JP7486771B2 - Inorganic particle dispersion slurry and dispersant for inorganic particle dispersion slurry - Google Patents

Description

The present invention relates to an inorganic particle dispersion slurry and a dispersant for an inorganic particle dispersion slurry.

A dispersant for coated paper, which contains (I) a water-soluble salt of a copolymer containing (a) 40 to 60 mol % of acrylic acid and (b) 60 to 40 mol % of (anhydrous) maleic acid, and (II) a water-soluble salt of a copolymer containing (a) 80 to 95 mol % of acrylic acid and (b) 20 to 5 mol % of (anhydrous) maleic acid, and is characterized in that it contains 30 to 300 parts by weight of copolymer (II) per 100 parts by weight of copolymer (I), is an inorganic particle dispersion slurry consisting of inorganic particles (heavy/light calcium carbonate, kaolin, clay, aluminum hydroxide, satin white, titanium oxide, talc, or a mixture thereof) and water (Patent Document 1).

Japanese Patent Application Laid-Open No. 8-188986

The above inorganic particle dispersion slurry has a problem in that sufficient fluidity cannot be obtained when the pH (25°C) is adjusted to 1 to 6. The object of the present invention is to provide an inorganic particle dispersion slurry that has excellent fluidity even when the pH (25°C) is 1 to 6 (preferably 1 to 5, more preferably 1.7 to 4.7), and a dispersant for this slurry.

The inorganic particle dispersion slurry of the present invention is characterized in that it contains inorganic particles (A), an acid (B), a dispersant (C) and water (D),
pH (25° C.) is 1 to 6,
The gist of the present invention is that the dispersant (C) contains a polyamine compound (Y) represented by formula (1).

R ¹ to R ⁵ are at least one selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, and a group represented by H-(AO) _s - (AO is an oxyalkylene group having 2 to 3 carbon atoms, and s is an integer from 1 to 80), and at least one of R ¹ to R ⁵ is a group represented by H-(AO) _s -. n is an integer from 1 to 6, m is an integer from 0 to 2, N is a nitrogen atom, C is a carbon atom, and H is a hydrogen atom.

The inorganic particle dispersion slurry of the present invention has excellent fluidity even when the pH (25°C) is 1 to 6 (preferably 1 to 5, and more preferably 1.7 to 4.7).

The dispersant of the present invention exhibits excellent fluidity even when applied to an inorganic particle dispersion slurry having a pH (25°C) of 1 to 6 (preferably 1 to 5, and more preferably 1.7 to 4.7).

There are no particular limitations on the inorganic particles (A) as long as they can be stably dispersed in water with a pH of 1 to 6, and examples of such particles include metal oxides and carbon.

Metal oxides include aluminum oxide, silicon oxide, and titanium oxide.

Examples of carbon include graphite and carbon black.

In addition to metal oxides and carbon, the inorganic particles (A) may also include metal sulfates (calcium sulfate, barium sulfate, cerium sulfate, etc.), metal silicates (aluminum silicate, potassium silicate, calcium silicate, magnesium silicate, etc.), metals (gold, rhodium, palladium, platinum, etc.), nitrides (aluminum nitride, boron nitride, silicon nitride, etc.), and composites containing these (sepiolite, zeolite, cordierite, boehmite, imogolite, sericite, alloys, diatomaceous earth, hydrotalcite, clay, talc, mica, glass, etc.).

The content (wt%) of inorganic particles (A) is preferably 1 to 80, more preferably 10 to 70, and particularly preferably 28 to 60, based on the weight of inorganic particles (A), acid (B), dispersant (C), and water (D). Within this range, the fluidity is further improved.

There are no particular limitations on the acid (B) as long as it can adjust the pH (25°C) of the inorganic particle dispersion slurry to 1 to 6. Either an inorganic acid or an organic acid may be used, and these may be used alone or in the form of a mixture.

Inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, chromic acid, and boric acid.

Organic acids include carboxylic acids (acetic acid, trifluoroacetic acid, malic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, fumaric acid, tartaric acid, etc.) and sulfonic acids (methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfone, etc.).

Among these acids, nitric acid, boric acid and organic acids are preferred, nitric acid and carboxylic acids are more preferred, and nitric acid and acetic acid are particularly preferred.

There are no restrictions on the content (wt%) of acid (B) as long as the pH (25°C) of the inorganic particle dispersion slurry can be adjusted to 1 to 6, but based on the weight of inorganic particles (A), acid (B), dispersant (C) and water (D), it is preferably 0.1 to 5, more preferably 0.5 to 4, and particularly preferably 1.5 to 3.

The dispersant (C) contains a polyamine compound (Y) represented by formula (1), and may be one type or a mixture of multiple types.

Examples of hydrocarbon groups having 1 to 10 carbon atoms include aliphatic hydrocarbon groups having 1 to 10 carbon atoms (such as methyl, ethyl, butyl, decyl, 2-ethylhexyl, cyclohexyl, and octenyl) and aromatic hydrocarbon groups having 6 to 10 carbon atoms (such as phenyl, benzyl, and naphthyl). Of these, aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferred, and methyl, ethyl, butyl, decyl, and 2-ethylhexyl are more preferred.

In the group represented by H-(AO) _s -, AO is an oxyethylene group or an oxypropylene group, and may contain one or two types, but preferably consists of any one type.

When (AO) _s contains two kinds of AO, they may be in a random or block form, or a mixture of these.

s is an integer from 1 to 80, preferably an integer from 1 to 60, and more preferably an integer from 1 to 40.

The polyamine compound (Y) can be easily obtained by known methods (for example, alkylene oxide addition reaction between polyamine and ethylene oxide and/or propylene oxide, or alkylene oxide addition reaction and hydrolysis reaction between ketimine derivative of polyamine and ethylene oxide and/or propylene oxide). The method using ketimine derivative of polyamine is a method in which the primary amino group is protected by ketone (ketimine, i.e., imino), and the secondary amino group is selectively subjected to alkylene oxide addition reaction, and the protecting group (imino group) is removed by hydrolysis to restore the primary amino group (JP Patent Publication 1-249748, etc.).

Polyamines include diamines {alkylenediamines (methylenediamine, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, etc.) and N-substituted diamines (N-methyl-ethylenediamine, N-ethyl-ethylenediamine, N-decylethylenediamine, N,N'-dimethylethylenediamine, N-(2-hydroxyethyl)ethylenediamine, N-ethyl-1,3-propylenediamine, etc.)}; triamines {dialkylenetriamines (diethylenetriamine, bis(hexamethylene)triamine, and 3,3'-diamino-dipropylenediamine)}; amine, etc.) and N-substituted triamines (N,N-bis(3-aminopropyl)methylamine, N,N',N''-trimethyldiethylenetriamine, N,N,N'',N''-tetraisopropyldiethylenetriamine, N,N,N'',N''-tetrabutyldiethylenetriamine, etc.); and tetramines {trialkylenetetramines (triethylenetetramine, N,N'-bis(3-aminopropyl)ethylenediamine, N,N'-bis(3-aminopropyl)-1,3-propanediamine, etc.) and N-substituted tetramines (N,N''-diisopropyltriethylenetetramine, etc.)}. Among these, alkylene diamines, N-substituted diamines, dialkylene triamines, and trialkylene tetramines are preferred from the viewpoint of fluidity, and more preferred are ethylenediamine, hexamethylenediamine, N-decyl-ethylenediamine, diethylenetriamine, and triethylenetetramine.

Ketimines of polyamines are imines that are more readily obtained by reaction of polyamines with ketones.

Ketones include ketones having 3 to 9 carbon atoms, such as acetone, methyl ethyl ketone, methyl butyl ketone, methyl pentyl ketone, methyl hexyl ketone, diethyl ketone, ethyl propyl ketone, ethyl butyl ketone, ethyl pentyl ketone, ethyl hexyl ketone, dipropyl ketone, propyl butyl ketone, propyl pentyl ketone, and propyl hexyl ketone. Of these, acetone, methyl ethyl ketone, and methyl butyl ketone are preferred from the viewpoint of ease of removal of the ketone after hydrolysis.

The dispersant (C) may contain an aqueous solvent. Examples of the aqueous solvent include water, alcohols having 1 to 6 carbon atoms (ethyl alcohol, methyl alcohol, ethylene glycol, diethylene glycol, etc.), and ketones having 1 to 6 carbon atoms (methyl isobutyl ketone, acetone, etc.), which may be used alone or in combination.

It is preferable that the dispersant (C) does not contain an aqueous solvent, but if it does contain an aqueous solvent, the content (weight %) of the aqueous solvent is preferably about 1 to 90 based on the weight of the polyoxyalkylene compound (Y) and the aqueous solvent. In this case, the content (weight %) of the polyamine compound (Y) is preferably about 10 to 99 based on the weight of the polyamine compound (Y) and the aqueous solvent.

The content (wt%) of the dispersant (C) is preferably 0.05 to 30, more preferably 0.1 to 10, and particularly preferably 0.5 to 5, based on the weight of the inorganic particles (A), acid (B), dispersant (C), and water (D). Within this range, the fluidity is further improved.

There are no particular limitations on the water (D), but ion-exchanged water and ultrapure water are preferred.

The content (wt%) of water (D) is preferably 1 to 90, more preferably 20 to 80, and particularly preferably 38 to 65, based on the weight of inorganic particles (A), acid (B), dispersant (C), and water (D). Within this range, the fluidity is further improved.

The inorganic particle dispersion slurry of the present invention may contain other components (such as water-soluble organic compounds and water-soluble metal compounds) and other additives (such as thickeners, rust inhibitors, and antifoaming agents) in addition to the inorganic particles (A), acid (B), dispersant (C), and water (D).

Water-soluble organic compounds include organic compounds that are easily soluble in water (0 to 100°C, preferably 5 to 60°C), such as alcohols with 1 to 4 carbon atoms and ketones with 3 to 6 carbon atoms.

Water-soluble metal compounds include metal compounds that are easily soluble in water (0 to 100°C, preferably 5 to 60°C), such as organic acid metal salts, metal nitrates, metal oxynitrates, metal hydroxides, and metal nitrites.

When other components are contained, the content (wt%) of the other components is preferably 0.1 to 70, more preferably 0.3 to 60, and particularly preferably 7 to 54, based on the weight of the inorganic particles (A), acid (B), dispersant (C), and water (D).

Thickeners include known natural or synthetic thickeners (inorganic compounds, cellulose compounds, proteins, acrylic polymers, vinyl polymers, etc.).

The rust inhibitor includes at least one selected from the group consisting of nitrogen-containing organic rust inhibitors and polyhydric alcohol partial ester rust inhibitors.

Defoamers include known water-based defoamers (such as silicone-based defoamers, mineral oil-based defoamers, polyether-based defoamers, and wax-based defoamers).

When other additives are contained, the content (wt%) of the other additives is preferably 0.1 to 5, more preferably 0.5 to 3, and particularly preferably 0.5 to 1, based on the weight of the inorganic particles (A), acid (B), dispersant (C), and water (D).

The inorganic particle dispersion slurry of the present invention can be produced by any known mixer/disperser without any limitation as long as it can uniformly mix and disperse the inorganic particles (A), acid (B), dispersant (C), and water (D), as well as other components and/or other additives as necessary. It is preferable to uniformly mix the components other than the inorganic particles (A) and then disperse the inorganic particles (A). Note that the inorganic particles may be pulverized or crushed during uniform mixing and dispersion.

The number average particle size (μm) of the inorganic particles (A) in the inorganic particle dispersion slurry of the present invention is preferably 0.01 to 100, more preferably 0.02 to 50, and particularly preferably 0.08 to 40.

The number-average particle size is determined using a laser diffraction analysis type particle size distribution analyzer (e.g., LA-950V2, Horiba, Ltd.) that complies with JIS X8825:2013 (particle size analysis - laser diffraction and scattering method).

The inorganic particle dispersion slurry of the present invention may be applied to various substrates (plastics, wood, leather, metals, ceramics, etc.) or may be dried and molded. It may also be mixed with a binder, etc., and applied to various substrates or may be dried and molded. Furthermore, it may be sintered after application or molding.

In the following description, unless otherwise specified, parts means parts by weight and % means % by weight.
The following polyamine compounds (Y1) to (Y8) {the values in <> correspond to the formula (1)} were synthesized by a known method and designated as dispersants (c1) to (c8) of the present invention, respectively. In addition, a comparative dispersant (c9; a 35% aqueous solution of sodium acrylate-sodium maleate copolymer <sodium acrylate:sodium maleate=50:50 (mol %), Mn=5000>) was prepared in accordance with Production Example 1 of Patent Document 1.

(Y1) Ethylenediamine-ethylene oxide 4 moles-propylene oxide 4 moles block adduct <n=2, m=0, s=2>
(Y2) Ethylenediamine-ethylene oxide 4-mol adduct <n=2, m=0, s=1>
(Y3) Ethylenediamine-propylene oxide 4-mol adduct <n=2, m=0, s=1>
(Y4) Ethylenediamine-ethylene oxide 3-mol adduct <n=2, m=0, s=1> (R ¹ is a hydrogen atom, and R ² , R ⁴ and R ⁵ each contain ethylene oxide.)
(Y5) Hexamethylenediamine-ethylene oxide 8 mole adduct <n=6, m=0, s=2>
(Y6) Diethylenetriamine-propylene oxide 10 mole adduct <n=2, m=1, s=10> Example of using a ketimine product of polyamine (R ¹ , R ² , R ⁴ and R ⁵ are hydrogen atoms, and R ³ contains a polyoxypropylene chain).
(Y7) Triethylenetetramine-ethylene oxide 60 moles-propylene oxide 20 moles random adduct <n=2, m=2, s=40> Example of using a ketimine product of polyamine (R ¹ , R ² , R ⁴ and R ⁵ are hydrogen atoms, and R ³ contains a polyoxyethylene-polyoxypropylene chain).
(Y8) N-decyl-ethylenediamine ethylene oxide 30 mole adduct <n=2, m=0, s=10> (R ¹ is a decyl group, and R ² , R ⁴ and R ⁵ each contain a polyoxyethylene chain.)

Example 1
2 parts of dispersant (c1), 55 parts of water (d1; ion-exchanged water), and 3 parts of acid (b1; acetic acid, EP standard, Nacalai Tesque, Inc.) were uniformly mixed, and 40 parts of inorganic particles (alumina, A-11, Sumitomo Chemical Co., Ltd.) were gradually added while stirring at 1,000 rpm using a homomixer (HIGH-FLEX DISPERSER, SMT Co., Ltd.), and after the addition was completed, the mixture was stirred at 1,500 rpm for 5 minutes to obtain inorganic particle dispersion slurry (1) of the present invention. The number average particle diameter of inorganic particles (a11) in inorganic particle dispersion slurry (1) was 33 μm.

The number-average particle size was measured using a laser diffraction particle size analyzer (LA-950V2, Horiba, Ltd.) by adding the measurement sample to water with an electrical conductivity of 0.1 mS/m or less so that the measurement sample concentration was 0.1%, at a measurement temperature of 25 ± 10°C. The refractive indexes used were 1.33 for the circulating liquid (water), 1.66 for alumina, 1.92 for carbon black, 2.50 for titanium oxide, and 1.45 for hydrophilic silica. The same applies below.

<Examples 2 to 8>
Inorganic particle dispersion slurries (2 to 8) of the present invention were obtained in the same manner as in Example 1, except that the dispersant (c1) was changed to any one of the dispersants (c2 to c8). The number average particle diameter of the inorganic particles (a12) in the inorganic particle dispersion slurry (2) was 32 μm. The number average particle diameter of the inorganic particles (a13) in the inorganic particle dispersion slurry (3) was 32 μm. The number average particle diameter of the inorganic particles (a14) in the inorganic particle dispersion slurry (4) was 33 μm. The number average particle diameter of the inorganic particles (a15) in the inorganic particle dispersion slurry (5) was 36 μm. The number average particle diameter of the inorganic particles (a16) in the inorganic particle dispersion slurry (6) was 33 μm. The number average particle diameter of the inorganic particles (a17) in the inorganic particle dispersion slurry (7) was 36 μm. The number average particle diameter of the inorganic particles (a18) in the inorganic particle dispersion slurry (8) was 36 μm.

<Example 9>
5 parts of dispersant (c1), 65 parts of water (d1; ion-exchanged water), 2 parts of acid (b2; nitric acid, JIS special grade reagent, Nacalai Tesque, Inc.), and 28 parts of inorganic particles (carbon black, MA100, Mitsubishi Chemical Corporation) were mixed uniformly, stirred using a stirring/defoaming device (Mazerustar KK-VT300, Kurabo Industries, Ltd.), and dispersed for 30 seconds at an output of 240 W using an ultrasonic dispersing device (UP400S, Hielscher) to obtain inorganic particle dispersion slurry (9) of the present invention. The number average particle diameter of inorganic particles (a21) in inorganic particle dispersion slurry (9) was 0.08 μm.

Example 10
Except for changing the dispersant (c1) to the dispersant (c2), the procedure of Example 9 was repeated to obtain an inorganic particle dispersion slurry (10) of the present invention. The number average particle diameter of the inorganic particles (a22) in the inorganic particle dispersion slurry (10) was 0.08 μm.

Example 11
60 parts of inorganic particles (titanium oxide, R-820, Ishihara Sangyo Kaisha, Ltd.), 1.5 parts of acid (b1), 0.5 parts of dispersant (c1), and 38 parts of water (d1) were uniformly mixed, and then stirred at 1,500 rpm for 5 minutes using a homomixer (HIGH-FLEX DISPERSER, SMT Corporation) to obtain inorganic particle dispersion slurry (11) of the present invention. The number average particle diameter of inorganic particles (a31) in inorganic particle dispersion slurry (11) was 0.49 μm.

Example 12
35 parts of inorganic particles (hydrophilic silica, Nipsil NA, Tosoh Silica Corporation), 2 parts of acid (b1), 3 parts of dispersant (c1), and 60 parts of water (d1) were uniformly mixed, and then stirred at 1,500 rpm for 5 minutes using a homomixer (HIGH-FLEX DISPERSER, SMT Corporation) to obtain inorganic particle dispersion slurry (12) of the present invention. The number average particle diameter of inorganic particles (a41) in inorganic particle dispersion slurry (12) was 10 μm.

Example 13
Except for changing the acid (b1) to the acid (b2), an inorganic particle dispersion slurry (13) of the present invention was obtained in the same manner as in Example 12. The number average particle diameter of the inorganic particles (a42) in the inorganic particle dispersion slurry (13) was 10 μm.

<Comparative Example 1>
An attempt was made to prepare a comparative inorganic particle dispersion slurry (14) in the same manner as in Example 1, except that the dispersant (c1) was changed to water (d1). However, the inorganic particles settled, and an inorganic particle dispersion slurry could not be obtained.

<Comparative Example 2>
Except for not using the dispersant (c1), a comparative inorganic particle dispersion slurry (15) was obtained in the same manner as in Example 1. The number average particle diameter of the inorganic particles (a19) in the inorganic particle dispersion slurry (15) was 37 μm.

<Comparative Example 3>
A comparative inorganic particle dispersion slurry (16) was obtained in the same manner as in Example 1, except that the dispersant (c1) was changed to a comparative dispersant (c9). The number average particle diameter of the inorganic particles (a20) in the inorganic particle dispersion slurry (16) was 36 μm.

<Comparative Example 4>
An attempt was made to prepare a comparative inorganic particle dispersion slurry (17) in the same manner as in Example 9, except that the dispersant (c1) was changed to water (d1). However, the inorganic particles aggregated and the entire mixture solidified, and therefore, an inorganic particle dispersion slurry could not be obtained.

<Comparative Example 5>
A comparative inorganic particle dispersion slurry (18) was obtained in the same manner as in Example 9, except that the dispersant (c1) was changed to the dispersant (c9). The number average particle diameter of the inorganic particles (a23) in the inorganic particle dispersion slurry (18) was 0.18 μm.

<Comparative Example 6>
Except for changing the dispersant (c1) to water (d1), a comparative inorganic particle dispersion slurry (19) was obtained in the same manner as in Example 11. The number average particle diameter of the inorganic particles (a32) in the inorganic particle dispersion slurry (19) was 1.1 μm.

<Comparative Example 7>
A comparative inorganic particle dispersion slurry (20) was obtained in the same manner as in Example 11, except that the dispersant (c1) was changed to the dispersant (c9). The number average particle diameter of the inorganic particles (a33) in the inorganic particle dispersion slurry (20) was 0.72 μm.

<Comparative Example 8>
A comparative inorganic particle dispersion slurry (21) was obtained in the same manner as in Example 12, except that the dispersant (c1) was changed to water (d1). The number average particle diameter of the inorganic particles (a43) in the inorganic particle dispersion slurry (21) was 12 μm.

<Comparative Example 9>
A comparative inorganic particle dispersion slurry (22) was obtained in the same manner as in Example 12, except that the dispersant (c1) was changed to the dispersant (c9). The number average particle diameter of the inorganic particles (a44) in the inorganic particle dispersion slurry (22) was 11 μm.

<Comparative Example 10>
A comparative inorganic particle dispersion slurry (23) was obtained in the same manner as in Example 13, except that the dispersant (c1) was changed to water (d1). The number average particle diameter of the inorganic particles (a45) in the inorganic particle dispersion slurry (23) was 12 μm.

<Comparative Example 11>
A comparative inorganic particle dispersion slurry (24) was obtained in the same manner as in Example 13, except that the dispersant (c1) was changed to the dispersant (c9). The number average particle diameter of the inorganic particles (a46) in the inorganic particle dispersion slurry (24) was 11 μm.

<Liquidity Evaluation 1>
The inorganic particle dispersion slurries (1) to (8), (11) to (13) prepared in Examples 1 to 8 and 11 to 13, and the inorganic particle slurries (15), (16), and (19) to (24) prepared in Comparative Examples 2, 3, and 6 to 11 were measured for viscosity (mPa·s) using a BM type viscometer (VISCOMETER TV-20, Toki Sangyo Co., Ltd., 25°C, 60 rpm). Furthermore, the pH of the slurries was measured using a multi-water quality meter (MM-43M, DKK-TOA Corporation, 25°C). The results are shown in the table below.

「－」は無機粒子分散スラリーが得られなかったことを意味し、「∞」は測定範囲（ｍＰａ・ｓ）を越えたことを意味する。

"-" means that no inorganic particle dispersion slurry was obtained, and "∞" means that the measurement range (mPa·s) was exceeded.

「－」は無機粒子分散スラリーが得られなかったことを意味する。 <Liquidity Evaluation 2>
The viscosity (mPa s) of the inorganic particle dispersion slurries (9) and (10) prepared in Examples 9 and 10, and the inorganic particle dispersion slurry (18) prepared in Comparative Example 5 was measured using an E-type viscometer (RE80 type, Toki Sangyo Co., Ltd., 25°C, 10 rpm). Furthermore, the pH of the slurries was measured using a multi-water quality meter (MM-43M, DKK-TOA Corporation, 25°C). The results are shown in the table below.

"-" means that no inorganic particle dispersion slurry was obtained.

The inorganic particle dispersion slurries prepared in the Examples had superior fluidity even when the pH (25°C) was 1 to 6, compared to the inorganic particle dispersion slurries prepared in the Comparative Examples. Furthermore, the dispersant of the present invention exhibited superior fluidity even when applied to inorganic particle dispersion slurries with a pH (25°C) of 1 to 6.

Claims (2)

The composition comprises inorganic particles (A), an acid (B), a dispersant (C) and water (D),
pH (25° C.) is 1 to 6,
1. A slurry containing dispersed inorganic particles, comprising a dispersant (C) containing a polyamine compound (Y) represented by formula (1):

R ¹ to R ⁵ are at least one selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, and a group represented by H-(AO) _s - (AO is an oxyalkylene group having 2 to 3 carbon atoms, and s is an integer from 1 to 80), and at least one of R ¹ to R ⁵ is a group represented by H-(AO) _s -. n is an integer from 1 to 6, m is an integer from 0 to 2, N is a nitrogen atom, C is a carbon atom, and H is a hydrogen atom. The inorganic particle dispersion slurry according to claim 1, wherein the inorganic particles (A) are metal oxide and/or carbon.