Chromium(iii)-containing aqueous solution and process for production of same

A manufacturing method and aqueous solution technology, applied in the direction of chemical instruments and methods, chromium sulfate, chromium compounds, etc., can solve the problems of poor practicability, difficulty in obtaining a glossy surface, long time, etc., and achieve the effect of excellent gloss

Inactive Publication Date: 2011-08-03
NIPPON CHECMICAL IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The reason is that when m is less than 2, gelation tends to occur, and it cannot be used in the form of an aqueous solution.
However, if this method is used, there are the following problems: it is difficult to replace the hydroxyl group in the basic chromium nitrate or the water molecule coordinated on the chromium atom with the phosphate ion, and the free phosphoric acid remains in the solution, or it takes a long time for the replacement. , and even if the solution is used as a trivalent chromium source or a supplementary source of trivalent chromium in a metal surface treatment bath, it is difficult to obtain a surface with excellent gloss
[0007] Moreover, in Patent Document 4, as a problem of the conventional electroplating bath containing trivalent chromium, it is cited that the complex formation of the complexing agent and the chromium salt is not sufficient after the bath is built, so that a sufficient uniformity cannot be obtained. Throwing power; As a method for improving this problem, it is described that a trivalent chromium compound is mixed with a water-soluble aliphatic carboxylic acid or a salt thereof and fully matured under heating to obtain a stable Chromium complex solution method
However, even with this method, it is difficult to say that it is a method that can quickly obtain a stable trivalent chromium-containing electroplating bath, and there is a problem of poor practicality.

Method used

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  • Chromium(iii)-containing aqueous solution and process for production of same
  • Chromium(iii)-containing aqueous solution and process for production of same
  • Chromium(iii)-containing aqueous solution and process for production of same

Examples

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example

[0204] Hereinafter, the present invention will be described using examples, but the present invention is not limited to these examples. "%" means "wt%" unless otherwise specified.

[0205] In an example, charge distribution of an aqueous solution containing chromium (III) was performed by diluting the aqueous chromium (III) solution with water to a total chromium concentration of 100 ppm using IC-ICP / AES (ion exchange separation-ICP emission analysis).

[0206] An ion-exchange separation device (DX-500, manufactured by DIONEX Corporation, Japan) was set to the following conditions.

[0207] Ion exchange resin: ethylvinylbenzene-divinylbenzene polymer (5.5 μm in diameter)

[0208] Eluent: methanesulfonic acid aqueous solution (the concentration of methanesulfonic acid increases linearly from 2mmol / L to 40mmol / L over time in 30 minutes, and is maintained at 40mmol / L after 30 minutes)

[0209] ·Flow rate: 1.2ml / min

[0210] ・Introduction volume of measurement object liquid: 20...

example 1

[0217] {instance 1}

[0218] (step 1)

[0219] 325.3 g of water was put into a glass-made reaction container with a condenser, and 124.9 g of chromium trioxide was further added, and fully stirred to obtain a chromic acid aqueous solution. Next, 292.8 g of 75% phosphoric acid was added to prepare a mixed aqueous solution of chromic acid and phosphoric acid.

[0220] Ethylene glycol is used as a reducing agent. 96.1 g of 20% ethylene glycol aqueous solution obtained by adding 76.6 g of water to 19.5 g of 98.5% ethylene glycol was added to the mixed aqueous solution of chromic acid and phosphoric acid at a rate of about 0.8 mL / min using a metering pump. The addition time was about 2 hours and the temperature was 102°C. 19.5 g of 98.5% ethylene glycol is equivalent to reducing 83% chromic acid.

[0221] (step 2)

[0222] Next, 216.2g of oxalic acid aqueous solution (containing 35% (COOH) 2 ), was added to the solution obtained in the first step at a rate of about 1.6mL / min. ...

example 2

[0224] {instance 2}

[0225] (step 1)

[0226] 512.9 g of water was added to a glass-made reaction vessel with a condenser, and 81.9 g of chromium trioxide was further added, and stirred well to obtain a chromic acid aqueous solution. Next, 106.7 g of 75% phosphoric acid was added to prepare a mixed aqueous solution of chromic acid and phosphoric acid.

[0227] Ethylene glycol is used as a reducing agent. 48.6 g of 20% ethylene glycol aqueous solution obtained by adding 38.7 g of water to 9.9 g of 98.5% ethylene glycol was added to the mixed aqueous solution of chromic acid and phosphoric acid at a rate of about 0.8 mL / min using a metering pump. The addition time was about 1 hour and the temperature was 100°C. 9.9 g of 98.5% ethylene glycol is equivalent to reducing 64% chromic acid.

[0228] (step 2)

[0229] Secondly, 302.4g oxalic acid aqueous solution (containing 35% (COOH) 2 ), was added to the solution obtained in the first step at a rate of about 2.3mL / min. The a...

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Abstract

A chromium(III)-containing aqueous solution which permits various molar ratios of acid radicals to Cr and which is useful as a trivalent-chromium source or replenisher for surface treatment baths for various metals, characterized by containing a chromium(III) composite salt which is formed by conducting the reduction of chromic acid while making two or more acids present either simultaneously or successively, said acids being selected from among inorganic acids (excluding chromic acid) and organic acids; and a process for the production of a chromium(III)-containing aqueous solution which comprises bringing chromic acid into contact with an acid other than chromic acid and / or an organic reducing agent in an aqueous medium to conduct the reduction of chromic acid, characterized in that the reduction of chromic acid is conducted in a state wherein at least two acids are present as the acid other than chromic acid either simultaneously or successively, said acids being selected from among inorganic acids and organic acids.

Description

technical field [0001] The invention relates to an aqueous solution containing chromium (III) which can be used for metal surface treatment such as chromium plating or trivalent chromium chemical conversion (chemical conversion) treatment and a manufacturing method thereof. Background technique [0002] An aqueous solution of inorganic acid chromium (III) or organic acid chromium (III) (in addition, in the following description, unless otherwise specified, refers to trivalent chromium when referring to chromium) can be used as a chromium plating solution for various surface treatment of metals. Furthermore, it can also be used in trivalent chromium chemical conversion treatment such as galvanizing or tin plating. [0003] As a chromium (III) source for surface treatment, for example, chromium chloride, chromium nitrate, chromium phosphate, etc. have been actively used, and the use of organic acid chromium such as chromium acetate, chromium oxalate, etc. has also been propos...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/00C23C22/48C25D3/06C25D3/10
CPCC23C22/10C23C2222/10C25D3/06C25D3/10C23C22/53C23C22/08C01G37/00C01G37/08C23C22/48
Inventor 番田知宏桑野弘行
Owner NIPPON CHECMICAL IND CO LTD
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