WO2007040284A1

WO2007040284A1 - Photoluminescent coating light alloy wheel and method for forming the coating

Info

Publication number: WO2007040284A1
Application number: PCT/JP2006/320139
Authority: WO
Inventors: Masahiro Baba; Toshio Nagata; Shin Moriya; Manish Mathur; Takahide Inoue
Original assignee: Hitachi Metals, Ltd.
Priority date: 2005-10-06
Filing date: 2006-10-06
Publication date: 2007-04-12

Abstract

This invention provides a photoluminescent coating light alloy wheel comprising a wheel substrate and a primer coating layer, an intermediate layer, a metallic layer, and a clear topcoating layer stacked in that order on the wheel substrate. The photoluminescent coating light alloy wheel is formed by providing a coating equipment comprising an apparatus for coating a primer coating material and a metallic coating material, a first oven for baking the primer coating material and the metallic coating material, an apparatus for coating a clear coating material, and a second oven for baking the clear coating material, and forming, on the wheel substrate, a primer coating layer formed of the primer coating material, an intermediate layer formed of the clear coating material, a metallic layer formed of the metallic coating material, and a clear topcoating layer formed of the clear coating material in that order.

Description

Specification

Glossy painted light alloy wheel and coating film forming method thereof

Technical field

TECHNICAL FIELD [0001] The present invention relates to a glitter-coated light alloy wheel based on an aluminum alloy or the like that has been provided with a metallic-like glitter coating, and a coating film forming method thereof, and more particularly The present invention relates to a light-paintable light alloy wheel and a method for forming a coating film thereof.

Background art

[0002] Light alloy wheels for automobile parts are provided with a multi-layer coating in order to impart a high quality appearance. As such multi-layer coating, for example, as described in JP-A-5-209141, a primer layer composed of an epoxy-polyester hybrid powder coating, a base coat layer composed of an acrylic solid metallic coating, and an acrylic solid coating. There is a three-layer coating consisting of a clear coat layer. The line that forms this three-layer coating on a light alloy wheel consists of a device for applying primer powder to the wheel base, a device for spraying color base paint, the first furnace for baking color base paint, and spraying clear paint. It has a device for painting and a second furnace for baking clear paint.

[0003] Recently, in order to enhance the texture of the coating film, metallic silver coating (brilliant coating) using a bright pigment reminiscent of a polished surface of metal has been applied. Metallic silver paint is required to have a high-density feeling that does not give the glare of grain of the conventional Syno-Lever metallic, and a shading that changes depending on the viewing direction. As a glitter paint satisfying such requirements, vapor deposited aluminum flakes having a thickness of 0.1 μπι or less are dispersed, but there is a problem that the power of metallic paint is very expensive.

[0004] Multilayer coating applied to light alloy wheels is not limited to metallic silver coating, but has a problem of poor appearance. Appearance defects are mainly due to irregularities on the skin appearing on the surface of the underlayer. If an appearance defect is found, it needs to be reworked, resulting in high costs. For this reason, inspection is performed at the time when the underlayer is applied, and the surface of the underlayer is smoothed manually by using a polishing machine or a sandpaper. However, if the lower layer or wheel base is exposed by polishing, it is necessary to repaint the underlayer. [0005] For example, a metallic silver coating described in Japanese Patent Application Laid-Open No. 2000-140756 has four types: an aluminum wheel, a powder primer layer, a color base coat, a glossy coating containing an aluminum flake pigment, and a clear coat. Although it has a layered structure, the primer layer may be exposed when a defective part that is not only high in appearance defects due to the wheel base is repaired, but it may be necessary to repaint the color base coat. In order to form this four-layered metallic silver coating, it is necessary to add one coating unit and one baking furnace to the three-layer coating line, which increases costs.

[0006] In order to avoid an increase in the number of painting lines, a three-layer coating facility has been improved to provide a four-layer coating facility. For example, the painting facility 30 shown in FIG. 5 has a sub-transport path 26 that connects the outlet of the first furnace 34a to the inlet of the first painting unit 33a. When this coating equipment 30 is used to form a glitter coating with a four-layer structure on the wheel base 1, the wheel base 1 passes through the first furnace 34a twice, but the second furnace 34b passes only once. do not do. For this reason, the second furnace 34b has a time zone during which no wheel is conveyed. That is, the coating process is performed semi-batch or intermittently rather than continuously. While the wheel circulates through the first paint unit 33a and the first furnace 34a, the wheel is not transported to the second furnace 34b, so it is transported to the second furnace 34b first after the metallic paint is completed. The temperature received by the wheel group to be received is not the same as the temperature received by the wheel group after being continuously conveyed. This is because when the first wheel group is transported to the second furnace 34b, the temperature in the second furnace 34b suddenly decreases. Because it has risen and stabilized. As a result, there arises a problem that the adhesion of the glitter coating cannot be stably obtained. The processing machine 27 performs a cutting process such as a rim on the wheel on which the clear top coat layer 14 is formed.

[0007] In order to keep the temperature of the second furnace constant, the painting facility 20 shown in Fig. 3 has a sub-transport path 25 between the outlet of the second furnace 24b and the inlet of the first painting unit 23a. Have. The first coating unit 23a and the first furnace 24a perform the formation and baking of the color base layer and the metallic layer, and the second coating unit 23b and the second furnace 24b perform the formation and baking of the topcoat layer. Do. However, in the painting facility 20, the wheel 1 passes through the second furnace 24b for the first time without baking, and the second time for the clear topcoat layer 14 for baking. One base layer l ib is subjected to a large thermal load, especially during the first pass. As a result, 1 lb of the color base layer is denatured and the adhesion of the coating is reduced.

Disclosure of the invention

Problems to be solved by the invention

[0008] Accordingly, the object of the present invention is to provide a glossy coating having such characteristics by utilizing a coating film with good coating adhesion and uneven quality, a glittering coating light alloy wheel, and an existing three-layer coating facility. It is to provide a method of forming a light alloy wheel.

Means for solving the problem

[0009] As a result of intensive studies in view of the above object, the present inventors have provided an intermediate layer between the underlayer and the metallic layer. It was discovered that the base layer was not exposed, the color base coating film was thermally protected even in the post-baking process, and a high-quality glitter coating film could be formed even in a three-layer coating facility. .

That is, the glitter coated light alloy wheel of the present invention is characterized by having an underlayer, an intermediate layer, a metallic layer, and a clear topcoat layer in this order on a wheel base.

[0011] The intermediate layer is preferably a resin layer having a thickness of 5 to 100 / m. The intermediate layer is preferably made of a paint containing no pigment, like the clear topcoat layer.

[0012] The underlayer preferably comprises a primer layer and / or a color base layer. The primer layer is preferably made of an epoxy-based or epoxy'polyester-based powder coating.

[0013] The metallic layer preferably has a thickness of 10 zm or less. It is preferable that metal flakes having a thickness of 1 to 50 nm and an aspect ratio of 300 to 800 are dispersed in the metallic layer.

[0014] It is preferable that the glitter-coated light alloy wheel of the present invention is painted on the skin portion.

[0015] The method of the present invention for forming a glittering coating film on a light alloy wheel includes an apparatus for applying a base paint and a metallic paint, a first furnace for baking the base paint and the metallic paint, and applying a clear paint. Using a coating apparatus having a second furnace for baking the clear paint, a base layer made of the base paint on the wheel base, and the clear paint An intermediate layer, a metallic layer made of the metallic paint, and a taree topcoat layer made of the clear paint are formed in this order.

The base paint is preferably a primer paint and / or a color base paint. When the underlayer is composed of a primer layer and a color base layer, it is preferable to apply the primer coating and the color base paint by another coating facility.

The invention's effect

[0017] Since the irregularities of the wheel base appearing on the surface of the underlayer are almost concealed by the intermediate layer, the incidence of appearance defects is significantly reduced, and even if appearance defects are found before forming the metallic layer, Polishing or the like can be performed without damaging the underlayer. In addition, the intermediate layer prevents the hydrofluoric acid contained in commercially available wheel cleaners from penetrating into the base layer, so that the color of the base layer does not become uneven.

[0018] In the method of the present invention, the existing three-layer coating equipment can be used as it is, so that the coating cost can be kept low. In addition, even if it passes through a high temperature clear paint baking oven, the intermediate layer does not apply a thermal load to the underlayer, so the glitter coating has good adhesion to the light alloy wheel. In addition, since light alloy wheels are frequently transported to the furnace for baking the clear paint for the intermediate layer and top coat, the temperature of the clear paint baking furnace does not vary from wheel to wheel, and the glitter paint light with stable quality is light. Can manufacture alloy wheels Brief description of the drawings

FIG. 1 is a cross-sectional view schematically showing a five-layer coating film of a glitter coated light alloy wheel of the present invention.

FIG. 2 is a cross-sectional view schematically showing a four-layer coating film of the glitter-coated light alloy wheel of the present invention.

FIG. 3 is a plan view schematically showing coating equipment used in the coating film forming method of the present invention.

FIG. 4 is a flowchart showing each step of the glittering coating film forming method of the present invention.

FIG. 5 is a plan view schematically showing a conventional painting facility.

FIG. 6 is a cross-sectional view schematically showing a four-layer coating film of a conventional glitter-coated light alloy wheel. BEST MODE FOR CARRYING OUT THE INVENTION

[0020] [1] Configuration

As shown in FIG. 1, a glittering light alloy wheel according to an embodiment of the present invention has a base layer 11 (primer layer 11a and color base layer l ib), an intermediate layer 12, a metallic layer in this order on a wheel substrate 1. It has a glittering coating film 10 comprising a layer 13 and a clear topcoat layer 14. Further, as shown in FIG. 2, the primer layer 11a may serve as the foundation layer 11 only.

[0021] (1) Wheel base

The wheel base body 1 made of an alloy such as Al or Mg may be formed by any method. For example, the wheel substrate 1 integrally formed by a low-pressure forging method can be used. Even if the glitter coating film 10 is applied to the skin portion of the wheel base 1, the intermediate layer 12 hides the uneven surface of the skin surface, so that the appearance defect is reduced and the color base layer l ib The need for repainting is reduced.

[0022] (2) Underlayer

The underlayer 11 consists of a primer layer 1 la and Z or a color base layer 1 lb. Preferably, the base layer 11 includes a primer layer 11a and a color base layer l ib in this order from the substrate side. If the primer layer 11a is only the primer layer 11a, the primer layer 11a can be colored. In order to increase the glitter, the color base layer 1 lb (or the colored primer layer 11a) is preferably a dark color such as black or amber.

[0023] When the underlayer is composed of only the primer layer 11a, it is preferable to form the primer layer 1la thick so that the wheel base 1 is not exposed by reworking. When concealing the wheel substrate 1 with the primer layer 1 la alone, the primer layer 11a is preferably dark. On the other hand, if the primer layer consists of a primer layer 1 la and a color base layer 1 lb, the primer layer 1 la is thicker than 40 μπι and the color base layer l ib is thinner than the primer layer 11a. 1 lb of color base layer may contain metal particles in a proportion of 20% by volume or less.

[0024] The primer paint is made of polyester, acrylic, epoxy or urethane resin. It is preferable to use an epoxy powder coating material [glycidinoate type (for example, bisphenol A type), glycidyl ester type, glycidylamine type, cyclic oxysilane type epoxy resin, etc.] having good adhesion to the wheel substrate. . A face with a cross-linking agent if necessary Add materials, curing agents, surface conditioners, etc.

[0025] A particularly preferred epoxy-based powder coating from the viewpoint of price and adhesion to the wheel substrate 1 is a darcidinole group / carboxynole group-crosslinked epoxy-polyester hybrid powder having an acid-terminated polyester resin as a curing agent. It is a paint. By baking an epoxy-polyester hybrid powder coating at a temperature of 150 to 180 ° C for 10 to 30 minutes, a smooth and strong polymer cross-linked coating is formed. When it is necessary to hide the unevenness of the hull skin of the wheel base body 1, the thickness of the primer layer 11a is preferably 40 to 200 μπι. Generally, electrostatic coating equipment is used for powder coating.

[0026] It is preferable to use a solvent-based paint containing an acrylic resin, polyester, epoxy resin or the like as the color base paint containing the pigment. The primer layer 1 la made of epoxy-polyester hybrid powder paint has a thermosetting acrylic resin-based color base coating (thermosetting acrylic resin, curing agent, pigment, etc. dissolved or dispersed in an organic solvent). Are preferably combined. In order to improve the working environment and reduce the cost of recovering organic solvents, high-solid color base paints (solid content concentration of 50% by volume or more) with a low proportion of organic solvents are preferred. A dark-colored color base paint is preferable because it gives a tint of steel. The pigments used in color base paints are organic pigments, inorganic pigments, carbon pigments (carbon black, graphite, etc.), metallic powders and the like. Additives such as antifouling pigments, ultraviolet absorbers, antioxidants, surface conditioners, antifouling agents and the like may be blended. The thickness of the color base layer is preferably 10 to 40 μm. In addition, the spray method is preferred as the color base paint application method.

[0027] (3) Intermediate layer

The intermediate layer 12 formed between the underlayer 11 and the metallic layer 13 smoothes the surface of the coating film, and when the metallic layer 13 is applied, the appearance defect due to unevenness is reduced, and expensive metallic coating can be repainted. Can reduce costs. In addition, even if an appearance defect occurs, scratches due to reworking are difficult to reach the underlayer, so that it is not necessary to repaint the underlayer 11.

[0028] The thickness of the intermediate layer 12 is preferably 5 μπι or more, and more preferably 10 μπι or more, in order to conceal the unevenness of the underlayer 11 and protect the underlayer 11 from reworking polishing. The overall film thickness becomes too thick The thickness of the intermediate layer 12 is preferably ΙΟΟ μ πι or less. A more preferred thickness is 10 to 40 μπι. Due to the thickness of the intermediate layer 12, the color base paint is not thermally damaged when passing through the furnace.

[0029] Since the incident light that has passed through the metallic layer 13 is reflected by the underlayer 11 and passes through the metallic layer 13 again and is emitted from the surface of the coating film, glitter is obtained, so the intermediate layer 12 is transparent. Is preferred. The intermediate layer 12 may be a semitransparent resin layer containing a slight amount of pigment, but a transparent resin layer containing no pigment is preferred. Further, when the cleaning agent containing hydrofluoric acid used by the user reaches the base layer 11, the wheel layer may be mottled. By providing the intermediate layer 12, intrusion of hydrofluoric acid can be prevented. This effect is even greater because resins that do not contain pigments have better chemical resistance.

The clear paint used for the intermediate layer 12 is preferably the same as the clear paint used for the clear topcoat layer 14. If the same paint is used, a separate painting unit is not required and manufacturing management is easy, so the painting cost can be reduced.

[0031] The clear paint for the intermediate layer 12 includes vehicles such as acrylic resin, polyamide resin, urethane resin, polyester resin, and epoxy resin, amino resins such as melamine resin and benzoguanamine resin, isophorone diisocyanate, and hexame. It contains isocyanates such as tylene diisocyanate, isocyanurates, or curing agents such as block bodies thereof. The intermediate layer coating material may be an organic solvent coating material, a powder coating material, and a water dispersion type or aqueous type aqueous coating material. A thickener, a curing agent, an ultraviolet absorber, an antioxidant, a surface conditioner, and the like may be added to the coating for the intermediate layer as long as the light transmittance is not impaired.

[0032] The thickness of the intermediate layer 12 is preferably 20 to 40 µm. The intermediate layer 12 can be formed by heat curing at 120 to 160 ° C. using, for example, an acrylic resin (main agent) and a melamine resin (curing agent). Instead of acrylic 'melanin paint, an intermediate layer with a thickness of 20-30 am obtained by thermosetting polyester' urethane paint at 60-100 ° C can also be used.

[0033] (4) Metallic layer

The metallic layer 13 is formed of a metallic paint containing metal flakes having a metallic appearance. The metal flakes are made of at least one selected from the group consisting of chromium, ananolium, nickel, and alloys thereof. Metal flakes are vapor deposited ribbons Crushed is preferred. The average thickness of metal flakes is preferably 1-90 nm, more preferably 1-50 nm. The average diameter of the metal flakes is preferably 2 to 70 zm, more preferably 3 to 50 zm. The aspect ratio (diameter / thickness) of metal flakes is preferably 30 or more, more preferably 300 to 800, and most preferably 400 to 700.

[0034] The metallic layer 13 preferably contains 20 vol% or more of metal flakes. The content of metal flakes is represented by the ratio of the total area of metal flakes to the area of the entire coating film in the electron micrograph of the metallic layer. The thickness of the metallic layer 13 is preferably 10 μm or less, more preferably 0.05 to 10 μm, and most preferably 0 · 1 to 3 μπι. If the thickness of the metallic layer 13 is less than 0.05 μπι, the glitter effect is insufficient, and even if it exceeds 10 / im, further improvement of the glitter effect cannot be obtained.

The light incident on the metallic layer 13 is reflected by the metal flakes. The portion without the metal flakes is transmitted, and the intermediate layer (clear layer) 12 thereunder is also transmitted and reflected by the color base layer l ib. Therefore, the glittering coating film 10 of the present invention has a metallic appearance reflecting the color tone of the color base layer ib.

[0036] Most metal flakes exist parallel to the coating surface. Aluminum flakes coated with a saturated fatty acid (eg stearic acid) or the like (leafed) are preferred because they are easily oriented in parallel with the coating film. The light reflected by the metal flakes parallel to the coating surface interferes with each other, giving a sense of light brightness.

[0037] As metal flakes, vapor-deposited aluminum flakes are preferred. Vapor-deposited aluminum flakes are obtained by vapor-depositing aluminum on the surface of a plastic film substrate and then crushing and dissolving and removing the substrate. A very thin vapor-deposited aluminum flake with an aspect ratio of 300 or more is oriented parallel to the coating surface. When used in combination with aluminum flakes and vapor deposition aluminum flakes, the glittering feeling is improved. Addition of ground aluminum flakes gives a unique design feeling.

[0038] It is preferable to add a dark color pigment to the metallic paint in order to improve the flip-flop property or to give a pleasant silver tone or a high-grade titanium alloy tone. Dark pigments are black or dark brown or blue inorganic or organic pigments. For example, carbon black, lamp black, bone black, graphite, magnetite, hematite (brown), copper • Black pigments such as chrome black, cobanoleto black and copper 'manganese' iron black, inorganic blue pigments such as ultramarine, bitumen and cobalt blue, and organic blue pigments such as phthalocyan blue. In addition, yellow pigments such as yellow lead, yellow iron oxide, yellow LiFeO, and yellow titanium oxide powder can be used.

[0039] The average particle size of the amber pigment is preferably 300 nm or less. If it exceeds 300 nm, light is blocked by the amber pigment and does not reach the underlayer 11. Since the light must be reflected by the dark color base layer l ib, the average particle size of the amber pigment should be less than 300 nm.

[0040] (5) Clear top coat layer

The clear topcoat layer 14 can be formed of an organic solvent-based clear paint or a powder-based clear paint. As the clear paint, an acrylic paint excellent in transparency, gloss, weather resistance and the like is preferable. For example, an organic solvent acrylic paint having a solid content of about 40 to 50% by mass is preferred. The acrylic paint contains a thermosetting acrylic resin obtained by solution polymerization of an acrylic monomer and a functional monomer having an epoxy group, a carboxyl group, a hydroxyl group, or the like. The curing agent is preferably melamines.

[0041] [2] Manufacturing method

In order to form a glitter coating on the light alloy wheel, as shown in Fig. 3, along the main transport path 22, the first coating unit 23a, which can switch between color base coating and metallic coating, color base coating and metallic coating The first furnace 24a for baking the paint, the second coating unit 23b for coating the clear paint for the intermediate layer and the top coat, and the second furnace 24b for baking the clear paint are sequentially provided. A three-layer coating facility is used in which a sub-transport path 25 is provided between the outlet of the furnace 24b and the inlet of the first coating unit 23a. A unit 21 that performs primer coating on the wheel base 1 is provided upstream of the first coating unit 23a.

[0042] As shown in FIG. 4, the primer layer 11a is applied to the wheel base body 1 by the unit 21 and baked (step 1). The wheel base body 1 having the primer layer 11a is moved along the main transport path 22 in the first direction. It is transported to the painting unit 23a, where it is painted by spraying color base paint (step 2). After the color base paint was baked in the first furnace 24a (step 3), the wheel base 1 was transported along the main transport path 22 to the second coating unit 23b where the intermediate layer clear paint was sprayed, etc. Paint (process 4), then bake clear paint for intermediate layer in second oven 24b (Step 5).

[0043] In the conventional three-layer coating equipment, as shown in FIG. 5, the wheel base 1 is transported to the processing machine 27 after the intermediate layer 12 is formed, and a necessary portion such as a rim is cut by a lathe process or the like. In the present invention, the wheel base 1 is returned to the first coating unit 23 a along the sub-transport path 25.

[0044] The first paint unit 23a is coated with a metallic paint by spraying or the like (step 6). After baking the metallic paint in the first furnace 24a (step 7), the wheel base 1 is transported along the main transport path 22 to the second coating unit 23b, where the top coat clear paint is sprayed. Paint with a brush (process 8) and bake in the second furnace 24b (process 9). In this way, a glitter coating film 10 having a four-layer structure is formed on the wheel substrate 1. In this painting facility, since the wheel 1 frequently passes through the second furnace 24b in which the clear paint for the intermediate layer and the top coat is baked, the second furnace 24b can maintain a steady state and there is no quality variation. The ability to form a glitter coating 10 is possible.

[0045] The first furnace 24a for baking the color base paint and the metallic paint preferably has a lower temperature than the second furnace 24b for baking the clear paint. Specifically, the first furnace 24a is 100 to 130. . C and the second furnace 24b is preferably 130-160 ° C.

In the three-layer coating facility 20 shown in FIG. 3, the wheel 1 passes through the second furnace 24b without baking for the first time, and for the second time for baking the clear topcoat layer 14. In this case, without the intermediate layer 12, the color base layer ib baked at a low temperature (100 to 130 ° C.) is subjected to a large thermal load especially during the first pass. However, the intermediate layer 12 serves as a thermal NOR and can prevent the color base layer l ib from being subjected to a thermal load. For this reason, even if it passes through the second furnace 24b twice, the color base layer ib is not modified and the adhesion of the coating film is not lowered.

[0047] The clear topcoat layer 14 is preferably formed to a thickness of 10 to 40 µm by applying it to the surface of the metallic layer 13 and then baking at a temperature of 130 to 180 ° C.

[0048] The surface of the wheel base 1 is preferably subjected to pretreatment comprising alkali degreasing, pickling and chemical conversion treatment before providing the primer layer 11a. In the chemical conversion treatment, in addition to the chromate chemical conversion treatment solution containing chromium chromate or chromium phosphate, a non-chromium chemical conversion treatment solution using titanic acid or dinoleconic acid can be used. Is preferred. The conversion coating has a thickness of 3 mg / m ² or more (preferably 5 to 20 mg / m ² ).

[0049] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

[0050] Example 1

A wheel substrate 1 integrally made of A 铸 Si-Mg alloy (equivalent to JIS AC4CH) at low pressure was pretreated by alkaline degreasing, chromate treatment, washing with pure water and drying. Epoxy polyester powder coating (manufactured by Nippon Paint Co., Ltd.) is electrostatically coated to a thickness of about 100 μm on the entire surface of the wheel base 1 including the hull skin, and at a temperature of 150 to 180 ° C. Baking for ~ 60 minutes formed primer layer 11a. Black thermosetting acrylic melamine paint (“AS70 Black Base” manufactured by Nippon Paint Co., Ltd.) is sprayed with a spray gun to a film thickness of 20 μm and baked at 100 to 130 ° C for 10 to 30 minutes. The color base layer l ib was formed. The primer layer 1 la and the color base layer 1 lb form an underlayer 11. As a result of the appearance inspection of the underlayer 11, it was found that the unevenness appearing on the surface of the underlayer 11 was about 20% of the entire hull skin of the wheel. On the color base layer l ib, an organic solvent-based thermosetting acrylic clear paint (manufactured by Nippon Paint Co., Ltd.) is sprayed with a spray gun to a film thickness of 25 μm, and the temperature is 130 to 160 ° C. The intermediate layer 12 was formed by baking.

[0051] As a result of the appearance inspection of the intermediate layer 12, the irregularities appearing on the surface are observed on the entire skin of the light alloy wheel.

It was reduced to 10% or less. When the intermediate layer 12 was polished with sandpaper of # 600 to 1200 to remove the concaves and convexes, the underlayer 11 was not exposed. When the metallic layer 13 and the clear topcoat layer 14 were formed on the intermediate layer 12 as they were, a smooth and excellent coating film having excellent glitter was obtained.

[0052] Comparative Example 1

In the same manner as in Example 1, the base layer 11 composed of the primer layer 11a and the color base layer lib was formed on the aluminum wheel base 1. Polishing the underlayer 11 with # 600-1200 sandpaper took more than twice as much time as Example 1. In addition, the color base layer “lib” partially disappeared by reworking, and the primer layer 11a might be exposed, and the base layer 11 had to be repainted. [0053] Example 2

After the same pretreatment as in Example 1 on a wheel base 1 (2-piece aluminum wheel with disk surface low-pressure forged and rim part rolled) made of A 卜 Si-Mg alloy (equivalent to JIS AC4CH) The entire surface of the wheel base 1, including the skin, is electrostatically coated with a dark-colored epoxy 'polyester powder coating (manufactured by Nippon Paint Co., Ltd.) to a thickness of approximately 110 am, and a temperature of 150 to 180 ° C. Was baked for 30 to 60 minutes to form a primer layer 11a. As a result of the appearance inspection of the primer layer 11a, it was found that the unevenness appearing on the surface of the primer layer 11a was about 23% of the entire hull skin of the wheel. On the primer layer 11a, the same intermediate layer 12 as in Example 1 was formed except that the film thickness was 20 μπι.

As a result of the appearance inspection, the irregularities appearing on the surface of the intermediate layer 12 were reduced to about 11% of the entire hull skin of the wheel. When the surface of the intermediate layer 12 was polished and the irregularities were removed in the same manner as in Example 1, the primer layer 11a was not exposed. When the metallic layer 13 and the tarrier top coat layer 14 were formed on the intermediate layer 12 as they were, a smooth and excellent coating film having excellent glitter was obtained.

[0055] Comparative Example 2

The primer layer 11a was formed on the wheel base 1 in the same manner as in Example 2. When the primer layer 11a was polished with sand paper of # 600 to 1200, it took more than twice as much time as in Example 1.

[0056] Example 3

Using the coating equipment 10 shown in FIG. 3, according to the flowchart shown in FIG. 4, the wheel substrate 1 made of an A 卜 Si_Mg alloy pretreated in the same manner as in Example 1 is applied to the five layers shown in FIG. A glittering coating film 10 having a structure was formed. First, with the primer layer forming device 21, electrostatic coating of epoxy 'polyester-no-iburd powder paint (manufactured by Nippon Paint Co., Ltd.) to a thickness of about lOO zm and 30-60 at a temperature of 150-180 ° C Baked for minutes (step 1). Wheel base 1 is transported to the first coating unit 23a, and a black high-solid thermosetting acrylic melamine-based paint (“AS70 Black Base” manufactured by Nippon Paint Co., Ltd.) is applied on the primer layer 11a. Was sprayed with a spray gun to a thickness of 30 μm (process 2). Thereafter, the wheel base 1 was transported to the first furnace 24a and baked at 100 to 130 ° C. for 10 to 30 minutes to form a color base layer lib (step 3). The wheel base 1 is transported to the coating unit 23b to apply tarrier paint, and organic solvent A thermosetting acrylic clear paint (manufactured by Nippon Paint Co., Ltd.) was sprayed with a spray gun to a film thickness of 30 μm (step 4). The wheel base 1 having the clear paint was conveyed to the second furnace 24b and baked at 130 to 160 ° C. to form the intermediate layer 12 (step 5).

[0057] The wheel base 1 was returned to the first coating unit 23a by the sub-transport path 25. 15 parts by mass of vapor-deposited aluminum flakes (average thickness: 17 nm, average particle size: 14 zm), 10 parts by mass of carbon black (average particle size: 20 nm), 100 parts by mass of polyester binder resin, and 100 masses Part of the xylene metallic paint was sprayed with a spray gun to a film thickness of 0.5 μm (step 6). Next, the wheel base 1 was conveyed to the first furnace 24a and baked at 100 to 130 ° C. for 20 minutes to form a metallic layer 13 having a thickness of 0.5 / m (step 7). The wheel base 1 was transported to the second coating unit 23b where clear paint was applied, and the same high solid thermosetting acrylic clear paint as the intermediate layer 12 was sprayed with a spray gun to a film thickness of 30 / m. (Step 8). The wheel substrate 1 to which the clear paint was applied was baked at 130 to 160 ° C. in the second furnace 24b to form a clear topcoat layer 14 (step 9).

[0058] When the clear topcoat layer 14 is baked, if the intermediate layer 12 is not present, the underlayer (primer layer 11a and color base layer ib) is subjected to a thermal load, and sufficient weather resistance and coating film adhesion are obtained. Furthermore, cracks and peeling occur in the coating film during the machining process.

[0059] Comparative Example 3

A glittering coating film 10 was formed in the same manner as in Example 3 except that the coating equipment 20 in FIG. 3 was used and the intermediate layer 12 was not provided. As a result, the color base layer l ib was baked in the first and second furnaces 24a and 24b, so that the coating film characteristics changed and the adhesion with the metallic base layer 13 was poor.

Claims

The scope of the claims

[1] A glittering light alloy wheel characterized by comprising an underlayer, an intermediate layer, a metallic layer, and a clear topcoat layer in this order on a wheel substrate.

[2] The glitter-coated light alloy wheel according to claim 1, wherein the intermediate layer is a resin layer having a thickness of 5 to 100 / m2.

[3] The glitter-coated light alloy wheel according to claim 1 or 2, wherein the intermediate layer is made of a paint containing no pigment.

[4] The glitter-coated light alloy wheel according to any one of claims 1 to 3, wherein the base layer is composed of a primer layer and / or a color base layer.

[5] The glitter-coated light alloy wheel according to claim 4, wherein the primer layer is made of an epoxy-based or epoxy-polyester-based powder paint.

[6] The brightly painted light alloy wheel according to any one of claims 1 to 5, wherein the metallic layer has a thickness of 10 μπι or less, and a thickness force of 1 to 50 nm and an aspect ratio therein. A bright alloy light alloy wheel characterized in that 300 to 800 metal flakes are dispersed.

[7] The glitter-coated light alloy wheel according to any one of claims 1 to 6, wherein a paint is applied to a ridge portion.

[8] In a method for forming a glittering coating film on a light alloy wheel, an apparatus for applying a base paint and a metallic paint, a first furnace for baking the base paint and the metallic paint, and an apparatus for applying a tarrier paint And a coating facility having a second furnace for baking the clear paint, a base layer made of the base paint on the wheel base, an intermediate layer made of the clear paint, a metallic layer made of the metallic paint, and A method comprising sequentially forming a clear topcoat layer comprising the clear paint.

[9] The method for forming a glittering coating film on a light alloy wheel according to [8], wherein the base paint is a primer paint and / or a color base paint.

[10] The method for forming a glittering coating film on a light alloy wheel according to [9], wherein the primer coating and the color base coating are sequentially applied onto the wheel substrate. Method.

11. The method for forming a glittering coating film of a light alloy wheel according to claim 10, wherein the undercoat layer is composed of the primer paint layer and the color base paint layer, and the primer paint and the color base paint are applied by another coating facility. A method characterized by