阅读说明：本技术 一种镀锌板无铬环保钝化剂及制备使用方法 (Chromium-free environment-friendly passivator for galvanized sheet and preparation and use method thereof ) 是由 杨洪刚 吕家舜 姜效军 李锋 徐闻慧 于 2019-10-08 设计创作，主要内容包括：本发明涉及一种镀锌板无铬环保钝化剂及制备使用方法,按重量份包括以下成分：潜固化型聚氨酯乳液20-40份；锆偶联剂5-20份；有机锌防锈剂0.5-5份；棕榈蜡乳液1-8份；纯水40-65份；所述的有机锌防锈剂为ALCOPHOR；纯水的电导率小于0.1×10<Sup>-6</Sup>mΩ.cm<Sup>-1</Sup>。优点是：利用潜固化型聚氨酯乳液固化时在锌板上交联反应形成膜组分,有机络合锆偶联剂,避免氟离子、硫酸根离子、氯离子的腐蚀,有机锌防锈剂与聚氨酯、偶联剂形成穿插交联反应,形成牢固的钝化膜,具有优异的防腐、抗磨、润滑作用。(The invention relates to a chromium-free environment-friendly passivator for a galvanized sheet and a preparation and use method thereof, wherein the passivator comprises the following components in parts by weight: 20-40 parts of latent curing type polyurethane emulsion; 5-20 parts of a zirconium coupling agent; 0.5-5 parts of organic zinc antirust agent; 1-8 parts of palm wax emulsion; 40-65 parts of pure water; the organic zinc antirust agent is ALCOPHOR; the pure water has a conductivity of less than 0.1 × 10 ‑6 mΩ.cm ‑1 . The advantages are that: when the latent curing type polyurethane emulsion is used for curing, a film component is formed on a zinc plate through a cross-linking reaction, a zirconium coupling agent is organically complexed, corrosion of fluorine ions, sulfate ions and chloride ions is avoided, an organic zinc antirust agent, polyurethane and the coupling agent form an alternate cross-linking reaction, a firm passivation film is formed, and the latent curing type polyurethane emulsion has excellent corrosion prevention, wear resistance and lubrication effects.)

1. The chromium-free environment-friendly passivator for the galvanized sheet is characterized by comprising the following components in parts by weight:

2. the galvanized sheet chromium-free environment-friendly passivator according to claim 1, wherein the organic zinc rust inhibitor is ALCOPHOR.

3. The galvanized sheet chromium-free environment-friendly passivator according to claim 1, wherein the conductivity of pure water is less than 0.1 x 10^-6mΩ.cm^-1。

4. The preparation method of the chromium-free environment-friendly passivator for the galvanized sheet according to claim 1, characterized by comprising the following steps:

1) uniformly mixing the latent curing type polyurethane emulsion and the zirconium coupling agent;

2) uniformly mixing an organic zinc antirust agent and pure water;

3) mixing the mixed solution obtained in the step 1) and the step 2), adding the carnauba wax emulsion, and grinding in a sand mill for more than 10min to obtain the uniform chromium-free environment-friendly passivator.

5. The use method of the chromium-free environment-friendly passivator for the galvanized sheet according to claim 1, characterized by comprising the following steps:

1) degreasing, cleaning and drying the galvanized steel sheet;

2) the galvanized sheet is evenly coated with the chromium-free environment-friendly passivating agent on two sides through a roller coater, and the coating amount is 1.2-2.0g/m on one side²；

3) After being coated, the galvanized steel sheet is dried by hot air, and the temperature of the galvanized steel is controlled at 70-95 ℃.

Technical Field

The invention relates to a chromium-free environment-friendly passivator for a galvanized sheet and a preparation and use method thereof.

Background

Galvanization is an effective method for improving the atmospheric corrosion resistance of steel, but in a humid environment, a galvanized layer is easy to corrode, white loose corrosion products are generated on the surface, dark gray products are sometimes generated, and the steel plate is seriously influencedThe appearance and performance of the galvanized sheet, therefore, the galvanized sheet is passivated and covered with a protective film. The passivating agent is a necessary product in the galvanizing processing process, the surface of a newly manufactured galvanized plate is very active, and the galvanized plate needs to be passivated before being packaged and stored in a warehouse so as to improve the antirust capacity in the storage and transportation processes. The action mechanism of the passivating agent is to seal micropores on the surface of the steel plate, and primary batteries are easily formed at the micropores to aggravate corrosion. The passivated steel plate has a smoother and more beautiful appearance, and does not influence subsequent processing such as welding, polishing and the like. The traditional passivation process adopts hexavalent chromic acid solution or sodium nitrite solution, and has self-repairing capability. Both of the above are carcinogenic substances, and the country has gradually abolished, especially exported products, and the use is forbidden. If the water discharged by European Union is not allowed to exceed 0.3mg/m³Some countries even propose no chromium (Cr) in wastewater⁶⁺) The ROHS directive of no hexavalent chromium is started to be implemented in 7 months in the European Union in 2006. Sodium nitrite is in contact with the skin for a long time, so that people can have serious skin allergy, and the taking of a few grams of sodium nitrite by mistake constitutes dangerous methemoglobinemia.

In recent years, the research on passivators is very active, more than 100 patent applications are already carried out in China, 50-60 passivators for galvanized plates are also available, and the passivators mainly focus on inorganic component passivators such as silicate, molybdate, titanate, zirconate and rare earth cerium lanthanum, but the antirust effect is not good when the protective film is too thin. The passivator composed of high polymer films such as conventional acrylic emulsion, polyurethane emulsion and the like has poor bonding strength with a metal matrix and also has unsatisfactory antirust effect. The third category is that the inorganic organic polymer composite passivator is improved compared with the two categories, but the adopted fluotitanate and fluozirconate assistants such as hydrogen fluoride, potassium fluoride, ammonium fluoride, sodium fluoride, fluosilicate and the like have obvious corrosion effect on the galvanized sheet; the adopted silane coupling agent and titanate coupling agent are easy to hydrolyze and have poor stability; the adopted anions of the rust inhibitors such as titanyl sulfate, lanthanum chloride, titanium trichloride and the like also have corrosion effect, and the high-grade chromium-free environment-friendly passivator which can be really used for industrial production is few.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a chromium-free environment-friendly passivator for a galvanized sheet and a preparation and use method thereof, which can meet the current environment-friendly requirement and can well protect a galvanized substrate.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a chromium-free environment-friendly passivator for a galvanized sheet comprises the following components in parts by weight:

the organic zinc antirust agent is ALCOPHOR.

The pure water has an electric conductivity of less than 0.1 × 10^-6mΩ.cm^-1。

Latent curing polyurethane emulsion is used as main filming matter and has exposed and cured reaction group during high temperature stoving. Too much tends to cause microcracking in the film, and increases the cost, and too little protection becomes weak. Selecting latent curing type single-component polyurethane emulsion.

The zirconium coupling agent further crosslinks and cures the polymer film, and when the amount is less than 5 parts, the curing is slowed down.

The organic zinc rust inhibitor (trade name alcopor) is distributed in the film phase and reacts with the zinc surface further to play a role in rust prevention. When the content is too large, the crystalline particles become large to affect the integrity of the film. ALCOPHOR 827 available from Hangao or Hechuan chemical may be selected.

The palm wax emulsion can enable the film to have lubricity on the premise of not influencing the antirust capacity, is convenient for subsequent shearing processing precision, and has the characteristic of small corrosivity. Less than 1 part is preferable because lubricity will be lost and foaming will occur when too much is applied.

Pure water (conductivity less than 0.1X 10)^-6mΩ.cm^-1) High purity water is the basis and guarantee of rust prevention.

A preparation method of a chromium-free environment-friendly passivator for a galvanized sheet comprises the following steps:

1) uniformly mixing the latent curing type polyurethane emulsion and the zirconium coupling agent;

2) uniformly mixing an organic zinc antirust agent and pure water;

3) mixing the mixed solution obtained in the step 1) and the step 2), adding the palm wax emulsion, and grinding in a sand mill for more than 10min to obtain the uniform chromium-free environment-friendly passivator.

A using method of a chromium-free environment-friendly passivator for a galvanized sheet comprises the following steps:

1) degreasing, cleaning and drying the galvanized steel sheet;

2) the galvanized sheet is evenly coated with the chromium-free environment-friendly passivating agent on two sides through a roller coater, and the coating amount is 1.2-2.0g/m on one side²；

3) After being coated, the galvanized steel sheet is dried by hot air, and the temperature of the galvanized steel is controlled at 70-95 ℃.

Compared with the prior art, the invention has the beneficial effects that:

the chromium-free environment-friendly passivator for the galvanized sheet utilizes cross-linking reaction on the galvanized sheet to form a membrane component when latent curing type polyurethane emulsion is cured, organically complexes a zirconium coupling agent to avoid corrosion of fluoride ions, sulfate ions and chloride ions, and forms a firm passivation membrane by the interpenetrating cross-linking reaction of an organic zinc antirust agent, polyurethane and the coupling agent, and has excellent corrosion prevention, wear resistance and lubrication effects. Under the condition of 85-95 ℃ of plate temperature, the drying speed is fast, the involucra has certain toughness, and the impact resistance is improved. The bonding strength, the rust resistance, the aging resistance and other key indexes are excellent, and white rust does not exist within 72 hours of a salt spray corrosion test.

Drawings

FIG. 1 is a first micrograph of a galvanized sheet treated with a chromium-free environmental passivation agent for galvanized sheets.

FIG. 2 is a second micrograph of a galvanized sheet treated with a chromium-free environmental passivation agent for galvanized sheets.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the present invention is not limited to the following embodiments.

A chromium-free environment-friendly passivator for a galvanized sheet comprises the following components in parts by weight:

the organic zinc antirust agent is ALCOPHOR. The pure water has a conductivity of less than 0.1 × 10^-6mΩ.cm^-1. The carnauba wax emulsion is preferably a carnauba wax emulsion.

Latent curing polyurethane emulsion is used as main filming matter and has exposed and cured reaction group during high temperature stoving. Too much tends to cause microcracking in the film, and increases the cost, and too little protection becomes weak. Selecting latent curing type single-component polyurethane emulsion.

The zirconium coupling agent further crosslinks and cures the polymer film, and when the amount is less than 5 parts, the curing is slowed down.

The organic zinc rust inhibitor (trade name alcopor) is distributed in the film phase and reacts with the zinc surface further to play a role in rust prevention. When the content is too large, the crystalline particles become large to affect the integrity of the film. ALCOPHOR 827 available from Hangao or Hechuan chemical may be selected.

The carnauba wax emulsion can enable the film to have lubricity on the premise of not influencing the antirust capacity, and is convenient for subsequent shearing processing precision. Less than 1 part is preferable because lubricity will be lost and foaming will occur when too much is applied.

Pure water (conductivity less than 0.1X 10)^-6mΩ.cm^-1) High purity water is the basis and guarantee of rust prevention.

A preparation method of a chromium-free environment-friendly passivator for a galvanized sheet comprises the following steps:

1) uniformly mixing the latent curing type polyurethane emulsion and the zirconium coupling agent;

2) uniformly mixing an organic zinc antirust agent and pure water;

3) mixing the mixed solution obtained in the step 1) and the step 2), adding the carnauba wax emulsion, and grinding in a sand mill for more than 10min to obtain the uniform chromium-free environment-friendly passivator.

A using method of a chromium-free environment-friendly passivator for a galvanized sheet comprises the following steps:

1) degreasing the galvanized steel sheet, cleaning with pure water, and drying with hot air;

2) the galvanized sheet is evenly coated on two sides by a roller coaterThe galvanized sheet chromium-free environment-friendly passivator has the coating weight of 1.2-2.0g/m on one side²；

3) After being coated, the galvanized steel sheet is dried by hot air, and the temperature of the galvanized steel is controlled to be 85-95 ℃.

The chromium-free environment-friendly passivator for the galvanized sheet comprises the following components in percentage by weight: