JPS596397A - Multi-color electrolytic coloration of aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To enable multi-color electrolytic coloration of various kinds of color tones in excellent productivity, by carrying out the reformation and the electrolytic coloration of an oxide film of Al or an Al alloy in an electrolytic coloring liquid after the anodic oxidation treatment thereof to carry out secondary and ternary electrolytic treatments in one liquid. CONSTITUTION:Parts made of Al or an Al alloy is subjected to anodic oxidation treatment in an acidic electrolytic liquid such as sulfuric acid or phosphoric acid or an alkaline electrolytic liquid such as NaOH or Na2CO3 to form an anodic oxidation film. In the next step, the treated one is treated in an electrolytic coloring liquid containing Sn, Ni, Co, Fe or Cu and based on phosphate or pyrophosphate by immersion or by applying DC or pulse voltage with positive polarization to reform the anodic oxidation film thereon or the form a new oxide film between said film and Al metal. Succeedingly, DC or pulse voltage is applied or AC voltage is applied to carry out electrolytic coloration. By this method, multicolors such as a golden color, a persimon color, red, purple, blue or green due to metal salts are developed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic coloring method for coloring aluminum and its alloy materials, and particularly to a multicolor electrolytic coloring method using a secondary electrolytic method (two-liquid three-stage electrolysis).

In general, multicolor electrolytic coloring methods are known from Japanese Patent Publication No. 54-13860 and Japanese Patent Publication No. 5'17239, both of which involve a tertiary electrolysis method (three-liquid three-stage electrolysis), in which sulfuric acid is used as the primary electrolysis. The anodic oxide film is chemically formed in the main electrolyte,
Secondary electrolysis involves anodic oxidation in an acidic bath mainly containing phosphoric acid to form an oxide film, and tertiary electrolysis involves electrolytic coloring in an electrolytic solution such as nickel sulfate/V.

As described above, the conventional method involves three-liquid, three-stage electrolysis, which involves many processing steps and poor productivity. In addition, there are many problems such as poor throwing power (uniformity of coloring) and coloring speed that is too fast, making it difficult to control color tone, so these methods are used industrially to manufacture products with uniform quality. It was difficult to do so.

In view of the above problems, the present invention allows aluminum or aluminum alloy materials to be colored in any color such as golden yellow, divine yellow, red, purple, blue, green, etc. Moreover, since the process can be carried out using a secondary electrolytic method, there are fewer processing steps. It has very high productivity, good color dispersion, and easy control of color tone, so it is easy to adopt industrially and is suitable for manufacturing products with uniform quality. The purpose is to provide a color electrolytic coloring method, and it is characterized by the use of an electrolytic solution that can simultaneously achieve the effects of secondary and tertiary electrolysis in the conventional tertiary electrolysis method with a single solution. .

The present invention will be explained in detail below.

(1) As the first step, use mineral acids such as sulfuric acid, phosphoric acid, and chromic acid, or organic acids such as oxalic acid and malonic acid, and a mixture thereof as an electrolyte for the oxide film, or use sodium hydroxide, An alkaline aqueous solution such as sodium carbonate is used as an electrolyte for forming an oxide film, and an oxide film is formed by anodizing in this electrolyte.

(2) As the second step, the oxide film produced in the first step is immersed in an electrolytic coloring solution mainly containing metal-containing phosphate or pyrophosphate, or by applying a direct current or pulses of positive polarity. After applying the voltage, a direct current or pulse voltage is applied, or an alternating current voltage is applied. Phosphoric acid or pyrophosphate and PH buffer, complex formation
Agents may also be added.

Phosphates or pyrophosphates containing metals are
Examples of metals include 5n, Ni, co, Fe, Cu, M
n, etc., and metals, metal oxides, metal hydrates, or mixtures thereof are precipitated into the micropores of the oxide film that is formed on the surface of the aluminum or aluminum alloy of one electrode during electrolysis. It is for coloring.

Phosphates or pyrophosphates are modified by modifying the oxide film formed in the first step when a positive polarity DC or pulse voltage is applied with these ions, phosphoric acid or pyrophosphate ions. These substances are useful for forming a new oxide film, such as nickel phosphate, stannous phosphate, copper pyrophosphate, and stannous pyrophosphate.
Examples include manganese. Here, phosphoric acid or pyrophosphoric acid may be added to further enhance this effect. Also, the same effect can be obtained by simply immersing it.

The pH buffering agent is preferably boric acid or an amine compound such as mono-, di-, or triethanolamine. Preferred complex forming agents include amine compounds and the like.

The voltage application method is to first apply a DC or pulse voltage of positive polarity to the electrolytic coloring liquid, and then apply a DC, PARNU voltage, or AC voltage. The positive voltage is preferably 5 to 30V, and the current density is preferably
001 A/62 m to 0.3 A/d2 m, and the current application time is preferably 30 seconds to 30 minutes. The subsequently applied DC or pulse voltage or AC voltage is preferably 1.0V to 30V, and the current density is preferably o,
I A y'd'rn ~ I A , / d2rr
By applying a voltage that is the same as or lower than the positive polarity voltage and current application time, the target color tone can be stably obtained and the throwing power is good.

Next, examples according to the present invention will be shown.

Example I Using an extruded shape of JIS A6063S-T5 material,
After normal pretreatment, sulfuric acid 15Qf/4.20℃
in an electrolyte with a voltage of 15 V and a current density of I A / 62
After applying electricity for 30 minutes at m to obtain an oxide film with a thickness of 9 μm,
Nickel phosphate (heptahydrate) 50f/l, phosphoric acid 10
p, /e, after applying a DC voltage of 20V with positive polarity in an electrolytic solution at 20°C (PH = 1.5), a negative DC voltage of 18V
Table 1 shows the positive voltage application time and the color tone of the colored film when applied for 1 minute.

Table 1: Color tone of the resulting colored film Example 2 Table 2 shows the color tone of the colored film obtained when the combination of voltages with positive and negative polarities was changed in Example 1. Note that the application time is 5 minutes for positive and 1 minute for negative.

Table 2 Color tone of the obtained colored film Example 3 Using JIS A1050P-0 material, after degreasing and etching with nitric acid and hydric soda, oxalic acid 40
f/l), voltage 40■ in electrolyte at 20°C, current density I
After applying electricity for 300 minutes at A/d2m to obtain an oxide film with a thickness of 977FF+, cupric pyrophosphate 10y/e,
Pyrophosphoric acid 10 f/l, triethanolamine 59.
/l, boric acid 20 f/l (PH=1>After applying a DC voltage of 15V with positive polarity for 10 minutes in an electrolytic solution of 20°C, Table 3 shows the color tone of the colored film depending on the application time of an AC voltage of 14V. Shown below.

Table 3 Color tone of the obtained colored film Example 4 Using an extruded shape of JIS A6063S-T5 material,
After normal pretreatment, sodium hydroxide 10f,
/'l, in an electrolyte of aluminum phosphate 2 y / e at a voltage of 2 m■, a current density of 2.5 A, / 4 at d2 m
After applying electricity for 00 minutes to obtain an oxide film with a thickness of 6I1m, phosphoric acid yJv 50f/(1, phosphoric acid 50y/(1
, sulfosalicylic acid 5y/11, was immersed in a bath at 20° C. for 5 minutes, and then a negative polarity DC voltage of 15 V was applied for 1 minute in the same bath, and the color of the film was blue.

Claims (1)

[Claims] In the first step, an anodic oxide film is formed on aluminum or aluminum alloy material in an electrolytic solution mainly containing sulfuric acid, and then in the second step, it is immersed or polarized in an electrolytic coloring solution such as nickel phosphate. After modifying the oxide film generated in the first step by applying a direct current or PALNU voltage with positive , or forming a new oxide film between the film and the aluminum metal, a direct current or pulse voltage is applied. Multicolor electrolysis of aluminum and aluminum alloys, which is characterized by applying electrolytic coloring treatment by applying or alternating current voltage to develop multiple colors such as golden yellow, divine yellow, red, purple, blue, and green. Coloring method.