JPS5874352A - Double-layer baked film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer baked coating film with improved interlayer adhesion of the coating film.

Conventionally, industrial paints and seven baking-type top coats were manufactured using autovjI1.
．． ! L % It is widely used for colored galvanized iron, light electrical appliances, fixtures and fittings, etc., and includes solid color paints, metallic color paints, clear paints, etc. These coating systems include a 1-coat, 1-bake type, and a 2-coat, 1-bake type, in which metallic caranie paint and clear paint are applied wet-on-wet and then baked. Recently, a painting method called two-tone color has been used from a design standpoint, but each paint may be the same paint or different types of paint. Furthermore, recently, on solid color coatings,
Alternatively, there is also an over clear coating method in which an additional clear coating film is formed on a two-coat, one-bake metallic clear coating film to improve the finished appearance and weather resistance.

In paint films that are finished by one-coat, one-bake type painting or two-coat, one-bath type painting, it is necessary to repair defects on the paint film. Generally, after adjusting the paint surface by sanding the defective area with sandpaper, repainting the defective area and its surrounding area or the entire surface using the same paint, and then adjusting it with wax or compound. In this way, in repair coatings, two-tone coatings, over-clear coatings, etc., a lower coating film (a coating film relative to an upper coating film, not necessarily a first layer coating film) formed from the same paint or a different type of paint.

It is inevitable that the upper coating film (hereinafter referred to as the primary coating film) and the upper coating film (hereinafter referred to as the secondary coating film) overlap (the secondary coating film is formed on the baked primary coating film).

There is almost no problem with the interlayer adhesion between the primary coating film and the secondary coating film in areas where the primary coating has been polished, etc., but delamination is likely to occur in unadjusted areas.

In other words, in areas where the primary coating has been adjusted by polishing, etc., contaminants on the coating surface are removed and a new coating surface is exposed, resulting in good adhesion and surface scratches, as well as an increase in surface area. As a result, the adhesion area increases and an anchoring effect of the secondary coating film to the scratched area is brought about, so interlayer adhesion hardly becomes a problem.

On the other hand, in the unadjusted areas of the primary coating film, the physical properties between the primary coating film and the secondary coating determine the interlayer adhesion;
Delamination is likely to occur regardless of whether the first and second coats are of the same type or different types. In the former case, the first coat is exposed to the air until it is repaired, so the painted surface is Surface properties such as surface tension change due to contamination, and since the primary coating is subjected to baking twice, including during repair, in the latter case (for example, 2 to When applied with paint or over clear coat), the paint film itself will adhere.

Furthermore, as is well known, the primary coating film is baked at a higher temperature and longer time than the standard baking conditions (hereinafter referred to as overbaking conditions), and the secondary coating film is baked under the standard baking conditions.
・If baked at lower temperature and/or shorter time conditions (hereinafter referred to as casting conditions), the interlayer adhesion of the coating will become even worse. Particularly in paint baking lines for industrial paints, objects to be coated may remain in the baking oven and be baked under overbaking conditions, and the secondary coating side is usually subjected to repair baking using an infrared lamp, etc. In many cases, it is baked for a short time on the line, so it may be a cast material condition. As described above, the difference in physical properties related to interlayer adhesion between the primary and secondary coatings under universal sliding conditions is greater than under standard baking conditions, resulting in poor interlayer adhesion. It will become. Another factor that can worsen the interlayer adhesion of a paint film is the environmental conditions when the paint for the second coat is applied on the first coat. For example, repair coatings applied in the winter are prone to interlayer delamination, but this is due to the low temperature and low humidity during the winter, which reduces the adsorption of water on the surface of the primary coating, resulting in van der Waalska bonding, which is mainly caused by hydrogen bonding forces. This is thought to be due to the fact that it becomes smaller.

Conventionally, the method of improving the interlayer adhesion of the paint film was to polish the entire surface of the primary paint film, but since it takes too much man-hours, in recent years only the necessary areas are polished, so the above-mentioned method is used for the unadjusted areas. The problem of adhesion remains, and countermeasures on the paint side have become necessary. Furthermore, heating and humidification using steam or the like is used as a countermeasure against low temperature and low humidity in winter, but this is not desirable from the standpoint of energy conservation.

As a measure to improve interlayer adhesion of paint films from the paint side, conventional methods have been to increase the amount of polar groups in the resin in the paint, such as hydroxyl groups and carboxyl groups, to increase Huss/der Waalska on the paint film surface. Although it is
As a result, polar groups remain in the coating film, and there is a risk that coating film performance such as water resistance and weather resistance will deteriorate.

In addition, as a countermeasure for adhesion under overbaking conditions between the primary coating film and the secondary coating film, the reactivity of the secondary coating film side is increased to bring the cohesive force closer to that of the primary coating film side. Acid catalysts such as phosphoric acid esters and para-toluene sulfonic acid are sometimes added to paints, but this can cause the paint to react and thicken during storage, and residual acid catalysts in the paint film can cause poor water resistance. undesirable.

The present invention has been made to solve the above-mentioned problems related to interlayer adhesion of baked paint films, and the gist thereof is that one type of paint film contains bentonites and organic bentonites selected from the group consisting of bentonites and organic bentonites. It consists in a multilayer baked coating film having at least one coating layer containing one or more types of additives.

The bentonites and organic bentonites used in the present invention are not particularly limited and may be any commercially available ones, such as Benton #38 and Benton #34 manufactured by National, Organite manufactured by Toyosun Yoko, Nisben, Examples include Bengel et al.

The additives used in the present invention may optionally contain other conventional additives such as inorganic silica, silicates such as finely divided silicic acid and diatoms.

The amount of the additive used in the present invention is usually 0.01 to 5% by weight, and in general, if it exceeds 5% by weight, it will lead to a decrease in the gloss and weather resistance of the top coat, and if it is less than 0.01% by weight, it will not be used in the present invention. However, it is difficult to achieve the objectives of the first term.

The above additives may be included in the primary coating side, or
It may be contained in both the primary coating film side and the secondary coating film side.

Furthermore, when the primary coating side is polished, the interlayer adhesion of the coating film is further improved.

The paints containing the above additives are not particularly limited, and include conventional baking-type top coat paints, such as alkyd/melamine type paints,
It may be any of solid color paints such as acrylic/melamine type paints, oil-free polyester/melamine type paints, oil-free polyester/isocyanate type paints, acrylic/insyanate type paints, metallic color paints, clear paints, etc.

The reason why the interlayer adhesion of the multilayer baked coating film according to the present invention is improved is not clear, but all of the above additives contain a large amount of oxygen atoms in their structures, so hydrogen between the primary coating film and the secondary coating film is It strengthens the bonding force and also has a higher rate of adsorption of moisture in the air than titanium dioxide or zinc oxide, so it is estimated that the van der Waals force between the coatings will increase and interlayer adhesion will be significantly improved. .

According to the present invention, all of the above-mentioned problems related to interlayer adhesion, which have conventionally been a concern in multilayer baked coatings, are solved.

The present invention will be explained below with reference to Examples and Comparative Examples.

All "parts" and "%" in the following description are based on weight.

■, Paint manufacturing example Paint 1 Alkyd varnish (“Betsukosol-1323” manufactured by Dainippon Ink Co., Ltd.) in a glass container (s o o cc) 14.3
Part, titanium oxide (rR-5NJ manufactured by Sakai Chemical Co., Ltd.) 80.
0 parts, Kijirole/n-butanol (weight ratio 4/1) 2
8.3 parts, and glass peas (1,5 bait Φ) ioo,
o parts were added, stirred uniformly, and dispersed for 1 hour. To this was added 68 parts of Betucosol-1323, 68 parts of melamine type paint ("Super Beckamine J-" manufactured by Nippon Reichhold Co., Ltd.).
820-60J) 35.5 parts and Kijirole/n-
14.7 parts of butanol (weight ratio 4/1) was added and dissolved to produce paint 1.

Paint 2 In a glass container (500cc), 14.3 parts of alkyd varnish (Petsukosol-1323-), titanium oxide (so and o parts of "R-5NJ" manufactured by Sakai Chemical Co., Ltd., organite (organic pentonite manufactured by Toyojun Yoko Co., Ltd.)) 2.4 parts, Kijirole/n-
28.3 parts of butanol (weight ratio 4/1) and 100.0 parts of glass peas (1.5wΦ) were charged, stirred uniformly, and then dispersed for 1 hour.
368.6 parts, Super Beckamine J-820-60 Fes 35.5 parts, and Kijirol/n-butanol (
14.7 parts (weight ratio 4/1) were added and dissolved to produce paint 2 (containing 1% organic bentonite).

Paint 3 Acridic 44-17 in a glass container (300CC)
9 FES (acrylic resin manufactured by Nippon Reichhold) 12
2 parts, 44 parts of Super Beckamine L-117-60 Fes (melamine resin manufactured by Nippon Reichhold), 0.6 parts of Modaflow (manufactured by Monsando), and 28 parts of Kijiroll.
0 parts were added and stirred uniformly to produce paint 3 (clear paint).

Paint 4 Acridic 44-17940 parts in a stainless steel container,
12 parts of Bengel (bentonite manufactured by Houjun Yoko Co., Ltd.), 48 parts of Kijiroll, and 1 glass bead for dispersion (1.5wΦ)
After adding 50 parts and dispersing for 1 hour, the glass beads were removed, and 500 parts of Acrydic 44-179 were added thereto and uniformly stirred to prepare a paste containing 2% bentonite.

8 parts of the paste was mixed into 3,100 parts of the paint and stirred uniformly to produce paint 4 (a clear paint containing 15% bentonite).

Paint 5 Apply Acridic 50-612 in the same way as paint 3.
(Acrylic Fes made by Nippon Reichhold Co., Ltd.) 122 copies, Super Beckamin L-117-60 Fes 44 copies,
Paint 5 (clear paint) was produced from 0.6 parts of Modaflow and 28.0 parts of Kijiroll. ,
1P Paint 6 In the same way as in the case of Paint 4, use Acrydic 50-61.
A paste containing 2% organic bentonite was prepared from 40 parts of Benton #38 (organic bentonite manufactured by National), 48 parts of Kijiroll, and 500 parts of Acrylic 50-612 varnish.

Paint 6 (a clear paint containing 0.3% organic bentonite) was prepared by mixing 20 parts of the paste, 7100 parts of the paint, and 606.0 parts of Sueta-Betsukamine L-117-60.

Paint 7 Acridic 47-71 in a glass container (300cc)
2 (Acrylic resin face made by Nippon Reichhold) 65
Department, Super Beckamin L-117-60 Fes 13.
6 parts of aluminum paste 1109MA (manufactured by Toyo Aluminum Co., Ltd.), 5.5 parts of n-butanol, 4.6 parts of n-butanol, 3 parts of ethyl acetate, 4 parts of butyl acetate, 3.4 parts of kijirole, and 0.5 parts of triethylamine. , 301, Bonma Hitoshi-
Paint 9 (metallic paint) was produced by stirring.

■Comparative Example 1 (Solid Color/Solid Color) Thinner [Xylol: Solvesso 150 (manufactured by Etsuso) = 7:3 (
Paint 1 (solid color paint) diluted to Ford Cup No. 4/20 seconds (paint liquid temperature 20°C) with weight ratio) was applied to test pieces (A, B, C and D) [commercially available J I
S, G3141 (5PCC-3 manufactured by Nippon Test Panel Co., Ltd.
D steel plate) was degreased and washed with Kijiroll, and then the solvent was wiped off using commercially available gauze.A primary coating film was applied to the piece using a commercially available cup gun under the conditions of 20°C and 75% RH using a normal coating method. After setting for 10 minutes until baking, test pieces A and B were baked at 140°C for 30 minutes, and test pieces C and D were baked at 160°C for 90 minutes.

Immediately after baking, the test piece was left in a container heated to %LH using silica gel at 20°C for 30 minutes, and at the same time the test piece was taken out and at the same time a second coat of the same paint as the first coat was applied on the unadjusted first coat. Painted as a film. Setting to 10
After running for 30 minutes, test pieces A and C were heated to 140°C for 30 minutes.
B and D were baked at 130° C. for 20 minutes, respectively, and then left in a room environment for 24 hours. The primary coating thickness and secondary coating thickness of the four test pieces were 35μ and 30μ, respectively.

The coating film was cross-cut at 14 intervals to create 100 squares, and a normal tape peeling test was conducted to evaluate the interlayer adhesion between the primary coating film and the secondary coating film. The results are shown in Table-1.

Example 1 (solid color/solid color) Comparative example 1
Test plates E, F, G, and H were prepared using paint 2 according to the procedure described in . The primary and secondary coating thicknesses were 35μ and 30μ, respectively.

The baking conditions for the coating film were as follows.

The interlayer adhesion of the coating film was evaluated in the same manner as in Comparative Example 1 for the obtained test plate. The results are shown in Table-1.

Comparative Example 2 (Clear/Clear) Thinner [Xylol: Solbetsuso 100 (manufactured by Kotsuso Co., Ltd.): Solbetsuso 150 = 70:15:15 (weight ratio)]
A test plate was prepared according to the procedure of Comparative Example 1 using Paint 3 diluted to Ford Cup No. 4/20 seconds 1 (solution temperature 20° C.). However, the baking conditions for the first and second coatings are 160℃, 90 minutes and 130℃, 20 minutes, respectively.
It was a minute.

Both the primary coating film thickness and the secondary coating film thickness were 30μ.

The interlayer adhesion of the coating film was evaluated in the same manner as in Comparative Example 1 for the obtained test plate. The results are shown in Table-1.

Example 2 (Clear/Clear) A test plate was prepared using Paint 4 according to the procedure of Comparative Example 2. Both the primary coating film thickness and the secondary coating film thickness were 30μ. The interlayer adhesion of the coating film was evaluated in the same manner as in Comparative Example 1 for the obtained test plate.

The results are shown in Table-1.

Table 1 8 Criteria: Ranking was done based on the number of peeled pieces out of 1100 squares according to the interlayer adhesion test.

0... 0'~5 0 6~2゜△ 21~4゜"'
41~60×
61-100■, Comparative Example 3 for improving interlayer adhesion between different types of paint films (solid color/metallic/clear) Paint 1 was used as the primary coating and painted under the same conditions as Comparative Example 1,
After baking at 160°C for 90 minutes, leave it in a container containing dry silica gel for 30 minutes, take it out, and immediately wash it with thinner (ethyl acetate: butyl acetate: xylene dicarbitol acetate = 20:20:40:, 20). Paint was applied according to the normal painting method using paint 7 (metallic paint) diluted to cup N04/15 seconds (paint liquid temperature 20°C), and after an interval of 3 minutes, the same clear paint as that prepared in Comparative Example 2 was applied. did. After setting 1
It was baked at 30°C for 20 minutes.

The primary coating thickness was 35μ, the secondary coating had a metallic coating thickness of 20μ, and a clear coating thickness of 30μ.

The interlayer adhesion of the coating film was evaluated in the same manner as Comparative Example 1, and the results are shown in Table 2.

Example 3 (Solid Color/Metallic Clear) The solid color used in Example 1 was used as the primary coating, and the metallic clear used in Comparative Example 3 was used as the secondary coating according to the procedure of Comparative Example 3. A test board was created.

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Comparative Example 4 (Clear/Clear) Paint 3 was used as the primary coating, and the clear paint color and conditions described in Comparative Example 2 were applied. After baking at 160°C for 90 minutes, the paint was placed in a container containing silica gel for 30 minutes. After being left to stand, it was immediately taken out and painted with Paint 5 according to the clear paint coating conditions, and after setting for 30 minutes, it was baked at 130° C. for 20 minutes to form a secondary paint film. Both the primary coating film thickness and the secondary coating film thickness were 30μ.

The interlayer adhesion of the coating film was evaluated in the same manner as Comparative Example 1, and the results are shown in Table 2.

Example 4 In accordance with the procedure of Comparative Example 4, a first coating film was formed using paint 4 (clear paint), a second coating film was formed using paint 6 (clear paint), and a test plate was prepared. Created.

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Comparative Example 5 Based on the procedure of Comparative Example 2, a first coating film was formed using Paint 3 (clear paint), and then a second coating film was formed using Paint 1 (solid color paint), and a test plate was prepared. It was created.

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Example 5 A test plate was prepared by forming a secondary coating film using Radcolor paint.

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Comparative Example 6 Based on the procedure of Comparative Example 3, a first coating film was formed using paint 1 (solid color paint), and a second coating film was then formed using paint 3 (clear paint), and a test plate was prepared. It was created.

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Example 6 A primary coating film was formed using paint 2 (solid color paint) in the same manner as in comparative example 6, and then paint 4 (j IJ
A test plate was prepared by forming a secondary coating film using a paint (Year paint).

The interlayer adhesion of the coating film was evaluated on the obtained test plate in the same manner as in Comparative Example 1, and the results are shown in Table 2.

Procedural amendment (spontaneous) 1. Indication of the case 1982 Patent Application No. 174147 52 Name of the invention Multi-layer baked coating 3. Person making the amendment Relationship to the case Patent applicant 4, Agent 5, Date of amendment order (Voluntary) 7. Contents of the addition (11, 11, 12, shell, line 4, "Paint 7" is corrected to "Paint 5."

(2) On page 12, line 5 from the bottom, there is a meeting called ``Paint 9.''
Revised to ``Paint 7''.

that's all

Claims (1)

[Claims] 1. At least one of the adjacent layers has a coating film containing one or more additives selected from the group consisting of bentonites and organic bentonites. Multi-layer baked coating. 2. The coating film according to item 1, wherein only the first coating film contains an additive. 3. The coating film according to item 1, wherein the first coating film and the second coating film contain an additive. 4. The coating film according to item 1, wherein the additive is organic bentonite. 5. The coating film according to item 1, containing 0.01 to 5% by weight of the additive.