JP3366412B2 - Alkaline battery separator - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alkaline battery separator.

[0002]

2. Description of the Related Art Conventionally, a separator has been used to separate a positive electrode and a negative electrode of an alkaline battery to prevent a short circuit and to hold an electrolytic solution to smoothly carry out an electromotive reaction.

For example, in JP-A-3-257755, in a cross section of a fiber composed of a polyolefin polymer component and an ethylene-vinyl alcohol copolymer component, one component is interposed between the other components and two or more are provided. Disclosed is a separator made of a non-woven fabric of ultrafine fibers obtained by dividing each of the components into splittable conjugate fibers that are divided into parts, and some of these components are exposed on the fiber surface. This separator is excellent in alkali resistance due to the polyolefin polymer component and liquid retention due to the ethylene-vinyl alcohol copolymer component.

However, the ethylene-vinyl alcohol copolymer component of this separator is dissolved in the electrolytic solution, and when it is used in a secondary battery, it is easily decomposed by the gas generated from the electrode, so that a short circuit occurs, Therefore, there is a problem in that the electromotive reaction cannot be smoothly carried out for a long period of time because the liquid retaining property cannot be obtained. In particular,
When this separator is used as a separator for a secondary battery, the separator is compressed by the expansion of the electrode plate at each charge and discharge, and the liquid retaining property is likely to decrease, so that a smooth electromotive reaction cannot be performed. Met.

On the other hand, a separator using a polyolefin fiber has excellent alkali resistance, but since the electrolyte retainability is poor, a separator in which a surfactant or the like is used to enhance the retainability is also known. Although this separator is initially obtained to a certain degree of hydrophilicity, long-term liquid retention, especially when this separator is used as a separator for a secondary battery, as described above. However, when the separator is compressed, the liquid retaining property is deteriorated, and the electromotive reaction cannot be smoothly performed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the object of the present invention is to prevent short-circuits from occurring, to provide excellent liquid retention, and to provide smooth operation over a long period of time. Another object of the present invention is to provide an alkaline battery separator capable of carrying out an electromotive reaction.

[0007]

The alkaline battery separator of the present invention (hereinafter sometimes simply referred to as "separator") comprises a polyolefin fiber mainly composed of ultrafine fibers obtained by dividing the polyolefin dividable composite fiber. It is a separator for alkaline batteries that consists only of water-entangled nonwoven fabric
Yes, the hydroentangled nonwoven fabric is hydrophilized.

When the hydroentangled non-woven fabric is adhered with a mixed low melting point polyolefin adhesive fiber, it is excellent in strength and is a preferable separator in production.

Furthermore, a separator hydrophilized by graft-polymerizing a vinyl monomer onto a hydro-entangled nonwoven fabric has more excellent liquid retention and fiber strength. Previous
Hydro-entangled nonwoven fabric is made of polyethylene fiber, polypropylene
Fiber, polyethylene, polypropylene, ethylene
-Propylene copolymer, ethylene-butene-propylene
Core-sheath type, side by side
Alternating layers, with dough, eccentric, and chrysanthemum fiber cross sections
Splittable or non-splittable composites with laminated fiber cross-sections
Fiber made of polyolefin fiber selected from among fibers
It is obtained by hydroentangling the web.
be able to. The ultrafine fibers are separated by hydroentangling treatment.
The splittable conjugate fiber may be obtained by splitting.
The fineness of the ultrafine fibers is 0.01 to 0.4 denier.
be able to. The splittable conjugate fiber is polyethylene resin.
Component and polypropylene resin component are preferred.
Good The low melting point polyolefin adhesive fiber is
Part containing ropylene resin component and polyethylene resin component
It is preferably composed of fusion type composite fibers. The water flow entanglement
Hydro-entry of a woven fabric to a fibrous web formed by the wet method
It is preferably obtained by a combination treatment. Hydrophilization
Sulfonation with fuming sulfuric acid or fluorine gas treatment
Can be

[0010]

Since the separator of the present invention is made of polyolefin fiber, it is excellent in electrolytic solution resistance and oxidation resistance and does not decompose to cause a short circuit. Moreover, since this polyolefin-based fiber is mainly composed of ultrafine fibers obtained by splitting the splittable conjugate fiber, the surface area is larger than the surface area of the splittable conjugate fiber, the distance between the entanglement points of the fiber is short, and the voids of the nonwoven fabric are minute, Capillary effect works. Therefore, the separator obtained by hydrophilizing the non-woven fabric composed mainly of the ultrafine fibers has an excellent liquid retaining property for a long period of time. Furthermore, since the separator is formed by the hydroentangling method, and the orientation direction of the fibers is substantially the thickness direction, when used as a separator for a secondary battery, it is particularly resistant to compression of the electrode plate. It is possible to maintain the liquid holding property, and it is possible to use it stably for a long period of time.

The method for manufacturing the separator of the present invention will be described below.

The fibers that can be used in the separator of the present invention must be polyolefin fibers that have resistance to electrolytic solution and oxidation. As the polyolefin fiber, for example, a fiber made of a single component such as polyethylene fiber or polypropylene fiber, polyethylene, polypropylene,
Ethylene-propylene copolymer, ethylene-butene-
Proper combination of resins such as propylene copolymer,
Core-sheath type, side-by-side type, eccentric type, or Fig. 1
(A) to (d), which has a chrysanthemum-shaped fiber cross section in which one component 1 is arranged between the other components 2, and FIG.
There is a splittable or non-splittable conjugate fiber having a fiber cross section in which one component 1 and the other component 2 are alternately laminated in layers as shown in FIG. In addition, among these polyolefin fibers, when the splittable conjugate fiber is mainly used, it can be split and entangled at the same time as the hydroentangling treatment, which is not only preferable in production, but also the obtained ultrafine fiber has a large surface area and thus is electrolyzed. The affinity for the liquid works, and the distance between the entanglement points of the fibers is short, and the voids are minute and dense, so the capillary effect occurs, the liquid retention is excellent for a long period of time, and the short circuit due to the dendrite is physically generated. Since it can be prevented, the separator can be used for a long time also in this respect.

The finer the ultrafine fibers obtained by dividing the splittable conjugate fiber, the more easily the capillary effect is produced and the dendrite can be physically prevented, but if it is too thin, it has no strength. Since it serves as a separator, the fineness of the ultrafine fibers is preferably 0.01 to 0.4 denier.

Among the splittable conjugate fibers, the fiber containing the polyethylene resin component and the polypropylene resin component has not only excellent electrolytic solution resistance but also the polyethylene resin component and the polypropylene resin component. Then, the degree of difficulty of hydrophilization by sulfonation, fluorine treatment, etc. is different. That is, the polyethylene resin component is relatively easily hydrophilized, whereas the polypropylene resin component is not easily hydrophilized. Therefore, the electrolyte solution is easily retained on the polyethylene resin component side, and the electrolyte solution is scarce on the polypropylene resin component side, and even if gas is generated in the sealed secondary battery, it quickly permeates to the other electrode. Since there is no danger that the internal pressure rises and the product bursts, it can be used favorably.

In the present invention, since the liquid retention is improved by mainly using the ultrafine fibers obtained from the splittable conjugate fiber, it is preferable to use 50% by weight or more of the splittable conjugate fiber, more preferably. Is 70% by weight or more, and most preferably 100% by weight.

In order to further improve the handleability of the non-woven fabric, it is possible to improve the dimensional stability by including a low melting point polyolefin adhesive fiber in an amount of 50% by weight or less. If the low melting point polyolefin-based adhesive fiber is 50% by weight or less, the problem of deterioration in liquid retention due to a decrease in the amount of ultrafine fibers does not occur, but more preferably 30% by weight.
It is the following. Examples of the low-melting-point polyolefin-based adhesive fibers include all-melt type polyethylene fibers and polypropylene fibers similar to those described above, and partially-melt type core-sheath type, side-by-side type, and eccentric type composite fibers. Also, if these adhesive fibers have a resin component that adheres at a temperature lower than the melting point of any resin component of other fibers (mostly ultrafine fibers) that make up the nonwoven fabric, the liquid retention property of the ultrafine fibers Will not hurt. In addition, it is also possible to use an ultrafine fiber obtained from the splittable conjugate fiber as an adhesive fiber.

Among these low melting point polyolefin-based adhesive fibers, partially melt-type composite fibers can be preferably used because the strength of the adhesive fibers is maintained by the resin component which is not melted. Furthermore, among the partially melted composite fibers, the fiber containing the polypropylene resin component and the polyethylene resin component is similar to the splittable composite fiber, even when gas is generated in the sealed secondary battery, Since it can be quickly permeated to the other electrode and there is no danger of bursting due to an increase in internal pressure, it can be suitably used.

The fineness and fiber length of the above-mentioned splittable composite fibers and low melting point polyolefin adhesive fibers are not particularly limited, but the fineness is 0.5 to 9 denier and the fiber length is 5
Those having a thickness of up to 60 mm can be preferably used.

The fiber web is formed from the fibers as described above. Examples of the method for forming the fiber web include a dry method and a wet method such as a card method and an air lay method.
Among these, the wet method can form a dense fiber web and can physically prevent dendrites, and thus can be preferably used.

When the fiber web is formed by the card method, the fibers may be oriented in one direction, or the fibers may be oriented so as to intersect with each other by a cross layer, or they may be laminated. Among these,
A fiber web including a fiber web oriented so that the fibers intersect with each other is characterized by being excellent in strength because the fibers are easily entangled with each other in the subsequent hydroentanglement treatment.

Further, when a fiber web layer consisting only of low melting point polyolefin adhesive fibers is formed and bonded, the bonding surface becomes a film and the liquid retaining property is poor, so low melting point polyolefin adhesive fibers are also used. In this case, it is preferable to mix with the splittable conjugate fiber.

The fiber web thus obtained is subjected to hydroentangling treatment. By this hydroentangling treatment, the orientation direction of the fibers becomes substantially the thickness direction of the non-woven fabric, so that it is possible to withstand the pressure applied between the electrode plates when assembling the battery, as well as the secondary It is possible to withstand the pressure when the electrode plate expands like a battery, and the separator has excellent liquid retention. Further, the separator of the present invention is mainly composed of splittable conjugate fiber entangled fibers, because the ultrafine fibers obtained by splitting are closely entangled, not only excellent in strength, but also thin, Since the active material can be filled in the battery in an amount corresponding to the reduced thickness, the battery also has a feature that the capacity can be increased. Furthermore, when the hydroentangling treatment is performed, not only the fibers are entangled but also the oil agent adhering to the fibers can be washed, so that not only the adverse effect of the oil agent on the battery performance can be eliminated, but also the hydrophilic treatment described below is performed. It is possible to obtain a separator that can be efficiently and stably carried out and has excellent liquid retention properties for a long period of time.

As the hydroentangling treatment having such an excellent effect, for example, a nozzle plate having nozzle diameters of 0.05 to 0.3 mm and a pitch of 0.2 to 3 mm arranged in a row, or two or more rows of nozzles are used. Using the nozzle plate arranged in the above, the treatment is performed with a water flow having a water pressure of 10 to 300 kg / cm ² . Such a hydroentangling treatment need not be performed once, and if necessary, 2
It can be processed more than once. Further, the water flow treated surface does not have to be only one side of the fiber web, and both sides may be treated.

In the hydroentangling treatment, if the support, such as a net or a mesh on which the fiber web is placed, has large holes, the resulting separator also has large holes, and a short circuit easily occurs. Therefore, it is more preferable to use a fine plain weave net of 50 mesh or more or a perforated plate having a hole distance of 0.4 mm or less.

When the hydroentangled non-woven fabric contains adhesive fibers, dimensional stability can be further improved by hydroentangling and then performing heat treatment or the like and adhering with the adhesive fibers. .

The hydroentangled nonwoven fabric thus obtained becomes the separator of the present invention by subjecting it to hydrophilic treatment. This hydrophilization treatment includes, for example, sulfonation treatment, fluorine treatment, or graft polymerization of vinyl monomers. Since these hydrophilization treatments can impart permanent hydrophilicity, they retain liquid retention properties for a long period of time. It becomes an excellent separator.

The sulfonation treatment is not particularly limited, and for example, it may be treated with fuming sulfuric acid, sulfuric acid, chromic acid, nitric acid or the like. Among them, the sulfonation treatment with fuming sulfuric acid has high reactivity and can be sulfonated relatively easily, and thus can be preferably used.

The fluorine gas treatment is also not particularly limited, and for example, a fluorine gas diluted with an inert gas to which oxygen gas, carbon dioxide gas, sulfur dioxide gas or the like is added and mixed may be used. In addition, after previously adhering the sulfur dioxide gas to the hydroentangled nonwoven fabric,
The method of contacting with fluorine gas is a more efficient and permanent hydrophilization treatment method.

As the graft polymerization of vinyl monomer,
As the vinyl monomer, for example, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinylpyridine, vinylpyrrolidone, or styrene can be used. When styrene is graft-polymerized, it is sulfonated in order to have an affinity with the electrolytic solution. Among these, acrylic acid can be preferably used because it has excellent affinity with the electrolytic solution.

These vinyl monomers can be polymerized by, for example, immersing the hydroentangled non-woven fabric in a solution containing the vinyl monomer and a polymerization initiator and heating it, or applying the vinyl monomer to the hydroentangled non-woven fabric and then irradiating it with radiation. There is a method of irradiating the hydroentangled nonwoven fabric with radiation and then contacting it with a vinyl monomer, a method of impregnating the hydroentangled nonwoven fabric with a vinyl monomer solution containing a sensitizer, and then irradiating it with ultraviolet rays. Before contacting the vinyl monomer solution with the hydroentangled nonwoven fabric, treating the hydroentangled nonwoven fabric surface with ultraviolet irradiation, corona discharge, plasma discharge, or the like is effective because it has a high affinity with the vinyl monomer solution. It has the feature that it can be graft polymerized.

The hydroentangled nonwoven fabric graft-polymerized with a vinyl monomer can be treated under milder conditions as compared with sulfonation and the like, so that the fiber strength is less deteriorated by the graft polymerization and the strength is excellent. Is.

Since the separator of the present invention is excellent in electrolytic solution resistance and oxidation resistance, does not cause a short circuit, and is excellent in liquid retention, the electromotive reaction is smoothly performed for a long period of time. It is possible. This separator is, for example,
Suitable for primary batteries such as alkaline manganese battery, mercury battery, silver oxide battery, air battery, nickel-cadmium battery, silver-zinc battery, silver-cadmium battery, nickel-zinc battery, nickel-hydrogen battery, etc. It can be used.

Examples of the separator of the present invention will be described below, but the present invention is not limited to these examples.

[0034]

【Example】

(Example 1) As fibers, polypropylene component (symbol 2 in the figure, circular polypropylene component: 0.04 denier, petal-shaped polypropylene component: 0.12 denier) and polyethylene as shown in Fig. 1 (c). A 100% separable composite fiber having a chrysanthemum-like cross-sectional shape and a fineness of 2 denier and a fiber length of 38 mm, which is composed of the components (symbol 1, 0.12 denier in the figure), is opened by a card machine, and the basis weight is 13 g / m. ^Two unidirectional fiber webs and a fiber web having a basis weight of 52 g / m ² in which fibers were crossed by a cross layer were laminated. The laminated fiber web was placed on a 80 mesh plain weave on the net, nozzle diameter 0.13 mm, using a nozzle plate of pitch 0.6 mm, with water flow pressure 130 kg / cm ^2, was treated at a time twice from both sides, A hydroentangled nonwoven fabric was obtained.

Next, this hydroentangled non-woven fabric was used in an amount of 15% by weight.
It was immersed in fuming sulfuric acid for 2 minutes to be sulfonated. afterwards,
Calendered at a linear pressure of 80 kg / cm to give a basis weight of 65 g / m ² ,
A separator having a thickness of 0.15 mm was obtained.

(Example 2) Same as in Example 1, 80% by weight of splittable composite fibers having a fineness of 2 denier and a fiber length of 38 mm, and a polypropylene having a fineness of 2 denier and a fiber length of 51 mm (core component) -low density polyethylene (sheath) Ingredient) Composite adhesive fiber 20
65 g / m 2 basis weight in the same manner as in Example 1, except that the low-density polyethylene component was fused by heat treatment at 110 ° C. after obtaining a hydroentangled nonwoven fabric. ^2. A sulfonated separator having a thickness of 0.15 mm was obtained.

(Example 3) Two 110 watt low-pressure mercury lamps were used as pretreatments on both sides of the hydroentangled nonwoven fabric obtained in the same manner as in Example 1 to obtain 184.9 nm and 25 nm.
Low-wavelength ultraviolet light around 3.7 nm is 1 from a distance of 5 cm.
Irradiated for minutes. Next, this hydro-entangled nonwoven fabric was impregnated with an acrylic acid monomer aqueous solution having the following composition, and two 110-watt low-pressure mercury lamps were used on both sides of the hydro-entangled nonwoven fabric under deoxidizing conditions. , 184.9 nm and 253.7 nm near low wavelength ultraviolet rays were irradiated for 1 minute from a distance of 5 cm to graft-polymerize 10% by weight of acrylic acid. The hydroentangled nonwoven fabric hydrophilized by the graft polymerization was calendered at a linear pressure of 80 kg / cm to obtain a separator having a basis weight of 72 g / m ² and a thickness of 0.15 mm. Note (blending of acrylic acid monomer aqueous solution, wt%) Acrylic acid monomer ・ ・ ・ 20.0 Water ・ ・ ・ 64.5 Benzophenone ・ ・ ・ 0.5 Methoxyethanol ・ ・ ・ 14.5 Nonionic surfactant ・ ・・ 0.5

Example 4 A heat-treated hydroentangled nonwoven fabric obtained in the same manner as in Example 2 (untreated with sulfonation)
In the same manner as in Example 3, an acrylic acid monomer was graft-polymerized to obtain a separator having a basis weight of 72 g / m ² and a thickness of 0.15 mm.

(Example 5) Fineness 2 denier, fiber length 10
80% by weight of the same splittable conjugate fiber as in Example 1 and a fineness of 2 denier and a fiber length of 15 mm of polypropylene (core component) -low density polyethylene (sheath component) composite adhesive fiber 20 mm
The slurry, which is mixed with and dispersed by weight, is made into paper by a wet papermaking method and then placed on an 80 mesh plain weave net.
Using a nozzle plate having a nozzle diameter of 0.13 mm and a pitch of 0.6 mm, a hydroentangled nonwoven fabric having a basis weight of 65 g / m ² was obtained by treating the surface twice with a water flow having a water pressure of 80 kg / cm ² . afterwards,
The hydroentangled nonwoven fabric was polymerized and calendered with acrylic acid in the same manner as in Example 3 to obtain a separator having a basis weight of 72 g / m ² and a thickness of 0.15 mm.

COMPARATIVE EXAMPLE 1 Polypropylene (core component) -polyethylene (sheath component) composite adhesive fiber having a fineness of 1.5 denier and a fiber length of 51 mm (25% by weight) and a polypropylene having a fineness of 0.9 denier and a fiber length of 38 mm (core) Component) -polyethylene (sheath component) composite adhesive fiber 75% by weight was mixed, and heat treatment was performed at 135 ° C. after the hydroentangled nonwoven fabric was obtained to fuse only the polyethylene component. Same as Example 1, 65 g / m ² basis weight, 0.15 m thickness
A m-sulfonated separator was obtained.

Comparative Example 2 Polypropylene component (symbol 2 in the figure, circular polypropylene component: 0.04 denier, petal-shaped polypropylene component: 0.12 denier) and ethylene as shown in FIG. 1 (c). 100% of splittable conjugate fibers having a chrysanthemum-shaped cross-sectional shape, a fineness of 2 denier, and a fiber length of 38 mm, which is composed of a vinyl alcohol copolymer component (symbol 1, 0.12 denier in the figure),
And Example 1 except that the sulfonation treatment was not performed.
A separator having a basis weight of 65 g / m ² and a thickness of 0.15 mm was obtained in the same manner as in.

Comparative Example 3 Only polypropylene (core component) -polyethylene (sheath component) having a fineness of 1.5 denier and a fiber length of 51 mm was used, and a hydroentangled nonwoven fabric was heat treated at 135 ° C. Then, the heat-treated hydroentangled nonwoven fabric having a basis weight of 65 g / m ² obtained in the same manner as in Example 1 except that only the polyethylene component was fused, was grafted with an acrylic acid monomer in the same manner as in Example 3. Polymerized,
A separator having a basis weight of 72 g / m ² and a thickness of 0.15 mm was obtained.

(Measurement of liquid retention under pressure) The separators of Examples 1 to 5 and Comparative Examples 1 to 3 cut into a diameter of 30 mm were prepared.
The weight (W ₀ ) was measured after reaching the water equilibrium under the condition of the temperature of 20 ° C. and the relative humidity of 65%. Next, the potassium hydroxide solution was retained by immersing it in a potassium hydroxide solution having a specific gravity of 1.3 (20 ° C.) for 1 hour so that the air in the separator was replaced with the potassium hydroxide solution. Next, this separator was sandwiched between upper and lower three filter papers (diameter 30 mm), a pressure of 58 kg / cm ² was applied for 30 seconds by a pressure pump, and then the weight (W ₁ ) of the separator was measured. And
The liquid retention under pressure was determined by the following formula. In addition, this measurement was performed 4 times with respect to one separator, and the average was made into the pressurized liquid retention rate. Also, for the separators of Examples 1 to 5 and Comparative Examples 1 to 3 after the end of the oxidation resistance test described below,
Similarly, the pressurized liquid retention rate was determined. The results are shown in Table 1.

[0044]

[Table 1]

(Measurement of 5% modulus strength) JIS L
According to 1096 (general woven fabric test method), the separators of Examples 1 to 5 and Comparative Examples 1 to 3 cut into 5 × 20 cm were separated by a chuck distance of 10 cm and a tensile speed of 300 mm / min.
With a tensile strength and elongation measuring machine (manufactured by Orientec Co., Ltd.),
The modulus strength at 5% elongation was measured. In addition, this measurement was performed 5 times with respect to one separator, and the average was taken as 5% modulus. The results are also shown in Table 1.

(Oxidation resistance test) The three separators of Examples 1 to 5 and Comparative Examples 1 to 3 cut into 5 × 5 cm were allowed to stand for 24 hours at a temperature of 20 ° C. and a relative humidity of 65%.
The weight (W ₂ ) of the three separators was measured. Next, this separator is treated with a 5% potassium permanganate aqueous solution 25
It was immersed in a mixed solution of 0 cc and 30 cc of an aqueous potassium hydroxide solution having a specific gravity of 1.3, boiled for 1 hour, and then thoroughly washed with water. Then, the separator is immersed in a dilute oxalic acid solution,
Manganese dioxide was dissolved and removed, washed thoroughly with water, and dried. After that, the temperature is kept at 20 ℃ and the relative humidity is 65%.
After standing for a period of time, the weight (W ₃ ) was measured, the weight change rate was calculated by the following formula, and the oxidation resistance was judged based on this. The results are also shown in Table 1.

[0047]

(Wettability Test) Examples 1 to 5 and Comparative Example 1
After cutting the separator of 3 to 2 × 180 cm, the separator is treated with an aqueous solution of potassium hydroxide having a specific gravity of 1.3 to 0.5.
Only the cm was soaked, and the liquid absorption height after 30 minutes was measured. The results are also shown in Table 1.

(Measurement of Average Pore Size) The average pore size of the separators of Examples 1 to 5 and Comparative Examples 1 to 3 was measured with a pore size distribution measuring device (manufactured by Coulter Electronics Co.). The results are also shown in Table 1.

[0050]

The alkaline battery separator of the present invention comprises:
Mainly comprising microfine fibers, dividable composite fibers comprising only polyolefin resin component is divided and entangled, Al consisting of only water-entangled nonwoven fabric made of polyolefin fibers
It is a separator for potassium battery, and since the hydroentangled nonwoven fabric is subjected to a hydrophilization treatment, it has excellent electrolytic solution resistance and oxidation resistance, does not cause a short circuit, and has excellent liquid retention. Therefore, the electromotive reaction can be smoothly performed over a long period of time.

In addition, of other fibers constituting the separator,
Having a resin component that can be adhered at a temperature lower than the melting point of any of the resin component, the low melting polyolefin adhesive fibers
When they are mixed and adhered, they are excellent in dimensional stability and tensile strength, and therefore they are preferable separators in production.

When the polyolefin fiber constituting the separator is a composite fiber containing a polypropylene component and a polyethylene component, it is excellent in gas permeability and therefore can be suitably used as a separator for a secondary battery. It is possible.

Further, a separator hydrophilized by graft polymerization of a vinyl monomer is more excellent in liquid retention and does not deteriorate fiber strength.

[Brief description of drawings]

FIG. 1 (a) is a schematic sectional view of a splittable conjugate fiber of the present invention (b) is a schematic sectional view of another splittable conjugate fiber of the present invention (c) is another splittable conjugate fiber of the present invention (D) A schematic cross-sectional view of another splittable conjugate fiber of the present invention (e) A schematic cross-sectional view of another splittable conjugate fiber of the present invention

[Explanation of symbols] 1 one component 2 Other ingredients

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuro Nakao 7 Kitatone, Sowa-machi, Sarushima-gun, Ibaraki Japan Vilene Co., Ltd. Incorporated (56) Reference JP 5-182654 (JP, A) JP 4-345753 (JP, A) JP 57-141862 (JP, A) JP 2-304862 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 2/16 H01M 6/06 H01M 10/24

Claims (11)

(57) [Claims] 1. A separator for an alkaline battery , which is mainly composed of ultrafine fibers obtained by splitting a polyolefin-based splittable conjugate fiber and is composed only of a hydroentangled nonwoven fabric made of a polyolefin-based fiber.
A separator for an alkaline battery , wherein the hydroentangled nonwoven fabric is hydrophilized. 2. The separator for an alkaline battery according to claim 1, wherein the hydroentangled nonwoven fabric is adhered with a mixed low melting point polyolefin adhesive fiber. 3. The separator for an alkaline battery according to claim 1, wherein the hydroentangled nonwoven fabric is graft-polymerized with a vinyl monomer to make it hydrophilic. 4. The polyethylene fiber is used as the hydroentangled nonwoven fabric.
Fiber, polypropylene fiber, or polyethylene, polypropylene
Pyrene, ethylene-propylene copolymer, ethylene-
Core-sheath combining butene-propylene copolymer
Type, side-by-side type, eccentric type, chrysanthemum-shaped fiber cross section
Having, having a cross-section of fibers laminated in alternating layers, splitting
Polyolefins selected from non-dividing or non-dividing composite fibers
Hydroentanglement treatment for fiber webs made of
Claims 1 to 1, characterized in that they are obtained by
Item 5. The alkaline battery separator according to any one of Item 3. 5. The ultrafine fibers are separated by hydroentangling treatment.
Characterized in that the splittable conjugate fiber is obtained by dividing
The alkaline electrolyte according to any one of claims 1 to 4.
Pond separator. 6. The fineness of the ultrafine fibers is 0.01 to 0.4.
It is denier, It is characterized by the above-mentioned.
The alkaline battery separator according to any one of 1. 7. The splittable conjugate fiber is a polyethylene resin.
It contains a component and a polypropylene resin component.
Al according to any one of claims 1 to 6,
Potassium battery separator. 8. The low melting point polyolefin adhesive fiber
Uses polypropylene resin component and polyethylene resin component
Characterized by consisting of partially fused composite fiber containing And the contract
The alkaline battery cell according to any one of claims 2 to 7.
Parator. 9. The hydroentangled nonwoven fabric is formed by a wet method.
Obtained by hydroentangling a fibrous web
Any one of claims 1 to 8 characterized in that
The alkaline battery separator described in. 10. The hydrophilizing treatment is performed by fuming sulfuric acid.
Claim 1 or 2 or claim, characterized in that
Item 4. An alkaline battery separator according to any one of items 4 to 9.
Lator. 11. The hydrophilic treatment is a fluorine gas treatment.
Claim 1 to 2 or Claim 4 to Claim, characterized in that
Item 10. The alkaline battery separator according to any one of Item 9.