JP2000315488A - Separator sheet for battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve absorptiveness of electrolyte, allow thinning, and extend battery service life by mixing in a specific ratio hydrophilic polyolefinic fiber with a specific single fiber fineness. SOLUTION: Using hydrophilic polyoefinic fiber with 0.0001-0.5 d single fiber fineness, pore size is reduced, separating ability is improved, and this separator is further thinned. From a point of liquid absorptiveness, by using such fineness of olefinic fiber, holding and absorption of electrolyte among fibers regardless of liquid absorptiveness of fiber itself is allowed. In addition, the olefinic fiber has high swelling resistance and can suppress inner resistance even for small fiber degree. This extra film fiber of 2-40 wt.% is added to hold the liquid absorptiveness, suppress the inner resistance, and provide the swelling resistance. Thus, because mechanical performance does not degrade even when using the extra fine fiber, the highly sturdy separator is provided, and swelling of the separator is suppressed, occupation rate of the separator is reduced, and battery service life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a battery separator sheet suitable for an alkaline primary battery such as an alkaline manganese battery, a mercury battery, a silver oxide battery, and an air zinc battery, a method for producing the same, and the battery separator sheet. The present invention relates to a battery separator.

[0002]

2. Description of the Related Art Generally, batteries such as an alkaline primary battery include:
A separator for separating the anode active material and the cathode active material is used. This separator should prevent internal short circuit between the anode material and the cathode material.It should have a high electrolyte absorption property to generate a sufficient electromotive reaction. It is small and can increase the amount of anode active material (battery life can be extended)
Various performances are required. As a battery separator having the above performance, because it has excellent chemical resistance, hydrophilicity, mechanical performance, etc., a battery separator using polyvinyl alcohol-based fiber, and in order to further improve electrolyte liquid retention, etc. Conventionally, battery separators using cellulosic fibers and the like have been widely used.

[0003]

However, with the recent development of electric appliances and the like, there has been a demand for batteries of higher performance and longer usable time. Therefore, further improvements such as swelling resistance of battery separators have been made.・ Thinning is strongly demanded. An object of the present invention is to provide a battery separator sheet which is excellent in internal short-circuit prevention property and electrolyte absorbing property, and which can be further thinned and can extend the usable time of a battery, a method for producing the same, and further using the separator sheet. An object of the present invention is to provide a battery separator.

[0004]

Means for Solving the Problems The present invention provides (1) a separator paper for batteries comprising 2 to 40% by weight of a hydrophilic polyolefin fiber having a single fiber fineness of 0.0001 to 0.5 d; 2 to 40% by weight of a hydrophilic polyolefin-based fiber having a single fiber fineness of 0.0001 to 0.5 d, and 10 to 10% of a polyvinyl alcohol-based fiber and / or a cellulose-based fiber.
~ 98% by weight of separator paper for batteries,
(3) The separator paper for a battery according to (1) or (2), wherein the hydrophilic polyolefin fiber has a single fiber fineness of 0.1 d or less, and (4) the hydrophilic polyolefin fiber is a sulfonated polyolefin fiber. (1)-(3)
The battery separator paper according to any one of the above. (5) Single fiber fineness obtained by removing the sea component of a sea-island component having an olefin-based polymer as an island component: 0.0001 to
(5) a method for producing a separator paper for a battery, which is wet-processed using 0.5 d of a hydrophilic polyolefin-based fiber so that the compounding ratio of the hydrophilic polyolefin-based fiber is 2 to 40% by weight; Using a hydrophilic polyolefin-based fiber having a single fiber fineness of 0.0001 to 0.5 d obtained by removing the sea component of the sea-island component as a component and then performing a sulfonation treatment, the compounding ratio of the hydrophilic polyolefin-based fiber is 2 (7) (1)-a method for producing a separator paper for a battery which is wet-processed so as to have a concentration of ４０40% by weight;
A battery separator using the battery separator paper according to (4).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a single fiber fineness of 0.000.
1 to 0.5 d of hydrophilic polyolefin-based fiber
It has been found that a battery separator excellent in various performances can be obtained by using a battery separator paper in which the weight% is blended. By using such a hydrophilic polyolefin-based fiber, the pore size is reduced, so that excellent separating properties (prevention of internal short-circuiting) are ensured even when the fiber is made thin, and the mechanical performance is not deteriorated even with an ultrafine fiber. Not only does the separator have a high stiffness, but also the swelling of the separator is significantly suppressed, so that the occupancy of the separator can be reduced (the usable time of the battery can be extended).

In the present invention, the single fiber fineness is 0.5 d or less, preferably 0.1 d or less, more preferably 0.0 d or less.
It is necessary to use an olefin fiber of 5d or less. By using such ultrafine fibers, the pore size is reduced, the separation properties can be further improved, and the separator can be further reduced in thickness. In addition, it is necessary to use an olefin-based fiber having such fineness from the viewpoint of liquid absorption.
In other words, when the fineness of the olefin fiber is small, it is possible to retain the electrolyte between the fibers, but since the fiber itself has a low liquid absorbing property, when the fineness increases, the liquid absorbing property of the separator also decreases. Becomes In the case of a fiber having a high swelling property, if the fineness is too small, there is a problem that the internal resistance becomes large. The effect is obtained. From the viewpoint of suppressing the increase in papermaking property and internal resistance, the single fiber fineness is 0.0001 d or more, particularly 0.1 fiber.
It is preferable to use an olefin-based fiber of 01d or more.
The fiber length is 0.5 to 2 from the viewpoints of papermaking properties, separation properties, and the like.
It is preferably 0 mm, especially 1 to 5 mm.

In the present invention, it is necessary to use at least a hydrophilic olefin-based ultrafine fiber. For example, even when polyvinyl alcohol (PVA) -based ultrafine fibers are blended, the separator has improved separating properties, but PVA-based fibers tend to swell more easily than olefin-based fibers because of their high hydrophilicity, In particular, the tendency is remarkable in the case of ultrafine fibers. Therefore, even if the PVA-based ultrafine fibers are blended, the swelling of the separator cannot be suppressed remarkably as in the present invention (the occupancy of the separator cannot be reduced), and the battery usable time is extended as in the present invention. I can't let it go. Further, since the olefinic ultrafine fiber has excellent swelling resistance, the internal resistance is hardly increased even when the ultrafine fiber is blended, and a more excellent effect can be obtained.

[0008] The compounding amount of such olefinic ultrafine fibers is:
2 to 40% by weight / paper, preferably 3% by weight or more / paper, more preferably 4% by weight or more / paper, and preferably 30% by weight or less / paper, and more preferably 20% by weight or less / paper. If the blending amount of the olefinic ultrafine fiber is too large, the liquid absorbing property becomes insufficient and the internal resistance increases, and if the blending amount is too small, the effect of the present invention is sufficiently obtained in terms of swelling resistance and the like. Absent.

Although usable olefin fibers are not particularly limited, it is preferable to use polypropylene fibers and / or polyethylene fibers. In the propylene-based polymer and / or the ethylene-based polymer, a hydroxyl group, a carboxyl group, fluorine, chlorine and the like may be introduced,
Other components may be copolymerized as long as the effects of the present invention are not impaired. The copolymerization ratio is 40% by weight.
Below, it is particularly preferable that the content is 30% by weight or less. Among them, polypropylene fibers are more preferable in the present invention, particularly from the viewpoint of chemical resistance and swelling resistance. Especially spinnability,
From the viewpoint of swelling resistance and the like, it is more preferable to use fibers made of a propylene resin having a weight average molecular weight of 80,000 to 150,000, particularly 100,000 to 120,000. Of course, two or more kinds of resins may be used in combination, and may contain additives such as an antioxidant and a process aid within a range that does not adversely affect battery performance when used as a battery separator.

[0010] The method for producing the fiber is not particularly limited. However, it is difficult to obtain ultrafine fibers simply by spinning a polyolefin-based resin. Therefore, a method of spinning a multi-component fiber containing an olefin-based polymer as one component and removing other components of the obtained multi-component fiber has been proposed. It is preferable to adopt a method of splitting the fiber made of the olefin-based polymer. Among them, it is preferable to employ a method of spinning sea-island fibers having an olefin-based polymer as an island component, and then removing the sea components of the sea-island fibers. Is obtained. Although ultrafine fibers can be obtained by removing the sea component (other components) after papermaking, the effect of the present invention cannot be obtained because the method does not result in a paper in which the fibers are densely entangled and the pore size becomes large. .

The polymer (component (B)) to be subjected to composite spinning or mixed spinning with the olefin polymer (component (A)) is not particularly limited as long as it is a thermoplastic polymer that can be removed without substantially impairing the performance of the olefin polymer. For example, a polyamide-based polymer (preferably nylon 6) that can be removed with an acidic aqueous solution, an alkali-reducible polyester-based polymer that can be removed with an alkaline aqueous solution, and the like can be given. From the viewpoints of spinnability, weight reduction processability, cost and the like, it is preferable to use an alkali-reducible polyester.

The type of the specific polyester is not particularly limited, and a polyester which is decomposed and / or dissolved by an alkali may be used. Among them, it is preferable to use a polyester which dissolves or decomposes within 1 hour, particularly within 30 minutes when immersed in a sodium hydroxide aqueous solution of 98 ° C. and 20 g / l at a bath ratio of 1: 500 and stirred.

[0013] The component A and the component B are mixed and spun.
A sea-island fiber having an island component as the component and a sea component as the B component may be produced. The mixing ratio of the A component and the B component may be appropriately changed, but from the viewpoint of cost, fiber diameter, and the like, A component: B component = 30: 70 to 95: 5, particularly 40:60 to 70:30.
(Weight ratio). The term “island-in-the-sea fiber” as used in the present invention means that there are several to tens of thousands, preferably about tens to thousands of islands (component A: olefin-based resin) in the sea component serving as a matrix in the cross section of the fiber. Refers to fiber. The sea-island fibers are formed by extrusion and the island components are continuous to some extent in the fiber axis direction, and the diameter and cross-sectional shape of the sea-island fibers are not particularly limited.

In the present invention, it is necessary to use hydrophilic olefin fibers. When using a highly hydrophobic olefin fiber, the liquid absorbing property of the separator, the liquid absorbing speed,
Water dispersibility and inter-fiber adhesion are impaired, and a desired separator cannot be obtained. As the hydrophilic polyolefin-based fiber, the degree of hydrophilicity measured by the method of Example was 0.30 g /.
g or more, particularly preferably 0.40 g / g or more. As the hydrophilic olefin fiber used in the present invention, a fiber composed of a polyolefin polymer into which a hydrophilic group has been introduced, or a polyolefin fiber composed of an ordinary highly hydrophobic olefin polymer can be used. Fibers obtained by treatment are preferred. The method for introducing the hydrophilic group is not particularly limited. For example, a method of copolymerizing a maleic anhydride alkyl ester, an unsaturated carboxylic acid alkyl ester, or the like can be suitably used, but the latter method is used because it is not preferable in terms of cost. Is preferred.

[0015] Examples of the hydrophilization treatment include treatments such as application of a surfactant, sulfonation treatment, plasma treatment, and sputtering treatment. Two or more of these treatments may be used in combination. Above all, it is preferable to perform at least a sulfonation treatment from the viewpoint of improving hydrophilic durability. In particular, sulfonation is preferably performed so that the sulfur concentration is 1500 ppm or more from the viewpoint of hydrophilicity and the like, and 10000 ppm or less, particularly 8000 ppm or less from the viewpoint of processability and cost. The sulfonation method is not particularly limited, and examples thereof include a method of treating with a sulfonation solution containing fuming sulfuric acid, sulfuric acid, chlorosulfuric acid, sulfuryl chloride and the like.

Among them, fuming sulfuric acid is preferred because it has high reactivity and can be sulfonated relatively easily. Ideally, after the sulfonation treatment, the fibers are washed with concentrated sulfuric acid, diluted diluted sulfuric acid, and water in that order, and then dried. Of course, other hydrophilic treatment may be performed before or after performing the sulfonation treatment,
Fibers obtained by spinning a hydrophilic polyolefin and subjected to a hydrophilic treatment may be used. It is also possible to subject the paper to a hydrophilization treatment after papermaking, but in the case of performing a sulfonation treatment, there is no adverse effect on other compounding components, and the drying step etc. is quick, and papermaking is also performed. It is preferable to subject the polyolefin fiber before sulfonation to sulfonation from the viewpoint of improving the adhesiveness to other fibers during the process. By using the hydrophilized fiber, the adhesiveness with other fibers having a high liquid absorbing property is improved, and particularly, the liquid absorbing speed of the electrolytic solution is remarkably improved. The liquid absorption rate of the separator is preferably 300 sec / 25 mm or less.

The type of fiber that can be used in combination with the hydrophilic olefin-based ultrafine fiber is not particularly limited. However, from the viewpoint of increasing the liquid absorbing property of the separator, a fiber having at least excellent chemical resistance and electrolyte absorbing property is used. Is preferred. Specifically, PV
It is preferable to mix the A-based fiber and / or the cellulosic fiber as a main component, and the compounding amount of the fiber is 10 to 98% by weight / paper, preferably 50% by weight or more / paper, more preferably 60% by weight or more. Paper, preferably 95% by weight or less / paper.

From the viewpoint of the liquid absorbing property and mechanical performance of the separator, it is preferable to mix both PVA-based fibers and cellulosic fibers. The amount of the PVA-based fibers is preferably 5% by weight or more, more preferably 10% by weight or more. And more preferably 50% by weight or less, particularly preferably 40% by weight or less. For the same reason, the amount of the cellulosic fiber is preferably at least 10% by weight, more preferably at least 30% by weight.
Further, it is preferably at most 90% by weight, particularly preferably at most 80% by weight. Although both PVA-based fibers and cellulosic fibers are excellent in electrolyte-absorbing properties, cellulose-based fibers have higher electrolyte-absorbing properties, and PVA-based fibers have more swelling resistance and mechanical properties. Excellent in performance. Therefore, desired performance can be obtained by changing the mixing ratio of both fibers.

The PVA-based fiber usable in the present invention is not particularly limited, but the main fiber is preferably a fiber having a water dissolution temperature of 90 ° C. or higher, particularly 100 ° C. or higher. Specifically, a fiber comprising a vinyl alcohol-based polymer having an average degree of polymerization of 1,000 to 5,000 and a degree of saponification of 95 mol% or more, particularly 99 mol% or more, is preferably exemplified. The vinyl alcohol polymer may be copolymerized with another copolymer component, but the copolymerization ratio is preferably 30 mol% or less, particularly preferably 10 mol% or less from the viewpoint of water resistance and the like. Further, a treatment such as acetalization may be performed. Also P
The VA-based fiber does not need to be composed of only the vinyl alcohol-based polymer, and may contain another polymer. Of course, it may be a composite spun fiber with other polymer or a mixed spun fiber (sea-island fiber). From the viewpoints of electrolyte absorption, mechanical performance, etc., the content of the vinyl alcohol-based polymer is 30% by weight or more, particularly 50% by weight or more,
It is preferable to use PVA-based fibers containing not less than% by weight. The fineness of the fiber is preferably 3d or less, particularly 1d or less, and more preferably 0.8d or less from the viewpoint of separation properties and thinning.
d or more, more preferably 0.2d or more. The fiber length may be set appropriately according to the single fiber denier,
Fiber length 0.5 to 10 mm, especially 1 to 5
mm is preferable.

The cellulosic fibers usable in the present invention include rayon fibers (including polynosic rayon fibers), acetate fibers, and natural pulp (wood pulp, cotton linter pulp, hemp pulp, etc.). That has undergone processing such as mercerization processing,
These beaten products can also be used. It is preferable to use rayon fibers from the viewpoint of alkali resistance, swelling resistance and the like. The fineness of the cellulosic fiber is not particularly limited, and for example, cut fibers having a fineness of about 0.1 to 3 d, beaten products of cut fibers or pulp, etc. can be used, but from the viewpoint of swelling resistance, fineness is about 0.1 to 3 d. It is preferable to mix the cut fibers of at least 30% by weight / paper. Of course, a cut fiber and a pulp-like material may be used in combination.

From the viewpoints of mechanical performance and dimensional stability of the nonwoven fabric, the dissolution temperature in water is 80 ° C. or less, preferably 60 to 75 ° C.
It is preferable to mix the binder component (resin-like or fibrous-like). It is preferable to use a fibrous binder from the viewpoint of reducing the increase in the pore size and the internal pressure of the paper, and it is particularly preferable to mix a PVA-based fibrous binder because of its hydrophilicity and high liquid absorbing property. Among them, the average degree of polymerization is 50
PVA having a degree of saponification of 97 to 99 mol%, in the range of about 0 to 3000
Are preferably used. Of course, it is not necessary to be composed of only the vinyl alcohol-based polymer, and other polymers may be included. Of course, composite spun fibers with other polymers, mixed spun fibers (sea-island fibers)
It may be. From the viewpoints of electrolyte absorbency, mechanical performance, etc., P containing at least 30% by weight of vinyl alcohol-based polymer, particularly at least 50% by weight, and more preferably at least 80% by weight.
It is preferable to use VA fiber. The fineness of the PVA-based fiber is preferably about 0.2 to 2d from the viewpoint of water dispersibility, adhesion to other components, pore size, and the like, and the fiber length is 1 to 5
It is preferably about mm. Of course, fibers other than the above fibers may be blended.

Papermaking is performed using such fibers to obtain a separator paper for a battery, but the method is not particularly limited. For example, a desired paper can be efficiently manufactured by using a general wet paper machine. Examples of the paper net used include circular nets, short nets and long nets, and these paper nets can be used alone or as a single layer, or as a multi-layer sheet by combining the paper nets. Good. From the point of obtaining a paper having uniform formation and excellent electrical properties, it is preferable to make a multi-layered paper, especially a two-layer paper with a short net-circle paper machine. Is preferred. After the slurry containing the paper stock is formed, the slurry is dried by a Yankee dryer or the like, whereby the intended battery separator is obtained. Needless to say, hot press working or the like can be further performed as necessary.

The thickness of the separator paper is preferably 0.2 mm or less, particularly 0.1 mm or less, and more preferably 0.09 mm or less from the viewpoint of liquid retention and thinning.
It is preferably at least 0.05 mm, more preferably at least 0.06 mm, in terms of mechanical performance and stiffness. For the same reason, the density is 0.5 g / cm ³ or less, further 0.4 g / cm ³ or less,
Further, it is preferably 0.35 g / cm ³ or less,
It is preferably 0.1 g / cm ³ or more.

The pore size of the separator paper is preferably 20 μm or less, particularly 18 μm or less, more preferably 17 μm or less, and further preferably 15 μm or less from the viewpoint of separation properties, and is preferably 10 μm or more from the viewpoint of pressure loss and the like. For the same reason, the air permeability of the paper is 22 cc / cm.
² cc / cm ² / sec or less, especially 20 cc / cm ² / sec or less, further 15 cc / cm ² / sec or less, and further 13 c
c / cm ² / sec or less, preferably 5 cc / cm ² / sec or more from the viewpoint of internal pressure.

The degree of swelling (%) of the separator paper is 15% or less, particularly 13% or less, further 9% or less, from the viewpoints of reducing the occupied area in the battery, suppressing an increase in internal pressure, and securing mechanical performance. It is preferably at most 5%, and particularly preferably at most 3%. Also, the electrolyte absorption of the separator paper is 0.2 g / 2500 mm ² or more, especially 0.1 g.
3g / 2500mm ² or more, further 0.35g / 250
A separator having a thickness of 0 mm ² or more is preferable. According to the present invention, a separator having excellent electrolyte solution absorbability can be obtained.

In view of the mechanical performance, dimensional stability, handleability, etc. of the separator paper, the breaking length is preferably 4 km or more, particularly 4.5 km or more, more preferably 5 km or more, and the stiffness is 0.25 kgf or more. And more preferably 0.3 kgf or more. Particularly, those having high stiffness not only facilitate the incorporation into the battery, but also have an excellent effect that the battery is hardly deformed even when subjected to an impact due to a drop or the like during use of the battery and the occurrence of an internal short circuit due to the deformation can be suppressed.

The battery separator paper of the present invention can be used as it is, or can be processed into a desired shape such as a bag-like body or a spiral-like body to obtain a battery separator.
Of course, a battery separator may be manufactured in combination with a material other than the battery separator paper of the present invention. For example, it can be laminated or spliced with another nonwoven fabric, film, or the like. However, from the viewpoint of efficiently obtaining the effects of the present invention, it is preferable to manufacture a battery separator from substantially only the battery separator paper of the present invention. Although the battery separator paper of the present invention can be applied to any battery separator, alkali resistance, alkali manganese batteries, because they are excellent in absorption of alkaline electrolyte,
It is suitable as a separator for an alkaline primary battery such as a mercury battery, a silver oxide battery, and a zinc-air battery, and has particularly excellent performance as a separator for an alkaline manganese battery.
By incorporating the battery separator of the present invention, a battery excellent in various performances can be obtained.

[0028]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. [Weight average molecular weight] Measured by GPC method. [Sulfur Concentration ppm] The absorption liquid in which the sample was subjected to sulfur absorption by the oxyfuel combustion flask method was determined using an ion chromatography analyzer (manufactured by Yokogawa Electric Corporation). [Hydrophilicity g / g] A polyolefin fiber having a weight of Ag was immersed in a 35% KOH solution at a bath ratio of 1/100 for 24 hours, and then centrifugally dehydrated under a condition of 3000 rpm × 10 min to obtain a weight Bg of the fiber. Measure, (BA) / A
Was calculated by

[Dissolution temperature in water ° C] 400 cc of water (2
0 ° C.), 2.6 g of the sample fiber was charged, and the temperature was raised at a rate of 1 ° C./m
In, the temperature was raised while stirring at a stirring speed of 280 rpm, and the temperature at which the fibers were completely dissolved was measured as the water dissolution temperature in water. [Freeness (CSF) ml] The Canadian standard freeness was measured according to JIS P 8121 "Testing Method for Freeness of Pulp".

[Thickness mm Density g / cm ³ ] JIS
P 8118 "Test methods for thickness and density of paper and paperboard"
It measured according to. [Basic weight g / m ² ] Measured according to JIS P 8124 “Measurement of metric basis weight of paper”. [Tear length km] Measured in accordance with JIS P 8113 "Test method for tensile strength of paper and paperboard".

[Liquid absorption g / g] A paper sample of 50 mm × 50 mm was treated with 35% KOH solution at a bath ratio of 1/100 for 24 hours.
The sample was immersed for 30 hours and drained naturally for 30 seconds, the weight of the sample was measured, and the amount of liquid absorbed was calculated by dividing the weight of the retained liquid by the weight of the paper. [Liquid Absorption Speed] The end of the sample was immersed in a 35% KOH solution, and the absorption speed was evaluated based on the time required for the 35% KOH solution to suck up to a height of 25 mm.

[Air permeability: cm ³ / cm ² / sec] JIS
L 1096-1996 According to the air permeability measurement method of "General Textile Test Method", the air permeability was measured by a Brasil-type air permeability tester manufactured by Toyo Seiki Seisaku-sho, Ltd. [Pore size μm] Measured by colter POROMETER II manufactured by Coulter Electronics Co., Ltd.

[Swelling degree%] The sample was made of 35% KOH and 30%.
After immersion for a minute, the thickness of the sample before and after immersion was measured with a dial thickness gauge, and the degree of swelling was calculated by (thickness after immersion-thickness before immersion) / thickness before immersion × 100. [Koshi kgf] 25% × 90mm sample is 35% K
After immersion in OH for 30 minutes, 20mm 'height) x 7mm
巻 き Rolled around the core 4 times, 20mm (height) × 9mmФ
(Inner diameter) was set in a cylinder, and the method of measuring the compression strength was used with "Rheometer RT-2010-CW" manufactured by Leotech Co., Ltd.

[Easily Alkali-Reducing Polyester Fiber] 5
-Sodium sulfoisophthalic acid (I) accounts for 2.5 mol% of all the acid components constituting the copolymerized polyester, and has a molecular weight of 20.
The structural units obtained from the polyethylene glycol (II) of formula No. 00 and the polyoxyethylene glycidyl ether (III) represented by the chemical formula 1 are each one of the total copolymerized polyesters.
A copolyester (intrinsic viscosity 0.58 dl / g), which occupies 0% by weight and the remainder is constituted by constituent units obtained from terephthalic acid and ethylene glycol, was used. The copolymerized polyester was completely dissolved within 30 minutes when immersed in a 20 g / liter aqueous solution of sodium hydroxide at 98 ° C. with a bath ratio of 1: 500 and stirred.

[0035]

Embedded image

Reference Example 1 Weight average molecular weight 10520
0, 50% by weight of polypropylene having a melting point of 166 ° C. and 50% by weight of an alkali-reducible copolyester were mixed and spun to form a 3.5-denier 3.5-denier polypropylene comprising an island component and an alkali-reducible copolyester comprising a sea component. A sea-island type fiber (number of islands: 50) was manufactured, cut into a length of 3 mm, immersed in a 6% NaOH aqueous solution (80 ° C.) for 30 minutes to remove sea components, and the single fiber fineness was 0.035 denier. Was produced. This fiber is sulfonated with fuming sulfuric acid, washed with concentrated sulfuric acid, dilute sulfuric acid, and water in that order to obtain a hydrophilic polypropylene fiber (sulfur concentration of 6600 pp).
m, hydrophilicity 0.44 g / g).

Reference Example 2 Weight average molecular weight 10520
0, 50% by weight of polypropylene having a melting point of 166 ° C., and 50% by weight of an alkali-reducible copolyester were mixed and spun to obtain 11.2 denier polypropylene having an island component and an alkali-reducible copolyester constituting a sea component. A sea-island type fiber (16 islands) was manufactured, cut into a length of 10 mm, and then cut with a 6% NaOH aqueous solution (80 ° C.).
The resultant was immersed for a minute to remove the sea component, thereby producing a polypropylene fiber having a single fiber fineness of 0.35 denier. This fiber is sulfonated with fuming sulfuric acid, washed with concentrated sulfuric acid, dilute sulfuric acid, and water in this order to obtain hydrophilic polypropylene fiber (sulfur concentration 5200p
pm, hydrophilicity: 0.39 g / g). [Reference Example 3] Weight average molecular weight 105200, melting point 166
A polypropylene fiber of 0.7 d obtained by melt-spinning polypropylene at 5 ° C. is cut into a length of 5 mm, and then the fiber is sulfonated with fuming sulfuric acid.
After washing in the order of water, a hydrophilic polypropylene fiber (sulfur concentration 3300 ppm, hydrophilicity 0.35 g / g) was obtained.

Example 1 5 parts by weight of the hydrophilic polypropylene fiber (0.035 d × 3 mm) obtained in Reference Example 1 and a polyvinyl alcohol-based main fiber (0.5 d × 2)
mm “VPB053 × 2” manufactured by Kuraray Co., Ltd., dissolution temperature in water of 100 ° C. or more) 30 parts by weight, rayon fiber (1d
× 2mm, manufactured by Toyobo Co., Ltd. “KPR1.0 ×
2 ", CSF600ml) 50 parts by weight, PVA-based binder fiber (1d x 3mm" VPB1 "manufactured by Kuraray Co., Ltd.
05-1 × 3 ”, dissolution temperature in water 70 ° C.) 15 parts by weight were dispersed in water to produce a slurry, which was then made into a two-layered papermaking machine using a short-mesh netting machine, followed by Yankee drying. Drying was carried out with a machine to obtain the intended battery separator paper. The obtained separator paper has high strength even with a thin thickness, separation properties,
It had high performances such as electrolyte absorption, and excellent swelling resistance. In addition, the formation was extremely good and homogeneous because of the two-layer lamination structure, and had an excellent structure as separator paper. Table 1 shows the results.

Examples 2 and 3, Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the mixing ratio was changed as shown in Table 1.
Table 1 shows the results. Example 4 The procedure of Example 1 was repeated, except that the hydrophilic polypropylene fiber (0.35 d × 10 mm) obtained in Reference Example 2 was used and the composition was changed as shown in Table 1. Table 1 shows the results.

Comparative Examples 3 and 4 The hydrophilic polypropylene fibers obtained in Reference Example 3 (0.7 d × 5 m
Example 1 was carried out in the same manner as in Example 1 except that the composition was changed as shown in Table 1 using m) or without blending the hydrophilic polypropylene fiber. In Comparative Example 3, the electrolyte solution retention property and the swelling resistance were excellent, but the pore size was large and the separation property was low. Further, although the separator obtained in Comparative Example 4 was excellent in electrolyte retention, it had a large area occupied by the battery due to low swelling resistance, and the usable time of the battery was shorter than that in Examples. . Table 1 shows the results. The polyvinyl alcohol-based main fiber (1.0 d × 3 mm) used in Comparative Example 4 was:
It is a fiber having a dissolution temperature in water of 100 ° C. or higher (“VPB103 × 3” manufactured by Kuraray Co., Ltd.), and the CSF of mercerized cotton is 550 ml.

[0041]

[Table 1]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L055 AF10 AF17 AF21 AF44 AF47 EA04 EA16 FA30 GA01 GA37 GA50 5H021 CC01 EE04 EE05 HH01 HH03

Claims (7)

[Claims] 1. A battery separator paper comprising 2 to 40% by weight of a hydrophilic polyolefin fiber having a single fiber fineness of 0.0001 to 0.5 d. 2 to 40% by weight of a hydrophilic polyolefin-based fiber having a single fiber fineness of 0.0001 to 0.5 d, and 10 to 10% of a polyvinyl alcohol-based fiber and / or a cellulose-based fiber.
-98% by weight of separator paper for batteries. 3. The separator paper for a battery according to claim 1, wherein the single-filament fineness of the hydrophilic polyolefin-based fiber is 0.1 d or less. 4. The battery separator sheet according to claim 1, wherein the hydrophilic polyolefin fiber is a sulfonated polyolefin fiber. 5. A hydrophilic polyolefin fiber having a single fiber fineness of 0.0001 to 0.5 d obtained by removing a sea component of a sea-island component having an olefin polymer as an island component. The method for producing a separator paper for a battery, which is wet-processed so that the compounding ratio of is 2 to 40% by weight. 6. A hydrophilic polyolefin-based fiber having a single fiber fineness of 0.0001 to 0.5 d obtained by removing a sea component of a sea-island component having an olefin-based polymer as an island component and subjecting it to sulfonation treatment. A method for producing a separator paper for a battery, which is wet-processed so that the compounding ratio of the hydrophilic polyolefin-based fiber is 2 to 40% by weight. 7. A battery separator using the battery separator paper according to claim 1. Description: