JP2005042199A - Surface treated aluminum material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treated aluminum material having no angle dependance on surface brightness and color tone, having high uniformity and reproducibility, having soft touch feeling and composed texture and also having high abrasion resistance. <P>SOLUTION: In an aluminum material which is composed of aluminum or an aluminum alloy and has an anodically oxidized film and a coated layer on the surface previously subjected to roughening treatment by acid etching treatment and alkali etching treatment, the pencil scratch resistance of the surface is 6H-9H and a ratio of the L<SP>*</SP>value of a 0° reception angle to the L<SP>*</SP>value of a 45° reception angle measured at a -45° incident angle by a bending spectral system is not less than 0.2. A 60° specular gloss is preferably not less than 5 and surface roughness (Rz) is preferably 3-30 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface-treated aluminum material having an anodized film and a coating layer. More specifically, the present invention relates to a surface-treated aluminum material made of aluminum or an aluminum alloy having an anodized film and a coating layer on a surface that has been previously roughened.

JP-A-3-047937 JP-A-3-257177 JP-A-5-070906 JP-A-6-336682

  Aluminum materials are lightweight, excellent in corrosion resistance, durability, workability, surface treatment properties, etc., and because they have moderate strength, building materials such as exterior materials, interior materials, surface layer materials, electrical equipment, etc. It is widely used in many fields including the casing material.

  And for such an aluminum material, the surface gloss is adjusted by a method such as a satin treatment or a blast treatment for the purpose of improving the harmony with the surrounding environment or improving the design depending on the purpose of use, or In addition, a surface treatment for coloring by a method such as electrolytic coloring treatment or painting treatment is performed.

  Specific examples of this type of surface treatment include, for example, adjusting the additive amount of alloy components such as Fe, Mn, Zr, Si, Cr, Mg, Zn, and Cu, and adjusting the surface color tone to white by roughening treatment. After that, a method of obtaining an aluminum material having a white color tone by performing anodizing treatment (Patent Document 1), and a method of obtaining an aluminum material having a crystal pattern by applying heat treatment and etching treatment to coarsen crystal grains (Patent Document 2). ), A method in which plastic deformation is applied after complete softening annealing treatment, and then heat treatment is performed to coarsen the crystal grains to obtain an aluminum material having a crystal pattern (Patent Document 3). (Patent Document 4) has been proposed in which an Al—Mg—Si based alloy contained at a ratio of 1 is extruded and then etched to obtain an aluminum material having a crystal pattern.

  However, the aluminum material obtained by such a conventional surface treatment method has a narrow range of selection of surface gloss imparted to the surface, has an angle dependency in which the color tone varies depending on the observation angle, and has an appearance after treatment. Since it cannot be controlled, the surface gloss and color tone are poor in uniformity and reproducibility, and in addition, it has a wide variety of surface gloss and color tone, especially touched by hand, especially in the field of building materials. However, there was a problem that it was not possible to cope with the warm touch that was easy to see with the eyes and the texture that produced the atmosphere of a calm home. Further, even if an aluminum material that solves these problems is proposed, there is a problem that the surface is easily damaged.

  Accordingly, an object of the present invention is to provide a surface-treated aluminum material that has a high degree of uniformity and reproducibility in surface gloss and tone, has a warm feel and a calm texture, and has a high scratch resistance. It is to provide.

As a result of intensive studies to solve such problems, the present inventors have found that an aluminum material having an anodized film and a coating layer on a surface that has been roughened in advance by an acid etching process and an alkali etching process. Of these, aluminum materials whose ratio of the L ^* value at a light receiving angle of 0 ° to the L ^* value at a light receiving angle of 45 ° measured at an incident angle of −45 ° using a variable angle spectroscopic system is greater than a specific value. There is no angle dependency in color, richness in uniformity and reproducibility, warm touch and calm texture, good adhesion between anodized film and coating layer, and high scratch resistance As a result, the present invention has been completed.

That is, the present invention is an aluminum material made of aluminum or an aluminum alloy having an anodized film and a coating layer on a surface that has been roughened in advance by an acid etching process and an alkali etching process, and the surface pencil. Scratch resistance is 6-9H, and the ratio of L ^* value at 0 ° light reception angle to L ^* value at 45 ° light reception angle (diffuse reflection ratio) measured at an incident angle of −45 ° with a variable angle spectroscopic system. Is a surface-treated aluminum material characterized by being 0.2 or more. In order to have high scratch resistance, the surface pencil scratch resistance is required to be 6 to 9H, more preferably 7 to 9H, and particularly preferably 8 to 9H. Since the surface-treated aluminum material of the present invention has high scratch resistance, it is difficult to be scratched and is not noticeable. The surface-treated aluminum material of the present invention has a diffuse reflection ratio of 0.2 or more. The same color is seen from any direction, and gloss and color do not change depending on the viewing angle. The ratio of diffuse reflection is more preferably 0.25 or more.

Here, the L ^* value of the light receiving angle of 0 ° measured at the incident angle of −45 ° with the variable angle spectroscopic system is the brightness of the diffuse reflection, and the light reception measured at the incident angle of −45 ° with the variable angle spectroscopic system as well The L ^* value at an angle of 45 ° is the brightness of total reflection. The ratio of the L ^* value at a light receiving angle of 0 ° to the L ^* value at a light receiving angle of 45 ° (diffuse reflection ratio) measured at an incident angle of −45 ° with a variable angle spectroscopic system is the gloss and tone of the aluminum material surface. There is an optical quantification of the angle dependence. The closer the value is to 1, the matte appearance becomes, and there is no difference in color tone depending on the observation angle. In the surface-treated aluminum material of the present invention, the same color is seen from any direction, and the ratio of diffuse reflection measured in any direction is 0.2 or more and 0.25 or more. preferable.

  Since the surface-treated aluminum material of the present invention is roughened by acid etching treatment and alkali etching treatment, and the anodizing treatment and electrodeposition coating treatment are performed, the surface shape remains, so that the surface gloss is extremely high. As a result, a surface having a warm feel and a calm texture can be obtained. The surface-treated aluminum material of the present invention preferably has a 60 ° specular gloss of 5 or less, more preferably 1 to 5, and particularly preferably 2 to 4. Moreover, the surface of the surface-treated aluminum material of the present invention has a gentle uneven surface. The surface roughness (Rz) is preferably 3 to 30 μm, more preferably 5 to 30 μm, and particularly preferably 8 to 25 μm. Since it has a comparatively deep recessed part, even if it contacts with another member in a convex part, it does not affect the coating film of a recessed part. That is, any contact with another member is a point contact or a continuous point, and is difficult to see as a scratch. In addition, the touch is smooth, but the coldness of the metal is difficult to convey and there is a warmth. It can be a mat-like building material. In addition, dust is difficult to adhere.

  In the surface-treated aluminum material of the present invention, the coating layer is preferably a matte electrodeposition coating layer formed by matte electrodeposition coating.

  Further, the surface-treated aluminum material of the present invention is obtained by subjecting an aluminum material made of aluminum or an aluminum alloy to a roughening treatment by an acid etching treatment and an alkali etching treatment after carrying out a normal pretreatment for degreasing and etching in advance. It can be manufactured by forming a film by oxidation treatment and electrodeposition coating.

  Ordinary pretreatment of degreasing and etching can be performed by immersing in an aqueous sulfuric acid solution and then immersing in an aqueous sodium hydroxide solution to remove the natural oxide film on the surface of the extruded aluminum alloy.

  As the surface roughening treatment, a “two-step treatment” method is adopted, which is a surface roughening treatment by a chemical treatment method, in which an acid etching treatment and an alkali etching treatment are performed. Moreover, after forming an oxide film such as an anodic oxide film on the surface of the aluminum material, the above two-stage treatment may be performed.

This first-stage acid etching treatment is preferably performed by anodic electrolysis in an aqueous solution containing a monobasic acid. More preferably, anodic electrolysis is carried out in an acidic aqueous solution, followed by immersion treatment in the same aqueous solution to form a large number of fine pits. Examples of monobasic acids and salts thereof used here include monobasic acids such as hydrochloric acid, nitric acid, acetic acid and perchloric acid, and sodium salts, potassium salts and ammonium salts thereof, preferably hydrochloric acid, nitric acid, Sodium chloride (NaCl), potassium chloride (KCl), ammonium chloride (NH ₄ Cl), sodium nitrate (NaNO ₃ ), potassium nitrate (KNO ₃ ), ammonium nitrate (NH ₄ NO ₃ ) and the like. These monobasic acids and salts thereof may be used alone or as a mixed acid obtained by mixing two or more kinds and salts thereof.

The treatment conditions in this anodic electrolytic treatment vary depending on the type of monobasic acid to be used, but usually a treatment solution having a concentration of 1 to 500 g / l, preferably 10 to 200 g / l, and a solution temperature of 10 to 60 is used. At a current density of 10 to 300 A / m ² , preferably 50 to 250 A / m ² , for 2 to 300 seconds, preferably 3 to 180 seconds. Anodic electrolysis is performed.

  Then, following the acid etching treatment in the first step, an alkali etching treatment is performed so as to be immersed in the alkaline aqueous solution in the second step. Thereby, it is preferable to further enlarge the pit formed by the hydrochloric acid immersion treatment. In the second stage process, the pits generated in the first stage process can be enlarged. Regarding the processing conditions in this second stage alkali etching treatment, the free alkali concentration is preferably 20 to 100 g / l, more preferably 40 to 70 g / l, and the treatment temperature is preferably 30 to 70 ° C., more preferably. It is 40-60 degreeC, and pH value becomes like this. Preferably it is 13 or more, Furthermore, processing time becomes like this. Preferably it is 3-20 minutes, More preferably, it is 5-15 minutes. If the free alkali concentration is less than 20 g / l, the treatment temperature is less than 30 ° C., or the pH value is less than 13, in any case, the dissolution rate is slow and the productivity is lowered. On the other hand, when the free alkali concentration exceeds 100 g / l, or the processing temperature exceeds 70 ° C., the dissolution rate becomes too fast. The pits are enlarged too much, the surface becomes smooth, and it becomes difficult to obtain a desired surface state.

  Also, the treatment time varies depending on conditions such as free alkali concentration, treatment temperature, pH value, etc., but it is difficult to obtain desired irregularities without uniform dissolution in short-time immersion that does not reach 3 minutes, In the case of soaking for more than 20 minutes, uniform dissolution proceeds excessively, and the unevenness becomes inconspicuous, and the dissolution loss of aluminum becomes large.

  The surface-treated aluminum material of the present invention, which has been roughened by the above chemical treatment method, and then anodized and electrodeposition-coated, has a relatively uniform uneven surface, so the reflectance can be suppressed to a very low level. , Uniform frosted surface. As a result, the reflections are not uneven from any direction and appear to have the same color tone.

  As shown in FIG. 2, the surface-treated aluminum material of the present invention has an anodized film on an aluminum substrate, and further an electrodeposition coating film thereon. Since the enlarged bottom portion is formed by chemical etching, the bottom of the concave portion of the uneven surface has a non-uniform shape. That is, in the concavo-convex portion formed by the anodized film, many portions are observed where the size of the bottom of the recess is larger than the size of the opening. As a result, as shown in FIG. 2, the electrodeposition coating film after the anodizing treatment has good adhesion due to the anchor effect and is hardly peeled off. In particular, partial adhesion is obtained. As a result, even if the coating film is scraped off, the convex portions are only cut into dots, and the coating film in the concave portions does not peel off together. By performing chemical etching, it is possible to make the die mark (streaks during extrusion) difficult to see. In particular, the above-mentioned surface-treated aluminum material of the present invention that has been subjected to the chemical etching treatment of the “two-stage treatment” by the acid etching treatment and the alkali etching treatment uniformly etches the entire circumferential surface including a complicated shape. The rolling marks, extrusion marks and the like disappear, and the die mark can be made particularly difficult to see.

The anodizing treatment can be usually performed by a generally performed method. This anodizing treatment includes anodic oxide film formation and metal oxide deposition. For example, this anodic oxide film formation can be performed under conditions of a sulfuric acid bath and a direct current of 100 to 150 A / m ² . In order to deposit the metal oxide, it is sufficient to deposit a metal that can be colored in a desired manner by a generally performed method. Further, the metal oxide can be deposited by electrolytic coloring treatment. Next, a coating layer is formed on the anodized film by electrodeposition coating. As the electrodeposition coating, it is usually preferable to perform matte electrodeposition coating by a generally performed method. Electrodeposition coating can also serve as a sealing hole. For electrodeposition coating, a transparent paint or a colored paint containing a pigment may be used.

  In addition, it is preferable to neutralize by a normal method, respectively, after the normal pretreatment of degreasing and etching, before the roughening treatment, and after the roughening treatment and before the anodizing treatment.

  Further, before the electrodeposition coating, in particular, the matte electrodeposition coating, it is preferable to perform the above-described electrolytic coloring treatment by a known method. For example, it is possible to deposit a colored metal oxide in the anodized film by immersing it in an electrolytic coloring tank mainly composed of a metal salt capable of being colored. It is also possible to subject the aluminum material with the anodized film to a modification of the pores of the anodized film so that a color based on the interference of light can be obtained by the electrolytic coloring process, followed by an electrolytic coloring process. At this time, first, the aluminum material after the modification treatment was used as an anode, and a preliminary electrolytic treatment for adjusting the barrier layer was applied for a while, and then a positive pulse voltage was applied in an electrolytic bath containing a metal salt using this as a cathode. It is preferable to electrolytically color with an electric current.

  According to the surface-treated aluminum material of the present invention, the surface gloss and color tone do not depend on the angle and look the same color when viewed from any direction, the color does not change depending on the viewing angle, rich in uniformity and reproducibility, Since it has a warm tactile sensation and a calm texture, and has high scratch resistance, it is possible to provide a novel surface-treated aluminum material that is hardly scratched and is not noticeable.

  Hereinafter, preferred embodiments of the present invention will be specifically described based on examples.

A6063 aluminum alloy extruded profile was immersed in an aqueous sulfuric acid solution having a concentration of 100 g / l for 210 seconds as a pretreatment, and then immersed in an aqueous solution of sodium hydroxide having a concentration of 50 g / l for 3 minutes at a bath temperature of 50 ° C. The natural oxide film on the surface of the alloy extrusion was removed. Next, this pretreated aluminum alloy extruded shape was anodized for 2 minutes in a sulfuric acid aqueous solution having a concentration of 150 g / l under conditions of a bath temperature of 20 ° C. and a current density of 150 A / m ² .

Next, anodic electrolysis was performed for 1 minute at a bath temperature of 30 ° C. and a current density of 100 A / m ² in an aqueous hydrochloric acid solution having a concentration of 100 g / l, and further immersed in the same aqueous solution for 5 minutes to form a large number of fine pits. Furthermore, it is immersed in a 50 g / l sodium hydroxide aqueous solution under conditions of a bath temperature of 50 ° C. and a treatment time of 10 minutes to further enlarge the pit formed by the hydrochloric acid immersion treatment, and then immersed in a sulfuric acid aqueous solution for neutralization. And then anodized for 30 minutes in a 150 g / l sulfuric acid aqueous solution at a current density of 150 A / m ² to form an anodized film and immersed in an electrolytic coloring bath mainly composed of nickel sulfate. A colored metal oxide was deposited in the anodized film. Further, a matte electrodeposition coating was applied by a normal method, followed by baking at 180 ° C. for 20 minutes to obtain a surface-treated aluminum alloy extruded shape.

Ratio of pencil scratch resistance, scratch resistance and diffuse reflection of the surface-treated aluminum alloy extruded shape obtained (light reception with respect to L ^* value at a light receiving angle of 45 ° measured at an incident angle of −45 ° with a variable angle spectroscopic system) L ^* value ratio at 0 ° angle), 60 ° specular gloss, and surface roughness (Rz) were measured. The results are shown in Table 1 together with the results of Comparative Example 1. Pencil scratch resistance was measured according to JIS H8602, and the diffuse reflection ratio was measured with a variable angle spectrocolorimetry system GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd. with a fixed incident angle of −45 °.

(Comparative Example 1)
A6063 aluminum alloy extruded profile was immersed in a 100 g / l sulfuric acid aqueous solution for 210 seconds as a pretreatment without performing a roughening treatment, and then in a 50 g / l sodium hydroxide aqueous solution with a bath temperature of 50 It was immersed for 3 minutes at 0 ° C. to remove the natural oxide film on the surface of the aluminum alloy extruded profile. Next, an anodizing film is formed by using an electrolytic solution of 160 ° C./liter of sulfuric acid at 23 ° C. and under a current density of 150 A / m ² , and immersed in an electrolytic coloring tank mainly composed of nickel sulfate. Thus, a colored metal oxide was deposited in the anodic oxide film. Next, the same matte electrodeposition coating and baking treatment as in Example 1 were performed to obtain a surface-treated aluminum alloy extruded profile.

FIG. 1 shows the obtained surface-treated aluminum alloy extruded profile of Example 1 and the surface-treated aluminum alloy extruded profile of Comparative Example 1 using a variable angle spectrocolorimetric system manufactured by Murakami Color Research Laboratory Co., Ltd. The L ^* value at each light receiving angle when the incident angle is −45 ° is shown in the graph.

FIG. 1 is a graph showing L ^* values for each light receiving angle when the incident angle is −45 °. FIG. 2 schematically shows a cross section of the surface portion of the surface-treated aluminum material of the present invention.

Explanation of symbols

  1: Electrodeposition coating film, 2: Anodized film, 3: Aluminum substrate

Claims (4)

An aluminum material made of aluminum or an aluminum alloy having an anodized film and a coating layer on a surface roughened in advance by acid etching treatment and alkali etching treatment, and the surface has a pencil scratch resistance of 6H to 9H, and the ratio of the L ^* value at a light receiving angle of 0 ° to the L ^* value at a light receiving angle of 45 ° measured at an incident angle of −45 ° with a variable angle spectroscopic system is 0.2 or more. Surface-treated aluminum material.   The surface-treated aluminum material according to claim 1, wherein the 60 ° specular gloss is 5 or less and the surface roughness (Rz) is 3 to 30 µm.   The surface-treated aluminum material according to claim 1 or 2, wherein the coating layer is a matte electrodeposition coating layer formed by matte electrodeposition coating.   The surface-treated aluminum material according to any one of claims 1 to 3, wherein the anodized film is an anodized film subjected to electrolytic coloring.

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