WO2009119143A1 - Aluminum pigment composition for water-base coating materials and water-base coating amterials - Google Patents

Abstract

An aluminum pigment composition for water-base coating materials which comprises an aluminum pigment, a rheology modifier, and an organic solvent, characterized in that the organic solvent has a solubility parameter of 6 to 12 and exhibits a solubility of 30mass% or below in water at 20°C and that when the rheology modifier is added to a resin emulsion and the obtained mixture is subjected to viscosity determination with a Brookfield type viscometer, both viscosity (B60) at a number of revolutions of 60 and viscosity (B6) at a number of revolutions of 6 fall within the range of 0.3 to 30Pa·s and the B6/B60 ratio, namely, thixotropic index is 1 to 60.

Description

Aluminum pigment composition for water-based paint and water-based paint

The present invention relates to an aluminum pigment composition for water-based paints that is excellent in orientation and can improve metallic unevenness to the same extent as that of solvent-based paints when blended with water-based paints, and water-based paints containing the same.

Conventionally, solvent-based paints using organic solvents have been the mainstream for metallic paints. However, in order to cope with environmental problems such as VOC regulations in recent years, a shift to water-based paints using water as a main solvent is progressing.

Compared with solvent-based metallic paints, aqueous metallic paints (also simply referred to as “aqueous paints” in the present invention) differ in various properties such as dispersibility and sedimentation of aluminum pigments in the paints. It is well known that this difference in paint type (that is, whether it is solvent-based or water-based) affects the orientation of the aluminum pigment when it is formed into a coating film. In addition, it has been found that the orientation of the aluminum pigment is largely influenced by the coating machine as well as the characteristics of the paint. Particularly in recent years, in the application of water-based metallic paints, metallic bell coating that prioritizes the coating efficiency over design properties has become the mainstream, so after coating formation so-called metallic unevenness (in metallic unevenness, blow unevenness, flow unevenness, There is unevenness of returning to the clear coating film, and the aluminum pigment moves in the coating film, which means that it appears uneven when aligned unevenly, aggregated, or unevenly distributed). It is known that flow unevenness and return unevenness are likely to occur when the viscosity of the coating is too low, thickly applied at once, or repeated many times in a short time.

In this metallic bell coating, the atomization efficiency is increased by giving the coating a high rotation shear (shearing force) during discharge. For this reason, the atomized particles become very fine, and the collision speed with respect to the coating plate becomes slow, so that the aluminum pigment is hardly collided. Collision orientation is a behavior in which paint particles (aluminum pigment) collide with a surface to be coated during spraying and are oriented so as to be parallel to the surface to be coated by deformation and flow during coating. For this reason, the orientation of the aluminum pigment in the coating film tends to be disturbed as compared with the conventional air spray in which the ejection amount is reduced and collided.

Various additives have been added to the water-based metallic paint for the purpose of controlling the disorder of the orientation of the aluminum pigment. However, it is difficult to control the orientation, which is almost the same as that of the solvent-based metallic paint. Color and appearance cannot be achieved with water-based paints.

In order to solve this metallic unevenness, there is an approach using an aluminum pigment, but JP 2005-240013 A (Patent Document 1) discloses that a specific amount of resin is controlled on the surface of the flaky aluminum powder. By coating, resin-coated aluminum pigment particles exhibit extremely excellent orientation in metallic coatings for automobile bodies, bumpers, parts, and repairs. Therefore, coating with high light intensity and low particle feeling is required. It is disclosed that a membrane can be provided.

However, this treatment method requires a step of coating a resin, which is troublesome and, furthermore, because the resin is coated, it is not possible to obtain a coating film that reflects the reflectance of the original aluminum pigment. .
JP 2005-240013 A

Currently, it is possible to improve the chemical stability by forming various treatments and coatings on the surface of aluminum pigments in water-based paints. It is not possible to improve to the same extent as in the above, and the occurrence of metallic unevenness cannot be suppressed.

The above-mentioned aluminum pigments that have been subjected to various surface treatments are blended into water-based paints that are pasted with a hydrophilic solvent in consideration of dispersibility in water-based paints. This idea is based on the fact that, in the case of solvent-based paints, dispersibility and color tone are improved by pasting aluminum pigments with a solvent having a high affinity with paint solvents. Even in the case of a water-based paint, dispersibility in the water-based paint can be improved by pasting the aluminum pigment with a hydrophilic solvent.

However, even if the dispersibility in the aqueous paint is improved in this way, the color tone, particularly the orientation in the coating film, cannot be improved to the same extent as in the solvent system. This is because the orientation of the aluminum pigment is disturbed at the time of application in the coating process and at the time of subsequent coating film formation (shrinkage of the wet coating film; shrinkage orientation). , Sagging of the paint occurs during application. It is presumed that these improve the dispersibility of the aluminum pigment in the water-based paint, particularly leading to a decrease in thixotropy after coating. Due to these factors, the orientation of the aluminum pigment is lowered in the water-based paint, and metallic unevenness tends to occur.

The present invention has been made in order to solve the above-described problems, and the object of the present invention is to improve the thixotropy of an aqueous paint and improve the orientation of an aluminum pigment after coating. Accordingly, an object of the present invention is to provide an aluminum pigment composition for water-based paints that can improve metallic unevenness and thus achieve the same color tone and appearance as those of organic solvent-based paints.

In order to improve the orientation of the aluminum pigment in the water-based paint, the present inventor paid attention to the behavior of the aluminum pigment in the water-based paint, particularly the behavior of the aluminum pigment at the time of coating or forming a coating film. Therefore, by adding and mixing the rheology control agent to the aluminum pigment, the rheology control agent is positively adsorbed on the surface of the aluminum pigment, thereby increasing the viscosity of the paint after application of the aqueous paint. It has been found that the sagging does not occur and the orientation of the aluminum pigment is not disturbed when the coating film is formed, and the metallic unevenness can be improved.

In addition to the above, the present inventor paid attention to the effect of the organic solvent that disperses the aluminum pigment on the water-based paint. As a result, the orientation of the aluminum pigment at the time of coating or coating formation in the case of pasting with a hydrophilic solvent. The disorder of the property is that the hydrophilic solvent is attributed, and the orientation of the aluminum pigment is improved by composing with a solvent having a low affinity with water, which is the main solvent in the aqueous paint, We found that metallic unevenness can be improved.

That is, the aluminum pigment composition for water-based paints of the present invention contains at least an aluminum pigment, a rheology control agent and an organic solvent, and the organic solvent has a solubility parameter (SP value) of 6 to 12, and The solubility in water at 20 ° C. is 30% by mass or less, and the rheology control agent is added with 2.5 parts by mass with respect to 100 parts by mass of the solid content in the resin emulsion, and a B-type viscometer is used. When the viscosity is measured, the viscosity B ₆₀ at 60 rotations and the viscosity B ₆ at 6 rotations are both in the range of 0.3 to 30 Pa · s, and the ratio B of B ₆ to B _{60 A} thixotropic index (TI value) of ₆ / B ₆₀ indicates 1 to 60.

The rheology control agent is preferably contained in an amount of 0.01 to 50 parts by mass with respect to 100 parts by mass of the aluminum pigment.

The rheology control agent is one or more compounds selected from the group consisting of urethane, acrylic, polyolefin, amide, anionic activator, nonionic activator, polycarboxylic acid, cellulose, and urea. It is preferable.

The organic solvent is preferably contained in an amount of 10 to 1000 parts by mass with respect to 100 parts by mass of the aluminum pigment.

Thus, the organic solvent having a specific SP value and having a solubility in water of not more than a specific amount is contained in the aluminum pigment composition, so that the thixotropy of the water-based paint can be obtained by a synergistic effect with the rheology control agent. Can keep sex. This is because when an aqueous paint containing an aluminum pigment is applied, an aluminum pigment that is not well-suited to water is wrapped in an oil component, and a region different from that of a resin layer having a high affinity for water or water is present. In order to form, the range which an aluminum pigment flows in a coating film is narrowed.

Also, the shrinkage of the volume of the coating film during baking creates an interface between the oily component and the aqueous component, and the presence of the aluminum pigment at this interface ensures that the orientation is not disturbed by the flow of Benard cells caused by the volatile components, and in parallel. It is thought that it becomes easy to arrange.

In addition, when combined with a rheology control agent as described above, further thixotropy is expressed, and the effect of stopping aluminum pigments in a state of being aligned in parallel in the coating film is manifested. It shows the effect.

Furthermore, the aqueous paint of the present invention contains the above-described aluminum pigment composition for aqueous paint.

According to the present invention, by introducing a rheology control agent into an aluminum pigment composition for water-based paints blended in water-based paints and improving thixotropy of the water-based paints, it is possible to improve orientation and metallic unevenness. Is. Furthermore, since an organic solvent having a specific SP value (a solvent having a low affinity with water as the main solvent in the aqueous paint) can be used in combination, the thixotropy of the aqueous paint can be improved. By improving the orientation of the aluminum pigment after deposition, the metallic unevenness is improved, so that the same color tone and appearance as those of the organic solvent-based paint can be achieved.

The present invention will be described in detail below, but the present invention is not limited thereto.
<Aluminum pigment composition for water-based paint>
The aluminum pigment composition for water-based paints of the present invention is a composition prepared for the purpose of blending in water-based paints, and contains at least an aluminum pigment, a rheology control agent and an organic solvent. As long as these three components are included, any other component can be included within the range showing the effects of the present invention.

By including a rheology control agent in the aluminum pigment composition for water-based paints, thixotropy is expressed in the water-based paint, and the effect of stopping the aluminum pigments in a parallel arrangement in the paint film after the paint is applied is exhibited. The effect of improving the orientation and metallic unevenness of the aluminum pigment can be obtained.

There has been a conventional idea to control rheology in paints by adding various additives to water-based paints. However, as in the present invention, focusing on aluminum pigments themselves, the orientation of aluminum pigments is controlled by rheology. The technical idea of improving by this is a completely new technical idea that did not exist before.

<Aluminum pigment>
As the aluminum pigment used in the aluminum pigment composition for water-based paints of the present invention, aluminum particles and those based thereon are used.

Here, the aluminum particles used in the present invention may be composed only of aluminum or may be composed of an aluminum alloy. When it consists only of aluminum, the purity of aluminum is not specifically limited, Even if an impurity is contained, it does not deviate from the scope of the present invention.

In addition, the shape of the aluminum particles used in the present invention may include various shapes such as a granular shape, a plate shape, a lump shape, and a flake shape (scale-like shape), but in order to give an excellent metallic feeling and luminance to the coating film. The flake shape is preferred.

The average particle size of the aluminum particles used in the present invention is not particularly limited, but is preferably 2 μm or more, more preferably 5 μm or more. The average particle size is preferably 40 μm or less, more preferably 30 μm or less. When the average particle size is less than 2 μm, handling in the production process is difficult, and the particles tend to aggregate. When the average particle size exceeds 40 μm, the coating surface becomes rough when used as a paint, which is preferable. Designability may not be realized.

Furthermore, the aluminum particles used in the present invention preferably have a shape factor (referred to as “aspect ratio” in the present invention) obtained by dividing the average particle size by the average thickness of 5 or more, particularly preferably 15 or more. The aspect ratio is preferably 1000 or less, and particularly preferably 500 or less. When the aspect ratio is less than 5, there is a tendency that the glitter feeling is insufficient, and when the aspect ratio exceeds 1000, the mechanical strength of the aluminum particles is lowered and the color tone may become unstable.

Here, the average particle size of the aluminum particles used in the present invention is calculated by calculating the volume average based on the particle size distribution measured by a known particle size distribution measurement method such as laser diffraction method, micromesh sieve method, Coulter counter method, etc. Desired. The average thickness is calculated from the hiding power and density of the aluminum pigment.

And the grinding | pulverization adjuvant may adhere to the surface of the aluminum particle used for this invention. As a grinding aid, an unsaturated fatty acid is usually used. Examples of the unsaturated fatty acid used here include oleic acid, linoleic acid, linolenic acid, ricinoleic acid, elaidic acid, zomarinic acid, gadoleic acid, and erucic acid.

In addition, as the aluminum pigment of the present invention, those having a water-resistant film formed on the surface of aluminum particles as a base material as described later can also be used. In the present invention, the water-resistant film formed on the surface of the aluminum particles may be expressed as “the water-resistant film is formed on the surface of the aluminum pigment”. The term “pigment” and “aluminum particles” are not clearly distinguished.

<Rheology control agent>
The rheology control agent generally means an additive that acts to control the rheology of the paint by adding it to the paint. Various names such as thixotropic agents, anti-settling agents, sagging inhibitors, thickeners, etc. In the present invention, among such rheology control agents, a B-type viscometer is particularly added to a resin emulsion (added at a ratio of 2.5 parts by mass with respect to 100 parts by mass of the solid content of the resin emulsion). When the viscosity is measured using the viscosity, the viscosity B ₆₀ at 60 revolutions and the viscosity B ₆ at 6 revolutions are both in the range of 0.3 to 30 Pa · s, and the B ₆ and the B ₆₀ A material having a characteristic that a thixotropic index (TI value) having a ratio B ₆ / B ₆₀ indicates 1 to 60 is employed. By having such characteristics, the thixotropy of the water-based paint is drastically improved. In the above definition, when the viscosity B ₆₀ or B ₆ is less than 0.3 Pa · s, or when the TI value is less than 1, there is a problem that the effect of improving the thixotropic property of the water-based paint cannot be expected, When the viscosity B ₆₀ or B ₆ exceeds 30 Pa · s, or when the TI value exceeds 60, the static viscosity of the water-based paint is too high to be re-stirred, and the fluidity at the time of coating is ensured. There is a problem that becomes difficult.

Hereinafter, an example of the composition of a resin emulsion for viscosity measurement used for evaluating whether or not the rheology control agent exhibits the above-described properties will be shown.

<Composition of resin emulsion>
JONCRYL 62J (* A) (as solid content) 21 parts by mass JONCRYL 711 (* B) (as solid content) 79 parts by mass (* A) BASF Japan: Styrene acrylic resin aqueous solution (* B) BASF Japan: acrylic resin The symbols of emulsions (* A) and (* B) indicate the company name (manufacturer) and the compound name. When the above-mentioned “JONCRYL 62J” and the above “JONCRYL 711” are mixed at a mass ratio of the former: the latter = 1: 3, the composition having the solid content ratio shown above can be obtained. The resin emulsion having such a composition is hereinafter referred to as “resin emulsion A”.

<Rheology control agent evaluation method>
Immediately after adding the rheology control agent so that the rheology control agent to be evaluated (active component thereof) is 2.5 parts by mass with respect to 100 parts by mass of the solid content of the resin emulsion A, and further stirring the dispersion at 1000 rpm for 3 minutes. The viscosity after 60 seconds is measured using a B-type viscometer (trade name “DVM-BII”, manufactured by Toki Sangyo Co., Ltd.) (using rotor No. 3), and the above viscosity B ₆ and viscosity B ₆₀ are obtained. Can do.

The chemical structure of the rheology control agent of the present invention is not particularly limited as long as it exhibits the above-mentioned properties. For example, urethane (a polymer or oligomer containing a urethane structure in the molecule), acrylic (an acrylate ester in the molecule), or the like. Or a polymer of a methacrylic acid ester, a structure comprising an oligomer), a polyolefin (eg, polyethylene, polypropylene, etc.), an amide (higher fatty acid amide, a polyamide, an oligomer, etc.), an anionic activator (sulfate ester, anionic fatty acid) , Linear alkylbenzene, higher alcohol, alpha olefin, normal paraffin, etc.), nonionic activator (nonionic fatty acid, higher alcohol, alkylphenol, etc.), polycarboxylic acid (at least 2 in the molecule) The carbo 1 type selected from the group consisting of derivatives (including derivatives having a sil group), cellulose (including various derivatives such as nitrocellulose, acetylcellulose, and cellulose ether), and urea (polymers and oligomers having a urea structure in the molecule). Alternatively, two or more compounds are used.

Here, when the rheology control agent used in the present invention is a polymer, the polymer listed above may be composed of only the main chain, and various substituents may be added to the main chain. For example, a phosphoric acid group, a carboxyl group, an amino group, a hydroxyl group and the like may be introduced. When substituents are introduced in this way, the amount of substituents introduced into the main chain is not particularly limited.

Further, the rheology control agent used in the present invention may be in a solid state or a liquid state at room temperature, but is more preferably a liquid from the viewpoint that it can be easily added in the production process. . However, even a solid state at ordinary temperature can be used by dissolving or dispersing in an appropriate solvent. Further, in order to prevent the aluminum pigment from reacting with water, the rheology control agent is particularly preferably diluted with a solvent other than water, and the rheology control agent itself is also preferably liquid.

And the addition amount of the rheology control agent used in the present invention is preferably 0.01 to 50 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the aluminum pigment. When the addition amount of the rheology control agent is less than 0.01 parts by mass, the effect of improving the color tone and unevenness can hardly be expected. When the addition amount exceeds 50 parts by mass, the thixotropy of the paint becomes too large, and it is normal. Since the viscosity during storage is too thick, it may not be possible to establish a paint. In addition, when the “aluminum pigment” is used as a reference for the blending amount as described above, when a water-resistant coating is formed on the surface of the aluminum pigment, it is based on the mass of the aluminum pigment on which such a water-resistant coating is formed. (Same below).

More specifically, the rheology control agent used in the present invention is a polycarboxylic acid-based "ASE-60" from Rohm & Hass Co., Ltd., "VISCALEX HV30" from Ciba Co., Ltd., "Chixol from Kyoeisha Chemical Co., Ltd." K-130B ”, etc., and polyurethane-based products such as“ UH750 ”and“ SDX-1014 ”from ADEKA Corporation,“ RM-12W ”and“ RM-285 ”from Rohm & Hass Corporation, ELEMENTIS ) “REOLATE FX1070” and the like, and polyamid-based ones include “Dispalon AQ-610” from Enomoto Kasei Co., Ltd., “Chixol W300” from Kyoeisha Chemical Co., Ltd. Is HEC (hydroxyethylcellulose) as the main chain, hydrophobized EC, CMC (carboxymethylcellulose) and the like are included, and examples of urea-based ones include “BYK-410”, “BYK-411”, “BYK-420”, “BYK-425”, etc. of Big Chemie Co., Ltd. Examples of the sulfate ester anionic activator include “Flonon SDR-80” manufactured by Kyoeisha Chemical Co., Ltd., and examples of polyolefin-based agents include “Flownon SA-345HF” manufactured by Kyoeisha Chemical Co., Ltd. Examples of higher fatty acid amides include “Flonon HR-4AF” manufactured by Kyoeisha Chemical Co., Ltd.

<Organic solvent>
The aluminum pigment composition for water-based paints of the present invention contains an organic solvent, the organic solvent has a solubility parameter (SP value) of 6 to 12, and has a solubility in water at 20 ° C. of 30% by mass or less. It is necessary to be. Thus, by using an organic solvent having a specific solubility parameter in combination with the above specific rheology control agent, these act synergistically, thereby improving the thixotropy of the aqueous paint and the orientation of the aluminum pigment. This is a dramatic improvement in the property and metallic unevenness.

The SP value of the organic solvent of the present invention is preferably 7 to 9, and the solubility in water is preferably 20% by mass or less, more preferably 10% by mass or less. Few organic solvents have an SP value of less than 6, and it is usually unthinkable to bring them into aqueous paint systems. On the other hand, when the SP value exceeds 12 and the solubility in water exceeds 30% by mass, the affinity for the resin in water-based paint and water is increased, which is not preferable from the viewpoint of reducing thixotropy.

As described above, an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less has limited solubility in water, and particularly has an SP value of 7 to 9. In addition, when an organic solvent having a solubility in water of 10% by mass or less is used, it is insoluble or hardly soluble in water. However, the use of an organic solvent exhibiting such properties in water-based paints defeats conventional technical common sense. It is. That is, conventionally, an organic solvent for an aluminum pigment composition for water-based paints, particularly an aluminum pigment composition for water-based paints containing an aluminum pigment subjected to a water-resistant coating treatment in order to improve the dispersibility of the aluminum pigment in the water-based paint. As for, it is usual to use a hydrophilic solvent, and the water-based paint contains an organic solvent whose solubility in water is limited and an organic solvent that is insoluble or hardly soluble in water. It was thought to have an adverse effect on physical properties. For this reason, it is conventional to include an organic solvent whose solubility in water is limited as an organic solvent constituting the aluminum pigment composition for water-based paints as in the present invention or an organic solvent that is insoluble or hardly soluble in water. Even if it is a person skilled in the art (rather, if it is a person skilled in the art), the use of an organic solvent whose solubility in water is limited or an organic solvent that is insoluble or sparingly soluble in water can be used. Such an excellent effect was never expected. The present invention has been made based on such completely new knowledge.

Here, the organic solvent used in the present invention is not particularly limited as long as the above-described conditions are satisfied. For example, hexane, heptane, octane, cyclohexane, mineral spirit, isoparaffin, normal paraffin, petroleum benzine, and the like. Aliphatic hydrocarbons, aromatic hydrocarbons such as benzene, xylene, toluene, solvent naphtha, halogenated hydrocarbons such as chlorobenzene, trichlorobenzene, perchlorethylene, trichloroethylene, n-octanol, 2-ethyl Alcohols such as hexanol and n-butanol, esters such as isobutyl acetate, butyl acetate and 2-ethylhexyl acetate, ketones such as methyl isobutyl ketone, cyclohexanone and diisobutyl ketone, and n-butoxypropanol Recall ethers can be exemplified, but these may also be used in each alone, or can be used in combination of two or more kinds. That is, it may be a single solvent or a mixed solvent in which two or more kinds are combined, but can be used as long as it satisfies the requirements of the organic solvent specified in the present invention.

Such an organic solvent is preferably contained in an amount of 10 to 1000 parts by mass with respect to 100 parts by mass of the aluminum pigment. More preferably, it is 40 to 250 parts by mass. If the amount is less than 10 parts by mass, the effect of improving the color tone and unevenness can hardly be expected. If the amount exceeds 1000 parts by mass, the aluminum pigment may not be sufficiently dispersed in the aqueous paint.

In addition, the aluminum pigment composition for water-based paints of the present invention can further contain a hydrophilic organic solvent as long as it contains the organic solvent as described above. However, the proportion of the hydrophilic organic solvent is preferably small and is preferably less than 10% by mass with respect to the organic solvent of the present invention. Examples of such hydrophilic organic solvents include ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and dipropylene. Examples include propylene glycol solvents such as glycol monomethyl ether and dipropylene glycol monoethyl ether, ethylene glycol solvents, and alcohol solvents such as isopropyl alcohol.

As described later, at the stage where a water-resistant coating is formed on the surface of the aluminum pigment, the solvent used in the coating treatment step is mainly composed of a hydrophilic organic solvent. Therefore, in order to obtain the aluminum pigment composition for water-based paints of the present invention, all or a predetermined ratio of the hydrophilic organic solvent present together with the aluminum pigment having such a water-resistant coating is changed to an SP value of 6 to 12. It is preferable to carry out solvent substitution with an organic solvent having a solubility in water at 20 ° C. of 30% by mass or less.

<Water resistant coating>
As the aluminum pigment of the present invention, one having a water-resistant film formed on the surface thereof can be used. As such a water-resistant coating, for example, a molybdic acid coating described in JP-A-06-057171 or a phosphoric acid-based coating is further formed on a molybdic acid coating described in JP-A-07-070468. Examples thereof include, but are not limited to, a silica film and / or a film formed from a silane coupling agent as described in WO 2004/096921.

Hereinafter, as such a water-resistant coating, a method of forming a molybdic acid-based coating on the surface of the aluminum pigment and a method of forming a silica coating on the surface of the aluminum pigment are shown.

<Molybdate coating>
The aluminum pigment having a molybdate coating has a molybdate coating on the surface of the aluminum pigment (aluminum particles) in an amount of 0.1 to 10% by mass in terms of Mo metal relative to aluminum. The primary treatment for forming the molybdate coating on the surface of the aluminum pigment consists of treating the aluminum pigment dispersed in a water-soluble solvent with an alkaline aqueous solution containing ammonium molybdate.

The aluminum pigment used for forming the molybdic acid-based film is desirably dispersed in advance in a hydrophilic organic solvent (hereinafter simply referred to as a water-soluble solvent) so as to be easily wetted with the treatment liquid. If the grinding medium is not compatible with the treatment liquid, it must be replaced with a water-soluble solvent in advance.

The treatment liquid is preferably prepared by dissolving ammonium molybdate in a mixed solution of water and a water-soluble solvent so as to have a concentration of several mass% or less.

Since the water-soluble solvent is naturally miscible with the aqueous phase, it is indispensable for realizing contact between the aluminum pigment and ammonium molybdate. Examples of water-soluble solvents that can be used include ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, and isopropyl alcohol.

When the aluminum pigment is reacted with the treatment liquid, it is important that the reaction is performed under alkali. Usually, the pH of the treatment liquid is 7 to 10, preferably 7.5 to 9.5, more preferably 8 to 9. If the pH is less than 7, the reaction with aluminum does not proceed slowly because of the presence of fatty acid adsorbed on the surface of the aluminum pigment (of course, the aluminum dissolves if the acid is out of the passive region). When the value exceeds 10, an abrupt reaction occurs, so that an aluminum pigment having an excellent color tone cannot be obtained.

Primary treatment is completed by removing water and unreacted substances from the reaction system. After the completion of the reaction, it is washed and filtered and then subjected to a secondary treatment. When the primary-treated aluminum pigment cake contains water, it is desirable to replace the water with the water-soluble solvent before the secondary treatment.

The molybdic acid-based film thus formed is in the range of 0.1 to 10% by mass, preferably 0.1 to 3% by mass in terms of Mo metal based on the aluminum pigment. If it is less than the lower limit, it is insufficient to suppress the generation of hydrogen gas. On the other hand, if it exceeds the upper limit, the coating becomes too thick and the color tone of the coating becomes worse.

Further, a phosphoric acid-based film of 0.05 to 1% by mass in terms of P element with respect to aluminum is formed on the molybdate film formed by the primary treatment. The secondary treatment for forming the phosphoric acid-based coating consists of treating the primary treated aluminum pigment with a solution of an inorganic or organic phosphoric acid compound.

As the phosphoric acid compound used for the secondary treatment, those known as compounds that can improve the corrosion resistance of conventional aluminum pigments are used. Examples of the inorganic phosphoric acid compound include orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid and the like, and inorganic phosphates such as 1 ammonium dihydrogen phosphate, 1 ammonium dihydrogen phosphate, and manganese (II) phosphate monobasic salt may also be used. Examples of the organic phosphoric acid compounds include methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, hexyl acid phosphate, octyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, cyclohexyl acid phosphate, phenyl acid phosphate, Organic acidic phosphates such as nonylphenyl acid phosphate and triphenyl phosphite can be used. Various organic amines can be used as the base constituting the salt of the organic phosphate ester. Among them, aliphatic primary amines and secondary amines having a total carbon number of 3 to 36 are preferable. This is because, when added in the form of acidic salts with these organic amines, the physical properties of the coating film, particularly hot water resistance, are remarkably improved.

Aliphatic primary and secondary amines include butylamine, dibutylamine, hexylamine, dihexylamine, octylamine, dioctylamine, decylamine, didecylamine, laurylamine, dilaurylamine, myristylamine, dimyristylamine, oleylamine And stearylamine.

The method of treating the primary treated aluminum pigment with the phosphoric acid-based secondary treatment agent depends on the type of the secondary treatment agent. When the treatment agent is an organic solvent-insoluble water-soluble compound such as phosphate, an aqueous solution of the secondary treatment agent is added to the primary-treated aluminum pigment cake to cause a reaction, and after solid-liquid separation, it can be mixed with water. It is desirable to wash with an organic solvent. By washing with an organic solvent that can be mixed with water, the water-soluble phosphate compound is uniformly and firmly deposited and fixed on the surface of the aluminum pigment, and at the same time, free phosphate ions that cause the temperature resistance of the coating to decrease. Are washed away with this organic solvent. On the other hand, when the secondary treatment agent is an organic solvent-soluble compound such as orthophosphoric acid or butyl acid phosphate, a treatment solution dissolved in a suitable organic solvent such as isopropyl alcohol or toluene is added to the primary treated aluminum pigment cake. It is desirable to knead.

The phosphoric acid-based film thus formed has a P element content of 0.05 to 1% by mass, preferably 0.1 to 0.5% by mass with respect to aluminum. If it is less than the lower limit, it is insufficient to suppress the generation of hydrogen gas. On the other hand, if the upper limit is exceeded, the hot water resistance and adhesion of a coating film prepared from an aluminum pigment will be lowered.

The aluminum pigment on which the molybdic acid-based coating is formed in this manner usually contains a high-boiling hydrophilic solvent as a volatile component from the viewpoint of application. As high-boiling hydrophilic solvents, propylene glycol solvents and ethylene glycol solvents such as propylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, Dipropylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc. can be used.

<Film formed from silica film and / or silane coupling agent>
As a method for forming a silica coating on the surface of an aluminum pigment (aluminum particles), there is a case where a molybdenum coating for coating the surface of aluminum particles is formed as a pretreatment.

Here, the molybdenum film is a film made of molybdenum oxide and / or molybdenum hydrate, and the molybdenum oxide specifically represents MoO ₃ , Mo ₂ O _{3, and the} like. It is specifically intended to indicate that such _{MoO 3 · H 2 O, MoO} 3 · H 2 O 2 · H 2 O.

By forming a molybdenum coating on the surface of the aluminum particles used in the present invention, the coating becomes the nucleus of precipitation, and it becomes easy to form a silica coating that further covers the surface of the molybdenum coating.

In addition, since the molybdenum coating has a certain corrosion resistance, the aluminum pigment having the molybdenum coating improves the corrosion resistance. Further, the molybdenum coating includes a coating solution formed from a silica coating and / or a silane coupling agent (a solution containing water and a strong alkaline or acidic solution) and aluminum coated with the molybdenum coating. It also has the effect of preventing abnormal reactions with particles.

The amount of Mo contained in the molybdenum film formed on the aluminum particle surface used in the present invention is preferably 0.01 parts by mass or more, and 0.05 parts by mass or more with respect to 100 parts by mass of the aluminum particles. More preferably. Further, the amount of Mo is preferably 5.0 parts by mass or less, and more preferably 2.0 parts by mass or less. The amount of Mo is desirably changed according to the specific surface area of the aluminum particles to be processed. For aluminum particles having a large specific surface area, it is preferable to increase the amount of Mo and to decrease it when the specific surface area is small.

When the amount of Mo is less than 0.01 parts by mass, the chemical stability tends to decrease, and when it exceeds 5.0 parts by mass, the decrease in the color tone (metallic luster) of the aluminum pigment increases. Inconveniences such as agglomeration of the aluminum pigment and deterioration of physical properties of the coating film may occur.

Further, the above molybdenum film does not need to be a film made of only molybdenum oxide and / or molybdenum hydrate, and may contain other additives and impurities within the range not impairing the characteristics of the present invention. .

Next, the silica coating may coat the surface of the aforementioned molybdenum coating further or directly coat the aluminum surface together with the coating formed from the silane coupling agent.

Here, the silica coating is a coating made of amorphous silica. Specifically, the amorphous silica is siloxane [H ₃ SiO (H ₂ SiO) _n SiH ₃ ], SiO ₂ , SiO ₂ · nH. It shall represent ₂ O etc. Here, in the above chemical formula, n represents an arbitrary positive integer.

In addition, what has a silica film on the surface of an aluminum pigment has a further superior corrosion resistance than the case where it has only a molybdenum film.

Also, since amorphous silica has a hydrophilic surface, the aluminum pigment of the present invention having a silica coating can be easily dispersed in an aqueous paint. Moreover, since amorphous silica is very stable in an aqueous solution, the aluminum pigment of the present invention having a silica coating is very stable in an aqueous solution.

Furthermore, another corrosion inhibitor may be added to the silica coating on the surface of the aluminum pigment for the purpose of further improving the corrosion resistance of the aluminum pigment. The corrosion inhibitor to be added is not particularly limited, and a known corrosion inhibitor can be used in such a blending amount that does not impair the effects of the present invention. Specific examples include acidic phosphate esters, dimer acids, and organic compounds. Examples thereof include phosphorus compounds and metal salts of molybdic acid.

Further, the above silica coating does not need to be a coating made of only amorphous silica, and may contain other additives and impurities as long as the characteristics of the present invention are not impaired.

In addition, by applying a film formed from a silane coupling agent on a molybdenum film or a silica film, the reactivity to water can be further suppressed, and adhesion, moisture resistance, weather resistance, etc. Various effects can be expected, such as improving the physical properties of the coating film, improving the dispersibility in the paint, and improving the orientation of the aluminum pigment.

However, depending on the type of silane coupling agent used, the water dispersibility may be reduced, but it can be improved by using an appropriate surfactant. The film obtained from the silane coupling agent is obtained by hydrolyzing a silane coupling agent as shown below and reacting with a hydroxyl group in the silica film on the surface of the aluminum particles.

For example, methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, 3-aminopropyl-trimethoxysilane, n-methyl-3-aminopropyl-trimethoxysilane 3-aminopropyl-triethoxysilane, 3-aminopropyl-tris (2-methoxy-epoxy-silane), n-aminoethyl-3-aminopropyltrimethoxysilane, n-aminoethyl-3-aminopropyl-methyl -Dimethoxysilane, 3-methacryloxypropyl-trimethoxysilane, 3-methacryloxypropyl-methyl-dimethoxysilane, 3-acryloxypropyl-trimethoxysilane, 3-glycidyloxypropyl- Limethoxysilane, 3-glycidyloxypropyl-methyl-dimethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-triethoxysilane, 3-mercaptopropyl-methyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane , Vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, vinyltriacetoxysilane, 3- (3,4-epoxycyclohexylethyltrimethoxy) silane, γ-aminopropyltriethoxysilane, N-β- ( Aminoethyl) -γ-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-anilidepropyltrimethoxysilane, 3- (4,5-dihydro (Midazolepropyltriethoxy) silane, n-phenyl-3-aminopropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, trifluoropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane , P-styryltrimethoxysilane and the like.

The following compounds are used as particularly preferred silane coupling agents.
R _A —Si (OR _B ) ₃ or R _A —SiR _B (OR _B ) ₂
R _A : C _2-18 alkyl group, aryl group or alkenyl group R _B : C 1-3 alkyl group The following compounds are also exemplified.

Examples include n-propyltrimethoxysilane, isobutyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, octadecyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, and the like.

Here, the total content of silicon contained in the silica film and the film formed from the silane coupling agent is preferably 1 part by mass or more with respect to 100 parts by mass of the aluminum pigment. More preferred. The silicon content is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.

When the silicon content is less than 1 part by mass, the corrosion resistance, water dispersibility, stability, etc. tend to be reduced. When the silicon content exceeds 20 parts by mass, the aluminum pigment aggregates. There may be a problem that the concealability is deteriorated or the color tone such as metallic luster is impaired.

<Method for producing aluminum pigment composition for water-based paint>
The manufacturing method of the aluminum pigment composition for water-based paints of this invention can be manufactured by adding and mixing an aluminum pigment, a rheology control agent, and an organic solvent.

The method of adding the rheology control agent is not particularly limited. For example, when the rheology control agent is in a liquid state at room temperature, a necessary amount can be added as it is. When the rheology control agent is in a solid state at room temperature, it is preferable to add a necessary amount after dissolving or dispersing in a suitable solvent. The rheology control agent may be added all at once or in stages.

Further, the mixing method after adding the above three members may be uniformly mixed with a normal stirrer such as a disper when the mixture of the aluminum pigment, the rheology control agent and the organic solvent is in a slurry state. In the state, it may be uniformly mixed by a kneader such as a kneader mixer, but is not limited thereto.

Further, the order of adding the aluminum pigment, the rheology control agent and the organic solvent is not particularly limited, but it is easy to uniformly mix the rheology control agent to the mixture (slurry state or paste state) of the aluminum pigment and the organic solvent. Is preferable.

In the case where a hydrophilic organic solvent is used as the organic solvent in the mixture of the aluminum pigment and the organic solvent, the hydrophilic organic solvent is used under the predetermined conditions specified in the present invention as described later. It is preferable to add the rheology control agent after performing the step of replacing with an organic solvent satisfying the above (hydrophilic organic solvent removing step). If the rheology control agent is added before the hydrophilic organic solvent removal step, the rheology control agent may be removed together with the hydrophilic organic solvent during the step, thereby reducing the effect of the present invention. This is because there is a possibility. Furthermore, in order to achieve the effects of the present invention, it is necessary to add an excessive rheology control agent, which is not economically preferable, and the process is performed using an organic solvent that satisfies the predetermined conditions specified by the present invention. Depending on the degree of filtration and washing, there is a possibility that the effect of the present invention may vary, which is not preferable in terms of manufacturing.

In addition, the aluminum pigment used in the aluminum pigment composition for water-based paints of the present invention is not particularly limited, but considering the water resistance of the aluminum pigment in the water-based paint, a treatment for forming a water-resistant film on the surface as described above. It is good to have been given. The process for forming such a water-resistant film is not particularly limited, and examples thereof include the processes shown in the method for forming a molybdic acid-based film on the surface of the aluminum pigment and the method for forming a silica film on the surface of the aluminum pigment as described above. . In the process of forming the water-resistant coating, a hydrophilic organic solvent is often used, and a hydrophilic organic solvent is usually used as the organic solvent in the treated aluminum pigment composition. In this case, in particular, this hydrophilic organic solvent is replaced with an organic solvent whose solubility in water is limited or the organic solvent of the present invention which is insoluble or hardly soluble in water (hydrophilic organic solvent removing step) ) May be required.

<Hydrophilic organic solvent removal step>
In many cases, the aluminum pigment composition after the water-resistant coating forming step contains a hydrophilic organic solvent as a main solvent.

The method for removing the hydrophilic organic solvent from this state is not particularly limited. For example, the aluminum pigment composition after the water-resistant film forming step is insoluble in an organic solvent or water having limited solubility in water. Alternatively, it is dispersed in a slightly soluble organic solvent (that is, an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less) and slurried, followed by suction filtration, and further 6 to 12 The hydrophilic organic solvent can be removed by repeating filtration and washing once to several times with an organic solvent having an SP value of 5 and a solubility in water of 30% by mass or less.

As another method, an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less after suction filtration of only the aluminum pigment composition after the water-resistant film forming step is used. The hydrophilic organic solvent can also be removed by filtration and washing.

When the aluminum pigment composition after the water-resistant coating forming step is dispersed in an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less, A ratio with an organic solvent having an SP value of 12 and a solubility in water of 30% by mass or less, an SP value of 6 to 12 after suction filtration, and a solubility in water of 30% by mass The degree of removal of the hydrophilic organic solvent can be adjusted by the frequency of the filtration / washing times with the organic solvent as described below.

Then, in the hydrophilic organic solvent removing step, the aluminum pigment after suction filtration and washing is added with an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less. Thus, an aluminum pigment composition for water-based paints containing an organic solvent having an SP value of 6 to 12 and a solubility in water of 30% by mass or less can be obtained.

<Water-based paint>
The water-based paint of the present invention contains the above-described aluminum pigment composition for water-based paints, and is sometimes referred to as a water-based metallic paint or a water-based metallic paint composition because it contains an aluminum pigment.

The blending amount of the aluminum pigment composition for water-based paint in the water-based paint of the present invention is preferably in the range of 0.1 to 30% by mass with respect to the water-based paint. When the blending amount is 0.1% by mass or more, it is preferable from the viewpoint that a desired design property can be obtained satisfactorily, and when it is 30% by mass or less, it is preferable from the point that the coating film has good sharpness. In addition, when the blending amount is less than 0.1% by mass, the decorative (metallic) effect of the aqueous paint tends to be reduced, and when the blending amount is more than 30% by mass, the characteristics of the aqueous coating are obtained. (Weather resistance, corrosion resistance, mechanical strength, etc.) may be insufficient.

In the aqueous paint of the present invention, a binder for aqueous paint can be appropriately blended. Examples of binders for water-based paints include thermosetting acrylic resin / melamine resin, thermosetting acrylic resin / CAB (cellulose acetate butyrate) / melamine resin, thermosetting polyester (alkyd) resin / melamine resin, thermosetting polyester. (Alkyd) resin / CAB / melamine resin, isocyanate curable urethane resin / room temperature curable acrylic resin, water-diluted acrylic emulsion / melamine resin, and the like. Such a binder for water-based paints is preferably blended within a range of 50 to 90% by mass with respect to the water-based paint.

In addition to the aluminum pigment composition for water-based paints and the binder for water-based paints, another color pigment, extender pigment or dye may be used in combination with the water-based paint of the present invention. Examples of the color pigment used in combination include organic color pigments, inorganic color pigments, pearl mica, alumina flakes, plate-like iron oxide, and silica flakes. These are preferably blended in the range of 1 to 30% by mass with respect to the water-based paint.

In addition to the above-mentioned components, surfactants, pigment dispersants, antifoaming agents, anti-settling agents, ultraviolet absorbers, and the like can be appropriately added to the water-based paint of the present invention.

<Example>
Hereinafter, although an example is given and the present invention is explained still in detail, the present invention is not limited to these.

<Preparation of aluminum pigment>
Aluminum paste B and aluminum paste C were prepared by forming a molybdate coating on the surface of the aluminum pigment contained in aluminum paste A as follows. That is, each of the aluminum paste B and the aluminum paste C contains an aluminum pigment having a molybdic acid-based film formed on the surface as a water-resistant film. The average particle diameter of the aluminum pigments described below is “D ₅₀ ” (particle diameter at 50% accumulation measured with a laser diffraction particle size distribution analyzer (trade name “Microtrac HRA9320-X100”, manufactured by Nikkiso Co., Ltd.)). Indicates.

First, 0.5 g of metal molybdenum powder was added little by little to 10 g of hydrogen peroxide containing 30% by mass of hydrogen peroxide, and the resulting solution was isopropyl alcohol (SP value: 11.5 at 20 ° C.). Solubility in water (hereinafter simply referred to as “water solubility”): 100% by mass) (hereinafter referred to as IPA) Aluminum paste A containing aluminum pigment having no water-resistant coating (Aluminum pigment average particle size 18 μm, solid content 65% by mass, mineral spirit (SP value: 7.7, solubility in water: almost 0% by mass) as organic solvent and solvent naphtha (SP value: about 8.7) 153.8 g (100 g as the aluminum content) and propylene glycol monomethyl ether containing 28.8 g) (solubility in water: almost 0% by mass) (SP value: 10.2, solubility in water: 100% by mass) is added and stirred at 50 ° C. for 1 hour. After solid-liquid separation of the aluminum pigment having a water-resistant coating on the surface, propylene glycol monomethyl ether is used. Aluminum paste B (containing an aluminum pigment having a water-resistant coating on its surface, an average particle diameter of 18 μm, a solid content of 65% by mass, and a propylene glycol monomethyl ether as a hydrophilic organic solvent by 35% by mass) by adjusting the amount of the solvent Obtained.

On the other hand, 100 g of the aluminum paste B thus obtained was further dispersed in 100 g of mineral spirit, and suction filtration was performed. After filtration, it was further filtered and washed with 100 g of mineral spirit. Thereby, the aluminum paste C (solid content 65 mass% and mineral spirit 35 mass% containing) which substituted the mineral spirit with the propylene glycol monomethyl ether which is the hydrophilic organic solvent contained in the aluminum paste B was obtained.

<Example 1>
Aluminum containing 2.5 g of a commercially available rheology control agent “Flownon SDR-80” (manufactured by Kyoeisha Chemical Co., Ltd., active ingredient 80 mass%, sulfate anionic activator) and an aluminum pigment having no water-resistant coating Paste D (trade name “6360NS”: manufactured by Toyo Aluminum Co., Ltd., average particle size of aluminum pigment 12 μm, solid content 69% by mass, mineral solvent (17% by mass), solvent naphtha (14% by mass) as organic solvent) In addition to 145 g (100 g as the aluminum content), the mixture was stirred at 50 ° C. for 10 minutes to obtain aluminum paste E (solid content 67.8% by mass). This aluminum paste E contains an aluminum pigment (without a water-resistant coating), a rheology control agent (sulfate ester anionic activator), an organic solvent (mineral spirit (16.7% by mass), solvent naphtha (13.8%). It corresponds to the aluminum pigment composition for water-based paints according to the present invention. Here, the properties of “Flownon SDR-80” were examined using the above-mentioned “resin emulsion A” and “evaluation method of rheology control agent”. As a result, viscosity B ₆₀ was 364 mPa · s (0.364 Pa · s), viscosity. B ₆ was 0.43 Pa · s, and the TI value was 1.2.

Table 1 shows the results (color tone and metallic unevenness) of this aluminum paste E painted with a metallic bell under the coating composition, coating conditions and coating conditions described later.

In Table 1, “aluminum paste” indicates the type of aluminum paste used. In the column of “Water Resistant Coating”, “Yes” is indicated when the water resistant coating is formed on the surface of the aluminum pigment contained in the aluminum pigment composition for water-based paints, and “None” when the water resistant coating is not formed. ". In the column of “specific organic solvent”, the aluminum pigment composition for water-based paints has a mineral spirit as an organic solvent having a solubility parameter of 6 to 12 and a solubility in water at 20 ° C. of 30% by mass or less. When included, it was written as “MS”, when it contained solvent naphtha, it was written as “SN” (when both were included, they were written together), and when neither was included, it was left blank. In the column of “hydrophilic organic solvent”, when the aluminum pigment composition for water-based paint contains propylene glycol monomethyl ether, “PG” is indicated, and when none is contained, it is left blank. In the column of “rheology control agent”, when the aluminum pigment composition for water-based paint contains a rheology control agent, it is described as “contained”; The pigment composition does not contain a rheology control agent, but the one in which the rheology control agent is added to the water-based paint is referred to as “external addition”.

<Example 2>
20 g of a commercially available rheology control agent “Flownon SA-345HF” (manufactured by Kyoeisha Chemical Co., Ltd., 10% by mass of active ingredient, polyolefin base) is added to the same aluminum paste D145 g used in Example 1, and 10 The mixture was stirred for a minute to obtain an aluminum paste F (solid content 61% by mass). This aluminum paste F includes an aluminum pigment (without a water-resistant coating), a rheology control agent (polyolefin base), and an organic solvent (mineral spirit (15% by mass), solvent naphtha (12% by mass)). It corresponds to an aluminum pigment composition for water-based paints. Here, when the characteristics of “Flownon SA-345HF” were examined using the above-mentioned “resin emulsion A” and “evaluation method of rheology control agent”, viscosity B ₆₀ was 437 mPa · s (0.437 Pa · s), viscosity B ₆ was 0.51 Pa · s, and the TI value was 1.2.

Table 1 shows the results of coating this aluminum paste F with a metallic bell under the coating composition, coating conditions and coating conditions described later.

<Example 3>
A commercial rheology control agent “Flownon HR-4AF” (manufactured by Kyoeisha Chemical Co., Ltd., active ingredient 20 mass%, higher fatty acid amide) 17.4 g was added to the same aluminum paste D145 g used in Example 1, 50 The mixture was stirred at 0 ° C. for 10 minutes to obtain an aluminum paste G (solid content: 62% by mass). The aluminum paste G includes an aluminum pigment (without a water-resistant coating), a rheology control agent (higher fatty acid amide), and an organic solvent (mineral spirit (15% by mass), solvent naphtha (12% by mass)). It corresponds to the aluminum pigment composition for water-based paints. Here, when the characteristics of “Flownon HR-4AF” were examined using the above-mentioned “resin emulsion A” and “evaluation method of rheology control agent”, viscosity B ₆₀ was 401 mPa · s (0.401 Pa · s), viscosity B ₆ was 0.43 Pa · s, and the TI value was 1.1.

Table 1 shows the results of coating this aluminum paste G with a metallic bell under the coating composition, coating conditions and coating conditions described below.

<Example 4>
In addition to 145 g of the same aluminum paste D used in Example 1, 2.0 g of “BYK-425” which is a commercially available rheology control agent (manufactured by Big Chemie, having a solid content of 100% by mass and a urea-modified urethane structure) The mixture was stirred for 10 minutes at a temperature to obtain aluminum paste H (solid content: 68% by mass). This aluminum paste H is composed of an aluminum pigment (having no water-resistant coating), a rheology control agent (having a urea-modified urethane structure), an organic solvent (mineral spirit (16.8% by mass), solvent naphtha (13.8% by mass). %)) And the aluminum pigment composition for water-based paints of the present invention. When the characteristics of “BYK-425” were examined using the above-mentioned “resin emulsion A” and “evaluation method of rheology control agent”, the viscosity B ₆₀ was 614 mPa · s (0.614 Pa · s), and the viscosity B ₆ was 0.79 Pa · s, and the TI value was 1.3.

Table 1 shows the results of coating this aluminum paste H with a metallic bell under the coating composition, coating conditions and coating conditions described later.

<Example 5>
2.0 g of the same “BYK-425” used in Example 4 was added to 154 g of the aluminum paste C obtained above (100 g as the aluminum content) and stirred at 50 ° C. for 10 minutes to obtain an aluminum paste I (solid content of 64 Mass%). This aluminum paste I includes an aluminum pigment (having a water-resistant coating), a rheology control agent (having a urea-modified urethane structure), and an organic solvent (mineral spirit (34.7% by mass)). It corresponds to a pigment composition.

Table 1 shows the results of coating this aluminum paste I with a metallic bell under the coating composition, coating conditions and coating conditions described later.

<Comparative Example 1>
Table 1 shows the results of coating the above-described aluminum paste A with a metallic bell under the coating composition, coating conditions and coating conditions described later.

The aluminum paste A is a comparative aluminum pigment composition for water-based paints containing an aluminum pigment (without a water resistant coating) and an organic solvent (mineral spirit (16% by mass), solvent naphtha (19% by mass)). It corresponds to a thing.

<Comparative example 2>
Table 1 shows the results of coating the above-described aluminum paste B with a metallic bell under the coating composition, coating conditions and coating conditions described later.

The aluminum paste B corresponds to a comparative aluminum pigment composition for aqueous paint containing an aluminum pigment (having a water-resistant coating) and an organic solvent (hydrophilic propylene glycol monomethyl ether (35% by mass)).

<Comparative Example 3>
Table 1 shows the results of coating the above-described aluminum paste D with a metallic bell under the coating composition, coating conditions and coating conditions described later.

The aluminum paste D corresponds to a comparative aluminum pigment composition for water-based paints containing an aluminum pigment (without a water resistant coating) and an organic solvent (mineral spirit, solvent naphtha).

<Comparative Example 4>
After preparing a water-based paint with the composition described later using the aluminum paste D, “BYK-425”, which is a rheology control agent used in Example 4, becomes 2.0 mass% with respect to the aluminum paste D. Was added to this water-based paint. Table 1 shows the results of coating with a metallic bell using the water-based paint under the coating and coating conditions described below.

The aluminum paste D corresponds to a comparative aluminum pigment composition for water-based paints containing an aluminum pigment (without a water-resistant coating) and an organic solvent (mineral spirit, solvent naphtha), and thus rheology. An aqueous paint is prepared once using an aluminum pigment composition for an aqueous paint that does not contain a control agent, and then a rheology control agent is added separately and independently to the aqueous paint.

<Coating composition, coating conditions and coating conditions>
Using each of the aluminum pastes described above, a water-based paint having the following composition (hereinafter referred to as a water-based paint composition for base coats) was prepared, and a surface-treated steel sheet (JIS G3310 steel sheet coated with zinc phosphate) electrodeposited with an automotive cationic electrodeposition paint. The base coating aqueous coating composition was applied under the following coating conditions to the surface of a steel sheet that had been subjected to a system chemical conversion treatment) and a polyester / melamine resin-based intermediate coating.

That is, with respect to the steel plate (450 mm × 300 mm) subjected to the above electrodeposition coating and intermediate coating, a base coat aqueous coating composition was coated with a metallic bell (bell rotation speed: 25000 rpm, conveyor speed: 3 m / min, Reciprocating speed: 60 m / min, reciprocating length: 1000 mm, shaping air: 2.5 kg / cm ² , discharge amount: 150 cc, applied voltage: −90 kV, booth atmosphere: temperature 25 ° C., humidity 75% RH), 80 ° C. × 3 A preheat for a minute was performed. Next, an organic solvent-type topcoat paint having the following composition was applied by air spray so as to have a dry film thickness of 40 μm, thereby preparing a metallic paint coated plate. Subsequently, this metallic paint coating plate was baked at 140 ° C. for 30 minutes. The film thicknesses of the base coat layer and the top coat layer after curing and drying were 15 μm and 40 μm, respectively.

<Water-based paint composition for base coat>
Aluminum paste 0.9 parts by weight Butyl glycol 4.8 parts by weight AQ320 (* 1) 0.1 part by weight Dimethylethanolamine (10% aqueous solution) 6.4 parts by weight Deionized water 27.0 parts by weight Setalux 6802 AQ-24 ( * 2) 26.7 parts by weight Bayhydrol PT241 (* 3) 3.9 parts by weight Bayhydrol XP2621 (* 4) 16.0 parts by weight Cymel 327 (* 5) 1.8 parts by weight Viscalex HV30 (* 6) 0.4 parts by weight Part 12.0 parts by weight of deionized water <Organic solvent type paint for top coat>
DesmophenA 870BA (* 7), 70% in butyl acetate 51.2 parts by mass Baysilone Paint Additive OL 17 (* 8), 10% in xylene 0.5 parts by mass Modaflow (* 9), 1% in xylene 0.5 mass Part Tinuvin 292 (* 10), 10% in xylene 5.3 parts by mass Tinuvin 1130 (* 11), 10% in xylene 10.7 parts by mass 1-methoxypropyl acetate / solvent naphtha = 1/1 solvent 10.2 parts by mass Parts butyl glycol acetate 2.1 parts by weight DesmodurN 3390BA / SN (* 12),
90% butyl acetate / solvent naphtha = 1/1 solution 19.5 parts by mass The symbols (* 1) to (* 12) indicate the company name (manufacturer) and the compound name as follows.

<Evaluation of color tone>
The color tone evaluation was performed about each metallic paint coating board obtained by making it above.

The color tone evaluation was performed by measuring the lightness and saturation of the metallic painted plate using an X-Rite MA68II multi-angle spectrocolorimeter. The colorimetric values were expressed in the L ^* a ^* b ^* color system (CIE 1976) and evaluated by paying attention to the change in L ^* values. In colorimetry, light deviated by 15 °, 25 °, 45 °, 75 °, and 110 ° from specularly reflected light was detected. In this case, the quality of the color tone was evaluated based on the 15 ° closest to the specular reflection light. Table 1 shows the measured values. The larger the value, the higher the brightness.

<Evaluation of metallic unevenness>
Metallic unevenness was evaluated for each of the metallic paint coated plates obtained as described above. Sensory evaluation by visual observation of one observer was performed. Evaluation was made into 10-step evaluation. That is, the best state without metallic unevenness was “10”, the smaller the numerical value, the greater the unevenness, and the worst state was “1”.

The results of Table 1 above are summarized below.
<Difference in effect due to the presence or absence of rheology control agent>
When Examples 1, 2, 3, 4 and Comparative Example 3 were compared, metallic unevenness was improved by adding a rheology control agent to the aluminum pigment composition for water-based paints (that is, the orientation of the aluminum pigment was improved). Improved).

<Difference in effect due to the addition of rheology control agent>
When Example 4 and Comparative Example 4 were compared, it was found that the metallic unevenness was worsened in Comparative Example 4 in which the rheology control agent was blended directly into the aqueous paint, not the aluminum pigment composition for aqueous paint.

<Synergistic effect of a combination of an organic solvent having a solubility parameter of 6 to 12 and a solubility in water at 20 ° C. of 30% by mass or less and a rheology control agent>
A comparison between Examples 1 and 5 and Comparative Example 2 shows that a combination of an organic solvent having a solubility parameter of 6 to 12 and water solubility at 20 ° C. of 30% by mass or less and a rheology control agent. It was found that the color tone and metallic unevenness can be improved.

<Evaluation of water resistance>
Both of the aluminum pigments contained in the aluminum pigment compositions for water-based paints of Example 5 and Comparative Example 2 have a water-resistant coating on their surfaces, so that they are superior in water resistance compared to those having no water-resistant coating. It was. That is, 200 g of the water-based paint composition for a base coat containing each of the aluminum pigment composition for a water-based paint of each example and the aluminum pigment composition for a water-based paint of each comparative example was sampled, and the sample was adjusted to 40 ° C. The accumulated hydrogen gas generation amount when stored in a water bath for 7 days was measured with a graduated cylinder by the water displacement method. As a result, each of the water-based paint compositions for base coats containing the aluminum pigment composition for water-based paints of Example 5 and Comparative Example 2 showed no gas generation even after standing for 7 days. Generation of gas was confirmed in all cases where the aluminum pigment composition for water-based paints was allowed to stand for 7 days.

Thus, the aluminum pigment compositions for water-based paints of Example 5 and Comparative Example 2 were both excellent in water resistance, but as is clear from Table 1, the aluminum pigment composition for water-based paints of Example 5 was Compared with the aluminum pigment composition for water-based paints of Comparative Example 2, the metallic unevenness was extremely good.

Therefore, it was confirmed that the aluminum pigment composition for water-based paints having the constitution of the present invention can achieve both high improvement in water resistance and improvement in metallic unevenness.

As described above, the embodiments and examples of the present invention have been described, but it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (5)

1. An aluminum pigment composition for water-based paints comprising at least an aluminum pigment, a rheology control agent and an organic solvent,
   The organic solvent has a solubility parameter of 6 to 12, and has a solubility in water at 20 ° C. of 30% by mass or less,
   When the rheology control agent is added in an amount of 2.5 parts by mass with respect to 100 parts by mass of the solid content in the resin emulsion and the viscosity is measured using a B-type viscometer, the viscosity at 60 rotations B ₆₀ and 6 and the viscosity B ₆ during rotation is in both the range of 0.3 ~ 30Pa · s, and thixotropic index is the ratio B ₆ / B ₆₀ and the B ₆₀ and the B ₆ to exhibit 1-60 An aluminum pigment composition for water-based paints.
2. The aluminum pigment composition for water-based paints according to claim 1, wherein the rheology control agent is contained in an amount of 0.01 to 50 parts by mass with respect to 100 parts by mass of the aluminum pigment.
3. The rheology control agent is one or more compounds selected from the group consisting of urethane, acrylic, polyolefin, amide, anionic active agent, nonionic active agent, polycarboxylic acid, cellulose, and urea. The aluminum pigment composition for water-based paints according to range 1.
4. The aluminum pigment composition for water-based paints according to claim 1, wherein the organic solvent is contained in an amount of 10 to 1000 parts by mass with respect to 100 parts by mass of the aluminum pigment.
5. A water-based paint comprising the aluminum pigment composition for water-based paint according to claim 1.