JP6509592B2 - Carbon black dispersion liquid and carbon black composite resin - Google Patents

Description

  The present invention relates to a carbon black dispersion, a carbon black composite resin, and a dispersant for carbon black.

  Carbon black is a fine particle composed of almost only carbon, and is widely used in various resin compositions for various purposes. Carbon black is used, for example, as a conductive material for batteries and conductive resins, and as a coloring material for inks and paints, from the viewpoint of conductivity and light absorption. In addition, it is also used as a filler for the purpose of improving the strength of a resin and improving the abrasion resistance because of the characteristics of physical properties such as hardness.

  A carbon black composite resin in which such carbon black is dispersed in various resin compositions is a method in which the carbon black is directly kneaded into the resin, or a method in which a dispersion of carbon black and a resin emulsion are uniformly mixed and precipitated with a coagulant. And so on.

  For example, Patent Document 1 discloses a carbon black dispersion having excellent dispersibility, which is obtained by treating the surface of carbon black with an oxidizing agent to impart surface acidic groups, and obtained using the carbon black dispersion. Carbon black composite resins have been proposed. Patent Document 2 proposes a carbon black composite resin obtained by adding an acrylic resin and carbon black to a solvent, mixing and dispersing them in a media mill, and then mixing with rubber and removing the solvent.

JP, 2011-16874, A JP 2002-338800 A

  However, in Patent Document 1, since an oxidizing agent is required, there is a problem of processing cost and processing waste solution, and it is desirable that carbon black whose surface is not treated can also be used. In Patent Document 2, since a solvent removal step is required, equipment cost and running cost are increased, and residual solvent and salt may lower the performance of the carbon black composite resin.

  Furthermore, in recent years, fine carbon black having an average primary particle diameter of 30 nm or less has come to be used in order to realize the performance such as the conductivity and blackness of a carbon black composite resin greater than conventional carbon black. However, since the fine carbon black has a large surface area, the dispersion stability in the dispersion liquid tends to be lowered. When a large amount of a dispersant is used to improve the dispersibility, the coprecipitation property of the carbon black and the resin is reduced, and a carbon black composite resin having good performance can not be obtained.

  The present invention provides a carbon black dispersion which is excellent in the dispersibility of fine carbon black having an average primary particle diameter of 30 nm or less, the dispersion stability, and the coprecipitation property with a resin. Furthermore, the present invention provides a carbon black composite resin which is excellent in the dispersed state of fine carbon black having an average primary particle diameter of 30 nm or less and is excellent in the performance such as the conductivity and the degree of blackness. Furthermore, the present invention provides a dispersant used to disperse carbon black having an average primary particle diameter of 30 nm or less, from which a carbon black dispersion having excellent coprecipitability with the above resin can be obtained.

  As a result of intensive studies to solve the problems in the above-mentioned prior art, the present inventors have completed the present invention.

That is, the present invention includes a carbon black, a dispersant, and an aqueous medium, wherein the average primary particle diameter of the carbon black is 30 nm or less, and the dispersant includes the following copolymer A. About.
Copolymer A: containing a structural unit (a) derived from a branched α-olefin and a structural unit (b) derived from at least one compound selected from an unsaturated dibasic acid and an anhydride thereof, Copolymer in which at least a part of the structural unit (b) is neutralized by a compound represented by the following formula (I)

［式（Ｉ）において、Ｒ¹、Ｒ²及びＲ³は同一又は異なり、水素原子、及び他の元素を含んでよい炭素数１以上４以下のアルキル基から選ばれる少なくとも１種である。］

[In formula (I), R ¹ , R ² and R ³ are the same or different, and are at least one selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms which may contain other elements. ]

The present invention relates to a carbon black composite resin obtained by a manufacturing method including the following steps (1) to (3).
(1) A step of mixing the carbon black dispersion liquid of the present invention and an aqueous resin emulsion to obtain a mixed liquid.
(2) A step of adding an acid to the mixed solution to form a coprecipitate of carbon black and a resin.
(3) A step of drying the coprecipitate.

The present invention is a dispersant containing the above-mentioned copolymer A, wherein
The present invention relates to a dispersant used to disperse carbon black having an average primary particle size of 30 nm or less in an aqueous medium.

  The carbon black dispersion liquid of the present invention can exhibit the effect of being able to improve the dispersibility, dispersion stability, and coprecipitation property with a resin of fine carbon black having an average primary particle diameter of 30 nm or less. Furthermore, the carbon black composite resin of the present invention can exhibit an effect that the dispersed state of fine carbon black having an average primary particle diameter of 30 nm or less is good and the performance such as conductivity and blackness is excellent. Furthermore, the carbon black dispersant of the present invention has the effect of being able to realize a carbon black dispersion liquid excellent in coprecipitation property with a carbon black resin having an average primary particle diameter of 30 nm or less, and a carbon black composite resin excellent in performance. Can play.

  The present inventor uses the copolymer containing the structural unit (a) and the structural unit (b) as a dispersant and at least a part of which is neutralized by a specific neutralizing agent, to obtain an average primary particle. It has been found that it is possible to realize a carbon black dispersion (hereinafter, also simply referred to as "dispersion") excellent in the dispersibility of fine carbon black having a diameter of 30 nm or less, the dispersion stability, and the coprecipitation with a resin. Furthermore, the present inventor uses carbon black as a dispersant by using a copolymer containing the structural unit (a) and the structural unit (b) and at least a part of which is neutralized by a specific neutralizing agent. The dispersed state of fine carbon black can be made excellent in the composite resin (hereinafter, also simply referred to as “composite resin”), and further the performance of the carbon black composite resin such as conductivity and blackness can be improved. Found out.

The dispersion of the present disclosure includes, in one aspect, carbon black, a dispersant, and an aqueous medium, the average primary particle diameter of the carbon black is 30 nm or less, and the dispersant includes the following copolymer A. .
Copolymer A: containing a structural unit (a) derived from a branched α-olefin and a structural unit (b) derived from at least one compound selected from an unsaturated dibasic acid and an anhydride thereof, Copolymer in which at least a part of the structural unit (b) is neutralized by a compound represented by the following formula (I)

［式（Ｉ）において、Ｒ¹、Ｒ²及びＲ³は同一又は異なり、水素原子、及び他の元素を含んでよい炭素数１以上４以下のアルキル基から選ばれる少なくとも１種である。］

[In formula (I), R ¹ , R ² and R ³ are the same or different, and are at least one selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms which may contain other elements. ]

[Carbon black]
The average primary particle size of carbon black in the present disclosure is 30 nm or less, preferably 25 nm or less, from the viewpoint of improving the performance of the composite resin, and preferably 10 nm or more, more preferably 15 nm from the viewpoint of dispersibility. It is above. More specifically, it is preferably 10 nm or more and 30 nm or less, and more preferably 15 nm or more and 25 nm or less. The method of calculating the average primary particle diameter is as described in the examples described later.

  As the carbon black in the present disclosure, at least one selected from furnace black and acetylene black is preferable from the viewpoint of dispersibility and performance improvement of the composite resin.

BET specific surface area of the carbon black in the present disclosure, from the viewpoint of dispersibility, preferably 100 m ² / g or more 500 meters ² / g or less, more preferably 120 m ² / g or more 400 meters ² / g or less, more preferably 140 m ² / It is g or more and 300 m ² / g or less. In the present disclosure, the BET specific surface area of carbon black is obtained by the nitrogen adsorption method of Japanese Industrial Standard (JIS) Z8830.

  The pH of carbon black in the present disclosure is preferably 5 or more, more preferably 6 or more, and still more preferably 7 or more, from the viewpoint of productivity and the effects of the present invention, and from the viewpoint of performance improvement of the composite resin, 10 or less is preferable, 9 or less is more preferable, and 8 or less is more preferable. In the present disclosure, the pH of carbon black is obtained by the following measurement method. First, 1 to 5 g of carbon black is precisely weighed, 100 mL of distilled water is added, and stirring is continued at room temperature for 24 hours while being sealed to obtain a suspension. The suspension is then measured with a glass electrode pH meter to obtain the pH of carbon black.

Total surface acidic groups of the carbon black in the present disclosure, in view of expressing effects of productivity and the present invention is preferably less than 3μeq / m ^2, more preferably less than 2μeq / m ^2, less than 1μeq / m ² and more preferable. In the present disclosure, the total surface acidic group content of carbon black is obtained by the following method. First, 1 to 5 g of carbon black is precisely weighed, 100 mL of a 0.05 M aqueous sodium hydroxide solution is added, and stirring is continued for 96 hours at room temperature while being sealed to obtain a suspension. Then, the obtained suspension is filtered with a 0.1 μm membrane filter, 20 mL of the obtained filtrate is titrated with 50 mL of 0.05 M hydrochloric acid, and the amount of acidic group per 1 g of carbon black is calculated from the titration amount which becomes the equivalent point. calculate. By dividing this value by the BET specific surface area, the total amount of acidic groups on the surface can be determined.

  The content of carbon black contained in the dispersion liquid of the present disclosure is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 5% by mass or more, from the viewpoint of productivity and performance improvement of the composite resin. Still more preferably, it is 10% by mass or more, and from the same viewpoint, it is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less.

[Dispersing agent]
The dispersant in the present disclosure includes the following copolymer A. The dispersant of the present disclosure is used to disperse carbon black having an average primary particle size of 30 nm or less in an aqueous medium.
Copolymer A: at least one compound selected from structural unit (a) derived from branched α-olefin (hereinafter also referred to as “monomer (a)”), unsaturated dibasic acid and anhydride thereof And a copolymer containing a constituent unit (b) derived from “monomer (b)” and at least a part of which is neutralized by a compound represented by the following formula (I)

［式（Ｉ）において、Ｒ¹、Ｒ²及びＲ³は同一又は異なり、水素原子、及び他の元素を含んでよい炭素数１以上４以下のアルキル基から選ばれる少なくとも１種である。］

[In formula (I), R ¹ , R ² and R ³ are the same or different, and are at least one selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms which may contain other elements. ]

  The constituent units (a) and (b) constituting the copolymer A are preferably constituent units derived from a radical polymerizable monomer.

  The arrangement of the structural unit (a) and the structural unit (b) may be any of alternating, random, block and graft, but preferably from the viewpoint of ease of production and dispersibility.

［式（ＩＩ）において、Ｒ⁴は水素原子及びアルキル基から選ばれる少なくとも１種、Ｒ⁵はアルキル基を示し、Ｒ⁴が水素原子の場合、Ｒ⁵は分岐鎖状のアルキル基であり、Ｒ⁴とＲ⁵との炭素数の合計は、好ましくは２以上３０以下である。］ In the present disclosure, the branched α-olefin is a compound represented by the following formula (II). In the copolymer A, the structural unit derived from this branched α-olefin is considered to act as an adsorptive group to the carbon black surface.

[In formula (II), R ⁴ is at least one selected from a hydrogen atom and an alkyl group, R ⁵ is an alkyl group, and when R ⁴ is a hydrogen atom, R ⁵ is a branched alkyl group, The total carbon number of R ⁴ and R ⁵ is preferably 2 or more and 30 or less. ]

R ⁴ is preferably at least one selected from a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of dispersibility, performance improvement of the composite resin, and easiness of production of the copolymer A.
The carbon number of R ⁵ is 1 or more, preferably 3 or more, and preferably 28 or less, more preferably 23 or less, still more preferably 17 or less, further preferably from the viewpoint of dispersibility and performance improvement of the composite resin. Is 11 or less, more preferably 7 or less. R ⁵ preferably has a branched chain, more preferably one or more selected from a methyl branch and an ethyl branch, and still more preferably a methyl branch, from the viewpoint of improving the dispersibility and the performance of the composite resin. From the same viewpoint, the number of methyl branches possessed by R ⁵ is preferably 1 or more, and preferably 3 or less, more preferably 2 or less, and still more preferably 2. A preferred example of R ⁵ having two methyl branches is a 2,2-dimethylpropyl group. In the present disclosure, the methyl (ethyl) branch means that the branched chain in the branched alkyl group is a methyl group (ethyl group). R ⁴ is preferably a methyl group, and R ⁵ is preferably selected from a methyl group and a 2, 2-dimethylpropyl group from the viewpoints of dispersibility, performance improvement of composite resin, and easiness of production of copolymer A. Or more preferably a 2,2-dimethylpropyl group.

  The monomer (a) is the branched α-olefin from the viewpoint of dispersibility and performance improvement of the composite resin, and the carbon number thereof is 4 or more, preferably 6 or more, and preferably 32 or less. More preferably, it is 26 or less, more preferably 20 or less, further preferably 14 or less, more preferably 10 or less, and still more preferably 8. Examples of the branched α-olefin include 2-methylpropene (hereinafter also referred to as “isobutylene”), 3,3-dimethyl-1-butene, 2-methyl-1-pentene, 4-methyl-1-pentene, 2, 4-dimethyl-1-pentene, 2,4,4-trimethyl-1-pentene (hereinafter also referred to as “α-diisobutylene”), 2-ethyl-1-hexene, etc. From the viewpoint of performance improvement, at least one selected from isobutylene and α-diisobutylene is preferable, and α-diisobutylene is more preferable.

  In the present disclosure, the unsaturated dibasic acid is a compound having a carbon-carbon double bond and two acidic groups in the molecule. When the monomer (b) is an unsaturated dibasic acid, the monomer (b) is preferably at least one selected from maleic acid, fumaric acid and itaconic acid from the viewpoint of dispersibility and performance improvement of the composite resin. And more preferably maleic acid and fumaric acid. When the monomer (b) is an anhydride of an unsaturated dibasic acid, the monomer (b) is preferably at least one selected from maleic anhydride and itaconic acid from the viewpoint of improving the dispersibility and the performance of the composite resin. It is a species, more preferably maleic anhydride. The monomer (b) is more preferably at least one selected from maleic acid, fumaric acid, and maleic anhydride from the viewpoint of dispersibility and performance improvement of the composite resin.

  In the copolymer A, the molar ratio [(a) / (b)] between the structural unit (a) and the structural unit (b) is preferably 0.2 or more from the viewpoint of improving the dispersibility and the performance of the composite resin. More preferably, it is 0.5 or more, more preferably 0.8 or more, and from the same viewpoint, it is preferably 5.0 or less, more preferably 2.0 or less, and still more preferably 1.2 or less.

  The copolymer A may be a copolymer further containing other structural units (hereinafter also referred to as “structural unit (c)”) in addition to the structural unit (a) and the structural unit (b). Good. The structural unit (c) is preferably a structural unit derived from a radically polymerizable monomer.

  As a monomer which forms the said structural unit (c), (meth) acrylic-acid alkylesters, unsaturated monobasic acids, nonionic group containing monomers, etc. are mentioned.

  Examples of the (meth) acrylic acid alkyl esters include methyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate ( Examples include lauryl methacrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, and behenyl (meth) acrylate.

  Examples of the unsaturated monobasic acids include acrylic acid, methacrylic acid and crotonic acid.

Examples of the nonionic group-containing monomers include 2-hydroxyethyl (meth) acrylate, and (meth) acrylic acid polyalkylene glycol monoester represented by the following formula (III).
CH ₂ = C (R ⁶ ) COO (R ⁷ O) _n R ⁸ (III)
In formula (III), R ⁶ represents at least one selected from a hydrogen atom and a methyl group, R ⁷ represents an alkanediyl group having 2 or 3 carbon atoms, and R ⁸ represents a hydrogen atom and a methyl group. Indicates at least one selected. n represents an average addition mole number and is 1 or more and 100 or less, and preferably 1 or more and 60 or less from the viewpoint of dispersibility.

  The constituent molar ratio of the constituent unit (c) in all constituent units constituting the copolymer A [constituent unit (c) / all constituent units] is 0 or more, and the viewpoint of dispersibility and performance of the composite resin Or less, 0.5 or less is preferable, 0.2 or less is more preferable, 0.1 or less is more preferable, and substantially 0 is even more preferable.

  The copolymer A is a copolymer neutralized by the compound represented by the formula (I) as described above.

  The compound represented by the above formula (I) (hereinafter, also simply referred to as “neutralizing agent N”) includes ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, propylamine, dipropylamine, Isopropylamine, diisopropylamine, butylamine, dibutylamine, isobutylamine, diisobutylamine, monoethanolamine, diethanolamine, triethanolamine, triethanolamine, methyldiethanolamine, dimethylethanolamine, hydroxypropylamine, triisopropanolamine, hydroxybutylamine etc. Ammonia, trimethylamine, monoethanolamine, diethanolamine, and triethanolamine from the viewpoint of the properties and physical properties of the composite resin Is preferably at least one selected from the emissions, more preferably ammonia.

  The degree of neutralization by the neutralizing agent N in the copolymer A is preferably 50 mol% or more, more preferably 60 with respect to the total amount of acidic groups of the copolymer A, from the viewpoint of dispersibility and physical properties of the composite resin. Mole% or more, more preferably 70 mole% or more, more preferably 80 mole% or more, still more preferably 90 mole% or more, still more preferably substantially 100 mole%, and not more than 100 mole%, and Even more preferably, it is 100 mol%.

  In the present disclosure, the acid group of the copolymer A is a concept including an acid group before neutralization and an acid group after neutralization. In the present disclosure, constituent units derived from anhydrides of unsaturated dibasic acids are considered to have two acidic groups per said constituent unit.

  When the compound represented by the formula (I) is present in excess with respect to the total amount of acidic groups of the copolymer A when producing the dispersant of the present disclosure, all of the copolymer A The degree of neutralization by the neutralizing agent N in the copolymer A in this case is substantially 100% by mole, since the acid group of is considered to be neutralized.

  The copolymer A may be neutralized with an alkali compound other than the neutralizing agent N (hereinafter also referred to as “other neutralizing agent”) to the extent that the dispersibility and the performance of the composite resin are not impaired.

  An alkaline compound other than the neutralizing agent N is a compound which exhibits alkalinity when added to water, and is a compound other than the compound represented by the formula (I). Examples of the alkali compound include alkali metal hydroxides and alkaline earth metal hydroxides, and at least one member selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide and calcium hydroxide. Is preferred.

  The degree of neutralization by the other neutralizing agent in the copolymer A is preferably less than 50 mol%, more preferably 20, with respect to the total amount of acidic groups of the copolymer A from the viewpoint of dispersibility and coprecipitation. It is at most mol%, more preferably at most 15 mol%, further preferably at most 10 mol%, even more preferably substantially 0 mol%.

  The form of the dispersing agent may be the copolymer A itself or may contain a solvent or the like, and from the viewpoint of suppressing the volatilization of the neutralizing agent N, a state of being dissolved in an aqueous medium is preferable. The solid content of the dispersant is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, from the viewpoint of efficiently expressing the dispersibility and the performance of the composite resin. From the viewpoint of suppressing the volatilization of the agent N, 60 mass% or less is preferable, 50 mass% or less is more preferable, and 40 mass% or less is more preferable. The method of measuring the solid content of the dispersant is as described in the examples.

  As a method of synthesizing a copolymer (hereinafter, also referred to as "polymerization product") before being neutralized by the neutralizing agent N, a radical polymerization method is preferable, and it is more preferable to carry out by the following solution polymerization method .

  In the solution polymerization method, while heating and stirring a liquid containing a solvent, a monomer mixture, and, if necessary, a component such as a polymerization initiator, a mixture of a polymerization initiator and, if necessary, a monomer is added dropwise to the liquid. It polymerizes.

  As a polymerization initiator used in the polymerization, known radical polymerization initiators can be used. For example, azo polymerization initiators, hydroperoxides, dialkyl peroxides, diacyl peroxides, ketones Peroxides, inorganic peroxides and the like can be mentioned.

  The amount of the polymerization initiator to be used is preferably 0.01 mol% or more, preferably 5 mol% or less, more preferably 3 mol% or less, more preferably 100 mol%, based on the total monomer amount. It is 1 mol% or less.

  The polymerization reaction is preferably carried out under a nitrogen atmosphere. The polymerization reaction temperature is preferably 30 ° C. or more and 180 ° C. or less. The polymerization reaction time is preferably 0.5 hours or more and 20 hours or less.

  In the polymerization, a polymerization chain transfer agent may be further used. As a polymerization chain transfer agent, mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan, mercaptoethanol, 3-mercapto-1,2-propanediol, mercaptopropionic acid, mercaptosuccinic acid and the like And thiuram disulfides; unsaturated heterocyclic compounds, etc., which may be used alone or in combination of two or more.

  The solvent used for the polymerization may be an aqueous medium or a medium other than the aqueous medium. As media other than aqueous media, aromatics such as toluene and xylene; alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and diethylene glycol dimethyl ether; and aliphatics such as hexane, cyclohexane and mineral oil A hydrocarbon etc. are mentioned. In the polymerization, it is more preferable to use the branched α-olefin which is the monomer (a) in excess and use it as a solvent, from the viewpoint of easiness of production of a polymerization product. Such a solvent is preferably a branched α-olefin having 6 to 10 carbon atoms, more preferably α-diisobutylene. The amount of the solvent used is preferably 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the total amount of monomers.

  When the solvent used for polymerization is not an aqueous medium, it is preferable to carry out solvent substitution or solvent removal after polymerization. In addition, even when an aqueous medium is used, solvent substitution or solvent removal may be performed for the purpose of purification or change of medium composition. The method of solvent substitution and solvent removal is generally a method of distilling off the solvent by heating, reduced pressure or the like, or dropping the solution after polymerization to a poor solvent of the copolymer to recover the precipitate.

  The weight average molecular weight of the polymerization product is preferably 2000 or more, more preferably 3000 or more, still more preferably 5000 or more, still more preferably 8000 or more, from the viewpoint of dispersibility and performance improvement of the composite resin. From the same viewpoint, 300000 or less is preferable, 100000 or less is more preferable, 70000 or less is more preferable, 50000 or less is more preferable, 30000 or less is more preferable. The method of measuring the weight average molecular weight is as described in the examples.

  In the present disclosure, the copolymer A used as a dispersant is preferably obtained through a neutralization step of neutralizing the polymerization product with a neutralizing agent N.

  When the neutralizing agent N used in the neutralization step is ammonia, at least one selected from liquid ammonia, ammonia water, and ammonia gas can be used, and from the viewpoint of workability, ammonia water is used. Is preferred.

  The amount of neutralizing agent N used in the neutralization step is preferably 50 mol% or more, 80 mol% or more, from the viewpoint of improving the dispersibility and the performance of the composite resin with respect to the total amount of acidic groups in the polymerization product. Is more preferably 100 mol% or more, and from the same viewpoint, 200 mol% or less is preferable, 150 mol% or less is more preferable, and 120 mol% or less is more preferable.

  The degree of neutralization of the copolymer A is determined by adding the amount of the neutralizing agent N used in the neutralization step in excess of the amount corresponding to the desired degree of neutralization, and then adding the excess neutralizing agent N. Adjustment can be carried out by distilling off the solution under reduced pressure or heating, or by adding an acid to precipitate a salt and removing it out of the system.

  The amount of the other neutralizing agent used in the neutralization step is preferably 33, based on the total amount of the neutralizing agent N and the other neutralizing agent, from the viewpoint of dispersibility and coprecipitation (flocculation). It is less than mol%, more preferably not more than 20 mol%, still more preferably not more than 15 mol%, still more preferably not more than 10 mol%, still more preferably substantially 0 mol%.

  The neutralization method in the neutralization step is preferably a method of adding a neutralizing agent while stirring a mixture containing an unneutralized polymerization product and an aqueous medium from the viewpoint of easiness of production, and a method of dropping is preferred. More preferable. The time for dripping is preferably 0.5 hours or more from the viewpoint of suppressing the aggregation of the unneutralized product of the polymerization product and the adhesion to the reaction tank, and from the viewpoint of efficient production, 3 hours or less is preferable.

  The temperature of the neutralization reaction in the neutralization step is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, from the viewpoint of uniformly advancing the neutralization reaction and the improvement of the neutralization reaction rate, and a solvent such as water From the viewpoint of suppressing evaporation of the solvent and volatilization of the neutralizing agent N, 90 ° C. or less is preferable, 85 ° C. or less is more preferable, and 80 ° C. or less is more preferable.

  The content of the copolymer A contained in the dispersion liquid of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably from the viewpoint of the dispersibility and the performance improvement of the composite resin. Is at least 0.5% by mass, more preferably at least 1% by mass, and from the viewpoint of handling of the dispersion, preferably at most 10% by mass, more preferably at most 5% by mass, still more preferably 3% % Or less.

  The content of the copolymer A with respect to 100 parts by mass of the carbon black contained in the dispersion of the present disclosure is preferably 0.2 parts by mass or more, more preferably 1 part by mass from the viewpoint of dispersibility and performance improvement of the composite resin. The amount is more preferably 2 parts by mass or more, and preferably 100 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less from the same viewpoint.

[Aqueous medium]
The aqueous medium contained in the dispersion of the present disclosure may contain an organic solvent which is uniformly miscible in water. From the viewpoint of dispersibility and coprecipitation, the content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, more preferably substantially 100 % By weight, and up to 100% by weight, and even more preferably 100% by weight.

  Examples of the organic solvent which is uniformly mixed with water include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, 2-butanone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, ethylene glycol, diethylene glycol, glycerin, N -Methyl pyrrolidone, or 2-pyrrolidone etc. is mentioned, Preferably it is at least 1 sort (s) chosen from ethanol, 2-propanol, acetone, 2-butanone, and N- methyl pyrrolidone.

  The content of the aqueous medium contained in the dispersion of the present disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, from the viewpoint of dispersibility and coprecipitation. More preferably, it is 80% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, and still more preferably 95% by mass or less.

[Flocculation promoter]
The dispersion of the present disclosure may optionally contain an aggregation promoter. The cohesion promoter is a substance capable of compensating for the cohesion of the carbon black dispersion.

  The aggregation promoter is preferably a polycarboxylic acid compound and a salt thereof from the viewpoint of dispersibility and aggregation, and one or more selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid Polymeric compounds obtained by polymerizing two or more kinds of monomers and salts thereof are more preferable, and at least one selected from polyacrylic acid, polymethacrylic acid and acrylic acid-maleic acid copolymer and salts thereof are more preferable.

  The weight average molecular weight of the polycarboxylic acid compound and the salt thereof is preferably 3000 or more, more preferably 5000 or more, still more preferably 10000 or more, from the viewpoint of aggregation (coprecipitability), and from the viewpoint of workability. One million or less is preferable, 500,000 is more preferable, and 300,000 or less is more preferable. The weight average molecular weight of the polycarboxylic acid compound and its salt can be measured by the same method as the above-mentioned polymerization product.

  In the polycarboxylic acid compound, some or all of the acidic groups may be neutralized by the neutralizing agent N, or may be mixed with the polymerization product and neutralized simultaneously with the polymerization product. You may mix with a carbon black dispersion liquid in the state neutralized beforehand. It may be neutralized with other neutralizing agents to the extent that the dispersibility or coprecipitation property is not impaired.

  The content of the aggregation promoter in the dispersion of the present disclosure is 0 parts by mass or more, and preferably 100 parts by mass or less, with respect to 100 parts by mass of the copolymer A, from the viewpoint of dispersibility and coprecipitation. 50 parts by mass or less is more preferable, and 20 parts by mass or less is more preferable.

[Other ingredients]
The dispersion of the present disclosure may optionally contain other components other than carbon black, a dispersant, an aqueous medium, and an aggregation promoter. As other components, inorganic fillers other than carbon black, active materials, viscosity modifiers, preservatives and the like can be mentioned.

  The inorganic filler may be any one that does not impair the dispersibility and the performance of the composite resin, and examples thereof include silica, mica, metal oxides, metal halides, and carbon materials other than the carbon black.

  Examples of the active material include lithium metal oxide containing cobalt, nickel, manganese, iron and the like, manganese oxide and the like.

[Method of producing carbon black dispersion]
The dispersion of the present disclosure is produced through a dispersion step of mixing and dispersing at least a carbon black, a dispersant containing the copolymer A, and an aqueous medium.

  In the dispersing step, a dispersing machine is used. As a dispersing machine, any dispersing machine capable of giving shear energy capable of breaking up powdery carbon black into a secondary cohesive structure called a structure can be used. Specifically, a roll mill, a kneader, an extruder, etc. A kneader, a disper, a homomixer, a jet mill, a sand mill, a bead mill, a high pressure homogenizer, an ultrasonic homogenizer, etc. may be mentioned.

  The aggregation promoter added as necessary may be added before the dispersing step, but is preferably added after the dispersing step from the viewpoint of dispersibility.

  The order of mixing of each component is, for example, a method in which carbon black, a dispersant and an aqueous medium are mixed together, and a method in which a dispersant is gradually added to a mixture of carbon black and an aqueous medium. The method of adding carbon black after mixing, the method of adding the liquid mixture of a dispersing agent and an aqueous medium to carbon black, etc. are mentioned.

[Carbon black composite resin]
The composite resin of the present disclosure is obtained by a manufacturing method including the following steps (1) to (3).
(1) A step of mixing the dispersion of the present disclosure with an aqueous resin emulsion to obtain a mixed solution.
(2) A step of adding an acid to the mixed solution to form a coprecipitate of carbon black and a resin.
(3) A step of drying the coprecipitate.

  As a mixing method in the step (1), any known mixing method can be used as long as it can mix the dispersion of the present disclosure and an aqueous resin emulsion. Examples of the resin in the aqueous resin emulsion include acrylic resins, urethane resins, SBR resins, natural resins and the like.

  In the step (2), an acid is added to the mixed solution obtained in the step (1) to preferably make the pH of the mixed solution 4 or less to generate the coprecipitate.

  As the drying method in the step (3), known drying methods can be used as long as the coprecipitate can be dried.

  The dispersion state of carbon black contained in the composite resin of the present disclosure is preferably substantially uniform or uniform from the viewpoint of improving the performance of the composite resin. The dispersed state of carbon black can be determined based on the variation in the volume specific resistance value and the variation in the degree of blackness (color unevenness).

  Hereinafter, the present invention will be described by way of examples. First, methods for measuring the weight average molecular weight, copolymerization ratio, solid content, and average primary particle size are shown below.

[Weight average molecular weight]
The weight average molecular weight of the polymerization product was measured by GPC (gel permeation chromatography) under the following conditions. The weight average molecular weight was calculated based on a calibration curve prepared in advance. The following standard samples were used for preparation of a calibration curve.
Measuring device: HLC-8120GPC (made by Tosoh Corporation)
Column: TSK α-M (made by Tosoh Corporation) x 2 columns Column temperature: 40 ° C
Detector: RI
Eluent: H ₃ PO ₄ (60 mmol / L) and LiBr (50 mmol / L) added N, N-dimethylformamide solution eluent Flow rate: 1.0 mL / min
Sample concentration: 0.1 mass% (solid content)
Sample injection volume: 0.1 mL
Standard sample: monodispersed polystyrene (manufactured by Tosoh Corporation: molecular weight 5.26 × 10 ² , molecular weight 1.02 × 10 ⁵ , molecular weight 8.42 × 10 ⁶ ; manufactured by Nishio Kogyo Co., Ltd .: molecular weight 4.0 × 10 ³ , molecular weight 3 .0 × 10 ⁴ , molecular weight 9.0 × 10 ⁵ )

[Copolymerization ratio]
The copolymerization ratio of the structural unit (a) and the structural unit (b) constituting the polymerization product was calculated from the integral value of 1 H-NMR. Specifically, first, 200 mg of a sample was dissolved in 2 mL of heavy chloroform, injected into a sample tube for NMR with a diameter of 5 mm, and measured with a 1 H-NMR measurement apparatus (“MR-400” manufactured by Agilent Technologies). Then, the copolymerization ratio was determined from the peak integral value derived from the structural unit (a) and the peak integral value derived from the structural unit (b) in the 1 H-NMR spectrum.

[Solid content]
The solid content was measured by the following method. The sample: 1 g was taken in a petri dish with a mass of W ₃ (g), and the mass of the whole petri dish containing the sample was measured to obtain W ₁ (g). The whole petri dish is dried in a vacuum dryer at 105 ° C. for 24 hours and further allowed to cool for 30 minutes in a desiccator, and then the mass of the whole petri dish containing non-volatile matter of the sample is measured to obtain W ₂ (g) did. The value obtained by the following formula was taken as the solid content.
Solids _{(wt%) = 100- (W 1 -W} 2) / (W 1 -W 3) × 100

[Average primary particle size]
The measurement of the average primary particle size of carbon black is carried out by photographing the carbon black powder at 5 to 100,000 times using a transmission electron microscope, enlarging the photograph, and measuring the particle size of 100 particles. The average value was determined as the average primary particle diameter of carbon black.

  The following method was used to evaluate the dispersibility and dispersion stability of the carbon black dispersion, and the performance of the conductive carbon black composite resin and the carbon black composite resin for coloring.

[Dispersibility of carbon black dispersion]
The evaluation of the dispersibility was performed based on the value of the dispersed particle diameter of the carbon black dispersion. The dispersed particle size was measured by diluting with deionized water so that the concentration of carbon black was about 0.05% by mass, using Zetasizer Nano manufactured by Marvern Instruments, and using Refractive Index 1.8, Absorption 10 as [Material]. , And [Dispersion] was performed by selecting Water and injecting into a designated 12 mm square glass cell. The smaller the dispersed particle size, the better the dispersibility.

[Dispersion stability of carbon black dispersion]
30 mL of the carbon black dispersion immediately after preparation was collected in a 50 mL glass sample bottle and allowed to stand at room temperature for 1 hour. The presence or absence of the sediment after standing and the upper layer of the dispersion liquid were visually evaluated and evaluated as follows.
Evaluation A: Sediment is not confirmed.
Evaluation B: Sediment is confirmed but the upper layer is opaque.
Evaluation C: Sediment is confirmed, and the upper layer is transparent.

[Performance of conductive carbon black composite resin]
The performance of the conductive carbon black composite resin was evaluated based on the coprecipitation property, the volume specific resistance value, and the dispersion state of carbon black. Each evaluation method will be described below.

(1) Co-precipitation (cohesive)
The coprecipitation property was evaluated by visually observing the coprecipitate and the upper layer (supernatant) obtained by adding the acid to the mixture of the carbon black dispersion and the aqueous resin emulsion. That is, in each example, 2N hydrochloric acid was added to the mixture of the carbon black dispersion and the aqueous resin emulsion until the pH became 3 or less, and then the solution was allowed to stand at room temperature for 1 hour to observe the following criteria Based on, coprecipitability was evaluated.
Evaluation A: The upper layer is transparent and the color of the sediment is uniform black.
Evaluation B: The upper layer is opaque and the color of the sediment is uniform black.
Evaluation C: Upper layer is opaque and gray sediment is observed.

(2) Volume Resistivity The volume resistivity was measured as follows. First, the recovered precipitate was coated on a glass plate with a rubber blanket to a thickness of about 1 mm, and dried at 105 ° C. for 24 hours with a vacuum dryer to obtain a composite resin for measurement. Using the obtained composite resin for measurement as a sample, connect an ASP probe to "Roresta GP MCP-T610" manufactured by Mitsubishi Analytech Co., Ltd., enter the sample thickness measured with a micrometer, and enter JIS K 7194 "4 of conductive plastic" Measure the resistance value at 10 points by the 4 terminal 4 probe method according to “Low resistance test method by probe method”, and use the common logarithm value (unit: Log Ω · cm) of the average value as the volume specific resistance value did. The smaller the volume specific resistance value, the better the conductivity. In the present embodiment, the volume specific resistance value (unit: Log Ω · cm) is preferably 4.8 or less, more preferably 3.6 or less, still more preferably 2.6 or less, still more preferably 2.5 or less. .

(3) Dispersion State The dispersion state of carbon black contained in the composite resin was evaluated as follows based on the dispersion of the volume specific resistance value. That is, it evaluated by the following references | standards by the presence or absence of the measurement location where 10 volume specific resistance values (unit: Log ohm * cm) mentioned above exceed 7.0.
Evaluation A: There are no measurement points exceeding 7.0 (Log Ω · cm).
Evaluation B: There is one or more measurement points exceeding 7.0 (Log Ω · cm).

[Performance of colored carbon black composite resin]
The performance of the colorable carbon black composite resin was evaluated based on the degree of blackness and the dispersion state of carbon black. Each evaluation method will be described below.

(1) Blackness The evaluation method of blackness was performed as follows. First, the recovered precipitate was coated on a glass plate with a rubber blanket to a thickness of about 1 mm, and dried at 105 ° C. for 24 hours with a vacuum dryer to obtain a composite resin for measurement. The obtained composite resin for measurement was used as a sample, and L * values at 10 points were measured using "Color Touch PC" manufactured by Technidylne, and the average value was defined as L * ave. The smaller the L * ave value, the better the blackness. In the present embodiment, the value of L * ave is preferably 23 or less, more preferably 21 or less.

(2) Dispersion State The dispersion state of carbon black contained in the composite resin was evaluated as follows by visually confirming the presence or absence of black shades (color unevenness) derived from carbon black on the surface of the composite resin.
Evaluation A: When the surface of the composite resin is uniform black and no shading (uneven color) is confirmed, it is judged that the dispersion state of carbon black in the composite resin is uniform.
Evaluation B: When the surface of the composite resin is not uniform black and shades (color unevenness) are confirmed, it is judged that the dispersion state of carbon black in the composite resin is nonuniform.

  Next, dispersants used in Examples and Comparative Examples will be described.

[Production Example 1: Production of Dispersant A1]
In a glass reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen introduction pipe, and a dropping funnel, diisobutylene (manufactured by Maruzen Petrochemical Co., Ltd.): 621.8 g and Rutonal A-50 (manufactured by BASF, polyvinyl ethyl) Ether): Charged 3.1 g. The inside of the reaction vessel was changed to a nitrogen atmosphere and stirring was started. The reaction vessel contents were heated to 105 ° C., and the temperature of the reaction vessel contents was then maintained at 105 ° C. until the polymerization reaction was complete. 190.0 g of molten maleic anhydride (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.) kept at 70 ° C., and 23.1 g of diisobutylene, perbutyl O (manufactured by NOF Corporation, t-butylperoxy-2-ethylhexa) Nooate): An initiator solution obtained by dissolving 10.3 g was dropped from the respective dropping funnels into the reaction vessel over 4 hours. After 20 minutes from the end of the dropwise addition, 1.2 g of perbutyl O dissolved in 7.3 g of diisobutylene is added into the reaction vessel, and aging is further carried out for 2 hours and 40 minutes to complete the polymerization reaction, and the polymerization product P1 To give a solution containing In a reaction vessel, 800 g of ion exchanged water was added to precipitate a precipitate of a polymerization product P1 of the structural unit (a) derived from diisobutylene and the structural unit (b) derived from maleic anhydride. The unreacted diisobutylene was then distilled off by steam distillation. The steam distillation was performed by heating the reaction vessel at normal pressure until the temperature of the contents of the reaction vessel reached 100 ° C. and distillation of diisobutylene ceased. After water was removed by decantation, the precipitate of the polymerization product P1 wetted with water was dried at 105 ° C. under a reduced pressure of 100 mmHg for 24 hours to obtain a polymerization product P1. The copolymerization ratio of the obtained polymerization product P1 was diisobutylene / maleic anhydride = 50 mol% / 50 mol%, and the weight average molecular weight of the polymerization product P1 was 25,000.

  Next, 100 g of the polymerization product P1 and 100 g of water were charged into a reaction vessel, and while stirring, the contents of the reaction vessel were brought to 75 ° C., and the neutralization step shown below was performed. The temperature of the liquid in the reaction vessel was maintained at 75 ° C. until the neutralization reaction was complete. In the neutralization step, first, 3.3 g of a 25% by mass aqueous ammonia solution (manufactured by Showa Denko KK): 3.3 g was added to the reaction vessel and held for 15 minutes. Subsequently, 64.7 g of 25% by mass aqueous ammonia solution was dropped into the reaction vessel over 1 hour to complete the neutralization reaction. And, in order to volatilize excess ammonia, after maintaining for 3 hours under the condition of reduced pressure: -40 cmHg, return to normal pressure and cool to room temperature, and ion exchange water so that solid content becomes 25 mass% In addition, it was kept for 30 minutes and then the stirring was stopped. Thus, an aqueous solution (dispersant A1) containing 25% by mass of a copolymer A1 obtained by neutralizing the polymerization product P1 with ammonia was obtained.

[Production Example 2: Production of Dispersant A2]
A structural unit derived from diisobutylene is prepared in the same manner as in Production Example 1 except that an initiator solution obtained by dissolving 13.5 g of perbutyl O in 23.1 g of diisobutylene is used as an initiator solution. A polymerization product P2 of (a) and a structural unit (b) derived from maleic anhydride was obtained. The copolymerization ratio of the obtained polymerization product P2 was diisobutylene / maleic anhydride = 50 mol% / 50 mol%, and the weight average molecular weight of the polymerization product P2 was 12000.

  Then, the neutralization process similar to the said manufacture example 1 was performed, the aqueous solution (dispersant A2) which contains 25 mass% of copolymers A2 obtained by neutralizing the polymerization product P2 with ammonia was obtained.

[Production Example 3: Production of Dispersant A3]
A structural unit derived from diisobutylene is prepared in the same manner as in Production Example 1 except that an initiator solution obtained by dissolving 2.6 g of perbutyl O in 23.1 g of diisobutylene is used as the initiator solution. A polymerization product P3 of (a) and a structural unit (b) derived from maleic anhydride was obtained. The copolymerization ratio of the obtained polymerization product P3 was diisobutylene / maleic anhydride = 50 mol% / 50 mol%, and the weight average molecular weight of the polymerization product P3 was 97,000.

  Then, the neutralization process similar to the said manufacture example 1 was performed, the aqueous solution (dispersant A3) containing 25 mass% of copolymers A3 obtained by neutralizing the polymerization product P3 with ammonia was obtained.

Production Example 4: Production of Dispersant A4
The same as in Production Example 1 except that Isoban 04 (manufactured by Kuraray, isobutylene-maleic anhydride copolymer, weight average molecular weight: 55000 to 65000) was used instead of the polymerization product P1 of Production Example 1 above. Thus, an aqueous solution (dispersant A4) containing 25% by mass of a copolymer A4 obtained by neutralizing isoban 04 with ammonia was obtained.

[Production Example 5: Production of Dispersant A5]
Instead of the polymerization product P1 of Production Example 1 above, a polymerization product of 1-octadecene and maleic anhydride (Wako Pure Chemical Industries, Ltd., weight average molecular weight: 30,000 to 50,000, copolymerization ratio: 1-octadecene / anhydride A copolymer A5 obtained by neutralizing the polymerization product of 1-octadecene and maleic anhydride with ammonia in the same manner as in Production Example 1 except that maleic acid = 1: 1) was used. An aqueous solution (dispersant A5) containing mass% was obtained.

Production Example 6: Production of Dispersant A6
100 g of the polymerization product P1 obtained in the above Production Example 1 and 100 g of water were charged in a reaction vessel, and while stirring, the contents of the reaction vessel were brought to 75 ° C., and the neutralization step shown below was performed. The temperature of the liquid in the reaction vessel was maintained at 75 ° C. until the neutralization reaction was complete. First, 249 mL of a 4 N aqueous solution of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped into the reaction vessel over 1.5 hours, and the stirring was further continued for 3 hours to complete the neutralization reaction. It cooled to room temperature, ion-exchange water was added so that solid content might be 25 mass%, stirring was stopped after hold | maintaining for 30 minutes. Thus, an aqueous solution (dispersant A6) containing 25% by mass of a copolymer A6 obtained by neutralizing the polymerization product P1 with sodium hydroxide was obtained.

Preparation Example 7 Preparation of Dispersant A7
A polymerization product P1 was prepared according to Production Example 6 except that 4N aqueous potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 4N aqueous sodium hydroxide solution of Production Example 6 as the neutralizing agent. Thus, an aqueous solution (dispersant A7) containing 25% by mass of copolymer A7 obtained by neutralizing with potassium hydroxide was obtained.

Production Example 8 Production of Aqueous Resin Emulsion
In a reaction vessel equipped with a stirrer, a dropping tank and a thermometer, 300 g of water, 6 g of ammonium lauryl sulfate and 10 g of N-methylol acrylamide were charged and mixed. Thereafter, while blowing nitrogen gas into the reaction vessel, the temperature of the reaction vessel contents is raised to 75 ° C., and styrene: 146 g, methyl methacrylate: 90 g, acrylic acid: 4 g, and 2 mass% ammonium persulfate aqueous solution: 25 g The mixture was added dropwise over 2 hours. Then, the polymerization is terminated by holding at 85 ° C. for 2 hours, ammonia water is added to neutralize to pH 7.5, and an acrylic resin emulsion R1 having a dispersed particle diameter: 0.1 μm, solid content concentration: 40 mass% is obtained. The The dispersed particle size is determined by the same measurement method as the dispersed particle size of the carbon black dispersion.

  Next, the carbon black dispersion liquid and carbon black composite resin of an Example and a comparative example are demonstrated.

Example 1
Carbon black (conductive carbon black, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Denka black FX-35", average primary particle diameter: 23 nm, BET specific surface area: in 100 mL of poly wide-mouthed bottle (manufactured by Nikko Hansen) 133 m ² / g, surface acidic group content: <0.1 μeq / m ² , pH: 9): 4 g, Dispersant A 1: 1.6 g, and ion exchange water as an aqueous medium to a total amount of 40 g Further, 80 g of zirconia beads (Nikkato Co., Ltd.) having a diameter of 0.3 mm was charged, and the container was sealed, followed by dispersing for 3 hours with a paint shaker (manufactured by Asada Iron Works Co., Ltd.) to obtain a paste. The dispersion of Example 1 was obtained by removing the zirconia beads from the obtained paste using a 100 mesh stainless steel wire mesh. The dispersed particle size was 207 nm.

  20 g of the dispersion of Example 1 and 10 g of the acrylic resin emulsion R1 obtained in Preparation Example 8 are put in a 50 mL screw tube (manufactured by Marem Co.), and the dispersion of Example 1 and acrylic are stirred while being stirred by a magnetic stirrer. 2N hydrochloric acid was added dropwise to the mixture with the resin emulsion R1 until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when left for 1 hour, the upper layer became transparent, and a uniform black sediment (coprecipitate) was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Example 1. The volume resistivity of this composite resin was 2.5 (Log Ω · cm), and no variation in the resistance was observed.

(Example 2)
A dispersion of Example 2 was obtained in the same manner as in Example 1 except that the dispersing agent A2 was used instead of the dispersing agent A1. The dispersed particle size was 199 nm.

  A mixed solution of the dispersion of Example 2 and the acrylic resin emulsion R1 of Production Example 8 was prepared in the same manner as Example 1, and 2N hydrochloric acid was dropped to the mixed solution until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when it was allowed to stand for 1 hour, the upper layer became transparent and a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Example 2. The volume resistivity of this composite resin was 2.4 (Log Ω · cm), and no variation in the resistance value was observed.

(Example 3)
A dispersion of Example 3 was obtained in the same manner as in Example 1 except that the dispersant A3 was used instead of the dispersant A1. The dispersed particle size was 231 nm.

  A liquid mixture of the dispersion of Example 3 and the acrylic resin emulsion R1 of Production Example 8 was prepared in the same manner as in Example 1, and 2N hydrochloric acid was dropped to the liquid mixture until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when it was allowed to stand for 1 hour, the upper layer became transparent and a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Example 3. The volume resistivity of this composite resin was 2.8 (Log Ω · cm), and no variation in the resistance value was observed.

(Example 4)
A dispersion of Example 4 was obtained in the same manner as in Example 1 except that the dispersing agent A4 was used instead of the dispersing agent A1. The dispersed particle size was 442 nm,

  A mixed solution of the dispersion of Example 4 and the acrylic resin emulsion R1 of Production Example 8 was prepared in the same manner as Example 1, and 2N hydrochloric acid was added dropwise to the mixed solution until the pH became 3 or less. Stirring was stopped after the addition was completed, and when left for 1 hour, the upper layer remained opaque, but a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Example 4. The volume resistivity of this composite resin was 3.5 (Log Ω · cm), and no variation in the resistance value was observed.

(Example 5)
20 g of the dispersion of Example 1 and a 1% by mass aqueous solution of poly (acrylic acid) ammonium salt (manufactured by Wako Pure Chemical Industries, molecular weight: 250,000) as a cohesion accelerator: 5 g with 50 mL screw tube (manufactured by Marem Co.) The mixture was stirred for 30 minutes with a magnetic stirrer to obtain a dispersion of Example 5. The dispersed particle size was 253 nm.

  The dispersion liquid of Example 5: 20 g of the acrylic resin emulsion R1 of Preparation Example 8 and 8 g of the acrylic resin emulsion R of Production Example 8 are put in a 50 mL screw tube (manufactured by Marem Co.) and the dispersion liquid of Example 5 and the acrylic resin emulsion are stirred while being stirred by a magnetic stirrer. 2N hydrochloric acid was added dropwise to the mixture with R1 until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when left for 1 hour, the upper layer became transparent, and a uniform black sediment (coprecipitate) was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Example 5. The volume resistivity of this composite resin was 2.6 (Log Ω · cm), and no variation in the resistance value was observed.

(Example 6)
As a “dispersant”, an example except that a mixture of dispersant A1 and dispersant A6 was used such that the degree of neutralization by ammonia was 90 mol% and the degree of neutralization by sodium hydroxide was 10 mol% In the same manner as in 1, a dispersion of Example 6 was obtained. The dispersed particle size was 215 nm.

  20 g of the dispersion of Example 6 and 8 g of the acrylic resin emulsion R of Preparation Example 8 are placed in a 50 mL screw tube (manufactured by Marem Co.), and the dispersion of Example 6 and the acrylic resin emulsion are stirred with a magnetic stirrer. 2N hydrochloric acid was added dropwise to the mixture with R1 until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when left for 1 hour, the upper layer became transparent, and a uniform black sediment (coprecipitate) was formed. The upper layer liquid was removed, and the lower layer sediment was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Example 6. The volume resistivity of this composite resin was 2.6 (Log Ω · cm), and no variation in the resistance value was observed.

(Example 7)
As a “dispersant”, an example except that a mixture of dispersant A1 and dispersant A6 was used such that the degree of neutralization by ammonia was 70 mol% and the degree of neutralization by sodium hydroxide was 30 mol% In the same manner as in 1, a dispersion of Example 7 was obtained. The dispersed particle size was 211 nm.

  The dispersion of Example 7: 20 g of the dispersion of Example 7 and 8 g of the acrylic resin emulsion R of Preparation Example 8 are placed in a 50 mL screw tube (manufactured by Marem Co.) and the dispersion of Example 7 and the acrylic resin emulsion are stirred with a magnetic stirrer. 2N hydrochloric acid was added dropwise to the mixture with R1 until the pH became 3 or less. Stirring was stopped after the addition was completed, and when it was allowed to stand for 1 hour, the upper layer remained opaque, but a uniform black precipitate (co-precipitate) was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Example 7. The volume resistivity of this composite resin was 4.0 (Log Ω · cm), and no variation in the resistance value was observed.

(Comparative example 1)
A dispersion of Comparative Example 1 was obtained in the same manner as in Example 1 except that Dispersant A5 was used instead of Dispersant A1. The dispersion of Comparative Example 1 has a dispersion particle size of 1120 nm and is poor in dispersibility, and after standing for 1 hour, the dispersion stability is also poor in a separated state in which the transparent aqueous layer is on the upper layer and the sediment is also on the bottom. The Therefore, the composite resin could not be produced.

(Comparative example 2)
A dispersion of Comparative Example 2 was obtained in the same manner as in Example 1 except that Dispersant A6 was used instead of Dispersant A1. The dispersed particle size was 210 nm.

  A mixed solution of the dispersion of Comparative Example 2 and the acrylic resin emulsion R1 of Production Example 8 was prepared in the same manner as Example 1, and 2N hydrochloric acid was dropped to the mixed solution until the pH became 3 or less. Stirring was stopped after the addition was completed, and left to stand for 1 hour, the upper layer remained opaque and gray sediment was observed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Comparative Example 2. The volume resistivity of this composite resin was 6.0 (Log Ω · cm), and variations in the resistance value were observed.

(Comparative example 3)
A dispersion of Comparative Example 3 was obtained in the same manner as in Example 1 except that the dispersant A7 was used instead of the dispersant A1. The dispersed particle size was 210 nm.

  A mixed solution of the dispersion of Comparative Example 3 and the acrylic resin emulsion of Preparation Example 8 was prepared in the same manner as Example 1, and 2N hydrochloric acid was added dropwise to the mixed solution until the pH became 3 or less. Stirring was stopped after the addition was completed, and left to stand for 1 hour, the upper layer remained opaque and gray sediment was observed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Comparative Example 3. The volume resistivity of this composite resin was 6.4 (Log Ω · cm), and variations in the resistance value were observed.

(Example 8)
In a 2 L stainless beaker, furnace black (coloring carbon black, manufactured by Cabot, trade name “Monarch 880”, average primary particle diameter 16 nm, BET specific surface area 220 m ² / g, surface acidic group content: 0.4 μeq / m ² , pH) : 8.5): 80 g, Dispersant A 1: 64 g, and ion-exchanged water as an aqueous medium to a total amount of 640 g, and after preliminary dispersion with a disper, a microfluidizer (manufactured by Microfluidics, high-pressure homogenizer) And 10 passes dispersion treatment under a trade name "M-110" at a pressure of 200 MPa.

  The total amount of the obtained solution is filtered using a syringe filter with a pore diameter of 5 microns, and the solid content is adjusted to 12% by mass (10% by mass as carbon black content) with ion-exchanged water, and an example of dispersed particle diameter 146 nm A dispersion of 8 was obtained. The dispersed particle size was 146 nm.

  The dispersion of Example 8: 2 g of an acrylic resin emulsion R1: 25 g are placed in a 50 mL screw tube (manufactured by Marem Co.) and mixed with the dispersion of Example 8 and an acrylic resin emulsion R1 while stirring with a magnetic stirrer. And 2N hydrochloric acid was added dropwise to the mixture until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when it was allowed to stand for 1 hour, the upper layer became transparent and a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a carbon black composite resin. No color unevenness (variation) was observed at a degree of blackness (L * value) of 21.

(Comparative example 4)
A dispersion of Comparative Example 4 was obtained in the same manner as in Example 8 except that the dispersant A6 was used instead of the dispersant A1. The dispersed particle size was 159 nm.

  A mixed solution of the dispersion of Comparative Example 4 and the acrylic resin emulsion R1 of Production Example 8 was prepared in the same manner as in Example 8, and 2N hydrochloric acid was added dropwise to the mixed solution until the pH became 3 or less. Stirring was stopped after the addition was completed, and left to stand for 1 hour, the upper layer remained opaque and gray sediment was observed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Comparative Example 4. Unevenness (variation) was observed at a degree of blackness (L * value) 27.

(Reference Example 1)
In a 2 L stainless beaker, furnace black (coloring carbon black, "Blackpearls 160" manufactured by Cabot, average primary particle size: 50 nm, BET specific surface area: 35 m ² / g, surface acidic group content: 0.4 μeq / m ² , pH: 8.5): 80 g, Dispersant A 1: 32 g, and ion-exchanged water as an aqueous medium are prepared to a total amount of 640 g, and after preliminary dispersion with a disper, a microfluidizer (high pressure homogenizer "M-110 manufactured by Microfluidics" 10) dispersion treatment at a pressure of 200 MPa.

  The total amount of the obtained solution was filtered using a syringe filter with a pore diameter of 5 microns, and the solid content was adjusted to 11% by mass (10% by mass as carbon black content) with ion-exchanged water, and the dispersion of Reference Example 1 was obtained. Obtained. The dispersed particle size was 120 nm.

  2 g of the dispersion of Reference Example 1 and 25 g of the acrylic resin emulsion R of Production Example 8 are placed in a 50 mL screw tube (manufactured by Marem Co.), and 2N hydrochloric acid is added until the pH becomes 3 or less while stirring with a magnetic stirrer. It dripped. After completion of the dropwise addition, the stirring was stopped, and when it was allowed to stand for 1 hour, the upper layer became transparent and a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain the composite resin of Reference Example 1. The blackness (L * value) was 24 and no color unevenness (variation) was observed.

(Comparative example 5)
A dispersion of Comparative Example 5 was obtained in the same manner as in Reference Example 1 except that the dispersing agent A6 was used instead of the dispersing agent A1. The dispersed particle size was 121 nm.

  2N hydrochloric acid was added dropwise to the dispersion of Comparative Example 5 in the same manner as in Reference Example 1 until the pH became 3 or less. After completion of the dropwise addition, the stirring was stopped, and when it was allowed to stand for 1 hour, the upper layer became transparent and a uniform black sediment was formed. The liquid in the upper layer was removed, and the sediment in the lower layer was collected and dried in a vacuum dryer at 105 ° C. for 24 hours to obtain a composite resin of Comparative Example 5. The degree of blackness (L * value) was 24 and no color unevenness (variation) was observed. The result was the same as in Example 1.

  The evaluation results of Examples 1 to 8 and Reference Example 1 and Comparative Examples 1 to 5 are shown in Tables 1 and 2.

  From the results shown in Tables 1 and 2, in Examples 1 to 8 in which a specific dispersant is used as a dispersant for carbon black having an average primary particle diameter of 30 nm or less, the monomer (a) is a linear α-olefin Compared with Comparative Example 1, a carbon black composite resin having excellent performance and excellent dispersibility and dispersion stability of the carbon black dispersion was obtained. Furthermore, in Examples 1 to 8, the performance of the carbon black composite resin was superior to Comparative Examples 2 to 4 in which an alkali compound other than the compound represented by Formula (I) was used as a neutralizing agent.

  Comparing Examples 1 to 7 and Comparative Examples 2 to 3 in which the degree of neutralization of the dispersant with the compound represented by the formula (I) is different, the degree of neutralization due to the compound represented by the formula (I) is low. As a result, the conductivity of the composite resin decreased, and the dispersion state also deteriorated. Therefore, it was found that the degree of neutralization by the compound represented by the formula (I) is preferably 100 mol%.

  Example 8 in which the average primary particle diameter of carbon black was 30 nm or less was superior in performance of the composite resin to Comparative Example 1 and Comparative Example 5 in which the average primary particle diameter of carbon black exceeded 30 nm. From this, it was found that the specific dispersant in the present disclosure is effective as a dispersant for carbon black having an average primary particle size of 30 nm or less.

  The carbon black dispersion liquid of the present invention is excellent in dispersibility, dispersion stability, and coprecipitation property with a resin, and therefore, when the carbon black dispersion liquid of the present invention is used, a high conductive effect can be obtained It is possible to provide a carbon black composite resin having performance such as blackness and is suitable for these applications.

Claims (12)

Containing carbon black, a dispersant and an aqueous medium,
The average primary particle diameter of the carbon black is 30 nm or less,
The carbon black dispersion liquid whose said dispersing agent contains following copolymer A.
Copolymer A: containing at least one constituent unit (b) derived from a branched α-olefin-derived constituent unit (a) and at least one compound selected from an unsaturated dibasic acid and an anhydride thereof, It is a copolymer which is partially neutralized by a compound represented by the following formula (I), and the degree of neutralization by the compound represented by the formula (I) is the total acid group content of the copolymer A To 50 mol% to 100 mol%.

[In formula (I), R ¹ , R ² and R ³ are the same or different, and are at least one selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms which may contain other elements. ] The branched α- olefin is at least one selected from 2-methyl-propene and 2,4,4-trimethyl-1-pentene, carbon black content dispersion liquid of claim 1. The carbon black dispersion liquid of Claim 1 or 2 whose compound represented by said Formula (I) is ammonia. The carbon black dispersion according to any one of claims 1 to 3 , wherein the structural unit (b) is a structural unit derived from at least one compound selected from maleic acid, maleic anhydride and fumaric acid. The BET specific surface area of the carbon black is not more than 100 m ² / g or more 500 meters ² / g, carbon black dispersion according to any one of claims 1 to 4. The carbon black dispersion liquid in any one of Claim 1 to 5 whose pH of the said carbon black is five or more and ten or less. Total surface acidic groups of the carbon black is less than 3μeq / m ^2, carbon black dispersion according to any one of claims 1 to 6. The carbon black dispersion according to any one of claims 1 to 7 , wherein a content of water in the aqueous medium is 80% by mass or more and 100% by mass or less. The carbon black dispersion according to any one of claims 1 to 8 , further comprising an aggregation promoter. Carbon black composite resin obtained by the manufacturing method containing following process (1)-(3).
(1) A step of mixing the carbon black dispersion according to any one of claims 1 to 9 with an aqueous resin emulsion to obtain a mixed liquid.
(2) A step of adding an acid to the mixed solution to form a coprecipitate of carbon black and a resin.
(3) A step of drying the coprecipitate. The carbon black composite resin according to claim 10 , wherein the step (2) is a step of coprecipitating the carbon black and the resin by adding an acid to make the pH of the mixture liquid 4 or less. It is a dispersant containing the following copolymer A,
A dispersant used to disperse carbon black having an average primary particle size of 30 nm or less in an aqueous medium.
Copolymer A: containing at least one constituent unit (b) derived from a branched α-olefin-derived constituent unit (a) and at least one compound selected from an unsaturated dibasic acid and an anhydride thereof, It is a copolymer which is partially neutralized by a compound represented by the following formula (I), and the degree of neutralization by the compound represented by the formula (I) is the total acid group content of the copolymer A To 50 mol% to 100 mol%.

[In formula (I), R ¹ , R ² and R ³ are the same or different, and are at least one selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms which may contain other elements. ]