JP4331704B2 - Gelling agent for alkaline battery and alkaline battery - Google Patents

Description

  The present invention relates to an alkaline battery gelling agent and an alkaline battery. More specifically, the present invention relates to a gelled negative electrode alkaline battery gelling agent used as a negative electrode gelling agent of an alkaline battery mainly composed of an alkaline electrolyte and zinc powder, and an alkaline battery using the same.

Conventionally, a high-concentration alkaline electrolyte (high-concentration potassium hydroxide aqueous solution, containing zinc oxide if necessary) and zinc powder and / or zinc alloy powder are mainly used for the cathode of alkaline batteries. For the purpose of preventing sedimentation of zinc powder and the like in an alkaline electrolyte, a gel using a water-absorbing resin obtained by insolubilizing poly (meth) acrylic acid and its salts with a crosslinking agent has been proposed. (Patent Documents 1 to 3). Furthermore, from the viewpoint of preventing sedimentation of zinc powder, preventing liquid leakage from the battery, and improving the production efficiency of the battery, a powder having a relatively large particle diameter and suppressing the spinnability has been proposed (Patent Document 4).
Japanese Patent Publication No. 8-28216 Japanese Patent Publication No.8-12775 Japanese Patent Laid-Open No. 10-50303 Japanese Patent No. 3323468

However, alkaline batteries using these water-absorbent resin gelling agents are not always satisfactory in terms of maintaining long-term discharge characteristics (discharge amount and discharge time) and impact resistance, which are the most important characteristics of alkaline batteries. I couldn't.
An object of the present invention is to provide an alkaline battery gelling agent excellent in maintaining long-term discharge characteristics (discharge amount and discharge time) and excellent in impact resistance, and an alkaline battery using the same.

The gelling agent for alkaline batteries of the present invention comprises a crosslinked polymer (A) having (meth) acrylic acid (salt) as a main constituent monomer unit, and (A) is an alkaline and hydrolyzable crosslinking agent. (B) a unit and a crosslinking agent (c) unit that is alkaline and does not hydrolyze, and the gel (GA) has a viscosity ratio (N1 / N60) of 0.7 to 1.3, and 37% by weight of hydroxide. The gist of the present invention is that it comprises a gelling agent whose amount of soluble component in an aqueous potassium solution is 30% by weight or less.
Viscosity ratio of gel (GA) (N1 / N60): 100 parts by weight of 37% by weight aqueous potassium hydroxide solution, 2 parts by weight of crosslinked polymer (A) and 200 parts by weight of zinc powder were uniformly stirred and mixed at 40 ° C. GA) was prepared, and the viscosity (40 ° C., N1) after leaving the gel (GA) for 1 day and the viscosity after standing for 60 days (40 ° C., N60) at the same temperature in accordance with JIS K7117-1: 1999. Obtain from the measured value.

The gelling agent of the present invention and the alkaline battery using the same have the following effects.
(i) When used in an alkaline battery, a battery having excellent discharge duration and impact resistance can be produced over a long period of time.
(ii) Since the alkaline electrolyte to which the gelling agent of the present invention is added is good in running out of liquid, it can sufficiently cope with the high-speed filling of the alkaline electrolyte due to the recent increase in battery production speed.
(iii) Since there is little variation in the filling amount of the electrolytic solution per battery at the time of filling, a battery having uniform quality can be produced even during mass production.
(iv) Almost no hydrogen gas is generated even when it comes into contact with zinc powder in an alkaline electrolyte, so there is no risk of the electrolyte flowing out or damaging the battery due to an increase in pressure inside the battery.
(v) Even in a battery having a small size, the negative electrode gel can be filled uniformly and at high speed, so that a battery having uniform quality can be produced.

The gelling agent of the present invention comprises a crosslinked polymer (A) having (meth) acrylic acid (salt) as a main constituent monomer unit, and the gel (GA) has a viscosity ratio (N1 / N60) of 0.7 to 0.7. 1.3 and 37% by weight The amount of a soluble component in an aqueous potassium hydroxide solution is 30% by weight or less.
Viscosity ratio of gel (GA) (N1 / N60): 100 parts by weight of 37% by weight aqueous potassium hydroxide solution, 2 parts by weight of crosslinked polymer (A) and 200 parts by weight of zinc powder were uniformly stirred and mixed at 40 ° C. GA) was prepared, and the viscosity (40 ° C., N1) after leaving the gel (GA) for 1 day and the viscosity after standing for 60 days (40 ° C., N60) at the same temperature in accordance with JIS K7117-1: 1999. It calculates | requires by following Formula from the measured value.
Viscosity ratio (N1 / N60) = (40 ° C., N1) / (40 ° C., N60)
The viscosity ratio (N1 / N60) is usually 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1. Within this range, since the zinc powder in the electrolytic solution is more difficult to settle, the discharge characteristics and impact resistance are further improved. Further, if the amount of the soluble component of the gelling agent is 30% by weight or less, the spinnability of the alkaline aqueous solution can be prevented from increasing or the viscosity can be prevented from decreasing over a long period.

  In the gelling agent of the present invention, among the swollen particles (BA) obtained by uniformly mixing 2 parts by weight of the crosslinked polymer (A) and 300 parts by weight of a 37% by weight aqueous potassium hydroxide solution at 25 ° C., the particle diameter is 32 to When the 1,000 μm swollen particles are at least 80% by weight based on the total weight of the swollen particles (BA), impact resistance is further improved, which is preferable.

  The absorption amount after 1 hour of the 37% by weight potassium hydroxide aqueous solution by the tea bag method is preferably 20 to 60 g / g, more preferably 23 to 50 g / g, and particularly preferably 25 to 40 g / g. . Within this range, the discharge characteristics of the battery are improved, and the uneven injection amount of the electrolyte per battery when the alkaline electrolyte containing the gelling agent is injected into the battery at a high speed is reduced.

The gelling agent of the present invention preferably has a gel (GA) viscosity (40 ° C., N1) of 30 to 300 Pa · s, more preferably 40 to 300 Pa · s, particularly preferably 50 to 200 Pa · s, Most preferably, it is 60-100 Pa.s.
When it is 30 or more, the discharge characteristics of the obtained alkaline battery are further improved. When it is 300 or less, the high-speed filling property of the electrolyte into the battery is excellent.

In the gelling agent of the present invention, the content of a metal element having a lower ionization tendency than zinc is preferably 15 × 10 ⁻⁴ wt% or less, more preferably 12 × 10 ⁻⁴ wt% or less, particularly preferably 10 × 10 ^{− 4} % by weight or less. Within this range, depending on the structure and capacity of the battery used and the amount of gelling agent added to the battery, a battery is formed between the zinc powder and the mixed metal ions in the battery, and hydrogen is generated by electrolysis. This is preferable because the pressure inside the battery due to the generation of gas, the outflow of the alkaline electrolyte, the damage of the battery, and the like can be prevented.

Moreover, as the gelling agent for alkaline batteries of the present invention, an aqueous solution polymerization method or reverse phase using a crosslinking agent (b) that decomposes under alkalinity and an allyl ether type crosslinking agent (c) having 2 to 10 allyl groups in combination. A water-swellable gelling agent comprising a cross-linked polymer (A) obtained by a suspension polymerization method and comprising (meth) acrylic acid (salt) as a main constituent monomer unit, wherein (b) and It is also preferable that each amount of (c) is 0.05 to 3% with respect to the weight of (meth) acrylic acid and its alkali metal salt and satisfy the following requirements (1) and (2).
Requirement (1): When the gelling agent is swollen in a 37% strength by weight potassium hydroxide aqueous solution, there should be 80% by weight or more of swollen particles having a particle size of 32 to 1,000 μm. Requirement (2); Tea bag method The absorption amount of the 37% strength by weight potassium hydroxide aqueous solution after 1 hour is 20 to 60 g / g. Requirement (1) is suitable for improving impact resistance and inserting a gelling agent into a battery. The requirement (2) is to improve the discharge characteristics of the battery and to reduce the unevenness of the injection amount of the electrolyte per battery when the alkaline electrolyte containing the gelling agent is rapidly injected into the battery. This is a suitable requirement.

The crosslinked polymer (A) can be obtained by polymerizing mainly (meth) acrylic acid (salt) in the presence of a crosslinking agent.
In the present invention, (meth) acrylic acid means acrylic acid and / or methacrylic acid, and "... acid (salt)" means "... acid" and / or "... acid salt". Means. Examples of the salt include alkali metal salts such as potassium, sodium and lithium, and alkaline earth metal salts such as calcium. A salt can be formed by neutralizing acrylic acid or methacrylic acid.
Since the gelling agent of the present invention is used in a high concentration alkaline aqueous solution, the (meth) acrylic acid (salt) unit contained in the crosslinked polymer (A) is an unneutralized product {(meth) acrylic acid unit}. Even if it is a neutralized body {(meth) acrylate unit}, the adhesiveness of the crosslinked polymer (A) can be reduced, the dispersibility can be improved, and the crosslinked polymer (A) can be produced. For the purpose of improving workability in the process, it is preferable to neutralize a part or all of the (meth) acrylic acid unit to obtain a (meth) acrylate unit.

When neutralizing the (meth) acrylic acid unit as necessary, usually an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide or lithium hydroxide, an alkaline earth metal hydroxide such as calcium hydroxide or an aqueous solution thereof. What is necessary is just to add to the monomer stage before superposition | polymerization, or the water-containing gel after superposition | polymerization, However, Since the crosslinking agent (c) which is the alkali and does not hydrolyze later mentioned has poor water solubility of a crosslinker, neutralization of (meth) acrylic acid When the polymerization is carried out at a high degree, the crosslinking agent (c) is separated from the aqueous monomer solution even if a predetermined amount of the crosslinking agent (c) is added, and the predetermined crosslinking cannot be carried out to obtain a crosslinked polymer (A) having the prescribed physical properties. In some cases, the degree of neutralization of (meth) acrylic acid is set to 0 to 30 mol%, and the polymerization is carried out by adding the crosslinking agent (c). If necessary, an alkali metal hydroxide is added to the hydrogel. Add inside If you adjust the degree is more preferable.
Final neutralization degree of (meth) acrylic acid (salt) unit of crosslinked polymer (A) in the present invention {acrylic acid based on the total number of moles of (meth) acrylic acid unit and (meth) acrylate unit The salt unit content (mol%)} is preferably 30 to 100, more preferably 40 to 90, and particularly preferably 50 to 90. Within this range, the impact resistance and discharge characteristics of the alkaline electrolyte are further improved.

The cross-linked polymer (A) can be obtained by polymerizing a monomer mainly composed of (meth) acrylic acid (salt). If necessary, it can be copolymerized with another monomer copolymerizable therewith. Also good. Other monoethylenically unsaturated monomers are not particularly limited as long as they are copolymerizable, but are preferably water-soluble, more preferably water-soluble ethylenically unsaturated monomers. As a water-soluble ethylenically unsaturated monomer,
Carboxylic acid (salt) monomers such as maleic acid (salt), fumaric acid (salt) and itaconic acid (salt);
Sulfonic acid (salt) monomers such as 2-acrylamido-2-methylpropanesulfonic acid (salt), sulfoalkyl (meth) acrylate and 4-vinylbenzenesulfonic acid (salt);
Amide monomers such as (meth) acrylamide, N-alkyl (C1-C3) substituted (meth) acrylamide [N-methylacrylamide, N, N-dimethylacrylamide, etc.] and N-vinylacetamide;
Alcohol monomers such as monohydroxyalkyl (C1-3) mono (meth) acrylate;
Polyethylene glycol (degree of polymerization: 2 to 100) mono (meth) acrylate, polypropylene glycol (degree of polymerization: 2 to 100) mono (meth) acrylate, methoxypolyethylene glycol (degree of polymerization: 2 to 100) mono (meth) acrylate, etc. Ether monomer;
Examples thereof include ester monomers such as alkyl (C1-5) (meth) acrylate and vinyl acetate. These ethylenically unsaturated monomers may be used in combination of two or more.
The content (% by weight) of the ethylenically unsaturated monomer unit other than (meth) acrylic acid (salt) is preferably 0 to 50, more preferably 0, based on the weight of the crosslinked polymer (A). -40, particularly preferably 0-30. Within this range, the viscosity stability over time is excellent, and the impact resistance and discharge characteristics of the alkaline battery are further improved.

The crosslinked polymer (A) is usually crosslinked using a crosslinking agent. The crosslinking agent is not particularly limited as long as it is usually used in the production of a polymer, but an alkaline and hydrolyzable crosslinking agent (b) or an alkaline and nonhydrolyzing crosslinking agent (c) is preferred. More preferably, it is a crosslinking agent containing a crosslinking agent (b) and a crosslinking agent (c).
By using the cross-linking agent (b) and the cross-linking agent (c) in combination, the viscosity stability of the gelling agent can be further improved and the separation of the alkaline electrolyte can be prevented, so that a long-term discharge can be maintained. be able to. Further, it can be uniformly injected when filling the battery, and the deviation of the injection amount of the electrolyte solution per battery is reduced, which is preferable. Here, the separation of the alkaline electrolyte is a phenomenon in which the gelling agent and the alkaline electrolyte cannot be maintained in a substantially uniform mixed state, and the gelling agent and the alkaline electrolyte are separated.

The crosslinker (b) unit only needs to have a hydrolyzable bond, and the hydrolyzable bond may be a bond that the crosslinker (b) originally has in the molecule or constitutes the crosslinked polymer (A). A bond formed by a crosslinking reaction with the monomer to be hydrolyzed may be used. Preferably, the crosslinking agent (b) is one in which 1% by weight of a gelling agent is added to a 37% aqueous potassium hydroxide solution at room temperature and 50% by weight or more decomposes when stirred for 1 hour.
Examples of the hydrolyzable bond include an ester bond and an amide bond.
Examples of the crosslinking agent (b) having a hydrolyzable bond in the molecule include N, N′-methylenebisacrylamide, ethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, and trimethylolpropane. 2-10 in a molecule such as tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate and pentaerythritol tetra (meth) acrylate, polyglycerin (degree of polymerization 3-13) polyacrylate Examples thereof include a copolymerizable crosslinking agent (b1) having an ethylenically unsaturated bond.
Among the crosslinking agents (b1), N, N′-methylenebisacrylamide, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate, more preferably N, N '-Methylenebisacrylamide, ethylene glycol di (meth) acrylate and trimethylolpropane tri (meth) acrylate, particularly preferably N, N'-methylenebisacrylamide and trimethylolpropane tri (meth) acrylate.
Examples of hydrolyzing bonds generated by crosslinking reaction include polyvalent glycidyl compounds (such as ethylene glycol diglycidyl ether), polyvalent isocyanate compounds (such as 4,4′-diphenylmethane diisocyanate), and polyvalent amine compounds (such as ethylenediamine). And a reactive crosslinking agent (b2) that reacts with a carboxylic acid represented by a polyhydric alcohol compound (such as glycerin). The reactive crosslinking agent (b2) can react with (meth) acrylic acid (salt) to form an ester bond or an amide bond.
Among the crosslinking agents (b), a polyvalent glycidyl compound which is preferably one of a copolymerizable crosslinking agent (b1) and a reactive crosslinking agent (b2) can be mentioned, and more preferably ethylene glycol diglycidyl ether. is there.
When the reactive crosslinking agent (b2) is used, it is generally heated at an optional stage after the addition of the crosslinking agent, preferably at 100 to 230 ° C., more preferably 120 to 160 ° C. to advance the crosslinking reaction. is there. Further, the reactive crosslinking agent (b2) may be used in combination with two or more kinds within a predetermined amount, and further with the copolymerizable crosslinking agent (b1).

The crosslinking agent (c) that is alkaline and does not hydrolyze does not have a hydrolyzable bond in the molecule and does not generate a hydrolyzable bond by a crosslinking reaction. Examples of such a crosslinking agent (c) include a crosslinking agent (c1) having two or more vinyl ether bonds and a crosslinking agent (c2) having two or more allyl ether bonds. Preferably, from the viewpoint of reactivity and the like, a crosslinking agent having two or more allyl ether bonds.
Examples of the crosslinking agent (c1) having two or more vinyl ether bonds include ethylene glycol divinyl ether, 1,4-butanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, 1,6-hexanediol divinyl ether, polyethylene Examples include glycol divinyl ether (polymerization degree 2 to 5), bisphenol A divinyl ether, pentaerythritol trivinyl ether, sorbitol trivinyl ether, polyglycerin (polymerization degree 3 to 13) polyvinyl ether, and the like.
The crosslinking agent (c2) having two or more allyl ether bonds includes a crosslinking agent (c21) having two allyl groups and no hydroxyl group in the molecule, two hydroxyl groups in the molecule and a hydroxyl group. 1-5 crosslinkers (c22), 3-10 allyl groups in the molecule and no hydroxyl groups, (c23), 3-10 allyl groups in the molecules and hydroxyl groups And a cross-linking agent (c24) having 1 to 3 or the like. When a hydroxyl group is included in the molecule, the compatibility with (meth) acrylic acid (salt) is good, the uniformity of crosslinking is improved, the stability of the gelling agent is improved, and the alkaline electrolyte containing the gelling agent is improved. Long-term stability of viscosity is even better.
As the crosslinking agent (c21) having two allyl groups in the molecule and not containing a hydroxyl group, diallyl ether, 1,4-cyclohexanedimethanol diallyl ether, alkylene (2 to 5 carbon atoms) glycol diallyl ether, and polyethylene Examples include glycol (weight average molecular weight: 100 to 4000) diallyl ether and the like.
Examples of the crosslinking agent (c22) having 2 allyl groups and 1 to 5 hydroxyl groups in the molecule include glycerin diallyl ether, trimethylolpropane diallyl ether, pentaerythritol diallyl ether, and polyglycerol (degree of polymerization: 2 to 5). Examples include diallyl ether.
Examples of the crosslinking agent (c23) having 3 to 10 allyl groups in the molecule and having no hydroxyl group include trimethylolpropane triallyl ether, glyceryl triallyl ether, pentaerythritol tetraallyl ether, and tetraallyloxyethane. Can be mentioned.
As the crosslinking agent (c24) having 3 to 10 allyl groups and 1 to 3 hydroxyl groups in the molecule, pentaerythritol triallyl ether and diglyceryl triallyl ether, sorbitol triallyl ether, polyglycerol (degree of polymerization) 3-13) and polyallyl ether.
Two or more kinds of the crosslinking agent (c) which is alkaline and does not hydrolyze may be used in combination. Of the cross-linking agents (c), cross-linking agents (c2) having preferably two or more allyl ether bonds, more preferably cross-linking agents having 1 to 5 hydroxyl groups and 2 to 10 allyl groups {(c22) and ( c24)}, particularly preferably a crosslinking agent having 3 to 10 allyl groups and 1 to 3 hydroxyl groups (c24), most preferably a crosslinking agent having 3 to 5 allyl groups and 1 to 3 hydroxyl groups (Pentaerythritol triallyl ether, sorbitol triallyl ether, etc.) (c25). When these cross-linking agents are used, compatibility with (meth) acrylic acid (salt) is good, and since the number of allyl groups is large, the low copolymerization characteristic of allyl groups can be covered and efficient crosslinking can be performed. Therefore, it is preferable.

  When the cross-linked polymer (A) contains a cross-linking agent (b) unit, the content of the cross-linking agent (b) unit depends on the type of the cross-linking agent (b) and the average degree of polymerization. The amount is 0.05 to 3% by weight, preferably 0.1 to 1% by weight, based on the weight of the combination (A). Within this range, separation of the alkaline electrolyte can be prevented, and the long-term discharge characteristics are further improved.

  When the cross-linked polymer (A) contains a cross-linking agent (c) unit, the content (% by weight) of the cross-linking agent (c) unit depends on the type of the cross-linking agent (c). It is 0.05-3 normally with respect to the weight of A), Preferably it is 0.1-1. Within this range, the filling property of the alkaline electrolyte containing the gelling agent into the battery and the long-term discharge characteristics of the alkaline electrolyte are further improved.

When the crosslinked polymer (A) contains a crosslinking agent (b) unit and a crosslinking agent (c) unit, the weight ratio (b / c) between the crosslinking agent (b) unit and the crosslinking agent (c) unit is: 0.25-4.0 are preferable, More preferably, it is 0.4-2.5, Most preferably, it is 0.5-2.0. Within this range, it is possible to further improve the stability of the gelling agent, prevent a decrease in viscosity over time, and prevent separation of the alkaline electrolyte, thereby maintaining a long-term discharge. Further, it can be uniformly injected when filling the battery, and the deviation of the injection amount of the electrolytic solution per battery is reduced, which is preferable.
The total content of the crosslinking agent (b) unit and the crosslinking agent (c) unit is preferably 0.1 to 6% by weight, more preferably 0.1 to 4% by weight, based on the weight of the crosslinked polymer (A). %, Particularly preferably 0.1 to 2% by weight. Within this range, the stability of the gelling agent is improved and the long-term stability of the viscosity of the alkaline electrolyte containing the gelling agent is further improved.

Next, the manufacturing method of the gelatinizer of this invention is demonstrated.
As a polymerization method for obtaining the crosslinked polymer (A), a known polymerization method can be applied. For example, any of solution polymerization, suspension polymerization, bulk polymerization, reverse phase suspension polymerization, or emulsion polymerization may be used.
Of these polymerization methods, solution polymerization, suspension polymerization, reverse phase suspension polymerization and emulsion polymerization are preferred, more preferably solution polymerization, reverse phase suspension polymerization and emulsion polymerization, particularly preferably solution polymerization and reverse phase suspension. Polymerization. For these polymerizations, known polymerization initiators, chain transfer agents and / or solvents can be used.
Most preferably, an aqueous solution polymerization method in which a crosslinking agent (b) and a crosslinking agent (c) are added and dissolved in an aqueous monomer solution mainly composed of (meth) acrylic acid (salt), and hydrophobic organic in the presence of a dispersing agent. This is a so-called reverse phase suspension polymerization method in which a similar aqueous monomer solution is dispersed and suspended in a solvent (for example, hexane, toluene, xylene, etc.). With these polymerization methods, a gelling agent having excellent discharge characteristics and impact resistance can be obtained.
A method of polymerizing (meth) acrylic acid (salt) by an aqueous solution polymerization method or a reverse phase suspension polymerization method may be a normal method, for example, a method of polymerization using a radical polymerization initiator, radiation, ultraviolet rays, electron beam, etc. Can be used.
When a radical polymerization initiator is used, the initiator includes an azo compound [azobisisovaleronitrile, azobisisobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'- Azobis [2-methyl-N- (2-hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) hydrochloride, etc.], inorganic peroxides [hydrogen peroxide, potassium persulfate, ammonium persulfate, Sodium persulfate, etc.], organic peroxides [di-t-butyl peroxide, cumene hydroperoxide, etc.], redox initiators [alkali metal sulfites or bisulfites, ammonium sulfites, ammonium bisulfites, L- Reducing agents such as ascorbic acid, alkali metal persulfate, ammonium persulfate, hydrogen peroxide, etc. Combination etc. peroxides. Two or more of these may be used in combination.

The polymerization temperature varies depending on the type of initiator used, but is preferably -10 ° C to 100 ° C, more preferably -10 ° C to 80 ° C in order to increase the degree of polymerization of (meth) acrylic acid (salt). is there.
The amount of the initiator is not particularly limited, but is preferably 0.000001 to 3.0%, more preferably in order to increase the degree of polymerization of the polymer with respect to the total weight of (meth) acrylic acid (salt). Is 0.000001 to 0.5%.
In the case of aqueous solution polymerization, the polymerization concentration (% by weight) of the monomer varies depending on other polymerization conditions, but (meth) acrylic acid (salt) increases the polymerization concentration when the polymerization concentration is increased. Pseudo-crosslinking (self-crosslinking) is likely to occur, resulting in a decrease in the amount of absorption and a decrease in the average polymerization degree of the polymer. Also, it is difficult to control the temperature during polymerization, resulting in a decrease in the average polymerization degree of the polymer and an increase in the oligomer component. Since it is easy, the polymerization concentration is preferably 10 to 40% by weight, and more preferably 10 to 30% by weight. Moreover, about -10-100 degreeC regarding polymerization temperature, -10-80 degreeC is more preferable. The amount of dissolved oxygen at the time of polymerization is preferably 0 to 2 ppm (2 × 10 ⁻⁴ wt% or less), and preferably 0 to 0.5 ppm (0.5 × 10 ⁻⁴ ), although it depends on the amount of radical initiator added. % By weight or less) is more preferable. Within these ranges, a crosslinked polymer (A) having a high degree of polymerization can be produced.
The degree of neutralization of (meth) acrylic acid during polymerization is not particularly limited as long as a predetermined amount of (b) and (c) can be completely dissolved in the monomer aqueous solution, but compared with (b), ) Is poorly water-soluble, and in particular, the solubility in (meth) acrylic acid (salt) aqueous solution is very low, and even when a predetermined amount of (c) is added, (c) is separated from the aqueous monomer solution and the predetermined crosslinking cannot be performed. Therefore, the degree of neutralization of (meth) acrylic acid at the time of polymerization is preferably 0 to 30% by mole polymerization, and if necessary, further neutralized after polymerization. After polymerization in an unneutralized state, polymerization is performed as necessary. More preferably, it is neutralized later.
In addition, (meth) acrylic acid is polymerized under the same conditions. Since the degree of polymerization tends to increase when the degree of neutralization is low, in order to increase the degree of polymerization of the polymer, the degree of neutralization is low. It is preferable to perform polymerization.

Regarding the reverse phase suspension polymerization method, an aqueous solution of (meth) acrylic acid (salt) is suspended and dispersed in a hydrophobic organic solvent typified by hexane, toluene, xylene, etc. in the presence of a dispersant. In this polymerization method, the monomer concentration in the monomer aqueous solution is preferably 10 to 40% by weight, and more preferably 10 to 30% by weight. Within this range, a crosslinked polymer (A) having a high degree of polymerization can be produced.
In addition, regarding this reverse phase suspension polymerization method, you may use a dispersing agent at the time of superposition | polymerization. Examples of the dispersant include sorbitan fatty acid esters such as sorbitan monostearate having 3 to 8 HLB (Hydrophile-Lipophile Balance), glycerin fatty acid esters such as glycerol monostearate, and sucrose such as sucrose distearate Surfactants such as fatty acid esters; ethylene / acrylic acid copolymer maleate, ethylene / vinyl acetate copolymer maleate, styrene sulfonic acid (salt) / styrene copolymer, hydrophilic in the molecule And a polymer dispersing agent having a group and soluble in a solvent for dispersing the monomer aqueous solution (hydrophilic group; 0.1 to 20% by weight, weight average molecular weight; 1,000 to 1,000,000), etc. However, it is better to use a polymer dispersant as the dispersant. It is preferable because the size of the suspended particles in the aqueous solution can be easily adjusted and a hydrogel of the crosslinked polymer (A) having a required particle size can be prepared.

0.1-20 weight% is preferable with respect to the weight of a hydrophobic organic solvent, and, as for the addition amount of surfactant and / or polymer dispersing agent, 0.5-10 weight% is more preferable.
0.1-2.0 are preferable and, as for the weight ratio (W / O ratio) of the monomer aqueous solution and hydrophobic organic solvent in reverse phase suspension polymerization, 0.3-1.0 are more preferable. Within these ranges, the particle diameter of the crosslinked polymer (A) can be further easily adjusted.
In the production of the crosslinked polymer (A), the average polymerization degree of the polymer when the polymer is produced under exactly the same conditions except that no crosslinking agent is used, is preferably 5,000 to 1,000,000, and more The polymerization is more preferably carried out under the conditions of 10,000 to 1,000,000. When polymerization is carried out under conditions where the average degree of polymerization is 5,000 or more, the use of an appropriate amount of a crosslinking agent prevents a decrease in viscosity and / or an increase in spinnability of a high-concentration alkaline aqueous solution to which a gelling agent is added. I can do it. The average degree of polymerization was measured by gel permeation chromatography (GPC method).

In the present invention, the crosslinked polymer (A) obtained by aqueous solution polymerization, reverse phase suspension polymerization or the like is obtained as a gel containing water (hydrous gel). The hydrogel is usually used as a gelling agent after drying.
Regarding the drying method of hydrous gel, in the case of aqueous solution polymerization, the hydrogel is subdivided to some extent with a meat chopper or cutter type crusher (the level of subdivision is about 0.5 to 20 mm square) or noodles, if necessary After neutralizing the hydrous gel by adding an alkali metal hydroxide or the like, air-permeable drying (lamination of the hydrogel on a punching metal or a screen and forcing a hot air of 50 to 150 ° C. to dry Etc.) and ventilation drying (water gel is put in a container, hot air is aerated and circulated and dried, and the gel is further subdivided with a machine such as a rotary kiln). Among these, air drying is preferable because efficient drying can be performed in a short time.
On the other hand, the drying method of the hydrogel in the case of reverse phase suspension polymerization is carried out by solid-liquid separation of the polymerized hydrogel and the organic solvent by a method such as decantation, followed by drying under reduced pressure (degree of vacuum; about 100 to 50,000 Pa) Or it is common to perform ventilation drying.

  As another drying method of the hydrogel in aqueous solution polymerization, for example, there is a contact drying method in which the hydrogel is compressed and stretched on a drum dryer and the like. It is necessary to create a thin film of hydrogel on the drum or the like. However, since the materials of commercially available drum dryers are generally made of a metal that has a lower ionization tendency than zinc, such as iron, chromium, nickel, etc., the frequency of contact with the drum metal surface per hydrous gel is low. Further, since the water-containing gel is a poly (meth) acrylic acid (salt) water-containing gel, the content of metal elements having a lower ionization tendency than zinc eluted in the gel is increased. Furthermore, the contact frequency between the water-containing gel and the drum is extremely high, and the water-containing gel is highly sticky. Therefore, it is necessary to make a knife-like object come into contact with the drum dryer to separate the dried product from the drum dryer. Due to the mechanical wear of the knife, the metal surface of the drum or knife is worn, and the metal is mixed into the dried product. As described above, when a contact drying method such as a drum dryer is used, metal ions and metal powder are likely to be mixed in the gelling agent, and these metals having a lower ionization tendency than zinc (metals having a standard electrode potential lower than zinc). Therefore, it contains a considerable amount of metal) ions and metal powder that can be expressed by atomic symbols such as Cr, Fe, Ni, Sn, Pb, Cu, Hg, and Ag. When these gelling agents are used as gelling agents for alkaline batteries, the zinc powder in the battery forms a battery with metal ions or metal powder having a lower ionization tendency than zinc. This may increase the pressure inside the battery, and may cause the alkaline electrolyte to flow out or severely damage the battery. Furthermore, the thin film-like dried product obtained by compressing and stretching the hydrogel on a drum dryer or the like is then crushed to adjust the particle size of the dried product to a desired particle size, and the particles are scale-like. Therefore, the strength is much weaker than that of the block-shaped pulverized product by the air-drying method or the air-drying method. The gel is destroyed and the gel becomes smaller. Therefore, it is preferable not to use a contact drying method such as a drum dryer.

In this invention, although the drying temperature at the time of water-containing gel drying changes variously by the dryer to be used, drying time, etc., Preferably it is 50-150 degreeC, More preferably, it is 80-130 degreeC. When the drying temperature is 150 ° C. or lower, the polymer is difficult to crosslink due to heat during drying, the degree of cross-linking does not increase excessively due to thermal cross-linking, the amount of absorption does not decrease, and the viscosity in an alkaline electrolyte does not decrease . When the temperature is 50 ° C. or higher, it is efficient without requiring a long time for drying. The drying time also varies depending on the model of the dryer to be used, the drying temperature, and the like, but is preferably 5 to 300 minutes, more preferably 5 to 120 minutes.
The dried product of the crosslinked polymer (A) thus obtained is pulverized and powdered as necessary. The pulverization method may be a normal method, and can be performed by, for example, an impact pulverizer (pin mill, cutter mill, skiller mill, ACM pulverizer, etc.) or an air pulverizer (jet pulverizer, etc.).
Even when crushing the dried product, if a crusher is used in which the metal rotating parts are in direct contact, the metal powder generated by mechanical wear may be mixed into the gelling agent. It is preferable not to use a pulverizer.
As for the powdered crosslinked polymer (A), a dry powder having a desired particle diameter can be collected using a sieve (vibrating sieve, centrifugal sieve, etc.) equipped with a desired screen if necessary.
In addition, in this invention, it is preferable to remove metal powders, such as iron, mixed using the iron removing machine using magnetism in the arbitrary steps after drying. However, even if iron removal is performed with high precision, it is difficult to remove metals that are not magnetic with iron removal machines, and magnetic metals are also contained inside dry polymer particles. It is desirable to give sufficient consideration to the production equipment so that these metals are not mixed from the beginning, since it cannot be removed.

In the present invention, the particle size of the crosslinked polymer (A) used is usually 32 as the particle size of the swollen particles (BA) after swelling and stirring the crosslinked polymer (A) in a 37 wt% aqueous potassium hydroxide solution. It is preferable to adjust the particle size of the dry powder or the like so that the swelling particles (BA) contain 80 wt% or more of ~ 1000 μm, more preferably 45 to 800 μm. If the average particle size of the swollen gelling agent is less than 80% when the average particle size is 32 to 1000 μm, the zinc powder cannot be prevented from settling in the battery. Even this battery cannot be filled uniformly, and there is a tendency that problems such as deterioration of discharge characteristics due to non-uniform filling amount tend to occur.
Regarding the weight average particle diameter at the time of drying measured according to JIS Z8815-1994 (6.1 dry sieving test) of the crosslinked polymer (A), the swelling ratio and alkali of the alkaline aqueous solution of the crosslinked polymer (A) Depending on the degree of gel breakage when stirred in an aqueous solution, it is preferably 1 to 400 μm, more preferably 10 to 300 μm, particularly preferably 30 to 250 μm, and most preferably 40 to 200 μm. This range is preferable because high-speed filling into the battery is further excellent.

The method for producing the gelling agent of the present invention has already been described above, but it is summarized as follows.
(i) A crosslinking agent {preferably an alkaline and hydrolyzable crosslinking agent (b) and an alkaline and non-hydrolyzing crosslinking agent (c)} is added to an aqueous monomer solution mainly composed of (meth) acrylic acid (salt) (meta ) 0.05 to 3% by weight with respect to the weight of acrylic acid (salt) (however, the optimum point varies depending on the average degree of polymerization of the polymer, the polymerization concentration, etc.). Adjustment is necessary), and the crosslinking agent is completely and uniformly dissolved in the monomer aqueous solution.
(ii) The average degree of polymerization of the polymer without adding (b) and (c) is 5,000 to 1,000,000, and excessive self-crosslinking (polymerization concentration is preferably 40% by weight or less) occurs. It is preferable to carry out the polymerization by an aqueous solution polymerization method and / or a reverse phase suspension polymerization method under difficult mild polymerization conditions to prepare a hydrogel of the crosslinked polymer (A).
(iii) In the case of aqueous solution polymerization, the water-containing gel obtained is subdivided to some extent as necessary, and then an alkali metal hydroxide is added as necessary to adjust the degree of neutralization. It is preferable to dry using a drying method. In the case of reverse phase suspension polymerization, it is preferable to dry the hydrogel after solid-liquid separation using a vacuum drying method or an aeration drying method.
In addition, in order to suppress the polymer thermal crosslinking by heating also at the time of drying, it dries in a short time as long as it can come out at a drying temperature (product temperature) of 150 ° C. or less (preferably 130 ° C. or less).
(iv) The dried pulverized product is preferably pulverized, and if necessary, it is preferable to prepare a gelling agent mainly composed of a dried product having a particle size of 1 to 400 μm using a sieve. When the gelling agent of the present invention is stirred in an alkaline aqueous solution, one side normally swells about 2 to 30 times, so that a gelling agent mainly having a particle size in an alkaline aqueous solution of 30 to 1000 μm is obtained.
(v) The degree of neutralization is performed within the specified amount.

Further, regarding the viscosity of the gelling agent of the present invention, a gel obtained by uniformly stirring and mixing 2.0 parts by weight of the crosslinked polymer (A), 200 parts by weight of zinc powder and 100 parts by weight of 37% by weight potassium hydroxide aqueous solution. The viscosity of the (GA) after standing for 1 day and after standing for 60 days is preferably 30 to 300 Pa · s, more preferably 40 to 300 Pa · s, particularly preferably 50 to 200 Pa · s. Most preferably, it is 60 to 100 Pa · s. When the viscosity is 30 Pa · s or more, the zinc powder can be hardly settled in the battery, and when it is 300 Pa · s or less, the handleability of the aqueous potassium hydroxide solution is relatively easy.
The methods described in the above (i) to (v) can be applied to the method for producing a gelling agent in which the viscosity of the aqueous potassium hydroxide solution to which the gelling agent of the present invention is added is in a predetermined range. .
Furthermore, regarding the content of the metal element having a lower ionization tendency than zinc of the gelling agent of the present invention, the ionization tendency is lower than that of zinc in the gelling agent by sufficiently considering the raw materials used and the production equipment. The content of the metal element can be 0 to 15 ppm (15 × 10 ⁻⁴ wt% or less), preferably 0 to 10 ppm (10 × 10 ⁻⁴ wt% or less) in the gelling agent.
If the content of the metal element having a lower ionization tendency of zinc in the gelling agent is 15 ppm or less, it depends on the structure and capacity of the battery used and the amount of the gelling agent added to the battery. It is difficult to form a battery between the powder and mixed metal ions or metal powder, hydrogen gas is not easily generated by electrolysis, the pressure inside the battery does not increase, and the alkaline electrolyte may flow out or the battery may be damaged. It is preferable because it is not present.

The amount of the soluble component in the 37 wt% potassium hydroxide aqueous solution of the gelling agent of the present invention is preferably 30 wt% or less (0 to 30 wt%), preferably 20 wt% or less, based on the weight of the gelling agent. Is more preferable. Especially preferably, it is 15 weight% or less.
If the amount of the soluble component of the gelling agent is 30% by weight or less, it is preferable because the spinnability of the aqueous alkali solution is not increased and the viscosity is lowered for a long time.
In order to reduce the amount of the soluble component, it is sufficient to increase the average degree of polymerization of the polymer or increase the amount of the crosslinking agent. However, if the amount of the crosslinking agent is increased, the amount of absorption of the gelling agent is decreased. Since the viscosity of the aqueous alkali solution to which is added may be lowered, it is preferable to increase the average degree of polymerization of the polymer.

The alkaline battery to which the gelling agent of the present invention can be applied as a gelling agent for an alkaline electrolyte is not particularly limited, and is an ordinary alkaline battery such as LR-20 (single type 1 alkaline battery), LR-6 type (single AA). The present invention can be applied to various types of alkaline batteries. The alkaline battery usually has a structure in which a positive electrode agent, a current collector rod and a gel negative electrode are enclosed in an outer can, and the positive electrode agent and the gel negative electrode are separated by a separator or the like.
A cross-sectional structure of a typical example of the alkaline battery of the present invention is shown in FIG. In FIG. 1, 1 is a positive terminal plate, 2 is a shrinkable tube, 3 is a positive electrode agent (made of MnO ₂ and carbon, etc.), 4 is an outer can, 5 is a separator, 6 is a current collecting rod, 7 is a gasket, and 8 is a negative electrode. A terminal plate 9 is a gel negative electrode. As described above, the outer casing 4 has a structure in which the positive electrode agent 3, the current collector rod 6 and the gel negative electrode 9 are enclosed, and the positive electrode agent 3 and the gel negative electrode 9 are separated by the separator 5.
Although it does not specifically limit, As a material of the positive electrode terminal board 1, a nickel plating steel plate etc. are mentioned, for example. Examples of the material of the shrinkable tube 2 include a tube of heat-shrinkable resin such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, or polyester resin. As the material of the positive electrode agent 3 (MnO ₂ + carbon, etc.), natural manganese dioxide or electrolytic manganese dioxide as an electrolytic manganese dioxide component, nickel oxyhydroxide or the like instead of manganese dioxide, acetylene black as a carbon component, Examples include those obtained by further adding an alkaline electrolyte as necessary. Examples of the material of the outer can 4 include a nickel-plated steel plate. Examples of the material for the separator 5 include alkali-resistant cellulose, nylon, polyolefin, acrylonitrile-vinyl chloride copolymer, polyvinyl alcohol, and combinations thereof. Examples of the material of the current collecting rod 6 include a tin-plated brass rod and an iron rod. Examples of the material of the gasket 7 include nylon resin and polyolefin resin. Examples of the material of the negative electrode terminal plate 8 include a nickel-plated steel plate. As the gel negative electrode 9, an alkaline electrolyte (such as an aqueous potassium hydroxide solution), zinc powder (and / or zinc alloy powder) and, if necessary, other additives added with the gelling agent of the present invention are used.

The method of filling the alkaline battery with the gelling agent of the present invention comprises: (a) the gelling agent of the present invention, an alkaline electrolyte (for example, containing a high-concentration potassium hydroxide aqueous solution, if necessary, zinc oxide, etc.), zinc powder (And / or zinc alloy powder) and, if necessary, other additives are pre-mixed to prepare a cathode material mixture, which is filled into a cathode container of a battery to form a gelled negative electrode, (b) the present invention The gelling agent and zinc powder (and / or zinc alloy powder) and, if necessary, other additives are filled in the cathode container of the battery, and then the alkaline electrolyte is filled to form a gelled negative electrode in the container. However, since the zinc powder can be uniformly dispersed in the cathode container of the battery, the method (a) is preferable.
The addition amount of the gelling agent varies depending on the structure of the cathode container, the particle size of the zinc powder, and the concentration of the alkaline electrolyte, but is preferably 0.5 to 10% by weight with respect to the alkaline electrolyte. 0 to 5.0% by weight is more preferable. When the addition amount is 0.5 to 10% by weight, the viscosity of the alkaline electrolyte is moderate, and the zinc powder can be prevented from settling, and the handleability is easy.

The gelling agent of the present invention is added in addition to the cross-linked polymer (A) for the purpose of improving the fluidity at the time of filling the cathode material mixture, as long as no problems occur in workability and battery characteristics. An agent may be included.
Examples of other additives include other gelling agents and vibration impact resistance improvers.
Other gelling agents include, for example, CMC (carboxymethylcellulose), natural gums (guar gum, etc.), uncrosslinked poly (meth) acrylic acid (salt), and microcrosslinked poly (meth) acrylic acid (salt) Examples thereof include fine powders of the gelling agent of the present invention, water-soluble resins such as polyvinyl alcohol, and the like. Among these, the finely powdered finely crosslinked poly (meth) acrylic acid (salt), the fine powder of the gelling agent of the present invention, etc. have a relatively small spinnability of the resin itself and are suitable for the cathode container. This is preferable because it provides fluidity when the negative electrode gel is filled.
The particle diameter of the thickener added as necessary is not particularly limited, but is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm in terms of the weight average particle diameter of the dried product. Within this range, even if the spinnability of the cathode material mixture is slightly increased by the addition of other additives, the particles swollen under alkali are small, and the amount of the cathode material mixture per battery is greatly affected. Since it does not give, it is preferable.
As the vibration impact resistance improver, oxides, hydroxides and sulfides of metal elements selected from the group consisting of indium, tin and bismuth can be used.
The content in the case of containing other additives is preferably 0 to 5.0% by weight, more preferably 0 to 3.0% by weight with respect to the alkaline electrolyte.
Other gelling agents can be added by dry blending the gelling agent of the present invention and the other gelling agent in advance and then blending with other cathode materials such as zinc powder and alkaline electrolyte. Examples include a method of adding and mixing separately from the gelling agent of the present invention at the time of preparing the mixture, a method of mixing the alkaline electrolyte and another gelling agent, and then mixing the gelling agent of the present invention and zinc powder. Any method can be used as long as it can add a predetermined amount of another gelling agent if necessary.

  As described above, the crosslinked polymer (A) polymerized by aqueous solution polymerization or reverse phase suspension polymerization can produce a gel that is less likely to break the gel even if (i) stirring is performed in an alkaline aqueous solution. Therefore, when used as a gelling agent for alkaline batteries, the zinc powder adheres uniformly around the gel swollen with the alkaline electrolyte, improving the discharge characteristics and life of the battery. In addition, the swollen gel in which the zinc powder is uniformly adhered to the surroundings increases the concentration of the zinc powder substantially and increases the frequency of contact between the zinc powders. Since (A) is uniformly filled, the gel does not flow easily, so that it is possible to prevent a decrease in voltage and short-circuit current even when subjected to an impact. (ii) Polymerization can be performed under control of polymerization temperature or mild conditions, and water having a low chain transfer constant is used as a solvent, so that the average polymerization degree of the polymer can be increased and the oligomer component can be reduced. Therefore, when used as a gelling agent for batteries, the stability of the high-concentration alkaline aqueous solution and the spinnability can be satisfied at the same time. In addition, since the electrolyte gel can be uniformly filled into the battery, the improvement in battery characteristics can be satisfied at the same time.

Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified,% indicates% by weight, ultrapure water indicates water having an electric conductivity of 0.06 μS / cm or less, and ion exchange water indicates water having an electric conductivity of 1.0 μS / cm or less.
The test methods used in the examples are shown below.

(I) Weight average particle diameter of crosslinked polymer (A) Measured according to JIS Z8815-1994 (6.1 dry sieving test) of crosslinked polymer (A). Large screen with 1 μm, 5 μm, 25 μm, 53 μm, 106 μm, 150 μm, 300 μm, 500 μm and 710 μm sieves (frame diameter 200 mm, depth 45 mm) created according to JIS Z8801-1: 2000 The cross-linked polymer (A) was sieved in order so that the ones were on top.
The weight average particle diameter of the crosslinked polymer (A) is JIS Z8819-2: 2001 (corresponding to ISO / FDIS9276-2: 1999). Number average of weighted average particle diameter of formula (12) described in 5.2 It is a value calculated according to the diameter.

(ii) Particle diameter and content of swollen particles (BA) of the crosslinked polymer (A) after stirring in a 37% aqueous potassium hydroxide solution:
<Creation of swollen particles (BA)>
In a 500 ml beaker, put 2 g of the cross-linked polymer (A), 300 g of 37% aqueous potassium hydroxide and a rotor (length 4 cm), and stir for 3 hours at 25 ° C. at a speed of 600 rpm using a magnetic stirrer. By mixing, swollen particles (BA) were obtained.
<Content of swollen particles having a particle diameter of 32 to 1,000 μm in swollen particles (BA)>
Created according to JIS Z8801-1: 2000, a 400 mesh (screen opening: 32 μm) sieve was placed on the bottom, and a 16 mesh (screen opening: 1000 μm) sieve was placed on top. Swelled particles (BA) were poured onto a 20 cm diameter sieve and further washed several times with a 40% aqueous potassium hydroxide solution. After leaving the sieve for 30 minutes and draining, the aqueous potassium hydroxide solution adhered to the screen was wiped off, and the weight of the swelling particles remaining on the top of the 400 mesh sieve was measured. The swollen particle content (%) of 32-1000 μm was measured.
32 to 1,000 μm swollen particle content (%) = 100 × [weight (g) of swollen particles on a sieve having an opening of 32 μm] / [2 × absorbed amount of crosslinked polymer (A) (g / g) ]
<Content of swollen particles having a particle diameter of 45 to 850 μm in swollen particles (BA)>
45 to 850 μm in the swollen particles (BA) was similarly used except that a sieve having an opening of 45 μm was used instead of a sieve having an opening of 32 μm, and a sieve having an opening of 850 μm was used instead of a sieve having an opening of 1000 μm. The swollen particle content (%) was measured.
45 to 850 μm gel content (%) = 100 × [weight of swollen particles (g) on a sieve having an opening of 45 μm] / [2 × absorbed amount of crosslinked polymer (A) (g / g)]

(iii) Absorption amount of cross-linked polymer (A) with respect to 37% potassium hydroxide aqueous solution (tea bag method):
The sample is 2.0 g of the crosslinked polymer (A), the nylon screen opening of the tea bag made of nylon screen is 32 μm (400 mesh), the test solution is 37% potassium hydroxide (reagent special grade) aqueous solution, the immersion time is 1 hour, Based on JIS K7223-1996, the amount of absorption was measured by the following equation under the condition of draining time of 30 minutes.
Absorption amount (g / g) = {(weight after soaking of tea bag containing sample and draining) − (average value of weight after soaking of tea bag not containing sample and draining)} / 2

(iv) Viscosity ratio of gel (GA) (N1 / N60):
<Viscosity of gel (GA) after standing for 1 day (40 ° C., N1)>
First, 2 g of the crosslinked polymer (A) and 200 g of zinc powder are mixed in a Nauta mixer, put into a 200 ml transparent plastic container with a lid, and then 100 g of 37% potassium hydroxide aqueous solution is left as it is. The mixture was stirred while being gradually added so as not to become turbid. After 1 hour, after confirming that the contents were uniformly gelled (or thickened) to become gel (GA), the gel (GA) was sealed with a lid and placed in a thermostatic chamber at 40 ° C. I left it for a day. Using a digital B-type viscometer (manufactured by TOKIMEC), the viscosity of the gel (GA) is measured according to JIS7117-1: 1999, and the viscosity of the gel (GA) after standing for 1 day (40 ° C., N1) and did. (Measurement temperature: 40 ° C., rotor No. 4, rotation speed: 3 rpm)
<Viscosity of gel (GA) after standing for 60 days (40 ° C., N60)>
The sample after the measurement of the viscosity (40 ° C., N1) of the gel (GA) after standing for 1 day was sealed and left in a thermostat at 40 ° C. for another 59 days. The viscosity of the gel (GA) was measured under the same conditions as the viscosity (40 ° C., N1), and the viscosity of the gel (GA) after standing for 60 days (40 ° C., N60) was determined.
<Viscosity ratio of gel (GA) (N1 / N60)>
The viscosity ratio (N1 / N60) of the gel (GA) was determined by the following formula.
Viscosity ratio (N1 / N60) = {viscosity after standing for 1 day (40 ° C., N1)} / {viscosity after standing for 60 days (40 ° C., N60)}

(v) Content of metal elements having a lower ionization tendency than zinc:
Put 0.5g of gelling agent, 3ml of hydrochloric acid and 4ml of nitric acid in the Teflon (registered trademark) decomposition vessel attached to the wet ashing device (Milestone: MLS-1200MEGA) and seal it in the wet ashing device. The Teflon (registered trademark) container was set, the wet ashing apparatus was operated, and the sample was completely decomposed. Ultrapure water is added to the decomposed sample to make a total liquid volume of 9 g, and iron (Fe), nickel (Ni), chromium (Cr), tin (Sn), lead by inductively coupled high-frequency plasma spectroscopy (ICP) Content was measured regarding the metal elements of (Pb), copper (Cu), and silver (Ag). Separately, a calibration curve for the metal element was prepared using a standard solution, and the content of each metal was determined using the calibration curve.
Metal element content (% by weight) = {Total amount of metal elements (Fe, Ni, Cr, Sn, Pb, Cu and Ag) in the gelling agent (g) × 9} /0.5 (g)
In the above formula, 0.5 (g) represents the weight of the gelling agent.

(vi) Amount of soluble components in 37% aqueous potassium hydroxide solution:
A gelling agent (1.0 g) and a 37% aqueous potassium hydroxide solution (200 g) were placed in a 500 ml beaker and stirred for 3 hours at 300 rpm using a magnetic stirrer. The stirred solution was filtered with a filter paper (No. 2 type, manufactured by Toyo Roshi Kaisha, Ltd.), and the filtrate was collected. 30 g of ion-exchanged water was added to 20 g of the filtrate, and 10% sulfuric acid aqueous solution was added to adjust the pH to 7.0 to obtain a sample solution. Separately from this, 30 g of ion-exchanged water was added to 20 g of 37% aqueous potassium hydroxide used for adjusting the filtrate, and further 10% sulfuric acid aqueous solution was added to adjust the pH to 7.0 to prepare a blank solution.
Using an automatic titration device (manufactured by Mitsubishi Chemical Corporation, GT-05 type), a 0.01N potassium hydroxide aqueous solution is dropped into the sample solution and the pH of the sample solution is once adjusted to 10.0. A 0.01N hydrochloric acid aqueous solution was added dropwise to the sample, and the amount {ml (Va)} of the 0.01N hydrochloric acid aqueous solution required until the pH of the sample solution reached 2.7 was measured.
The same operation was performed on the blank solution, and the hydrochloric acid aqueous solution dropping amount {ml (Vb)} of the blank solution was measured.
All the above operations were performed at 25 ° C.
When the constituent monomer of the cross-linked polymer (A) is composed only of acrylic acid, the amount of soluble component (%) in the aqueous potassium hydroxide solution in the gelling agent according to formulas -1, -2, and -3. Was calculated.
M = (Va−Vb) × N (Formula-1)
M: Amount of potassium acrylate in the sample solution (mmol)
N: Normality of hydrochloric acid aqueous solution W = M × E × D (Formula-2)
W: Weight of potassium acrylate in the sample E: 110 (potassium acrylate molecular weight)
D: Dilution ratio (200/20)
Soluble component amount (%) = W (g) × 100/1 (g) (Formula-3)
In the above formula-3, 1 (g) represents the sample weight.
When the constituent monomer of the crosslinked polymer (A) is composed of only methacrylic acid, E is 124 (molecular weight of potassium methacrylate). When copolymerizing acrylic acid and methacrylic acid, and for polymers copolymerized with monomers other than (meth) acrylic acid, the amount of carboxylic acid per unit molecular weight is calculated and corrected (the copolymerized weight ratio is the soluble component) The amount of soluble component is calculated assuming that the same weight ratio is present).

Example 1
In a 2-liter beaker, 200 g of acrylic acid, 0.6 g of pentaerythritol triallyl ether (manufactured by Daiso Corporation) (0.3 wt% / acrylic acid), 0.6 g of trimethylolpropane triacrylate (0.3 wt% / Acrylic acid) and 800 g of ion-exchanged water were added and mixed by stirring to prepare an aqueous acrylic acid solution and cooled to 8 ° C.
The acrylic acid aqueous solution was put into a 1.5 liter adiabatic polymerization tank, and the dissolved oxygen amount in the acrylic acid aqueous solution was adjusted to 0.1 ppm or less through nitrogen in the aqueous solution. To this adiabatic polymerization layer, 4.0 g of 0.1% hydrogen peroxide solution, 4.0 g of 0.1% L-ascorbic acid aqueous solution and 10% 2,2′-azobis (2-amidinopropane) hydrochloride (Wako Pure) Yaku Kogyo Co., Ltd., trade name: V-50) 1.0 g of aqueous solution was added, and nitrogen purge into the aqueous solution was continued until polymerization started. After confirming that the polymerization started and the viscosity of the acrylic acid aqueous solution started to rise, the purge of nitrogen was stopped and the polymerization was carried out for 6 hours. When the temperature of the aqueous acrylic acid solution was measured with a hot spot thermometer, the maximum temperature reached was 63 ° C.
In addition, when the average degree of polymerization of the polymer polymerized under the same conditions except that the above two kinds of crosslinking agents were removed was measured using GPC, the average degree of polymerization of the polymer was about 28,000.
After removing the block-like crosslinked hydrous gel from the adiabatic polymerization tank and using a small meat chopper (Royal) to subdivide the gel into noodles with a thickness of 3 to 10 mm, 40% hydroxide The aqueous gel was neutralized by adding 222 g of a sodium (reagent special grade) aqueous solution (degree of neutralization 80 mol%).

The neutralized water-containing gel is laminated on a SUS screen having an opening of 850 μm with a thickness of 5 cm, and hot air at 120 ° C. is applied for 1 hour using a small air-permeable dryer (manufactured by Inoue Metal Co., Ltd.). The water-containing gel was air-permeable and the water-containing gel was dried.
The dried product was pulverized using a cooking mixer, and particles having a particle size of 32 to 500 μm (400 to 30 mesh) were collected using a sieve to obtain the gelling agent (1) of the present invention.
Regarding the gelling agent (1), the weight average particle diameter, the content of the metal element, the absorption amount with respect to the 37% aqueous potassium hydroxide solution, the viscosity after one day of the gel (G / A) (40 ° C., N1), after 60 days Viscosity (40 ° C., N60), viscosity ratio (N1 / N60), particle diameter of swollen particles (BA) (content of 32-1000 μm, content of 45-850 μm), and in 37% aqueous potassium hydroxide solution The amount of soluble components was measured.
Moreover, the same measurement was performed also about Examples 2-13 and Comparative Examples 1-8. The results are shown in Tables 1 and 2.

Example 2
In Example 1, the same operation as in Example 1 was performed except that ethylene glycol diglycidyl ether (manufactured by Nagase Kasei Co., Ltd., trade name: Denacol 810) was used instead of trimethylolpropane triacrylate. A gelling agent (2) was obtained.

Example 3
The same procedure as in Example 1 was performed except that the amount of pentaerythritol triallyl ether added was 0.2 g (0.1% / acrylic acid) in Example 1, and the gelling agent (3) of the present invention was used. Got.

Example 4
In a 1 liter beaker, 100 g of acrylic acid, 272.2 g of ion-exchanged water and 0.2 g of pentaerythritol triallyl ether (0.2 wt% / acrylic acid) were added and mixed to dissolve the crosslinking agent. While cooling the beaker with an ice bath, 100 g of 40% sodium hydroxide aqueous solution was added to neutralize a part (72 mol%) of acrylic acid. After the neutralized monomer solution was cooled to 5 ° C., 0.2 g of potassium persulfate was added as a polymerization initiator to prepare a monomer aqueous solution.
In a 2 liter separable flask equipped with a stirrer and a condenser (cooler), 1000 ml of cyclohexane and 10 g of sodium styrenesulfonate / styrene block copolymer as a dispersant were heated to 60 ° C. using a hot water bath. Stir to dissolve the dispersant in cyclohexane.
After making the dissolved oxygen of cyclohexane 0.1 ppm or less through nitrogen in a cyclohexane liquid in a separable flask, stirring the cyclohexane using a stirrer and using the dropping funnel, 400 g of the monomer aqueous solution and 0.5% ethylene glycol 80 g of diglycidyl ether aqueous solution (0.4% by weight / acrylic acid) was added dropwise, reverse phase suspension polymerization was carried out at a polymerization temperature of 60 ° C., and after completion of the dropwise addition of the monomer aqueous solution, the mixture was further heated for 2 hours. When completed, a spherical hydrous gel was obtained in cyclohexane.
After the rotation of the stirrer was stopped and the produced hydrogel was allowed to settle, cyclohexane was removed by decantation, and the remaining hydrogel was washed with cyclohexane several times to remove the dispersant adhering to the hydrogel.
The obtained spherical water-containing gel was spread on a release paper, and dried for 2 hours with a 80 ° C. vacuum dryer (degree of vacuum: 10,000 to 20,000 Pa). When the particle size of the dried product was measured, the content of 45 to 850 μm was 92%, so that it was directly used as the gelling agent (4) of the present invention.

In the present invention, the relationship between the degree of decompression and the actual pressure is as follows.
Actual pressure = Normal pressure (1.013 × 10 ⁵ Pa) −Decompression degree

Example 5
Powder blend of 85 g of the gelling agent of the present invention obtained in Example 1 and 15 g of finely crosslinked polyacrylic acid fine powder (trade name: Junron PW-150, manufactured by Nippon Pure Chemical Co., Ltd.) obtained by commercially available precipitation polymerization The gelling agent (5) of the present invention was obtained.

Example 6
In Example 1, a particle size of 500 μm or more was collected using a sieve and used as the gelling agent (6) of the present invention.

Example 7
In Example 1, a particle size of 32 μm or less was collected using a sieve and used as the gelling agent (7) of the present invention.

Reference example 1
In Example 1, a reference gelling agent (8) was obtained in the same manner as in Example 1 except that trimethylolpropane triacrylate was not used.

Example 9
In Example 1, the gelling agent (9) of this invention was obtained like Example 1 except having changed the drying method into the following method.
(Drying method)
Water content subdivided between a drum dryer made of an alloy of iron and chromium heated to 160 ° C. (manufactured by Kashiwagi Machinery Co., Ltd.) and a pressure roll made of Teflon (registered trademark) attached to the drum dryer (clearance 0.5 mm) The gel was placed, and the hydrogel was rolled onto a drum dryer with a thickness of 0.5 mm and dried for 3 minutes. After drying, a knife (manufactured by SUS) attached to the drum dryer was brought into contact with the drum dryer, and the dried film was peeled off from the drum dryer. When the film thickness was measured with a film thickness meter, the thickness was about 0.2 mm.
The dried film is pulverized using a cooking mixer, and a 3-500 μm sample is collected using a sieve.

Example 10
In Example 1, the gelling agent (10) of the present invention was obtained in the same manner as in Example 1 except that the addition amount of trimethylolpropane triacrylate was 0.06 g (0.03% / acrylic acid). .

Example 11
In Example 1, the gelling agent (11) of the present invention was obtained in the same manner as in Example 1 except that the amount of trimethylolpropane triacrylate added was 8.0 g (4.0% / acrylic acid). .

Example 12
In Example 1, the gelling agent (12) of the present invention was prepared in the same manner as in Example 1 except that the addition amount of pentaerythritol triallyl ether was 0.2 g and the addition amount of trimethylolpropane triacrylate was 0.35 g. )

Example 13
In Example 1, the gelling agent (13) of the present invention was prepared in the same manner as in Example 1 except that the addition amount of pentaerythritol triallyl ether was 0.8 g and the addition amount of trimethylolpropane triacrylate was 0.4 g. )

Comparative Example 1
Commercially available carboxymethyl cellulose (CMC2450, manufactured by Daicel Chemical Industries, Ltd.) was used as a comparative gelling agent (H1).

Comparative Example 2
A commercially available finely cross-linked polyacrylic acid fine powder (Carbopol 941, manufactured by BF Goodrich Company, average particle size of about 20 μm) was used as a comparative gelling agent (H2).

Comparative Example 3
A finely-crosslinked polyacrylic acid fine powder (Junron PW-150, manufactured by Nippon Pure Chemicals Co., Ltd., average particle size of about 20 μm) by 20 g of a commercially available precipitation polymerization method is added to an aqueous methanol solution {methanol / water = 70/30 (weight ratio). Mixture)} was added and stirred to granulate. The granulated product was dried at 100 ° C. with an air circulation dryer, and then lightly pulverized with a cooking mixer, and a product having a particle size of 210 to 850 μm was collected using a sieve and used as a comparative gelling agent (H3).

Comparative Example 4
In Example 1, except not using the Pentaerisu lithol triallyl ether, in the same manner as in Example 1 to obtain a gelling agent (H4) comparison.

Comparative Example 5
In Example 1, except that the addition amount of Pentaerisu lithol triallyl ether and 0.06 g (0.03% / acrylic acid) to give a gelling agent for comparison in the same manner as in Example 1 (H5) .

Comparative Example 6
In Example 1, except that the addition amount of Pentaerisu lithol triallyl ether and 8.0 g (4.0% / acrylic acid) to give a gelling agent for comparison in the same manner as in Example 1 (H6) .

Comparative Example 7
In Example 1, the addition amount of the added polymerization initiator (hydrogen peroxide, ascorbic acid, V-50) was increased 10 times, and instead of ion-exchanged water, a 20% ethanol aqueous solution {ethanol / water = 20/80 ( Except for the weight ratio)}, the same operation as in Example 1 was performed to obtain a comparative gelling agent (H7).
Incidentally, when the average polymerization degree of polymerization except crosslinking agent and is Pentaeri scan lithol triallyl ether and trimethylolpropane triacrylate polymer was measured by using GPC, the average polymerization degree of the polymer is about 1,700 met It was.

Comparative Example 8
Without using the two kinds of crosslinking agents used in Example 1, the same operation as in Example 1 was performed to obtain a comparative gelling agent (H8).

Using the gelling agents (1) to (13) prepared in Examples 1 to 13 and the gelling agents (H1) to (H8) prepared in Comparative Examples 1 to 8 and an alkaline electrolyte, zinc powder (UNION) MINIERES A., product name: 004F (2) / 68), sedimentation time, variation in injection time and injection amount, generation amount of hydrogen gas, duration of model battery and impact resistance were measured by the following methods.
The results are shown in Tables 3 and 4.

(Precipitation of zinc powder)
Biaxial kneader (product name: PNV-1 manufactured by Irie Trading Co., Ltd.) with a capacity of 1 liter, 150 g of 37% aqueous potassium hydroxide solution, 300 g of zinc powder having an average particle size of 120 μm, 2.5 g of a gelling agent and a thickener (product) Name: Junlon PW-150) 0.5 g was added and mixed for 60 minutes at a rotation speed of 50 rpm to prepare a negative electrode gel.
50 g of the prepared negative electrode gel was put into a 50 ml sample bottle (diameter 34 mm, height 77 mm, made of polypropylene) that can be sealed, and bubbles that were introduced during mixing were degassed under reduced pressure.
After sealing the sample bottle and leaving it in a constant temperature bath at 40 ° C. for 30 days, using the apparatus attached to the powder tester (manufactured by Hosokawa Micron Co., Ltd.), the sample bottle is 300 times from a height of 3 cm at a rate of 30 times / min. Tapping promoted the precipitation of zinc powder. After completing the tapping, the distance (mm) at which the zinc powder was most settled was measured from the initial position of the zinc powder (the position of the upper end of the negative electrode gel in the sample bottle), and this was determined as the sedimentation property (mm) of the zinc powder. It was.

(Variation of injection time and injection amount)
Add 150 g of 37% potassium hydroxide aqueous solution, 300 g of zinc powder with an average particle size of 120 μm, 2.5 g of gelling agent and 0.5 g of thickener (trade name: Junlon PW-150) to a 1 liter biaxial kneader. And mixing for 60 minutes at a rotation speed of 50 rpm to prepare a negative electrode gel. The prepared negative electrode gel was transferred to a beaker, and bubbles introduced during mixing were degassed under reduced pressure.
The degassed gelled potassium hydroxide aqueous solution was sucked into a 20 ml syringe having an injection port with an inner diameter of 2 mm and a scale of 0.1 ml.
From the height of the mouth of the 5 ml sample bottle (inner diameter 18 mm, height 40 mm), compress the syringe by 2.0 ml and inject the gel-like potassium hydroxide aqueous solution into the sample bottle. The time (seconds) from when the gelled aqueous potassium hydroxide solution was completely separated from the syringe inlet was measured with a stopwatch. The same operation was repeated 20 times in total, and the average value was taken as the injection time (seconds).
The weight (20 times) of the potassium hydroxide aqueous solution injected into the sample bottle was measured, and the standard deviation (σ) of the injection amount was calculated to determine the variation in the injection amount.

(Hydrogen gas generation amount)
A 50 ml sample bottle (34 mm in diameter, 77 mm in height, made of polypropylene) 15 g of 37% potassium hydroxide aqueous solution, 30 g of zinc powder having an average particle size of 120 μm, 0.25 g of a gelling agent and a thickener (trade name: Junron PW) -150) 0.05 g was added and mixed for 60 minutes at a rotation speed of 50 rpm.
The sample bottle was covered with a lid (having a hole with a diameter of about 3 mm into which the gas detection tube can be inserted, and the portion was covered with a sealing tape), and the inside was sealed, and then placed in a thermostat at 50 ° C. for 30 days.
After 30 days, the sample bottle is taken out, and a hydrogen gas detector tube (Kitakawa gas detector tube, manufactured by Komyo Chemical Co., Ltd., hydrogen gas measurable range: 500 to 8000 ppm) is put in the hole of the lid that has been opened in advance. Inserted into the phase section, the hydrogen gas concentration in the gas phase was measured.

(Battery duration)
To a 1 liter biaxial kneader, add 150 g of 37% potassium hydroxide aqueous solution, 300 g of zinc powder, 2.5 g of gelling agent and 0.5 g of thickening agent, and mix for 60 minutes at 50 rpm. Created.
After defoaming under reduced pressure, 15 g of this negative electrode gel was injected into the negative electrode container of the LR-6 model battery shown in FIG. Here, the constituent material of each part other than the gel negative electrode 9 of the model battery is a nickel-plated steel plate, the material of the shrinkable tube 2 is polyethylene, the material of the positive electrode agent 3 is 50 parts by weight of electrolytic manganese dioxide, and acetylene black 5 A composition comprising 1 part by weight of a weight part and a 37% by weight potassium hydroxide aqueous solution, the outer can 4 as a material for nickel-plated steel, the separator 5 as a material for polyolefin, and the current collector rod 6 as a material for tin plating The brass rod and gasket 7 were made of polyolefin resin, and the negative electrode terminal plate 8 was made of nickel-plated steel plate. An external resistance of 2Ω was connected to the prepared model battery at room temperature (20 to 25 ° C.), the battery was continuously discharged, and the time until the voltage decreased to 0.9 V was defined as the battery duration (hour). After the model battery was prepared, the same operation was performed on the model battery that was left in a constant temperature bath at 60 ° C. for 60 days, and the duration of the battery was measured.

(Battery impact resistance)
To the model battery made in the same way as above, connect the external resistance of 2Ω at room temperature (20-25 ° C) and continuously discharge the model battery from the height of 1m 10 times continuously before dropping. And the voltage immediately after dropping were measured, and the impact resistance (%) was calculated by the following formula.
Impact resistance (%) = {Voltage immediately after dropping (10th time) (V) / Voltage before dropping (V)} × 100
After the model battery was created, the same operation was performed on the model battery that was left in a constant temperature bath at 60 ° C. for 60 days to obtain impact resistance.

  In Example 6 of Table 3, clogging occurred in the syringe used at the time of injection, but injection was possible when an injection port having an inner diameter of 5 mm was used.

  The gelling agent of the present invention is useful not only as a cylindrical alkaline battery but also as a gelling agent for primary and secondary alkaline batteries such as alkaline button batteries, silver oxide batteries, nickel cadmium batteries, nickel metal hydride batteries, etc. . Moreover, the alkaline battery using the gelling agent of the present invention is useful as an alkaline battery having excellent impact resistance and excellent discharge characteristic maintenance.

It is sectional drawing which shows an example of the alkaline battery of this invention.

Explanation of symbols

1. Positive terminal plate 2. Shrink tube Cathode agent 4. Exterior can Separator 6. Current collecting rod 7. Gasket 8. Negative electrode terminal plate 9. Gel negative electrode

Claims (10)

It consists of a crosslinked polymer (A) having (meth) acrylic acid (salt) as a main constituent monomer unit, and (A) is an alkaline and hydrolyzable crosslinker (b) unit, and is alkaline and does not hydrolyze A cross-linking agent (c) unit, the viscosity ratio (N1 / N60) of the gel (GA) is 0.7 to 1.3, and the amount of soluble components in a 37 wt% potassium hydroxide aqueous solution is 30 wt%. The gelling agent for alkaline batteries which is the following.
Viscosity ratio of gel (GA) (N1 / N60): 100 parts by weight of 37% by weight aqueous potassium hydroxide solution, 2 parts by weight of crosslinked polymer (A) and 200 parts by weight of zinc powder were uniformly stirred and mixed at 40 ° C. GA) was prepared, and the viscosity (40 ° C., N1) after leaving the gel (GA) for 1 day and the viscosity after standing for 60 days (40 ° C., N60) at the same temperature in accordance with JIS K7117-1: 1999. Obtain from the measured value.   The gelling agent according to claim 1, wherein the gel (GA) has a viscosity (40 ° C, N1) of 30 to 300 Pa · s. The gelling agent according to claim 1 or 2, wherein the crosslinked polymer (A) satisfies the following requirements.
Of the swollen particles (BA) obtained by uniformly mixing 2 parts by weight of the crosslinked polymer (A) and 300 parts by weight of a 37 wt% aqueous potassium hydroxide solution at 25 ° C., swollen particles having a particle diameter of 32 to 1,000 μm swell. At least 80% by weight relative to the total weight of the particles (BA)   The gelling agent according to any one of claims 1 to 3, wherein an absorption amount after 1 hour of a 37 wt% potassium hydroxide aqueous solution by a tea bag method is 20 to 60 g / g. Crosslinked polymer (A) contains the weight ratio of crosslinking agent (b) unit and the crosslinking agent (c) units (b / c) is any of claims 1 to 4 is 0.4 to 2.5 gelling agent according to any. The gelling agent according to any one of claims 1 to 5, wherein the crosslinking agent (b) is a compound having an ester bond and / or an amide bond, or a compound capable of forming an ester bond and / or an amide bond. The gelling agent according to any one of claims 1 to 6 , wherein the crosslinking agent (c) has 3 to 10 allyl groups and 1 to 5 hydroxyl groups. The gelling agent according to any one of claims 1 to 7 , wherein the content of the metal element having a lower ionization tendency than zinc is 15 x 10 ^-4 wt% or less. (Meth) acrylic acid obtained by an aqueous solution polymerization method or reverse phase suspension polymerization method using a crosslinking agent (b) that decomposes under alkalinity and an allyl ether type crosslinking agent (c) having 2 to 10 allyl groups A water-swellable gelling agent comprising a cross-linked polymer (A) having (salt) as a main constituent monomer unit, wherein each amount of (b) and (c) is (meth) acrylic acid and A gelling agent for an alkaline battery which is 0.05 to 3% based on the weight of the alkali metal salt and which satisfies the following requirements (1) and (2).
Requirement (1): When the gelling agent is swollen in a 37% strength by weight potassium hydroxide aqueous solution, there should be 80% by weight or more of swollen particles having a particle size of 32 to 1,000 μm. Requirement (2); Tea bag method The absorption of 37% strength by weight potassium hydroxide aqueous solution after 1 hour is 20 to 60 g / g. An alkaline battery comprising the gelling agent according to any one of claims 1 to 9 and zinc powder.

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