JP3277186B2 - Fiber sheet material and battery separator using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery separator.

[0002]

2. Description of the Related Art Fibers containing a styrenic polymer have a benzene ring, which is a side chain of the styrenic polymer, having a high reactivity, so that a sulfonic group is introduced into the benzene ring and the hydrophilicity of the benzene ring is utilized. It has been proposed to use it for applications such as battery separators. However, fibers containing a styrene-based polymer are brittle and have no elongation, so that it is difficult to process them into a fiber sheet, and the versatility is poor.

In an alkaline battery, a separator is used to separate a positive electrode and a negative electrode to prevent a short circuit.
As the separator, it is necessary that the separator is not affected by an electrolytic solution such as potassium hydroxide and has excellent retention of the electrolytic solution so that the electromotive reaction can be performed smoothly. Have been used. However, since polyolefin fibers are hardly sulfonated, the retention of the electrolyte was insufficient. Therefore, there has been proposed a separator obtained by sulfonating fibers obtained by mixing polystyrene, which is one kind of polyolefin-based fibers, with polyolefin (Japanese Patent Laid-Open Publication No. Hei.
No. 174964), however, since the fiber is given a fiber strength by polyolefin, the more polyolefin, the more difficult it is to sulfonate. Conversely, the more polystyrene, the more the polystyrene, the lower the fiber strength. It was difficult to process it.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a battery separator containing a fiber containing a specific styrene-based polymer. .

[0005]

A battery separator according to the present invention.
Others, have a syndiotactic structure, the glass transition temperature
Contains a modified styrenic polymer component whose temperature has decreased by 5 ° C. or more and has an elongation of 60 to 200%, and / or
Or have a syndiotactic structure, glass transition temperature
Contains a modified styrenic polymer component reduced by 5 ° C. or more ,
A battery separator comprising a drawn fiber having an elongation of 20 to 150% , wherein at least
Styrene-based polymer component is sulfonated
is there.

The battery separator according to the present invention is characterized in that the styrene-based polymer component having a syndiotactic structure is a modified styrene-based polymer component having a glass transition temperature lowered by 5 ° C. or more.
Wherein at least the modified styrenic polymer component is
Since it is made into rufone, it has excellent electrolyte retention
Separator.

Further, it is the unstretched fibers and / or drawn fiber is not divided Runode, battery separator having excellent retention of electrolyte.

[0008]

SUMMARY OF The battery separator of the present invention have a syndiotactic structure, modified <br/> styrenic polymer component having a reduced glass transition temperature of 5 ° C. or higher (hereinafter, unless otherwise specified, "styrenic polymer "contains a to) as having a syndiotactic structure, possess undrawn fiber having elongation 60 to 200% and / or a syndiotactic structure,
A battery separator comprising a stretched fiber having a modified styrenic polymer component having a glass transition temperature lowered by 5 ° C. or more and having an elongation of 20 to 150% , wherein at least
Styrene-based polymer component is sulfonated
is there. Since the fibers have elongation, a fiber sheet can be obtained, and the obtained fiber sheet also has excellent workability.

Hereinafter, the battery separator of the present invention will be described in more detail.

The undrawn fiber or drawn fiber of the present invention contains a styrene polymer component having a syndiotactic structure, which has excellent fiber strength and is easily fiberized. The syndiotactic structure refers to a structure having stereoregularity in which benzene rings and substituted benzene rings, which are side chains, are alternately located in opposite directions with respect to the main chain. And 13C-NMR spectrum for easy analysis.

The undrawn fiber or drawn fiber of the present invention preferably contains a styrenic polymer component having a high syndiotactic structure.
Analyzed by C-NMR spectrum, those having a syndiotacticity of at least 75%, more preferably at least 85%, and at least 30%, more preferably at least 50%, of racemic pentads are preferred. .

The styrenic polymer component of the present invention includes:
For example, polyalkylstyrene such as polystyrene, polymethylstyrene, polyethylstyrene, and polyisopropylstyrene; polyhalogenated styrene such as polychlorostyrene, polybromostyrene, and polyfluorostyrene; and polyhalogen such as polychloromethylstyrene There are polyalkoxystyrenes such as alkylated styrene, polymethoxystyrene, polyethoxystyrene, and polyvinyl benzoate. These can be used alone or in combination, and can be used by hydrogenation polymerization or copolymerization. Among these, polystyrene, polyalkylstyrene, hydrogenated polystyrene, and copolymers containing these structural units can be preferably used, and among these, polystyrene is most preferred.

The weight average molecular weight of the styrene polymer component is preferably from 1 to 4,000,000. If it is less than 10,000, the fiber-forming property is poor, and if it exceeds 4,000,000, the viscosity is high,
Due to poor spinnability, more preferably 50,000 to 800,000,
Most preferably, it is 100,000 to 300,000.

[0014] with respect to the styrene polymer component, for example, adding a plasticizer, copolymerizing other molecules, or by a method such as introduction of other functional groups in the side chain, a glass transition temperature of 5 ℃ reduced more, the benzene ring of the modified styrenic polymer component is easier to chemical modification (hereinafter, JP
Unless otherwise stated, "modified styrenic polymer"
A modified styrene-based polymer whose transfer temperature has been lowered by 5 ° C. or more;
Do) . On the other hand, the properties of the modified styrenic polymer component whose glass transition temperature has dropped below 30 ° C. are remarkably reduced. Therefore, it is preferable to suppress the drop of the glass transition temperature to 30 ° C. or lower. More preferably, the temperature is lowered by 5 to 20 ° C.
For example, if the styrenic polymer component has a glass transition temperature of 100
In the case of polystyrene of about ° C, the glass transition temperature is 7
Modified polystyrene reduced to 0 to 95 ° C, more preferably modified polystyrene reduced to 80 to 95 ° C.

Among these methods for lowering the glass transition temperature, the method of adding a plasticizer is a preferable method because the physical properties of the styrene-based polymer component hardly deteriorate and the operation is simple. Examples of the plasticizer include alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, and 1,5 pentanediol, hydrobenzoin,
Aromatic glycols such as benzpicol, carbocyclic glycols such as cyclopentane 1,2-diol, cyclohexane 1,2-diol, phthalic esters such as dimethyl phthalate and diethyl phthalate, di-2 adipate
Aliphatic dibasic acid esters such as -ethylhexyl and di-n-decyl adipate; and phosphoric acid esters such as tributyl phosphate and tri-2-ethylhexyl phosphate. Among these, alkylene glycol is preferably used because of good compatibility with the styrene-based polymer component and high plasticization efficiency, and among these, ethylene glycol is most preferably used.

The amount of the plasticizer to be added is not particularly limited, and may be appropriately set so that the decrease in the glass transition temperature is 5 to 30 ° C. For example, 0.5 to 10% by weight, more preferably 1 to 6% by weight, of ethylene glycol is added to polystyrene.

The unstretched fibers or stretched fibers of the present invention may comprise only the modified scan <br/> styrene polymer component but, when mixed with other polymer components, modified styrene-based weight In order to utilize the properties of the coalesced component, the modified styrene polymer component is preferably contained in an amount of 20% by weight or more, more preferably 40% by weight or more. Since chemical modification of the benzene ring of the modified styrenic polymer component, for ease of chemical modification, preferably accounts for more than 40% of the fiber surface.

The polymer component other than the modified styrenic polymer component may be any of thermoplastic and fiber-forming components, such as polyethylene, polypropylene, and the like.
Polyolefins such as polystyrene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-butene-propylene copolymer, 6-nylon,
Nylon such as 66-nylon and polyester such as polyethylene terephthalate and polybutylene terephthalate can be used. As the fibers for the alkaline battery separator, polyolefins having excellent alkali resistance can be preferably used, and among them, polypropylene can be most preferably used.

The arrangement of the modified styrenic polymer component and other polymer components may be, for example, a lotus root or three-dimensional network obtained by mixing and spinning the modified styrenic polymer and other polymer components. etc. and those modified styrenic polymer component, or other polymer components arranged in Jo, a modified styrene polymer with other polymer component obtained by conjugate spinning, the fiber cross section, concentric or eccentric shape Core-sheath type, sea-island type,
Alternatively, as shown in FIGS. 1 (a) to 1 (d), a chrysanthemum flower type in which one component 1 is arranged between other components 2, as shown in FIG.
There is a multilayer type in which one component 1 and another component 2 are alternately laminated in two or more layers. A mixture spinning the former is excellent in fiber strength, the benzene ring tends to chemical modification of the modified styrenic polymer component, there is a feature that the latter those composite spinning, the modified styrenic polymer component fiber surface Benzene ring of the modified styrenic polymer component is easily chemically modified. Among the latter composite spinning, concentric or eccentric core-sheath type and sea-island type can be suitably used because the entire fiber surface can be a modified styrene-based polymer component. .

When an undrawn fiber or drawn fiber having a chrysanthemum flower type or multi-layered fiber cross section can be divided, it is divided into fine fibers to increase the surface area and to obtain a fiber having a more dense structure. Since it can be formed into a sheet-like material, when used as a battery separator, it can be suitably used because it is more excellent in retention of an electrolytic solution and can prevent a short circuit.

The undrawn fiber of the present invention comprises a resin component containing a modified styrenic polymer component and a spinning temperature of 300 to 40.
It can be obtained by melt spinning at 0 ° C. and a draft ratio of 20 to 160. If the spinning temperature is less than 300 ° C., the elongation of the obtained undrawn fiber is less than 60%, so that the processability is poor. If the spinning temperature exceeds 400 ° C., the decomposition of the modified styrene polymer component becomes remarkable. That's why. More preferred spinning temperatures are 310-360 ° C, most preferably 315 ° C.
３５０350 ° C.

If the draft ratio is less than 20, or more than 160, undrawn fibers having an elongation of 60% or more cannot be obtained even when spinning at the above-mentioned temperature, the preferred draft ratio is 20 to 160. More preferably, it is 30 to 140.

The unstretched fiber is given an orientation,
Cooling is preferred in order to have an elongation of at least%. However, if it is cooled immediately after spinning, the elongation is 60%.
Since it is difficult to obtain the above undrawn fibers and the fibers are easily broken and the spinnability deteriorates, it is preferable to cool at a point 3 mm or more away from the end of the extrusion port of the extrusion nozzle.

The spinning conditions other than these conditions are not particularly limited.
It is 1 to 0.5 mm, more preferably 0.2 to 0.4 mm.

The undrawn fiber obtained in this way is 6
Since it has an elongation of 0 to 200%, it has excellent workability. The fiber cross-sectional shape may be a polygonal shape such as a triangle, a quadrangle, or a hexagon, an ellipse, an ellipse, or the like in addition to a circle, and is not particularly limited.

The elongation of the fiber in the present invention is determined by Tensilon (UTM-III-10 manufactured by Toyo Baldwin Co., Ltd.).
Using a 1 kg cell at 0), the fiber is pulled until the fiber breaks under the conditions of a measured length of the fiber (between chucks) of 20 mm and a pulling speed of 20 mm / min. From the length before pulling and the length at break, It is determined by the following equation. This measurement was performed at a temperature of 25 ° C.
Perform in.

The drawn fiber of the present invention can be obtained by drawing the undrawn fiber obtained as described above.
It has an elongation of 50% and is excellent in strength. If the elongation of the drawn fiber is less than 20%, it is brittle and the workability is poor.
This is because there is no strength. More preferred elongation is 20 to 10
0%.

This stretching may be appropriately set so that the stretched fiber falls within the above range, but is generally 1.3 to 3.0.
It is preferable to perform double stretching. If the ratio is less than 1.3 times, the strength is not so improved despite the stretching, and if it exceeds 3.0 times, the fiber is easily broken and the stretched fiber obtained has no elongation. More preferably, 1.4 to 2.
5 times. This stretching can be performed at room temperature, but can be performed stably at a temperature of 80 to 200 ° C. without sticking of the fibers.

Note that, since the crystal orientation is generated by stretching, the birefringence changes, and by measuring this value, it is possible to distinguish between a drawn fiber and an undrawn fiber.

The fiber diameter of these undrawn fibers and drawn fibers is as follows:
The thickness is preferably 18 μm or less, more preferably 7 μm or less, so as to have excellent retention of the electrolyte and prevent short-circuiting due to the deposition of dendritic metals and the movement of the electrode active material. When the undrawn fiber or drawn fiber has an irregular cross section, the value converted into a circular cross section is defined as the fiber diameter. Also,
When undrawn fibers or drawn fibers have splitting properties,
The fiber diameter after division may be within the above range.

Although the fiber length is not particularly limited, it is appropriately set according to the method of forming the fiber sheet. For example, when the nonwoven fabric is formed by a wet method, the thickness is preferably 3 to 30 mm. When the nonwoven fabric is formed by a dry method such as a card method or an air lay method,
It is preferably from 20 to 110 mm.

The unstretched fiber and / or the fiber sheet containing the stretched fiber as described above is formed. However, since the unstretched fiber and the stretched fiber have excellent elongation, they are not broken, Or a knit or a nonwoven fabric. The battery separator has a large number of three-dimensional space, it is preferable excellent nonwoven retention of the electrolytic solution.

The content of the undrawn fiber and the drawn fiber is as follows:
In order to utilize the properties of these fibers, the content is preferably 20% by weight or more, more preferably 40% by weight or more, in the fiber sheet.

The non-stretched fiber and the fiber other than the stretched fiber include nylon resins such as 6-nylon and 66-nylon, ethylene-vinyl alcohol copolymer, and the like.
Polypropylene resin such as polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-butene-propylene copolymer alone, or in fiber cross section, concentric or eccentric core-sheath type Alternatively, as shown in FIGS. 1A to 1D, a chrysanthemum flower type in which one component 1 is arranged between other components 2, FIG.
As shown in (e), one component 1 and another component 2 are alternately 2
Fibers combined in a multi-layer type laminated in layers or more can be used. As the battery separator, a fiber containing a polyolefin-based resin having excellent alkali resistance and oxidation resistance can be preferably used, and a fiber containing polypropylene, polyethylene, and polymethylpentene has excellent fiber strength. it can.

If the heat-fusible fibers are contained as fibers other than the undrawn fibers and the drawn fibers, the fibers are fused with the heat-fusible fibers to improve the shape stability of the fibrous sheet. Therefore, it can be used more preferably.

As a method for forming the fiber web (before the entanglement or bonding of the nonwoven fabric), for example, there are a dry method such as a card method and an air-lay method, a wet method, and among these methods.
Since the fiber web obtained by the wet method is dense and has a uniform surface state, when used as a battery separator, precipitation of dendritic metal and migration of the electrode active material can be prevented. It is a forming method.

When a fiber web is formed by the card method, if the fibers include fibers whose orientation directions intersect with each other, the difference in strength between the vertical direction and the horizontal direction is small, so this is a preferable method for forming a fiber web.

As a method of forming a nonwoven fabric from such a fiber web, for example, a method of entanglement of the fiber web by the action of a water stream or a needle, a method of fusing and bonding heat-fusible components of fibers, There are methods such as binding with a binder, and these methods can be used alone or in combination.

In the battery separator of the present invention, the method of entanglement by the action of a water stream is closely entangled to form fine voids, so that it has excellent electrolyte solution retention properties, and furthermore has an oil agent or a surfactant. Since sulfonation can be efficiently performed when sulfonation is performed after forming a fibrous sheet-like material, the method is suitable for forming a nonwoven fabric. In addition, when the above-described splittable fibers are included, the splitting can be performed by a water flow, and therefore, there is an advantage in manufacturing.

As a method of entanglement by the water flow, for example, a nozzle diameter of 0.05 to 0.3 mm, more preferably a nozzle diameter of 0.5 to 0.3 mm.
Nozzle plates with 10 to 0.18 mm, pitch 0.2 to 3 mm, more preferably 0.4 to 1.2 mm arranged in a single row, or nozzle plates with nozzles arranged in two or more rows, such as a grid or staggered And treating from one side or both sides of the fiber web with a water flow at a water pressure of 10 to 300 kg / cm2.

In addition, it has a dense structure and prevents short-circuiting due to the deposition of dendritic metal and the movement of the electrode active material.
When treating with a water stream, it is preferable to use a fine net of 50 mesh or more or a perforated plate having a hole area of 0.06 mm2 or less as a support.

The battery separator obtained as described above preferably has a thickness of 0.05 to 0.3 mm. 0.05m
If it is less than 0.3 m, the retention of the electrolyte tends to decrease, and
If it exceeds mm, it becomes impossible to fill a large amount of the active material. A more preferred thickness is from 0.06 to 0.25 mm.

The battery separator obtained as described above.
In data, the benzene ring of the undrawn fiber and drawn fiber is chemically modified. In addition, the chemical modification of undrawn fiber and drawn fiber
Although it may be before the formation of the fibrous sheet, it is easier to handle after formation.

The battery separator according to the present invention comprises fuming sulfuric acid,
Sulfonation with chlorosulfuric acid, sulfuryl chloride, concentrated sulfuric acid, etc.
And excellent in hydrophilicity and excellent in retention of the electrolytic solution.

The above-mentioned modified styrenic polymer component having a lowered glass transition temperature can be easily and sufficiently sulfonated with concentrated sulfuric acid. can be done, Ru can be excellent in hydrophilicity. More specifically, the concentration of sulfur introduced by sulfonation with concentrated sulfuric acid is 5p
When sulfonating to pm, the glass transition temperature is 10
For a fiber made of polystyrene at about 0 ° C. and a fiber made of modified polystyrene having a glass transition temperature of about 90 ° C., sulfonation of the modified polystyrene fiber can be performed in about half the time as sulfonation of the polystyrene fiber. A modified polystyrene fiber having a glass transition temperature of about 90 ° C. can be sulfonated to a sulfur concentration of 270 ppm, which cannot be obtained by conventional sulfonation with concentrated sulfuric acid.

The concentration of sulfur introduced by sulfonation was determined by measuring the absorption liquid obtained by absorbing easily sulfonated fibers by the oxyfuel flask method using an ion chromatography apparatus (D).
It refers to the sulfur concentration obtained by analysis using IONEX, 2000i / SP).

Further, a fibrous sheet-like material mainly composed of a fiber in which a resin component such as a polyolefin hardly sulfonated and a modified styrene-based polymer component are exposed on the surface of an undrawn fiber or a drawn fiber, or a polyolefin Sheet made from a mixture of fibers mainly composed of resin and fibers mainly composed of a modified styrene-based polymer component. Since it has inferior parts, it has excellent electrolyte retention in parts with excellent hydrophilicity and excellent gas permeability in parts with inferior hydrophilicity, so it is suitable for use as a sealed battery separator. it can. In addition, when the unstretched fiber or the stretched fiber is splittable, in addition to the effect of gas permeability,
Since a dense structure can be formed and the electrolyte solution is more excellent in holding properties, it can be suitably used.

[0048] Thus, sulfonated fibrous sheet is excellent in hydrophilicity can be used as a separator for primary or secondary batteries. The battery may be open or closed, and may be cylindrical, flat, or square. More specifically, alkaline manganese batteries, mercury batteries, silver oxide batteries,
Primary batteries such as air batteries, nickel-cadmium batteries,
It can be suitably used as a separator of a secondary battery such as a silver-zinc battery, a silver-cadmium battery, a nickel-zinc battery, and a nickel-hydrogen battery.

The battery separator of the present invention has been described above.
Was.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. The resin had a melt viscosity of 320 ° C. and a shear rate of 10 ³ S ⁻¹ .
The measurement was performed using a 0 mm nozzle.

The liquid holding ratio under pressure is the electrolyte holding ratio at the time of pressurization and was measured as follows. That is, after the separator cut to a diameter of 30 mm was brought to equilibrium with water at a temperature of 20 ° C. and a relative humidity of 65%, the weight (W ₀ , mg) was obtained.
Was measured. Next, the separator was immersed in a potassium hydroxide solution having a specific gravity of 1.3 (20 ° C.) for one hour so that the air in the separator was replaced with the potassium hydroxide solution, thereby keeping the potassium hydroxide solution. Next, the separator was sandwiched between three filter papers (No. 2, 30 mm in diameter), and a pressure of 21 kgf / cm ² was applied for 30 seconds by a pressure pump, and then the weight of the separator (W ₁ , mg) ) Was measured. Then, the pressurized liquid holding ratio was determined by the following equation. In addition, this measurement was performed four times for one separator, and the average was defined as the liquid holding ratio under pressure.

[0052]

EXAMPLES Reference Example 1 Only polystyrene having a syndiotactic structure (manufactured by Idemitsu Petrochemical Co., Ltd.) having a melt viscosity of 430 poise, a weight average molecular weight of 170,000 and a glass transition temperature of 100 ° C., having a diameter of 0.2 was used.
From an extrusion nozzle of 5 mm and a temperature of 320 ° C., 0.14 g /
Min. And wound at a speed of 210 m / min. With a draft ratio of 66 while cooling with air over 10 cm below a point 5 mm away from the end of the extrusion port of the extrusion nozzle. Circular cross section, fiber diameter 15.4 μm, elongation An undrawn fiber having a degree of 135% was obtained.

The undrawn fiber was drawn twice at 120 ° C. to obtain a drawn fiber having a fiber diameter of 10.9 μm and an elongation of 29%. The drawn fiber was bundled so as to have a denier of 10,000, crimped with a crimper having a nip roll width of 5 mm, and then cut into a length of 50 mm.

Next, a concentric core-sheath type composite fiber composed of 70% by weight of the drawn fiber and polypropylene (core) -polyethylene (sheath) (fiber diameter 20 μm, fiber length 51 m)
m, a sheath component fusing temperature of 110 ° C.), 30% by weight, and carding, and a fiber web is formed by crossing the fiber orientation directions with a cross layer.
℃, 80kg / cm linear pressure calendering, 6
A non-woven fabric having a thickness of 5 g / m ² and a thickness of 0.2 mm was obtained. Then
This nonwoven fabric was immersed in a 97% sulfuric acid solution at 80 ° C. for 20 minutes, washed with water, dried at 60 ° C., the sulfur concentration introduced by sulfonation was 4.0 ppm, and the pressure retention rate was 8.5%.
Was obtained.

Example 1 To 96 parts of polystyrene having a syndiotactic structure (manufactured by Idemitsu Petrochemical Co.) of Reference Example 1 , 4 parts of polyethylene glycol was added as a plasticizer, and the glass transition temperature was 90 ° C. In the same manner as in Reference Example 1 except that the unstretched fiber had a circular cross section, a fiber diameter of 15.4 μm, and an elongation of 110%.

The unstretched fiber was treated at room temperature (25 ° C.) for 1.5 hours.
After drawing twice, it was cut to obtain a drawn fiber having a fiber diameter of 12.5 μm, a fiber length of 10 mm, and an elongation of 50%. Next, a core-sheath type composite fiber (fiber diameter: 20 μm, fiber length: 15 m) composed of the drawn fiber, 70% by weight and the same resin component as in Reference Example 1
m) After forming a fiber web by wet method with 30% by weight, the fiber web is placed on a 80-mesh plain woven net, and the water pressure is adjusted using a nozzle plate having a nozzle diameter of 0.13 mm and a pitch of 0.6 mm. With a water flow of 130 kg / cm ² ,
After treating each side twice, the fiber web was entangled to obtain an entangled fiber web. The same calender treatment and sulfonation treatment as in Reference Example 1 were performed to obtain a basis weight of 67 g / m ² and a thickness of 0.2 mm. , Sulfur concentration introduced by sulfonation 9.3
ppm, and a liquid retaining ratio under pressure of 13.1% was obtained.

(Example 2 ) Modified polystyrene having the same glass transition temperature of 90 ° C as in Example 1 and polypropylene having a melt viscosity of 270 poise were separately melted at a weight ratio of 1: 1. 0.3 cross section, divided into eight small holes by eight grooves
mm, the melt of polypropylene was discharged from the small holes of the extrusion nozzle heated to 320 ° C., and the melt of modified polystyrene was discharged from the groove at 0.07 g / min. Winded at a speed of 210 m / min and a draft ratio of 87 while cooling with air over 10 cm below from the point where it was made, having a circular cross section and a fiber diameter of 16.1 μm.
m, an undrawn fiber having an elongation of 130% was obtained.

The undrawn fiber was drawn and cut twice on a heater at 120 ° C. to obtain a fiber diameter of 11.4 μm and a fiber length of 10
A drawn fiber (see FIG. 1 (a)) having an elongation of 25% was obtained. In this drawn fiber, the modified polystyrene is divided into eight portions by polypropylene extending from the center of the drawn fiber, the modified polystyrene occupies 47.8% of the fiber surface, and is mechanically dividable. The fiber diameter was 2.9 μm for polypropylene and 2.8 μm for modified polystyrene.

Next, 70% by weight of the drawn fiber was added to
Using the same core-sheath type composite fiber 30 wt% 1, Example
In the same manner 1 performs fiber web forming, hydroentangling, calendering, and the sulfonation treatment, basis weight 65g
/ M ² , a thickness of 0.2 mm, a concentration of sulfur introduced by sulfonation of 9.6 ppm, and a liquid retention under pressure of 14.5%.

(Comparative Example 1) Only polystyrene having an atactic structure having a melt viscosity of 130 poise and a glass transition temperature of 100 ° C (manufactured by Asahi Kasei Kogyo Co., Ltd.) was used, and was wound at a draft ratio of 66 at 200 m / min. Except that, in the same manner as in Reference Example 1 , the cross section was circular, the fineness was 15.4 μm, and the elongation was 6.3%.
Was obtained. After that, the undrawn fiber is
An attempt was made to draw twice on a heater at ℃, but the film could not be stably drawn, such as sticking to the heater, and a drawn fiber could not be obtained, so that a separator could not be obtained.

[0061]

The battery separator of the present invention exhibits have a syndiotactic configuration, decrease the glass transition temperature of 5 ° C. or higher
Containing a modified styrenic polymer component, 60-200%
Discoloration of possess undrawn fiber having elongation, and / or a syndiotactic structure, was reduced glass transition temperature of 5 ° C. or higher
A battery separator comprising a stretched fiber containing a conductive styrenic polymer component and having an elongation of 20 to 150% ,
At least the modified styrenic polymer component is sulfonated
Is what is being done. Since the fibers have elongation, a fiber sheet can be obtained, and the obtained fiber sheet also has excellent workability.

The battery separator of the present invention can be used without breaking during production or use.

The modified styrene polymer component having at least a syndiotactic structure and a glass transition temperature lowered by 5 ° C. or more is sulfonated, so that the battery separator is excellent in electrolyte solution retention.

When the unstretched fiber and / or the stretched fiber are divided, a fiber sheet having a small fiber diameter and a dense structure is obtained. Separator.

[Brief description of the drawings]

FIG. 1A is an example of a cross-sectional view of an undrawn fiber. FIG. 1B is another example of a cross-sectional view of an undrawn fiber. FIG. Example (e) Another example of a cross-sectional view of an undrawn fiber

[Explanation of symbols]

 1 One component 2 Other component

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D04H 1/00-18/00 D01F 8/00-8/18 H01M 2/16

Claims (2)

(57) [Claims] [Claim 1] have a syndiotactic structure, glass
An undrawn fiber containing a modified styrenic polymer component having a transition temperature lowered by 5 ° C. or more and having an elongation of 60 to 200%;
And / or have a syndiotactic structure, the glass transition
An electrode containing a drawn fiber having a modified styrenic polymer component whose temperature has dropped by 5 ° C. or more and having an elongation of 20 to 150%.
A pond separator, wherein at least the modified styrene
Separation for battery with sulfonated polymer component
Ta. 2. An undrawn fiber and / or a drawn fiber is divided.
The battery separator according to claim 1, wherein
Ta.