JPH0657461A - Smut removing liquid - Google Patents

Abstract

PURPOSE:To provide a smut removing liq. for rapidly removing the surface smut, i.e. insoluble residues, generated when the surface of aluminum, aluminum alloy and stainless steel is chemically polished with acid or alkali, degreased, etched or electrolyzed. CONSTITUTION:A vanadium compd. or >=2 kinds of vanadium compds. are incorporated into nitric acid, sulfuric acid, phosphoric acid or a liq. contg. >=2 kinds of the acids. Ferric sulfate, ferric chloride, ferric nitrate, etc., as the trivalent iron salt are further incorporated, as required. The aluminum or stainless steel with smut formed on its surface is dipped in the smut removing liq., or the liq. is sprayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to chemical polishing of the surface of aluminum or an aluminum alloy (both are collectively referred to as "aluminum") or stainless steel,
The present invention relates to a smut removing solution capable of promptly removing smut, that is, an insoluble residue generated on the surface of a metal when subjected to treatments such as electrolysis, degreasing with acid or alkali, and etching with acid or alkali.

[0002]

2. Description of the Related Art The following treatments are apt to form smut on the surface of aluminum or stainless steel.

When degreasing or etching is applied to aluminum for the purpose of cleaning the surface when anodizing or painting. When carrying out chemical polishing, electrolysis, acid or alkali treatment when performing brightening treatment or satinizing treatment on aluminum. When performing chemical etching, electrolytic etching, corrosion, or punching when processing aluminum. When performing chemical etching when pickling or processing stainless steel.

In carrying out the above-mentioned treatments (1) to (4), acids such as sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid and hydrochloric acid, or alkalis such as sodium hydroxide, sodium carbonate, trisodium phosphate and sodium aluminate are used. However, in this case, smut is apt to be generated on the metal surface.

In order to remove such smut, conventionally, a smut removing solution containing nitric acid, sulfuric acid, chromic acid, phosphoric acid alone or a mixed acid of two or more kinds thereof has been used.

[0006]

However, when nitric acid alone is used as the smut removing solution, the smut removing solution may have a viscosity of 30 to 30%.
It is difficult to completely remove the smut in a short time even with a high-concentration nitric acid of 40% or more, and there is also a problem that a high concentration causes a bad odor. Further, when smut is removed using chromic acid, hexavalent chromium is known to have an adverse effect on the human body and is regulated as a harmful substance.

Recently, the aluminum surface treatment line tends to be automated due to lack of manpower. However, when the conventional smut removing solution as described above is used, the removal time is long and the removal is incomplete. Problems such as odor and odor are major obstacles to line automation.

Therefore, the present invention has been made for the purpose of providing a new and improved smut removing liquid capable of reliably removing smut generated during surface treatment of aluminum or stainless steel in a short time. is there.

[0009]

That is, the present invention provides a smut for removing smut generated when aluminum, aluminum alloy or stainless steel is subjected to treatment such as chemical polishing, degreasing, etching and electrolysis with acid or alkali. A removal solution, characterized in that a solution containing nitric acid, sulfuric acid, or phosphoric acid alone or in combination of two or more kinds contains vanadium compound alone or in combination of two or more.

In a preferred embodiment of the smut removing solution of the present invention, a trivalent iron salt such as ferric sulfate, ferric chloride and ferric nitrate may be further contained.

As the acid to be used, inorganic acids such as nitric acid, sulfuric acid and phosphoric acid may be used singly or as a mixed acid of two or more kinds. Nitric acid is the most suitable acid, and the acid concentration is 0.
1% or more is desirable, and up to 98% nitric acid can be used, but it is economically and practically 1 to 30%. Further, a better smut removing effect can be expected by adding sulfuric acid or phosphoric acid to nitric acid.

Vanadium compounds typified by vanadium pentoxide and ammonium vanadate are pentavalent, tetravalent, trivalent,
It exists in a divalent state and dissolves in water or an acid.

For oxides and related compounds, VO, V
(OH) ₂ , V ₂ O ₃ , V (OH) ₃ , VO ₂ , M ₂ V
_{4 O 9 · 7H 2 O,} V 2 O 5, HVO 3, M 3 VO 4,
M ₄ V ₂ O ₇ , H ₂ V ₄ O ₁₁ , MVO ₃ , M ₄ (V
O ₂ ) H ₂ (V ₅ O ₁₆ ) and the like can be preferably used.

Further, as the halide, VCl ₂ , VF
_{3, M 2 VF 5, VCl} 3, VOCl 3 and the like, VSO ₄ · 7H ₂ O as sulfates and related acido complex compound,
VSO ₄ · M ₂ SO ₄ · 6H ₂ O, K ₄ [V (C
N) ₆ ] .3H ₂ O and the like can be used as the vanadium compound in the present invention. In the above formula, M represents a monovalent cation.

The amount of the vanadium compound used is preferably in the range of 0.01 wt% to 12 wt% as the V content with respect to the smut removing liquid. If it is less than 0.01% by weight, the improvement of the smut removal rate is not observed so much and it is not practical. On the other hand, if it exceeds 12% by weight, the solubility of the vanadium compound approaches the limit at room temperature, and the viscosity of the solution tends to increase even after dissolution, which is not desirable for use as a smut removing solution.

In the present invention, the effect of improving the smut removal rate can be further enhanced by further containing a trivalent iron salt such as ferric sulfate, ferric chloride or ferric nitrate in the smut removal solution. it can. The amount of such iron salt used is preferably in the range of 0.001% by weight to 12% by weight with respect to the smut removing liquid as the Fe content. If it is less than 0.001% by weight, the improvement effect of the smut removal rate is not improved and it is not practical. On the other hand, if it exceeds 12% by weight, it tends to be difficult to completely dissolve at room temperature, which is not desirable.

If necessary, a surfactant may be added to further enhance the smut removing effect. As the surfactant, one kind or two or more kinds of nonionic type, anionic type and cationic type can be added, and the addition amount is preferably 0.1% by weight or less.

The method for removing smut using the smut removing liquid of the present invention will be described in detail below. First, the surface of aluminum is etched by an ordinary method using acid or alkali. For example, when an alkali is used, it may be dipped in a 5-10% aqueous solution of caustic soda at 50-70 ° C. for 30 seconds-2 minutes. When an acid is used, it may be immersed in a mixed acid of phosphoric acid and sulfuric acid at 80 to 110 ° C. for 30 seconds to 2 minutes. Next, after washing with water, if smut is attached to the surface, the smut can be quickly removed by immersing in the smut removing liquid of the present invention or spraying the smut removing liquid. The operating temperature of the smut remover is in the range of room temperature to 100 ° C, preferably room temperature to 60 ° C.
Is the range.

On the other hand, in order to brighten and smooth aluminum, it is chemically polished with a phosphoric acid / sulfuric acid type or phosphoric acid / sulfuric acid / nitric acid type polishing agent, or a phosphoric acid / sulfuric acid type polishing agent is used. When electropolishing with smut, smut may be generated on the aluminum surface. Also in this case, the smut can be quickly removed by immersing in the smut removing liquid of the present invention or spraying the smut removing liquid.

Aluminum materials to which the smut removing liquid of the present invention can be effectively applied include pure aluminum and aluminum alloys. For example, JIS1000
Series, 2000 Series, 3000 Series, 5000 Series, 6
Examples include the 000s and 7000s. It is also suitable for alloys having a Si content of 1% or less in aluminum castings and aluminum die castings.

Furthermore, the surface of the stainless steel is
Smut generated during etching using a nitric acid-based etching agent can also be effectively removed by immersing in the smut removing liquid of the present invention or spraying the smut removing liquid.

When the smut removing solution of the present invention is continuously used, there is a tendency that the smut removing rate gradually decreases due to aging, but it is recovered by supplementing with a new removing solution, Continuous use is possible.

The smut removing solution of the present invention can also be prepared by adding a vanadium compound to a smut removing solution which is generally used in the past and is composed of only nitric acid.

[0024]

The present invention will be described in detail below with reference to examples and comparative examples, but the examples are described merely for the purpose of illustration, and the present invention is not limited to these examples.

The evaluation method of smut removal in Examples and Comparative Examples is as follows. That is, an aluminum plate or a stainless steel plate on which smut was generated was prepared, part of the smut was wiped off with a cloth and physically removed, and then immersed in a smut removal solution. The time during which the remaining smut was removed by the removing liquid and the surface state was the same as the surface of the aluminum plate or stainless steel plate from which the smut was physically removed was visually confirmed.

Example 1 A commercially available chemical polishing liquid (phosphoric acid / nitric acid system) was used to form a JIS 1050 aluminum plate having a size of 5 cm × 10 cm and a thickness of 0.5 mm.
After chemically polishing at 100 ° C. for 1 minute and washing with water, an aluminum plate on which smut was generated was prepared. This was immersed in the following smut removing solution. 67.5% nitric acid 100 g Ammon metavanadate 5 g Water 1000 g As a result, the smut could be removed at room temperature for 2 seconds.

Comparative Example 1 The smut-forming aluminum plate prepared in Example 1 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, the smut could not be completely removed even at room temperature for 2 minutes.

Example 2 A JIS 6063 aluminum material having a size of 7 cm × 15 cm was etched with 5% caustic soda at 60 ° C. for 1 minute and then washed with water to prepare an aluminum mold having smut. This was immersed in the following smut removing solution. 67.5% nitric acid 200 g 97% sulfuric acid 50 g vanadium pentoxide 5 g water 1000 g As a result, the smut could be removed at room temperature for 2 seconds.

Comparative Example 2 The smut-forming aluminum mold material prepared in Example 2 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, the smut could be removed at room temperature for 30 seconds.

Example 3 A JIS 1100 aluminum plate having a size of 5 cm × 10 cm and a thickness of 0.5 mm was chemically polished with a commercially available chemical polishing liquid (phosphoric acid / sulfuric acid / nitric acid system) at 100 ° C. for 1 minute and then washed with water. An aluminum plate on which smut was generated was prepared. This was immersed in the following smut removing solution. 67.5% nitric acid 200 g Sodium metavanadate 5 g Ferric sulfate 10 g Water 1000 g As a result, the smut could be completely removed at room temperature for 2 seconds.

Comparative Example 3 The smut-forming aluminum plate prepared in Example 3 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, the smut could not be completely removed even at room temperature for 2 minutes.

Example 4 A 5 cm × 10 cm, 0.5 mm thick plate of JIS 5052 aluminum material was placed on a commercially available chemical polishing liquid (phosphoric acid / sulfuric acid system).
After chemically polishing at 100 ° C. for 1 minute and washing with water, an aluminum plate on which smut was generated was prepared. This was immersed in the following smut removing solution. 67.5% nitric acid 100 g 98% sulfuric acid 20 g Potassium metavanadate 10 g Water 1000 g As a result, the smut could be removed at room temperature for 3 seconds.

Comparative Example 4 The smut-forming aluminum plate prepared in Example 4 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, smut could be removed at room temperature for 1 minute and 30 seconds.

Example 5 A plate of JIS 5052 aluminum material having a size of 5 cm × 10 cm and a thickness of 0.5 mm was etched with 5% caustic soda at 60 ° C. for 1 minute and then washed with water to prepare an aluminum plate having smut. This was immersed in the following smut removing solution. 67.5% nitric acid 100 g 85% phosphoric acid 10 g sodium metavanadate 5 g water 1000 g As a result, the smut could be removed at room temperature for 3 seconds.

Comparative Example 5 The smut-forming aluminum plate prepared in Example 5 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, the smut could be removed at room temperature for 40 seconds.

Example 6 A commercially available chemical polishing liquid (phosphoric acid / nitric acid system) was used to form a JIS 1050 aluminum plate having a size of 5 cm × 10 cm and a thickness of 0.5 mm.
After chemically polishing at 100 ° C. for 1 minute and washing with water, an aluminum plate on which smut was generated was prepared. This was immersed in the following smut removing solution. Commercial smut remover (main component nitric acid) 1000 ml Ammon metavanadate 5 g As a result, smut could be removed at room temperature for 3 seconds.

Comparative Example 6 The smut-forming aluminum plate prepared in Example 6 was immersed in the following liquid. 1000 ml of commercial smut remover (main component nitric acid) As a result, smut could be removed at room temperature for 30 seconds.

Example 7 A 5 cm × 10 cm, 0.5 mm thick plate of JIS 1070 aluminum material was put into a commercially available chemical polishing liquid (phosphoric acid / nitric acid system).
After chemically polishing at 100 ° C. for 1 minute and washing with water, an aluminum plate on which smut was generated was prepared. This was immersed in the following smut removing solution. 67.5% nitric acid 100 g 98% sulfuric acid 10 g Ammon metavanadate 5 g Potassium metavanadate 5 g Water 1000 g As a result, the smut could be removed at room temperature for 2 seconds.

Comparative Example 7 The smut-forming aluminum plate prepared in Example 7 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, the smut could not be completely removed even at room temperature for 2 minutes.

Example 8 SUS304 stainless steel material 5 cm × 10 cm, thickness 0.
95mm of 5mm plate with 20% hydrochloric acid, 10% nitric acid aqueous solution
After immersing at ℃ for 1 minute, it was washed with water to prepare a smut-formed stainless steel plate. This was immersed in the following smut removing solution. 67.5% nitric acid 200 g 98% sulfuric acid 30 g vanadium pentoxide 10 g water 1000 g As a result, the smut could be removed at room temperature for 10 seconds.

Comparative Example 8 The smut-forming stainless steel plate prepared in Example 8 was immersed in the following liquid. 67.5% nitric acid 500 g Water 500 g As a result, smut could not be removed even at room temperature for 1 minute.

[0042]

As can be seen from the above description, the smut removing solution of the present invention is effective in reducing the smut generated when chemically polishing, degreasing, etching, electrolyzing, etc. aluminum or stainless steel with an acid or an alkali. Can be removed selectively.

In particular, the conventional smut removing solution containing only nitric acid had many problems such as bad odor due to high nitric acid concentration, insufficient removal of smut, slow removal rate, and rapid aging. All of these problems can be solved by using the smut removing solution. Moreover, even if it is continuously used for a long time, the effect can be recovered only by replenishing a new solution. Therefore, it is possible to provide a smut removing solution that can cope with automation of the aluminum surface treatment line and the like.

Claims (2)

[Claims] 1. A smut removing solution for removing smut generated when aluminum, aluminum alloy or stainless steel is subjected to treatment such as chemical polishing, degreasing, etching and electrolysis with acid or alkali, which is nitric acid or sulfuric acid. Alternatively, a smut removing solution comprising a vanadium compound alone or two or more kinds in a solution containing phosphoric acid alone or two or more kinds. 2. The smut-removing solution according to claim 1, further comprising a trivalent iron salt.