JPH086049B2 - Aqueous pigment dispersion - Google Patents

Description

The present invention relates to an aqueous pigment dispersion liquid which is easy to produce using a novel dispersant and has excellent storage stability.

Conventionally, in water-based paints such as emulsion paints and water-soluble resin paints that contain pigments, the coloring effect of the coating surface is reduced due to the difficulty of dispersion of the pigments during production and the aggregation / sedimentation of the pigments during storage, flooding, It is well known that undesired phenomena such as flooding and loss of gloss occur. Therefore, in general, an aqueous pigment dispersion liquid in which pigments are previously dispersed with a dispersant is prepared, and this is mixed and dispersed in an aqueous coating material to be colored to color the aqueous coating material.

A low molecular weight compound such as a surfactant is used as a dispersant in the conventional aqueous pigment dispersion liquid, but there is a harmful effect of the dispersant, that is, a secondary adverse effect that the coating performance or the coating state is deteriorated. Inevitably, in recent years, it is the actual situation that the deterioration of coating film performance and the like is suppressed by using an oligomer or a polymer having a medium molecular weight as a dispersant.

However, when an oligomer or a polymer is used as the dispersant, the amount used is larger than that of the low-molecular-weight surfactant, and the resulting aqueous pigment dispersion is used according to the type of binder used in the aqueous paint. There are drawbacks such as being limited by This goes against the rationalization in the production of paints, and therefore there is a strong demand for the development of an aqueous pigment dispersion common to various water-based paints.

Conventionally, as a dispersant component that can easily disperse a pigment in a small amount, has compatibility with various water-based resins, and does not cause deterioration of coating film performance of water-based paint by itself, this patent application A copolymer obtained by carrying out a copolymerization reaction between an unsaturated monomer having a hydrophobic long-chain group itself, a nitrogen-containing unsaturated monomer and an ethylenically unsaturated carboxylic acid (JP-A-59-227940). JP, JP-A-60-81252, JP, JP-A-6
0-81253, JP-A 61-103537, JP-A 61-
No. 235466).

These copolymer compositions have a comb structure in which the hydrophobic part and the hydrophilic part are well balanced, and contain a nitrogen component and a carboxyl group, which have excellent adsorbability for pigments, and are extremely soluble in an aqueous solution. It had a high surface activity and exhibited excellent pigment dispersibility with a smaller amount than the conventional water-soluble resin.

However, the aqueous pigment dispersion obtained by using the above copolymer composition as a dispersant has excellent pigment dispersibility at the time of production, but in the long-term storage of the dispersion, the pigments are aggregated to form a part. A solid or totally solid caking state cannot be restored to the state before storage even if the product is re-dispersed with a stirrer. It had the problem of causing defects.

Therefore, as a result of diligent efforts to solve the above problems, the present inventor has found that a monomer having a fatty acid group as a monomer component, a macromonomer obtained by polymerization of a nitrogen-containing unsaturated monomer, and α, β The present invention has been completed by finding that the above problems can be solved by using a copolymer containing an ethylenically unsaturated carboxylic acid as an essential monomer component as a pigment dispersion stabilizer.

That is, the present invention provides an aqueous pigment dispersion liquid comprising a pigment, a dispersant and an aqueous medium, wherein the dispersant is a modified vinyl unsaturated monomer (A) having a C ₈ or more fatty acid residue at the molecular end ( Hereinafter, this is referred to as "modified vinyl monomer") 3 to 90 parts by weight (B) At least one vinyl-polymerizable functional group selected from acryloyloxy, methacryloyloxy, allyloxy, and aromatic vinyl is attached to one end. Nitrogen-containing macromonomer having (hereinafter, referred to as "nitrogen-containing macromonomer") 2 to 90 parts by weight (C) α, β-ethylenically unsaturated carboxylic acid 1 to 30 parts by weight (D) above (A) to Provided is an aqueous pigment dispersion, which is an aqueous product of a copolymer obtained by copolymerizing 0 to 91 parts by weight of an α, β-ethylenically unsaturated monomer other than (C). .

According to the present invention, the above copolymer has a structure in which a long-chain component having strong hydrophobicity is bonded in a separated form to a main chain containing a specific nitrogen-containing monomer having strong hydrophilicity derived from a macromonomer. When the pigment is dispersed in water using this, the long chain component separated from the main chain of the copolymer while the functional group of the copolymer is adsorbed or chemically bonded to the pigment particles. Is entangled with the long-chain component of other copolymers to form a barrier layer having strong hydrophobicity by wrapping around the pigment particles and forming a hydrophilic component dispersed in water to stabilize the pigment in an aqueous medium. It is possible to obtain a different aqueous pigment dispersion. As described above, the aqueous pigment dispersion liquid is surrounded by the barrier layer having a hydrophobic component between the pigment and water and having a component excellent in hydrolysis resistance. In addition, since the barrier layer is composed of a component having a large steric hindrance, the pigments can be prevented from approaching each other, and as a result, there is no settling or agglomeration and excellent storage properties are exhibited. Further, since the copolymer has a surface activity that is excellent in the balance between the hydrophobicity derived from the long-chain component and the hydrophilicity derived from the macromonomer component, the pigment dispersibility and the property excellent in storage properties are improved. Show. Further, since the macromonomer component has a large nitrogen content obtained by copolymerizing or homopolymerizing a nitrogen-containing unsaturated monomer, it strongly adsorbs or binds to the pigment, so that the pigment dispersibility and storage stability are stable. It is possible to obtain a dispersion having excellent properties. The nitrogen-containing component in the copolymer can be easily and surely introduced by using the macromonomer component used in the present invention. Furthermore, since the dispersion has a low acid value, that is, a small amount of carboxyl groups, a colored coating film excellent in performance such as water resistance can be obtained.

Hereinafter, the dispersant used in the aqueous pigment dispersion liquid of the invention will be described in detail.

Modified vinyl-based monomer (A): The modified vinyl-based monomer used in the dispersant of the present invention includes a monomer containing a C ₈ or more fatty acid residue and an ethylenically unsaturated bond at the molecular end. Examples thereof include monomers obtained by modifying a monomer containing an ethylenically unsaturated bond with a modifying agent such as C ₈ or higher oil, fatty acid, fatty acid alcohol, fatty acid glycidyl ester or fatty acid amine.

The monomer containing an ethylenically unsaturated bond,
A monomer having a functional group such as a hydroxyl group, a carboxyl group, a glycidyl group, an isocyanate group, and an aziridine group in the molecule. Specifically, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc. Hydroxyl group-containing monomer; (meth) acrylic acid, carboxyethyl (meth) acrylic acid, (anhydrous) maleic acid, itaconic acid, and other carboxyl group-containing unsaturated monomers;
Glycidyl group-containing unsaturated monomers such as glycidyl (meth) acrylate, allyl glycidyl ether, and vinylphenyl glycidyl ether; addition products of diisocyanate compound and hydroxyalkyl (meth) acrylate (1: 1), α, α-dimethyl- Examples thereof include isocyanate group-containing unsaturated monomers such as m-isopropenylbenzyl isocyanate and isocyanate ethyl (meth) acrylate; and aziridine group-containing unsaturated monomers such as aziridinyl ethyl (meth) acrylate.

In addition, as the modifier, there may be mentioned C ₈ or higher oils and fats, fatty acids, aliphatic alcohols, fatty acid glycidyl esters, fatty acid amines, and the like. Specifically, lauric acid, 2-ethylhexanoic acid, stearic acid, etc. are synthesized. Saturated fatty acids; coconut oil, olive oil, castor oil, safflower oil, linseed oil,
Soybean oil, sesame oil, tall oil, cottonseed oil, dehydrated hyacinth oil and fatty acids thereof; 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol and other aliphatic alcohols; Cardura E (Shell Chemical Co., glycidyl ester of versatic acid), etc. Glycidyl ester of fatty acid; fatty acid amines such as octylamine, dodecylamine, stearylamine and the like.

The modified vinyl-based monomer (A) includes the following.

(I) Alkyl ester of (meth) acrylic acid; for example, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and the like.

(Ii) Addition product of glycidyl group-containing unsaturated monomer and fatty acid (JP-A-59-227940); for example, addition product of glycidyl (meth) acrylate and safflower oil fatty acid.

(Iii) Isocyanate group-containing unsaturated monomer
No. 1-235466); for example, a reaction product of tolylene diisocyanate / 2-hydroxyethyl methacrylate (molar ratio 1/1) adduct and oleyl alcohol.

(Iv) Esterification product of hydroxyl group-containing unsaturated monomer and fatty acid (JP-A-59-227940); for example, esterification product of 2-hydroxyethyl methacrylate and linseed oil fatty acid.

(V) Addition product of unsaturated monomer containing aziridine group and fatty acid (JP-A-61-103537); for example, addition product of aziridinyl ethyl methacrylate and linseed oil fatty acid.

Nitrogen-containing macromonomer (B): The macromonomer used in the dispersant of the present invention has a polymer obtained by polymerizing a nitrogen-containing unsaturated monomer as a molecular main chain, and acryloyl is attached to one end of the main chain. It has a radical-polymerizable unsaturated group such as oxy, methacryloyloxy, allyloxy and styryl.

The nitrogen-containing unsaturated monomer component constituting the above molecular chain is, for example, one or more of unsaturated monomers having a nitrogen-containing heterocycle or a nitrogen-containing derivative of (meth) acrylic acid. It is obtained by homopolymerization or copolymerization of monomers.

[1] As unsaturated monomers having a nitrogen-containing heterocyclic ring, 1 to
It includes monomers in which a monocyclic or polycyclic heterocyclic ring containing three, preferably one or two ring nitrogen atoms is bonded to a vinyl group, and particularly includes the following monomers.

(I) Vinylpyrrolidones; for example, 1-vinyl-2-pyrrolidone, 1-vinyl-3
-Pyrrolidone, etc.

(II) Vinyl pyridines; for example, 2-vinyl pyridine, 4-vinyl pyridine, 5
-Methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine and the like.

(III) Vinylimidazoles; For example, 1-vinylimidazole, 1-vinyl-2-methylimidazole and the like.

(IV) Vinylcarbazoles; for example, N-vinylcarbazole and the like.

(V) vinylquinolines; for example, 2-vinylquinoline and the like.

(VI) vinylpiperidines; for example, 3-vinylpiperidine, N-methyl-3-vinylpiperidine and the like.

(VII) Others; For example, formula (Where R ₁ has the above-mentioned meaning)
(Meth) acryloylmorpholine and formula (Where R ₁ has the above-mentioned meaning)
(Meth) acryloylpyrrolidine and the like.

Among the above-mentioned vinyl monomers having a nitrogen-containing heterocycle, vinylpyrrolidones, vinylimidazoles and vinylcarbazoles are preferable, and those in which the ring nitrogen atom is tertiaryized are preferable.

[2] Nitrogen-containing derivatives of (meth) acrylic acid include those having a substituted or unsubstituted amino group in the ester portion of (meth) acrylic acid ester, amides of (meth) acrylic acid and those substituted in the amide portion. Those containing an amino group are included, and in particular, the following formulas (I) to (III) In the above formulas, R ₁ represents the above meaning, R ₂ and R ₃ each independently represent a hydrogen atom or a lower alkyl group, R ₄ represents a hydrogen atom or a lower alkyl, and R ₅ represents a hydrogen atom, a lower atom. Represents an alkyl group, a di (lower alkyl) amino lower alkyl group, a hydroxy lower alkyl group or a lower alkoxy lower alkyl group, and n represents an integer of 2 to 8, wherein aminoalkyl (meth) acrylate and (meth) acrylamide Is suitable. Where "low"
Means that the group to which it is attached has 6 or fewer carbon atoms,
It means that the number is preferably 4 or less.

As a specific example of such a nitrogen-containing (meth) acrylic monomer, an aminoalkyl (meth) of the above formula (I) is shown.
Examples of acrylates include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth). ) Acrylate, N, N-dimethylaminobutyl (meth) acrylate, N-propylaminoethyl (meth) acrylate, N-butylaminoethyl (meth) acrylate and the like, and aminoalkyl (meth) of the above formula (II). ) Examples of acrylamide include N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide and the like, and examples of (meth) acrylamide of (III) above include ( (Meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylic Bromide, N-
Butyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N
-Methylol (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethylaminopropylacrylamide and the like. As these nitrogen-containing (meth) acrylic monomers, those having a tertiary nitrogen atom are most suitable, and those having a secondary tertiary atom are also suitably used. Among them, N, N-dimethylacrylamide and N, N-dimethylaminopropyl (meth) acrylamide, which have excellent hydrolysis resistance, are preferable.

The α, β-ethylenically unsaturated nitrogen-containing monomers described above can be used alone or in combination of two or more.

Preparation of the macromonomer to be used in the present invention is carried out according to a conventionally known method. For example, the above-mentioned monomer can be used, for example, a chain transfer agent having a carboxyl group such as thioglycolic acid and, for example, azobisisobutyronitrile , A prepolymer having a carboxyl group at one end obtained by a polymerization reaction in the presence of a polymerization initiator such as benzoyl peroxide, or the above monomer, for example, azo-based having a carboxyl group such as azobiscyanovaleric acid A prepolymer having a carboxyl group at one end obtained by performing a polymerization reaction in the presence of a polymerization initiator and a tertiary amine is reacted with a vinyl monomer having a functional group capable of reacting with a carboxyl group of the prepolymer. It can be done by doing. As the above-mentioned vinyl monomer, typically, for example, glycidyl acrylate, glycidyl methacrylate,
-Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. containing acryloyloxy or methacryloyloxy group-containing monomers; allyl alcohol, allyl glycidyl ether, etc. containing allyloxy groups Examples thereof include monomers and monomers containing an aromatic vinyl group such as p-isopropenylphenyl glycidyl ether and p-vinylphenyl glycidyl ether.

The molecular weight of the macromonomer used in the present invention can have a number average molecular weight of 500 to 15,000, preferably 700 to 10,000. When the molecular weight is less than 500, the storage stability of the aqueous pigment dispersion is improved. Poor, while the molecular weight is 15,0
If it is greater than 00, the molecular weight of the main chain and the side chain are out of balance, resulting in poor pigment dispersibility and storage stability of the aqueous pigment dispersion.

α, β-ethylenically unsaturated carboxylic acid (C): The α, β-ethylenically unsaturated carboxylic acid used in the dispersant of the present invention includes a carbon atom to which a carboxyl group is bonded and a carbon atom adjacent to the carbon atom. An unsaturated fatty acid mono- or polycarboxylic acid of a type having an addition-polymerizable double bond between them, which contains 3 to 8, particularly 3 to 5 carbon atoms and has 1 or 2 carboxyl groups is suitable. Examples thereof include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid and the like.

Other α, β-ethylenically unsaturated monomer (D): Further, α, β-other than (A), (B), and (C) above.
The ethylenically unsaturated monomer (D) is not particularly limited and can be widely selected according to the performance desired for the dispersant of the present invention. Representative examples of such unsaturated monomers are as follows.

(1) Ester of acrylic acid or methacrylic acid: for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid allyl acrylate, C ₂ ~ ₇ alkenyl esters of acrylic acid or methacrylic acid and allyl methacrylate; acid isopropyl, butyl Mekuriru acid, C ₁ ~ ₇ alkyl esters of acrylic acid or methacrylic acid hexyl methacrylate such as hydroxyethyl acrylate, hydroxyethyl ethyl methacrylate, hydroxypropyl acrylate, C ₂ ~ ₇ hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl methacrylate; allyloxyethyl a Relate, acrylic acid or C ₃ ~ ₇ alkenyloxy alkyl esters of methacrylic acid such as allyloxy methacrylate.

(2) Vinyl aromatic compound: For example, styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene.

(3) Polyolefin compound: For example, butadiene,
Isoprene, chloroprene.

(4) Others: acrylonitrile, methacrylonitrile, methyl isopropenyl ketone; vinyl acetate, vinyl propionate, etc.

In addition to the above-mentioned monomers (1) to (4), the above-mentioned nitrogen-containing unsaturated monomer can be used.

Among the above-mentioned monomers, it is preferable to use acrylic acid, methacrylic acid ester, vinyl aromatic compound and the like from the viewpoint of polymerization rate, copolymerizability and the like.

The unsaturated monomer is appropriately selected according to the desired physical properties and may be used alone or in combination of two or more kinds.

According to the present invention, the modified vinyl monomer (A) described above,
The nitrogen-containing macromonomer (B), the α, β-ethylenically unsaturated carboxylic acid (C) and the unsaturated monomer (D) are copolymerized with each other. The copolymerization can be carried out according to a method known per se for producing an acrylic copolymer, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method or the like.

When performing the copolymerization, the mixing ratio of the above five components can be changed depending on the performance desired as a dispersant,
It is suitable to blend in the following proportions.

Modified vinyl monomer (A): 3 to 90 parts by weight, preferably 10 to 80 parts by weight in view of pigment dispersibility and storage stability, nitrogen-containing macromonomer (B): 2 to 90 parts by weight, preferably pigment From the viewpoint of dispersibility and storage stability, 3 to 70 parts by weight, α, β-ethylenically unsaturated carboxylic acid (C): 1 to 30 parts by weight, preferably 2 to 20 parts by weight from the viewpoint of water solubility and coating film performance. , Unsaturated monomers (D) other than the above (A) to (C): 0 to 91
Parts by weight, preferably 5 to 85 parts by weight from the viewpoint of coating film performance.

The above-mentioned copolymerization reaction is advantageously carried out preferably by a solution polymerization method, and the above-mentioned four components are usually in the presence of a polymerization catalyst in a suitable inert solvent, usually about 0 to about 180 ° C., preferably about At a reaction temperature of 40 to about 170 ° C, about 1 to about 20
The reaction can be carried out for a period of time, preferably about 6 to about 10 hours.

As the solvent to be used, it is desirable to use a solvent that can dissolve the copolymer produced and be miscible with water so that gelation does not occur during the copolymerization reaction. In particular, those which can be used as they are without removal when obtaining the aqueous pigment dispersion are preferable. Examples of the solvent for example, the formula HO-CH ₂ CH ₂
-OR ₆ [wherein R ₆ is hydrogen atom or 1 to 8 carbon atoms]
Representing one alkyl group], such as ethylene glycol, butyl cellosolve, ethyl cellosolve; [Wherein R ₆ has the same meaning as described above] such as propylene glycol solvent such as propylene glycol monomethyl ether; Formula HO—CH ₂ CH ₂ —OCH ₂ CH ₂ —OR ₆ [wherein R ₆ has the same meaning as described above] A carbitol-based solvent, such as diethylene glycol, methyl carbitol, or butyl carbitol: R ₇ O—CH ₂ CH ₂ —OR ₈ [wherein R ₇ and R ₈ each have 1 to 3 carbon atoms] Representing an alkyl group of], such as ethylene glycol dimethyl ether; formula R ₇ O—CH ₂ CH ₂ OCH ₂ —CH ₂
A diglyme-based solvent of OR ₈ [wherein R ₇ and R ₈ have the same meanings as described above] such as diethylene glycol dimethyl ether; and the formula R ₉ O—CH ₂ CH ₂ OCO—CH ₃ [wherein R ₉
Cellosolve acetate-based solvents such as ethylene glycol monoacetate represents a hydrogen atom or a CH ₃ or C ₂ H _5], and methyl cellosolve acetate; formula R ₁₀ O
Alcohol solvents such as H [wherein R ₁₀ represents an alkyl group having 1 to 4 carbon atoms] such as ethanol and propanol; and diacetone alcohol, dioxane, tetrahydrofuran, acetone, dimethylformamide, 3-methoxy-3 -Methyl-butanol and the like can be used.

However, an inert solvent which is not miscible with water can also be used, and such a water-immiscible solvent has a boiling point of 250 ° C. or less so that it can be easily removed by distillation under normal pressure or reduced pressure after the completion of the polymerization reaction. Is preferred. Examples of such a solvent include those represented by the formula: Wherein R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Wherein R ₁₂ and R ₁₃ each represent an alkyl group having 1 to 4 carbon atoms;
Such as toluene, xylene and the like; wherein R ₁₄ -COO-R
Acid or ester represented by ₁₅ [wherein R ₁₄ represents an alkyl group having 1 to 6 carbon atoms, R ₁₅ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms or a cyclohexyl group], for example, Acetic acid, ethyl formate, butyl acetate, cyclohexyl acetate, etc .; Formula R ₁₆ R ₁₇ C═O
[Wherein R ₁₆ and R ₁₇ each represent an alkyl group having 1 to 8 carbon atoms] and Ketones represented by, for example, methyl ethyl ketone,
Cyclohexanone, etc .: Formula R ₁₆ —O—R ₁₇ [wherein R ₁₆
And R ₁₇ have the same meaning as described above], for example, ethyl ether, hexyl ether and the like; represented by the formula R ₁₈ OH, wherein R ₁₈ represents an alkyl group having 5 to 11 carbon atoms. Alcohols, for example, hexanol.

These solvents are 15 to 90% of the total weight of the above-mentioned four copolymer components.
It can be used in the range of weight%.

Further, as the polymerization catalyst, for example, azo compounds, perchoxide compounds, sulfides, sulfines,
Radical initiators that can be used for ordinary radical polymerization such as sulfinic acids, diazo compounds, nitroso compounds, redox systems and ionizing radiation are used.

In the present invention, a substantially satisfactory aqueous pigment dispersion can be obtained even if the molecular weight of the produced copolymer is changed,
If the molecular weight is too low, the physical properties of the coating film of the aqueous coating material to be colored may deteriorate. Further, when the molecular weight is too high, the viscosity becomes high, and when the viscosity is lowered, the concentration of the copolymer is lowered and the dispersibility of the pigment is lowered.
Generally, the number average molecular weight of the resulting copolymer is about 2,000-
Advantageously, it is carried out until it is in the range of about 150,000, preferably about 2,500 to about 100,000.

The copolymer resin thus produced is made water-soluble as it is or after the solvent is distilled off. This water solubilization can be carried out by a conventional method, for example, by neutralizing a carboxyl group present in the copolymer resin with a conventionally known neutralizing agent. Examples of neutralizing agents that can be used include ammonia, amines, alkali metal hydroxides, alkali metal carbonates and bicarbonates, and the like. As the amine, a primary, secondary or tertiary alkylamine; primary, secondary or tertiary alkanolamine; and cycloalkylamine can be used.
Further, potassium hydroxide, sodium hydroxide and the like can be used as alkali metal hydroxides; potassium carbonate, sodium carbonate, sodium bicarbonate and the like can be used as alkali metal carbonates and bicarbonates.

The neutralization treatment can be easily carried out by a conventional method by adding the above-mentioned neutralizing agent or its aqueous solution to the copolymer resin or its solution obtained as described above. The amount of the neutralizing agent used is generally 0.1 to 2.0 equivalents, preferably 0.3 to 1.0 equivalents, relative to the carboxyl groups in the resin.

The water-solubilized polymer thus obtained is used as a dispersant in an aqueous pigment dispersion containing a pigment, a dispersant and an aqueous medium.

The amount of the dispersant comprising the water-soluble polymer is the amount of the pigment.
Generally about 1 to 500 parts by weight, preferably about 1 per 100 parts by weight.
It can be up to 300 parts by weight. If the upper limit of this range is exceeded, the balance between the coloring power and the viscosity of the aqueous pigment dispersion tends to be unbalanced, while if the lower limit is not reached, the dispersion stability of the pigment tends to decrease.

The aqueous medium used in the aqueous pigment dispersion of the present invention is substantially water, but if necessary, for example, when the degree of hydrophilicity of the dispersant is low and sufficient pigment dispersion performance cannot be obtained. A hydrophilic organic solvent can be used together. As the hydrophilic organic solvent, those used in the production of the polymer may be used alone or in combination.

Further, the pigment used in the aqueous pigment dispersion of the present invention,
Inorganic and organic pigments usually used in this type of pigment dispersion can be used. Examples of the inorganic pigment include (1) oxide-based (zinc white, titanium dioxide, red iron oxide, chromium oxide, cobalt blue, iron). (Black, etc.); (2) Hydroxide type (alumina white, yellow iron oxide, etc.); (3)
Sulfide, selenide type (zinc sulfide, vermilion, cadmium yellow, cadmium red, etc.); (4) ferrocyanide type (dark blue, etc.); (5) chromate type (yellow lead, zinc chromate, molybdenum red, etc.) (6) Sulfate system (precipitating barium sulfate, etc.); (7) Carbonate system (precipitating calcium carbonate, etc.); (8) Silicate system (hydrous silicate, clay, ultramarine, etc.); (9 ) Phosphate-based (manganese violet, etc.);
(10) Carbon-based (carbon black, etc.); (11) Metal powder-based (aluminum powder, bronze powder, zinc dust, etc.) and the like, and organic pigments include (1) nitroso pigment-based (naphthol green B etc.) ); (2) Nitro pigment system (naphthol yellow S etc.); (3) Azo pigment system (resole red, lake red C, fast yellow, naphthol red, red etc.); (4) Dye lake pigment system (alkali blue) Lake, rhodamine lake, etc.); (5) phthalocyanine pigment system (phthalocyanine blue, fast sky blue etc.); (6) condensed polycyclic pigment system (perylene red,
Quinacridone red, dioxazine violet, isoindolinone yellow, etc.) and the like.

The content of the pigment in the aqueous pigment dispersion of the present invention is not particularly limited, but it is generally about 2 to 90% by weight based on the weight of the dispersion.

The aqueous pigment dispersion of the present invention can be prepared by mixing together the above components in a suitable dispersing device. As a dispersing device that can be used, a ball mill commonly used in the paint industry is used. , Roll mill, homomixer, sand grinder, shaker,
Attritors are listed.

If necessary, a conventionally known surfactant or protective colloid can be added to the aqueous pigment dispersion liquid of the present invention.

Thus, the aqueous pigment dispersion of the present invention is a conventionally known water-soluble resin such as an alkyd resin, an acrylic resin, an epoxy resin, a urethane resin, a maleinized polybutadiene resin, or the like, which is used for an aqueous paint and an aqueous ink, a water dispersion. It has good miscibility with organic resins and emulsions and is not limited by these resins, and can be widely used for coloring water-based paints made of any resin.

As specific examples of the above-mentioned aqueous resin, for example, an alkyd resin is obtained by synthesizing the same raw material as a conventional solvent-type alkyd resin, and polycondensing a polybasic acid, a polyhydric alcohol, and an oil component by a conventional method. is there. Acrylic resin
α, β-ethylenically unsaturated acids (eg acrylic acid, methacrylic acid, maleic acid etc.), (meth) acrylic acid esters (eg ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate) , Propyl methacrylate, butyl methacrylate, etc.) and vinyl aromatic compounds (eg styrene,
Vinyltoluene, etc.). As the epoxy resin, a method of synthesizing an epoxy ester by reacting an epoxy group of the epoxy resin with an unsaturated fatty acid and adding α, β-unsaturated acid to the unsaturated group, a hydroxyl group of the epoxy ester, a phthalic acid or a triethyl ester Examples thereof include epoxy ester resins obtained by a method of esterifying a polybasic acid such as mellitic acid.

Further, as the urethane-based resin, a polyisocyanate compound (for example, toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, etc.) is used to introduce a urethane group into the resin skeleton, and dimethylolpropion A carboxyl group is introduced using an acid or the like.

When the above-mentioned aqueous resin is made water-soluble, it is synthesized so that the acid value of the resin becomes about 35 to 200, and this is neutralized with an alkaline substance, for example, sodium hydroxide, amine, etc. It is used as a paint. On the other hand, when these resins are used in a self-dispersion type, they are made into low acid value type resins having an acid value of about 5 to 35, and these are neutralized to be used in a water dispersion type coating material.

As the emulsion, an emulsifier-dispersed emulsion obtained by dispersing an alkyd resin, an acrylic resin, an epoxy resin, or a urethane resin using an anionic or nonionic low-molecular-weight surfactant; using the above-mentioned surfactant (meta) Emulsion polymerization emulsion obtained by emulsion polymerization of monomers such as acrylate, acrylonitrile, styrene, butadiene, vinyl acetate, vinyl chloride; maleated polybutadiene, maleated alkyd resin, maleated fatty acid modified vinyl resin, drying oil or Soap-free emulsions obtained by subjecting the above-mentioned monomers to emulsion polymerization and graft reaction using a water-soluble resin such as a semi-drying oil fatty acid-modified acrylic resin as an emulsion stabilizer are mentioned.

The aqueous pigment dispersion liquid of the present invention is particularly effective for blending with an aqueous coating material comprising a low acid value water-dispersible resin and an emulsion having poor pigment dispersibility. Above all, the effect is particularly remarkable for the low acid value water-dispersible resin and emulsion having the oxidative curability.

The blending ratio of the aqueous pigment dispersion of the present invention to the aqueous paint can be varied within a wide range depending on the type of pigment in the dispersion and the degree of coloring required for the final paint.
Generally, the pigment dispersion can be blended in the range of 2 to 1,000 parts by weight per 100 parts by weight of the resin component of the above-mentioned water-based paint.

Next, the present invention will be further described with reference to examples. In the examples, parts and% mean parts by weight and% by weight.

Reference Example (A-1) Safflower oil fatty acid 236 parts Glycidyl methacrylate 119 parts Hydroquinone 0.4 parts Tetraethylammonium bromide 0.2 parts were placed in a reaction vessel. Stir the reaction at 140-150 ℃
At a temperature of 1 to obtain an addition reaction product of the fatty acid-modified acrylic monomer (A-1). The addition reaction between the epoxy group and the carboxyl group was followed while measuring the amount of the residual carboxyl group. It took about 4 hours to complete the reaction.

Reference Example (A-2) Flaxseed oil fatty acid 364 parts Aziridinylethylmethacrylate 208 parts Hydroquinone 0.6 parts After putting the above components in a reaction vessel, the reaction temperature was kept at 140 to 150 ° C. while stirring the reaction solution. An addition reaction was performed. The addition reaction between the epoxy group and the carboxyl group was followed while measuring the amount of the residual carboxyl group. A fatty acid-modified acrylic monomer (A-2) was obtained with a reaction time of about 4 hours.

Reference Example (A-3) 2-hydroxyethyl methacrylate was added to a reaction vessel.
278 parts, 208 parts of toluene diisocyanate and 0.1 part of hydroxynone were added and reacted at 60 ° C. for 3 hours to obtain an unsaturated monomer having an isocyanate group. Then, 430 parts of oleyl alcohol was added to 486 parts of the unsaturated monomer having an isocyanate group obtained above, and the mixture was reacted at 80 ° C. for 3 hours to obtain an unsaturated monomer having a urethane bond (A-3). .

Reference Example (B-1) 250 parts of ethanol was charged into a reaction vessel, and the temperature was raised to 70 ° C. Then 4,4'-azobisisobutyronitrile 12.
Polymerization was carried out by adding 5 parts of a monomer solution prepared by dissolving 250 parts of N-vinyl-2-pyrrolidone and a solution prepared by dissolving 17.5 parts of mercaptoacetic acid in 80 parts of ethanol separately over 2 hours. After completion of polymerization, cool to 20 ° C and use diethyl ether.
The mixture was added to 10,000 parts to cause coagulation and then settling, and the obtained powder was dried under reduced pressure at 10 mmHg at 80 ° C. for 10 hours. The acid value of the powder was 26.1.

Next, 213 parts of ethyl cellosolve and 200 parts of the above powder were added to another reaction container, and the temperature was raised to 70 ° C. to completely dissolve the powder. Once cooled to 20 ° C, 13.2 parts of glycidyl methacrylate, tetraethylammonium bromide 0.
Charge 2 parts and hydroquinone 0.3 parts and react at 120 ° C for 5 hours to obtain 49% of N-vinyl-2-pyrrolidone with acid value 0.5.
A macromonomer solution (B-1) was obtained.

Reference Example (B-2) 200 parts of ethanol was charged into a reaction vessel, and the temperature was raised to 70 ° C. N-vinyl-2-pyrrolidone 100 parts, ethanol 1
A solution in which 00 parts and 4,4′-azobis (4-cyano) valeric acid 20 parts were mixed and dissolved was added dropwise over 2 hours. 20 ℃ after dropping
The resulting powder was reprecipitated and dried under reduced pressure at 10 mmHg at 80 ° C. for 10 hours. The acid value of the powder was 34.2.

Next, in another reaction vessel, 104 parts of ethyl cellosolve and 95 parts of the above powder were charged, and the temperature was raised to 70 ° C. to completely dissolve the mixture, and 20 ° C.
Cooled to 8.3 parts glycidyl methacrylate, 0.2 parts tetraethylammonium bromide, 0.2 parts hydroquinone
Was charged for 5 hours and reacted at 115 ° C. for 5 hours to prepare a 50% macromonomer solution of N-vinyl-2-pyrrolidone (B-
2) was obtained.

Reference Example (B-3) Instead of N-vinyl-2-pyrrolidone of Reference Example 1,
Using N, N-dimethylaminoacrylamide, an acid value of 1.5
51% macromonomer (B-3) of N, N'-dimethylaminoacrylamide was obtained.

Example 1 292 parts of n-butyl cellosolve was placed in a reaction vessel and heated to 120 ° C. Next, the mixture in the proportions shown below was added dropwise to this solution over about 2 hours. The reaction was carried out under nitrogen injection.

Fatty acid-modified acrylic monomer (A-1) 94 parts Macromonomer (B-1) 41 parts Acrylic acid 15 parts 2-Hydroxyethylmethacrylate 79 parts Azobisdimethylvaleronitrile 14 parts Reaction solution kept at 120 ° C While stirring, the above mixture was added dropwise. After 1 hour from the end of the dropping, 2.0 parts of azobisisobutyronitrile was added to the reaction solution, and after 2 hours, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and then the reaction was carried out for 2 hours while maintaining the temperature at 120 ° C. It was After completion of the reaction, the unreacted monomer and n-butyl cellosolve were distilled under reduced pressure to obtain a copolymer solution having a heating residue of 70.3%, a resin acid value of 48.9, and a Gardner viscosity (40% n-butyl cellosolve solution) H. Further, this copolymer was neutralized with triethylamine (1.0 equivalent neutralization), and water was added to obtain a dispersant (I) consisting of an aqueous solution having a heating residue of 40%.

Next, a mixture of 8.3 parts of this dispersant and 200 parts of titanium white pigment (Titanium White R-5N manufactured by Sakai Chemical Co., Ltd.) was dispersed for 0.5 hours by using a Red Devil disperser to obtain the aqueous pigment dispersion liquid (a) of the present invention. ) Got.

Similarly, the pigments were dispersed according to the formulations shown in Table 1 below to obtain the aqueous pigment dispersions (b) to (d) of the present invention. The pigments other than titanium white were dispersed for 1 hour.

The properties of the resulting aqueous pigment dispersion are summarized in Table 1 below.
Shown in

Next, 10 parts of the aqueous pigment dispersion (a) and a water-dispersible alkyd resin (linseed oil fatty acid / pentaerythritol / benzoic acid / isophthalic acid / maleic anhydride = 903/705/1140/6
A water-based paint by thoroughly mixing a mixture consisting of 23.4 parts, which is obtained by neutralizing an alkyd resin having an oil length of 30 and an acid value of 16 from 1.0 / 45 (parts) with 1.0 equivalent of triethylamine. (1) was prepared.

Similarly, a mixture of the pigment dispersion and the aqueous resin shown in Table 2 below is thoroughly mixed to prepare an aqueous paint (2) to (6).
I got The coating performances of the obtained water-based paints are summarized in Table 2 below.

Example 2 280 parts of n-butyl cellosolve was placed in a reaction vessel and heated to 120 ° C. Next, the mixture in the proportions shown below was added dropwise to this solution over about 2 hours. The reaction was carried out under nitrogen injection.

Fatty acid-modified acrylic monomer (A-2) 75 parts Macromonomer (B-2) 250 parts N-vinylpyrrolidone 39 parts Acrylic acid 11 parts Azobisdimethylvaleronitrile 18 parts Reaction solution kept at 120 ° C While stirring, the above mixture was added dropwise. After 1 hour from the end of the dropping, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and after 2 hours, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and then the reaction was carried out for 2 hours while maintaining the temperature at 120 ° C. It was After completion of the reaction, unreacted monomer and n-butyl cellosolve were distilled under reduced pressure, and the heating residue was 70.3%, resin acid value was 36.4,
A copolymer solution of Gardner viscosity (40% n-butyl cellosolve solution) P was obtained. Furthermore, this copolymer was neutralized with triethylamine (1.0 equivalent neutralization), and water was added to obtain a dispersant (II) consisting of an aqueous solution having a heating residue of 40%.

Next, the obtained dispersant (II) was used to disperse the pigments shown in Table 1 below in the same manner as in Example 1 to obtain an aqueous pigment dispersion liquid (e) of the present invention.

Further, the pigment dispersion (e) and an aqueous resin shown in Table 2 below were thoroughly mixed to prepare an aqueous paint (7).

The properties of the pigment dispersion liquid (e) and the coating film performance of the water-based paint (7) are shown in Tables 1 and 2 below, respectively.

Example 3 Unsaturated monomer (A-3) 150 parts Macromonomer (B-3) 170 parts Acrylic acid 15 parts A monomer mixture was polymerized according to the method described in Example 1. A copolymer solution having a heating residue of 70.5%, a resin acid value of 45.7, and a Gardner viscosity (40% n-butyl cellosolve solution) S was obtained. This was neutralized with triethylamine (1.0 equivalent neutralization) to obtain a dispersant (III) consisting of an aqueous solution having a heating residue of 40%.

Next, the obtained dispersant (III) was used to disperse the pigments shown in Table 1 below in the same manner as in Example 1 to obtain an aqueous pigment dispersion liquid (f) of the present invention.

Further, the pigment dispersion liquid (f) and an aqueous resin shown in Table 2 below were sufficiently mixed to prepare an aqueous coating material (8).

The properties of the pigment dispersion liquid (f) and the coating film performance of the water-based paint (8) are shown in Tables 1 and 2 below, respectively.

Example 4 The polymerization reaction was performed under the same conditions as in Example 3 except that the same amount of stearyl methacrylate was used instead of the unsaturated monomer (A-3) in Example 3, and the heating residue was 71.0%.
A copolymer solution having a resin acid value of 33.0 and a Gardner viscosity (40% n-butyl cellosolve solution) L was obtained. Next, this was neutralized with triethylamine (1.0 equivalent neutralization) to obtain a dispersant (IV) consisting of an aqueous solution having a heating residue of 40%.

Next, the obtained dispersant (IV) was used to disperse the pigments shown in Table 1 below in the same manner as in Example 1 to obtain an aqueous pigment dispersion liquid (g) of the present invention.

Further, this pigment dispersion liquid (g) and an aqueous resin shown in Table 2 below were thoroughly mixed to prepare an aqueous paint (9).

The properties of the above pigment dispersion (g) and the coating film performance of the water-based paint (9) are shown in Tables 1 and 2 below, respectively.

Example 5 The polymerization reaction was performed under the same conditions as in Example 1 except that the same amount of macromonomer (B-2) was used instead of macromonomer (B-1) in Example 1, and the heating residue was 71.0.
%, Resin acid value 35.6, and Gardner viscosity (40% n-butyl cellosolve solution) N, a copolymer solution was obtained. Next, neutralize with triethylamine (1.0 equivalent neutralization), heat residue 40%
A dispersant (V) consisting of the above aqueous solution was obtained.

Next, the obtained dispersant (V) was used to disperse the pigments shown in Table 1 below in the same manner as in Example 1 to obtain an aqueous pigment dispersion liquid (h) of the present invention.

Further, the pigment dispersion liquid (h) and an aqueous resin shown in Table 2 below were sufficiently mixed to prepare an aqueous paint (10).

The properties of the pigment dispersion liquid (h) and the coating film performance of the water-based paint (10) are shown in Tables 1 and 2 below, respectively.

Comparative Example 1 Safflower oil fatty acid (236 parts), glycidyl methacrylate (119 parts), hydroquinone (0.4 parts), and tetraethylammonium (0.2 parts) were placed in a reaction vessel and heated to 140-150.
The reaction was carried out at a temperature of ° C for 4 hours to obtain a fatty acid-modified monomer. Next, instead of the macromonomer (B-1) of Example 1, N-vinyl-2-pyrrolidone was used in the same amount as the solid content to carry out the polymerization reaction, and the heating residue was 70.1% and the resin acid value was 35.
2, Gardner viscosity (40% n-butyl cellosolve solution)
A copolymer solution of N was obtained. Next, it was neutralized with triethylamine (1.0 equivalent neutralization) to obtain a dispersant (VI) consisting of an aqueous solution having a heating residue of 40%.

Next, the pigment shown in Table 1 below was dispersed by using the obtained dispersant (VI) in the same manner as in Example 1 to obtain an aqueous pigment dispersion (i).

Further, the pigment dispersion liquid (i) and an aqueous resin shown in Table 2 below were thoroughly mixed to prepare an aqueous paint (11). The properties of the pigment dispersion liquid (I) and the coating film performance of the water-based paint (11) are shown in Tables 1 and 2 below.

* 1 Titanium white R-5N: Sakai Chemical Co., Ltd. titanium oxide Carbon MA: Mitsubishi Kasei carbon black Mapico Yellow XLO: Titanium Industry Co., Ltd. yellow pigment * 2 Measured by ASTM D1201-64 * 3 Measured by B-type viscometer * 4 The acid value of the water-dispersed alkyd resin used in Example 1 was
Emulsion (solid content 40%) obtained by polymerizing 70 parts of n-butyl acrylate with 30 parts of neutralized resin of 60 as an emulsion stabilizer * 5 Dodecylbenzene sodium salt as an emulsion stabilizer and styrene / Emulsion (solid content 50%) obtained by polymerizing a monomer mixture consisting of methyl methacrylate / n-butyl methacrylate = 35/15/50 [Film coating performance test] Aqueous dryers (1) to (11) with an aqueous dryer ( Product name “Dykunate” manufactured by Dainippon Ink and Co., Ltd., cobalt metal content 3
%) Was added at a ratio of 1 part to 100 parts of resin solid content and coated on a mild steel plate. After drying at 20 ° C. and a relative humidity of 75% for 3 days, it was subjected to a test.

Adhesiveness of goggles: 100 pieces of goggles having a width of 1 mm were made, and cellophane adhesive tape was adhered on them to peel off them vigorously for testing.

Water resistance: It was immersed in tap water at 20 ° C. for 2 days and the state of the coated surface was examined with the naked eye.

Claims (1)

[Claims] 1. An aqueous pigment dispersion liquid comprising a pigment, a dispersant and an aqueous medium, wherein the dispersant comprises (A) a modified vinyl unsaturated monomer having a C ₈ or more fatty acid residue at the molecular end. 90 parts by weight (B) Nitrogen-containing macromonomer having at least one vinyl-polymerizable functional group selected from acryloyloxy, methacryloyloxy, allyloxy and aromatic vinyl at one end 2 to 90 parts by weight (C) α, β- 1 to 30 parts by weight of ethylenically unsaturated carboxylic acid (D) Copolymer obtained by copolymerizing 0 to 91 parts by weight of α, β-ethylenically unsaturated monomer other than the above (A) to (C) An aqueous pigment dispersion, which is a combined aqueous product.