JP2010076339A - Magnesium alloy member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnesium alloy member with high designability by developing a material excellent in designability. <P>SOLUTION: The magnesium alloy member has a primer layer 11 on at least one surface of a rolled magnesium alloy base material 10 and has a dye layer 12 on the primer layer. It is preferable to have a scattering layer between the primer layer and the dye layer. Further, it is preferable to additionally have a transparent layer on the dye layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnesium alloy member provided with a coating layer, and particularly relates to a magnesium alloy member having high design properties having a deep color feeling.

  BACKGROUND ART Magnesium alloys obtained by adding various elements to magnesium have been used as materials for casings of portable electric devices such as mobile phones and laptop computers and members of automobile parts. In recent years, the demand for this material is expanding, and there is a demand for improvement in durability and design by coloring and the like.

  However, magnesium alloys have a problem that they are easily oxidized in the atmosphere. For this reason, when used as an equipment casing, it is practically necessary to impart corrosion resistance by applying some treatment to the surface of the magnesium alloy material. In addition, when coloring the surface of a magnesium alloy housing in the design of the product, a treatment to provide a base that is compatible with the dye or paint is applied to improve the dyeing property or the coating property of the paint. There is also a need to improve.

For example, Japanese Patent Application Laid-Open No. 2002-371380 (Patent Document 1) describes a method in which a film containing magnesium oxide and magnesium aluminate is provided on the surface of a magnesium alloy substrate by anodization, and this film is colored with a dye. Has been.
JP 2002-371380 A

  Although the above-described technology can also provide a magnesium alloy member having a high design property to some extent, considering the needs from the market in the future, development of a material having a better design property is desired. Therefore, the present invention provides a magnesium alloy member having high design properties. Patent Document 1 discloses that a film is provided on a magnesium alloy base material and colored with a dye, but the characteristics of the magnesium alloy base material to be colored have not been studied. Then, this invention considers also the magnesium alloy base material colored, and it aims at improving design nature more.

  The present invention is a magnesium alloy member characterized by having an undercoat layer on at least one surface of a rolled magnesium alloy base material and a dye layer on the undercoat layer. Since the rolled magnesium alloy base material has few internal defects, surface defects, etc., it has high plastic workability, there are few generation | occurrence | production of the crack and crack during a process, and can implement | achieve the outstanding surface property. Therefore, a high surface quality after coating, that is, a clean painted surface can be obtained. The undercoat layer is disposed for the purpose of improving adhesion to the dye layer or the scattering layer described later.

  In the present invention, it is preferable that a scattering layer is further provided between the undercoat layer and the dye layer. The scattering layer is intended to diffusely reflect the light transmitted through the dye layer. A deeper color sensation can be obtained by irregularly reflecting the transmitted light.

  In the present invention, it is preferable that a transparent layer is further provided on the dye layer. By providing the transparent layer, the dye layer can be protected and a deep color feeling can be obtained.

  In this invention, the said magnesium alloy base material is comprised with the rolling material which consists of a Mg-Al type magnesium alloy, and it is preferable to contain 8 mass% or more and 11 mass% or less of Al. Further, the Mg—Al based magnesium alloy is preferably AZ91 based. By using the above-mentioned alloy, even in the case of painting using a dye, even if moisture permeates from the painted part, the corrosion of the substrate surface hardly proceeds. By having the above characteristics, the magnesium alloy member of the present invention is excellent in design. Hereinafter, the present invention will be described in more detail.

  According to the present invention, a magnesium alloy member having high design properties can be realized.

(Substrate composition)
As the magnesium alloy constituting the base material of the member of the present invention, those having various compositions containing Mg as an additive element (remainder: Mg and impurities) can be used, and are not particularly limited. For example, Mg-Al system, Mg-Zn system, Mg-RE (rare earth element) system, Y addition alloy, etc. are mentioned. In particular, an Mg-Al alloy containing Al is preferable because of its high corrosion resistance. Examples of the Mg-Al alloy include an AZ alloy (Mg-Al-Zn alloy, Zn: 0.2 to 1.5 mass%) and an AM alloy (Mg-Al-Mn alloy, Mn: 0.15-0.5% by mass), AS alloy (Mg—Al—Si alloy, Si: 0.6-1.4% by mass), Mg—Al—RE (rare earth element) alloy, An alloy obtained by further adding one or more elements selected from the group consisting of Bi, Sn, Pb, Ca, and Be to these Mg—Al based alloys can be given. The content of Al is preferably 1.0% by mass or more and 11% by mass or less, and as the Al content increases, the mechanical properties such as corrosion resistance and strength are excellent. However, if too much, the plastic workability tends to decrease, Considering mechanical properties and moldability, 8% by mass or more and 11% by mass or less is more preferable. In particular, Mg—Al alloys containing 8 to 11 mass% Al and 0.2 to 1.5 mass% Zn, typically AZ80 and AZ91 equivalent materials (for example, AZ91E; 8.3-9. 2% by mass of Al, AZ91D; Al containing 8.5 to 9.5% by mass of Al) can be suitably used. In particular, the AZ91 equivalent material has high corrosion resistance, and even in the case of coating using a dye, even if moisture permeates from the coated portion, corrosion of the substrate surface does not easily proceed.

(Base material form)
Typically, the base material is a rolled material obtained by rolling a cast material, a processed material obtained by further subjecting the rolled material to heat treatment, leveler processing, polishing, etc., and further pressing or bending the rolled material or processed material. Examples thereof include a plastic processed material subjected to plastic processing such as forging. Substrates that have been subjected to plastic working such as rolling and pressing have fine crystal grain size and excellent mechanical properties such as strength compared to cast materials, as well as internal and surface defects such as shrinkage and voids. And has good surface properties. Since the rolled material has fewer surface defects than the cast material, the process of filling the defect putty (defect correction) and surface polishing may or may not be performed before the undercoat layer is formed, Since the generation of defective products due to insufficient defect correction can be reduced, it is possible to contribute to an improvement in product yield. Hereinafter, casting conditions and rolling conditions will be described.

(Casting conditions)
The cast material is preferably produced by a continuous casting method such as a twin roll method, in particular, a casting method described in WO / 2006/003899. Since the continuous casting method can be rapidly solidified, oxides and segregation can be reduced, and a cast material excellent in plastic workability such as rolling can be obtained. Further, by rolling the cast material, defects that adversely affect plastic processing such as subsequent press processing, for example, coarse crystal precipitates having a particle size of 10 μm or more can be eliminated. In particular, AZ-based alloys tend to produce crystal precipitates as the amount of Al increases. However, rolling the continuous casting material results in a rolled material with few defects regardless of the alloy composition. The obtained cast material may be subjected to heat treatment (solution treatment, heating temperature: 380 to 420 ° C., heating time: 60 to 600 minutes) or an aging treatment for homogenizing the composition. In particular, in the case of an AZ-based alloy, it is preferable to perform solution treatment for a long time when the content of Al is high. The size of the cast material is not particularly limited, but is preferably 10 mm or less because segregation is likely to occur if it is too thick.

(Rolling conditions)
Rolling is preferably performed in multiple passes under the conditions of 200 to 400 ° C. for the heating temperature of the object to be processed, 150 to 250 ° C. for the heating temperature of the rolling roll, and 10 to 50% of the rolling reduction per pass. Moreover, it is preferable to appropriately combine the above conditions so that a rolled material having a desired thickness can be obtained. By appropriately combining the above-mentioned temperatures, conditions of the rolling reduction per pass, and the number of passes, for example, a workpiece having a thickness of 3 to 8 mm before rolling is 1 mm or less, specifically, a thickness of 0.2 mm. It is possible to roll.

  Intermediate heat treatment (heating temperature: 250 to 350 ° C., heating time: 20 to 60 minutes) is performed in the middle of the rolling process, and distortion, residual stress, texture, etc. introduced into the object to be processed by the processing up to this heat treatment are removed. If it reduces, it is preferable that a subsequent rolling can prevent inadvertent cracking, distortion and deformation, and can be rolled more smoothly. Further, a final heat treatment may be performed after the final rolling. For example, in the case of an AZ-based alloy, the heating temperature of the final heat treatment is preferably higher as the Al amount is higher. When the Al amount is 8 to 11% by mass, the heating temperature is 300 to 340 ° C., and the heating time is 10 to 30. Minutes are preferred. In these heat treatments, if the temperature is too high or the time is too long, the crystal grains become too coarse and the plastic workability such as press working is lowered.

The rolled material subjected to the above rolling has a small variation in crystal grain size, and has low segregation during casting (for example, an intermetallic compound such as Mg ₁₇ Al ₁₂ ), internal defects, surface defects, etc., and therefore has high plastic workability. The occurrence of cracks and cracks during processing is effectively reduced, and the surface properties are excellent.

(Preliminary machining after rolling and before plastic working)
The obtained rolled material is preferably subjected to leveler processing for correcting waviness of the rolled material, crystal grain orientation, and the like and polishing for smoothing the surface of the rolled material. The leveler processing is performed, for example, by passing the rolled material through a roller leveler, and the polishing processing is typically wet belt type polishing. The abrasive grains are preferably # 240 or more, more preferably # 320 or more, particularly # 600. The rolled material subjected to the preliminary processing and the plastic processed material obtained by performing plastic processing such as press processing on the rolled material are likely to form a layer such as a primer or a dye described later.

(Plastic processing)
Plastic processing such as press processing, deep drawing processing, forging processing, blow processing and bending processing is a temperature range in which the structure of the rolled material is recrystallized and the mechanical properties of the rolled material are not significantly changed, specifically 300. It is preferable to carry out at a temperature not higher than ° C., particularly at a temperature of 200 to 300 ° C. When plastic processing is performed on the rolled material at such a temperature, the size of the crystal grains in the portion that is not plastically deformed hardly changes, so that the strength of this portion hardly changes before and after the plastic processing, and high strength is achieved. It is possible to maintain a high-strength plastic working material.

  The plastic working may be performed at any stage before or after the formation of a coating layer such as an undercoat layer or a dye layer described later.

  A heat treatment may be performed after the plastic working to remove strain and residual stress introduced by the plastic working and to improve the mechanical characteristics. The heat treatment conditions include heating temperature: 100 to 450 ° C., heating time: about 5 minutes to 40 hours.

(Anti-corrosion treatment)
The anticorrosion treatment is performed by chemical conversion treatment, anodization treatment or the like. When the anticorrosion treatment is performed, magnesium on the surface of the base material is oxidized to produce an oxide of magnesium, and a layer made of this oxide functions as an anticorrosion layer. This anticorrosion layer may be formed before plastic working such as press working or after plastic working. If an anticorrosion layer is provided before plastic processing, this layer may function as a lubricant during plastic processing. Furthermore, since this anticorrosion layer produces the state where the fine crack (crack) produced, the adhesiveness with an undercoat becomes high because the constituent material of an undercoat enters into the crack.

(Undercoat layer)
The purpose of the primer layer is to improve the corrosion resistance so that corrosion factors such as moisture do not penetrate into the base material, to increase the adhesion of the coating film on the magnesium alloy and the adhesion to the dye layer or scattering layer on the primer layer Arranged. The undercoat layer is formed of a resin agent. By using a resin agent, good adhesion with a dye layer or the like can be obtained. Examples of the resin used include alkyd resin, acrylic resin, saturated polyester resin, unsaturated polyester resin, epoxy resin, urethane resin, fluororesin, silicon resin, amide resin, epoxy / acrylate resin, and the like. When using an epoxy resin system, a baking type, a two-part type, or a one-part type is applied by a spray method, a dipping method, or a brush coating method. The heat treatment (drying) is performed at 60 to 180 ° C. for 10 to 120 minutes depending on the type. A powder paint or water-based paint can be used as long as adhesion and corrosion resistance are satisfied. The undercoat layer preferably has a thickness of 10 μm or more and 30 μm or less. If it is less than 10 μm, uniform coating is difficult, and the adhesion and corrosion resistance may not be satisfied throughout the coating film, which is not preferable. On the other hand, if the thickness exceeds 30 μm, the entire coating film thickness is increased, the adhesion is deteriorated, the outer dimensions of the product are increased, and the coating cost is increased.

(Dye layer)
In order to give a deep color feeling to the magnesium alloy member, a layer containing a dye is disposed on the primer layer. The dye layer is a layer formed by applying a solution containing a dye. As a coloring method, it is possible to provide a layer containing a pigment, but a dye is used as a colorant in order to obtain a deeper color feeling and to give a good color with a higher degree of freedom. The dye layer is coated with a direct dye, acid dye, metal-containing complex dye, oil-soluble dye or the like dissolved in various solvents by a spray method, etc., and subjected to heat treatment (drying) at 50 to 120 ° C. for 10 to 100 minutes. Form. The dye layer preferably has a thickness of 15 μm or more and 30 μm or less. If it is less than 15 μm, it is difficult to obtain a deep color feeling even if a dye is used, and color unevenness occurs due to variations in film thickness, which is not preferable. On the other hand, if it exceeds 30 μm, like the undercoat layer, the entire coating film thickness is increased, the adhesion is deteriorated, the outer dimensions of the product is increased, and the coating cost is increased.

  The basic part of the present invention is composed of the above-mentioned undercoat layer and dye layer, but the following scattering layer and transparent layer may be added in order to further improve designability and corrosion resistance.

(Scattering layer)
The scattering layer is disposed between the primer layer and the dye layer. The scattering layer is a layer formed by applying a solution containing metal powder. The purpose of this scattering layer is to diffusely reflect the light transmitted through the dye layer. A deeper color can be obtained by irregularly reflecting the transmitted light. The scattering layer is formed by applying a paint in which metal fine powders such as Al, Ti, and Ag are dispersed by a spray method or the like, and performing heat treatment (drying) at 50 to 120 ° C. for 10 to 100 minutes. The scattering layer preferably has a thickness of 10 μm or more and 20 μm or less. If it is less than 10 μm, uniform coating is difficult, and the scattering state of the transmitted light of the upper dye layer is not uniform, and color unevenness is not preferable. On the other hand, when the thickness exceeds 20 μm, there are problems such as poor adhesion, large external dimensions of the product, and high coating cost.

(Transparent layer)
The transparent layer is disposed on the dye layer. This transparent layer is not particularly limited as long as it is transparent, has excellent adhesion to the dye layer, and is excellent in corrosion resistance and surface hardness to some extent. For example, a known clear coating using a resin such as a transparent acrylic resin or a transparent fluororesin can be used. In order to form a transparent layer using the above resin or the like, either a wet method (immersion method, spray coating, electrodeposition coating, etc.) or a dry method (PVD method, CVD method) may be used. Various ultraviolet curable resins can also be used. By providing the transparent layer, the dye layer can be protected and a deep color feeling can be obtained. The transparent layer preferably has a thickness of 20 μm or more and 200 μm or less. If it is less than 20 μm, it is too thin to obtain a deep color feeling, and it is difficult to serve as a protective layer. On the other hand, if it exceeds 200 μm, the adhesion is deteriorated and the color of the dye layer may be blurred.

  1 and 2 are cross-sectional views schematically showing a magnesium alloy member of the present invention. As shown in FIG. 1, an undercoat layer 11 is disposed on the surface of a rolled magnesium alloy substrate 10, and a dye layer 12 is disposed thereon. By taking such a structure, it becomes a magnesium alloy member with high designability. Also, the configuration as shown in FIG. 2 can be taken. Each layer is laminated | stacked in order of the rolled magnesium alloy base material 10, the undercoat layer 11, the scattering layer 13, the dye layer 12, and the transparent layer 14. FIG. With such a laminated structure, a deeper color feeling can be obtained.

(Test Example 1)
A cast material and a rolled material made of a magnesium alloy were prepared, and the coating treatment of the undercoat layer and the dye layer was performed, and the panel test, corrosion resistance test, and adhesion test were performed on the appearance.

  It consists of a magnesium alloy having a composition equivalent to AZ31 (Mg-3.0 mass% Al-0.7 mass% Zn) and a composition equivalent to AZ91 (Mg-9.0 mass% Al-0.7 mass% Zn). Board material was prepared. The cast material is produced by a die casting method and has a thickness of 1 mm. The rolled material is obtained by rolling a 5 mm thick plate obtained by twin roll casting. As the conditions, the temperature of the rolling object is 200 to 400 ° C., the rolling roll temperature is 150 to 250 ° C., and rolling is performed a plurality of times under the condition that the rolling reduction per pass is 10 to 50%, so that the final thickness becomes 0.6 mm. I made it. The obtained rolled material and cast material were subjected to leveler processing and polishing processing in this order, and the cut pieces cut into a desired size were subjected to warm press processing (press temperature 200 to 300 ° C.) to obtain a pre-coating material.

  The pre-coating material is subjected to a base treatment to form a coating layer (undercoat layer, dye layer) to obtain a magnesium alloy member. The base treatment was performed in the order of degreasing → acid etching → desmutting → surface adjustment → chemical conversion treatment → drying. Wash with water between each step from degreasing to drying. The conditions are described below.

Degreasing: 10% KOH and nonionic surfactant 0.2% solution under stirring, 60 ° C., 10 minutes Acid etching: 5% organic phosphoric acid solution stirring, 40 ° C., 1 minute Desmutting: 10% KOH solution Under ultrasonic stirring of 60 ° C., 5 minutes Surface adjustment: 60 ° C., 5 minutes under stirring of an aqueous carbonate solution adjusted to pH 8 Chemical conversion treatment: P-based treatment solution manufactured by Company A with 10% phosphoric acid as a main component + 1% Using KOH as a treatment liquid, stirring, 30 ° C., 2 minutes, drying: 150 ° C., 5 minutes

  The undercoat layer was formed by spraying a baking type epoxy paint and baking at 160 ° C. for 30 minutes. Several test materials were prepared by changing the thickness of the primer layer. Table 1 shows combinations of the thickness of the pre-coating material and the undercoat layer.

  The dye layer was formed by spraying a paint using a metal-containing complex dye and performing a baking treatment at 80 ° C. for 20 minutes. Several test materials were prepared by changing the thickness of the dye layer. Table 1 shows the conditions.

(Test Example 2)
The material which performed the process similar to Test Example 1 was prepared until the base | substrate process, and the test material which made the structure of the coating layer the undercoat layer, the scattering layer, the dye layer, and the transparent layer was produced.

  The undercoat layer was formed under the same conditions as in Test Example 1. The scattering layer was formed by spray-coating a paint in which Al fine powder was dispersed and baking at 90 ° C. for 20 minutes. Several test materials were produced by changing the thickness of the scattering layer.

  The dye layer was formed under the same conditions as in Test Example 1. The transparent layer was formed by spraying a colorless and transparent acrylic paint and baking at 150 ° C. for 10 minutes. For the transparent layer, several thicknesses were changed to prepare test materials. Table 1 shows the thickness of each layer of the produced test material.

(Panel test)
About the obtained test material, the panel test was implemented for arbitrary 10 persons. ◎ when 9 or more out of 10 have a deep color sense and excellent design, ◎ for 7-8, △ for 5-6, △ 4 The following cases were evaluated as x. The results are shown in Table 1. The panel test target can be selected according to the target layer of a product using a magnesium alloy member such as a personal computer or a mobile phone (for example, a group that likes PCs in their 20s).

(Corrosion resistance test)
According to JIS Z2371 (salt water spray test method), each test material was evaluated for the presence or absence of corrosion after spraying 5% salt water for 240 hours.

(Adhesion test)
In accordance with JIS K5600-5-6 (Adhesion (Crosscut)), an adhesion test was conducted to evaluate the adhesion of the coating layer. That is, 11 cuts are made in the coating film at intervals of 1 mm vertically and horizontally, and an adhesive tape is pasted thereon to peel off, and the number of coating films peeled off from the magnesium alloy surface is counted. The case where all 100 pieces are not peeled is denoted by ◎, the number of peeled pieces of 10 or less is indicated by ○, and the case where 11 pieces or more are peeled is indicated by ×.

  As can be seen from the results in Table 1, the test examples using the rolled material (Test Examples 1-A to E, G, Test Example 2-A to E, G) are the test examples using the cast material (Test Example). The panel test results are higher than 1-F and Test Example 2-F). In other words, it can be said that the design is excellent. Moreover, it can be said that the direction which has a scattering layer and a transparent layer has high designability from the comparison of Test Example 1-A and Test Example 2-A.

  Furthermore, it can be said from the comparison between Test Example 2-A and Test Example 2-G that the design using the AZ91 material is higher. Furthermore, it is preferable to use the AZ91 material from the viewpoint of corrosion resistance. Furthermore, when the AZ91 rolled material is used, the thickness of each layer is within the above-described preferred range (undercoat layer 10 to 30 μm, dye layer 15 to 30 μm, scattering layer 10 to 20 μm, transparent layer 20 to 200 μm: test example 1-A, Test Example 2-A) and those outside the range (Test Examples 1-B to E, Test Example 2-B to E) are superior in design, corrosion resistance, and adhesion within the range. It can be said that it has sex.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the composition of the magnesium alloy, the conditions of casting, rolling, and plastic working, the plate thickness after casting and after rolling, the forming method of the uneven processing, the forming conditions, the forming material of the coating layer, the forming method, etc. may be appropriately changed. it can.

  The magnesium alloy member of the present invention can be suitably used in a field that is desired to have excellent design properties such as a casing of portable electric equipment.

It is a cross-sectional schematic diagram which shows the magnesium alloy member of this invention. It is a cross-sectional schematic diagram which shows the magnesium alloy member of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnesium alloy base material 11 Undercoat layer 12 Dye layer 13 Scattering layer 14 Transparent layer

Claims (5)

  A magnesium alloy member characterized by having an undercoat layer on at least one surface of a rolled magnesium alloy material and a dye layer on the undercoat layer.   2. The magnesium alloy member according to claim 1, further comprising a scattering layer between the undercoat layer and the dye layer.   The magnesium alloy member according to claim 1, further comprising a transparent layer on the dye layer.   The magnesium alloy member according to any one of claims 1 to 3, wherein the magnesium alloy material is composed of a Mg-Al-based magnesium alloy and contains 8 mass% or more and 11 mass% or less of Al.   The magnesium alloy member according to claim 4, wherein the Mg—Al-based magnesium alloy is AZ91-based.

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