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A kind of chromium-free passivation solution for galvanized layer and using method thereof

A chrome-free passivation, galvanized sheet technology, applied in the direction of metal material coating process, can solve the problem of lack of chromate self-healing performance

Inactive Publication Date: 2017-05-03
SHANGHAI DEXIU CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Molybdenum is in the same family as chromium, and molybdate has low toxicity, so it has certain advantages in replacing chromate treatment. However, in the passivation film of chromate, due to the strong oxidation and mobility of hexavalent chromium, It can be self-repaired after the film is broken. It is very hoped that the molybdate passivation film will also have such properties, but because the oxidation of hexavalent molybdate is not as strong as that of hexavalent chromate, molybdate passivation is not suitable. Self-healing properties of chromate

Method used

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  • A kind of chromium-free passivation solution for galvanized layer and using method thereof

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Embodiment approach

[0045] As a preferred embodiment of the present invention, the chromium-free passivation solution also includes trimethylolpropane trimethacrylate TMPTMA used as a cross-linking agent, the amount of the cross-linking agent being the water-based alkyd 12~25% of the total mass of the resin.

[0046] As a preferred embodiment of the present invention, the water-based alkyd resin is a hyperbranched alkyd resin, which is based on trimethylolpropane, dimethylol propionic acid, linolenic acid, phthalic anhydride, maleic acid Diene acid anhydride is synthesized as a raw material, and the degree of branching of the hyperbranched alkyd resin is 0.5~0.6, and the number average molecular weight M n =4.68×10 3 g / mol, mass average molecular mass M w =5.4×10 3 g / mol, polydispersity index M w / M n =1.15.

[0047] As another preferred embodiment of the present invention, the water-based alkyd resin is a hyperbranched alkyd resin, which is based on dipentaerythritol, dimethylol propionic ...

Embodiment 1

[0059] A chromium-free passivation solution for zinc plating and a method for using the same, wherein the chromium-free passivation solution includes the following raw materials in weight percent:

[0060] Waterborne Alkyd 25%

[0061] Sodium molybdate 1%

[0062] Zirconium carbonate 1%

[0063] The balance is water

[0064] Phosphoric acid to adjust pH to 1~3

[0065] The water-based alkyd resin is prepared through the following steps: in a 500ml four-necked flask equipped with a stirrer, a thermometer, and an oil-water separator, add 1.073mol of linoleic acid, 1.016mol of glycerol, and xylene (accounting for the total amount of the formula) at one time. 5~10% of mass), 1 mol of phthalic anhydride, and catalyst LiOH (0.02% of linoleic acid), CO 2 , stir, heat up to 160°C within 40~50min, then gradually raise the temperature to 220~230°C within 1~3h, keep the esterification until the acid value is below 10 mgKOH / g, and the viscosity (Gargerian tube) reaches 10s as the reac...

Embodiment 2

[0069] A kind of chromium-free passivation solution for galvanized layer, described chromium-free passivation solution comprises the raw material of following percentage by weight:

[0070] TMPTMA modified water-based alkyd resin 20%

[0071] Potassium molybdate 3%

[0072] Zirconium carbonate 2%

[0073] The balance is water

[0074] Phosphoric acid to adjust pH to 1~3

[0075] The TMPTMA modified water-based alkyd resin is prepared through the following steps: according to the same method as in Example 1, the water-based alkyd resin with an acid value of 55 ~ 65mgKOH / g is prepared, and 20% of the alkyd resin quality is added to it by titration The TMPTMA, control the titration time for 2h, and then react at 170°C for 2h. Infrared spectrum detection shows that the TMPTMA modified water-based alkyd resin has been synthesized.

[0076] The preparation method and usage method are the same as in Example 1.

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Abstract

The invention discloses a chromium-free passivating solution used for zinc coating, and an application method thereof. The chromium-free passivating solution used for zinc coating comprises following raw materials: waterborne alkyd resin, a molybdate, diammonium bis[carbonato-O]dihydroxyzirconate, and the balance water; pH value of the chromium-free passivating solution is adjusted to be 1 to 3 with phosphoric acid; and waterborne alkyd resin is prepared from a waterborne monomer, an unsaturated fatty acid, a polyhydric alcohol, and a polyatomic acid. The chromium-free passivating solution is capable of obtaining passivation coatings with excellent performance on metal surfaces; the performance of the passivation coatings is close to that of chromate passivation coatings, and corrosion resistance of the passivation coatings is even better than that of the chromate passivation coatings, so that chromate can be completely replaced by the chromium-free passivating solution, and environmental-friendly passivation coatings are obtained. The chromium-free passivating solution contains no chromate, so that environment pollution is reduced greatly, and requirements of WEES and ROHS restrictions are satisfied. And in addition, raw material cost is low; and a treatment method is simple and convenient.

Description

technical field [0001] The invention belongs to the technical field of passivation treatment of galvanized layers. More specifically, the invention relates to a chromium-free passivation solution for galvanized layers and a method for using the same, belonging to IPC classification number C23C. Background technique [0002] As we all know, the traditional aluminum alloy surface protection treatment process is mainly chromate passivation, the passivation process is simple, low cost, good corrosion resistance, and has self-healing properties. However, the chromate passivation solution contains hexavalent chromium, which is highly toxic and seriously pollutes the environment. It is easy to cause harm to human health during the production and recycling of plated parts. With the implementation of the EU RoHS environmental protection directive, all electronic and electrical equipment sold in the EU market must prohibit the use of heavy metals such as lead, mercury, cadmium, and he...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/42
CPCC23C22/42
Inventor 寿华军何查里
Owner SHANGHAI DEXIU CHEM CO LTD
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