WO2010143554A1 - Dispersant for pigment and use thereof - Google Patents

Abstract

Disclosed is a dispersant for pigments composed of (meth)acrylic acid (co)polymers or a dispersant for various inorganic particles, which has high dispersion stabilizing effect and is capable of stably dispersing pigments and various inorganic particles for a long time, while suppressing an increase of viscosity or a decrease of pH of slurry thereof over time and thus maintaining good fluidity of the slurry. Conventional slurry of an inorganic pigment that has a small particle size is likely to have an increased slurry viscosity since the interaction between the particles is strong due to increased surface areas and thus causes aggregation of the particles. Specifically disclosed is a dispersant for a pigment which is composed of a partially neutralized product of (A) a polymer of (a) an α,β-unsaturated carboxylic acid monomer or (B) a copolymer that is composed of 80-99% by mole of a unit of (a) the α,β-unsaturated carboxylic acid monomer and 1-20% by mole of another unit that is composed of either (b) a (meth)acrylate ester monomer and/or (c) a (meth)acrylate ester monomer of a polyalkylene glycol (with (a) + (b) + (c) being 100% by mole). The dispersant for a pigment is characterized in that ammonia or an organic amine is used as a neutralizing agent.

Description

Dispersant for pigment and use thereof

The present invention relates to a pigment and a dispersant for various inorganic particles. More preferably, it is a dispersing agent for calcium carbonate, and when used to produce a high-concentration pigment slurry having a solid content exceeding 70%, or particularly a pigment slurry having a small particle size, the dispersion stabilizing effect is high, and the particulate form (Meth) acrylic acid (co) can be dispersed while maintaining good fluidity, and can be stably dispersed over a long period of time while suppressing increase in slurry viscosity and pH decrease over time. A dispersant for a pigment of a polymer is provided.

Conventionally, as a dispersant for stably dispersing inorganic pigments such as calcium carbonate, kaolin, satin white, titanium oxide, and talc in water, homopolymers of acrylic acid (salt) and acrylic acid (salt) and other co-polymers are used. Copolymers with polymerizable monomers are known.
In Patent Document 1 (Japanese Patent Application Laid-Open No. 54-82416), a pigment is dispersed with a dispersant composed of a polycarboxylic acid (salt). In Patent Document 2 (Japanese Patent Laid-Open No. 49-130915), a dispersant comprising a monomer containing a carboxylic acid (salt) and a copolymer of a (meth) acrylic acid ester monomer having 1 to 4 carbon atoms. The pigment is dispersed. In Patent Document 3 (Japanese Patent Application Laid-Open No. 2005-307023), a monomer containing a carboxylic acid (salt) and a part of terminal groups in a copolymer of other monomers are derived from an alcohol having 1 to 3 carbon atoms. The pigment is dispersed with a dispersant that is a functional group.

However, in recent years, there has been a demand for higher concentration dispersion and fine particle dispersion as compared with the prior art, and the suppression of thickening over time with respect to inorganic pigment slurries has been demanded more than ever.
In particular, an inorganic pigment having a small particle size tends to increase the slurry viscosity because the surface area increases and the interaction between particles becomes strong and the particles tend to aggregate.
In addition, the slurry obtained in the aqueous system must maintain a high pH value because spoilage progresses due to the propagation of germs in a neutral or lower region and the commercial value is impaired.

In response to such a demand, satisfactory performance has not been obtained with the conventional dispersants as described above. For example, a dispersant comprising a polycarboxylic acid (salt) described in Patent Document 1 or a monomer containing a carboxylic acid (salt) described in Patent Document 2 and having 1 to 4 carbon atoms (meth) In the dispersant composed of a copolymer with an acrylate monomer, it is difficult to say that the increase in dispersion viscosity over time is sufficiently suppressed, and the inorganic pigment dispersant described in Patent Document 3 However, the resin structural unit and the neutralizing agent are not particularly optimized, and it is difficult to say that they are well suited for dispersion stabilization as an inorganic pigment dispersant, and there is no description regarding pH.

JP 54-82416 A JP 49-130915 A Japanese Patent Laid-Open No. 2005-307023

An object of the present invention is to provide a dispersant that is excellent in the effect of stabilizing dispersion over time of a high-concentration inorganic pigment slurry having a small particle size and the effect of suppressing the decrease in slurry pH, which is required for a dispersant in recent years, in a high pH region. It is in.

As a result of intensive studies to solve the above problems, the present inventors have found that a dispersant having the following constitution is used for dispersing inorganic pigments, particularly calcium carbonate, despite its low pH. Surprisingly, it has been found that not only can the dispersion slurry be maintained in the strong alkali region, but also stability over time, fluidity of the slurry, and filterability are excellent, and the present invention has been achieved.

That is, the first of the present invention is the polymer (A) of the α, β-unsaturated carboxylic acid monomer (a) or the α, β-unsaturated carboxylic acid monomer (a) units 80 to 99. 1% to 20% by mole of (meth) acrylic acid ester monomer (b) and polyalkylene glycol (meth) acrylic acid ester monomer (c) or one or both units (however, (a) + (B) + (c) = 100 mol%) of the partially neutralized product of the copolymer (B), wherein 20 to 80 mol% of the acid groups are partially ammonia or organic amine A dispersant for inorganic pigments having a pH of 6.0 or less, which is neutralized.
The second of the present invention is the pigment dispersant according to the first invention, wherein the inorganic pigment is calcium carbonate.
In the third aspect of the present invention, the monomer (b) unit constituting the copolymer (B) is a (meth) acrylic acid ester having 1 to 8 carbon atoms, and the monomer (c) unit is The dispersant for calcium carbonate according to the second invention, which is a (meth) acrylic acid ester of a polyalkylene glycol represented by the general formula (I).

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an ethylene group or a propylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents a number of 0 to 4, and n represents 2 to 10)
The fourth or the present invention is characterized in that the acid group in the monomer (a) unit of the polymer (A) or copolymer (B) is in the form of an organic amine salt. It is a dispersing agent for calcium carbonate as described in three inventions.
The fifth aspect of the present invention is a polymer (A) or copolymer (B) having a weight average molecular weight (Mw) of 4000 to 8000 by gel permeation chromatography using polyacrylic acid as a reference substance, The dispersant for calcium carbonate according to any one of the second to fourth inventions, wherein Mw / Mn (weight average molecular weight / number average molecular weight) is 2.7 or less.
The sixth aspect of the present invention is the dispersant for calcium carbonate according to any one of the second to fifth aspects, which is a copolymer (B).
In the seventh aspect of the present invention, the monomer (a) unit constituting the copolymer (B) is acrylic acid, the monomer (b) unit is butyl acrylate, and the monomer (c) unit. Is a dispersant for calcium carbonate according to any one of the second to sixth inventions, wherein R ² in the general formula (1) is a polypropylene glycol mono (meth) acrylate having a propylene group.
The eighth aspect of the present invention is the dispersant for calcium carbonate according to any one of the second to seventh aspects, wherein the organic amine is monoethanolamine.
A ninth aspect of the present invention is a calcium carbonate dispersion having a pH of 9.5 or higher, which is prepared by wet grinding using the calcium carbonate dispersant according to any one of the second to eighth aspects.
The tenth aspect of the present invention is the calcium carbonate dispersion according to the ninth aspect, in which the calcium carbonate is heavy calcium carbonate.

The (meth) acrylic acid (salt) -based (co) polymer of the present invention is mainly used as a dispersant for inorganic pigments such as calcium carbonate, kaolin, satin white, titanium oxide, talc, calcium phosphate, cement and gypsum. Although effective, it is particularly effective when used in calcium carbonate.
That is, when a calcium carbonate dispersion is prepared using a calcium carbonate dispersant comprising the (meth) acrylic acid (salt) -based (co) polymer of the present invention, the calcium carbonate concentration is high even when the calcium carbonate concentration is high. Even when the particle size of the particles is extremely small, the viscosity is low and the handling is excellent, and the viscosity of the dispersion does not increase over time, so that a low viscosity can be maintained over a long period of time, and there is no aggregation over time. Can be obtained smoothly.
In addition, by adjusting the calcium carbonate dispersion using the calcium carbonate dispersant comprising the (meth) acrylic acid (salt) -based (co) polymer of the present invention, a low-viscosity dispersion as described above can be obtained. In addition, it is possible to obtain a calcium carbonate dispersion having excellent handling properties such as fluidity and filterability. Furthermore, the pH of the calcium carbonate dispersion can maintain a strong alkali region that can suppress bacterial growth for a long period of time. It is particularly useful because it can.
The dispersant for calcium carbonate of the present invention can be effectively used as a dispersion stabilizer for calcium carbonate used in the paper industry, plastics, rubber, paints, inks, adhesives, sealants, etc., taking advantage of the above-described properties. .

Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, examples of the α, β-unsaturated carboxylic acid (a) include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and citraconic acid. Phthalic anhydride or itaconic anhydride may be half-esterified with alkyl alcohol. These may be used alone or in combination of two or more.
Of these, preferred is (meth) acrylic acid. In the present invention, (meth) acrylic acid means acrylic acid or methacrylic acid. More preferred is acrylic acid because of the stability of the slurry and ease of polymerization.

The (meth) acrylic acid ester monomer (b) of the present invention includes linear, branched and cyclic alkyl (meth) acrylates having an alkyl group of 1 to 20 carbon atoms: for example, (meth) acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic Examples include cyclohexyl acid and isobornyl (meth) acrylate.
Further, hydroxyalkyl (meth) acrylates: for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ω-hydroxy (meth) acrylate And polyalkylene glycol (n = 2 to 30).
Further, 3-sulfopropyl (meth) acrylate, mono (2-hydroxyethyl acrylate) acid phosphate, mono (2-hydroxyethyl methacrylate) acid phosphate, mono (2-hydroxypropyl acrylate) acid phosphate, mono (3-hydroxy Examples also include sulfonic acid and phosphoric acid group-containing (meth) acrylic acid esters such as ethyl acrylate) acid phosphate and mono (3-hydroxyethyl methacrylate) acid phosphate.
From the viewpoint of the dispersibility of calcium carbonate and the stability of the slurry, alkyl (meth) acrylates having 1 to 8 carbon atoms are preferred, and butyl acrylate is more preferred.

As the monomer (c) of the (meth) acrylic acid ester of polyalkylene glycol, those represented by the following general formula (1) are preferable.

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an ethylene group or a propylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents a number of 0 to 4, and n represents 2 to 10)
The molecular weight of the polyalkylene glycol chain is preferably from 100 to 2,000. More preferably, it is a polypropylene glycol mono (meth) acrylate in which R2 in the general formula (1) is a propylene group.

In the present invention, other monomers can be copolymerized as long as the physical properties of the copolymer are not impaired. Such a monomer is not particularly limited. For example, an aromatic ethylenically unsaturated monomer such as an amide-containing ethylenically unsaturated monomer: (meth) acrylamide or N-methylol (meth) acrylamide: Styrenes such as styrene, α-methylstyrene, vinyltoluene, hydroxystyrene, vinylnaphthalene and the like, sulfonic acid group-containing monomers: (meth) allylsulfonic acid, styrenesulfonic acid, α-methylstyrenesulfonic acid, isoprenesulfone Acid, vinyltoluenesulfonic acid, (meth) allyloxybenzenesulfonic acid, (meth) allyloxy-2-hydroxypropylsulfonic acid, bis (3-sulfopropyl) itaconate, and the like.

The dispersant of the present invention includes a polymer (A) comprising the monomer (a) or a copolymer comprising the monomer (a) and the monomer (b) and / or the monomer (c) ( B) can be used. The composition of the copolymer (B) is such that (a) is 80 to 99 mol%, (b) and / or (c) is 1 to 20 mol% ((a) + (b) + (c) = 100 mol) %). The copolymer (B) is preferred from the balance of calcium carbonate dispersibility, slurry stability, fluidity and filterability. In copolymer (B), when (b) and / or (c) is less than 1 mol%, the above balance is not sufficient, and when it exceeds 80 mol%, the stability in the high pH region becomes insufficient. .

The production method of the polymer (A) or copolymer (B) of the present invention is not particularly limited, and any of solution polymerization, emulsion polymerization, suspension polymerization and the like can be used. Of these, solution polymerization is preferred.
Solvents for solution polymerization include water, alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, etc.), ethers (tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, heptane, etc.), aromatic Examples include hydrocarbons (toluene, xylene, etc.) and mixtures thereof. Among these, preferred is a mixed solvent of alcohol and water, and more preferred is a mixed solvent of isopropanol and water.
The mixing ratio of the mixed solvent of alcohol and water is preferably alcohol / water = 90/10 to 10/90, more preferably 70/30 to 30/70 in terms of mass ratio. When the ratio of water exceeds 90% by mass, some of the monomers belonging to the monomer (b) and / or (c) are difficult to dissolve, which is not preferable. On the other hand, if the ratio of water is less than 10% by mass, it is not preferable because alcohol needs to be replaced with water when used as a dispersant, which is costly and labor intensive.

As the radical polymerization initiator used for the production of the polymer (A) or copolymer (B) of the present invention, a peroxide radical polymerization initiator generally used can be used. Specific examples include persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,5- Hydroperoxides such as dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, water-soluble peroxides such as hydrogen peroxide; methyl ethyl ketone peroxide, cyclohexanone peroxide Ketone peroxides such as oxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxy) -p-diisopropylbenzene, α, α '-Bi Dialkyl peroxides such as bis (t-butylperoxy) -n-diisopropylhexyne, t-butylperoxyacetate, t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxy Peroxyesters such as isophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, n-butyl-4,4-bis (t-butylperoxy) ) Peroxyketals such as valerate, 2,2-bis (t-butylperoxy) butane, and oil-soluble peroxides such as diacyl peroxide such as dibenzoyl peroxide.
The above peroxide-based radical polymerization initiators may be used alone or in combination of two or more. Of the peroxide radical polymerization initiators described above, hydrogen peroxide and persulfate peroxides having a low decomposition temperature that can easily control the molecular weight are more preferable.

The amount of the radical polymerization initiator used is not particularly limited, but is 0.10 to 15% by mass, particularly 0 based on the total mass of all monomers used for the production of the polymer (A) or the copolymer (B). It is preferably used in a proportion of 1 to 5% by mass. If the amount of radical polymerization initiator used is too small, the polymerization rate decreases, while if too large, the polymer (A) or copolymer (B) remains in the polymer (A) or copolymer (B) even after polymerization, and the stability is impaired. Or may adversely affect the performance as a dispersant.

In producing the polymer (A) or the copolymer (B), an appropriate amount of a chain transfer agent may be added to the polymerization system in order to adjust the molecular weight. Usable chain transfer agents include, for example, sodium phosphite, sodium hypophosphite, sodium bisulfite, mercaptoacetic acid, mercaptopropionic acetic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecyl mercaptan, thio Examples thereof include glycerol and thiomalic acid.

The polymerization temperature for producing the polymer (A) or copolymer (B) is preferably 50 to 150 ° C, more preferably 70 to 100 ° C. When the polymerization temperature is lower than 50 ° C., the copolymerization rate tends to decrease. On the other hand, when the polymerization temperature is higher than 150 ° C., the monomer (a) causes a dimerization reaction or the monomers (b) and (c) Pyrolysis. Moreover, there exists a possibility that the thermal decomposition of the produced | generated polymer (A) or copolymer (B) itself may arise.
The polymerization time is preferably about 3 to 20 hours, particularly about 3 to 10 hours.

The above-described polymerization reaction for producing the polymer (A) or the copolymer (B) is performed at least 40 mol% or more of the acid groups of the monomer (a) before polymerization and at the polymerization stage, and more preferably 70 to 100%. The polymerization is preferably carried out so that the mol%, particularly 90 to 100 mol%, is in an unneutralized state from the viewpoint that the polymerization reaction proceeds uniformly.

The weight average molecular weight (Mw) of the polymer (A) or copolymer (B) (measured by gel permeation chromatography using polyacrylic acid as a standard substance) is usually 2,000 to 10,000. The preferred range is 4,000 to 8,000. When the weight average molecular weight (Mw) is less than 2000, the adsorption power to calcium carbonate with time decreases, whereas when the Mw exceeds 10,000, the calcium carbonate particles are bonded (crosslinked), resulting in a calcium carbonate slurry. This is not preferable because it causes thickening over time.
Further, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably 2.7 or less, more preferably 2.5 or less, More preferably, it is 2.4 or less. When Mw / Mn exceeds 2.7, the amount of low molecular weight components having low adsorptivity to calcium carbonate with time increases, and at the same time, high molecular weight components that cause the bonding (crosslinking) of calcium carbonate particles to each other. This also increases the amount of water, and as a result, it tends to cause thickening of the calcium carbonate slurry over time, which is not preferable.

As a method for obtaining the (meth) acrylic (co) polymer salt of the present invention, from the solution containing the polymer (A) or copolymer (B) obtained above, if necessary, distillation, vacuum distillation, drying, etc. After removing the organic solvent by the above operation, the carboxyl group of the monomer unit (a) constituting the polymer (A) or copolymer (B) is neutralized with a basic compound to form a salt. It can be obtained by water-solubilization.
The basic compound used for the neutralization is ammonia or an organic amine.
The degree of neutralization is 20 to 80 mol%, preferably 30 to 50 mol% of the carboxyl group of the monomer unit (a) by at least one basic compound selected from ammonia or organic amine. Further, the neutralization is carried out so that 20 to 80 mol% of the carboxyl groups of the structural unit (a) are free acid groups, and thereby good dispersibility and pH with respect to the calcium carbonate slurry. It is possible to adjust a dispersant having an excellent effect of suppressing the decrease.
If necessary, several kinds of ammonia and organic amines may be used, and other basic compounds may be used in combination as long as the physical properties are not impaired.
Further, an aqueous solution of the polymer (A) and / or the copolymer (B), an aqueous ammonium salt solution or an organic amine salt aqueous solution of (A) and / or (B), and (A) and / or An aqueous solution obtained by neutralizing (B) with another basic compound can also be blended so as to have the neutralization ratio as described above.

When the ratio of ammonium salt and organic amine salt in the polymer (A) and / or copolymer (B) of the present invention (referred to as (meth) acrylic acid-based (co) polymer in the present invention) exceeds 80% Further, it is not preferable because dispersibility deteriorates, and it is not preferable industrially from the viewpoint of cost and odor. On the other hand, it is not preferable that these proportions are less than 20% because the effect of suppressing the decrease in pH over time of the calcium carbonate slurry is weakened.
Moreover, when the neutralization rate of the acid group in the (meth) acrylic acid-based (co) polymer is less than 20%, the pH immediately after the pulverization of the calcium carbonate slurry is lowered, and the pH over time as described above. This is not preferable because the effect of suppressing the decrease is weakened.
In addition, it is necessary to adjust the basic compound so that the dispersant of the present invention has a pH of 6.0 or lower. When the pH exceeds 6.0, physical properties such as fluidity and filterability of the dispersion slurry are insufficient.

The basic compound used in the present invention is ammonia or an organic amine, and the organic amine includes a primary amine, a secondary amine, and a tertiary amine.
As the primary amine and the secondary amine, for example, in the case of an aliphatic amine, a lower alkylamine having an alkyl group having 1 to 20 carbon atoms, methylamine, ethylamine, n-butylamine, octylamine, dodecylamine, dimethylamine, diethylamine, diamine, In addition to butylamine, dioctylamine, didodecylamine, etc., alkanolamines (monoethanolamine, diethanolamine, etc.), (poly) alkylenepolyamines (ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine), or their derivatives (alkyl) Compound, alkylene oxide adduct) and the like.
In the case of a tertiary amine, a tertiary amine or a quaternary ammonium salt obtained by quaternizing it is included. Such amines include aliphatic amines (trimethylamine, triethylamine, isopropylethylamine, octyldimethylamine, dodecyldimethylamine, etc.), alicyclic amines (N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine). Etc.), and tertiary amines such as aromatic amines (N, N-dimethylaniline, N, N-diethylaniline, etc.), and quaternary ammonium salts obtained by quaternizing them with dialkyl carbonate or the like.
As the basic compound, ammonia has a strong irritating odor, and is preferably an organic amine, more preferably an alkanolamine or a lower alkylamine. Monoethanolamine is particularly preferred from the viewpoint of low odor and environmental friendliness.

Examples of other basic compounds that can be used in combination to neutralize the acid group in the (meth) acrylic acid (based) copolymer include alkali metal hydroxides and alkaline earth metal hydroxides. As the alkali metal, lithium, sodium, potassium and the like are preferable, and as the alkaline earth metal, calcium, magnesium, barium and the like are preferable. These may be used alone or as a mixture of two or more. Of these, sodium hydroxide is particularly preferred.
However, the use of only alkali metal hydroxides or alkaline earth metal hydroxides should be avoided because the pH of the dispersion slurry decreases.

The dispersant of the present invention exhibits a particularly excellent effect on inorganic pigments, particularly calcium carbonate. The amount of the dispersant of the present invention is usually 0.01 to 10% by mass, preferably 0.05 to 5% by mass, and particularly preferably 0.1 to 3% by mass with respect to calcium carbonate. If it is less than 0.01% by mass, the dispersion effect is insufficient, and if it exceeds 10% by mass, the dispersion tends to increase in viscosity.
The pH of the calcium carbonate dispersion of the present invention is preferably 8.0 or higher. If it is less than this, miscellaneous bacteria will propagate easily in a slurry, and it will become a cause of rot odor or performance will fall. More preferably, the pH is 9.5 or higher.

As the calcium carbonate used in the present invention, light calcium carbonate, colloidal calcium carbonate, heavy calcium carbonate and the like are exemplified, but heavy calcium carbonate is preferable from the viewpoint of cost and the like. When coarse powder heavy calcium carbonate of about 400 to 40 mesh (about 0.04 mm to 0.4 mm) is used, the performance of the dispersant for calcium carbonate of the present invention is maximized.

The dispersant of the present invention exhibits an excellent effect as a dispersant for various inorganic particles such as silica particles, ceria (cerium oxide) particles, and alumina particles in addition to the above inorganic pigment dispersant.

Generally, silica dispersions are used in papermaking applications, metal processing applications, fiber applications, paint applications, optical material applications, and chemical mechanical polishing (hereinafter referred to as “CMP”) applications.

CMP is a technique used for flattening the surface of a wafer in the manufacturing process of semiconductor devices. A polishing pad is attached to a polishing surface plate, the polishing pad surface is immersed in an abrasive, and the surface to be polished is pressed and pressed. In this state, the polishing surface plate is rotated, and the convex portions are removed and smoothed by mechanical friction between the abrasive and the convex portions of the object to be polished.
As an abrasive in this CMP, one obtained by dispersing silica particles or ceria particles using a dispersant is known.

In the case of producing a dispersion of silica particles, it is preferable to use 0.01 to 2.0 parts by weight of a dispersant in solid content with respect to 100 parts by weight of silica particles.

The average particle size of the silica particles may be appropriately set according to the purpose, but is preferably 0.005 to 0.5 μm when used as a CMP abrasive.
By setting the average particle size to 0.005 μm or more, when the dispersion is used in the CMP process, the polishing rate is high, and by setting the average particle size to 0.5 μm or less, sedimentation of particles can be suppressed. .
The blending amount of the silica particles is preferably 0.1 to 50% by weight with respect to the dispersion. By setting the content to 0.1% by weight or more, when the dispersion is used in the CMP process, the polishing rate becomes high. On the other hand, by setting the content to 50% by weight or less, aggregation of particles can be suppressed.

On the other hand, ceria dispersions are used for exhaust gas purification catalyst applications, gas sensor applications, optical material applications, and CMP applications.

In the case of producing a dispersion of ceria particles, it is preferable to use 0.01 to 2.0 parts by weight of a dispersant in solid content with respect to 100 parts by weight of ceria particles.

The average particle diameter of the ceria particles may be appropriately set according to the purpose, but is preferably 0.01 to 1.0 μm when used as a CMP abrasive.
By setting the average particle size to 0.01 μm or more, when the dispersion is used in the CMP process, the polishing rate is high, and by setting the average particle size to 1.0 μm or less, particle sedimentation can be suppressed. .
The blending amount of ceria particles is preferably 0.1 to 50% by weight with respect to the dispersion. By setting the content to 0.1% by weight or more, when the dispersion is used in the CMP process, the polishing rate becomes high. On the other hand, by setting the content to 50% by weight or less, aggregation of particles can be suppressed.

Alumina dispersions are used for papermaking, metal processing, textiles, paints, optical materials and ceramics.

In the case of producing a dispersion of alumina particles, it is preferable to use 0.01 to 5.0 parts by weight of a dispersant in solid content with respect to 100 parts by weight of alumina particles.

The average particle diameter of the alumina particles may be appropriately set according to the purpose, but is preferably 0.01 to 5.0 μm.
By making the average particle diameter 0.01 μm or more, it becomes advantageous in terms of cost. On the other hand, by making it 5.0 μm or less, the ceramic becomes excellent in toughness when producing ceramic from alumina particles. .
The blending amount of the alumina particles is preferably 40 to 85% by weight with respect to the dispersion. By setting the content to 40% by weight or more, the ceramic can be excellent in dimensional accuracy when the ceramic is produced from the alumina particles. On the other hand, when the content is 85% by weight or less, the dispersion liquid has a low viscosity and is easy to handle.

The dispersion containing alumina particles obtained by using the dispersant of the present invention can be used for various applications, and can be particularly preferably used as a dispersion for producing a ceramic.
In this case, it can be used together with ceramic raw material powder other than alumina.
As the ceramic raw material powder, inorganic powder can be used, metal oxides such as titania, magnesia and zirconia, metal carbides such as silicon carbide, nitrides such as aluminum nitride and silicon nitride, carbonates such as calcium carbonate and barium carbonate. Examples thereof include salts and barium titanate.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.
In the following examples, “%” and “part” indicate “% by mass” and “part by mass”, respectively.
In the following examples, the measurement of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the (meth) acrylic acid-based (co) polymer, and the measurement or evaluation of the dispersion characteristics with respect to calcium carbonate are as follows. I went.

[1] Weight average molecular weight (Mw) and number average molecular weight (Mn) of (meth) acrylic acid copolymer
100 μL of a sample collected from the neutralized (meth) acrylic acid (co) polymer aqueous solution obtained in the production example and adjusted to a concentration of 0.4 wt / vol% was added to a column [manufactured by Tosoh Corporation]. Column “TSKgel G3000PWXL-TSKgel G4000PWXL-TSKgel G6000PWXL” (each having a length of 300 mm and an inner diameter of 7.8 mm connected in series) was injected at a column temperature of 35 ° C. with an eluent [0.1 M NaCl, 0.1 M phosphate buffer (phosphoric acid 1N dihydrate 7.70 g, phosphoric acid 2N 12 hydrate 36.3 g, NaCl 8.63 g, deionized water 1476.4 g)] at a flow rate of 0.8 mL / A water-based gel permeation chromatograph (GPC) method that elutes the components adsorbed on the column through Acrylic acid-based (co) weight average molecular weight (Mw) of the polymer and the number average molecular weight (Mn) were measured. At that time, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the (meth) acrylic acid (co) polymer are the weight average molecular weight (Mw), the number average molecular weight (Mn), and the peak top molecular weight (Mp). ) With clear polyacrylate (with molecular weights of 9 million, 5550, 1.14 million, 440,000, 131200, 7900, 2400 manufactured by AMERICA POLYMER STANDARDS CORP.) It was calculated from the calibration curve.

[2] Dispersion characteristics with respect to calcium carbonate [2-a] Wet grinding treatment of heavy calcium carbonate Disperser [Sand grinder (manufactured by Igarashi Kikai)], coarse powdered heavy calcium carbonate [No. A manufactured by Maruo Calcium Co., Ltd. "Heavy coal" (42 mesh residue 1% or less, 100 mesh residue 90% or more)] is filled with 900 g and alumina beads (average diameter 1.0 mm; grinding media) in an amount of 2970 g. A neutralized (meth) acrylic acid-based (co) polymer aqueous solution was added in an amount of 0.75% by mass as a solid content of the (meth) acrylic acid-based (co) polymer based on 900 g of heavy calcium carbonate. And then adding distilled water to prepare a heavy calcium carbonate slurry with a heavy calcium carbonate concentration of 75 mass% in the disperser, and then stirring the stirring blade in the disperser to 1000 rp. Rotated at a rotational speed was 50 min wet grinding process.

[2-b] Evaluation of fluidity of heavy calcium carbonate slurry during wet pulverization treatment The fluidity of heavy calcium carbonate slurry during the wet pulverization treatment of [2-a] was evaluated according to the following evaluation criteria.
○: There is no adhering matter to the stirring blades of the disperser from the initial stage to the late stage of the grinding, and the fluidity is extremely excellent.
Δ: There are few deposits on the stirring blades of the disperser from the initial stage to the late stage, and the fluidity is excellent.
X: Throughout the initial stage to the late stage (especially at the initial stage of pulverization), there is a considerable amount of deposits on the stirring blades of the disperser, and the fluidity (particularly the fluidity at the initial stage of pulverization) is low.

[2-c] Average particle size of heavy calcium carbonate particles in heavy calcium carbonate slurry Light scattering intensity is appropriate for the heavy calcium carbonate slurry after wet grinding obtained by the wet grinding treatment of [2-a] above. In a heavy calcium carbonate slurry using a laser light scattering particle size distribution meter (“LA-920 type” manufactured by HORIBA, Ltd.) The average particle size of the heavy calcium carbonate particles was measured.

[2-d] Filterability of Heavy Calcium Carbonate Slurry Using the total amount of wet calcium pulverized slurry and alumina beads obtained by the wet pulverization treatment of [2-a] above as a sample, , Pour flatly into a cylindrical filtration apparatus (filter part is 25 cm in diameter) with a 200-mesh filter cloth, and measure the amount of filtration (g) of the slurry after 5 minutes from the start of filtration. Filterability was evaluated according to the evaluation criteria.
○: 40% by mass or more of the sample passes through the filter cloth, and the filterability is extremely excellent.
(Triangle | delta): 30 mass% or more and less than 40 mass% of a sample passes a filter cloth, and is excellent in filterability.
X: Less than 30% by mass of the sample passes through the filter cloth, and the filterability is poor.

[2-e] Stability over time of heavy calcium carbonate slurry The filtrate obtained through the above [2-d] and passed through the 200th mesh filter cloth was used as a sample, and the concentration of heavy calcium carbonate in the sample was When the concentration was higher than 75% by mass, the sample was diluted with distilled water to prepare a sample having a heavy calcium carbonate concentration of 75% by mass. The sample was kept standing at a temperature of 25 ° C., and the viscosity at the beginning (immediately after preparation of the sample) and after 7 days of standing was measured using a BM viscometer (manufactured by Tokimec) at a temperature of 25 ° C. 3 rotors or # 4 rotor (# 3 rotor is used when the sample viscosity is 1000 mPa · s or less, # 4 rotor is used when the sample viscosity is 1000 to 1000 mPa · s) and the rotational speed is 60 rpm. The viscosity of the heavy calcium carbonate slurry was measured.

[2-f] pH of heavy calcium carbonate slurry
The slurry with a heavy calcium carbonate concentration of 75% by mass adjusted in [2-e] above was used as a sample, and the pH value at the beginning (immediately after preparation of the sample) and after 7 days of standing was adjusted to a temperature of 25 ° C. In the state, it was measured using a pH meter (“D-12 type” manufactured by Horiba, Ltd.) and evaluated according to the following evaluation criteria.
○: The pH value at the beginning (immediately after preparation of the sample) and after 7 days of standing are both 9.5 or more.
X: The pH value at the beginning (immediately after preparation of the sample) and after 7 days of standing are both lower than 9.5.

○ Production Example 1 [Production of (meth) acrylic acid copolymer (B-1)]
(1) A four-necked flask was charged with 114.8 g of isopropanol and 138.0 g of deionized water, and the internal temperature was raised to 78 ° C. while rotating and stirring the contents of the flask at 200 rpm. After the internal temperature became constant, 0.87 g of ammonium persulfate and 4.05 g of deionized water were added all at once. One minute later, 232.2 g of acrylic acid, 37.8 g of butyl acrylate, and deionized water 44 A monomer mixed aqueous solution consisting of 1.6 g (total 314.6 g) and a polymerization initiator aqueous solution consisting of 7.83 g ammonium persulfate and 56.5 g deionized water (total 64.3 g) were continuously added over 6 hours each. Supplied to. After completion of continuous supply, the inner temperature was maintained at 78 ° C. and aging was performed for 1.5 hours, and then the inner temperature was cooled to 50 ° C. When 500 mg of the reaction solution was collected and analyzed by gas chromatography, unreacted acrylic acid and butyl acrylate were not detected.
(2) Next, the pressure in the flask was controlled to 80 mmHg by a pressure controller and a vacuum pump, and isopropanol was continuously distilled off. The amount of deionized water lost to azeotrope with isopropanol was added to the flask.

(3) Subsequently, the contents of the flask ((meth) acrylic acid copolymer, hereinafter referred to as “B-1”) were heated at 155 ° C. for 45 minutes and weighed, and then in the heated aqueous solution. The amount of the (meth) acrylic copolymer was measured, and deionized water was added based on the measured value to prepare an aqueous solution having a solid content concentration (B-1 content) of 45%.
(4) Using an aqueous solution having a solid content concentration (B-1 content) of 45% obtained in (3) above, the weight average molecular weight (Mw) and number average of B-1 contained in the aqueous solution When the molecular weight (Mn) was measured by the above method [1], the weight average molecular weight (Mw) = 5200, the number average molecular weight (Mn) = 2300, and the molecular weight distribution (Mw / Mn) = 2.26.

○ Production Example 2 [Production of (meth) acrylic acid copolymer (B-2)]
(1) In Production Example 1 (B-1) (1), the monomer mixed aqueous solution was mixed with 220.3 g of acrylic acid and polypropylene glycol monoacrylate [number of added moles of polypropylene oxide n = 3, terminal hydroxyl group (R ³ = H)] The same polymerization operation as in Production Example 1 (1) was carried out except that the monomer mixture was changed to 49.7 g and 44.6 g of deionized water (total 314.6 g). After completion of the reaction, 500 mg of the reaction solution was collected and analyzed by gas chromatography. As a result, unreacted acrylic acid and polypropylene glycol monoacrylate were not detected.
(2) Next, the same operation as in B-1 (2) and (3) was performed to prepare an aqueous solution having a solid content concentration [(meth) acrylic acid copolymer content] of 45% (obtained). The (meth) acrylic acid copolymer is hereinafter referred to as “B-2”).
(3) Using an aqueous solution having a solid content concentration (B-2 content) of 45% obtained in (2) above, the weight average molecular weight (Mw) and number average of B-2 contained in the aqueous solution When the molecular weight (Mn) was measured by the above method [1], the weight average molecular weight (Mw) = 4800, the number average molecular weight (Mn) = 2300, and the molecular weight distribution (Mw / Mn) = 2.05.

○ Production Example 3 [Production of (meth) acrylic acid polymer (A-1)]
(1) In Production Example 1 (B-1) (1), the monomer mixed aqueous solution was changed to a monomer aqueous solution consisting of 270.0 g of acrylic acid and 44.6 g of deionized water (314.6 g in total). Except for the above, the same polymerization operation as in (1) of B-1 was performed. After completion of the reaction, 500 mg of the reaction solution was collected and analyzed by gas chromatography. As a result, unreacted acrylic acid was not detected.
(2) Next, the same operation as in Production Example 1 (2) and (3) was performed to prepare an aqueous solution having a solid content concentration [(meth) acrylic acid polymer content] of 45% (obtained) The (meth) acrylic acid polymer is hereinafter referred to as “A-1”).
(3) Using an aqueous solution having a solid content concentration (A-1 content) of 45% obtained in (2) above, the weight average molecular weight (Mw) and number average of A-1 contained in the aqueous solution When the molecular weight (Mn) was measured by the above method [1], the weight average molecular weight (Mw) = 5300, the number average molecular weight (Mn) = 2400, and the molecular weight distribution (Mw / Mn) = 2.21.

Using the (meth) acrylic acid-based (co) polymers (B-1), (B-2) and (A-1) obtained in Production Examples 1 to 3, neutralization shown in the following Examples According to the method, a dispersant is prepared by neutralizing some or all of the acid groups of (B-1), (B-2) and (A-1), and the method described in [2-a] above. Wet grinding of heavy calcium carbonate was performed. Then, the fluidity of the heavy calcium carbonate slurry during the wet pulverization treatment was evaluated by the above method [2-b].
Further, for the heavy calcium carbonate slurry obtained by the wet pulverization treatment, the average particle size of the heavy calcium carbonate particles contained in the slurry is measured by the method of [2-c] above, and the filterability of the slurry is determined. Evaluated by the above method [2-d], and further evaluated the temporal stability of the slurry by the above method [2-e], and finally evaluated the pH value of the slurry by the above method [2-f]. did.
The evaluation results of each example are shown in Table 1, and the evaluation results of each comparative example are shown in Table 2.

○ Example 1
Using an aqueous solution of (meth) acrylic acid copolymer B-1, the flask was cooled with ice water, and a 48% sodium hydroxide aqueous solution was supplied while measuring the pH to remove 20% of the carboxyl group derived from acrylic acid. Neutralization was further performed, and monoethanolamine was further supplied to neutralize 30% of carboxyl groups derived from acrylic acid to prepare a neutralized copolymer having a solid content concentration of 42.0% and pH = 5.0.
Using this neutralized copolymer, wet pulverization of heavy calcium carbonate was performed by the method described in [2-a] above, and the viscosity of the dispersion slurry was measured. The viscosity on the wet pulverization day was 610 mPa · s, the viscosity after 7 days was 930 mPa · s. When the median diameter of the dispersion immediately after production was measured, the median diameter was 0.604 μm, and the 1.32 μ under value was 98%. When the pH of the dispersion slurry was measured, the pH on the wet grinding day was 9.8, and the pH after 7 days was 9.8.

Example 2
Neutralization was performed in the same manner as in Example 1 except that the (meth) acrylic acid copolymer used in Example 1 was changed from B-1 to B-2. Thus, a pigment dispersant having a solid content concentration of 41.2% and a pH of 5.1 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 3
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 20% monoethanolamine and 30% 48% aqueous sodium hydroxide. Thus, a pigment dispersant having a solid content concentration of 42.1% and a pH of 5.0 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 4
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to only monoethanolamine 30%. In this way, a pigment dispersant having a solid content concentration of 42.9% and a pH of 4.4 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 5
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 30% monoethanolamine and 50% 48% aqueous sodium hydroxide. Thus, a pigment dispersant having a solid content concentration of 41.2% and a pH of 5.9 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 6
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to only monoethanolamine 50%. In this manner, a pigment dispersant having a solid content concentration of 43.0% and a pH of 5.2 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 7
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to only monoethanolamine 80%. Thus, a pigment dispersant having a solid content concentration of 43.4% and a pH of 5.9 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 8
In Example 1, neutralization was carried out in the same manner as in Example 1 except that the neutralization rate was changed to only 50% ammonia. Thus, a pigment dispersant having a solid content concentration of 40% and a pH of 4.9 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

Example 9
Neutralization was performed in the same manner as in Example 1 except that the (meth) acrylic acid-based (co) polymer used in Example 1 was changed from B-1 to A-1. In this manner, a pigment dispersant having a solid content concentration of 42.3% and a pH of 5.1 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

○ Comparative Example 1
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 97% neutralization with a 48% sodium hydroxide aqueous solution. Thus, a pigment dispersant having a solid content concentration of 40% and a pH of 8.0 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

○ Comparative Example 2
Neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 30% with monoethanolamine and 67% with 48% sodium hydroxide aqueous solution. In this way, a pigment dispersant having a solid content concentration of 40.7% and a pH of 8.1 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

○ Comparative Example 3
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 50% neutralization with a 48% sodium hydroxide aqueous solution. Thus, a pigment dispersant having a solid content concentration of 40.5% and a pH of 5.1 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

○ Comparative Example 4
In Example 1, neutralization was performed in the same manner as in Example 1 except that the neutralization rate was changed to 97.0% neutralization with monoethanolamine. In this manner, a pigment dispersant having a solid content concentration of 43.2% and a pH of 8.2 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

○ Comparative Example 5
In Example 1, the (meth) acrylic acid (co) polymer used was changed from B-1 to A-1, and the neutralization rate was 30% with monoethanolamine and 67% with 48% aqueous sodium hydroxide. % Neutralization was carried out in the same manner as in Example 1 except that the amount was changed to neutralize. Thus, a pigment dispersant having a solid content concentration of 39.9% and a pH of 8.0 was obtained. Using this neutralized polymer, wet calcium carbonate was wet pulverized by the method described in [2-a] above, and each dispersion characteristic of the dispersion slurry was evaluated.

ADVANTAGE OF THE INVENTION According to this invention, the dispersing agent for calcium carbonate useful for the dispersing agent for inorganic pigments, especially a high concentration pigment slurry, and a pigment slurry with a small particle diameter can be provided.
If such a dispersant is used, the dispersion pigment has a high stabilizing effect and can be dispersed while maintaining good fluidity in the form of fine particles, so that the viscosity and pH of the slurry over time can be increased over a long period of time. A stable dispersion is obtained. The dispersion is optimal for the paper industry, plastics, rubber, paints, inks, adhesives, sealants and the like.

Claims (10)

1. α, β-unsaturated carboxylic acid monomer (a) polymer (A), or α, β-unsaturated carboxylic acid monomer (a) unit 80-99 mol%, and (meth) acrylic acid 1 to 20 mol% of the ester monomer (b) and the (meth) acrylate monomer (c) of the polyalkylene glycol or one of the units (provided that (a) + (b) + (c) = A partially neutralized product of the copolymer (B) comprising 100 mol%), wherein 20 to 80 mol% of the acid groups are partially neutralized with ammonia or an organic amine. An inorganic pigment dispersant having a pH of 6.0 or less.
2. The pigment dispersant according to claim 1, wherein the inorganic pigment is calcium carbonate.
3. The monomer (b) unit constituting the copolymer (B) is a (meth) acrylic acid ester having 1 to 8 carbon atoms, and the monomer (c) unit is represented by the following general formula (I) The dispersant for calcium carbonate according to claim 2, which is a (meth) acrylic acid ester of polyalkylene glycol.
   

   

   (Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an ethylene group or a propylene group, R ³ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents a number of 0 to 4, and n represents 2 to 10)
4. The calcium carbonate according to claim 2 or 3, wherein the acid group in the monomer (a) unit of the polymer (A) or the copolymer (B) is in the form of an organic amine salt. Dispersant.
5. The polymer (A) or copolymer (B) has a weight average molecular weight (Mw) of 4000 to 8000 by gel permeation chromatography using polyacrylic acid as a reference substance, and Mw / Mn (weight average molecular weight / number). The dispersant for calcium carbonate according to any one of claims 2 to 4, which has an average molecular weight of 2.7 or less.
6. The dispersant for calcium carbonate according to any one of claims 2 to 5, which is a copolymer (B).
7. The monomer (a) unit constituting the copolymer (B) is acrylic acid, the monomer (b) unit is butyl acrylate, and the monomer (c) unit is R in the general formula (1). 7. The dispersant for calcium carbonate according to claim 2, wherein ² is a polypropylene glycol mono (meth) acrylate having a propylene group.
8. The dispersant for calcium carbonate according to any one of claims 2 to 7, wherein the organic amine is monoethanolamine.
9. A calcium carbonate dispersion having a pH of 9.5 or higher, which is adjusted by wet grinding using the calcium carbonate dispersant according to any one of claims 2 to 8.
10. The calcium carbonate dispersion according to claim 9, wherein the calcium carbonate is heavy calcium carbonate.