JP2008081643A - Carbon binder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon binder excellent in the adhesiveness of the binder under the condition of a repetitive temperature change of a high temperature of ≥50°C and a low temperature of ≤0°C (heat shock test). <P>SOLUTION: The carbon binder comprises a polymer having a structural unit derived from a conjugated diene-based compound, a structural unit derived from an aromatic vinyl-based compound and a structural unit derived from an ethylenic unsaturated carboxylic acid-based compound, and an antioxidant, wherein the temperature at which the polymer has maximum loss angle tangent (tanδ) measured by dynamic viscoelastic measurement is from -10°C to 60°C and the maximum value of the loss angle tangent (tanδ) is from 0.3 to 1.5, and the method for producing the binder is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a carbon binder excellent in heat transfer used in electronic devices, various displays, other devices, devices, etc., and can be stored at high temperature and low temperature under a high temperature condition of 50 ° C. or higher and a low temperature condition of 0 ° C. or lower. The present invention relates to a carbon binder excellent in adhesion to a base of a binder under repeated temperature change (heat shock test) conditions.

  In recent years, carbon binders excellent in heat dissipation or heat transfer have attracted attention, starting with electronic devices and various display fields. For example, in an electronic device such as a personal computer, the amount of heat generated has been increasing due to an increase in the operating frequency of a CPU (central processing unit) in recent years, and power consumption is also increasing for components other than the CPU. . On the other hand, the device itself is required to be further reduced in size and weight, and in addition to this, there is a demand for noise reduction and power consumption reduction. Therefore, a heat dissipation system that does not depend on air cooling by a fan is required. Also in the field of displays, for example, in a plasma display, it is a big problem to suppress a temperature rise due to heat generation, and measures for heat dissipation are required also in displays such as organic EL.

  In such a field, a member called a carbon binder is used (in particular, refer to Patent Document 1). This material works to conduct heat and is soft and can keep the contact thermal resistance between members low, but it can be repeatedly stored at high temperature and low temperature under a high temperature condition of 50 ° C or higher and a low temperature condition of 0 ° C or lower. Adhesion of the binder to the substrate under the temperature change (heat shock test) conditions was insufficient and not satisfactory.

JP 2006-137860 A

  In this situation, the point of designing and producing the carbon binder is that the material used (such as graphite) generates very little dust, does not cause a short circuit inside the electronic device, has a certain flexibility, Heat transfer between members can be sufficiently achieved without pressure, and good adhesion to the substrate is required, but high temperature storage and low temperature under high temperature conditions of 50 ° C or higher and low temperature conditions of 0 ° C or lower. The present condition is that there is no carbon binder having good adhesion to the base of the binder under temperature change (heat shock test) conditions in which storage is repeated.

  Recently, a carbon binder with excellent adhesive properties under rapidly changing characteristics (especially temperature change (heat shock test) under repeated high temperature storage above 50 ° C and low temperature storage below 0 ° C). There is to do.

  As a result of intensive studies to obtain a carbon binder excellent in binder adhesion under temperature change (heat shock test) conditions in which high temperature storage at 50 ° C. or higher and low temperature storage at 0 ° C. or lower is repeatedly performed, the present inventors have conjugated dienes. A polymer containing a structural unit derived from an aromatic compound, a structural unit derived from an aromatic vinyl compound, and a structural unit derived from an ethylenically unsaturated carboxylic acid compound, and an antioxidant, the polymer comprising dynamic viscoelasticity By using a carbon binder having a maximum loss angle tangent (tan δ) of measurement of −10 to 60 ° C. and a maximum value of loss angle tangent (tan δ) of 0.3 to 1.5, 50 The present invention is completed by finding that the adhesiveness of the binder is good under the temperature change (heat shock test) conditions in which high temperature storage above 0 ° C. and low temperature storage below 0 ° C. are repeated. I arrived.

  The present invention comprises a polymer containing a structural unit derived from a conjugated diene compound, a structural unit derived from an aromatic vinyl compound, and a structural unit derived from an ethylenically unsaturated carboxylic acid compound, and an antioxidant, A carbon binder in which the polymer has a temperature at which the loss angle tangent (tan δ) of dynamic viscoelasticity measurement is maximized at −10 to 60 ° C., and the maximum value of the loss angle tangent (tan δ) is 0.3 to 1.5. A method for producing the carbon binder is provided.

  According to the carbon binder of the present invention, it is possible to obtain a binder compound having excellent adhesion even at a low temperature of 0 ° C. or lower. A carbon binder having excellent adhesion can be obtained.

  In the carbon binder of the present invention, the temperature at which the polymer has the maximum loss angle tangent (tan δ) in dynamic viscoelasticity measurement is −10 to 60 ° C., and the maximum value of the loss angle tangent (tan δ) is 0.3 to 1.5 is not particularly limited, but for example, a polymer containing a structural unit derived from a conjugated diene compound, a structural unit derived from an aromatic vinyl compound, and a structural unit derived from an ethylenically unsaturated carboxylic acid compound And an antioxidant, wherein the antioxidant contains 0.01 to 5.0 parts by weight with respect to 100 parts by weight of the polymer.

  When the temperature at which the loss tangent (tan δ) of the dynamic viscoelasticity measurement of the polymer is maximum is less than −10 ° C., it is not preferable from the viewpoint of a decrease in adhesive strength at high temperatures. Moreover, when it exceeds 60 degreeC, it is unpreferable from the point that the adhesiveness at the time of initial bonding is inferior. Furthermore, when the maximum value of the loss angle tangent (tan δ) is less than 0.3 or more than 1.5, the adhesiveness varies, and there is a tendency that a part with poor adhesiveness is partially mixed. It is not preferable.

  Hereafter, the polymer used for the binder for secondary battery electrodes of this invention is explained in full detail.

  In order for the polymer to have a loss angle tangent (tan δ) in the dynamic viscoelasticity measurement of −10 to 60 ° C. and a maximum value of the loss angle tangent (tan δ) of 0.3 to 1.5, a conjugated diene system The ratio of the compound to the aromatic vinyl compound can be obtained by emulsion polymerization at a ratio of 50/50 to 12/88% by weight. Alternatively, emulsion polymerization may be carried out by supplying a monomer emulsion obtained by mixing a polymerizable monomer mixture and water in advance into a reaction vessel.

  Hereinafter, the polymer used for the carbon binder of the present invention will be described in detail.

  The structural unit derived from the conjugated diene compound contained in the polymer is given by a conjugated diene monomer, and specific examples thereof include 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene. 1,3-pentadiene, 2,4-hexadiene and the like, but are not limited thereto. These conjugated diene monomers can be used as one kind or a mixture of two or more kinds. The content of the conjugated diene monomer is 10 to 70% by weight of the total polymer monomer, preferably 10 to 60% by weight, and particularly preferably 10 to 50% by weight. If the amount of the conjugated diene monomer is too large, the strength of the binder is insufficient. Conversely, if the amount is too small, the flexibility is insufficient.

  The structural unit derived from the aromatic vinyl compound contained in the polymer is given by an aromatic vinyl monomer, and specific examples thereof include styrene, α-methylstyrene, vinyltoluene, vinylanisole, α-halostyrene, vinyl. Naphthalene, divinylstyrene and the like can be mentioned, but are not limited thereto. These aromatic vinyl monomers can be used as one kind or a mixture of two or more kinds.

  The structural unit derived from the ethylenically unsaturated carboxylic acid compound contained in the polymer is particularly limited as long as it is given by the ethylenically unsaturated carboxylic acid monomer and has a carboxyl group and an ethylenically unsaturated group in the molecule For example, acrylic acid, methacrylic acid, 2- (meth) acryloylpropionic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and the like can be used, and one or a mixture of two or more of these can be used. Can do. In particular, it is preferable to use an ethylenically unsaturated dicarboxylic acid compound such as itaconic acid, maleic acid or fumaric acid in terms of the adhesive strength of the substrate. The content of the ethylenically unsaturated dicarboxylic acid compound is preferably 0.05 or more of the total polymerizable monomer because the adhesive strength of the base is high, and is preferably 10% by weight or less. It is preferable because the surface of the electric agent is not easily covered excessively, and as a result, the overvoltage does not increase. Furthermore, 0.1 to 5 weight% is preferable among the said range, and 0.2 to 2 weight% is especially preferable.

  Moreover, you may use together ethylenically unsaturated compounds other than the above as a component which comprises the said polymer. The ethylenically unsaturated compound other than the above is not particularly limited as long as it is copolymerizable with the monomers, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate. , I-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (Meth) acrylates such as (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate; , 2-G Fluoroethyl (meth) acrylate, 2,2,3,3-pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, β- Fluorine-containing vinyl monomers such as (perfluorooctyl) ethyl (meth) acrylate; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether , Vinyl ethers such as amyl vinyl ether and hexyl vinyl ether; nitriles of unsaturated carboxylic acids such as (meth) acrylonitrile; ethylene, tetrafluoroethylene, vinylidene fluoride, N-vinylpyrrolidone Etc., and one or a mixture of two or more of these can be used.

  In addition to the above-mentioned monomers, ethylenically unsaturated monomers containing a crosslinkable reactive group can also be used. For example, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate, aminoethyl (meth) acrylate, N-monoalkylaminoalkyl (meth) acrylate, N, N-dialkylaminoalkyl (meth) Acrylate, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane , Γ- (meta) Examples include acryloxypropyltriisopropoxysilane, 2-aziridinylethyl (meth) acrylate, (meth) acryloyl isocyanate ethyl, acetoacetoxyethyl (meth) acrylate, and allyl (meth) acrylate.

  Moreover, if necessary, a polyfunctional monomer having two or more ethylenically unsaturated groups can be used. For example, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate , Neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, diallyl phthalate, divinylbenzene, allyl (meth) acrylate, etc. .

  The antioxidant used in the present invention is one or more compounds selected from the group consisting of phenolic antioxidants, amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Of these, the use of phenolic antioxidants and amine antioxidants is preferred in terms of adhesion to the base of the binder. Examples of phenolic antioxidants include 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis. (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), triethylene glycol-bis [3- (3-tert-butyl-5-methyl-hydroxy Phenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (normal octylthio) -6- ( 4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, pentaeryth Til-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-) Hydrocinnamide), 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanu 2,4-bis [(octylthio) methyl] -ortho-cresol, isooctyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene 3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate] methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionoxy] -1, 1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5 · 5] undecane and the like.

  Examples of amine antioxidants include 2,2-hydroxy-5-methylphenyl-benzotriazole, 4,4′-bis- (2,2-dimethylbenzyl) diphenylamine, bis (1,2,2,6,6). -Pentamethyl-4-piperidyldecanedionate, etc. Examples of the sulfur-based antioxidant include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3. 3, 3'-thiodipropionate, pentaerythrityl-tetrakis (3-laurylthiopropionate) ditridecyl-3,3'-thiodipropionate, 2-mercaptobenzimidazole, etc. Phosphorous antioxidants. As trisnonylphenyl phosphite, triphenyl phosphite, tris (2,4-di- tert-butylphenyl) phosphite, etc. The antioxidant is not limited to the above, and the content of the antioxidant is 0.01-5. It is essential that the amount is 0 part by weight, preferably 0.05 to 3 parts by weight, particularly preferably 0.1 to 1 part by weight. If the amount exceeds 50 parts by weight, the polymerization rate becomes very slow, which is not practical.This method of adding an antioxidant may be charged all at once before the start of polymerization, or may be present in a small amount at the start of the polymerization and remain in the middle of the polymerization. May be added.

  The polymer in the carbon binder of the present invention is usually dispersed in a dispersion medium in the form of particles. The presence of particles can be easily confirmed by transmission electron microscopy or optical microscopy.

  The method for obtaining the polymer is not particularly limited. A latex in which a polymer is dispersed in water can be produced, and this latex can be used as it is as a binder, or the obtained latex water is replaced with an organic dispersion medium to obtain an organic dispersion of the polymer, which is used as a binder. It can also be used. Examples of the method for replacing the dispersion medium include a method of adding an organic dispersion medium to the latex and then removing water in the dispersion medium by a distillation method, a fractional filtration method, a dispersion medium phase conversion method, or the like.

  The method for producing the latex is not particularly limited, and can be produced by an emulsion polymerization method, a suspension polymerization method, or the like. For example, the method described in "Experimental Chemistry Course" Vol. 28, (Publisher: Maruzen Co., Ltd., edited by The Chemical Society of Japan), that is, water, a dispersant, an emulsifier, and a crosslink in a sealed container with a stirrer and a heating device. Addition of additives such as agents, initiators, and monomers as raw materials so as to have a predetermined composition, and stirring or suspending or emulsifying the monomers etc. in water, and increasing the temperature while stirring, the diene system A latex in which the polymer is dispersed in water can be obtained. An emulsifier, a dispersing agent, a polymerization initiator and the like are generally used in these polymerization methods, and the amount used may be a generally used amount. In the polymerization, seed particles can be employed (seed polymerization).

  The emulsifier used in the production of the latex is not particularly limited, but an emulsifier having a polymerizable unsaturated group in the molecule generally called “reactive emulsifier” can also be used. As reactive emulsifiers that can be used in the present invention, for example, “Latemul S-180” (manufactured by Kao Corporation) having a sulfonic acid group and a salt thereof, “Eleminol JS-2, RS-30” (Sanyo Chemical Industries ( "AQUALON HS-10, HS-20" (Daiichi Kogyo Seiyaku Co., Ltd.), "Adekaria soap SE-10, SE-20" (Asahi Denka Kogyo Co., Ltd.) having sulfate groups and salts thereof "New Frontier A-229E" having a phosphate group (Daiichi Kogyo Seiyaku Co., Ltd.), etc .; "Aqualon RN-10, RN-20, RN-" having a nonionic hydrophilic group 30, RN-50 "(Daiichi Kogyo Seiyaku Co., Ltd.) and the like, and one or a mixture of two or more thereof can be used.

As the polymerization initiator used in the monomer polymerization, radical polymerization initiators are used. For example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, cumene hydroperoxide, tert-butyl There are organic peroxides such as hydroperoxide, hydrogen peroxide, etc., and radical polymerization is carried out using only these peroxides, or the above-mentioned peroxides and metal salts of ascorbic acid, formaldehyde sulfoxylate, thio Polymerization can also be achieved by a redox polymerization initiator system used in combination with a reducing agent such as sodium sulfate, sodium bisulfite, ferric chloride, etc., and 4,4′-azobis (4-cyanovaleric acid), 2,2 It is also possible to use an azo initiator such as' -azobis (2-amidinopropane) dihydrochloride. One or a mixture of two or more can be used.

  Among the polymerization initiators used in the polymerization of the above monomers, examples of the organic peroxides include diacyl peroxides such as benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, and tert-butylcumyl peroxide. , Dialkyl peroxides such as dicumyl peroxide, peroxyesters such as tert-butyl peroxylaurate, tert-butyl peroxybenzoate, cumene hydroperoxide, paramentane hydroperoxide, tert-butyl hydroperoxide The hydroperoxides etc. are mentioned, These 1 type, or 2 or more types of mixtures can be used.

  Among the polymerization initiators used in the polymerization, examples of the reducing organic compound include ascorbic acid and its salt, erythorbic acid and its salt, tartaric acid and its salt, citric acid and its salt, and formaldehyde sulfoxylate. A metal salt etc. are mentioned, These 1 type, or 2 or more types of mixtures can be used in combination with the said organic peroxides.

  In the present invention, when it is necessary to adjust the molecular weight of the polymer of the polymer, a compound having a chain transfer ability as a molecular weight modifier, for example, lauryl mercaptan, octyl mercaptan, dodecyl mercaptan, 2-mercaptoethanol, thioglycolic acid Mercaptans such as octyl, 3-mercaptopropionic acid, thioglycerin, or α-methylstyrene dimer may be added.

Further, latex obtained by these methods can be used for alkali metal (Li, Na, K, Rb, Cs) hydroxide, ammonia, inorganic ammonium compounds (NH ₄ Cl, etc.), organic amine compounds (ethanolamine, diethylamine, etc.), etc. Can be adjusted to a pH of 5 to 13, preferably 6 to 12, by adding a basic aqueous solution in which is dissolved. Among these, pH adjustment using ammonia and alkali metal hydroxide is preferable because it improves the binding property between the current collector and carbon.

  The solid content concentration of the carbon binder of the present invention is not particularly limited, but is usually 10 to 65% by weight, preferably 20 to 65% by weight.

  The carbon binder of the present invention is prepared by mixing as an aqueous dispersion in which an aqueous dispersant, conductive carbon, and water as necessary are added in advance, and further mixing by a dispersing device having a high shearing force. A binder formulation can be obtained. Examples of the dispersing device having a high shearing force include a bead mill, a high-pressure homogenizer, and an ultrasonic homogenizer. By using a device having a high shearing force, the conductive carbon and latex can be mixed at a submicron level. Further, from the viewpoint of dispersion efficiency and production efficiency, 50% or more of the total aqueous dispersant amount and 50% by weight or more of the total conductive carbon amount are mixed in advance and finely dispersed in the above-described apparatus having high shearing force, and then the remaining aqueous solution. It is preferred to mix the dispersant with the remaining conductive carbon and latex. The degree of dispersion can be examined using a crush gauge, and is preferably 10 μm or less, more preferably 3 μm or less, and particularly preferably 1 μm or less.

  The carbon binder composition can be used as various binders mixed with various additives and applied to a current collector. The amount used as a binder for the substrate is not particularly limited, but is usually 0.1 to 30 parts by weight, preferably 0.5 to 10 parts by weight as a solid content of the composition with respect to 100 parts by weight of carbon. . If the amount is less than 0.1 parts by weight, good adhesive strength cannot be obtained. If the amount exceeds 30 parts by weight, the overvoltage is remarkably increased, which adversely affects battery characteristics.

  Furthermore, in the carbon binder of the present invention, a water-soluble thickener may be used as an additive in an amount of 2 to 60 parts by weight based on 100 parts by weight of the polymer, for example, carboxy-modified styrene butadiene copolymer latex solids. Examples of the water-soluble thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein.

In the present invention, the carbon is not particularly limited as long as it functions as a heat conductive material. For example, it is preferable to use expanded graphite powder. Although there is no restriction | limiting in particular about expanded graphite powder, If importance is attached to cost, it is preferable to use natural graphite and artificial graphite as raw material graphite. The average particle size of carbon used in the present invention is 0.1 to 200 μm, preferably 3 to 100 μm, more preferably 5 to 50 μm, due to problems such as a decrease in slurry stability and an increase in interparticle resistance in the coating film. It is preferable that it is in the range.

  The carbon binder of this invention is apply | coated on a base material as a coating liquid, is heated and dried on the said conditions, and is shape | molded. At this time, if necessary, it may be molded together with the current collector material. Alternatively, a current collector such as an aluminum foil, a copper foil, or a nickel foil may be used as a base material. Moreover, as a coating method used here, various coater heads such as a reverse roll method, a comma bar method, a gravure method, and an air knife method can be used. Although there is no restriction | limiting in particular in a drying method, A standing drying, a ventilation dryer, a warm air dryer, an infrared heater, a far-infrared heater, etc. can be used.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail using an Example, this invention is not limited to the range of these Examples. In Examples and Comparative Examples shown below, “part” or “%” is based on weight unless otherwise specified. Various evaluations in the examples and comparative examples were performed as follows.

(Measurement and results of dynamic viscoelastic properties of films using latex of the present invention and comparative examples)
The storage elastic modulus (E ′), loss elastic modulus (E ″) and tan δ (= E ″ / E ′) of each film obtained in each of the above Examples and Comparative Examples were measured for solid viscoelasticity manufactured by RHEOMETRIICS. It measured using apparatus "RSA-2". Each value of the measurement results is listed in Table 1. In addition, the said film casts latex on a glass plate, and after drying for 5 hours at 40-60 degreeC, a film is peeled from a glass plate, 120 degreeC x 20 minutes heat-drying process, the dry film thickness 0 .3 mm was used.

  Method for evaluating adhesion to metal foil: A binder was applied to a copper foil and a nickel foil of 50 μm and dried at 120 ° C. for 10 minutes to obtain a coating film having a thickness of 15 μm. The obtained coating film was left in a test machine at 60 ° C. for 1 hour using a heat shock tester, and then left at −20 ° C. for another hour. This operation was repeated 100 times with this as one cycle. The adhesion was evaluated based on the number of cells remaining after the cell-like scratch was applied to the coating film in accordance with JIS K5400, and a cellophane adhesive tape was affixed and peeled off. For example, if the adhesion is good, all of the grids remain on the coating film, which is indicated as 100/100.

Example 1
100 parts of ion-exchanged water in an autoclave with a stirrer, 0.5 part of sodium alkyldiphenyl ether disulfonate (New Coal 271A, Nippon Emulsifier product) as the active ingredient amount, 0.2 part of Clewat TAA (Teikoku Chemical Industries product) as a chelating agent, 4 , 4′-bis- (2,2-dimethylbenzyl) diphenylamine (antioxidant) was charged in 0.4 parts, and the temperature was raised to 80 ° C. with stirring, after purging with nitrogen. On the other hand, 20 parts of ion-exchanged water, 0.5 part of sodium alkylbenzene sulfonate (Neopelex G-15, Kao product) and 0.4 part of tert-dodecyl mercaptan are charged in a separate container, and the unit amount is as shown in Table 1. 100 parts of the body was added and stirred to prepare a monomer emulsion and purge with nitrogen. On the other hand, 0.15 part of ammonium persulfate was added to 10 parts of ion-exchanged water and dissolved, and then charged into an initiator container and replaced with nitrogen. Separately from this, 0.1 part of ammonium persulfate was dissolved in 2 parts of ion-exchanged water, and was added when the internal temperature of the autoclave reached 80 ° C. from a bomb that was pressurized and replaced with nitrogen, and the polymerization reaction was started. Next, the monomer emulsion and the initiator solution were added to the autoclave in about 3 hours, and then held at 80 ° C. for 1 hour to carry out emulsion polymerization to a polymerization rate of 99.7%. Thereafter, removal of unreacted monomer by steam distillation, concentration, and pH adjustment by addition of 25 wt% ammonia water were performed to obtain a carbon binder (A-1) having a solid content of 48.5%. The polymerization proceeded stably, the generation of aggregates was not observed at all, and the obtained binder A-1 was extremely stable. The temperature (° C.) at which tan δ of the film was maximum was 58 ° C., and the maximum value of tan δ (max value of tan δ) was 1.4.

Example 2
125 parts of ion-exchanged water in an autoclave with a stirrer, 0.5 part of sodium alkyldiphenyl ether disulfonate (New Coal 271A, Nippon Emulsifier product) as the active ingredient amount, 0.2 part of Clewat TAA (Teikoku Industrial Co., Ltd.) as chelating agent, 4 , 4'-bis- (2,2-dimethylbenzyl) diphenylamine (antioxidant) 0.4 part, tert-dodecyl mercaptan 0.4 part, 100 parts of the monomer shown in Table 1 (other than butadiene) Was added, and 0.15 part of ammonium persulfate was added, and the emulsion polymerization was carried out at a temperature range of 65 ° C. to 80 ° C. for 7 hours with a polymerization rate of 99.6% while stirring. It was. Thereafter, removal of unreacted monomer by steam distillation, concentration, and pH adjustment by addition of 25 wt% ammonia water were performed to obtain a carbon binder (A-2) having a solid content of 48.3%. Polymerization proceeded stably, the generation of aggregates was not observed at all, and the obtained binder A-2 was extremely stable. The temperature (° C.) at which tan δ of the film was maximum was 14 ° C., and the maximum value of tan δ (max value of tan δ) was 0.6.

Example 3
A carbon binder (A-3) having a solid content of 49.8% was obtained in the same manner as in Example 2 except that the amount of the monomer used was changed to Example 3 in Table-1. Polymerization proceeded stably, the generation of aggregates was not observed at all, and the obtained binder A-3 was extremely stable. The temperature (° C.) at which the tan δ of the film was maximum was −6 ° C., and the maximum value of tan δ (max value of tan δ) was 0.4.

Comparative Example 1
100 parts of ion-exchanged water in an autoclave with a stirrer, 0.5 part of sodium alkyldiphenyl ether disulfonate (New Coal 271A, Nippon Emulsifier product) as the active ingredient amount, 0.2 part of Clewat TAA (Teikoku Chemical Industries product) as a chelating agent, 4 , 4′-bis- (2,2-dimethylbenzyl) diphenylamine (antioxidant) was charged in 0.4 parts, and the temperature was raised to 80 ° C. with stirring, after purging with nitrogen. On the other hand, 20 parts of ion-exchanged water, 0.5 part of sodium alkylbenzene sulfonate (Neopelex G-15, Kao product) and 0.4 part of tert-dodecyl mercaptan were charged in a separate container, and the amount of the composition shown in Table 2 100 parts of the body was added and stirred to prepare a monomer emulsion and purge with nitrogen. On the other hand, 0.15 part of ammonium persulfate was added to 10 parts of ion-exchanged water and dissolved, and then charged into an initiator container and replaced with nitrogen. Separately from this, 0.1 part of ammonium persulfate was dissolved in 2 parts of ion-exchanged water, and was added when the internal temperature of the autoclave reached 80 ° C. from a bomb that was pressurized and replaced with nitrogen, and the polymerization reaction was started. Next, the monomer emulsion and the initiator solution were added to the autoclave in about 3 hours, and then held at 80 ° C. for 1 hour to carry out emulsion polymerization to a polymerization rate of 99.7%. Thereafter, removal of unreacted monomer by steam distillation, concentration and pH adjustment by addition of 25 wt% ammonia water were performed to obtain a carbon binder (B-1) having a solid content of 48.5%. Polymerization proceeded stably, the generation of aggregates was not observed at all, and the obtained binder B-1 was extremely stable. The temperature (° C.) at which the tan δ of the film was maximum was 62 ° C., and the maximum value of tan δ (max value of tan δ) was 1.6.

Comparative Example 2
125 parts of ion-exchanged water in an autoclave with a stirrer, 0.5 part of sodium alkyldiphenyl ether disulfonate (New Coal 271A, Nippon Emulsifier product) as the active ingredient amount, 0.2 part of Clewat TAA (Teikoku Industrial Co., Ltd.) as chelating agent, 4 , 4'-bis- (2,2-dimethylbenzyl) diphenylamine (antioxidant) 0.4 part, tert-dodecyl mercaptan 0.4 part, and 100 parts of a monomer having a composition shown in Table 2 (other than butadiene) Was added, and 0.15 part of ammonium persulfate was added, and the emulsion polymerization was carried out at a temperature range of 65 ° C. to 80 ° C. for 7 hours with a polymerization rate of 99.6% while stirring. It was. Thereafter, removal of unreacted monomer by steam distillation, concentration and pH adjustment by addition of 25 wt% ammonia water were performed to obtain a carbon binder (B-2) having a solid content of 48.3%. Polymerization proceeded stably, no generation of aggregates was observed, and the obtained binder B-2 was extremely stable. The temperature (° C.) at which tan δ of the film was maximum was −15 ° C., and the maximum value of tan δ (max value of tan δ) was 0.2.

Comparative Example 3 (no antioxidant added)
125 parts of ion-exchanged water in an autoclave equipped with a stirrer, 0.5 parts of sodium alkyldiphenyl ether disulfonate (New Coal 271A, Nippon Emulsifier product) as the active ingredient amount, 0.2 part of Clewat TAA (Teikoku Chemical Industries product) as a chelating agent, tert -Charge 0.4 parts of dodecyl mercaptan and 100 parts of the monomer having the composition shown in Table 2 (Nitrogen substitution was performed after adding raw materials other than butadiene), and 0.15 parts of ammonium persulfate was added and stirred. However, emulsion polymerization was carried out in a temperature range of 65 ° C. to 80 ° C. for 7 hours until the polymerization rate reached 99.6%. Thereafter, removal of unreacted monomer by steam distillation, concentration, and pH adjustment by addition of 25 wt% aqueous ammonia were performed to obtain a carbon binder (B-3) having a solid content of 48.5%. Polymerization proceeded stably, no generation of aggregates was observed, and the obtained binder B-3 was extremely stable. The temperature (° C.) at which tan δ of the film was maximum was 12 ° C., and the maximum value of tan δ (max value of tan δ) was 0.5.

Claims (9)

A carbon binder comprising a polymer containing a structural unit derived from a conjugated diene compound, a structural unit derived from an aromatic vinyl compound, and a structural unit derived from an ethylenically unsaturated carboxylic acid compound, and an antioxidant, The temperature at which the polymer has a maximum loss angle tangent (tan δ) in dynamic viscoelasticity measurement is −10 to 60 ° C., and the maximum value of the loss angle tangent (tan δ) is 0.3 to 1.5. A carbon binder characterized by The carbon binder according to claim 1, wherein the antioxidant is at least one compound selected from the group consisting of phenolic antioxidants, amine antioxidants, sulfur antioxidants, and phosphorus antioxidants. . The carbon binder according to claim 2, wherein the antioxidant is an amine compound and / or a phenol compound. In the structural unit derived from the ethylenically unsaturated carboxylic acid compound in the polymer, the content of the structural unit derived from the ethylenically unsaturated dicarboxylic acid compound is from 0.05 to 10 with respect to all the polymers in the binder. The carbon binder according to claim 1, which is 0% by weight. The conjugated diene compound is at least one selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 2,4-hexadiene. The carbon binder according to claim 1, which is a compound of A method for producing a carbon binder for polymerizing a polymerizable monomer mixture containing a conjugated diene compound, an aromatic vinyl compound and an ethylenically unsaturated dicarboxylic acid compound, and polymerizing the polymerizable monomer mixture A method for producing a carbon binder comprising polymerizing a polymerizable monomer mixture in the presence of an amine-based and / or phenol-based compound antioxidant. The method for producing a carbon binder according to claim 6, wherein the content of the conjugated diene compound is 10 to 50% by weight of the total polymerizable monomer. The method for producing a carbon binder according to claim 6, wherein the content of the ethylenically unsaturated dicarboxylic acid compound is 0.05 to 10% by weight of the total polymerizable monomer. The method for producing a carbon binder according to claim 6, 7 or 8, wherein a monomer emulsion obtained by mixing a polymerizable monomer mixture and water in advance is supplied into a reaction vessel and polymerized.