KR101598572B1 - Composition for desmut treatment and method of desmut treatment of aluminum alloy using the same - Google Patents

Abstract

The present invention relates to a composition for desmut treatment of an aluminum alloy to be used in a desmut process, which is one of pretreatment processes executed to perform plating and painting of an aluminum alloy product, and a desmut treatment method using the same. The composition for desmut treatment of the present invention includes a phosphoric acid, a sulfate compound, an ammonium compound and a solvent. The composition for desmut treatment according to the present invention is eco-friendly and has an excellent smut removal ratio without using a nitric acid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a composition for dismutting aluminum alloy,

The present invention relates to a composition for treating a desmut for use in a desmut process, which is one of pretreatment processes carried out to perform plating and painting of an aluminum alloy product.

Aluminum alloys are suitable for almost all structural parts since they are suitable for weight reduction of parts. As a result, the demand for plating for products made of aluminum is increasing rapidly.

Aluminum alloys are generally composed of Al and other components (Si, Fe, Cu, Mn, Mg, Zn, Ni). Aluminum alloy products for casting, which are generally made of Al- It is easy to oxidize. Therefore, in order to improve the corrosion resistance and appearance of the surface of the material, surface treatment by plating, painting, anodizing, etc. is required.

Generally, when the surface of an aluminum material is chrome-plated by a plating method, due to the oxide on the surface of the material, a lot of plating defects such as adhesion failure after plating or poor adhesion after shipment are caused. Therefore, a series of pretreatment steps are required to remove the oxides of the surface before plating. Specifically, prior to performing the plating process, a pretreatment step such as degreasing, etching, desmutting, anodizing, and cleaning is performed on the surface of a product to be treated.

Such a pretreatment process is a process involving stability, durability, etc. of the final surface-treated product, which has a decisive influence on the quality of the product. In the pretreatment step, the etching step is a step of removing an oxide film formed on the surface of an aluminum product through an acid or alkali cleaning of an aluminum alloy material or the like. In the process of removing the oxide film, a reducing metal salt Mert is essential.

The surface of the aluminum alloy material which has been etched by immersing it in an etching solution composed of an acid or an aqueous alkali solution may be provided in a material containing Si and Fe, Cu, Mn, Mg, Zn and Ni, Is formed on the surface of the product, and the plating or the coating is not sufficiently adhered even after plating or coating on the surface of the product, which causes peeling, which is a factor that largely affects the cause of the defect in the surface treatment product This smudge must be removed.

Particularly, when the dismut process is not sufficiently carried out, there is a problem that the adhesion of the plating or the coating is insufficient even after the plating or coating is formed on the surface of the product, And it is an important process having a considerably large influence on the entire machining cost.

Such smudge is usually carried out by using a mixed liquid such as concentrated nitric acid and hydrofluoric acid as a dismutting liquid, which is rapidly dissolved in the desmutting liquid to be separated from the surface of the aluminum alloy material and precipitated in the surface treating composition do.

As the desmut treatment liquid which is conventionally used, nitric acid contained in the treatment liquid generates nitric acid gas (NOx) during the desmut process and adversely affects the human body and the environment, and its use is limited. In addition, it causes a lot of damage to the surface of the aluminum to be treated, which adversely affects the subsequent processes such as chromate and zincate treatment.

Accordingly, it is an object of the present invention to provide a non-nitric acid dismut treatment composition which does not contain nitric acid and is environmentally friendly, exhibits a superior smut removal rate as compared with the conventional dismutation treatment liquid containing nitric acid and minimizes damage to the surface of the aluminum alloy during the dismut treatment process Has been demanded.

Accordingly, it is an object of the present invention to provide a desmut treatment composition which is eco-friendly and excellent in a smut removal ratio without using nitric acid.

Further, it is intended to provide a dismut treatment composition capable of stably performing dismut treatment on a surface of a product when applied to an aluminum alloy, particularly an Al-Si-metal-based aluminum alloy product, thereby improving plating quality.

In one embodiment, the present invention provides a composition for treating a desmut containing phosphoric acid, a sulfate compound, an ammonium compound, and a solvent.

At this time, the composition may include 50 to 90% by weight of 85% phosphoric acid, 5 to 30% by weight of ammonium compound, and 1 to 20% by weight of sulfate compound.

The ammonium compound is selected from the group consisting of ammonium hydroxide (H ₅ NO), ammonium acetate (C ₂ H ₇ NO ₂ ), ammonium formate (NH ₄ CHO ₂ ), ammonium nitrate (NH ₄ NO ₃ ), ammonium hydrogen sulfate (NH ₄ HSO _4), ammonium sulphate _{((NH 4) 2 SO 4} ), ammonium sulfide (H ₈ N ₂ S), ammonium adipate _{(C 6 H 16 N 2 O} 4), ammonium fluoride (NH ₄ F ), ammonium chloride (NH ₄ Cl), tetraethyl ammonium acetate _{(C 8 H 20 NC 2 H} 3 O 2), ammonium hexafluorotitanate silicate _{((NH 4) 2 SiF 6} ), tetrapropyl ammonium bisulfate (C ₁₂ H ₂₈ NHSO _4), ammonium phosphinate _{(NH 4 H 2 PO 2)} , ammonium hydrogen maleate _{(C 4 H 7 NO 4)} , ammonium benzoate _{(C 7 H 9 NO 2)} , perchloric acid tetrabutylammonium (C One or two selected from the group consisting of ammonium bicarbonate ( ₁₆ H ₃₆ NClO ₄ ), ammonium bifluoride (NH ₄ HF ₂ ) and ammonium oxalate (C ₂ H ₈ N ₂ O ₄ ) Or more.

The sulfate compound may be selected from the group consisting of calcium sulfate (CaSO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), ammonium peroxodisulfate ((NH ₄ ) ₂ SO ₅ ), diethyl sulfate (C ₄ H ₁₀ O ₄ S) sulfonic acid (CH ₄ O ₃ S), dimethylsulfoxide (C ₂ H ₆ OS), ferric sulfate _{(Fe 2 (SO 4) 3} ), magnesium sulfate (MgSO _4), sulfuric acid, mercury (HgSO _4), copper sulfate (CuSO ₄ ), nickel sulfate (NiSO ₄ ), potassium sulfate (K ₂ SO ₄ ), sodium sulfate (Na ₂ SO ₄ ), sodium peroxide disodium sulfate (Na ₂ S ₂ O ₈ ) and sodium thiosulfate (Na ₂ S ₂ O ₃ ) ≪ / RTI > and mixtures thereof.

The desmutting composition preferably has a temperature of 5 to 30 캜.

In another embodiment of the present invention, an aluminum alloy and an aluminum die-cast alloy are prepared by dipping a surface of an alloy on which a reducing metal salt has been formed in the desmutting composition to remove a reducing metal salt formed on the surface of the alloy And the like.

At this time, it is preferable that the immersion is performed in the desmut treatment composition for 30 seconds to 10 minutes.

The composition for treating a dismutate of an aluminum alloy according to an embodiment of the present invention can obtain a smut removal efficiency superior to that of a conventional nitrate-type dismutated solution. Therefore, the aluminum alloy can be easily plated and painted, so that the productivity can be improved. That is, silicon and reductive metal salt impurities on the surface of the etched aluminum alloy (die cast) are effectively removed, so that adhesion and uniformity can be increased during final plating and coating and anodic oxidation.

In addition, it is possible to completely dissolve and remove residual oil after degreasing and etching in an aluminum alloy material, minimizing surface damage of an aluminum alloy, and improving surface uniformity in processes such as chromate, zincate and plating / It is possible to obtain the result of the processing of FIG.

Furthermore, since nitric acid is not contained, it is possible to perform a desmutting operation without generating nitric acid gas harmful to the human body when an aluminum alloy material or the like is etched, and nitrate acidic waste water is not generated, thereby solving the problem of waste water treatment.

1 is a photograph of an aluminum smartphone substrate treated with an etchant.
Fig. 2 is data showing the results of analysis of the components of the smut existing on the surface of the aluminum substrate after the acid etching shown in Fig. 1 by SEM-EDX.
3 is a photograph of the surface of the aluminum substrate subjected to the desmutting treatment with a mixed acid solution of nitric acid and hydrofluoric acid.
4 is a photograph of a surface of an aluminum substrate subjected to a desmutting treatment with the desmut treatment composition of the present invention.
5 is an SEM photograph of the surface of the aluminum substrate before the treatment with the etching solution.
6 is an SEM photograph of a surface of an aluminum substrate treated with an etching solution.
7 is a SEM photograph of the surface of the aluminum substrate subjected to the desmutting treatment with a mixed acid solution of nitric acid and hydrofluoric acid.
8 is an SEM photograph of the surface of the aluminum substrate subjected to the desmutting treatment with the dismut treatment composition of the present invention.

The present invention can remove the silicon component and the reducing metal salt which are generated when aluminum alloy or aluminum die casting (ALDC) material (hereinafter also referred to as "aluminum alloy material, etc.") is etched without generating nitric acid gas harmful to the human body and environment (Also referred to as " dismut treatment solution ").

When an aluminum alloy is immersed in a dismut treatment composition, an alloy component such as copper, silicon, and iron contained in the component remains on the aluminum surface, which is called a smut. Generally, the smudge is easily removed by hand, and the more aluminum alloy contains, the more smut is formed and the color becomes black.

As a dismutant treating liquid for removing such smut, the present invention provides a treating liquid containing phosphoric acid, a sulfate compound and an ammonium compound.

The phosphoric acid contained in the desmutting solution of the present invention is a major component that performs a role as a dismutating solution. The phosphoric acid is treated on the basis of a 85% strength phosphoric acid solution (indicated by phosphoric acid (85%)) And can occupy a content of 50 to 90% by weight based on the total weight of the liquid. When the content of phosphoric acid (85%) is less than 50% by weight, the function as a dismutting liquid of the present invention is not exhibited. When the content exceeds 90% by weight, the aluminum film is damaged by phosphoric acid, It is preferable that the above ranges are included.

The ammonium compound plays a role of removing smuts such as silicon and copper from the surface of an aluminum alloy material or the like together with phosphoric acid in the desmut treatment solution of the present invention.

It is preferable that the ammonium compound is contained in an amount of 5 to 30% by weight based on the total weight of the dismut treatment composition. If it is contained in an amount of less than 5% by weight, it may be impossible to sufficiently remove the smuts such as silicon and copper. If it exceeds 20% by weight, further effect can not be increased due to saturation of the dismutting effect. It is preferable to limit it to not more than% by weight.

This ammonium compound is not particularly restricted but includes, for example, ammonium hydroxide (H ₅ NO), ammonium acetate _{(C 2 H 7 NO 2)} , ammonium formate (NH ₄ CHO _2), ammonium nitrate (NH ₄ NO ₃ ), ammonium hydrogensulfate (NH ₄ HSO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), ammonium sulfide (H ₈ N ₂ S), ammonium adipate (C ₆ H ₁₆ N ₂ O ₄ ) , Ammonium fluoride (NH ₄ F), ammonium chloride (NH ₄ Cl), tetraethylammonium acetate (C ₈ H ₂₀ NC ₂ H ₃ O ₂ ), ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ) (C ₁₂ H ₂₈ NHSO ₄ ), ammonium phosphinate (NH ₄ H ₂ PO ₂ ), ammonium hydrogensulfate (C ₄ H ₇ NO ₄ ), ammonium benzoate (C ₇ H ₉ NO ₂ ), composed of perchlorate of tetrabutyl ammonium _{(C 16 H 36 NClO 4)} , ammonium bi-fluoride (NH ₄ HF ₂₎ and ammonium oxalate _{(C 2 H 8 N 2 O} 4) Selected from the group of one or may be a mixture of two or more.

It is judged that the effect of inducing the change of the smear solubility and the surface tension is further improved by including the ammonium compound in the desmut treatment solution of the present invention.

The sulfate compound is preferably contained in an amount of 1 to 20% by weight based on the total weight of the desmut treatment composition. If it is contained in an amount of less than 1% by weight, the effect obtained by the addition of the above-mentioned sulfate compound is not sufficiently obtained. If it exceeds 20% by weight, there is a problem in smect solubility and solution stability. .

This sulfate is not particularly restricted but includes, for example, calcium sulfate (CaSO _4), ammonium sulfate _{((NH 4) 2 SO 4} ), peroxide, ammonium persulfate _{((NH 4) 2 SO 5} ), sulfate, diethyl (C ₄ H ₂ O ₄ S), methane sulfonic acid (CH ₄ O ₃ S), dimethyl sulfoxide (C ₂ H ₆ OS), ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), magnesium sulfate (MgSO ₄ ) (HgSO _4), copper sulfate (CuSO _4), nickel sulfate (NiSO _4), potassium sulfate (K ₂ SO _4), sodium sulfate (Na ₂ SO _4), hydrogen peroxide double sodium sulfate (Na ₂ S ₂ O ₈₎ and sodium thiosulfate ( Na ₂ S ₂ O ₃ ), or a mixture of two or more thereof.

Further, it is considered that the sulfate compound has a role in further improving the effect of dissolving the smut attached to the surface of the aluminum alloy material or the like in the desmut treatment solution of the present invention and influencing the stabilization of the solution during the smut treatment.

As described above, the desmut treatment liquid containing phosphoric acid, ammonium compound and sulfate compound is preferably controlled in the temperature range of 5 to 30 占 폚. When the temperature of the treatment liquid is less than 5 캜, it is difficult to obtain a sufficient smut removing effect to be obtained by the dismutating treatment liquid of the present invention. On the other hand, at a temperature higher than 30 캜, excessive dismut have. The desmut treatment liquid is preferably, for example, 10 to 30 占 폚, more preferably 15 to 30 占 폚, and most preferably room temperature (20 to 25 占 폚).

On the other hand, the smut removal treatment from the surface of an aluminum alloy material or the like using the disuture treatment liquid of the present invention can be performed by immersing the disposal material in the disuture treatment liquid for 30 seconds to 10 minutes. It is difficult to obtain desired desmut effect in a time shorter than 30 seconds, and it is disadvantageous in that it takes less economical time to take longer than 10 minutes. More preferably from 30 minutes to 5 minutes, and even more preferably from 30 seconds to 3 minutes.

The surface of the aluminum alloy material or the like can be pretreated using the desmut treatment liquid as described above. The pretreatment step including the desmutting step using the desmutting solution of the present invention can be carried out, for example, in a step of degreasing-etching-desmut-anodizing . Hereinafter, this will be described in more detail.

Degreasing

Degreasing step to degrease the aluminum surface. The degreasing may be carried out in accordance with the type of solvent, such as solvent degreasing, emulsion cleaning using a solution in which a surfactant is emulsified in a solvent and water, ultrasonic degreasing, electrolytic degreasing, alkaline cleaning, etc. . The degreasing step is not particularly limited, and a degreasing solution usually used for degreasing may be used.

etching

The etching step is a step of removing scratches and other defects on the aluminum surface. Acid etching is generally used for a material containing a lot of silicon, and acid etching can be used in the etching step of the present invention. The etching solution includes, for example, sulfuric acid and the like and can be performed at room temperature. The etching temperature can generally be performed at room temperature near 20 [deg.] C. If the etching temperature at the time of etching is low or high, the reaction does not occur, or the aluminum film may be affected by excessive etching.

Dismute

The dismutating solution provided by the present invention can be used.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. However, it is to be understood that the present invention is not limited to the following embodiments, and that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. It is obvious that it can be changed.

Example  One

An aluminum substrate (6.4 cm x 13.1 cm x 0.03 cm) made of an aluminum alloy was prepared. SEM photographing was performed on the surface of the aluminum substrate, and the results are shown in Fig.

An etching process for removing the oxide film formed on the prepared aluminum substrate surface was performed.

In the etching step, the aluminum substrate was immersed in a DAC-107DZ etching solution (room temperature: 20 ° C) manufactured by Jeon Young Co., Ltd. for about one minute to remove the oxide film existing on the surface of the aluminum substrate.

The aluminum substrate after the etching treatment was photographed, and a photograph thereof is shown in Fig. Further, SEM photographing was performed on the surface of the etched aluminum substrate, and the results are shown in FIG.

Referring to FIG. 2, it can be seen that a large amount of black smut particles are formed on the surface of the aluminum substrate.

Meanwhile, the SEM-EDX component analysis was performed on the smoot particles present on the surface of the substrate, and the results are shown in FIG. From the analysis results of the components, it was found that the components of the smoot particles mainly contain Al and Si, which are aluminum alloy components, and Cu and Zn are present together. As a result, it was confirmed that smut particles of a reducing metal salt such as Al, Si, Cu, Zn exist on the surface of the etched aluminum substrate.

In order to remove the smut on the surface of the etched aluminum substrate, 80 wt% of phosphoric acid (85%), 5 wt% of sodium sulfate (Na ₂ SO ₄ ) as a sulfate compound, and ammoniumphosphinate (NH ₄ H _{2 < / RTI} > PO2), and the remaining solvent was deionized water.

The aluminum substrate etched in the prepared dismut treatment liquid (room temperature: 20 캜) was immersed for 60 seconds.

The surface of the desmutted aluminum substrate was photographed and SEM-photographed, and the photographs thereof are shown in Fig. 5 and Fig. 6, respectively.

Comparative Example  One

In order to confirm the smut removal effect of the dismutant treatment liquid according to the first embodiment, the conventional dismutation treatment using the nitric acid-type dismutation treatment liquid was performed as a comparative example.

The same aluminum substrate as in Example 1 was etched by the same method to etch the aluminum substrate.

In order to remove the smut on the surface of the etched aluminum substrate, using the product name SR-819Al (mixed acid etchant of nitric acid / hydrofluoric acid, room temperature: 20 ° C) And immersed for 60 seconds.

The surfaces of the dismutted aluminum substrates were then photographed and SEM-photographed, and the respective photographs are shown in Figs. 7 and 8. Fig.

7 and 8 showing the results of Comparative Example 1 treated with the conventional nitrate-type dismutating solution and Figs. 5 and 6 treated with the desmutting solution of Example 1 were compared with each other, It can be confirmed that the removal of the smut is significantly improved as compared with the comparative example 1.

Claims (7)

delete (CaSO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₂ ), ammonium sulfate (1 to 20 wt%) and ammonium sulfate (1 to 20 wt% ₄₎ sulfate, diethyl (C ₄ H ₁₀ O ₄ S), methanesulfonic acid (CH ₄ O ₃ S), dimethylsulfoxide (C ₂ H ₆ OS), ferric sulfate _{(Fe 2 (SO 4) 3} ), magnesium sulfate (MgSO _4), sulfuric acid, mercury (HgSO _4), copper sulfate (CuSO _4), nickel sulfate (NiSO _4), potassium sulfate (K ₂ SO _4), sodium sulfate (Na ₂ SO _4), and sodium thiosulfate (Na ₂ S ₂ O ₃ ).
The process of claim 2, wherein the ammonium compound is selected from the group consisting of ammonium hydroxide (H ₅ NO), ammonium acetate (C ₂ H ₇ NO ₂ ), ammonium formate (NH ₄ CHO ₂ ), ammonium nitrate (NH ₄ NO ₃ ) , ammonium hydrogen sulfate (NH ₄ HSO _4), ammonium sulphate _{((NH 4) 2 SO 4} ), ammonium sulfide (H ₈ N ₂ S), ammonium adipate _{(C 6 H 16 N 2 O} 4), ammonium fluoro (NH ₄ F 2), ammonium chloride (NH ₄ Cl), tetraethylammonium acetate (C ₈ H ₂₀ NC ₂ H ₃ O ₂ ), ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ) (C ₁₂ H ₂₈ NHSO ₄ ), ammonium phosphinate (NH ₄ H ₂ PO ₂ ), ammonium hydrogen maleate (C ₄ H ₇ NO ₄ ), ammonium benzoate (C ₇ H ₉ NO ₂ ), perchloric acid ( ₁ ) selected from the group consisting of tetrabutylammonium (C ₁₆ H ₃₆ NClO ₄ ), ammonium bifluoride (NH ₄ HF ₂ ) and ammonium oxalate (C ₂ H ₈ N ₂ O ₄ ) Or a mixture of two or more species.
delete The desmutting composition according to claim 2, wherein the desmutting composition has a temperature of 5 to 30 캜.
The alloy surface of the aluminum alloy and the aluminum die cast alloy in which the reducing metal salt is formed is immersed in the desmutting composition as described in any one of claims 2, 3 and 5 to form a reducing metal salt Is removed.
7. The method of claim 6, wherein the dipping is performed on the desmutting composition for 30 seconds to 10 minutes.

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