JP7473291B2 - Matte paint composition - Google Patents

Description

The present invention relates to a matte paint composition.

Traditionally, the exterior paint films of automobiles and other vehicles have generally had a glossy design, but in recent years, a new design with reduced gloss, known as a matte design, has been attracting attention.

As a means for forming a coating film exhibiting a matte design (hereinafter sometimes referred to as a "matte coating film"), for example, Patent Document 1 describes a low-gloss two-component clear coat that includes a base resin containing a urethane resin, an isocyanate resin that is combined with the base resin immediately before application of the low-gloss two-component clear coat to form a two-component base resin mixture, and a silica-based matting agent.

When repair painting an object with a high-quality paint film, such as an automobile body, it is required that the repair paint film formed by the repair painting has a finished appearance equivalent to that of the existing paint film. In addition, since repair painting is performed on a completed automobile body, it is required that the repair paint film be dried at a low temperature so as not to affect the parts such as the equipment inside the body.

In addition, the painting environment for new construction varies greatly from one repair painting site to another, whereas industrial painting lines are stable within a controlled range. Therefore, the challenge is to create a finished appearance that does not look out of place between the repair paint film and the existing paint film at all repair painting sites.

On the other hand, paint prepared by paint manufacturers generally cannot be used for painting as it is due to its high viscosity, and so paint manufacturers ship it to distributors together with dilution thinner. Painters purchase both products from distributors and mix the paint with dilution thinner to adjust the viscosity and painting workability according to the purpose, and then use it for painting.

In recent years, volatile organic compounds such as toluene and xylene, which have traditionally been used in paints, have become regulated as environmental pollutants, and regulations have been strengthened. Both paints and thinners are required to reduce or essentially not contain these regulated substances.

In particular, when repairing automobile bodies or parts, or painting objects that do not enter a drying oven, the paint film cannot be dried at high temperatures after painting, and the repair matte paint film must reproduce not only the color of the existing paint film, but also the matte feel and its degree, using paints and thinners that are safe for humans and the environment. In the case of new painting, the painting environment is stable within the control range of industrial painting lines, but each repair painting site may be painted outdoors or in a place without a painting booth, and the painting conditions, such as humidity conditions, are not constant, and the painting environment is often different in summer and winter. Compared to when the target parts or bodies are painted entirely on an industrial painting line, the painting environment varies greatly depending on the painting site, so there was a challenge in adjusting the degree of matteness to the surrounding areas to the same level and creating a natural finish.

Patent Document 2 proposes a method for repairing matte paint. This invention does not take into account variations in paint thickness or painting environment, and the gloss of the paint film formed can vary greatly. In other words, gloss stability can be insufficient.

Patent Document 3 proposes a matte paint repair method for repairing paint defects such as bumps that occur in a matte paint film. However, in actual automobile repair sites, it is not always possible to paint with the same paint and in the same environment, and there are cases where the gloss stability is insufficient and the matte feel does not match between the old paint film and the repaired area. In addition, the drying speed is often insufficient, and problems such as sagging can occur.

JP 2012-97260 A Japanese Patent Application Laid-Open No. 10-286520 JP 2007-84726 A

The objective of the present invention is to propose a matte paint composition and a method for repair painting of a painted body that are suitable for forming a repair matte paint film that matches the color and matte feel of the old matte paint film and does not look out of place against the old matte paint film, regardless of the painting environment and does not substantially contain toluene, xylene, etc.

As a result of extensive research, the inventors have discovered that the above problems can be solved.

The present invention includes the following embodiments:
Item 1.
A matte coating composition comprising a base agent (I) and a curing agent (II),
The main component (I) contains a hydroxyl group-containing acrylic resin (A), a matting agent (B) containing silica particles (b1), and an organic solvent (C),
The organic solvent (C) includes an organic solvent (c1) having a solubility in water (20° C.) in the range of 5 to 50 g/100 g and a boiling point of 100 to less than 190° C.;
The content ratio of the silica particles (b1) and the organic solvent (c1) contained in the main agent (I) is
A matte paint composition characterized in that the ratio is within the range of 70/30 to 10/90.

Item 2.
Item 2. The matte coating composition according to item 1, wherein the content of the organic solvent (c1) is within the range of 5 to 55 mass% based on the total mass of all solvents contained in the matte coating composition.

Item 3.
Item 3. The matte coating composition according to item 1 or 2, wherein the hydroxyl-containing acrylic resin (A) has a glass transition temperature of 30° C. or higher.

Item 4.
Item 4. The matte coating composition according to any one of items 1 to 3, wherein the silica particles (b1) are organically treated silica particles (b1').

Item 5.
The content of the silica particles (b1) is within the range of 5 to 40 parts by mass relative to 100 parts by mass of the resin solid content of the hydroxyl group-containing resin (A) contained in the main agent (I). The matte coating composition according to any one of claims 1 to 4.

Item 6.
Item 6. The matte coating composition according to any one of items 1 to 5, wherein the curing agent (II) contains a polyisocyanate compound (D).

Item 7.
Item 7. The matte coating composition according to any one of items 1 to 6, wherein the main component (I) further contains a rheology control agent (E).

Item 8.
Item 8. The matte coating composition according to Item 7, wherein the rheology control agent (E) contains crosslinked polymer fine particles (e1).

Item 9.
9. A method for forming a coating film, comprising coating a substrate with the matte coating composition according to any one of claims 1 to 8 to form an outermost coating film.

Item 10.
A step (1) of applying a primer surfacer to an old coating film or a damaged part of a painted body to form a base coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a clear coating composition onto the colored base coating film obtained in the step (2) and drying the composition to form a clear coating film (III);
A method for repairing a painted body, comprising the steps of: (a) applying a clear paint composition to a matte paint composition according to any one of items 1 to 8;

Item 11.
A step (1) of applying a primer surfacer to an old coating film or a damaged part of a painted body to form a base coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a first clear coating composition (CC1) onto the colored base coating film obtained in the step (2) and drying the composition to form a first clear coating film (III);
A method for repair coating of a coated body, comprising a step (4) of coating a second clear coating composition (CC2) on the first clear coating film obtained in the step (3) to form a second clear coating film (IV),
The second clear paint composition (CC2) is a matte paint composition according to any one of items 1 to 8. A method for repairing a painted body.

The composition of the present invention can form a repair matte coating film that dries quickly regardless of the painting environment, and that matches the color and matte feel of the repair matte coating film and the old matte coating film, making it natural to the old matte coating film. It can also suppress the occurrence of uneven gloss even in the low gloss range of 60° gloss values of 1 to 40, where uneven gloss is particularly noticeable. It can also obtain a coating film that is excellent in gloss stability and matte gloss, even when dried at room temperature or forced drying under relatively mild temperature conditions, which are often used in on-site car repairs, etc.

The following provides a detailed explanation of the matte paint composition of the present invention (hereinafter sometimes abbreviated as "the paint") and the method for forming a multilayer coating film.

The matte coating composition of the present invention comprises a base agent (I) and a curing agent (II),
A matte coating composition comprising a base agent (I) and a curing agent (II),
The main component (I) contains a hydroxyl group-containing acrylic resin (A), a matting agent (B) containing silica particles (b1), and an organic solvent (C). The organic solvent (C) contains an organic solvent (c1) having a solubility in water (20°C) within a specific range and a boiling point within a specific range, and the content ratio of the silica particles (b1) and the organic solvent (c1) contained in the main component (I) is within a range of 70/30 to 10/90. This will be described in detail below.

<Main ingredient (I)>
In the present invention, the hydroxyl-containing acrylic resin (A) contained in the main component (I) reacts with the curing agent (II) described below, and together they become a film-forming component.

Hydroxyl-containing acrylic resin (A)
The hydroxyl-containing acrylic resin (A) can be produced by copolymerizing the hydroxyl-containing polymerizable unsaturated monomer (a1) and the other polymerizable unsaturated monomer (a2) by a known method.

The hydroxyl-containing polymerizable unsaturated monomer (a1) is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated groups in one molecule. Specifically, the hydroxyl-containing polymerizable unsaturated monomer (a1) is preferably a monoester of acrylic acid or methacrylic acid with a dihydric alcohol having 2 to 10 carbon atoms, and examples of the hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Furthermore, examples of the hydroxyl-containing polymerizable unsaturated monomer (a1) include ring-opening polymerization adducts of the hydroxyalkyl (meth)acrylates and lactone compounds such as ε-caprolactone. Specific examples of the ring-opening polymerization adducts include "PLACCEL FA-1", "PLACCEL FA-2", "PLACCEL FA-3", "PLACCEL FA-4", "PLACCEL FA-5", "PLACCEL FM-1", "PLACCEL FM-2", "PLACCEL FM-3", "PLACCEL FM-4", and "PLACCEL FM-5" (all of which are trade names manufactured by Daicel Chemical Industries, Ltd.). These hydroxyl group-containing polymerizable unsaturated monomers (a1) can be used alone or in combination of two or more kinds.

In this specification, "(meth)acrylate" means "acrylate or methacrylate". "(meth)acrylic acid" means "acrylic acid or methacrylic acid". Furthermore, "(meth)acrylamide" means "acrylamide or methacrylamide".

The other polymerizable unsaturated monomers (a2) include the following monomers (a2-1) to (a2-8).

(a2-1) Acid group-containing polymerizable unsaturated monomer:
It is a compound having one or more acid groups and one polymerizable unsaturated group in one molecule, and examples thereof include carboxyl group-containing polymerizable unsaturated monomers such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, and maleic anhydride; sulfonic acid group-containing polymerizable unsaturated monomers such as vinyl sulfonic acid and sulfoethyl (meth)acrylate; and acidic phosphate ester-based polymerizable unsaturated monomers such as 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid phosphate, 2-(meth)acryloyloxy-3-chloropropyl acid phosphate, and 2-methacryloyloxyethylphenyl phosphoric acid.

(a2-2) Monoesterification product of (meth)acrylic acid and a monohydric alcohol having 1 to 20 carbon atoms:
Examples of such acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, "isostearyl acrylate" (product name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate.

(a2-3) Polymerizable unsaturated monomer having an alicyclic hydrocarbon group:
Examples of the acrylate include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, adamantyl (meth)acrylate, 3,5-dimethyladamantyl (meth)acrylate, 3-tetracyclododecyl methacrylate, 4-methylcyclohexylmethyl (meth)acrylate, 4-ethylcyclohexylmethyl (meth)acrylate, 4-methoxycyclohexylmethyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclododecyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate. Among these, from the viewpoints of acid resistance and stain resistance, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferred.

Note that polymerizable unsaturated monomers having both an alicyclic hydrocarbon group and a hydroxyl group are included in the hydroxyl group-containing polymerizable unsaturated monomer (a1).

(a2-4) Aromatic polymerizable unsaturated monomer:
For example, styrene, α-methylstyrene, vinyltoluene, and the like are included.

(a2-5) Glycidyl group-containing polymerizable unsaturated monomer:
It is a compound having one glycidyl group and one polymerizable unsaturated group in one molecule, and specific examples thereof include glycidyl acrylate and glycidyl methacrylate.

(a2-6) Nitrogen-containing polymerizable unsaturated monomer:
Examples include (meth)acrylamide, dimethylacrylamide, N,N-dimethylpropylacrylamide, N-butoxymethylacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, N,N-dimethylaminoethyl (meth)acrylate, vinylpyridine, and vinylimidazole.

(a2-7) Other vinyl compounds:
Examples include vinyl acetate, vinyl propionate, vinyl chloride, and versatic acid vinyl esters such as "Veova 9" and "Veova 10" (trade names, manufactured by HEXION).

(a2-8) Polymerizable unsaturated group-containing nitrile compound:
For example, acrylonitrile, methacrylonitrile, etc. are included.

The above other copolymerizable polymerizable unsaturated monomers can be used alone or in combination of two or more.

The amount of the hydroxyl-containing polymerizable unsaturated monomer (a1) used is preferably 5 to 50 parts by mass, more preferably 10 to 45 parts by mass, and even more preferably 15 to 40 parts by mass, based on 100 parts by mass of the amount of the polymerizable unsaturated monomer used to produce the hydroxyl-containing acrylic resin (A).

When the amount of the hydroxyl group-containing polymerizable unsaturated monomer (a1) used is 15 parts by mass or more, it is preferable because the crosslinking in the cured coating film makes it easier to obtain a predetermined alkali resistance. On the other hand, when the amount is 50 parts by mass or less, the compatibility and/or copolymerization reactivity with other polymerizable unsaturated monomers (a2) is improved, and further the compatibility with other components in the paint is improved, which improves the finished appearance of the coating film, so this is preferable.

In addition, from the viewpoint of the weather resistance, alkali resistance, etc. of the coating film to be formed, it is preferable to use an acid group-containing polymerizable unsaturated monomer (a2-1) as at least one of the other polymerizable unsaturated monomers (a2).

In this case, the amount of the acid group-containing polymerizable unsaturated monomer (a2-1) used is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, based on 100 parts by mass of the amount of the polymerizable unsaturated monomer used to produce the hydroxyl group-containing acrylic resin (A).

In addition, from the viewpoint of the alkali resistance and appearance of the coating film formed, it is preferable to use a polymerizable unsaturated monomer (a2-3) having an alicyclic hydrocarbon group as at least one of the other polymerizable unsaturated monomers (a2).

In this case, the amount of the polymerizable unsaturated monomer (a2-3) having an alicyclic hydrocarbon group used is preferably 1 to 40 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 20 to 40 parts by mass, based on 100 parts by mass of the polymerizable unsaturated monomer used to produce the hydroxyl group-containing acrylic resin (A).

In addition, from the viewpoint of the alkali resistance of the coating film to be formed, it is preferable to use an aromatic polymerizable unsaturated monomer (a2-4) as at least one of the other polymerizable unsaturated monomers (a2).

In this case, the amount of aromatic polymerizable unsaturated monomer (a2-4) used is preferably 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 5 to 30 parts by mass, based on 100 parts by mass of the amount of polymerizable unsaturated monomer used to produce the hydroxyl group-containing acrylic resin (A).

The copolymerization method for obtaining the hydroxyl group-containing acrylic resin (A) by copolymerizing the above polymerizable unsaturated monomers is not particularly limited, and any copolymerization method known per se can be used. Among them, the solution polymerization method in which polymerization is carried out in an organic solvent in the presence of a polymerization initiator can be preferably used.

Examples of organic solvents used in the solution polymerization method include aromatic solvents such as toluene, xylene, and "Swasol 1000" (product name, high boiling point petroleum solvent, manufactured by Cosmo Oil Co., Ltd.); ester solvents such as ethyl acetate, butyl acetate, 3-methoxybutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propyl propionate, butyl propionate, and ethoxyethyl propionate; and ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone.

These organic solvents can be used alone or in combination of two or more. In the present invention, ester-based solvents and ketone-based solvents with a medium to high boiling point of about 100°C to 200°C are used, and butyl acetate is particularly preferred in terms of the solubility of the hydroxyl-containing acrylic resin (A) used in the matte coating composition of the present invention. In addition to these organic solvents, aromatic solvents with a high boiling point can also be used in suitable combinations, but in consideration of the effects on the environment and human body, it is preferable that the solvent is substantially free of toluene and xylene. By substantially free of toluene and xylene, it is preferable that no toluene or xylene is used as an organic solvent during synthesis, or that the amount of toluene or xylene is reduced to less than 0.1 mass% by solvent replacement after synthesis.

Polymerization initiators that can be used in copolymerizing the hydroxyl group-containing acrylic resin (A) include radical polymerization initiators known per se, such as 2,2'-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl peroctoate, and 2,2'-azobis(2-methylbutyronitrile).

The hydroxyl value of the hydroxyl-containing acrylic resin (A) is preferably within the range of 80 to 200 mgKOH/g, and more preferably within the range of 100 to 170 mgKOH/g. If the hydroxyl value is 80 mgKOH/g or more, the crosslinking density is high, making it easier to obtain the desired weather resistance, alkali resistance, and coating appearance. Also, if the hydroxyl value is 200 mgKOH/g or less, the water resistance of the coating film is improved, which is preferable.

The weight average molecular weight of the hydroxyl group-containing acrylic resin (A) is preferably within the range of 2500 to 40,000, and from the viewpoint of high solids content and finish of the paint, is more preferably within the range of 4,000 to 30,000. A weight average molecular weight of 2500 or more is preferable because it is easier to obtain the desired coating film performance such as weather resistance, alkali resistance, and coating film appearance. In addition, a weight average molecular weight of 40,000 or less is preferable because it improves the smoothness of the coating film and improves the finish.

In this specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by a gel permeation chromatograph ("HLC8120GPC" manufactured by Tosoh Corporation) to the weight average molecular weight of polystyrene. Four columns, "TSKgel G-4000HxL", "TSKgel G-3000HxL", "TSKgel G-2500HxL", and "TSKgel G-2000HxL" (all product names manufactured by Tosoh Corporation), were used under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 mL/min, detector: RI. The number average molecular weight is also a value measured under the same conditions as above.

The glass transition temperature of the hydroxyl-containing acrylic resin (A) can usually be adjusted within the range of -40°C to 85°C, but from the viewpoint of drying properties, it is preferable to set it to 30°C or higher, and preferably within the range of 40°C to 85°C. If the glass transition temperature is 30°C or higher, the coating film dries well and the desired coating film hardness is obtained, and if it is 85°C or lower, the coating film surface smoothness is improved, which is preferable.

To obtain an acrylic resin with such a high glass transition temperature, it is desirable to include, as part of the copolymerization components, among other polymerizable unsaturated monomers, a monomer whose homopolymer glass transition temperature is 30°C or higher, preferably within the range of 40 to 130°C, in terms of improving drying properties.

The content of the monomer having a glass transition temperature of 30°C or higher in the homopolymer is preferably 10 parts by mass or more, preferably 30 to 80 parts by mass, and more preferably 40 to 70 parts by mass, based on 100 parts by mass of the polymerizable unsaturated monomer used in the production of the hydroxyl group-containing acrylic resin (A).

In this specification, the glass transition temperature of a monomer refers to the glass transition temperature of the homopolymer of each monomer listed in Polymer Handbook (4th Edition, edited by J. Brandup and E.H. Immergut). For the glass transition temperature of a monomer not listed in the document, the glass transition temperature is the value obtained by synthesizing a homopolymer of the monomer so that the weight average molecular weight is about 50,000 and measuring the glass transition temperature by differential scanning calorimetry.

Specific examples of monomers whose homopolymers have a glass transition temperature of 30°C or higher include styrene, methyl methacrylate, ethyl methacrylate, methacrylates having a branched alkyl group with 3 to 4 carbon atoms, such as i-propyl methacrylate, i-butyl methacrylate, tert-butyl methacrylate, etc., cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, etc., cetyl acrylate (also known as hexadecyl acrylate), benzyl methacrylate, and other (meth)acrylates having a cyclic alkyl structure, as well as isostearyl acrylate, stearyl methacrylate, etc.

The hydroxyl-containing acrylic resin (A) may be used alone or in combination of two or more.

From the viewpoints of weather resistance and drying properties, the content of the hydroxyl-containing acrylic resin (A) contained in the main component (I) is preferably within the range of 50 to 100% by mass, more preferably 70 to 100% by mass, based on the total resin solid content contained in the main component (I).

Matting agent (B)
The matting agent (B) essentially contains silica particles (b1).

By incorporating silica particles (b1) in a specific ratio with the organic solvent (c1) described below, it is possible to obtain a coating film that has excellent matte properties and excellent drying properties regardless of the coating environment.

The shape of the silica particles (b1) is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous particles can be used.

The silica particles (b1) may be untreated particles or may be particles that have been surface-treated with an organic or inorganic compound. Among them, from the viewpoints of alkali resistance, gloss stability, etc., organically treated silica particles (b1') are particularly preferred. Examples of treatments with organic compounds include polyethylene treatment, polyethylene wax treatment, and hydrophobic surface treatment.

Commercially available products that can be used as the silica particles (b1) include, for example, the Sylysia series manufactured by Fuji Silysia Co., Ltd. ("Sylysia 350", "Sylysia 430", "Sylysia 435", "Sylysia 436", "Sylysia 450", etc.), the Sylohobic series ("Sylohobic 100", "Sylohobic 200", "Sylohobic 702", "Sylohobic 4004", etc.), the Sylosphere series ("Sylosphere 1504", "Sylosphere 1510", etc.), the SYLOID series manufactured by Grace Japan Co., Ltd. ("Syloid W300", "Syloid W500", etc.), and the ACEMATT series manufactured by Evonik Degussa Japan Co., Ltd. ("ACEMATT HK460", "ACEMATT HK400", "ACEMATT OK412", "ACEMATT OK520", "ACEMATT OK607", "ACEMATT TS100", "ACEMATT 3200, "ACEMATT 3300", "ACEMATT 3600", etc.), NIPGEL series ("NIPGEL AZ-200", etc.), NIPSIL series ("NIPSIL E-200A", "NIPSIL SS-50B", "NIPSIL SS-178B", etc.) manufactured by Nippon Silica Industries Co., Ltd., MIZUKASIL series ("MIZUKASIL P-73", "MIZUKASIL P-526", etc.) manufactured by Mizusawa Chemicals Co., Ltd., Carplex series ("CARPLEX CS-8", etc.) manufactured by Shionogi & Co., Ltd., AEROSIL series ("AEROSIL 200", "AEROSIL R805" and "AEROSIL R972", etc.), and the Radiolite series manufactured by Showa Chemical Industry Co., Ltd. (Radiolite 100, Radiolite 200, Radiolite 500, Radiolite 500R, Radiolite 500RS, etc.).

The content of the silica particles (b1) is preferably within the range of 5 to 40 parts by mass, more preferably within the range of 7 to 30 parts by mass, and even more preferably within the range of 9 to 25 parts by mass, based on 100 parts by mass of the resin solid content of the hydroxyl group-containing acrylic resin (A) contained in the main component (I).

As the other matting agent, a matting agent known per se that has been conventionally used in paints can be used. Examples of other types of matting agents include inorganic fine particles other than silica particles, resin beads, etc.

Other inorganic particles include, for example, alumina particles, titania particles, zirconia particles, zircon particles, tin oxide particles, magnesia particles, or mixtures thereof.

Examples of the resin beads include PMMA (polymethyl methacrylate) resin beads, MMA-EGDM (ethylene glycol dimethacrylate) copolymer resin beads, nylon resin beads, polytetrafluoroethylene resin beads, polycarbonate resin beads, etc.

Examples of commercially available products that can be used as the above resin beads include the "Techpolymer Series (product name)" manufactured by Sekisui Chemical Industry Co., Ltd., the "Dyneon Series (product name)" manufactured by Sumitomo 3M Limited, and the "Microflat MA Series (product name)" manufactured by Koyo Chemical Co., Ltd.

The total content of the matting agent (B), which is the total mass of the silica particles (b1) and other matting agents, can be appropriately adjusted within the range of 5 to 40 parts by mass based on 100 parts by mass of the resin solids of the hydroxyl-containing acrylic resin (A) contained in the main agent (I). From the viewpoint of the balance between matting properties and smoothness, it is more preferable that it is within the range of 7 to 30 parts by mass, and even more preferable that it is within the range of 10 to 25 parts by mass.

When the content of the matting agent (B) is 5 parts by mass or more, a coating film with suppressed gloss can be formed. When the content of the matting agent (B) is 40 parts by mass or less, a coating film with excellent alkali resistance can be formed.

The matting agent (B) may contain a matting agent other than the silica particles (b1). In that case, from the viewpoint of gloss stability and alkali resistance, the content ratio of the silica particles (b1) to the other matting agent is preferably within a range of 60/40 to 100/0 by mass, more preferably 70/30 to 99/1, and even more preferably 75/25 to 95/5.

When a matting agent other than silica particles (b1) is included, the content is preferably 20 parts by mass or less, more preferably in the range of 1 to 15 parts by mass, based on 100 parts by mass of the total resin solids content of the hydroxyl group-containing acrylic resin (A) contained in the main component (I).

From the viewpoint of the balance between matting properties and smoothness, the average particle size of the matting agent (B) is preferably 1 to 20 μm, more preferably 2 to 15 μm, and even more preferably 3 to 10 μm.

In this specification, the average particle size of the matting agent refers to the D50 value of the particle size distribution measured using a laser scattering method. The D50 value is the particle size at which the cumulative particle size distribution from the small particle size side is 50% of the volume-based particle size distribution. In this specification, the volume-based particle size distribution of the matting agent was measured using a laser diffraction/scattering particle size distribution measuring device "Microtrac MT3300" (product name, manufactured by Nikkiso Co., Ltd.). In this case, as a pretreatment, the matting agent was added to a mixed solvent of acetone and isopropyl alcohol and dispersed by applying ultrasonic waves for 1 minute, and the matting agent concentration was adjusted to a concentration that would result in a predetermined transmittance range set in the device.

From the viewpoint of matting ability, the oil absorption of the matting agent (B) is preferably 100 to 400 mL/100 g, more preferably 100 to 380 mL/100 g, and even more preferably 100 to 360 mL/100 g.

In this specification, the oil absorption of the matting agent is a value measured in accordance with JIS K5101-13-2:2004.

Organic solvent (C)
In the present invention, the organic solvent (C) is desirably an organic solvent that does not adversely affect the drying properties of the formed coating film or the coating environment, and is an organic solvent that can stably disperse the resins in the coating composition of the present invention, particularly the matting agent (B), and can cause the resins to be compatible with each other, and includes organic solvent (c1) having a solubility in water (20°C) in the range of 5 to 50 g/100 g and a boiling point of 100 to less than 190°C.

In particular, in the present invention, the organic solvent (C) contained in the main agent (I) is characterized in that, from the viewpoint of obtaining good dispersibility of silica particles and a good matte appearance, the organic solvent (c1) is contained in a ratio of silica particles (b1) to organic solvent (c1) within the range of 70/30 to 10/90. When the ratio is within the above range, a matte paint composition with excellent gloss stability can be obtained regardless of the painting environment.

By including organic solvent (c1) within the above range, a matte coating film with excellent drying properties and gloss stability can be obtained.

In the present invention, "solubility in water" means the mass (g) of a solvent that can be dissolved in 100 g of water at a measurement temperature of 20°C. Therefore, it is the same value as the mass % of a solvent that can be dissolved in 100 mass % of water.

As for the type of organic solvent (c1), within the above range, it can be appropriately selected from aliphatic hydrocarbon solvents and/or alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents having 9 or more carbon atoms, ester solvents, ketone solvents, ether solvents, alcohol solvents, glycol ester solvents, etc. In addition, taking into consideration the effects on the environment and human body, it is preferable that the total content of toluene and xylene is less than 1 mass% of the total solvents contained in the matte paint composition.

Organic solvent (c1)
Specific examples of such a preferred organic solvent (c1) include:
Cyclohexanone (also known as Anone, boiling point 156°C, [8.7g/100g], no hydroxyl group), methoxypropyl acetate (also known as Propylene glycol monomethyl ether acetate, boiling point 146°C, [19.8g/100g], no hydroxyl group), ethylene glycol monomethyl ether propionate (boiling point 160°C, [18.5g/100g], no hydroxyl group), ethoxypropyl acetate (boiling point 154°C, [9.5g/100g], no hydroxyl group), 3-methoxybutyl acetate (also known as Methoxybutyl acetate, boiling point 171.3°C, [6.5g/10 0 g], no hydroxyl group), 3-methyl-3-methoxybutyl acetate (also known as 3-methoxy-3-methylbutyl acetate, boiling point 188°C, [6.8 g/100 g], no hydroxyl group), dipropylene glycol dimethyl ether (also known as dimethylpropylene diglycol, boiling point 171°C, [37 g/100 g], no hydroxyl group), propylene glycol mono-t-butyl ether (boiling point 151°C, [14.5 g/100 g], hydroxyl group present), propylene glycol monobutyl ether (boiling point 170.2°C, [6.4 g/100 g] hydroxyl group present), etc. Among these, ester-based organic solvents are preferred, and in particular, 3-methoxybutyl acetate and/or 3-methyl-3-methoxybutyl acetate are preferred.

Here, the value in [ ] indicates the solubility in water (20°C), and the value in ( ) indicates whether or not the hydroxyl group is present in the organic solvent molecule.

From the viewpoints of drying properties and gloss stability, the content of organic solvent (c1) is preferably within the range of 5 to 55% by mass relative to the total mass of all solvents contained in the matte paint composition, and from the viewpoints of the balance of matte properties, sagging properties, and drying properties, it is preferably within the range of 10 to 30% by mass.

The organic solvent (C) may contain an organic solvent other than the organic solvent (c1).
Examples of the organic solvent include an organic solvent (c2) having a boiling point of 190° C. or higher, and an organic solvent (c3) other than the organic solvents (c1) and (c2).

Organic solvent (c2) is an organic solvent with a boiling point of 190°C or higher. By using an organic solvent (c2) with a relatively high boiling point in combination, gloss stability may be improved.

Specifically, propylene glycol diacetate (boiling point 190°C), 1,4-butanediol diacetate (boiling point 232°C), 1,3-butylene glycol diacetate (boiling point 232°C), diethylene glycol monoethyl ether acetate (boiling point 217°C), dipropylene glycol methyl ether (boiling point 190°C), diethylene glycol monoethyl ether (boiling point 202°C), dipropylene glycol n-propyl ether (boiling point 212°C), dipropylene glycol n-butyl ether (boiling point 229°C), tripropylene glycol methyl ether (boiling point 242°C), diethylene glycol monobutyl ether (boiling point 231°C), "DBE" (a mixed solvent of dimethyl glutarate, dimethyl succinate and dimethyl adipate, manufactured by DowDuPont) (boiling point 196-225°C), Solvent #150 (boiling point 190-210°C, manufactured by Sankyo Chemical Co., Ltd.), "Swasol 1500" (boiling point 190-210°C [initial distillate 180-185°C], manufactured by Cosmo Oil Co., Ltd.), etc. can be mentioned.

The organic solvent (c2) is less than 30% by mass, preferably in the range of 0.5 to 20% by mass, and particularly preferably in the range of 1 to 10% by mass, based on the total mass of all solvents contained in the matte coating composition, from the viewpoints of drying property and gloss stability.

Other organic solvents (c3)
Examples of organic solvents other than the organic solvent (c1) and the organic solvent (c2) include aliphatic hydrocarbon solvents such as hexane and heptane; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, ethyl acetate, ethyl-3-ethoxypropionate, cyclohexyl acetate, normal butyl propionate (also known as normal butyl propionate), and ethylene glycol monoisobutyl ether acetate; ether solvents such as ethylene glycol monoethyl ether (also known as cellosolve), isopropyl glycol (also known as ethylene glycol monoisopropyl ether), ethylene glycol monobutyl ether, and propylene glycol-n-propyl ether; alcohol solvents such as ethanol, propanol, 2-ethylhexyl alcohol, and 3-methoxy-3-methylbutanol; ketone solvents such as methyl ethyl ketone, methyl pentyl ketone, and methyl isopentyl ketone; aromatic hydrocarbon solvents such as "Swasol 310" and "Swasol 1000" (both manufactured by Cosmo Oil Co., Ltd.); alicyclic hydrocarbon solvents, amide solvents, and the like can be mentioned.

Among these, from the viewpoints of being inexpensive and improving gloss stability and compatibility with other components, it is preferable to use at least one selected from butyl acetate, isobutyl acetate, ethyl acetate, and ethyl-3-ethoxypropionate.

From the viewpoints of drying property and gloss stability, the organic solvent (c3) is preferably contained in an amount of 95 mass% or less, and preferably in the range of 50 to 90 mass%, based on the total mass of all solvents contained in the matte coating composition.

Generally, organic solvents with a boiling point of less than 100°C under normal pressure are called low-boiling solvents, those with a boiling point between 100°C and 150°C are called medium-boiling solvents, and those with a boiling point above 150°C are called high-boiling solvents.

The present invention is believed to be able to obtain a coating film with a good and stable matte appearance with less gloss fluctuation due to coating conditions by containing the organic solvent (c1) with a medium to high boiling point and a specific range of solubility in water (20°C) and silica particles (b1) in the main agent (I) in a specific ratio, which has excellent compatibility with other components, reduces the variation in the coating solid content across the entire coating surface when forming a film, and contributes to the dispersibility of the silica particles (b1).

In addition, by including a specific amount of organic solvent (c1) with a medium to high boiling point and a specific range of solubility in water (20°C), it is possible to obtain a coating film with excellent drying properties and gloss stability, which is particularly suitable for on-site applications such as automobile repair.

The main component (I) may further contain, as necessary, paint additives commonly used in the field of paints, such as resins other than the hydroxyl-containing acrylic resin (A), diluents, curing catalysts, color pigments, luster pigments, extender pigments, pigment dispersants, rheology control agents (E), UV absorbers, light stabilizers, plasticizers, etc.

Examples of resins other than the hydroxyl group-containing acrylic resin (A) include silicone resins, urethane resins, fluororesins, epoxy resins, polyester resins, alkyd resins, and mixtures or modified resins thereof, such as acrylic-modified polyester resins, acrylic silicone resins, acrylic-modified epoxy resins, and epoxy ester resins. These may also have hydroxyl groups. Other examples include acrylic resins that do not contain hydroxyl groups. These may be used alone or in combination of two or more.

When the main component (I) contains other resins, the content of those resins is, for example, preferably less than 30 parts by mass, in the range of 1 to 10 parts by mass, and more preferably in the range of 1.5 to 8 parts by mass, based on 100 parts by mass of the total resin solids content of the hydroxyl group-containing acrylic resin (A) contained in the main component (I).

Rheology control agent (E)
By blending the rheology control agent (E), the present matte coating composition can be given thixotropy, and thus when high shear stress is applied, such as during spray coating, the viscosity is sufficiently reduced to facilitate spray coating work, while when low shear stress is applied after application to the substrate, the apparent viscosity can be increased. As a result, when applying to a vertical substrate or when baking after application to that portion, the occurrence of coating film defects such as sagging and repelling can be prevented, and a coating film with a good matte appearance can be formed. Examples of such rheology control agents (E) include crosslinked polymer fine particles and polyurea compounds.

The crosslinked polymer microparticles are internally crosslinked particulate polymers that are almost or completely insoluble in organic solvents and can be stably dispersed in the composition.

As the crosslinked polymer microparticles, known intramolecularly crosslinked microparticle polymers obtained by aqueous emulsion or aqueous suspension polymerization or nonaqueous dispersion polymerization can be used.

Among these, the particulate polymer having an intramolecular crosslinked structure obtained by the aqueous emulsion or aqueous suspension polymerization method can be made into a solid form by separating it by physical or chemical means such as evaporation or azeotropy of water, or precipitation or aggregation of the polymer (particles). Alternatively, when carrying out such physical or chemical means, the medium of the desired crosslinked polymer particulates may be directly replaced from water to other resins, organic solvents, etc.

As the crosslinked polymer microparticles, for example, crosslinked polymer microparticles obtained by emulsion polymerization of a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule and other radically polymerizable unsaturated monomers in the presence of a reactive emulsifier containing an allyl group in the molecule, as disclosed in JP-A-3-66770, can be suitably used.

These crosslinkable polymer microparticles have a high crosslink density and are substantially non-swelling and non-fusible even in organic solvents with high polymer dissolving power, such as toluene and ethyl acetate. When added to the present coating composition containing an organic solvent, it is possible to obtain a solution (dispersion) with a high resin content, i.e., a high solids content, without causing a substantial increase in the viscosity of the present coating composition.

The crosslinked polymer microparticles generally have an average particle size within the range of about 0.01 to about 2 μm, and particularly preferably 0.05 to 0.5 μm. Microparticles with particle sizes within this range provide a coating film with anti-sagging effect and a stable matte appearance. Here, the average particle size of the crosslinked polymer microparticles is a volume-based value measured at 20°C using a [submicron particle size distribution measuring device "COULTER N4 type" (manufactured by Beckman Coulter)] (hereinafter the same) after diluting appropriately with deionized water or the like in the usual manner, and performing monodispersion mode analysis.

Also, as the rheology control agent (E), for example, as described in JP-B-7-81099, a solid particulate polyurea compound consisting of a reaction product of an isocyanurate trimer obtained from a diisocyanate compound having 3 to 20, preferably 5 to 14, more preferably 8 to 12 carbon atoms, and an amine compound having at least one primary amino group can be used.

When the main component (I) contains a rheology control agent (E), the content is, for example, preferably within the range of 1 to 10 parts by mass, and more preferably within the range of 1.5 to 8 parts by mass, based on 100 parts by mass of the total resin solids content of the hydroxyl group-containing acrylic resin (A) contained in the main component (I).

Curing catalyst Examples of the curing catalyst include organometallic compounds such as tin octylate, dibutyltin diacetate, dibutyltin di(2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di(2-ethylhexanoate), dibutyltin oxide, dibutyltin sulfide, dioctyltin oxide, dibutyltin fatty acid salts, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, zinc fatty acids, bismuth octanoate, bismuth 2-ethylhexanoate, bismuth oleate, bismuth neodecanoate, bismuth versatate, bismuth naphthenate, cobalt naphthenate, calcium octylate, copper naphthenate, and tetra(2-ethylhexyl)titanate; tertiary amines, etc. These can be used alone or in combination of two or more.

When the matte coating composition of the present invention contains a curing catalyst, the content of the curing catalyst is preferably within the range of 0.05 to 10 parts by mass, more preferably within the range of 0.1 to 5 parts by mass, and even more preferably within the range of 0.2 to 3 parts by mass, based on 100 parts by mass of the resin solids in the matte coating composition.

Examples of color pigments include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, etc.

Examples of luster pigments include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flake, aluminum oxide, mica, aluminum oxide coated with titanium oxide and/or iron oxide, and mica coated with titanium oxide and/or iron oxide.

Examples of extender pigments include talc, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, alumina white, etc.

The above pigments can be used alone or in combination of two or more.

When the matte paint composition of the present invention is used as a clear paint and contains a pigment, the content of the pigment is preferably an amount that does not impair the transparency of the resulting coating film. For example, based on 100 parts by mass of the resin solids in the matte paint composition, the content of the pigment is usually preferably within the range of 0.1 to 20 parts by mass, more preferably within the range of 0.3 to 10 parts by mass, and even more preferably within the range of 0.5 to 5 parts by mass.

When the matte paint composition of the present invention is used as a colored paint and contains a pigment, the content of the pigment is usually preferably within the range of 1 to 200 parts by mass, more preferably within the range of 2 to 100 parts by mass, and even more preferably within the range of 5 to 50 parts by mass, based on 100 parts by mass of the resin solids in the matte paint composition.

As the ultraviolet absorbing agent, conventionally known ones can be used, for example, ultraviolet absorbing agents such as benzotriazole-based absorbers, triazine-based absorbers, salicylic acid derivative-based absorbers, and benzophenone-based absorbers. These can be used alone or in combination of two or more kinds.

When the matte coating composition of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably within the range of 0.1 to 10 parts by mass, more preferably within the range of 0.2 to 5 parts by mass, and even more preferably within the range of 0.3 to 2 parts by mass, based on 100 parts by mass of the resin solids in the matte coating composition.

Light stabilizers that have been known in the art can be used, such as hindered amine light stabilizers.

When the matte coating composition of the present invention contains a light stabilizer, the content of the light stabilizer is preferably within the range of 0.1 to 10 parts by mass, more preferably within the range of 0.2 to 5 parts by mass, and even more preferably within the range of 0.3 to 2 parts by mass, based on 100 parts by mass of the resin solids in the matte coating composition.
Curing agent (II)
The curing agent (II) used in the present invention contains a curing agent component, and the curing agent component contains a polyisocyanate compound (D).

Polyisocyanate Compound (D)
The polyisocyanate compound (D) is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.

Examples of the aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine aliphatic diisocyanates such as 2,6-diisocyanatohexanoate 2-isocyanatoethyl, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, alicyclic diisocyanates such as 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylenebis(4,1-cyclohexanediyl)diisocyanate (common name: hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2-isocyanatopropyl ... , 5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-isocyanatopropyl)-bicyclo(2.2.1)heptane, Examples of alicyclic triisocyanates include 2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane.

Examples of the araliphatic polyisocyanate include araliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; and araliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

Examples of the aromatic polyisocyanate include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, etc.; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, etc.; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate, etc.

In addition, examples of derivatives of the polyisocyanates include dimers, trimers, biurets, allophanates, uretdione, uretoimine, isocyanurates, oxadiazinetriones, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, etc. of the above-mentioned polyisocyanates.

The polyisocyanates and derivatives thereof may be used alone or in combination of two or more. Among these polyisocyanates, aliphatic diisocyanates and their derivatives are preferably used from the viewpoint of weather resistance and the like.
The polyisocyanate compound (D) may be a prepolymer obtained by reacting the polyisocyanate compound or its derivative with a compound having an active hydrogen group, such as a hydroxyl group or an amino group, which can react with the polyisocyanate under an isocyanate group excess condition. Examples of the compound that can react with the polyisocyanate include polyhydric alcohols, low molecular weight polyester resins, amines, water, etc.

The polyisocyanate compounds (D) may be used alone or in combination of two or more kinds.

When two or more polyisocyanate compounds are used as the curing agent (II), it is preferable to adjust the amount of the polyisocyanate compounds so that the isocyanate group content in the curing agent (II) is, on average, 5% by mass or more, and preferably within the range of 8 to 25% by mass, from the viewpoints of storage stability and weather resistance.

The content of the polyisocyanate compound (D) in the above matte coating composition can be adjusted appropriately so that the equivalent ratio (NCO/OH) between the isocyanate groups of the polyisocyanate compound (D) and the hydroxyl groups of the hydroxyl-containing acrylic resin (A) is generally within the range of 0.5 to 5.0, but from the viewpoint of curability and weather resistance, it is preferably within the range of 1.1 to 3.0, and more preferably within the range of 1.2 to 2.0. By ensuring that the equivalent ratio (NCO/OH) is within the above preferred range, there is an advantage that the curing reactivity of the matte coating composition can be ensured within a good range. Note that all of the above equivalent ratios are calculated based on solid content.

The curing agent (II) used in the present invention may contain an organic solvent (C).

As the organic solvent (C), the organic solvents listed above in the section on organic solvent (C) can be suitably used.

Among the organic solvents contained in the curing agent (II), organic solvents without hydroxyl groups are preferred, and from the viewpoints of drying speed and finish adjustment such as obtaining a desired matte appearance, and miscibility with the main agent (I), at least one organic solvent selected from esters, glycols, ketones, and hydrocarbons without hydroxyl groups is preferred. The curing agent is particularly preferred because it is prepared with the above organic solvent without hydroxyl groups, which provides an excellent balance between storage stability and miscibility between the hydroxyl-containing acrylic resin (A) and the curing agent.

The solid content of the curing agent (II) can be appropriately adjusted within the range of 10 to 100% by mass, preferably within the range of 30 to 99% by mass.

In addition, the curing agent (II) may be blended with paint additives such as surface conditioners, defoamers, curing catalysts, UV absorbers, light stabilizers, dehydrating agents, etc., as necessary, to the extent that the storage properties and drying properties of the curing agent (II) are not impaired. As a curing component, other crosslinking components capable of crosslinking with the hydroxyl groups of the hydroxyl-containing acrylic resin (A) other than the polyisocyanate compound may be included, but from the viewpoint of low-temperature curing, it is preferable that the polyisocyanate compound (D) is adjusted to 70 parts by mass or more, and particularly 80 to 100 parts by mass, per 100 parts by mass of the resin solid content in the curing agent.

Preparation of Matte Paint Composition The coating film obtained by applying the matte paint composition of the present invention has a matte property.

In this specification, having a matte finish means that the 60° specular gloss value of the formed coating film measured according to JIS K 5600-4-7:1999 is less than 75, preferably less than 70, and more preferably less than 65.

The matte coating composition of the present invention is preferably an organic solvent-based coating composition. In this specification, an organic solvent-based coating composition is a coating that does not substantially contain water as a solvent.

When applying the matte paint composition of the present invention, it is preferable to use a diluent as necessary to adjust the solid content to 15% by mass or more, particularly preferably within the range of 35 to 60% by mass, and the viscosity to within the range of 5 to 30 seconds/Ford cup #4/20°C, in terms of paint workability and reducing the amount of organic solvent discharged.

The diluent may be any of the organic solvents listed in the section on organic solvent (C) above, but it is desirable that the diluent contains organic solvent (c1) whose solubility in water (20°C) is in the range of 5 to 50 g/100 g and whose boiling point is less than 100 to 190°C, and that the content of organic solvent (c1) is adjusted to be in the range of 5 to 55 mass% relative to the total mass of all solvents contained in the matte coating composition.

From the viewpoint of storage stability, the matte coating composition of the present invention is a two-part coating composition in which the main component (I) containing the hydroxyl-containing acrylic resin (A) and the matte agent (B) is separated from the hardener (II), and it is preferable to mix the two immediately before use.

Coating film forming method The substrate to which the matte coating composition of the present invention is applied is not particularly limited, but includes substrates having a base material such as metal or plastic, and the substrate may be painted. The substrate may also be a molded product containing the above-mentioned base material. The applications of these substrates include, for example, automobiles, motorcycles, and other automobile vehicles or their parts, large vehicles such as trucks, buses, construction machines, and railroad cars, and their parts.

The surfaces of the above-mentioned metal substrates or plastic substrates or molded products thereof may be degreased and/or surface-treated.

The object to be coated may also be a coating film (old coating film) already formed on the surface to be coated or a damaged part of a coated body.

The method for applying the matte coating composition of the present invention is not particularly limited, and examples thereof include air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, and other coating methods, by which a wet coating film can be formed. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating or rotary atomization coating is particularly preferred.

When air spray coating, airless spray coating, or rotary atomization coating is performed, it is preferable to adjust the viscosity of the coating composition of the present invention appropriately using a solvent so that it is within a viscosity range suitable for such coating, usually a viscosity range of about 15 to 60 seconds at 20°C using a Ford Cup No. 4 viscometer.

There are no particular limitations on the method of drying the matte coating composition of the present invention. A coating film can be obtained by drying at room temperature, but there is no problem with heat drying or forced drying depending on the coating environment, etc. When heat drying is used, drying can be performed under relatively mild drying conditions, within the range of 25 to 80°C, preferably 40 to 60°C. There are no particular limitations on the time for heat drying, and it is suitable, for example, to be within the range of 10 to 60 minutes, preferably 15 to 30 minutes.

If necessary, air drying may be performed using a blower or the like. For room temperature drying, a coating film can be obtained by drying in an environment of, for example, 5 to 45°C. The relative humidity (hereinafter sometimes abbreviated as RH) during coating is preferably 80% or less, and particularly preferably 70% or less.

In the case of forced drying, from the perspective of the finish, it may be acceptable to set (stand still) the product at room temperature for 2 to 30 minutes before heat drying.

The film thickness can be adjusted as appropriate depending on the condition of the surface to be coated, but generally, a dry film thickness of 5 to 150 μm, 10 to 100 μm, and especially 7 to 60 μm is appropriate.

The matte coating composition of the present invention is extremely excellent in drying property and gloss stability, and therefore, for example,
By applying the matte coating composition of the present invention to a substrate to form a coating film on the outermost surface, a matte appearance can be imparted to the substrate while taking advantage of its design. In particular, the present coating composition has excellent drying properties, does not contain toluene or xylene, and is a coating composition that is considerate of the human body and the environment, and is therefore particularly suitable for use as a coating for automobile repairs.

In addition, since drying is possible at room temperature or under mild drying conditions, it can also be suitably used as a paint for large vehicles.
Repair painting method for painted bodies The present paint can be applied as a matte paint composition particularly to old paint films or damaged parts of painted bodies, and can be suitably used as a repair painting method for painted bodies.

For example, the following methods I and II can be suitably used.

Method I
A step (1) of applying a primer surfacer to an old coating film or a damaged part of a painted body to form a base coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a clear coating composition onto the colored base coating film obtained in the step (2) and drying the composition to form a clear coating film (III);
A method for repair coating of a coated body, comprising the steps of:

Method II
A step (1) of applying a primer surfacer to a damaged portion of a painted body to form a base treatment coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a first clear coating composition (CC1) onto the colored base coating film obtained in the step (2) and drying the composition to form a first clear coating film (III);
A method for repair coating of a coated body, comprising a step (4) of coating a second clear coating composition (CC2) on the first clear coating film obtained in the step (3) to form a second clear coating film (IV),
A method for repair painting of a painted body, wherein the second clear paint composition (CC2) is the matte paint composition of the present invention.

In the above-mentioned method I or method II, the old coating film or the painted body can be a known matte coating film, preferably a multi-layer coating film including a matte clear coating film.

In the above methods I and II, examples of the old coating film or painted body as the substrate include a coating film or painted body in which a cured undercoat coating film made of an electrodeposition paint is formed on a metal substrate; a coating film or painted body in which a cured intermediate coating film is formed on the cured undercoat coating film; a coating film or painted body in which an uncured intermediate coating film is formed on the cured undercoat coating film; a coating film or painted body in which a cured undercoat coating film made of a primer paint containing a polyolefin resin is formed on a plastic substrate; a coating film or painted body in which an uncured undercoat coating film made of a primer paint containing a polyolefin resin is formed on a plastic substrate, and the like.

In addition, the old paint film or damaged area of the painted body to be painted can be cleaned and sanded with sandpaper in advance, and the surface to be painted can be primed with a putty composition, etc., if necessary.

By applying a primer surfacer or other undercoat treatment agent to form a undercoat treatment film, it is possible to protect exposed damaged areas of the painted body or the uneven surface of the base material, and also improve adhesion to the colored base coating film described below.

The primer surfacer can be applied by a conventional method such as spray coating. In addition, when applying a putty composition, it can be applied using, for example, a spatula. Before applying or filling the base treatment agent, the damaged area of the coated body and its surroundings may be cleaned or sanded with sandpaper.

The putty or primer surfacer may be dried. Examples of the drying method include room temperature drying or forced drying. This drying process allows the coating to harden to the inside. In the case of room temperature drying, specifically, it is left to stand at room temperature for 5 hours or more, or in the case of forced drying, it can be heated at 40 to 120°C for 5 to 60 minutes. In the case of forced drying, it can be set (left to stand) at room temperature for 2 to 30 minutes before heat hardening in terms of the finish. For example, a blower or the like can be used for drying.

The thickness of the resulting primer surfacer is usually 8 to 500 μm, preferably 10 to 150 μm, on a dry film thickness basis, taking into consideration subsequent polishing.

For example, waterproof paper or sandpaper can be used for polishing. It is also possible to use waterproof paper for wet sanding, or to polish with a coarse polishing compound and then a fine polishing compound.

In addition, in the above methods I and II, one or more types of paint compositions may be used as the colored base paint composition, and one or more layers of the colored base paint film may be formed. After the colored base paint composition is applied, the coating film may be preheated, for example, at 40 to 90°C for about 3 to 30 minutes in order to promote the evaporation of the solvent in the colored base paint composition without curing the coating film.

Colored Base Coating Composition As the colored base coating composition, for example, a water-based coating material or an organic solvent-based coating material can be used. Among them, from the viewpoint of reducing the environmental load, a water-based coating material is preferred.

In this specification, water-based paint generally means paint in which a film-forming resin, pigment, etc. are dispersed and/or dissolved in water or a medium whose main component is water (aqueous medium).

For example, when the substrate is an automobile body, a colored base coating composition that is known per se and is commonly used in painting automobile bodies can be used.

Specifically, the colored base coating composition can be prepared by dissolving or dispersing a base resin, such as an acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin, having a crosslinkable functional group such as a carboxyl group or a hydroxyl group, an amino resin, such as a melamine resin or a urea resin, or a crosslinking agent, such as a polyisocyanate compound which may be blocked, in water or an organic solvent together with a pigment, a thickener, and other optional components. In particular, a thermosetting water-based coating can be preferably used, which uses at least one resin selected from the group consisting of a hydroxyl-containing polyester resin and a hydroxyl-containing acrylic resin as the base resin, and at least one resin selected from the group consisting of a melamine resin and a polyisocyanate compound which may be blocked as the curing agent.

The above pigments may be color pigments, extender pigments, or luster pigments, each of which may be used alone or in combination of two or more.

Examples of color pigments include titanium oxide, zinc oxide, carbon black (including conductive carbon black), molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, etc.

Examples of extender pigments include talc, clay, kaolin, baryta, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white.

Examples of luster pigments include non-leafing or leafing aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flakes, graphite flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, and mica coated with titanium oxide or iron oxide. Of these, it is preferable to use at least one luster pigment selected from aluminum, mica, aluminum oxide coated with titanium oxide or iron oxide, and mica coated with titanium oxide or iron oxide. These may be used alone or in combination of two or more.

The solid content of the colored base coating composition can usually be 60% by mass or less, and the solid content at the time of application can usually be 10 to 50% by mass.

Additives that can be added to the colored base paint composition include general paint additives such as ultraviolet absorbers, light stabilizers, antioxidants, surface conditioners, and defoamers, including those exemplified for the paint composition of the present invention.

The method for applying the colored base coating composition is not particularly limited, and examples include air spray, airless spray, rotary atomization, brush, roller, hand gun, all-purpose gun, immersion, roll coater, curtain flow coater, roller curtain coater, die coater, etc., and can be appropriately selected depending on the application of the substrate, etc., and multiple coats may be applied.

After the colored base coating composition is applied, it may be dried, for example by room temperature drying or forced drying. In the case of room temperature drying, specifically, it is left to stand at room temperature (for example, 10 to less than 40°C) for 5 hours or more, or in the case of forced drying, it can be heated at 40 to 120°C for 5 to 60 minutes. In the case of forced drying, from the viewpoint of the finish, it can be set (left to stand) at room temperature for 2 to 30 minutes before heat curing. For example, a blower or the like may be used for drying.

From the standpoint of shortening the process, it is preferable to overcoat the clear paint composition (CC1) and/or the matte paint composition of the present invention while the colored base coating is in an uncured state.

Clear coating composition (CC1)
As the clear coating composition (CC1), for example when the substrate is an automobile body, a per se known composition that is usually used in painting automobile bodies can be used.

Specifically, the clear coating composition (CC1) can be prepared by dissolving or dispersing a base resin, such as an acrylic resin, polyester resin, or urethane resin, having a crosslinkable functional group such as a carboxyl group or a hydroxyl group, an amino resin, such as a melamine resin or a urea resin, or a crosslinking agent, such as a polyisocyanate compound which may be blocked, in an organic solvent together with other optional components. In particular, a heat-curable solvent-based coating can be used that uses at least one resin selected from the group consisting of a hydroxyl-containing polyester resin and a hydroxyl-containing acrylic resin as the base resin, and at least one resin selected from the group consisting of a melamine resin and a polyisocyanate compound which may be blocked as the curing agent.

The solid content of the above clear coating composition (CC1) can usually be 60% by mass or less, and the solid content at the time of application can usually be 30 to 50% by mass.

Optional components that can be added to the clear paint composition (CC1) include pigments such as color pigments, extender pigments, and luster pigments, including those exemplified for the paint composition of the present invention, as well as general paint additives such as UV absorbers, light stabilizers, antioxidants, surface conditioners, and defoamers.

The present invention will be described in more detail below with reference to Production Examples, Examples and Comparative Examples.
The present invention is not limited thereto. In each example, "parts" and "%" are
Unless otherwise specified, the amounts are based on mass. The coating thickness is based on the cured coating. Furthermore, the amounts in the table are based on the mass of the solid content.
Production of Hydroxyl-Containing Acrylic Resin (A) Production Example 1
Into a four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet, 45 parts of butyl acetate (boiling point 126° C., water solubility (20° C.) 0.7 g/100 g) was charged as an organic solvent during production, and the temperature was raised to 120° C. under nitrogen gas aeration. After the temperature reached 120° C., the nitrogen gas aeration was stopped, and a monomer mixture having the composition of the monomers and polymerization initiator shown in Table 1 below was added dropwise over 4 hours.
Next, the mixture was aged for 1 hour at 120°C while passing nitrogen gas through it, and then a mixture of 0.5 parts of 2,2'-azobisisobutyronitrile and 5 parts of butyl acetate was added dropwise over 1 hour, followed by aging for 1 hour at about 120°C, and then diluted with the same organic solvent as in the production to a solid content of 50% to obtain a hydroxyl-containing acrylic resin (A1-1) solution. The hydroxyl value based on the solid content of the obtained acrylic resin was 82 mgKOH/g, the weight average molecular weight was about 17000, and the glass transition temperature was 62°C.

Production Examples 2 to 4
Hydroxyl-containing acrylic resins (A1-2) to (A1-4) were produced in the same manner as in Production Example 1, except that the monomer compositions and organic solvents used in production were as shown in Table 1 below. The hydroxyl value, weight average molecular weight, and glass transition temperature based on the solid content of each of the resulting hydroxyl-containing acrylic resins are also shown in Table 1.

Production Example 5 Production of crosslinked polymer microparticles In a reaction vessel equipped with a thermometer, a thermostat, a stirring device, a reflux condenser and a dropping device, 355 parts of deionized water and 2 parts of "Latemul S-120A" (trade name, manufactured by Kao Corporation, sulfosuccinic acid-based allyl group-containing anionic reactive emulsifier, 50% aqueous solution) were charged and heated to 90°C with stirring. To this, 20% of an aqueous solution in which 1.25 parts of a water-soluble azoamide polymerization initiator "VA-086" (trade name, manufactured by Wako Pure Chemical Industries, Ltd., 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide]) was dissolved in 50 parts of deionized water was added. After 15 minutes, 5% of a monomer mixture consisting of 30 parts of styrene, 40 parts of methyl methacrylate, 15 parts of n-butyl acrylate, 5 parts of 2-hydroxyethyl acrylate and 10 parts of 1,6-hexanediol diacrylate was added. Then, after stirring for another 30 minutes, the remaining monomer mixture and the polymerization initiator aqueous solution were started to be dropped. The monomer mixture was dropped for 3 hours, and the polymerization initiator aqueous solution was dropped for 3.5 hours, during which the polymerization temperature was kept at 90°C. After the polymerization initiator aqueous solution was dropped, the mixture was heated for 30 minutes and kept at 90°C, and then cooled to room temperature and taken out using a filter cloth to obtain an aqueous dispersion of polymer fine particles with a solid content of 20%. This aqueous dispersion was dried in an electric hot air dryer at 60°C on a stainless steel tray to obtain crosslinked polymer fine particles (P1) as a solid resin. The average particle size of the obtained crosslinked polymer fine particles (P1) was 90 nm, the acid value was less than 0.5 mgKOH/g, and the hydroxyl value was 24 mgKOH/g.

Production Example 6 Curing agent (II-1)
100 parts of "Sumidur N3300" (product name, manufactured by Sumika Covestro Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate, solid content 100%, NCO content 21.8% by mass) without any organic solvent was used as the curing agent (II-1).

Production Examples 7 and 8
The organic solvents used in Production Example 4 were those shown in Table 2, and the mixture was stirred for 30 minutes to prepare hardeners (II-2) and (II-3) with solid contents of 40%.

(Example 1) Preparation of Matte Paint Composition No. 1 As the main agent (I), 200 parts (100 parts solids) of the hydroxyl-containing acrylic resin (A-1) obtained in Production Example 1, 20 parts (20 parts solids) of the matte agent (B-1), 35 parts of the organic solvent (c1)-1, 15 parts of the organic solvent (c3)-1, and other components shown in Table 3-1 were mixed and stirred using a rotary blade mixer to prepare the main agent (I). Then, the curing agent (II-1) was mixed with the main agent in an amount such that the NCO/OH ratio was 1.3, and the matte paint composition (1) was obtained. At this time, the viscosity at 20 ° C. according to Ford Cup No. 4 was 15 seconds.

(Preparation of painted boards)
The center of the coated object 1 was polished with #240 paper, and on the coated plate with the steel plate partially exposed, "COODE Filler Dark Gray (L20) Base" (trade name, Kansai Paint Co., Ltd., acrylic polyol and polyisocyanate-based environmentally friendly organic solvent high solid primer surfacer paint) was spray-painted as a primer surfacer to a dry film thickness of 60 to 70 μm, dried at 60 ° C for 30 minutes, and then water-polished with #400 paper. On top of that, "Retan WB Eco EV 400 Deep Black" (Kansai Paint Co., Ltd., water-based repair colored base coat paint) was spray-painted to a dry film thickness of 15 μm, left at room temperature for 10 minutes, forced dried at 60 ° C for 10 minutes, and then the matte paint composition (1) obtained in Example 1 was painted under the painting conditions and film thickness shown in Tables 4-1, 4-2, and 4-3, and dried by heating at 60 ° C for 30 minutes to prepare a coated plate for gloss stability and alkali resistance test.

The "painting conditions" in Tables 4-1, 4-2, and 4-3 are as follows: Painting condition 1: room temperature 23°C, relative humidity (RH) 60%,
Coating condition 2 is a room temperature of 30° C. and a relative humidity of 75% (assuming summer), and coating condition 3 is a room temperature of 5° C. and a relative humidity of 50% (assuming winter).

(Preparation of test plate for evaluating sagging resistance)
On a dull steel plate measuring 11 cm x 45 cm and having a thickness of 0.8 mm that had been subjected to a zinc phosphate conversion treatment, "Elecron GT-10" (product name, thermosetting epoxy resin-based cationic electrodeposition paint, manufactured by Kansai Paint Co., Ltd.) was electrodeposited to a cured film thickness of 20 μm, and cured by heating at 170°C for 30 minutes. "TP-65-2" (product name, polyester-melamine resin-based automotive midcoat paint, manufactured by Kansai Paint Co., Ltd.) was air spray painted on top of it to a cured film thickness of 35 μm, and then heated and cured at 140°C for 30 minutes to obtain a coated specimen for testing. Next, 21 punch holes with a diameter of 5 mm were made in a row at 2 cm intervals in a section 3 cm from the end of the long side of the test substrate, and then, under paint booth conditions (booth conditions 3) of a temperature of 19 ° C. and a relative humidity of 51%, the water-based base coat paint composition "Retan WB Eco EV 400 Deep Black" (product name, Kansai Paint Co., Ltd., acrylic urethane resin-based water-based repair colored base paint composition, black paint color) was applied to the test substrate to a film thickness of 15 μm under the conditions of the paint booth at a temperature of 19 ° C. and a relative humidity of 51%, and the test substrate was left at room temperature for 10 minutes, and then preheated at 60 ° C. for 3 minutes. Then, the paint composition (1) obtained in Example 1 was applied to the uncured coating film with a film thickness gradient so that a film thickness of approximately 30 μm to 60 μm was obtained in the long direction, and the test plate for evaluating sagging resistance was obtained by leaving it at room temperature for 10 minutes, and then heating it at 60 ° C. for 20 minutes to cure both coating films together.

(Substrate)
The object 1, which represents a newly installed painted panel, was prepared as follows.

Substrate 1: An electrocoat-coated plate measuring 30 cm x 45 cm that had been coated with an epoxy resin-based electrocoat paint was air-spray-coated with a base coat paint ("TP-65-2", product name, manufactured by Kansai Paint Co., Ltd., a polyester-melamine resin-based automotive base coat paint) to a cured film thickness of 35 μm, and then heated and cured at 140°C for 30 minutes. Next, under painting conditions of a temperature of 23°C and a relative humidity of 68%, an aqueous base coat paint composition ("WBC-713T NO. 202" (product name, Kansai Paint Co., Ltd., acrylic melamine resin-based aqueous topcoat base coat paint for automobiles, black paint color) was applied to the coating film to a film thickness of 15 μm, left at room temperature for 5 minutes, preheated at 80°C for 3 minutes, and then a matte paint composition (15) shown in Table 3-3 below was applied as a new matte paint to the uncured colored base coating film to a cured film thickness of 35 μm, left at room temperature for 10 minutes, and then heated at 140°C for 20 minutes to cure, thereby producing coated object 1. The 60-degree gloss value of coated object 1 was 18.

(Examples 2 to 14 and Comparative Examples 1 to 6)
Matte coating compositions (2) to (20) each having a Ford Cup No. 4 viscosity of 15 seconds at 20° C. were obtained in the same manner as in Example 1, except that the formulations in Example 1 were those shown in Tables 3-1, 3-2, and 3-3 below. Using each matte coating composition, coated panels for gloss stability and alkali resistance tests and test panels for sagging resistance evaluation were prepared in the same manner as in Example 1.

(Example 15)
Coated panels for testing gloss stability and alkali resistance were prepared in the same manner as in Example 1, except that the substrate was changed to Substrate 2 described below. The gloss stability was rated A and the alkali resistance was rated S, which was good.

Substrate 2 (thin film): Substrate 2 was prepared in the same manner as Substrate 1, except that the dry film thickness of the matte coating composition (15) shown in Table 3-3 below was 25 μm. The 60-degree gloss value of Substrate 2 was 14.

(Example 16)
Coated panels for testing gloss stability and alkali resistance were prepared in the same manner as in Example 1, except that the substrate was changed to Substrate 3 described below. The gloss stability was rated A and the alkali resistance was rated S, which was good.

Substrate 3 (thick film): Substrate 3 was prepared in the same manner as Substrate 1, except that the dry film thickness of the coating composition (15) shown in Table 3-3 below was 45 μm. The 60 degree gloss value of Substrate 3 was 22.

なお、表２～表４に記載の各成分は下記のとおり。

The components listed in Tables 2 to 4 are as follows.

Main ingredient (I)
Matting agent B-1: ACEMATT OK-607, product name, manufactured by Evonik Industries, silica particles surface-treated with an organic compound, wax-treated precipitated silica, particle size (d50) 4.4 μm, specific surface area 130 m2/g, solid content 100 mass%,
B-2: ACEMATT OK-520, product name, manufactured by Evonik Industries, silica particles surface-treated with an organic compound, wax-treated precipitated silica, particle size (d50) 6.5 μm, specific surface area 220 m2/g, solid content 100 mass%,
B-3: Microflat MA-106, product name, manufactured by Koyo Chemical Industry Co., Ltd., polycarbonate resin beads, particle size (d50) 5.8 μm, solid content 7 mass%, cyclohexanone/butyl acetate (20/73) mixed solvent. Note that in Example 13, the amounts of cyclohexanone and butyl acetate were calculated, and the amount of organic solvent was shown in Tables 3-1, 3-2, and 3-3 as organic solvent β.

Organic solvent Organic solvent (c1)-1: 3-methoxybutyl acetate, alias: methoxybutyl acetate, boiling point 171.3°C, water solubility 6.5g/100g, no hydroxyl group,
Organic solvent (c1)-2: 3-methyl-3-methoxybutyl acetate, alias: 3-methoxy-3-methylbutyl acetate, boiling point 188°C, water solubility 6.8g/100g, no hydroxyl group,
Organic solvent (c1)-3: cyclohexanone, also known as anone, boiling point 156° C., [8.7 g/100 g], no hydroxyl group), a solvent for the matting agent B-3,
Organic solvent (c2)-1: "DBE": trade name, manufactured by DowDuPont, a mixed solvent of dimethyl glutarate, dimethyl succinate and dimethyl adipate, boiling point 196 to 225°C, water solubility 5.3 g/100 g,
Organic solvent (c2)-2: Aromatic hydrocarbon-based high boiling point solvent (non-toluene xylene-containing), boiling point 190° C. or higher, insoluble in water.
Organic solvent (c3)-1: butyl acetate, boiling point 126°C, water solubility 0.7 g/100 g,
Organic solvent (c3)-2: isobutyl acetate, boiling point 118°C, water solubility 1.6 g/100 g
Organic solvent (c3)-3: ethyl acetate, boiling point 77.1° C., water solubility 8.0 g/100 g or more.

Additive Surface conditioner: BYK-337, product name, manufactured by BYK Japan Co., Ltd., silicon-based surface conditioner, polyether-modified polydimethylsiloxane, active ingredient 15% by mass,
Curing catalyst: SCAT2R, trade name, manufactured by Sankyoki Synthetic Co., Ltd., organometallic catalyst mixture (a 50% solvent naphtha solution of di-n-butyltin bis-fatty acid salt and fatty acid zinc salt,
Ultraviolet absorber: Tinuvin (registered trademark) 1130, manufactured by BASF Japan, a benzotriazole (BTZ)-based ultraviolet absorber;
Light stabilizer: Tinuvin (registered trademark) 292, manufactured by BASF Japan Ltd.
Rheology control agent: crosslinked polymer fine particles (P1) obtained in Production Example 5, having an average particle size of 90 nm, an acid value of less than 0.5 mg KOH/g, and a hydroxyl value of 24 mg KOH/g.

Performance Test Method In the present invention, it is important that all performances are excellent, and if any one of them is rated "D" or "B", it is a failure.

Test item 1: Drying property After coating a 30 cm x 45 cm steel plate with coating condition 1 to a dry film thickness of 35 μm, the plate was left at room temperature (20° C.) for 30 minutes, and the surface drying property of each test plate was checked by touching with a finger. The evaluations were A, B, and C, which were pass, and D, which was fail.

This indicates the time it takes for the coating film to harden and dry, and the shorter it is, the faster it dries.

A: After 15 minutes, the surface was good with no tack.
B: After 20 minutes, the surface was good with no tack.
C: After 25 minutes, the surface was good with no tack.
D: After 25 minutes, there is tack on the surface.

Test item 2: Matte property Under coating condition 1, each matte coating composition was applied to a steel plate of 30 cm x 45 cm size so that the dry film thickness was 35 μm, and then the test plate was dried at 60°C for 30 minutes, after which the 60° specular gloss of the test plate was measured and evaluated. A value of less than 75 was considered to be acceptable.

Test item 3: Gloss stability (gloss difference due to film thickness fluctuation)
In Example 1, each matte paint composition was applied to a coated plate prepared in the same manner except that the film thickness was 25 μm, and similarly, each matte paint composition was applied to a coated plate prepared in the same manner but with a film thickness of 24 μm. The 60° specular gloss was measured for each coated plate, and the difference therebetween was evaluated according to the following criteria.

Gloss stability (gloss difference due to changes in paint booth conditions):
Using the substrate 1 as the substrate, each matte paint composition was applied to a coated plate in a film thickness of 35 μm under coating condition 2, and the 60° specular gloss of a coated plate when applied to a film thickness of 35 μm under coating condition 3 was measured, and the difference was evaluated according to the following criteria.

Gloss stability (overall rating):
Based on the results of the gloss stability (difference in gloss due to film thickness variation: sometimes abbreviated as gloss difference (film thickness)) and the gloss stability (difference in gloss due to coating condition variation: sometimes abbreviated as gloss difference (coating condition)), the evaluation was performed according to the following criteria: S and A are pass, and D is fail.
S: Gloss stability (gloss difference (film thickness)) and gloss stability (gloss difference (painting conditions)) are both less than 5;
A: The difference in either gloss stability (gloss difference (film thickness)) or gloss stability (gloss difference (painting conditions)) is 5 or more and less than 10, and the difference is not 10 or more.
D: Either the difference in gloss stability (gloss difference (film thickness)) or gloss stability (gloss difference (painting conditions)) is 10 or more.

Test item 4: sagging resistance The position where sagging of the coating film was observed 3 mm from the lower end of the punch hole of each test plate for evaluating sagging resistance was examined, and the film thickness at that position (sagging limit film thickness (μm)) was measured to evaluate sagging resistance. The larger the sagging limit film thickness, the better the sagging resistance.
Or, S and A are pass, and D is fail.
S: sagging limit film thickness is 35 μm or more,
A: The sagging limit film thickness is 25 μm or more and less than 35 μm,
D: The sagging limit film thickness is less than 25 μm.

Test item 5: Alkali resistance 0.5 mL of a 1% aqueous solution of sodium hydroxide was dropped onto the coating surface of the coated plate produced in each Example and Comparative Example when the plate was coated to a thickness of 35 μm, and the plate was left for 24 hours in an atmosphere of a temperature of 20° C. and a relative humidity of 65%, after which the coating surface was wiped with gauze and the appearance was visually evaluated according to the following criteria: S and A are pass, and D is fail.
S: No abnormality on the coating surface.
A: Discoloration (whitening) of the coating surface is observed.
D: Significant discoloration (whitening) of the coating surface.

Claims (9)

A matte coating composition comprising a base agent (I) and a curing agent (II),
The composition contains a base material (I), a hydroxyl group-containing acrylic resin (A), a matting agent (B) containing organically treated silica particles (b1'), and an organic solvent (C),
The organic solvent (C) includes an organic solvent (c1) having a solubility in water (20° C.) in the range of 5 to 50 g/100 g and a boiling point of 100 to less than 190° C.;
the mass ratio of the organically treated silica particles (b1') and the organic solvent (c1) contained in the main agent (I) is within a range of 70/30 to 10/90;
A matte coating composition, characterized in that the content of the organic solvent (c1) is within the range of 5 to 55 mass% based on the total mass of all solvents contained in the matte coating composition. The matte paint composition according to claim 1, wherein the hydroxyl-containing acrylic resin (A) has a glass transition temperature of 30°C or higher. The matte coating composition according to claim 1 or 2, wherein the content of the organically treated silica particles (b1') is within the range of 5 to 40 parts by mass per 100 parts by mass of the resin solid content of the hydroxyl group-containing resin (A) contained in the main component (I). The matte paint composition according to any one of claims 1 to 3, wherein the curing agent (II) contains a polyisocyanate compound (D). The matte paint composition according to any one of claims 1 to 4, wherein the main agent (I) further contains a rheology control agent (E). The matte paint composition according to claim 5, wherein the rheology control agent (E) contains crosslinked polymer fine particles (e1). A coating film forming method in which the matte coating composition according to any one of claims 1 to 6 is applied to a substrate to form a coating film on the outermost surface. A step (1) of applying a primer surfacer to an old coating film or a damaged part of a painted body to form a base coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a clear coating composition onto the colored base coating film obtained in the step (2) and drying the composition to form a clear coating film (III);
A method for repair coating of a coated body, comprising the steps of: (a) applying a clear coating composition to a coated body; and (b) applying a clear coating composition to a coated body. A step (1) of applying a primer surfacer to an old coating film or a damaged part of a painted body to form a base coating film (I);
A step (2) of applying a colored base coating composition onto the undercoat treatment coating to form a colored base coating film (II);
A step (3) of applying a first clear coating composition (CC1) onto the colored base coating film obtained in the step (2) and drying the composition to form a first clear coating film (III);
A method for repair coating of a coated body, comprising the step (4) of coating a second clear coating composition (CC2) on the first clear coating film obtained in the step (3) to form a second clear coating film (IV),
A method for repair painting of a painted body, wherein the second clear paint composition (CC2) is a matte paint composition according to any one of claims 1 to 6.