JPH10214610A - Nonwoven fabric nonaqueous electrolyte cell separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nonwoven fabric for a separator which is excellent in mechanical strength such as tensile strength and can be wound satisfactorily around an electrode by using bacteria cellulose produced by micro-organisms. SOLUTION: Cellulose and others containing heteropolysaccharide with cellulose as its principal chain are used, for instance, as bacteria cellulose produced by micro-organisms. An aqueous slurry is made by dissociating bacteria cellulose produced and stored by incubating the micro-organisms. In addition, heat resistant organic fabric with a fusing point of thermal decomposition temperature of not less than 250C is preferably contained in it. Furthermore, inorganic fabric is preferably contained, and pressure treatment of pressurized thermal treatment is carried out. Since the dissociated substance of bacteria cellulose obtained thereby has a very high combining ability between fabrics, by mixing a small amount with other organic fabric or inorganic fabric, a sheet with good strength can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for a non-aqueous electrolyte battery separator having high mechanical strength, good winding property with an electrode, and excellent battery workability.

[0002]

2. Description of the Related Art Conventionally, as a non-aqueous electrolyte battery separator, for example, JP-A-6-325747 discloses a microporous membrane made of a high molecular weight polyethylene having an intrinsic viscosity [η] of 5 dl / g or more. ing. As a separator for a lithium battery, JP-A-3-105851 discloses
An ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 ⁵ or more, and a weight average molecular weight / number average molecular weight of 10 to 300;
A microporous membrane comprising a composition with polyethylene is disclosed.

[0003] These separators are not only complicated in manufacturing process and high in cost, but also have low mechanical strength such as tensile strength. There has been a problem that the separator is pierced by an object or a bounce, or a crack is formed and torn.

[0004] Separators using nonwoven fabrics have been developed instead of conventional microporous membranes due to ease of production and stability of quality. For example, a separator nonwoven fabric for a battery using a specific fiber is disclosed in JP-A-5-74442,
As disclosed in JP-A-5-335005, when these nonwoven fabrics are used for a separator, the thickness of the nonwoven fabric varies greatly as compared with a microporous membrane, and the adhesion to an electrode constituting a battery is significantly reduced. . Therefore, in the case of a battery, there is a disadvantage that a sufficient volume of electrodes cannot be incorporated, and at present, satisfactory performance cannot be obtained when assembled as a battery. Furthermore, when a battery is manufactured by winding or laminating an electrode and a separator, there are many cases where there is a problem in workability such as disturbing loading into a battery case.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-aqueous electrolyte battery separator non-woven fabric having high mechanical strength, good winding properties with electrodes, and excellent battery workability.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, the use of bacterial cellulose produced by microorganisms has excellent mechanical strength such as tensile strength and the like. The present inventors have found that a nonwoven fabric for a non-aqueous electrolyte battery separator having excellent winding properties and excellent battery processability can be obtained, which has led to the present invention.

[0007] That is, the present invention is a nonwoven fabric for a non-aqueous electrolyte battery separator, which comprises bacterial cellulose produced by a microorganism.

The melting point or the thermal decomposition temperature is 250 ° C.
It is preferable to include the above heat-resistant organic fibers.

Further, it is preferable to include inorganic fibers.

[0010] Further, it is preferable that pressure treatment or pressure heat treatment is performed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the nonwoven fabric for a non-aqueous electrolyte battery separator of the present invention will be described in detail.

The bacterial cellulose produced by the microorganism in the present invention includes those containing cellulose and a heteropolysaccharide having cellulose as a main chain and β-1,3, β-cells.
It contains glucans such as 1, 2 and so on. In the case of the heteropolysaccharide, components other than cellulose include hexoses such as mannose, fructose, galactose, xylose, arabinose, rhamnose, and glucuronic acid, pentoses, and organic acids. These polysaccharides may be composed of a single substance, or may be composed of two or more kinds of polysaccharides bonded by a hydrogen bond or the like, and any of them can be used.

The bacterial cellulose produced by the microorganism in the present invention may be any bacterial cellulose as described above.

The microorganism producing such bacterial cellulose is not particularly limited, but may be Acetobacter acetyl subsp. Xylinum (A
cetobacter aceti subsp. xy
linum) ATCC 10821, A. pasteurian, A. rancence (A. r)
ancens), Sarsina Ventriculi (Sarci)
naventriculi, Bacterium xyloides, Pseudomonas bacteria, Agrobacterium bacteria, etc., which produce bacterial cellulose can be used.

The method for culturing these microorganisms to produce and accumulate bacterial cellulose may be in accordance with a general method for culturing bacteria. That is, inoculate the microorganism into a normal nutrient medium containing organic trace nutrients such as carbon sources, nitrogen sources, inorganic salts, other amino acids, and vitamins as necessary,
Stir or gently ventilate.

Next, the bacterial cellulose produced and accumulated is disaggregated to obtain an aqueous slurry. Disintegration can be easily performed using a rotary disintegrator or a mixer. Since the thus obtained bacterial cellulose disintegration has a very high binding ability between fibers, a strong sheet can be obtained only by mixing a small amount with other organic fibers or inorganic fibers.

The amount of bacterial cellulose in the nonwoven fabric for a non-aqueous electrolyte battery separator in the present invention is not particularly limited, but is preferably 3 to 60% by weight. When the amount is less than 3% by weight, the effect of increasing the strength of the nonwoven fabric is small. On the other hand, if the content is more than 60% by weight, the concentration of bacterial cellulose in the papermaking slurry becomes too high, and the furnace water deteriorates, making it difficult to form a sheet.

The heat-resistant organic fiber used in the present invention means a fiber which does not melt or decompose even at 250 ° C. and shows little deterioration even when stored at 200 ° C. in a high temperature atmosphere for one month or more.

Specifically, a wholly aromatic polyester fiber,
Polyphenylene sulfide fiber, polyether ketone fiber, polyimide fiber, polyether sulfone fiber, wholly aromatic polyamide fiber, polyamide imide fiber, polyether imide fiber, and the like, among these fibers, adversely affect battery characteristics among these fibers. However, from the viewpoint of excellent battery storage characteristics, a wholly aromatic polyester fiber, a polyphenylene sulfide fiber, a polyether ketone fiber, a polyimide fiber, and a polyether sulfone fiber are preferable.

The length of the heat-resistant organic fiber used in the present invention is not particularly limited, but is preferably 1 to 30 mm. If the length of the fibers is less than 1 mm, the fibers are less entangled with each other, and as a result, the strength due to heat fusion is insufficient, which is not preferable. On the other hand, if the length is longer than 30 mm, the fibers are not entangled with each other to form a uniform nonwoven fabric, and not only the thickness variation of the nonwoven fabric increases, but also when used as a nonaqueous electrolyte battery separator, the electric resistance becomes uneven in the width direction. Therefore, it is not preferable.

The fiber diameter is preferably 5 deniers or less, more preferably 0.1 to 3 deniers. If the fiber diameter of the fiber is larger than 5 denier, the thickness of the nonwoven fabric becomes non-uniform, and not only the electric resistance becomes non-uniform, but also a pinhole is easily formed and the strength of the nonwoven fabric is unfavorably reduced.

The inorganic fibers used in the present invention include alumina fibers, alumina-silica fibers, rock wool, glass fibers, micro glass fibers, zirconia fibers, potassium titanate fibers, alumina whiskers, and aluminum borate whiskers.

Alumina fibers are fibers containing alumina (Al ₂ O ₃ ) as a main component. As a method for producing alumina fibers, a spinning solution in which an aqueous solution of an aluminum salt and a water-soluble polysiloxane are mixed is spun, and this is spun in the air for 100 hours.
An inorganic salt method of firing at 0 ° C. or higher, a sol method of spinning and firing alumina sol or silica sol, dry spinning of a solution containing polyaluminoxane and a mixture of silicate ester, and the obtained precursor fiber in air at 1000 Precursor polymer method of firing at a temperature of not less than 0 ° C., dry-spinning of a slurry containing α-Al2O3 fine powder of 0.5 μm or less,
A slurry method in which the particles are fired at a temperature of 000 ° C. or more and further sintered in a gas flame at 1500 ° C. to sinter the crystal particles.

The alumina-silica fiber has an alumina content of 4
It is made of a fiber having a silica content of 0 to 60% and a silica content of 60 to 40%, for example, by the following method. Blowing by adding borate glass, zirconia, chromium oxide, etc. to the alumina / silica raw materials such as kaolin calcined product, bauxite alumina, silica sand, silica stone powder, etc., melting it at high temperature and blowing compressed air or steam jet Fibers are formed by a spinning method using the centrifugal force of a rotor rotating at a high speed.

Rock wool is produced, for example, by the following method. Blast furnace slag is used as a main raw material, and quartzite, dolomite, coal rock, etc. are added to the blast furnace slag, and the mixture is placed in an electric furnace at 1500 to 1600.
The mixture is heated and melted at a temperature of 1100C, and the obtained homogeneous melt is dropped at 1400C on a high-speed rotating body to form fibers.

The micro glass fiber is an ultrafine glass fiber produced by a steam spraying method, a spinning method, a flame insertion method, a rotary method or the like, and has an average fiber diameter of generally 5 μm.
m or less.

These inorganic fibers preferably have a fiber diameter of several μm or less and a fiber length of several tens to several hundreds μm in order to produce a nonwoven fabric for a nonaqueous electrolyte battery separator having a uniform thickness.

The non-woven fabric for a non-aqueous electrolyte battery separator according to the present invention contains organic fibers other than heat-resistant organic fibers,
For example, polypropylene resin, polyethylene resin, polyolefin fiber consisting of polymethylpentene resin,
Polyester fiber, acrylic fiber, fibrous binder and the like may be added as necessary.

As the fibrous binder, a type in which the fibers themselves are partially or wholly melted by heat to generate a binding force between the fibers, and the fibers themselves are partially or wholly dissolved in water or hot water and the fibers themselves are dissolved in the drying process A type that produces binding force on
Further, a type in which a binding force is generated between fibers by entanglement of fine fibers, or the like may be used alone or in combination of two or more depending on the purpose.

Specific examples of these fibrous binders include vinylon fiber, polyester fiber, polypropylene fiber, polyethylene fiber, composite fiber composed of polyethylene and polypropylene, polypropylene and ethylene-
Composite fibers made of a vinyl alcohol copolymer, and polyolefin synthetic pulp, polyamide fiber, natural pulp, and the like produced from a polyolefin resin are preferably used. Polyolefin fibers including vinylon fibers and polypropylene are more preferably used from the viewpoint that the nonwoven fabric has high strength and is excellent in heat resistance and electrolytic solution resistance.

For the purpose of improving the strength, heat resistance, folding resistance and other properties of the non-woven fabric for a non-aqueous electrolyte battery separator, an inorganic binder represented by colloidal silica, colloidal alumina, water glass or the like is applied or impregnated. Such treatment may be applied to the nonwoven fabric for a non-aqueous electrolyte battery separator in the present invention. Further, instead of these inorganic binders, organic binders such as various water-soluble resins, oil-soluble resins, and latexes may be used.

The nonwoven fabric for a non-aqueous electrolyte battery separator of the present invention is preferably subjected to a pressure treatment or a pressure heat treatment.

The reason for this is that by performing the pressure treatment or the pressure heat treatment, the surface smoothness of the nonwoven fabric is improved, and the adhesion to the electrode, the winding property, and the workability of the battery are significantly improved. In particular, the heat treatment under pressure is highly effective because the surface smoothness and mechanical strength of the nonwoven fabric are significantly improved.

Examples of the method of the pressure treatment and the pressure heat treatment include a calendar treatment performed using a calendar such as a super calender, a machine calender, a heat calender, a soft calender, and a heat soft calender.
In particular, pressure heat treatment using a heat calender is preferable.

The treatment temperature in the pressurized heat treatment depends on the type of organic fibers constituting the non-woven fabric for a non-aqueous electrolyte battery separator, and the treatment is performed at a temperature between Tg and melting point of the organic fibers. When fibers are blended, it is necessary to raise the processing temperature to the temperature at which the adhesive force of the heat-fusible fiber is developed.
0-200 ° C is preferred. When the pressure treatment is performed at a temperature lower than 50 ° C., a sufficient adhesive strength is not exhibited, and troubles such as a return of the thickness over time or a failure to reduce the thickness to a desired thickness easily occur. On the other hand, when the pressure treatment is performed at a temperature higher than 200 ° C., the fibers themselves are deteriorated by heat, and the strength is reduced or the fibers are deformed. Even if deterioration does not occur, the density of the nonwoven fabric is too high, and sufficient air permeability cannot be obtained, which impairs battery performance.

The basis weight of the non-aqueous electrolyte battery separator for non-woven fabric of the present invention is not particularly limited but is preferably 5 to 100 g / m ^2, it is used more preferably 10 to 50 g / m ^2.

The thickness of the non-woven fabric for a non-aqueous electrolyte battery separator in the present invention is preferably from 10 to 100 μm.
６０60 μm is more preferable. If the thickness is less than 10 μm,
It is not preferable because the short-circuit failure rate at the time of battery assembly increases.
On the other hand, when the thickness is more than 100 μm, the electric resistance due to the thickness is increased, and the battery characteristics are deteriorated and the energy density is greatly reduced.

The nonwoven fabric for a non-aqueous electrolyte battery separator of the present invention is preferably produced by a wet papermaking method because of its high uniformity in thickness. Examples of the paper machine used in the wet papermaking method include a fourdrinier paper machine, a round paper machine, an inclined paper machine, and a combination machine combining two or more types.

[0039]

EXAMPLES The present invention will be described below in detail with reference to examples, but the contents of the present invention are not limited to the examples.

<Preparation Example of Bacterial Cellulose Disintegration>
Sucrose 5 g / dl, yeast extract 0.5 g / d
l, ammonium sulfate 0.5 g / dl, potassium hydrogen phosphate (KH ₂
PO ₄ ) 0.3 g / dl, magnesium sulfate (MgSO ₄
・ 7H ₂ O) pH 5 medium 5 consisting of 0.05 g / dl
0 ml into a 200 ml Erlenmeyer flask.
Steam sterilization at 20 degrees for 20 minutes. Add yeast extract 0.
Acetobacter, acetyl, subsp., Xylinum ATCC10821 grown on a test tube slope agar medium having a composition of 5 g / dl, peptone 0.3 g / dl, and mannitol 2.5 g / dl (pH 6) were inoculated in a platinum loop at 30 ° C. And cultured. After 30 days, a gel-like film containing white bacterial cellulosic polysaccharide was formed on the upper layer of the culture solution. After washing this gel-like membrane with water, 100 times the dry weight of water was added, and the mixture was treated at 15000 rpm for 10 minutes using an excel auto-homogenizer (manufactured by Nippon Seiki Co., Ltd.) to give a 1% suspension of bacterial cellulose disintegration product. Was prepared.

Example 1 A suspension of the bacterial cellulose disintegration material previously prepared, a core-sheath composite fiber composed of a polypropylene resin and a polyethylene resin (NBF-H manufactured by Daiwa Spinning Co., Ltd., 0.7 d fineness, fiber length 5
mm) was dispersed in water to prepare a slurry. At this time, the mixing ratio of the bacterial cellulose and the core-sheath composite fiber was set to 1
5:85. Subsequently, wet papermaking was performed using a circular paper machine to prepare a non-aqueous electrolyte battery separator nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 80 μm.

Example 2 In the same manner as in Example 1, a nonwoven fabric for a non-aqueous electrolyte battery separator having a basis weight of 20 g / m ² was subjected to wet papermaking, and then subjected to pressure treatment using a super calender to adjust the thickness to 60 μm.

Example 3 A nonwoven fabric for a non-aqueous electrolyte battery separator having a basis weight of 20 g / m ² was subjected to wet papermaking in the same manner as in Example 1 and then subjected to a pressure heat treatment at 100 ° C. using a hot calender to reduce the thickness to 40 μm. It was adjusted.

Example 4 A suspension of the bacterial cellulose disintegration prepared above and a wholly aromatic polyester fiber (Vectran, fineness 2.5 denier, fiber length 5 m, Kuraray Co., Ltd.) as a heat-resistant organic fiber
m) was dispersed in water to prepare a slurry. At this time, the mixing ratio between the bacterial cellulose and the wholly aromatic polyester fiber was set to 20:80. Next, wet papermaking was performed using a circular paper machine to prepare a non-aqueous electrolyte battery separator nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 90 μm.

Example 5 In the same manner as in Example 4, a nonwoven fabric for a nonaqueous electrolyte battery separator having a grammage was made by wet papermaking, and then pressure-treated using a super calender to adjust the thickness to 70 μm.

Example 6 In the same manner as in Example 4, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then heat-treated under pressure at 130 ° C. using a hot calender to adjust the thickness to 50 μm.

Example 7 A suspension of the bacterial cellulose disintegration product prepared above and polyphenylene sulfide fiber (manufactured by Toray Industries, Inc., PPS, fineness 2 denier, fiber length 5 mm) as a heat-resistant organic fiber
Was dispersed in water to prepare a slurry. At this time, the mixing ratio between the bacterial cellulose and the wholly aromatic polyester fiber was set to 10:90. Subsequently, wet papermaking was performed using a circular paper machine to prepare a non-aqueous electrolyte battery separator nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 85 μm.

Example 8 In the same manner as in Example 7, a nonwoven fabric for a nonaqueous electrolyte battery separator having a grammage was subjected to wet papermaking and then subjected to pressure treatment using a super calender to adjust the thickness to 70 μm.

Example 9 In the same manner as in Example 7, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then subjected to a pressure heat treatment at 120 ° C. using a hot calender to adjust the thickness to 50 μm.

Example 10 A suspension of the previously prepared bacterial cellulose disintegration, alumina fiber (Safir RF, manufactured by ICI), polyester fiber (# 4080, manufactured by Unitika, 2 denier fineness)
A slurry having a fiber length of 5 mm) dispersed in water was prepared. At this time, bacterial cellulose, alumina fiber,
The mixing ratio of the polyester fibers was set to 20:50:30.
Next, wet papermaking was performed using a circular paper machine, and the basis weight was 25 g / m ² ,
A nonwoven fabric for a non-aqueous electrolyte battery separator having a thickness of 108 μm was prepared.

Example 11 In the same manner as in Example 10, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then pressure-treated using a super calender to adjust the thickness to 90 μm.

Example 12 In the same manner as in Example 10, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking and then heat-treated under pressure at 130 ° C. using a hot calender to adjust its thickness to 60 μm.

Example 13 A suspension of the bacterial cellulose disintegration prepared above, micro glass fiber (manufactured by Schuller, # 110)
Was dispersed in water to prepare a slurry. At this time, the mixing ratio of bacterial cellulose and micro glass fiber was 4
0:60. Subsequently, wet papermaking was performed using a circular paper machine to prepare a non-aqueous electrolyte battery separator nonwoven fabric having a basis weight of 20 g / m ² and a thickness of 85 μm.

Example 14 In the same manner as in Example 13, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then pressure-treated using a super calender to adjust the thickness to 70 μm.

Example 15 A nonwoven fabric for a nonaqueous electrolyte battery separator having a grammage was wet-paper-formed in the same manner as in Example 13, and then heat-treated under pressure at 100 ° C. using a hot calender to adjust the thickness to 50 μm.

Example 16 A suspension of bacterial cellulose disintegration prepared above, a core-sheath composite fiber composed of a polypropylene resin and a polyethylene resin (manufactured by Daiwa Spinning Co., Ltd., NBF-H, fineness 0.7 denier, fiber length 5 mm) , Wholly aromatic polyester fiber (Kuraray Co., Vectran, fineness 2.5 denier, fiber length 5 m
m), micro glass fiber (manufactured by Schuller, #
110) was dispersed in water to prepare a slurry. At this time, the mixing ratio of bacterial cellulose, core-sheath conjugate fiber, wholly aromatic polyester, and micro glass fiber was 20: 2.
0:30:30. Subsequently, wet papermaking was performed using a circular paper machine to prepare a non-aqueous electrolyte battery separator nonwoven fabric having a basis weight of 25 g / m ² and a thickness of 104 μm.

Example 17 In the same manner as in Example 16, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then subjected to a pressure treatment using a super calender to adjust the thickness to 80 μm.

Example 18 In the same manner as in Example 16, a nonwoven fabric for a nonaqueous electrolyte battery separator having a basis weight was made by wet papermaking, and then subjected to a pressure heat treatment at 100 ° C. using a hot calender to adjust the thickness to 50 μm.

Comparative Example 1 A slurry in which 100% of the core-sheath conjugate fiber used in Example 1 was dispersed in water was prepared, and wet-laid using a circular paper machine, and had a basis weight of 20 g / m ² and a thickness of 90 μm. A non-woven fabric for a non-aqueous electrolyte battery separator was produced.

Comparative Example 2 A slurry in which 100% of the wholly aromatic polyester fiber used in Example 4 was dispersed in water was prepared, and wet-laid using a circular paper machine to obtain a basis weight of 20 g / m ² and a thickness of 100 μm. Of non-aqueous electrolyte battery separators was prepared.

Comparative Example 3 A slurry in which 100% of the alumina fiber used in Example 10 was dispersed in water was prepared, and wet papermaking was attempted using a circular paper machine, but the alumina fiber had no self-binding force. Therefore, the mechanical strength of the nonwoven fabric for a non-aqueous electrolyte battery separator was remarkably weak.

The above Examples 1 to 18 and Comparative Examples 1 to 3
The nonwoven fabric for a non-aqueous electrolyte battery separator obtained by the above was measured by the following test method, and the results are shown in Table 1 below. In addition, what could not be measured was marked with "-".

<Tensile strength> The tensile strength was measured using a Tensilon tester in accordance with the method specified in JIS-P8116. The sample width was 20 mm. The unit is Kg / 20m
m.

<Pinhole> It was visually evaluated whether or not the nonwoven fabric for a nonaqueous electrolyte battery separator prepared in Examples and Comparative Examples had through holes. The case where there was no through-hole was defined, and the case where there was a through-hole.

<Battery processability> The nonwoven fabric for a nonaqueous electrolyte battery separator prepared in Examples and Comparative Examples using lithium cobaltate as a positive electrode active material and graphitized carbon as a negative electrode was used as a nonaqueous electrolyte battery separator. This was arranged so as to be in contact with each electrode, and the whole was an electrode having a spiral structure. Next, LiClO ₄ was dissolved in a mixed solvent of ethylene carbonate: diethyl carbonate = 1: 1 so as to have a concentration of 0.5 M / l to prepare an electrolytic solution. Using these electrodes and electrolyte, 18650 type (18 mm diameter,
(Length: 65 mm) A cylindrical lithium battery was produced. At this time, the non-uniformity, gap, meandering, shift, and breakage between the electrode and the separator were examined and evaluated for battery workability. ◎: Uniformly manufactured without any gap, meandering, misalignment, or breakage and processed without any problem. ◎ Rarely, meandering or misaligned, but processed without any problem, ○. Those that were present were rated as △, and those that were difficult to work due to problems in workability were rated as x.

<Heat Resistance> The nonwoven fabric for a non-aqueous electrolyte battery separator prepared in Examples and Comparative Examples was sandwiched between metal plates from above and below, and connected to an electric resistance measuring device so that electric resistance could be measured. The nonwoven fabric sandwiched between the metal plates was placed in an electric furnace, heated to 500 ° C., and the temperature and the electric resistance were measured. As the temperature rises, the nonwoven fabric shrinks, melts,
If it does not serve as a separator due to combustion or the like, the electric resistance decreases, and eventually a short circuit occurs. By measuring the temperature at which this short circuit occurs, the heat resistance was measured. When the temperature is 180 ° C. or higher, the heat resistance is good, and when the temperature is 120 to 180 ° C., the temperature is slightly poor but within the practicable range. If it is lower than 120 ° C., it is defective. When no short circuit occurred up to 500 ° C., “500 <” is described in the table.

[0067]

[Table 1]

Evaluation: As is evident from the results in Table 1, the nonwoven fabric for a nonaqueous electrolyte battery separator prepared in Examples 1 to 18 of the present invention contains bacterial cellulose produced by microorganisms, and thus has a pinhole. And had high mechanical strength and excellent battery workability.

Among them, those subjected to the pressure treatment improved the workability of the battery due to the effect of reducing the thickness and the effect of improving the surface smoothness, and those subjected to the heat treatment under pressure improved the effect and the mechanical strength. Battery workability was improved.

The nonwoven fabric for a non-aqueous electrolyte battery separator prepared in Examples 10 to 12 contained hard and brittle alumina fibers, and thus was slightly inferior in battery workability.

The nonwoven fabric for a non-aqueous electrolyte battery separator produced in Examples 4 to 18 was excellent in heat resistance because it contained heat-resistant organic fibers or inorganic fibers.

On the other hand, the nonwoven fabrics for nonaqueous electrolyte battery separators prepared in Comparative Examples 1 to 3 did not contain bacterial cellulose, and therefore had low mechanical strength, and were displaced or broken, resulting in poor battery workability.

The nonwoven fabric for a non-aqueous electrolyte battery separator prepared in Comparative Examples 1 and 2 did not contain any bacterial cellulose and consisted only of fibers having a large fiber diameter, so that pinholes were formed.

The non-woven fabric for a non-aqueous electrolyte battery separator prepared in Comparative Example 3 was made of only alumina fibers having no self-binding force, and therefore had extremely low mechanical strength. there were.

[0075]

The nonwoven fabric for a non-aqueous electrolyte battery separator of the present invention has a high mechanical strength and a good winding property with an electrode, so that a battery excellent in battery processability can be manufactured. It can be seen that when heat-resistant organic fibers having a melting point or thermal decomposition temperature of 250 ° C. or higher are added and when inorganic fibers are added, heat resistance is also excellent. When the pressure treatment or the pressure heat treatment is performed, the surface smoothness and mechanical strength of the nonwoven fabric are improved, so that the nonwoven fabric is further excellent in battery processability.

Claims (4)

[Claims] 1. A non-woven fabric for a non-aqueous electrolyte battery separator, comprising bacterial cellulose produced by a microorganism. 2. The nonwoven fabric for a non-aqueous electrolyte battery separator according to claim 1, further comprising a heat-resistant organic fiber having a melting point or a thermal decomposition temperature of 250 ° C. or higher. 3. The nonwoven fabric for a non-aqueous electrolyte battery separator according to claim 1, wherein the nonwoven fabric contains inorganic fibers. 4. The nonwoven fabric for a non-aqueous electrolyte battery separator according to claim 1, wherein the nonwoven fabric is subjected to a pressure treatment or a pressure heat treatment.