Finishing liquid for galvanization production line and preparation method of finishing liquid

Abstract

The invention relates to the technical field of hot-dip galvanized plate finishing processes, and particularly discloses a finishing liquid for a galvanizing production line and a preparation method of the finishing liquid, the finishing liquid comprises 4-9% of a lubricant, and the lubricant is a combination of polyol ester and a nano reinforcing agent; 7%-27% of an antirust agent, wherein the antirust agent is a combination of organic acid and alcohol amine; 1.2%-5% of a corrosion inhibitor, wherein the corrosion inhibitor is a combination of benzotriazole and mercaptobenzothiazole; 0.5%-5% of a surface active agent, wherein the surface active agent is nonionic reverse block polyether; 0.3%-1% of a dispersant, wherein the dispersant is a combination of polyisobutylene succinimide and modified polycarboxylate; 0.1%-1% of a bactericide, wherein the bactericide is isothiazolinone; 0.2%-3% of a defoaming agent, wherein the defoaming agent is emulsified silicone oil; 0.2%-3% of an additive, wherein the additive is a combination of diethanol amine, boric acid, molybdate and a nano lubricant; and the balance of deionized water. The finishing liquid provided by the invention is stable in low-temperature performance, good in adhesive force, good in corrosion resistance and environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of hot-dip galvanized sheet finishing technology, and in particular to a finishing solution for galvanizing production lines and its preparation method. Background Technology

[0002] Hot-dip galvanized products have gradually gained an important position in the construction, transportation, home appliance, and packaging industries due to their outstanding corrosion resistance, ease of processing, long service life, environmental friendliness, and economic advantages. However, improper control of temperature, pressure, and zinc bath composition during galvanizing production line operation can easily lead to white streaks on the product surface, affecting product quality. Therefore, the finishing process is an indispensable quality control hub in the galvanizing production line and a crucial link in enhancing product competitiveness.

[0003] Currently, commonly used finishing solutions contain nitrites. While nitrites offer excellent corrosion resistance, they have poor cleaning performance, low surface gloss, and nitrite compounds pose certain health risks. Furthermore, although existing finishing solutions can form a basic lubricating film on the galvanized sheet surface, the film's hardness is insufficient, making it prone to wear under high-pressure finishing processes. The lubrication failure cycle is short, and the finishing solutions have weak zinc powder capture and anti-agglomeration capabilities, easily leading to zinc powder agglomeration on the galvanized sheet surface, resulting in panel impurities, faster wear of the finishing rollers, and a higher panel defect rate. Summary of the Invention

[0004] To address the problems mentioned in the background art, the present invention aims to provide a finishing solution for galvanizing production lines.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A finishing solution for a galvanizing production line, comprising, by percentage: Lubricant 4%-9%, wherein the lubricant is a combination of polyol ester and nano-reinforcing agent; The rust inhibitor is 7%-27%, which is a combination of organic acid and alkanolamine. The rust inhibitor uses a polybasic organic acid containing multiple carboxyl groups, which can form a dense oxide film on the metal surface through chelation. At the same time, multiple polar groups increase the adhesion of molecules to the metal surface, which can effectively block corrosive media from contacting the metal surface and improve the corrosion resistance of the product. The alkanolamine reacts with the organic acid in the component to directly generate amine soap in the liquid. The generated amine soap and free alkanolamine molecules can be adsorbed together on the steel strip surface to form a hydrophobic protective film, which effectively reduces the chemical corrosion of the metal surface. The corrosion inhibitor is 1.2%-5%, which is a combination of benzotriazole and mercaptobenzothiazole. Benzotriazole contains nitrogen atoms in its molecular structure, which can form coordinate bonds with the metal surface. Through adsorption, it forms a chemically stable protective film on the metal surface, effectively blocking the penetration of corrosive media. Mercaptobenzothiazole has 1.3 times the adsorption energy of benzotriazole on the metal surface, which can fill the gaps in the protective film, and has a significant protective effect on the passivation area of ​​the zinc plating layer. The surfactant is 0.5%-5%, and the surfactant is a nonionic reverse-intercalated polyether. The polypropylene oxide (PO) segment in the reverse-intercalated polyether molecule has excellent oleophilicity and adsorption properties, and can be firmly adsorbed onto the metal surface to form a strong and tough lubricating film. The hydrophilic end (EO chain) is on the outside, which makes it soluble in water at low temperature to form a stable solution or emulsion. At the same time, it has excellent hard water resistance and temperature adaptability, and has excellent performance in wetting, emulsification and foam control. The dispersant is 0.3%-1%, which is a combination of polyisobutylene succinimide and modified polycarboxylate. Polyisobutylene succinimide prevents zinc powder agglomeration through steric hindrance effect, and the modified polycarboxylate (molecular weight 8000-10000) has carboxyl groups that can form electrostatic adsorption with the zinc powder surface. Under the dual effect, the zinc powder capture rate is increased from 70% to 95%, avoiding roller marks and pit defects. The bactericide is 0.1%-1%, and the bactericide is isothiazolinone. Isothiazolinone has an inhibitory effect on a variety of bacteria, fungi and algae, and can kill or inhibit the growth of microorganisms even at low concentrations, effectively preventing emulsion demulsification and product deterioration that affects the quality of the board surface. The defoamer is 0.2%-3%, and the defoamer is emulsified silicone oil. Emulsified silicone oil has extremely low surface tension, about 20-21 mN / m, which can spread rapidly to the surface of the foam liquid film, destroy the elasticity of the film and promote the drainage of the liquid film, thereby achieving instantaneous defoaming and effectively eliminating foam generated during the finishing process due to high-speed roller coating, etc. At the same time, it has excellent chemical stability, is resistant to high temperature and oxidation, and does not easily react chemically with other components in the system. Additives of 0.2%-3%, wherein the additives are a combination of diethanolamine, boric acid, molybdate and nano-lubricants; The remainder is deionized water.

[0006] Furthermore, in the lubricant, the polyol ester is one or more of isooctanol phosphate, tridecyl phosphate, or polyethylene glycol diester. The polar ester groups in the polyol ester molecule are selected to strongly adsorb onto the metal surface, forming a dense, low-shear-strength lubricating film with a thickness of 0.1-0.5 μm, high flash point, >240℃, and strong oxidation resistance. The nano-reinforcing agent is nano-boron nitride, which (particle size 50-100 nm) can penetrate into the gaps in the lubricating film, improve the film hardness, reduce wear on the smooth roller, and achieve a rotational oxygen bomb test result of >1200 min.

[0007] Furthermore, in the rust inhibitor, the organic acid is C. 11-12 One or more acids selected from monobasic organic acids, dibasic organic acids, and polybasic mixed acids, wherein the alcohol amine is one or more selected from triethanolamine, diethanolamine, and isopropanolamine.

[0008] Furthermore, in the additive, the nano lubricant is nano zinc oxide. Nano zinc oxide can fill the gaps between zinc flowers, improve the surface smoothness of the galvanized sheet, effectively reduce the roughness of the coating, and at the same time, nano zinc oxide can keep the bacterial inhibition rate above 99%.

[0009] The present invention also provides a method for preparing a finishing solution, the method comprising the following steps: adding deionized water to a reaction vessel, then adding organic acid and alkanolamine, stirring for 30 minutes, then sequentially adding polyol ester, nano-reinforcing agent and reverse intercalation polyether, heating and stirring, raising the temperature to 65°C, adding polyisobutylene succinimide and modified polycarboxylate, stirring for about 1 hour and then lowering the temperature to 50°C, then sequentially adding benzotriazole, mercaptobenzothiazole, isothiazolinone, emulsified silicone oil, diethanolamine, boric acid, molybdate and nano-lubricant, stirring while adding, reacting for 1.5 hours until the solution is a clear and transparent liquid, thereby obtaining the finishing solution.

[0010] The beneficial effects of this invention are as follows: the polar ester groups of the polyol ester can be strongly adsorbed onto the metal surface to form a dense lubricating film with a thickness of 0.1-0.5 μm and low shear strength, with an adsorption capacity of up to 1.5 GPa, providing continuous lubrication protection. Furthermore, the thermal decomposition temperature of the polyol ester can reach 300℃, preventing lubrication failure due to volatilization. It also exhibits good biodegradability. Combined with reverse-intercalated polyethers, it can improve the low-temperature stability of the finishing solution, ensuring the formation of a stable lubrication system even at low temperatures, providing continuous lubrication and protection for the product. The nano-reinforcing agent can penetrate into the gaps in the lubrication film formed by the polyol ester, significantly… This product significantly improves film hardness, enhances the wear resistance of the lubricating film, reduces film wear under high-pressure finishing processes, and lowers finishing roller wear. Polyisobutylene succinimide prevents zinc powder agglomeration through steric hindrance, and the carboxyl groups of the modified polycarboxylate can form electrostatic adsorption with the zinc powder surface. Under this dual effect, the zinc powder capture rate reaches up to 95%, effectively reducing surface defects of galvanized sheets and also reducing the wear of finishing rollers. The composition of rust inhibitors and corrosion inhibitors has been optimized, forming a dense chemical protective film on the strip surface through adsorption, which greatly improves the product's corrosion resistance. The finishing solution is free of nitrites and is environmentally friendly. Detailed Implementation

[0011] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the protection scope of the present invention.

[0012] Example 1 The finishing solution was prepared based on the following components:

[0013] Add deionized water to the reaction vessel, then add neodecanoic acid, adipic acid, and triethanolamine, and stir for 30 minutes. Then add polyethylene glycol diester, nano boron nitride, and reverse-intercalated polyether in sequence, heat and stir, and raise the temperature to 65°C to ensure that the mixed acid and alkanolamine react fully to form amine soap. Then add polyisobutylene succinimide and modified polycarboxylate, stir for about 1 hour, and then lower the temperature to 50°C. Then add benzotriazole, mercaptobenzothiazole, isothiazolinone, emulsified silicone oil, diethanolamine, boric acid, molybdate, and nano zinc oxide in sequence while stirring. React for 1.5 hours until the solution is a clear and transparent liquid to obtain the finishing solution.

[0014] The finishing solution made from this component is a clear and transparent liquid with an acid value of 78.9 mg KOH / g, a total alkalinity of 43.1 mg KOH / g, and an electrical conductivity of 1552 µS / cm. It exhibits excellent lubrication, rust prevention, cleaning, and wettability for steel plates during hot rolling, effectively suppressing foam formation and reducing surface defects. Furthermore, the material selection prioritizes phosphorus-free and nitrite-free components, minimizing environmental pollution and making it an environmentally friendly product.

[0015] Example 2 The finishing solution was prepared based on the following components:

[0016] Deionized water was added to the reaction vessel, followed by neodecanoic acid and triethanolamine. The mixture was stirred for 30 minutes, then tridecyl phosphate, nano boron nitride, and reverse-intercalated polyether were added sequentially. The mixture was heated and stirred until it reached 65°C to ensure that the mixed acid and alkanolamine reacted fully to form amine soap. Then, polyisobutylene succinimide and modified polycarboxylate were added and stirred for about 1 hour. The temperature was then lowered to 50°C, and then benzotriazole, mercaptobenzothiazole, isothiazolinone, emulsified silicone oil, diethanolamine, boric acid, molybdate, and nano zinc oxide were added sequentially while stirring. The mixture was reacted for 1.5 hours until the solution became a clear and transparent liquid, thus obtaining the finishing solution.

[0017] The finishing solution made from this component is a clear and transparent liquid with an acid value of 80.2 mg KOH / g, a total alkalinity of 45.6 mg KOH / g, and an electrical conductivity of 1537 µS / cm. It exhibits good lubrication, rust prevention, and cleaning properties for steel plates during hot rolling, but the dispersibility of this component is poor.

[0018] Example 3 The finishing solution was prepared based on the following components:

[0019] Add deionized water to the reaction vessel, then add neodecanoic acid and triethanolamine, stir for 30 minutes, then add polyethylene glycol diester, tridecanol phosphate, nano boron nitride and reverse-intercalated polyether in sequence, heat and stir, raise the temperature to 65°C to ensure that the mixed acid and alkanolamine react fully to form amine soap, then add polyisobutylene succinimide and modified polycarboxylate, stir for about 1 hour and then lower the temperature to 50°C, then add benzotriazole, mercaptobenzothiazole, isothiazolinone, emulsified silicone oil, diethanolamine, boric acid, molybdate and nano zinc oxide in sequence, stirring while adding, react for 1.5 hours until the solution is a clear and transparent liquid, to obtain the finishing solution.

[0020] The finishing solution made from this component is a clear and transparent liquid with an acid value of 76.5 mg KOH / g, a total alkalinity of 43.7 mg KOH / g, and an electrical conductivity of 1507 µS / cm. It exhibits good lubrication, rust prevention, and cleaning properties for steel plates during hot rolling, but the amount of corrosion inhibitor is relatively small, resulting in weak protection for steel.

[0021] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A finishing solution for a galvanizing production line, characterized in that, The components of the finishing solution, measured by percentage, include: Lubricant 4%-9%, wherein the lubricant is a combination of polyol ester and nano-reinforcing agent; Rust inhibitor 7%-27%, wherein the rust inhibitor is a combination of organic acid and alcohol amine; The corrosion inhibitor is 1.2%-5%, wherein the corrosion inhibitor is a combination of benzotriazole and mercaptobenzothiazole; Surfactant 0.5%-5%, wherein the surfactant is a nonionic reverse-intercalation polyether; The dispersant is 0.3%-1%, wherein the dispersant is a combination of polyisobutylene succinimide and modified polycarboxylate; The fungicide is 0.1%-1%, and the fungicide is isothiazolinone; Defoamer 0.2%-3%, wherein the defoamer is emulsified silicone oil; Additives of 0.2%-3%, wherein the additives are a combination of diethanolamine, boric acid, molybdate and nano-lubricants; The remainder is deionized water.

2. The finishing solution for a galvanizing production line according to claim 1, characterized in that, In the lubricant, the polyol ester is one or more of isooctanol phosphate, tridecyl phosphate, or polyethylene glycol diester, and the nano-reinforcing agent is nano-boron nitride.

3. The finishing solution for a galvanizing production line according to claim 1, characterized in that, In the rust inhibitor, the organic acid is C. 11-12 One or more acids selected from monobasic organic acids, dibasic organic acids, and polybasic mixed acids, wherein the alcohol amine is one or more selected from triethanolamine, diethanolamine, and isopropanolamine.

4. The finishing solution for a galvanizing production line according to claim 1, characterized in that, In the additive, the nano lubricant is nano zinc oxide.

5. A method for preparing a finishing solution for a galvanizing production line, characterized in that, The process includes the following steps: adding deionized water to a reaction vessel, then adding organic acid and alkanolamine, stirring for 30 minutes, then sequentially adding polyol ester, nano-reinforcing agent and reverse-intercalated polyether, heating and stirring, raising the temperature to 65°C, adding polyisobutylene succinimide and modified polycarboxylate, stirring for about 1 hour, lowering the temperature to 50°C, then sequentially adding benzotriazole, mercaptobenzothiazole, isothiazolinone, emulsified silicone oil, diethanolamine, boric acid, molybdate and nano-lubricant, stirring while adding, reacting for 1.5 hours until the solution becomes a clear and transparent liquid, obtaining the finishing solution.

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