Gel for alkaline batteries

Abstract

Provided are a gelling agent for alkaline batteries, which is excellent in maintenance of long-term discharge characteristics (discharge capacity and discharge time) and impact resistance and heat resistance, and an alkaline battery using the same. A gelling agent for alkaline batteries, which comprises a crosslinked polymer (A) having water-soluble vinyl monomer (a1) and / or vinyl monomer (a2) that becomes water-soluble vinyl monomer (a1) by hydrolysis and internal crosslinking agent (b) as essential constitutional units, a part of the crosslinked polymer (A) being neutralized with alkali metal hydroxide (c), and the neutralization uniformity of the gelling agent for alkaline batteries being 60 to 90%.

Description

TECHNICAL FIELD

[0001] The present application relates to a gelling agent for alkaline batteries. BACKGROUND

[0002] In the past, a negative electrode of an alkaline battery has mainly used a mixture of a high-concentration alkaline electrolyte (a high-concentration aqueous potassium hydroxide solution, a solution containing zinc oxide and the like as necessary) and a zinc powder and / or a zinc alloy powder and the like, and from the viewpoints of preventing the settlement of the zinc powder in the alkaline electrolyte, preventing the leakage of a liquid from the battery, and improving the production efficiency of the battery, a proposal has been made to use a water-absorbing resin and the like obtained by insolubilizing a poly(meth)acrylic acid and a salt thereof with a crosslinking agent as a thickening agent for the purpose of suppressing the stringiness (Patent Document 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-34379 SUMMARY OF THE INVENTION

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, alkaline batteries have recently been required to be further improved in performance, and an alkaline battery using a gelling agent of these water-absorbing resins cannot be said to be sufficient in the settlement-preventing property of a zinc powder and the like in an alkaline electrolyte, and cannot necessarily satisfy the maintenance of long-term discharge characteristics (discharge capacity and discharge time) and the impact resistance of the battery. In addition, in the case where a strong impact is applied to the alkaline battery or in the case of an accidental short circuit, a large current flows in the battery and heat is generated, and the discharge characteristics are reduced, and thus the battery cannot necessarily satisfy the heat resistance.

[0008] Therefore, an object of the present application is to provide a gelling agent for alkaline batteries and an alkaline battery using the same, which are excellent in the maintenance of long-term discharge characteristics (discharge capacity and discharge time), the impact resistance, and the heat resistance.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The present inventors have conducted intensive studies in order to solve the above problems, and as a result, the present application has been completed. That is, the present application is a gelling agent for alkaline batteries, which contains a crosslinked polymer (A) composed of a water-soluble vinyl monomer (al) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (al) by hydrolysis, and an internal crosslinking agent (b), a part of the crosslinked polymer (A) is neutralized with an alkali metal hydroxide (c), and the neutralization uniformity of the gelling agent for alkaline batteries is 60 to 90%.

[0011] EFFECTS OF THE INVENTION

[0012] The gel agent for alkaline batteries of the present application, the alkaline battery exerts the following effects.

[0013] (1) The gel agent for alkaline batteries of the present application is excellent in the anti-settling property of zinc powder or the like in the negative electrode material, and thus, in the case of being used for an alkaline battery, it is possible to produce a battery which is extremely excellent in the discharge duration with a small amount and for a long period, and in the impact resistance.

[0014] (2) The negative electrode material to which the gel agent for alkaline batteries of the present application is added is small in the change in viscosity at the time of heat generation, and thus, it is possible to produce a battery which is extremely excellent in the impact resistance, the heat resistance, and the safety.

[0015] (3) The negative electrode material to which the gel agent for alkaline batteries of the present application is added is in an appropriate range in the viscosity at the time of filling, and the negative electrode material is good in the liquid cut, and thus, the deviation in the amount of the negative electrode material filled per 1 battery is small, and thus, it is possible to produce a battery having a uniform quality even in mass production, and in addition, even in a small-sized battery, it is possible to uniformly and rapidly fill the negative electrode material, and thus, it is possible to produce a battery having a uniform quality. DETAILED DESCRIPTION

[0016] Gel agent for alkaline batteries

[0017] The gel agent for alkaline batteries (G) of the present application contains a crosslinked polymer (A) composed of a water-soluble vinyl monomer (al) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (al) by hydrolysis, and an internal crosslinking agent (b), a part of the crosslinked polymer (A) is neutralized with an alkali metal hydroxide (c), and the neutralization uniformity of the gel agent for alkaline batteries is 60 to 90%.

[0018] In the present application, the water-soluble vinyl monomer means a vinyl monomer which has a property of dissolving at least 100 g in 100 g of water at 25°C.

[0019] The water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) that becomes (a1) by hydrolysis are not particularly limited, and for example, the water-soluble radical polymerizable monomers described in Japanese Patent Application Publication No. 2005-075982 can be mentioned. Among them, from the viewpoint of discharge properties, the water-soluble vinyl monomer (a1) is preferred, an anionic vinyl monomer is further preferred, and a carboxylic acid (salt) having a vinyl group having 3 to 30 carbon atoms {unsaturated monocarboxylic acid (salt) [(meth)acrylic acid, crotonic acid, cinnamic acid, and salts thereof, etc.]; unsaturated dicarboxylic acid (salt) (maleic acid, fumaric acid, citraconic acid, itaconic acid, and salts thereof, etc.); and a monoalkyl (carbon number 1 to 8) ester of the unsaturated dicarboxylic acid (maleic acid monobutyl ester, fumaric acid monobutyl ester, ethyl carbitol monoester of maleic acid, ethyl carbitol monoester of fumaric acid, citraconic acid monobutyl ester, and itaconic acid glycol monoester, etc.} is particularly preferred, and an unsaturated monocarboxylic acid (salt) is especially preferred, and an acrylic acid (salt) is most preferred.

[0020] In the present application, (meth)acrylic acid means acrylic acid and / or methacrylic acid, and "... acid (salt)" means "... acid" and / or "... acid salt". As the salt, alkali metal salts such as potassium, sodium, and lithium, and alkaline earth metal salts such as calcium are included.

[0021] The constituent monomer from the water-soluble vinyl monomer (a1) can be either the unneutralized form or the neutralized form (constituent monomer of the water-soluble vinyl monomer salt). In addition, from the viewpoints of adhesion reduction, dispersion improvement, and handling of the crosslinked polymer (A), it is preferred that a part or all of the crosslinked polymer (A) be neutralized.

[0022] In the case where neutralization of the constituent monomer from the water-soluble vinyl monomer (a1) included in the crosslinked polymer (A) is performed, it is sufficient to add a hydroxide of an alkali metal such as potassium hydroxide, sodium hydroxide, and lithium hydroxide or an aqueous solution thereof to the monomer stage before polymerization or the aqueous gel after polymerization, but the crosslinking agent (b2) described later that does not hydrolyze under alkaline conditions lacks water solubility, and therefore, if polymerization is performed in a state where the degree of neutralization of the water-soluble vinyl monomer (a1) is high, sometimes even if a prescribed amount of the crosslinking agent (b2) is added, the crosslinking agent (b2) separates from the monomer aqueous solution and prescribed crosslinking cannot be performed, and the crosslinked polymer (A) cannot be obtained, and it is more preferred that the degree of neutralization of the water-soluble vinyl monomer (a1) be set to 0 to 30 mol% so that it also contains the crosslinking agent (b2) and polymerization be performed, and the degree of neutralization be adjusted as needed by adding a hydroxide of an alkali metal to the aqueous gel.

[0023] In the case where an anionic vinyl monomer {most preferably acrylic acid (salt)} is used as the water-soluble vinyl monomer (al) of the crosslinked polymer (A), the final neutralization degree {content of the anionic base (mol%) based on the total number of moles of the anionic group of the anionic vinyl monomer and the anionic base} of the anionic vinyl monomer is preferably from 10 to 90, further preferably from 40 to 85, and particularly preferably from 60 to 80. If this range is satisfied, the impact resistance and discharge characteristics of the negative electrode material become better. Note that the anionic base refers to the neutralized anionic group.

[0024] From the viewpoint of the absorption capacity of the gel (G), the content of the water-soluble vinyl monomer (al) and the vinyl monomer (a2) that becomes (al) by hydrolysis, based on the total weight of (al), (a2), the crosslinking agent (bl) that is hydrolyzed under alkaline conditions, and the crosslinking agent (b2) that is not hydrolyzed under alkaline conditions, is preferably from 98.0 to 99.90% by weight, further preferably from 99.0 to 99.85% by weight, and particularly preferably from 99.2 to 99.83% by weight.

[0025] The water-soluble vinyl monomer (al) and / or the vinyl monomer (a2) that becomes (al) by hydrolysis can each be used alone or in combination with two or more.

[0026] Among the water-soluble vinyl monomer (al) and the vinyl monomer (a2) that becomes (al) by hydrolysis, from the viewpoint of the discharge characteristics of the alkaline battery, (al) is preferably used alone and (al) and (a2) are preferably used in combination, and (al) is further preferably used alone.

[0027] In the case where both the water-soluble vinyl monomer (al) and the vinyl monomer (a2) that becomes (al) by hydrolysis are used as the constituent monomers, from the viewpoint of the discharge characteristics of the alkaline battery, the molar ratio of the constituent monomers from these vinyl monomers {(al) / (a2)} is preferably from 75 / 25 to 99 / 1, further preferably from 85 / 15 to 98 / 2, and most preferably from 90 / 10 to 95 / 5.

[0028] The crosslinked polymer (A) can further include, as the constituent monomers, other vinyl monomers (a3) that can be copolymerized with the water-soluble vinyl monomer (al) and the hydrolyzable vinyl monomer (a2). The other vinyl monomers (a3) can each be used alone or in combination with two or more.

[0029] As the other vinyl monomer (a3) copolymerizable, there is no particular limitation, and a hydrophobic vinyl monomer known (for example, a hydrophobic vinyl monomer disclosed in paragraphs

[0028] to

[0029] of Japanese Patent No. 3648553, a vinyl monomer disclosed in paragraphs

[0025] of Japanese Patent Application Laid-Open No. 2003-165883 and paragraphs

[0058] of Japanese Patent Application Laid-Open No. 2005-75982, etc.) and the like can be used, and specifically, for example, the following (i) to (iii) vinyl monomers and the like can be used.

[0030] (i) aromatic enchainable monomer having 8 to 30 carbon atoms

[0031] styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, and halogen-substituted styrene such as dichlorostyrene, and the like.

[0032] (ii) aliphatic enchainable monomer having 2 to 20 carbon atoms

[0033] olefins (ethylene, propylene, butylene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene and octadecene, etc.); and dienes (butadiene and isoprene, etc.); and the like.

[0034] (iii) alicyclic enchainable monomer having 5 to 15 carbon atoms

[0035] mono-olefinically unsaturated monomers (pinene, limonene and indene, etc.); and polyvinyl monomers [cyclopentadiene, dicyclopentadiene and ethylidenenorbornene, etc.]; and the like.

[0036] The content (mole %) of the other vinyl monomer (a3) unit in the crosslinked polymer (A) is preferably 0 to 5, further preferably 0 to 3, particularly preferably 0 to 2, and especially preferably 0 to 1.5, based on the total moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit, from the viewpoint of absorption performance and the like, and most preferably the other vinyl monomer (a3) constitutes 0 mole % of the monomers.

[0037] The crosslinked polymer (A) is crosslinked using an internal crosslinking agent (b). As the internal crosslinking agent (b), a crosslinking agent (b1) that is hydrolyzed under alkaline conditions and a crosslinking agent (b2) that is not hydrolyzed under alkaline conditions and the like can be cited.

[0038] In the present application, it is preferable to use both (b1) and (b2) together. By using both (b1) and (b2) together, the viscosity stability of the gelling agent (G) is further improved, and the loss of the alkaline electrolyte solution can be prevented, so that the long-term discharge of the battery can be maintained. Furthermore, the electrolyte solution can be injected uniformly at the time of filling of the battery, and the variation in the amount of the electrolyte solution injected per battery is also small, so that it is preferable. Note that, here, the "loss of the alkaline electrolyte solution" means that the substantially uniform mixed state of the gelling agent (G) and the alkaline electrolyte solution cannot be maintained, and the gelling agent (G) and the alkaline electrolyte solution are separated.

[0039] In the crosslinking agent (b1) that is hydrolyzed under alkaline conditions, "hydrolyzed under alkaline conditions" means that the constituent monomer from (b1) has a hydrolyzable bond in the crosslinking polymer (A), and the hydrolyzable bond can be a bond that the crosslinking agent (b1) originally has in the molecule {the crosslinking agent at this time is a crosslinking agent (b11) having a hydrolyzable bond in the molecule}, or a hydrolyzable bond that is generated by the hydrolysis of a bond generated by the crosslinking reaction with other monomers { (a1) or (a2)} that constitute the crosslinking polymer (A) {the bond generated by the crosslinking reaction at this time is a crosslinking agent (b12) that is hydrolyzed}. As the hydrolyzable bond, an ester bond, an amide bond, and the like are included.

[0040] As the crosslinking agent (b11) having a hydrolyzable bond in the molecule, for example, N,N'-methylenebisacrylamide, ethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate, and a copolymerizable crosslinking agent having 2 to 10 ethylenic unsaturated bonds in the molecule, such as polyglycerol (polymerization degree 3 to 13) polyacrylate, can be given.

[0041] As the crosslinking agent (b12) in which the bond generated by the crosslinking reaction is hydrolyzed, a reaction-type crosslinking agent that reacts with a carboxylic acid, such as a polyvalent glycidyl compound (ethylene glycol diglycidyl ether, etc.), a polyvalent isocyanate compound (4,4'-diphenylmethane diisocyanate, etc.), a polyvalent amine compound (ethylene diamine, etc.), and a polyvalent alcohol compound (glycerol, etc.), can be given. The reaction-type crosslinking agent can react with a (meth)acrylic acid (salt) to form an ester bond or an amide bond.

[0042] Among the cross-linking agents (b1) which are hydrolyzed under alkaline conditions, from the viewpoint of the stability of the viscosity of the negative electrode material to which the gelling agent (G) is added, a polyvalent acrylamide compound and a polyvalent acrylate compound are preferred, N,N'-methylenebisacrylamide, ethyleneglycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate are further preferred, and N,N'-methylenebisacrylamide, ethyleneglycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate and ethyleneglycol diglycidyl ether are particularly further preferred, and N,N'-methylenebisacrylamide and trimethylolpropane tri(meth)acrylate are most preferred.

[0043] The cross-linking agent (b2) which is not hydrolyzed under alkaline conditions is a cross-linking agent which does not have a hydrolyzable bond within the molecule and does not generate a hydrolyzable bond due to the cross-linking reaction. As such a cross-linking agent (b2), a cross-linking agent (b21) having two or more vinyl ether bonds and a cross-linking agent (b22) having two or more allyl ether bonds, and the like can be given. From the viewpoint of reactivity and the like, a cross-linking agent having two or more allyl ether bonds is preferred.

[0044] As the cross-linking agent (b21) having two or more vinyl ether bonds, ethyleneglycol divinyl ether, 1,4-butanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, 1,6-hexanediol divinyl ether, polyethyleneglycol divinyl ether (polymerization degree: 2 to 5), bisphenol A divinyl ether, pentaerythritol trivinyl ether, sorbitol trivinyl ether, polyglycerol (polymerization degree: 3 to 13) polyvinyl ether, and the like can be given.

[0045] As the cross-linking agent (b22) having two or more allyl ether bonds, a cross-linking agent (b221) having two allyl groups within the molecule and not having a hydroxyl group, a cross-linking agent (b222) having two allyl groups within the molecule and having one to five hydroxyl groups, a cross-linking agent (b223) having three to ten allyl groups within the molecule and not having a hydroxyl group, a cross-linking agent (b224) having three to ten allyl groups within the molecule and having one to three hydroxyl groups, and the like can be given. When a hydroxyl group is contained within the molecule, the compatibility with the vinyl monomer (a1) and / or (a2) {particularly, (meth)acrylic acid (salt)} is good, the uniformity of cross-linking increases, the performance of the gelling agent (G) improves, and the long-term stability of the viscosity of the negative electrode material containing the gelling agent (G) is further excellent.

[0046] As the cross-linking agent (b221) having two allyl groups within the molecule and not having a hydroxyl group, 1,4-cyclohexanedimethanol diallyl ether, an alkylene (carbon number: 2 to 5) glycol diallyl ether, and a polyalkylene (carbon number: 2 to 6) glycol (weight average molecular weight: 100 to 4000) diallyl ether, and the like can be given.

[0047] As the crosslinking agent (b222) having 2 allyl groups and 1 to 5 hydroxyl groups in the molecule, glycerol diallyl ether, trimethylolpropane diallyl ether and pentaerythritol diallyl ether, polyglycerol (polymerization degree 2 to 5) diallyl ether, and the like can be given.

[0048] As the crosslinking agent (b223) having 3 to 10 allyl groups and no hydroxyl group in the molecule, trimethylolpropane triallyl ether, glycerol triallyl ether, pentaerythritol tetraallyl ether and tetraallyloxyethane, and the like can be given.

[0049] As the crosslinking agent (b224) having 3 to 10 allyl groups and 1 to 3 hydroxyl groups in the molecule, pentaerythritol triallyl ether and diglycerol triallyl ether, sorbitol triallyl ether, polyglycerol (polymerization degree 3 to 13) polyallyl ether, and the like can be given.

[0050] The crosslinking agent (b2) which is not hydrolyzed under alkaline conditions can be used in combination of two or more.

[0051] Among the crosslinking agents (b2), the crosslinking agent (b22) having 2 or more allyl ether bonds is preferable, the crosslinking agents {(b222) and (b224)} having 1 to 5 hydroxyl groups and 2 to 10 allyl groups are further preferable, the crosslinking agent (b224) having 3 to 10 allyl groups and 1 to 3 hydroxyl groups in the molecule is particularly preferable, and pentaerythritol triallyl ether and diglycerol triallyl ether and sorbitol triallyl ether are most preferable. When these crosslinking agents are used, the compatibility with the water-soluble vinyl monomer (a1) and the vinyl monomer (a2) which becomes (a1) by hydrolysis is good, and efficient crosslinking can be performed, and thus they are preferable.

[0052] The content of the crosslinking agent (b1) which is hydrolyzed under alkaline conditions in the crosslinked polymer (A) of the present application also depends on the kind of the crosslinking agent (b1) and the average polymerization degree, and is preferably 0.05 to 1% by weight, further preferably 0.1 to 0.8% by weight, and particularly preferably 0.1 to 0.5% by weight, based on the weight of the crosslinked polymer (A). If it is within this range, excessive liquid loss of the alkaline electrolyte solution can be prevented, and thus the long-term discharge characteristics of the battery are further excellent.

[0053] The content of the crosslinking agent (b2) which is not hydrolyzed under alkaline conditions in the crosslinked polymer (A) also depends on the kind of the crosslinking agent (b2), and is preferably 0.05 to 1% by weight, further preferably 0.05 to 0.5% by weight, and particularly preferably 0.1 to 0.3% by weight, based on the weight of the crosslinked polymer (A). If it is within this range, the long-term discharge characteristics of the battery are further excellent.

[0054] The total content of the cross-linking agent (b1) and the cross-linking agent (b2) is preferably 0.10 to 2.0% by weight, further preferably 0.30 to 1.0% by weight, and particularly preferably 0.40 to 0.8% by weight, based on the weight of the cross-linked polymer (A). If it is within this range, excessive liquid loss of the alkaline electrolyte solution can be prevented, and thus the long-term discharge characteristics of the battery are further excellent. In addition, the stability of the gel agent (G) is improved, and the long-term stability of the viscosity and the temperature stability of the alkaline electrolyte solution containing the gel agent (G) are further excellent.

[0055] The gel agent (G) of the present application can contain a surfactant (D) having an HLB of 1 to 12. Here, "HLB" is an index indicating the balance between hydrophilicity and lipophilicity, and can be calculated from the ratio of the inorganic value to the organic value of an organic compound, for example, by the Oda method described in "Surfactant Primer" (issued by Sanyo Chemical Industries, Co., Ltd. in 2007, written by Takeshi Fujimoto) on page 212.

[0056] HLB = 10 x inorganic value / organic value

[0057] As for the inorganic value and the organic value used to derive the HLB, the values in the table described in "Surfactant Primer" on page 213 can be used.

[0058] As the surfactant (D), both ionic surfactants and nonionic surfactants are included.

[0059] As the ionic surfactant, well-known anionic surfactants, amphoteric surfactants, and cationic surfactants are included, and specifically, the ionic surfactants described in International Publication No. 99 / 03577, International Publication No. 2002 / 005949, and USP 4331447 can be mentioned. As the surfactant (D), from the viewpoint of the viscosity of the gel and the high-speed injectability of the negative electrode material, a nonionic surfactant is preferred.

[0060] Nonionic surfactants do not exhibit ionicity even if they are dissolved in water, but exhibit surface activity. In the present application, the nonionic surfactant is not particularly limited, and from the viewpoint of the viscosity of the gel and the high-speed injectability of the negative electrode material, at least one selected from the group consisting of sucrose fatty acid esters, sorbitan fatty acid esters, glycerol fatty acid esters, and fatty acid amides is preferred.

[0061] As the sucrose fatty acid ester, there are included sucrose fatty acid esters in which a fatty acid having 8 to 22 carbon atoms is ester-bonded to sucrose. Specifically, there are mentioned sucrose stearate [e.g., sucrose stearate manufactured by Daiichi Kogyo Seiyaku Co., Ltd. {DKESTER F-50 (HLB = 6), F-70 (HLB = 8), and F-110 (HLB = 11), etc.}, sucrose stearate manufactured by Mitsubishi Chemical Food Corp. {Ryoto Sugar Ester S-370 (HLB = about 3), S-770 (HLB = about 7), S-970 (HLB = about 9), S-1170 (HLB = about 11), and S-1170F (HLB = about 11), etc.}, etc.] and the like.

[0062] As the sorbitan fatty acid ester, there are included sorbitan fatty acid esters in which a fatty acid having 8 to 22 carbon atoms is ester-bonded to sorbitan. Specifically, there are mentioned sorbitan palmitate [sorbitan palmitate manufactured by Kawaken Co., Ltd. {RHEODOL SP-P10 (HLB = 6.7), etc.} and sorbitan palmitate manufactured by Riken Vitamin Co., Ltd. {RIKENMAL P-300 (HLB = 5.6), etc.}, etc.] and the like.

[0063] As the glycerin fatty acid ester, there are included glycerin fatty acid esters in which a fatty acid having 8 to 22 carbon atoms is ester-bonded to glycerin and / or a polymer (polymerization degree: 2 to 20) of glycerin. Specifically, there are mentioned diglycerin monolaurate [diglycerin monolaurate manufactured by Riken Vitamin Co., Ltd. {POEM DL-100 (HLB = 9.4), etc.}, etc.], diglycerin monomyristate [diglycerin monomyristate manufactured by Riken Vitamin Co., Ltd. {POEM DM-100 (HLB = 8.7), etc.}, etc.], diglycerin monostearate [diglycerin monostearate manufactured by Riken Vitamin Co., Ltd. {POEM DS-100A (HLB = 7.7), etc.}, etc.], diglycerin monooleate [diglycerin monooleate manufactured by Riken Vitamin Co., Ltd. {POEM DO-100V (HLB = 7.3), RIKEMAL DO-100 (HLB = 7.4), etc.}, etc.], decaglycerin stearate [decaglycerin stearate manufactured by Riken Vitamin Co., Ltd. {POEM J-0081HV (HLB = 12), POEM J-0381V (HLB = 12), etc.}, etc.], and the like.

[0064] As the fatty acid amide, a fatty acid amide in which a fatty acid having 8 to 22 carbon atoms is amide-bonded to ethanolamine is included. Specifically, coconut oil fatty acid monoethanolamide [coconut oil fatty acid monoethanolamide {PROFAN AB-20 (HLB = 11) and the like} manufactured by Sanyo Chemical Industries, Inc., stearic acid monoethanolamide [stearic acid monoethanolamide {PROFAN SME (HLB = 10) and the like} manufactured by Sanyo Chemical Industries, Inc., and the like] can be mentioned.

[0065] From the viewpoint of the high-speed injectability of the negative electrode material and the dehydration shrinkage of the negative electrode material, the HLB of the surfactant (D) is preferably 1 to 12, further preferably 3 to 11, and particularly preferably 5 to 9. In addition, as the surfactant (D), from the viewpoint of the high-speed injectability of the negative electrode material and the dehydration shrinkage of the negative electrode material, a nonionic surfactant is preferred, and further, at least one selected from the group consisting of sucrose fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, and fatty acid amide is preferred.

[0066] In the gel (G) of the present application, from the viewpoint of the high-speed injectability of the negative electrode material and the dehydration shrinkage of the negative electrode material, the content of the surfactant (D) is preferably 0.001 to 2.0% by weight, further preferably 0.005 to 1.0% by weight, particularly preferably 0.01 to 0.8% by weight, and most preferably 0.01 to 0.5% by weight, based on the weight of the crosslinked polymer (A).

[0067] In the case where the surfactant (D) is in the form of a powder, the particle size of the surfactant is not particularly limited, and from the viewpoint of the dry-mixing property in the crosslinked polymer (A), the volume average particle size is preferably 0.1 to 2000 μm, further preferably 0.5 to 1500 μm, and particularly preferably 1 to 1000 μm.

[0068] Next, the production method of the gel (G) for alkaline batteries of the present application will be described.

[0069] As the production method of the crosslinked polymer (A), a water-containing gel polymer (containing a crosslinked polymer and water) obtained by a publicly known solution polymerization (adiabatic polymerization, thin film polymerization, and spray polymerization method; Japanese Patent Application Laid-Open No. 55-133413 and the like), a publicly known suspension polymerization method, and a reverse phase suspension polymerization (Japanese Patent Application Laid-Open No. 54-30710, Japanese Patent Application Laid-Open No. 56-26909, Japanese Patent Application Laid-Open No. 1-5808, and the like) is dried and pulverized to obtain. The crosslinked polymer (A) can be one alone or a mixture of two or more.

[0070] The crosslinked polymer (A) can be obtained by polymerizing a monomer composition in which the water-soluble vinyl monomer (al) and / or the vinyl monomer (a2) which becomes the water-soluble vinyl monomer (al) by hydrolysis, and the internal crosslinking agent (b) are essential components, and as the polymerization method, a solution polymerization method is preferred, and it is advantageous in terms of production cost because it does not require the use of an organic solvent or the like, and therefore a water solution polymerization method is particularly preferred, and from the viewpoint of not requiring temperature control during polymerization, a water solution adiabatic polymerization method is most preferred.

[0071] The method of polymerizing the water-soluble vinyl monomer (al) and / or the vinyl monomer (a2) which becomes (al) by hydrolysis, and the internal crosslinking agent (b) using a water solution polymerization method can be a publicly known method, and for example, a method of polymerizing using a radical polymerization initiator, a method of irradiating radiation, ultraviolet rays, electron beams, or the like can be mentioned.

[0072] In the case of using a radical polymerization initiator, as the initiator, azo compounds [azobisisovaleronitrile, azobisisobutyronitrile, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide, 2,2'-azobis(2-imidazolinopropane) hydrochloride, and the like], inorganic peroxides [hydrogen peroxide, potassium persulfate, ammonium persulfate, sodium persulfate, and the like], organic peroxides [di-t-butyl peroxide, cumene hydroperoxide, and the like], redox initiators [a combination of a sulfite or bisulfite of an alkali metal salt, an ammonium sulfite, an ammonium bisulfite, a reducing agent such as L-ascorbic acid, and a persulfate of an alkali metal salt, ammonium persulfate, hydrogen peroxide, and the like], and the like can be mentioned. Two or more of them can be used in combination.

[0073] The polymerization temperature varies depending on the kind of the initiator used, and from the viewpoint of improving the polymerization degree of the polymer, it is preferably -10°C to 100°C, and more preferably -10°C to 80°C.

[0074] The amount of the initiator is also not particularly limited, and from the viewpoint of improving the polymerization degree of the polymer, it is preferably 0.000001 to 3.0% by mass, and further preferably 0.000001 to 0.5% by mass, based on the total weight of the vinyl monomers (al), (a2), the crosslinking agent (b), and other monomers (a3) used as necessary.

[0075] In the case of aqueous solution polymerization, the polymerization concentration (wt%) of the monomers varies depending on the other polymerization conditions, and the water-soluble vinyl monomer (al) and the vinyl monomer (a2) which becomes (al) by hydrolysis easily cause self-crosslinking (self-crosslinking) of the monomers themselves in parallel with the polymerization if the polymerization concentration is increased, resulting in a decrease in the absorption amount, a decrease in the average polymerization degree of the polymer, and in addition, it is difficult to control the temperature during polymerization, easily resulting in a decrease in the average polymerization degree of the polymer and an increase in the oligomer component, and therefore the polymerization concentration is preferably 10 to 40 wt%, and more preferably 10 to 30 wt%. In addition, the polymerization temperature is preferably -10 to 100°C, and more preferably -10 to 80°C. The dissolved oxygen amount during polymerization also depends on the amount of the radical initiator added and the like, but is preferably 0 to 2 ppm (2 x 10 -4 wt% or less, and more preferably 0 to 0.5 ppm (0.5 x 10 -4 wt% or less. If these ranges are satisfied, a crosslinked polymer (A) having a high polymerization degree can be produced.

[0076] The degree of neutralization during polymerization is not particularly limited as long as the internal crosslinking agent (b) of the prescribed amount can be completely dissolved in the monomer aqueous solution, and (b2) lacks water solubility compared to (bl), and in addition, in particular, the solubility of the monomer having an acid group in the aqueous solution is extremely low, and even if (b2) of the prescribed amount is added, (b2) sometimes separates from the monomer aqueous solution and cannot perform the prescribed crosslinking, and therefore the degree of neutralization of the monomer having an acid group during polymerization is preferably 0 to 30 mol%, and further neutralized after polymerization as necessary, and more preferably polymerized in the unneutralized state and further neutralized after polymerization as necessary. In addition, in the case where the monomer having an acid group is polymerized under the same conditions, the polymerization degree easily increases when the degree of neutralization is low, and therefore in order to increase the polymerization degree of the polymer, it is also preferable to polymerize in the state where the degree of neutralization is low.

[0077] In the production of the crosslinked polymer (A), in addition to the fact that a crosslinking agent is not used, it is further preferable that the average polymerization degree of the polymer when the polymer is produced under the same conditions be 5000 to 1000000, and more preferably 10000 to 1000000.

[0078] If the polymerization is performed under the condition where the average polymerization degree is 5000 or more, by using an appropriate amount of the crosslinking agent, it is possible to prevent a decrease in the viscosity and / or an increase in the stringiness of the high-concentration alkaline aqueous solution to which the gelling agent is added. The measurement of the average polymerization degree described above is performed by gel permeation chromatography (GPC method).

[0079] In the present application, the crosslinked polymer (A) obtained by aqueous solution polymerization is obtained in the form of a gel containing water (hydrogel). The hydrogel is used as a gelling agent after drying.

[0080] As the drying method of the water-containing gel, in the case of the aqueous solution polymerization, the following methods can be exemplified: the water-containing gel is subjected to a certain degree of subdivision (the level of the subdivision is about 0.5 to 20 mm square) or strip formation using a meat grinder or a cutting type coarse crusher, and after the neutralization of the water-containing gel by the addition of the alkali metal hydroxide (c), air-through drying (layering the water-containing gel on a punched metal or a screen, and forcibly passing hot air at 50 to 150°C to dry, etc.) or air circulation drying (putting the water-containing gel into a container, and circulating hot air to dry, and further drying while the gel is finely subdivided by a machine such as a rotary kiln) or the like are performed. Among them, the air-through drying can efficiently dry in a short time, and thus is preferred.

[0081] As the other drying method of the water-containing gel in the aqueous solution polymerization, for example, there are a contact drying method in which the water-containing gel is stretched and dried on a drum dryer, etc., but since the water-containing gel has poor heat conductivity, in order to dry, a thin film of the water-containing gel is made on the drum, etc. However, the material of the commercially available drum dryer is usually formed of a metal having a lower ionization tendency than zinc, such as iron, chromium, nickel, etc., and thus the frequency of the contact of each water-containing gel with the metal surface of the drum is extremely high, and in addition, the water-containing gel is a water-containing gel of polyacrylic acid (salt), and thus the content of the metal element having a lower ionization tendency than zinc, which is eluted in the gel, becomes high. Furthermore, the frequency of the contact of the water-containing gel with the drum is extremely high, and the water-containing gel has high adhesion, and thus a material such as a knife is brought into contact with the drum dryer to peel the dried product from the drum dryer, and due to the mechanical wear of the drum and the knife, the metal surface of the drum or the knife is worn, and the metal is mixed into the dried product. As described above, if the contact drying method using the drum dryer or the like is used, the metal ions, metal powder are easily mixed into the gel, and a considerable amount of the metal ions, metal powder of the metal having a lower ionization tendency than zinc (the metal represented by the atomic symbol of Cr, Fe, Ni, Sn, Pb, Cu, Hg, Ag, etc. since it is a metal having a lower standard electrode potential than zinc) is contained. When these gels are used as the gel for the alkaline battery, the zinc powder in the battery forms a battery between the metal ions or metal powder having a lower ionization tendency than zinc, and thus hydrogen gas is generated by electrolysis, and thus the pressure in the battery rises, and further, the outflow of the alkaline electrolyte, and in a serious case, the breakage of the battery are sometimes caused. Furthermore, for the thin film-like dried product in which the water-containing gel is stretched and dried on the drum dryer, etc., even if the pulverization is performed thereafter to adjust the particle diameter of the dried product to the desired particle diameter, the particles become scale-like, and thus the strength is extremely weak, and if the swollen gel is mechanically mixed with the zinc powder in a high concentration alkaline aqueous solution, the swollen gel is broken, and the gel becomes small. Therefore, the contact drying method using the drum dryer or the like is not preferred.

[0082] In the present application, the drying temperature when the aqueous gel is dried is preferably 50 to 150°C, more preferably 80 to 130°C, depending on the type of drying machine used, the drying time, etc. If the drying temperature is 150°C or less, the polymer is not easily crosslinked by heat during drying, the crosslinking degree does not excessively increase due to thermal crosslinking, the absorption amount does not decrease, and the viscosity in the alkaline electrolyte does not decrease. If it is 50°C or more, drying does not require a long time and is efficient. The drying time also varies depending on the type of drying machine used, the drying temperature, etc., and is preferably 5 to 300 minutes, more preferably 5 to 120 minutes.

[0083] The dried product of the crosslinked polymer (A) thus obtained is powdered by pulverization as needed. The pulverization method can be a publicly known method, and for example, an impact pulverizer (pin mill, cutter mill, Skirel mill, ACM pulverizer, etc.), an air pulverizer (jet mill, etc.) can be used.

[0084] The powdered crosslinked polymer (A) can be collected as a dried powder having a desired particle size by using a sifter (vibrating sifter, centrifugal sifter, etc.) having a desired screen, as needed.

[0085] The volume average particle diameter of the gelling agent (G) in the present application is preferably 20 to 500 μm, more preferably 30 to 400 μm, and particularly preferably 30 to 170 μm.

[0086] If the volume average particle diameter is in this range, the viscosity of the alkaline electrolyte to which the gelling agent (G) is added becomes in an appropriate range, the liquid break of the negative electrode material becomes good, and thus a battery with stable quality can be manufactured, and the settlement of zinc powder in the negative electrode material can be prevented, and thus a battery with excellent discharge characteristics over time can be produced.

[0087] Note that the volume average particle diameter described above is measured by the following method.

[0088] <Measurement method of volume average particle diameter of gelling agent (G)>

[0089] The gelling agent (G) of the present application is dispersed in methanol, and measured using a laser diffraction particle size distribution measuring device [Microtrac (manufactured by NIKKISO CO., LTD.)]. Note that the volume average particle diameter of the gelling agent (G) in the examples described below is measured by the above method.

[0090] The crosslinked polymer (A) can be reacted with a surface crosslinking agent as needed, and the surface can be subjected to crosslinking treatment.

[0091] As the surface crosslinking agent, a publicly known surface crosslinking agent, for example, a surface crosslinking agent described in Japanese Patent Application Laid-Open No. 2003-225565 can be used.

[0092] Among these surface crosslinking agents, from the viewpoint of the discharge characteristics of the alkaline battery, a crosslinking agent having at least two or more functional groups capable of reacting with the carboxyl group of the acrylic acid (al) is preferable, a polyglycidyl group is further preferable, ethylene glycol diglycidyl ether and glycerol diglycidyl ether are particularly preferable, and ethylene glycol diglycidyl ether is most preferable.

[0093] From the viewpoint of the discharge characteristics of the alkaline battery, the content (mole %) of the surface crosslinking agent based on the number of moles of the constituting monomers is preferably 0.001 to 0.30, further preferably 0.005 to 0.25, and particularly preferably 0.010 to 0.20.

[0094] The method of the surface crosslinking reaction can apply a publicly known method {for example, Japanese Patent No. 3648553, Japanese Patent Application Laid-Open No. 2003-165883, Japanese Patent Application Laid-Open No. 2005-75982, Japanese Patent Application Laid-Open No. 2005-95759}.

[0095] From the viewpoint of the high-speed injection of the negative electrode material, the gel agent (G) of the present application preferably has the surface active agent (D) in the vicinity of the surface of the crosslinked polymer (A). As the substance having the surface active agent (D) in the vicinity of the surface of the crosslinked polymer (A), a substance obtained by the following method can be mentioned.

[0096] (1) a method of directly mixing the surface active agent (D) as a solid in the crosslinked polymer (A) in the form of dry blending, for example;

[0097] (2) a method of dispersing the surface active agent (D) in the form of a slurry in water or a hydrophilic organic solvent and mixing in the crosslinked polymer (A);

[0098] (3) a method of dissolving the surface active agent (D) in a hydrophobic organic solvent, impregnating the crosslinked polymer (A), and performing drying.

[0099] Among these mixing methods, from the viewpoint of the easiness of drying and the small amount of residual solvent, (1) is preferable.

[0100] In the gel agent (G) of the present application, an additive can be added at an arbitrary stage {in the polymerization step in the manufacturing process of the crosslinked polymer (A), the chopping step, the drying step, the pulverization step, the surface crosslinking step, and / or before and after these steps, and after the step of mixing (A) and (D), etc.} as needed.

[0101] Note that in the present application, it is preferable to remove the metal powder such as iron mixed in at any stage after drying using a magnetic iron removing machine. However, even if the iron removing machine is used to perform iron removal with high precision, it is difficult to remove metals that do not have magnetism using the iron removing machine, and furthermore, it is not possible to remove metals having magnetism contained in the inside of the dried polymer particles or adhered to the dried particles. Therefore, it is desirable to take sufficient measures with respect to the production equipment in order to not mix these metals from the beginning.

[0102] The neutralization uniformity of the gelling agent (G) in the present application is 60 to 90%, preferably 65 to 85%, and further preferably 70 to 80%. If the neutralization uniformity is within the range of 60 to 90%, the viscosity of the alkaline electrolyte to which the gelling agent (G) is added becomes within an appropriate range, the breakage of the negative electrode material becomes good, and thus a battery of which the quality is stable can be manufactured, and the precipitation of zinc powder in the negative electrode material can be prevented, and thus a battery of which the discharge characteristics over time are excellent can be produced. On the other hand, if the neutralization uniformity is less than 60%, the breakage of the negative electrode material of the alkaline battery to which the gelling agent (G) is added deteriorates, the filling amount deviates, and when it exceeds 90%, the viscosity stability of the gelling agent (G) decreases, and the precipitation of zinc powder occurs, and thus there is a tendency that the impact resistance and the heat resistance deteriorate.

[0103] The neutralization uniformity of the gelling agent (G) can be appropriately adjusted by the timing of the addition of the alkali metal hydroxide (c) at the time of production, the subdivision and drying conditions of the aqueous gel, or the mixing of crosslinked polymers (A) having different neutralization degrees. As a method of decreasing the neutralization uniformity, there can be mentioned not adding the alkali metal hydroxide (c) at the time of polymerization, adding the alkali metal hydroxide (c) to the aqueous gel after polymerization to perform neutralization, or mixing crosslinked polymers (A) having different neutralization degrees. On the other hand, as a method of increasing the neutralization uniformity, there can be mentioned performing polymerization after neutralization by adding the alkali metal hydroxide (c), or increasing the contact frequency of the aqueous gel with the alkali metal hydroxide (c) by mixing and chopping the aqueous gel after the addition of the alkali metal hydroxide (c) using a chopper.

[0104] The neutralization uniformity of the gelling agent (G) is measured by the following method.

[0105] <Measurement method of neutralization uniformity>

[0106] The sample sheet for measurement is produced by the following method.

[0107] A measuring sample was spread on one side of a substrate prepared by adhering one side of a double-sided tape (4 cm x 4 cm: "NICETACK" manufactured by NICHIBAN Co., Ltd.) to a sheet of polyethylene (5 cm x 5 cm) in a manner so as to fill the surface without gaps. Next, the substrate was turned over, and the excess measuring sample that was not adhered was shaken off. A BBT solution (bromothymol blue: 400 mg, methanol: 200 mL, water: 200 mL) was sprayed at 0.2 g / sec toward the surface of the substrate for 10 seconds. After 20 seconds, the spraying was further performed at 0.1 g / sec for 10 seconds, and a sample sheet was prepared.

[0108] The neutralization uniformity was measured in the following manner.

[0109] A photograph was taken in a room with white illumination that was not exposed to sunlight, using a pixel of 8 megapixels or more. The sample sheet 20 seconds after the spraying of the BBT solution was used in the photograph.

[0110] The photograph after the photographing was analyzed using the image analysis software "WinROOF" for Windows. First, the total area of the sample (Gl) was calculated. The monochromatization of the image was performed by selecting [Image processing], [Monochrome image] from the menu. Next, [Binary processing], [Binaryization based on two thresholds] was selected, and the threshold was adjusted visually so as to make the boundary of the measurement region coincide with the boundary of the sample. Then, [Measurement], [Total area · number] was selected, and the calculated value was set as the total area of the sample (Gl).

[0111] Next, the area of the specified color of the sample (G2) was calculated. The binary processing was set to the color extraction mode, and the hue of the specified color was set to the range of 60 to 75, the lightness to the range of 23 to 120, and the chroma to the range of 40 to 255. The measurement was set to the total area · number mode, and the calculated value was set as the area of the specified color (G2). The neutralization uniformity was calculated in the following manner.

[0112] Neutralization uniformity (%) = (G2) / (Gl) x 100

[0113] It should be noted that the neutralization uniformity of the gelling agent in the examples described later was measured in the above-described manner.

[0114] The viscosity (Nl(40)) of the gel (GA) of the gelling agent (G) of the present application is preferably 70 to 120 Pa-s, further preferably 80 to 110 Pa-s, and particularly preferably 90 to 100 Pa-s. If it is in this range, the long-term discharge characteristics are further excellent. Here, the gel (GA) is a gel prepared by stirring and mixing 97 parts by weight of a 40% by weight aqueous potassium hydroxide solution and 3 parts by weight of the gelling agent (G) until uniform, and is a gel after 24 hours at 40°C. The viscosity (Nl(40)) of this gel (GA) was measured in the following manner.

[0115] Method for measuring viscosity (Nl(40)) of gel (GA)

[0116] The viscosity of the gel (GA) at 40°C was measured as the viscosity of the gel (GA) using a digital B-type viscometer (manufactured by TOKIMEC Corporation) in accordance with JIS 7117-1:1999. Note that the measurement was performed using a No. 4 rotor at a rotation speed of 3 rpm. Note that the viscosity of the gel (GA) in the examples described later was measured in accordance with the above method.

[0117] In addition, the ratio (Nl(40) / N60(40)) of the viscosity (Nl(40)) of the gel (GA) of the gel (G) of the present application to the viscosity (N60(40)) after further 59 days at 40°C is preferably 0.85 to 1.15, and further preferably 0.90 to 1.10. If this range is satisfied, the zinc powder in the electrolyte is less likely to settle, and thus the discharge characteristics and the impact resistance are further excellent. The ratio (Nl(40) / N60(40)) of the viscosity of the gel (GA) is measured by the following method. Note that the ratio (Nl(40) / N60(40)) of the viscosity of the gel (GA) in the examples described later was measured in accordance with the following method.

[0118] Method for measuring ratio (Nl(40) / N60(40)) of viscosity of gel (GA)

[0119] The sample whose measurement of the viscosity (Nl(40)) of the gel (GA) was completed was sealed and further left in a thermostat at 40°C for 59 days. The viscosity of the gel (GA) obtained by measurement under the same conditions as the viscosity (Nl(40)) was taken as the viscosity (N60(40)) of the gel (GA) after left for 60 days. The ratio (Nl(40) / N60(40)) of the viscosity of the gel (GA) was calculated by the following equation.

[0120] Ratio (Nl(40) / N60(40)) of viscosity (Nl(40)) of gel (GA) to viscosity (N60(40)) after further 59 days at 40°C = {viscosity (Nl(40))} / {viscosity (N60(40))}

[0121] Further, the ratio (Nl(40) / Nl(150)) of the viscosity (Nl(40)) of the gel (GA) of the gel agent (G) of the present application to the viscosity (Nl(150)) of the gel (GA) after temperature adjustment at 150°C is preferably 0.85 to 1.15, further preferably 0.90 to 1.10. If it is in this range, the zinc powder in the electrolyte under high temperature conditions is more unlikely to settle, and thus the impact resistance and heat resistance are further excellent. The viscosity ratio (Nl(40) / Nl(150)) of the gel (GA) is measured by the following method. Note that the viscosity ratio (Nl(40) / Nl(150)) in the temperature change of the gel (GA) in the Examples described later is measured according to the following method.

[0122] <Measurement method of viscosity ratio (Nl(40) / Nl(150)) of gel (GA)>

[0123] The sample after the measurement of (Nl(40)) of the gel (GA) is sealed and temperature-adjusted in a thermostat at 150°C for 10 minutes. After temperature adjustment at 150°C for 10 minutes, temperature adjustment is performed at 40°C for 1 hour. The viscosity of the gel (GA) is measured under the same conditions as the viscosity (Nl(40)), as the viscosity (Nl(150)) of the gel (GA) after temperature adjustment at 150°C. The viscosity ratio (Nl(40) / Nl(150)) of the gel (GA) is calculated by the following equation.

[0124] Viscosity ratio (Nl(40) / Nl(150)) of gel (GA) = {viscosity (Nl(40))} / {viscosity (Nl(150))}

[0125] <Alkaline battery>

[0126] The alkaline battery of the present application has a gel-like negative electrode containing the gel agent (G) and zinc powder. As the alkaline battery having a gel-like negative electrode containing the gel agent (G) and zinc powder, there is no particular limitation, and it can be applied not only to general alkaline batteries such as LR-20 (single 1 type alkaline battery), LR-6 type (single 3 type alkaline battery), but also to other various alkaline batteries. The alkaline battery generally has a structure in which a positive agent, a current collector rod, and a gel negative electrode are enclosed in an outer can, and the positive agent and the gel negative electrode are separated by a separator or the like.

[0127] As a method of filling the gel-like negative electrode containing the gel agent (G) and zinc powder into an alkaline battery, the following methods can be exemplified:

[0128] (1) A method of producing a gel-like negative electrode by previously mixing the gelling agent (G), an alkaline electrolyte solution (e.g., an aqueous potassium hydroxide solution having a high concentration, which contains zinc oxide or the like as necessary), zinc powder (and / or zinc alloy powder), and other additives as necessary, preparing a mixture of negative electrode material, and filling it into a negative electrode container of a battery;

[0129] (2) A method of producing a gel-like negative electrode by filling the gelling agent (G) and zinc powder (and / or zinc alloy powder) and other additives as necessary into a negative electrode container of a battery, and then filling an alkaline electrolyte solution, and the like.

[0130] Among them, the method of the above (1) in which zinc powder is uniformly dispersed in the negative electrode container of the battery is preferred. The amount of the gelling agent (G) to be added varies depending on the structure of the negative electrode container, the particle size of the zinc powder, and the concentration of the alkaline electrolyte solution, and is preferably 0.5 to 10% by weight, and further preferably 1.0 to 5.0% by weight, based on the weight of the alkaline electrolyte solution. If the amount of the gelling agent to be added is 0.5 to 10% by weight, the viscosity of the alkaline electrolyte solution containing the gelling agent becomes moderate, and the settling of the zinc powder can be prevented, and the workability is also easy.

[0131] The settling of the zinc powder of the gelling agent (G) is preferably less than 10 mm, and more preferably less than 5 mm. Note that the settling of the zinc powder of the gelling agent (G) is measured by the method described in the examples.

[0132] Example

[0133] Hereinafter, the present application will be further described by examples and comparative examples, but the present application is not limited thereto. Hereinafter, unless otherwise specified, 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.

[0134] Example 1

[0135] In a 3-liter adiabatic polymerization tank, 280.0 g of acrylic acid, 0.50 g of pentaerythritol triallyl ether (0.18% by weight relative to acrylic acid), 0.45 g of trimethylolpropane triacrylate (0.16% by weight relative to acrylic acid), and 720 g of ion exchange water were added, the acrylic acid aqueous solution was adjusted by stirring the mixture, and then the acrylic acid aqueous solution was cooled to 3°C. After cooling, nitrogen was introduced into the acrylic acid aqueous solution at a flow rate of 5 L / min to make the dissolved oxygen concentration in the acrylic acid aqueous solution 0.10 ppm or less. The dissolved oxygen concentration was measured using an oxygen concentration meter based on a membrane electrode method (ORBISPHERE 510, manufactured by HACH ULTRA). After confirming that the acrylic acid aqueous solution was 3°C, 5.0 g of a 2,2'-azobis(2-amidinopropane) hydrochloride aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-50) having a concentration of 10% by weight as a polymerization initiator, 5.0 g of hydrogen peroxide water having a concentration of 1.0% by weight, 5.0 g of an L-ascorbic acid aqueous solution having a concentration of 1.0% by weight, and 5.0 g of an iron (III) sulfate aqueous solution having a concentration of 0.1% by weight were added to the adiabatic polymerization tank while continuing to introduce nitrogen. After adding the polymerization initiator, the introduction of nitrogen was continued for 25 minutes, and then the introduction of nitrogen was stopped, and the polymerization reaction was performed by standing for 16 hours. After standing for 16 hours, the hydrogel obtained by the polymerization reaction was taken out of the polymerization tank. The taken-out hydrogel was shredded using a shredder (12VR-400K, manufactured by ROYAL, screen plate diameter 8 mm) at a gel temperature of 90°C, and after adding 280.0 g of a 49% by weight sodium hydroxide (reagent special grade) aqueous solution to the finely divided hydrogel, the hydrogel was uniformly mixed using the above-described shredder to perform neutralization. After the neutralization mixing, the hydrogel was further mixed and shredded using the above-described shredder. The neutralized and mixed hydrogel was layered on a screen having a mesh size of 850 μm made of SUS in a thickness of 5 cm, and a hot air of 150°C was introduced into the hydrogel using a small-sized air-through drier (manufactured by Inoue Metal Co., Ltd.) for 1 hour to evaporate the moisture in the hydrogel, and a dried gel was obtained. The dried gel was pulverized using a cooking mixer, and a gel having a particle size of 75 μm (200 mesh) was collected using a sieve to obtain a gel agent (G-1) of the present application.

[0136] Example 2

[0137] In Example 1, the amount of acrylic acid added was 250.0 g, the amount of pentaerythritol triallyl ether added was 0.55 g (0.22% by weight relative to acrylic acid), the amount of trimethylolpropane triacrylate added was 0.45 g (0.18% by weight relative to acrylic acid), the amount of ion exchange water added was 750.0 g, and the amount of a 49% by weight sodium hydroxide (reagent special grade) aqueous solution added was 250.0 g, and the same operation as in Example 1 was performed to obtain a gel agent (G-2) of the present application.

[0138] Example 3

[0139] In Example 2, after the neutralization kneading was performed by adding 250.0 g of a 49 wt% aqueous sodium hydroxide (reagent special grade) solution to the finely divided aqueous gel, 0.5 g of sucrose stearate (HLB: 7) was further added, and the aqueous gel was uniformly kneaded and shredded using the above-described shredder, and the same operations as in Example 2 were performed except for this, to obtain a gel agent (G-3) of the present application.

[0140] Example 4

[0141] In Example 2, after the neutralization kneading was performed by adding 250.0 g of a 49 wt% aqueous sodium hydroxide (reagent special grade) solution to the finely divided aqueous gel, the aqueous gel was kneaded and shredded without using the above-described shredder, and the same operations as in Example 2 were performed except for this, to obtain a gel agent (G-4) of the present application.

[0142] Comparative Example 1

[0143] In Example 1, after the neutralization kneading, the aqueous gel was further kneaded and shredded using the above-described shredder, and the same operations as in Example 1 were performed except for this, to obtain a comparative gel agent (H-1).

[0144] Comparative Example 2

[0145] In Example 4, the screen plate diameter of the shredder (12VR-400K manufactured by ROYAL) used was made to be 16 mm, and the same operations as in Example 4 were performed except for this, to obtain a comparative gel agent (H-2).

[0146] The results of measuring the neutralization uniformity and the viscosity of the gels (GA) using the above-described methods for the gel agents (G-1) to (G-4) produced in Examples 1 to 4 and the comparative gel agents (H-1) and (H-2) produced in Comparative Examples 1 and 2 are shown in Table 1. Note that the volume average particle diameters of the gel agents (G-1) to (G-4) produced in Examples 1 to 4 and the comparative gel agents (H-1) and (H-2) produced in Comparative Examples 1 and 2 were all 50 μm.

[0147] [Table 1]

[0148]

[0149] Further, the results of measuring the sedimentation of zinc powder and the deviation of the injection amount using the gel agents (G-1) to (G-4) of the present application and the comparative gel agents (H-1) and (H-2) are shown in Table 2.

[0150] (1) Sedimentation of zinc powder

[0151] In a biaxial kneader (manufactured by Nippon Gohsei Co., Ltd., trade name: PNV-1) having a capacity of 1 liter, 150 g of a 40% by weight potassium hydroxide aqueous solution and 300 g of zinc powder (manufactured by UNION MINIERES.A. Co.) having a volume average particle diameter of 200 μm, and 3.0 g of a gelling agent were added, and mixed at a rotation speed of 50 rpm for 60 minutes to produce a negative electrode material. 50 g of the produced negative electrode material was put in a sample bottle (diameter: 34 mm, height: 77 mm, made of polypropylene) capable of being sealed, and the bubbles that had entered during the mixing were degassed under reduced pressure. The sample bottle was sealed and, after being left in a thermostat at 40°C for 60 days, the sample bottle was tapped gently 300 times at a rate of 30 times / minute from a height of 3 cm using a device attached to a powder tester (manufactured by Hosokawa Micron Corporation) to promote the sedimentation of the zinc powder. After the end of the gentle tapping, the distance (mm) from the initial position of the zinc powder (the position of the upper end of the negative electrode material in the sample bottle) to the most settled position of the zinc powder was measured as the sedimentation property (mm) of the zinc powder. The sedimentation property of the zinc powder was evaluated in accordance with the following evaluation criteria.

[0152] < Evaluation Criteria >

[0153] ◎: less than 5.0 mm

[0154] O: 5.0 mm or more and less than 10.0 mm

[0155] X: 10.0 mm or more

[0156] (2) Deviation of injection amount

[0157] In a biaxial kneader having a capacity of 1 liter, 150 g of a 40% by weight potassium hydroxide aqueous solution, 300 g of zinc powder (manufactured by UNION MINIERES.A. Co.) having a volume average particle diameter of 200 μm, and 3.0 g of a gelling agent were added, and mixed at a rotation speed of 50 rpm for 60 minutes to produce a negative electrode material. The produced negative electrode material was moved to a beaker, and the bubbles that had entered during the mixing were degassed under reduced pressure. The negative electrode material after the degassing was sucked into the inside of a 10-ml syringe having an injection port having an inner diameter of 2 mm and having a scale of 0.1-ml units. From the height of the mouth of a 5-ml sample bottle (inner diameter: 18 mm, height: 40 mm), the syringe was pressed into 5.0 ml, and the negative electrode material was injected into the sample bottle, and the weight of the negative electrode gel injected into the sample bottle was measured. The same operation was repeated a total of 20 times, and the standard deviation (σ) of the injection amount was calculated as the deviation of the injection amount. The deviation of the injection amount was evaluated in accordance with the following evaluation criteria.

[0158] < Evaluation Criteria >

[0159] ◎: 0.02 or less

[0160] O: 0.03 or more and 0.10 or less

[0161] X: 0.11 or more

[0162] The evaluation results are shown in Table 2.

[0163] [Table 2]

[0164]

[0165] Industrial applicability

[0166] The gel (G) of the present application is useful not only as a cylindrical alkaline battery, but also as a gel for primary and secondary alkaline batteries such as alkaline button batteries, silver oxide batteries, nickel-cadmium storage batteries, nickel-hydrogen storage batteries, and the like. In addition, the alkaline battery using the gel of the present application is excellent in impact resistance and heat resistance, is excellent in the maintenance of discharge characteristics, and is excellent in the viscosity stability of the negative electrode material, and thus is useful as an alkaline battery improved in production efficiency and safety.

Claims

1. A gelling agent for alkaline batteries, characterized in that, The alkaline battery gel contains a crosslinked polymer (A) comprising a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which is hydrolyzed to become a water-soluble vinyl monomer (a1) and an internal crosslinking agent (b), a portion of which is neutralized by an alkali metal hydroxide (c), and the neutralization uniformity of which is 60% to 90%.

2. The gelling agent for alkaline batteries according to claim 1, wherein, The internal crosslinking agent (b) includes a crosslinking agent (b1) that can be hydrolyzed under alkaline conditions and a crosslinking agent (b2) that does not hydrolyze under alkaline conditions.

3. The gelling agent for alkaline batteries according to claim 1 or 2, wherein, The gel (GA) was prepared by stirring 97 parts by weight of a 40% by weight potassium hydroxide aqueous solution and 3 parts by weight of the alkaline battery gelling agent until homogeneous, and the viscosity N1 (40) of the gel (GA) after being placed at 40°C for 24 hours was 70 Pa·s to 120 Pa·s.

4. The gelling agent for alkaline batteries according to claim 1 or 2, wherein, The gel (GA) prepared by mixing 97 parts by weight of a 40% by weight aqueous solution of potassium hydroxide and 3 parts by weight of the alkaline battery gelling agent until homogeneous, and the viscosity N1 (40) of the gel (GA) after being placed at 40°C for 24 hours and the viscosity N60 (40) after being placed at 40°C for 59 days, has a ratio N1 (40) / N60 (40) of 0.85 to 1.

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5. The gelling agent for alkaline batteries according to claim 1 or 2, wherein, The gel (GA) was prepared by stirring 97 parts by weight of a 40% by weight aqueous solution of potassium hydroxide and 3 parts by weight of the alkaline battery gelling agent until homogeneous. The ratio of the viscosity N1 (40) of the gel (GA) after being placed at 40°C for 24 hours to the viscosity N1 (150) of the gel (GA) after temperature adjustment at 150°C was 0.85 to 1.

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6. The gelling agent for alkaline batteries according to claim 1 or 2, wherein, The alkaline battery gel also contains a surfactant (D) with an HLB value of 1 to 12.

7. The gelling agent for alkaline batteries according to claim 6, wherein, The surfactant (D) is selected from at least one of sucrose fatty acid esters, sorbitan fatty acid esters, glycerol fatty acid esters, and fatty acid amides.

8. An alkaline battery, characterized in that, The battery has a gel-like negative electrode containing an alkaline battery gelling agent and zinc powder. The alkaline battery gelling agent contains a crosslinked polymer (A) composed of a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) through hydrolysis, and an internal crosslinking agent (b). A portion of the crosslinked polymer (A) is neutralized by an alkali metal hydroxide (c), and the neutralization uniformity of the alkaline battery gelling agent is 60% to 90%.

9. The alkaline battery according to claim 8, wherein, The zinc powder in the gelling agent for alkaline batteries has a settling property of less than 10.0 mm.

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