JP4521659B2 - Method for producing magnesium or magnesium alloy material - Google Patents

Description

The present invention relates to a magnesium metal material having a highly decorative crystal pattern on the surface and a method for producing the same.

Magnesium alloys are used in a wide range of housings for various home appliances due to their characteristics such as light weight, good thermal conductivity, corrosion resistance, and excellent plastic workability. These alloys have the advantage that they can be molded into various shapes such as accessories, stationery, and various cases by bending, drawing, pressing, etc., but these alloy materials have a crystal pattern decoration with a metallic luster as well as corrosion resistance. It was difficult to apply at the same time.
A method of anodizing is widely known as a method for imparting corrosion resistance to a magnesium metal material. For example, Patent Document 1 discloses this method, but the surface of the material obtained here has little metallic luster, and none of the materials produced a crystal pattern with high decorativeness that can be confirmed with the naked eye.

JP 61-34200 A

An object of the present invention is to form a surface film having a metallic luster and a crystal pattern on a magnesium alloy material having a deficient surface decoration in the prior art.

In the present invention , a crystal precipitation process is performed after a crystal grain macro-treatment is performed on magnesium or a magnesium alloy that has been crystallized in advance, or on a magnesium or magnesium alloy that is not subjected to a macro-crystallization of crystal grains. subjected, then by anodizing treatment or coating treatment, a method for manufacturing a magnesium or magnesium alloy material having a plurality of polygonal crystal pattern having at least 2mm or more sides of length 2 or more on the surface.
The metal material of the present invention has a plurality of large crystal planes that are large enough to allow macroscopic confirmation of magnesium or its alloys on the surface, and when surface gloss is measured using a gloss meter, It emits reflected light from two or more directions from the surface, and when viewed from a certain position, it shows a number of different glossinesses. When the surface is moved, the reflected light of each crystal surface changes, so it has a glittering decoration. It can be put out.
Such a metal material can be produced by subjecting magnesium or a magnesium alloy to a crystal precipitation treatment, and then anodizing treatment or coating treatment alone or in combination. Magnesium and its alloy used as a starting material are preferably preliminarily crystallized into macro grains. For example, it is preferable to use a stretched material such as a rolled plate, a round bar, or an extruded material, or a cast material such as a sand mold, a die, or a die cast, or a forged material, in which crystal grains have been made macro. For example, there is a method of promoting the growth by heat treatment to make the crystal grains macro.
On the other hand, it is also possible to use a raw material that has not been crystallized with magnesium and its alloy as a starting material. As such materials, there are various products or products made by bending, drawing or pressing magnesium material. In this case, the shape of the product exceeds the recrystallization temperature of the material. It is preferable to carry out the crystallization precipitation treatment of the present invention after heat-treating for 10 minutes or more at a temperature not higher than the melting temperature in a range that does not significantly deform the crystal grains.
The heat treatment temperature at the time of the macro conversion is in the range of 300 to 630 ° C., and the holding time is 10 minutes or more, preferably 30 minutes to 72 hours. The product after the heat treatment is preferably cooled to room temperature at a cooling rate, for example, 0.3 to 300 ° C./min, which is controlled so that crystal grains having a desired size are grown until the temperature becomes below the recrystallization temperature. Alternatively, it may be cooled at the controlled speed up to about 300 ° C., which is the recrystallization temperature, and then allowed to stand naturally to cool to room temperature.
In the heat treatment for making the crystal grains macroscopic, in a heating furnace, in an atmosphere not containing oxygen at a pressure of 0.05 to 0.3 MPa or filled with a gas not containing oxygen, such as nitrogen or argon, or continuously at a flow rate of 5 It is preferable to flow at ˜1500 ml / min.
The products made by such a method, stationery as office relationship, projector, DVD, PC, scanner, printer, mouse, the wall of a building relationships, ceiling, wheat bran, handle, contact plate, desk, chair, lighting fixtures Interior parts such as gate doors, gate pillars, fences, shelves, digital cameras as mobile products, mobile phones, MD, CD equipment, video cameras, headphones, radios, etc. Components of general household appliances, minicomponents, refrigerators, coolers , Humidifiers, landline telephones, clock-related dials, appearance, hands, cosmetics-related compacts, lipstick containers, caps, and other general items such as tableware, dishes, balls, coasters, spoons, hawks, knives , Beer cups, kitchen utensils such as jars, jars, vases, jars, business card cases, pendants, Less, bracelets, belts, earrings, rings which is part or all of the body and accessories or products that are molded into the housing or the like, such as products of interest. In addition, these products do not necessarily have to be made of a magnesium-based material.
As a method of crystal precipitation treatment, magnesium is contained in a solution containing at least one alcohol, carboxylic acid, sulfonic acid, amine and / or a derivative thereof, or one or more of a fluorinated compound, a fluorosilicate compound, a silicate compound, and a phosphate compound . or magnesium alloy at a bath temperature 15 to 50 ° C., can be achieved by immersed time 3 seconds to 10 minutes, processes. Specific examples of the compounds used here include organic compounds such as CH ₃ OH, CH ₃ CH ₂ OH, CH ₃ CH ₂ CH ₂ OH, CH ₃ CH (OH) CH ₃ , CH ₃ CH ₂ CH ₂ as alcohols. _{CH 2 OH, (CH 2 OH} ) 2, CH 2 OHCHOHCH 2 OH, HOCH 2 CH 2 OCH 2 CH 2 OH, etc. CHC _{6 H} 5 OH, HCOOH as carboxylic _{acids, CH 3 COOH, CH 3 CH} 2 COOH, CH _{2 = CHCOOH, CH 3 CH =} CHCOOH, (CHCOOH) 2, (COOH) 2, CH 2 (COOH) 2, (CH 2 COOH) 2, HOOC (CH 2) 2 COOH, C 6 H 5 COOH, C 6 As sulfonic acids such as H ₄ (COOH) ₂ , amines such as C ₆ H ₅ SO ₃ H As CH ₃ CH ₂ NH ₂ , C ₂ H ₅ CH (NH ₂ ) CH ₂ CH ₂ CH ₃ , C ₆ H ₅ NH ₂ , NH ₂ CONH _2, etc., amides such as HCONH ₂ , CH ₃ CONH ₂ , C ₆ H ₅ CONH ₂ , (CONH ₂ ) ₂ , fluorine compounds such as HF, KF, MgF ₂ , NH ₂ F, etc., bifluoride as NH ₄ HF ₂ , silicic acid compounds as Na ₂ SiO ₃ , Na ₄ such as _{SiO 4, K 2 SiO 2,} Na 2 SiF 6, MgSiF 6 as silicofluoride, such as _(NH 4) 2 SiF _6, etc. phosphoric acid compound is used one or more than one. These compounds can also be mixed and used, and the concentration used is preferably 0.01 to 10 mol / L.
Polishing treatment before the crystallization treatment may be subjected to be performed in the present invention. As a polishing method, there are an electrolytic polishing method and a chemical polishing method, and the bath composition of the electrolytic polishing is phosphoric acid, nitric acid, caustic soda, caustic potash, one organic compound, etc., one or more organic compounds, etc. In a solution containing As the organic compound at this time, an organic compound containing an aromatic or aliphatic carboxyl group, alcohol group, nitro group, sulfone group or hydroxyl group is used. As conditions for the electropolishing, the compound concentration of the used solution is 1 to 6 mol / L, the bath temperature is 10 to 50 ° C., the time is 30 seconds to 10 minutes, and the current density is preferably 7 ± 5 A / dec square meter.
For chemical polishing, a method in which the bath composition is phosphoric acid-based, nitric acid-based, or an acid-side liquid containing the above-described organic compound, and a method in which a caustic soda-based or sodium phosphate-based alkaline-side liquid is used. There is. In chemical polishing, the concentration of the compound is 1 to 10 mol / L, the bath temperature is 10 to 50 ° C., and the time is 30 seconds to 5 minutes. By performing the polishing treatment, the metallic gloss of the surface can be greatly improved.
In the present invention, an etching process may be performed before the crystal precipitation process. Etching methods include one or more containing mineral acids such as sulfuric acid, nitric acid, phosphoric acid, fluorides such as acidic ammonium fluoride, or aromatic or aliphatic compounds having carboxyl or sulfone groups It can be carried out with an acidic solution.
As the conditions for the etching treatment, it is preferable to carry out by immersing in a solution having a contained compound concentration of 0.4 to 6 mol / L at 10 to 50 ° C. for 10 to 180 seconds.
The anodic oxidation treatment of the present invention comprises at least one alkali or alkaline earth metal hydroxide, carbonate, bicarbonate, silicate or silicofluoride and a film forming stabilizer in an amount of 0.5 to 10 mol / Using a solution containing a concentration of L, preferably the electrolysis conditions are bath temperature 50 to 80 ° C., current density 0.8 to 4 A / dec square meter, voltage 2 to 40, preferably 2 to 15 V, and spark discharge is generated. Do not let it. The film formed by this method is a porous non-spark discharge anodic oxide film having a thickness of 1 to 50 μm.
As the film formation stabilizer, inorganic compounds such as fluoride salts, bifluoride salts, silicofluoride salts, mineral acid salts, or cyclic or chain organic compounds containing alcohol groups, carboxyl groups, sulfone groups, etc. are used. .
The waveform of the power source used in the anodizing treatment can be any one or a combination of DC waves, pulsating waves, pulse waves, PR waves, inverted waves, or alternating current having a frequency of 20 Hz to 2 KHz. .
In the present invention, after the crystallization treatment, the coating treatment may be performed with or without the anodizing treatment and the chemical conversion treatment. The chemical conversion treatment film formed here is preferably a transparent to translucent film having a color tone that is almost as close to the base color as possible, and if possible, a chromium-free film is more preferable. Further, a coating treatment may be performed after the anodizing treatment. The coating agent used is preferably transparent to translucent so that the crystal pattern does not disappear, and is preferably coated from gloss to matte. Furthermore, as the coating agent composition, either inorganic or organic may be used.
Magnesium and magnesium alloys obtained in the present invention are bent, drawn or pressed into a mobile phone, Walkman (TM), other various electrical parts, a case for business card holders, etc. when they are plate-like. Molded and used as a lightweight product with high decorativeness and aesthetics.
When a material already processed into a product shape is used, it is also used as a highly decorative product having a metallic luster as it is after coloring and dyeing after anodizing treatment if necessary.

Magnesium and its alloy material obtained by the method of the present invention have a large and vivid metallic luster and crystal pattern on the surface, the degree of reflection of light changes depending on the viewing angle, and it is highly decorative aesthetic. Excellent materials or products can be obtained.

Next, the present invention will be specifically described with reference to examples. In the examples, “%” represents “% by weight” unless otherwise specified.

Magnesium plate (AZ31B) that has undergone macro-crystallization treatment is degreased and then etched (NH ₄ HF ₂ : concentration 100 g / L, liquid temperature 23 ° C., 30 seconds), followed by crystal precipitation treatment ((CH (OH) COOH) ₂ : 10 g / L + CH ₃ COOH; 5 ml / L, 25 ° C., 15 seconds), anodizing electrolyte (KOH: 80 g / L + (CH ₂ OH) ₂ CHOH: 10 g / L + Na ₂ SiO ₃ ; 6 g / L + (COONa) ₂ ; 5 g / L was anodized at a bath temperature of 60 ° C., a current density of 1.2 A / dec square meter, and a voltage of 3.5 V for 15 minutes.
When this workpiece (product) was measured using an Olympus GM268 gloss meter at an incident / reflection angle of 85 °, the maximum glossiness was 58%. On this sample surface, there are many large and complex polygonal or curved magnesium crystal planes with a side of 2 to 30 mm, and when the glossiness of the sample is measured, the glossiness of each crystal surface Ranges from 7 to 58%. For this reason, when exposed to natural light, a crystal pattern of matte to semi-gloss was seen, and the decoration was rich.
For the comparative example, a plate that had been subjected only to macroscopic treatment of crystal grains and not subjected to crystal precipitation treatment was degreased, etched, anodized and sealed under the same conditions as described above. On the surface of this comparative sample, a crystal pattern showing decorativeness was not seen with the naked eye.

Chemical polishing (HNO ₃ (67.5%): 4 V / V%, + H ₃ PO ₄ (85%): 0.51 V / V%, + H ₂ SO ₄ (98%) after the steps of Example 1, degreasing and etching ): 0.2 V / V%) was performed at a liquid temperature of 25 ° C. for 30 seconds, followed by crystal precipitation treatment and anodizing treatment in the same manner as in Example 1. When this workpiece is measured with a gloss meter as in Example 1. The maximum glossiness was 82%. The glossiness for each crystal surface ranges from 21 to 82%. When this work was exposed to natural light, a shiny and glittering crystal pattern was seen.

AZ31B tableware, which has not been crystallized in advance, is placed in an electric furnace (volume: 15 L). As a preparation, argon gas is flown at a pressure of 0.1 MPa and a flow rate of 1000 ml / min for 20 minutes, and then the pressure is the same. Then, the flow rate was set to 750 ml / min, heating was started, and the temperature was maintained at 580 ° C. for 24 hours. Thereafter, it was cooled to 250 ° C. at a cooling rate of 100 ° C./60 minutes, and then allowed to stand at room temperature. This product was degreased, etched, chemically polished, crystallized and anodized in the same manner as in Example 2, and then dyed as food dye (food yellow No. 4, Hodogaya Chemical Co., Ltd .; liquid concentration 3 g / L, 50 ° C., 15 minutes). When this dish was measured with a gloss meter in the same manner as in Example 1, the maximum glossiness was 79%. The glossiness for each crystal surface ranged from 14 to 79%. When this dish was exposed to natural light, a shiny, glittering yellow decorative crystal pattern was visible.

As in Example 2, two workpieces were pretreated as in Example 2, and degreasing, etching, chemical polishing, and crystal precipitation were performed, and then one sheet was subjected to a colorless and transparent gloss conversion treatment described in JP-A-9-228062. The system clear was coated with 10 μm and dried at 170 ° C. for 30 minutes. The other sheet was subjected to the same coating treatment without chemical conversion treatment. When these two workpieces were measured with a gloss meter as in Example 1, the maximum glossiness with chemical conversion treatment was 89%, the maximum glossiness without chemical conversion treatment was 93%, and the glossiness for each crystal surface was chemical conversion treatment. Yes, it was 35 to 89%, and without chemical conversion treatment, it ranged from 40 to 93%. When these two workpieces were exposed to natural light, a shiny, glaring and decorative crystal pattern was visible.

The magnesium material of the present invention is used in industries with applications where decoration is desired, such as lightweight casings.

The surface photograph of the material obtained in Example 1 of this invention is shown.

Claims (1)

Degreasing and then etching the magnesium plate that has undergone macro-crystallization, followed by crystal precipitation treatment [[CH (OH) COOH) ₂ + CH ₃ COOH] and then anodizing with an anodic oxidation electrolyte. The surface is complicated by large crystal planes of polygonal or curvilinear magnesium with a side of 2 to 30 mm or more on a surface. The manufacturing method of the magnesium plate which exists in large numbers.

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