JPS63162073A - Method for coating metal - Google Patents

Abstract

PURPOSE:To form a coated film having excellent toughness, etc., on a metal, by mixing a solvent, a ladder silicone oligomer, and the alkyl ester or phenyl ester of phthalic acid, etc., in a specified ratio, coating the mixture on the metal, and curing the mixture under specified conditions. CONSTITUTION:A coating agent of (A) a solvent, (B) a ladder silicone oligomer, and (C) the alkyl ester (where 1-4 alkyl group is used) or phenyl ester of phthalic acid, adipic acid, sabacic acid, citric acid, maleic acid, fumaric acid, or phosphric acid and wherein the mixing weight ratio of (B)/(C) is controlled to 100/(5-130) is coated on the bendable material, and the agent is precured at <=140 deg.C and then completely cured at >=150 deg.C after bending. As a result, the adhesion to the metal is improved, and a coated film having excellent surface hardness, heat resistance, and toughness and without being cracked at the bend when the metal is bent is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a method for forming a coating film that has excellent adhesion to metal and is tough and heat resistant even after two bending processes. The present invention relates to a method of coating metals that can be bent, and particularly to a method of coating metals that is effectively used for coating machinery, electrical and electronic equipment, vehicles, etc. for exploding.

[Conventional technology]

Ladder-type silicone oligomers are compounds that generally have a structure represented by the following general formula (1), and are well dissolved in a solvent, become three-dimensional by heating, and form a hard, heat-resistant coating film.

RRR (In the formula, R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an optionally substituted phenyl group, a hydroxyl group, or an alkoxyl group. However, among all R, hydroxyl is The paint film formed from oligomers is brittle, and has the disadvantage that cracks tend to form at the bends, especially when applied to metal and bent. Conventionally, coating agents made by adding nylon, alkyd resin, etc. to ladder-type/recone oligomers have been investigated, but these have not been fully satisfactory in preventing cracks from occurring at bent portions.

[Problem that the invention seeks to solve]

An object of the present invention is to overcome the drawbacks of the conventional ladder-type silicone oligomers, to have good adhesion to metals, to have excellent surface hardness, heat resistance, and toughness to metals, and to be able to bend easily when bent. The object of the present invention is to provide a complete method for coating metal that provides a crack-free coating.

[Failure to solve the problem]

The present invention provides a metal coating method that can achieve the above object.

That is, the present invention provides (A) a solvent, (B) a ladder-type silicone.
/ oligomer and (C)7 alkyl ester of talic acid, adipic acid, sebacic acid, citric acid, maleic acid, fumaric acid or phosphoric acid (provided that the number of carbon atoms in the alkyl group is 1)
~4. ) or phenyl ester, and the mixing ratio of (B) to (C) is 100:5 by weight.
After applying a coating agent of ~130 to a metal that can be bent, pre-curing is performed at a temperature of 140°C or less, followed by 9-fold bending, and then completely curing at a temperature of 150°C or higher. The present invention relates to a metal coating method characterized by the following.

The metal coating method of the present invention will be explained below.

Generally, when a coating film is made by mixing a ladder-type silicone oligomer and a plasticizer, phase separation occurs during drying or heat curing due to poor miscibility between the ladder-type silicone oligomer and the plasticizer. The agent leaches to the surface and the coating becomes sticky.

Therefore, it is generally not done to soften ladder-type silicone oligomers by mixing a plasticizer with them.

However, the present inventors have discovered that heptalic acid, adipic acid,
Sebacic acid, citric acid, maleic acid, fumaric acid, or phosphoric acid alkyl ester or phenyl ester is mixed with a ladder-type silicone oligomer in a specific ratio, and this is applied to a bendable metal and cured under specific conditions. It has been found that a coating film with excellent performance in terms of surface hardness, heat resistance, toughness, etc. can be obtained, and a coated product can be obtained that does not generate cracks at the bent portion even after bending.

Compounds other than alkyl esters or phenyl esters of the above acids, such as dioctyl phthalate, dioctyl phthalate, didecyl phthalate, dilauryl phthalate, trioctyl phosphate, nooctylanobate, nooctyl sebacate, dioctyl maleate,
If compounds such as dioctyl fumarate or chlorinated paraffin, so-called plasticizers, are blended into ladder-type silicone oligomers, the plasticizers will ooze out to the surface during the drying and heat curing process, and a sufficient plasticizing effect may not be obtained. First, the surface of the coating film becomes sticky, which is undesirable.

Moreover, even if the acid alkyl ester or phenyl ester of the component (C) used in the present invention,
If the weight ratio of the mixture is less than 5 to 100 parts of the ladder-type silicone oligomer, the effect of the present invention cannot be obtained.On the other hand, if it is added in a weight ratio of more than 130 parts, not only the surface hardness will be insufficient, but also the component (C) The alkyl or phenyl ester of the acid leaches onto the surface and becomes sticky.

The coating agent used in the present invention includes (A) a solvent, (B) a ladder-type silicone oligomer, (C) phthalic acid, azopic acid, sebacic acid, citric acid,
Alkyl esters of maleic acid, fumaric acid, or phosphoric acid (however, the number of carbon atoms in the alkyl group is 1 to 4) or phenyl esters are mixed in a weight ratio of (B) to (C) of 100 to 5. 13o1 preferably 100:10
It is adjusted by blending and dissolving within the range of ~100. The total concentration of (B) and (C) in the coating agent is 5 to 6
It is desirable that the amount is 0% by weight, preferably 10 to 50% by weight.

The solvent for component (A) must be capable of dissolving the ladder-type silicone oligomer as component (B) and the acid alkyl ester or phenyl ester as component (C), and have a boiling point in the range of 50 to 200°C. Preferably. Typical examples of such solvents include ethanol, isopropyl
Examples include R-nol, butanol, toluene, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, tetrahydrofuran, cellosolve, cellosolve acetate, punarseron rub, trichloroethane, and the like. These solvents may be used as a mixture of two or more thereof, or may be a mixture of these solvents mainly consisting of gold and other solvents having a boiling point higher than 200°C.

In addition, the ladder-type silicone oligomer of component (B) used in the present invention, -ff formula (1)% formula% (wherein, R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, even if substituted It is a good phenyl group, hydroxyl group, or alkoxyl group. However, among all R, the hydroxyl group, alkoxyl group, or the total amount of these groups is 10 mole or less.

In general formula (1), when R is an alkyl group, an alkyl group having a carbon number in the range of 1 to 4 is usually used, and if the carbon number is larger than 4, it is not preferable because the curing speed is slow. . Furthermore, in general formula (1), if the total amount of hydroxyl groups, alkoxyl groups, or these groups among all R is more than 10 moles, it is not preferable because the water resistance of the cured coating film will be poor.

The ladder type silicone oligomer represented by the general formula (1) has a weight average molecular weight of 500 to 10,000, particularly 100
0 to 5000 is preferred.

The alkyl ester or phenyl ester of an acid as component (C) is an alkyl ester of phthalic acid, adipic acid, sebacic acid, citric acid, maleic acid, fumaric acid or phosphoric acid (provided that the alkyl group has 1 to 4 carbon atoms). ) or phenyl ester.

If the number of carbon atoms in the alkyl group of the acid alkyl ester is greater than 4, the miscibility with the ladder-type silicone oligomer will be poor, and 8 acid alkyl esters with a carbon number greater than 4 will appear on the coating film surface, resulting in the coating film lasting forever. It is not preferred because it has viscosity.

Representative examples of the alkyl ester or phenyl ester of the acid component (C) include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dimethyl adipate, diethyl sepacate, dimethyl citrate, noethyl maleate, diethyl fumarate, and tributyl phosphate. , nophenyl maleate, triphenyl phosphate, etc.

Two or more types of acid alkyl esters or phenyl esters as component (C) may be used in combination.

When using a coating agent in which the mixing ratio of the ladder-type silicone oligomer as the component (B) and the acid alkyl ester or phenyl ester as the component (C) is outside the range of the present invention, as described above, effect cannot be obtained.

The coating agent according to the present invention may include a dye, if necessary.
Pigments, fillers, UV absorbers, coupling agents, leveling agents, etc. can be added.

The prepared coating agent is applied to a bendable metal surface such as iron, stainless steel, copper, zinc, tin, aluminum, titanium, or an alloy thereof. The shape of the metal may be any shape as long as it can be bent, such as a plate, a rod, or a tube. The coating agent can be applied by spray coating, dip coating, brush coating, flow coating, spin coating, or the like. After coating and application, store at room temperature or 100%
The solvent is removed by drying at a temperature below 140°C, and then precuring is carried out by heating to 140°C or below, preferably 50 to 140°C. If the preliminary curing temperature is higher than 140° C., the curing progresses too much and cracks will occur in the coating film during subsequent bending, which is undesirable. The heating conditions for preliminary curing are 100℃
Preferably, the temperature is 30 minutes at 120°C, 10 minutes at 120°C, or 5 minutes at 140°C. After preheating, the coating film still has some flexibility and can be bent. After performing the folding process, the temperature is 150°C or higher, preferably 150°C or higher.
Complete curing is carried out at a temperature of 250°C. The heating conditions for complete curing were: 150°C for 2 hours, 170°C for 90 minutes, 18
Desirably, the heating time is about 1 hour at 0°C or about 30 minutes at 200°C. A curing catalyst (for example, tetramethylammonium hydroxide) may be added to the coating agent to lower the heating temperature, if necessary. Furthermore, when applying the coating agent to a bendable metal, a silane coupling agent solution may be applied to the metal surface in advance in order to further improve the adhesion between the metal and the coating film.

According to the method of the present invention, when it is bent with metal, there is no occurrence of scratches at the bent part, it has excellent adhesion to the metal, and it is possible to form a coating film on the metal with high surface hardness and heat resistance. It can be effectively used for painting machines, electrical and electronic equipment, vehicles, aircraft, etc.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 In the general formula (1), R consists of a methyl group and a phenyl group, and the molar ratio thereof is 2:1. 100 g of a ladder-type silicone oligomer (molecular weight approximately 1500), 40.9 g of dimethyl phthalate, and 1200 g of n-butanol were added. A coating agent was prepared by dissolving it.

After sandblasting this coating agent, it was degreased with trichloroethane to a length of 100 mm, a width of 100 mm, and a thickness of 0.0 mm. I MR carbon steel is immersed and the film thickness after drying is 10
It was applied by dip coating to a micron thickness. After leaving it at room temperature for 30 minutes to evaporate the solvent, it was precured by heating at 120° C. for 10 minutes. After cooling to room temperature, JIS K
Using a bending tester of 54006.16, the diameter of the mandrel is 3M.
It was bent 180 degrees.

This sample was heated at 180° C. for 1 hour to completely cure it. The surface hardness of the sample after cooling was 7H, the gopang adhesion test of a part of the outer corner of the bend was 100/100, and no cracks were observed on the surface. Also, this sample?
Even when the film was left at 400° C. for 10 minutes and then immediately returned to room temperature, no abnormality was observed in the coating film, and the goblin adhesion test of a part of the outside corner of the bend was 100/100.

Comparative Example 1 A coating agent having the same composition as in Example 1 was dip-coated onto carbon steel of the same size that had been subjected to the same treatment so that the film thickness after drying was 10 microns.

After leaving at room temperature for 30 minutes to evaporate the solvent,
Curing was performed by heating at ℃ for 1 hour. After cooling to room temperature,
It was bent 180 degrees in the same manner as in Example 1. The surface hardness of this sample was 20/100 in a part of the outer corner of the 7H1 bend, but it was 20/100 in a puncture adhesion test, and cracks were observed on the surface. Also, this sample? Even after leaving it at 400℃ for 10 minutes and returning it directly to room temperature, no abnormality was observed in the coating except for a part of the outer corner of the fold, but there was a panning mark in a part of the outer corner of the fold. Adhesion test is O/100
When the film was completely cured at 50° C. and 50° C. and then bent, the adhesion was poor.

Example 2 A coating agent was prepared by dissolving a ladder-type silicone oligomer (molecular weight approximately 1000) in general formula (1) in which R is a phenyl group (molecular weight: approximately 1000) in 100 g of dibutyl maleate and 400 p of toluene. The surface of this coating agent was anodized, and the length was 100 fHfl and the width was 1.
00+m, 0.2 m thick aluminum plate was spray coated to a dry film thickness of 8 microns. After being left at 50°C for 1 hour, preliminary curing was performed at 100°C for 30 minutes. After cooling to room temperature, it was bent by 180 degrees using a JIS K54006.16 bending tester to form three groups with a diameter of the mandrel. This sample was heated at 200° C. for 30 minutes to completely cure it.

The surface hardness of the sample after cooling was 5H, and the goblin adhesion test was 1.
00/100, no cracks were observed on the surface. Also, this sample f! No abnormality was observed in the coating film even when it was left at 400℃ for 10 minutes and then returned to room temperature.
It was 00/100.

Comparative Examples 2 to 8 An aluminum plate was coated in the same manner as in Example 2, except that dioctyl maleate was used instead of dibutyl maleate in Example 2, and the coating was precured, bent, and Fully cured. After cooling, the surface hardness of the sample was 3B or less and it was sticky, and the goblin adhesion test at a part of the outer corner of the fold was 0/100. Further, when this sample was left at 400° C. for 10 minutes and immediately returned to room temperature, cracks were observed, and the goblin adhesion test at a part of the outside corner of the bend was O/100.

Moreover, in the above, instead of dioctyl maleate,
When coating agents were prepared using dioctyl phthalate, dioctyl fumarate, dioctyl adipate, nooctyl sebacate, dioctyl citrate, and chlorinated paraffin, tackiness was observed in the coating film in the same manner as above.

Example 3 Using a ladder type silicone oligomer (molecular weight 2100) in which R is a methyl group in general formula (1), a coating agent having the following blending ratio was prepared.

Ladder type silicone oligomer 100.9 Noethyl azopate 15I Fluorine leveling agent 0.05,9 Ethyl acetate
250 g of this coating agent was applied to a copper plate having a length of 100 francs, a width of 100 wns, and a thickness of 0.1 wns by flow coating. The dry film thickness is approximately 1
I set it to 0 micron. After coating, it was dried at 50°C for 30 minutes, and then precured at 140°C for 5 minutes.

After cooling to room temperature, using a JIS K54006.16 bending machine, the core was bent 9 times at 180 degrees to make 3 diameters. This sample was heated at 170° C. for 90 minutes to completely cure it. The surface hardness of the sample after cooling is 5H1, and the adhesion test on a part of the outer corner of the bend is Zoo/100.
No cracks were observed on the surface.

Furthermore, even when this sample was left at 400°C for 10 minutes and then immediately returned to room temperature, no abnormality was observed in the coating film, and the adhesion test of a part of the outside corner of the bend was 100/100. .

Comparative Example 9 A coating agent was prepared using the same formulation as in Example 3, except that the mixing ratio of noethyl adibate was changed to 3 g, and it was applied to a copper plate in the same manner, followed by pre-curing, bending, and complete curing. . Cracks appeared on the painted surface of the sample, and the bent portion was completely peeled off.

Comparative Example 10 The mixing ratio of diethyla zopate was 200. A coating agent was prepared using the same formulation as in Example 3, except that the symbol @ was changed. This coating agent was applied to a copper plate in the same manner as in Example 3, and subjected to preliminary curing, folding, and complete curing.

The surface hardness of the painted surface of the sample was as low as HB, and the goblin adhesion test of the folded portion was O/100.

Example 4 A coating agent was prepared in the same manner as in Example 1 except that nitriphenyl phosphate was used instead of trimethyl phthalate.

This coating agent was degreased and degreased with trichloroethane.
Spray coating was performed on a 0 crn x 30 crn SUS 304 stainless steel plate so that the film thickness after drying was 25 microns. After leaving it at room temperature for 30 minutes to evaporate the solvent, it was precured by heating at 120° C. for 10 minutes. After cooling to room temperature, it was bent by 180 degrees using a JIS K54006.16 bending tester with a mandrel diameter of 3M.

This sample! Complete curing was performed by heating at &180° C. for 1 hour. The surface hardness of the sample after cooling was 100/100 in the punch adhesion test of a part of the outer corner of the 6H1 bend, and no cracks were observed on the surface. Also, this sample? Even when the film was left at 400° C. for 10 minutes and immediately returned to room temperature, no abnormality was observed in the coating film, and the goggle adhesion test of a part of the outer corner of the 9th bend was 100/100.

Example 5 Ladder type/licone oligomer-1 in which R is composed of a 97 mol methyl group and a 3 mol hydroxyl group in the general formula (1)
00g, diethyl sebacate 30g, and t130.9 mixed solvent of toluene and n-butanol (weight ratio 4:1)
) to prepare a coating agent. Galvanized steel plate (length 100711m) degreased with this coating agent
A film (width: 50 mm, thickness: 0.2 mm) was immersed and applied until the film thickness after drying was 10 microns. After leaving it at room temperature for 30 minutes to volatilize the solvent, it was heated at 120° C. for 10 minutes to perform preliminary curing. After cooling to room temperature, JIS
Using a K54006.16 bending tester, the core was bent 180 degrees with a diameter of 3. This sample was heated to 180℃
It was heated for 1 hour for complete curing. After cooling, the surface hardness of this sample was 7H1. A cross-cut adhesion test of a part of the bent outer corner was 100/100, and no cracks were observed on the surface.

Example 6 Ladder type silicone oligo 7-100g same as Example 5
and 30g of acetyl triethyl citrate and 130g
A coating agent was prepared by dissolving it in butanol. This coating was applied to the same galvanized row plate as in Example 5. The conditions for preliminary curing, bending, and complete curing are the same as in Example 5. The surface hardness of the obtained sample was 6H, and a part of the outer corner of the bend was tested for adhesion to the pan, and the test was 100/
100, and no cracks or scratches were observed on the surface.

Example 7 In Example 6, a coating agent was prepared by using 30.9 i of dimethyl fumarate instead of acetyl IJ ethyl citrate. Thereafter, samples were obtained in the same manner as in Example 6 using the other coating agents. The surface hardness of the obtained sample was 100/100 in a part of the outer corner of the 7H1 bend, but the punch adhesion test was 100/100, and no cracks were observed on the surface.

〔Effect of the invention〕

As described above, after applying the coating agent according to the present invention to a bendable metal, pre-curing is performed,
By heating and completely curing the material after bending, it became possible to form a good coating film even on the bent portions.

Claims (1)

[Claims] (A) Solvent, (B) Ladder-type silicone oligomer, and (C) Alkyl ester of phthalic acid, adipic acid, sebacic acid, citric acid, maleic acid, fumaric acid, or phosphoric acid (provided that the number of carbon atoms in the alkyl group is 1 to 4) or phenyl ester, and the above (B) pair (
After applying a coating agent having a mixing ratio of C) of 100:5 to 130 by weight to a bendable metal,
A method for coating metal, which comprises preliminary curing at a temperature of 140°C or lower, followed by bending, and complete curing at a temperature of 150°C or higher.