JP6545961B2 - Polymeric dispersant for inorganic pigments - Google Patents

Description

  The present invention relates to a polymer dispersant for inorganic pigments, and a slurry composition containing the same.

  In the fine ceramic field and the like using inorganic pigments, attempts have been made to realize miniaturization, high speed, low power consumption, high efficiency, and high capacity by controlling a nanoscale fine structure.

Patent documents 1 and 2 disclose binder resin used for the inorganic fine particle dispersed paste composition containing inorganic fine particles.
Patent Document 3 discloses a polymeric dispersant for inorganic pigments comprising three structural units including a structural unit having an acid group, a structural unit having a macromonomer, and the like.

Japanese Patent Application Laid-Open No. 6-072759 JP, 2009-144079, A WO 2010/024186 specification

  The demand for nanodispersion technology of inorganic pigments in non-aqueous solvents is high, and there is a need for improved dispersant performance. Furthermore, also in the ceramic sheet represented by the green sheet used for a laminated ceramic capacitor, the handling property such as strength (hereinafter also referred to as "sheet strength") of the ceramic sheet after slurry coating is accompanied by thinning of the sheet. Improvement is required. Patent documents 1 and 2 mention using a methacrylic acid ester copolymer containing polyethylene glycol chain as a binder resin. However, the resin disclosed in the document is not a polymer dispersant for inorganic pigments but a binder resin, and is considered to be insufficient for dispersing the inorganic pigments. Patent Document 3 refers to a polymer dispersant containing a polyethylene glycol chain as a dispersant for highly dispersing barium titanate particles. However, there is room for further improvement in the improvement of the strength of a coating film such as a ceramic sheet obtained by pigment slurry coating.

  The present invention provides a polymer dispersant for inorganic pigments capable of producing a ceramic sheet having excellent inorganic pigment dispersibility and sheet strength.

  The present invention comprises the structural unit (a) represented by the formula (1), the structural unit (b) represented by the formula (2), and the structural unit (c) represented by the formula (3), A copolymer having a mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) of more than 0.7 and 7.5 or less and a weight average molecular weight of 1,000 to less than 50,000 (the following The present invention relates to a polymer dispersant for inorganic pigments (hereinafter also referred to as "the dispersant of the present invention"), which is used in a non-aqueous solvent, including the "copolymer of the present invention".

［式（１）中、Ｒ^１、Ｒ^２、及びＲ^３は同一又は異なり、水素原子、メチル基及びエチル基から選ばれる少なくとも１種を示し、Ｘ^１はＯＨ及びＯ⁻Ｍ^＋から選ばれる少なくとも１種を示し、Ｍ^＋は陽イオンを示す。］

［式（２）中、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^８は同一又は異なり、水素原子、メチル基及びエチル基から選ばれ得る少なくとも１種を示し、Ｒ^７は炭素数２以上４以下のアルカンジイル基を示し、Ｘ^２は酸素原子及びＮＨから選ばれる少なくとも１種を示し、ｎは平均付加モル数を示し、１以上１４０以下である。］

［式（３）中、Ｒ^９、Ｒ^１０、及びＲ^１１は同一又は異なり、水素原子、メチル基及びエチル基から選ばれる少なくとも１種を示し、Ｘ^４は酸素原子及びＮＨから選ばれる少なくとも１種を示し、Ｒ^１２及びＲ^１３は炭素数１以上３０以下の炭化水素基を示す。］

[In formula (1), R ¹ , R ² and R ³ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ¹ is selected from OH and O ⁻ M ⁺ M 1 represents at least one type, and M ⁺ represents a cation. ]

[In formula (2), R ⁴ , R ⁵ , R ⁶ and R ⁸ are the same or different, and represent at least one selected from a hydrogen atom, a methyl group and an ethyl group, and R ⁷ has 2 or more and 4 or less carbon atoms] And X ² represents at least one selected from an oxygen atom and NH, n represents an average addition mole number, and is 1 or more and 140 or less. ]

[Wherein, in the formula (3), R ⁹ , R ¹⁰ and R ¹¹ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ⁴ is at least one selected from an oxygen atom and NH] R ¹² and R ¹³ each represent a hydrocarbon group having 1 to 30 carbon atoms. ]

  Furthermore, the present invention relates to a slurry composition containing a non-aqueous solvent, an inorganic pigment, and the dispersant of the present invention (hereinafter, also referred to as “the slurry composition of the present invention”).

  The dispersant of the present invention has the effect of being able to highly disperse the inorganic pigment particles in the non-aqueous solvent and to improve the strength of the ceramic sheet formed from the slurry composition containing the dispersant. Thereby, this invention can suppress generation | occurrence | production of the defect by the fracture | rupture at the time of peeling a ceramic sheet from a release film, and can exhibit the effect of making handling property at the time of lamination | stacking of a ceramic sheet easy.

  The inventor of the present invention is a copolymer comprising the structural unit (a), the structural unit (b) and the structural unit (c), wherein the specific structural unit is contained at a predetermined ratio and the specific molecular weight is obtained. It has been found that good dispersibility (hereinafter, also simply referred to as "dispersibility") of inorganic pigments can be realized in a non-aqueous solvent, and that sheet strength can be improved. In the present disclosure, “to achieve good dispersibility of the inorganic pigment” means that the inorganic pigment can be dispersed in the state of the primary particle diameter or in a state close thereto, and good dispersibility is maintained even if a binder resin is added. It says what can be done. In the present disclosure, “improving the sheet strength” means that the breaking stress of a ceramic sheet formed from a slurry composition containing an inorganic pigment and a dispersant is improved.

  Although the details of the mechanism by which the effects of the present invention appear are unknown, the following can be presumed. First, in the copolymer contained in the dispersant of the present invention, the structural unit (a) is adsorbed on the surface of the inorganic pigment, and the structural unit (b) is obtained as a dispersing group by providing strong steric repulsion between the inorganic pigment particles. It functions and develops the dispersibility of the inorganic pigment particles. Furthermore, since the structural unit (c) has a low affinity with the non-aqueous solvent, the copolymer molecule itself can be contained by containing the structural unit (b) having a high affinity with the non-aqueous solvent at a specific ratio. Elution to the non-aqueous solvent is suppressed, and steric repulsion between the inorganic pigment particles is maintained. Therefore, factors that lower the sheet strength, such as interactions between components forming the ceramic sheet, such as a binder, and the copolymer molecules, and plasticization due to elution of the copolymer are eliminated, and good dispersibility and high sheet strength can be achieved. It can be expressed. Furthermore, by decreasing the molecular weight of the copolymer, the copolymer coats the surface of the inorganic pigment more uniformly, and the elution efficiency of the copolymer is further suppressed by the improvement of the adsorption efficiency, resulting in higher dispersibility and sheet strength. Express. However, these are only estimates, and the present invention is not limited to these mechanisms.

  The dispersant of the present invention may be the copolymer of the present invention itself, or may contain the copolymer of the present invention and further contain other components. As the other components, solvents, plasticizers, antistatic agents, binder resins and the like can be mentioned.

式（１）において、Ｒ^１、Ｒ^２、及びＲ^３は同一又は異なり、水素原子、メチル基及びエチル基から選ばれる少なくとも１種を示し、Ｘ^１はＯＨ及びＯ⁻Ｍ^＋から選ばれる少なくとも１種を示し、Ｍ^＋は陽イオンを示す。 [Constituent unit (a)]
The copolymer of the present invention contains the constituent unit (a) represented by the formula (1). The structural unit (a) has an acid group which can be neutralized, and it is considered that the copolymer molecules are selectively and strongly adsorbed on the surface of the inorganic pigment by electrostatic interaction with the surface of the inorganic pigment.

In the formula (1), R ¹ , R ² and R ³ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ¹ is at least one selected from OH and O ⁻ M ⁺ One type is shown, M ⁺ shows a cation.

R ¹ and R ² are preferably at least one selected from a hydrogen atom and a methyl group, from the viewpoint of the improvement of the sheet strength, the improvement of the dispersibility and the ease of introduction of the constituent unit (a) into the copolymer It is preferably a hydrogen atom, and R ³ is preferably at least one selected from a hydrogen atom and a methyl group, more preferably a methyl group. X ¹ is preferably OH from the same viewpoint as described above. Examples of M ⁺ include ammonium ion, organic ammonium ion and the like.

  Examples of the structural unit (a) include structural units derived from monomers having a carboxy group (hereinafter, also referred to as “monomers (a)”), structural units obtained by introducing a carboxy group after polymerization, and the like. From the viewpoint of easiness of preparation of combination, it is preferably a structural unit derived from the monomer (a). From the same point of view, the structural unit (a) is preferably a structural unit derived from a monomer having an ethylenically unsaturated double bond copolymerizable with the monomers forming the structural units (b) and (c). is there.

The monomer (a) is preferably a monomer represented by the formula (4) from the viewpoint of the improvement of the sheet strength, the improvement of the dispersibility and the easiness of introduction of the structural unit (a).

In Formula (4), R ¹ , R ² , R ³ , and X ¹ are the same as the above-described structural unit (a) in one or more embodiments.

  As the monomer (a), (meth) acrylic acid, crotonic acid and the like can be mentioned, and from the viewpoint of improvement of dispersibility and ease of introduction of the constituent unit (a) to the copolymer, (meth) acrylic acid is preferable. And more preferably methacrylic acid. In the present specification, “(meth) acrylic acid” means at least one selected from acrylic acid and methacrylic acid.

  The content of the structural unit (a) in all the structural units of the copolymer of the present invention is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of improvement in sheet strength and dispersibility. The content is preferably 5% by mass or more, more preferably 5% by mass or more, further preferably 8% by mass or more, further preferably 12% by mass or more, and from the same viewpoint, preferably less than 66% by mass, more preferably The content is 60% by mass or less, more preferably 45% by mass or less, still more preferably 35% by mass or less, and still more preferably 25% by mass or less.

[Constituent unit (b)]
The copolymer of the present invention contains the structural unit (b) represented by the formula (2). It is thought that the structural unit (b) has a nonionic group, provides strong steric repulsion between the inorganic pigment particles, and suppresses aggregation of the inorganic pigment particles to contribute to high dispersibility.

In formula (2), R ⁴ , R ⁵ , R ⁶ and R ⁸ are the same or different, and represent at least one selected from a hydrogen atom, a methyl group and an ethyl group, and R ⁷ has 2 or more and 4 or less carbon atoms An alkanediyl group is shown, and X ² is at least one selected from an oxygen atom and NH, n is an average addition mole number, and is 1 or more and 140 or less. R ⁴ and R ⁵ are preferably at least one selected from a hydrogen atom and a methyl group, from the viewpoints of the improvement of sheet strength, the improvement of dispersibility and the ease of introduction of the constituent unit (b) into the copolymer It is preferably a hydrogen atom, and R ⁶ is preferably at least one selected from a hydrogen atom and a methyl group, more preferably a methyl group. From the same point of view, R ⁷ is preferably at least one selected from ethanediyl and propanediyl, more preferably ethanediyl or a mixture of ethanediyl and propanediyl, still more preferably ethanediyl, R ⁸ Is preferably a methyl group or an ethyl group, more preferably a methyl group, and X ² is preferably an oxygen atom. n is 1 or more, preferably 2 or more, more preferably 10 or more, and still more preferably 20 or more from the viewpoint of improving the dispersibility, and is 140 or less from the viewpoint of improving the sheet strength, preferably Is 100 or less, more preferably 50 or less, and still more preferably 25 or less.

  Examples of the structural unit (b) include structural units derived from a monomer having a nonionic group (hereinafter, also referred to as “monomer (b)”), structural units obtained by introducing a nonionic group after polymerization, and the like. From the viewpoint of easiness of production of the copolymer, it is preferably a structural unit derived from the monomer (b). Examples of the nonionic group include polyoxyalkylene groups such as polyoxyethylene group and polyoxypropylene group. From the same point of view, the structural unit (b) is preferably a structural unit derived from a monomer having an ethylenically unsaturated double bond which is copolymerizable with the monomers forming the structural units (a) and (c). is there.

The monomer (b) is preferably a monomer represented by the formula (5) from the viewpoint of the improvement of the sheet strength, the improvement of the dispersibility, and the ease of introduction of the structural unit (b).

In Formula (5), R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , X ² , and n are the same as the above-described structural unit (b) in one or more embodiments.

  As the monomer (b), methoxy polyethylene glycol (meth) acrylate, methoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, ethoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, polyethylene glycol mono (meth) acrylate And polypropylene glycol mono (meth) acrylate, 2-methoxyethyl (meth) acrylamide, 2-ethoxyethyl (meth) acrylamide, 3-methoxypropyl (meth) acrylamide and the like. Among these, from the viewpoint of improvement in sheet strength and dispersibility, methoxy polyethylene glycol (meth) acrylate is preferable, and methoxy polyethylene glycol methacrylate is more preferable. In the present specification, “(meth) acrylate” means at least one selected from acrylate and methacrylate. Similarly, “(meth) acrylamide” means at least one selected from acrylamide and methacrylamide.

  The content of the structural unit (b) in all the structural units of the copolymer of the present invention is preferably more than 4% by mass, more preferably 10% by mass or more, from the viewpoint of improving sheet strength and dispersibility. The content is preferably 15% by mass or more, more preferably 20% by mass or more, and preferably 65% by mass or less, more preferably less than 55% by mass, still more preferably 45% by mass or less from the viewpoint of sheet strength improvement. .

[Constituent unit (c)]
The copolymer of the present invention contains the structural unit (c) represented by the formula (3). Since the structural unit (c) has a nonpolar group, it is considered to suppress the re-elution of the copolymer adsorbed on the surface of the inorganic pigment into the non-aqueous solvent. Furthermore, since the structural unit (c) does not have an ionic group, while keeping the copolymer on the surface of the inorganic pigment, the degree of freedom of the molecular shape of the copolymer is enhanced to more uniformly cover the inorganic pigment. Conceivable.

In the formula (3), R ⁹ , R ¹⁰ and R ¹¹ are the same or different and represent at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ⁴ is at least one selected from an oxygen atom and NH R ¹² and R ¹³ each represent a hydrocarbon group having 1 or more and 30 or less carbon atoms. R ⁹ and R ¹⁰ are preferably at least one selected from a hydrogen atom and a methyl group, more preferably a hydrogen atom, from the viewpoint of dispersibility improvement and easiness of introduction of the constituent unit (c) to the copolymer. And X ⁴ is preferably an oxygen atom. R ¹¹ is preferably at least one selected from a hydrogen atom and a methyl group, and is more preferably a hydrogen atom from the viewpoint of improving the sheet strength and the dispersibility. R ¹² is preferably an aliphatic hydrocarbon group, and more preferably has a branched chain from the viewpoint of improving the sheet strength and the dispersibility. The carbon number of R ¹² is 1 or more, preferably 5 or more, more preferably 12 or more, still more preferably 16 or more, from the viewpoint of improvement in sheet strength, and the viewpoint of ease of production of the copolymer Therefore, preferably 22 or less, more preferably 18 or less. As R ¹² , methyl group, ethyl group, butyl group, octyl group, 2-ethylhexyl group, decyl group, lauryl group, myristyl group, cetyl group, stearyl group, isostearyl group, oleyl group, behenyl group, cyclohexyl group, A benzyl group etc. are mentioned and it is an at least 1 sort (s) selected from a stearyl group and an isostearyl group preferably from a viewpoint of a sheet strength improvement and a dispersible improvement, More preferably, it is an isostearyl group. X ² is preferably R ¹³ from the viewpoint of improving the sheet strength and the dispersibility. R ¹³ is preferably an aromatic hydrocarbon group from the viewpoint of improvement in sheet strength, improvement in dispersibility, and availability. The carbon number of R ¹³ is 1 or more, preferably 5 or more from the viewpoint of improvement in sheet strength, and preferably 22 or less, more preferably 18 or less from the viewpoint of ease of production of the copolymer. It is. Examples of R ¹³ include decyl group, isodecyl group, stearyl group, isostearyl group, cyclohexyl group, phenyl group and the like, and from the viewpoint of improvement in sheet strength and dispersion, a phenyl group is preferable.

The solubility parameter (unit: [(MPa) ^1/2 ]) of the structural unit (c) is preferably 12.0 or more, more preferably 14.5 or more, further preferably from the viewpoint of easiness of copolymer production. Is 15.0 or more, and preferably 20.0 or less, more preferably 17.0 or less, still more preferably 16.2 or less, still more preferably 15.8 or less from the viewpoint of improving sheet strength. In the present invention, the solubility parameter of the structural unit (c) refers to a value calculated by the method of Hansen. That is, the solubility parameter corresponds to δ calculated from the three-dimensional solubility parameter described in JP-A-2004-196719 [0013]. Each three-dimensional solubility parameter is as described in DW. Using the molar attraction constant of the group described in Van Krevelen, "Properties of Polymers., 3rd ed., Elsevier, New York., 1990 Ch. 7", the mole of the group constituting constituent unit (c) It can be calculated by adding the attraction constant.

  Examples of the structural unit (c) include structural units derived from monomers having a nonpolar group (hereinafter, also referred to as “monomers (c)”), structural units obtained by introducing a nonpolar group after polymerization, and the like. From the viewpoint of the ease of production of the copolymer, it is preferably a structural unit derived from the monomer (c). As a nonpolar group, hydrocarbon groups, such as an alkyl group, an alkylene group, and an aryl group, are mentioned, for example. From the same point of view, the structural unit (c) is preferably a structural unit derived from a monomer having an ethylenically unsaturated double bond copolymerizable with the monomers forming the structural units (a) and (b). is there.

The monomer (c) is preferably a monomer represented by the formula (6) from the viewpoint of the improvement of the sheet strength, the improvement of the dispersibility, and the ease of introduction of the structural unit (c).

In formula (6), R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and X ⁴ are the same as the above-mentioned structural unit (c) in one or more embodiments.

  As the monomer (c), methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, etc. Ester compounds; Amide compounds such as butyl (meth) acrylamide, octyl (meth) acrylamide, lauryl (meth) acrylamide, stearyl (meth) acrylamide, behenyl (meth) acrylamide; α-olefins such as 1-decene and 1-octadecene; And those in which these alkyl chains are branched; and benzyl (meth) acrylate, styrene and the like. Among them, at least one selected from methyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, benzyl (meth) acrylate and styrene from the viewpoint of improvement in sheet strength and dispersibility. It is more preferably at least one selected from isostearyl methacrylate and styrene, and from the viewpoint of improving the dispersibility, more preferably styrene.

  The content of the structural unit (c) in all the structural units of the copolymer of the present invention is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass from the viewpoint of improving sheet strength. %, And preferably from 75% by mass or less, more preferably less than 70% by mass, still more preferably 65% by mass or less, still more preferably 55% by mass or less from the viewpoint of improving sheet strength and dispersibility. is there.

  The mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) in the copolymer of the present invention is more than 0.7, preferably 0, from the viewpoint of improving the sheet strength. .8 or more, more preferably 0.9 or more, and still more preferably 1.0 or more, and from the viewpoint of improving sheet strength and dispersibility, it is 7.5 or less, preferably 3.7 or less More preferably, it is 2.2 or less, More preferably, it is 1.5 or less.

[Other configuration unit]
The copolymer of the present invention may contain other structural units other than the structural units (a), (b) and (c) as long as the effects of the present invention are not impaired. The content of the other structural unit among all the structural units of the copolymer of the present invention is preferably 10% by mass or less, more preferably 3% by mass or less, still more preferably 1 from the viewpoint of exerting the effects of the present invention. It is less than mass%.

[Production of copolymer]
The copolymer of the present invention can be obtained by a known method such as, for example, polymerizing a monomer mixture containing the monomers (a), (b) and (c) by a solution polymerization method. Examples of the solvent used for solution polymerization include aromatics such as toluene and xylene; alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran and diethylene glycol dimethyl ether. The amount of the solvent is preferably 50 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the total amount of monomers.

  A well-known radical polymerization initiator can be used as a polymerization initiator, Azo-type polymerization initiator, hydroperoxides, dialkyl peroxides, diacyl peroxides, ketone peroxides, etc. are mentioned. The amount of the polymerization initiator is preferably 1 mol or more, more preferably 2 mol or more, still more preferably 3 mol or more, and preferably 15 mol or less, more preferably 12 mol or less, per 100 mol of the total amount of monomers. More preferably, it is 9 mol or less. The polymerization reaction is preferably performed in a nitrogen atmosphere, the reaction temperature is preferably 60 ° C. to 180 ° C., and the reaction time is preferably 0.5 hours to 20 hours.

  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, and mercaptosuccinic acid; thiuram disulfide Hydrocarbons; unsaturated cyclic hydrocarbon compounds; unsaturated heterocyclic compounds etc. may be mentioned, and one or more of them may be used.

[Copolymer]
In the copolymer of the present invention, the arrangement of the structural unit (a), the structural unit (b) and the structural unit (c) may be any of random, block, graft and the like, from the viewpoint of ease of production of the copolymer. And preferably at least one selected from random and block, and from the viewpoint of improving dispersibility, it is more preferably random. In the copolymer of the present invention, the mass ratio of the structural unit (a) in all the structural units is the monomer (a) to the total amount of monomers used for polymerization, and a monomer capable of adding an acid group which can be neutralized after polymerization; It can be considered as a mass ratio of the total amount to the acid group. The mass ratio of the structural unit (b) in all the structural units is the total amount of the monomer (b), the monomer capable of introducing a nonionic group after polymerization, and the nonionic group with respect to the total amount of monomers used for polymerization. It can be considered as a mass ratio. The mass ratio of the structural unit (c) in all the structural units is the mass ratio of the total amount of the monomer (c), the monomer capable of introducing a nonpolar group after polymerization, and the nonpolar group to the total amount of monomers used for polymerization. It can be regarded as The mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) is represented by [mass ratio of structural unit (c) in all structural units / structural unit in all structural units It can be considered as the mass ratio of b).

  The weight average molecular weight of the copolymer of the present invention is 1000 or more, preferably 2000 or more, more preferably 4000 or more, still more preferably 7000 or more, from the viewpoint of improvement in sheet strength and dispersion improvement. From the viewpoint of the improvement of sheet strength, the improvement of dispersibility and the ease of production of the copolymer, it is less than 50000, preferably 40000 or less, more preferably 20000 or less, still more preferably 10000 or less. The measuring method of a weight average molecular weight is based on the method as described in an Example.

  The dispersant of the present invention containing the copolymer of the present invention is excellent in the dispersibility of the inorganic pigment in the non-aqueous solvent, and is formed from a slurry composition containing the non-aqueous solvent, the inorganic pigment and the dispersant of the present invention Excellent in strength such as ceramic sheet. Therefore, the dispersant of the present invention is suitably used for dispersing the inorganic pigment in the non-aqueous solvent.

Non-aqueous solvent
The solubility parameter (unit: [(MPa) ^1/2 ]) of the non-aqueous solvent that can be used in the present invention is preferably 20 or more from the viewpoint of improving the dispersibility of the inorganic pigment and compatibility with the polymer dispersant. , More preferably 21 or more, and preferably 30 or less, more preferably 26 or less. In the present invention, the solubility parameter of the non-aqueous solvent is determined according to the method of Fedors [R. F. Fedors. Polym. Eng. Sci. , 14, 147 (1974)] is referred to.

  The solubility parameter can be suitably adjusted using two or more non-aqueous solvents. Although the solubility parameter of such a mixed solvent can be determined by the above-mentioned method, it can also be calculated and calculated from the solubility parameter and volume fraction of each component of the mixed solvent as a simple method. For example, when toluene and ethanol are mixed at a volume fraction of 50:50, the solubility parameter is (18.3) × 0.5 + (26.2) × 0.5 = 22.3.

  Non-aqueous solvents usable in the present invention include xylene (18.2), ethyl acetate (18.2), toluene (18.3), tetrahydrofuran (18.5), methyl ethyl ketone (19.3), acetone (19.7), butyl cellosolve (20.2), dimethylformamide (24.7), n-propanol (24.9), ethanol (26.2), dimethyl sulfoxide (26.4), n-butanol (28) And 7), at least one selected from organic solvents such as methanol (29.7). The numerical values in the above () are solubility parameters.

[Inorganic pigment]
In general, the surface of the inorganic pigment has both an acid point and a base point. The amount of acid point and base point in the non-aqueous solvent can be determined by back titration. In the back titration method, a basic reagent (or an acidic reagent) whose concentration is known in advance is mixed with an inorganic pigment at a constant ratio and sufficiently neutralized, and then solid-liquid separation is performed by a centrifuge or the like, The supernatant is titrated to determine the amount of acid (or the amount of base) from the amount of basic reagent (or the amount of acidic reagent) which has been reduced. In the present invention, the amount of base and the amount of acid can be determined by the following.

1) Determining the amount of base 2 g of inorganic pigment is precisely weighed (sample amount), put into 30 mL of 0.01 N acetic acid-toluene / ethanol (volume ratio 48/52) solution, ultrasonic cleaner (manufactured by Branson “1510 J- Dispersion treatment is carried out for 1 hour with MT ") to obtain a dispersion. After standing for 24 hours, a portion of the dispersion is centrifuged at 25,000 rpm for 60 minutes using a centrifuge ("CP-56G" manufactured by Hitachi, Ltd.). Add 10 mL of the separated upper layer liquid portion to 20 mL of a toluene / ethanol solvent (volume ratio 2/1) to which a phenolphthalein indicator is added, and perform neutralization titration with a 0.01 N potassium hydroxide-ethanol solution. The titration amount at this time is X (mL), B is the titration amount necessary to neutralize 10 mL of 0.01 N acetic acid-toluene / ethanol (volume ratio 48/52), B (mL), and the sample amount is S (g) Then, the amount of base is determined by the following equation.
Base amount (μmol / g) = 30 × (B−X) / S

2) How to determine the amount of acid Finely weigh 2 g of the inorganic pigment (sample amount), put in 30 mL of 0.01N n-butylamine-toluene / ethanol (volume ratio 48/52) solution, and use an ultrasonic cleaner (Branson). Dispersion treatment is carried out with 1510 J-MT ") for 1 hour to obtain a dispersion. After standing for 24 hours, a portion of the dispersion is centrifuged at 25,000 rpm for 60 minutes using a centrifuge ("CP-56G" manufactured by Hitachi, Ltd.). Add 10 mL of the separated upper layer liquid portion to 20 mL of a toluene / ethanol solvent (volume ratio 2/1) to which a bromcresol green indicator is added, and perform neutralization titration with a 0.01 N hydrochloric acid-ethanol solution. The titration amount at this time is X (mL), the titration amount necessary to neutralize 10 mL of 0.01 N n-butylamine-toluene / ethanol (volume ratio 48/52) is B (mL), the sample amount is S ( Assuming that g), the amount of acid is determined by the following equation.
Amount of acid (μmol / g) = 30 × (B−X) / S

  The inorganic pigment in the present invention is preferably a basic inorganic pigment from the viewpoint of improvement in sheet strength and dispersion. The basic inorganic pigment is an inorganic pigment having a base amount as defined above having a larger value than the acid amount as defined above, and metal oxides such as titanium oxide, magnesium oxide, barium oxide and aluminum oxide; magnesium carbonate, carbonate Metal carbonates such as barium; barium zirconate, calcium zirconate, calcium titanate, barium titanate, composite oxides such as strontium titanate, etc. may be mentioned. From the viewpoint of improving the properties of the ceramic sheet, the inorganic pigment in the present invention is more preferably a complex oxide, and still more preferably barium titanate.

  Average particle size (average particle size based on BET specific surface area) of the inorganic pigment which can suitably use the dispersant of the present invention, and average particle size (volume median particle) of the inorganic pigment contained in the slurry composition of the present invention The diameter (D50) is preferably 500 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less from the viewpoint of improvement of dispersibility, and from the viewpoint of maintaining dispersibility, preferably 5 nm or more, more preferably Is 7 nm or more, more preferably 8 nm or more. The average particle size (average particle size based on BET specific surface area) of the inorganic pigment preferably refers to the average particle size of the powdery inorganic pigment, and is measured as follows.

Method of measuring average particle diameter of inorganic pigment (average particle diameter based on BET specific surface area) Average particle diameter of inorganic pigment (average particle diameter based on BET specific surface area) Assuming that the BET specific surface area S (m ² / g) and the density 無機 (g / cm ³ ) of the inorganic fine particles measured by the nitrogen adsorption method can be used. That is, since the BET specific surface area is a surface area per unit mass, assuming that the surface area is A (m ² ) and the mass of particles is W (g),
S = A / W
= [4 x pi x (R / 2) ² ] / [4/3 x pi x (R / 2) ³ x p x 10 ⁶ ]
= 6 / (R × ρ × 10 ⁶ )
The following equation is obtained. Converting the unit of particle size to nm,
R (nm) = 6000 / (S × ρ)
The average particle diameter (average particle diameter based on BET specific surface area) can be obtained. For example, if the BET specific surface area of barium titanate (density 6.0 g / cm ³ ) is 5.0 (m ² / g), the average particle size (average particle size based on BET specific surface area) is 200 nm It becomes.

[Method of producing a slurry composition]
The slurry composition of the present invention can be produced by a method comprising the steps of mixing, preferably dispersing, the inorganic pigment, the non-aqueous solvent and the dispersant of the present invention. Said step comprises the step of mixing the inorganic pigment, the non-aqueous solvent and the dispersant of the present invention with the medium. The shape of the medium is preferably beads, and the particle size thereof is preferably 0.1 mm or more, more preferably 0.5 mm or more, preferably 3 mm or less, more preferably 1.5 mm or less. The material of the medium is preferably alumina or zirconia, more preferably zirconia. The preferred amounts of the inorganic pigment, the non-aqueous solvent and the dispersant of the present invention to be mixed when producing the slurry composition are the same as the contents of the respective components in the slurry composition described later. By the above manufacturing method, an inorganic pigment can be dispersed in a non-aqueous solvent, and a slurry composition excellent in dispersibility and sheet strength can be manufactured.

[Slurry composition]
If the dispersing agent of this invention is used, the slurry composition which the inorganic pigment disperse | distributed to the non-aqueous solvent can be obtained. Therefore, the slurry composition of the present invention contains an inorganic pigment, a non-aqueous solvent and the dispersant of the present invention. The content of the inorganic pigment in the slurry composition is preferably 5% by mass or more, more preferably 10% by mass or more from the viewpoint of improvement of dispersibility, and preferably 60% by mass or less from the same viewpoint Preferably it is 50 mass% or less. The content of the copolymer derived from the dispersant of the present invention relative to 100 parts by mass of the inorganic pigment is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, from the viewpoint of improving the dispersibility. From the viewpoint of improving sheet strength, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. The "copolymer derived from the dispersant of the present invention" refers to a copolymer contained in the dispersant of the present invention.

  The dispersibility in the slurry composition can be evaluated by the viscosity of the slurry composition, the sedimentation behavior of the inorganic pigment, the particle size distribution of the inorganic pigment, and the like, and is preferably evaluated by the particle size distribution from the viewpoint of the determination of the number of coarse particles. The dispersibility of the slurry composition of the present invention is measured by the method described in the examples.

  The slurry composition of the present invention may contain an additive such as a low molecular weight compound such as a binder resin, an antistatic agent, a plasticizer, a lubricant, a dispersion aid and the like, as long as the effects of the present invention are not impaired. It is preferable to contain a binder resin from the viewpoint of sheet strength improvement.

  The binder resin is preferably a polyvinyl acetal resin, and more preferably a polyvinyl butyral resin, from the viewpoint of improving the sheet strength and the performance of the ceramic sheet. The degree of acetalization of the polyvinyl acetal resin is preferably 55 mol% or more, more preferably 65 mol% or more, from the viewpoint of solubility in non-aqueous solvent and improvement in strength of the ceramic sheet, and strength of the ceramic sheet From the viewpoint of improvement, it is preferably 80 mol% or less, more preferably 75 mol% or less.

  The content of the binder resin in the slurry composition of the present invention relative to 100 parts by mass of the inorganic pigment is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, still more preferably 6 parts by mass from the viewpoint of improving the sheet strength. The amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 11 parts by mass or less, and still more preferably 9 parts by mass or less from the viewpoint of improving dispersibility. When the slurry composition contains the dispersant of the present invention, a ceramic sheet excellent in sheet strength can be obtained even with a small amount of binder resin.

  The above-mentioned antistatic agent is preferably a cationic antistatic agent from the viewpoint of improving the sheet strength. As said cationic antistatic agent, the compound which has nitrogen-containing heterocyclic rings, such as an alkyl imidazoline and an alkyl imidazole, is mentioned, for example. The content of the antistatic agent in the slurry composition of the present invention relative to 100 parts by mass of the inorganic pigment is preferably 0.05 parts by mass or more, more preferably 0.1 from the viewpoint of improving the sheet strength and the performance of the ceramic sheet. From the viewpoint of maintaining the strength of the ceramic sheet, the amount is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less.

  With regard to the embodiments described above, the present invention further discloses the following composition, manufacturing method, or use.

［式（１）中、Ｒ^１、Ｒ^２、及びＲ^３は同一又は異なり、水素原子、メチル基及びエチル基から選ばれる少なくとも１種を示し、Ｘ^１はＯＨ及びＯ⁻Ｍ^＋から選ばれる少なくとも１種を示し、Ｍ^＋は陽イオンを示す。］

［式（２）中、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^８は同一又は異なり、水素原子、メチル基及びエチル基から選ばれ得る少なくとも１種を示し、Ｒ^７は炭素数２以上４以下のアルカンジイル基を示し、Ｘ^２は酸素原子及びＮＨから選ばれる少なくとも１種を示し、ｎは平均付加モル数を示し、１以上１４０以下である。］

［式（３）中、Ｒ^９、Ｒ^１０、及びＲ^１１は同一又は異なり、水素原子、メチル基及びエチル基から選ばれる少なくとも１種を示し、Ｘ^４は酸素原子及びＮＨから選ばれる少なくとも１種を示し、Ｒ^１２及びＲ^１３は炭素数１以上３０以下の炭化水素基を示す。］ <1> contains the structural unit (a) represented by Formula (1), the structural unit (b) represented by Formula (2), and the structural unit (c) represented by Formula (3), Containing a copolymer having a mass ratio [(c) / (b)] of the structural unit (c) to the unit (b) of more than 0.7 and not more than 7.5 and a weight average molecular weight of 1,000 to less than 50,000. Polymeric dispersant for inorganic pigments used in non-aqueous solvents.

[In formula (1), R ¹ , R ² and R ³ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ¹ is selected from OH and O ⁻ M ⁺ M 1 represents at least one type, and M ⁺ represents a cation. ]

[In formula (2), R ⁴ , R ⁵ , R ⁶ and R ⁸ are the same or different, and represent at least one selected from a hydrogen atom, a methyl group and an ethyl group, and R ⁷ has 2 or more and 4 or less carbon atoms] And X ² represents at least one selected from an oxygen atom and NH, n represents an average addition mole number, and is 1 or more and 140 or less. ]

[Wherein, in the formula (3), R ⁹ , R ¹⁰ and R ¹¹ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ⁴ is at least one selected from an oxygen atom and NH] R ¹² and R ¹³ each represent a hydrocarbon group having 1 to 30 carbon atoms. ]

<2> In the copolymer, the arrangement of the structural unit (a), the structural unit (b) and the structural unit (c) is preferably at least one selected from random and block, more preferably random, <1 Polymeric dispersant for inorganic pigments as described in>.
The content of the structural unit (a) is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, still more preferably 5% by mass, based on all constituent units of the <3> copolymer. The polymeric dispersant for inorganic pigments as described in <1> or <2> which is more than%, More preferably, it is 8 mass% or more, More preferably, it is 12 mass% or more.
The content of the structural unit (a) is preferably less than 66% by mass, more preferably 60% by mass or less, still more preferably 45% by mass or less, still more preferably 35% by mass, based on all constituent units of the <4> copolymer. The polymeric dispersant for inorganic pigments in any one of <1> to <3> which is% or less, more preferably 25 mass% or less.
The inorganic pigment according to any one of <1> to <4>, wherein the content of the structural unit (a) is preferably more than 5% by mass and less than 66% by mass in all the constituent units of the <5> copolymer Polymer dispersants.
<6> The inorganic according to any one of <1> to <5>, n in the formula (2) is 1 or more, preferably 2 or more, more preferably 10 or more, and still more preferably 20 or more. Polymeric dispersant for pigments.
<7> The inorganic pigment according to any one of <1> to <6>, wherein n in the formula (2) is 140 or less, preferably 100 or less, more preferably 50 or less, still more preferably 25 or less Polymer dispersants.
The content of the structural unit (b) is preferably more than 4% by mass, more preferably 10% by mass or more, still more preferably 15% by mass or more, still more preferably 20% by mass, based on all constituent units of the <8> copolymer. Polymeric dispersant for inorganic pigments according to any one of <1> to <7>, which is%.
The content of the structural unit (b) is preferably 65% by mass or less, more preferably less than 55% by mass, and still more preferably 45% by mass or less, based on the total constituent units of the <9> copolymer. Polymeric dispersant for inorganic pigments according to any one of <8>.
The inorganic pigment according to any one of <1> to <9>, wherein the content of the structural unit (b) is preferably more than 4% by mass and less than 55% by mass in all the constituent units of the <10> copolymer Polymer dispersants.
<11> Any one of <1> to <10>, wherein the carbon number of R ¹² in the formula (3) is 1 or more, preferably 5 or more, more preferably 12 or more, still more preferably 16 or more Polymeric dispersant for inorganic pigments as described in 4.
<12> formula (3) number of carbon atoms in ^{R 12} in is preferably 22 or less, more preferably 18 or less, the inorganic pigment for polymeric dispersing agent according to any one of <11> to <1>.
<13> formula (3) number of carbon atoms in ^{R 13} in is 1 or more, preferably 5 or more, inorganic pigment for polymeric dispersing agent according to any one of <12> to <1>.
<14> formula (3) number of carbon atoms in ^{R 13} in is preferably 22 or less, more preferably 18 or less, the inorganic pigment for polymeric dispersing agent according to any one of <13> to <1>.
<15> formula (3) the number of carbon atoms of ^{R 12} and ^{R 13} in is preferably 5 or more and 30 or less, the inorganic pigment for polymeric dispersing agent according to any one of <14> to <1>.
The solubility parameter (unit: [(MPa) ^1/2 ]) of the <16> structural unit (c) is preferably 12.0 or more, more preferably 14.5 or more, still more preferably 15.0 or more. The polymeric dispersant for inorganic pigments in any one of <1> to <15>.
The solubility parameter (unit: [(MPa) ^1/2 ]) of the <17> structural unit (c) is preferably 20.0 or less, more preferably 17.0 or less, still more preferably 16.2 or less, further preferably The polymeric dispersant for inorganic pigments according to any one of <1> to <16>, wherein is 15.8 or less.
The content of the structural unit (c) is preferably 20% by mass or more, more preferably more than 30% by mass, and still more preferably 40% by mass or more, based on the total constituent units of the <18> copolymer. Polymeric dispersant for inorganic pigments according to any one of <17>.
The content of the structural unit (c) is preferably 75% by mass or less, more preferably less than 70% by mass, still more preferably 65% by mass or less, still more preferably 55% by mass, based on all constituent units of the <19> copolymer. The polymeric dispersant for inorganic pigments in any one of <1> to <18> which is% or less.
The inorganic pigment according to any one of <1> to <19>, wherein the content of the structural unit (c) is preferably more than 30% by mass and less than 70% by mass, based on all the constituent units of the <20> copolymer. Polymer dispersants.
The mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) in the <21> copolymer is more than 0.7, preferably 0.8 or more, more preferably 0 <9> The polymer dispersant for inorganic pigments according to any one of <1> to <20>, which is 9 or more, and more preferably 1.0 or more.
The mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) in the <22> copolymer is 7.5 or less, preferably 3.7 or less, more preferably 2 .2 The polymer dispersant for an inorganic pigment according to any one of <1> to <21>, which is not more than 2, more preferably not more than 1.5.
<23> Any of <1> to <22>, wherein the mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) is preferably more than 0.7 and 2.2 or less Polymeric dispersant for inorganic pigments described in "Kani".
The inorganic compound according to any one of <1> to <23>, wherein the weight average molecular weight of the <24> copolymer is 1000 or more, preferably 2000 or more, more preferably 4000 or more, and still more preferably 7000 or more. Polymeric dispersant for pigments.
The inorganic compound according to any one of <1> to <24>, wherein the weight average molecular weight of the <25> copolymer is less than 50,000, preferably 40000 or less, more preferably 20000 or less, still more preferably 10000 or less. Polymeric dispersant for pigments.
<26> The polymer dispersant for an inorganic pigment according to any one of <1> to <25>, wherein the inorganic pigment is preferably a basic inorganic pigment, more preferably a complex oxide, more preferably barium titanate. .
The slurry composition containing the polymer dispersing agent for <27> non-aqueous solvent, an inorganic pigment, and the inorganic pigment in any one of <1> to <26>.
<28> The slurry composition according to <27>, preferably further containing a binder resin.
<29> The content of the copolymer derived from the high molecular weight dispersant for inorganic pigments based on 100 parts by mass of the inorganic pigment is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, <27 The slurry composition as described in> or <28>.
The content of the copolymer derived from the high molecular weight dispersant for inorganic pigments to 100 parts by mass of <30> inorganic pigment is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, <27> to <29 The slurry composition as described in any one of>.
<31> The slurry composition according to any one of <27> to <30>, wherein the content of the inorganic pigment in the slurry composition is preferably 5% by mass or more, more preferably 10% by mass or more.
<32> The slurry composition according to any one of <27> to <31>, wherein the content of the inorganic pigment in the slurry composition is preferably 60% by mass or less, more preferably 50% by mass or less.

  Hereinafter, the present invention will be described by way of examples. In the following examples, X in the notation "polyalkylene glycol (X mole)" indicates the average addition mole number of alkylene oxide of the alkylene glycol. The measurement of the weight average molecular weight, the solid content and the particle size of the slurry composition, and the evaluation of the sheet strength were performed by the following methods.

(1) Measurement of weight average molecular weight A gel permeation chromatography (hereinafter also referred to as "GPC") method was used. The sample was diluted with N, N-dimethylformamide, and a solution having a solid concentration of 0.3% by mass of the sample was prepared as a sample solution, and 100 μL of the solution was subjected to measurement. A solution of phosphoric acid and lithium bromide dissolved in N, N-dimethylformamide so as to have concentrations of 60 mmol / L and 50 mmol / L, respectively, is used as an eluent, GPC [apparatus: "HLC-8120 GPC" manufactured by Tosoh Corporation, Detector: Differential refractometer (apparatus attachment), column: Tosoh Corp. "TSK-GEL alpha-M" x 2 pieces, column temperature: It measured by 40 degreeC, eluent flow rate: 1 mL / min]. As a standard substance, polystyrene (manufactured by Tosoh Corp .: molecular weight 5.26 × 10 ² , 1.02 × 10 ⁵ , 8.42 × 10 ⁶ ; manufactured by Nishio Kogyo Co., Ltd .: molecular weight 4.0 × 10 ³ , 3. 0 × 10 ⁴ , 9.0 × 10 ⁵ ) were used.

(2) Measurement of solid content A glass rod and 10 g of dry anhydrous sodium sulfate were placed in a petri dish, 1 g of a sample was weighed there, mixed with a glass rod, and dried with a vacuum dryer at 105 ° C. (pressure 8 kPa) for 2 hours. The mass after drying was weighed, and the value obtained by the following equation was regarded as the solid content.
Solid content (% by mass) = {[(mass after drying− (weight of petri dish + weight of glass rod + mass of anhydrous sodium sulfate))] / mass of sample} × 100

(3) Measurement of Particle Size of Slurry Composition As a particle size measuring device, a particle size distribution measuring device ("Zetasizer Nano ZS" manufactured by Sysmex Corporation) based on the principle of photon correlation method (dynamic light scattering method) was used. A liquid obtained by mixing 0.025 g of a non-aqueous slurry composition and 2 mL of a toluene / ethanol mixed solvent (volume ratio: 48/52) as a dispersion medium is used as a sample, and 1.2 mL is added to a glass cell having an optical path length of 10 mm. It extract | collected and put in the measurement part and measured. As measurement parameters, the refractive index of the particles, the refractive index of the dispersion medium and the sample viscosity were input. For example, when the inorganic pigment is barium titanate, the refractive index of the particles is 2.40. The refractive index of the dispersion medium was 1.423, and the sample viscosity was 0.752. The particle diameter at which the frequency distribution of the scattering intensity becomes 50% is D50, and the particle diameter at which the frequency distribution becomes 90% is D90.

(4) Evaluation of sheet strength Using a film applicator (gap 50 μm), the slurry composition was applied to a silicone-treated release film (“Purex A31” manufactured by Teijin DuPont Films, Inc.), and kept at 60 ° C. for 16 hours It dried and shape | molded the ceramic sheet. The thickness of the ceramic sheet after drying was 5 μm. The obtained ceramic sheet is cut and separated using a lever-type sample cutting machine ("SD type" manufactured by Dumbbell Co., Ltd.) to which a super dumbbell ("SDK-2493" manufactured by Dumbbell Co., Ltd.) is attached together with the release film. The breaking stress when the sheet breaks is measured using a bench-type precision testing machine ("Autograph EZ-Test" manufactured by Shimadzu Corporation) with a sheet from which the mold film has been peeled as a test piece and equipped with a jig for tensile test. Sheet strength was taken. The higher the breaking stress, the better the sheet strength.

Details of the polymer dispersants used in Examples and Comparative Examples are shown in Table 1. Here, the abbreviations of the raw materials used in Table 1 and the following examples are as follows. What has a description of Sp value is a solubility parameter (unit: [(MPa) ^1/2 ]) calculated by Hansen's method when the raw material becomes a constituent unit of a copolymer by polymerization.
St: Styrene (manufactured by NS Styrene Monomer) (Sp value: 15.5)
-MMA: methyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.) (Sp value: 16.4)
SMA: Stearyl methacrylate ("NK Ester S" manufactured by Shin-Nakamura Chemical Co., Ltd.) (Sp value: 16.0)
· I-SMA: Branched stearyl methacrylate ("NK ester S-1800 M" manufactured by Shin-Nakamura Chemical Co., Ltd.) (Sp value: 15.7)
· SA: stearyl acrylate ("STA" manufactured by Osaka Organic Chemical Industry Ltd.) (Sp value: 15.9)
-PEG (2) MA: methoxypolyethylene glycol (2 moles) methacrylate ("NK-ester M-20G" manufactured by Shin-Nakamura Chemical Co., Ltd.)
-PEG (13) MA: methoxy polyethylene glycol (13 moles) methacrylate ("NK-ester M-130 G" manufactured by Shin-Nakamura Chemical Co., Ltd.)
-PEG (23) MA: methoxy polyethylene glycol (23 moles) methacrylate ("NK-ester TM-230G" manufactured by Shin-Nakamura Chemical Co., Ltd.)
PEG (90) MA: methoxypolyethylene glycol (90 mol) methacrylate (NOF Corporation "Blenmer PME-4000")
-PEG (120) MA: methoxy polyethylene glycol (120 moles) methacrylate (manufactured by Kao, part number: chemical product intermediate)
-MAA: methacrylic acid ("GE-110" manufactured by Mitsubishi Gas Chemical Co., Ltd.)
-MPD: 3-mercapto-1,2-propanediol ("1-thioglycerol" manufactured by Asahi Chemical Industry Co., Ltd.)
V-65B: 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)

Example 1
In a 1 L separable flask equipped with a reflux condenser, a stirrer, a thermometer and a nitrogen introduction pipe, 6.75 g of MAA as a "monomer for initial feeding", 18.0 g of PEG (90) MA, 20.25 g of St, 2 mg of MPD 1. 8 g and 27.0 g of ethanol (manufactured by Kishida Chemical Co., Ltd., reagent) were charged, the flask was replaced with nitrogen while stirring, and the temperature was raised to 80 ° C. While stirring the inside of the flask at 80 ° C, a mixed solution of 1.35 g of V-65B and 12.15 g of ethanol as an "initiator solution" is added into the flask, and then 60.75 g of MAA as a "droplet monomer solution" A mixed solution of 162 g of PEG (90) MA, 182.25 g of St, 16.2 g of MPD, 12.15 g of V-65B and 243.0 g of ethanol was dropped into the flask over 3 hours. The mixture was further stirred at 80 ° C. for 3 hours and cooled. Ethanol was added to the flask for concentration adjustment to obtain a polymer dispersant solution. The solid content was 55.9% by mass, and the weight average molecular weight was 8200.

[Examples 3 to 13 , 15 to 17, Reference Examples 2 and 14, Comparative Examples 1 to 3]
Polymeric dispersant solution in the same manner as in Example 1, except that the compositions of “monomer for initial charge”, “initiator liquid” and “monomer liquid for dropping” were changed according to the description of Table 1, respectively. I got The solid content and weight average molecular weight are as shown in Table 1.

(Method of Preparing Slurry Composition)
36 g of barium titanate powder (BET specific surface area 15 m ² / g), a polymer dispersion solution equivalent to 0.6 g in terms of copolymer (solid content) contained, 50 g of zirconia beads having a diameter of 1 mm, and zirconia beads A toluene / ethanol mixed solvent (volume ratio: 48/52) of an amount such that the content of barium titanate in the removed components is 50% by mass is placed in a polyethylene container having a volume of 100 mL, Dispersion treatment was performed for 96 hours under the conditions of room temperature and 120 r / min, using “Big Rotor BR-2” manufactured by Toray Industries, Ltd. Then, 2.8 g of polyvinyl butyral resin ("S-LEC BM-2" manufactured by Sekisui Chemical Co., Ltd .; butyralization degree 68 mol%, hydroxyl amount 31 mol%, molecular weight about 50,000) and di (2-ethylhexyl) phthalate 0. Toluene / ethanol mixed solvent (volume ratio: 56 g), 0.2 g of alkyl imidazoline (“homogen L-95” manufactured by Kao Corporation), and an amount of barium titanate of 30% by mass with respect to the slurry composition 48/52) were added to the container, and dispersion treatment was performed for 2 hours at room temperature and 120 r / min using the table-top type ball mill. The zirconia beads were removed by 200 mesh nylon filtration to obtain a slurry composition.

(Evaluation of dispersibility and sheet strength)
Measurement of particle size (D50 and D90) and evaluation of sheet strength were performed using the obtained slurry composition. The results are shown in Table 2.

As shown in Table 2, the slurry compositions of Examples 1 , 3 to 13, 15 to 17 and Reference Examples 2 and 14 have better dispersibility than Comparative Examples 2 and 3, and Examples 1 , 3 to 13 , 15 The ceramic sheet obtained from the slurry composition of -17 and the reference examples 2 and 14 showed the intensity | strength superior to that of comparative example 1-3.

  As described above, the present invention is useful, for example, in the process of producing a slurry composition containing a basic inorganic pigment in a non-aqueous solvent and the process of producing a ceramic sheet.

Claims (8)

The structural unit (a) represented by the formula (1), the structural unit (b) represented by the formula (2), and the structural unit (c) represented by the formula (3)
The mass ratio [(c) / (b)] of the constituent unit (c) to the constituent unit (b) is more than 0.7 and not more than 7.5,
The content of the structural unit (a) is 8% by mass or more and 35% by mass or less,
The content of the structural unit (b) is 10% by mass or more and less than 55% by mass,
Content of structural unit (c) is more than 30 mass% and 58 mass% or less ,
A high inorganic pigment for use in a non-aqueous solvent, comprising a copolymer having a weight average molecular weight of 1,000 to less than 50,000 (excluding a copolymer containing a constitutional unit derived from a methacrylate monomer having an amino group) Molecular dispersant.

[In formula (1), R ¹ , R ² and R ³ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ¹ is selected from OH and O ^- M ⁺ M 1 represents at least one type, and M ⁺ represents a cation. ]

[In formula (2), R ⁴ , R ⁵ , R ⁶ and R ⁸ are the same or different, and represent at least one selected from a hydrogen atom, a methyl group and an ethyl group, and R ⁷ has 2 or more and 4 or less carbon atoms] And X ² represents at least one selected from an oxygen atom and NH, n represents an average addition mole number, and is 1 or more and 140 or less. ]

[Wherein, in the formula (3), R ⁹ , R ¹⁰ and R ¹¹ are the same or different and each represents at least one selected from a hydrogen atom, a methyl group and an ethyl group, and X ⁴ is at least one selected from an oxygen atom and NH] R ¹² and R ¹³ each represent a hydrocarbon group having 1 to 30 carbon atoms. ] The polymer dispersant for inorganic pigments according to claim 1 , wherein n is 10 or more and 140 or less in the formula (2) . The number of carbon atoms of R ¹² and R ¹³ in Formula (3) is 5 or more and 30 or less, the inorganic pigment for polymeric dispersing agent according to claim 1 or 2. The inorganic pigment according to any one of claims 1 to 3 , wherein the mass ratio [(c) / (b)] of the structural unit (c) to the structural unit (b) is more than 0.7 and 2.2 or less. Polymeric dispersant. The inorganic pigment polymer dispersant according to any one of claims 1 to 4 , wherein the inorganic pigment is a composite oxide. The slurry composition containing a non-aqueous solvent, an inorganic pigment, and the polymeric dispersing agent for inorganic pigments in any one of Claims 1-5 . The slurry composition according to claim 6 , further comprising a binder resin. The slurry composition according to claim 6 or 7 , wherein a content of the copolymer derived from the polymer dispersant for an inorganic pigment with respect to 100 parts by mass of the inorganic pigment is 10 parts by mass or less.