JP4207266B2

JP4207266B2 - Powder coating method and apparatus

Info

Publication number: JP4207266B2
Application number: JP27549598A
Authority: JP
Inventors: 健児井尾
Original assignee: Aisin Seiki Co Ltd; Aisin Corp
Current assignee: Aisin Corp
Priority date: 1998-09-29
Filing date: 1998-09-29
Publication date: 2009-01-14
Anticipated expiration: 2018-09-29
Also published as: JP2000102750A

Description

【０００１】
【産業上の利用分野】
本発明は、塗膜の平滑性に優れた粉体塗装方法に関する。
【０００２】
【従来の技術】
自動車部品に限らず機械部品などの塗装は、外観向上や防錆性向上などの目的で頻繁に使用されている。これらの塗装をするにあたり現在注目されている技術に粉体塗装方法である。粉体塗装方法は、浮遊槽内に粉体粒子を吹上げ浮遊する粉体粒子に電荷を与え、浮遊槽内において電圧をかけつつ被塗装物を移動させて被塗装物の表面に粉体粒子を付着させるというものである。この方法は、従来の溶剤塗装や水溶性塗装に比較して、大気中に多く塗料を噴霧させることなく塗装ができるため塗料の飛散がなく塗料回収が容易でリサイクル性が良好であり、溶剤を使用しないため環境汚染の心配もないので注目されている技術である。
【０００３】
しかしながら、粉体塗装は、塗膜の平滑性が悪いため仕上がり外観が溶剤塗装などと比較して悪く、溶剤塗装と同等の仕上がり外観にするためには、溶剤塗装塗膜の１．５倍以上の約６０乃至８０ミクロン（μｍ）程度の塗膜を形成しなければならなかった。
【０００４】
そこで、粉体塗装の薄膜での塗膜の平滑性を向上させるため、特開平９−２０８８５５号公報に記載されたものがある。これは、粉体塗装に使用される平均粒子径が５乃至１５ミクロン、９０％累積粒子径が１５乃至２５ミクロン及び粒子形状が球状よりなるものである。
【０００５】
【発明が解決しようとする課題】
しかし、上記した粉体塗装では、粒子径を均一化及び微細化することが必要であり、これにより塗装する前工程が増えてしまい塗装費用が高くなってしまうという問題がある。
【０００６】
故に、本発明は、塗膜の平滑性に優れた薄膜の粉体塗装を低コストで行うことのできる粉体塗装法を提供することを、その技術的課題とするものである。
【０００７】
【課題を解決するための手段】
上記課題を解決するために請求項１の発明は、浮遊槽内に粉体粒子を吹上げ浮遊する粉体粒子に電荷を与え、浮遊槽内で被塗装物を移動させて被塗装物の表面に粉体粒子を付着させる粉体塗装方法において、浮遊槽内に、粉体粒子を吹上げる第一の吹き上げ手段と、該第一の吹き上げ手段より上方に上下方向でそれぞれ異なる位置に配置され、前記第一の吹き上げ手段で吹き上げられた粉体粒子にエアー圧を与える複数のエアー配管からなる第二の吹上げ手段とを備え、該第二の吹き上げ手段からのエアー圧を前記第一の吹き上げ手段で吹き上げられた粉体粒子に複数回与えることで、粉体粒子径の小さな重量の軽い粉体粒子ほど上方の層となるように粉体粒子径の異なる複数の層を前記浮遊槽内で形成するようにしたので、塗膜の平滑性を向上させるように粉体粒子径の異なる粉体粒子を最適に被塗装物に付着させることができる。
【０００８】
請求項２の発明によれば、被塗装物の塗装を行う浮遊槽と、浮遊槽内の下部に配置された多孔質板と、多孔質板上に供給される粉体粒子と、多孔質板下に配置され粉体粒子を浮遊槽内に吹き上げる第一の吹き上げ手段と、吹き上げられた粉体粒子に更にエアー圧を複数回与え、粉体粒子径の小さな重量の軽い粉体粒子ほど上方の層となるように前記第一の吹き上げ手段より上方に上下方向でそれぞれ異なる位置に配置される複数のエアー配管からなる第二の吹き上げ手段と、浮遊槽内を浮遊する粉体粒子に電荷を与える電極体と、浮遊槽内で被塗装物を移動させる移動装置と、粉体粒子を水平方向に流動させる塗装エアー配管とからなるので、塗膜の平滑性を向上させるように粉体粒子径の異なる粉体粒子を最適に被塗装物に付着させることができる。
この場合、第二の吹き上げ手段は、前記浮遊槽内の上部に配置される前記エアー配管ほど微弱なエアー圧を前記浮遊槽内に噴射すると良い。
【０００９】
【発明の実施の形態】
この出願の発明の実施の形態を図面に基づいて説明する。図１は本発明に係る粉体塗装装置の断面図、図２は本発明に係る粉体塗装方法により形成される塗膜の概念図である。
【００１０】
図１に示されるように、粉体塗装装置１は、被塗装物１１の塗装を行う浮遊槽２と、浮遊槽２内の下部に配置された多孔質板３と、多孔質板３上に供給される粉体粒子４と、多孔質板３の下に配置され粉体粒子４を浮遊槽２内に吹き上げる図示しない吹上げエアー供給装置に連通した吹上げエアー通路５と、吹き上げられた粉体粒子４に更にエアー圧を与えて粉体粒子径の小さな重量の軽い粉体粒子４ほど上方の層となるように粉体粒子径の異なる複数の層を形成する補助エアー配管６と、浮遊槽２内を浮遊する粉体粒子４に電荷を与える電極体１２と、浮遊槽２内で被塗装物１１を移動させる移動装置１０と、粉体粒子４を水平方向に流動させる塗装エアー配管１３とから構成される。
【００１１】
粉体粒子４は、例えばエポキシからなり、供給通路８から多孔質板３上に設置された容器１４内に供給され、容器１４に接続された振動装置７で振動を与えられることにより多孔質板３上に均等拡散し、凝集することを防止される。
【００１２】
まず、粉体粒子４は、多孔質板３を下方から上方へ通過するエアー通路５からのエアーにより、浮遊槽２内に吹き上げられる。このとき、エアー圧力は約０．２〜０．４ｋｇｆ／ｃｍ^２である。
【００１３】
次に、吹上げられた粉体粒子４は、エアー通路５からのエアーに第１の補助エアー配管６ａから若干浮遊槽２中心方向に傾斜して上方へ向って噴射されるエアーを合成することにより更に吹上げられる。増加されたエアー圧力は、例えば０．３〜１．５ｋｇｆ／ｃｍ^２の増加となっており、粉体粒子４中で粒子径が比較的大きく重量が重いものは然程上方へは吹上げられないで、後述する第２の補助エアー配管６ｂに到達せずに第１層を形成するようになる。第１層は、好適には粉体粒子４ａの平均粒子径が１０〜４５μｍで構成されると良く、前述したエアー圧力の範囲内で第１の補助エアー配管６ａのエアー圧力を設定すればよい。
【００１４】
更に、第２の補助エアー配管６ｂより上方に達した比較的粒子径の小さな重量が軽い粉体粒子４は、エアー通路５からのエアーに第２の補助エアー配管６ｂから若干浮遊槽２中心方向に傾斜して上方へ向って噴射されるエアーを合成することにより更に吹上げられ、第２層を形成する。第２層は、好適には粉体粒子４ｂの平均粒子径が３〜１５μｍで構成されると良い。なお、本実施の形態では第２の補助エアー配管６ｂのエアー圧力は、第１の補助エアー配管６ａと同等に設定している。当然、エアー通路５からのエアーは、第１の補助エアー配管６ａ付近よりも第２の補助エアー配管６ｂ付近の方が上方にあるため圧力が弱くなっているので、同程度の微弱なエアー圧力を合成したとしても、第２の補助エアー配管６ｂで吹上げられる粉体粒子４の粒子径及び重量より、第１の補助エアー配管６ａで吹上げられるそれの方が大きく重くなる。第２の補助エアー配管６ｂにより吹上げられ第２層を超えた粉体粒子４は、平均粒子径が１５μｍ以下のもので、徐々に補助エアー配管６と浮遊槽２の側壁との空間を下降して再度容器１４に入り、振動装置７からの振動により容器１４に均等拡散されて、エアー通路５からのエアーにより再度浮遊槽２内へ吹上げられる。
【００１５】
本実施の形態では、粉体粒子４の平均粒子径毎に分割した層を２層としたが、補助エアー配管６を多段に配置して、エアー圧力を各補助エアー配管毎に微弱に設定することで、より細かい粉体粒子４の平均粒子径の異なる多段の層を得ることも可能である。なお、多段の層を得るためには、粉体粒子４の粒子径及び重量等の関係より各補助エアー配管の間隔は、５００ｍｍ以下とした方がより良い。
【００１６】
浮遊槽２内に第１及び第２層を形成した粉体粒子４は、高電圧を発生可能な電圧装置９に接続され約−６０ＫＶをかけられた電極体１２で浮遊槽２内のエアーをイオナイズさせて水平方向に流動させることにより、静電気を帯びさせられて浮遊槽２内を水平方向に流動するエアーと一緒に流動する。また、塗装エアー配管１３から浮遊槽２内へ水平方向に噴射されるエアーにも粉体粒子４は、流動させられている。
【００１７】
被塗装物１１は、アース１５が接続された移動装置１０により、まず浮遊槽２内の第１層を通過させられ、浮遊槽２内を水平方向に移動する静電気を帯びた平均粒子径１０〜４５μｍの比較的大きく重い粉体粒子４ａが静電気による反発を起こしながら表面に略均一に付着する。第１層を通過した被塗装物１１は、次に第２層を通過させられ、浮遊槽２内を水平方向に移動する静電気を帯びた平均粒子径３〜１５μｍの比較的小さく軽い粉体粒子４ｂが静電気による反発を起こしながら、図２に示されるように、平均粒子径１０〜４５μｍの粉体粒子４ａが付着した表面に更に略均一に付着する。
【００１８】
他の実施の形態としては、次のようなものがある。
【００１９】
特に自動車の塗装には、耐食性及び耐候性が求められ、耐食性と密着性を兼ね備えたエポキシと耐候性を備えたアクリルとを、下層にエポキシ、上層にアクリルというように組み合わせることが望ましい。
【００２０】
そこで、浮遊槽２をエポキシとアクリルとが分割されるように仕切板などを設置し、先ずエポキシが入っている浮遊槽２に被塗装物１１を前述したような粉体粒子４の平均粒子径を制御した層に通過させてエポキシの塗膜を形成し、次にアクリルが入っている浮遊槽２に被塗装物１１を通過させてエポキシの塗膜の上層にアクリルの塗膜を形成するようにする。これにより、エポキシの塗膜が平滑性の高いものなるので、この塗膜に更に塗膜が形成するアクリルも同様に均一にエポキシの塗膜表面に付着して平滑性の高いものとなり、かつ、耐食性及び耐候性に優れた塗装が可能となる。
【００２１】
【発明の効果】
以上説明したように本発明に係る粉体塗装方法及びその装置は、粉体粒子を吹上げるエアーの制御という簡単な方法により平均粒子径の異なる複数の層を浮遊槽内に形成することができるので、塗膜の平滑性を向上させるように粉体粒子径の異なる粉体粒子を最適に被塗装物に付着させることができる。
【図面の簡単な説明】
【図１】本発明に係る粉体塗装装置の断面図。
【図２】本発明に係る粉体塗装方法により形成される塗膜の概念図。
【符号の説明】
１粉体塗装装置
２浮遊槽
３多孔質板
４粉体粒子
５吹上げエアー通路
６補助エアー配管
１０移動装置
１１被塗装物
１２電極体
１３塗装エアー配管[0001]
[Industrial application fields]
The present invention relates to a powder coating method having excellent coating film smoothness.
[0002]
[Prior art]
Coating of not only automobile parts but also machine parts is frequently used for the purpose of improving the appearance and improving rust prevention. A powder coating method is a technology that is currently attracting attention for these coatings. In the powder coating method, powder particles are blown up in a floating tank, electric charges are applied to the floating powder particles, and the object to be coated is moved while applying a voltage in the floating tank so that the powder particles are applied to the surface of the object to be coated Is attached. Compared to conventional solvent coating and water-soluble coating, this method can be applied without spraying a lot of paint in the atmosphere, so there is no scattering of paint, paint recovery is easy, and recyclability is good. Because it is not used, there is no concern about environmental pollution.
[0003]
However, powder coating is poor in smoothness of the coating film, so the finished appearance is poor compared to solvent coating, etc. In order to achieve a finished appearance equivalent to solvent coating, it is 1.5 times more than solvent coating film. A coating film of about 60 to 80 microns (μm) was required.
[0004]
In order to improve the smoothness of the coating film in the powder coating thin film, there is one described in JP-A-9-208855. This is an average particle size used for powder coating of 5 to 15 microns, a 90% cumulative particle size of 15 to 25 microns, and a spherical particle shape.
[0005]
[Problems to be solved by the invention]
However, in the above-described powder coating, it is necessary to make the particle diameter uniform and fine, and there is a problem that the pre-process for coating increases and the coating cost increases.
[0006]
Therefore, this invention makes it the technical subject to provide the powder coating method which can perform the powder coating of the thin film excellent in the smoothness of the coating film at low cost.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is directed to the surface of the object to be coated by supplying electric charge to the powder particles that are blown and suspended in the floating tank and moving the object to be coated in the floating tank. In the powder coating method of attaching the powder particles to the first blasting means for blowing up the powder particles in the floating tank, and arranged at different positions in the vertical direction above the first blowing means , And a second blowing means comprising a plurality of air pipes for applying an air pressure to the powder particles blown up by the first blowing means, and the air pressure from the second blowing means is increased by the first blowing up. By giving the powder particles blown up by the means a plurality of times, a plurality of layers having different powder particle diameters are formed in the floating tank so that the lighter powder particles having a smaller powder particle diameter become upper layers. Since it was formed, the smoothness of the coating film The different powder particles powder particle size can be optimally attached to the object to be coated so as to above.
[0008]
According to invention of Claim 2, the floating tank which coats a to-be-coated object, the porous board arrange | positioned in the lower part in a floating tank, the powder particle supplied on a porous board, and a porous board a first blow means blow up the powder particles are placed under the floating vessel, giving a plurality of further air pressure to the powder particles blown up times, above the higher lighter powder particles a small weight of the powder particle size Charge is applied to the second blowing means composed of a plurality of air pipes arranged at different positions in the vertical direction above the first blowing means so as to form a layer, and the powder particles floating in the floating tank Since it consists of an electrode body, a moving device for moving the object to be coated in the floating tank, and a coating air pipe for flowing the powder particles in the horizontal direction, the particle size of the powder particles is improved so as to improve the smoothness of the coating film. Optimum adhesion of different powder particles to the workpiece It can be.
In this case, the second blowing means may inject a weaker air pressure into the floating tank as the air pipe arranged at the upper part in the floating tank.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the invention of this application will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a powder coating apparatus according to the present invention, and FIG. 2 is a conceptual diagram of a coating film formed by the powder coating method according to the present invention.
[0010]
As shown in FIG. 1, the powder coating apparatus 1 includes a floating tank 2 that coats an object to be coated 11, a porous plate 3 disposed in the lower part of the floating tank 2, and a porous plate 3. Powder particles 4 to be supplied, blowing air passages 5 arranged below the porous plate 3 to blow the powder particles 4 into the floating tank 2 and communicated with a blowing air supply device (not shown), and the blown powder Auxiliary air pipe 6 for forming a plurality of layers having different powder particle diameters so that lighter weight powder particles 4 having a smaller powder particle diameter are provided by applying air pressure to body particles 4 and floating, and floating An electrode body 12 for applying an electric charge to the powder particles 4 floating in the tank 2, a moving device 10 for moving the object 11 to be coated in the floating tank 2, and a coating air pipe 13 for causing the powder particles 4 to flow in the horizontal direction. It consists of.
[0011]
The powder particles 4 are made of, for example, epoxy, and are supplied from a supply passage 8 into a container 14 installed on the porous plate 3 and are vibrated by a vibration device 7 connected to the container 14. 3 is uniformly diffused and prevented from agglomerating.
[0012]
First, the powder particles 4 are blown up into the floating tank 2 by air from an air passage 5 that passes through the porous plate 3 from below to above. At this time, the air pressure is about 0.2 to 0.4 kgf / cm ² .
[0013]
Next, the blown-up powder particles 4 synthesize the air jetted upward from the first auxiliary air pipe 6a to the air from the air passage 5 with a slight inclination toward the center of the floating tank 2. Is further blown up. The increased air pressure is, for example, an increase of 0.3 to 1.5 kgf / cm ² , and powder particles 4 having a relatively large particle size and a heavy weight are blown upwards. Therefore, the first layer is formed without reaching the second auxiliary air pipe 6b described later. The first layer preferably has an average particle diameter of 10 to 45 μm, and the air pressure of the first auxiliary air pipe 6a may be set within the aforementioned air pressure range. .
[0014]
Further, the powder particles 4 having a relatively small particle diameter and reaching the upper side from the second auxiliary air pipe 6b are slightly moved from the second auxiliary air pipe 6b toward the center of the floating tank 2 to the air from the air passage 5. The air is further blown up by synthesizing the air that is inclined upward and injected upward to form the second layer. The second layer preferably has an average particle diameter of the powder particles 4b of 3 to 15 μm. In the present embodiment, the air pressure of the second auxiliary air pipe 6b is set to be equal to that of the first auxiliary air pipe 6a. Naturally, the air from the air passage 5 is weaker because the pressure in the vicinity of the second auxiliary air pipe 6b is higher than that in the vicinity of the first auxiliary air pipe 6a. Even if synthesized, the particle size and weight of the powder particles 4 blown up by the second auxiliary air pipe 6b are larger and heavier than those blown up by the first auxiliary air pipe 6a. The powder particles 4 blown up by the second auxiliary air pipe 6b and exceeding the second layer have an average particle diameter of 15 μm or less, and gradually descend the space between the auxiliary air pipe 6 and the side wall of the floating tank 2. Then, it again enters the container 14, is evenly diffused into the container 14 by vibration from the vibration device 7, and is blown up again into the floating tank 2 by the air from the air passage 5.
[0015]
In the present embodiment, the layers divided for each average particle diameter of the powder particles 4 are two layers, but the auxiliary air pipes 6 are arranged in multiple stages, and the air pressure is set weak for each auxiliary air pipe. Thus, it is also possible to obtain a multi-stage layer having finer powder particles 4 having different average particle diameters. In order to obtain a multi-stage layer, it is better that the interval between the auxiliary air pipes is 500 mm or less because of the particle diameter and weight of the powder particles 4.
[0016]
The powder particles 4 in which the first and second layers are formed in the floating tank 2 are connected to a voltage device 9 capable of generating a high voltage, and the air in the floating tank 2 is evacuated by an electrode body 12 applied with about −60 KV. By ionizing and flowing in the horizontal direction, static electricity is generated and flows in the floating tank 2 together with air flowing in the horizontal direction. Further, the powder particles 4 are also caused to flow in the air jetted horizontally from the coating air pipe 13 into the floating tank 2.
[0017]
The object to be coated 11 is first passed through the first layer in the floating tank 2 by the moving device 10 to which the earth 15 is connected, and has an average particle diameter of 10 to 10 which is charged with static electricity moving in the horizontal direction in the floating tank 2. The relatively large and heavy powder particles 4a of 45 μm adhere substantially uniformly to the surface while causing repulsion due to static electricity. The object 11 to be coated that has passed through the first layer is then passed through the second layer, and is a relatively small and light powder particle having an average particle diameter of 3 to 15 μm charged with static electricity that moves horizontally in the floating tank 2. As shown in FIG. 2, while 4b is repelled by static electricity, the powder particles 4a having an average particle diameter of 10 to 45 μm adhere more uniformly to the surface.
[0018]
Other embodiments include the following.
[0019]
In particular, coating of automobiles requires corrosion resistance and weather resistance, and it is desirable to combine an epoxy having both corrosion resistance and adhesion and an acrylic having weather resistance, such as an epoxy in the lower layer and an acrylic in the upper layer.
[0020]
Therefore, a partition plate or the like is installed in the floating tank 2 so that epoxy and acrylic are divided. First, the average particle diameter of the powder particles 4 as described above is placed in the floating tank 2 containing the epoxy. Is passed through the controlled layer to form an epoxy coating, and then the article 11 is passed through the floating tank 2 containing acrylic to form an acrylic coating on top of the epoxy coating. To. As a result, since the epoxy coating film has high smoothness, the acrylic that the coating film further forms on this coating film also uniformly adheres to the epoxy coating surface and becomes highly smooth, and Coating with excellent corrosion resistance and weather resistance becomes possible.
[0021]
【The invention's effect】
As described above, the powder coating method and apparatus according to the present invention can form a plurality of layers having different average particle diameters in a floating tank by a simple method of controlling air that blows up powder particles. Therefore, powder particles having different powder particle diameters can be optimally attached to the object to be coated so as to improve the smoothness of the coating film.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a powder coating apparatus according to the present invention.
FIG. 2 is a conceptual diagram of a coating film formed by the powder coating method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Powder coating apparatus 2 Floating tank 3 Porous board 4 Powder particle 5 Blowing air passage 6 Auxiliary air piping 10 Moving apparatus 11 Object 12 Electrode body 13 Coating air piping

Claims

A powder coating method in which powder particles are blown up and floated in a floating tank, charges are applied to the powder particles, the object to be coated is moved in the floating tank, and the powder particles adhere to the surface of the object to be coated In
The first blowing means for blowing up the powder particles in the floating tank, and the powder blown up by the first blowing means , arranged at different positions in the vertical direction above the first blowing means. Second blowing means comprising a plurality of air pipes for applying air pressure to the body particles, and the air pressure from the second blowing means is applied to the powder particles blown up by the first blowing means a plurality of times. by giving, powder, characterized in that a plurality of layers of different powder particle size such that the smaller the weight of light powder particles as the upper layer of the powder particle diameter so as to form at the floating vessel Body painting method.

A floating tank for coating an object to be coated, a porous plate disposed in the lower part of the floating tank, powder particles supplied on the porous plate, and the powder disposed under the porous plate a first blow means blow up the body particles into the floating vessel further provided multiple air pressure to the powder particles blown up, the upper layer the lighter powder particles a small weight of the powder particle size As described above , the second blowing means composed of a plurality of air pipes arranged at different positions in the vertical direction above the first blowing means, and the electrode for applying an electric charge to the powder particles floating in the floating tank A powder coating apparatus comprising: a body; a moving device for moving an object to be coated in the floating tank; and a coating air pipe for flowing the powder particles in a horizontal direction.

3. The powder coating apparatus according to claim 2, wherein the second blowing means injects a weaker air pressure into the floating tank as the air pipe is arranged at an upper portion in the floating tank.