JPS6024193B2 - Painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides solvent-based paints or water-based paints (hereinafter referred to as
It is also sometimes referred to as water-based paint.

) is spray-painted, and even when the paint film is dry, a box paint is applied to the unpainted area using a wet-on-wet method. Most of the current box coating paints are used as undercoat paints, but these military coating paints have a special effect on the smoothness of the intermediate coat or top coat and maintain stability during the box bathing. There are restrictions on the formulation composition, and therefore the anti-corrosion properties, especially the thread rust resistance, tend to be inferior to solvent-based anti-rust coatings and powder coatings with high pigment concentrations.

On the other hand, military uniform painting has the advantage of being able to coat every corner of objects with complex shapes, so it is usually used as a method to take advantage of this feature and improve the rust prevention ability compared to conventional methods. After applying water-based paints, solvent-based paints, etc. (higher pigment content and anti-corrosion pigments than box paints) by spraying, etc. to form a coating film, the unpainted areas are coated with a silver coating. There are ways to comprehensively improve coating performance. However, even with this method, the fin coating film does not completely adhere to the spray dust part when spraying water-based paint, etc., and it requires an additional step in the painting process.Furthermore, the regular coating paint does not contain crab coating paint. The phenomenon of re-dissolution of the coating surface due to washing water and physically attached paint has been observed, and the boundary between the water-based paint film and the exposed coating film is not coated uniformly, resulting in corrosion prevention. There is a problem of inferiority.
Therefore, the present inventors applied a wet-on-wet method to the coating process, and applied a resin that is the same or compatible with the resin component of the crab paint, which had limitations due to the formulation composition of conventional dew paints. We found that by selecting a water-based paint using a water-based paint, etc., we could match such a method, simplify the painting process, and achieve the goal of high corrosion resistance of the paint film.

That is, the present invention provides a coating method in which a solvent-based paint or water-based paint is applied to an object to be coated, and then the unpainted areas are coated with a coating, in which the resin component of the solvent-based paint or water-based paint is the same as the resin component of the military uniform paint. Or, it is compatible, and the re-dissolution rate when a coated plate coated with the unpainted part is immersed for 10 minutes at 80 qo is 1.
The present invention relates to a coating method characterized in that after applying a solvent-based paint or a water-based paint with a fin-depositing paint having a content of 5% (wt%) or less (the same applies hereinafter), a wet-on-wet coating is applied to unpainted areas. In this invention, the redissolution rate is determined using a magnetic stirrer using a test plate whose weight has been measured in advance, with a distance between electrodes of 15 mm in a glass or plastic crab bath, an electrode area ratio of 1:1, and an electrodeposition bath temperature of 3 mm. - Electrodeposit for about 8 minutes at a voltage that will give you the standard film thickness while stirring.

Also, record the amount of electricity at that time. Immediately thereafter, the exposed test plate was washed with water and baked under Fuji-semi ant-free conditions. We measured the weight of the coating film after the competition on this test board,
Let it be A (many). In addition, the re-dissolution test plate was coated with a hexagonal coating so that the amount of electricity was equalized under the above-mentioned welding conditions, and then the test plate was placed in a hexagonal bath with stirring stopped at 80 qo.
It is obtained by soaking for 10 minutes, then washing with water in the same manner, and soaking under standard conditions.

If the weight of this dawn coating film is B (evening), then the redissolution rate (%
) is represented by {(A-B)÷A}×100. Solvent-based paints used in the present invention include epoxy resin paints, acrylic resin paints, alkyl resin paints, polyester resin paints, urethane resin paints, and water-based paints such as acrylic resin paints, alkyd resin paints, Any of the various paints commonly used in practical use, such as polybutadiene paints, can be used, but in order to perform stable line painting, it is necessary that the tortoise coating be in a stable state. It must be the same as or compatible with the resin component of the military paint, and it must not have an adverse effect on the electrodeposition paint even if a small amount is dissolved in the electrodeposition bath.

In particular, unneutralized resin used in turtle coating is used as a vehicle component,
It is preferable to use a paint made from this material with a high antirust effect. Such a paint is applied to the object to be coated by a known painting method such as spray painting. In the present invention, after a water-based paint or the like is applied to an object to be coated, the object to be coated is directly introduced into a fin bath using a wet-on-wet method, and the fin coating portion is exposed to paint. In this case, it is undesirable for the solvent in the water-based paint or solvent-based paint to gradually remain in the draught bath, so please allow sufficient setting time (for example, 10 to 20 minutes). It is preferable to introduce it into the electrodeposited layer after The electrocoating paint used is an anionic or cationic type that is commonly used in practice, but the resin component of the electrocoating paint must be the same as or compatible with the resin component of the solvent-based paint or water-based paint. is necessary.

In addition, ordinary anionic or cationic paints are
The coating film that is formed immediately after adhesion is usually about 35 to 50%
It has a redissolution rate of at least about 20%. With fin coatings that have such a high re-dissolution rate, the flea coating film formed at the boundary between the water-based paint film and the electroplated coating is pulled up from the electroplating bath and the electroplated coating. After being removed, the frayed paint film will be remelted due to the physically adhered box paint.
Additionally, during the rinsing process with ultrafiltration furnace liquid or dew-washing water that contains dry-adhesive paint, re-dissolution of the deposited paint film occurs, resulting in areas with a thin coat or no coating at all. Poor purulence performance (especially corrosion resistance). Therefore, in the present invention, the re-dissolution rate of the tortoise coating film is determined by the type of neutralizing agent in the tortoise coating and its blending amount (neutralization equivalent).
, 15% or less, by changing the resin acid value or resin base value, the molecular weight of the resin, the type of solvent and its blending amount, etc.
Preferably, it is essential that it be 10% or less. Among these, a particularly effective means is selection of the type and amount of the neutralizing agent. In the case of anionic adhesion paints, the types of neutralizers used are alkylamine compounds such as trimethylamine, diethylamine, and triethylamine, and potassium hydroxide, rather than alkanolamine compounds such as monoethanolamine, diethanolamine, and triethanolamine. gives better results. Further, the amount of the neutralizing agent to be blended has a particularly large contribution to the redissolution rate, and the smaller the amount to be blended, the more effective it is in reducing the redissolution rate. In the case of ordinary anion-type electrodeposition paints, the neutralization equivalent in the formulation of the neutralizing agent is relatively high due to the box deposition characteristics, workability, etc., for example, the resin acid value is 50 to 1.
In the case of resins for pigmented coatings of about 0.00, the amount is practically used in the range of about 0.8 to 1.2 equivalents, but in the present invention, it is preferable that this is better and lower, and about 0.4 to 0.6 equivalents are used. Appropriate. In the case of cationic electrodeposition paints, organic substances such as acetic acid, hydroxyl acetic acid, propionic acid, butyric acid, and succinic acid, as well as inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, can be used as neutralizing agents. However, hydroxyl acetic acid, acetic acid, etc. give good results.

The blending amount of the neutralizing agent has a large influence on the redissolution rate, and in order to reduce the redissolution rate, it is better to have a smaller blending amount. In ordinary cationic electrodeposition paints, the neutralization equivalent in the formulation of neutralizing agents, such as electrodeposition properties and tortoise workability, is relatively high. 0.8 ~]
．． A range of 2 equivalents is considered appropriate, but in the present invention, lower amounts are preferred, and approximately 0.1 to 0.5 equivalents are appropriate.

In either anionic or cationic type dew coating, if the redissolution rate of the electrodeposited coating is 15% or more,
Corrosion resistance tends to decrease at the boundary with a paint film such as a water-based paint, which is not in accordance with the purpose of the present invention.

As described above, in the case of painting by the method of the present invention, even if the electrocoating paint physically adheres to the paint film part of the water-based paint, etc., it does not form a film and the adhered paint is removed during the water washing process. It can be removed with

In addition, the anti-fouling paint is applied to the unpainted areas or the thin areas where the spray dust has been applied. Furthermore, since the wet-on-wet method is used, even if a small part of the paint film of water-based paint or the like peels off due to physical causes such as collision during line transfer, that part can be covered by box painting. In addition, since the electrocoating paint used has a low remelting rate, the helmet coating film applied to the boundary area is not redissolved during the normal washing process, etc., and a sufficient coating film is formed at the boundary area. It is possible to significantly improve coating film performance, especially corrosion resistance. In addition,
It is of course possible to apply a finishing coat after the coating according to the present invention, if necessary. Next, the present invention will be explained with reference to Examples and Comparative Examples.

Parts indicate parts by weight. Example 1 Using a polyptadiene paint *1 as a solvent-based paint and a polybutadiene-based electrodeposition paint *2 (anionic type) as a haze coating, the solvent-based paint was spray-painted in the steps shown in Table 1, and then the coating film was A salt water mist test was conducted on the coated plate obtained by applying a turtle coating in an uncured state using a wet-on-wet method and spraying and washing with ultrafiltration furnace liquid for 2 minutes.

Table 2 shows the mysterious results. Table 1 *1 Composition of solvent-based polybutadiene paint Polybutadiene used in electrodeposition paint *2 (unneutralized) 10 Guo Titanium White 50 Zinc White
40 carbon black
0.5 Rust preventive pigment (strontium chromate) 10 Solvent (xylolbutyl cellosolve/butanol = 7/2/1) 150 350.5 were dispersed in a ball mill for 2 feeding hours.

*2 Combination composition of military uniform paint polybutadiene-based paint Manufactured by Kansai Paint Co., Ltd., Elekron M. 6500, acid value 100,
Triethylamine 0.55 equivalent neutralized varnish resin content 1
0 parts, titanium white 20 parts, baryta 15 parts, strontium chromate 0.3 parts, carbon black 0.5 parts
The mixture was dispersed in a ball mill for 2 hours, and then deionized water was added to adjust the heating residue to 12%.

Note that the redissolution rate of the electrodeposited coating film of this turtle-deposited paint was 7%. Example 3 Using an epoxy paint*3 as the solvent-based paint and an epoxy-based polyamino electrodeposition paint (anion type) as the electrodeposition paint, the solvent-based paint was spray-painted in the steps shown in Table 3, and then the coating was finished. A salt water mist test was conducted on the coated plate obtained by applying a fin coating using a wet-on-wet method with a hard coating and spraying it with ultrafiltration furnace solution for 2 minutes.

The test results are shown in Table 2. Table 3 *3 Compounding composition of solvent-based epoxy paint Epoxy resin used for crab paint *4 / Butyl Cellosolve / Butanol = 6/2
/2 was added and dispersed in a bevel mill to make the nonvolatile content 55%.

*4 Compounding composition of epoxy-based polyamino paint for haze coating Kansai Paint Co., Ltd., Elekron M. 9000 epoxy-based PoI
Blend 100 parts of J amino varnish (resin base number 80, neutralization equivalent with hydroxyl acetic acid 0.3), 20 parts of titanium white, and 5 parts of clay, disperse in a ball mill between 2 coats, and then heat the residue to 12%. Adjustments were made by adding deionized water.

The redissolution rate of the exposed coating film of this electrodeposition paint was 4%. Example 3 In Example 1, a water-removable maleated acrylic paint *5 was used instead of the solvent-based paint.

Other conditions were the same as in Example 2. The test results are shown in Table 2. *5 The composition of the water-soluble maleated acrylic paint was added and dispersed for 2 calm hours in a Bepul mill, and this was diluted with deionized water to adjust the viscosity at the time of painting.

In addition, when the resin component *5 and the resin component *2 were mixed, they fell out uniformly. Comparative Example Example 1 was carried out under the same conditions as in Example 1 except that the neutralization equivalent of the tortoise coating was 0.80. In this case, the redissolution rate of the military coating of the box coating was 35%. Ta.

Table 2 Note) Salt spray resistance According to JISZ 2371 constant water loss core fog test.

Claims (1)

[Claims] 1 In a painting method in which a solvent-based paint or water-based paint is spray-painted on the object to be painted, and then electrodeposition is applied to the unpainted areas.
The resin component of the solvent-based paint or the water-based paint is the same as or compatible with the resin component of the electrodeposition paint, and the coated plate coated with the electrodeposition on the unpainted area is placed in an electrodeposition bath at 30°C. The redissolution rate when immersed for 10 minutes in
A coating method characterized in that after coating the solvent-based paint or the water-based paint, an electrodeposition paint having an amount of 5% by weight or less is applied wet-on-wet to an unpainted area.