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Method for preparing trivalent chromium compound

A technology of compound and trivalent chromium, applied in the direction of chromium compound, chemical instrument and method, inorganic chemistry, etc. Corrosion and anti-fingerprint resistance galvanized steel sheet protection layer and other problems, to achieve the effect of low cost, stable product quality, excellent anti-fingerprint

Inactive Publication Date: 2009-12-23
PANGANG GROUP VANADIUM TITANIUM & RESOURCES +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Therefore, someone proposes to use trivalent chromium compound as the film-forming agent of the plating solution, but the plating solution obtained by using the trivalent chromium compound in the prior art such as chromium chloride, chromium nitrate, etc. cannot obtain corrosion resistance and The protective layer of galvanized steel sheet with excellent fingerprint resistance, especially for hot-dip galvanized steel sheet, requires the thickness of the coating to be extremely thin, generally only 1-3 microns, and must have self-lubricating properties, and the lubrication of the film layer must be ensured Performance and corrosion resistance must be coated on electro-galvanized sheets with low surface roughness. Therefore, self-lubricating sheets produced by Japanese steel companies and Korean steel companies use electro-galvanized steel sheets as substrates
When using trivalent chromium compounds in the prior art such as chromium chloride, chromium nitrate, etc. to prepare the coating solution as a self-lubricating coating for hot-dip galvanized steel coils, due to the high surface roughness of hot-dip galvanized steel, A coating excellent in both lubricity and corrosion resistance cannot be obtained

Method used

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preparation example Construction

[0010] According to the preparation method of the trivalent chromium compound provided by the present invention, wherein, the ratio of the hexavalent chromium compound to the reducing agent and the complexing agent can be a ratio conventionally used in the art, generally a value near the stoichiometric ratio , for different reducing agents, the molar ratio of hexavalent chromium compound to reducing agent may be different. The molar ratio of the hexavalent chromium compound to the total amount of the reducing agent and the complexing agent is 1:0.3-4, the weight ratio of the reducing agent to the complexing agent is 1:0.1-10, and the amount of water is 1:0.1-10. 3-10 times the weight of the compound, the temperature is 10-50°C, and the time is 30-200 minutes.

[0011] The molar ratio of the hexavalent chromium compound to the total amount of the reducing agent and the complexing agent is 1:0.6-1.5, and the weight ratio of the reducing agent to the complexing agent is 1:0.5-5. ...

Embodiment 1

[0025] This embodiment is used to illustrate the preparation method of the trivalent chromium compound provided by the present invention.

[0026] Add 300 kg of deionized water into a 3000-liter enamel reactor, then add 50 kg of chromic anhydride, start the stirrer of the reactor and stir for 10 minutes to dissolve the chromic anhydride. After the chromic anhydride is completely dissolved, add 100 kg of 2,3,4-trihydroxyglutaric acid at room temperature, and start the stirrer quickly to dissolve the trihydroxyglutaric acid quickly. When the solution does not bubble, it is judged that the reaction is complete, and the desired trivalent chromium compound is obtained. According to Xu Wenlong, Electroplating and Environmental Protection, 1992, Volume 12, No. 3, P29-31, it is determined that the product contains a large amount of trivalent chromium compounds, and the content of hexavalent chromium compounds is less than 0.01 g / L.

Embodiment 2

[0028] This embodiment is used to illustrate the preparation method of the trivalent chromium compound provided by the present invention.

[0029] Under the condition of stirring, 20 kg of methanol was added to 20 kg of maleic acid, and after mixing uniformly, a methanol-maleic acid mixture was obtained for subsequent use.

[0030] Add 100 kg of deionized water to a 2000-liter plastic bucket, then add 20 kg of chromic anhydride, and stir for 10 minutes with a polytetrafluoroethylene stirrer. After the chromic anhydride is completely dissolved, add the above-mentioned Prepared methanol-maleic acid mixed solution, until the reaction system turns light green purple (2 hours from the beginning of adding methanol-maleic acid mixed solution), the desired trivalent chromium compound can be obtained. According to Xu Wenlong, Electroplating and Environmental Protection, 1992, Volume 12, No. 3, P29-31, it is determined that the product contains a large amount of trivalent chromium compo...

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Abstract

The invention provides a method for preparing a trivalent chromium compound. The method comprises the following steps that a hexavalent chromium compound contacts with a reducing agent and a complexing agent under the existence of water, wherein the reducing agent is a substance capable of reducing hexavalent chromium into trivalent chromium; and the complexing agent is a substance capable of having complexation with trivalent chromium ions. When the trivalent chromium compound prepared by the method is adopted as a film forming agent of a galvanized self-lubricating steel plate, an obtained self-lubricating coating has obviously improved fingerprint resistance, corrosion resistance and adhesive force as well as obviously reduced coefficient of dynamic friction.

Description

technical field [0001] The invention relates to a preparation method of a trivalent chromium compound. Background technique [0002] Galvanized materials, such as galvanized steel sheets or steel coils, are easily corroded by oxygen and water in the environment during production, storage, transportation and use. In order to prevent corrosion, chromate, etc. containing Cr are mainly used now. 6+ The treatment agent forms a layer of chromate passivation film on the galvanized steel plate, and then heats and dries to form a covering film. [0003] However, for galvanized chromate passivation film, especially chromate passivation film of galvanized steel sheet or steel coil, in order to ensure the silver-white luster of the zinc layer, light-colored passivation film such as colorless transparent or blue-white is mainly used. Chemical film, Cr in the film layer 6+ The content is less, and the thickness of the film layer is thin, and it only plays a short-term anti-corrosion ef...

Claims

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Application Information

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IPC IPC(8): C01G37/00
CPCC23C2222/10
Inventor 田冰张勇刚马建权邹永金郭太雄许哲峰张爱萍李国安
Owner PANGANG GROUP VANADIUM TITANIUM & RESOURCES
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