JP2001076703A - Introducing method of sulfur-containing functional group, method of manufacturing for separator for battery, and separator for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently introducing a sulfur-containing functional group, with high reactivity, the manufacturing method of a separator for a battery, and a separator for a battery. SOLUTION: The introducing method of the sulfur-containing functional group comprises contacting an objective material having moisture with a mixed gas containing fluorine gas and sulfur-containing compound gas. The manufacturing method of the separator for the battery comprises contacting a fiber sheet having moisture with the mixture gas containing fluorine gas and sulfur- containing compound gas. The separator for the battery comprises the sheet manufactured by the above process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for introducing a sulfur-containing functional group, a method for producing a battery separator, and a battery separator.

[0002]

2. Description of the Related Art For example, nonwoven fabrics made of polyolefin fibers have excellent alkali resistance, and can be suitably used as separators for alkaline batteries such as nickel-hydrogen batteries and nickel-cadmium batteries. However, polyolefin-based fibers have low affinity for the electrolytic solution, and an alkaline battery using a nonwoven fabric made of polyolefin-based fibers as a separator cannot generate an electromotive reaction smoothly. Various surface treatments have been implemented to impart affinity.

[0003] As one of the surface treatment methods, there is a method in which a nonwoven fabric made of a polyolefin fiber is brought into contact with a mixed gas containing a fluorine gas and a sulfur-containing compound gas. According to this method, since a sulfur-containing functional group (for example, a sulfofluoride group) can be introduced into the polyolefin-based fiber, the affinity between the polyolefin-based fiber and the electrolytic solution can be imparted. However, from an industrial point of view, there has been a long-awaited need for a method having a higher reactivity and capable of efficiently introducing a sulfur-containing functional group.

On the other hand, fields other than battery separators, for example,
Even in the field where ion absorption, ammonia adsorption or biocompatibility is required, from the industrial point of view, the reactivity is higher and the sulfur-containing functional group can be introduced efficiently from the industrial viewpoint as in the case of the battery separator. The way was long-awaited.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has high reactivity.
It is an object of the present invention to provide a method for efficiently introducing a sulfur-containing functional group, a method for producing a battery separator, and a battery separator.

[0006]

The method for introducing a sulfur-containing functional group according to the present invention is a method in which an object to be treated having moisture is brought into contact with a mixed gas containing a fluorine gas and a sulfur-containing compound gas. As described above, it has been found that, when an object to be treated having moisture is brought into contact with a mixed gas containing a fluorine gas and a sulfur-containing compound gas, reactivity is high and a sulfur-containing functional group can be efficiently introduced.

[0007] The method for producing a battery separator of the present invention is a method in which a sheet containing a fiber sheet having moisture is brought into contact with a mixed gas containing a fluorine gas and a sulfur-containing compound gas. Thus, when the sheet containing the fiber sheet having moisture is brought into contact with the mixed gas containing the fluorine gas and the sulfur-containing compound gas, the reactivity is high, the sulfur-containing functional group can be efficiently introduced, and the hydrophilicity is improved. They found that they could produce excellent battery separators.

[0008] Since the battery separator of the present invention comprises a sheet manufactured by the above-described method, it can be efficiently manufactured and has excellent hydrophilicity.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The object to be treated in the present invention into which a sulfur-containing functional group can be introduced is not particularly limited. Examples thereof include fibers, yarns, films, porous membranes, woven fabrics, knitted fabrics, non-woven fabrics, and the like. It can be a net or a composite of these. When the object to be processed is a sheet-shaped object (for example, a film, a porous film, a woven fabric, a knitted fabric, a nonwoven fabric, a net, or a composite thereof), the object has excellent flexibility and can be wound into a roll. Therefore, after unwinding, a sulfur-containing functional group can be introduced, and then can be wound up,
It is suitable for manufacturing. Further, the resin component constituting the object to be treated is not particularly limited, but examples thereof include polyolefins such as polyethylene and polypropylene, polyesters, polyamides, polyimides, polyphenylene sulfides, silicone resins, and fluorine-containing resins. .

[0010] When the battery separator is manufactured, the object to be treated preferably contains a fiber sheet such as a woven fabric, a knitted fabric, or a nonwoven fabric so as to have excellent electrolyte retention.
More preferably, it comprises a nonwoven fabric, and particularly preferably it comprises a nonwoven fabric and a microporous film. Further, the fibers constituting the fiber sheet and the resin component constituting the microporous film are not particularly limited, but preferably contain a polyolefin-based resin so as to be excellent in alkali resistance and oxidation resistance. More preferably, it is composed of only a polyolefin resin. More specifically, polyethylene (for example, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), ethylene-based copolymer, polypropylene, propylene-based copolymer, polymethylpentene, methyl It is preferably composed of a pentene copolymer or the like.

[0011] Such an object to be processed retains moisture,
Contact with mixed gas containing fluorine gas and sulfur-containing compound gas
Touch. If the water content of the object is too small,
Effective introduction of sulfur-containing functional groups without significant improvement in responsiveness
If it is not possible, if too much, the sulfur
Since there is a tendency that no functional groups can be introduced,
The weight is preferably 0.5 to 50% of the mass of the object to be treated.
And more preferably 0.5 to 40%. In addition,
The surface density of the treated body is usually 10 to 300 g / m. ^TwoIs about
Therefore, the water content is 0.05 to 150 g / m^TwoIs
Is preferred, and 0.05 to 120 g / m^TwoIs more
preferable. In particular, separation of batteries for non-woven fabric
When producing a sheet, the water content is 0.1% of the sheet mass.
It is preferably from 5 to 40%, and from 0.5 to 30%.
Is more preferred. The surface density of the battery separator is
Usually 30-100g / m^TwoWater content
Is 0.15 to 40 g / m^TwoAnd preferably 0.1
5 to 30 g / m^TwoIs more preferable. Note that this
"Water content" means that the object to be treated is heated at a temperature of 105 to 110C.
What is the difference in mass from the mass when dried to a constant mass?
U.

When the object to be processed (including a sheet including a fiber sheet suitable as a battery separator, the same applies hereinafter) does not have moisture, the object to be processed is provided with moisture. . Examples of a method of applying moisture to the object include a method of immersing the object in water, a method of applying water to the object, and a method of spraying water on the object. When water is imparted to a fiber or a microporous film made of a polyolefin resin, as in a battery separator, the polyolefin resin is hydrophobic, and the water may be difficult to adapt. In such a case, it is preferable that the object be modified in advance by a discharge treatment (for example, a corona discharge treatment, a plasma treatment, a glow discharge treatment, an electron beam treatment, or the like) and then water be provided. preferable. Also, add a surfactant to the water,
It is possible to improve the familiarity with the object to be processed, or after applying the water by the method described above, forcibly remove the water by sandwiching the object to be processed with a film or passing between a pair of rolls. You may give.

Next, the object to be treated having moisture is brought into contact with a mixed gas containing a fluorine gas and a sulfur-containing compound gas,
A sulfur-containing functional group is introduced into the object. Examples of the sulfur-containing compound gas include a sulfur monoxide gas and a sulfur dioxide gas. In the present invention, a gas other than the fluorine gas and the sulfur-containing compound gas, for example, an oxygen-containing compound gas (for example, an oxygen gas, a carbon monoxide gas, a carbon dioxide gas, or the like) may be included. Further, since fluorine gas has extremely high reactivity, it is preferable to dilute the fluorine gas by mixing a nitrogen gas or a rare gas (for example, helium, argon, or the like). As described above, the volume ratio when a nitrogen gas or a rare gas is contained is as follows: (fluorine gas, F) :( sulfur-containing compound gas (including oxygen-containing compound gas in some cases), R) :( nitrogen gas, rare gas, D ) = 0.1-2
The ratio is preferably 0: 0.1-20: 99.8-60.

The contact between the object to be treated having water and the mixed gas can be carried out at room temperature, and the object to be treated and the mixed gas are brought into contact so that a sulfur-containing functional group can be easily introduced. The object to be processed may be heated before, during, or after the contact. Note that the contact temperature of the object to be processed with the mixed gas is preferably about 10 to 80 ° C.

The contact time of the object to be treated with the mixed gas is not particularly limited, but it is preferable that the object be contacted for 10 seconds or more so that the sulfur-containing functional group can be sufficiently introduced. Since the mixed gas has a very high reactivity and is dangerous, the contact between the object to be processed and the mixed gas is performed in a closed container, or the inlet and outlet of the object to be processed are filled with nitrogen gas. It is preferably carried out in a container that can be sealed by such as.

[0016] By bringing the object to be treated having moisture into contact with the mixed gas as described above, a sulfur-containing functional group can be introduced. However, since fluorine gas is contained in the mixed gas, fluorine atoms can be introduced. Since a functional group (for example, a sulfofluoride group) is also introduced, when further hydrophilicity is required (for example, when used for a battery separator), the object to be treated is brought into contact with a mixed gas before being treated with water. It is preferable to replace the fluorine atom with a hydrogen atom by immersion in water or alcohol.

The object to which the sulfur-containing functional group is introduced as described above is hydrophilic, water-absorbing, water-retaining, adhesive, dyeing, printing, ion-exchange, ion-absorbing, ammonia-adsorbing,
Or because the biocompatibility is given or improved,
It can be suitably used for applications requiring these characteristics. In particular, a sheet including a fiber sheet (particularly a fiber sheet made of polyolefin fiber) which has been hydrophilized by introducing a sulfur-containing functional group by the above-mentioned method is used for a battery separator (in particular, a nickel-cadmium battery, a nickel-hydrogen battery). When used as a battery, it is possible to easily inject the electrolyte into the entire separator during battery manufacture, and it is also excellent in the retention of the electrolyte over a long period of time. Can be.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0019]

EXAMPLES (Preparation of nonwoven fabric) Fineness 2 having a core component of polypropylene (melting point: 160 ° C.) and a sheath component (fusing component) of low density polyethylene (melting point: 115 ° C.)
Denier, core-sheath type heat-fusible fiber with a fiber length of 10 mm 25 m
as%, as shown in FIG. 1, a polypropylene component (symbol 12 in the figure, one circular ultrafine polypropylene fiber having a fineness of 0.02 denier (melting point: 160 ° C.) and a triangular polypropylene having a fineness of 0.08 denier Eight ultra-fine fibers (melting point: 160 ° C) can be generated and eight high-density polyethylene components (symbol 11 in the figure, eight high-density polyethylene ultra-fine fibers having a fineness of 0.08 denier (melting point: 125 ° C) can be generated) Having an orange cross section and a fineness of 1.
3 denier, splittable fiber 40 mass having a fiber length of 15 mm
% And tensile strength 9 g / d (denier), fineness 2
A slurry obtained by mixing and dispersing denier and 35 mass% of high-strength polypropylene fiber having a fiber length of 10 mm (melting point: 168 ° C.) was formed by a slant wire short net method to form a fiber web.

Next, the fiber web is dried by a hot air circulation dryer set at a temperature of 120 ° C., and simultaneously with the drying of the fiber web, the sheath component of the core-sheath type heat-fusible fiber is fused to produce a fused fiber web. did. Next, the fused fiber web was placed on a 100 mesh net, and the nozzle diameter was 0.15.
mm, a water stream with an internal pressure of 12 MPa is jetted from the nozzle plate in which nozzles are arranged in a line at a nozzle pitch of 0.8 mm to the fused fiber web alternately on both sides alternately twice, so as to be entangled and at the same time splittable fibers. Divided. Next, the fused fiber web to which the water flow was applied was dried by a hot air circulation dryer set at a temperature of 120 ° C., and at the same time, the sheath component of the core-sheath type heat-fusible fiber was fused to obtain a surface density of 60 g.
/ M ² and a non-woven fabric having a thickness of 0.15 mm.

(Example 1) [0021] After uniformly spraying water on the nonwoven fabric obtained as described above, water is applied to the nonwoven fabric by passing between nip rolls, and at the same time, the water content is 10% of the weight of the nonwoven fabric. %. Next, fluorine gas (3 vol%), oxygen gas (5 vol%), sulfur dioxide gas (5 vol%) and nitrogen gas (87 vol%)
%) Is supplied to the container filled with the mixed gas consisting of
The contact was performed for 20 seconds (temperature: 20 ° C.). Then, the nonwoven fabric contacted with the mixed gas is dried by a drier set at a temperature of 80 ° C., and then calendered at a linear pressure of 9.8 N / cm to have an areal density of 60 g / m ² and a thickness of 0.1 g / m ² . A 15 mm separator was manufactured.

(Example 2) [0022] After uniformly spraying water on the non-woven fabric obtained as described above, water is passed between the nip rolls to make the non-woven fabric familiar with water, and at the same time, the water content is 25% of the weight of the non-woven fabric. Except that it was adjusted to be%
The same operation as in Example 1 was repeated to obtain an areal density of 60 g /
A separator having a thickness of m ² and a thickness of 0.15 mm was produced.

(Comparative Example) The same operation as in Example 1 was performed except that water was not sprayed on the nonwoven fabric obtained as described above, and the water was used as it was (water content was 0% of the mass of the nonwoven fabric). Repeatedly, area density 60 g / m ² , thickness 0.15 mm
Was manufactured.

(Measurement of Liquid Absorbing Height) Each of the separators of Examples 1 and 2 and Comparative Example was cut into a rectangular shape having a width of 25 mm and a length of 180 mm, and the water was equilibrated. Next, a region from one end of each strip-shaped separator to 5 mm is immersed at right angles in an aqueous solution of potassium hydroxide having a specific gravity of 1.3 kept at a temperature of 20 ° C. ± 2 ° C., and after 10 minutes, The elevated height of the aqueous potassium oxide solution was measured. The results were as shown in Table 1. As described above, since the separator of the present invention has a high liquid absorption rate and can inject the electrolytic solution into the entire separator, the battery can be efficiently produced.

[0025]

【table 1】

(Measurement of Drop Absorption Rate) After each of the separators of Examples 1 and 2 and Comparative Example was brought into water equilibrium, a temperature of 20 ° C. was measured for five randomly selected points of each separator.
30 µl of aqueous potassium hydroxide solution with a specific gravity of 1.3 at ± 2 ° C
(Microliter) was dropped, and the time required for the aqueous potassium hydroxide solution to be completely absorbed by the separator was measured, and the average time was calculated. The results were as shown in Table 1. As described above, since the separator of the present invention has a high absorption rate, a battery can be efficiently produced.

[0027]

According to the method for introducing a sulfur-containing functional group of the present invention,
This method has high reactivity and can efficiently introduce a sulfur-containing functional group.

The method for producing a battery separator according to the present invention is a method for producing a battery separator having high reactivity, capable of efficiently introducing a sulfur-containing functional group, and having excellent hydrophilicity.

The battery separator of the present invention can be manufactured efficiently and has excellent hydrophilicity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a splittable fiber.

[Explanation of symbols]

 Reference Signs List 1 splittable fiber 11 high-density polyethylene component 12 polypropylene component

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F073 AA01 BA07 BA08 BA23 BA29 BA31 BB01 BB04 DA04 DA06 DA09 4L031 AA14 AB09 AB10 AB34 BA07 BA17 CA08 DA08 DA09 DA21 5H021 BB09 CC02 EE02 EE04 EE07 EE08 EE10 EE23 EE34

Claims (5)

[Claims] 1. A method for introducing a sulfur-containing functional group, comprising contacting an object to be treated having moisture with a mixed gas containing a fluorine gas and a sulfur-containing compound gas. 2. The method for introducing a sulfur-containing functional group according to claim 1, wherein the water content of the object to be treated is 0.5 to 50% of the mass of the object to be treated. 3. A method for producing a battery separator, comprising contacting a sheet containing a fiber sheet holding moisture with a mixed gas containing a fluorine gas and a sulfur-containing compound gas. 4. The method for producing a battery separator according to claim 3, wherein the moisture content of the sheet including the fiber sheet is 0.5 to 40% of the sheet mass. A separator for a battery, comprising a sheet manufactured by the method according to claim 3 or 4.