JP2001076702A - Separator paper sheet for battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator paper sheet for a battery excellent in an internal short circuit preventing property and an electrolyte absorbing property, capable of being made thin, and capable of prolonging its operating period for the battery by blending ethylene-vinyl alcohol copolymer fibers with a specific single fiber fineness at a specific ratio. SOLUTION: The single fiber fineness of copolymer fibers with a hydrophilic group is 0.0001-0.5 d, and the blending ratio is 2-45 wt.%. The copolymer fibers are preferably blended with 10-98 wt.% of polyvinyl alcohol and/or cellulose fibers having a high hydrophilic property and a good separating property and easily swelled. The pressure loss by the suppression of the swelling of fibers is reduced, the deterioration of the mechanical performance extra fine fibers is prevented, the separating property by a small bore size of a thin separator paper sheet is secured, and a sufficient liquid absorbing property can be attained. The sea component of sea island fibers containing the spun ethylene-vinyl alcohol copolymer as the island component is removed, and the obtained copolymer fibers with the prescribed single fiber fineness are wet-spun at the prescribed ratio to manufacture the separator paper sheet as a preferable method.

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 a battery comprising 2 to 45% by weight of an ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 0.0001 to 0.5 d. , (2) single fiber fineness 0.0001
(3) ethylene separator paper containing 2 to 45% by weight of ethylene-vinyl alcohol copolymer fiber of 0.5 to 0.5d and 10 to 98% by weight of polyvinyl alcohol fiber and / or cellulose fiber. -Single fiber fineness obtained by removing the sea component of the sea-island fiber having a vinyl alcohol copolymer as an island component; 0.0001 to
A method for producing a separator paper for a battery, which uses 0.5d ethylene-vinyl alcohol-based copolymer fiber and wet-processes the paper so that the blending ratio of the ethylene-vinyl alcohol-based copolymer fiber is 2 to 45% by weight; (4) A battery separator using the battery separator paper according to (1) or (2).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a single fiber fineness of 0.000.
It has been found that a battery separator excellent in various performances can be obtained by using a battery separator paper containing 2 to 45% by weight of an ethylene-vinyl alcohol copolymer fiber of 1 to 0.5 d. When ultrafine fibers having high hydrophilicity such as polyvinyl alcohol (PVA) fibers are blended, the separator has an improved separating property but tends to swell, and the tendency is particularly remarkable in the ultrafine fibers. Therefore, when the PVA-based ultrafine fibers are blended, the swelling of the separator cannot be suppressed, so that not only the battery usable time cannot be efficiently extended but also the pressure loss increases. However, in the present invention, since the ethylene-vinyl alcohol copolymer fiber is used, the swelling of the fiber is suppressed, and the pressure loss does not become a problem. Therefore, a separator having a high "stiffness" can be obtained. Further, since the pore size is reduced, excellent separation properties (prevention of internal short circuit) can be ensured even when the thickness is reduced.
Further, in general, when an olefin-based fiber is blended, the hydrophilicity is reduced and the liquid absorbing property of the electrolyte is likely to be impaired. In order to increase the hydrophilicity by sulfonation treatment or the like, enormous labor and complicated steps are required. However, in the present invention, since the ethylene-vinyl alcohol-based copolymer has a hydrophilic group, it is possible to efficiently increase the separating property, the swelling resistance, etc. without substantially impairing the liquid absorbing property, etc. Can be.

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 ethylene-vinyl alcohol copolymer 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. It is also necessary to use ethylene-vinyl alcohol copolymer fibers having such a fineness from the viewpoint of liquid absorption. That is, when the fineness of the ethylene-vinyl alcohol-based copolymer fiber is small, it is possible to retain the electrolyte between the fibers, but since the fiber itself is not so high in liquid absorbency, if the fineness increases, the separator becomes large. Will also decrease the liquid absorbency. 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 increases.However, since the ethylene-vinyl alcohol copolymer fiber has a high swelling resistance, when the fineness is extremely small. However, excellent effects can be obtained. From the viewpoint of suppressing the increase in papermaking properties and internal resistance, single fiber fineness of 0.0001
It is preferable to use ethylene-vinyl alcohol-based copolymer fibers of d or more, particularly 0.01 d or more. The fiber length is preferably from 0.5 to 20 mm, particularly preferably from 1 to 5 mm, from the viewpoints of papermaking properties, separation properties, and the like.

[0007] The blending amount of the ultrafine fibers of the ethylene-vinyl alcohol copolymer is 2 to 45% by weight / paper, preferably 3% by weight or more / paper, more preferably 4% by weight or more / paper. % By weight / paper, preferably 20% by weight / paper. If the blending amount of the ethylene-vinyl alcohol-based ultrafine fibers is too large, the liquid absorbing property becomes insufficient and the internal resistance becomes large, while if the blending amount is too small, the effect of the present invention is sufficient in terms of swelling resistance and the like. Can not be obtained.

The ethylene-vinyl alcohol-based copolymer constituting the ethylene-vinyl alcohol-based copolymer fiber of the present invention is not particularly limited, but ethylene content is considered from the viewpoint of hydrophilicity, swelling resistance, spinnability, heat resistance and the like. Is preferably 30 to 70 mol% of a copolymer. As the ethylene content increases, the swelling resistance increases, but the liquid absorption tends to decrease. When the ethylene content decreases, the liquid absorption improves, but the swelling resistance tends to decrease. The ethylene content may be set according to the purpose or the like. From the viewpoint of swelling resistance and liquid absorption, it is particularly preferable that the ethylene content (the ratio of the repeating unit composed of ethylene) is 40 to 60 mol%. The copolymer may be any of random, block and graft copolymers.

The method for producing the ethylene-vinyl alcohol copolymer used in the present invention is not particularly limited, but it can be produced efficiently by saponifying the ethylene-vinyl acetate copolymer. From the viewpoint of hydrophilicity, the degree of saponification of the vinyl alcohol unit is preferably at least 95 mol%, particularly preferably at least 98 mol%. Further, other units may be copolymerized in the ethylene-vinyl alcohol-based copolymer, but from the viewpoint of efficiently obtaining the effects of the present invention, copolymer components other than ethylene units and vinyl alcohol units are preferred. Is preferably at most 30 mol%, particularly preferably at most 10 mol%. The average molecular weight of the copolymer is
500-5000, especially 8 in view of spinnability and hot water resistance
It is preferable to be about 00 to 3500.

Further, the ethylene-vinyl alcohol-based copolymer fiber does not need to be composed only of the ethylene-vinyl alcohol-based copolymer, and other fibers may be used as long as the effects of the present invention and battery performance are not adversely affected. Polymers and other additives (antioxidants, process aids, etc.) may be included. However, from the viewpoint of efficiently obtaining the effects of the present invention, the ratio of the ethylene-vinyl alcohol-based copolymer is 5%.
0% by weight or more, especially 70% by weight or more, further 90% by weight
It is preferable that this is the case.

[0011] The method for producing the fiber is not particularly limited. However, simply spinning an ethylene-vinyl alcohol copolymer is difficult to obtain ultrafine fibers,
It is preferable to employ a method of spinning a multi-component fiber having an ethylene-vinyl alcohol-based copolymer as one component, and removing or splitting the other components of the obtained multi-component fiber.
Among them, it is preferable to employ a method of spinning sea-island fibers having an ethylene-vinyl alcohol-based copolymer as an island component and then removing the sea component of the sea-island fiber, using ultrafine fibers obtained by such a method. The desired separator is obtained by papermaking. Ultrafine fibers can also be obtained by removing the sea component (other components) after papermaking,
According to this method, the paper does not become a paper in which fibers are entangled densely, and the pore size becomes large. Therefore, it is preferable to adopt a method of making paper using ultrafine fibers.

The polymer (component (B)) to be spin-spun or mixed with the ethylene-vinyl alcohol copolymer (component (A)) is a thermoplastic polymer which can be removed without substantially impairing the performance of the copolymer. It is not particularly limited. 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.

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 view of the liquid absorbing property, liquid absorbing rate and water dispersibility during papermaking, the hydrophilicity of the ethylene-vinyl alcohol copolymer fiber is 0.30 g / g or more, especially 0.35 g. / G or more, more preferably 0.38 g / g or more, and the water absorption rate is preferably 300 sec / 25 mm or less, particularly preferably 250 sec / 25 mm or less. At this time, in order to increase the hydrophilicity of the ethylene-vinyl alcohol copolymer fiber, that is, to increase the initial liquid absorption and liquid absorption speed when incorporated into the battery, and to further improve the water dispersibility during papermaking, A hydrophilic surfactant may be added to the fiber surface as long as the performance is not adversely affected.

The separator paper may be produced using such ethylene-vinyl alcohol-based ultrafine fibers, but the types of fibers that can be used in combination with the ultrafine fibers are not particularly limited. However, from the viewpoint of increasing the liquid absorption of the separator, it is preferable to mix fibers having at least excellent chemical resistance and electrolyte liquid absorption. Specifically, it is preferable to mix PVA-based fibers and / or cellulosic fibers as a main component, and the blending amount of the fibers is 10 to 98% by weight / paper, preferably 50% by weight or more / paper, and more preferably 60% by weight or more. It is preferable that the ratio is not less than 95% by weight / paper and not more than 95% by weight / paper.

From the viewpoints of the liquid absorbing property and mechanical performance of the separator, it is preferable to mix both PVA-based fibers and cellulosic fibers, and 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 better swelling resistance and mechanical properties. Excellent in performance. Therefore, desired performance can be obtained by changing the mixing ratio of both fibers.

The PVA fiber usable in the present invention is not particularly limited, but the main fiber is preferably a fiber having a dissolution temperature in water 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 20 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.

Further, the PVA-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). It is preferable to use a PVA-based fiber containing 30% by weight or more, particularly 50% by weight or more, and more preferably 80% by weight or more of a vinyl alcohol-based polymer from the viewpoints of electrolyte absorbency, mechanical performance, and the like. The fineness of the fiber is preferably 3 d or less, particularly 1 d or less, and more preferably 0.8 d or less from the viewpoint of separation properties and thinning, and is 0.1 d or more from the viewpoint of papermaking properties and suppressing an increase in internal pressure. It is preferably at least 0.2 d. The fiber length may be appropriately set according to the single fiber denier, but the fiber length is 0.5 to 10 from the viewpoint of papermaking properties and the like.
mm, particularly preferably 1 to 5 mm.

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). The content of the binder component is 1 to 30% by weight /
Paper, especially 5-20% by weight / paper is preferred. 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 500 to 3000
Fibers composed of PVA having a degree of saponification of 97 to 99 mol% 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, it may be a composite spun fiber with other polymer or a mixed spun fiber (sea-island fiber). It is preferable to use a PVA-based fiber containing 30% by weight or more, particularly 50% by weight or more, and more preferably 80% by weight or more of a vinyl alcohol-based polymer from the viewpoints of electrolyte absorbency, mechanical performance, and the like. 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 is preferably about 1 to 5 mm in fiber length. 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 / sec or less, particularly 20 cc / cm ² / sec or less, more preferably equal to or less than 17 cc / cm ² / sec, is preferably from the viewpoint of the internal pressure of 5 cc / cm ² / sec or more.

The degree of swelling (%) of the separator paper is 35% or less, particularly 30% or less, particularly 25% or less from the viewpoint of reducing the occupied area in the battery, suppressing an increase in internal pressure, and ensuring mechanical performance. Is preferred. The electrolyte absorption of the separator paper is 0.2 g / 2500 mm ² or more, especially 0.3 g.
/ 2500mm ² or more, further 0.35g / 2500m
m ² or more, particularly preferably 0.38 g / 2500 mm ² or more, is preferred. 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. It is preferred that 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. [Hydrophilicity g / g] Weight of fiber after immersing ethylene-vinyl alcohol fiber having a weight of Ag in a 35% KOH solution at a bath ratio of 1/100 for 24 hours and then centrifugally dewatering at 3000 rpm × 10 min. Bg was measured and (B
-A) / A was calculated.

[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 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 / l aqueous solution of sodium hydroxide at 98 ° C. and stirred at a bath ratio of 1: 500.

[0035]

Embedded image

Reference Example 1 Ethylene content of 44 mol%,
50% by weight of an ethylene-vinyl alcohol copolymer having a saponification degree of 99% (“E105Y” manufactured by Kuraray Co., Ltd.) and 50% by weight of an alkali-reducible copolyester were mixed and spun to obtain an ethylene-vinyl alcohol copolymer. A 3.5 denier sea-island type fiber (number of islands: 50) in which the coalesced is an island component and the alkali-reducible copolyester constitutes a sea component is produced, cut into a length of 3 mm, and then treated with a 6% NaOH aqueous solution ( (80 ° C.) for 30 minutes to remove the sea component to obtain an ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 0.035 denier (having a hydrophilicity of 0.50 g / g).

Reference Example 2 Ethylene content of 44 mol%
50% by weight of an ethylene-vinyl alcohol copolymer having a saponification degree of 99% (“E105Y” manufactured by Kuraray Co., Ltd.) and 50% by weight of an alkali-reducible copolyester were mixed and spun to obtain an ethylene-vinyl alcohol copolymer. A sea-island type fiber (number of islands: 16) of 11.2 denier, in which the coalesced is an island component and the alkali-reducible copolyester constitutes a sea component, is cut into a length of 10 mm and then cut into 6% NaO
The sea component was removed by immersion in an aqueous H solution (80 ° C.) for 30 minutes to obtain an ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 0.35 denier (hydrophilicity: 0.43 / g).

Reference Example 3 Ethylene content of 44 mol%,
50% by weight of an ethylene-vinyl alcohol-based copolymer having a saponification degree of 99% (“E105Y” manufactured by Kuraray Co., Ltd.) and 50% by weight of an alkali-reducible copolyester were composite-spun to obtain an ethylene-vinyl alcohol-based copolymer. A 2.2 denier core-sheath fiber in which the coalesced component is a core component and the alkali-reducible copolyester constitutes a sheath component is produced, cut into a length of 5 mm, and then cut into a 6% NaOH aqueous solution (80%).
C.) for 30 minutes to remove the sea component to obtain an ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 1.1 denier (having a hydrophilicity of 0.37 g / g).

Example 1 The ethylene-vinyl alcohol copolymer fiber obtained in Reference Example 1 (0.035
d x 3 mm) 5 parts by weight, polyvinyl alcohol-based main fiber (0.5 d x 2 mm Kuraray Co., Ltd. "VPB05
3 × 2 ”, dissolution temperature in water 100 ° C. or more) 30 parts by weight, rayon fiber (1d × 2 mm, manufactured by Toyobo Co., Ltd.“ K ”
PR1.0 × 2 ”, CSF600ml) 55 parts by weight, P
VA binder fiber (1d × 3mm “VPB105-1 × 3” manufactured by Kuraray Co., Ltd., dissolution temperature in water 70 ° C.) 1
A slurry is prepared by dispersing 0 parts by weight in water, and the slurry is made into two layers by a short-mesh-mesh paper machine. I got The obtained separator paper was excellent in various properties such as high strength, separation property, and electrolyte absorption property even in a thin thickness, and was excellent in 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 Ethylene-vinyl alcohol copolymer fiber obtained in Reference Example 2 (0.35 d × 10 mm)
And the procedure was the same as in Example 1 except that the composition was changed as shown in Table 1. Table 1 shows the results.

[Comparative Example 3, Comparative Example 4] Using the ethylene-vinyl alcohol copolymer fiber (1.1 d × 5 mm) obtained in Reference Example 3, or using the ethylene-vinyl alcohol copolymer fiber The procedure was performed in the same manner as in Example 1 except that the blending was changed as shown in Table 1 without blending.
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 fibers (1.0 d × 3 mm) used in Comparative Example 4 had a water dissolution temperature of 100
℃ or higher fiber (Kuraray Co., Ltd. “VPB103 ×
3 ") and the CSF of mercerized cotton is 550 m
l.

[0042]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D21H 13/16 D21H 13/16 27/00 27/00 Z F term (Reference) 4L035 DD13 DD19 FF01 FF05 4L045 AA02 AA03 AA05 BA03 BA06 BA20 BA60 4L055 AF39 AF44 AF47 EA04 EA16 FA10 FA16 FA21 FA30 GA50 5H021 BB08 BB13 CC00 CC01 CC02 EE04 EE05 EE11 EE15 HH00

Claims (4)

[Claims] 1. A battery separator paper comprising ethylene-vinyl alcohol copolymer fibers having a single fiber fineness of 0.0001 to 0.5 d in a proportion of 2 to 45% by weight. 2. An ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 0.0001 to 0.5 d is blended in an amount of 2 to 45% by weight, and a polyvinyl alcohol fiber and / or a cellulose fiber is incorporated in an amount of 10 to 98% by weight. Battery separator paper. 3. An ethylene-vinyl alcohol copolymer fiber having a single fiber fineness of 0.0001 to 0.5d obtained by removing a sea component of a sea-island fiber having an ethylene-vinyl alcohol copolymer as an island component. And the compounding ratio of the ethylene-vinyl alcohol copolymer fiber is 2 to 4
A method for producing a separator paper for a battery which is wet-processed so as to have a concentration of 5% by weight. 4. A battery separator using the battery separator paper according to claim 1 or 2.