CN107815676B

CN107815676B - Multifunctional trivalent chromium passivator capable of continuously and rapidly treating surface of strip steel and preparation method and application thereof

Info

Publication number: CN107815676B
Application number: CN201711189707.1A
Authority: CN
Inventors: 杨维毅; 夏雨; 周宪民
Original assignee: SHENYANG PARKERIZING CO Ltd
Current assignee: SHENYANG PARKERIZING CO Ltd
Priority date: 2017-11-24
Filing date: 2017-11-24
Publication date: 2020-05-12
Anticipated expiration: 2037-11-24
Also published as: CN107815676A

Abstract

The invention relates to a multifunctional trivalent chromium passivator capable of continuously and rapidly treating the surface of strip steel, and a preparation method and application thereof. The trivalent chromium passivator provided by the invention is prepared from a trivalent chromium compound, liquid fumed silica or a silane coupling agent, a complexing agent, inorganic acid, a film-forming aid, wax emulsion, a wetting agent and water. The trivalent chromium passivator provided by the invention has high corrosion resistance, humidity resistance, water resistance, high temperature resistance, lubricity, alkali resistance, solvent resistance, coating property and certain self-repairing capability, and can continuously and rapidly form a uniform and compact nano-scale oxide conversion film on the surface of a steel plate. The passivating agent disclosed by the invention is short in film forming time and is suitable for a continuous coating production line of a roller coater for high-speed production of strip steel.

Description

Multifunctional trivalent chromium passivator capable of continuously and rapidly treating surface of strip steel and preparation method and application thereof

Technical Field

The invention relates to a multifunctional trivalent chromium passivator for a high-speed continuous galvanizing production line in a steel mill, which can quickly form a passivation film on the surface of a steel plate, and a preparation method and application thereof.

Background

With the increase of economic strength in China, the demand of steel plates in the automobile industry, the household appliance industry, the building industry and the like is continuously increased, and the requirements on the material quality and the environmental protection of the plates are also continuously increased. The application amount of galvanized plates in the industries is multiplied every year, and the requirements on corrosion prevention and rust prevention of the galvanized plates are higher and higher. Zinc is often used as a protective layer for steel because of its low reduction potential, low cost, etc., but it is chemically active and easily corroded, and thus it is generally necessary to passivate the zinc coating. The hexavalent chromium passivator has the advantages of simple operation, low cost and simple and convenient control, and the obtained passivation film has the advantages of good corrosion resistance, beautiful appearance, self-repairing capability and the like, but the hexavalent chromium is a highly toxic substance, has carcinogenic and teratogenic effects and cannot meet the requirements of the European Union RoHS standard on heavy metals such as cadmium, mercury, lead, hexavalent chromium and the like. Trivalent chromium passivation has properties similar in many respects to hexavalent chromium passivation, but is only one percent toxic to hexavalent chromium. A large amount of trivalent chromium passivators are applied to a continuous galvanizing production line in a steel mill at the present stage, and are coated on the surface of a steel plate by a roller coater to form a passivation film quickly and uniformly, but the passivation film has a single function and only has an anti-corrosion and anti-rust function. The current customers have more and more functional requirements, higher performance requirements and lower cost requirements, and the development of the multifunctional high-performance trivalent chromium passivator is also an essential product along with the development of the market.

Disclosure of Invention

The invention aims to provide a trivalent chromium passivator with certain self-repairing capability, which is obtained by reasonably preparing trivalent chromium salt, liquid fumed silica or silane coupling agent, inorganic acid, wax emulsion and additive.

The technical scheme adopted by the invention is as follows: a multifunctional trivalent chromium passivator for treating the surface of band steel continuously and quickly is prepared from

Preferably, the trivalent chromium compound is one or two of chromium sulfate, chromium nitrate, chromium phosphate and chromium dihydrogen phosphate.

Preferably, the silane coupling agent is an aminosilane coupling agent and/or an epoxysilane coupling agent.

Preferably, the complexing agent is one or two of citric acid, acetic acid, lactic acid and oxalic acid.

Preferably, the inorganic acid is one, two or three of phosphoric acid, nitric acid or hydrofluoric acid.

Preferably, the film-forming assistant is two, three or four of cobalt nitrate, sodium nitrate, potassium nitrate, ammonium fluoride, ammonium bifluoride, sodium dihydrogen phosphate or ammonium dihydrogen phosphate.

Preferably, the wax emulsion is a nonionic oxidized polyethylene wax.

Preferably, the wetting agent is fatty alcohol-polyoxyethylene ether.

A preparation method of a multifunctional trivalent chromium passivator capable of continuously and rapidly treating the surface of strip steel comprises the following steps: preparing the materials according to the proportion, adding the complexing agent into water in sequence under stirring, and stirring for 10-20 min; adding inorganic acid, and stirring for 15-30 min; adding liquid fumed silica and/or silane coupling agent, stirring for 10-60min to completely hydrolyze the liquid fumed silica and/or silane coupling agent; adding film forming assistant and stirring for 20-40 min; adding wax emulsion, and stirring for 3-7 min; adding trivalent chromium compound, and stirring for 10-20 min; adding wetting agent, and stirring for 5-10 min.

The multifunctional trivalent chromium passivator capable of continuously and rapidly treating the surface of strip steel is applied to the formation of a passivation film on the surface of a steel plate. The method comprises the following steps: the multifunctional trivalent chromium passivating agent is continuously and rapidly coated on the upper surface and the lower surface of a galvanized plate by a roller coater for 2-5 seconds, and then dried at 60-80 ℃ for 10-15 seconds to form a thin passivation film on the surface of the steel plate.

The invention has the beneficial effects that:

1. the passivating agent disclosed by the invention can passivate the metal surface by continuous and rapid roller coating treatment, and a uniform and compact passivating film with excellent performance is formed at a lower baking temperature in a shorter treatment time, so that the passivating agent has a very important application value.

2. According to the passivating agent disclosed by the invention, by adding a plurality of raw material components, a passivating film formed on the surface of a steel plate has certain self-repairing capability, excellent corrosion resistance, lubricating property, humidity and heat resistance, water resistance, coating property, high temperature resistance, solvent resistance, hydrophobic function of the surface of the steel plate and other properties.

3. The passivator disclosed by the invention has the advantages of good product stability, long shelf life, low odor and convenience in field operation.

4. When strip steel is continuously produced, particularly on a high-speed continuous galvanizing production line in a steel mill, a passivating film is quickly formed on the surface of a steel plate by adopting a coating method of a roller coater, so that the surface of the steel plate has high corrosion resistance and lubricity, the lubricity and the processability of the steel plate during stamping deformation are improved, and the process of electrostatic spraying of rolling oil can be omitted, thereby reducing the cost.

5. The passivating agent disclosed by the invention has high corrosion resistance, humidity resistance, water resistance, high temperature resistance, lubricity, alkali resistance, solvent resistance and coating property, has a certain self-repairing capability, and can continuously and quickly form a uniform and compact nano-scale oxide conversion film on the surface of a steel plate. After liquid fumed silica is added, the surface of the steel plate has hydrophobicity; after the wax emulsion is added, the lubricating property and the processability of the steel plate during stamping deformation can be improved, the phenomenon of blackening of a passive film after stamping is solved, and the process of electrostatic spraying of rolling oil is omitted, so that the cost is reduced.

6. The passivating agent disclosed by the invention is short in film forming time and is suitable for a continuous coating production line of a roller coater for high-speed production of strip steel.

Detailed Description

Example 1

Composition of multifunctional trivalent chromium passivator capable of continuously and rapidly treating surface of strip steel

(II) preparation method

Sequentially adding lactic acid into pure water and stirring for 10min at a medium speed of 500 r/min; adding phosphoric acid and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding an aminosilane coupling agent, and stirring for 30min to completely hydrolyze the aminosilane coupling agent; adding liquid fumed silica, and stirring for 10 min; adding ammonium fluoride and stirring for 10 min; adding cobalt nitrate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium nitrate, and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether, stirring for 7min, and stirring to obtain the target product.

Example 2

(II) preparation method

Sequentially adding acetic acid into pure water and stirring at a medium speed of 500r/min for 10 min; adding citric acid, and stirring for 10 min; adding phosphoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding an epoxy silane coupling agent, and stirring for 30min to completely hydrolyze the silane coupling agent; adding liquid fumed silica, and stirring for 10 min; adding potassium nitrate, and stirring for 10 min; adding sodium dihydrogen phosphate, and stirring for 10 min; adding ammonium fluoride and stirring for 10 min; adding cobalt nitrate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium sulfate and stirring for 10 min; adding chromium phosphate and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether, stirring for 7min, and stirring to obtain the target product.

Example 3

(II) preparation method

Sequentially adding acetic acid into pure water and stirring at a medium speed of 500r/min for 10 min; adding oxalic acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding an aminosilane coupling agent, stirring for 30min, adding an epoxy silane coupling agent, and stirring for 30min to completely hydrolyze silane; adding sodium nitrate, and stirring for 10 min; adding cobalt nitrate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium dihydrogen phosphate, and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether, stirring for 7min, and stirring to obtain the target product.

Example 4

(II) preparation method

Sequentially adding acetic acid into pure water and stirring at a medium speed of 500r/min for 10 min; adding lactic acid, and stirring for 10 min; adding phosphoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding an aminosilane coupling agent, and stirring for 30min to completely hydrolyze the aminosilane coupling agent; adding cobalt nitrate, and stirring for 10 min; adding sodium dihydrogen phosphate, and stirring for 10 min; adding ammonium bifluoride and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium nitrate, and stirring for 10 min; adding chromium dihydrogen phosphate, and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether for 7min, and stirring uniformly to obtain the target product.

Example 5

(II) preparation method

Sequentially adding lactic acid into pure water and stirring for 10min at a medium speed of 500 r/min; adding oxalic acid and stirring for 10 min; adding phosphoric acid and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding liquid fumed silica, and stirring for 10 min; adding sodium dihydrogen phosphate, and stirring for 10 min; adding ammonium fluoride and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium sulfate and stirring for 10 min; adding chromium nitrate, and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether for 7min, and stirring uniformly to obtain the target product.

Example 6

(II) preparation method

Sequentially adding citric acid into pure water and stirring for 10min at a medium speed of 500 r/min; adding phosphoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding an aminosilane coupling agent and stirring for 30 min; adding liquid fumed silica, and stirring for 10 min; adding sodium dihydrogen phosphate, and stirring for 10 min; adding potassium nitrate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium phosphate and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether, stirring for 7min, and stirring to obtain the target product.

Example 7

(II) preparation method

Sequentially adding acetic acid into pure water and stirring at a medium speed of 500r/min for 10 min; adding phosphoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding epoxy silane coupling agent and stirring for 30 min; adding ammonium bifluoride and stirring for 10 min; adding ammonium dihydrogen phosphate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium dihydrogen phosphate, and stirring for 10 min; adding chromium sulfate and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether for 7min, and stirring uniformly to obtain the target product.

Example 8

(II) preparation method

Sequentially adding acetic acid into pure water and stirring at a medium speed of 500r/min for 10 min; adding lactic acid, and stirring for 10 min; adding phosphoric acid and stirring for 10 min; adding nitric acid, and stirring for 10 min; adding hydrofluoric acid and stirring for 10 min; adding an aminosilane coupling agent and stirring for 30 min; adding epoxy silane coupling agent, stirring for 30min and hydrolyzing completely; adding sodium dihydrogen phosphate, and stirring for 10 min; adding cobalt nitrate, and stirring for 10 min; adding nonionic oxidized polyethylene wax, and stirring for 5 min; adding chromium nitrate, and stirring for 10 min; adding chromium phosphate and stirring for 10 min; adding fatty alcohol-polyoxyethylene ether, stirring for 7min, and stirring to obtain the target product.

Example 9 application of a multifunctional trivalent chromium passivator for continuously and rapidly treating the surface of strip steel

The method comprises the following steps: the multifunctional trivalent chromium passivator prepared in the embodiments 1-8 of the invention adopts a roller coater coating method to quickly form a passivation film on the surface of the galvanized strip steel. The method comprises the following specific steps: after degreasing, washing and drying the galvanized steel sheet, the medicament prepared in the embodiment 1-8 is subjected to a coating experiment by a roller coater, the coating time is 2-5 seconds, and the medicament is dried for 10-15 seconds at the temperature of 60-80 ℃, so that a thin layer of passive film is formed on the surface of the galvanized steel sheet.

As a result: the humidity and heat resistance delta E is less than 2.8, and the high temperature resistance delta E is less than 1.2 (the industry standard is that the humidity and heat resistance delta E is less than 5 and the high temperature resistance delta E is less than 3); better water resistance, alkali resistance, solvent resistance, delta E < 0.8 (industry standard: water resistance delta E < 3, alkali resistance delta E < 3, solvent resistance delta E < 3), and excellent paintability. The corrosion resistance is greatly improved by adding the nano silicon dioxide and the silane coupling agent, the plane neutral salt spray test can reach more than 240h, the corrosion area is less than 5% (the industrial standard: 72h neutral salt spray, the plate surface corrosion area is less than 5%), the cross salt spray test can reach more than 200h, and the self-repairing capability is better. By adding the nonionic oxidized polyethylene wax, the surface of the steel plate has better lubricity, the surface dynamic friction coefficient is less than 0.15 (the surface of the common trivalent chromium passivation plate has no lubricity, and the dynamic friction coefficients are all more than 0.4), the base plate can be well protected when the steel plate is deformed by stamping, the phenomenon that the passivation film is blackened after stamping is solved, and the process and the cost of electrostatic spraying of the calendering oil are saved.

Claims

1. The multifunctional trivalent chromium passivator capable of continuously and rapidly treating the surface of strip steel is characterized by being prepared from the following raw materials in percentage by weight:

10% of chromium nitrate, 2% of an aminosilane coupling agent, 1% of liquid fumed silica, 2% of lactic acid, 4.5% of phosphoric acid, 1% of nitric acid, 0.2% of hydrofluoric acid, 0.5% of ammonium fluoride, 1% of cobalt nitrate, 3% of nonionic oxidized polyethylene wax, 0.1% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or, by weight, 40% of chromium sulfate 15%, 30% of chromium phosphate 10%, 4% of epoxy silane coupling agent, 1% of liquid fumed silica, 2% of acetic acid, 2% of citric acid, 2% of phosphoric acid, 5% of nitric acid, 0.2% of potassium nitrate, 2% of sodium dihydrogen phosphate, 0.5% of ammonium fluoride, 2.3% of cobalt nitrate, 2% of nonionic oxidized polyethylene wax, 0.5% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or 35wt% of chromium dihydrogen phosphate 25%, aminosilane coupling agent 2%, epoxy silane coupling agent 4%, acetic acid 3%, oxalic acid 2%, nitric acid 4%, hydrofluoric acid 1%, sodium nitrate 0.5%, cobalt nitrate 1.5%, nonionic oxidized polyethylene wax 1%, fatty alcohol-polyoxyethylene ether 1%, and the balance of pure water;

or 10% of chromium nitrate, 10% of chromium dihydrogen phosphate, 5% of an aminosilane coupling agent, 1.5% of acetic acid, 1.5% of lactic acid, 7.9% of phosphoric acid, 2% of nitric acid, 0.1% of hydrofluoric acid, 1.5% of cobalt nitrate, 2% of sodium dihydrogen phosphate, 0.5% of ammonium bifluoride, 2% of nonionic oxidized polyethylene wax, 0.3% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or 20% of chromium sulfate, 5% of chromium nitrate, 5% of liquid fumed silica, 2% of lactic acid, 2% of oxalic acid, 6.2% of phosphoric acid, 0.8% of hydrofluoric acid, 2% of sodium dihydrogen phosphate, 0.5% of ammonium fluoride, 5% of nonionic oxidized polyethylene wax, 0.6% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or 30% of chromium phosphate, 2% of an aminosilane coupling agent, 4% of liquid fumed silica, 5% of citric acid, 7% of phosphoric acid, 3% of nitric acid, 2% of sodium dihydrogen phosphate, 1.5% of potassium nitrate, 3% of nonionic oxidized polyethylene wax, 0.8% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or 15% of chromium dihydrogen phosphate, 10% of chromium sulfate, 7% of epoxy silane coupling agent, 3% of acetic acid, 6.5% of phosphoric acid, 1.5% of nitric acid, 0.4% of hydrofluoric acid, 0.5% of ammonium bifluoride, 2.5% of ammonium dihydrogen phosphate, 4% of nonionic oxidized polyethylene wax, 0.2% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

or 10% of chromium nitrate, 15% of chromium phosphate, 3% of an aminosilane coupling agent, 6% of an epoxy silane coupling agent, 2% of acetic acid, 1.5% of lactic acid, 7.5% of phosphoric acid, 2% of nitric acid, 0.5% of hydrofluoric acid, 2% of sodium dihydrogen phosphate, 1.3% of cobalt nitrate, 1.5% of nonionic oxidized polyethylene wax, 0.3% of fatty alcohol-polyoxyethylene ether and the balance of pure water;

the multifunctional trivalent chromium passivator is used for quickly roll-coating the surface of galvanized strip steel to form a passivation film.

2. A preparation method of a multifunctional trivalent chromium passivator capable of continuously and rapidly treating the surface of strip steel is characterized by comprising the following steps: preparing the materials according to the proportion of claim 1, adding the complexing agent into water in sequence and stirring for 10-20 min; adding inorganic acid, and stirring for 15-30 min; adding liquid fumed silica and/or silane coupling agent, stirring for 10-60min to completely hydrolyze the liquid fumed silica and/or silane coupling agent; adding film forming assistant and stirring for 20-40 min; adding wax emulsion, and stirring for 3-7 min; adding trivalent chromium compound, and stirring for 10-20 min; adding wetting agent, and stirring for 5-10 min.