JPH02144171A - Coating method - Google Patents

Abstract

PURPOSE:To make finish appearance of both a vertical part and a horizontal part especially good while utilizing single coating material by spray-coating the horizontal part and the vertical part with coating material for coating the vertical part and also performing coating of the horizontal part while mixing the above coating material with an atomized organic solvent. CONSTITUTION:In the case of coating a material having a horizontal part and a vertical part to be coated, the above both parts are spray-coated with coating material for coating the vertical part. As this coating material for coating the vertical part, for example, yield stress of the coated coating material liquid is preferably regulated to >=0.2dyne/cm<2>. Coating of the horizontal part is performed while mixing this coating material with an atomized organic solvent. This atomized organic solvent is excellent in compatibility with the atomized particles of this coating material and desirably contains the organic solvent having >=140 deg.C b.p. as a main component. For example, ethylene glycol monoisopropyl ether is utilized. As a result, both parts are finished to the coated surface especially good in finish appearance such as smoothness/brightness and luster by utilizing single coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating a workpiece having both horizontal and vertical parts, and more specifically, the present invention relates to a method for painting a workpiece having both horizontal and vertical parts, and more specifically, uses a single paint to coat both parts with smoothness, sharpness, and gloss. The present invention relates to a coating method capable of finishing a painted surface with a particularly good finished appearance.

When painting exterior panels (mainly metal, plastic, etc.) of automobiles (including buses, trucks, autopipes, etc.), household metal products, metal processed products, etc., there is a strong demand for excellent finished appearance. However, these outer panels coexist with a horizontal portion and a vertical portion, and it has been difficult to spray-paint both portions with a single paint to the same extent and with a good finished appearance. In other words, in general, the applied paint on vertical parts tends to partially flow down during setting and baking, resulting in thin areas or puddles in the paint film (sagging), which tends to reduce the finished appearance, especially the smoothness. To prevent this, anti-sagging agents are added or the viscosity is increased, but if paint adjusted in this way is applied directly to horizontal areas, it suppresses fluidity, resulting in the formation of minute uneven surfaces. On the other hand, paint adjusted to give a good finish on horizontal areas tends to flow, and when painted on vertical areas, the above-mentioned defects occur. At present, there is no established method for finishing horizontal and vertical sections to the same degree and with excellent finished appearance using one paint.

It is also known to paint the horizontal and vertical parts with a single paint while rotating the object, but this requires large equipment to rotate the object, and the painting line suddenly stops. Then, most of the objects to be coated existing in the line from the middle of painting to just before the coating film hardens have defects such as the risk of deterioration of the finished appearance of the coating.

Furthermore, the vertical part and the horizontal part are respectively adapted to 2f.
It is possible to paint with more than one paint, but 2 f
This method is undesirable because it requires the preparation of one or more paints, the painting process becomes complicated, the cost of equipment such as circulation increases, and maintenance is difficult.

The purpose of the present invention is to eliminate the above-mentioned various defects, and its characteristics are: (1) A single paint is used to paint horizontal and vertical parts; (2) The paint works well when applied to vertical parts. It is prepared so that a finished painted surface can be obtained; The above objects have been fully achieved and the present invention has been completed.

That is, when painting an object having a horizontal portion and a vertical portion, the present invention spray-paints both portions with a paint for painting the vertical portion, and coats the horizontal portion with an n-containing organic solvent. The present invention relates to a coating method characterized in that the coating is carried out while mixing.

The objects to be coated that can be coated by the method of the present invention are objects that have both vertical and horizontal parts, and specifically include the exterior panels of the above-mentioned automobiles, home appliances, and office equipment. For products where it is important to paint surfaces with excellent appearance, such as smoothness, sharpness, and gloss,
It is preferable to apply this method. Here, the vertical portion is an extension line of the surface to be coated based on the state in which the surface to be coated is placed or suspended from the painting process to the drying (baking) process of the coating film. In principle, the angle between the plane and the horizontal plane is within the range of 40 to 140 degrees. If this angle is 90 degrees, the surface to be coated will be perpendicular to the horizontal plane (it will be vertical).The horizontal part of the surface to be coated will be at an angle outside the above range.In addition, if the surface is curved, the tangent line will be If the angle with the horizontal plane is within the range of 50 to 130 degrees, it is a vertical part, and outside this range, it is basically a horizontal part.A flat part and a curved part may coexist on the object to be coated.

The paint used in the present invention is a well-known organic solvent-based liquid paint that can form a coating film with excellent smoothness, sharpness, and gloss on the vertical portion of the object to be coated. The form is preferably a solution type or a non-aqueous dispersion type, and any of clear paint, colored paint, or metallic paint may be used.

The main components of this paint are a base resin and an organic solvent.
Further, if necessary, a curing agent, a coloring pigment, a metallic pigment, a physical additive, a flow regulator, an anti-settling agent, a surface regulator, an ultraviolet absorber, etc. are appropriately blended. As the base resin,
For example, acrylic resins, polyester resins, alkyd resins, or modified resins thereof are preferably used, and the curing agent is preferably an amino resin or a block polyisocyanate compound, but is not limited to these.

What is particularly important about this paint is that it has the ability to form a coating film with an excellent finished appearance when applied to vertical areas. It is preferable to control the fluidity of the applied coating liquid, for example, the yield stress of the applied coating liquid is 0 or 2.
It is preferable to adjust it to dyne/cm" or more.

These adjustments may be made by, for example, adding a fluidity regulator to the paint or controlling the balance of organic solvent components in the paint, but are not limited to these. Specifically, as the fluidity adjusting agent, those described in JP-A-53-67733 are preferably used, and aliphatic, cycloaliphatic and aromatic diisocyanates (for example, hexamethylene- 1,6
-diisocyanate, tolylene diisocyanate, etc.)
and a monoamine or hydroxy monoamine having 1 to 5 carbon atoms (for example, benzylamine, propylamine, tertiary butylamine, 2-amylethanol) (diurea type thixotropy imparting agent). In addition, regarding the balance of organic solvents in the paint, it is important to ensure that organic solvents with different boiling points and vapor pressures have good coating workability, and that the applied coating liquid has an appropriate viscosity within the above-mentioned range ( (yield value).

In the method of the present invention, the paint is applied to both the vertical and horizontal parts of the object without changing their composition.

For painting, conventional spray painting methods can be used, such as air spray, airless spray, electrostatic air spray,
Paint using an electrostatic airless sprayer, electrostatic rotary atomizer, etc. The viscosity of the paint during painting is preferably in the range of 10 to 45 seconds for Ford Cup No. 014 at 20°C.

When vertical and horizontal areas are spray-painted with this paint, it is possible to finish the vertical areas with excellent paint surfaces such as clarity, smoothness, and gloss, but the fluidity of the applied paint is low. The finished appearance of the horizontal portions is not satisfactory. Therefore, in the present invention, when painting the horizontal portions, it is necessary to spray the paint while spraying an organic solvent.

That is, the organic solvent to be sprayed has excellent compatibility with the spray particles of the paint and has a boiling point of 140° C. or higher, preferably 150° C. or higher, and more preferably 160° C. or higher, as a main component. Examples of such organic solvents include Swab Rule #310. Suwasol #1000. Suwasol #1500. Suwazol #1800 (all of the above are Cosmo Oil brand names, hydrocarbon solvents), ethylene glycol monoisopropyl ether (isopropyl cellosolve), 5-butyl ether on ethylene glycol (butyl cellosolve), 3-
Methoxybutyl acetate, diethyl glycol monoethyl ether (carpitol), diethylene glycol monobutyl ether (butylcarpitol), diethylene glycol monoethyl acetate (carpitol acetate), 2-ethylhexyl alcohol, methylcyclol\quizanol, etc. These can be used alone or in combination of two or more. The organic solvent may have insufficient compatibility with the paint or have a boiling point of 1.
If the temperature is lower than 40°C, evaporation during spraying will be significant and the purpose of the present invention cannot be achieved.
Other organic solvents such as n-butanol, iso-butanol, etc. below 0.degree. C. may be contained within a range that does not impede achievement of the objectives of the present invention.

Spraying of the organic solvent can be carried out in the same manner as for the above-mentioned paint, and the amount of spraying can be arbitrarily selected depending on the purpose. A range of 50% by weight, preferably 3-30% by weight, more preferably 5-20% by weight is suitable.

It is preferable that the coating of the object having a vertical portion and a horizontal portion according to the present invention is carried out as follows.

First, the vertical portions are coated with the above-mentioned paint (sometimes by spray painting by already known methods,
It is possible to finish the painted surface with excellent image clarity, smoothness, and gloss.

On the other hand, the same paint is also used for painting horizontal areas, but this is different from painting vertical areas in that it is also sprayed with an organic solvent. In other words, one or more coating machines ("painting guns") for spraying paint and one or more coating machines ("spraying guns") for spraying solvent should be installed separately at the tip of the coating gun. It goes without saying that the spray gun should be aimed at the target surface to be coated, and there are no particular restrictions on the direction of the spray gun tip, but it is preferable that the spray gun should be facing the target surface. Although the organic solvent is sprayed separately, it is preferable to spray the organic solvent uniformly into the paint particles that are being sprayed.
Preferably, the spray patterns of both the solvent and the solvent are nearly or completely identical and overlap, so that
Both particles are applied to the surface to be coated in a uniformly mixed state, and the fluidity of the coating liquid is improved, and the sharpness, smoothness, gloss, etc. of the finished coated surface are improved to the same extent as those of the vertical portion. In other words, it is necessary that the coating liquid applied to the horizontal portion be uniformly mixed with the organic solvent sprayed separately.

Therefore, even if the organic solvent is sprayed before or after the paint is sprayed, the purpose of the present invention cannot be achieved because it is difficult to uniformly mix both solvents.

By the method of the present invention, it has become possible to finish a coated object having both a vertical portion and a horizontal portion with a single paint into a coated surface with excellent image clarity, smoothness, and gloss. Moreover, in adopting this method, there is no need to make major changes to existing equipment, and furthermore, even if the painting line suddenly stops, damage can be minimized.

Examples and Comparative Examples A metal box-shaped container (all angles are 90 degrees cube) coated with electrodeposited brimer and intermediate paint is placed on a stand, and the horizontal and vertical parts of the outer surface are coated with metallic base paint. (Note 1) was applied using an electrostatic air spray gun (REA gun, manufactured by Nippon Ransburg Co., Ltd.) at a rate of 15±
I painted it to a thickness of 2μ, left it at room temperature for 3 minutes, and then painted the vertical and horizontal parts with clear paint.

That is, clear paints (I) to (III) are applied to the vertical portions.
) Only (Note 2) was coated with a spray coating machine (Minibell, manufactured by Nippon Ransburg Co., Ltd.) to a thickness of 40±3μ based on the cured coating. On the other hand, on the horizontal part, clear paint (I
) to (III) (same as above) and an organic solvent sprayer (W-71, manufactured by Iwata Painting Machine Co., Ltd.) are installed separately, and most of the spray particles of mFl and solvent are mixed from each of them. I sprayed it on the surface to be coated and painted the horizontal areas. The coating film thickness was 40±3μ based on the cured coating. Both coatings were then cured by heating at 140° C. for 30 minutes. The composition of the organic solvent used in the above clear coating, the ratio of the solvent to the clear coating during spray coating, and the condition of the finished coating are shown in Table 2. All percentages and percentages are by weight.

(Note 1) Metallic base paint 50% acrylic resin liquid A (medium-11110 parts 60% kneepan 20SE-60f city-2) 42 parts 45% acrylic resin non-aqueous dispersion (*-3) 44 parts aluminum paste (umbrella- 4) 20 part Benton #2
7 (Medium-5) 1 part The above mixture was mixed with a mixed solvent consisting of 30 parts of toluene, 30 parts of ethyl acetate, 10 parts of isobutyl alcohol, and 30 parts of Swasol #1O0000 to a viscosity of 13 seconds (Ford Cup No. 4/20°C). Adjusted to.

(◆-1) 50% acrylic (M fat A methyl methacrylate 30 parts, ethyl acrylate
35 parts, n-butyl acrylate 24 parts, bitroxyethyl acrylate 10 parts, and acrylic acid 1 part were mixed with xylene/! using a polymerization initiator α, α′-azobisisobutyronitrile. ] - Acrylic resin liquid (medium-2) with a weight average molecular weight of 4,130,000 and a resin solid content of 50%, polymerized in a mixed solvent of butanol 80/20 (medium-2) 60% Kneepan 20SE-60, a product manufactured by Mitsui Toatsu Chemical Co., Ltd. Name, butanol-modified melamine formaldehyde IM in intestinal fluid i - 3145% acrylic resin non-aqueous dispersion of adduct of poly-12-hydroxystearic acid (hexamer) and glycidyl methacrylate in n-hebutane solution, 98 parts of methyl methacrylate , 1 part of glycidyl methacrylate,
Milky white acrylic resin non-aqueous dispersion obtained by heterogeneously polymerizing 1 part of methacrylic acid and then cross-linking the particle portion by adding dimethylaminoethanol (Book-4) Aluminum Paste Manufactured by Toyo Aluminum Co., Ltd., Aluminum Paste #55 -519 (ψ-5) Bentone #27 Manufactured by NL Chemical Co., thixotropy imparting agent (Note 2) Clear paint (I) ~ (In) 50% acrylic resin liquid B
(*-41l OO part 60% knee pants 20SE-60(
Reference-2) 50 copies 1% Raybo No. 3 (*-81
The clear varnish obtained by stirring 0.3 parts was diluted with the diluting solvent shown in Table 1.

(Medium-6) 50% acrylic resin liquid B 10 parts of styrene, 30 parts of isobutyl methacrylate,
Weight average molecular weight 10 obtained in the same manner as above in a xylene solution of 12 parts of n-butyl methacrylate, 25 parts of 2-ethylhexyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate and 3 parts of meccrylic acid.
,000, IM Acrylic with 50% fat content (M Intestinal fluid f city-7150% Diudiureaxotropy imparting agent, xamethylene diisocyanate and benzylamine above 5
Diurea-type thixotropy imparted (Syn-8) obtained by reacting in 0% acrylic resin liquid B. 1% Raybow Mumen, manufactured by Raybow Chemical Co., Ltd. Composition of silicone additives Table 1 Clear paint (I) to (II+) (Amount (parts) per 100 parts of Naka-91 clear varnish.

(◆-101 organic solvent (a): Swazol #1500 (b) Swazol #1500/carpitol acetate-1
-=80/20 (c) Xylene (*-111 Organic solvent spray amount Number of parts f* for clear coating rI spray 71j 1100 parts
-121P G D value Measured using a Gd meter manufactured by Japan Color IJF Institute rJclII-GGD-166.

1-13) ICM (Direct) Measurement was carried out using "Image Clarity Measuring Machine" manufactured by Suga Test Instruments ■.

Claims (1)

[Claims] When painting an object that has horizontal and vertical parts, spray paint both parts with a paint for vertical parts,
A coating method characterized in that the horizontal portion is coated while being mixed with an atomized organic solvent.