阅读说明：本技术 一种电镀锌钢板用无铬表面处理液及其制备方法 (Chromium-free surface treatment liquid for electro-galvanized steel plate and preparation method thereof ) 是由 陆飚 黄勇 罗晓锋 郭文勇 于 2020-07-16 设计创作，主要内容包括：本发明涉及金属表面处理领域,具体公开了一种电镀锌钢板用无铬表面处理液及其制备方法,该表面处理液由水性有机硅树脂20~50质量份、钼酸盐0.1~2质量份、镍盐0.05~2质量份、钛盐0.05~2质量份、铈盐0.05~3质量份、磷酸1~5质量份、冰醋酸0.5~2质量份、乙二醇2~10质量份和去离子水40~80质量份制备而成。本发明提供的电镀锌钢板用无铬表面处理液用于电镀锌钢板表面处理时,可以在电镀锌层表面形成一层有机无机复合的钝化膜,该钝化膜具有优异的耐蚀性和加工性,同时也具有优异的耐高温黄变性能。(The invention relates to the field of metal surface treatment, and particularly discloses a chromium-free surface treatment liquid for an electro-galvanized steel plate and a preparation method thereof, wherein the surface treatment liquid is prepared from 20-50 parts by mass of water-based organic silicon resin, 0.1-2 parts by mass of molybdate, 0.05-2 parts by mass of nickel salt, 0.05-2 parts by mass of titanium salt, 0.05-3 parts by mass of cerium salt, 1-5 parts by mass of phosphoric acid, 0.5-2 parts by mass of glacial acetic acid, 2-10 parts by mass of ethylene glycol and 40-80 parts by mass of deionized water. When the chromium-free surface treatment solution for the electro-galvanized steel sheet is used for the surface treatment of the electro-galvanized steel sheet, a layer of organic-inorganic composite passivation film can be formed on the surface of the electro-galvanized layer, and the passivation film has excellent corrosion resistance and processability and also has excellent high-temperature yellowing resistance.)

1. The chromium-free surface treatment liquid for the electro-galvanized steel sheet is characterized by being prepared from the following raw materials: 20-50 parts by mass of an aqueous organic silicon resin solution, 0.1-2 parts by mass of molybdate, 0.05-2 parts by mass of nickel salt, 0.05-2 parts by mass of titanium salt, 0.05-3 parts by mass of cerium salt, 1-5 parts by mass of phosphoric acid, 0.5-2 parts by mass of glacial acetic acid, 2-10 parts by mass of ethylene glycol and 40-80 parts by mass of deionized water.

2. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 1, characterized in that the aqueous silicone resin solution is prepared by the following method:

Step 1, taking 20-50 parts by mass of a silane coupling agent containing epoxy groups, 10-30 parts by mass of a silane coupling agent containing short chain alkyl groups and 1-10 parts by mass of a silane coupling agent containing long chain alkyl groups, wherein the mass ratio of the silane coupling agent containing short chain alkyl groups to the silane coupling agent containing long chain alkyl groups is as follows: (3-10): 1, stirring and mixing uniformly to obtain a mixture;

and 2, adding 120-200 parts by mass of deionized water and 0.1-2 parts by mass of inorganic acid into a reactor, heating to 40-70 ℃, dropwise adding the mixture obtained in the step 1 into the reactor in a stirring state for 1-4 hours, and after dropwise adding, carrying out heat preservation reaction for 2-4 hours to obtain the water-based organic silicon resin solution.

3. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 2, wherein the epoxy group-containing silane coupling agent has a chemical formula of R₀-Si(OR₁)₃Wherein R is₀Is gamma- (2, 3-epoxypropoxy) propyl;

the chemical formula of the silane coupling agent containing the short chain alkyl is R₂-Si(OR₁)₃Wherein R is₂Is an alkyl group having a main chain carbon atom number of 1-5;

the chemical formula of the silane coupling agent containing long-chain alkyl is R₃-Si(OR₁)₃Wherein R is₃Is alkyl with 6-20 carbon atoms in the main chain;

the R is₁Is one or more of methyl, ethyl, propyl and isopropyl.

4. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 3, characterized in that the epoxy-containing silane coupling agent is γ - (2, 3-glycidoxy) propyltrimethoxysilane and/or γ - (2, 3-glycidoxy) propyltriethoxysilane;

the silane coupling agent containing short-chain alkyl is one or more of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane and isopropyltriethoxysilane;

the silane coupling agent containing long-chain alkyl is one or more of n-hexyltrimethoxysilane, n-hexyltriethoxysilane, dodecyl-trimethoxysilane, dodecyl-triethoxysilane, octadecyl-trimethoxysilane and octadecyl-triethoxysilane.

5. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 1, characterized in that the molybdate is sodium molybdate and/or potassium molybdate;

the nickel salt is one or more of nickel nitrate, nickel acetate and nickel sulfate;

the titanium salt is one or more of titanium sulfate, titanyl sulfate and ammonium fluotitanate;

The cerium salt is one or more of cerium nitrate, cerium sulfate and cerium acetate.

6. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to any one of claims 1 to 5, characterized in that it is prepared by the following method:

adding the water-based organic silicon resin solution into a reactor at normal temperature, starting stirring, then adding molybdate, nickel salt, titanium salt, cerium salt, phosphoric acid, glacial acetic acid and ethylene glycol into deionized water, stirring and dissolving, then dropwise adding the dissolved mixture into the reactor for 10-30 min, and stirring for 20-60 min after dropwise adding is finished to obtain the chromium-free surface treatment solution for the electro-galvanized steel plate.

7. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 1, characterized in that the phosphoric acid concentration is 85 wt%.

8. The chromium-free surface treatment liquid for electrogalvanized steel sheets according to claim 2, wherein the inorganic acid is one or more of 98wt% sulfuric acid, 85wt% phosphoric acid, and 68 wt% nitric acid.

Technical Field

The invention relates to the technical field of metal surface treatment materials, in particular to a chromium-free surface treatment liquid for an electro-galvanized steel plate and a preparation method thereof.

Background

The electrogalvanized steel plate is widely applied to the fields of household appliances, machinery, aviation, buildings and the like, the electrogalvanizing on the surface can effectively improve the corrosion resistance of the steel plate, but in humid air, the electrogalvanizing on the surface of the steel plate can generate corrosion to form white spots or gray objects, the appearance and the corrosion resistance of products are influenced, and therefore the surface of the electrogalvanized steel plate needs to be passivated. The traditional chromium-containing passivator is harmful to the environment and human bodies and is gradually eliminated, in order to achieve or exceed the passivation effect of chromium salt, the chromium-free passivator with better corrosion resistance in the current market is often compounded by organic matters and inorganic salts, the organic matters and inorganic matters are compounded to treat a zinc layer, the corrosion resistance of the obtained passivation film is superior to that of the passivation film obtained by singly using the organic matters or singly using the inorganic matters, and the general application of the electro-galvanized steel plate can be met.

However, under some harsh use conditions, the electrogalvanizing chromium-free passivator is required to have good corrosion resistance and excellent processability, and simultaneously, a passivation film is required to have good high-temperature yellowing resistance and no obvious yellowing at 300 ℃, while organic resins used in commonly used organic-inorganic composite passivators can generate decomposition reaction within the temperature range and have serious surface yellowing, in patent applications with publication numbers of CN102134713A, CN101914344A and CN101316947A, the electrogalvanizing passivation plate treated by the treating solution has serious surface yellowing after being baked at 300 ℃ for 30 minutes, in patent application with publication number of CN1254033A, silane is used as an organic component, but contains a large amount of amino-terminated silane, and the surface yellowing of the steel plate treated by the treating solution is serious after being baked at 300 ℃ for 30 minutes, so that a chromium-free surface treating solution for the electrogalvanizing steel plate needs to be developed, and after the electrogalvanizing steel plate is treated by the electrogalvanizing chromium-free surface treating solution, the formed passive film has good corrosion resistance and good high-temperature yellowing resistance.

Disclosure of Invention

In view of the disadvantages of the prior art, the invention aims to provide a chromium-free surface treatment solution for an electrogalvanized steel sheet, and a passive film obtained after the electrogalvanized steel sheet is treated by the treatment solution has high corrosion resistance, excellent processability and excellent high-temperature yellowing resistance.

The technical scheme of the invention is as follows:

a chromium-free surface treatment liquid for an electrogalvanized steel sheet is prepared from the following raw materials: 20-50 parts by mass of an aqueous organic silicon resin solution, 0.1-2 parts by mass of molybdate, 0.05-2 parts by mass of nickel salt, 0.05-2 parts by mass of titanium salt, 0.05-3 parts by mass of cerium salt, 1-5 parts by mass of 85% phosphoric acid, 0.5-2 parts by mass of glacial acetic acid, 2-10 parts by mass of ethylene glycol and 40-80 parts by mass of deionized water;

further, the treatment fluid is prepared from the following raw materials: 30-45 parts by mass of an aqueous organic silicon resin solution, 0.1-1 part by mass of molybdate, 0.1-1 part by mass of nickel salt, 0.1-1 part by mass of titanium salt, 0.1-1 part by mass of cerium salt, 1-5 parts by mass of 85% phosphoric acid, 0.5-2 parts by mass of glacial acetic acid, 2-10 parts by mass of ethylene glycol and 40-80 parts by mass of deionized water;

preferably, the preparation method of the aqueous silicone resin solution is as follows:

step 1, taking 20-50 parts by mass of a silane coupling agent containing epoxy groups, 10-30 parts by mass of a silane coupling agent containing short chain alkyl groups and 1-10 parts by mass of a silane coupling agent containing long chain alkyl groups, wherein the mass ratio of the silane coupling agent containing short chain alkyl groups to the silane coupling agent containing long chain alkyl groups is as follows: (3-10): 1, stirring and mixing uniformly to obtain a mixture;

Step 2, adding 120-200 parts by mass of deionized water and 0.1-2 parts by mass of inorganic acid into a reactor, heating to 40-70 ℃, dropwise adding the mixture obtained in the step 1 into the reactor in a stirring state for 1-4 hours, and after dropwise adding, carrying out heat preservation reaction for 2-4 hours to obtain a water-based organic silicon resin solution;

preferably, in the method for preparing the aqueous silicone resin solution, the structure of the epoxy-containing silane coupling agent is R₀-Si(OR₁)₃Wherein R is₀Is gamma- (2, 3-epoxypropoxy) propyl; r₁Is one or more of methyl, ethyl, propyl and isopropyl;

preferably, in the method for preparing the aqueous silicone resin solution, the structure of the silane coupling agent containing short chain alkyl is R₂-Si(OR₁)₃Wherein R is₂Is an alkyl group having a main chain carbon number of 1 to 5, R₁Is one or more of methyl, ethyl, propyl and isopropyl;

preferably, the water isIn the preparation method of the solution of the organic silicon resin, the structure of the silane coupling agent containing the long-chain alkyl is R₃-Si(OR₁)₃Wherein R is₃Is alkyl with 6-20 carbon atoms in the main chain, R₁Is one or more of methyl, ethyl, propyl and isopropyl;

more preferably, in the preparation method of the aqueous silicone resin solution, the epoxy-containing silane coupling agent is gamma- (2, 3-glycidoxy) propyltrimethoxysilane and/or gamma- (2, 3-glycidoxy) propyltriethoxysilane;

More preferably, in the preparation method of the aqueous silicone resin solution, the silane coupling agent containing short chain alkyl is one or more of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane and isopropyltriethoxysilane;

more preferably, in the preparation method of the aqueous silicone resin solution, the long-chain alkyl-containing silane coupling agent is one or more of n-hexyltrimethoxysilane, n-hexyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, octadecyltrimethoxysilane and octadecyltriethoxysilane;

preferably, in the preparation method of the aqueous silicone resin solution, the inorganic acid is one or more of sulfuric acid with the mass concentration of 98%, phosphoric acid with the mass concentration of 85% and nitric acid with the mass concentration of 68%;

preferably, the molybdate is sodium molybdate and/or potassium molybdate;

preferably, the nickel salt is one or more of nickel nitrate, nickel acetate and nickel sulfate;

preferably, the titanium salt is one or more of titanium sulfate, titanyl sulfate and ammonium fluotitanate;

Preferably, the cerium salt is one or more of cerium nitrate, cerium sulfate and cerium acetate;

preferably, the chromium-free surface treatment liquid for electrogalvanized steel sheets is prepared by the following steps: adding the water-based organic silicon resin solution into a reactor at normal temperature, starting stirring, then adding molybdate, nickel salt, titanium salt, cerium salt, phosphoric acid, glacial acetic acid and ethylene glycol into deionized water, stirring and dissolving, then dropwise adding the dissolved mixture into the reactor for 10-30 min, and stirring for 20-60 min after dropwise adding is finished to obtain the chromium-free surface treatment solution for the electro-galvanized steel plate.

After the treatment solution is coated and dried on the surface of an electrogalvanized steel plate, an organic and inorganic composite film can be obtained, wherein the organic film is an organic silicon resin film, the organic silicon resin film does not contain amino groups, meanwhile, the organic film is tightly combined with a zinc layer on the surface of the steel plate through epoxy groups in the resin film, and the organic film can be endowed with excellent film-forming property and density by using a long-chain and short-chain silane coupling agent in a certain proportion, wherein the mass ratio of the short-chain silane coupling agent to the long-chain silane coupling agent is (3-10): 1, and the proportion is less than 3: 1, the film layer on the surface of the electrogalvanized steel plate sticks hands at normal temperature, so that the electrogalvanized steel plate cannot be normally used, and when the ratio is more than 10:1, the film layer on the surface of the electrogalvanized steel plate is too brittle, and the film layer is easy to fall off during bending or subsequent processing of the electrogalvanized steel plate; molybdate, nickel salt, titanium salt, cerium salt and phosphoric acid react with the zinc layer in the drying process of the solution on the surface of the zinc layer to generate inorganic salt which is difficult to dissolve in water in the process of raising the pH value of the solution, a plurality of groups of inorganic salts cooperate with each other to form an inorganic conversion film, and the organic-inorganic composite film can improve the corrosion resistance of the surface of the zinc layer; the glacial acetic acid with a certain dosage can adjust the pH value of the treatment liquid, so that the treatment liquid is kept stable, and the glycol can improve the stability of the organic silicon resin in the solution and improve the film forming property of the organic silicon resin.

Compared with the prior art, the invention has the advantages that:

the water-based organic silicon resin is used as an organic component in the chromium-free surface treatment liquid for the electro-galvanized steel sheet, compared with common organic resin, the organic silicon resin has excellent high-temperature resistance, and a passive film obtained by treating the electro-galvanized steel sheet by using the surface treatment liquid has better corrosion resistance, excellent processability and excellent high-temperature yellowing resistance.

Drawings

FIG. 1 is a surface appearance diagram of an electrogalvanized steel sheet subjected to surface treatment by the surface treatment liquid in the example and then subjected to a salt spray resistance test for 120 hours.

Detailed Description

The present invention is further described in detail with reference to the following examples, which are intended to facilitate the understanding of the present invention by those skilled in the art, but are not intended to limit the present invention.

In the following examples, reagents not specifically described are conventional reagents, and information of some raw material manufacturers and the like is as follows:

name of raw materials	Manufacturer of the product	Number plate
			Gamma- (2, 3-glycidoxy) propyltrimethoxysilane	Nanjing Engde New Material technology Co., Ltd	SCA-E87M
Methyltrimethoxysilane	Nanjing Engde New Material technology Co., Ltd	SCA-K01M
			Dodecyl trimethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-K12M
N-hexyl radicalTrimethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-K06M
			Gamma- (2, 3-epoxypropoxy) propyltriethoxysilane	Nanjing Engde New Material technology Co., Ltd	SCA-E87E
Ethyl triethoxysilane	Nanjing Engde New Material technology Co., Ltd	SCA-K02E
			Octadecyl trimethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-K18M
N-hexyl triethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-K12E
			Isopropyl triethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-Ki03E
Isopropyl trimethoxy silane	Nanjing Engde New Material technology Co., Ltd	SCA-Ki03M