JP2001323203A - Method for adjusting concentration of aqueous pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for adjusting the concentration of an aqueous pigment dispersion able to adjust the concentration of the aqueous pigment dispersion by dilution, free from the troubles of the sedimentation and aggregation of the pigment in the aqueous pigment dispersion after dilution, and able to make the dispersion excellent in storage stability, color hue stability with the laps of time, and the like. SOLUTION: The concentration of an aqueous pigment dispersion is adjusted with a diluting agent comprising (A) an inorganic powdery body, (B) a dispersant, (C) an aqueous solvent and (D) a water-soluble thickener, whose construction ratio is 2-70 wt.%, 1-10 wt.%, 20-97 wt.% and 0-3 wt.% for the components A, B, C and D, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for adjusting the concentration of an aqueous pigment dispersion.

[0002]

2. Description of the Related Art In recent years, there has been an increasing shift from solvent-based paints to water-based paints in consideration of the environment and the human body. In addition, the toning of paints is becoming smaller due to diversification of colors, remodeling of detached houses, increasing demands for quick delivery, and the like. Conventionally, the toning of water-based paint is
It is carried out by mixing an aqueous pigment dispersion of red, blue, yellow, white, black or the like into an aqueous paint. However, since the scale of small-toned tones is small, if the coloring power of the aqueous pigment dispersion is too strong, the hue tends to change with a small amount of addition, and the toning accuracy is reduced. For this reason,
When performing small-toning, a method is used in which an aqueous pigment dispersion is diluted with water, a thickener-containing aqueous solution, or the like in advance, and used in a form in which tinting power is suppressed. On the other hand, when an aqueous pigment dispersion is produced, a process using a disperser such as an attritor or a ball mill is required, but such a dispersion process usually requires several hours or more. For this reason, the pigment concentration tends to fluctuate from production lot to production lot due to volatilization of some components. Therefore, the pigment concentration is corrected by appropriately diluting it with water or the like after the dispersion step.

However, when the pigment dispersion is diluted with water or the like as described above, problems such as sedimentation and aggregation of the pigment occur over time and a change in coloring power are likely to occur, and sufficient It is difficult to ensure stability.

[0004]

Accordingly, an object of the present invention is to control the concentration of an aqueous pigment dispersion by dilution, and the aqueous pigment dispersion after dilution does not cause sedimentation or aggregation of the pigment.
An object of the present invention is to provide a method for adjusting the concentration of an aqueous pigment dispersion which can provide excellent storage stability, color stability over time, and the like.

[0005]

Means for Solving the Problems In order to solve these problems, the present inventors have conducted intensive studies, and as a result, have found that inorganic powders, dispersants, aqueous media and, if necessary, water-soluble thickeners are used. The inventor found that the contained diluent was effective, and completed the present invention.

That is, the present invention provides: The aqueous pigment dispersion contains (A) an inorganic powder, (B) a dispersant, (C) an aqueous medium, and (D) a water-soluble thickener. % By weight, (B)
Component 1 to 10% by weight, (C) Component 20 to 97% by weight,
(D) A method for adjusting the concentration of an aqueous pigment dispersion, wherein the concentration is adjusted by diluting with a diluent that is 0 to 3% by weight of the component. 2. The molecular weight of the component (B) in the diluent is 1000-2.
00000 3. The method for adjusting the concentration of an aqueous pigment dispersion described in 1. above. 3. The component (B) in the diluent is an alkylene oxide-containing anionic dispersant. Or 2. 3. The method for adjusting the concentration of an aqueous pigment dispersion described in 1. above. 4. The average particle diameter of the component (A) in the diluent is 0.03 to
5 μm ~ 3. The method for adjusting the concentration of an aqueous pigment dispersion according to any one of the above. Is provided. 5.1. ~ 4. An aqueous pigment dispersion whose concentration has been adjusted by any one of the above methods.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail along with its embodiments.

[Diluent] First, the diluent used in the present invention contains (A) an inorganic powder as an essential component. (A)
Although the type of the component is not particularly limited, barium sulfate, silica, calcium carbonate and the like can be suitably used.

The ratio of the component (A) in the diluent is 2 to 70% by weight. When the proportion of the component (A) is less than 2% by weight, the storage stability and hue stability over time when the aqueous pigment dispersion is diluted are reduced. When the proportion is more than 70% by weight, the flowability of the diluent itself is reduced. May not be secured.

The average particle size of the component (A) is 0.03 to 5 μm.
m, more preferably 0.05 to 1 μm.
By using such an average particle size, the storage stability of the aqueous pigment dispersion after dilution, hue stability over time, and the like can be further improved, and the effect on the gloss of the paint can be suppressed. it can.

As the dispersant (B), a dispersant capable of dispersing the component (A) can be used. Examples thereof include polycarboxylates such as polyacrylates, sulfates such as alkyl sulfates and alkyl ester sulfates, and the like. Sulfonates such as alkyl sulfonates and sulfosuccinates; and phosphate esters such as alkyl phosphates.

The component (B) has a number average molecular weight of 1,000 to 2,
00000 is preferred. With such a molecular weight, the storage stability, the hue stability over time, and the like of the aqueous pigment dispersion after dilution can be improved. When the molecular weight is larger than 200,000, the viscosity of the diluent itself becomes high, so that handling may be inconvenient.

In the present invention, it is particularly preferable to use an alkylene oxide-containing anionic dispersant as the component (B). This makes it possible to further enhance the physical properties of the diluted aqueous pigment dispersion. Examples of the group imparting anionic property include a carboxylate, a sulfate, a sulfonate, and a phosphate. Examples of the alkylene oxide include methylene oxide, ethylene oxide, propylene oxide, butylene oxide and the like. Of these, ethylene oxide and / or
Alternatively, propylene oxide is preferably used. The number average molecular weight of the alkylene oxide chain is 40 to 150.
00 is desirable. If it is larger than 15,000, the water resistance and weather resistance of the final coating film may be undesirably reduced. The acid value of the alkylene oxide-containing anionic dispersant is determined by the dispersibility of the component (A),
Considering the water resistance and weather resistance of the coating film, 2-100 KO
Desirably, it is Hmg / g.

The ratio of the component (B) in the diluent is 1 to 10% by weight. If the amount is less than 1% by weight, the storage stability of the diluent cannot be ensured, and the effect of improving the temporal hue stability cannot be obtained even when mixed with the aqueous pigment dispersion.
If it is more than 10% by weight, it will adversely affect the water resistance and weather resistance of the final coating film.

Water is mainly used as the aqueous medium, but it is also possible to use a water-soluble organic solvent as a medium other than water. Such water-soluble organic solvents include, for example, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol, propylene glycol, propylene glycol Monomethyl ether, 1-3
Butanediol, N-methylpyrrolidone and the like.

The aqueous medium as the component (C) is composed of 2
It is contained in a ratio of 0 to 97% by weight. If it is less than 20% by weight, the fluidity of the diluent cannot be secured. If it is more than 97% by weight, the storage stability of the diluent will be reduced, and even if it is mixed with the aqueous pigment dispersion, the effect of improving the hue stability over time and the like cannot be obtained.

(D) The water-soluble thickener includes, for example,
Hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose,
Polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether and the like can be used.

The component (D) is contained in the diluent at a ratio of 0 to 3% by weight. If the content is more than 3% by weight, the fluidity of the diluent itself will decrease, and the water resistance and weather resistance of the final coating film will be adversely affected.

In the diluent of the present invention, in addition to the above components, an antifoaming agent, a preservative, a fungicide and the like can be added.

The method for producing the diluent is not particularly limited, but the component (A) is charged into a mixture of the components (B) and (C), and the mixture is dispersed by a disperser such as an attritor, a ball mill, a sand mill, or a paint shaker. Can be suitably used. In this case, the component (D) may be appropriately added before or after the addition of the component (A).

[Method of Adjusting Concentration] In the present invention, the concentration of an existing aqueous pigment dispersion is adjusted using the above-mentioned diluent.
The aqueous pigment dispersion to which the present invention can be applied is not particularly limited, but usually is a dispersion in which a color pigment is dispersed at a concentration of 15 to 75% by weight. As the coloring pigment, for example, inorganic pigments such as titanium oxide, carbon black, graphite, red iron oxide, yellow iron oxide, ocher, chrome green, ultramarine, etc.,
Insolubles such as naphthols (permanent red, permanent carmine, brilliant carmine), pyrazolones (pyrazolone orange, pyrazolone red, benzimidazolone), monoazos (fast yellow, benzimidazolone yellow, disazo (diarilide yellow)) Soluble azo pigments such as azo pigments, Watching Red, Permanent Red and Lake Red, condensed azo pigments, phthalocyanine green, chlorinated phthalocyanine green, brominated phthalocyanine green, phthalocyanine blue, copper phthalocyanine blue and other phthalocyanine pigments, anthraquinones (anthraquinones) Red, dianthraquinone red, anthanthrone red, anthanthrone orange), perylene (perylene red, perylene scarlet, pe Ren Maroon), perinone,
Condensed polyquinacridone (quinacridone red, quinacridone violet, quinacridone magenta, quinacridone maroon, quinacridone scarlet), diketopyrrolopyrrole (diketopyrrolopyrrole), isoindolinone, isoindoline, quinophthalone (quinophthalone yellow), etc. And organic pigments such as ring pigments.

As a mixing method for adjusting the concentration of the aqueous pigment dispersion, it is sufficient to add the diluent of the present invention to the aqueous pigment dispersant and stir the mixture uniformly using a stirrer. The mixing amount may be appropriately set so that the aqueous pigment dispersion has a desired pigment concentration. Usually, up to about 1000 parts by weight can be mixed with 100 parts by weight of the aqueous pigment dispersion.

In the present invention, the concentration of the aqueous pigment dispersion is adjusted by using an inorganic powder, a dispersant, an aqueous medium and, if necessary, a diluent containing a water-soluble thickener. The storage stability and the hue stability over time of the aqueous pigment dispersion can be sufficiently ensured. Although the mechanism of action is not clear, the inorganic powder with the dispersant adsorbed on the surface is
It is presumed that by floating between the color pigment particles, aggregation and sedimentation of the color pigment are prevented, and this greatly contributes to stabilization. In particular, when a high-molecular-weight dispersant or a dispersant containing an alkylene oxide chain is used, it is considered that the steric hindrance effect can further enhance the stability.

[0024]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

[0025]

[Table 1]

[0026]

[Table 2]

(Production of Aqueous Pigment Dispersion A)
30% by weight of phthalocyanine green, which is a green pigment,
30% by weight of an ethylene oxide adduct, 40% by weight of a water-soluble thickener and deionized water were mixed and then added. Glass beads (particle diameter: about 1 mm) were added, and the mixture was dispersed for 120 minutes with a paint shaker to disperse an aqueous pigment. Liquid A was obtained.

[Example 1] (Preparation of diluent) Using the raw materials shown in Table 1, a diluent "P-1" was prepared at the ratio shown in Table 2. In preparing the diluent, a paint shaker was used as a disperser,
Dispersion was performed for minutes. (Concentration adjustment) 50 parts by weight of the prepared diluent "P-1" was added to 100 parts by weight of the aqueous pigment dispersion A, and the mixture was stirred for 3 minutes with a stirrer to homogenize. As a result, an aqueous pigment dispersion “Q-1” having a pigment concentration adjusted to 20% by weight was obtained. (Test) One part by weight of the dispersion “Q-1” was added to 99 parts by weight of a white water-based paint “PLEASE COAT” (manufactured by SK Chemical Co., Ltd.) to prepare a paint. This paint is applied on a standard white paper with a wet film thickness of 0.25 mm and dried,
Coated paper 1 was prepared. Next, the dispersion “Q-1” was placed at 20 ° C.
After standing at 50 ° C. for 4 weeks, the appearance of the dispersion was confirmed.
(Used product left at 20 ° C.) and coated paper 3 (Used product left at 50 ° C.) were prepared. The hue of each coated paper created is measured with a colorimeter TC-
1800 (manufactured by Tokyo Denshoku Co., Ltd.), and the color difference between the coated papers 2 and 3 with respect to the coated paper 1 was obtained.

Example 2 A diluent "P-1" was added to 67 parts by weight of 100 parts by weight of a green aqueous pigment dispersion B (LIOFAST color; manufactured by Toyo Ink Mfg. Co., Ltd., pigment concentration: 33.5% by weight). 0.5 parts by weight and a pigment concentration of 20
By weight, an aqueous pigment dispersion "Q-2" was obtained. Otherwise, the test was performed in the same manner as in Example 1.

Example 3 An aqueous pigment dispersion in which the pigment concentration of the aqueous pigment dispersion A was adjusted to 20% by weight using "P-2" prepared at the compounding ratio shown in Table 2 as a diluent "Q-3" was obtained. Otherwise, the test was performed in the same manner as in Example 1.

Example 4 Aqueous pigment dispersion prepared by adjusting the pigment concentration of aqueous pigment dispersion A to 20% by weight using "P-3" prepared at the compounding ratio shown in Table 2 as a diluent "Q-4" was obtained. Otherwise, the test was performed in the same manner as in Example 1.

Example 5 Aqueous pigment dispersion prepared by adjusting the pigment concentration of aqueous pigment dispersion A to 20% by weight using "P-4" produced at the compounding ratio shown in Table 2 as a diluent "Q-5" was obtained. Otherwise, the test was performed in the same manner as in Example 1.

Example 6 An aqueous pigment dispersion in which the pigment concentration of the aqueous pigment dispersion A was adjusted to 20% by weight using "P-5" prepared at the compounding ratio shown in Table 2 as a diluent "Q-6" was obtained. Otherwise, the test was performed in the same manner as in Example 1.

Comparative Example 1 To 100 parts by weight of the aqueous pigment dispersion A, 50 parts by weight of water was added, followed by stirring for 3 minutes to homogenize. Thus, an aqueous pigment dispersion “Q-7” in which the pigment concentration was adjusted to 20% by weight was obtained. The obtained dispersion was tested in the same manner as in Example 1.

Comparative Example 2 To 100 parts by weight of the aqueous pigment dispersion A, 50 parts by weight of a 3% by weight aqueous solution of hydroxyethylcellulose was added, followed by stirring for 3 minutes to homogenize.
Thus, an aqueous pigment dispersion “Q-8” in which the pigment concentration was adjusted to 20% by weight was obtained. The obtained dispersion was tested in the same manner as in Example 1.

(Results) Table 3 shows the test results. The appearance was evaluated as follows: ○: No abnormality, Δ: Separation / settling, ×:
Significant separation and sedimentation occurred. The evaluation of color difference is ◎: △
E = 0 to 0.5, △: ΔE = 0.5 to 1.0, Δ: ΔE
= 1.0 to 2.0, ×: ΔE = 2.0 or more.

[0037]

[Table 3]

Example 1 using the diluent specified in the present invention
In any of Nos. To 6, there was no abnormality in appearance and color difference after storage, and good results were obtained. In particular, Examples 1 to 4, which are preferred embodiments of the present invention, exhibited excellent storage stability and color stability over time. On the other hand, in Comparative Example 1, the pigment precipitated at both 20 ° C. and 50 ° C., the color difference was large, and the stability was poor. In Comparative Example 2, sedimentation of the pigment was observed, and the result was particularly poor stability at 50 ° C.

[0039]

According to the present invention, the concentration of the aqueous pigment dispersion can be adjusted by dilution, and the aqueous pigment dispersion after dilution does not cause separation, sedimentation or aggregation, storage stability, color stability over time, etc. Excellent.

Claims (5)

[Claims] 1. An aqueous pigment dispersion comprising: (A) an inorganic powder,
It contains (B) a dispersant, (C) an aqueous medium, and (D) a water-soluble thickener, and its composition ratio is (A) 2 to 70% by weight, (B) 1 to 10% by weight, C) Components 20 to 97
A method for adjusting the concentration of an aqueous pigment dispersion, wherein the concentration is adjusted by diluting with a diluent that is 0 to 3% by weight of a component (D). 2. The molecular weight of component (B) in the diluent is 10
The method for adjusting the concentration of an aqueous pigment dispersion according to claim 1, wherein the concentration is from 00 to 200,000. 3. The method for adjusting the concentration of an aqueous pigment dispersion according to claim 1, wherein the component (B) in the diluent is an alkylene oxide-containing anionic dispersant. 4. The method for adjusting the concentration of an aqueous pigment dispersion according to claim 1, wherein the average particle size of the component (A) in the diluent is 0.03 to 5 μm. 5. An aqueous pigment dispersion having a concentration adjusted by the method according to claim 1.