JPH0425076B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a metallic finishing method, in particular to a metallic finishing method using water-based metallic paints. Conventional technology Metallic paint films are made of flake-like metallic pigments contained in the paint film that reflect incident light from the outside and sparkle, creating a richly varied color that combines with the various color tones of the paint film. It has a unique appearance with excellent cosmetic properties, and is often applied to the exterior panels of automobiles and motorbikes. As a method for forming such a metallic coating film, a one-coat, one-bake method is used, in which a metallic paint containing a metallic pigment is applied directly to the object to be coated or on the surface of a hardened intermediate coating film, and then heated and cured. (1C1B), apply metallic paint, heat cure it, and then apply clear paint to form a transparent film.
A two-coat, two-bake method (2C2B) in which the coating is heated and cured again, a two-coat, one-bake method (2C1B) in which both coatings are coated in the above order and both coatings are simultaneously cured by one heating, and the 2C1B is used. The 3-coat, 2-bake method (3C2B) is known, in which clear paint is coated on top of the painted surface and then heated and cured again. Among these methods, the number of painting steps, finished metallic appearance, paint film performance, etc. are comprehensively judged. Therefore, the 2C1B metallic finishing method is the most commonly used. On the other hand, a metallic coating film that has a uniform metallic feel with no metallic unevenness and excellent gloss clarity has flake-like metallic pigments that are spread parallel to the coating surface and uniformly over the entire surface of the object being coated. It is said to be formed because of the regular orientation and excellent smoothness of the coated surface of the metallic paint itself. In order to meet these requirements, metallic paints have a high viscosity when applied to the surface to be coated (metallic pigments do not easily flow, preventing the occurrence of metallic unevenness), as well as film thickness and heating immediately after application. It is said that it is preferable to use a material that has a large difference in film thickness after curing (the metallic pigment tends to be oriented parallel to the painted surface), and as a result,
Metallic paints containing a large amount of organic solvent and having a low solid content concentration (usually 20 to 30% by weight of non-volatile content) have been used in the above-mentioned various coating methods. However, in the paint field, which handles large amounts of organic solvents, prevention of air pollution and resource conservation have been raised as important issues, and the use of water-based paints has been cited as a countermeasure, and water-based paints are also used in metallic finishing methods. There is an increasing demand for the application of metallic paints. However, since water-based paints use water as a solvent, the amount of water evaporated varies greatly depending on the humidity at the time of painting, resulting in a marked difference in the finished state of the paint. That is, at high humidity, the paint applied to the object to be coated tends to flow, while at low humidity, the coated surface becomes rough. Therefore, when using water-based metallic paints, it is necessary to strictly control the humidity during painting, which requires a great deal of labor and equipment cost, which is economically undesirable. In addition, water-based metallic paints have a high surface tension and are less likely to leak from the cured intermediate coat to the underlying surface than organic solution-based paints, making it difficult to obtain a uniform arrangement of metallic pigments, resulting in metallic unevenness, There are drawbacks such as a decrease in gloss and sharpness, and poor finishing properties. Problems to be Solved by the Invention In view of these circumstances, the inventor of the present invention has developed a water-based metallic paint that contributes to the prevention of air pollution and resource conservation, as well as a uniform and excellent metallic feel. We conducted intensive research with the main purpose of creating a metallic paint film with glossy clarity. As a result, the above purpose can be achieved by applying a thermosetting paint that does not contain metallic pigments in advance, and applying a water-based metallic paint to the coated surface while the viscosity of the applied paint is within a specific range. I have discovered what I can accomplish. Means for Solving the Problems The present invention uses a neutralized polyhydric carboxylic acid resin having an acid value of 5 to 100 and an amino resin as essential components,
An organic solution-type or non-aqueous dispersion-type thermosetting paint that does not contain metallic pigments (hereinafter simply referred to as "non-metallic paint") is applied to the object to be coated, and the clay of the applied paint is mixed with 10 poise ( After adjusting the temperature to 20°C or above, painting a thermosetting water-based metallic paint thereon, and further painting a transparent thermosetting paint, the coating film consisting of the above three layers is heated and cured at the same time. This relates to a metallic finishing method. The feature of the present invention is that on a painted surface coated with a non-metallic paint containing a neutralized polyhydric carboxylic acid resin,
The viscosity of the applied coating film is adjusted to a specific range,
The process involves painting a water-based metallic paint over it. In other words, when applying a water-based metallic paint, the pre-applied non-metallic paint exhibits strong water absorption due to the neutralized polyhydric carboxylic acid resin contained therein, It absorbs water in the water-based metallic paint and rapidly increases the viscosity of the water-based metallic paint. At the same time, because the viscosity of the non-metallic paint is adjusted to a specific range, the water-based metallic paint applied thereon is less susceptible to the effects of the non-metallic paint, resulting in uneven flow, sagging, etc.
A finish free of defects such as metallic unevenness can be obtained. Furthermore, water-based metallic paints have good wettability with non-metallic paints, so they do not cause defects such as rough skin even when applied in a low humidity atmosphere. In this way, the present invention uses a water-based metallic paint to eliminate the effects of changes in the coating atmosphere on finish quality, thereby making it possible to achieve a metallic finish with excellent metallic feel, smoothness of the painted surface, glossy clarity, etc. It is something. Below, the paints used in the present invention and the method of finishing a metallic paint film using these will be explained in detail. (1) Non-metallic paint This paint aligns the metallic pigments in the water-based metallic paint film that is then formed uniformly and parallel to the painted surface without being affected by atmospheric humidity, and also makes the metallic painted surface smooth. It is an organic solution type or non-aqueous dispersion type thermosetting paint that is used for finishing purposes and does not contain flaky metallic pigments. In the present invention, the basic resin used in the non-metallic paint is a polyhydric carboxylic acid resin having an acid value of 5 to 100, and various known resins can be used as long as they satisfy these requirements.
Among them, the following resins can be cited as representative examples. () At least one carboxyl group-containing polymerizable unsaturated monomer such as the following group (A) and at least one polymerizable unsaturated monomer such as the group (C) that can be copolymerized therewith, and Acrylic resin or vinyl resin preferably having a number average molecular weight of about 5,000 to about 40,000, obtained by copolymerizing at least one hydroxyl group-containing polymerizable unsaturated monomer such as Group (B), if necessary. (A) α, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, etc.
β-ethylenically unsaturated carboxylic acid; (B) 2-hydroxyethyl acrylate, 2
- Acrylic acid or methacrylic acid having 1 to 8 carbon atoms, such as hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc.
(C)(1) Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, tert-butyl acrylate,
Acrylic acid or methacrylic acid having 1 carbon atom such as tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, decyl acrylate, etc. ~24 alkyl or cycloalkyl esters; (2) acrylamide, methacrylamide,
N-methylacrylamide, N-ethylmethacrylamide, diacetone acrylamide, N-methylolacrylamide, N-methylolmethacrylamide,
Functional acrylic or methacrylamide such as N-butoxymethylacrylamide; (3) Glycidyl group-containing vinyl monomers such as glycidyl acrylate, glycidyl methacrylamide, allyl glycidyl ether; (4) Styrene, vinyltoluene, vinyl propionate, α - Vinyl monomers such as methylstyrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl propionate, vinyl pivalate, Beoba monomer (Siel Chemicals); () ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, 2, Polyhydric alcohols such as 2-dimethylpropanediol, glycerin, trimethylolpropane, and pentaerythritol, monohydric alcohols used in combination as necessary, or monoepoxy compounds having one glycidyl group in the molecule. Name: Ciel Chemical Co., Ltd.
)” as the alcohol component, phthalic anhydride,
isophthalic acid, tetrahydrophthalic anhydride,
Polybasic acids such as hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, trimellitic anhydride, and pyromellitic anhydride, and monobasic acids such as benzoic acid and t-butylbenzoic acid used in combination as necessary. An oil-free alkyd resin formed by condensing the above alcohol component and the above acid component with a basic acid as the acid component, or castor oil, dehydrated castor oil, tung oil, safflower oil, large oil in addition to the above alcohol component and the above acid component. The oil component, which is one or a mixture of soybean oil, linseed oil, tall oil, coconut oil, etc., and one or more of these fatty acids, is added to the above acid component and alcohol component, and the three components are reacted. An oil-modified alkyd resin having a number average molecular weight of preferably 500 to 10,000. () A graft copolymer obtained by grafting an acrylic resin or a vinyl resin onto an alkyd resin, preferably having a number average molecular weight of about 5,000 to about
40,000, for example, vinyl monomer and/or alkyd resin with polymerizable unsaturated groups.
Or a graft copolymer obtained by reacting acrylic monomers. The acid value of the above polyhydric carboxylic acid resin is 5 to 100.
should be in the range of , preferably 10-50,
More preferably, it is in the range of 30 to 50. If the acid value of the resin is less than 5, the next applied water-based metallic paint will not be compatible with the resin, and the water-based metallic paint will not be effective in absorbing moisture, so the water-based metallic paint will not flow unevenly, sag, etc. Defects occur and the metallic feel of the paint film becomes significantly worse. Moreover, if the acid value is more than 100, the water resistance of the coating film will deteriorate, which is not preferable. In addition, the above-mentioned polycarboxylic acid resin can be made to contain hydroxyl groups by copolymerizing monomers such as the above-mentioned group (B), and when such a resin is used, coating film hardness, water resistance, and weather resistance are improved. Improves coating film performance. In this case, when the hydroxyl value of the resin is in the range of about 10 to about 200, a remarkable effect of improving coating film performance is observed, and the range of 25 to 70 is particularly preferred. Examples of basic substances that neutralize these polyhydric carboxylic acid resins include various basic substances such as ammonia, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, dimethylethanolamine, diethanolamine, and triethanolamine. can be used. The amount of the neutralizing agent used is generally about 0.1 to about 2.0 equivalents, particularly preferably about 0.3 to about 1.2 equivalents, based on the carboxyl group in the resin. If the amount of the neutralizing agent used is less than 0.1 equivalent, the next applied water-based metallic paint will not be compatible with the water-based metallic paint and will not have the effect of absorbing water from the water-based metallic paint, resulting in uneven flow and dripping of the water-based metallic paint. This causes defects such as, and the metallic feel of the coating film becomes significantly worse. Moreover, when the amount is more than 2.0 equivalent, the coating film performance deteriorates. The amino resin used in the present invention is a crosslinking agent for curing the polyhydric carboxylic acid resin, and various known crosslinking agents are used, such as melamine, benzoguanamine, triazine compounds, urea, dicyandiamide, formaldehyde, etc. Examples include those obtained by condensation or co-condensation of and modified with a modifier.
Among these, melamine formaldehyde resin is preferred. In addition, the blending ratio of the polyvalent carboxylic acid resin and the amino resin is usually about 50 to about 90 parts by weight of the polyvalent carboxylic acid resin based on the solid content weight, preferably about 65 to about 65 parts by weight from the viewpoint of coating film performance. About 85 parts by weight, amino resin: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight. In the present invention, the non-metallic paint is used as an organic solution type or non-aqueous dispersion type paint in which the above neutralized polyhydric carboxylic acid resin and amino resin are dissolved or dispersed in an organic solvent. The non-metallic paint can be an organic solution-type thermosetting paint or a non-aqueous dispersion-type thermosetting paint, but one of the purposes of the present invention is to prevent air pollution and save resources. From this point of view, it is preferable that the non-metallic paint is also a so-called high solids type paint in which the concentration of non-volatile matter at the time of coating is adjusted to about 35% by weight or more, particularly about 40 to about 60% by weight. Depending on the form of the non-metallic paint, examples of solvents to be used include ester solvents, ether solvents, alcohol solvents, amide solvents, ketone solvents, aliphatic hydrocarbon solvents, and aromatic hydrocarbon solvents. A solvent may be used. Furthermore, the above-mentioned non-metallic paints may contain coloring pigments, extender pigments, viscosity modifiers,
A coating surface conditioner etc. can be used. In the present invention, the non-metallic paint is
Although it can be applied directly to the object to be coated, it is also possible to apply a primer such as an electrodeposition paint (anionic type, cationic type) and a thermosetting intermediate paint, and then paint after curing these coatings. preferable. As the coating machine, it is preferable to use an atomization type coating machine, such as an air spray coating machine, an airless spray coating machine, an air atomization type or a rotary electrostatic coating machine, etc.
The viscosity of the paint during painting is approximately
It is preferably adjusted to 15 to about 60 seconds, especially 15 to 35 seconds (20℃), and the coating film thickness is about 2 to about 20μ, especially about 5 to about 15μ, based on the heat-cured film thickness.
is suitable. In the present invention, after coating the non-metallic paint, the viscosity of the non-metallic paint applied to the surface to be coated is 10 poise or more, preferably 20 to 100 poise,
(both at 20°C), a water-based metallic paint is applied onto the painted surface. If a water-based metallic paint is applied at a viscosity lower than 10 poise, the metallic paint will sag or the orientation of the metallic pigment will become non-uniform, which is not preferred. In the present invention, the viscosity of the applied non-metallic paint is measured by applying the non-metallic paint to a tin plate using the method described above (it is preferable to perform the painting under conditions as close to actual conditions as possible), and then applying the applied paint to a glass bottle. and collect it with a cone-and-plate viscometer at a shear rate of 10 sec ^-1.
This was done by reading the viscosity at . The viscosity of the applied non-metallic paint can be easily adjusted by appropriately adjusting the non-volatile content concentration, solvent composition, viscosity, etc. of the paint at the time of application, and the applied viscosity immediately after application is within the above range. If it is lower, it can be adjusted by leaving it at room temperature or preheating to volatilize the solvent. In order to shorten the coating interval between non-metallic paint and water-based metallic paint as much as possible, a viscosity modifier should be added to the non-metallic paint so that the coating viscosity of the non-metallic paint immediately after application is within the above range. and
Various known viscosity modifiers can be used as such viscosity modifiers. For example, Penton 27
(a thixotropic agent made by NL Chemical Co., Ltd.), and Erosil #200 (a silica-based thixotropic agent made by Nippon Aerosil Co., Ltd.). (2) Thermosetting water-based metallic paint The metallic paint is a paint that is applied onto a non-metallic paint film within the above-mentioned specific viscosity range, uses water as its main solvent, and is water-soluble or water-dispersible. thermosetting acrylic resin,
The main component is a metallic pigment, and if necessary, a coloring pigment, an extender pigment, a coating surface conditioner, a viscosity conditioner, etc. are added. As the water-soluble or water-dispersible acrylic resin which is a constituent component of the water-based metallic paint, all conventionally known ones are included. As a typical example, water-soluble acrylic resin,
Obtained by polymerizing one or more monomers selected from α,β-monoethylenically unsaturated carboxylic acids, their hydroxyalkyl esters, and other α,β-monoethylenically unsaturated monomers. Acid value of about 20 to about 100 and hydroxyl value of about 20 to about 200
Examples include acrylic resins. The polymerizable unsaturated monomers that are the raw materials for the water-soluble acrylic resin mentioned above include α,β monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, and acrylic acid 2
α, such as hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc.
Hydroxyalkyl esters of β-monoethylenically unsaturated carboxylic acids and methyl acrylate,
Ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methacrylic acid
Alkyl esters of α,β-monoethylenically unsaturated carboxylic acids such as iso-butyl, acrylamide derivatives such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetone acrylamide, glycidyl acrylate, etc. Glycidyl esters of α,β-monoethylenically unsaturated carboxylic acids, vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate, aromatic unsaturated monomers such as styrene, α-methylstyrene, and vinyltoluene. The body is used. The polymerization reaction is carried out using a radical polymerization catalyst such as azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, etc., in an organic solvent compatible with water such as butyl cellosolve. If the acid value of the resin is less than 20, it will be difficult to dissolve in water, and if it exceeds 100, the coating performance will deteriorate due to the influence of residual carboxyl groups. The water-soluble acrylic resin obtained in this way can be prepared using basic materials such as ammonia or amines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine, and dimethylaminoethanol, or alkali metal hydroxides such as potassium hydroxide and sodium hydroxide. Neutralize using substances. Thereafter, water and, if necessary, an organic solvent compatible with water are added to obtain a suitable solid content, and the mixture is diluted with water. On the other hand, the water-dispersible acrylic resin is produced by using an ionic or non-ionic or both low-molecular or high-molecular surfactant as a dispersion stabilizer, or by using a water-soluble resin. It is a known product prepared by emulsion polymerization of a polymerizable unsaturated monomer, which is a raw material for the resin, in an aqueous medium by a commonly known method. Water-soluble amino resins used as crosslinking agents for acrylic resins include those obtained by condensation or co-condensation of formaldehyde with melamine, benzoguanamine, triazine compounds, urea, dicyandiamide, etc.
_C1-8 denatured with _alcohol denaturant,
Carboxyl group-containing amino resins and the like are also used. Usually prepared by reacting about 0.5 to about 2.0 equivalents of formaldehyde with 1 equivalent of amino group in alkaline or acidic conditions using a pH regulator (e.g. ammonia, sodium hydroxide, amines) by a known method. be done. Preferred in the present invention is melamine formaldehyde resin. The acrylic resin component and amino resin component constituting the aqueous metallic paint of the present invention are suitably blended in the following proportions based on solid weight. When the components consist only of water-soluble acrylic resin: Acrylic resin component: about 50 to about 90 parts by weight, preferably about 65 to about 85 parts by weight Amino resin component: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight Parts by weight When a water-dispersible acrylic resin is used as a component, a water-soluble acrylic resin is also used at the same time, and the proportions are as follows. Water-dispersible acrylic resin component: about 10 to about 70 parts by weight, preferably about 20 to about 50 parts by weight Water-soluble acrylic resin component: about 10 to about 70 parts by weight, preferably about 30 to about 50 parts by weight Amino resin component: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight Known metallic pigments can be used, such as flaky pigments such as aluminum, copper, brass, mica-like iron oxide, bronze, and stainless steel. Metallic powder is mentioned, and the blending amount of these powders is 10% of the solid content of the thermosetting resin composition.
From about 1 to about 50 parts by weight per 0 parts by weight is preferred. The form of the water-based metallic paint is
An organic solvent solution type or a non-aqueous dispersion type is preferred. The water-based metallic paint can be applied in the same manner as the non-metallic paint, and has a viscosity of about 10 to about 40 seconds (20
C), and the coating film thickness is preferably about 5 to about 25 microns based on the heat-cured coating film. In the present invention, it is preferable that the non-metallic paint and the water-based metallic paint have compatibility, and specifically, some or all of the thermosetting resin compositions contained in both paints are common or similar. It is desirable that there is a novelty between the two, or even if they are different species. (3) Transparent thermosetting paint The transparent thermosetting paint (hereinafter referred to as "Top Coat")
(sometimes abbreviated as ) is a paint that forms a transparent coating film that is applied as the top layer coating on a high solid metallic coating surface. Therefore, it is preferable that the top coat forms a coating film with excellent gloss, weather resistance, acid resistance, alkali resistance, solvent resistance, and hot water resistance. Examples include organic solvent solution type or non-aqueous dispersion type paints in which the vehicle component is a thermosetting resin composition consisting of an amino resin (crosslinking agent), and furthermore, ultraviolet absorbers,
A coloring agent and the like may also be added as appropriate. Furthermore, from the viewpoint of preventing the occurrence of metallic unevenness, it is preferable to use a vehicle component of the top coat that has poor compatibility with the thermosetting resin composition contained in the water-based metallic paint. For example, for a system using acrylic resin as the basic resin, the difference between the solvability parameter (SP value) of the acrylic resin of the top coat and the SP value of the acrylic resin of the water-based metallic paint is about 0.1 to
Preferably it is about 1.0. From the viewpoint of pollution prevention and resource saving, which are one of the objectives of the present invention, the top coat is preferably of a high solid content type, and specifically, the non-volatile content concentration at the time of coating is approximately 35% by weight or more. , preferably about 40 to about 60% by weight, more preferably about 45 to about 60% by weight
It is desirable to adjust the content to approximately 60% by weight. Coating can be done in the same manner as the non-metallic paints, the viscosity during coating is adjusted to about 15 to about 60 seconds (20°C) using a #4 food cup, and the coating film thickness is about 100% based on the heat-cured coating. 5 to about 50μ is suitable. The metallic finish of the present invention is obtained by applying the above-mentioned non-metallic paint, water-based metallic paint, and top coat at a temperature of about 100 to about 180°C for about 15 to 15 minutes.
This is done by heating for approximately 45 minutes to simultaneously cure the three layers of coating. The metallic paint film finished in this way has a high level of non-volatile content when applied, but the metallic pigments are oriented parallel to the painted surface and uniformly (no metallic unevenness), and is smooth. The result is an excellent, high-sharp image. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Hereinafter referred to as "part" and "%"
Unless otherwise specified, "parts by weight" and "% by weight"
shows. Production example Basic resin solution production example (1) Production of acrylic resin solution A-1 Styrene 15 parts, methyl methacrylate 20 parts,
46 parts of ethyl acrylate, 15 parts of hydroxyethyl acrylate, and 4 parts of acrylic acid were polymerized in xylene using a polymerization initiator α-α'-azobisisobutyronitrile to obtain an acrylic resin solution A- with a resin content of 70%. I got 1. The number average molecular weight of the acrylic resin is about 20,000,
The acid value was 31.1. (2) Production of acrylic resin neutralization solution AN-1 To 100 parts of resin solid content of acrylic resin solution A-1, 5 parts of dimethylaminoethanol (neutralization equivalent: 1.01) was added to neutralize, and the mixture was neutralized with isobutyl alcohol. Acrylic resin neutralization solution with 50% resin content
AN-1 was obtained. (3) Production of polyester resin solution P-1 31 parts of neopentyl glycol, 7 parts of trimethylolpropane, 24 parts of phthalic anhydride, 17 parts of tetrahydrophthalic anhydride, 5 parts of trimellitic anhydride
and 15 parts of castor oil fatty acid were added to a reaction vessel and reacted at 200-230°C for 5 hours, then 8 parts of phthalic anhydride was added, further 8 parts of phthalic anhydride were added, and further 1 part of phthalic anhydride was added at 180°C. Let the time react,
A polyester resin with a molecular weight of 5600 and an acid value of 45 was obtained. 43 parts of xylene was added to 100 parts of the polyester resin to obtain a 70% polyester resin solution P-1. (4) Polyester resin neutralization solution Resin solid content of polyester resin solution P-1
7 parts dimethylaminoethanol per 100 parts
(neutralization equivalent: 0.98) to neutralize the solution, and isobutanol was added to obtain a 60% polyester resin neutralized solution PN-1. (5) Acrylic/polyester graft resin solution
Production of PA-1 Polyester resin solution P- obtained in (3) above
1 was further diluted with xylene to 33% concentration, and 35 parts of methyl methacrylate, 46 parts of ethyl acrylate, 15 parts of hydroxyethyl acrylate, and 4 parts of acrylic acid were added, and the polymerization initiator α,α'-azobisiso Graft polymerization was carried out using butyronitrile to obtain an acrylic/polyester graft resin solution PA-1 with a resin content of 50%. The resin acid value of this resin solution PA-1 was 38. (6) Production of neutralized acrylic/polyester graft resin solution PAN-1 6 parts of dimethylaminoethanol ( (neutralization equivalent: 1.00) and neutralized with isobutyl alcohol to obtain an acrylic/polyester graft resin neutralized solution PAN-1 with a resin concentration of 45%. (7) Production of water-soluble acrylic resin aqueous solution W-1 15 parts of styrene, 20 parts of methyl methacrylate,
25 parts of ethyl acrylate, butyl acrylate
20 parts of hydroxyethyl acrylate, 15 parts of acrylic acid, and 5 parts of acrylic acid were polymerized in butyl cellosolve using a polymerization initiator α,α'-azobisisobutyronitrile to obtain an acrylic resin solution with a resin content of 70%. Acrylic resin solution thus obtained
After adding 4.3 parts of dimethylaminoethanol to 100 parts, water was added to obtain a water-soluble acrylic resin aqueous solution W-1 with a concentration of 55%. (8) Production of water-dispersed acrylic resin dispersion W-2 Add 68.0 parts of deionized water, 0.2 parts of ammonium persulfate, and 1.5 parts of TritonX-200 to a reaction vessel.95
Heat to ℃. Separately, the following monomer composition: Styrene 15 parts Methyl methacrylate 85 parts Ethyl acrylate 33 parts Hydroxypropyl methacrylate 15 parts Acrylic acid 2.0 parts N-octyl mercaptan 0.6 parts Ammonium persulfate 0.4 parts TritonX-200 1.5 parts Emulgen 840S 1.0 parts Deionized water 53.0 parts Note Rohm & Haas Anionic surfactant Kao Atlas Nonionic surfactant is mixed to form an aqueous emulsion of acrylic monomer. Next, this aqueous emulsion was heated to the above 95°C.
dropwise over 3 hours into the solution heated to . Meanwhile, the temperature is maintained at 95°C. After the monomer addition is complete, the reaction mixture is held at 95° C. for about 2 hours under stirring, then allowed to cool to 35° C. and 0.5 parts dimethylethanolamine and 4 parts deionized water are added. In this way, a stable milky white dispersion W-2 of water-dispersed acrylic resin having a solid content of 45% was obtained. (9) Production of acrylic resin solution A-2 40 parts of cellosolve acetate was charged into an ordinary acrylic resin reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, etc., heated and stirred, and after reaching 135°C, the following The monomer mixture was added over a period of 3 hours. Methyl methacrylate 10 parts i-Butyl methacrylate 30 parts n-butyl methacrylate 12 parts 2-ethylhexyl methacrylate 20 parts 2-hydroxyethyl methacrylate 25 parts Methacrylic acid 3 parts Cellosolve acetate 50 parts α,α'-azobisisobutyronitrile 4 parts After adding the above monomer mixture, let the reaction continue for 1 hour.
Continue at 135°C, then add 10 parts of cellosolve acetate and α,α′-azobisisobutyronitrile.
A mixture consisting of 0.6 parts was added over a period of 1 hour and 30 minutes. After reacting for 2 hours, cellosolve acetate was distilled off under reduced pressure to make the resin concentration 65%.
was adjusted to produce acrylic resin solution A-2. The number average molecular weight of the resin component of acrylic resin solution A-2 (measured by vapor pressure osmosis method) is 6100,
The viscosity of the acrylic resin solution A-2 was Z ₂ (Gardner bubble viscosity, 25° C.). (10) Production of acrylic resin non-aqueous dispersion B 126 parts of melamine, 412 parts of butyl formaldehyde (40%), 190 parts of n-butanol, and 36 parts of xylene were charged into a reaction vessel, heated, and the distilled water was dissolved into water. After reacting for 7 hours while separating in a separator, the system was depressurized and 100 parts of distillate was removed, and then 50 parts of hydrocarbon solvent Cielsol 140 (product of Ciel Sekiyu Co., Ltd.) and 50 parts of n-heptane were added. part, resin content 60%, varnish viscosity J (Gardner bubble viscosity
A melamine resin solution was prepared at a temperature of 25°C. 58 parts of the above melamine resin solution, 30 parts of n-heptane
A reaction vessel was charged with 0.15 parts of benzoyl peroxide, heated to 95°C, and the following monomer mixture was added dropwise over a period of 3 hours. Styrene 15 parts Acrylonitrile 9 parts Methyl methacrylate 13 parts Methyl acrylate 15 parts N-Butyl methacrylate 1.8 parts 2-Hydroxyethyl methacrylate 10 parts Acrylic acid 1.2 parts Benzoyl peroxide 0.5 parts N-Butanol 5 parts Schierzol 140 30 parts N-Heptane 9 parts One hour after the completion of the dropwise addition of the monomer mixture, a mixture of 0.65 parts of t-butyl peroctoate and 3.5 parts of Cielzol 140 was added dropwise over 1 hour. After that, keep the temperature at 95℃ 2
Stirring was continued for an hour. Thereafter, 34 parts of the solvent was removed under reduced pressure to obtain an acrylic resin non-aqueous dispersion B having a resin content of 60% and a varnish viscosity of A (Gardner bubble viscosity). Paint manufacturing example (1) Non-metallic paint A 70% acrylic resin solution A-1 100 parts 88% Cymel 370 (melamine resin manufactured by Mitsui Toatsu Chemical Co., Ltd.) 34 parts Both of the above components were mixed, and then xylene was added. 40
30 copies of Swazol #1000 (Maruzen Oil Co., Ltd. product)
A mixed solvent consisting of 20 parts of ethyl acetate and 10 parts of isobutanol with a viscosity of 25 seconds (food cup #4/
(20°C). The nonvolatile content at this time was 45% by weight. (2) Non-metallic paint AN 140 parts of 50% acrylic resin solution AN-1 34 parts of 88% Cymel 370 were prepared in the same manner as in (1). (3) Non-metallic paint B 70% polyester resin solution P-1 100 parts 88% Cymel 370 34 parts Both of the above components were mixed uniformly, and then 30 parts of toluene, 35 parts of ethyl acetate, 10 parts of isobutyl alcohol, Swasol # Viscosity 30 seconds with a mixed solvent consisting of 15 parts of 1000 (Food Cup No. 4/20℃)
It was prepared as follows. The nonvolatile content at this time was 55% by weight. (4) Non-metallic paint 117 parts of BN 60% polyester resin solution PN-1 and 34 parts of 88% Cymel 370 were prepared in the same manner as in (3). (5) Water-based metallic paint M 55% water-soluble acrylic resin W-1 100 parts 45% water-dispersed acrylic resin W-2 45 parts 100% Cymel 350 25 parts The following aluminum paste dispersion is added to the mixture of each of the above components. Aluminum paste A (Toyo Aluminum Co., Ltd. product aluminum paste #4919) 10 parts Aluminum paste B (Toyo Aluminum Co., Ltd. product aluminum paste #55-519) 20 parts Isopropyl alcohol Mix 30 parts with water and reduce the viscosity to 16 seconds ( Food Cup No.
4/20°C). (6) Topcoat T Topcoat T was prepared by dispersion using acrylic resin solution A-2 with the following formulation. 65% acrylic resin solution A-2 108 parts 70% Yuban 20HS (Note 1) 43 parts 60% acrylic resin non-aqueous dispersion B 54 parts 1% Raybow No. 3 (Note 2) 0.1 part (Note 1) Mitsui Toatsu Melamine resin (Note 2) manufactured by Kagaku Co., Ltd. Silicone additive manufactured by Raybor Chemical Co., Ltd. Next, the above top coat was coated with a mixed solvent consisting of 35 parts of Naftesol #150, 35 parts of butyl cellosolve, and 30 parts of n-butanol to a viscosity of 35 seconds (Food Cup #1). The viscosity was adjusted to 4/20°C), and a top coat T with a solid content concentration of 53% was prepared. Example 1 Polybutadiene electrocoating paint was dried on a dull copper plate with a thickness of 0.8 mm and subjected to zinc phosphate chemical conversion treatment.
Electrodeposited to a thickness of 20μ, baked at 170℃ for 20 minutes, then sanded with #400 sandpaper and wiped with petroleum benzene to degrease. Next, I air-sprayed Surf Acer, an intermediate coating for automobiles, to a dry film thickness of approximately 25μ, and baked it at 140℃ for 30 minutes.
Sand with #400 sandpaper, drain and dry. Then, it is degreased with petroleum benzine and used as a material for testing. Next, in a painting booth with humidity adjusted to 60%, 75%, and 90%, the above-mentioned non-metallic paint AN was applied to the above-mentioned material using Minibell G (manufactured by Nippon Landsburg Co., Ltd., rotary electrostatic After applying the film to a dry film thickness of 5 to 10 μ using a paint sprayer and leaving it at room temperature for 2 minutes, the viscosity of the applied paint was 37 poise/20
℃), apply water-based metallic paint M using REA (manufactured by Nippon Landsburg Co., Ltd., electrostatic air spray) to a dry film thickness of 10 to 15 μm, and then leave it at room temperature for 3 minutes, then dry Top Coat C. Film thickness is 35~
Apply to a thickness of 40μ using Minibell G. After leaving it at room temperature for 10 minutes, use an electric hot air dryer.
It was heated and cured at 140°C for 30 minutes. Table 1 shows the appearance of the obtained coating film. Examples 2 and 3 The test materials used in Example 1 were coated with the paints of Examples 2 and 3 shown in Table 1 in the same manner as in Example 1, and cured by heating. The appearance of the obtained coating film is summarized in Table 1. Comparative Example 1 A water-based metallic paint was applied directly to the test material used in Example 1 using REA so that the dry film thickness was 10 to 15 μm, and after being left at room temperature for 3 minutes, Top Coat C was applied to the dry film thickness of 35 μm. Apply with Minibell G to a thickness of ~40μ. Thereafter, it was left at room temperature for 10 minutes, and then heated and cured at 140°C for 30 minutes in an electric hot air dryer to prepare a test coated plate of Comparative Example 1. Table 1 shows the appearance of the obtained coating film. Comparative Examples 2 to 5 The test materials used in Example 1 were coated with the paints shown in Table 1 in the same manner as in Example 1, and cured by heating. The appearance of the obtained coating film is summarized in Table 1.

【table】

【table】

Claims (1)

[Claims] 1. An organic solution type or non-aqueous dispersion type thermosetting paint that contains a neutralized polyhydric carboxylic acid resin having an acid value of 5 to 100 and an amino resin as essential components and does not contain metallic pigments is applied to the object to be coated. The clay of the applied paint is adjusted to 10 poise (20°C) or higher, a thermosetting water-based metallic paint is applied thereon, a transparent thermosetting paint is further applied, and then the above three-layered coating is applied. A metallic finishing method characterized by heating and curing the film at the same time.