JP2011219611A - Metal oxide particle dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal oxide particle containing dispersion excellent in dispersion stability (aggregation proofness).SOLUTION: This dispersion includes metal oxide particles (A), aqueous liquid (B) and aggregation prevention agent (C). The aggregation prevention agent (C) is a phosphorus atom containing compound. Preferably, the aggregation prevention agent (C) is an acid phosphorus compound and/or a salt of them. More preferably, the aggregation prevention agent (C) is at least one type selected from a group consisting of phosphate, pyrophosphate, metaphosphoric acid, phosphoric ester, phosphonic acid, diphosphonic acid, triphosphonic acid, tetraphosphonic acid, pentaphosphonic acid, monophosphonic acid, phosphonate, phosphinic acid, diphosphinic acid, monophosphinic acid, and a salt of them.

Description

  The present invention relates to a metal oxide particle dispersion. More specifically, the present invention relates to a dispersion suitable for water-based paints and water-based inks.

  As a dispersion containing metal oxide particles (designable printing, magnetic ink, etc.), (1) a molecular weight of 1000 to 25000 is selected from polyacrylate, acrylic acid / acrylamide copolymer and polyvinylphosphonic acid. In the presence of a dispersant containing at least one type of polymer electrolyte and an alkali metal salt of these compounds, it contains a dispersion of superparamagnetic solid particles dispersed in water or alcohol and measured at 22 ° C. A magnetic ink composition (Patent Document 1) having a viscosity of 10 cP or less and a saturation magnetization of 32 mT or more, and (2) an aqueous magnetic dispersion containing a copolymer, an amphiphilic compound and magnetic ultrafine particles The magnetic ultrafine particles are synthesized by an aqueous reaction that does not include a drying step and are in an aqueous suspension state and crystalline, and the copolymer is styrene. An aqueous magnetic dispersion comprising acrylic acid, the amphiphilic compound comprising polyethylene oxide and an aromatic ring, and the aqueous magnetic dispersion further comprising at least one monovalent metal ion and ammonium ion The body (Patent Document 2) is known.

JP 5-140492 A JP 2001-354883 A

However, conventional dispersions have insufficient dispersion stability (anti-aggregation property), and there is a problem that increasing the amount added to improve dispersion stability increases the viscosity of the dispersion. There is also the problem that the metal oxide bleeds out after printing the body.
An object of the present invention is to provide a metal oxide particle-containing dispersion excellent in dispersion stability (anti-aggregation property).

As a result of intensive studies to solve these problems, the present inventor has reached the following invention.
That is, the dispersion of the present invention is characterized by a dispersion comprising metal oxide particles (A), an aqueous liquid (B) and an aggregation inhibitor (C), wherein the aggregation inhibitor (C) is a phosphorus atom. The point is that it is a contained compound.

  Since the dispersion of the present invention is excellent in dispersion stability (anti-aggregation property), it maintains excellent dispersion stability for a long time and does not cause aggregation of metal oxide particles. Therefore, it can be suitably used as a metal oxide particle-containing dispersion for various paints and inks, and is particularly useful as a dispersion (ink jet ink or the like) that is required to have low viscosity and long-term dispersion stability.

  Although it will not specifically limit if it is an oxide of a metal element as a metal oxide particle (A), From a use use etc. as a dispersion | distribution, it contains the metal atom of 2-7 valence (preferably 2-4 tetravalence). For example, oxides of alkaline earth metals (magnesium, calcium, strontium, barium, etc.), oxides of group 4 metal elements (titanium, zirconium, etc.), and group 5 metal elements (vanadium) are suitable. And oxides of 6-14 group metal elements (chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, silver, zinc, aluminium, silicon, tin, etc.) .

The metal oxide particle (A) may be an oxide containing two or more types of metal atoms, that is, a composite oxide, or a mixture of two or more types of different types of metal oxide particles. There may be.
The metal oxide particles (A) also include compounds (oxides) of metal atoms and atoms other than oxygen atoms (sulfur atoms, nitrogen atoms, halogen atoms, etc.) in addition to compounds of metal atoms and oxygen atoms. included.

Examples of the metal oxide particles (A) include titanium dioxide (TiO ₂ ), chromium dioxide (CrO ₂ ), molybdenum dioxide (MoO ₂ ), molybdenum trioxide (MoO ₃ ), manganese dioxide (MnO ₂ ), Zirconium dioxide (ZrO ₂ ), iron oxide (II) (FeO), iron oxide (III) (Fe ₂ O ₃ ), triiron tetroxide (Fe ₃ O ₄ ), cobalt dioxide (CoO ₂ ), copper oxide (II) ) (CuO), zinc oxide (ZnO), aluminum oxide _(alumina, Al _{2 O 3),} tin oxide (II) (SnO), tin oxide (IV) _(SnO 2), tin oxide (VI) _(SnO 3) , barium titanate _(BaO 3 Ti), lead titanate (PbTiO _3), strontium titanate (SrTiO _3), potassium niobate (KNbO _3), aluminum Strontium (SrAl ₂ O _4), and ammonium chromate _{((NH 4) 2 Cr 2} O 4) and ammonium titanate _{((NH 4) 2 TiO 3} ) can be mentioned. Of these, metal oxide particles composed of oxides of group 6-14 metal elements are preferred, and oxides of cobalt, chromium, nickel, zinc, iron or molybdenum are more preferred. The metal oxide particles (A) are more preferably magnetic particles.

The magnetic particles include known magnetic particles such as superparamagnetic solid particles as described in US Pat. No. 4,810,401, γ · Fe ₂ O ₃ , chromium dioxide, various ferrites (spinel type ferrite (manganese Zinc ferrite, nickel zinc ferrite, copper zinc ferrite, etc.), magnetoplumbite type ferrite (barium ferrite, strontium ferrite, etc.), garnet type ferrite (yttrium iron garnet ferrite, etc.), etc. can be used. There are no particular restrictions on the shape and crystallinity of the magnetic particles.

  The size of the metal oxide particles (A) is not particularly limited, but the number average particle size (μm) of the primary particles of the metal oxide particles (A) is preferably 0.01 to 10, more preferably 0.8. It is 03-8, Most preferably, it is 0.05-5 micrometers. In addition, the number average particle diameter of the primary particles of the metal oxide particles is a method defined in JIS Z8819-2: 2001 by using the measured value of the particle size distribution measured in accordance with JIS Z8825-1: 2001. The number average particle diameter (number criterion arithmetic average length diameter) is obtained. Although there is no restriction | limiting in particular as a measuring apparatus, For example, it measures using the laser analysis / scattering type particle size distribution measuring apparatus LA-950V2 by Horiba, Ltd. etc. Moreover, the measurement sample of the metal oxide particle used for the measurement is measured in a state of being dispersed to the primary particles according to JIS Z8824: 2004. As the measurement solvent, water and / or ethanol can be used, the measurement concentration is about 0.1 to 5% by weight, and the measurement temperature is about 15 to 40 ° C. Processing of measurement data is automatically performed by a computer attached to the measurement device.

  The shape of the metal oxide particles (A) is not particularly limited, but is preferably a needle shape, but may be a spherical shape, a spheroid shape (spindle shape), a polyhedral shape, an indefinite shape, or the like.

The aqueous liquid (B) includes water and an aqueous solution (an aqueous solution composed of an aqueous solvent and water).
Examples of aqueous solvents include monools (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, etc.), polyols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, sorbit, sorbitan, etc.), glycol ethers, etc. (Such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol and butyl carbitol), glycol ester (such as methyl cellosolve acetate and cellosolve acetate), ketone (such as acetone and methyl ethyl ketone), alkanolamine (monoethanolamine, diethanolamine and Triethanolamine, etc.), other polar solvents (formamide, acetamide, dimethylformamide, N-methyl) Rupiroridon and dimethylsulfoxide, etc.), and mixtures thereof.

  When the aqueous liquid (B) is an aqueous solution, the content (% by weight) of the aqueous solvent is preferably 1 to 80, more preferably 3 to 60, and particularly preferably 5 to 5 based on the weight of the aqueous liquid (B). 50.

  The aggregation inhibitor (C) is not particularly limited as long as it is a compound containing a phosphorus atom in its structure (phosphorus atom-containing compound), but is preferably an acidic phosphorus compound and / or a salt thereof.

An acidic phosphoric acid compound is a phosphoric acid compound having a pH of less than 7 in an aqueous solution.
The pH is measured according to JIS K0400-12-10: 2000 (5% by weight aqueous solution, 25 ° C.).

  Acidic phosphoric acid compounds and / or salts thereof include phosphoric acid, pyrophosphoric acid, metaphosphoric acid, phosphoric acid ester, phosphonic acid, diphosphonic acid, triphosphonic acid, tetraphosphonic acid, pentaphosphonic acid, monophosphonic acid, phosphonic acid ester, phosphine At least one selected from the group consisting of acids, diphosphinic acids, monophosphinic acids and salts thereof is included.

  Examples of phosphate esters include ethyl phosphate, 2-ethylhexyl phosphate, diisooctyl phosphate, diethyl phosphate, diphenyl phosphate, di-n-butyl phosphate, lauryl phosphate, oleyl phosphate, behenyl phosphate and butanol ethylene oxide Examples thereof include phosphoric esters of 3 mol adducts.

  Examples of the diphosphonic acid include methylene diphosphonic acid, ethylene diphosphonic acid, ethylidene diphosphonic acid, hydroxyethylidene diphosphonic acid, butylene-1,1-diphosphonic acid, and phenylene-1,4-diphosphonic acid.

Examples of triphosphonic acid include nitrilotrisethylenephosphonic acid <N (CH ₂ CH ₂ PO (OH) ₂ ) ₃ > and 1,3,5-tri (phosphonomethyl) pentane <(HO) ₂ P (O) —CH ₂ —. ) ₃ C ₅ H ₉ > and the like.

Examples of tetraphosphonic acid include 1,2,3,4-tetra (phosphonoethyl) cyclohexane <((HO) ₂ P (O) —CH ₂ CH ₂ —) ₄ C ₆ H ₁₀ > and ethylenediaminetetra (methylenephosphonic acid). {N, N, N ′, N′-tetrakis (phosphonomethyl) ethylenediamine <((HO) ₂ P (O) —CH ₂ —) ₂ NCH ₂ CH ₂ N (—CH ₂ —PO (OH) ₂ ) ₂ > } Etc. are mentioned.

As pentaphosphonic acid, diethylenetriaminepenta (methylenephosphonic acid) {N, N, N ′, N ′, N ″ -pentakis (phosphonoethyl) diethylenetriamine <((HO) ₂ P (O) —CH ₂ —) ₂ NCH _{2 CH 2 N (-CH 2 -PO (} OH) 2) CH 2 CH 2 N (-CH 2 -PO (OH) 2) 2>} , and the like.

  Examples of the monophosphonic acid include methylphosphonic acid, pentyl-1-phosphonic acid, 2-methylhexyl-1-phosphonic acid, phenylphosphonic acid, amidomethylphosphonic acid, and chloro (phenyl) phosphonic acid.

  Examples of the phosphonic acid ester include methyl phosphonate, hexyl phosphonate, phenyl phosphonate, oleyl phosphonate, and phosphonic acid ester of lauryl alcohol ethylene oxide 5-mol adduct.

  Examples of the diphosphinic acid include methylene diphosphinic acid and butylene diphosphinic acid.

  As monophosphinic acid, ethylphosphinic acid, dimethylphosphinic acid, ethylmethylphosphinic acid, methyl-n-propylenephosphinic acid, methandi (methylphosphinic acid), benzene-1,4- (dimethylphosphinic acid), methylphenylphosphinic acid And diphenylphosphinic acid.

  These salts include alkali metal (such as sodium and potassium) salts, alkaline earth metal (such as magnesium and calcium) salts, ammonium salts, amines (methylamine, dimethylamine, laurylamine, oleylamine, ethylenediamine, Phenylamine, diethylenetriamine, cyclohexylamine) salt, or hydroxyamine (ethanolamine, diethanolamine, triethanolamine, aminoethylethanolamine, 2-amino-2-methyl-1-propanol, 2-amino-1-butanol and 4- Amino-1-octanol and the like) salts. Of these, alkali metal salts, amine salts and hydroxyamine salts are preferable, sodium salts, potassium salts, amine salts having 2 to 12 carbon atoms and hydroxyamine salts having 2 to 12 carbon atoms, particularly preferably sodium salts. , Potassium salts and hydroxyamine salts having 2 to 10 carbon atoms.

  Among these, at least one selected from the group consisting of phosphoric acid, pyrophosphoric acid, phosphoric acid ester, phosphonic acid, diphosphonic acid, alkylphosphonic acid, phosphinic acid, diphosphinic acid and salts thereof is preferable, and pyrophosphoric acid is more preferable. , Phosphoric acid ester, diphosphonic acid, diphosphinic acid and at least one selected from the group thereof.

When the aggregation inhibitor (C) is a salt of an acidic phosphorus compound, this salt is obtained from a neutralization reaction between the acidic phosphorus compound and an alkali.
Alkalis include alkali metal hydroxides (such as sodium hydroxide and potassium hydroxide), alkaline earth metal hydroxides (such as magnesium hydroxide and calcium hydroxide), ammonia, amines (methylamine, dimethylamine, Laurylamine, oleylamine, ethylenediamine, phenylamine, diethylenetriamine and cyclohexylamine) and hydroxyamine (ethanolamine, diethanolamine, triethanolamine, aminoethylethanolamine, 2-amino-2-methyl-1-propanol, 2-amino- 1-butanol and 4-amino-1-octanol). Of these, alkali metal hydroxides, amines and hydroxyamines are preferred, sodium hydroxide, potassium hydroxide, amines having 2 to 12 carbon atoms and hydroxyamines having 2 to 12 carbon atoms, particularly preferably water. Sodium oxide, potassium hydroxide, and hydroxyamines having 2 to 10 carbon atoms.

  When the aggregation inhibitor (C) is a salt of an acidic phosphorus compound and an alkali, it can be neutralized by a known method, or can be neutralized after being diluted with an aqueous liquid (B) or the like. When using an aqueous liquid (B) etc., the density | concentration of an acidic phosphorus compound is about 10 to 80 weight%. Further, the neutralization temperature is usually about 20 to 40 ° C. (while cooling when the exotherm is intense). Further, the degree of neutralization may be selected in a timely manner according to the pH of the target dispersion. However, considering the corrosiveness and safety, it is preferable to adjust the degree of neutralization to usually 5 to 8.

  The content weight ratio (A: C) of the metal oxide particles (A) and the aggregation inhibitor (C) is not particularly limited, but is preferably 100: 0.01 to 50, more preferably from the viewpoint of dispersion stability. It is most desirable that the ratio is 100: 0.05 to 35, particularly preferably 100: 0.1 to 30.

  The content (% by weight) of the metal oxide particles (A) is not particularly limited, but in order to maintain an appropriate viscosity from the viewpoint of workability as a dispersion, the metal oxide particles (A) and the aqueous liquid (B ) And the weight of the anti-aggregation agent (C), preferably 10 to 90, more preferably 15 to 85, and particularly preferably 20 to 80.

  The content (% by weight) of the aqueous liquid (B) is not particularly limited, but is preferably 1 to 90 based on the weight of the metal oxide particles (A), the aqueous liquid (B), and the aggregation inhibitor (C), More preferably, it is 5-70, Most preferably, it is 8-60.

  The content (% by weight) of the aggregation inhibitor (C) is not particularly limited, but is 0.001 to 30 based on the weight of the metal oxide particles (A), the aqueous liquid (B), and the aggregation inhibitor (C). Is preferable, more preferably 0.05 to 25, and particularly preferably 0.1 to 20.

The dispersion of the present invention may contain known additives {the following various dyes (colorants), resins, etc.} depending on the purpose.
(1) Colorant Disperse dye, acid dye, direct dye, basic dye, various organic or inorganic pigments, etc. (2) Aqueous resin Acrylic resin, acrylic-styrene resin, vinyl acetate resin, epoxy resin, alkyd resin, acrylic modified alkyd Resins, melamine resins, epoxy resins, hexamethylol melamine resins, urea-formaldehyde condensates, urea-melamine cocondensates, etc. (3) Thickeners Polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, xanthan gum, etc. (4) Wetting agents (5) Ultraviolet absorber (6) Antioxidant (7) Antifungal agent (8) Antifoaming agent (9) Anti-drying agent (10) Water resistance imparting agent (11) Anti-bleeding agent (12) Anti-repellent agent (13) Others Surfactant

  When the additive is included, the amount (% by weight) of these additives is not particularly limited, but is 0.1% based on the weight of the metal oxide particles (A), the aqueous liquid (B), and the aggregation inhibitor (C). -40 is preferable, More preferably, it is 1-30.

  The dispersion of the present invention can be produced using a known dispersion method. Dispersers are not particularly limited, and commonly used mixers and dispersers can be applied. Container drive media such as roll mills, ball mills, centrifugal mills, planetary ball mills, as well as general dispersers such as paint shakers, homomixers, and dispersers A high-speed rotating mill such as a mill or a sand mill, or a medium stirring mill such as a stirring tank mill can be used.

The viscosity of the dispersion of the present invention is not particularly limited, but is generally preferably low, more preferably a rotational viscosity at 25 ° C. of 0.2 to 1000 mPa · s, particularly preferably 0.5 to 800 mPa · s. Most preferably, it is 1 to 500 mPa · s. In particular, when used as an ink for an ink jet printer or the like, the rotational viscosity (25 ° C.) is preferably 0.4 to 10 mPa · s, more preferably 1 to 7 mPa · s in order to prevent printability and clogging. is there. In addition, there is no restriction | limiting in particular also about the inkjet system in the case of using as an inkjet ink, It can apply to a well-known system.
The rotational viscosity is measured in accordance with JIS R1652: 2003 (Brookfield single cylinder rotational viscometer).

  In general, the pH of the dispersion is preferably near neutral. However, particularly when used as an ink for an inkjet printer, the pH is preferably from the viewpoint of preventing corrosion of the head and maintaining dispersion stability. It is preferably 6 to 10, and more preferably 7 to 9. In order to make pH into the said range, you may add a well-known pH adjuster etc. in the range which does not inhibit the performance of a dispersion.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.

  Using a metal oxide particle (A) and an aqueous liquid (B) and an anti-agglomeration agent (C) or a comparative anti-agglomeration agent (HC), 5 with a stirring defoamer (Sinky Corporation, AR-250 type). The mixture was stirred and degassed for a minute to obtain dispersions of Examples 1 to 24 and Comparative Examples 1 to 5. The compounding ratios of Examples and Comparative Examples are shown in Tables 1 to 4 (the numbers in the tables are parts by weight).

<Metal oxide particles (A)>
(A1) Number average particle diameter measured by triiron tetroxide (Fe ₃ O ₄ ) (LA-950V2 (manufactured by Horiba, Ltd.) = 4.3 μm, the same shall apply hereinafter) (reagent grade 1, manufactured by Nacalai Tesque, Inc .; The same unless otherwise specified)
(A2) Chromium oxide (III) (Cr ₂ O ₃ ) (number average particle diameter = 2 μm)

<Aqueous liquid (B)>
(B1) Water (deionized water)
(B2) Ethanol

<Aggregation inhibitor (C)>
(C1) Phosphoric acid (C2a) Pyrophosphate (C2b) Sodium pyrophosphate (C3) Lauryl phosphate ester (C4) Phosphonic acid (C5a) Methylene diphosphonic acid (C5b) Potassium methylene diphosphonate (C6a) Nitrilotris ethylene phosphone Acid (C6b) Ammonium nitrilotrisethylenephosphonate (C7) Phenylphosphonic acid (C8) Phosphinic acid (C9) Butylene diphosphinic acid (C-10) Metaphosphoric acid (C-11a) Ethylenediaminetetra (methylenephosphonic acid)
(C-11b) Potassium ethylenediaminetetra (methylenephosphonic acid) (C-12a) Diethylenetriaminepenta (methylenephosphonic acid)
(C-12b) diethylenetriaminepenta (methylenephosphonic acid) ammonium (C-13) methyl phosphonate (C-14a) methylenediphosphinic acid (C-14b) sodium methylenediphosphinate (C-15) methylphenylphosphinic acid

<Comparison anticoagulant (HC)>
(HC1) Sodium polyacrylate (product name “Nopcos Perth 44-C”, manufactured by San Nopco, “Nopcos Perth” is a registered trademark of the company)
(HC2) Polyethylene glycol (product name “PEG-1000”, manufactured by Sanyo Chemical Industries, Ltd.)

Ａ：Ｃは、金属酸化物粒子（Ａ）１００に対する凝集剤（Ｃ）の含有比率である（以下同様）。

A: C is the content ratio of the flocculant (C) to the metal oxide particles (A) 100 (the same applies hereinafter).

  The dispersions obtained in Examples and Comparative Examples were evaluated for dispersion stability (initially, after standing for 1 week), cohesiveness and rotational viscosity by the following methods. These results are shown in Table 5.

<Dispersion stability>
100 g of the dispersion was put in a test tube having a diameter of 1 cm and a height of 20 cm, sealed, and allowed to stand at room temperature (about 25 ° C.) for 1 hour, and then the ratio (%) of the resulting supernatant portion to the total liquid height. The initial dispersion stability was obtained. Thereafter, the mixture was allowed to stand in a constant temperature dryer at 60 ° C. for 1 week, and then the ratio (%) of the resulting supernatant portion to the total liquid height was determined and used as the dispersion stability after standing for 1 week. A larger value means that the dispersion stability is worse (0% means that no separation occurs).

<Cohesiveness>
In the evaluation of the dispersion stability, the hardness of the aggregate that settled after standing at 60 ° C. for 1 week was determined by tactile sensation according to the following criteria (re-dispersion was gently performed several times (○ Easy) or tens of times (triggered by inverting).
◎: No sediment is generated. ○: The generated sediment is soft and can be easily redispersed. △: The generated sediment is slightly hard and difficult to redisperse. ×: The generated sediment is hard and cannot be redispersed.

<Rotational viscosity>
The viscosity at 25 ° C. of the dispersion was measured using a BM type viscometer to obtain the dispersion viscosity (mPa · s). “Immediately after preparation” is a value measured immediately after preparing the dispersion, and “After standing” is a value after standing at 60 ° C. for one week. In addition, what was isolate | separated was measured after stirring and defoaming again uniformly for about 5 minutes. A larger value indicates higher viscosity (= poor).

As is apparent from Table 5, the dispersion of the present invention was superior in dispersion stability and low in viscosity as compared with the comparative dispersion.

Claims (7)

A dispersion comprising metal oxide particles (A), an aqueous liquid (B), and an aggregation inhibitor (C), wherein the aggregation inhibitor (C) is a phosphorus atom-containing compound. . The dispersion according to claim 1, wherein the aggregation inhibitor (C) is an acidic phosphorus compound and / or a salt thereof. Anti-aggregation agent (C) is phosphoric acid, pyrophosphoric acid, metaphosphoric acid, phosphoric acid ester, phosphonic acid, diphosphonic acid, triphosphonic acid, tetraphosphonic acid, pentaphosphonic acid, monophosphonic acid, phosphonic acid ester, phosphinic acid, diphosphinic acid The dispersion according to claim 1, which is at least one selected from the group consisting of monophosphinic acid and salts thereof. The dispersion according to any one of claims 1 to 3, wherein the metal oxide particles (A) contain a divalent to heptavalent metal atom. The number average particle diameter of the primary particle of a metal oxide particle (A) is 0.01-10 micrometers, The dispersion in any one of Claims 1-4. The dispersion according to any one of claims 1 to 5, wherein the content weight ratio (A: C) of the metal oxide particles (A) and the aggregation inhibitor (C) is from 100: 0.01 to 50. The content of the metal oxide particles (A) is 10 to 90% by weight based on the weight of the metal oxide particles (A), the aqueous liquid (B) and the aggregation inhibitor (C). The dispersion in any one of.