JP3347840B2 - Aqueous pigment dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous pigment dispersion which is used as a colorant for paints and inks by being mixed with various aqueous resin solutions or dispersions.

[0002]

2. Description of the Related Art Conventionally, as an aqueous pigment dispersion for a colorant, a dispersion of a pigment in a water-soluble acrylic resin or a surfactant has been generally used.

[0003]

However, in paints using these aqueous pigment dispersions, the pigments settle during storage, and the coatings have poor water resistance, causing blistering and glossiness of the coatings. There was an easy problem.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention provides an aqueous pigment wherein the pigment (A) is mixed and dispersed in the following water-soluble urethane resin (B), and the amount of (B) is 0.1 to 10 times the weight of (A). A colorant for a water-based paint or a water-based printing ink comprising a dispersion; and a water-based paint or a water-based printing ink containing the colorant. Water-soluble urethane resin (B): a water-soluble urethane resin obtained by extending a NCO-terminated urethane prepolymer (b) having a hydrophilic group having a hydrophilic group content of 0.1 to 20% by weight with water and / or a polyamine. And is prepared by capping a part of the NCO group of (b) with a monoalcohol and / or a monoamine, and has an average number of functional groups (-N
(Only H ₂ or ＮＨNH is calculated as an active hydrogen-containing group.)
Is less than 2.

[0005] In the present invention, examples of the pigment (A) include inorganic pigments and organic pigments. As inorganic pigments, white pigments (titanium white, zinc white, lithopone, lead white, etc.), transparent white pigments (calcium carbonate, barium sulfate, calcium silicate, etc.), black pigments (carbon black, animal black, graphite, etc.) , Gray pigments (zinc powder, slate powder, etc.), red pigments (redwood, lead red, etc.), brown pigments (amber, iron oxide powder, bandike tea, etc.), yellow pigments (graphite, zinc chromate, yellow iron oxide, etc.) , Green pigments (chromium green, chromium oxide, viridian, etc.), blue pigments (ultramarine, navy blue, etc.), purple pigments (mars purple, light-mouth cobalt purple, etc.), metal powder pigments (aluminum powder, copper powder, bronze powder, etc.) Is mentioned. Organic pigments include natural organic pigments and synthetic organic pigments. Natural organic pigments include cochineal lake, madder lake and the like. Examples of the synthetic organic pigments include nitroso pigments (such as naphthol / gulin Y and naphthol / grin B), nitro pigments (such as naphthol / yellow S, pigment chlorin, and ritol / fast yellow GG), and pigment-dye type azo pigments (toluidine / glyph). Red, Hansa Yellow, Naphthol AS-G, etc., Azo lake made from water-soluble dyes (Persia Orange, Ponceau 2R, Bordeaux B, etc.), Azo lake made from poorly soluble dyes (Resole Red, Bone Maroon, Red Lake) C), lakes made from basic dyes (e.g., fanal color), lakes made from basic acid dyes (e.g., acid green lake, peacock blue lake),
Xanthan lake (such as eosin), anthraquinone lake (such as alizarin lake, purpurin lake), pigments from vat dyes (such as indigo, argon yellow), phthalocyanine pigments (such as phthalocyanine)
Blue, phthalocyanine green, etc.). These pigments are used alone or in combination of two or more.

In the present invention, the water-soluble urethane resin (B) having an average number of functional groups (in the case of using alkanolamine, only -NH ₂ or ＮＨNH is calculated as an active hydrogen-containing group) of less than 2 is used as an active hydrogen-containing compound. Part of the NCO group of the NCO-terminated prepolymer (b) having a hydrophilic group, comprising a compound having an active hydrogen group and a hydrophilic group in the molecule and an organic polyisocyanate, is capped with a monoalcohol or a monoamine and is treated with water or a polyamine. It is obtained by elongating the chain and dissolving it in water. Examples of the active hydrogen-containing compound include a high molecular polyol, a low molecular polyol and a polyamine (for example, those described in JP-A-3-9951).

Preferred as high molecular polyols are polyether polyols and polyester polyols, and particularly preferred are adipates and / or phthalate diols of branched or straight-chain alkanediols having 2 to 6 carbon atoms. The OH equivalent of the polymer polyol is usually from 200 to 3,000, preferably from 250 to 2,000.

Preferred low molecular polyols include:
1,4-butanediol, 3-methylpentanediol, 2-ethyl-1,3-hexanediol and trimethylolpropane.

Preferred polyamines are hexamethylenediamine, isophoronediamine, N-hydroxylethylethylenediamine and 4.4'-diaminodicyclohexylmethane.

These active hydrogen-containing compounds are usually used alone or in combination with a high molecular polyol and a low molecular polyol and / or a polyamine.

The compound having an active hydrogen and a hydrophilic group in the molecule includes an anion group or an anion group or an anion-forming group (a compound which reacts with a base to form an anion group, Compounds which are neutralized with a base before, during or after the chemical reaction to convert to an anionic group) (for example, those disclosed in JP-B-42-24192 and JP-B-55-192).
No. 41607), those known as compounds having an active hydrogen and a cationic group in the molecule (for example, those described in JP-B-43-9076) and active hydrogen and nonionic in the molecule. Compounds known as compounds having a hydrophilic hydrophilic group (for example, Japanese Patent Publication No. Sho 48-4)
No. 1718), and preferred among these are compounds having active hydrogen and an anionic group (such as a carboxyl group or a sulfonic acid group) in the molecule. Particularly preferred among these are compounds having an active hydrogen and a carboxyl group in the molecule, and specific examples thereof include α, α-dimethylolpropionic acid and α, α-dimethylolbutyric acid. .

The content of the hydrophilic group in (b) is
0.1 to 20% by weight, preferably 0.5 to
10% by weight. If the content of the hydrophilic group is less than 0.1% by weight, the water-soluble (B) cannot be obtained, and if it exceeds 20% by weight, the water resistance of the coating film as a paint or ink decreases.

The organic polyisocyanate is disclosed in
-9951 publication. Of these, preferred are 2,4 and / or 2,6
-Tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and α , Α,
α ′, α′-tetramethylxylylene diisocyanate (TMXDI).

In producing (b), an active hydrogen compound (including a compound having active hydrogen and a hydrophilic group in the molecule)
The ratio of the active hydrogen-containing group ｛OH, NH ₂ , NH [(b) with water and / or a polyamine when using an alkanolamine is -NH the equivalent ratio of ₂ or = NH only be calculated as the active hydrogen-containing group]} with an isocyanate group is generally 1: (1.05 to 2), preferably 1: (1.05 to 1.5).

In the production of (b), a method of reacting an active hydrogen-containing compound (including a compound having an active hydrogen and a hydrophilic group in a molecule) with a polyisocyanate may be a one-shot method in which each component is reacted at a time or a one-shot method. A multi-stage method in which a stepwise reaction is carried out. A part of an active hydrogen-containing compound (for example, a polymer polyol) is reacted with a polyisocyanate to form an NC.
After the O-terminal prepolymer is formed, the remaining active hydrogen-containing compound is allowed to react to produce any of the methods (2). The synthesis reaction of (b) is usually performed at 40 to 140 ° C, preferably 60 to 120 ° C. The prepolymerization reaction may be performed in an organic solvent inert to isocyanate (for example, acetone, toluene, dimethylformamide, etc.), or the solvent may be added during or after the reaction.

The water-soluble urethane resin (B) in the present invention
Are known methods (an anion-forming group, a method of forming an anion group by neutralizing with a base, a cation-forming group, the NCO-terminated urethane prepolymer (b) having a hydrophilic group obtained by the above method, In the case of, a method of forming a cationic group with a quaternizing agent or a method of neutralizing with an acid to form a cationic group), and then dissolving in water while elongating the chain with water and / or a polyamine. It is something that can be done.

As a method for making the average number of functional groups (B) (when using alkanolamine, only -NH ₂ or = NH is calculated as an active hydrogen-containing group) is less than 2,
For example, in the synthesis step (b) above, a compound having one active hydrogen-containing group (in the case of using an alkanolamine, only -NH ₂ or = NH is calculated as an active hydrogen-containing group) in the molecule {monoalcohol (for example, Methanol, butanol) or monoamines (eg, butylamine,
Dibutylamine) in combination with water or a polyamine to extend the chain of an NCO-terminated prepolymer in which some of the NCO groups are capped, or monoamine (for example, butylamine) when the chain is extended with water and / or a polyamine. , Ethanolamine and diethanolamine). When the average number of functional groups of (B) is 2 or more, the obtained (B) becomes gel-like or the dispersibility of the pigment deteriorates, which is not preferable. The average number of functional groups referred to above is the average number of NCO groups that contributed to the chain elongation reaction per molecule in (B).

In the present invention, the ratio of (A) and (B) is
(B) is 0.1 to 10 times the weight of (A). When the ratio of (B) is less than 0.1 times, (A) is not sufficiently dispersed, so that a stable aqueous pigment dispersion cannot be obtained.
On the other hand, when the ratio of (B) exceeds 10 times, the stability of the aqueous pigment dispersion does not matter, but since the concentration of (A) in the dispersion is low, the coloring function of the aqueous paint or the aqueous printing ink becomes poor. descend. Usually, an aqueous pigment dispersion which is stable at 10 times or less and excellent in coloring function can be obtained.

As a method of obtaining an aqueous pigment dispersion by mixing (A) and (B), a method of collectively kneading (A) and (B) in an attritor, a sand mill, a three-roll mill, a ball mill, or the like. A method in which (A) is charged in advance and (B) is gradually mixed and kneaded, or a method in which (B) is charged in advance and (A) is gradually mixed and kneaded is exemplified.

The aqueous pigment dispersion of the present invention may contain, if necessary, an aqueous resin, a dye, an organic modifier, a stabilizer, a dispersant, a surfactant, an antifoaming agent, a preservative, an antifreezing agent and a thickener. Additives such as agents can be added. Specific examples of these are as follows. Aqueous resin: acrylic, vinyl acetate, vinyl chloride or urethane emulsion, SBR or NBR latex. Dye: direct dye, reactive dye or metal complex dye. Organic modifier: fluororesin powder, silicone resin powder or urethane resin powder. Stabilizer: Hindered phenol, hydrazine, phosphorus, benzophenone, benzotriazole, oxalic acid anilide or hindered amine stabilizer. Dispersant: polyacrylic acid-based dispersant. Surfactant: a nonionic surfactant such as an ethylene oxide adduct of nonylphenol. Antifoaming agent: silicone-based or fluorine-based antifoaming agent. Preservatives: organic nitrogen sulfur compound-based or organic sulfur halogen compound-based preservatives. Antifreeze: ethylene glycol, propylene glycol, and the like. Thickener: cellulose derivative, starch derivative or polyvinyl alcohol.

Further, a crosslinking agent can be added to the aqueous pigment dispersion of the present invention for the purpose of further improving the coating film performance. Examples of the crosslinking agent include amino resins [eg, methylolated and / or alkoxymethylated urea or melamine resins]; polyepoxy compounds [eg, bisphenol A glycidyl ether, hydrogenated bisphenol A]
Alkylene oxide (2 to 3 carbon atoms) was added to glycidyl ether of polyhydric alcohol such as glycidyl ether, ethylene glycol or polyethylene glycol glycidyl ether, glycerin, trimethylolpropane, sorbitol, glycerin, trimethylolpropane, sorbitol, etc. Glycidyl ether]; polyethylene urea compounds (such as diphenylmethane-bis-4.4′-NN′-ethylene urea); polyisocyanate compounds (eg, IPDI and HDI
A polyisocyanate obtained by blocking a trimer of the above with phenol, methyl ethyl ketoxime or ε-caprolactam).

The aqueous pigment dispersion of the present invention is excellent in pigment dispersion stability and water resistance of a coating film, so that it is suitably used as a coloring agent for aqueous paints or aqueous printing inks.

[0023]

EXAMPLES The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. In the following, “part” indicates “part by weight” and “%” indicates “% by weight”.

Production Example 1 A polyethylene adipate diol (number average molecular weight 2000) 16 was placed in a pressure polymerization reactor equipped with a thermometer and a stirrer.
2.0 parts, dimethylolpropionic acid 47.6 parts, n-
After charging 13.8 parts of butanol, 176.0 parts of IPDI, and 400.0 parts of acetone, replacing the reaction system with nitrogen gas, the mixture was reacted at 80 ° C. for 7 hours with stirring to obtain an NCO terminal having an NCO% content of 2.68%. An acetone solution of the urethane prepolymer was obtained. The obtained acetone solution was cooled to 30 ° C., and 35.9 parts of triethylamine was added. Then water 74
Add 2.9 parts to the acetone solution, and add
To remove acetone, solid content 35.0%, viscosity 60cp
Thus, 1142.9 parts (C) of a / 25 ° C. water-soluble urethane resin were obtained.

Production Example 2 A polyethylene adipate diol (number average molecular weight 2000) 17 was placed in a pressure polymerization vessel equipped with a thermometer and a stirrer.
3.9 parts, trimethylolpropane 6.6 parts, dimethylolpropionic acid 47.6 parts, IPDI 171.9 parts,
After charging 400.0 parts of acetone and replacing the reaction system with nitrogen gas, the mixture was reacted at 80 ° C. for 7 hours with stirring to obtain an acetone solution of an NCO-terminated urethane prepolymer having an NCO% content of 2.65%. The obtained acetone solution was cooled to 30 ° C., and 35.9 parts of triethylamine was added. Next, a solution prepared by dissolving 20.0 parts of diethanolamine in 780.09 parts of water was added to the acetone solution.
To remove acetone, solid content 35.0%, viscosity 230c
1200.0 parts of a water-soluble urethane resin having a p / 25 ° C (D)
I got

Production Example 3 Polycaprolactone diol (number average molecular weight 2000) 246.7 was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
Parts, 7.4 parts of 1,4 butanediol, 5.1 parts of trimethylolpropane, 17.9 of dimethylolpropionic acid
Parts, 123.0 parts of IPDI, and 400 parts of acetone, the reaction system was replaced with nitrogen gas, and the mixture was reacted at 80 ° C. for 7 hours with stirring to obtain an NCO-terminated urethane prepolymer having an NCO% content of 1.67%. . The obtained acetone solution was cooled to 30 ° C., and 13.5 parts of triethylamine was added. Next, 600.0 parts of water was added to the acetone solution, and acetone was removed at 50 to 60 ° C. under reduced pressure to obtain a solid content of 40.0 parts.
% Aqueous urethane resin dispersion 1 having a viscosity of 350 cp / 25 ° C.
000.0 parts (E) were obtained.

Example 1 100 parts of titanium oxide, 30 parts of (C) obtained in Production Example 1, and 70 parts of water were blended and kneaded with a ball mill to obtain a pigment dispersion. In 100 parts of the dispersion, butyl cellosolve and Cymel 3 were added.
No. 03 (manufactured by Mitsui Cyanamid Co., Ltd., methoxylated methylol melamine) and (E) obtained in Production Example 3 were blended in the proportions shown in Table 1, and then uniformly mixed with a paint conditioner to obtain an aqueous paint. The storage stability of the paint and the water resistance of the coating film were tested. Table 1 shows the results.

Example 2 100 parts of titanium oxide, 30 parts of (D) obtained in Production Example 2, and 70 parts of water were blended and kneaded with a ball mill. Hereinafter, a water-based paint was prepared in the same manner as in Example 1, and the same test as in Example 1 was performed. Table 1 shows the results.

Comparative Example 1 Titanium oxide 100 parts, Carribbon L-400 (a polycarboxylic acid type pigment dispersant manufactured by Sanyo Chemical Industries, Ltd.) 1.2
And 98.8 parts of water, and kneaded with a ball mill to obtain a pigment dispersion. Hereinafter, a water-based paint was prepared in the same manner as in Example 1, and the same test as in Example 1 was performed. Table 1 shows the results.

[0030]

[Table 1]

Test Method Stability of paint: The paint was stored at 25 ° C. for 14 days, and the presence or absence of sedimentation of the pigment was visually observed. Water resistance of the coating film: The coating material was applied to a tin plate using a spray gun to a dry film thickness of 20 μm, baked at 180 ° C. for 10 minutes, and then immersed in 40 ° C. warm water for 30 days. The blisters and gloss were visually observed.

[0032]

The aqueous pigment dispersion of the present invention not only exhibits good coloring performance as a coloring agent for aqueous paints and aqueous printing inks, but also has excellent pigment settling stability during storage of paints and inks. And significantly improves the water resistance of the coating film, which is extremely useful industrially.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // C08G 18/00 C08G 18/00 C 18/10 18/10 C08L 75/04 C08L 75/04 (56) References JP JP-A-62-109813 (JP, A) JP-A-63-37160 (JP, A) JP-A-55-134635 (JP, A) JP-A-55-99951 (JP, A) JP-A-55-110113 (JP, A) JP-A-5-9405 (JP, A) JP-A-4-218577 (JP, A) JP-A-6-166735 (JP, A) JP-A-64-20221 (JP, A) 53-106753 (JP, A) JP-A-62-256817 (JP, A) JP-A-5-132567 (JP, A) JP-A-5-320361 (JP, A) (58) Fields investigated (Int. Cl ^7, DB name) C08G 18/00 -. 18/87 C08L 75/00 - 75/16 C09D 175/00 - 175/16 C09D 17/00 CA (STN) REGISTRY (ST N)

Claims (5)

(57) [Claims] An aqueous pigment wherein the pigment (A) is mixed and dispersed in the following water-soluble urethane resin (B), and the amount of (B) is 0.1 to 10 times the weight of (A). A colorant for a water-based paint or a water-based printing ink, comprising a dispersion. Water-soluble urethane resin (B): a water-soluble urethane resin obtained by extending a NCO-terminated urethane prepolymer (b) having a hydrophilic group having a hydrophilic group content of 0.1 to 20% by weight with water and / or a polyamine. there are, and monoalcohols and / or monoamines (said monoamine is -NH ₂ or = NH and has) produced by capping a portion of the NCO groups in (b), in a case where using the average functionality (alkanolamine Is -NH
Water-soluble urethane resin in which ₂ or = NH alone is calculated as an active hydrogen-containing group) is less than 2. 2. The colorant according to claim 1, wherein (B) is a resin having an anionic group. 3. The aqueous pigment dispersion further comprises an acrylic pigment,
The colorant according to claim 1, comprising a vinyl acetate-based, vinyl chloride-based, or urethane-based emulsion, or an SBR-based or NBR-based latex. 4. A water-based paint containing the colorant according to claim 1. 5. An aqueous printing ink containing the colorant according to claim 1.