JP2001210298A - Alkaline battery separator and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for an alkaline battery which is excellent in a self-discharge suppressing action and a wettability and has a small variation in a capacity retention ratio, and a method for producing the same. SOLUTION: The alkaline battery separator includes a fiber sheet having an average ammonia trapping amount of 0.4 mmol / g or more. In the production method, the graft polymerizable monomer, oligomer, and / or polymer may be used in an amount of 0.01
After performing a graft polymerization treatment in the presence of oxygen on a fiber sheet to which a graft polymerization solution containing a mass% or more of a surfactant was attached, the entire area of the upper surface and the lower surface of the fiber sheet was covered with an air-impermeable film. In this state, a graft polymerization treatment is further performed to prepare a graft-polymerized fiber sheet for an alkaline battery separator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for an alkaline battery (hereinafter sometimes simply referred to as "separator") and a method for producing the same. The alkaline battery separator of the present invention is, for example, an alkaline primary battery (for example,
Alkaline manganese battery, mercury battery, silver oxide battery, or air battery) or alkaline secondary battery (e.g., nickel-cadmium battery, silver-zinc battery, silver-cadmium battery, nickel-zinc battery, nickel-hydrogen battery, or charging) Type alkaline manganese battery), and particularly suitable for a nickel-cadmium battery or a nickel-hydrogen battery.

[0002]

2. Description of the Related Art Conventionally, a separator has been used so that a positive electrode and a negative electrode of an alkaline battery can be separated to prevent a short circuit, and at the same time, an electrolysis reaction can be carried out smoothly by holding an electrolytic solution. . Since this separator needs to hold an electrolytic solution composed of potassium hydroxide or the like, a fiber sheet composed of polyolefin fibers having excellent alkali resistance is preferable. However, polyolefin-based fibers have low affinity for the electrolyte and have very poor retention of the electrolyte. Therefore, the fiber sheet made of the polyolefin-based fibers is hydrophilized by various methods to retain the electrolyte. Noh was given.

[0003] As one of the hydrophilic treatment methods, there is a method of graft-polymerizing a vinyl monomer. For example, Japanese Patent Publication No. Hei 6-509208 discloses a separator in which a vinyl monomer is graft-polymerized on a cloth made of polyolefin fibers, and the above publication further discloses a vinyl monomer added to a cloth made of polyolefin fibers. A method for producing a separator, comprising a step of impregnating the solution with a solution of the above and a step of irradiating the cloth with ultraviolet rays under conditions not exposing to oxygen, are disclosed. However, when this separator is used in a nickel-cadmium battery, a nickel-hydrogen battery, or the like, oxygen generated at the time of overcharge deteriorates the separator to cause a short circuit, or a deteriorated product due to oxygen affects the electrode plate, The life of the battery may be shortened, and the self-discharge suppressing action is also low.

The present inventor has already found a separator for an alkaline battery and a method for producing the same which have solved the above disadvantages (Japanese Patent Application Nos. 10-217116 and 11-2).
No. 47808). That is, the fiber sheet to which the graft-polymerizable monomer and / or polymer is adhered is subjected to the first graft polymerization treatment in the presence of oxygen, and then the fiber sheet is further surrounded by a non-breathable film. It has been found that by performing the graft polymerization treatment of No. 2, an alkaline battery separator having excellent oxidation resistance and self-discharge suppressing action can be obtained.

[0005]

SUMMARY OF THE INVENTION The inventors of the present invention have conducted intensive studies with the aim of obtaining a separator for an alkaline battery having an excellent self-discharge suppressing action. It has been found that a battery separator for alkali having extremely excellent discharge suppressing action can be obtained. It has also been found that a fiber sheet having a high ammonia trapping amount can be obtained, for example, by performing the first and second graft polymerization treatments using a graft polymerization solution containing a surfactant. When the fiber sheet thus obtained is used as a separator for an alkaline battery, it has been newly found that not only the self-discharge suppressing action is excellent, but also the wettability and the capacity retention ratio have excellent characteristics. The present invention is based on such findings. Therefore, the object of the present invention is to
In order to provide an alkaline battery separator having excellent self-discharge suppressing action, furthermore, in addition to the self-discharging suppressing action, also has excellent wettability, and further has a small capacity retention rate variation, and, It is to provide a manufacturing method thereof.

[0006]

The object of the present invention is to include a fiber sheet according to the present invention having an average ammonia trapping amount of 0.4 mmol / g or more (hereinafter referred to as a high ammonia-trapping fiber sheet). The problem can be solved by a separator for an alkaline battery. In addition, the present invention provides a monomer, oligomer, and / or
Alternatively, after performing a graft polymerization treatment in the presence of oxygen on a fiber sheet to which a graft polymerization solution containing a polymer and 0.01 to 3% by mass of a surfactant is adhered, the entire area of the upper surface and the lower surface of the fiber sheet is not covered. The present invention relates to a method for producing a separator for an alkaline battery, comprising preparing a graft-polymerized fiber sheet for an alkaline battery separator by further performing a graft polymerization treatment in a state of being covered with a breathable film.

[0007] In this specification, the "average ammonia trapping amount" is an average value of 10 or more measuring points of the ammonia trapping amount, and is an arbitrary value of any one measuring point 1 of the target fiber sheet.
It can be obtained by measuring the amount of trapped ammonia in a method described later for zero or more locations and calculating the average value thereof.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The high ammonia-capturing fiber sheet in the alkaline battery separator of the present invention is, for example,
The non-woven fabric, woven fabric, or knitted fabric having an average ammonia trapping amount of 0.4 mmol / g or more, or a composite thereof may be used. It is preferred that Among these, the fibers can be arranged three-dimensionally, and in terms of excellent retention of the electrolytic solution, it is more preferable that the fibers include a graft-polymerized nonwoven fabric, and that the nonwoven fabric further comprises a graft-polymerized nonwoven fabric. preferable. In addition, the ammonia high-capturing fiber sheet has a fineness of 0.01 to 4 dt so as to have appropriate denseness for preventing a short circuit or excellent permeability for generated gas and the like.
ex (decitex) fibers.

Hereinafter, the present invention will be described in accordance with an embodiment in which the high ammonia-capturing fiber sheet is a graft-polymerized fiber sheet.

The fibers constituting the high ammonia-capturing fiber sheet include, for example, polyolefin fibers (for example, polypropylene fibers or polyethylene fibers), polyamide fibers, vinylon fibers, vinylidene fibers, polyvinyl chloride fibers, polyester fibers, and acrylic fibers. Fiber or polyurethane fiber. Among these, it is preferable to use a polyolefin-based fiber because of its excellent alkali resistance.

[0011] The polyolefin-based fiber may be, for example, a polymer of a monomer such as propylene, ethylene, butene, or methylpentene, a copolymer of two or more of these monomers, or a copolymer of these monomers with vinyl alcohol;
A copolymer with acrylic acid or methacrylic acid (for example,
A resin component such as an ethylene-vinyl alcohol copolymer, an ethylene-acrylic acid copolymer, or an ethylene-methacrylic acid copolymer. In addition, the polyolefin-based fiber may be a single fiber composed of only one type of the resin component, or may be a composite fiber composed of two or more types of the resin component. Examples of the latter composite fiber include a composite fiber having a fiber cross-sectional shape of, for example, a core-sheath type, a side-by-side type, an eccentric type, a sea-island type, an orange type, or a multi-bimetal type.

Since the polyethylene resin is easily graft-polymerized, it is preferable that the polyethylene resin accounts for more than 60% of the total surface of the fibers constituting the fiber sheet before the graft polymerization. Further, when the resin component constituting the fiber surface is made of an ethylene-vinyl alcohol copolymer, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, or the like, the graft reaction speed is increased, and the fibers themselves are hydrophilic. It is suitable because of its nature.

In addition, the high ammonia-capturing fiber sheet in the alkaline battery separator of the present invention can contain, for example, at least one kind of fibers of ultrafine fibers, high-strength fibers, or fusion fibers.

The fine fibers have a fineness of 0.55 d.
tex or less (preferably 7.8 × 10 ⁻⁷ dtex or less)
0.33 dtex). By containing such ultrafine fibers, the retention of the electrolyte can be improved, excellent dendritic prevention can be obtained, high capacity can be achieved, and the battery life can be prolonged. Can be.

The ultrafine fibers are preferably made of a polyolefin-based polymer [eg, polyethylene (eg, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, or ultra-high-molecular-weight polyethylene), polypropylene, etc. , Polymethylpentene,
Ethylene-propylene copolymer or ethylene-butene-propylene copolymer]. More specifically, it is more preferably made of polyethylene (low-density polyethylene, linear low-density polyethylene, or high-density polyethylene), polypropylene, polymethylpentene, or the like.

Such an ultrafine fiber may be subjected to, for example, a mechanical treatment (for example, a treatment with a fluid such as a water stream, or a calender treatment) or a chemical treatment (for example, a treatment for removing a polymer, or a treatment for swelling at least one polymer). )
Thus, the dividable splittable fiber can be split or formed by a melt blow method. Among the above-mentioned methods, it is preferable to divide and form a splittable fiber capable of obtaining an ultrafine fiber having excellent fiber strength.
Examples of the cross-sectional shape of the preferable splittable fiber include a sea-island shape, an orange shape, and a multi-bimetal shape. Such splittable fibers are
Spinning can be performed by a conventional composite spinning method.

[0017] The ammonia-capturing fiber sheet constituting the alkaline battery separator of the present invention may contain high-strength fibers having a tensile strength of 4.5 cN / dtex or more. The high-strength fiber has a tensile strength of 6.2 cN / d.
tex or more, more preferably 8 cN / dtex or more, and 10.7 cN / dtex.
It is most preferred that this is the case. In addition, "tensile strength" in this specification means the value measured by the method prescribed | regulated to JISL1015 (chemical fiber staple test method). When the ammonia high-capturing fiber sheet contains such high-strength fibers, it prevents the burrs of the electrode plate from penetrating through the separator or being cut by the edge of the electrode plate to cause a short circuit when manufacturing a battery. can do.

The high-strength fiber is also made of a polyolefin-based polymer, for example, polyethylene (for example, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, or ultra-high-molecular-weight polyethylene) or polypropylene so as to have excellent alkali resistance. , Polymethylpentene,
It is preferably an ethylene-propylene copolymer or an ethylene-butene-propylene copolymer.
Among them, it is preferable to be made of polypropylene or ultrahigh molecular weight polyethylene (average molecular weight is about 1,000,000 to 5,000,000).

The high ammonia-capturing fiber sheet constituting the separator for an alkaline battery of the present invention may contain fused fibers. Examples of the fused fibers include fused fibers used in known nonwoven fabrics. When the high ammonia-capturing fiber sheet contains the fused fibers, the tensile strength and the softness of the separator can be improved, so that a battery can be manufactured with a high yield.

In order to prevent the fiber strength of all the constituent fibers other than the fused fibers constituting the high ammonia-capturing fiber sheet from decreasing, the fusion fibers have a melting point lower than the melting point of all the constituent fibers other than the fused fibers. It is preferable to have a resin component having a low melting point (sometimes referred to as a low melting point component) on at least the fiber surface. This low melting point component is preferably at least 10 ° C. lower than the melting point of any constituent resin of the fibers other than the fused fibers in the high ammonia trapping fiber sheet, and more preferably at least 15 ° C. lower.

The fused fibers are also made of a polyolefin-based polymer such as polyethylene (for example, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, or ultra-high-molecular-weight polyethylene) so as to have excellent alkali resistance. , Polypropylene, polymethylpentene, ethylene-propylene copolymer, or ethylene-butene-propylene copolymer. If the ammonia high-capturing fiber sheet contains ultrahigh molecular weight polyethylene fibers as high strength fibers, the softening temperature of the ultrahigh molecular weight polyethylene fibers (for example, , 125 ° C.)
Preferably, the fused fibers are fused. Therefore, the fused fiber in this case preferably contains low-density polyethylene as a low-melting point component.

The fused fiber may be composed of a single resin component, or may be composed of two or more resin components. The latter fused fiber is preferable in that the tensile strength of the separator can be further improved. When composed of two or more types of resin components, the fiber cross-sectional shape can be, for example, a core-sheath type, side-by-side type, eccentric type, sea-island type, multiple bimetal type, or orange type.

The ratio of the ultrafine fibers, the high-strength fibers, and / or the fused fibers contained in the high ammonia-capturing fiber sheet constituting the separator for an alkaline battery of the present invention is not particularly limited. Usually, the ammonia high-capturing fiber sheet is made of 0 to 70 mass% of ultrafine fibers (preferably 1
0-70 mass%) and high-strength fiber 0-70 mass
% (Preferably 5 to 40% by mass) and 0 to 0
95 mass% (preferably 10 to 85 mass%). The ammonia high-capturing fiber sheet is preferably made of a combination of a high-strength fiber and a fusion fiber, or a combination of a high-strength fiber, a fusion fiber and a microfiber.

Further, the ammonia high-capturing fiber sheet constituting the separator for an alkaline battery of the present invention is a polyolefin-based fiber having a fineness exceeding 0.55 dtex, in addition to ultrafine fibers, high-strength fibers and / or fused fibers. , But not as microfibers, high-strength fibers, or fused fibers. When such a polyolefin-based fiber is used, an appropriate void is formed and gas permeability (for example,
A separator excellent in oxygen permeability).

The high ammonia-capturing fiber sheet constituting the alkaline battery separator of the present invention has an average ammonia trapping amount per unit mass of 0.4 mmol / g or more, preferably 0.45 mmol / g or more. , More preferably 0.5 mmol / g or more. If the average ammonia trapping amount is less than 0.4 mmol / g, the self-discharge suppressing effect may be low.

The “average ammonia trapping amount” in the present specification refers to the ammonia trapping amount measurement point 1 as described above.
It is an average value of 0 or more, and the following step (A) is performed for 10 or more arbitrary measurement points of the target fiber sheet.
To (D), the amount of trapped ammonia can be measured, and the average value thereof can be calculated.

(A) Pretreatment of test piece (1) About 2 g of a test piece is collected from a sample, and the mass (W; unit = g) of the collected test piece is measured (measured with an accuracy up to 0.001 g). . (2) Measure 120 ml of 8 mol / l-KOH aqueous solution with a measuring cylinder and pour into a 250 ml Erlenmeyer flask (with a glass stopper). (3) After the test piece is sufficiently moistened with pure water, it is sufficiently squeezed,
It is cut into small pieces of about 1 cm ² and placed in the Erlenmeyer flask (2). (4) Further, in the Erlenmeyer flask, 0.3 mol / l
-NH ₃ containing 8 mol / l-KOH aqueous solution (8 mol /
the l-KOH aqueous solution, NH ₃ which concentration was prepared by adding ammonium chloride to a 0.3 mol / l)
After accurately adding 5 ml with a pipette, quickly seal with a glass stopper and shake to mix the test piece sufficiently. (5) The Erlenmeyer flask containing the test piece is allowed to stand in a constant temperature bath at 40 ° C. for 3 days. (6) As a blank, two Erlenmeyer flasks different from the above (2) are prepared, and the above operations (2) to (5) are repeated except that the test piece is not put in the Erlenmeyer flask.

(B) Distillation of residual ammonia [Parnas.
Distillation by Micro-Kjeldahl Method Using Wagner Distillation Apparatus (See FIG. 1)] (1) Take out an Erlenmeyer flask from a thermostat, cool in tap water. (2) On the other hand, the Parnas-Wagner distillation apparatus 1 shown in FIG.
, Pure water is poured into the round bottom flask 11 for steam generation from the liquid injection tube 21 and boiled. Instead of using the tube 21, for example, pure water can be put into the round bottom flask 11 and then set in the distillation apparatus. (3) As a flask for capturing ammonia, 200 ml of pure water is put into a new 500 ml Erlenmeyer flask different from the Erlenmeyer flask of the above (1), and subsequently, 2.5 ml of 0.1 mol / l hydrochloric acid is injected using a burette. And then 10
After adding about drops of methyl red, this 500 ml Erlenmeyer flask is set in the Parnas-Wagner distillation apparatus 1 as the ammonia capturing flask 16. At this time, it is set so that the lower end of the guide tube 26 extending from the cooler 15 of the distillation apparatus is located in the liquid in the 500 ml Erlenmeyer flask 16. (4) 25 ml of the ammonia-containing solution is taken out of the Erlenmeyer flask of (1) with a pipette, and injected through the liquid inlet 13 of the Parnas-Wagner distillation apparatus 1. The injected ammonia-containing solution is guided into the vacuum bottle 14 through the guide tube 24. After flushing the liquid inlet 13 with pure water, the liquid inlet 13 is stopped with a clip 17.

(5) The pure water in the round bottom flask 11 of (2) is boiled to generate steam. The generated steam passes through the guide tube 22, the drainage device 12, the guide tube 23, and the guide tube 24 in this order, and is led to the vacuum bottle 14. This water vapor evaporates the ammonia contained in the ammonia-containing solution in the vacuum bottle, and the evaporated ammonia vapor is sent to the cooler 15 through the guide tube 25 attached to the upper part of the vacuum bottle 14 and condensed. Is done. The condensed ammonia is supplied to the induction pipe 2 extending from the cooler 15.
6 and collected in a 500 ml Erlenmeyer flask 16 for capturing ammonia. This ammonia distillation is performed for 10 minutes. (6) After completion of the ammonia distillation, the 500 ml Erlenmeyer flask 16 for capturing ammonia is removed from the Parnas-Wagner distillation apparatus 1. Guide tube 2 extending from cooler 15
6 was washed with distilled water.
1 Put in an Erlenmeyer flask.

(C) Titration (1) When the color of the solution in the 500 ml Erlenmeyer flask of the above (B) and (6) is pink (that is, when hydrochloric acid remains), the content of the flask is , 0.1 mol
/ L Potassium hydroxide aqueous solution is titrated by dropping from a burette until it turns yellow (0.1 m
It is referred to as V ₁ ol / l potassium hydroxide solution amount). When the color of the solution in the 500 ml Erlenmeyer flask (B) and (6) is yellow (that is, when hydrochloric acid does not remain), 0.1 mol / l hydrochloric acid is added to the flask in a reddish color. The titration is carried out by dropping from a burette until completion (the amount of dropped 0.1 mol / l hydrochloric acid is V ₂ ). (2) In the 500 ml Erlenmeyer flask prepared as a blank, all the acid in this Erlenmeyer flask is consumed and yellowed, so 0.1 mol / l hydrochloric acid is changed until reddish.
The titration is carried out by dropping from a burette (the dropped 0.1 mol / l hydrochloric acid amount is V ₀ ).

(D) Determination of Ammonia Capture Amount (1) Ammonia Capture Amount (C _p : Unit = mmol NH ₃ /
g) is calculated by the following formula (1): C _p = (n ₀ −n _p ) / W (1) [where n ₀ is calculated by the following formula (1a) and remained in a blank test. The amount of ammonia (mmolNH ₃ ), and n _p is the amount of ammonia n ₁ (mmolNH ₃ ) not captured by the test piece, calculated by the following formula (1b), or by the following formula (1c). Calculated ammonia amount n ₂ (mmolNH ₃ ) not captured by the test piece
). Here, n ₀ is an average value of two blanks.

Formula (1a): n ₀ = (125/25) × (2.5 + V ₀ ) × 0.1 (1a) Formula (1b): n ₁ = (125/25) × (2.5 −V ₁ ) × 0.1 (1b) Formula (1c): n ₂ = (125/25) × (2.5 + V ₂ ) × 0.1 (1c)

The ammonia-capturing fiber sheet constituting the alkaline battery separator of the present invention has a potassium ion exchange capacity per unit mass of preferably 0.3 to 2 m.
eq / g, and more preferably 0.4 to 1.7 meq.
/ G, most preferably 0.5 to 1.5 meq / g.
It is. If the potassium ion exchange capacity is less than 0.3 meq / g, the wettability tends to be poor. If the potassium ion exchange capacity exceeds 2 meq / g, potassium ions in the electrolyte are trapped, and the potassium ion concentration is reduced. Drop,
Battery life tends to be shorter.

The term “potassium ion exchange capacity” as used herein means a value calculated by a measuring method comprising the following steps (A) to (E). (A) Preparation of test piece (1) As a test piece, 50 mm × 2 from the width direction of the sample
Three test pieces of 00 mm are collected. (2) Measure the mass (W; unit = g) of each of the collected test pieces (measured with an accuracy up to 0.001 g).

(B) Pretreatment of test piece (1) A 1 mol / l hydrochloric acid aqueous solution is put into a plastic container with a lid. Note that the amount of the aqueous hydrochloric acid solution is set to an amount that the test piece placed in the plastic container with a lid sufficiently sinks in the next step (2). (2) After the test piece is sufficiently moistened with pure water, the test piece is placed in a plastic container with a lid and sealed. (3) The plastic container with the lid is placed in a thermostat at 60 ° C. for 1 hour. (4) After one hour, remove the test piece from the plastic container with the lid, and rinse thoroughly with pure water.

(C) Addition of alkali (1) New plastic container with lid (100 ml)
Then, the test pieces subjected to the pretreatment of the above (B) are rolled and placed one by one, and 90 ml of pure water is added. 0.1mo in it
Pipet exactly 10 ml of 1 / l potassium hydroxide standard solution, cover and gently shake. (2) As blanks, each 90 ml of pure water is poured into two plastic containers (100 ml) each having a lid different from the above (1), and 10 ml of a 0.1 mol / l potassium hydroxide standard solution is accurately poured therein. Pipette, cover, and shake lightly. (3) All the plastic containers with lids of (1) and (2) are placed in a thermostat at 60 ° C. for 2 hours. (4) After 2 hours, take out the plastic container, put it in water and return it to normal temperature (about 20 minutes).

(D) Titration (1) From a plastic container with a lid containing a test piece, only the liquid inside is transferred to a beaker (the test piece is left in the container while being impregnated). (2) The inside of the plastic container with the lid and the test piece are sufficiently washed with pure water, and the washing liquid is also added to the beaker of (1). (3) While stirring the solution in the beaker, add a few drops (about 2 drops) of a titration indicator phenolphthalene solution (the solution turns red). (4) A 0.1 mol / l hydrochloric acid standard solution is dropped from the burette, and titration is performed. (5) Read the value when the color of the solution changes from red to transparent [the titration of hydrochloric acid in the test piece: b (ml)]. (6) Repeat the above-mentioned operations (1) to (5) for two plastic containers with lids prepared as blanks, and titrate [blanche hydrochloric acid titration: c (ml)].

(E) Determination of potassium ion exchange capacity (1) Potassium ion exchange capacity (X: unit = meq /
g) is calculated by the following formula (2): [X (meq / g)] = {(c−b) × 0.1} / W (2) [where X is “ion exchange per unit weight” A), b is the “hydrochloric acid titer of the test piece”, c is the “blank hydrochloric acid titer”, and W is the “test piece weight W (g)”.
And the average (up to one decimal place) of the measured and calculated values of the three test pieces.

The graft ratio of the highly ammonia-trapping fiber sheet constituting the separator for an alkaline battery of the present invention is preferably 5 to 20%, more preferably 6 to 16%.
And most preferably 7 to 15%. When the graft ratio is less than 5%, the wettability tends to deteriorate. When the graft ratio exceeds 20%, the internal pressure increases, the electrode dies (drys out), or the potassium ion concentration increases. Tends to decrease. The term “graft ratio” in the present specification refers to a formula (3): [graft ratio (%)] = {A / (A + B)} × 100 (3) (where A is introduced by a graft polymerization treatment) B is the dry weight of the fiber sheet before the graft polymerization treatment is performed).

The high ammonia-capturing fiber sheet constituting the separator for an alkaline battery of the present invention is not limited to this. For example, (1) a graft-polymerizable monomer, oligomer, and / or polymer and .01
A step of performing a first graft polymerization treatment on a fiber sheet to which a graft polymerization solution containing 3 mass% of a surfactant is attached in the presence of oxygen (hereinafter, referred to as a first graft polymerization treatment step) And (2) a state in which the entire area of the upper surface and the lower surface of the fiber sheet that has been subjected to the first graft polymerization treatment step (hereinafter, referred to as a first graft polymerization treated fiber sheet) is covered with a non-breathable film, and And a step of performing a second graft polymerization treatment (hereinafter, referred to as a second graft polymerization treatment step).

The fiber sheet (that is, the fiber sheet before the graft polymerization solution is applied; hereinafter, referred to as “fiber sheet before treatment”) that can be used as a starting material in the production method of the present invention is, for example, a nonwoven fabric. , Woven or knitted fabric, or a composite thereof. A nonwoven fabric is preferable, and a nonwoven fabric is more preferable, since the fibers can be arranged three-dimensionally and are excellent in holding the electrolytic solution. Examples of the fibers constituting the unprocessed fiber sheet include polyolefin fibers (for example, polypropylene fibers or polyethylene fibers), polyamide fibers, vinylon fibers, vinylidene fibers, polyvinyl chloride fibers, polyester fibers,
An acrylic fiber or a polyurethane fiber can be used. Among these, it is preferable to use a polyolefin-based fiber because of its excellent alkali resistance.

The untreated fiber sheet can be easily produced by a conventional method. For example, a suitable nonwoven fabric can be manufactured as follows. That is, a fiber web is formed using the fibers (preferably polyolefin fibers) by a wet method or a dry method (for example, a card method, an air lay method, a melt blow method, a spun bond method, or the like). The fiber length generally varies depending on the method of forming the fiber web. For example, when the fiber web is formed by a wet method, the fiber length is 1.
When using a short fiber of about 25 mm to form a fiber web by a dry method (for example, a card method or an air lay method), it is common to use a long fiber having a fiber length of about 25 to 110 mm. is there. The fiber web can be composed of a single layer, or can be formed by laminating different types of fiber webs, such as laminating a fiber web by a wet method and a fiber web by a dry method, or laminating fiber webs having different fiber compositions. it can. In particular, a laminate of the fiber web formed by the wet method and the fiber web formed by the dry method has both the uniformity of the fiber web formed by the wet method and the strength of the fiber web formed by the dry method.

Next, the nonwoven fabric can be manufactured by bonding the fiber webs. Examples of the bonding method include (1) a method of entanglement by a fluid flow (for example, a water flow), and (2) a fusion fiber mixed as a fiber constituting a fiber web, and a part of the fusion fiber. Or a method of fusing them all, (3) a method of bonding partially or entirely with a binder, and (4) a method of using these together. As described above, when the fiber web by the wet method and the fiber web by the dry method are laminated, there is substantially no distinction between the fiber web by the wet method and the fiber web by the dry method. Preferably, they are entangled by a fluid stream (e.g., a water stream) so as to form a nonwoven fabric. In addition, in the case where the splitting fiber which can be split into the ultrafine fibers by the physical action is included, there is an effect that the splitting of the splittable fiber can be simultaneously performed by the fluid flow. Further, it is preferable to fuse the fused fibers because the tensile strength and the softness of the separator can be improved.

The graft polymerization solution used in the production method of the present invention comprises at least a graft-polymerizable monomer, oligomer and / or polymer and 0.01 to 3
mass% of a surfactant. Examples of the graft-polymerizable monomer include a vinyl monomer (that is, a monomer having a carbon-carbon double bond), and specific compounds of the vinyl monomer include, for example, unsaturated monocarboxylic acid. (For example,
Acrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid, vinyl acetic acid, methacrylic acid, angelic acid, tiglic acid, allylic acetic acid, α-ethyl crotonic acid,
Cinnamic acid, 10-undecenoic acid, oleic acid, elaidic acid, erucic acid, brassic acid, lume citric acid, sorbic acid, linoleic acid, eleostearic acid, linolenic acid,
Arachidonic acid, acetylene carboxylic acid, tetrolic acid, stearolic acid, behenolic acid, or xymenic acid) or a derivative (eg, esterified product) of the unsaturated monocarboxylic acid, unsaturated dicarboxylic acid (eg, maleic acid, fumaric acid, methyl Maleic acid, methyl fumaric acid, glutaconic acid, itaconic acid, allylmalonic acid, terraconic acid, muconic acid, or butynedioic acid) or a derivative (eg, esterified product) of the unsaturated dicarboxylic acid, unsaturated tricarboxylic acid (eg, aconitic acid) Or a derivative of the unsaturated tricarboxylic acid (eg, an esterified product), a heterocyclic vinyl monomer (eg, vinylpyridine or vinylpyrrolidone), or an aromatic vinyl monomer (eg,
Styrene). When styrene is used as the graft-polymerizable monomer, the second
It is preferable to further sulfonate after performing the graft polymerization treatment step.

Among these graft-polymerizable monomers, an unsaturated monocarboxylic acid or unsaturated dicarboxylic acid in which a carboxyl group is directly bonded to carbon having a double bond is preferable from the viewpoint of easy graft polymerization. Further, acrylic acid or methacrylic acid is more preferable in that the polymerization is easily controlled and good hydrophilicity is produced by graft polymerization.

The graft-polymerizable oligomer or polymer is, for example, a polymer of the above-described graft-polymerizable monomer, which is grafted to the pre-treatment fiber sheet and the first graft-polymerized fiber sheet. A polymerizable polymer can be used, and it is preferable to use polyacrylic acid, an oligomer of acrylic acid, polymethacrylic acid, or an oligomer of methacrylic acid from the viewpoint of reactivity.

In the production method of the present invention, when such a polymerizable monomer, oligomer, and / or polymer is attached to the fiber sheet before treatment, for example, (1)
A method of applying or spraying a solution containing a monomer, an oligomer, and / or a polymer on a fiber sheet before treatment, or (2) a method of immersing the fiber sheet before treatment in a solution containing a monomer, oligomer, and / or polymer And the like.

The graft polymerization liquid used in the production method of the present invention may contain a graft-polymerizable monomer, oligomer or polymer alone, or may contain a graft-polymerizable monomer, oligomer and / or polymer. May be contained in combination of two or more. The concentration of the graft-polymerizable monomer, oligomer, and / or polymer contained in the graft polymerization solution is not particularly limited, but may be 10 to 4%.
0 mass%, preferably 15 to 35mass
s%, more preferably 20 to 35 mass%.
Is more preferable. The concentration of the graft-polymerizable monomer, oligomer, and / or polymer is 10 ma
If it is less than ss%, it tends to be difficult to produce a separator having a graft ratio of 5% or more, and if the concentration of the graft-polymerizable monomer, oligomer, and / or polymer exceeds 40 mass%, the graft ratio is increased. Is 20%
It tends to be difficult to produce the following separators.

Surfactants which can be contained in the graft polymerization solution used in the production method of the present invention include:
For example, a nonionic surfactant (for example, polyoxyethylene alkyl ether or polyoxyethylene alkylphenol ether, higher alcohol or alkyl ethoxylate), or an anionic surfactant (for example, alkali metal salt of higher fatty acid, alkylsulfonic acid) Salt or sulfosuccinate salt). From the viewpoint of imparting wettability or battery performance, it is preferable to use a nonionic surfactant, and it is more preferable to use a higher alcohol or an alkyl ethoxylate.

The concentration of the surfactant contained in the graft polymerization solution used in the production method of the present invention is 0.01 to 0.01.
Although it is not particularly limited as long as it is 3 mass%, it is preferably 0.03 to 3 mass%, more preferably 0.05 to 1 mass%. If the surfactant concentration is less than 0.01 mass%, the obtained graft-polymerized fiber sheet tends to have poor wettability to an alkaline solution. If the surfactant concentration exceeds 3 mass%, it tends to be difficult to produce a separator having an average ammonia trapping amount of 0.4 mmol / g or more, and stickiness tends to occur, which is inconvenient in production. May occur.

The graft polymerization solution used in the production method of the present invention may contain, in addition to a graft-polymerizable monomer, oligomer and / or polymer and a surfactant, if necessary, for example, a chain transfer agent and / or An initiator may be included. For example, if a chain transfer agent is added to the graft polymerization solution, it is considered that the length of the graft chain can be shortened, and the unreacted homopolymer or the like is excellent in washing and removing properties, which is preferable in production. Further, using a graft polymerization solution containing a chain transfer agent,
It is preferable to perform the first graft polymerization treatment step (that is, the graft polymerization treatment in the presence of oxygen) since the self-discharge suppression effect tends to be excellent. When the self-discharge suppressing action is excellent, the graft ratio can be reduced, and as a result, the secondary effect of improving the oxidation resistance is also exerted.

As the chain transfer agent, for example, lower alcohols (eg, isopropyl alcohol), polyfunctional alcohols (eg, polyethylene glycol), or dicarboxylic acids (eg, maleic acid) can be used. It is preferable to use polyethylene glycol from the viewpoint of the influence on polyethylene glycol. In particular, it is preferable to use polyethylene glycol (degree of polymerization = 2000 or less). The degree of polymerization of the polyethylene glycol used is 20
If it exceeds 00, it becomes solid and it is difficult to disperse it uniformly. If it cannot be dispersed uniformly, the graft polymerization will not be performed uniformly, for example, the ammonia trapping property will be non-uniform. The lower limit of the degree of polymerization of the polyethylene glycol is about 100, and the degree of polymerization of the polyethylene glycol is more preferably 200 to 1,000.

The concentration of the chain transfer agent (particularly, polyethylene glycol) that can be contained in the graft polymerization solution used in the production method of the present invention is not limited to this, but should be 3 to 50 mass%. Is preferable, and more preferably 5 to 30 mass%.
More preferably, it is あ る 25 mass%. When the concentration of the chain transfer agent is less than 3 mass%, it tends to be difficult to produce a separator having an average ammonia trapping amount of 0.4 mmol / g or more. Inconvenience may occur. If the concentration of the chain transfer agent exceeds 50 mass%, the graft ratio tends to decrease, and the average amount of trapped ammonia tends to decrease.

The reaction initiator which can be contained in the graft polymerization solution used in the production method of the present invention includes:
For example, benzophenone, a peroxide (eg, benzoyl peroxide), or an azo compound can be used, and it is preferable to use benzophenone from the viewpoint of affecting battery performance. The concentration of the reaction initiator (particularly, benzophenone) that can be contained in the graft polymerization solution used in the production method of the present invention is not limited to this, but is preferably 0.05 to 1 mass%. ,
It is more preferably from 0.05 to 0.5 mass%, and still more preferably from 0.05 to 0.3 mass%. If the concentration of the initiator is less than 0.05 mass%, the graft polymerization tends not to proceed sufficiently. If the concentration of the initiator exceeds 1 mass%, the separator having an average ammonia trapping amount of 0.4 mmol / g or more is used. Tends to be difficult to manufacture.

The solvent (dispersion medium) of the graft polymerization solution used in the production method of the present invention is not particularly limited, and for example, water, alcohol, or acetone can be used. The above-mentioned liquid for graft polymerization can further contain a homopolymer formation inhibitor (for example, iron sulfate), if necessary.

If an extra graft polymerization solution is contained when the graft polymerization solution is adhered to the fiber sheet before treatment, the graft polymerization solution is unevenly distributed due to gravity, and as a result, the graft polymerization is unevenly distributed. Therefore, it is preferable to remove an excessive graft polymerization solution.
That is, when depositing the pretreatment fiber sheet in the graft polymerization solution, the graft polymerization solution, to the surface density 100 g / m ² of pretreatment fiber sheet, 40~250g / m ²
And more preferably 50 to 200 g / m ² . As a means for removing the excess graft polymerization solution, for example, a method of passing between a pair of rolls or a method of passing between flat plate presses can be used.

Before adhering the graft polymerization solution to the untreated fiber sheet, for example, ultraviolet irradiation, corona discharge, and / or plasma irradiation may be used to improve the compatibility between the graft polymerization solution and the untreated fiber sheet. It is preferable to perform the surface treatment of the untreated fiber sheet by discharging or the like.

In the first graft polymerization treatment step in the production method of the present invention, the first graft polymerization is carried out on the fiber sheet to which the liquid for graft polymerization has adhered in the presence of oxygen. In the case of the first graft polymerization in the presence of oxygen, it is sufficient that oxygen is present. For example, the first graft polymerization may be carried out in air, or may be carried out while supplying oxygen. Although it is possible, it is preferable to carry out in air in view of simplification of the production process (oxygen concentration is easily made constant).

Examples of the graft polymerization method in the first graft polymerization treatment step include irradiation with ultraviolet rays, irradiation with far infrared rays, irradiation with radiation (X-ray, α-ray, β-ray, or γ-ray), or thermal polymerization. Can be. Among these methods, graft polymerization can be performed only on the fiber surface,
In addition, ultraviolet irradiation is preferable because the radical generation time of the reaction initiator is short and the graft polymerization can be performed in a short time.

In the first graft polymerization treatment step, the first graft polymerization treatment can be carried out to such an extent that the liquid for graft polymerization does not completely evaporate. The graft polymerization treatment time in the first graft polymerization treatment step is, for example,
It can be appropriately determined according to the type of the graft polymerization method to be used, the conditions for performing the graft polymerization (for example, irradiation intensity), the graft ratio, or the ammonia capture ratio.

In the second graft polymerization treatment step in the production method of the present invention, the entire area of the upper surface and the lower surface of the first graft polymerization treated fiber sheet obtained by performing the first graft polymerization treatment step is not ventilated. In a state covered with a conductive film,
Further, a second graft polymerization treatment is performed to impart hydrophilicity. By covering the entire area of the upper surface and the lower surface of the first graft-polymerized fiber sheet with the air-impermeable film, the monomer, oligomer, and / or polymer evaporated from the first graft-polymerized fiber sheet are not diffused. 2
Can be carried out.

The non-breathable film is formed of a gas (in particular,
The film is not particularly limited as long as it is a film that does not allow passage of the vapor for the graft polymerization liquid), but the light transmittance at the absorption wavelength of the reaction initiator is high (for example, 80% or more). It is preferable to use a polyolefin-based film (for example, a polyethylene film or a polypropylene film). This is because if the light transmittance at the absorption wavelength of the reaction initiator is low, the progress of the polymerization reaction is hindered.

When the entire surface of the upper surface and the lower surface of the first graft-polymerized fiber sheet is covered with the air-impermeable film,
An inner space of the first graft-polymerized fiber sheet;
The first graft-polymerized fiber sheet is sandwiched between the air-impermeable films without applying pressure to the first graft-polymerized fiber sheet from both sides so as to allow the presence of air in the space near the outer surface of the graft-polymerized fiber sheet. That is, the second graft polymerization step is performed in the presence of oxygen. In addition, for the end portion of the first graft polymerization-treated fiber sheet and its periphery,
Cover with a non-breathable film (for example, a non-breathable film covering the upper surface of the first graft-polymerized fiber sheet;
The air-impermeable film covering the lower surface of the graft-polymerized fiber sheet may be continuous, or may not be covered with the air-impermeable film (for example, the first air-impermeable film).
The air-impermeable film covering the upper surface of the graft-polymerized fiber sheet and the air-impermeable film covering the lower surface of the first graft-polymerized fiber sheet may be separated.

In the second graft polymerization treatment step, the temperature is preferably 100 ° C. or more (more preferably, 1 ° C.).
Under a condition of 10 ° C. or higher). By setting the temperature at such a high temperature, it is possible to easily produce a high ammonia-trapping fiber sheet (separator) having excellent oxidation resistance and an average ammonia trapping amount of 0.4 mmol / g or more.

Examples of the graft polymerization method in the second graft polymerization treatment step include irradiation with ultraviolet rays, irradiation with far infrared rays, irradiation with radiation (X-ray, α-ray, β-ray, or γ-ray), or thermal polymerization. The method exemplified above for the graft polymerization method in the first graft polymerization treatment step can be used. The first graft polymerization in the first graft polymerization step (that is, the graft polymerization in the presence of oxygen) and the second graft polymerization in the second graft polymerization step (that is, the first graft polymerization step) (Graft polymerization in a state where the fiber sheet is in a closed state) may be the same or different in polymerization conditions other than the presence or absence of an air-impermeable film covering the first graft-polymerized fiber sheet.

In the second graft polymerization treatment step, the second graft polymerization treatment is carried out so that the average ammonia trapping amount is 0.4 m
mol / g or more (preferably 0.45 mmol / g or more, more preferably 0.5 mmol / g or more). The graft polymerization treatment time in the second graft polymerization treatment step can be appropriately determined according to, for example, the type of the graft polymerization method to be used, the conditions for performing the graft polymerization (for example, irradiation intensity), the graft ratio, or the ammonia capture ratio. it can.

The ratio of the treatment time (A) for the first graft polymerization to the treatment time (B) for the second graft polymerization (ie,
A: B) is not particularly limited, but is 1: 8 to
The ratio is preferably 5: 4, more preferably 2: 7 to 5: 4. Treatment time of first graft polymerization and second
If the ratio to the treatment time of the graft polymerization is shorter than 1: 8, the average amount of trapped ammonia may decrease. First
When the ratio of the treatment time of the graft polymerization to the treatment time of the second graft polymerization is longer than 5: 4, the graft polymerization hardly proceeds, the retention of the electrolyte decreases, and it is difficult to suppress self-discharge. As a result, the capacity retention ratio tends to decrease.

The fiber sheet obtained by performing the first and second graft polymerization treatment steps is, for example, water, hot water, hot water,
Alternatively, it is preferable to sufficiently wash with alcohol or the like. This is because the fiber sheet obtained by performing the first and second graft polymerization treatment steps contains some unreacted substances (for example, graft monomers, oligomers, and / or polymers).

The fiber sheet obtained by performing the first and second graft polymerization treatment steps may be subjected to a known hydrophilization method, for example, surfactant treatment, fluorine diluted with an inert gas such as nitrogen gas. Gas, oxygen gas, carbon dioxide gas, or a treatment with a mixed gas of at least one gas selected from a gas such as sulfur dioxide gas, or further hydrophilizing by a method such as a discharge treatment, the injection rate of the electrolytic solution. Speed up and improve battery productivity. In the surfactant treatment step, the surfactant is preferably attached in an amount of 0.1 to 3 mass%, more preferably 0.2 to 1.5 mass%, based on the mass of the separator. More preferably, it is deposited in an amount of 0.3 to 1.2 mass%.

The separator for an alkaline battery of the present invention is excellent not only in the self-discharge suppressing action but also in the wettability and the capacity retention ratio. Therefore, the separator for an alkaline battery of the present invention has a nickel-
It can be suitably used for batteries such as cadmium batteries and nickel-hydrogen batteries. Of course, other alkaline batteries, for example, alkaline primary batteries (for example, alkaline manganese batteries, mercury batteries, silver oxide batteries, or air batteries) or alkaline secondary batteries (for example, silver-zinc batteries, silver-cadmium batteries, nickel- It can also be suitably used as a separator for a zinc battery or a rechargeable alkaline manganese battery).

[0071]

EXAMPLES The present invention will be described below in more detail with reference to examples, but these examples do not limit the scope of the present invention.

Example 1 A core-sheath type fused fiber (fineness = 0.8 dtex, fiber length = 5 mm) whose core component is made of polypropylene and whose sheath component is made of high-density polyethylene (melting point: 132 ° C.)
80 mass% and high strength polypropylene fiber (fineness =
2.2dtex, fiber length = 10mm, tensile strength = 8c
(N / dtex) of 20 mass% was dispersed to form a fiber web by a wet papermaking method. Then
After heat treating this fiber web at 136 ° C., a linear pressure of 10
High-density polyethylene, which is a sheath component of the core-sheath type fused fiber, was fused between N / cm (normal temperature) rolls to form a non-processed nonwoven fabric.

On the other hand, from the following components (1) to (6),
A liquid for graft polymerization was prepared. In addition, iron sulfate was added as a homopolymer formation inhibitor. (1) Acrylic acid monomer 30 mass% (2) Benzophenone 0.1 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 0.5 mass% (5) Polyethylene glycol (degree of polymerization: 400) 10 mass% (6) Water 59 mass%

Then, after impregnating the non-woven fabric before treatment with the graft polymerization solution (the surface density of the non-woven fabric is 100 g / m ^2).
Respect, containing the graft polymerization solution at a rate of 80 g / m ^2), at an intensity of 180 mW / cm ² from a metal halide mercury lamps which are arranged one on each side of the nonwoven fabric for 15 seconds with ultraviolet rays of 365nm centered in air irradiation Then, acrylic acid was graft-polymerized. Next, the first graft-polymerized non-woven fabric is sandwiched between two non-breathable films so as not to exclude air from the internal space and the space near the outer surface of the first graft-polymerized non-woven fabric,
Irradiation of ultraviolet rays with a center of 365 nm was performed for 15 seconds at an illuminance of 180 mW / cm ² from a metal halide mercury lamp arranged one on each side of the first graft polymerization-treated nonwoven fabric,
Acrylic acid was further polymerized on the graft polymer bonded in the above step. At this time, the temperature of the first graft-polymerized nonwoven fabric was 110 ° C., and the graft-polymerization liquid was in a state of evaporating from all sides of the two impermeable films.
Next, the graft-polymerized nonwoven fabric is sufficiently washed with water, dried, and calendered at a linear pressure of 10 N / cm to obtain the separator of the present invention (area density = 60.8 g / m ² , thickness =
0.15 mm, graft ratio = 9.8%).

[0074]

Example 2 The separator of the present invention (area density = 60.8) was obtained by repeating the procedure of Example 1 except that a graft polymerization solution prepared from the following components was used.
g / m ² , thickness = 0.15 mm, graft ratio = 9.8
%). (1) Acrylic acid monomer 30 mass% (2) Benzophenone 0.1 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 0.1 mass% (5) Polyethylene glycol (degree of polymerization: 400) 10 mass% (6) Water 59.4 mass%

[0075]

Example 3 The procedure of Example 1 was repeated to obtain a separator of the present invention (area density = 60.8), except that a graft polymerization solution prepared from the following components was used.
g / m ² , thickness = 0.15 mm, graft ratio = 9.8
%). (1) Acrylic acid monomer 30 mass% (2) Benzophenone 0.1 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 0.05 mass% (5) Polyethylene glycol (degree of polymerization: 400) ) 10 mass% (6) Water 59.45 mass%

[0076]

EXAMPLE 4 The procedure of Example 1 was repeated to obtain a separator of the present invention (area density = 60.8), except that a graft polymerization solution prepared from the following components was used.
g / m ² , thickness = 0.15 mm, graft ratio = 9.8
%). (1) Acrylic acid monomer 30 mass% (2) Benzophenone 0.1 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 1 mass% (5) Polyethylene glycol (degree of polymerization: 400) 10 mass % (6) Water 58.5 mass%

[0077]

Example 5 The procedure of Example 1 was repeated to obtain a separator of the present invention (area density = 60.8), except that a graft polymerization solution prepared from the following components was used.
g / m ² , thickness = 0.15 mm, graft ratio = 9.8
%). (1) Acrylic acid monomer 25 mass% (2) Benzophenone 0.3 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 3 mass% (5) Polyethylene glycol (degree of polymerization: 400) 10 mass % (6) Water 61.3 mass%

[0078]

[Comparative Example 1] A core-sheath type fusion-bonded fiber (fineness = 1.2 dtex, fiber length = 10 m) in which the core component is made of polypropylene and the sheath component is made of high-density polyethylene (melting point: 132 ° C.)
m; high-density polyethylene occupies 100% of the fiber surface)
From the slurry in which 100 mass% was dispersed, a fiber web was formed by a wet papermaking method. Next, after the fiber web is heat-treated at 136 ° C., high-density polyethylene, which is a sheath component of the core-sheath type fused fiber, is fused between rolls (at room temperature) at a linear pressure of 10 N / cm to form a non-woven fabric before treatment. Formed.

On the other hand, from the following components (1) to (5),
A liquid for graft polymerization was prepared. (1) Acrylic acid monomer 25 mass% (2) Benzophenone 0.3 mass% (3) Iron sulfate 0.4 mass% (4) Nonionic surfactant 3 mass% (5) Water 71.3 mass%

Next, after impregnating the non-woven fabric before treatment with the graft polymerization solution (area density of the non-woven fabric is 100 g / m ^2).
Respect, containing the graft polymerization solution at a rate of 80 g / m ^2), the non-woven fabric, so as to exclude air from the space of the inner space and outer surface vicinity of the nonwoven fabric was sandwiched between a non-breathable film, the nonwoven fabric At an illuminance of 180 mW / cm ² from a metal halide mercury lamp arranged one on each side of
Acrylic acid was graft-polymerized by irradiating an ultraviolet ray having a nm center for 30 seconds. Next, the graft-polymerized nonwoven fabric is sufficiently washed with water, dried, and calendered at a linear pressure of 10 N / cm to obtain a separator for comparison (area density = 59.8).
g / m ² , thickness = 0.15 mm, graft ratio = 10.5
%).

[0081]

[Evaluation of Physical Properties] (1) Measurement of Ammonia Capture Amount The ammonia capture amount of the separator of the present invention manufactured in Examples 1 to 5 and the comparative separator manufactured in Comparative Example 1 were measured. The measurement was performed for each separator.
This was performed using 10 samples. Table 1 shows the results. In Table 1, the values in parentheses indicate the minimum and maximum values of 10 data, and the values above them indicate the average value of 10 data. The unit is “mmol / g”.

(2) Measurement of capacity retention ratio As a current collector of an electrode, a paste-type nickel positive electrode (33 mm width, 182 mm length) using a foamed nickel base material and a paste-type hydrogen storage alloy negative electrode (mesh metal alloy, 3
3 mm width, 247 mm length). Next, after each separator prepared in Examples 1 to 5 and Comparative Example 1 was cut into a width of 35 mm and a length of 410 mm, each separator was sandwiched between a positive electrode and a negative electrode, and spirally wound to form an SC.
An electrode group corresponding to the type was created. After this electrode group was housed in an outer can, 5 mol / l potassium hydroxide and 1 mol / l lithium hydroxide were injected into the outer can as an electrolytic solution and sealed to form a cylindrical nickel-hydrogen battery.

Next, each cylindrical nickel-metal hydride battery was charged at 0.1 C to 150% of its capacity,
The battery was discharged at 0.1 C, and the initial capacity (A) at a final voltage of 1.0 V was measured. Then, at 0.1 C, 1
After being charged 50%, the battery was left in a constant temperature room at a temperature of 65 ° C. for 5 days. Thereafter, the battery was discharged again at 0.1 C, and the capacity (B) at a final voltage of 1.0 V was measured. From these results, the capacity retention ratio (C) was calculated by the following equation (4): C (%) = (B / A) × 100 (4) The measurement was performed on 10 samples for each separator. Was performed using

Table 1 shows the results. In Table 1, the numerical values in parentheses indicate the minimum and maximum values of the ten data,
The numerical value above it indicates the average value of 10 data. The unit is “%”. As shown in Table 1, the separator of the present invention has a high capacity retention rate and a small variation in the capacity retention rate, so that the separator is stable in quality.

<< Table 1 >> Average Ammonia Capture Amount Capacity Retention Rate Example 1 0.55 61 (0.53 to 0.58) (58 to 62) Example 2 0.58 62 (0.56 to 0.60) (60-63) Example 3 0.63 63 (0.62-0.64) (62-64) Example 4 0.486 (0.40-0.52) (50-62) Example 5 0.435 58 (0.38 to 0.48) (48 to 61) Comparative Example 1 0.35 45 (0.32 to 0.38) (42 to 48)

[0086]

As described above, the separator for an alkaline battery of the present invention comprises:
In addition to being excellent in self-discharge suppressing action, it has excellent properties in variations in wettability and capacity retention. According to the production method of the present invention, the alkaline battery separator of the present invention having such excellent characteristics can be produced.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an apparatus used for measuring an amount of captured ammonia.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Parnas-Wagner distillation apparatus; 11 ... round bottom flask; 12 ... drainer; 13 ... liquid inlet;
4 ... vacuum bottle; 15 ... cooler; 16 ... ammonia capture flask; 17 ... clip;
-Injection pipe; 22, 23, 24, 25, 26 ... guide pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Kato 7-city Kitatone, Sowa-cho, Sarushima-gun, Ibaraki Prefecture Within Japan Vilene Co., Ltd. (72) Yasuhiro Ito 7-city Kitatone, Sowa-cho, Sarushima-gun, Ibaraki Inside the Vilene Co., Ltd. (72) Inventor Hiroaki Yamazaki 7th, Kitatone, Sowa-cho, Sarushima-gun, Ibaraki Japan F-term in the Vileen Co., Ltd. 5H021 BB01 BB02 BB05 BB08 BB12 BB13 BB15 BB19 CC02 EE04 EE16 EE34 HH00 HH01 HH06 HH07 HH10

Claims (10)

[Claims] An average amount of captured ammonia is 0.4 mmol.
/ G or more, wherein the separator for an alkaline battery comprises a fiber sheet. 2. A potassium ion exchange capacity of 0.3 to 2 m.
The separator for an alkaline battery according to claim 1, comprising a fiber sheet of eq / g. 3. The alkaline battery separator according to claim 1, wherein the fiber sheet is a graft-polymerized fiber sheet. 4. The alkaline battery separator according to claim 3, wherein the graft ratio is 5 to 20%. 5. A fiber sheet to which a graft polymerization solution containing a graft-polymerizable monomer, oligomer, and / or polymer and 0.01 to 3% by mass of a surfactant is adhered is graft-polymerized in the presence of oxygen. After the treatment, in a state where the entire area of the upper surface and the lower surface of the fiber sheet is covered with the air-impermeable film, further graft polymerization is performed to prepare a graft-polymerized fiber sheet for an alkaline battery separator. To manufacture a separator for an alkaline battery. 6. The method according to claim 5, wherein the concentration of the graft-polymerizable monomer, oligomer, and / or polymer contained in the graft polymerization solution is 10 to 40 mass%. 7. The method according to claim 7, wherein the graft polymerization liquid is 3 to 50 ma.
The production method according to claim 5, further comprising ss% of a chain transfer agent. 8. The method according to claim 7, wherein the chain transfer agent is polyethylene glycol. 9. The method according to claim 9, wherein the graft polymerization liquid is 0.05 to 1%.
9. The composition according to claim 5, further comprising a mass% of a reaction initiator.
The production method according to any one of the above. 10. The graft polymerization treatment performed in a state in which the entire area of the upper surface and the lower surface of the fiber sheet is covered with an air-impermeable film is performed at a temperature of 100 ° C. or higher. The production method according to claim 1.