JP5036403B2 - Polyvinyl acetal thermosetting resin composition and powder coating - Google Patents

Description

  The present invention relates to a polyvinyl acetal thermosetting resin composition and a powder coating material.

A thermosetting composition in which an epoxy compound is blended in a solvent solution of polyvinyl acetal having a carboxyl group, and further, pigments such as calcium carbonate and clay are blended therein,
In particular, adhesive compositions are known (Patent Document 1, Patent Document 2). However, these are solvent solution-based adhesive compositions, and there is a problem that an environmental load is imposed due to the use of an organic solvent.

  Also known is a powder coating obtained by dry blending resin powder (butyral resin or the like) powder having an average particle diameter of 5 to 50 μm and pigment powder having an average particle diameter of 0.01 to 1.0 μm (Patent Document 3). However, when a normal butyral resin having no functional group is used, the resulting coating film has low solvent resistance.

Japanese Patent Application Laid-Open No. 55-108443 (with claims, upper right column on page 3) JP-A-55-139410 (Claims, page 3, lower right column) JP 2004-43669 A (Claims, [0024])

  The present invention solves the above-mentioned problems of the prior art, and is a thermosetting resin composition capable of imparting a coating film excellent in solvent resistance, and further, excellent in coloration by a pigment and smoothness. An object of the present invention is to provide a thermosetting resin composition, particularly a powder coating, which can form an excellent coating film and has excellent fluidity.

According to the present invention, the object is made of polyvinyl acetal powder having a functional group reactive with a hydroxyl group (A) and the pigment powder (B), and by the thermosetting resin composition which satisfies the following condition reach is made.
(1) The average particle diameter (AD) of (A) is 10 to 250 μm.
(2) The weight ratio of (B) / (A) is 0.1 / 100 to 50/100
(3) The average particle size (BD) of (B) is 2 to 150 μm
(4) | AD-BD | <100 μm

  Still another object of the present invention is to provide a polyvinyl acetal (A) having a functional group that reacts with a hydroxyl group, having at least one functional group selected from a carboxyl group, a carboxylate group, an epoxy group, and an isocyanate group. This is more preferably achieved.

  Furthermore, the object of the present invention is more preferably achieved by a dry blend composition comprising (A) and (B) and a powder coating composition comprising the same.

  The thermosetting resin composition of the present invention is excellent in fluidity and can form a coating film excellent in solvent resistance, smoothness, and colorability. Moreover, the coating film which has these outstanding performances can be formed at low cost only by dry blending (A) and (B).

  Here, “excellent solvent resistance” means that the cured product obtained by heat treatment dissolves the polyvinyl acetal porous powder, such as ethanol, propanol, butanol, methyl ethyl ketone, dioxane, tetrahydrofuran, ethyl acetate, chloroform, dimethyl. It means that it is insoluble or difficult to dissolve in formamide, dimethyl sulfoxide and the like.

In addition, excellent colorability means that there is no or very little color unevenness, and does not mean whether the dispersion state of the pigment in the coating film is uniform. Moreover, being excellent in smoothness means that the coating film thickness is uniform.
Furthermore, the thermosetting resin composition of the present invention, particularly the powder coating, does not cause layer separation between the resin powder and the pigment powder, and the fluidity of the powder coating is excellent. Furthermore, since polyvinyl acetal is excellent in adhesiveness with a base material, it can provide excellent adhesiveness with a base material without any pretreatment with a primer or the like, and has high hardness. A coating film can also be formed.

  In the present invention, the polyvinyl acetal having a functional group that reacts with a hydroxyl group is a functional group that reacts with a hydroxyl group in the polyvinyl acetal, preferably a carboxyl group, a carboxylate group, an epoxy group, or an isocyanate group. Examples thereof include polyvinyl acetal having a functional group. As the polyvinyl acetal having these functional groups, (1) one obtained by acetalizing polyvinyl alcohol having these functional groups, (2) one obtained by acetalizing polyvinyl alcohol with an aldehyde containing these functional groups, (3 ) A compound obtained by reacting a hydroxyl group in polyvinyl acetal with a compound containing these functional groups, (4) A polymer obtained by graft-polymerizing an ethylenic saturated monomer having these functional groups to polyvinyl alcohol, and acetalized. Can be mentioned.

  As the polyvinyl alcohol having a carboxyl group or a carboxylate group (carboxylic acid group, carboxylate group), first, an unsaturated polycarboxylic acid such as an unsaturated monocarboxylic acid or an unsaturated dicarboxylic acid, or a carboxylic acid thereof. Examples thereof include vinyl alcohol copolymers using salts and carboxylic acid esters as comonomer.

As unsaturated monocarboxylic acid or its carboxylate used as a comonomer, (meth) acrylic acid, crotonic acid, oleic acid, and their carboxylates (lithium salt, sodium salt, potassium salt, magnesium salt, calcium) Salt, ammonium salt, etc.). As the unsaturated polyvalent carboxylic acid or its carboxylate used as a comonomer, unsaturated dicarboxylic acid or its salt is particularly suitable. Maleic acid, fumaric acid, itaconic acid, their carboxylate (lithium salt) Sodium salts, potassium salts, magnesium salts, calcium salts, ammonium salts, etc.), unsaturated dicarboxylic acid monoesters (such as alkyl esters such as methyl esters and ethyl esters), unsaturated dicarboxylic acid anhydrides (such as maleic anhydride) Can be mentioned.
The unsaturated monocarboxylic acid ester used as a comonomer includes acrylic acid or a salt thereof, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, acrylic Acrylic acid esters such as i-butyl acid, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid and salts thereof, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate Methacrylic acid esters such as i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate and octadecyl methacrylate.

  As a method of acetalizing polyvinyl alcohol with an aldehyde containing a carboxyl group or a carboxylate group, the polyvinyl alcohol is acetalized with an aldehyde containing a carboxyl group or a carboxylate group, such as glyoxylic acid, phthalaldehyde acid, or terephthalaldehyde acid. The method of doing is mentioned. Two or more kinds of these aldehydes may be used as necessary, and other aldehydes may be used simultaneously.

  In addition, as a method of reacting a hydroxyl group in polyvinyl acetal with a compound containing a functional group reactive with a hydroxyl group, for example, maleic anhydride, itaconic anhydride, succinic anhydride, carboxylic anhydride such as phthalic anhydride , A method of reacting a compound having two or more reactive groups such as itaconic acid and isophorone diisocyanate, a part of the polyfunctional compound is protected with a protecting group, and then reacted with polyvinyl acetal Then, the method by deprotecting, etc. are mentioned.

  In addition, as a method of graft polymerizing an ethylenic saturated monomer having these functional groups to polyvinyl alcohol and acetalizing, ethylenic compounds having a carboxyl group such as (meth) acrylic acid, hydroxyethyl (meth) acrylate, etc. Examples thereof include a method in which an unsaturated monomer is graft-polymerized onto a vinyl alcohol polymer in an aqueous solution of the vinyl alcohol polymer and then acetalized.

  In the present invention, as the polyvinyl acetal having an epoxy group, a polyvinyl acetal using a glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate or the like as a comonomer is preferably used. Can be mentioned. Moreover, as a polyvinyl acetal which has an isocyanate group, what reacted isophorone diisocyanate is mentioned as a suitable thing.

  In the present invention, the content of functional groups such as a carboxyl group, a carboxylate group, an epoxy group, and an isosoanato group is preferably 0.1 to 20 mol% with respect to the ethylene part of the main chain of the polyvinyl acetal, 0.5-10 mol% is optimal.

  The polyvinyl acetal constituting the polyvinyl acetal powder used in the present invention is usually produced using a vinyl alcohol polymer as a raw material. The vinyl alcohol polymer can be obtained by a conventionally known method, that is, by polymerizing a vinyl ester monomer and saponifying the obtained polymer. As a method for polymerizing the vinyl ester monomer, a conventionally known method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. As the polymerization initiator, an azo initiator, a peroxide initiator, a redox initiator, or the like is appropriately selected depending on the polymerization method. As the saponification reaction, a conventionally known alcoholysis or hydrolysis using an alkali catalyst or an acid catalyst can be applied. Among them, a saponification reaction using methanol as a solvent and a caustic soda (NAOH) catalyst is simple and most preferable.

Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, and palmitic acid. Examples thereof include vinyl, vinyl stearate, vinyl oleate, vinyl benzoate, and isopropenyl acetate, and vinyl acetate is particularly preferable.
A vinyl alcohol polymer obtained by saponifying a polymer obtained by polymerizing a vinyl ester monomer differs in the content of each unit depending on the degree of saponification. And vinyl ester units corresponding to the monomer. For example, when vinyl acetate is used as the vinyl ester monomer, the vinyl alcohol polymer obtained by the above production method includes a vinyl alcohol unit and a vinyl acetate unit.

  When the vinyl ester monomer is polymerized, other monomers, for example, α-olefins such as ethylene, propylene, n-butene and isobutylene are copolymerized within the range not detracting from the gist of the present invention. You can also.

  It does not specifically limit as an acid catalyst used for acetalization, Any of an organic acid and an inorganic acid can be used, For example, an acetic acid, paratoluenesulfonic acid, nitric acid, a sulfuric acid, hydrochloric acid etc. are mentioned. Of these, hydrochloric acid, sulfuric acid, and nitric acid are more generally used, and hydrochloric acid is particularly preferably used.

  In the present invention, it is preferable to use polyvinyl acetal acetalized with an aldehyde having 2 to 6 carbon atoms. Examples of the aldehyde having 2 to 6 carbon atoms include acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, 2-ethylbutyraldehyde, and the like. The above may be used in combination. Of these, aldehydes having 4 to 6 carbon atoms, particularly n-butyraldehyde, are preferably used. By using an aldehyde having 2 to 6 carbon atoms, particularly 4 to 6 carbon atoms, a thermosetting resin composition such as a powder coating material which is an object of the present invention can be suitably obtained.

  The degree of acetalization of the polyvinyl acetal used in the present invention is preferably 40 to 85 mol%, and more preferably 50 to 85 mol%. When the degree of acetalization is in this range, the thermosetting resin such as a powder coating, which is excellent in coloration of the coating film, can give a more uniform coating thickness, and has excellent adhesion to the substrate. A composition is obtained. In order to achieve the object of the present invention more suitably, the content of vinyl ester units of polyvinyl acetal is 0.1 to 30 mol%, and the content of vinyl alcohol units is 10 to 50 mol%. Is preferred.

  Next, what is important in the present invention is that the condition (1), that is, the average particle diameter (AD) of the polyvinyl acetal powder (A) satisfies 10 to 250 μm, and this condition is satisfied. Thus, excellent colorability can be imparted to the coating film. The average particle size is preferably 150 μm or less, and optimally 100 μm or less. Moreover, about a lower limit, Preferably it is 20 micrometers or more.

  When the polyvinyl acetal powder satisfies such a specific particle size, it is preferable because it exhibits excellent powder flowability as a powder coating material and can impart excellent colorability and smoothness to the coating film. It is.

  The method for obtaining the average particle diameter of the polyvinyl acetal powder is not particularly limited. For example, an apparatus that can be obtained by measurement by a laser diffraction method and can be used for the measurement is, for example, manufactured by Shimadzu Corporation. It can be measured by a particle size distribution measuring device SALD2200 or the like.

The polyvinyl acetal powder having such a specific particle diameter can be obtained, for example, by the following method.
First, an aqueous solution of vinyl alcohol polymer {concentration 3 to 15% by weight; the concentration is a value calculated by (weight of vinyl alcohol polymer) / (weight of vinyl alcohol polymer aqueous solution) × 100}. Adjust to 80 to 100 ° C., gradually lower the temperature over 10 to 60 minutes, and when the temperature drops to −10 to 30 ° C., add aldehyde and catalyst and keep the temperature constant for 30 to 300 minutes. The reaction proceeds and the temperature is further raised to 40 to 80 ° C. over 30 to 200 minutes, and this temperature is maintained for about 1 to 3 hours. Next, the whole is preferably cooled to room temperature, washed with water, added with a neutralizing agent (alkali, etc.) and dried to obtain the intended polyvinyl acetal powder. Further, although aggregate particles having a maximum particle diameter exceeding 250 μm are hardly generated by the above method, when aggregate particles exceeding the maximum particle diameter of 250 μm are generated, it is preferable to remove them by a filter.

  In the present invention, the degree of polymerization of polyvinyl acetal is preferably 150 to 2000, and more preferably 200 to 1500.

  Next, in the present invention, the pigment powder (B) to be blended with the polyvinyl acetal powder includes titanium oxide, iron oxide, red pepper, carbon black, phthalocyanine green, phthalocyanine blue, diazo yellow, quinacridone, aluminum metal and Examples include mica, light diffusing agents (glass beads, silicone, polymethyl methacrylate, etc.), pigment powders such as barium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, clay, and talc. At least one of these powders It is preferable to use it.

  The pigment powder (B) can also be used as a resin powder (pigment masterbatch) containing a pigment inside or on the surface. The resins used in the pigment masterbatch include polyvinyl acetal resins, poly (meth) acrylate resins, polystyrene resins, styrene- (meth) acrylate copolymer resins, polyester resins, polyamide resins, polycarbonate resins, and polyolefins. Examples thereof include those having good compatibility with the powder (A), such as polyvinyl acetal resin. The pigment master batch is obtained by melt-kneading a pigment and a resin for the master batch and pulverizing them. The pigment is contained in an amount of 0.1 to 99% by weight, preferably 5 to 95% by weight, more preferably 10 to 90% by weight, and most preferably 20 to 80% by weight based on the resin for the masterbatch. The use of a pigment masterbatch is often preferred for achieving the purpose of the present invention.

  Furthermore, what is important in the present invention is that the weight ratio (B) / (A) of the condition (2), that is, the polyvinyl acetal powder (A) and the pigment powder (B) is 0.1 / 100 to 50. / 100 is satisfied. By satisfying these conditions, a coating film having excellent colorability can be obtained, and further excellent fluidity, excellent adhesion to a substrate, and excellent coating film hardness can be imparted. The preferred weight ratio (B) / (A) is 1/100 to 30/100, optimally 1.5 / 100 to 25/100. Here, when the pigment powder (B) is used as a pigment master batch, the weight of the pigment powder (B) does not include the weight of the resin for the master batch.

Furthermore, a preferred embodiment in the present invention is that the condition (3), that is, the average particle diameter (BD) of the pigment powder (B) satisfies 2 to 150 μm. When the pigment is used as a pulverized product of a pigment master batch, it is preferable that the particle size of the pulverized product satisfies an average particle size (BD) of 2 to 150 μm.
When the pigment powder satisfies this condition, excellent colorability can be imparted to the coating film, and further excellent fluidity can be imparted. The average particle size is preferably 130 μm or less, and optimally 100 μm or less. The lower limit of the average particle diameter is preferably 5 μm or more, and optimally 10 μm or more. The maximum particle size is preferably 250 μm or less.

  In addition, a preferred embodiment of the present invention is to satisfy the condition (4), that is, | AD-BD | <100 μm. By satisfying these conditions, layer separation between the resin powder and the pigment powder does not occur, and excellent fluidity is imparted. A more preferable condition is | AD−BD | <80 μm.

  Examples of the method of dry blending the polyvinyl acetal powder (A) and the pigment powder (B) include a method in which both are uniformly mixed, for example, a method using a drive render, a Henschel mixer, a ball mill, or the like. Thus, the powder obtained by dry blending is suitable as a powder coating material.

In the present invention, it is also a preferred aspect to use the polyamide resin powder (C) in combination.
Examples of polyamide-based resins include nylon-6, nylon-6,6, nylon-6 / 6,6 copolymer, nylon-9, nylon-6,10, nylon-11, nylon-12, and the like. 1 type (s) or 2 or more types are used. Among these, nylon-11 and 12 are more preferable. By using these polyamide-based resin powders in combination, it is possible to impart high impact resistance to the coating film, and furthermore, it is possible to obtain a powder coating material that is excellent in fluidity and powder-off properties. Here, “powder-off property” is an evaluation item corresponding to the amount of extra paint adhering to the surface of the base material when the powder paint is applied to the substrate surface, and is determined visually. If the powder coating powder has good powder-off properties, the amount of excess paint is small, or because there is no adhesion of excess paint, coating unevenness of coating is less likely to occur. The amount of the extra paint increases, and coating unevenness of the paint tends to occur.

  More preferably, the polyamide-based resin powder (C) has an average particle size of 10 to 250 μm or less and a maximum particle size of 250 μm. The average particle size of the polyamide resin powder is preferably 150 μm or less, and more preferably 100 μm or less. Moreover, about a lower limit, it is 20 micrometers or more suitably. For example, the polyamide resin powder can be pulverized to a desired particle size. The average particle size and the maximum particle size of the polyamide-based resin powder are determined by the same method as the average particle size and the maximum particle size of the polyvinyl acetal (A) described above.

  In the present invention, when the polyamide resin powder is used in combination, the polyvinyl acetal powder (A) and the polyamide resin powder (C) are in a weight ratio, and (A) / (C) is 20/100 to 100/5. Preferably it is. Preferably it is 50 / 100-100 / 5, More preferably, it is 50 / 100-100 / 10.

  The thermosetting resin composition of the present invention, particularly the powder coating, preferably contains 50% by weight or more of the total of the above (A) and (B), more preferably 70% by weight or more. More preferably, it is 80% or more.

  In the present invention, blending the inorganic fine particles (D) can further improve the fluidity of the powder coating comprising the polyvinyl acetal powder (A) and the pigment powder (B), Furthermore, it is a preferred embodiment because it improves the hardness. Here, the inorganic fine particles (D) are distinguished from pigments, and examples thereof include silica and aluminum oxide.

It is more preferable that the inorganic particles (D) have an average particle diameter of 1 μm or less. The average particle diameter of the inorganic particles (D) is preferably 0.5 μm or less, more preferably 0.1 μm or less. For example, the inorganic fine particles (D) can be pulverized into a desired particle diameter. The average particle size and the maximum particle size of the inorganic fine particles (D) are determined by the same method as the average particle size and the maximum particle size of the polyvinyl acetal (A) described above. The inorganic fine particles (D) are preferably blended in an amount of 0.0001 to 2 parts by weight, more preferably 100 parts by weight of (A) alone or 100 parts by weight of (A) and (C) in total. Is 0.001 to 1 part by weight.
Furthermore, in the present invention, an additive such as a sagging inhibitor, a surface conditioner, an ultraviolet absorber, a light stabilizer, an antioxidant, and a catalyst for promoting crosslinking can be appropriately added as additives.

The thermosetting resin composition of the present invention can be applied to various applications because a cured product having excellent solvent resistance can be imparted by heat treatment (about 100 to 300 ° C.). For example, it can be applied to powder coatings, ceramic binders, photosensitive material binders, ink binders, inorganic material binders, glass films for automobiles or buildings, and among these, it is particularly suitable as a powder coating material.
When used for powder coating, it can be used in various powder coating methods. Examples of the powder coating method include a fluid dipping method, an electrostatic coating method, and a thermal spraying method. The coating temperature condition varies depending on the coating method and the degree of polymerization of the polyvinyl acetal used, but is preferably about 100 to 300 ° C.

Examples of the base material to be coated with the polyvinyl acetal powder coating of the present invention include metals such as steel pipes, steel plates, baskets, carts, and ceramics, ceramics, glass, plastics, and the like. When powder coating is applied to these metals, the surface of the substrate is degreased, phosphated, or plated as necessary to improve the adhesion to the substrate or the corrosion resistance and appearance of the coating. Alternatively, a primer application treatment such as epoxy resin may be performed.
Moreover, a coating film can also be made into a multilayered structure by apply | coating the powder coating material of this invention on the base material represented by a metal. Here, the multi-layering method is not particularly limited. For example, the method of applying the powder coating of the present invention a plurality of times, the application of the powder coating of the present invention to another powder coating, a predetermined pattern For example, a method of alternately performing a plurality of times, applying a mixture of the powder coating material of the present invention and another powder coating material, and causing phase separation upon melting on the substrate surface due to the difference in affinity between the two. Thus, a method of forming a multi-layered resin layer by a single coating can be used. Among these, the method of applying the powder coating a plurality of times is more preferable because it does not need to consider the affinity between the resins.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. In the following examples, “%” and “part” mean “% by weight” and “part by weight” unless otherwise specified.

Various physical properties of polyvinyl acetal, polyvinyl acetal powder, and pigment powder were measured according to the following methods.
(Vinyl acetate group content of polyvinyl acetal)
It was dissolved in DMSO-d6 at a concentration of 2%, and measured and calculated at 80 ° C. using 1H-NMR (manufactured by JEOL; AL400 type).
(Vinyl alcohol group content of polyvinyl acetal)
It was dissolved in DMSO-d6 at a concentration of 2%, and measured and calculated at 80 ° C. using 1H-NMR (manufactured by JEOL; AL400 type).
(Polyvinyl acetal modified amount of glyoxylic acid, modified amount of maleic anhydride)
It was dissolved in DMSO-d6 at a concentration of 2%, and measured and calculated at 80 ° C. using 1H-NMR (manufactured by JEOL; AL400 type). The amount of modification was calculated relative to the ethylene part of the main chain of polyvinyl butyral.

(Average particle diameter of polyvinyl acetal powder and pigment powder)
It measured using the particle size distribution analyzer SALD2200 by Shimadzu Corporation.
(Moisture content of polyvinyl acetal powder)
{(Weight of water-containing polyvinyl acetal powder−dry weight of polyvinyl acetal powder) / weight of water-containing polyvinyl acetal powder} × 100. Here, the dry weight of the polyvinyl acetal powder is a weight when the polyvinyl acetal powder is dried in a dryer at 105 ° C. for 3 hours.

Example 1
(Preparation of polyvinyl butyral)
In a glass container having an internal volume of 2 liters equipped with a reflux condenser, a thermometer and a squid type stirring blade, 1295 g of ion-exchanged water, itaconic acid-modified polyvinyl alcohol (PVA-1: polymerization degree 600, saponification degree 98 mol%, Then, the whole was heated to 95 ° C. to completely dissolve PVA to form an aqueous PVA solution (concentration 7.5% by weight). The formed PVA aqueous solution was gradually cooled to 10 ° C. over about 30 minutes while continuing to stir at a rotational speed of 120 rpm, and then the aqueous solution was added with 53 g of butyraldehyde and an acid catalyst as a butyralization catalyst at a concentration of 20 The butyralization of PVA was started by adding 90 ml of weight% hydrochloric acid. After butyralization was performed for 150 minutes, the whole was heated to 50 ° C. over 60 minutes, held at 50 ° C. for 120 minutes, and then cooled to room temperature. The resin deposited by cooling is filtered, washed with ion exchange water (100 times the amount of ion exchange water relative to the resin), held at 40 ° C. for 15 hours, and then washed again with 100 times the amount of ion exchange water. After dehydration, it was dried at 40 ° C. under reduced pressure for 18 hours to obtain itaconic acid-modified polyvinyl butyral (PVB-1) powder (water content 1.0%). The resulting powder (PVB-1) had a butyralization degree of 68 mol%, a residual acetyl group (content of vinyl acetate units) of 2 mol%, a modification degree of 1.0 mol%, and a residual hydroxyl group (vinyl alcohol unit). The content of was 29 mol%.

(Preparation of polyvinyl butyral powder)
After drying the itaconic acid-modified polyvinyl butyral powder (PVB-1) obtained as described above, using a wire mesh of 60 mesh (aperture 250 μm), particles of 250 μm or more are removed, and polyvinyl butyral powder having an average particle diameter of 85 μm (A-1) was prepared.
(Preparation of powder paint)
Pigment powder {“Iriodin 100 Silver Pearl” (pearl pigment) manufactured by Merck & Co., Inc. (pearl pigment) (no particles having an average particle size of 35 μm and a particle size of 250 μm or more) 5 to 100 parts of the prepared powder (A-1) The parts were mixed by a drive render to obtain the powder coating material of the present invention.

(Coating of base material using powder paint)
The surface of a 0.8 mm thick × 50 mm × 100 mm stainless steel plate (SAS304) was washed with a detergent to be degreased and sufficiently washed with ion exchange water to obtain a substrate. The above-mentioned powder coating material was applied to the base material by a fluid immersion method. In the fluid immersion, air was blown through a perforated plate into a cylindrical coating chamber (fluid chamber) (height 50 cm, diameter 30 cm) to flow the powder paint. The substrate made of the stainless steel plate is preheated (temperature 230 ° C., 10 minutes), suspended in a fluidized bed of polyvinyl butyral powder, taken out after 10 seconds, and post-heated at 230 ° C. for 10 minutes. To obtain a painted product.

Evaluation of the obtained powder coating material and a coating film was performed in accordance with the following method. The results are shown in Table 1.
(Flowability of polyvinyl butyral powder)
The flowability of the polyvinyl butyral powder in the coating chamber was evaluated by visually observing the state of the upper surface of the powder coating material blown up by the air from the perforated plate. Evaluation was made according to the following criteria. The results are shown in Table 1.
○: Polyvinyl butyral powder flows uniformly.
Δ: The polyvinyl butyral powder flows, but the state is uneven.
X: The whole polyvinyl butyral powder does not flow, and air is ejected from a part of the powder surface.
(Colorability of coating film)
The colorability of the coating film applied to the substrate was visually evaluated according to the following criteria.
○: No unevenness in the colored state.
Δ: Some unevenness is observed.
X: The whole surface is a madara pattern.
(Uniformity of coating thickness)
The uniformity of the thickness of the coating film formed on the surface of the substrate was evaluated according to the following method. The results are shown in Table 1.
For one sample, the thickness of the coating film was measured at five points to determine the average value, and the difference between the maximum value and the minimum value with respect to the average value was expressed in%. The lower the value, the higher the uniformity of the coating thickness.
○: Less than 20% ×: 20% or more (ethanol resistance test of coating film)
The coating film portion of the coated plate was wiped with a cloth moistened with ethanol five times, and the state of the coating film surface was visually evaluated according to the following criteria.
○: No change in coating film surface.
X: The surface of the coating film was dissolved, and there was a change in the coating film (a trace residue, pigment adhesion)

Example 2
(Adjustment of pulverized product)
To 100 parts of the powder (A-1) produced above, 5 parts of pigment {"Toka Carbon # 7100F" (carbon black) manufactured by Tokai Carbon Co., Ltd., average particle size 42 μm} are added and mixed by a drive render. The mixture was kneaded with an extruder, pulverized, and classified with a 60 mesh to obtain a powder coating having an average particle size of 77 μm.
Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 3
(Preparation of resin powder containing pigment in or on the surface)
To 100 parts of polyvinyl acetal (manufactured by Kuraray Europe GmbH: Mowital B30H average particle size 102 μm), 20 parts of “Toka Carbon # 7100F” (carbon black) manufactured by Tokai Carbon Co., Ltd. was added, mixed by a drive renderer, and then an extruder. Kneaded and pulverized, and classified with 60 mesh to obtain a resin powder (MB-1) having an average particle size of 80 μm.
20 parts of resin powder (MB-1) was mixed with 100 parts of powder (A-1) by a drive render to obtain a powder coating material of the present invention.
Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 4
In Example 1, powder coating was performed in the same manner as in Example 1 except that 20 parts of pigment was used instead of 5 parts of pigment. Table 1 shows the evaluation results of the obtained coating film.

Example 5
In Example 1, instead of the pigment “Iriodin 100 Silver Pearl”, a pigment {“Toka Carbon # 7100F” (carbon black) manufactured by Tokai Carbon Co., Ltd., average particle size 42 μm} was used. The powder coating was performed in the same manner as described above. Table 1 shows the evaluation results of the obtained coating film.

Example 6
In Example 1, instead of the pigment “Iriodin 100 Silver Pearl”, the pigment {Moritashita Valve Industrial Co., Ltd. “Valve MR270E” (ferric oxide), average particle size 20 μm} was used. Powder coating was performed in the same manner as in Example 1. Table 1 shows the evaluation results of the obtained coating film.

Example 7
(Preparation of polyvinyl butyral)
In a glass container having an internal volume of 2 liters equipped with a reflux condenser, a thermometer and a squid type stirring blade, 1295 g of ion-exchanged water, itaconic acid-modified polyvinyl alcohol (PVA-1: polymerization degree 600, saponification degree 98 mol%, Then, the whole was heated to 95 ° C. to completely dissolve PVA to form an aqueous PVA solution (concentration 7.5% by weight). The formed PVA aqueous solution was gradually cooled to 10 ° C. over about 30 minutes while continuing to stir at a rotational speed of 120 rpm, and then the aqueous solution was added with 53 g of butyraldehyde and an acid catalyst as a butyralization catalyst at a concentration of 20 The butyralization of PVA was started by adding 90 ml of weight% hydrochloric acid. After butyralization was performed for 150 minutes, the whole was heated to 50 ° C. over 60 minutes, held at 50 ° C. for 120 minutes, and then cooled to room temperature. After filtering the resin deposited by cooling, it was washed with ion-exchanged water (50 times the amount of ion-exchanged water with respect to the resin), then added with 0.3 wt% sodium hydroxide solution for neutralization, and at 40 ° C. After holding for 10 hours, it was washed again with 50 times the amount of ion-exchanged water, dehydrated, dried for 18 hours under reduced pressure at 40 ° C., and itaconic acid-modified polyvinyl butyral (PVB-2) powder (water content) 1.0%). The resulting powder (PVB-2) had a butyralization degree of 68 mol%, a residual acetyl group (content of vinyl acetate units) of 2 mol%, a modification degree of 1.0 mol%, and a residual hydroxyl group (vinyl alcohol unit). The content of was 29 mol%.
A powder (A-2) having an average particle diameter of 90 μm was prepared from the powder (PVB-2) in the same manner as in Example 1. In Example 1, powder coating was performed in the same manner as in Example 1 except that powder (A-2) was used instead of powder (A-1). Table 1 shows the evaluation results of the obtained coating film.

Example 8
In Example 2, a powder coating material having an average particle diameter of 82 μm was obtained in the same manner as in Example 2 except that the powder (A-2) was used instead of the powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 9
In Example 3, powder coating material was obtained in the same manner as in Example 3 except that powder (A-2) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 10
In a glass container having an internal volume of 2 liters equipped with a reflux condenser, a thermometer, and a squid type stirring blade, 1295 g of ion-exchanged water and 105 g of polyvinyl alcohol (PVA-1: polymerization degree 600, saponification degree 98 mol%). The whole was heated to 95 ° C. to completely dissolve PVA, and an aqueous PVA solution (concentration 7.5% by weight) was prepared. The aqueous PVA solution was gradually cooled to 10 ° C. over about 30 minutes while continuing to stir at a rotational speed of 120 rpm. Then, 2.5 g of glyoxylic acid, 58 g of butyraldehyde, and an acid as a butyralization catalyst were added to the aqueous solution. As a catalyst, 90 ml of hydrochloric acid having a concentration of 20% by weight was added to start butyralization of PVA. After butyralization was performed for 150 minutes, the whole was heated to 50 ° C. over 60 minutes, held at 50 ° C. for 120 minutes, and then cooled to room temperature. After filtering the resin deposited by cooling, it was washed with ion-exchanged water (50 times the amount of ion-exchanged water with respect to the resin), then added with 0.3 wt% sodium hydroxide solution for neutralization, and at 40 ° C. After holding for 10 hours, it was washed again with 50 times the amount of ion-exchanged water, dehydrated, dried at 40 ° C. under reduced pressure for 18 hours, and powdered with glyoxylic acid-modified polyvinyl butyral (PVB-3) (containing water) 1.0%). The resulting powder (PVB-3) had a butyralization degree of 68 mol%, a residual acetyl group (content of vinyl acetate units) of 2 mol%, a modification degree of 2.0 mol%, and a residual hydroxyl group (vinyl alcohol unit). The content of was 28 mol%. A glyoxylic acid-modified polyvinyl butyral powder (PVB-3) was prepared from a powder powder (A-3) having an average particle diameter of 75 μm in the same manner as in Example 1.
In Example 1, powder coating was performed in the same manner as in Example 1 except that powder (A-3) was used instead of powder (A-1). Table 1 shows the evaluation results of the obtained coating film.

Example 11
In Example 2, a powder coating material having an average particle diameter of 75 μm was obtained in the same manner as in Example 2 except that the powder (A-3) was used instead of the powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 12
In Example 3, a powder coating material was obtained in the same manner as in Example 3 except that powder (A-3) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 13
(Preparation of polyvinyl butyral porous powder)
In a glass container having an internal volume of 2 liters equipped with a reflux condenser, a thermometer, and a squid type stirring blade, 1295 g of ion-exchanged water and 105 g of polyvinyl alcohol (PVA-1: polymerization degree 600, saponification degree 98 mol%). The whole was heated to 95 ° C. to completely dissolve PVA, and an aqueous PVA solution (concentration 7.5% by weight) was prepared. The aqueous PVA solution was gradually cooled to 10 ° C. over about 30 minutes while continuing to stir at a rotational speed of 120 rpm, and then the aqueous solution was mixed with 58 g of butyraldehyde and a concentration of 20% as an acid catalyst as a butyralization catalyst. 90 ml of% hydrochloric acid was added to start butyralization of PVA. After butyralization was performed for 150 minutes, the whole was heated to 50 ° C. over 60 minutes, held at 50 ° C. for 120 minutes, and then cooled to room temperature. After filtering the resin deposited by cooling, it was washed with ion-exchanged water (50 times the amount of ion-exchanged water with respect to the resin), then added with 0.3 wt% sodium hydroxide solution for neutralization, and at 40 ° C. After holding for 10 hours, it was washed again with 50 times the amount of ion-exchanged water, dehydrated, and dried at 40 ° C. under reduced pressure for 18 hours to obtain a polyvinyl butyral (PVB-4) powder (water content of 1. 0%) was obtained. The resulting PVB-4 had a butyralization degree of 68 mol%, a vinyl acetate group content of 2 mol%, and a vinyl alcohol group content of 30 mol%.

(Production of crosslinkable polyvinyl butyral porous powder)
Into a 2 L separable flask, 950 g of hexane and 50 g of methyl ethyl ketone (MEK) were added, and 200 g of PVB-4 was added and dispersed while stirring (solid content concentration 17%). 14.7 g of maleic anhydride, 3.0 g of triethylamine, and 0.1 g of 4-methoxyphenol were added, and the reaction was performed in a heterogeneous system at 25 ° C. for 5 hours. After the reaction, the product was filtered, and the obtained powder was washed with 2 L of 0.1 mol / L hydrochloric acid aqueous solution, then washed 5 times with 2 L of distilled water, dried, and modified polyvinyl butyral porous powder (water content) 1.2%). The resulting modified polyvinyl butyral porous powder had a butyralization degree of 68 mol%, a residual acetyl group (vinyl acetate unit content) of 2 mol%, a modification degree of 3.5 mol%, and a residual hydroxyl group (vinyl alcohol unit). The content of was 26.5 mol%.
A powder (A-4) having an average particle diameter of 67 μm was prepared from the modified polyvinyl butyral porous powder in the same manner as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the powder (A-4) was used instead of the powder (A-1) in Example 1. The results are shown in Table 1.

Example 14
Example 2 A powder coating material having an average particle diameter of 71 μm was obtained in the same manner as in Example 2 except that powder (A-4) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Example 15
In Example 3, powder coating material was obtained in the same manner as in Example 3 except that powder (A-4) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Comparative Example 1
After drying the polyvinyl butyral porous powder (PVB-4: unmodified) prepared in Example 13, using a 60-mesh (mesh size of 250 μm) wire mesh, 250 μm or more particles were removed, and a powder having an average particle diameter of 72 μm Body (A-5) was prepared. Evaluation was performed in the same manner as in Example 1 except that the powder (A-5) was used instead of the powder (A-1) in Example 1. The results are shown in Table 1.

Comparative Example 2
Example 2 A powder coating material having an average particle diameter of 83 μm was obtained in the same manner as in Example 2 except that powder (A-5) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Comparative Example 3
In Example 3, powder coating material was obtained in the same manner as in Example 3 except that powder (A-5) was used instead of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

Comparative Example 4
In Example 1, powder coating was performed in the same manner as in Example 1 except that 55 parts of pigment was used for 100 parts of powder (A-1). Table 1 shows the evaluation results of the obtained coating film.

Comparative Example 5
In Example 1, powder coating was performed in the same manner as in Example 1 except that 0.05 part of pigment was used with respect to 100 parts of powder (A-1). Table 1 shows the evaluation results of the obtained coating film.

Comparative Example 6
In Example 2, a powder coating material was obtained in the same manner as in Example 2 except that 55 parts of pigment was used with respect to 100 parts of powder (A-1). Powder coating was performed in the same manner as in Example 1 with the obtained powder coating material. Table 1 shows the evaluation results of the obtained coating film.

  The thermosetting resin composition of the present invention can be applied to a wide range of uses because it can impart a coating film excellent in solvent resistance, colorability and the like by heat treatment. For example, it can be applied to powder coatings, ceramic binders, photosensitive material binders, ink binders, inorganic material binders, glass films for automobiles or buildings, and among these, it is particularly suitable as a powder coating material.

Claims (7)

A thermosetting resin composition comprising a polyvinyl acetal powder (A) and a pigment powder (B) having a functional group that reacts with a hydroxyl group, and satisfying the following conditions.
(1) The average particle diameter (AD) of (A) is 10 to 250 μm.
(2) The weight ratio of (B) / (A) is 0.1 / 100 to 50/100
(3) The average particle size (BD) of (B) is 2 to 150 μm
(4) | AD-BD | <100 μm The thermosetting according to claim 1, wherein the polyvinyl acetal (A) having a functional group that reacts with a hydroxyl group is a polyvinyl acetal having at least one functional group selected from a carboxyl group, a carboxylate group, an epoxy group, and an isocyanate group. Resin composition. The thermosetting resin composition according to claim 1 or 2 , wherein the thermosetting resin composition is a dry blend composition of (A) and (B). The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a pulverized product of the melt-kneaded product of (A) and (B) . The thermosetting according to any one of claims 1 to 4 , wherein the polyvinyl acetal constituting (A) is a polyvinyl acetal obtained by acetalizing a vinyl alcohol polymer with an aldehyde having 2 to 6 carbon atoms. Resin composition. Pigment powder (B) is titanium oxide, iron oxide, red iron oxide, carbon black, phthalocyanine green, phthalocyanine blue, diazo yellow, quinacridone, any claims 1-5 is at least one selected from aluminum metal and mica 2. The thermosetting resin composition according to item 1. The powder coating material which consists of a thermosetting resin composition of any one of Claims 1-6 .