JP5105577B2 - Method for producing magnesium alloy molded processed body and magnesium alloy molded processed body - Google Patents

Description

  The present invention particularly relates to a method for manufacturing a magnesium alloy molded processed body having a beautiful surface after molding and a magnesium alloy molded processed body using the manufacturing method.

  Lightweight magnesium alloy is an exterior case member for small portable electronic devices such as mobile communication devices and laptop computers, large case members such as suitcases for travel and attachment cases for storing documents, hoods, trunk lids, doors, fenders, etc. Application to automotive parts and the like has been attempted. However, magnesium alloys have poor workability and are extremely difficult to form at a high workability. In order to draw such a difficult-to-work magnesium alloy, the temperature of the die, punch, and wrinkle pressing member of the draw forming apparatus is heated to about 150 to 400 ° C. (see, for example, Patent Document 1). ), Heating the die, punch, and blank holder, and heating the magnesium to the recrystallization temperature range through these forming tools, and the heating induces an annealing effect that recrystallizes and softens and easily deforms. However, a method of heating a magnesium alloy to a recrystallization temperature range at the time of forming, such as a manufacturing method of a magnesium alloy hard case in which a magnesium blank is hot-drawn in a box shape (see, for example, Patent Document 2) has been proposed.

  It has also been proposed to use a lubricant to facilitate processing. For example, a method of forming an ultra-hard film such as titanium nitride or diamond-like carbon on the surface of a press mold by a coating process (see, for example, Patent Document 3), biodegradable oil, rust preventive / lubricant, extreme pressure There has been proposed a method of forming using a plastic working oil for magnesium alloy or aluminum alloy containing an additive, further an organic zinc compound and an organic molybdenum compound (see, for example, Patent Document 4). However, even when these are heated and molded, molded using a lubricant, or heated and molded using a lubricant, the surface tends to be wrinkled by contact with the tool during processing. It cannot be applied to applications that require a beautiful surface appearance.

  In order to prevent wrinkles on the surface during molding, a method of performing plastic working by attaching a plate made of pure magnesium, pure aluminum, resin, etc. softer than magnesium alloy material to at least one surface of the punch and die (for example, Patent Document 5) and a method of press forming at a high temperature by placing a fluororesin film sheet as a heat insulating material on the upper and lower surfaces of a heated magnesium thin plate have been proposed (for example, see Patent Document 6). However, in these methods, soft pure magnesium, pure aluminum, resin, or fluororesin film sheet used as a cushioning material must be used for each processing, and the continuous productivity is poor. In particular, since the fluororesin film sheet is expensive, a molded product obtained by using these methods must be disadvantageous in terms of cost.

Prior art documents relating to the present invention include the following.
JP 2003-290843 A JP 2002-254115 A JP 2003-154418 A JP 2003-105364 A Japanese Patent Laid-Open No. 2001-300643 Japanese Patent Laid-Open No. 06-328155

  An object of the present invention is to provide a manufacturing method for forming a magnesium alloy molded processed body at a high degree of processing at low cost, and a magnesium alloy formed processed body having a beautiful surface formed by using the manufacturing method. And

In order to achieve the object of the present invention, the present invention has the following features.
(1) The method for producing a magnesium alloy molded product of the present invention comprises:
Cover the surface of the magnesium alloy material with an organic resin that gives processability,
After molding into a predetermined shape at 200-350 ° C ,
A method for producing a magnesium alloy molded processed body in which the organic resin is removed using a resin coating removing liquid ,
The organic resin is
It is characterized by comprising one or more of a water-soluble urethane resin, a water-soluble polyester resin, a water-soluble acrylic resin, a water-soluble epoxy resin, or a resin obtained by modifying these organic resins .
(2) The manufacturing method of the magnesium alloy formed processed body of the present invention is the above (1),
After the organic resin is removed, surface treatment and / or coating is performed on the magnesium alloy material molded into a predetermined shape.
(3) The manufacturing method of the magnesium alloy molded processed body of the present invention is the above (1) or (2),
The organic resin further contains any one or more of a silane coupling agent, colloidal silica, a lubricant, and a metal alkoxide.
(4) The method for producing a magnesium alloy formed article of the present invention is any one of the above (1) to (3),
The organic resin further contains a heat resistance imparting agent.
(5) The method for producing a magnesium alloy molded processed body of the present invention is any one of the above (1) to (4),
As the resin coating removing liquid, a liquid mainly composed of an alkaline aqueous solution having a pH of 10 or more is used.
(6) The method for producing a magnesium alloy formed article of the present invention is any one of the above (1) to (5).
When the surface of the magnesium alloy material is coated with an organic resin imparting processability and molded into a predetermined shape, the surface friction coefficient at the processing temperature is 0.2 or less.
The friction coefficient is a value measured using a HEIDON ball contact friction coefficient measuring device (Dynamic Strain Amplifer 3K-34D, Peeling / Slipping / Scratching TESTER HEIDON-14).

The magnesium alloy molded processed body of the present invention is characterized by being manufactured using the method for manufacturing a magnesium alloy molded processed body according to any one of the above (1) to (6).

Hereinafter, the present invention will be described in detail.
The magnesium alloy material used in the production of the magnesium alloy molded body of the present invention includes pure magnesium, 1.0 to 9.0% by weight of aluminum as an alloy component, 0.5 to 6.0% by weight of zinc, manganese Is a magnesium alloy having a crystal grain size of 2 to 50 μm, more preferably 2 to 10 μm. (Hereinafter, in order to simplify the description, both pure magnesium and a magnesium alloy are collectively referred to as a magnesium alloy). These magnesium alloys are applied to the following forming processes as plate materials such as extruded materials, cutting materials, and hot rolled materials. When a plate material is used, the plate thickness is preferably 0.05 to 2.0 mm. The surface of these magnesium alloy materials is coated with an organic resin to obtain a magnesium alloy material for forming.

  The organic resin coated on the surface of the magnesium alloy material is preferably a water-soluble or water-dispersible resin, such as a water-soluble urethane resin, a water-soluble polyester resin, a water-soluble acrylic resin, a water-soluble epoxy resin, or these organic resins. A water-soluble acrylic-modified polyester resin, a phenyl silicone-modified acrylic resin, and the like obtained by modifying the above are preferable. These organic resins may be used alone or in combination of two or more. The addition percentage of the organic resin is desirably in the range of 20 to 85% by weight. If it is less than 20% by weight, the formed organic resin film is undesirably easily damaged by processing. If it exceeds 85% by weight, there is no problem in characteristics, but it is not economical. Furthermore, since a temperature exceeding 150 ° C. is often used as the processing temperature of the magnesium alloy material, it is preferable to use an organic resin having excellent heat resistance.

  These organic resins may be water-soluble or water-dispersible resins alone, applied to the above magnesium alloy material and dried to form a film, but in order to improve moldability and corrosion resistance, the following substances are used. You may use it by making it contain in organic resin. When other substances are added, the water-soluble or water-dispersible resin is desirably contained in an amount of 20% by weight or more. If it is less than 20% by weight, the formed organic resin film tends to be damaged by processing, which is not desirable. By including a silane coupling agent, the adhesion of the organic resin film to the magnesium material, particularly the adhesion during molding, is significantly improved. Silane coupling agents are classified according to the type of functional group such as vinyl, epoxy, styryl, methacryloxy, acryloxy, amino, ureido, chloropropyl, mercapto and isocyanate. It can be used effectively. This is presumably because the silane coupling agent has excellent binding properties, that is, adhesion to most resins. Specifically, the epoxy silane coupling agent KBM403 is excellent in bonding with urethane and epoxy resins, and the amino silane coupling agent KBM903 is excellent in bonding with acrylic resins and has excellent adhesion. Showing gender. In addition, since there are various types of urethane resins, not only the epoxy silane coupling agent KBM403 but also the amino silane coupling agent KBM903 can provide excellent effects. The silane coupling agent is preferably contained in the organic resin film at 5% by weight or less, more preferably 1% by weight or less. Even if the content exceeds 5% by weight, the effect of improving the adhesion is saturated, which is not economically advantageous.

  Moreover, by including colloidal silica, the hardness of the organic resin film is improved, the scratch resistance is improved, and the corrosion resistance is also improved. The colloidal silica is preferably contained in the organic resin film at 50% by weight or less. If the content exceeds 50% by weight, the organic resin film becomes too hard, the workability of the organic resin film deteriorates, and cracks are likely to occur in the organic resin film during molding.

  Furthermore, by including a lubricant, the moldability of the magnesium alloy material for forming, in which an organic resin film is formed on the magnesium alloy material, is improved. As the lubricant, higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, calcium salts, aluminum salts, zinc salts, barium salts, magnesium salts of these higher fatty acids, higher fatty acid esters thereof, polyethylene wax, Polyolefin wax such as polypropylene wax, fluorine wax such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride, inorganic powder such as graphite, molybdenum disulfide, and boron nitride can be used. . These lubricants are preferably contained in the organic resin film at 20% by weight or less. When the content exceeds 20% by weight, the adhesion at the time of molding the organic resin film to the magnesium alloy material deteriorates.

  Furthermore, by including a metal alkoxide, the heat resistance of the magnesium alloy material for forming, in which an organic resin film is formed on the magnesium alloy material, is improved. Examples of the metal alkoxide include boron, aluminum, titanium, vanadium, manganese, iron, cobalt, copper, yttrium, zirconium, niobium, lanthanum, cerium, tantalum, and tungsten alkoxides. Among them, titanium-based alkoxides are preferable. Can be used. These metal alkoxides are preferably contained in the organic resin film at 10% by weight or less. When the content exceeds 10% by weight, the moldability of the magnesium alloy material for molding in which an organic resin film is formed on the magnesium alloy material is lowered. The silane coupling agent, colloidal silica, lubricant, and metal alkoxide may each be contained alone in the organic resin film, but may be contained in two or more.

  The organic resin obtained as described above is applied to the surface of the magnesium alloy material and dried to form an organic resin film. The thickness of the organic resin film is preferably 0.1 to 50 μm, and more preferably 1 to 10 μm after drying. Thus, a magnesium alloy material for forming is obtained, but the coefficient of friction of the surface at the processing temperature is preferably 0.2 or less. The friction coefficient at the processing temperature is the friction coefficient at the temperature at which the magnesium alloy material for forming is processed. HEIDON ball contact friction coefficient measuring device (Dynamic Strain Amplifer 3K-34D, Peeling / Slipping / Scratching TESTER HEIDON- It is a value measured using 14).

  The magnesium alloy material for forming obtained as described above has a coefficient of friction of 0.2 or less at the processing temperature and is excellent in formability, and is used for drawing, forging, rolling, press forging, etc. Thus, it can be suitably molded without using a solid lubricant such as lubricating oil or molybdenum disulfide which has been conventionally used. Further, since it can be suitably formed even when used together with a solid lubricant such as lubricating oil or molybdenum disulfide which has been conventionally used, a conventional method for producing a magnesium alloy material that requires application of lubricating oil and the present invention It is also possible to use a manufacturing method capable of non-oil-coating and to process continuously in a conventional oil-coating manufacturing process. Further, when the magnesium alloy material for forming is heated to a temperature range of 350 ° C. or less, preferably 200 to 350 ° C., the workability is further improved as compared with a temperature range of less than 200 ° C. In addition, it is possible to perform molding with a high degree of processing. However, when the molding process is performed in a temperature range exceeding 200 ° C., the organic resin film is decomposed and discolored or cracks are generated in the film, which deteriorates the appearance and makes it difficult to improve the degree of processing. Therefore, not only improving the heat resistance of the organic resin alone, but also adding a heat resistance imparting agent to the organic resin film, the organic resin film is discolored in a high temperature processing temperature range of 200 to 350 ° C. or less. Or forming a crack without causing cracks, and the degree of processing can be improved. As a result, in the forming process of the magnesium alloy material for forming process, the processing temperature at which the same workability as that obtained when using a conventional lubricating oil is used can be lowered in a temperature range of 350 ° C. or lower. This makes it possible to obtain an advantage that unnecessary heat treatment is unnecessary. Of course, needless to say, it is not necessary to apply the lubricating oil during the molding process.

  As the heat resistance imparting agent, it is preferable to use a heat resistant resin such as polyimide or a siloxane compound. Examples of the siloxane compound include polymers and monomers of organosiloxanes such as dimethylsiloxane, diethylsiloxane, methylethylsiloxane, diphenylsiloxane, and methylphenylsiloxane, or polyalkylene oxide groups, hydroxyl groups, amide groups, and carboxyl groups in these organosiloxane molecules. , One having at least one substituent of at least one of a sulfone group and an amino group is preferably used. These heat resistance imparting agents are preferably contained in the organic resin film in an amount of 5 to 80% by weight, and more preferably 10 to 60% by weight. In this way, by including a heat resistance imparting agent in the organic resin film, it is possible to heat the magnesium alloy material for forming to a warm working temperature range of 200 to 350 ° C. and form it with a high workability. It becomes. The heat resistance imparting agent may be contained alone in the organic resin, but may be contained in combination with one or more of the above silane coupling agent, colloidal silica, and lubricant. Good.

  The organic resin film remains and adheres to the surface of the magnesium alloy molded body thus molded. Depending on the application, it may be used as it is, or may be further coated on the organic resin film as necessary. However, when applied to applications where a beautiful metal surface itself is required, the organic resin remaining on the surface must be removed. The organic resin may be removed by spraying abrasive particles on the surface using a shot blasting method, but the surface shape changes, and therefore it is preferable to remove the organic resin using a removing liquid. As the removal liquid, it is preferable to use a liquid mainly composed of an alkaline aqueous solution having a pH of 10 or more and a surfactant or the like imparting wettability or wettability to the alkaline aqueous solution. When the pH is 10 or less, it takes a long time to remove. The alkaline aqueous solution is inexpensive, and the alkaline aqueous solution remaining after the organic resin is removed can be easily washed with water and then dried, so that the cost required for the organic resin removal step can be reduced.

  The magnesium alloy molded processed body of the present invention can be obtained as described above, but in order to impart corrosion resistance and aesthetics, the molded processed body is further subjected to known surface treatments such as anodizing treatment, chemical conversion treatment and plating. It may be applied or a transparent or colored coating may be applied. Alternatively, after performing any of these surface treatments, a transparent or colored coating may be further applied thereon.

  The magnesium alloy molded product produced by using the production method of the present invention as described above has a beautiful metal surface, and the exterior of a small portable electronic device such as a mobile communication device or a laptop computer. The present invention can be suitably applied to a case member, a large case member such as a travel suitcase or an attachment case for document storage, and an automobile member such as a hood, a trunk lid, a door, or a fender.

Hereinafter, the present invention will be described in detail with reference to examples.
(Making magnesium alloy material for forming)
As a magnesium alloy material for forming, the resin solution shown in Table 1 or the silane coupling agent shown in Table 1 on the resin shown in Table 1 on both sides of a 0.4 mm-thick magnesium alloy plate having the following alloy components: , Colloidal silica, lubricant, metal alkoxide, heat resistance-imparting resin solution so that each additive has the content shown in Table 1 in the dried state, and the resin film after drying The coating was applied using a bar coater so as to have the thickness shown in Table 1 and dried to prepare a magnesium alloy material for molding for testing.
<Alloy components>
Al: 3.1 wt%, Zn: 1.1 wt%, Mn: 0.31 wt%, balance: Mg and inevitable impurity elements <Average crystal grain size>
8μm

(Making magnesium alloy molded products)
The magnesium alloy material for forming obtained as described above was drawn under the following conditions to obtain a magnesium alloy formed article. The processing temperature was the same as that of the die and the blank holder, and only the punch temperature was room temperature. In addition, the friction coefficient at the processing temperature was measured with a HEIDON friction coefficient measuring apparatus attached with a holder heating device. In the measurement, after heating the forming magnesium alloy material fixed to the holder to the processing temperature, the contact ball is a SUS ball having a diameter of 10 mm attached to the apparatus, a measurement load of 200 g, and a measurement time of 1.6 mm / sec. It was measured.
<Punch shoulder R>
5mm
<Punch temperature>
Room temperature <Dice temperature>
200 ° C, 250 ° C
<Blank holder temperature>
200 ° C, 250 ° C
<Aperture speed>
1 mm / sec <lubricating oil and lubricant>
No lubricating oil or lubricant is used when processing the magnesium alloy material of the present invention

  As a comparative example, sample No. 17 obtained by applying a commercially available plastic working oil G3080 (manufactured by Nippon Yasaku Oil Co., Ltd.) on both sides of the above magnesium alloy material, and fluorine having a thickness of 50 μm on both sides of the magnesium alloy material A sample provided with a resin film was drawn under the same conditions as Sample No. 18 to obtain a magnesium alloy molded body for comparison.

(Removal of organic resin film)
From the magnesium alloy molded product of the present invention obtained as described above, the organic resin film remaining and adhered under the following conditions was removed.
<Removal bath>
Bath composition Top Magster 100 (Okuno Pharmaceutical Co., Ltd.) 300mL / L
Top Magster 100AD (Okuno Pharmaceutical Co., Ltd.) 10mL / L
An aqueous solution obtained by mixing pH 13.4
Bath temperature 70 ° C
Agitation Ultrasonic immersion time 10 minutes In this way, test materials shown as sample numbers 1 to 13 were obtained.

(surface treatment)
The sample material of sample number 3 was anodized under the following conditions as a surface treatment to obtain a sample material of sample number 14.
<Anodizing treatment>
Bath composition Ammonium dichromate 40g / L
Ammonium sulfate 25g / L
Ammonia water 3.0mL / L
Bath temperature 40 ℃
Stirring bath circulation Current density 1A / dm ²

(Painting)
A transparent polyester resin paint was applied to the sample material of sample number 3 so that the thickness after drying was 10 μm and dried to obtain a sample material of sample number 15.

(Surface treatment and painting)
The sample material of sample number 3 was anodized in the same manner as the sample material of sample number 14, and then coated in the same manner as the sample material of sample number 15, and the sample material of sample number 16 was applied. It was.

(Comparative material for comparison)
Lubricating oil adhering to the surface of the magnesium alloy molded processed body of the comparative example was removed with acetone, and a sample No. 17 was prepared. Moreover, the magnesium alloy molding processed body of the comparative example peeled the fluororesin film, and used it as the sample material of the sample number 18.

(Evaluation of surface appearance of magnesium alloy molded product)
The appearances of the magnesium alloy molded products of Sample Nos. 1 to 18 obtained as described above were visually observed and evaluated according to the following criteria.
A: No damage is observed on the sample surface.
○: No practical damage is observed.
Δ: Damage causing practical problems is observed.

(Evaluation of post-processing properties)
Regarding the magnesium alloy molded processed bodies of Sample Nos. 14 to 16, the state of post-treatment (anodic oxidation treatment and / or coating) performed after removing the remaining organic resin film was visually observed and evaluated according to the following criteria.
○: Appearance which is a problem in practical use is not recognized at all.
These results are shown in Table 2.

  As shown in Table 2, the magnesium alloy material according to the present invention is obtained by coating a magnesium alloy material with an organic resin and then removing the remaining organic resin using an organic resin removing solution. Compared to conventional magnesium alloy molded products that have been molded using a lubricating oil, the surface is hardly wrinkled and an expensive fluororesin film is formed. A beautiful surface state equivalent to the magnesium alloy molded product used can be obtained. Furthermore, after removing the remaining organic resin film from the magnesium alloy molded body of the present invention, surface treatment such as anodizing treatment for improving corrosion resistance and appearance and / or post-treatment such as painting can be applied without any problem. can do.

  Magnesium alloy molding according to the present invention, wherein the surface of the magnesium alloy material is coated with an organic resin imparting processability and molded into a predetermined shape, and then the organic resin is removed using a resin coating removing liquid Magnesium alloy molding processed body formed by using the manufacturing method of the processed body can be processed at a high degree of processing and is formed using a conventional lubricant. Compared to the body, the surface is less likely to be wrinkled and has a beautiful surface equivalent to a magnesium alloy molded body formed by molding using an expensive fluororesin film. Further, the organic resin can be easily removed using an inexpensive removal solution. Therefore, when a magnesium alloy molded processed body is manufactured using the manufacturing method of the present invention, the obtained magnesium alloy molded processed body has a beautiful surface free from wrinkles and can be manufactured at low cost. Yes, for automobiles such as exterior case members for small portable electronic devices such as mobile communication devices and laptop computers, large case members such as suitcases for travel and attachment cases for storing documents, hoods, trunk lids, doors, fenders, etc. It can be suitably applied to members and the like.

Claims (7)

Cover the surface of the magnesium alloy material with an organic resin that gives processability,
After molding into a predetermined shape at 200-350 ° C ,
A method for producing a magnesium alloy molded processed body in which the organic resin is removed using a resin coating removing liquid ,
The organic resin is
Magnesium alloy molding process characterized by comprising one or more of a water-soluble urethane resin, a water-soluble polyester resin, a water-soluble acrylic resin, a water-soluble epoxy resin, or a resin obtained by modifying these organic resins Body manufacturing method. 2. The method for producing a magnesium alloy molded processed body according to claim 1, wherein after the organic resin is removed, surface treatment and / or coating is performed on the magnesium alloy material molded into a predetermined shape. 3. The magnesium alloy according to claim 1 , wherein the organic resin further contains any one or more of a silane coupling agent, colloidal silica, a lubricant, and a metal alkoxide. A method for producing a molded product. The method for producing a magnesium alloy molded processed body according to any one of claims 1 to 3, wherein the organic resin further contains a heat resistance imparting agent. The method for producing a magnesium alloy molded processed body according to any one of claims 1 to 4 , wherein a liquid mainly composed of an alkaline aqueous solution having a pH of 10 or more is used as the resin coating removal liquid. When the surface of the magnesium alloy material is coated with an organic resin imparting processability and molded into a predetermined shape, the surface friction coefficient at the processing temperature is 0.2 or less. Item 6. A method for producing a magnesium alloy molded article according to any one of Items 1 to 5.
However, the friction coefficient is a value measured using a HEIDON ball contact friction coefficient measuring device (Dynamic Strain Amplifer 3K-34D, Peeling / Slipping / Scratching TESTER HEIDON-14). A magnesium alloy molded processed body manufactured by using the method for manufacturing a magnesium alloy molded processed body according to any one of claims 1 to 6 .