JPS6056226B2 - Surface treatment method for zinc-based substrates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method when applying a coating to the surface of a zinc-based substrate such as zinc, zinc alloy, electrogalvanized, hot-dip galvanized body, etc.

Conventionally, as a surface treatment method for surface coating of zinc-based substrates,
Shot blasting, degreasing and phosphate conversion treatments, or treatment with solutions containing alkali metal hydroxides or ammonium hydroxides were commonly used.

However, in phosphate chemical conversion treatment, the treatment process is complicated;
The disadvantage is that it takes a long time to process. In addition, treatment with a solution containing alkali metal hydroxide or ammonium hydroxide is simple and provides excellent adhesion, but it has the disadvantage that a sufficient effect on corrosion resistance cannot be obtained. be. The present invention provides a surface coating base for zinc-based substrates that provides superior coating adhesion and corrosion resistance when coating the surface of zinc-based substrates, and that is also easy to treat, compared to the above-mentioned treatment methods. The present invention provides a processing method.

That is, in the present invention, after treating the surface of a zinc-based substrate such as zinc, zinc alloy, or zinc plating with an aqueous solution of an alkali metal hydroxide, N-
The surface of a zinc-based substrate is characterized by being treated with coco β-aminobutyric acid or without treatment with an aqueous solution or dispersion of an organosilicon compound represented by the following general formula, or an organic solvent solution. It is a processing method.

General formula [R(CH2)n]. ．． 5i-X4? However,
m is an integer of 1 to 3; n is 0 or an integer of 1 to 3; when n is 0, R is an alkenyl group;
When it is an integer of ~3, R is an amino group, an alkylene diamino group, an alkanolamino group having 1 to 5 carbon atoms, α, β
A monounsaturated aliphatic Group 5 carboxylic acid residue, an alkoxy group having an epoxy group, or a cycloalkyl group having an epoxy group, and X is an alkoxy group having 1 to 5 carbon atoms, an alkoxyalkoxy group (each alkoxy has 1 carbon number ~5), saturated aliphatic carboxylic acid residues, hydroxyl groups, and alkyl groups having 1 to 5 carbon atoms, and all x are alkyl groups. It is never.

Generally, metal objects to be painted are cleaned by organic solvent degreasing or alkali degreasing prior to painting, but in the present invention, zinc The surface of the base material is treated with an aqueous solution of an alkali metal hydroxide such as sodium or potassium by a conventional method.

In this case, it is desirable to not only activate the surface layer of the zinc-based base material, but also to perform a treatment so that a zinc hydroxide film can be formed on the surface of the zinc-based base material. The higher the concentration of these alkanolyte aqueous solutions, the shorter the time required for treatment, but if the concentration is too high, the treatment will be excessive and the surface of the zinc-based substrate will be greatly worn out, and sludge will accumulate in the treatment solution, causing consumption of the chemicals. Therefore, it is desirable to reduce the amount to 10% or less. In addition, the higher the temperature of the processing solution, the shorter the processing time, so the processing can be carried out by heating the processing solution. For example, 1 alkali concentration 8 to 10%, temperature 5 (range) for 2 to 3 minutes, 2 alkali concentration 4 to 6%, temperature 7 C) for 3 to 5 minutes, 8
From the viewpoint of process control, it is preferable to carry out the treatment for 5 to 1 times at an alkali concentration of 3% or less and a temperature of 90C. The purpose of this treatment is to produce a zinc-active coating on the surface of the zinc-based substrate.

In the present invention, in this treatment using an aqueous solution of an alkali metal hydroxide, the alkali degreasing step as described above may also be used.

When treating with an aqueous solution of alkali metal hydroxide, the treatment should be carried out until a uniform zinc hydroxide layer is formed on the surface of the zinc-based substrate. If the material is oxidized in the water, degreasing, cleaning, activation, and formation of a hydroxide film may be uneven or insufficient. In this case, water or trichlorethylene, perchlorethylene, 1,1
, 1-trichloroethane, carbon tetrachloride, N-coco β-aminobutyric acid dissolved in a halogenated hydrocarbon solvent such as chloroform, i.e., with the general formula
0 of fatty aminocarboxylic acids represented by 1"゛""1" (R1 indicates coconut oil alcohol of Cl2 to 1)
．． Dip or spray in a 1-10%, preferably 1-5% solution! Otoin h ■ 1 ＾ Genju 廿 1 demasu +
Sushi (8) 1 Limatsu l small? Adhesion and corrosion resistance are further improved. The effect is best with a 1 to 5% solution, and treatment heated to 50°C or the boiling point of water or a halogenated hydrocarbon solvent also gives good results, but the surface of the zinc-based substrate to be treated If the surface of the substrate is uniform and can be activated to the extent that the surface of the substrate turns slightly gray by treatment with an aqueous solution of alkali metal hydroxide, organosilicon can be directly activated without treatment with N-coco β-aminobutyric acid. The object of the present invention is also achieved by treatment with compounds. After the above treatment, the present invention involves treatment with an aqueous solution or dispersion of an organosilicon compound or an organic solvent solution.

General formula [R(CH2)n) used in the present invention. NSi-X4-. One end group X of the silicon compound represented by is a reactive group that reacts with zinc activated with alkali metal hydroxide, that is, zinc hydroxide, and provides a strong bond; It is a reactive group that chemically bonds with the resin component in the final top coat.

m in the above general formula is an integer of 1 to 3, and n is 0 or an integer of 1 to 3. Of each terminal group, [R(C
H2+-.

] will be explained. When n is 0, R is an alkenyl group, and a typical and preferred example thereof is a vinyl group, and lower alkenyl groups such as a propenyl group, an allyl group, and a butenyl group are preferably used. When n is an integer from 1 to 3, i.e. -+. CH2+-. is a methylene group, an ethylene group or a trimethylene group, R is an alkyl group such as an amino group, for example an ethylene diamino group, a propylene diamino group, etc. diamino group, lower alkanolamino group such as diethanolamino group, α, such as acrylic acid, methacrylic acid, crotonic acid, etc.
Residues of β-monounsaturated aliphatic carboxylic acids (carboxylic acid residues refer to groups obtained by removing hydrogen atoms from the carboxyl group of carboxylic acids), such as alkoxy groups having epoxy groups such as glycidoxy groups, or epoxycyclohexyl groups. When m is 2 or 3, [R(CH2+-)] may be the same group or different groups. One group x is, for example, a methoxy group. group, an alkoxy group having 1 to 5 carbon atoms such as an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, such as a methoxyethoxy group, an ethoxyethoxy group,
From alkoxyalkoxy groups such as butoxyethoxy groups, e.g. residues of saturated aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, hydroxyl groups and alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, propyl groups, etc. selected from the group.

When m is 2 or 1, all X's may be the same group or different groups, but in organosilicon compounds where all x's are alkyl groups, including when m is 3, the reaction with zinc hydroxide Not suitable for use due to gender. Examples of organosilicon compounds represented by the above general formula are as follows.

Vinyltriethoxysilane Vinyltris(β-methoxyethoxy)silane Vinyltriacetoxysilane γ-Aminopropyltriethoxysilane H2N(CH2)3-Si(0CH2-CH3)3β-
Aminoethyltriethoxysilane H2N(CH2)2-
Si(0CH2-CH3)3aminomethyltriethoxysilane H2NCH2-Si(0CH2-CH3)3γ-
Aminopropyltrimethoxysilane H2N(CH2)3
-Si-(0CH3)3N-β(aminoethyl)γ-aminopropyltrimethoxysilane H2N-(CH2)2
-NH(CH2)3-Si(0CH3)3N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane H2N(CH2)2NH(CH2)3-Si- (CH
3) (0CH3)2γ-methacryloxypropyltrimethoxysilane γ-N,N-diethanolaminopropyltriethoxysilane (HOCH2CH2)2N(C
H2) 3-Si(0CH2-CH3)3γ-glycidoxypropyltrimethoxysilane β-(3,4epoxycyclohexyl)ethyltrimethoxysilane or silanol corresponding to each of the above silanes, such as vinylsilanol, γ
-Aminopropylsilanol, β-aminomethylsilanol, aminomethylsilanol, N-β(aminoethyl)γ-aminopropylsilanol, and the like.

When m in the above general formula is 2, one of the X's is a silane compound having an alkyl group, or when m is 1, one or two of the X's are silane compounds having an alkyl group. These organosilicon compounds react with zinc hydroxide generated on the surface of the zinc-based substrate treated with an aqueous solution of alkali metal hydroxide, forming a coating layer consisting of a zinc-silicate organic compound, and It exhibits a coupling effect on both the surface of the base material and the final coating layer.

The concentration of the organosilicon compound used in this step in the aqueous solution or organic solvent solution is 0.01 to 10%, preferably 0.1 to 5%. When an organosilicon compound is used in the form of an aqueous solution, it is preferably disposed of promptly because it will be hydrolyzed during long-term running use. For long-term running, alcohols such as methanol, ethanol and butanol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and butyl acetate,
Trichlorethylene, perchlorethylene, 1,1,1
- 0.01 to 10% of an organosilicon compound in an organic solvent such as a oxidized hydrocarbon such as trichloroethane, carbon tetrachloride, or chloroform, or an aromatic hydrocarbon such as toluene, or a mixture thereof with water. Dissolve at room temperature to 60℃
It is easy to perform the immersion treatment under treatment conditions of ℃, and the treatment can be performed uniformly. It can also be used in the form of a dispersion.
If the concentration of the organosilicon compound is less than 0.01%, the coupling effect with the top coating will be reduced, and there is a tendency that no improvement in corrosion resistance can be expected. Furthermore, when treated at a concentration exceeding 10%, repellency tends to occur on the painted surface of the top coat. One group [R-+. CH2+.

] is a vinyl group, an amino group, a carboxylic acid residue, or an epoxy group. Therefore, on zinc-based substrates treated with these, cross-linking-reactive powder coatings and solvent-borne coatings having carboxyl groups, hydroxyl groups, methylol groups, alkoxymethylol groups and epoxy groups or polyalkenyl groups may be used. It is possible to paint with a solvent-free paint for ultraviolet or electron beam curing, but depending on the type of paint, [R-+. CH2+-. ] The group may be selected appropriately. Thus, by treating the surface of zinc-based materials such as zinc, zinc plating, and zinc alloys with the treatment method of the present invention, the paint applied thereto will have a strong chemical bond, resulting in extremely excellent adhesion, corrosion resistance, and durability. A thin coating film is formed.

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

Example 1 General purpose rolled zinc plate degreased with trichlorethylene vapor (
JISH432l, 70m x 150cm x 0.6cm thick)
1 in a 1% aqueous sodium hydroxide solution heated to 90°C.
After soaking in powder, it was washed with running water for 5 minutes and then air-dried.

After drying, it was immersed in a solution consisting of 0.1 part of each of the following organosilicon compounds, a part of methanol, and 1 part of water at 25° C. for 5 minutes, and then air-dried. Organosilicon compound: (a) Vinyltris(β-methoxyethoxy)silane (
b) γ-methacryloxypropyltrimethoxysilane (c) β-(3,4 epoxycyclohexyl)ethyltrimethoxysilane (d) γ-glycidoxypropyltrimethoxysilane (e) γ-aminopropyltrimethoxysilane (f ) N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (g) Vinyltriethoxysilane (h) Vinyltriacetoxysilane (1) β-aminoethyltrimethoxysilane (j) Aminomethyltriethoxysilane ( k) γ-aminopropyltrimethoxysilane (1) N-β-(aminoethyl)-
γ-Aminopropylmethyldimethoxysilane (n1) γ
-N,N-diethanolaminopropyltriethoxysilane (n) γ-glycidoxypropylsilanol (0)
γ-Aminopropylsilanol Next, the above-treated general-purpose rolled zinc plate was coated with an acrylic solvent-based clear paint (ethyl acrylate, 0 parts styrene, 18 parts N-methylolacrylamide, 2 parts acrylic acid, and 35 parts methanol. After normal solution polymerization in the presence of 1 part and 1 part of butanol, 25 parts of melamine resin was applied, baked and cured as two powders at an ambient temperature of 180°C, and then left to cool. After cooling, a coating film of about 15 microns was obtained.

(1) A grid of 100 1wR square squares was cut on the finished coated board, and the adhesion was evaluated by counting the number of grids remaining without peeling off from the flat board base.

(2) Corrosion resistance was evaluated by immersing the sample in a 5% saline solution maintained at 5CfC and observing the surface condition taken out at regular intervals. The results are shown in Table-1. Comparative Example 1 Table 1 shows the results of a test conducted in the same manner as in Example 1, except that the treatment with the methanol aqueous solution of various organosilicon compounds was not performed.

Comparative Example 2 Table 1 shows the results of a test carried out in the same manner as in Example 1, except that the treatment with a 1% aqueous sodium hydroxide solution heated to 90 DEG C. and the washing with running water were not performed.

Examples 2-3 Electrogalvanized flat plate degreased with trichlorethylene vapor (7 micron electrolytic galvanized JIS G3l4l cold rolled steel plate dull).

70 Tn
After washing with water for a minute, two powders were dried at 100°C.

After drying, Example 2 was immersed in a 1% aqueous solution of N-coco β-aminobutyric acid at 90° C. for 5 minutes, and then air-dried. In Example 3, the following treatment was carried out without carrying out the treatment with this aqueous solution of N-coco β-aminobutyric acid. Next, it was immersed in a 5% aqueous dispersion of γ-methacryloxypropyltrimethoxysilane at 2.5° C. for 5 minutes, and then air-dried.

Electrolytic galvanized flat plate treated with
After preheating at 0°C for 1 minute, dicarboxylic acid-curing acrylic resin powder paint (Meltak A-200, manufactured by Toagosei Chemical Industry Co., Ltd.) was applied using the fluidized dipping method, and the ambient temperature was 2.
After baking and hardening the powder at 00°C, it was allowed to cool to obtain a coating film of about 250 microns.

The adhesion of the finished coated board was evaluated in the same manner as in Example 1.

Corrosion resistance was evaluated by immersion in a 5% saline solution maintained at 80°C. The results are shown in Table 2. Comparative Example 3 In Example 2, N-coco β-amino Table 2 shows the results of a test conducted in the same manner as in Example 2, except that neither the treatment with the butyric acid aqueous solution nor the treatment with the γ-methacryloxypropyltrimethoxysilane aqueous dispersion was performed.

Comparative Example 4 In Example 2, treatment with a 10% sodium hydroxide aqueous solution at 25°C, washing with running water, and
Table 2 shows the results of testing in the same manner as in Example 2, except that the drying was not carried out at 0°C for 20 minutes.

Comparative Example 5 Table 2 shows the results of a test conducted in the same manner as in Example 3, except that the treatment with a 10% sodium hydroxide aqueous solution at 25°C, washing with running water, and drying at 100°C for two cycles were not performed. show.

Examples 4-5 Hot-dip galvanized flat plate degreased with trichlorethylene vapor (80 micron hot-dip galvanized JlSH3l4l cold-rolled steel plate dull).

70m mowing 50m mowing. 6% (2 thick) heated to 70℃
After being immersed in an aqueous potassium hydroxide solution for 5 minutes, it was washed with running water for 5 minutes and then dried at 100°C.

After drying, in Example 4, a 5% trichloroethylene solution of N-coco β-aminobutyric acid was sprayed at 50° C. for 1 minute, and then air-dried. In Example 5, the following treatment was carried out without carrying out the treatment with the trichlorethylene solution of N-coco β-aminobutyric acid.

Next, it was immersed in a 1% trichlorethylene solution of γ-glycidoxypropyltrimethoxysilane and a 1% trichlorethylene solution of N-β(aminoethyl)γ-aminopropyltrimethoxysilane at 50°C for 5 minutes, respectively, and then dried. Dry.

A dihydroxide-curing epoxy resin powder coating (Meltak E-100, manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was applied to each of these treated hot-dip galvanized flat plates using an electrostatic coating method, and the powder was baked and cured at an ambient temperature of 200°C. After that, it was cooled by standing to cool to obtain a coating film of about 50 microns. Evaluation of the adhesion and corrosion resistance of the finished painted board was carried out in Examples 2 and 3.
I did the same. The results are shown in Table-3. Comparative Example 6 In Example 4, treatment of N-coco β-aminobutyric acid with Trikucho reethylene solution and treatment of γ-glycidoxypropyltrimethoxysilane or N-β(aminoethyl)γ-aminopropyltrimethoxysilane Table 3 shows the results of the test conducted in the same manner as in Example 4 except that no treatment with trichlorethylene solution was performed.

Comparative Example 7 Table 3 shows the results of a test conducted in the same manner as in Example 4, except that the treatment with a 6% potassium hydroxide aqueous solution heated to 70°C, washing with running water, and drying the two powders at 100°C were not performed. Shown below.

Comparative Example 8 The same test results as in Example 5 were carried out, except that the treatment with a 6% potassium hydroxide aqueous solution heated to 70°C, washing with running water, and drying at 100°C were not performed. It is shown in Table-3.

Examples 6 to 8 Hot-dip galvanized plates degreased with trichlorethylene vapor (
80 micron hot-dip galvanized JISG3l4l cold-rolled steel plate dull.

70WR x 15i x 1.2 mm thick) was immersed for 5 minutes in a 3% aqueous sodium hydroxide solution heated to 90°C, rinsed with running water, and air-dried.

Next, for Examples 6 to 8, one powder was immersed in a 0.5% aqueous solution of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane at 25°C, and then air-dried.

Thereafter, in Example 6, a dicyandiamide curing type epoxy resin powder coating (Meltak E-500, manufactured by Toagosei Chemical Industry Co., Ltd.) was applied to the hot-dip galvanized flat plate subjected to the above treatment, and the temperature at the ambient temperature was 200℃
After baking and hardening the powder, it was allowed to cool to obtain a coating film of about 60 microns. In addition, for Example 7, a flat plate was preheated at an ambient temperature of 200°C and then coated with a dihydroxide-curing epoxy resin powder coating (Meltak E-100, manufactured by Toagosei Chemical Co., Ltd.) using a fluidized dipping method. After hardening by baking one powder at an ambient temperature of 20 (range), the mixture was allowed to cool to obtain a coating film of about 250 microns. Regarding Example 8, the flat plate was heated at an ambient temperature of 200°C.
After preheating, a polyester resin-curing epoxy resin powder coating (Meltak E-300, manufactured by Toagosei Chemical Industry Co., Ltd.) was applied using the fluidized dipping method, and the ambient temperature was 200.
After baking and hardening the powder at ℃, it was cooled by standing to cool to about 25℃.
A coating film of 0 micron was obtained.

The adhesion and corrosion resistance of the coated plates were evaluated in the same manner as in Examples 2 and 3, and the results are shown in Table 4.

Comparative Example 9 Table 4 shows the results of testing in the same manner as in Example 6, except that no treatment with an aqueous solution of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane was performed in Example 6. .

Comparative Example 10 Table 4 shows the results of a test conducted in the same manner as in Example 6, except that the treatment with a 3% sodium hydroxide aqueous solution heated to 90°C and the washing with running water were not performed.

Comparative Example 11 Table 4 shows the results of a test conducted in the same manner as in Example 7, except that no treatment with an aqueous solution of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane was performed in Example 7. Shown below.

Comparative Example 12 Table 4 shows the results of a test conducted in the same manner as in Example 7, except that the treatment with a 3% aqueous sodium hydroxide solution heated to 90°C and the washing with running water were not performed.

Comparative Example 13 Table 4 shows the results of a test conducted in the same manner as in Example 8, except that no treatment with an aqueous solution of γ-glycidoxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane was performed in Example 8. Shown below.

Comparative Example 14 Table 4 shows the results of a test conducted in the same manner as in Example 8, except that the treatment with a 3% caustic soda aqueous solution heated to 900C and the washing with running water were not performed.

Claims (1)

[Scope of Claims] 1. After the surface of a zinc-based substrate is treated with an aqueous solution of an alkali metal hydroxide, it is treated with an aqueous solution or aqueous dispersion or an organic solvent solution of an organosilicon compound represented by the following general formula. Characteristic surface treatment method for zinc-based substrates. General formula [R CH_2)_n]_mSi-X_4_-_m However, m is an integer of 1 to 3, n is 0 or an integer of 1 to 3, and when n is 0, R is an alkenyl group, n is an integer of 1 to 3, R is an amino group, an alkylene diamino group, an alkanolamino group having 1 to 5 carbon atoms, an α,β-unsaturated aliphatic carboxylic acid residue, an alkoxy group having an epoxy group, or an epoxy group. It is a cycloalkyl group having a group. In addition, X is an alkoxy group having 1 to 5 carbon atoms, an alkoxyalkoxy group (each alkoxy has 1 to 5 carbon atoms), a saturated aliphatic carboxylic acid residue, a hydroxyl group, and a carbon number 1
- at least one group selected from the alkyl groups of 5 to 5, but not all of X are alkyl groups. 2 After treating the surface of the zinc base material with an aqueous solution of alkali metal hydroxide, N-coco dissolved in water or a halogenated hydrocarbon is treated.
A method for surface treatment of zinc-based substrates, which comprises treating with β-aminobutyric acid, and then treating with an aqueous solution or dispersion of an organosilicon compound represented by the following general formula, or an organic solvent solution. General formula I [R■CH_2)_n]_mSi-X_4_-_m However, m is an integer of 1 to 3, n is 0 or an integer of 1 to 3, and when n is 0, R is an alkenyl group, When n is an integer of 1 to 3, R is an amino group, an alkylene diamino group, an alkanolamino group having 1 to 5 carbon atoms, an α,β-unsaturated aliphatic carboxylic acid residue, an alkoxy group having an epoxy group, or It is a cycloalkyl group having an epoxy group. In addition, Although at least one group is selected, not all Xs are alkyl groups.