JP2005187512A - Aqueous powder slurry coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous powder slurry coating in which the fluidity of the coating component that is obtained after the aqueous medium is evaporated and dried is improved to bring forth prevention of the sagging and the continuous film formed thereafter is excellent in smoothness. <P>SOLUTION: The aqueous powder slurry coating composition is the one in which a pigment particle and a water-insoluble film-formable resin particle, or a composite particle wherein a pigment is coated by a film-formable resin having a self water dispersive property, and a resin globular particle consisting of a resin incompatible with the above resin and having a smaller average particle diameter is dispersed in an aqueous medium that contains a surfactant where deemed necessary. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aqueous powder slurry paint that can improve the fluidity of paint components after the aqueous medium is evaporated and dried to prevent sagging and is excellent in the smoothness of a continuous film formed thereafter.

  In order to reduce the burden on the environment and improve the working environment, paints that do not contain organic solvents are being actively developed. One direction of development is powder paint, and the other is water-based paint. Although the powder paint does not contain an organic solvent, it has a powder form, so that the smoothness of the colored coating is inferior to that of the liquid paint, and there is a problem that the working environment is deteriorated due to dust.

  In the case of water-based paints, the disadvantages of powder paints are eliminated, but generally, the film-forming resin is water-soluble, and the colored film has excellent smoothness but lacks high durability. have. Therefore, attention is focused on water-based paints in which the film-forming resin is made water-dispersible to increase the durability of the film.

  For such water-based paint applications, water-based pigments of colored particles (so-called microcapsule-type colored particles) that do not contain an organic solvent or an external emulsifier (surfactant) and whose pigment is coated with a self-dispersible film-forming resin It is known that a dispersion can be applied (see Patent Document 1). An aqueous powder slurry paint in which a pigment and a resin are dispersed as separate particles in an aqueous medium, although not containing microcapsule-type colored particles, is also known (see Patent Document 2).

  Aqueous powder slurry coating based on such an aqueous pigment dispersion of microcapsule-type colored particles, to which an ionic thickener or a nonionic associative thickener is added to improve the dispersibility and fluidity. Is known (see Patent Document 3). Also known is an aqueous powder slurry paint that does not contain microcapsule-type colored particles, but that contains a non-urethane associative thickener added to a powder slurry in which pigment and resin are dispersed in an aqueous medium as separate particles. (See Patent Document 4).

  However, these thickeners are suitable for improving dispersibility, fluidity, etc. until the liquid medium in the coating is evaporated to dryness. The fluidity in the process could not be controlled effectively.

  In a coating containing an organic solvent, it is also known to add a microgel having a particle size of 0.2 to 1.5 μm to prevent sagging (see Patent Document 5). However, the aqueous powder slurry paint has a drawback that an excellent effect is not exhibited.

  Depending on whether the liquid medium is an organic solvent or water, and whether the resin component that forms the continuous film is soluble or insoluble in the liquid medium, the fluidity of the paint component after evaporation of the liquid medium varies greatly. Additives that adjust the fluidity of paints are called, for example, fluidity modifiers, rheology modifiers, sagging inhibitors, thickeners, etc., and various types are actually known. When applied to a slurry paint system, there is no actual knowledge about what is suitable for improving the fluidity of the resin component after evaporation of the liquid medium. There is a need for an aqueous powder slurry coating composition that can improve the fluidity of paint components after the aqueous medium is evaporated and dried to prevent sagging, and is excellent in the smoothness of the continuous film formed thereafter.

Japanese Patent Laid-Open No. 3-221137 Japanese Patent Laid-Open No. 2002-275427 JP-T-2002-524648 JP 2002-275376 A JP-A-8-269394 JP-A-8-311369

  An object of the present invention is to provide an aqueous powder slurry paint that can improve the fluidity of paint components after the aqueous medium is evaporated and dried to prevent sagging, and is excellent in the smoothness of the continuous film formed thereafter. And

  As a result of intensive studies in view of the above circumstances, the present inventors have solved the above problems in an aqueous powder slurry paint mainly composed of an aqueous pigment dispersion of colored particles composed of a pigment and a film-forming resin. Has found that the addition of specific resin particles is suitable, and has completed the present invention.

  That is, the present invention comprises a pigment (A), a water-insoluble film-forming resin (b1), and resin particles (D) having a smaller average particle diameter made of a resin incompatible with the resin (b1). An aqueous powder slurry coating composition characterized by being dispersed in an aqueous medium containing a surfactant (E) (hereinafter referred to as the first invention) is provided.

  In the present invention, the pigment (A) has a smaller average particle size comprising the colored particles (c1) coated with the water-insoluble film-forming resin (b1) and the resin (b1) incompatible with the resin (b1). Provided is an aqueous powder slurry coating composition characterized in that the resin particles (D) are dispersed in an aqueous medium containing a surfactant (E) (hereinafter referred to as the second invention).

  Further, the present invention provides a smaller average particle comprising the colored particles (c2) in which the pigment (A) is coated with a self-dispersible film-forming resin (b2) and a resin incompatible with the resin (b2). Provided is an aqueous powder slurry coating composition characterized in that resin particles (D) having a diameter are dispersed in an aqueous medium (hereinafter referred to as a third invention).

  The aqueous powder slurry coating composition of the present invention further contains resin particles having a smaller average particle diameter made of an incompatible resin with respect to the film-forming resin constituting the dispersed particles that form the continuous coating film. Therefore, the fluidity of the paint component after the aqueous medium is evaporated and dried can be improved to prevent sagging, and the smoothness of the continuous film formed thereafter is excellent.

Hereinafter, the present invention will be described in detail.
From the first invention to the third invention, as the aqueous powder slurry coating composition, resin particles having a smaller average particle diameter comprising a pigment, a film-forming resin, and a resin incompatible with the film-forming resin Is common in that it is contained in an aqueous medium. The major differences between the inventions are the following three points.
1) Whether the dispersed particles contained in the aqueous powder slurry coating composition are dispersed in the aqueous medium as separate particles of the pigment and the film-forming resin, or the pigment is coated with the film-forming resin Are they dispersed in an aqueous medium as particles?
2) Whether the film-forming resin contained in the aqueous powder slurry coating composition is water-insoluble and does not have self-water dispersibility or self-water dispersibility.
3) Whether or not a surfactant is contained in the aqueous powder slurry coating composition.

  Examples of the pigment (A) in the present invention include known and commonly used organic pigments and inorganic pigments. Examples of organic pigments include azo pigments, phthalocyanine pigments, condensed polycyclic pigments, nitroso pigments, and inorganic pigments include, for example, oxide pigments, chromate pigments, carbon pigments, Examples include mica pigments and metal powder pigments. These pigments (A) may be in the form of powder or wet cake. This pigment (A) is preferably a pigment having an average primary particle diameter of 0.05 to 30 μm.

  The film-forming resin (B) in the present invention is a water-insoluble film-forming resin (b1) or a self-water dispersible film-forming resin (b2). This film-forming resin (B) is not water-soluble and has a property of being dispersed in an aqueous medium in the presence of a surfactant (E) described later or in the absence of the surfactant (E). It must have the property of being dispersed in an aqueous medium. In the present invention, the film-forming resin that is not water-soluble and is dispersed in an aqueous medium in the presence of the surfactant (E) described later is referred to as a water-insoluble film-forming resin (b1). A film-forming resin that is dispersed in an aqueous medium in the absence of the surfactant (E) described later is referred to as a self-water-dispersible film-forming resin (b2).

  Moreover, in this invention, an aqueous medium means the thing containing 60% or more of water by mass conversion only with water or the mixture of water and a water-soluble organic solvent.

  In the present invention, the resin (b1) and the resin (b2) are selected and used from the film-forming resin (B) described later. Whether or not the resin (B) is water-soluble can be easily confirmed by mixing the resin (B) with water. The resin (b1) is generally a resin that does not contain hydrophilicity such as a carboxyl group or a sulfone group, and itself does not have water dispersibility, so that the surfactant (E) described later is used. Dispersed in an aqueous medium with the help. On the other hand, the resin (b2) is generally a base that will be described later with at least a part of the functional group of a resin containing a functional group that becomes anionized by neutralization such as a carboxyl group or a sulfone group and becomes hydrophilic. It is a resin obtained by neutralizing with a chemical substance. Since the resin (b2) itself has water dispersibility, it is easily dispersed in an aqueous medium without the aid of the surfactant (E).

  Examples of the film-forming resin (B) include alkyd resins, styrene resins, acrylic resins, polyester resins, epoxy resins, urethane resins, fluororesins, and silicon resins. These may be used singly, in combination of two or more, or in combination of two or more.

  These film-forming resins (B) may be those that are not crosslinked and cured. For example, alkyd resin, acrylic resin, polyester resin, fluororesin, silicon resin, epoxy resin as a main agent, and melamine as a curing agent. By using resin, urea resin, blocked isocyanate resin, polyamide resin, acid anhydride, polyfunctional epoxy compound, etc. in combination so as to become a known and commonly used curing system, including dispersed particles containing only the main resin Compared to the coating film obtained from the aqueous powder slurry coating composition, the durability of the coating film can be further improved, which is preferable. Here, if a thermosetting curing agent is used, an aqueous powder slurry coating composition containing dispersed particles containing the curing agent in an uncured state until the time of coating can be obtained.

  The main components for forming a continuous coating film in the aqueous powder slurry coating composition of the present invention are the pigment (A) and the film-forming resin (B). The pigment (A) particles and the water-insoluble film-forming resin (b1) particles are dispersed by the surfactant (E), and the pigment (A) is coated with the water-insoluble film-forming resin (b1). In a form in which the colored particles are dispersed by the surfactant (E), the colored particles in which the pigment (A) is coated with the self-water-dispersible film-forming resin (b2) without the surfactant (E) There are three forms: a distributed form. The latter two dispersed particles are so-called microcapsule type colored particles (composite particles).

  Examples of the surfactant (E) used in combination with the water-insoluble film-forming resin (b1) include known and commonly used surfactants such as anionic surfactants, nonionic surfactants, and amphoteric surfactants. Can be mentioned. Examples of basic substances used in preparing the self-water dispersible film-forming resin (b2) include ammonia, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, methylamine, and ethylamine. Primary amines, secondary amines such as dimethylamine and diethylamine, and tertiary amines such as trimethylamine and triethylamine. Moreover, as a basic substance, alkanolamines, such as a diethanolamine and a triethanolamine, can also be used, for example.

  In the aqueous powder slurry coating composition of the present invention, the volume average particle diameter of the dispersed particles in the aqueous medium composed of the pigment (A) and the film-forming resin (B) is not particularly limited, Usually 0.1 to 35 μm, especially 1 to 30 μm, especially smoothness when formed into a film, mixed toning properties when colored resin particles of different colors are mixed (the color mixed when formed into a film is uniform) In consideration of the difficulty of sedimentation required when a water-based powder slurry coating is used, it is preferably 3 to 15 μm. The dispersed particles in the first invention include pigment (A) particles and water-insoluble film-forming resin (b1) particles, and the dispersed particles in the second invention have film-forming properties in which the pigment (A) is water-insoluble. Colored particles coated with the resin (b1), and the dispersed particles in the third invention are colored particles in which the pigment (A) is coated with a self-dispersible film-forming resin (b2).

  The volume average particle diameter of the resin particles (D) contained in the aqueous powder slurry coating composition of the present invention can be easily measured by a dynamic light scattering method. The volume average particle diameter of the dispersed particles, which will be described later, can also be measured by the dynamic light scattering method. However, when handling large particles that are larger than the range that can be measured by the dynamic light scattering method, measure by the laser diffraction scattering method .

  The aqueous powder slurry coating composition of the present invention has a smaller average particle size made of a resin that is incompatible with the resin (B), in addition to the dispersed particles, which are the main components that form a continuous coating film. Resin particles (D) are contained. The resin particles (D) are required to have a volume average particle size relatively smaller than that of the dispersed particles, and specifically, the volume average particle size is preferably 5 to 200 nm. The resin particles (D) may or may not be self-water dispersible, but when the resin particles (D) do not have self-water dispersibility, in order to disperse them in an aqueous medium, As in the case of the dispersed particles, it is often necessary to use a surfactant (E) in combination. As will be described later, in order to prevent the film obtained from the aqueous powder slurry coating composition from being inferior in continuous film properties such as water resistance, the resin particles (D) must have self-water dispersibility. preferable.

  Further, the resin constituting the resin particles (D) needs to be incompatible (incompatible) with the film-forming resin (B) constituting the dispersed particles. Such a resin can be selected from the film-forming resin (B) described above. Whether or not the film-forming resin (B) constituting the dispersed particles and these resins are incompatible with each other is determined by mixing resin solutions of two different resins and evaporating the liquid medium in the resin solution. Whether or not each resin phase-separates when dried or after the remaining resin components are melted and formed into a film after drying. In addition, when phase separation is more remarkable, it can confirm easily that it is incompatible by the resin component becoming cloudy.

  The resin particles (D) are preferably crosslinked infusible and insoluble gel particles. Whether or not the resin in the resin particles (D) has such properties can be confirmed by, for example, confirming that the resin is not melted by gradually heating the resin to a high temperature (not melting), or This can be confirmed by the fact that swelling and dissolution do not occur when the is immersed in an organic solvent heated at high temperature.

  If the film-forming resin (B) constituting the dispersed particles and the resin constituting the resin particles (D) are in an incompatible relationship as described above, the former: acrylic resin and the latter: A combination of resins of the same type such as an acrylic resin may be used, or a combination of different resins such as the former: polyester resin and the latter: acrylic resin may be used. As a suitable combination of the specific film-forming resin (b1) or (b2) constituting the dispersed particles in the present invention and the resin constituting the resin particles (D), a paint component after the aqueous medium has evaporated is used. For example, it is a combination of the former: polyester resin and the latter: acrylic resin in that the sagging prevention effect during melting is good.

  The aqueous powder slurry coating composition of the present invention is converted into mass when the total of the pigment (A), the film-forming resin (B), and the resin particles (D) is 100% (based on the total solid content). And it is preferable to contain the resin particle (D) so that it may become 0.5 to 10%.

  The aqueous powder slurry coating composition of the present invention comprises the resin particles (with respect to the base coating composition in which dispersed particles composed of the pigment (A) and the film-forming resin (B) are dispersed in an aqueous medium. It can be prepared by adding D).

  Such a base coating composition includes a base coating composition (first) in which a pigment (A) and a water-insoluble film-forming resin (b1) are dispersed in an aqueous medium containing a surfactant (E). Corresponding to the base coating composition in the invention), the colored particles (c1) in which the pigment (A) is coated with the water-insoluble film-forming resin (b1) are dispersed in an aqueous medium containing the surfactant (E). The base coating composition (corresponding to the base coating composition in the second invention), the pigment (A) is coated with a self-dispersible film-forming resin (b2), and the colored particles (c2) are aqueous. A base coating composition (corresponding to the base coating composition in the third invention) dispersed in a medium.

These base coating compositions can be prepared, for example, as follows.
Manufacturing method 1:
A method in which a pigment (A), a water-insoluble film-forming resin (b1), a surfactant (E), and an aqueous medium are mixed and forcedly dispersed.
Manufacturing method 2:
A method in which the above-mentioned raw materials are reacted with the surfactant (E) in water in the presence of the pigment (A) to form a resin (b1), and are associated as necessary.
Manufacturing method 3:
The mixture of the pigment (A), the water-insoluble film-forming resin (b1), and the organic solvent is gradually phase-inverted from the oil phase to the water phase using water and the surfactant (E), and then the solvent is removed. The pigment (A) is colored particles coated with the resin (b1), and the colored particles are dispersed in water.
Manufacturing method 4:
The mixture of the pigment (A), the self-water dispersible film-forming resin (b2), and the organic solvent is gradually phase-inverted from the oil phase to the water phase using water, and then the solvent is removed. Is colored particles coated with the resin (b2), and the colored particles are dispersed in water.
Manufacturing method 5:
The solvent is removed from the mixture of the pigment (A), the self-water dispersible film-forming resin (b2), the organic solvent and water, and an acid substance is added to the resin (B) to increase the water dispersibility of the resin (b2). After drastically reducing and precipitating and washing the precipitate, the precipitate is dispersed in an aqueous medium together with a basic substance that is a neutralizing agent to form colored particles in which the pigment (A) is coated with the resin (b2). A method of dispersing colored particles in water.

  The base coating composition in the first invention can be easily prepared by the production method 1. The base coating composition in the second invention can be easily prepared by the production methods 2 and 3. The base coating composition in the third invention can be easily prepared by the production methods 4 and 5. Production methods 3 and 4 are methods for producing dispersed particles called a phase inversion emulsification method, and production method 5 is a method for producing dispersed particles by a precipitation method using acid precipitation (hereinafter referred to as an acid precipitation method). It is.

  In the manufacturing methods 3 to 5, an organic solvent is used. Here, any known and various organic solvents that dissolve the film-forming resin (B) without causing a reaction with the pigment (A) or the film-forming resin (B) can be used. However, in consideration of odor and influence on the environment, the finally obtained aqueous powder slurry coating composition preferably contains no organic solvent as much as possible.

  Examples of such an organic solvent include ketones such as methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; alcohols such as 2-propanol, 2-methyl-1-propanol, 1-butanol, and 2-methoxyethanol; Ethers such as tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane; amides such as dimethylformamide and N-methylpyrrolidone; lower monocarboxylic acid esters such as ethyl acetate and butyl acetate; It is preferable to use a ketone having 4 to 6 carbon atoms or a lower monocarboxylic acid ester.

  In the production methods 1 to 3, various surfactants (E) as described above can be used. By using the surfactant (E), it is possible to improve the dispersion stability of the dispersed particles in the aqueous medium, but the coating formed from the finally obtained aqueous powder slurry coating composition. The amount used is preferably as small as possible so as not to adversely affect the continuous film properties such as water resistance of the film. Specifically, an addition amount of 3% or less with respect to the film-forming resin (B) is preferable. The surfactant (E) is first added in its entirety to the aqueous medium to prepare an aqueous medium containing the surfactant (E) as a uniform, and this together with the pigment (A) and / or the film-forming property. A method of mixing the resin (B) is preferable.

  In preparing the aqueous powder slurry coating composition of the present invention, the use of each base coating composition obtained in accordance with the production method 4 or 5 does not contain the surfactant (E), and the coating composition is later used. This is preferable in that it does not adversely affect the continuous film characteristics.

  The method for producing dispersed particles by the phase inversion emulsification method of production method 4 is the same as the acid precipitation method of production method 5 in that there is no drawback of the aqueous powder slurry coating composition prepared using the surfactant (E). Although having the same advantage, it is preferable at the point which can prepare an aqueous-powder slurry coating composition by a process fewer than the manufacturing method 5. FIG.

  As described above, in the production method 4, the mixture of the pigment (A), the self-water dispersible film-forming resin (b2), and the organic solvent is gradually phase-inverted from the oil phase to the water phase using water. The solvent is removed to form colored particles in which the pigment (A) is coated with the resin (b2), and the colored particles are dispersed in water. This method is described in detail in Patent Document 1.

  This method is, for example, a method of mixing a mixture (sometimes referred to as a mill base) in which a pigment (A) is dispersed in an organic solvent solution of a self-water dispersible film-forming resin (b2), and water. Without using the surfactant (E), the pigment (A) can be colored particles (c2) coated with the resin (b2), and the colored particles (c2) are more spherical. The main feature is that the particle size distribution can be further sharpened in a small particle size range.

  In this method, first, an organic solvent dispersion in which the pigment (A) is dispersed and the self-water-dispersible film-forming resin (b2) is dissolved is mixed with phase-inversion emulsification, and the water of the swollen colored particles is mixed. A dispersion is produced.

  The self-water dispersible film-forming resin (b2) can be dispersed in water with high stability over time without using a surfactant (E), and itself can form a film. A resin having properties that can be formed (having film-forming properties). In terms of water dispersibility, this resin must not be 100% soluble in water (see Patent Documents 1 and 6). The resin (b2) can be selected from those exemplified in the description of the film-forming resin (B).

  Specifically, the self-dispersible film-forming resin (b2) is a styrene resin, an acrylic resin, or a polyester resin containing a functional group that becomes anionic by neutralization such as a carboxyl group and a sulfone group. Examples thereof include a resin obtained by neutralizing at least a part of the functional group with a basic substance, such as the polyurethane resin. Examples of the resin containing a functional group that becomes anionic upon neutralization include, for example, an acrylic resin or diol obtained by polymerizing a monoethylenically unsaturated monomer containing a carbosyl group and a (meth) acrylic acid ester as essential components. Polyester resin obtained by condensing a compound selected from the group consisting of dialkanol monocarboxylic acid, trimellitic acid and pyromellitic acid as essential components, and dialkanol monocarboxylic acid as essential components including diol and organic diisocyanate , Polyurethane resin obtained by addition polymerization of a compound selected from the group consisting of trimellitic acid and pyromellitic acid. As the basic substance for neutralizing the functional group that becomes anionic by neutralization of the resin, any of the above-mentioned substances can be used, but the volatile basic substance is used after the coating of the resin (b2). It is preferable because it volatilizes and the water resistance of the continuous coating film can be improved.

  An aqueous dispersion of colored particles (c2) swollen by mixing water and phase-inversion emulsifying the organic solvent dispersion in which the pigment (A) is dispersed and the self-water-dispersible film-forming resin (b2) is dissolved. Is obtained. Even if the organic solvent dispersion in which the pigment (A) is dispersed and the self-dispersible film-forming resin (b2) is dissolved is mixed with water and emulsified, the water dispersion of the swollen colored particles (c2) Is obtained.

  The organic solvent used in preparing the organic solvent dispersion is not limited as long as it is compatible with water as long as it dissolves the self-water-dispersible film-forming resin (b2). If an insoluble organic solvent is used, phase inversion is unlikely to occur and the particle size distribution of the colored particles tends to widen. On the other hand, if an organic solvent that is sufficiently compatible with water is used, slow phase inversion occurs and the colored particles are sufficiently There is a tendency not to form. On the other hand, as described above, in order to prevent the aqueous powder slurry coating composition from containing an organic solvent as much as possible, the organic solvent used here has an appropriate affinity for dissolving the resin (b2) and water. Among them, it is preferable to use an organic solvent having a solubility of 5 to 30% in water at 20 ° C. and dissolving the resin (b2). The aqueous dispersion of swollen colored particles (c2) is an aqueous dispersion containing an organic solvent and water but containing more water.

  Since the organic solvent-water mixed medium dispersion of the colored particles (b2) prepared by such phase inversion emulsification contains an organic solvent, the organic solvent-distilled solvent is distilled off to swell the colored particles (c2). It is possible to produce an aqueous dispersion of colored particles (c2) in which the resin (b2) is not swollen. The aqueous dispersion of the colored particles (c2) is the above-described base coating composition.

  In this solvent removal, distillation by heating, or depending on the type of resin (b2), the colored particles (c2) are not melted in a short time at a low temperature and under reduced pressure, or are suitable for water. It is necessary to recover the organic solvent that affects the environment by making fluid contact.

  In vacuum distillation, generally, a container filled with the dispersion is decompressed to remove and recover the organic solvent, or the dispersion is sprayed through a narrow orifice into a container set to maintain the required low pressure. There is a method of removing and recovering the organic solvent.

  In the method of distilling off the organic solvent using countercurrent contact, the organic solvent-water mixed medium dispersion of the colored particles (c2) and water are brought into countercurrent contact, and the organic solvent in the colored particles (c2) is removed. In addition to leaching, the organic solvent-water mixed medium dispersion is separated into a mixture of an organic solvent and water and an aqueous dispersion of colored particles (c2).

  Next, an aqueous pigment dispersion in which the colored particles (c2) in which the pigment (A) is coated with a self-dispersible film-forming resin (b2) is dispersed in an aqueous medium is added to the resin (b2). By mixing resin particles (D) having a smaller average particle size made of a soluble resin, an aqueous powder slurry coating composition is obtained.

  In consideration of the resin (b2) contained in the colored particles (c2), which are dispersed particles, the resin particles (D) are incompatible with the above-described particles of the film-forming resin (B) and the guideline described above regarding the particle diameter. Select according to.

  The resin particles (D) can be prepared by a known and commonly used method, but can be easily prepared by the phase inversion emulsification method of the production method 4 described above without using the pigment (A). By this method, similarly to the colored particles (c2), it is possible to further sharpen the particle size distribution of the resin particles (D) in a smaller particle size range.

  In order to obtain infusible and insoluble gel particles obtained by crosslinking the resin particles (D), a curing agent is used in combination without using the pigment (A), and the resin (b2), the curing agent, What is necessary is just to carry out cross-linking hardening after setting it as the particle | grains containing this. By carrying out like this, the aqueous dispersion of the resin particle (D) which consists of the bridge | crosslinked insoluble insoluble gel particle excellent in dispersion stability can be obtained.

  The aqueous powder slurry coating composition of the present invention is obtained by mixing the base coating composition comprising the aqueous dispersion of the colored particles (c2) and the aqueous dispersion of the resin particles (D), each obtained in this manner. Can be obtained. The resin particles (D) are added for the purpose of preventing sagging of the paint components after the aqueous medium is evaporated and dried, and an appropriate dispersion of the resin particles (D) with respect to the aqueous dispersion of the colored particles (c2). What is necessary is just to add the quantity. This addition amount is as described above.

  As mentioned above, although the manufacturing method of the aqueous powder slurry coating composition of this invention was explained in detail about the aqueous dispersion (base coating composition) of the colored particles obtained by the phase inversion emulsification method of the manufacturing method 4, the manufacturing method 1 The aqueous dispersion (base coating composition) obtained in 3 and 5 can also be used to produce the aqueous powder slurry coating composition of the present invention by the same operation.

  In addition, as the basic substance used when obtaining an aqueous dispersion of colored particles by the acid precipitation method of the production method 5 or the like, any of those described above can be used. Examples of the acidic substance include formic acid, acetic acid, Hydrochloric acid or the like can be used. In the case of preparing the aqueous powder slurry coating composition of the present invention using a self-water dispersible resin obtained by neutralizing a resin containing a carboxyl group or a sulfone group as the self-water dispersible resin (b2). As the self-water dispersible resin (b2), the water-based powder of the present invention is obtained by using a self-water dispersible resin obtained by neutralizing a resin containing an amino group having the opposite polarity to the above. A slurry coating composition can also be prepared.

  If necessary, a curing agent can be further added to the aqueous powder slurry coating composition of the present invention. Any of the aforementioned curing agents can be used. As the film-forming resin (B) for obtaining dispersed particles, the case where a curing agent is used in combination with a resin as a main agent has been exemplified before, but this is an internal curing system. On the other hand, as the film-forming resin (B), dispersed particles may be obtained using only the resin as the main agent, and a curing agent may be used in combination with this, which is an external curing system. Again, if a thermosetting curing agent is used, an aqueous powder slurry coating composition containing the curing agent in an uncured state until coating can be obtained. The aqueous powder slurry coating composition may be prepared so that an internal curing system and an external curing system are used in combination.

  In addition, the aqueous powder slurry coating composition of the present invention contains, as necessary, a filler, a rust inhibitor, a UV stabilizer, a UV absorber, a flow modifier, a repellency inhibitor, and the like as necessary. Can do.

  The aqueous powder slurry coating composition of the present invention has a total solid content of 10 to 60%, especially 20 to 50% in terms of mass, from the viewpoint of ease of drying and curing and easy adjustment to the viscosity of easy coating. Is preferred.

  The aqueous powder slurry coating composition of the present invention can be coated on various substrates and dried to form a continuous film by a known and commonly used coating method so as to obtain an appropriate dry film thickness according to the purpose. The aqueous powder slurry coating composition of the present invention further containing a thermosetting curing agent is baked to crosslink and cure the curing agent following the drying. As a coating method, for example, air spray coating, electrostatic coating, dip coating, brush coating, or the like can be employed. Examples of the substrate include synthetic resin plates such as polyethylene, polypropylene, and polyethylene terephthalate, and metal plates such as aluminum plates and steel plates. In the case of the aqueous powder slurry coating composition of the present invention further containing a thermosetting curing agent, only a metal plate can be selected by selecting a curing agent having an appropriate curing temperature and a synthetic resin plate from the viewpoint of heat resistance. In addition, baking can be applied to a synthetic resin plate.

  For car body painting, a multilayer coating film is formed on a metal plate. For example, a cationic electrodeposition coating layer, an intermediate coating layer, a top coating layer, and a clear coating layer are arranged in this order on a surface-treated steel plate. Are stacked. The aqueous powder slurry coating composition of the present invention containing a curing agent can be used as the intermediate coating and the top coating.

  Hereinafter, the present invention will be described in detail with reference to examples and the like. The present invention is not limited by these examples. All parts and% in the examples are based on mass.

Production Example 1 <Production Example of Aqueous Dispersion Containing Colored Particles (c2)>
1000 parts of Finedick (registered trademark) M-8420 (powder polyester resin manufactured by Dainippon Ink & Chemicals, Inc .; acid value = 33 ± 3) in a reaction vessel equipped with a stirrer, a temperature sensor, and a distillation apparatus And 1000 parts of methyl ethyl ketone were heated and mixed at 80 ° C. to dissolve the resin in methyl ethyl ketone, thereby preparing a resin solution in which the nonvolatile content was adjusted to 50%.
600 parts of the resin solution and 300 parts of “Typaque CR-97” (titanium dioxide manufactured by Ishihara Sangyo Co., Ltd.) are placed on a dynomill pigment disperser (model: KDL A type, manufactured by Willy et Bacofen). Then, it was dispersed for 2 hours by a circulation method (a method in which the dispersion liquid discharged from the disperser is returned to the mixing tank). Cooling water was passed through the cooling jacket so that the dispersion temperature was kept at 40 ° C. or lower.
After the dispersion is completed, the pigment dispersion is extracted from the mixing tank, and further 800 parts of the resin solution is added to the obtained dispersion. After uniformly mixing with a three-one motor, 33 parts of triethylamine is added with stirring to neutralize the mixture. To obtain a dispersion containing the pigment and the self-water dispersible resin.
100 parts of the dispersion thus obtained were charged into a reaction vessel and stirred. After about 10 minutes, 100 parts of water was added dropwise under stirring to cause phase inversion emulsification, whereby titanium dioxide was converted into a polyester resin. An aqueous pigment dispersion containing composite particles coated with was obtained. The organic solvent is removed from this aqueous pigment dispersion by distillation under reduced pressure, and further concentrated to eliminate swelling of the resin in the composite particles, and white, spherical composite particles in which 35% non-volatile content of titanium dioxide is coated with a polyester resin. A water dispersion was prepared in which was stably dispersed in water.
The volume average particle diameter of the aqueous dispersion was measured with a Microtrac 9220FRA (laser diffraction scattering type particle size analyzer manufactured by Nikkiso Co., Ltd.). It was confirmed that it was larger than the particle diameter.

Production Example 2 <Production Example of Water Dispersion Containing Resin Particles (D)>
Methyl ethyl ketone is added to the reaction vessel of an automatic polymerization reaction device (polymerization tester DSL-2AS type manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introducing device at the top 900 parts were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 150 parts of 2-hydroxyethyl methacrylate, 140 parts of methacrylic acid, 300 parts of styrene, 160 parts of butyl methacrylate, butyl acrylate, from a dropping device 150 parts were added dropwise over 4 hours. After completion of the dropwise addition, the reaction was further continued at the same temperature for 15 hours to obtain an anionic group-containing organic polymer compound solution having an acid value of 90, a weight average molecular weight of 17,000, and a glass transition point (calculated value) of 30 ° C. After completion of the reaction, a part of methyl ethyl ketone was distilled off under reduced pressure, and the nonvolatile content of the resin solution was adjusted to 50%.
100 parts of the resin solution and 3.0 parts of a curing agent “TETRAD-X” (Mitsubishi Gas Chemical Co., Ltd. N, N, N ′, N′-tetraglycidylmetaxylylenediamine) are used in a reaction vessel. After charging and stirring and mixing, 5.3 parts of triethylamine was added and neutralized to obtain a dispersion containing a pigment, a self-water dispersible resin, and a curing agent. Furthermore, about 10 minutes later, 250 parts of water was added dropwise with stirring to cause phase inversion emulsification to obtain an aqueous dispersion of resin particles made of a self-water dispersible acrylic resin containing a curing agent. . Subsequently, methyl ethyl ketone was removed and concentrated from this aqueous dispersion by distillation under reduced pressure in the same manner as described above. Thereafter, an aqueous dispersion of acrylic resin particles containing a curing agent, which has undergone solvent removal and concentration of methyl ethyl ketone, is allowed to stand in a thermostatic bath at 70 ° C. for 12 hours for crosslinking and curing, and has a non-volatile content of 25% and a volume average particle size of 20 An aqueous dispersion of acrylic resin particles having a self-dispersibility of 7 nm was obtained. The volume average particle size was measured with a laser Doppler particle size analyzer Microtrac UPA150 (Leeds & Northrop).
The resin constituting the resin particle (D) is phase-separated from the resin (B) constituting the colored particle, so that both are incompatible. The resin is gradually heated to a high temperature and does not melt. It was confirmed that the acrylic resin particles (D) were crosslinked infusible and insoluble gel particles because swelling and dissolution did not occur when immersed in heated tetrahydrofuran.

Production Example 3 <Production Example of Water Dispersion Containing Pigment and Resin>
Mix 1000 parts of Finedic (registered trademark) M-8420, 2000 parts of water and 59 parts of triethylamine while heating at 80 ° C. in a reaction vessel equipped with a stirrer, a temperature sensor and a distillation apparatus. The resin was dissolved in water to adjust the nonvolatile content to 35% to prepare an aqueous resin solution.
1050 parts of the resin aqueous solution and 300 parts of “Typaque CR-97” were passed through a dynomill pigment disperser and dispersed by a circulation method for 2 hours. Cooling water was passed through the cooling jacket so that the dispersion temperature was kept at 40 ° C. or lower.
After the dispersion is completed, the pigment dispersion is extracted from the mixing tank, and 1050 parts of the resin aqueous solution is further added to the obtained dispersion. After thoroughly mixing with a three-one motor, water is added to produce an aqueous dispersion having a nonvolatile content of 35%. did. This aqueous dispersion was an aqueous pigment dispersion in which a pigment was dispersed in an aqueous resin solution.

  By stirring and mixing 100 parts of the aqueous pigment dispersion obtained in Production Example 1 and 7 parts of an aqueous dispersion of acrylic resin particles obtained in Production Example 2, an aqueous powder having a non-volatile content of 34.3% A slurry coating composition was prepared.

Comparative Example 1
By stirring and mixing 100 parts of the aqueous pigment dispersion obtained in Production Example 3 and 7 parts of the aqueous dispersion of acrylic resin particles obtained in Production Example 2, an aqueous coating composition having a non-volatile content of 34.3% A product was prepared.

Comparative Example 2
An aqueous coating composition having a nonvolatile content of 34.3% was prepared by stirring and mixing 100 parts of the aqueous pigment dispersion obtained in Production Example 1 and 2 parts of water.

Comparative Example 3
An aqueous coating composition having a nonvolatile content of 34.3% was prepared by stirring and mixing 100 parts of the aqueous pigment dispersion obtained in Production Example 3 and 2 parts of water.

<Comparison test>
About the aqueous powder slurry coating composition prepared in the above examples and the aqueous coating compositions prepared in the respective comparative examples, the fluidity test of the coating components after the aqueous medium is evaporated and dried, and the continuous coating formed Visual evaluation was performed on the smoothness.

  First, in the fluidity test, a 4 cm long by 3 cm wide enclosure was made using aluminum foil on a 15 cm long by 5 cm wide tin plate, and an aqueous powder slurry coating composition or aqueous coating composition 2 was formed inside the enclosure. Pour 0.0 parts. Thereafter, the tin plate is kept in a horizontal state for 24 hours and air-dried, and further left in a 50 ° C. constant temperature bath for 24 hours. After that, in the enclosure made of aluminum foil, when the tin plate is set up vertically, the lower part is removed, and the tin plate is fixed so as to maintain an inclination angle of 30 ° with respect to the vertical direction. Was put into the dryer. After 15 minutes, it was taken out from the dryer, and the fluidity of the coating film component at the time of melting was evaluated by the distance (cm) that the coating film component dripped.

Moreover, about the smoothness of the obtained film, it determined visually according to the following evaluation criteria.
Evaluation criteria
○: Excellent smoothness of the film.
Δ: Unevenness is observed in a part of the coating.
X: Concavities and convexities are seen over almost the entire area of the coating.

  Table 1 shows the evaluation results of the fluidity test and the smoothness test for the compositions of Examples and Comparative Examples 1 to 3.

As can be seen from the comparison between Comparative Example 2 and Comparative Example 3, in the comparison of the original base paints, the water-based system is less likely to sagg than the water-dispersed system.
As can be seen from the comparison between Comparative Example 3 and Comparative Example 1, when specific resin particles are added to the film-forming resin aqueous solution in which the pigment is dispersed as the base paint, dripping can be prevented, but the obtained continuous The smoothness of the film is inferior to that in the case of no addition.
From this result, it was expected that the addition of the specific resin particles was similarly expressed in both the water-based system and the water-dispersed system. From the comparison between Comparative Example 1 and Examples, the pigment and the film-forming resin were used as the base paint. Surprisingly, it was found that when specific resin particles were added to the dispersion, the fluidity was improved without impairing the smoothness of the continuous film seen in the water-based system.
It is clear that this is a peculiar result inherent to the water dispersion that cannot be predicted from the result of the water system. This suggests that when resin particles are added to the system, the base is the water-based or water-dispersed system, and the divergence mechanism of the water remaining in the dry coating is different. Yes.

Claims (9)

A pigment (A), a water-insoluble film-forming resin (b1), and resin particles (D) having a smaller average particle diameter made of a resin that is incompatible with the resin (b1) include a surfactant ( An aqueous powder slurry coating composition which is dispersed in an aqueous medium containing E). Colored particles (c1) in which the pigment (A) is coated with a water-insoluble film-forming resin (b1), and resin particles having a smaller average particle diameter (D) made of a resin incompatible with the resin (b1) (D Is dispersed in an aqueous medium containing the surfactant (E). Colored particles (c2) in which the pigment (A) is coated with a self-water dispersible film-forming resin (b2), and resin particles having a smaller average particle diameter made of a resin incompatible with the resin (b2) An aqueous powder slurry coating composition, wherein (D) is dispersed in an aqueous medium. The composition according to any one of claims 1 to 3, wherein the resin particles (D) are crosslinked insoluble and insoluble gel fine particles. The resin constituting the water-insoluble film-forming resin (b1) or the self-water-dispersible film-forming resin (b2) is a polyester resin, and the resin constituting the resin particles (D) is an acrylic resin. The composition as described in any one of 1-4. The composition according to any one of claims 1 to 5, wherein the resin particles (D) are resin particles having a volume average particle diameter of 5 to 200 nm. The composition according to any one of claims 1 to 6, wherein the resin particles (D) are contained in an amount of 0.5 to 10% in terms of mass with respect to the total solid content of the aqueous powder slurry coating composition. . The total solid content is 10 to 60% in terms of mass, The composition according to any one of claims 1 to 7. The composition according to any one of claims 1 to 8, further comprising a curing agent.