JP6142415B2 - Carbon black dispersion and use thereof - Google Patents

Description

 The present invention relates to a carbon black dispersion excellent in dispersibility and storage stability. The present invention also relates to a battery electrode mixture layer and a lithium ion secondary battery using the dispersion.

  Carbon black is used in a wide range of fields such as printing inks, ink-jet inks, inks for writing instruments, paints, and plastic forming materials as coloring pigments, light-shielding materials, conductive materials, heat-conductive materials, polymer reinforcing materials, and the like. In order to satisfy the required quality for these applications and to make the production process efficient and shorten, it is important to disperse carbon black in a solvent so that it can be easily applied.

  In recent years, especially in consideration of the environment and production costs, it has been required to produce a carbon black dispersion with a higher concentration than before, to reduce the amount of solvent used and to reduce the energy used during drying. Yes.

  Since these requirements have a great influence on the cost of the solvent and the energy used during drying, the more expensive the solvent used or the higher the boiling point of the solvent used, the more important. N-methyl-2-pyrrolidone used in non-aqueous secondary batteries and the like is more expensive than common solvents and has a very high boiling point of 200 ° C. or higher. There is a strong demand for reducing the above.

  In order to disperse a large amount of carbon black in a solvent, it is particularly effective to adsorb a dispersant on the surface of the carbon black so that the dispersion is in a stable state. Carbon using various dispersants Black dispersions have been proposed.

  Examples of the dispersant for dispersing carbon black using N-methyl-2-pyrrolidone as a solvent include low molecular weight surfactants as disclosed in Patent Document 1 and low molecules such as dye derivatives as disclosed in Patent Document 2. A compound (hereinafter simply referred to as a pigment derivative) or a polymer compound as described in Patent Documents 3 and 4 (hereinafter simply referred to as a resin-type dispersant) is known. These dispersants are required to be added in as small an amount as possible except when the main component constituting the paint functions as a dispersant as it is.

  When these dispersants are used, it is necessary to use them according to the characteristics of the respective dispersants. For example, the possible composition range, viscosity, surface tension, etc. of the obtained dispersion greatly depend on the material used for the dispersant. Because of the differences, it is very important to select a suitable dispersant. Hereinafter, the characteristics of the case where a low molecular weight surfactant, a pigment derivative, and a resin type dispersant are used as the dispersant will be described.

  First, an example in which a low molecular weight surfactant is used as a dispersant is described in Patent Document 1, but it is considered that functional groups are weakly ionized in an organic solvent, and a large amount is required to obtain good dispersion stability. Is not preferable from the viewpoint of the amount of the dispersant added.

  The dye derivative described in Patent Document 2 is considered to function as a dispersant in order to stabilize the particle surface by being chemically adsorbed on the carbon black surface and to form a better particle surface charge. The pigment derivative is suitable as a dispersant in an organic solvent from the viewpoint of a dispersant addition amount because a good dispersion can be obtained even with a small addition amount.

  For example, the resin-type dispersant described in Patent Documents 3 and 4 can obtain a good dispersion even with a relatively small addition amount, as in the case of the pigment derivative. From the viewpoint of the amount of dispersant addition, the dispersant in an organic solvent It is suitable as. In these resin-type dispersants, the chemical or physical adsorption to the carbon black surface and the polymer chain dissolution structure after adsorption are considered to be important. This is thought to be because even if the polymer compound is adsorbed to the surface of the particle well, if the polymer chain does not stick out well to the solvent side, the steric repulsion cannot be effectively performed between the particles. Yes. In addition, since it is a high molecular compound, it can be expected that it is chemically stable in harsh environments or that it is easier to control and manage reactivity than low molecular weight dye derivatives. I can do it.

  As a resin-type dispersant for dispersing carbon black using N-methyl-2-pyrrolidone as a solvent, for example, polyvinyl pyrrolidone and polyvinyl butyral described in Patent Document 3 or 4 are known. These resins are dissolved in N-methyl-2-pyrrolidone, adsorbed on the surface of carbon black particles, and the polymer chains adsorbed on different particles rebound sterically, thereby exhibiting dispersion performance. It is considered to be. However, when a high-concentration carbon black dispersion is prepared using these resin-type dispersants, there is a problem that the viscosity of the resulting dispersion becomes very high. When the viscosity of the carbon black dispersion is very high, the fluidity of the dispersion is poor, so the processability, homogeneity, and coatability of the liquid after adding other binder components and other powder components It becomes difficult to secure a uniform coating layer.

  Because of this problem, there is a demand for the development of a dispersant that has a higher dispersion performance than polyvinyl pyrrolidone or polyvinyl butyral and can obtain a carbon black dispersion with a higher concentration.

  For example, Patent Document 5 suggests the possibility of using various nonionic surfactants. Polyvinyl acetal resin or polyvinyl alcohol resin is one of the nonionic surfactants, and N is the solvent. -Methyl-2-pyrrolidone is described as one of known additives, nitrogen compounds such as amine compounds and ammonium compounds, respectively. However, until now, when a specific solvent called N-methyl-2-pyrrolidone solvent is used, a particularly good dispersion can be obtained by using a resin containing a specific skeleton and a specific additive as a dispersant. It is still unclear whether there is a possibility that

 In the battery field, carbon black is widely used as a conductive additive, but when forming a battery electrode mixture layer, in order to shorten the production process in an efficient manner, carbon black is used in a solvent, It is important how to disperse uniformly at a high concentration so that coating can be performed easily.

  For example, Patent Documents 6 and 7 describe a coating liquid containing carbon black, unmodified or modified polyvinyl alcohol resin or polyvinyl acetal resin, and N-methyl-2-pyrrolidone. Describes that an electrode plate of a lithium ion secondary battery is manufactured by adding a positive electrode active material or a negative electrode active material to the coating solution. However, these polyvinyl alcohols and polyvinyl acetal resins in Patent Documents 6 and 7 are used in large quantities as binders (resin binders), and the technical idea of using polyvinyl alcohols and polyvinyl acetal resins as dispersants. There is no.

  In general, when carbon black is dispersed using a dispersant, the dispersibility of the carbon black is deteriorated when the amount of the dispersant is extremely reduced, and on the contrary, the dispersibility is improved when the amount of the dispersant is extremely increased. However, when used in battery applications, it is expected to adversely affect battery characteristics such as an increase in resistance and deterioration in conductivity.

  However, in order to obtain a highly concentrated and uniformly dispersed carbon black dispersion, not only the physical and chemical properties of the carbon black used, the solvent type, and the dispersant, but also their quantitative relationships have been studied in detail. In the case where a specific solvent called N-methyl-2-pyrrolidone and a vinyl alcohol skeleton-containing resin are used as a dispersant and an amine compound as an additive, carbon black and a vinyl alcohol skeleton-containing resin are not reported. And the physical and chemical properties of amine compounds, and how their quantitative relationship affects the carbon black dispersion, battery electrode composite layer, and battery characteristics is not studied at all. Met.

  Moreover, generally, when manufacturing the electrode for lithium ion secondary batteries, the solvent used for preparation of an electrode compound liquid is determined by the polymer material used for the binder in a battery. At present, in the production of electrodes for lithium ion secondary batteries, polyvinylidene fluoride is generally used as a particularly suitable binder for forming an electrode, and N-methyl-2-pyrrolidone is generally used as a solvent for dissolving polyvinylidene fluoride. It is used. Since N-methyl-2-pyrrolidone has a very high boiling point of 202 ° C., it is necessary to spend a large amount of energy and time for drying the electrode mixture liquid. In order to solve this problem, attempts have been made to obtain an electrode mixture solution having a concentration as high as possible using N-methyl-2-pyrrolidone as a solvent. Another performance required for the carbon black dispersion liquid for the electrode mixture liquid of the lithium ion secondary battery is that it is desirable that the amount of the dispersant added is as small as possible. This is because the ratio of the other electrode constituent components in the electrode film decreases by the amount of the dispersant added.

JP-A-8-190912 JP 2011-162698 A Japanese Patent Laid-Open No. 2003-157846 JP 2011-184664 A JP 2011-70908 A International Publication No. 2009/147789 International Publication No. 2011/024799

  In view of the above situation, in the present invention, the resulting carbon black dispersion is significantly reduced in viscosity compared to conventionally known resin-type dispersants, that is, the carbon black concentration that can be achieved is significantly higher, and carbon It is an object to provide a carbon black dispersion using N-methyl-2-pyrrolidone as a solvent, which is excellent in black dispersibility and storage stability of the dispersion. Moreover, it is a subject to provide the battery electrode compound-material layer with a uniform and favorable coating-film physical property and low surface resistance.

  The inventors of the present invention focused on the physical and chemical properties of carbon black, solvent species, and dispersant, and as a result of detailed examination of their quantitative relationship, the amount of carbon black and vinyl alcohol skeleton-containing resin used. Found that there is a critical range that greatly contributes to dispersibility, and when these are within a certain range, high concentration, low viscosity, and long-term storage stability The present inventors have found that a good carbon black dispersion can be produced and have completed the present invention.

  That is, an embodiment of the present invention is a carbon black dispersion liquid containing carbon black, a vinyl alcohol skeleton-containing resin, N-methyl-2-pyrrolidone, and an amine compound, and comprising 100 parts by weight of carbon black Wherein the carbon black contains 1 to 15 parts by weight of a vinyl alcohol skeleton-containing resin and 0.1 to 2.6 parts by weight of an amine compound. Concerning the dispersion.

  Moreover, the embodiment of the present invention contains 1 part by weight or more and 8 parts by weight or less of a vinyl alcohol skeleton-containing resin with respect to 100 parts by weight of carbon black, and 0.2 part by weight or more of an amine compound. The carbon black dispersion is characterized by containing 5 parts by weight or less.

  In another embodiment of the present invention, the amine compound includes an aliphatic primary amine, an aliphatic secondary amine, an aliphatic tertiary amine, an amino acid, an alkanolamine, a polyoxyalkylene alkylamine, a polyamine, and an alicyclic compound. The present invention relates to the above carbon black dispersion, which is one or more amine compounds selected from the group consisting of nitrogen heterocyclic compounds.

  In addition, an embodiment of the present invention is such that the amine compound includes an aliphatic primary amine, an aliphatic secondary amine, an aliphatic tertiary amine, an alkanolamine, and a polyoxyalkylene alkylamine having only one amino group. It is related with the said carbon black dispersion liquid which is 1 or more types of amine compounds selected from the group which consists of. However, the amino group is a primary, secondary or tertiary functional group.

  An embodiment of the present invention is characterized in that the vinyl alcohol skeleton-containing resin is a vinyl alcohol skeleton-containing resin selected from the group consisting of polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, and polyvinyl formal resins. It relates to the carbon black dispersion.

  In addition, an embodiment of the present invention relates to a carbon black dispersion for a battery, wherein the carbon black dispersion further contains a positive electrode active material or a negative electrode active material.

  An embodiment of the present invention also relates to a battery electrode mixture layer formed by applying the carbon black dispersion or the battery carbon black dispersion.

  An embodiment of the present invention is a lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium. And at least one of a positive electrode and a negative electrode is related with the lithium ion secondary battery which comprises the said battery electrode compound-material layer.

  According to the present invention, it is possible to obtain a carbon black dispersion liquid having a significantly lower viscosity than when a conventionally known resin-type dispersant is used, and to increase the carbon black concentration. As a result, a carbon black dispersion with a higher concentration than before can be provided, and the amount of N-methyl-2-pyrrolidone solvent used can be greatly reduced, and the drying process of the coated film can be greatly shortened. You will be able to In addition, it is possible to provide a carbon black dispersion liquid using N-methyl-2-pyrrolidone as a solvent, which is excellent in carbon black dispersibility and dispersion storage stability.

  In addition, when an electrode mixture solution for a secondary battery is prepared using the dispersion, it is easy to add and knead the active material powder because of its low viscosity, and each electrode component has a high concentration. Even when a mixture solution is used, a uniform and good coating film can be obtained, and therefore a battery electrode mixture layer having a low surface resistance can be obtained.

The carbon black dispersion in the present invention contains carbon black, a vinyl alcohol skeleton-containing resin, an amine compound, and N-methyl-2-pyrrolidone. Details will be described below. In this specification, “carbon black dispersion”, “carbon black dispersion for battery” may be abbreviated as “dispersion”, and “N-methyl-2-pyrrolidone” may be abbreviated as “NMP”.
<Carbon black>
As the carbon black used in the present invention, various types such as commercially available furnace black, channel black, thermal black, acetylene black, ketjen black and the like can be used. Ordinarily oxidized carbon black, hollow carbon black, graphitized carbon black, carbon nanotube, carbon nanofiber, and the like can also be used.

  The oxidation treatment of carbon black is performed by treating the carbon black at a high temperature in the air or by treating it with nitric acid, nitrogen dioxide, ozone, etc., for example, phenol group, quinone group, carboxyl group, carbonyl group. This is a treatment for directly introducing (covalently bonding) such an oxygen-containing polar functional group to the surface of carbon black, and is generally performed to improve the dispersibility of carbon black.

  The carbon black used in the present invention is not particularly limited, but industrially produced carbon black such as acetylene black and furnace black is preferably used.

  Further, the average primary particle diameter of carbon black used in the production of the dispersion is preferably 0.01 to 1 μm, particularly in the range of the average primary particle diameter of carbon black used in general dispersions and paints. 0.01 to 0.2 μm is preferable, and 0.01 to 0.1 μm is more preferable. The average primary particle size referred to here indicates an arithmetic average particle size measured with an electron microscope, and this physical property value is generally used to represent the physical characteristics of carbon black.

As other physical property values representing the physical characteristics of carbon black, BET specific surface area and pH are known. The BET specific surface area refers to a specific surface area (hereinafter simply referred to as a specific surface area) measured by the BET method by nitrogen adsorption, and this specific surface area corresponds to the surface area of carbon black. The amount you need also increases. The pH changes under the influence of functional groups on the carbon black surface and impurities contained therein.
<Vinyl alcohol skeleton-containing resin>
In the present invention, a vinyl alcohol skeleton-containing resin is used as a dispersant. That is, the vinyl alcohol skeleton-containing resin is used not as a binder but as a dispersant. Although there is no restriction | limiting in particular about the manufacturing method of vinyl alcohol frame | skeleton containing resin used by this invention, Hereinafter, using polyvinyl acetate as a raw material, the polyvinyl alcohol resin obtained by saponifying this, and using a polyvinyl alcohol resin as a raw material A polyvinyl formal resin or a polyvinyl acetal resin obtained by a formalization reaction or an acetalization reaction will be described.

  In general, the polyvinyl alcohol resin is obtained by using polyvinyl acetate obtained by polymerizing vinyl acetate as a raw material, saponifying the polyvinyl acetate, and substituting the acetyl group with a hydroxyl group. Because of this synthesis process, the polyvinyl alcohol resin has an acetyl group and a hydroxyl group, and the ratio is expressed as the degree of saponification. The saponification degree in the present invention is the same as the definition of saponification degree known in the industry, and the total moles of structural units (typically vinyl ester units) and vinyl alcohol units that can be converted into vinyl alcohol units by saponification. The ratio (mol%) that the number of moles of the vinyl alcohol unit occupies with respect to the number. In particular, when polyvinyl acetate is used as a raw material, the number of hydroxyl groups derived from the vinyl alcohol skeleton contained in the polyvinyl alcohol resin is divided by the sum of the number of acetyl groups derived from the vinyl acetate skeleton and the number of hydroxyl groups derived from the vinyl alcohol skeleton. Means the value.

  In general, a polyvinyl formal resin or a polyvinyl acetal resin is obtained by reacting a polyvinyl alcohol resin with an aldehyde to form or acetalize it. For this synthesis process, the polyvinyl formal resin has an acetyl group, a hydroxyl group, and a formal group, and the polyvinyl acetal resin has an acetyl group, a hydroxyl group, and an acetal group. These properties as a resin are mainly characterized by the ratio of hydroxyl groups to formal groups or acetal groups.

  The vinyl alcohol skeleton-containing resin used in the present invention is synthesized by a conventionally known synthesis method, and various commercially available products and synthetic products can be used alone or in combination of two or more. It is not limited to.

  The functional group contained in the vinyl alcohol skeleton-containing resin includes, for example, an acetoacetyl group, a sulfonic acid group, a carboxyl group, a carbonyl group, and an amino group as a functional group other than a hydroxyl group, an acetyl group, an acetal group, or a formal group. Those introduced, those having a structure such as ether or ester, those modified with various salts, and those modified with anions or cations are also included in the scope of the vinyl alcohol skeleton-containing resin used in the present invention. These can be used alone or in combination of two or more.

  The effect of the vinyl alcohol skeleton-containing resin as a dispersant on carbon black is affected by the solubility and swelling property with respect to NMP, the average degree of polymerization, and the vinyl alcohol skeleton content ratio.

 The vinyl alcohol skeleton-containing resin preferably has a vinyl alcohol skeleton content of 10 to 90 mol%, more preferably 20 to 85 mol%.

  The polyvinyl alcohol resin as the dispersant preferably has an average degree of polymerization of 50 to 3000, particularly preferably 100 to 2000, and more preferably 100 to 1500.

  The polyvinyl acetal resin, polyvinyl butyral resin, and polyvinyl formal resin as the dispersant are preferably those having an average calculated molecular weight of 5,000 to 200,000, particularly preferably 10,000 to 150,000, and more preferably 15,000 to 150,000.

  The vinyl alcohol skeleton-containing resin as the dispersant is not particularly limited, but may be used in combination with a conventionally known dispersant described in Patent Documents 1 to 4, a conventionally known additive, or the like. I can do it.

  Examples of commercially available vinyl alcohol skeleton-containing resins include Kuraray Poval (polyvinyl alcohol resin manufactured by Kuraray), Gohsenol (polyvinyl alcohol resin manufactured by Nippon Synthetic Chemical Industry), Denka Poval (manufactured by Denki Kagaku Kogyo Co., Ltd.), and J-Poval. (Nippon Vinegar POVAL Co., Ltd.), ESREC (Polyvinyl acetal resin manufactured by Sekisui Chemical Co., Ltd.), Mobital (Kuraray Polyvinyl Butyral resin), Vinylec (JNC Polyvinyl formal resin), etc. Can be obtained from the market.

More specifically, for example, Kuraray Poval PVA-403, PVA-505, L-8, L-9, L-9-78, L-10, C-506, KL-506, and ESREC BL-1 , ESREC BL-10, ESREC BX-L, MOVITAL B16H, MOBITAL 30T, MOBITAL 30HH, MOVITAL 60T, VINYREC K, VINYREC L, VINYREC H, VINYREC E, etc., but are not limited thereto. Absent.
<Amine compound>
In the present invention, an amine compound is used. As the amine compounds, primary amines (primary amines), secondary amines (secondary amines), and tertiary amines (tertiary amines) are mainly used, and ammonia and quaternary ammonium compounds are not included. As the amine compound, in addition to monoamine, amine compounds such as diamine having a plurality of amino groups in the molecule, triamine, tetramine, and polyamine can be used. In addition to the above, amino acids, alicyclic nitrogen-containing heterocyclic compounds, and the like can also be used. The amino group in this specification is a primary, secondary or tertiary functional group.

 The amine compounds used in the present invention are aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines, amino acids, alkanolamines, polyoxyalkylenealkylamines, polyoxyalkyleneamines, polyethyleneimines, polyamines, alicyclic rings. One or more amine compounds selected from the group consisting of the formula nitrogen-containing heterocyclic compounds are preferable, and have only one amino group, an aliphatic primary amine, an aliphatic secondary amine, an aliphatic tertiary amine, and an alkanol. One or more amine compounds selected from the group consisting of amines and polyoxyalkylene alkylamines are more preferred.

  The amine compound used in the present invention can be used alone or in combination of two or more, regardless of whether it is a commercially available product or a synthetic product.

  Specifically, for example, aliphatic primary amines such as ethylamine, octylamine, laurylamine, myristylamine, stearylamine, oleylamine, secondary aliphatic amines such as diethylamine, dibutylamine, distearylamine, triethylamine, dimethyloctyl Aliphatic tertiary amines such as amine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylvalmitylamine, dimethylstearylamine, dimethylbehenylamine, dilaurylmonomethylamine, trioctylamine, alanine, methionine, proline, serine , Amino acids such as asparagine, glutamine, lysine, arginine, histidine, aspartic acid, glutamic acid, cysteine, dimethylaminoethanol, monoethanol Alkanolamines such as amine, diethanolamine, methyldiethanolamine, triethanolamine, polyoxyalkylenealkylamines such as polyoxyethylene laurylamine, polyoxyethylene octadecylamine, polyoxyalkyleneamine (polyetheramine), polyethyleneimine, polyvinylamine, etc. Alicyclic nitrogen-containing heterocyclic compounds such as polyamine, hexamethylenetetramine, morpholine, piperidine and the like, but are not limited thereto.

  The molecular weight of the amine compound is preferably 30 or more and 15000 or less, more preferably 45 or more and 10,000 or less, still more preferably 89 or more and 1200 or less, and particularly preferably 89 or more and 500 or less.

  The number of carbon atoms of the amine compound is preferably 2 or more and 1000 or less, more preferably 3 or more and 700 or less, still more preferably 4 or more and 60 or less, and particularly preferably 4 or more and 24 or less. .

  When the amine compound is an aliphatic amine, those having 2 to 40 carbon atoms are preferable, those having 8 to 36 are more preferable, and those having 8 to 24 are particularly preferable.

  The acid dissociation constant (pKa) of the amine compound is preferably 7 or more and 12 or less, more preferably 8 or more and 11 or less, and particularly preferably 9 or more and 10.5 or less. The acid dissociation constant is a value in an aqueous solution at 25 ° C.

  The number of amino groups possessed by the amine compound is preferably 1 or more, 4 or less, more preferably 1 or more and 2 or less, particularly 1 from the viewpoint of storage stability of the dispersion. preferable.

  The chemical structure of the amine compound includes an alicyclic nitrogen-containing heterocyclic compound, an amine compound in which the amino group is covalently bonded to the α-carbon of the carbonyl group or carboxyl group, and an amine system having two or more carbonyl groups or carboxyl groups An amine compound other than the compound is preferred.

  The amine compound is preferably dissolved in an amount of 1 part by weight or more with respect to 100 parts by weight of N-methyl-2-pyrrolidone at 0 ° C. or more and 40 ° C. or less under atmospheric pressure.

In the polyoxyalkylene alkylamine, the nitrogen atom in the amino group is preferably contained in an amount of 1 to 15% by weight, more preferably 3 to 6% by weight. .
<N-methyl-2-pyrrolidone>
N-methyl-2-pyrrolidone (NMP) is used for manufacturing electrodes of lithium ion secondary batteries. In the present invention, one or more other solvents may be used in combination as long as the performance as a dispersant for the vinyl alcohol skeleton-containing resin and the battery performance are not impaired. However, from the industrial applicability assumed by the present invention. , NMP is preferably used alone.
<Method for producing carbon black dispersion>
The dispersion of the present invention is obtained by dispersing carbon black in NMP using a vinyl alcohol skeleton-containing resin as a dispersant and an amine compound as an additive or dispersant. In this case, the vinyl alcohol skeleton-containing resin and carbon black are added simultaneously or sequentially and mixed to disperse the vinyl alcohol skeleton-containing resin while acting (adsorbing) on the carbon black. However, in order to more easily produce a carbon black dispersion, a vinyl alcohol skeleton-containing resin is dissolved, swollen, or dispersed in NMP, and then carbon black is added to the liquid and mixed. It is more preferable to cause the alcohol skeleton-containing resin to act (adsorb) on the carbon black. Further, as a powder other than carbon black, for example, when an electrode active material for a secondary battery is added and used as an electrode mixture liquid, a vinyl alcohol skeleton-containing resin, carbon black, and an electrode active material are contained in NMP. The charge distribution process may be performed simultaneously.

  The amine compound may be added before the vinyl alcohol skeleton-containing resin is allowed to act on the carbon black, or may be added after the dispersion treatment is completed. In either case, suitable effects are obtained. It is done.

  As the dispersion device, a disperser usually used for pigment dispersion or the like can be used. For example, mixers such as dispersers, homomixers, planetary mixers, homogenizers (such as “Clairemix” manufactured by M Technique, “Fillmix” manufactured by PRIMIX, “Abramix” manufactured by Silverson, etc.), paint conditioners ( Red Devil), colloid mill ("PUC colloid mill" manufactured by PUC, "colloid mill MK" manufactured by IKA), cone mill ("Cone mill MKO" manufactured by IKA), ball mill, sand mill (Shinmaru Enterprises) "Dynomill", etc.), Attritor, Pearl Mill ("DCP Mill" manufactured by Eirich), Coball Mill and other media type dispersers, Wet Jet Mill ("Genus PY" manufactured by Genus, "Starburst" manufactured by Sugino Machine "Nanomizer" manufactured by Nanomizer ), M Technique Co., Ltd. "Claire SS-5", Nara Machinery Co., Ltd. "MICROS" media-less dispersing machine such as, but other roll mill, and the like, but is not limited to these.

  In the present invention, the amount of the vinyl alcohol skeleton-containing resin added as a dispersant to the carbon black is preferably 1 part by weight or more and 15 parts by weight or less, preferably 1 part by weight or more and 10 parts by weight with respect to 100 parts by weight of the carbon black. The following is more preferable, 1 to 8 parts by weight is further preferable, 1 to 5 parts by weight is particularly preferable.

  In the present invention, the amount of the amine compound added to carbon black is preferably 0.1 parts by weight or more and 2.6 parts by weight or less, based on 100 parts by weight of carbon black, 0.2 parts by weight or more, The amount is more preferably no more than parts by weight, particularly preferably no less than 0.2 parts by weight and no more than 1 part by weight.

  In the present invention, the addition amount of the amine compound relative to the vinyl alcohol skeleton-containing resin is preferably 10 parts by weight or more and 67 parts by weight or less, and preferably 20 parts by weight or more and 33 parts by weight or less with respect to 100 parts by weight of the vinyl alcohol skeleton containing resin. Is more preferable.

By blending at such a ratio, the viscosity of the carbon black dispersion, which is a problem to be solved by the present invention, can be reduced, and a dispersion having a high concentration and excellent dispersibility and storage stability can be obtained. It becomes easy.
<Active material>
When using the dispersion liquid of this invention for a battery electrode compound-material layer, a positive electrode active material or a negative electrode active material can be contained further.

  The positive electrode active material for the lithium ion secondary battery is not particularly limited, but metal oxides capable of doping or intercalating lithium ions, metal compounds such as metal sulfides, and conductive polymers are used. be able to.

Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, and transition metal sulfide powders such as TiS ₂ and FeS. In addition, conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene can also be used. Moreover, you may mix and use said inorganic compound and organic compound.

The negative electrode active material for the lithium ion secondary battery is not particularly limited as long as it can be doped or intercalated with lithium ions. For example, metal Li, alloys thereof such as tin alloys, silicon alloys, lead alloys, Li _x Fe ₂ O ₃ , Li _x Fe ₃ O ₄ , Li _x WO ₂ , lithium titanate, lithium vanadate, silicon Metal oxides such as lithium oxide, conductive polymers such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon and hard carbon, artificial graphite such as highly graphitized carbon materials, or natural Examples thereof include carbonaceous powders such as graphite, carbon black, mesophase carbon black, resin-fired carbon materials, air-growth carbon fibers, and carbon fibers. These negative electrode active materials can be used alone or in combination.

  These active materials preferably have an average particle diameter in the range of 0.05 to 100 μm, and more preferably in the range of 0.1 to 50 μm. The average particle diameter of the active material as used herein is an average value of particle diameters obtained by measuring the active material with an electron microscope.

  In the present invention, conventionally known dispersants, resins, additives and the like may be used in combination for the purpose of adjusting the physical properties of the coating film and the like as long as the above-described problems are not affected.

Examples of such a dispersant include polyvinyl alcohol resin, polyvinyl butyral resin, polyvinyl acetal resin, polyvinyl formal resin, polyvinyl butyral resin and polyvinyl pyrrolidone resin, conventionally known dye derivatives, and low molecular weight surfactants. . Examples of the resin include polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene, polypropylene, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid, polyacrylamide, and polyurethane. , Various rubbers such as polydimethylsiloxane, epoxy resin, acrylic resin, polyester resin, melamine resin, phenol resin, styrene butadiene rubber, lignin, pectin, gelatin, xanthan gum, welan gum, succinoglycan, cellulosic resin, polyalkylene oxide, Examples include polyvinyl ether, chitins, chitosans, starch and the like. Examples of the additive include phosphorus compounds, sulfur compounds, organic acids, amine compounds and amide compounds, organic esters, various silane-based, titanium-based, and aluminum-based coupling agents. These conventionally known dispersants, resins, additives and the like can be used alone or in combination of two or more.
<Uses of carbon black dispersion>
The field of application of the carbon black dispersion of the present invention is not particularly limited, but is a field where light shielding properties, electrical conductivity, durability, jetness, etc. are required, for example, gravure ink, offset ink, magnetic recording medium back In coatings, electrostatic toners, ink jets, automobile paints, fiber / plastic forming materials, battery electrodes, and electrophotographic seamless belts, a stable and uniform composition can be provided. Among them, the use of NMP, compatibility with polyvinylidene fluoride, polyimide precursors, and the like, and the strength and flexibility of the formed coating film and molded product, the electrode for lithium ion secondary battery, It is suitably used for electric double layer capacitor electrodes, lithium ion capacitor electrodes, electrophotographic seamless belts, and the like.

  Using the carbon black dispersion of the present invention and further adding a binder such as polyvinylidene fluoride and polytetrafluoroethylene, a primer for a lithium ion secondary battery electrode, an electric double layer capacitor electrode, or a lithium ion capacitor electrode Lithium ion secondary battery by adding a layer, and positive and negative active materials such as lithium transition metal composite oxides such as lithium cobaltate and lithium manganate, graphite, activated carbon, graphite, carbon nanotubes and carbon nanofibers Electrode layers for electrodes, electrodes for electric double layer capacitors, and electrodes for lithium ion capacitors can be manufactured. In addition, the electrophotographic seamless belt can be produced by a conventionally known method using the carbon black dispersion of the present invention as a conductive material, polyimide, polyamideimide, and the like as precursors.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example, unless the summary is exceeded. In this example, “part” represents “part by weight” and “%” represents “% by weight”.

 Carbon black (sometimes abbreviated as “CB”), polyvinyl butyral resin (sometimes abbreviated as “PVB”), polyvinyl acetal resin, polyvinyl formal resin, polyvinyl alcohol resin (“ PVA "may be abbreviated), other dispersants, amine compounds, binders, electrode active materials and the like are shown below.

Moreover, although only the composition of each raw material is described in each table, the remaining components not particularly described are all N-methyl-2-pyrrolidone (NMP).
<Carbon black>
# 30 (manufactured by Mitsubishi Chemical Corporation): furnace black, primary particle diameter 30 nm, specific surface area 74 m ² / g, hereinafter abbreviated as # 30.
# 5 (Mitsubishi Chemical Co., Ltd.): Furnace black, average primary particle diameter 76 nm, specific surface area 29 m ² / g, hereinafter abbreviated as # 5.
MA77 (Mitsubishi Chemical Corporation): oxidized carbon black, primary particle diameter 23 nm, specific surface area 130 m ² / g, hereinafter abbreviated as MA77.
Denka black HS-100 (manufactured by Denki Kagaku Kogyo): acetylene black, primary particle diameter 48 nm, specific surface area 39 m ² / g, hereinafter abbreviated as HS-100.
Denka black granular product (manufactured by Denki Kagaku Kogyo Co., Ltd.): Acetylene black, primary particle diameter 35 nm, specific surface area 69 m ² / g, hereinafter abbreviated as granular product.
EC-300J (manufactured by Akzo): Ketjen black, primary particle diameter 40 nm, specific surface area 800 m ² / g, hereinafter abbreviated as 300J.
(Measurement method of average primary particle size of carbon black)
The average primary particle size (MV) of carbon black was measured (calculated) by the method shown below. A sample for measurement was prepared by adding propylene glycol monomethyl ether acetate to a carbon black powder, adding a small amount of Disperbyk-161 as a resin-type dispersant, and dispersing the mixture in a water bath of an ultrasonic cleaner for 1 minute. This sample was applied to a measurement target, dried, and taken with a transmission electron microscope (transmission electron microscope H-7650, manufactured by Hitachi High-Technologies Corporation) to photograph 100 or more primary particles of carbon black. In the photographed image, an arbitrary 100 carbon black particles are selected, the average value of the minor axis diameter and major axis diameter of the primary particles is defined as the particle diameter (d), and then the individual carbon blacks are obtained. Considering it as a sphere having a diameter (d), the volume (V) of each particle was determined, and this operation was performed on 100 carbon black particles, and the calculation was performed using the following equation (1).

Formula (1) MV = Σ (V · d) / Σ (V)

<Polyvinyl butyral resin, polyvinyl acetal resin>
ESREC BL-10 (manufactured by Sekisui Chemical Co., Ltd.): polyvinyl butyral resin, hydroxyl group 28 mol%, butyral degree of 71 mol%, calculated molecular weight 15000. Hereinafter, it is abbreviated as BL-10.
ESREC BX-5 (manufactured by Sekisui Chemical Co., Ltd.): polyvinyl acetal resin, hydroxyl group 33 mol%, acetalization degree 66 mol%, calculated molecular weight 130000. Hereinafter, abbreviated as BX-1.
ESREC KS-10 (manufactured by Sekisui Chemical Co., Ltd.): polyvinyl acetal resin, hydroxyl group 25 mol%, acetalization degree 74 mol%, calculated molecular weight 17000. Hereinafter, abbreviated as KS-10.
Mobital B30HH (manufactured by Kuraray): polyvinyl butyral resin, 11% hydroxyl group. Hereinafter, it is abbreviated as B30HH.
<Polyvinyl formal resin>
-Vinylec K (manufactured by JNC): polyvinyl formal resin. Hereinafter abbreviated as vinylec.
<Polyvinyl alcohol resin>
Kuraray Poval PVA-405 (manufactured by Kuraray): polyvinyl alcohol resin, saponification degree 82 mol%, average polymerization degree 500, hereinafter abbreviated as PVA-405.
Kuraray Poval C-506 (manufactured by Kuraray): cation-modified polyvinyl alcohol resin, saponification degree 76 mol%, average polymerization degree 600, hereinafter abbreviated as C-506.
<Dispersant>
[Surfactant]
Emulgen A-60 (manufactured by Kao Corporation): nonionic surfactant (polyoxyethylene distyrenated phenyl ether), hereinafter abbreviated as EmA-60.
Demol N (manufactured by Kao Corporation): an anionic surfactant (a sodium salt of β-naphthalenesulfonic acid-formalin condensate), hereinafter abbreviated as DemN.
Azisper PB-821 (manufactured by Ajinomoto Fine Techno Co.): a basic functional group-containing copolymer, hereinafter abbreviated as PB-821.
<Amine compound>
Ethylamine: Aliphatic primary amine. Molecular formula C ₂ H ₇ N. Molecular weight 45.
N-octylamine: an aliphatic primary amine. Molecular formula C ₈ H ₁₇ NH ₂ . Molecular weight 129. Hereinafter, it is abbreviated as octylamine.
Stearylamine: an aliphatic primary amine. Molecular formula C ₁₈ H ₃₇ NH ₂ . Molecular weight 269.5.
-Distearylamine: Aliphatic secondary amine. Molecular formula C ₃₆ H ₇₅ N.
-Dimethyloctylamine: Aliphatic tertiary amine. Molecular formula C ₁₀ H ₂₃ N. Molecular weight 157.
-Dimethylhexadecylamine: An aliphatic tertiary amine. Molecular formula C ₁₈ H ₃₉ N. Molecular weight 269.5.
Tri-n-octylamine: an aliphatic tertiary amine. Molecular formula C ₂₄ H ₅₁ N. Molecular weight 354. Hereinafter, it is abbreviated as trioctylamine.
Triethanolamine: an alkanolamine-based tertiary amine. Molecular formula C ₆ H ₁₅ NO ₃ . pKa = 7.6.
Diethanolamine: Alkanolamine secondary amine. Molecular formula C ₄ H ₁₁ NO ₂ . pKa = 8.9.
N, N-dimethyl-2-aminoethanol: Aminoethanol-based tertiary amine. Molecular formula C ₄ H ₁₁ NO. pKa = 9.8. Hereinafter, it is abbreviated as DMAE.
Amite 102 (manufactured by Kao Corporation): polyoxyethylene dodecylamine (average EO = 2 mol addition, tertiary amine).
Amite 105 (manufactured by Kao Corporation): polyoxyethylene dodecylamine (average EO = 5 mol addition, tertiary amine).
Amite 302 (manufactured by Kao Corporation): polyoxyethylene octadecylamine (average EO = 2 mol addition, tertiary amine).
Amit 320 (manufactured by Kao Corporation): polyoxyethylene octadecylamine (average EO = 20 mol addition, tertiary amine).
Polyethyleneimine 1200 (manufactured by Junsei Co., Ltd.): molecular weight 1200, amine value 19. Hereinafter, it is abbreviated as PEI1200.
Polyethyleneimine 1800 (manufactured by Junsei Co., Ltd.): molecular weight 1800, amine value 19. Hereinafter, it is abbreviated as PEI1800.
Polyethyleneimine 10000 (manufactured by Junsei Co., Ltd.): molecular weight 10,000, amine number 18. Hereinafter, it is abbreviated as PEI10000.
-Hexamethylenetetramine: An alicyclic nitrogen-containing heterocyclic compound (tertiary amine). Molecular formula C ₆ H ₁₂ N ₄ .
L (+)-arginine: basic amino acid. Molecular formula C ₆ H ₁₄ N ₄ O ₂ . Hereinafter, abbreviated as arginine.
L-aspartic acid: acidic amino acid. Molecular formula C ₄ H ₇ NO ₂ . Hereinafter, it is abbreviated as aspartic acid.
L-asparagine monohydrate: neutral amino acid. Molecular formula C ₄ H ₈ N ₂ O ₃ . Hereinafter, it is abbreviated as asparagine.
<Other nitrogen-containing compounds>
Acrylamide: An amide compound. Molecular formula C ₃ H ₅ NO.
Acetonitrile: A nitrile compound. Molecular formula C ₂ H ₃ N.
<Binder>
KF polymer W1100 (manufactured by Kureha): polyvinylidene fluoride (PVDF), hereinafter abbreviated as PVDF.
-KF polymer W7300 (manufactured by Kureha): polyvinylidene fluoride (PVDF), hereinafter abbreviated as # 7300.
<Active material>
HLC-22 (Honjo Chemical Co., Ltd.): positive electrode active material lithium cobaltate (LiCoO ₂ ), average particle size 6.6 μm, specific surface area 0.62 m ² / g, hereinafter abbreviated as LCO.
Artificial graphite: negative electrode active material, average particle size 18 μm, hereinafter abbreviated as graphite.
<Evaluation of carbon black dispersion>
The carbon black dispersions obtained in Examples and Comparative Examples were evaluated by measuring the viscosity and average particle diameter after dispersion.

  The viscosity value was measured using a B-type viscometer (“BL” manufactured by Toki Sangyo Co., Ltd.), and the dispersion was sufficiently stirred with a spatula at a dispersion temperature of 25 ° C. and a B-type viscometer rotor rotating at 60 rpm. Then went immediately. The rotor used for the measurement is No. when the viscosity value is less than 100 mPa · s. No. 1 is 100 or more and less than 500 mPa · s. 2 is 500 or more and less than 2000 mPa · s. 3 is 2000 or more and less than 10,000 mPa · s. Four of each were used. The case where the obtained viscosity value was 10,000 mPa · s or more was described as “> 10000”, but this indicates that the viscosity was so high that it could not be evaluated with the B-type viscometer used for the evaluation. The lower the viscosity, the better the dispersibility, and the higher the viscosity, the poor the dispersibility. The storage stability was evaluated from the change in viscosity value after the carbon black dispersion was stored at 50 ° C. for 10 days. The smaller the change, the better the stability.

  In addition, the average particle size after dispersion was measured by diluting the carbon black dispersion with NMP to an appropriate concentration and then using the ultrasonically treated liquid as a measurement sample, and using a dynamic light scattering particle size distribution analyzer ( The measurement was performed by measuring the average particle diameter (D50 value) using “Nanotrack UPA-EX” manufactured by Nikkiso Co., Ltd., light source wavelength 780 nm). Various measurement conditions were such that the loading index value of the dispersion diluted with NMP by the above method was 0.7 or more and 1.3 or less, the particle conditions were absorbent particles, particle shape non-spherical, density 1.80, and the solvent conditions were The solvent refractive index was 1.47, the solvent viscosity was 1.80 mPa · s at a liquid temperature of 20 ° C., the solvent viscosity was 1.65 mPa · s at a liquid temperature of 25 ° C., and the obtained median diameter was expressed as a D50 value. The measurement result is obtained by measuring the background value of the NMP solvent at a liquid temperature of 25 ° C., filling a sample with the liquid temperature of 25 ° C. prepared by the above method into a measurement container, and performing the measurement under the above measurement conditions. It was.

When the same carbon black is used, the smaller the D50 value, the better the dispersibility, and the larger the D50 value, the poorer the dispersibility. The storage stability was evaluated from the change in the D50 value after storing the carbon black dispersion at 50 ° C. for 10 days. The smaller the change, the better the stability.
<Preparation of carbon black dispersion>
(Carbon black dispersion using polyvinyl butyral resin or polyvinyl acetal resin and various amine compounds)
[Example 1-1 to Example 1-17]
In accordance with the composition shown in Table 1, NMP and polyvinyl butyral resin or polyvinyl acetal resin and various amine compounds are charged into a glass bottle, mixed and dissolved or mixed and dispersed. As a result, each carbon black dispersion was obtained by dispersing with a paint shaker for 2 hours. In all cases, the viscosity was low, the D50 value was small, and the storage stability was good.
[Comparative Example 1-1 to Comparative Example 1-4]
In accordance with the composition shown in Table 1, NMP and BX-5 or various dispersants are charged into a glass bottle, mixed and dissolved, or mixed and dispersed. Then, various carbon blacks are added, and 1.25 mmφ zirconia beads are used as media. Dispersed for 2 hours on a shaker. However, all of the obtained dispersions are in a high-viscosity state, a remarkably high-viscosity state, or because the D50 value is large, it can be seen that carbon black cannot be sufficiently dispersed. . From these results, when various vinyl alcohol skeleton-containing resins are used alone as dispersants or when conventionally known dispersants are used, a desired high concentration and low viscosity carbon black dispersion can be obtained. It became clear that it was not possible.
<Preparation of carbon black dispersion containing binder>
[Example 2-1 to Example 2-31]
In accordance with the composition shown in Table 2, NMP, various vinyl alcohol skeleton-containing resins, various amine compounds and various binders are charged into a glass bottle, mixed and dissolved or mixed and dispersed, and then various carbon blacks are added and dispersed with a homogenizer for 1 hour. Each carbon black dispersion was obtained. All of them had no coarse particles, had a low viscosity, and had good storage stability.
[Example 2-39]
According to the composition shown in Table 2, NMP, BL-10, and octylamine were charged into a glass bottle and sufficiently mixed and dissolved. Next, a powder mixture in which the granular product and PVDF were homogeneously mixed was prepared, and this was added to the NMP solution of BL-10 and octylamine prepared in advance. Then, it disperse | distributed for 1 hour with the homogenizer, and obtained the carbon black dispersion liquid. There were no coarse particles, the viscosity was low, and the storage stability was good.
[Example 2-40]
According to the composition shown in Table 2, 65 parts of the carbon black dispersion liquid of Example 1-1, 6.5 parts of PVDF and 28.5 parts of NMP were added to a glass bottle and dispersed for 1 hour with a homogenizer. Got. There were no coarse particles, the viscosity was low, and the storage stability was good.
[Comparative Examples 2-1 to 2-3]
In accordance with the composition shown in Table 2, NMP, various vinyl alcohol skeleton-containing resins and PVDF are charged into a glass bottle, and after mixing and dissolving or mixing and dispersing sufficiently, the granular product is added and dispersed for 1 hour with a homogenizer. Got. However, it was revealed that the viscosity of the obtained dispersion was as high as that prepared without adding a binder, and the carbon black and binder concentrations could not be further improved.
[Comparative Examples 2-4 to 2-5]
In accordance with the composition shown in Table 2, NMP, BL-10, various additives and PVDF are charged into a glass bottle, and after mixing and dissolving or mixing and dispersing sufficiently, a granular product is added and dispersed for 1 hour with a homogenizer. A dispersion was obtained. However, the viscosity of the obtained dispersion was as high as when various vinyl alcohol skeleton-containing resins were used alone as a dispersant, and it became clear that the concentration of carbon black and binder could not be further improved. .
[Comparative Example 2-6, Comparative Example 2-8, Comparative Example 2-10]
In accordance with the composition shown in Table 2, NMP, various vinyl alcohol skeleton-containing resins, octylamine, and PVDF were charged into a glass bottle, thoroughly mixed and dissolved, or mixed and dispersed, then added with HS-100, and dispersed with a homogenizer for 1 hour. Each carbon black dispersion was obtained. However, the viscosity of the obtained dispersion is as high as when using various vinyl alcohol skeleton-containing resins alone as a dispersant, and the amount of octylamine added to 100 parts by weight of carbon black is 0.1 wt. It was revealed that the carbon black and binder concentration could not be further improved when the amount was smaller than the part.
[Comparative Example 2-7, Comparative Example 2-9, Comparative Example 2-11]
In accordance with the composition shown in Table 2, NMP, various vinyl alcohol skeleton-containing resins, octylamine and PVDF were charged into a glass bottle, mixed and dissolved, or mixed and dispersed. A carbon black dispersion was obtained. There were no coarse particles and the viscosity was low, but the storage stability was not good.
[Comparative Example 2-12 to Comparative Example 2-13]
In accordance with the composition shown in Table 2, NMP, BL-10, octylamine and PVDF are charged into a glass bottle, and after mixing and dissolving or mixing and dispersing sufficiently, the granular product is added and dispersed with a homogenizer for 1 hour, and each carbon black is dispersed. A liquid was obtained. All of the obtained dispersions were in a state of extremely high viscosity and the D50 value was large, so that carbon black could not be sufficiently dispersed.
<Preparation of carbon black dispersion containing positive electrode active material or negative electrode active material as powder other than carbon black>
[Example 3-1 to Example 3-7]
Carbon containing a binder obtained in Examples 2-2 to 2-4, Example 2-6, Example 2-8, Example 2-9, and Example 2-11 according to the composition shown in Table 3 LCO, which is a positive electrode active material, was charged into the black dispersion and thoroughly mixed with a disper to obtain each liquid mixture. Since the carbon black dispersion used had a low viscosity, a large amount of LCO could be added, and the resulting mixture was also in a low viscosity state.
[Example 3-8 to Example 3-10]
In accordance with the composition shown in Table 3, graphite as a negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Example 2-2, Example 2-4, and Example 2-8, and a disper was used. Mix well to obtain each mixture. Since the carbon black dispersion used had a low viscosity, a large amount of graphite could be added, and the resulting mixture was also in a low viscosity state.
[Comparative Examples 3-1 to 3-3]
In accordance with the composition shown in Table 3, LCO as the positive electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Example 2-1, Comparative Example 2-6, and Comparative Example 2-7, and a disper was used. Mix well to obtain each mixture. In any case, since the viscosity value of the carbon black dispersion used was high, the increase in the viscosity value when LCO was added was larger than in Examples 3-1 to 3-7, and the stability was also high. The increase in viscosity in the evaluation test was also large.
[Comparative Example 3-4 to Comparative Example 3-6]
In accordance with the composition shown in Table 3, graphite as a negative electrode active material was charged into the carbon black dispersion containing the binder obtained in Comparative Example 2-1, Comparative Example 2-6, and Comparative Example 2-7, and a disper was used. Mix well to obtain each mixture. In any case, since the viscosity value of the carbon black dispersion used was high, the increase in the viscosity value when MFC was added was larger than in Examples 3-8 to 3-11, and the stability was also high. The increase in viscosity in the evaluation test was also large.
<Preparation of battery electrode composite layer>
After applying the carbon black dispersion containing the positive electrode active material or the negative electrode active material obtained in each of the above Examples and Comparative Examples as a battery electrode mixture liquid on a polyethylene terephthalate (PET) film using a doctor blade The film was dried at 120 ° C. under reduced pressure for 30 minutes, and a dried film (battery electrode mixture layer) having a film thickness of 100 μm was produced.

Evaluation of the obtained battery electrode mixture layer was performed by surface resistance and coating film appearance. The surface resistance was measured according to JIS K7194 using Loresta GP (manufactured by Mitsubishi Chemical Analytech). The appearance of the coating film was visually determined as follows: ○: no problem (good), Δ: spotted pattern (bad), x: coarse grain streaking (very bad).
[Example 4-1 to Example 4-7, Comparative Example 4-1 to Comparative Example 4-2]
As the positive electrode mixture liquid, the battery electrode mixture liquid obtained in Example 3-1 to Example 3-7 and Comparative Example 3-2 to Comparative Example 3-3 was used. Material layer). The evaluation results are shown in Table 4.
[Example 4-8 to Example 4-10, Comparative Example 4-3 to Comparative Example 4-4]
As the negative electrode mixture liquid, the battery electrode mixture liquid obtained in Examples 3-8 to 3-10 and Comparative Examples 3-5 to 3-6 was used, and the negative electrode mixture layer (battery electrode) A composite layer) was prepared. The evaluation results are shown in Table 4.

From Table 4, the battery electrode mixture layer of Example 4-1 to Example 4-10 has a better coating film appearance than the battery electrode mixture layer of Comparative Example 4-1 to Comparative Example 4-4. Furthermore, it was revealed that the surface resistance of the coating film was excellent. In Comparative Example 4-1 and Comparative Example 4-3, coating was difficult because the viscosity of the electrode mixture solution used was too high. Moreover, in Comparative Example 4-2 and Comparative Example 4-4, it is considered that the surface resistance value increased as a result of the amine compound contained in a large amount functioning as an insulating component.
<Assembly of lithium ion secondary battery positive electrode evaluation cell>
[Example 5-1 to Example 5-7, Comparative Example 5-1 to Comparative Example 5-2]
The previously prepared battery electrode mixture liquid (the positive electrode mixture liquids of Example 3-1 to Example 3-7, Comparative Example 3-2, and Comparative Example 3-3) having a thickness of 20 μm serving as a current collector After apply | coating using a doctor blade on aluminum foil, after heat-drying at 120 degreeC under pressure reduction, it rolled with the roller press machine and produced the positive mix layer of thickness 100 micrometers. This is a punching working electrode with a diameter of 9 mm, a metallic lithium foil (thickness 0.15 mm) as a counter electrode, and a separator made of a porous polypropylene film (# 2400 manufactured by Celgard) is inserted and laminated between the working electrode and the counter electrode, An electrolyte solution (nonaqueous electrolyte solution in which LiPF ₆ is dissolved at a concentration of 1M in a mixed solvent of ethylene carbonate and diethyl carbonate mixed at a volume ratio of 1: 1) is filled and a bipolar electrode type metal cell (HS manufactured by Hosen Co., Ltd.) Flat cell). The cell was assembled in a glove box substituted with argon gas.
<Assembly of lithium ion secondary battery negative electrode evaluation cell>
[Examples 5-8 to 5-10, Comparative Example 5-3 to Comparative Example 5-4]
The previously prepared battery electrode mixture (the negative electrode mixture liquids of Examples 3-8 to 3-10, Comparative Example 3-5, and Comparative Example 3-6) was used as a current collector in aluminum having a thickness of 20 μm. After apply | coating using a doctor blade on foil, it heat-dried at 120 degreeC under pressure reduction, Then, it rolled by the roller press machine, and produced the 100-micrometer-thick negative mix layer. This is a punching working electrode with a diameter of 9 mm, a metallic lithium foil (thickness 0.15 mm) as a counter electrode, and a separator made of a porous polypropylene film (# 2400 manufactured by Celgard) is inserted and laminated between the working electrode and the counter electrode, An electrolyte solution (nonaqueous electrolyte solution in which LiPF ₆ is dissolved at a concentration of 1M in a mixed solvent of ethylene carbonate and diethyl carbonate mixed at a volume ratio of 1: 1) is filled and a bipolar electrode type metal cell (HS manufactured by Hosen Co., Ltd.) Flat cell). The cell was assembled in a glove box substituted with argon gas.
<Characteristic evaluation of lithium ion secondary battery positive electrode>
Using the charging / discharging device (SM-8 manufactured by Hokuto Denko Co., Ltd.) at 25 ° C., the prepared positive electrode evaluation cell was fully charged with constant current and constant voltage charging (upper limit voltage 4.2 V) at a charging rate of 1.0 C. The charge / discharge for discharging to the discharge lower limit voltage of 3.0 V at a constant current at the same rate as the charge was defined as one cycle (charge / discharge interval pause time 30 minutes), and this cycle was performed for a total of 50 cycles to perform charge / discharge. . The cell after evaluation was disassembled, and the appearance of the electrode coating film (the coating film appearance after 50 cycles) was visually confirmed. Evaluation criteria for coating film appearance are ○ (very good) when no peeling is observed and no change in appearance, △ (good) when there is no peeling but change in appearance, partially mixed Was evaluated as x (defect) when peeling from the current collector was observed. Further, the capacity retention ratio is a percentage of the discharge capacity at the 50th cycle with respect to the discharge capacity at the 1st cycle, and the closer the value is to 100%, the better. When a normal charge / discharge curve could not be obtained due to a short circuit or the like, and the capacity could not be obtained, no value was given (−). The evaluation results are shown in Table 5.
<Evaluation of lithium ion secondary battery negative electrode characteristics>
Using the charging / discharging device (SM-8 manufactured by Hokuto Denko Co., Ltd.) at 25 ° C., the prepared negative electrode evaluation cell was fully charged with constant current and constant voltage charging (lower limit voltage 0.5 V) at a charging rate of 1.0 C. Charging / discharging is performed at a constant current at the same rate as during charging until the voltage reaches 1.5 V, and one cycle (charging / discharging interval pause time 30 minutes) is performed, and this cycle is performed for a total of 50 cycles. It was. The cell after the evaluation was disassembled, and the appearance of the electrode coating film (the coating film appearance after 50 cycles) was evaluated based on the same criteria as the positive electrode characteristic evaluation. Further, the capacity retention rate was determined in the same manner as the positive electrode characteristics. The evaluation results are shown in Table 5.

  From Table 5, Example 5-1 to Example 5-7 and Example 5-8 to Example 5-10 using the electrode of the present invention are Comparative Example 5-1 to Comparative Example 5-2 and Comparative Example. Compared with 5-3 to Comparative Example 5-4, the coating film appearance was good, and the capacity retention rate after 50 cycles was also good.

  However, acrylamide and acetonitrile are other nitrogen-containing compounds.

Claims (8)

  It contains carbon black, vinyl alcohol skeleton-containing resin, N-methyl-2-pyrrolidone, and an amine compound. The vinyl alcohol skeleton-containing resin is 1 part by weight or more and 15 parts by weight with respect to 100 parts by weight of carbon black. Carbon black dispersion liquid containing 0.1 part by weight or more and 2.6 parts by weight or less of an amine compound.   It contains 1 to 8 parts by weight of a vinyl alcohol skeleton-containing resin with respect to 100 parts by weight of carbon black, and contains 0.2 to 1.5 parts by weight of an amine compound. The carbon black dispersion according to claim 1.   The amine compound is selected from the group consisting of aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines, amino acids, alkanolamines, polyoxyalkylene alkylamines, polyamines and alicyclic nitrogen-containing heterocyclic compounds. The carbon black dispersion according to claim 1, wherein the carbon black dispersion is one or more kinds of amine compounds.   One or more selected from the group consisting of aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines, alkanol amines and polyoxyalkylene alkyl amines, wherein the amine compound has only one amino group. The carbon black dispersion according to claim 3, wherein the carbon black dispersion is an amine compound. However, the amino group is a primary, secondary or tertiary functional group.   The vinyl alcohol skeleton-containing resin is one or more vinyl alcohol skeleton-containing resins selected from the group consisting of polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, and polyvinyl formal resins. 4. The carbon black dispersion according to any one of 4 above.   A carbon black dispersion for a battery comprising the carbon black dispersion according to any one of claims 1 to 5 and further containing a positive electrode active material or a negative electrode active material.   A battery electrode mixture layer formed by applying the carbon black dispersion according to claim 1 or the battery carbon black dispersion according to claim 6.   A lithium ion secondary battery comprising a positive electrode having a positive electrode mixture layer on a current collector, a negative electrode having a negative electrode mixture layer on the current collector, and an electrolyte containing lithium, wherein the positive electrode and the negative electrode are at least A lithium ion secondary battery, one of which comprises the battery electrode mixture layer according to claim 7.