber (manufactured by Toray DuPont, “Kevlar 49”, fineness 1.5 dtex, Fiber length 6 mm) 5% by mass was mixed together and disaggregated in pulper water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 64.9 g / m ² . A separator for an alkaline battery having a thickness of 162 μm was obtained.

Thermoplastic polyamide fiber A (fiber length 10 mm) 10 mass%, Thermoplastic polyamide fiber B (fiber length 5 mm) 20 mass%, Thermoplastic polyamide fiber C (fiber length 3 mm) 40 mass%, Para-type aromatic polyamide fiber (Toray -DuPont, "Kevlar 49", fineness 1.5 dtex, fiber length 6 mm) 20% by mass, ethylene content 44 mol%, saponification degree 99.6%, fineness 0.08 detex, fiber length 3 mm ethylene 10% by mass of vinyl alcohol copolymer fibers were mixed together, disaggregated in pulper water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 35.9 g / m ² . A separator for an alkaline battery having a thickness of 85 μm was obtained.

Thermoplastic polyamide fiber A (fiber length 10 mm) 10 mass%, Thermoplastic polyamide fiber B (fiber length 10 mm) 20 mass%, Nylon 6 / Nylon 66 sheath-core composite fiber (fineness 2.2 dtex, fiber length 5 mm) 20 mass %, Thermoplastic polyamide fiber C (fiber length 3 mm) 30% by mass, para aromatic polyamide fiber (Toray Dupont, “Kevlar 49”, fineness 1.5 dtex, fiber length 6 mm) 20% by mass mixed together Then, the pulp was disaggregated in water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 67.2 g / m ² . A separator for an alkaline battery having a thickness of 166 μm was obtained.

Thermoplastic polyamide fiber A (fiber length 10 mm) 30% by mass, thermoplastic polyamide fiber C (3 mm) 15% by mass, para-aromatic polyamide fiber (manufactured by Toray DuPont, “Kevlar 49”, fineness 1.5 dtex, fiber 6 mm in length) 25% by mass, 20% by mass of Kevlar pulp (beaten with a disc refiner), ethylene content of 44 mol%, saponification degree 99.6%, fineness 0.08 dtex, fiber length 3 mm Alcohol copolymer fibers (10% by mass) were mixed together, disaggregated in pulper water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 150 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high baron 3.2 mm, and the basis weight was 63.2 g / m ² . A separator for an alkaline battery having a thickness of 155 μm was obtained.

[Comparative Example 1]
A dry nonwoven fabric made of nylon 6 and nylon 66 (manufactured by Japan Vilene Co., Ltd., card type, basis weight 63.5 g / m ² , thickness 150 μm) was used as a separator for an alkaline battery.

[Comparative Example 2]
Crystalline polypropylene fiber (manufactured by Yamatobo, “PZ”, fineness 0.8 dtex, fiber length 10 mm) 70% by mass, polyethylene / polypropylene sheath-core composite fiber (manufactured by Yamatobo, “NBF-H”, fineness 1. (7 dtex, fiber length 5 mm) 30% by mass were mixed together and disaggregated in pulper water, and a uniform papermaking slurry was prepared under gentle stirring of the chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high baron 3.2 mm, and the basis weight was 66.9 g / m ² . A separator for an alkaline battery having a thickness of 161 μm was obtained.

[Comparative Example 3]
60% by mass of thermoplastic polyamide fiber A (fiber length 5 mm) and 40% by mass of thermoplastic polyamide fiber B (fiber length 5 mm) are mixed together, disaggregated in the water of the pulper, under gentle stirring of the chest, A uniform papermaking slurry was prepared. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calendar process was performed at a roll temperature of 220 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 65.3 g / m ² . A separator for an alkaline battery having a thickness of 160 μm was obtained.

[Comparative Example 4]
Thermoplastic polyamide fiber A (fiber length 5 mm) 70 mass%, ethylene content 44 mol%, saponification degree 99.6%, fineness 0.6 dtex, fiber length 5 mm ethylene-vinyl alcohol copolymer fiber 30 mass% Were mixed together, disaggregated in water of a pulper, and a uniform papermaking slurry was prepared under gentle stirring of a chest. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a calender treatment was performed at a roll temperature of 150 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high ballon 3.2 mm, and the basis weight was 65.1 g / m ² . A separator for an alkaline battery having a thickness of 160 μm was obtained.

[Comparative Example 5]
Nylon 66 fiber (fineness 0.5 dtex, fiber length 10 mm) 10 mass%, nylon 6 / nylon 66 sheath-core composite fiber (fineness 2.2 dtex, fiber length 10 mm) 50 mass%, and para-type aromatic polyamide fiber (Toray・ Made by DuPont, "Kevlar 49", fineness 1.5dtex, fiber length 6mm) 40% by mass together, disaggregated in pulper water, and uniform slurry for paper making under gentle stirring of chest Prepared. This papermaking slurry was made using a wet papermaking method with a slanted short paper machine and then dried with a Yankee dryer to produce a wet nonwoven fabric. Next, a thermal calendar treatment was performed at a roll temperature of 200 ° C., and finally, a corona treatment was performed on both surfaces of the nonwoven fabric using an electrode 20 mm wide × 600 mm and a dielectric high baron 3.2 mm, and the basis weight was 66.6 g / m 2. A separator for an alkaline battery having a thickness of 162 μm was obtained.

  Table 1 shows the results obtained in the above Examples and Comparative Examples.

Evaluation;
Examples 1 to 5 use thermoplastic polyamide fibers excellent in alkali resistance and oxidation resistance as constituent fibers, and further use para-aromatic polyamide fibers excellent in cut resistance, so that alkali resistance and oxidation resistance are used. It can be seen that the separator for alkaline batteries is excellent in physical properties typified by cut resistance. In particular, in Examples 2 to 5, since ultra-fine fibers of thermoplastic polyamide fibers are blended, it can be seen that the pore diameter is small and the dendrite durability is excellent. Moreover, in Example 3 and Example 5, since the ultra-fine fiber of ethylene-vinyl alcohol copolymer is mix | blended as a binder fiber, tensile strength is high, and the tension | tensile_strength is carried out with the automatic group winding composition machine at the time of battery manufacture. Even if it is high, it has sufficient tensile strength to counter this. In Example 4, a composite fiber made of nylon 6 / nylon 66 is used as a part of the binder fiber, but an unstretched yarn of thermoplastic polyamide fiber and an ultrafine fiber of ethylene-vinyl alcohol copolymer were blended. Therefore, it can be seen that the strength of the separator is maintained even after the KMnO 4 + KOH mixed aqueous solution treatment at 80 ° C.
Comparative Example 1 is a separator made of an aliphatic polyamide fiber, but is a dry nonwoven fabric, so has a large pore diameter, and is inferior to the separator obtained in the examples in terms of alkali resistance and oxidation resistance.
Comparative Example 2 is a separator made of polyolefin fibers, but is excellent in alkali resistance but inferior to the separator obtained in the examples in terms of liquid retention and liquid absorption speed.
Comparative Example 3 and Comparative Example 4 are alkaline battery separators having a composition that does not include para-aromatic polyamide fibers. It can be seen that the separator has low cut strength compared to, for example, Example 1.
Comparative Example 5 is an alkaline battery separator in which para-aromatic polyamide fibers are blended with nylon 6 and nylon 66 fibers. The separator has a low strength retention after treatment with a KMnO 4 + KOH mixed aqueous solution, and has alkali resistance, It turns out that it is inferior to oxidation resistance.

Claims (5)

Composite yarn comprising thermoplastic polyamide fiber drawn yarn, para-aromatic polyamide fiber , thermoplastic polyamide fiber undrawn yarn, ethylene-vinyl alcohol copolymer fiber and ethylene-vinyl alcohol copolymer as one component A separator for an alkaline battery comprising a nonwoven fabric containing at least one binder fiber selected from the group consisting of fibers , wherein the thermoplastic polyamide fiber is a dicarboxylic acid in which 60 mol% or more of the dicarboxylic acid component is an aromatic carboxylic acid component An alkaline battery separator comprising an acid component and a diamine component in which 60 mol% or more of the diamine component is an aliphatic alkylenediamine having 6 to 12 carbon atoms. 2. The alkaline battery separator according to claim 1, wherein the thermoplastic polyamide comprises a dicarboxylic acid component comprising a terephthalic acid component, and the diamine component comprises a 1,9-nonanediamine component and a 2-methyl-1,8-octanediamine component. The fineness of the thermoplastic polyamide fiber is 0.01 to 2.0 dtex, the fiber length is 3 to 20 mm, the fineness of the para-aromatic polyamide fiber is 0.5 to 2.0 dtex, and the fiber length is 3 to 20 mm. The alkaline battery separator according to claim 1 or 2 , wherein a blending ratio of the thermoplastic polyamide fiber and the para-aromatic polyamide fiber is 9 5 : 5 to 70:30. The nonwoven fabric has a basis weight of 20 to 75 g / m ² , a thickness of 50 to 200 μm, a tensile strength of 1000 N / m or more, an average pore diameter of 5 to 30 μm, a maximum pore diameter of 50 μm or less, and a cut resistance of 100 mN · m ² / It is g or more, The separator for alkaline batteries of any one of Claims 1-3. An alkaline battery comprising the alkaline battery separator according to claim 1 incorporated therein.