KR20090077372A - High close adhesion coating method for metal alloy and metal alloy coated by the same - Google Patents

Abstract

A method for painting a metal alloy molding material with high adhesion and the painted metal alloy molding material are provided to offer high adhesion on a coating surface of the metal alloy molding material. A method for painting a metal alloy molding material with high adhesion includes the following steps of: performing an alkali degreasing process of the metal alloy molding material(201); washing the metal alloy molding material of a first base material with water or purified water or warm water; drying the metal alloy molding material of a second base material; spraying flame of fuel gas including a modifier compound of which boiling point is 10°C~105°C on the surface of the material; and applying a coating layer which is a design layer on the material.

Description

High close adhesion coating method for metal alloy molding and metal alloy molded by the above method

The present invention utilizes metal alloys such as magnesium alloys, aluminum alloys, titanium alloys, and the like to form new high adhesion to metal alloy moldings formed by injection molding, die casting molding, thixo casting molding, and the like. The present invention relates to a coating method and a metal alloy molding coated with high adhesion by the above method.

Currently, metal alloy moldings formed by means of injection molding, die casting molding, thixocast molding, etc. utilizing metal alloys such as magnesium alloys, aluminum alloys and titanium alloys are used for mini disks, video cameras, digital cameras and mobile phones. It is widely used in various fields such as electronics. Among the metal alloys, magnesium alloys are particularly light in weight, have a greater than one-digit strength, and have high thermal conductivity and excellent heat dissipation, and thus have good electromagnetic shielding properties. Marketability is expanding year by year.

However, metal alloy moldings formed by means such as injection molding, die casting molding, thixocast molding, or the like, which are represented by magnesium alloys, are never used as they are, and acrylic resin paint systems or urethane resin paint systems It is common to coat a design with paint, such as. On the other hand, since the process leading to the coating of the metal alloy molding, the molding means such as injection molding, die casting molding, thixocast molding, etc., the casting surface is rough, there are also problems such as adhesion release agent, etc. In order to secure close contact in reality, a very complicated process is required. As an example, the coating of magnesium alloy molded products is described as work input → boiling water washing → strong alkali degreasing → boiling water washing → purified water cleaning → chemical conversion treatment (such as zinc phosphate coating) → purified water cleaning → dewatering drying → dust removal → spraying It has to go through the painting process and at least eight processes before reaching the painting process, and further ensures close contact between the metal alloy molding and various paints as a step before entering the painting process. In order to secure a good coating finish, many processes, time, effort, and cost were required, such as coating a primer such as epoxy resin and then applying an adhesive (putter) treatment process if necessary.

Here, the inventor of the present invention discloses a "surface modification technique" disclosed in the following patent document, which the inventors have already developed and are planning for practical use in securing adhesion at the coating interface of a metal alloy molding represented by a magnesium alloy. Attempted to find and confirm that the above-described "interface modification technology" works very effectively for the interfacial modification of a metal alloy molding represented by a magnesium alloy.

[Patent Document 1] Japanese Patent Laid-Open No. 2003-238710 (Patent No. 3557194)

In "Patent Document 1", outlines of a method for interfacial modification of a solid material and an apparatus thereof are disclosed, each of which contains a silane atom, a titanium atom, and an aluminum atom, each having a boiling point of 10 ° C to 100 ° C. Prepare an interfacial reformer comprising a storage tank for storing fuel gas containing a surface modifier compound, a conveying unit for transferring the fuel gas to the injector, and an injector (burner) for injecting a flame of the fuel gas. In addition, an interfacial modification technique is disclosed in which a silicate salt or the like is sprayed on the surface of a material of a solid material in whole or in part to activate the treatment part.

However, Patent Document 1 merely describes a surface modification method common to various solid materials in interfacial modification of each solid material, and is a metal alloy molded product represented by magnesium alloy, which is a specific problem to be solved by the present invention. There is no disclosure regarding a specific methodology related to securing adhesion in the painting interface.

The present invention provides a specific methodology for securing adhesion at the coating interface of a metal alloy molding represented by a magnesium alloy, which not only ensures the adhesion at the coating interface of the metal alloy molding, but is also a subsequent coating. A high adhesion coating method to a metal alloy molding which can greatly simplify various steps in the step, and a metal alloy molding coated with high adhesion by the coating method.

More specifically, the molding technology of metal alloy moldings formed by means such as injection molding, die casting molding, thixocast molding, or the like represented by conventional magnesium alloys has been a significant technological innovation in recent years, as represented by thixocast molding. Even though the casting surface was noticeably improved as the cavity (the cavity existing inside the die casting) as before, and it became a relatively clean casting surface, the surface is still rough, and the design layer is still on the metal alloy molding. As described above, until the coating layer is coated, the workpiece is loaded, the boiling water is washed, the strong alkali is degreased, the heated is washed, the purified water is washed, the chemical conversion treatment (such as zinc phosphate coating), the purified water is washed, the dehydrated is dried and the dust is removed. Spray coating process, at least 8 steps to reach the painting process In addition, as a preliminary step of the subsequent painting process, a primer such as an epoxy resin must be applied to secure adhesion with various paints, and in most cases, an adhesive (putter) is used to ensure smoothness of the casting surface. ) It had to go through each step of treatment → sanding → dust removal.

As described above, in the coating of metal alloy moldings formed by means such as injection molding, die casting molding, thixocast molding, or the like represented by magnesium alloys, many steps leading up to the coating are complicated and Since the treatment cost is also high, it is necessary to improve the desired process. Therefore, an object of the present invention is to solve the above problems.

In order to achieve the above object, the present invention is an alkali degreasing treatment step of a metal alloy molding; Washing the metal alloy molding according to No. 1 with purified water or water or hot water; Dehydrating and drying the metal alloy molding according to No. 2; After carrying out the third step, a fuel compound containing a modifying compound containing a silane atom, a titanium atom, or an aluminum atom, each having a boiling point of 10 ° C to 105 ° C. Spraying the flame with respect to the surface of the metal alloy molding in whole or in part to perform an interfacial activation treatment so that the surface of the metal alloy molding has a wetness index (measurement temperature of 25 ° C.) of 73 dyn / cm or more; The high-strength coating method to the metal alloy molding, characterized in that it comprises a; coating step of applying a coating layer to be a design layer through the surface activation treatment step of the fourth substrate.

The metal alloy molding is preferably a high adhesion coating method, characterized in that the magnesia alloy, aluminum alloy or titanium alloy.

In another aspect, the present invention is another technical gist of a metal alloy molding coated with a high-tight coating method.

According to the present invention, the interfacial reforming performance of the interfacial reforming layer 301 shown in FIG. 3 is measured at a contact angle of 73 dyn / cm or more at a wet index (measurement temperature 25) when measured with a wet index reagent. Even in this case, the superhydrophilic effect can be reliably obtained at 10 ° (measurement temperature of 25 ° C.) or less, and the coating step, which becomes the design layer, which is a subsequent step in this interface modification state, is coated with the primer step omitted, and Mg-Al It can be confirmed that both the adhesion strength of the interface between the Zn-based (AZ91D) molded object and the coating layer and the coating appearance are excellent. In addition, even in the case of other aluminum-based or titanium-based alloy moldings, the interface modification apparatus can be used to modify the interface similarly to the magnesium alloy molding, and thus superhydrophilic effect can be exhibited.

In addition, using the magnesium-based alloy (Mg-Al-Zn-based: AZ91D) molded article formed by the thixocast molding method as an example, the flow from the pretreatment process of the coating process to the design layer formation will be described according to the present invention. , Alkali degreasing process → boiling water washing or purified water washing process → dehydration drying process → surface activation treatment process → vibration elimination process → primers? Coating process, and the process according to the conventional method: boiling water washing → strong alkali degreasing → boiling water washing → purified water washing → compared with chemical conversion treatment (e.g. zinc phosphate coating) → purified water washing → dehydration drying → dust removal → primer coating, the conventional process is eight steps and the process according to the present invention is five steps. The number of processes can be reduced by almost half, resulting in a significant reduction in manufacturing time and a reduction in manufacturing costs. Moreover, even in the coating process for forming a design layer, since the primer application process is unnecessary, it is possible to finish 1 coating as it is, and there is also an advantage in that the design layer can be directly formed, and the economic effect is large.

In addition, when the coating interface of various metal alloy moldings is interfacially modified by the above-described interfacial modifying apparatus, the surface of various metal alloy moldings, that is, the uneven surface of about tens of micrometers to several hundreds of micrometers formed on the casting surface, becomes superhydrophilic. Since the various paints formed thereafter flow to the concave-convex surface and are intimately tightly bonded to each other, the coating process, which is a subsequent process at the interface of various metal alloy moldings, can ensure sufficient adhesion in the state of the primary. There is an advantage.

SUMMARY OF THE INVENTION The present invention has been made with attention to the many processes and complexity of reaching the coating process of the above-described metal alloy molding, and by interfacially modifying the surface interface of the metal alloy molding, It is a fundamental improvement in many of the processes and complexity of the metal alloy molding up to the coating process.

First, the methodology regarding the interfacial modification of a metal alloy molding is described. 1 is a schematic diagram showing an outline of an interface reforming apparatus according to the present invention, and will be described based on the schematic diagram.

The interfacial modifier 100 is an interfacial modifier compound containing a silane atom, a titanium atom, or an aluminum atom, and includes an alkyl silane compound, an alkoxy silane compound, a siloxane compound, a silazane compound, an alkyl titanium compound, an alkoxy titanium compound, and an alkyl aluminum. A modifier compound storage tank 102 for storing the interfacial modifier compound 101 selected from the group consisting of a compound and an alkoxy aluminum compound, and heating for vaporizing the interfacial modifier compound 101 in the modifier compound storage tank 102. Supplying means (103), a fuel gas storage tank (106) for storing fuel gas, such as propane gas, LPG gas, and air for conveying combustion air and the interface modifier compound of the fuel gas; Compressed air source 107, interfacial modifier compound 101 vaporized by heating means 103 and the fuel gas storage tank It is composed of a feed 105 for transferring the air and fuel gas (106) the compressed air source 107 to the minute section (burner) 104. In addition, the transfer path 105 includes a sub mixer 108 for mixing the vaporized interfacial modifier compound 101 and the air of the compressed air source 107, a mixed gas of the vaporized interfacial modifier compound and air, The main mixer 109 for uniformly mixing the fuel gas sent from the fuel gas storage tank 106 is provided. In addition, the discharge flow rate of each of the modifier compound storage tank 102 for storing the interfacial modifier compound 101, the compressed air source 107 for supplying air, and the fuel gas storage tank 106 is controlled for each discharge flow rate. Flow rate regulating valves 110, 111, 112 with flowmeters are formed to constitute the interface reforming apparatus 100. Next, each said main structural member (part) is demonstrated in detail.

[Storage tank for interfacial modifier compound]

As shown in FIG. 1, a heating means 103 such as a heating heater is provided at the lower portion of the interfacial modifier compound storage tank 102, and the interfacial modifier compound 101 which is liquid at room temperature and atmospheric pressure is vaporized. It is configured to be. The heating means 103 is controlled by a CPU (not shown). That is, the CPU is electrically connected to each sensor such as a liquid amount sensor of the interface modifier compound, a liquid temperature sensor, and the like, and controls the heating means so that the liquid amount and liquid temperature of the interface modifier compound fall within a prescribed range. .

In the present invention, examples of using a liquid-phase interfacial modified compound are given, but a gas or a solid compound may also be used. In the case of using a gaseous interfacial modifier compound, it is not necessary to provide a heater in the storage tank 102 for the interfacial modifier compound. Instead, it is preferable to provide flow rate adjusting means such as a pressure regulating valve. In addition, in the case of using the interface modifier compound in the solid form, for example, the solid form compound may be dissolved in a solvent or melted by heat to pass through the liquid transport pipe piped from the storage tank of the present embodiment to the vicinity of the flame of the burner. Interfacial modification can be carried out by direct transfer into the burner.

`` Transfer department ''

The conveying section 105 is typically a "pipe" structure, as shown in Figure 1, the combustion air supplied from the compressed air source 107 and the vaporized interface sent from the modifier compound storage tank 102 A main mixer for uniformly mixing the submixer 108 for mixing a modifier compound, the mixed gas mixed by the submixer 108, and the fuel gas discharged from the storage tank 106 of the fuel gas ( 109 is installed.

`` Burner ''

As illustrated in FIG. 1, the injection unit (burner) 104 is a surface to be reformed on the flame 113 obtained by burning the combustion gas sent through the transfer unit 105 (modified surface). It sprays on (not shown) and interface-modifies a to-be-modified surface. And the state of the flame 113, the flow rate of the vaporized interfacial modifier compound 101, the amount of combustion air sent from the compressed air source 107 and the fuel gas sent from the fuel gas storage tank 106 Each can be optimally adjusted by adjusting the opening degree of the flowmeter with flowmeter 110, 111, 112 provided with each gas flow path. Moreover, the kind of burner is not specifically limited, For example, any of a premixed burner, a diffusion burner, a partial premixed burner, a spray burner, and an evaporation burner may be sufficient. Moreover, also in the form of a burner, it does not restrict | limit in particular.

The interfacial modifier compound is not particularly limited as long as it is a compound containing a silane atom, a titanium atom or an aluminum atom and can burn in a flame of a general gas burner. In view of the availability and ease of handling, for example, an alkylsilane compound, an alkoxysilane compound, a siloxane compound, a silazane compound, an alkyl titanium compound, an alkoxy titanium compound, an alkyl aluminum compound and an alkoxy aluminum compound It is preferred that it is at least one compound selected from the group.

Suitable examples of the alkylsilane compound include methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, tetraethylsilane, dimethyl dichlorosilane, dimethyl diphenylsilane, diethyl dichlorosilane, diethyl diphenylsilane, methyltrichlorosilane, Substituents such as monosilane compounds having substituents such as methyltriphenylsilane and dimethyldiethylsilane, disilane compounds having substituents such as hexamethyl disilane, hexaethyldisilane and chloroheptamethyldisilane, and octamethyltrisilane The trisilane compound etc. which it has are mentioned.

Suitable examples of the alkoxysilane compound include methoxysilane, dimethoxysilane, trimethoxysilane, tetramethoxysilane, ethoxysilane, diethoxysilane, triethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyl Dimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dichlorodimethoxysilane, dichlorodiethoxysilane, diphenyl dimethoxy One kind single or two types or more combinations, such as a methoxysilane, diphenyl diethoxysilane, trichloromethoxysilane, trichloroethoxysilane, triphenylmethoxysilane, and triphenylethoxysilane, are mentioned.

Suitable examples of the siloxane compound include tetramethyl disiloxane, pentamethyl disiloxane, hexamethyl disiloxane, octamethyl trisiloxane, hexamethyl cyclo trisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclo pentasiloxane, and dodecamethyl cyclohexasiloxane. Etc. can be mentioned.

Preferred examples of the silazane compound include hexamethyl disilazane and the like. Moreover, tetramethyl titanium, tetraethyl titanium, tetrapropyl titanium, etc. are mentioned as a suitable example of an alkyl titanium compound. Suitable examples of the alkoxy titanium compound include titanium methoxide and titanium ethoxide. Preferable examples of the alkyl aluminum compound include trimethyl aluminum, triethyl aluminum, tripropyl aluminum, and the like. Suitable examples of the alkoxy aluminum compound include aluminum methoxide, aluminum ethoxide and the like. These compounds may be used alone or in combination.

Among the above suitable examples, the silane compound, the alkoxysilane compound, the siloxane compound and the silazane compound are very preferable in view of easy handling, easy vaporization, and easy availability.

Next, a magnesium-based alloy molding formed by thixocasting a magnesium alloy: Mg-Al-Zn system (AZ91D) using the above-described interfacial reforming apparatus is used. How the modified surface of the magnesium-based alloy molding is modified based on FIG.

FIG. 2 schematically shows an enlarged cross-sectional view of a magnesium-based alloy molding molded by a thixocast molding method, for explaining the state of the casting surface. In FIG. 2, reference numeral 201 denotes an Mg-Al-Zn-based (AZ91D) molded product, and when the surface of the molded product is microscopically observed, unevennesses 202 and 203 having a size of several tens of micrometers to several hundreds of micrometers are noticeable. Even in the thixo-casting molding method in which the casting surface is relatively smooth in the metal alloy molding method, in order to coat the coating layer as a design layer on the surface of the casting, in the past, 'hot water washing → strong alkali degreasing → heating washing → purifying water washing → Mars ( Chemical conversion treatment (such as zinc phosphate coating) → purified water washing → dehydration drying → vibration damping '', and if this step is omitted, the adhesion between the Mg-Al-Zn-based (AZ91D) molding and the coating layer Since it is not secured, it has been recognized as an essential process that must be performed to secure adhesion.

However, in modifying the interface between the Mg-Al-Zn-based (AZ91D) molding and the coating layer using the interface modification apparatus shown in FIG. 1, the Mg-Al-Zn-based (AZ91D) molding is approximately The degreasing treatment is first performed in an alkaline solution, and then dehydration drying is finished, and then the same Mg-Al- is used as the interface modifier shown in FIG. 1 (using a silane compound-based interface modifier compound as the interface modifier compound). When the surface of the Zn-based (AZ91D) molding is interfacially modified, an enlarged cross section of the magnesium-based alloy molding as shown in FIG. 2 is shown in FIG. 3, for example, a silicate-based interfacial modified layer 301 having a thickness of several nm to several tens of nm. ) Is formed.

Let's look at a specific embodiment below.

A case of a mobile phone was obtained by a thixocast molding method in a magnesium alloy (Mg-Al-Zn system: AZ91D). The case was subjected to pretreatment of design layer formation via the process described below.

(1) pretreatment process

Work input → weak alkali degreasing (1 minute) → washing (1 minute) → dehydration drying (1 minute) → surface activation treatment (2 seconds) In addition, the modifier compound in the surface activation treatment uses hexamethyldisiloxane, and flames Propane-GAS was used as fuel GAS for processing.

(2) design layer formation process

Subsequently, the design layer was formed for the case of the mobile telephone which completed the said preprocessing process through the process described below.

Work input → vibration damping (2 seconds) → prime spray spray: average film thickness (25 μm), (10 seconds): thermosetting paint (2-component urethane resin: Ishimart Japan Japan product: IMS-100) → setting ( Room temperature: 10 minutes) → curing drying (70 ° C. × 30 minutes) → cooling (5 minutes) → work taking out.

(3) coating film appearance

The appearance of the coating film can be completed very smoothly with a primerless coating 1, and there are no problems in appearance.

(4) coating film properties

Item result Remarks Coating appearance ◎ Rough surfaces, pinholes, sags, and stains Hardness 2H Pencil Hardness, Mitsubishi Uni Impact resistance ◎ Dupont, 500g, 20 ℃ Water resistance ◎ 400 ℃ × 240 hours Salt water spray resistance ◎ JIS-Z2371.240 Water discoloration resistance Exterior ◎ 55 ml x 4 hours, 2 ml dropwise ΔE 0.84 Alkali discoloration resistance Exterior ◎ 55 ° C x 4 hours, 2 ml dropwise 1 / 10N NaOH aqueous solution ΔE 0.53 Acid resistance discoloration Exterior ◎ 55 ° C x 4 hours, 2 ml dropwise 1 / 10N H ₂ SO ₄ ΔE 0.18 Oil resistance ◎ N-heptane, N-hexane 20 ° C x 24 hours Wax Resistant, Remover Products ◎ ST-7 45 ℃ × 10 minutes deposition Oil resistance ◎ Genuine gear oil, 0.3-0.5 ml dropping Internal synergism ◎ 50% aqueous solution, 0.3-0.5 ml dropping Wear resistance ◎ Stoke 100mm 500 round trip Engine oil resistance ◎ MS multi-grade engine oil 0.3 ~ 0.5ml dipped for 4 hours

1 is a schematic diagram of an interface reformer.

Figure 2 is an enlarged cross-sectional view of the magnesium-based alloy molding not subjected to the reforming according to the present invention.

Figure 3 is an enlarged cross-sectional view of the magnesium-based alloy molding when the surface modification according to the present invention.

<Description of Major Symbols in Drawing>

100: interfacial modifier 101: interfacial modifier compound

102: modifier compound storage tank 103: heating means

104: injection part (burner) 105: transfer path

106: fuel gas storage tank 107: compressed air source

108: sub mixer 109: main mixer

110, 111, 112: flow control valve with flow meter

113: flame 201: Mg-Al-Zn-based (AZ91D) moldings

202: unevenness 203: unevenness

301: interface modification layer

Claims (3)

A high adhesion coating method on a metal alloy molding which must at least pass each of the following steps. 1. Alkali degreasing treatment process of metal alloy moldings. 2. A step of washing the metal alloy molding according to No. 1 with purified water or water or hot water. 3. The process of dehydrating and drying the metal alloy molding of the said 2nd description. 4. A fuel containing a modifier compound having a boiling point of 10 ° C to 105 ° C with a reforming compound containing a silane atom, a titanium atom, or an aluminum atom after the step 3 above. A surface of the metal alloy molding is surface-activated by spraying a gas flame onto the surface of the metal alloy molding in whole or in part. 5. Coating process which coats the coating layer used as a design layer through the surface activation treatment process of the said 4th description. The method of claim 1, The metal alloy molding is a high adhesion coating method, characterized in that the magnesia alloy, aluminum alloy or titanium alloy. A metal alloy molded article coated with high adhesion by the high adhesion coating method according to any one of claims 1 and 2.

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