JPS61230772A - Method for coating metal - Google Patents

Abstract

PURPOSE:To form a film excellent in a rust-proof property, a degreasing property, lubricity and paintability, by applying the electrostatic coating of rust-proof lubricant with a specific composition to the surface of a metal in a specific coating amount. CONSTITUTION:Rust-proof lubricant is electrostatically applied to the surface of metal such as a can manufacturing grade steel plate or tin plated steel plate in an amount of 4-250mg/m<2>. The rust-proof lubricant to be used contains 5-40% of a reaction product obtained by reacting an org. carboxylic acid compound, for example, caprylic acid, laurylic acid or benzoic acid and secondary - tertiary amines, for example, methylamine or diethylethanolamine with citric ester such as trimethyl citrate or triethyl citrate and, if necessary, animal and vegetable oils, synthetic ester and a surfactant can be added to said lubricant.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides rust prevention,
The present invention relates to a metal coating method for applying a rust-preventing lubricant that has degreasing properties, lubricity, paintability, and printability.

[Conventional technology]

Steel sheets for cans, or surface-treated steel sheets such as tin-plated steel sheets and tin-free steel sheets are coated with anti-rust lubricating oil to prevent rust and scratches during transportation. However, the coating film thickness is extremely thin in consideration of painting properties, printing properties, and degreasing properties.

In recent years, the export of these steel plates has increased, and the role of rust-preventing lubricants has become important. Conventionally, dioctyl sebacate, etc., was applied to the steel plate surface, and this was then coated with vaporizable rust-preventing paper. It was packed in However, with this method, the rust prevention ability is insufficient and chains may occur during transportation of the steel plate, and when the steel plate is plated, it is difficult to remove these oils, resulting in poor plating adhesion and uneven plating. Therefore, there is a demand for a more excellent coating method for rust-preventing lubricating oil, but there is still no coating method that satisfies this requirement.

When considering the rust prevention and lubricity of steel plates, it is possible to improve the performance by applying general rust prevention oil, but these have poor degreasing properties and have poor paintability and ink printability. It's bad and can't be used.

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide rust prevention and
The object of the present invention is to provide a method for coating metal with a rust-preventing lubricant that is comprehensively superior to conventional methods in terms of degreasing, lubrication, painting and printing properties. ] In order to achieve the above object, the inventors of the present invention have studied the following matters.

(1) A thin and uniform oil film is formed on the surface of the steel plate using an electrostatic coating method. If an oil with good electrical conductivity is used, the particles will not be charged and will become atomized, resulting in an uneven coated oil film, so consider using an oil with low electrical conductivity.

(2) Consider an oil that has sufficient rust-preventing power even if the oil film formed on the surface of the steel plate is thin.

(3) Consider an oil with good degreasing properties.

(4) Consider using oil with good lubricity.

(51 Consider oils that are compatible with paints and printing inks.

As a result of studying the above matters, we invented the following coating method.

That is, the present invention is a reaction product of a citric acid ester, an organic carboxylic acid compound, and an amine. : A metal coating method characterized by electrostatically coating a metal surface with 4 to 250 □ coats of a rust-preventing lubricating oil containing 5 to 40%.

CH-Sword OR.

Citric acid ester has the general formula HOCC00Ry and the table CHt
In formula 1, Rt, Rt, and Rs are preferably hydrocarbon compounds having 1 to 8 carbon atoms, and as the number of carbon atoms increases further, the degreasing property deteriorates.

Examples of citric acid esters in the present invention include:

Examples include trimethyl citrate, triethyl citrate, tripropyl citrate, tributyl citrate, trioctyl citrate, and the like.

Organic carboxylic acid compounds are generally represented by 2RCOOH1
In the formula, R is preferably a hydrocarbon compound having 3 to 18 carbon atoms; if the number of carbon atoms is less than 2, the rust preventive power becomes poor, the electrical conductivity increases, and the electrostatic applicability deteriorates. When the number increases beyond 19, the degreasing property decreases.

Examples of organic carboxylic acid compounds include aliphatic carboxylic acids and aromatic carboxylic acids, such as propionic acid, butyric acid, caproic acid, capric acid, capric acid, lauric acid,
Examples include oleic acid, benzoic acid, toluic acid, p-nitrobenzoic acid, and butylbenzoic acid. Rust prevention, cleanability, odor,
In consideration of electrical conductivity, caprylic acid, capric acid, lauric acid and benzoic acid are preferred.

Among the amines used in the present invention, primary amines have an odor, so secondary to tertiary amines are preferred.

Examples of the amine include alkylamines such as methylamine, ethylamine, butylamine, ethylhexylamine, etc., and aminoalcohols such as dimethylethanolamine, diethylethanolamine, dibutylethanolamine, and diethylhexylethanolamine.

Other examples include cyclohexylamine, dicyclohexylamine, morpholine, jetanolamine, and methylmorpholine.

When an amine compound has a large number of OH groups, its rust prevention properties decrease,
Furthermore, since the electrical conductivity improves, electrostatic coating properties deteriorate. Therefore, the number of OR groups in the amine compound is preferably 2 or less,
Those having three OH groups, such as triethanolamine, are not preferred.

Preferred amines commercially available in Japan in the present invention are represented by the following general formula.

L Hydrocarbon Compound j In the present invention, the combination ratio of organic carboxylic acid and amine is preferably 1 mole. In addition, the citric acid ester is made to contain t-5 to 40% of the reaction product between an organic carboxylic acid compound and an amine, but if it is less than 5%, the rust prevention ability will decrease, and if it exceeds 40%, the electrical conductivity will increase and the electrostatic Spreadability deteriorates.

The amount of rust-preventing lubricant applied to the metal surface is 4 to 2,501. If it is less than 4V, the coating film will become uneven and the lubricity and rust prevention properties will decrease, and if it exceeds 250V/Tft', the paintability will deteriorate. , printability and washability deteriorate.

Animal and vegetable oils and synthetic esters (eg, dioctyl sebacate, acetylated trialkyl citrate) may be blended into the rust-preventing lubricating oil of the present invention in order to adjust the viscosity and electrical conductivity. Additionally, a surfactant may be added to improve cleaning properties.

Example 1 1 mole of caprylic acid and 1 mole of dibutylamine were mixed,
The mixture was stirred and reacted for 30 minutes while maintaining the temperature at -50 to 60°C to obtain dibutylamine salt of caprylic acid. Next, 30 parts of this caprylic acid dibutylamine salt and 70 parts of citric acid triethyl ester were mixed, and the electrical conductivity was 1.3.
A rust-preventing lubricating oil of μs/GML was obtained.

The rust-preventing lubricant was electrostatically applied to a 0.241M thick steel plate for upper raw material 5PCCI using a P-body electrostatic coating device, resulting in a uniform coating of 25WI9/GO. This coated steel plate 'k 70iix was cut into 15 g pieces and tested for lubricity, corrosion resistance, degreasing property, paintability and printability. The test method is as follows, and the test results are as follows:
Shown in the table.

Example 2 1 mole of lauric acid and 1 mole of diethylethanolamine were mixed and reacted by stirring for 30 minutes while maintaining the mixture at 50 to 60°C to obtain diethylethanolamine salt of lauric acid. Next, 30 parts of this diethylethanolamine salt of lauric acid and 70 parts of tributyl citrate were mixed to obtain a rust-preventing lubricating oil having an electrical conductivity of 5.5 μS/611.

This was subjected to electrostatic coating and performance testing in the same manner as in Example 1, and the results are shown in Table 1.

Example 3 1 mole of oleic acid and 1 mole of Morpoly/ were mixed and reacted by stirring for 30 minutes while maintaining the mixture at 50 to 60°C to obtain a morpholine salt of oleic acid. Next, 30 parts of this morpholine salt of oleic acid and 70 parts of triisoglobil citrate were mixed.

A rust-preventing lubricating oil with an electrical conductivity of 0.5 μS/cra was obtained. This was subjected to electrostatic coating and performance testing in the same manner as in the implementation film, and the results are shown in Table 1.

Example 4 1 mole of t-butylbenzoic acid and 1 mole of dibutyl ethanolamine were mixed and reacted by stirring for 30 minutes while maintaining the temperature at -50 to 60°C. Got salt.

Next, 7130 parts of this dibutylethanolamide of t-butylbenzoic acid and 70 parts of triethyl citrate were mixed to obtain a rust-preventing lubricating oil having an electrical conductivity of 4.0 μs/cIL.

This was subjected to electrostatic coating and performance testing in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 Dioctyl sebacate (electrical conductivity 0.02μS/Cr
IL) was subjected to electrostatic coating and performance testing in the same manner as in Example 1, and the results are shown in Table 1.

Comparative example 2 citric acid triethyl ester (electrical conductivity 0.08 pS
/cIIL)t-Electrostatic coating and performance tests were carried out in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 Example 10 Dibutylamide/salt of Cagrilic Acid t-Example 9'
Electrostatic coating was performed in the same manner as lJ t, but the electrical conductivity was 5.
Since it was as high as 51iS/C1l and had a high viscosity, it could not be applied uniformly.

〔Effect of the invention〕

By electrostatically applying the rust-preventing lubricating oil of the present invention to a gold R4 surface, especially an iron surface, it has better rust prevention, degreasing, lubricity, paintability, and printability than before. You can get excellent overall results.

Claims (6)

[Claims] (1) Prepare a rust-preventing lubricant containing 5 to 40% of a reaction product of an organic carboxylic acid compound and an amine to a citric acid ester, and apply 4 to 250 mg of the rust-preventive lubricant to the metal surface.
m^2 A metal coating method characterized by electrostatic coating. (2) The metal coating method according to claim 1, wherein the citric acid ester is represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1, R_2, and R_3 are hydrocarbon compounds having 1 to 8 carbon atoms. ] (3) The method for coating a metal according to claim 1, wherein the organic carboxylic acid compound is represented by the following formula. ROCCH [wherein R is a hydrocarbon compound having 3 to 18 carbon atoms. ] (4) The metal coating method according to claim 1, wherein the amine is a secondary to tertiary amine. (5) The method for coating a metal according to claim 4, wherein the secondary to tertiary amine is a secondary to tertiary amine that does not have three OH groups. (6) The metal coating method according to claim 1, wherein the electrostatically coated metal surface is an iron-based metal surface.