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A kind of preparation method of chrome-free environmental protection conversion film before dipping galvanized steel pipe

A technology of galvanized steel pipe and conversion film, applied in the direction of metal material coating process, etc., can solve the problems of coating peeling, decreased anti-corrosion effect, poor adhesion, etc., and achieve the effect of increasing the thickness of the film layer and improving the corrosion resistance.

Active Publication Date: 2021-06-18
ZHEJIANG WUYUAN TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In the prior art, there are the following technical problems: 1. If the hot-dip galvanized layer is not treated, its corrosion resistance is poor, and black spots or white rust are easily generated in the environment, and the anti-corrosion effect is greatly reduced. Furthermore, the galvanized steel pipe The adhesion between itself and the dipping PE powder is extremely poor, and the interface between the PE coating and the workpiece is easily corroded by the medium, thus forming voids or corrosion products, resulting in coating peeling off; 2. Chromate passivation is simple in process and low in cost , has the advantage of good anti-corrosion effect on the galvanized layer, and is widely used in many fields, but hexavalent chromium is highly toxic and carcinogenic, and poses serious harm to the human body and the environment

Method used

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  • A kind of preparation method of chrome-free environmental protection conversion film before dipping galvanized steel pipe
  • A kind of preparation method of chrome-free environmental protection conversion film before dipping galvanized steel pipe
  • A kind of preparation method of chrome-free environmental protection conversion film before dipping galvanized steel pipe

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Experimental program
Comparison scheme
Effect test

Embodiment a

[0036] 1) Cleaning and activation: immerse the galvanized steel pipe in an inorganic or organic acid bath solution, in which the free acidity is 15-50 Pt, the surfactant is 0.5 part of fatty alcohol polyoxyethylene ether, the temperature is normal temperature, and the time is 1-3 minutes. The pH adjusters are hydrochloric acid and sulfuric acid.

[0037] 2) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, the pH>2, the temperature is normal temperature, and the time is 1-2 minutes.

[0038] 3) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, pH>5, and the temperature should be normal temperature for 1-2 minutes.

[0039] 4) Chromium-free conversion: Inorganic additives in the raw materials in the chromium-free conversion solution are 2 parts of fluozirconic acid, 1 part of hydrofluoric acid, 1 part of manganese nitrate; 0.3 parts of sodium molybdate; 0.1 part of ferrou...

Embodiment b

[0045] 1) Cleaning and activation: immerse the galvanized steel pipe in the inorganic or organic acid bath solution, in which the free acidity is 15-50Pt, the surfactant is 1 part of fatty alcohol polyoxyethylene ether, the temperature is normal temperature, and the time is 1-3min. The acids used are sulfuric acid and hydrofluoric acid.

[0046] 2) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, the pH>2, the temperature is normal temperature, and the time is 1-2 minutes.

[0047] 3) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, pH>5, and the temperature should be normal temperature for 1-2 minutes.

[0048]4) Chromium-free transformation: Inorganic additives in the raw materials in the chromium-free transformation liquid are 5 parts of fluozirconic acid, 1.5 parts of hydrofluoric acid, 4 parts of manganese nitrate; 0.4 part of sodium molybdate; 0.6 part of ferrous...

Embodiment c

[0055] 1) Cleaning and activation: immerse the galvanized steel pipe in the inorganic or organic acid bath solution, in which the free acidity is 15-50Pt, the surfactant is 2 parts of fatty alcohol polyoxyethylene ether, the temperature is normal temperature, and the time is 1-3min. The acids used are sulfuric acid and hydrofluoric acid.

[0056] 2) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, the pH>2, the temperature is normal temperature, and the time is 1-2 minutes.

[0057] 3) Water washing: immerse the cleaned and activated workpiece in water, the water should keep overflowing, pH>5, and the temperature should be normal temperature for 1-2 minutes.

[0058] 4) Chromium-free conversion: Inorganic additives in raw materials in the chromium-free conversion liquid are 10 parts of fluozirconic acid, 2 parts of hydrofluoric acid, 5 parts of manganese nitrate; 0.5 parts of sodium molybdate; 1 part of ferrous sulfate; co...

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Abstract

The invention discloses a method for preparing a chrome-free environmental protection conversion film before dipping a galvanized steel pipe. The method comprises the following steps: 1) acid degreasing; 2) washing with water; 3) washing with water; 4) chromium-free conversion: raw materials in the chromium-free conversion liquid are inorganic additives, complexing agents, pH regulators, rare earth salts and silanes, and organic The acid is used as a cross-linking accelerator of the chemical conversion film, so that the combination of the silane liquid and the rare earth salt can form a film with the surface of the galvanized steel pipe, with a pH value of 2.5-4.0, a temperature of 25-40°C, and a time of 3-5 minutes; 5) washing with water ; 6) pre-baking; 7) dipping: fluidization; 8) leveling and curing. Compared with the prior art, the preparation method of the chromium-free environmental protection conversion film of the galvanized steel pipe before dipping has the following beneficial effects: not only the conversion film has good corrosion resistance, but also further reduces the treatment of waste water, and the chromium-free Environment friendly.

Description

technical field [0001] The invention relates to a method for preparing a conversion film of a galvanized steel pipe, in particular to a method for preparing a chromium-free and environment-friendly conversion film of a galvanized steel pipe before dipping. Background technique [0002] Dip molding: refers to the process of coating plastic powder on the metal surface by heating to achieve anti-corrosion processing. [0003] Dip molding is a heating process, metal preheating, impregnation, and curing. During immersion, the heated metal sticks to the surrounding material, the hotter the metal, the longer the immersion time and the thicker the material. Naturally, temperature and dip profile are key factors in determining how much plastisol sticks. Amazing shapes can be made by dipping. Hot-dipping powder raw materials: PE general-purpose dipping powder, PE engineering-type dipping powder, PE pipe-type dipping powder Conversion film: Conversion film is a metal surface produce...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/34C23C22/78
CPCC23C22/34C23C22/78C23C2222/20
Inventor 朱小辉邢爱梅施翔彭强
Owner ZHEJIANG WUYUAN TECH CO LTD
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