KR101291062B1 - Method of surface treatment for exterior decor of car - Google Patents

Abstract

PURPOSE: An alkali-resistant surface treating method for a vehicle exterior material is provided to improve an alkali-resistant property through a simple process forming an alkali-resistant layer in the cavity existing inside an oxidized layer and forming an oxide film. CONSTITUTION: An alkali-resistant surface treating method for a vehicle exterior includes the following steps: pre-processing a component of an aluminum alloy material in order to remove stains and foreign materials on the surface thereof; forming an oxide film forming a porous layer in which is alkali-resistant, superior, and compact; forming an alkali-resistant layer avoiding the surface discoloration caused by a strong alkali; and dry-processing in a drying furnace of a temperature of 800-100°C for 10-20 minutes after cleaning the component with ion-exchanged water. [Reference numerals] (S10) Pre-processing process; (S20) Oxide film forming process; (S30) Alkali-resistant layer forming process; (S40) Cleaning and drying process

Description

Alkali-resistant surface treatment method of exterior materials for vehicles {Method of surface treatment for exterior decor of car}

The present invention relates to an alkali-resistant surface treatment method of a vehicle exterior material, and more particularly, to improve the alkali resistance to a vehicle exterior material made of aluminum alloy to increase the texture of the exterior material and to improve the surface treatment method.

Recently, various materials have been developed and used to achieve fuel efficiency improvement through weight reduction, except for parts where high-strength steel plates such as doors, bonnets, and bumpers should be used. As a material for lightening the vehicle exterior materials, light alloy materials, high tensile materials, and the like are applied. In particular, the application of metals such as aluminum, magnesium, and titanium, which are lightweight and have high strength in alloys, is being expanded.

In addition, the use of exterior materials applied with aluminum alloy materials in the existing stainless steel and plastic plating has been expanded to enhance the texture with vehicle interior parts. Aluminum is a hard metal and lacks its corrosion resistance, so surface treatment technology is necessary. In addition, the surface treatment technology required to improve the mechanical properties of the material itself requires additional technology for improving the surface as an exterior material.

Related to the conventional surface treatment of aluminum, there is a method for surface treatment of aluminum or aluminum alloy products disclosed in Korean Patent Laid-Open Publication No. 10-2002-0007812, and the product, which is described in the body surface of aluminum or aluminum alloy Concave-convex portion to form an amorphous concave portion and the protrusion is alternately formed, the engaging groove is formed on the concave portion to form a wider inner interval than the inlet spacing of the concave portion, the surface of the body formed with the concave-convex portion of the configuration as described above Disclosed is a method for surface treatment of aluminum and aluminum alloy products, characterized in that the anodization layer and the Teflon coating layer are formed on the substrate.

In the case of the surface treatment method according to the patent, the surface of the main body is not smooth because the uneven part of the amorphous indentation and the protrusion formed on the surface of the body should be formed by a metal ball or by a physical method. Is not suitable, the process for forming the uneven portion is added to increase the manufacturing cost, it is difficult to obtain the effect of uniform surface treatment due to the amorphous uneven portion and there is a problem that can not increase the alkali resistance.

Another conventional technique is a surface treatment method of aluminum or an aluminum alloy disclosed in Japanese Patent Laid-Open No. 10-2008-0066581.

The patent discloses a surface treatment method of aluminum or aluminum alloy to form a nickel plated film, wherein the aluminum oxide film formed on the surface of the aluminum or aluminum alloy of the object to be removed is removed, and the water-soluble nickel salt is formed on the aluminum or aluminum alloy. And a first electroless nickel-plated coating film using a first electroless nickel-phosphorus plating bath containing hypophosphorous acid and / or its salt and organic carboxylic acid other than aminocarboxylic acid and / or its salt. A water-soluble nickel salt, hypophosphorous acid and / or its salt, aminocarboxylic acid and / or its salt are included on the surface of the 1st nickel plating process which forms the form, and the said 1st electroless nickel plating film, A second electroless nickel plating film was formed using a second electroless nickel-phosphorus plating bath containing no organic carboxylic acid other than aminocarboxylic acid and salts thereof. The castle there is the method for surface treatment of aluminum or aluminum alloy characterized in that it comprises a second step of nickel plating.

The surface treatment method disclosed in the patent has a problem in that the first and second nickel plating processes are separately configured, and thus, many apparatuses and time are required for surface treatment, thereby increasing the process cost and increasing alkali resistance.

In the prior art, when aluminum parts are used as vehicle exterior materials, the disadvantages of aluminum for alkali resistance are compensated for by electrodeposition coating after anodizing, but this method increases the cost of process cost and the process failure rate for post-treatment. There are many problems with the increase.

Meanwhile, in the case of an exported vehicle, chemical washing is performed using an alkali as shown in FIG. 1 to remove wax applied for exterior protection when the vehicle is shipped. Accordingly, as shown in FIG. There is a problem that the surface appearance of the exterior material using the material is damaged.

Therefore, the present invention provides a simple process consisting of a pretreatment process, an oxide film formation process for securing alkali resistance, an alkali resistance imparting process for imparting alkali resistance to the oxide film, a washing and drying process on the surface of an aluminum part used for automobile exteriors. The purpose of the present invention is to provide a surface treatment method that can improve the alkali resistance of the vehicle exterior material by supplementing the disadvantages of the aluminum material.

Alkali-resistant surface treatment method of the vehicle exterior material according to the present invention is a surface treatment method of the vehicle exterior material, the pre-treatment step (S 10) for pre-treatment to remove surface stains and foreign substances of aluminum alloy material parts, and excellent in alkali resistance An oxide film forming step (S 20) for forming an oxide film forming a dense pore layer, an alkali-resistant layer forming step (S 30) for forming an alkali-resistant layer that prevents surface discoloration against strong alkalis, and ion-exchanged water Washing and drying process for 10 to 20 minutes in a drying furnace at a temperature of 80 ~ 100 ℃ and characterized by consisting of a drying step (S 40).

Accordingly, the present invention provides an alkali-resistant surface treatment method of the vehicle exterior material having excellent alkali resistance by anodizing the surface of the vehicle exterior material made of aluminum alloy, but the pre-treatment process, the oxide film forming process, alkali resistance in the pores existing in the oxide layer There is an effect that can increase the alkali resistance of the vehicle exterior material through a simple process consisting of a layer forming process and washing and drying process.

1 is an implementation photograph of chemical car wash
Figure 2 is a photo of the appearance discoloration of the anodizing product after washing
FIG. 3 is a block diagram
Figure 4 is a photograph of the alkali resistance test results of the product produced by the present invention

The present invention relates to an alkali-resistant surface treatment method of a vehicle exterior material, and more particularly, to improve the alkali resistance to a vehicle exterior material made of aluminum alloy to increase the texture of the exterior material and to improve the surface treatment method.

The present invention provides a surface treatment method for a vehicle exterior material, comprising a pretreatment step (S 10) for pretreatment to remove surface stains and foreign substances from an aluminum alloy material part, and an oxide film for forming a dense pore layer excellent in alkali resistance. An oxide film forming step (S 20), an alkali layer forming step (S 30) for forming an alkali resistant layer to prevent surface discoloration against strong alkalis, and washing with ion-exchanged water and drying in a drying furnace at a temperature of 80 to 100 ° C. It is characterized by consisting of a washing and drying process (S 40) for 10 to 20 minutes drying treatment.

In addition, the pretreatment step (S 10) is a step of pretreatment in order to remove the surface stains or foreign matter of the aluminum alloy material parts pressed or extruded 100 g / L sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) and Treatment with alkaline degreasing solution consisting of sodium carbonate (Na ₂ CO ₃ ) 1-4 g / L at a temperature of 50-70 ° C. for 5 minutes, and a temperature of 40-40 in an alkaline solution containing 100 g / L of sodium hydroxide (NaOH). After treatment for 10 to 300 seconds at 60 ℃, and nitrate (HNO ₃ ) 68% stock solution mixed with water 1: 1 to remove the smut (smut) generated on the surface at room temperature for 1-5 minutes ( de-smut) process.

In addition, the oxide film forming step (S 20) is a process of forming an alkali-resistant oxide film having a dense pore layer, the electrolyte is sulfuric acid (specific gravity 1.8) 150 ~ 180g / L, citric acid 10 ~ 20g / L, hexafluorosilicate 10 It is characterized by consisting of ~ 15g / L, glycerin 1 ~ 2.5g / L, glyconic acid 1.5 ~ 2.75g / L.

In addition, the alkali-resistant layer forming step (S 30) is a step of forming an alkali-resistant layer for imparting better alkali resistance to the pores in the oxide film formed in the oxide film forming step (S 20), that is, the oxide pore layer, Primary sealing solution consisting of nickel sulfate 50-100 g / L, cobalt sulfate 5-10 g / L ammonium fluoride 30-60 g / L and surfactant 0.5-1 g / L The pH is 4 ~ 6, the temperature is 20 ~ 30 ℃ and the air is agitated, and the treatment time is 5 ~ 10 minutes.

In addition, the alkali-resistant layer forming step (S 30) is the first sealing process after the washing step (S 31) without a separate drying step after the second sealing process (S 32), the secondary sealing process ( The secondary sealing solution used in S 32) is a metal alkoxide solution and a silica compound with 1 to 1.5 moles of tetramethyl orthosilicate (TMOS) or tetraethyl orthosilicate (TEOS). 0.1 to 0.5 moles of sodium sodium silicate or silicate sol, mixed with 1.2 to 1.5 moles of water and 0.01 to 0.05 moles of alcohol with respect to 1 mole of the silicate compound, stirred for 1 to 2 hours, and then triethanolamine 0.01 to 0.05 It is characterized by adding mole and adding 0.01 to 0.05 g / L of surfactant.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a manufacturing process diagram of the alkali-resistant surface treatment method of the vehicle exterior material according to the present invention, the present invention is a surface treatment method of the vehicle exterior material, a pretreatment step of pre-treatment to remove the surface stains and foreign matter of aluminum alloy material parts ( S10), an oxide film forming step of forming an oxide film forming a fine pore layer excellent in alkali resistance (S20), and an alkali layer forming step for forming an alkali resistant layer that prevents surface discoloration to strong alkalis. (S 30) and the washing and drying step (S 40) of washing with ion-exchanged water and drying treatment for 10 to 20 minutes in a drying furnace at a temperature of 80 ~ 100 ℃.

First of all, aluminum alloys used as automotive exterior materials are commonly used alloys of aluminum and magnesium, and should have high gloss on the surface, be beautiful, and be clean in appearance, so that there is no change in external pollution and surface tone.

To this end, the pretreatment process (S 10) is a process of pretreatment to remove surface stains or foreign substances of the pressed or extruded aluminum alloy material parts, 100 g / L of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ) and Treatment with alkaline degreasing solution consisting of sodium carbonate (Na ₂ CO ₃ ) 1-4 g / L at a temperature of 50-70 ° C. for 5 minutes, and a temperature of 40-60 in an alkaline solution containing 100 g / L of sodium hydroxide (NaOH). After treatment for 10 ~ 300 seconds at ℃, and nitrate (HNO ₃ ) 68% stock solution mixed with water 1: 1 to remove the smut (smut) formed on the surface at room temperature for 1-5 minutes (de -smut) process.

Of course, in addition to the above-described pretreatment methods, organic solvents such as acetone and trichloroethylene, which are generally used, or commercial degreasing agents for aluminum products using commercial surfactants can be used. The alloy metal inclusions of can be removed.

Next, an oxide film forming process (S 20) is a process of forming an alkali-resistant oxide film having a dense pore layer, and a passivation film of aluminum oxide and pores having a size of several nm to several nm are formed together, and the electrolyte solution is sulfuric acid (specific gravity 1.8). ) 150 ~ 180g / L, citric acid 10 ~ 20g / L, hexafluorosilicic acid (H ₂ SiF ₆ ) 10 ~ 15g / L, glycophosphoric acid 1 ~ 2.5g / L, gluconic acid ) It consists of 1.5 ~ 2.75g / L.

Electrolytic conditions for forming an oxide film are accompanied by air agitation and maintained at a temperature of 18 to 25 ° C, in a constant current mode with a current density of 0.5 to 1.5 A / dm ^{2. The} cathode on the anode is an insoluble cathode. Lead, platinum, and carbon plates Anodic electrolytic treatment is carried out for 10 to 15 minutes. At this time, the thickness of the oxide film formed is formed to 2 ~ 10㎛, more preferably the thickness is formed to 3 ~ 5㎛.

In this case, a DC power source may be used, but more preferably, an AC sine wave power source 60Hz capable of uniformly forming fine pores.

The oxide film formed through the oxide film forming process (S 20) includes an alkali-based compound in the oxide film itself, thereby improving alkali resistance. When the thickness of the oxide film formed on the surface of the product is less than 2 μm, If the thickness of the oxide film is too thin, there is a high risk of oxidation of the product. On the contrary, if the thickness of the oxide film is exceeded, the process time required for forming the oxide film is increased, thereby increasing the cost, and the surface of the product is deteriorated due to the oxide film. There is a concern.

Next, the alkali-resistant layer forming process (S 30), that is, the third process forms an alkali-resistant layer for imparting better alkali resistance to the pores in the oxide film formed in the oxide film forming process (S 20), that is, the oxide pore layer. As a step, it is divided into a primary sealing process (S 31) and a secondary sealing process (S 32).

First, the first sealing process (S 31) is 50 to 100 g / L nickel sulfate, 5 to 10 g / L cobalt sulfate, 30 to 60 g / L ammonium fluoride, surfactant Primary sealing solution consisting of 0.5 ~ 1g / L, the pH is 4 ~ 6, the temperature is 20 ~ 30 ℃ air agitation and the treatment time is 5 ~ 10 minutes.

First, nickel sulfate is usually produced as a by-product of nickel smelting. When nickel, nickel oxide, and nickel carbonate are dissolved in sulfuric acid and evaporated at room temperature, they are precipitated as green needles (orthogonal crystals) of lacquer salt, and are white opaque even when weathered in air. It becomes a powder. These nickel sulfates include low cobalt (Co 0.02 to 0.03%) and ultra low cobalt (Co <0.0001%) nickel sulfates depending on the content of cobalt (Co). Nickel sulfate that can be used in the present invention is an electrochromic color of aluminum products. It is preferable to use nickel sulfate of low sodium (Na <0.002%) which is mainly used as a solvent.

The cobalt sulfate is a divalent and trivalent compound of cobalt, and can be obtained by heating CoSO ₄ (II) anhydride, red hygroscopic powder, and hydrate to 300 ° C. Such cobalt sulfate is sulfuric acid among the components of the primary sealing solution. About 10% of nickel is preferred.

The ammonium fluoride is a colorless deliquescent acicular crystal and decomposes into NH ₃ and HF at a high temperature. The ammonium fluoride is preferably about 60% of nickel sulfate in the components of the primary sealing solution.

The surfactant is a substance that reduces the surface tension by adsorbing to the interface in a dilute solution, so that oil and water are well mixed, the present invention by adding 0.5 ~ 1g / L in the primary sealing treatment solution The effect of sealing can be enhanced.

In this case, the surfactant used may be FC-4430 (3M Co., Ltd.).

The present invention is composed of the above-described nickel sulfate (50-100 g / L), cobalt sulfate (5 ~ 10 g / L), ammonium fluoride (ammouium fluoride) 30 ~ 60 g / L, surfactant 0.5 ~ 1 g / L After performing the first sealing treatment with the first sealing treatment liquid and washing with water without a separate drying step, the second sealing treatment step (S 32) is performed.

The secondary sealing solution used in the secondary sealing process (S 32) is a tetramethyl orthosilicate (TMOS) or tetraethyl orthosilicate (TEOS) as a metal alkoxide solution and a silica compound. ) 1 to 1.5 moles and 0.1 to 0.5 moles of sodium sodium silicate or silicate sol, mixed with 1.2 to 1.5 moles of water and 0.01 to 0.05 moles of alcohol with respect to 1 mole of silicate compound, and stirred for 1 to 2 hours, followed by triethanolamine (Triethanolamine) 0.01 to 0.05 mole is added and 0.01 to 0.05g / L surfactant is added to prepare a secondary sealing solution.

At this time, the solution temperature is suitably about 50 ~ 70 ℃ 60 ℃. The treatment time can be adjusted to 15 to 30 minutes depending on the thickness, but can be adjusted by adding an additional time of 3 minutes per 1 μm, depending on the thickness of the coating.

The vehicle exterior material that has undergone the third process is filled with silica (SiO ₂ ) -based compound having excellent alkali resistance together with the sealing material of aluminum hydroxide in the pores in the oxide film, thereby improving the alkali resistance of the vehicle exterior material.

After the secondary sealing process is completed, the product is washed with ion-exchanged water, and the washing and drying step (S 40) is performed for 10 to 20 minutes in a drying furnace at a temperature of 80 to 100 ° C.

Figure 4 is a photograph of the alkali test results of the product produced by the present invention, the test method is a drop of 0.1N NaOH solution to the surface-treated steel plate 1-2 drops and left for 10 minutes to determine whether the surface discoloration [ This test method is GM (General Motors) automotive standard GMW14665 No. This is the test standard according to Section 3.8 Alkaline Resistacne.

The surface treatment by the conventional anodizing method is a photo (a) shown on the left side of Figure 4, it is determined that the alkali resistance is weak, the surface treatment according to the present invention is a photo (b) shown on the right side of Figure 4 to alkali resistance The effect is considered to be remarkable.

In other words, the existing surface treatment product is severely discolored, whereas the surface treatment according to the present invention did not react to the NaOH solution to the extent that it is not known whether discoloration.

S 10; Pretreatment process
S 20; Anodization Process
S 30: alkali resistant layer forming process
S 31; Primary sealing process S 32; Second Sealing Process
S 40; Washing and drying process

Claims (5)

In the surface treatment method of the vehicle exterior material,
A pretreatment step (S 10) for pretreatment to remove surface stains and foreign substances of aluminum alloy material parts, an oxide film formation step (S 20) for forming an oxide film forming a dense pore layer excellent in alkali resistance, and strong alkali Alkali-layer forming process (S 30) to form an alkali-resistant layer to prevent surface discoloration to, and washing and drying step of washing with ion-exchanged water and drying for 10 to 20 minutes in a 80 ~ 100 ℃ drying furnace ( S 40),
The oxide film forming step (S 20) is a step of forming an alkali-resistant oxide film having a dense pore layer, the electrolyte is sulfuric acid (specific gravity 1.8) 150 ~ 180g / L, citric acid 10 ~ 20g / L, hexafluorosilicate 10 ~ 15g / L, glycerin 1 ~ 2.5g / L, glycolic acid 1.5 ~ 2.75g / L, characterized in that the alkali-resistant surface treatment method of the vehicle exterior material.
The method of claim 1,
The pretreatment step (S 10) is a step of pretreatment to remove surface stains or foreign substances of the pressed or extruded aluminum alloy material parts 100 g / L and sodium carbonate (sodium tripolyphosphate, Na ₅ P ₃ O ₁₀ ) sodium carbonate, Na ₂ CO ₃ ) 1 ~ 4 g / L alkaline degreasing solution treated for 5 minutes at a temperature of 50 ~ 70 ℃, sodium hydroxide (NaOH) 100 g / L containing alkaline solution at a temperature of 40 ~ 60 ℃ De-smut to remove the smut generated on the surface for 1 to 5 minutes by mixing 1 to 1 with a mixture of water and nitric acid (HNO ₃ ) 68% stock solution for 10 to 300 seconds. ) Alkali-resistant surface treatment method of a vehicle exterior material characterized in that the process.
delete The method of claim 1,
The alkali-resistant layer forming step (S 30) is a step of forming an alkali-resistant layer for imparting better alkali resistance to the pores in the oxide film formed in the oxide film forming step (S 20), that is, the oxide pore layer, nickel sulfate (nickel sulfate) 50 ~ 100g / L, cobalt sulfate 5 ~ 10g / L, ammonium fluoride 30 ~ 60g / L, surfactant 0.5 ~ 1g / L 4 to 6, the temperature is 20 to 30 ℃ air agitation and the treatment time is an alkali-resistant surface treatment method of the vehicle exterior material, characterized in that carried out in 5 to 10 minutes.
5. The method of claim 4,
The alkali-resistant layer forming step (S 30) is performed after the first sealing step (S 31) and washed with no additional drying step after the secondary sealing step (S 32),
The secondary sealing solution used in the secondary sealing process (S 32) is tetramethyl orthosilicate (TMOS) or tetraethyl orthosilicate (Tetraethyl Orthosilicate) as a metal alkoxide solution and a silica compound. TEOS) 1 to 1.5 moles and 0.1 to 0.5 moles of sodium sodium silicate or silicate sol, mixed with 1.2 to 1.5 moles of water and 0.01 to 0.05 moles of alcohol with respect to 1 mole of the silicate compound, followed by stirring for 1 to 2 hours. Alkali-resistant surface treatment method of the vehicle exterior material characterized by adding 0.01 ~ 0.05 mol of amine (triethanolamine) and 0.01 ~ 0.05g / L surfactant.

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