JPH1036984A - Matted aluminum material and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a matte aluminum material having a reflectance of 30% or less when an incident angle is 60 degrees. [Constitution] This matte aluminum material has a particle size of 5μ.
m or less, the second phase particles having a volume ratio of 1.4 to 5%, and having a diameter of 0.1 to 1 by alkali etching.
It has a surface on which dimples are formed in the range of 00 μm, the aspect ratio r / d of the average depth d (μm) to the average radius r (μm) of the dimples is 0.6 or more, and the residual area ratio α of the flat portion is 0 to 30%, and the reflectance at an incident angle of 60 degrees is 30% or less. [Effect] An excellent desired matte surface can be obtained even with a small loss in etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matte aluminum material used for building material panels, cosmetic containers, decorative articles, daily necessities and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Aluminum materials are roughened by barrel polishing, liquid honing, electrolytic polishing, belt sander, etc., and are used as matting materials in applications where metallic luster is not desired. The roughened aluminum surface is a factor that imparts excellent adhesion to paints and films. Above all, etching using an alkali etching solution is a matting method that is frequently used because it is advantageous in terms of production cost and can be extended on a degreasing treatment. In addition,
The so-called matting material usually has a reflectance of 30% or less at an incident angle of 60 degrees.

[0003]

However, in the conventional alkaline etching, it is considered that a large amount of etching is required to stably obtain a matte surface.
Therefore, the life of the etching bath is short, and a large amount of waste liquid treatment is required. Further, it was necessary to adjust the etching conditions according to the history of the material to be processed. The present invention has been devised to solve such a problem. By quantitatively controlling dimples formed on the aluminum surface by etching, the amount of alkali etching can be reduced sufficiently. The aim is to obtain a matte aluminum surface.

[0004]

In order to achieve the object, the matte aluminum material of the present invention comprises second phase particles having a particle size of 5 μm or less and a volume ratio of 1.4 to 5%. 0.1 to 100 in diameter by alkali etching
It has a surface with dimples in the range of μm,
Average radius r for average dimple depth d (μm)
(Μm), the aspect ratio d / r is 0.6 or more, the residual area ratio α of the flat portion is 0 to 30%, and the reflectance R at an incident angle of 60 degrees is 30% or less. (See FIG. 2). The aluminum material to be etched may be, for example, A1070, A1080, A1100, A1200 according to JIS H4000 standard.
Pure aluminum, A5051, A5154, A5N01
Al-Mg based alloys such as A6063, etc.
There are i-based alloys, Al-Mn-based alloys such as A3003 and A3005, and Al-Si-based alloys such as A4043. Among these alloys, after casting and rolling an aluminum melt in which the total content of Si and Fe is adjusted to a range of 0.8 to 1.0% by weight as a general alloy element, 560 to 640
An aluminum material that has been subjected to a heat treatment at 20C for 20 to 80 hours is preferable. In this case, it is preferable that the allowable amount of the inevitable impurities is 0.2% by weight or less for Cu and Zn, and 0.1% by weight or less for each of the other elements. Or,
A bonding material having these aluminum materials as a surface layer is similarly applied.

[0005]

The present inventors have studied the relationship between the amount of alkali etching and the reflectance using various materials. As a result, it has been found that, with the specified aluminum material, the matte state of the material to be processed does not change even when the alkali etching is performed at a certain etching amount or more. The reason why the matte state, in other words, the reflectance does not change, is presumed to be the surface state of the etched aluminum material. That is, light incident on the surface of the aluminum material on which the dimples are formed is reflected by the remaining flat portion and the bottom surface of the dimple. Since the ratio of the amount of light reflected at a certain angle to the amount of incident light from the surface of the aluminum material is the reflectance, in order to reduce the amount of reflected light, correlated reflections at the remaining flat portion and the bottom of the dimple must be made. It becomes a problem.

Under such a premise, a surface analysis was performed for each material composition of the alkali-etched aluminum material, and a relationship between the surface state and the reflectance was investigated. When an aluminum material having a particle size of the second phase particles of 5 μm or less and a volume ratio of 1.4 to 5% is used as a processing material, a matte surface can be stably obtained by alkali etching. Turned out to be. Furthermore, the diameter of the dimple formed by the alkali etching is 0.1 to
In the range of 100 μm, and the average dimple depth d (μ
m) aspect ratio of average radius r (μm) to d / r
Is 0.6 or more, and when the residual area ratio α of the flat portion is 0 to 30%, a matte surface having a reflectance of 30% or less at an incident angle of 60 degrees is obtained.

[0007] In particular, the aspect ratio is a factor that greatly affects the reflectivity, and this promotes irregular reflection on the etched surface. Desired reflectivity R
Of the aspect ratio and the residual area ratio α of the flat part corresponding to
Is reduced to 30% or less.
Even with a relatively small etching amount of about
% Or less matte surface is stably obtained. Therefore, the target matte aluminum material can be obtained by selecting the dimples and the flat area remaining area ratio of the shapes that are easily manufactured from the quality of the material to be processed, so that the processing time can be reduced and the production time can be reduced. Management becomes easier. Further, for example, even if a defective product is formed by post-processing and is re-etched at a level within the above-mentioned range, the matte state is not changed, and the yield is improved. In this regard, in the conventional matting by etching, since the degree of matting is not quantitatively grasped, the aluminum surface is obtained and etched with an excessive etching amount. It was a poor thing.

A usable alkaline etching aqueous solution is
Although the type is not particularly restricted, NaOH,
There are Na ₃ PO ₄ , KOH and the like, and auxiliaries such as sodium gluconate and sodium nitrate are added as needed.
For example, when using a NaOH-based etchant,
The concentration is 1 to 100 g / l (preferably 3 to 10 g / l)
Immersion at a bath temperature of room temperature to 90 ° C. (preferably 40 to 60 ° C.) for 20 minutes or less (preferably 2 to 15 minutes). Further, in order to prevent the occurrence of scale, 0.5 to
5 g / l sodium gluconate, 5-50 g / l sodium nitrate or 1-10 g to increase the etching rate
g / l of sodium fluoride or the like is added as needed.
The dimples formed by etching have a diameter of 0.1 to 100 μm even when various sizes are mixed.
m, preferably in the range of 1 to 50 μm on average. Dimples less than 0.1 μm in diameter
The effect on matting is small and ignored. However, 1
Dimples having a large diameter exceeding 00 μm are visually recognized and treated as having surface defects.

The depth d of the dimple is preferably in the range of 1 to 30 μm. Dimples having a depth of more than 30 μm are treated as having surface defects. On the other hand, 1 μm
Shallow dimples that do not have a small effect on matting. Further, when the aspect ratio d / r of the dimple is 0.
A relationship of 6 or more needs to be established, and the upper limit of the aspect ratio d / r is about 2. In a dimple having an aspect ratio d / r of less than 0.6, the reflectance is increased due to reflection at the bottom surface of the dimple, and the matting effect of the dimple is reduced. The remaining area ratio α of the flat part is
The larger the value, the higher the reflectivity. Therefore, in order to obtain a predetermined matte surface, the surface needs to be suppressed to 30% or less. The volume fraction, dimples, remaining flat portions, and the like of the second phase particles are observed by an optical microscope, a SEM, a laser microscope, and the like, and image processing of the observation results provides dimple depth d, radius r, and remaining flat portion area. Is determined. In particular, as a means for obtaining information in three-dimensional directions, a laser microscope is preferable.

During etching, dimples are formed starting from the second phase particles. In this regard, the dispersed state of the second phase particles has an important effect on the distribution and size of dimples formed by etching. According to the study of the present inventors, it has been found that when the second phase particles having a particle size of 5 μm or less are dispersed at a volume ratio of 1.4 to 5% or less, a good matte surface can be stably obtained. . As the second phase particles, Al ₃ Fe, Al ₆ Fe, α-AlFeSi, β-
AlFeSi, α-AlFeMSi (M = Cu, Mn,
Cr), Al ₂ Cu, Mg ₂ Si, Al _n Mn, TiA
There are l, Si and the like, which may be noble or nobler than the matrix, and are preferably uniformly dispersed in the matrix. Such a structure state is not a problem because the entire matrix is manufactured as a uniform structure if it is a normal one. However, when the distribution of the second phase particles in the thickness direction is observed by the manufacturing method, the etching is performed. It is preferable that the substrate is held to a depth of at least about 50 to 100 μm from the front surface.

An aluminum material satisfying the above conditions is
It can be obtained by adjusting the components, rolling conditions, heat treatment conditions, and the like according to a conventional method. For example, the content of Si and Fe as commonly used alloy elements is 0.1 to 0.6% by weight and 0.2 to 0.9% by weight, respectively, and the total content is 0.8 to 1.0% by weight. % In the case of an aluminum alloy adjusted to the range of
By performing the heat treatment at 0 to 640 ° C. for 20 to 80 hours, the second phase particles can be generated in an appropriate range. When the heat treatment temperature is lower than 560 ° C., the second phase particles having a particle size of 5 μm or more crystallized during casting do not disappear. 640
At a heat treatment temperature higher than 0 ° C., the fine particles disappear in solid solution, and conversely, the relatively large and stable second phase particles grow to a particle size exceeding 5 μm. In addition, the second phase particles having a particle size of 5 μm or more formed during casting do not become a particle size of 5 μm or less during the heat treatment time that does not reach 20 hours, and the volume ratio of the second phase particles is 1. Below 4%. The upper limit of the inevitable impurities is determined as a range that can be used as pure aluminum.

When the particle size of the second phase particles exceeds 5 μm, the second phase particles or the vicinity of the second phase particles are preferentially etched, so that large shallow dimples are generated. for that reason,
It is difficult to obtain a uniform matte surface, the amount of light reflected from the bottom surface of the dimple increases, and the decrease in reflectance does not progress. Preferably, a particle size of about 0.5 to 3 μm is practical. If the volume fraction of the second phase particles is less than 1.4%, the residual area ratio α of the flat portion tends to increase, and the second phase effect on the improvement of the matte state by the dispersion of the second phase particles. The effect of particles is small. Conversely, if the volume ratio exceeds 5%, it is difficult to obtain a dimple shape having a uniform size and uniform dispersion effective for matting. Practically, it is preferable to be distributed at a volume ratio of 1.5 to 3%. The matte aluminum material is neutralized and desmutted after etching.
For the neutralization and desmutting treatment, an ordinary method using a 10 to 40% by weight nitric acid solution, a 100 to 200 g / l sulfuric acid solution or the like is employed. Thereafter, if necessary, a film according to the purpose is formed by anodizing treatment using an anodizing electrolytic bath such as sulfuric acid, oxalic acid, boric acid, or clear coating.
When the matte state, that is, the reflectivity is changed by the post-processing, it is necessary to select an etching condition in consideration of the change. It should be noted that, even if the base material of the composite plate in which the above-mentioned aluminum material is clad on the base material is subjected to the coating treatment, a matte material can be obtained on one side.

[0013]

【Example】

Example 1: An aluminum alloy having the composition shown in Table 1 was cast into an ingot of 160 mm x 150 mm x 30 mm, and a surface of 5 mm per side was applied to both sides to a thickness of 20 mm. The ingot after face milling was subjected to a homogenization treatment at 600 ° C. × 1 hour, and was cold-rolled to a thickness of 1 mm. The obtained cold rolled sheet
Annealing was performed at 40 ° C. for 80 hours to obtain an annealed material. The second of the annealed material
When the phase particles were measured, the average particle diameter was 0.5 μm and the volume ratio was 2%. The annealing material is immersed in a 5% by weight aqueous NaOH solution at a bath temperature of 50 ° C., and the dimple shape has an average radius of 1 μm and a depth of 0.6 μm.
And the aspect ratio d / r = 0.6, the residual area ratio α of the flat portion
Was etched to 1.5%. At this time, the etching loss was 5 μm. The processed material after the etching had a reflectance of 15%. Further, even if the etching was further continued, the reflectance remained almost at the same level as shown in FIG.

Comparative Example 1 The same aluminum material as in Example 1 was used and the heat treatment conditions were adjusted to adjust the average particle diameter of the second phase particles to 0.8 μm and the volume ratio to 0.7%. This heat-treated material was etched using the same etching solution as in Example 1 until the loss on etching became 5 μm. The reflectance of the obtained processing material is 50%, and the dimple shape at this time has an average radius r of 0.4 μm, a depth d of 1 μm, an aspect ratio d / r of 0.4, and a residual area ratio of the flat portion. α was 50%. To lower the reflectance,
As shown in FIG. 1, longer etching was required.

Comparative Example 2: Using the same aluminum material as in Comparative Example 1, etching was performed until the dimple shape became an aspect ratio d / r = 0.6 by changing the etching time. The reflectance of the obtained treatment material was 37%, and the dimple shape at this time had an average radius r of 1.7 μm, a depth d of 1 μm, and a residual area ratio α of the flat portion of 40%. Comparative Example 3: The same aluminum cold-rolled sheet as in Example 1 was used for 650
Annealed at 100 ° C. for 100 hours to obtain an annealed material. When the second phase particles of this annealed material were measured, the average particle diameter was 0.7 μm,
The volume ratio was 1.2%. When this annealed material was etched under the same conditions as in Example 1, the reflectance was 38%.
It was found that a matte material could not be obtained after long-time annealing.

Example 2 A cold-rolled sheet was obtained from an aluminum alloy having the composition shown in Table 2 under the same conditions as in Example 1;
Annealing was performed at 570 ° C. for 25 hours to obtain an annealed material. When the second phase particles of this annealed material were measured, the average particle size was 0.5 μm.
m and the volume ratio were 2.4%. When this annealed material was etched under the same conditions as in Example 1, the reflectance was 1
It was 2%, which proved that a matting material could be obtained if the conditions of the present invention were satisfied.

Comparative Example 4 The same aluminum cold-rolled sheet as in Example 2 was annealed at 550 ° C. for 15 hours to obtain an annealed material. When the second phase particles of this annealed material were measured, the average particle diameter was 0.4 μm and the volume ratio was 2%. When this annealed material was etched under the same conditions as in Example 1, the reflectance was 32%, and it was found that a matte material could not be obtained by the low-temperature short-time annealing treatment.

Comparative Example 5 An aluminum alloy having the composition shown in Table 3 was cold-rolled under the same conditions as in Example 1, and the obtained cold-rolled sheet was annealed at 640 ° C. for 80 hours to obtain an annealed material. When the second phase particles of this annealed material were measured, the average particle diameter was 0.5 μm and the volume ratio was 1.4%. When this annealed material was etched under the same conditions as in Example 1, the reflectance was 38%, and it was found that a matting material could not be obtained if the composition did not satisfy the conditions of the present invention.

[0019]

As described above, in the present invention, the depth and radius of the dimple formed on the surface of the material by the alkali etching of the aluminum material under the specified conditions are determined by the residual area of the flat portion. By defining the relationship with the ratio, a matting material having a low reflectance can be stably obtained in a relatively short time treatment. In addition, the relationship between the depth and radius of the dimple and the remaining area ratio of the flat part eliminates the need for excessive etching, reducing the required thickness of the material to be processed and increasing the throughput per unit usage of the etching solution. It is used for setting etching conditions necessary for obtaining a matting material with good productivity and reproducibility. Furthermore, as long as the above-mentioned dimple condition is satisfied, even if the etching process is repeated a plurality of times, a processing material having a desired matte state can be obtained. As a result, even if the product becomes defective due to post-processing, the film can be removed by post-processing by re-etching and can be used again for post-processing, thereby improving the yield in the entire process. I do.
In this way, the matte-treated aluminum material is
Used for applications such as building material panels, cosmetic containers, decorations, and daily necessities.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in reflectivity according to an etching loss of each test piece.

FIG. 2 is a schematic view of a dimple formed on a surface of an aluminum material by alkali etching.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shunichi Ushino 1-34-1, Kabara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Within Nippon Light Metal Co., Ltd. Group Technology Center (72) Inventor Yasuhisa Nishikawa 1, Kambara-cho, Kambara-cho, Anbara-gun, Shizuoka Prefecture 34-1, Nippon Light Metal Co., Ltd. Group Technology Center

Claims (3)

[Claims] 1. A particle size of 5 μm or less and a volume ratio of 1.4 to 5
% Of the second phase particles, and has a surface on which dimples having a diameter in the range of 0.1 to 100 μm have been formed by alkali etching, and has an average radius r with respect to the average depth d (μm) of the dimples. μm) is 0.6 or more, and the residual area ratio α of the flat portion is 0 to 30.
%, And the reflectance at an incident angle of 60 degrees is 30% or less. 2. A particle size of 5 μm or less and a volume ratio of 1.4 to 5
%, When the aluminum material containing the second phase particles is roughened by alkali etching, the dimples formed by etching have a diameter of 0.1 to 100 μm,
Average radius r for average dimple depth d (μm)
A method for producing a matte aluminum material, characterized in that etching conditions are determined so that an aspect ratio d / r of (μm) is 0.6 or more and a residual area ratio α of a flat portion is 0 to 30%. 3. After casting and rolling a molten aluminum in which the total content of Si and Fe as added elements is adjusted to be in the range of 0.8 to 1.0% by weight, the molten aluminum is cast at 560 to 640 ° C.
The method for producing a matte aluminum material according to claim 2, wherein an aluminum material subjected to heat treatment for up to 80 hours is used.