JP3470524B2 - Powder coating composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention provides a coating film which contains a ceramic component and is excellent in stain resistance, stain removability, weather (light) resistance, moisture resistance and appearance, and also environmental conservation and safety. High powder coating composition.

[0002]

2. Description of the Related Art In recent years, powder coatings containing almost no volatile components have been widely used for coating automobile parts, home electric appliances and building materials. On the other hand, the coating film used for outdoor applications is
Due to changes in the environment such as air pollution, the amount of oil drops and dust contained in the atmosphere increases, making it easier to contaminate the coatings applied to buildings and automobiles than before, and it is difficult to remove the dirt. Problem is occurring. Therefore, as the performance of the coating film, resistance to contamination, that is, stain resistance, and removability of contaminants from the contaminated coating film, that is, stain removability, have been desired. Under these circumstances, it has excellent stain resistance, stain removal resistance, weather (light) resistance, and water resistance.
It has been desired to create a powder coating composition having excellent chemical resistance, appearance, environmental protection and safety. As a typical example of the powder coating material having stain resistance today, there is a coating material containing a fluorine-containing resin as a main component. The stain resistance was due to the high weather resistance of the fluororesin. The characteristics of the fluorine-containing resin include (1) that the size of the binding energy between the fluorine atom and the carbon atom is greater than that of the hydrogen atom and the carbon atom and is stable, and (2) that the fluorine atom has a higher energy than the hydrogen atom. Large atomic radius of atoms and low polarizability between fluorine molecules (0.68 × 10 ^-24 cc)
Therefore, the function is exhibited by high water repellency and oil repellency due to the low surface free energy.

However, the fluorine-containing resin has a low dielectric constant, and the coating film has a property of easily causing stains such that the coating film is easily charged and hardly discharged. Also, since the electronegativity of the fluorine atom is high, the polymerizability is different from that of ordinary acrylic monomers, which limits the range of resin design. Some fluorine-containing monomers have limited solubility in solvents. However, there is a concern that the resin price is high, hydrofluoric acid is generated at the stage of the waste treatment of the coating film using the fluorine-containing resin, and there is concern about the impact on the environment, but the price is high. , Restrictions on use, and adverse effects on the environment at the time of disposal. On the other hand, recently, as a highly weather-resistant coating composition in the field of solvent-based coatings, a coating composition having weather resistance imparted by an acrylic polyol obtained by copolymerizing a polymerizable UV-stable monomer as an essential component has been proposed. (JP-A-1-261409). However, this publication makes no mention of resistance to contamination. Further, as a stain resistant composition, a coating composition prepared by mixing a partial condensate of an organosilicon compound and specific silica fine particles has been proposed (JP-A-2-3468). However, in this publication, the resin component used in the coating composition is not described in detail. Furthermore, a coating composition containing an acrylic polyol resin, a binder, an inorganic organosol, and a solvent has been proposed (JP-A-4-173882). However, although this coating composition has been improved to some extent in stain resistance and weather (light) resistance, it has the drawback of insufficient stain removability. As described above, a coating composition, particularly a powder coating composition, which gives a coating film having excellent stain resistance, stain removability, and weather (light) resistance has not yet been found.

[0004]

The present invention has been made in view of the state of the art, and provides a coating film having good chemical performance and physical performance, and particularly stain resistance, stain removability and weather resistance. The purpose of the present invention is to provide a powder coating composition having excellent environmental protection and safety while forming a coating film having excellent (light) property, moisture resistance and appearance.

[0005]

As a result of intensive studies to develop a powder coating composition having the above properties, the present inventors have found that a specific thermosetting powder coating composition and a specific ceramic composition are used. It was found that a composition containing and can achieve the object, and the present invention has been completed based on these findings.

That is, the present invention provides (A) 55 to 95% by weight of a thermosetting powder coating material component containing a thermosetting resin which is solid at room temperature, and (B) a dispersion of a silicon oxide sol,
Surface treatment with silane coupling agent before and after drying
The average particle size obtained by it is 5~100nm Shi
Run coupling agent Surface treatment Silicon oxide fine particle component 5
A powder coating composition containing 45% by weight is provided. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the powder coating composition of the present invention, the thermosetting resin which is used as the component (A) and is solid at room temperature is not particularly limited, but it can be applied to conventional thermosetting powder coatings. Known thermosetting resins such as a self-crosslinking type used as a film forming component, a curing agent-containing type, and a curing agent post-addition type can be used. Examples of such thermosetting resin include, for example, acrylic-based, polyester-based, and
A resin having a functional group that is solid at room temperature such as a fluorine-based or epoxy-based resin is used, and examples of the curing agent include a melamine resin, a blocked isocyanate compound, a polybasic acid, an amide, a glycidyl compound, and a polymer thereof. In particular, considering weather resistance (light), it is desirable to use an acrylic resin. The functional group of the main agent and the functional group of the curing agent react with each other to form a crosslinked structure. The mixing ratio of the main agent and the curing agent in the thermosetting resin is preferably in the range of 0.6 to 1.6 as the functional group ratio of the main agent and the curing agent. These thermosetting resins may be used alone or in combination of two or more. The mixing ratio of the thermosetting powder coating component containing the thermosetting resin which is solid at room temperature as the component (A) is 55, which is the total amount of the components (A) and (B).
˜95 wt%, preferably 60-93 wt%.

In the powder coating composition of the present invention, (B)
Component Silane Coupling Agent Surface Treatment Silicon Oxide Fine Particles
Since various functional groups can be introduced on the particle surface, when forming a film in the powder coating composition of the present invention,
It becomes easy to chemically bond with an organic component such as a resin or polyisocyanate. In this way, the silane cup is formed by chemically bonding the ceramic component and the organic component.
Compared to the case where the ring agent surface-treated silicon oxide fine particles are formed and the film is not chemically bonded, the coating film has stronger crosslinking, and the stain resistance, stain removal property, chemical resistance, weather resistance and the like are improved.

The dispersion of silicon oxide sol can be obtained by adding silicon tetrahalide into water, adding an acid to an aqueous solution of sodium silicate, or the like. Moreover, as a commercial item, for example, as an aqueous dispersion, Snowtex-O
[Nissan Chemical Co., Ltd., trade name] and Snowtex-
N [NISSAN CHEMICAL INDUSTRIES, LTD., Trade name] is an organic solvent dispersion of Snowtex MIBK-ST [NISSAN CHEMICAL INDUSTRIES, LTD. Trade name] and Snowtex MIBK.
-SZ [manufactured by Nissan Chemical Industries, Ltd., trade name] and the like. When the silane coupling agent surface-treated silicon oxide fine particle component is produced by using an aqueous dispersion of silicon oxide sol as a raw material, the aqueous dispersion medium of silicon oxide sol is completely removed and dried to be used as a solid state. . As a method for removing the aqueous dispersion medium, for example, a water-soluble organic solvent is added to the dispersion medium, and the aqueous dispersion medium is phase-converted into an organic solvent by repeating azeotropic dehydration, and then the organic solvent is removed under reduced pressure. A method etc. can be mentioned. Examples of the method for removing the organic solvent dispersion medium include a method in which the organic solvent is removed under reduced pressure as it is, and a method in which the organic solvent is removed under reduced pressure after phase conversion into an organic solvent that is easy to remove the solvent. Although the removal of the organic solvent under reduced pressure varies depending on the type of the organic solvent used, it is generally preferable that the temperature is in the range of 30 to 80 ° C. and the degree of reduced pressure is in the range of 15 to 100 mmHg.

The surface treatment of the dispersion of silicon oxide sol with the silane coupling agent can be performed before or after drying the silicon oxide sol. That is,
The surface treatment with the silane coupling agent before drying the silicon oxide sol can be performed, for example, by adding the silane coupling agent to the dispersion of the silicon oxide sol. Further, the surface treatment with the silane coupling agent after drying the silicon oxide sol is, for example, directly after pulverizing the silicon oxide sol by the above solvent removal method,
Alternatively, it can be carried out by a method of performing solid-liquid reaction with a dispersion of powdered silicon oxide sol by adding a silane coupling agent after dispersing in a suitable dispersion solvent. The temperature of the surface treatment with the silane coupling agent is not particularly limited, but it is usually preferably performed in the range of 20 to 100 ° C., and 3
It is more preferably carried out in the range of 0 to 90 ° C, particularly preferably in the range of 40 to 80 ° C. Also,
The surface treatment time with the silane coupling agent is not particularly limited, but it can be usually carried out by reacting for 30 minutes to 48 hours. Among the surface treatment methods using the above silane coupling agent, in the sense of increasing the uniformity of the surface treatment.
A method of surface-treating the silicon oxide sol before drying is preferable.

Further, in the surface treatment of the aqueous dispersion of the silicon oxide sol with the silane coupling agent, the dispersion medium is subjected to azeotropic dehydration with an azeotropic dehydration solvent and then subjected to the surface treatment with the silane coupling agent. It is possible to perform the treatment with high uniformity and stability of the treated surface.
Examples of the azeotropic solvent include water-soluble alcohols, carboxylic acid esters, cyclic ethers and the like. Examples of water-soluble alcohols include ethanol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, methyl cellosolve, ethyl cellosolve, ethylene glycol monomethyl. Ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 3-methyl-3-methoxybutanol, propylene glycol monomethyl ether, ethylene glycol , Propylene glycol and the like. Examples of the water-soluble carboxylic acid ester include methyl acetate and ethyl acetate. Examples of the water-soluble cyclic ether include 1,4-dioxane.

These azeotropic solvents may be used either individually or in combination of two or more. Further, a solvent that is immiscible with water or a solvent that is miscible with water may be used as an intermediary for the purpose of increasing the azeotropic distillation dehydration efficiency. Examples of the solvent include benzene, xylene, toluene, cyclohexanone, diphenyl ether, dibutyl ether and the like. These solvents may be used alone or in combination of two or more. However, the amount used is limited to the range in which the sol is not aggregated and varies depending on the solvent, but is usually preferably in the range of 1 to 10% by weight. The azeotropic distillation dehydration is preferably performed while dropping an azeotropic solvent. The azeotropic distillation dehydration is preferably performed in the range of 30 to 100 ° C, and particularly preferably in the range of 40 to 80 ° C. The azeotropic distillation dehydration can be performed under reduced pressure or normal pressure, but it is preferably performed under reduced pressure.

Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane,
γ-methacryloyloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Aminopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane and the like, and preferably methyltrimethoxysilane, dimethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyl. Oxypropyltrimethoxysilane is preferable, and methyltrimethoxysilane and dimethyldimethoxysilane are particularly preferable. Further, as commercially available products, A-162, A
-163, AZ-6122 (all are trade names, manufactured by Nippon Unicar Co., Ltd.) and the like. These silane coupling agents can be used alone or in combination of two or more. When surface-treating with a silane coupling agent,
The content of the silane coupling agent is preferably 1 to 40% by weight, more preferably 5 to 30% by weight, based on the heating residue of the silicon oxide sol.

Further , the surface treatment oxidation of the silane coupling agent
The silicon fine particles have an average particle size of 5 to 100 nm and are 5
˜50 nm is particularly preferred. When the average particle size is larger than 100 nm, the transparency of the clear film is impaired, and the stain resistance and stain removability of the coating film deteriorate. In the powder coating composition of the present invention , the blending amount is preferably selected to be 5 to 45% by weight, and 7 to 40% by weight based on the total amount of the components (A) and (B). More preferable. When the amount is less than 5% by weight based on the total amount of the components (A) and (B), the silane coupling agent surface-treated oxidized case
The effect of the fine particles of iodine is not sufficiently exerted, and the effect of improving the stain resistance, stain removability, weather (light) resistance, moisture resistance, etc. of the coating film is not recognized so much. There is a tendency for the flexibility to decrease. Stain resistance of coating film,
Stain release, Sila view of the balance, such as weather (light) resistance
Coupling agent surface treatment silicon oxide fine particle component,
The range of 7 to 40% by weight is preferable with respect to the total amount of the components (A) and (B).

If necessary, a pigment may be added to the powder coating composition of the present invention in the range of 0.01 to 100 parts by weight based on 100 parts by weight of the thermosetting resin as another component. As the pigment, it is possible to use inorganic pigments such as titanium dioxide, carbon black and iron oxide, extender pigments such as talc, precipitated barium sulfate, silica and calcium carbonate, and organic pigments such as cyanine blue and azo pigments. Further, as in the conventional powder coating composition, other components such as a curing accelerator, a leveling agent, a defoaming agent, an antioxidant, a modifier such as an ultraviolet absorber, and other additives may be added as a thermosetting resin. 10
It can be added in the range of 0.01 to 30 parts by weight with respect to 0 parts by weight. These pigments and additives may be mixed in advance with the thermosetting powder coating material component (A), or in advance with the silane coupling agent surface-treated silicon oxide fine particle component (B). They may be mixed, or the surface of the thermosetting powder coating component (A) and the surface of the silane coupling agent (B) may be mixed.
Although it may be mixed after mixing the treated silicon oxide fine particle component, it is preferably mixed in advance with the thermosetting powder coating material component (A). Further, the silane coupling agent surface-treated acid of the component (B) in the powder coating composition of the present invention
When the silicon oxide fine particle component and the pigment component are used together to form a colored coating film, they are incorporated in the powder coating composition (B).
The total content of the components and the pigment components is usually preferably 70% by weight or less in the powder coating composition, and more preferably 40% by weight or less. If it is used in an amount of more than 70% by weight, the amount of the thermosetting resin component that is a coating film forming component in the powder coating composition decreases, and the mechanical strength of the resulting coating film may be impaired, which is not preferable. Therefore,
In order to exert the performance of the present invention, it is effective to preferentially determine the blending amount of the component (B) and to determine the blending amount by suppressing the blending amount of the pigment component to the desired color tone as much as possible. Yes, it is preferable.

The powder coating composition of the present invention comprises the thermosetting powder coating component (A) and the silane catalyst (B).
It is desirable that the silicon oxide fine particle component for surface treatment of the pulling agent is uniformly dispersed. In order to prevent the components (A) and (B) from being separated during storage, transportation and painting, it is preferable that both components are in a melted and integrated state. Therefore, as an example of the method for producing the powder coating composition of the present invention,
There may be mentioned a method in which both the components (A) and (B) are heated to a temperature at which the resin component in the component (A) melts, and the component (B) is dispersed in the component (A). In the above production method, the component (A),
The component (B) is simultaneously kneaded at a temperature at which the resin component in the component (A) is melted, and silane coupling phosphorus is added to the melted powder coating material.
Agent surface-treated silicon oxide fine particles can be dispersed. This melt-kneading method can be performed by various melt-kneading methods in ordinary powder coating production.

In the method for producing the powder coating composition of the present invention, specifically, for example, the thermosetting resin main component which is the component (A),
A predetermined amount of the component (B) is added to a mixture of a curing agent, and optionally a pigment and an additive, and the mixture is mixed with a dry blender. Then, using an extrusion kneader, a single-screw or twin-screw extruder, etc. Melt kneading is carried out in a temperature range in which the resin component in the component (A) is melted, usually 80 to 120 ° C.,
It can be carried out by pelletizing, cooling and then finely pulverizing the resulting mixture with an impact pulverizer, an air flow type pulverizer or the like and classifying it.

As an example of a more preferable production method in which both the component (A) and the component (B) are melt-integrated, a thermosetting resin of the component (A) containing the component (B) is used. The method of using a masterbatch is mentioned. That is, after the thermosetting resin main component of the component (A) is dissolved in an appropriate solvent, the dispersion of the silicon oxide sol that is the raw material of the component (B) is dispersed and stabilized with or without heating. Then, a silicon oxide sol-stabilized resin solution is prepared, and after the silane coupling treatment, the solvent is distilled off under reduced pressure and dried under reduced pressure to produce a thermosetting resin masterbatch containing the component (B). The thermosetting resin masterbatch containing the obtained component (B) was added with a curing agent and, if necessary, a pigment, an additive and the like in the same manner as in the above Production Example, and mixed by a dry blender, followed by extrusion kneading. Melt-kneading is carried out using a machine to form pellets and then cooled. The powder coating composition of the present invention can be produced by finely pulverizing this with an impact pulverizer, an air flow type pulverizer or the like and classifying it. here,
Without dispersing the component (B) in the component (A),
The method of adding and dispersing the component (B) at the time of crushing after the components are melt-kneaded or at the time of classification not only causes insufficient dispersion in the coating composition, but also the component (B) during storage, transportation, and coating operations. May result in separation. Such disproportionation of the component (B) adversely affects the change in coating efficiency during coating and the stain resistance, stain removal resistance, weather (light) resistance and physical performance of the coating film. Not good for quality control.

When the powder coating composition of the present invention is used as a single-layer top coating composition, the coating method may be an electrostatic spraying method, a fluidized-bed coating method, an electrostatic fluidized-bed coating method or the like. A coating material is applied to the article to be coated by a method, and then heated and melted to be cured to form a coating film, thereby obtaining a coated article. Of the coating methods, the electrostatic spraying method is particularly preferable. To apply the powder coating composition of the present invention, a commercially available electrostatic coating machine (loading voltage: -50 to -90k) is applied to an object to be coated.
V) or other powder coating method is applied uniformly, and then heated and melted in a hot air baking oven, an infrared oven, an induction heating oven or the like to be cured to form a coating film. The coating thickness is usually 30 to 1
It is suitable to apply it to 50 μm, preferably 50 to 80 μm.

When used in a composite coating film composed of a colored base coat and a clear top coat which is the powder coating composition of the present invention, the colored base coat is applied onto an object to be coated and pre-dried (flushing). ) Or after heating and curing, the powder coating composition of the present invention is applied on the colored base coat coated surface by using the same coating method as in the case of being used as the above-mentioned single-layer top coating, and then heat-melted and cured. A coating film is formed by hardening and a coated article is obtained. Conventional thermosetting powder coating materials such as acrylic resin, polyester resin, and epoxy resin can be used as the colored base coat of the powder coating material. At this time, a colored base coat of the powder coating material is applied onto an object to be coated, heated and melted to be cured to form a coating film, and then the powder coating composition of the present invention is applied as a clear top coat. It is applied on the surface and then heated and melted to be cured to form a coating film to obtain a coated article.

For the colored base coat, conventional solvent-based paints and water-based paints can be used in addition to the above powder paints. As a coating method using a solvent-based paint or a water-based paint as a colored base coat, an organic solvent suitable for the paint system used in some cases or a reactive diluent is added to adjust the viscosity to a desired value, and then air spray or static is applied. Using a commonly used coating machine such as an electric air spray, roll coater, flow coater, dipping type coater, or a brush, bar coater, applicator, etc., so that the coating film after drying becomes 0.5 to 300 μm Apply
The present invention is used as a clear top coat after pre-drying (flushing) at a temperature at which a curing reaction does not occur to remove a solvent component or after heat curing at a temperature of 60 to 300 ° C. which is a normal baking condition for 5 seconds to 24 hours. The powder coating composition of (1) is applied to the coated surface of the colored base coat, and then heated and melted to be cured to form a coating film, thereby obtaining a coated product. The heat curing condition of the powder coating composition of the present invention depends on the kind of the thermosetting resin as the component (A) and the blending ratio of the coating composition, but usually the temperature of the coated article is 120 to 250 ° C.
For 5 to 30 minutes, preferably at 140 to 200 ° C for 5 to 2
0 minutes is appropriate.

The material to be coated with the powder coating composition of the present invention is not particularly limited as long as it can withstand the heating conditions at the time of coating film formation, and various materials can be used. Examples thereof include various shapes such as organic materials and inorganic materials such as glass, metal, plastic, ceramics, concrete and gypsum board. For example, examples of the plate include a metal steel plate having a thickness of about 0.2 to 2 mm, a galvanized steel plate, an aluminum plate, a stainless plate, a glass plate, and a ceramics plate. These objects to be coated may be those that have been surface-treated in advance, or those that have a coating film formed on their surface in advance. Examples of coated articles obtained by applying the powder coating composition of the present invention include buildings, structures, metal products, plastic products, ceramic products, glass products and the like. More specifically, automobiles, automobile parts (for example, parts such as bodies, bumpers, spoilers, mirrors, wheels, interior materials, and various other materials), metal plates such as steel plates, motorcycles, motorcycles Parts, road materials (for example,
Guardrails, traffic signs, etc., tunnel materials (for example, side wall boards), ships, railway vehicles, aircraft, printing equipment, parts for printing equipment, furniture, musical instruments, home appliances, building materials, containers, office supplies, sports equipment. , Toys, etc.

EXAMPLES Next, the present invention will be described more specifically by way of examples.
The present invention is not limited to these examples. [Creation of test plate] Polished steel plate (JIS G 3141)
, Epicoprimer No. After coating 1000BF2 (registered trademark, bake type epoxy resin coating manufactured by NOF CORPORATION) to a dry film thickness of 20 μm, 160 ° C. × 20
Baked for minutes. Then, on top of that, high urethane No. 5
000 (white) (registered trademark, Nippon Oil & Fats Co., Ltd., urethane resin paint) and high urethane curing agent HA (registered trademark, Nippon Oil & Fats Co., Ltd., curing agent) are mixed at a weight ratio of 6: 1. After coating the above to a dry film thickness of 25 μm,
A test plate was prepared by forced drying at 80 ° C. for 30 minutes and leaving it overnight.

The coating performance of the coating film obtained from the powder coating composition of the present invention was determined as follows. (1) Specular gloss: JIS K-5400 (1990)
The values when the incident angle and the light receiving angle are 60 degrees are shown according to 7.6. (2) Visibility: Visual observation was evaluated according to the following criteria. ○: When a fluorescent lamp is projected on the coating film, the fluorescent lamp is clearly reflected. Δ: When a fluorescent lamp is projected on the coating film, the periphery (outline) of the fluorescent lamp is slightly blurred. X: When a fluorescent lamp is projected on the coating film, the periphery (outline) of the fluorescent lamp is markedly blurred. (3) Pencil hardness: JIS K-5400 (1990)
8.4.2 The procedure was carried out according to the hand scraping method.

(4) Adhesion: JIS K-5400 (1
990) 8.5.1 Adhesion test is performed according to the cross cut method,
Adhesion was evaluated according to the following criteria. ○: 10 points △: 8 points ×: 6 points or less (5) Erichsen value: JIS K-5400 (199
0) 8.2.2 Performed according to the breaking distance method. (6) Weather resistance (accelerated weather resistance test): JIS D-020
The retention rate (%) of 60 ° gloss of the coating film (JIS K-5400 (1990) 7.6) was determined by a test using a 55.4 sunshine carbon arc lamp type weather resistance tester.

(7) Xylene rubbing resistance: The surface of the test piece was visually observed for a change in the surface condition after 100 reciprocating rubbing with a channel impregnated with xylene, and the xylene rubbing resistance was evaluated according to the following criteria. ◯: There is no change in the gloss of the test piece as compared with the original test piece. Δ: There is a slight change in the gloss of the test piece as compared with the original test piece. X: The gloss of the test piece is significantly changed as compared with the original test piece. (8) Oil resistance marker stain resistance: A line was drawn on the coating film of the test piece with an oily marker, heated at 80 ° C. for 5 hours, and then the line state was wiped off with a flan soaked with xylene. Was visually observed, and the oily marker staining property was evaluated according to the following criteria. ○: The line of the oil-based marker on the test piece was completely wiped off and no trace was left. Δ: A trace of the line of the oily marker on the test piece remains slightly. X: The trace of the line of the oily marker on the test piece is clearly left.

(9) Outdoor exposure contamination (ΔL): After exposing the test piece to the outdoors, SM color computer SM-4
The L value after exposure was measured with -MCH (Suga Tester Co., Ltd., trade name), and the value obtained by subtracting the L value before exposure from the L value after exposure was determined as ΔL and evaluated. (10) Moisture resistance: 40% relative humidity of the test piece is 40%
After exposure for 120 hours at ± 1 ° C, take out 2
The surface condition of the test piece after the elapse of time was visually observed and evaluated according to the following criteria. ◯: There is no change in gloss and surface condition of the test piece as compared with the original test piece. Δ: There are some changes in gloss of the test piece and blisters (blister) as compared with the original test piece. X: Compared with the original test piece, the change in the gloss of the test piece and the blister (blister) are remarkable.

Production Example 1 Snowtex MIBK-ST (trade name, manufactured by Nissan Chemical Industries, Ltd.) was placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux tube with a Dean-Stark trap and a dropping funnel.
Silicon oxide sol dispersion (average particle size: 30 nm), solid content: 30% by weight, solvent: methyl isobutyl ketone) 10
00 parts by weight and 40 parts by weight of A-163 (manufactured by Nippon Unicar Co., Ltd., silane coupling agent) were charged and heated to 8
After holding at 0 ° C. for 8 hours and treating with a silane coupling agent, the solvent component is heated at a temperature of 40 ° C. and a vacuum degree of 15 to 20 mmH.
g under reduced pressure for 1 hour and then heated to 60 ° C.,
By continuing the distillation under reduced pressure for 30 minutes, 284 parts by weight of the surface-treated silica sol (average particle diameter of dispersion: 32 nm) was obtained.

Production Example 2 Almatex PD7690 (trade name, manufactured by Mitsui Toatsu Chemicals, Inc., powder coating acrylic in a reaction vessel equipped with a stirrer, a thermometer, a reflux tube with a Dean Stark trap and a dropping funnel. Resin) 750 parts by weight, ethyl acetate 10
00 parts by weight and Snowtex MIBK-ST (Production Example 1
The same) (250 parts by weight) was charged, and the mixture was heated to 60 ° C. with gentle stirring. 11 parts by weight of A-163 (manufactured by Nippon Unicar Co., Ltd., a silane coupling agent) was added while dispersing the sol component in the resin solution, and the mixture was maintained at 60 ° C. for 2 hours while stirring to perform surface treatment with the silane coupling agent. After removing the solvent component, the temperature is 40 ℃, vacuum degree is 15 ~ 20mmHg
The mixture was heated under reduced pressure for 2 hours, heated to 150 ° C. for 1 hour, and continued under reduced pressure for another 2 hours, then collected in a stainless steel vat, cooled and pulverized to obtain a thermosetting resin masterbatch ( R-MB) 883 parts by weight was obtained. The average particle size of the surface-treated dispersion of silica sol is 32 nm.

Examples 1 to 7 The components of Examples 1 to 7 shown in Table 1 and Table 2 were uniformly mixed for about 1 minute by a dry blender (trade name, Henschel mixer, manufactured by Mitsui Miike Kakoki Co., Ltd.). Mix, then 8
Melt-kneading is performed using an extrusion kneader (trade name: Busco Kneader PR-46, manufactured by Buss Co., Ltd.) under a temperature condition of 0 to 100 ° C., and after cooling, finely pulverized by a hammer-type impact pulverizer and then classified by a wire mesh of 80 mesh. By doing so, a powder coating material was produced. The obtained powder coating material was applied to an object to be coated (the above-mentioned test plate) having a predetermined plate thickness by an electrostatic spraying method with a charge of −80 kV so that the average film thickness was 50 to 60 μm. Next, after heat curing under the baking conditions shown in Tables 1 and 2 to prepare a test piece, the coating film physical properties of the test piece were evaluated and summarized in Tables 3 and 4.

[0031]

[Table 1]

[0032]

[Table 2]

Note: The subscripts in Tables 1 and 2 indicate the following. 1): manufactured by Mitsui Toatsu Chemicals, Inc., trade name, acrylic resin,
Epoxy equivalent 475 g / eq, glass transition temperature 64 ° C. 2): Johnson Polymer Co., Ltd., trade name, acrylic resin, hydroxyl value 94 mg / g, glass transition temperature 50 ° C. 3): Nippon Yupica Co., Ltd., trade name , Polyester resin, hydroxyl value 31 mg / g, glass transition temperature 57 ° C. 4): Asahi Glass Co., Ltd., trade name, fluororesin, hydroxyl value 50 mmKOH / g, glass transition temperature 68 ° C., fluorine content 30% by weight 5) : Manufactured by Huls, trade name, ε-caprolactam block isophorone diisocyanate, NCO equivalent 280 g
/ Eq 6): Ciba Geigy, trade name, UV absorber 7): Sankyo Co., Ltd., trade name, radical trap agent 8): Mitsui Toatsu Chemical Co., Ltd., trade name, leveling agent 9): Anti-armpit agent

[0034]

[Table 3]

[0035]

[Table 4]

As is clear from the results of Tables 3 and 4,
The coating film obtained from the powder coating composition of the present invention has specular gloss, sharpness, pencil hardness, adhesion, Erichsen value, weather resistance, xylene rubbing resistance, oil resistance marker stain resistance, outdoor exposure stain resistance. And excellent in moisture resistance.

Comparative Examples 1 to 6 The components of Comparative Examples 1 to 5 shown in Table 5 were uniformly mixed for about 1 minute by a dry blender (trade name, Henschel Mixer, manufactured by Mitsui Miike Kakoki Co., Ltd.), Next 80-1
Melt-kneading is performed using an extrusion kneader (trade name: Busco Kneader PR-46, manufactured by Buss Co., Ltd.) under a temperature condition of 00 ° C., and after cooling, finely pulverized with a hammer-type impact pulverizer and then classified with a wire mesh of 80 mesh. To produce a powder coating. The obtained powder coating composition should have an average film thickness of 50 to 60 μm.
Coating was performed on an object to be coated having a predetermined plate thickness by an electrostatic spraying method with a charge of 80 kV. Then, after heat curing under the baking conditions shown in Table 5, the coating film physical properties were evaluated,
It is summarized in Table 6.

[0038]

[Table 5] Note: The subscripts in Table 5 indicate the following. 1) to 9): The same as in Table 1. 10): Dispersion of silicon oxide sol (obtained by distilling a dispersion medium of MIBK-ST (trade name, manufactured by Nissan Chemical Industries, Ltd.) under reduced pressure).

[0039]

[Table 6]

Silane Coupling Agent Surface Treatment Silicon Oxide
Comparative Examples 1 and 3 in which the fine particle component (indicated as organic / inorganic composite fine particle component in the table ) is less than 5% by weight .
All of 4 and 5 are inferior in moisture resistance, accelerated weathering resistance, xylene rubbing resistance, oil resistance marker stain resistance, outdoor exposure stain resistance, etc., and Comparative Example 6 which is a fluororesin type is inferior in outdoor exposure stain resistance. Silane Coupling Agent Surface Treatment Comparative Example 2 in which the silicon oxide fine particle component was not surface treated with the silane coupling agent (untreated silica sol) was inferior in 60 ° gloss, sharpness, Erichsen value and moisture resistance.

[0041]

The powder coating composition of the present invention has a weather resistance (light).
In addition to providing a coating film having excellent properties, stain resistance, stain removability, and a good appearance and moisture resistance, it has excellent characteristics such as high environmental conservation and safety.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-143789 (JP, A) JP-A-4-173882 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 5 / 03,7 / 12,201 / 00

Claims (4)

(57) [Claims] 1. (A) 55 to 95% by weight of a thermosetting powder coating material component containing a thermosetting resin solid at room temperature, and (B) an acid
Before and after drying the sol of silicon oxide sol,
Silane coupling agent having an average particle diameter of 5 to 100 nm obtained by surface-treating with a lan coupling agent
A powder coating composition comprising 5 to 45% by weight of a surface-treated silicon oxide fine particle component. 2. Silane coupling agent surface-treated silica oxide
The elementary fine particle component is obtained by subjecting a dispersion medium of an aqueous silicon oxide sol to azeotropic dehydration with an azeotropic dehydration solvent and then surface-treating the dispersion of the silicon oxide sol with a silane coupling agent. The powder coating composition described. 3. A compounding amount of a silane coupling agent is an amount of oxidation.
1-40% by weight based on the heating residue of silicon sol
The powder coating composition according to claim 1 or claim 2. 4. A powder coating composition comprising a component (A) and a component (B).
It is obtained by melt-kneading the components and then finely pulverizing them.
The powder coating composition according to any one of claims 1 to 3.