JPH0794163A - Alkali resistant fiber, alkaline battery separator using the fiber and alkaline battery using the separator - Google Patents

Abstract

PURPOSE:To provide a separator free from the ingress of an electrolyte, while having the high capability of holding an electrolyte and preventing the appearance of dendrite by impregnating alkali resistant fiber with the bridged state of polyvinyl alcohol having the specified constitutional unit. CONSTITUTION:Polyvinyl alcohol having a constitutional unit expressed by the general formula is bridged and alkali resistant fiber is impregnated with the polyvinyl alcohol in bridged state. In the formula I, R1 stands for a quaternary aromaticity complex cyclic residual group containing nitrogen, R2 for a hydrogen atom or an alkoxy group and R3 for a hydrogen atom or an acyl group. Also, (m) stands for 0 or 1, and (n) for a natural number between 1 and 6. An alkaline battery separator is formed out of a fabric sheet including that alkali resistant fiber. Also, the separator is plain weave, twilled weave, or sateen weave fiber including the aforementioned fiber, or a fabric sheet such as nonwoven fabric or fabric available from a wet method, a span pond method, a melt blow method, a water flow leno weaving method, a needle punch method, a partial or total thermocompression method, or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkali resistant fiber, an alkaline battery separator using the same, and an alkaline battery using the same.

[0002]

2. Description of the Related Art Conventionally, a separator has been used so as to separate a positive electrode and a negative electrode of an alkaline battery to prevent a short circuit and to hold an electrolytic solution so that an electromotive reaction can be carried out smoothly.

A conventional alkaline secondary battery separator is
It is provided in the form of a woven fabric or a non-woven fabric, and the fibers that make up the woven fabric or the non-woven fabric are polyamide fibers, and it is common to use a potassium hydroxide solution as the electrolytic solution. There was a problem that the positive electrode and the negative electrode were short-circuited by being attacked.

Therefore, it has been considered to use a separator using a polyolefin fiber such as polypropylene fiber, but since the polyolefin fiber is hydrophobic and has a low affinity with the electrolytic solution, the electrolyte retaining property is low. There was a problem of being bad.

Further, the separator using the above polyamide-based fiber or polyolefin-based fiber has a shortened service life due to a so-called dendrite in which dendritic metal is deposited on the electrode plate during discharging and / or charging. There was also the problem of being short.

On the other hand, conventional separators for alkaline primary batteries are provided in the form of non-woven fabric, paper, etc. Vinylon fibers and polyvinyl alcohol fibers make up the non-woven fabric and paper, and potassium hydroxide solution is used as an electrolytic solution. However, there is a problem that the fiber is attacked by the electrolytic solution as it is used, and the positive electrode and the negative electrode are short-circuited.

[0007] Further, pulp such as mercerized pulp and linter pulp is used in order to improve the electrolyte retention of the separator. Impurities and / or impurities in these pulps are used.
Or, in order to suppress the generation of hydrogen in the electrolytic solution, due to the action of aluminum added to the zinc that constitutes the negative electrode, during discharge, a short circuit occurs due to dendrites in which dendritic zinc oxide is deposited on the electrode plate, There is also a problem that the service life is short, such as causing abnormal voltage drop.

[0008]

DISCLOSURE OF THE INVENTION The present invention is not affected by an alkaline solution such as a potassium hydroxide solution, and is not affected by an alkali resistant fiber or an alkaline solution which is excellent in retaining the alkaline solution. It is intended to provide a separator for an alkaline battery which has excellent properties and excellent dendrite prevention property, and an alkaline battery having a long service life.

[0009]

The alkali resistant fiber of the present invention has the general formula

[Chemical 2] (In the formula, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, and n is 1 to 1. Polyvinyl alcohol having a structural unit represented by a natural number of 6) (hereinafter,
"PVA" is sometimes crosslinked (hereinafter,
"Crosslinked PVA").

The alkaline battery separator of the present invention (hereinafter sometimes referred to as "separator") comprises a fiber sheet containing the alkali resistant fiber.

The alkaline battery of the present invention is an alkaline battery using the above separator.

[0012]

The crosslinked PVA contained in the alkali resistant fiber of the present invention is not easily decomposed by an alkaline electrolytic solution such as potassium hydroxide, has an affinity with the alkaline electrolytic solution, and retains liquid. The separator containing the alkali-resistant fiber is excellent in alkali resistance and liquid retention, and at the time of discharging and / or charging, it chelate with ions before the dendritic metal is deposited on the electrode plate. It is a separator that can form ions to trap ions, is unlikely to deposit dendritic metal, and is unlikely to cause a short circuit due to dendrite. Further, since the crosslinked PVA is also excellent in heat resistance, it is a separator that can withstand use under high temperature conditions such as trickle charging. As described above, the separator of the present invention is excellent in alkali resistance, liquid retention, and dendrite prevention property, so that the alkaline battery using this separator can be used for a long period of time. The formation of chelates with ions to trap the ions has been confirmed by the experimental examples described later.

The PVA of the present invention has a structural unit represented by the following general formula.

[Chemical 3] In the formula, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, and n is 1 Is a natural number of 6 to 6, and R ₁ is, for example, a pyridinium group, a quinolinium group, an isoquinolinium group, a pyrimidinium group, a thiazolium group, a benzothiazolium group, a benzoxazolium group, etc. May have a substituent such as an alkyl group, an alkoxyl group, an amino group and a carbamoyl group. R ₂ is, for example, a hydrogen atom or an alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group and an isopropoxy group. R ₃ is, for example, a hydrogen atom or an acyl group such as a formyl group, an acetyl group, a propionyl group, a butyryl group and an isobutyryl group.

More specifically, chemical formulas 4 to 7 in which R ₃ is a hydrogen atom and chemical formula 8 in which R ₃ is an acetyl group can be exemplified.

[Chemical 4]

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

The hydroxyl group of PVA is preferably present in an amount of 20 mol% or more, more preferably 40 mol% or more, and most preferably 80 mol, based on the monomer unit of PVA so as to easily form a chelate with an ion. % Or more. Further, although the aromatic nitrogen-containing heterocyclic residue is cross-linked with a side chain containing the nitrogen-containing heterocyclic residue, the aromatic nitrogen-containing heterocyclic residue is added to the monomer unit of PVA so as not to inhibit chelate formation between a hydroxyl group and an ion. , Preferably 20 mol% or less,
It is preferably 0.5 mol% or more so as not to impair the electrolytic solution resistance and heat resistance due to crosslinking. More preferably, it is 1 to 10 mol%.

The degree of polymerization of PVA is not less than 500, and the degree of saponification is not limited to 70 to 100%.

When a hydrophobic portion is partially formed on the PVA with, for example, an aldehyde compound such as butyraldehyde, flexibility is generated and the handleability can be improved.

The alkali resistant fiber of the present invention is a fiber containing the above-mentioned crosslinked PVA, and may be, for example, a fiber consisting of only the crosslinked PVA obtainable by the wet spinning method, or the crosslinked PVA may be a constituent component of the fiber. One of the fibers may be a spun fiber, or may be a fiber such as a regenerated fiber, a semi-synthetic fiber, a synthetic fiber, a plant fiber, or an animal fiber having crosslinked PVA partially or wholly attached to the fiber surface.

Hereinafter, the alkali resistant fiber having the latter crosslinked PVA attached to the fiber surface will be described.

The crosslinked PVA can be adhered to the surface of the fiber by, for example, adhering the crosslinked PVA with an adhesive, or spraying, impregnating or applying an uncrosslinked PVA solution on the fiber. After that, there is a method of crosslinking. If it is the latter method, no adhesive is used,
Since it does not deteriorate the performance of the crosslinked PVA, it is a suitable attachment method.

There is no particular problem when the cross-linked PVA is entirely attached to the fiber surface, but when it is partially attached, the alkali resistance of the non-attached portion may be poor. Therefore, as the fibers to which the crosslinked PVA is attached, polyolefin fibers such as polyethylene fibers and polypropylene fibers having excellent alkali resistance, core-sheath type fibers,
Side-by-side type, eccentric type, or FIGS. 1 (a) to 1 (d)
1 having a chrysanthemum-shaped fiber cross section in which one component 1 is arranged between the other components 2, as shown in FIG. 1 (e),
A polyolefin fiber such as a splittable or non-splittable conjugate fiber having a fiber cross section in which one component 1 and the other component 2 are alternately laminated in layers can be preferably used. In particular, crosslinked PVA
In the case where the fibers adhered in (1) are splittable conjugate fibers, after splitting, the fibers become ultrafine fibers having a portion to which the crosslinked PVA is not attached, so it is preferable to use polyolefin-based splittable conjugate fibers.

A nonwoven fabric obtained by dividing the polyolefin-based dividable conjugate fiber into an ultrafine fiber or a nonwoven fabric obtained by a melt-blowing method has a large surface area and thus has a high affinity for an electrolytic solution, and moreover, a distance between entanglement points of the fibers. It is a separator that can be used for a long period of time because it is short and has minute voids and is dense, which produces a capillary effect, is more excellent in liquid retention, and can physically prevent short circuits due to dendrites. Further, the ultrafine fibers obtained by dividing the polyolefin-based splittable conjugate fiber can be obtained by splitting at the same time as the entanglement by the water flow, and therefore, not only is preferable in production, but the resulting nonwoven fabric is also excellent in strength, It has excellent workability during battery assembly and can be used favorably.

In the present invention, an adhesive fiber may be included in addition to the fiber containing the crosslinked PVA to improve the dimensional stability of the separator and further improve the handling property. As the adhesive fiber, it is preferable to use all-melt type polyethylene fiber or polypropylene fiber polyolefin fiber having excellent alkali resistance, or partially melt type core-sheath type, side-by-side type, or eccentric type polyolefin-based composite fiber. In addition, it is also possible to bond with the adhesive resin component produced from the splittable conjugate fiber containing the adhesive resin component.

The separator of the present invention includes a woven fabric such as a plain weave, a twill weave, and a satin weave containing the above-mentioned fibers, a wet method, a spunbond method, a melt blow method, a hydroentangling method, a needle punch method, a partial or complete method. A nonwoven fabric obtained by a method such as a thermocompression bonding method, or a fiber sheet such as a knitted fabric.

When the fiber containing the crosslinked PVA is contained in an amount of 10% by weight or more in the separator of the present invention, the separator is excellent in the liquid retention property and the dendrite prevention property.

The separator of the present invention obtained as described above can be used for alkaline primary batteries or alkaline secondary batteries. For example, when it is used as a cylindrical alkaline manganese primary battery, the negative electrode portion is copper. Around the current collector of the negative electrode consisting of a brass bar or brass, and a negative electrode mixture layer obtained by kneading an amalgamated zinc powder with an alkaline solution and a gelling agent such as carboxymethyl cellulose. A positive electrode mixture layer made of a mixture with carbon powder, and a nickel-plated steel plate that serves as both a positive electrode current collector and a terminal formed on the outside of the positive electrode mixture layer. The separator of the present invention is sandwiched and used so as to separate the layer and the positive electrode mixture layer. Even when zinc is used for the negative electrode as in this alkaline manganese primary battery, the use of the separator of the present invention can prevent a short circuit due to dendrite without using mercury to suppress the elution of zinc. As it can be prevented, it does not cause any environmental problems. Furthermore, since it is not necessary to use pure zinc so that mercury is not used, there is a labor saving of energy consumed for obtaining pure zinc, and a cost merit thereby arises.

On the other hand, for example, when it is used in a cylindrical nickel-cadmium sealed secondary battery, it is provided between a negative electrode composed of a porous body mainly composed of metal cadmium particles and a positive electrode having nickel hydroxide filled in the porous body. Then, the separator of the present invention is interposed, and the spirally wound cylindrical product is housed in a cylindrical nickel-plated steel case together with the electrolytic solution and hermetically sealed.

When the separator of the present invention is used in a nickel-hydrogen battery, self-discharge can be suppressed,
A battery with a long service life can be obtained. This is because the separator of the present invention can adsorb and suppress the migration of the metal eluted from the hydrogen storage electrode to the positive electrode, which is the main cause of self-discharge in the nickel-hydrogen battery. In addition, since the separator of the present invention can adsorb the eluted metal, the same effect can be obtained in other secondary batteries.

The alkaline primary battery of the present invention may have a cylindrical shape or a button shape, and the shape is not limited. On the other hand, the alkaline secondary battery may also be an open type or a closed type, and the shape may be a cylindrical shape, a flat shape, or a prismatic shape, and this point is not limited. The separator of the present invention is, for example, an alkaline manganese battery, a mercury battery, a silver oxide battery, a primary battery such as an air battery, a nickel-cadmium battery, a silver-zinc battery, a silver-cadmium battery, a nickel-zinc battery, a nickel-hydrogen battery. It can be used for secondary batteries such as.

Examples of the separator of the present invention will be described below, but the present invention is not limited to the following examples.

[0031]

【Example】

(Experiments 1 to 9) As shown in Table 1, 13% by weight of PVA (experiments 1 to 9) containing various styrylpyridinium-based residues and having a hydroxyl group capable of forming a chelate in an uncrosslinked state was dissolved in water. The PVA aqueous solution was applied on an acrylic plate with a metal coater and then dried at room temperature to obtain a film having a thickness of 100 μm. This was irradiated with ultraviolet rays for 10 minutes with a high pressure mercury lamp and self-crosslinked to obtain a crosslinked PVA film.

(Zinc ion adsorption test) 3 cm × 3 in a 30% potassium hydroxide solution having a zinc ion concentration of 0.1 mol / l
After immersing the films of Experiments 1 to 9 cut in cm and leaving them for 24 hours, each film was washed with pure water to remove zinc ions which were not attached to the surface but did not form a chelate. , Ash each film with a platinum crucible,
The adsorbed zinc ions were extracted and the zinc ion adsorption amount was measured by the atomic absorption method with a constant volume. The results are shown in Table 1.

[0033]

[Table 1]

(Cadmium ion adsorption test-1) Experiments 1 to 8 were conducted in an aqueous solution having a cadmium ion concentration of 0.1 mol / l.
The cadmium ion adsorption amount was measured in exactly the same manner as the zinc ion adsorption test except that each of the films was immersed. The results are also shown in Table 1.

(Cadmium ion adsorption test-2) Zinc ions except that the films of Experiments 1 to 3 were immersed in a 30% potassium hydroxide solution having a cadmium ion concentration of 8.9 × 10 ^-5 mol / l. The cadmium ion adsorption amount was measured in exactly the same manner as the adsorption test. The results are also shown in Table 1.

As can be seen from Table 1, since the crosslinked PVA film can adsorb metal, it is considered that the deposition of dendritic metal can be suppressed and the short circuit due to dendrite can be prevented.

Example 1 50 parts of polyethylene resin and 50 parts of polypropylene resin were separately melted in an extruder and weighed at a gear pump speed ratio of 5: 5. Composite spinning and stretching so that the polyethylene resin component becomes the sheath component,
A composite fiber filament having a fineness of 1.5 denier was obtained.

On the other hand, a styrylpyridinium-based residue as shown in Chemical formula 4 (a) is added to the PVA monomer unit in an amount of 1
An uncrosslinked 3 wt% PVA aqueous solution was obtained in which PVA having a mol% of 99% and a chelate-forming hydroxyl group of 99 mol% and a polymerization degree of 1,700 and a saponification degree of 88% was dissolved in water.

Next, the composite fiber filament is mixed with the P
After contacting with a roll containing an aqueous VA solution and drying, 0.5% by weight of solid content PVA is attached to the composite fiber, and then UV light is irradiated for 1 minute by a high pressure mercury lamp to self-crosslink the PVA. Let The composite fiber filament having the crosslinked PVA attached was cut into 51 mm to obtain an alkali resistant fiber of the present invention.

Alkali-resistant fiber 80 thus obtained
20% by weight of polypropylene-polyethylene core-sheath composite fiber (1.5 denier, 51 mm) having no cross-linked PVA attached and obtained in the same manner as described above was mixed and opened by a card machine. The fiber web is heat-treated at 130 ° C. to fuse only the polyethylene component which is the sheath component of the core-sheath type composite fiber, and the basis weight is 70 g / m ² and the thickness is 0.2 mm.
To obtain a separator.

(Example 2) 50% by weight of alkali resistant fiber
And polypropylene-polyethylene core-sheath type composite fiber (1.5 denier, 51 mm) without cross-linked PVA attached 5
A separator having a basis weight of 70 g / m ² and a thickness of 0.2 mm was obtained in the same manner as in Example 1 except that 0% by weight was mixed.

(Comparative Example) Example 1 except that 100% by weight of polypropylene-polyethylene core-sheath type composite fiber (1.5 denier, 51 mm) without cross-linked PVA attached was used.
A nonwoven fabric was obtained in the same manner as in. Thereafter, a nonionic surfactant was attached to the nonwoven fabric in a solid content of 0.5% by weight to obtain a separator having a basis weight of 70 g / m ² and a thickness of 0.2 mm.

(Wettability) After the separators of Examples 1 and 2 and Comparative Example were cut into 2 × 15 cm, the separator was immersed in an aqueous solution of potassium hydroxide having a specific gravity of 1.3 for 0.5 cm for 30 minutes. The wettability is evaluated by the height of the liquid absorbed when the time has elapsed. This test was performed before and after the battery charge / discharge test described below. The results are shown in Table 2.

[0044]

[Table 2]

(Battery Charge / Discharge Test) Using the separators of Examples 1 and 2 and Comparative Example, the battery capacity was 1200 mAh.
Nickel-cadmium battery was manufactured. After activating this battery, place each battery in a constant temperature bath at 20 ℃.
After charging with mA for 6 hours, resting for 30 minutes, and discharging to a final voltage of 0.8 V at 240 mA as one cycle,
Measure the number of times to charge and discharge. The results are also shown in Table 2.

[0046]

INDUSTRIAL APPLICABILITY The crosslinked PVA contained in the alkali resistant fiber of the present invention is not easily decomposed by an alkaline electrolytic solution such as potassium hydroxide, and is not easily decomposed with an alkaline electrolytic solution such as potassium hydroxide. It is a fiber that has affinity and excellent liquid retention.

Since the alkaline battery separator of the present invention contains the alkali resistant fiber,
It has excellent liquid retention, and at the time of discharging and / or charging, it can form a chelate with ions before the dendritic metal is deposited on the electrode plate and can be captured, so that the dendritic metal is less likely to deposit,
A short circuit due to a dendrite is unlikely to occur, and it can be used for a long time.

As described above, since the separator of the present invention is not easily corroded by the electrolytic solution, has an excellent liquid retaining property, and has an excellent dendrite prevention property, the alkaline primary battery and alkaline secondary battery using this separator are It has a long service life.

[Brief description of drawings]

FIG. 1 (a) is a schematic sectional view of a splittable conjugate fiber of the present invention (b) is a schematic sectional view of another splittable conjugate fiber of the present invention (c) is another splittable conjugate fiber of the present invention (D) A schematic cross-sectional view of another splittable conjugate fiber of the present invention (e) A schematic cross-sectional view of another splittable conjugate fiber of the present invention

[Explanation of symbols]

 1 one component 2 other component

Claims (3)

[Claims] 1. A general formula: (In the formula, R ₁ is a quaternized aromatic nitrogen-containing heterocyclic residue, R ₂ is a hydrogen atom or an alkoxy group, R ₃ is a hydrogen atom or an acyl group, m is 0 or 1, and n is 1 to 1. An alkali resistant fiber comprising a polyvinyl alcohol having a structural unit represented by a natural number of 6) in a crosslinked state. 2. An alkaline battery separator comprising a fiber sheet containing the alkali resistant fiber according to claim 1. 3. An alkaline battery comprising the alkaline battery separator according to claim 2.