JPH08103719A - Coating application method - Google Patents

Abstract

PURPOSE: To provide a method for coating a non-solvent coating containing a nonvolatile component whose viscosity is low immediately after spraying, but is high to prevent the coating from dripping when it is coated. CONSTITUTION: A non-solvent paint consisting of a macromonomer containing 10 to 40wt.% of monomer having a thermal crosslinking functional group with an ethylene unsaturated bond at a terminal, at least one type of photopolymerizable monomer having one or two ethylene unsaturated bonds, a thermocurable crosslinking agent and a photopolymerization initiator, is sprayed to an object to be coated, and the scattering coating particles are irradiated with a UV rays. The paint which fixes on the object is heated at the crosslinking temperature of the thermocurable crosslinking agent. The coating becomes highly viscous when fixing and thus is prevented from dripping, because the macromonomer and the photopolymerizable monomer become polymerized by a UV rays and thickened.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、低粘度でありかつ不揮
発分１００％の無溶剤型塗料の塗装方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a solventless paint having a low viscosity and a nonvolatile content of 100%.

【０００２】[0002]

【従来の技術】自動車や家電製品の塗装には、耐候性な
どの物性が優れていることから、熱硬化型のアクリル樹
脂塗料が一般に用いられている。この熱硬化型のアクリ
ル樹脂塗料は、アクリル樹脂と、メラミン樹脂やイソシ
アネート樹脂などの架橋剤と、有機溶剤とから主として
構成されている。このうちアクリル樹脂と架橋剤とは熱
などにより反応し、三次元網目構造を形成して強靱な塗
膜を形成する。一方、有機溶剤は塗料の粘度を適切な値
に調整し、スプレーなどの塗装作業を容易としている。2. Description of the Related Art Thermosetting acrylic resin paints are generally used for coating automobiles and home electric appliances because of their excellent physical properties such as weather resistance. This thermosetting acrylic resin paint is mainly composed of an acrylic resin, a crosslinking agent such as a melamine resin or an isocyanate resin, and an organic solvent. Among them, the acrylic resin and the crosslinking agent react with each other by heat or the like to form a three-dimensional network structure and form a tough coating film. On the other hand, the organic solvent adjusts the viscosity of the paint to an appropriate value to facilitate the painting work such as spraying.

【０００３】ところで近年、地球環境保護の観点から塗
装作業における有機溶剤排出量の低減が重要な課題とな
り、水性塗料やハイソリッド塗料の開発が活発に行われ
ている。中でも、水性塗料は排水処理が必要となるこ
と、乾燥が遅いことなどの理由から、ハイソリッド塗料
の開発が重要視されており、特に究極のハイソリッド塗
料としての無溶剤型塗料が最も好ましい塗料として注目
されている。By the way, in recent years, from the viewpoint of protecting the global environment, reduction of the amount of organic solvent emission in the painting work has become an important issue, and water-based paints and high-solid paints have been actively developed. Above all, development of high solid paints is regarded as important because water-based paints require wastewater treatment, drying is slow, and the like, and solventless paints as the ultimate high solid paints are the most preferable paints. Is being watched as.

【０００４】[0004]

【発明が解決しようとする課題】無溶剤型塗料とは、低
粘度でありかつ不揮発分１００％の塗料をいう。この無
溶剤型塗料を実現するためには、溶剤を用いずに低粘度
にしてスプレーなどの塗装作業を容易にすること、及び
溶剤の揮発を利用することなく塗着時に粘度を増大させ
て垂れを防止することを同時に達成する必要がある。The solventless coating material is a coating material having a low viscosity and a nonvolatile content of 100%. In order to realize this solvent-free paint, make the viscosity low without using a solvent to facilitate coating work such as spraying, and increase the viscosity at the time of application without using the volatilization of the solvent to drip. It is necessary to achieve the prevention at the same time.

【０００５】このような無溶剤型塗料として、例えば特
開昭５９−１０３７９３号公報には、不飽和二重結合を
有するモノマーと、そのモノマーに溶解する熱可塑性樹
脂と、光重合開始剤とからなる紫外線硬化型塗料組成物
を含む塗料が開示されている。しかし、この塗料は、粘
度が低く過ぎて垂直面に塗装すると垂れが生じるという
不具合がある。また、塗膜に紫外線を照射して硬化させ
る関係上、被塗物の形状に制約が生じる。As such a solvent-free coating material, for example, JP-A-59-103793 discloses a monomer having an unsaturated double bond, a thermoplastic resin soluble in the monomer, and a photopolymerization initiator. A coating material containing the ultraviolet curable coating composition is disclosed. However, this paint has a problem that the viscosity is too low to cause dripping when applied to a vertical surface. In addition, the shape of the article to be coated is restricted because the coating film is irradiated with ultraviolet rays to be cured.

【０００６】本発明はこのような事情に鑑みてなされた
ものであり、塗布時にスプレーされた直後は低粘度であ
るが、塗着時には高粘度となって垂れが防止されるよう
な無溶剤型塗料の塗装方法を提供することを目的とす
る。The present invention has been made in view of the above circumstances, and has a low viscosity immediately after being sprayed at the time of application, but has a high viscosity at the time of application and is a solventless type which prevents sagging. It is an object to provide a coating method for paint.

【０００７】[0007]

【課題を解決するための手段】上記課題を解決する本発
明の塗装方法は、熱架橋性官能基含有モノマーを１０〜
４０重量％含み片末端にエチレン性不飽和結合を有する
マクロモノマーと、エチレン性不飽和結合を１つ又は２
つ有する少なくとも１種の光重合性モノマーと、熱硬化
性架橋剤と、光重合開始剤とからなる無溶剤型塗料を被
塗物に向けて噴霧する工程と、飛行中の塗料に紫外線を
照射する工程と、上記被塗物に塗着した塗料を上記熱硬
化性架橋剤の架橋温度に加熱する工程とからなることを
特徴とするものである。The coating method of the present invention for solving the above-mentioned problems comprises a heat-crosslinkable functional group-containing monomer in an amount of 10 to 10.
Macromonomer containing 40% by weight and having an ethylenically unsaturated bond at one end, and one or two ethylenically unsaturated bonds
Of spraying a solventless paint consisting of at least one photopolymerizable monomer having two, a thermosetting cross-linking agent, and a photopolymerization initiator toward the object to be coated, and irradiating the paint in flight with ultraviolet rays And a step of heating the coating material applied to the coating object to the crosslinking temperature of the thermosetting crosslinking agent.

【０００８】本発明に係る無溶剤型塗料を構成するマク
ロモノマーとしては、熱架橋性官能基含有モノマーを１
０〜４０重量％含み、片末端にエチレン性不飽和結合を
有するものが用いられる。熱架橋性官能基含有モノマー
の含有量が１０重量％よりも少ないと、架橋が不十分と
なり良好な塗膜物性を確保できない。また、熱架橋性官
能基含有モノマーの含有量が４０重量％よりも多いと、
架橋密度が高くなり過ぎて硬くてもろい塗膜となり、塗
膜性能が低下する。熱架橋性官能基含有モノマーとして
は、例えばアクリル酸、メタクリル酸、２−ヒドロキシ
エチルアクリレート、２−ヒドロキシエチルメタクリレ
ート、グリシジルメタクリレートを用いることができ
る。As the macromonomer constituting the solventless coating composition according to the present invention, 1 is a monomer containing a heat-crosslinkable functional group.
It is used in an amount of 0 to 40% by weight and having an ethylenically unsaturated bond at one end. When the content of the heat-crosslinkable functional group-containing monomer is less than 10% by weight, the crosslinking becomes insufficient and good coating film physical properties cannot be secured. When the content of the heat-crosslinkable functional group-containing monomer is more than 40% by weight,
The crosslink density becomes too high, resulting in a hard and brittle coating film, resulting in poor coating performance. As the heat-crosslinkable functional group-containing monomer, for example, acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate can be used.

【０００９】マクロモノマーとして、エチレン性不飽和
結合を複数もつものを用いた場合、塗粒の飛行中にゲル
化するため塗膜表面の平滑性が損なわれる。また、マク
ロモノマーとして、末端以外にエチレン性不飽和結合を
ものものを用いた場合、マクロモノマー同士やマクロモ
ノマーと光重合性モノマーとの反応性が低下し、十分な
増粘効果が得られない。When a macromonomer having a plurality of ethylenically unsaturated bonds is used, the surface smoothness of the coating film is impaired due to gelation during the flight of coating particles. Further, when a macromonomer having an ethylenically unsaturated bond in addition to the terminal is used, the reactivity between the macromonomers or between the macromonomer and the photopolymerizable monomer is lowered, and a sufficient thickening effect cannot be obtained. .

【００１０】マクロモノマーの重量平均分子量（以下Ｍ
ｗという）としては、５００〜５０００とすることが好
ましい。マクロモノマーのＭｗが５００より小さいと、
１分子中に十分な熱架橋性官能基含有モノマーを導入す
ることが困難となる。またマクロモノマーのＭｗが５０
００よりも大きくなると、塗料の粘度が高くなりハイソ
リッド化が困難となる。特に好ましいマクロモノマーの
Ｍｗは１０００〜３０００である。Weight average molecular weight of macromonomer (hereinafter M
(referred to as w) is preferably 500 to 5000. If the Mw of the macromonomer is less than 500,
It becomes difficult to introduce sufficient heat-crosslinkable functional group-containing monomer into one molecule. In addition, Mw of macromonomer is 50
If it is larger than 00, the viscosity of the coating material increases and it becomes difficult to form a high solid. The Mw of the particularly preferred macromonomer is 1000 to 3000.

【００１１】このマクロモノマーは、無溶剤型塗料中に
２０〜９０重量％添加することが好ましい。光重合性モ
ノマーとマクロモノマーが光重合性開始剤によって重合
してできたポリマーが塗料の主樹脂となり、主樹脂は塗
膜性能を確保するために塗料全体に対して５０重量％は
必要である。マクロモノマーの添加量が２０重量％より
少ないと、光重合性モノマーが３０重量％より多く必要
となる。このように光重合性モノマーの添加量が３０重
量％より多くなると、未反応の光重合性モノマーが多く
存在することとなり、塗膜物性に悪影響を及ぼすことと
なる。このため、マクロモノマーの添加量は２０重量％
以上とすることが好ましい。一方、マクロモノマーの添
加量が９０重量％より多いと、粘度が高くなり過ぎると
ともに、塗料中の光重合性モノマーの添加量が相対的に
少なくなり、塗着時に必要な増粘が得られ難くなる。マ
クロモノマーの添加量として、特に好ましい範囲は３０
〜５０重量％である。The macromonomer is preferably added in an amount of 20 to 90% by weight in the solventless coating composition. The polymer obtained by polymerizing the photopolymerizable monomer and macromonomer with the photopolymerizable initiator becomes the main resin of the paint, and the main resin is required to be 50% by weight with respect to the entire paint in order to secure coating film performance. . When the addition amount of the macromonomer is less than 20% by weight, the photopolymerizable monomer is required to be more than 30% by weight. As described above, when the amount of the photopolymerizable monomer added is more than 30% by weight, a large amount of unreacted photopolymerizable monomer is present, which adversely affects the physical properties of the coating film. Therefore, the amount of macromonomer added is 20% by weight.
It is preferable to make the above. On the other hand, when the addition amount of the macromonomer is more than 90% by weight, the viscosity becomes too high and the addition amount of the photopolymerizable monomer in the coating becomes relatively small, and it is difficult to obtain the necessary thickening at the time of coating. Become. A particularly preferable range of the addition amount of the macromonomer is 30
~ 50% by weight.

【００１２】上記マクロモノマーは、上記熱架橋性官能
基含有モノマー及び通常のアクリル樹脂に使用されるモ
ノマー（例えばメチルメタクリレート、ブチルアクリレ
ート、エチルヘキシルメタクリレートやスチレン）をチ
オグリコール酸などの連鎖移動剤の存在下で重合させた
後、グリシジルメタクリレートと反応させるという一般
的な合成法により製造することができる。The macromonomer is a monomer containing a heat-crosslinkable functional group and a monomer (eg, methylmethacrylate, butylacrylate, ethylhexylmethacrylate or styrene) used in ordinary acrylic resins, and a chain transfer agent such as thioglycolic acid. It can be produced by a general synthetic method in which it is polymerized below and then reacted with glycidyl methacrylate.

【００１３】このマクロモノマーを種々選択することに
より、塗膜物性を種々調整することができる。本発明に
係る無溶剤型塗料を構成する光重合性モノマーは、エチ
レン性不飽和結合を１つ又は２つ有するものが少なくと
も１種用いられる。エチレン性不飽和結合を３つ以上有
する光重合性モノマーを用いると、塗粒の飛行中にゲル
化するため塗膜表面の平滑性が損なわれる。エチレン性
不飽和結合を１つ又は２つ有する光重合性モノマーとし
ては、例えば２−エチルヘキシルカルビトールアクリレ
ート、トリプロピレングリコールジアクリレート、テト
ラエチレングリコールジアクリレート、ｎ−ドデシルメ
タクリレート、エチルヘキシルアクリレートを用いるこ
とができる。この光重合性モノマーは、熱架橋性官能基
を含んでいてもいなくても良い。Various physical properties of the coating film can be adjusted by selecting various macromonomers. As the photopolymerizable monomer constituting the solventless coating composition according to the present invention, at least one photopolymerizable monomer having one or two ethylenically unsaturated bonds is used. When a photopolymerizable monomer having three or more ethylenically unsaturated bonds is used, the surface of the coating film is impaired because it gels during the flight of the coating particles. As the photopolymerizable monomer having one or two ethylenically unsaturated bonds, for example, 2-ethylhexyl carbitol acrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, n-dodecyl methacrylate, ethylhexyl acrylate may be used. it can. This photopolymerizable monomer may or may not contain a thermally crosslinkable functional group.

【００１４】光重合性モノマーのＭｗとしては、１００
〜５００とすることが好ましい。光重合性モノマーのＭ
ｗが１００より小さいと、揮発性が高くなるためスプレ
ー時に溶剤と同様の揮発成分となる。一方、光重合性モ
ノマーのＭｗが５００よりも大きいと、塗料の粘度が高
くなりハイソリッド化が困難となる。特に好ましい光重
合性モノマーのＭｗは１５０〜３５０である。The Mw of the photopolymerizable monomer is 100.
It is preferable to set it to ˜500. Photopolymerizable monomer M
When w is less than 100, the volatility becomes high, so that it becomes a volatile component similar to the solvent during spraying. On the other hand, when the Mw of the photopolymerizable monomer is larger than 500, the viscosity of the coating becomes high and it becomes difficult to form a high solid. The Mw of the particularly preferred photopolymerizable monomer is 150 to 350.

【００１５】この光重合性モノマーは、無溶剤型塗料中
に１０〜３０重量％添加することが好ましい。光重合性
モノマーの添加量が１０重量％より少ないと、塗着時の
増粘効果が小さい。一方、光重合性モノマーの添加量が
３０重量％より多いと、未反応の光重合性モノマーが多
く存在することとなり、塗膜物性に悪影響を及ぼすこと
となる。光重合性モノマーの添加量として、特に好まし
い範囲は１０〜２０重量％である。The photopolymerizable monomer is preferably added to the solventless coating material in an amount of 10 to 30% by weight. When the amount of the photopolymerizable monomer added is less than 10% by weight, the thickening effect during coating is small. On the other hand, when the amount of the photopolymerizable monomer added is more than 30% by weight, a large amount of unreacted photopolymerizable monomer is present, which adversely affects the physical properties of the coating film. A particularly preferable range of the addition amount of the photopolymerizable monomer is 10 to 20% by weight.

【００１６】本発明に係る無溶剤型塗料を構成する熱硬
化性架橋剤としては、特に限定されないが、粘度が１０
０〜１０００ｃＰのものを用いることが好ましい。熱硬
化性架橋剤の粘度が１００ｃＰより低いと塗着時に必要
な粘度が得にくくなり、１０００ｃＰより高いと塗料の
粘度が高くなりハイソリッド化が困難となる。熱硬化性
架橋剤として、例えばメラミン樹脂、イソシアネート樹
脂を用いることができる。The thermosetting cross-linking agent constituting the solventless coating composition according to the present invention is not particularly limited, but has a viscosity of 10
It is preferable to use one of 0 to 1000 cP. If the viscosity of the thermosetting cross-linking agent is lower than 100 cP, it becomes difficult to obtain the necessary viscosity at the time of coating, and if it is higher than 1000 cP, the viscosity of the coating becomes high and it becomes difficult to form a high solid. As the thermosetting crosslinking agent, for example, melamine resin or isocyanate resin can be used.

【００１７】この熱硬化性架橋剤は、無溶剤型塗料中に
１５〜６０重量％添加することが好ましい。熱硬化性架
橋剤の添加量が１５重量％より少ないと、マクロモノマ
ーの熱架橋性官能基を十分に架橋させることが困難とな
る。一方、熱硬化性架橋剤の添加量が６０重量％より多
いと、主樹脂の性能が十分に発揮できなくなり、塗膜物
性に劣るようになる。熱硬化性架橋剤の添加量として、
特に好ましい範囲は２０〜４０重量％である。The thermosetting crosslinking agent is preferably added in an amount of 15 to 60% by weight in the solventless coating composition. When the addition amount of the thermosetting crosslinking agent is less than 15% by weight, it becomes difficult to sufficiently crosslink the thermocrosslinkable functional group of the macromonomer. On the other hand, when the addition amount of the thermosetting crosslinking agent is more than 60% by weight, the performance of the main resin cannot be fully exhibited and the physical properties of the coating film deteriorate. As the addition amount of the thermosetting crosslinking agent,
A particularly preferred range is 20 to 40% by weight.

【００１８】また、熱硬化性架橋剤として、上記マクロ
モノマーに含まれる熱架橋性官能基含有モノマーの熱架
橋性官能基と熱により反応する熱架橋性官能基を含有す
るモノマーが含まれたマクロモノマーを用いることも可
能である。例えば、上記マクロモノマーとして、熱架橋
性官能基としてのカルボキシル基を含有するモノマーが
含まれたマクロモノマーを用いた場合、この熱架橋性官
能基としてのカルボキシル基と熱により反応する熱架橋
性官能基としてのグリシジル基を含有するモノマーが含
まれたマクロモノマーを熱硬化性架橋剤として用いるこ
とができる。Further, as the thermosetting cross-linking agent, a macromolecule containing a monomer containing a heat-crosslinkable functional group that reacts with heat with the heat-crosslinkable functional group of the heat-crosslinkable functional group-containing monomer contained in the macromonomer. It is also possible to use monomers. For example, when a macromonomer containing a monomer containing a carboxyl group as a heat-crosslinkable functional group is used as the macromonomer, a heat-crosslinkable functional group that reacts by heat with the carboxyl group as the heat-crosslinkable functional group is used. A macromonomer containing a monomer containing a glycidyl group as a group can be used as the thermosetting crosslinking agent.

【００１９】本発明に係る無溶剤型塗料を構成する光重
合開始剤は、紫外線の照射によりラジカルを発生してマ
クロモノマーの片末端のエチレン性二重結合を攻撃し重
合を開始させるものであり、市販の光重合開始剤、例え
ばダロキュア１１７３やイルガキュア（ともにチバガイ
ギ社製）を使用できる。この光重合開始剤の添加量は、
マクロモノマー及び光重合性モノマーの総量に対して１
〜１０重量％である。光重合開始剤の添加量が１重量％
より少ないと、反応開始点としてのラジカル発生が少な
いために塗着時に高粘度となることが困難であり垂れが
生じるようになる。また光重合開始剤の添加量が１０重
量％より多いと、反応阻害が起こるため反応性が逆に低
下してしまうとともに、未反応の光重合性開始剤が塗膜
中に多く存在することとなる。The photopolymerization initiator constituting the solventless coating composition according to the present invention is one which generates radicals by irradiation of ultraviolet rays and attacks the ethylenic double bond at one end of the macromonomer to initiate polymerization. A commercially available photopolymerization initiator such as Darocur 1173 or Irgacure (both manufactured by Ciba-Geigy) can be used. The amount of this photopolymerization initiator added is
1 for the total amount of macromonomer and photopolymerizable monomer
10 to 10% by weight. Addition amount of photopolymerization initiator is 1% by weight
When the amount is smaller, it is difficult to obtain a high viscosity at the time of application because the generation of radicals as a reaction starting point is small, and dripping occurs. When the amount of the photopolymerization initiator added is more than 10% by weight, the reaction is adversely affected due to reaction inhibition, and the unreacted photopolymerization initiator is often present in the coating film. Become.

【００２０】本発明に係る無溶剤型塗料が飛行している
間に照射する紫外線の照射量としては、１０〜２００ｍ
Ｊ／ｃｍ² の範囲が望ましい。照射量が１０ｍＪ／ｃｍ
² より少ないとマクロモノマー同士や光重合性モノマー
同士の反応が充分でなく、塗着時に高粘度となることが
困難であり垂れが生じるようになる。また２００ｍＪ／
ｃｍ² を超えると塗着時の粘度が高くなり過ぎ、塗膜の
平滑性が損なわれるようになる。なお、マクロモノマー
量を例えば１０重量％などと少なくすれば、２００ｍＪ
／ｃｍ² 以上の照射量で適当な増粘度が得られるが、ス
プレー作業時に２００ｍＪ／ｃｍ² 以上の紫外線を照射
することは実用上困難である。The irradiation amount of ultraviolet rays to be applied during flight of the solventless coating material according to the present invention is 10 to 200 m.
The range of J / cm ² is desirable. Irradiation dose is 10 mJ / cm
^If it is less than ^2, the reaction between the macromonomers and between the photopolymerizable monomers is not sufficient, and it becomes difficult to have a high viscosity during coating, resulting in sagging. 200mJ /
When it exceeds cm ² , the viscosity at the time of coating becomes too high, and the smoothness of the coating film is impaired. If the amount of macromonomer is reduced to, for example, 10% by weight, 200 mJ
/ Cm ² or more suitable thickening irradiation amount is obtained, it is practically difficult to irradiate the 200 mJ / cm ² or more ultraviolet during spraying.

【００２１】被塗物に塗着した塗料を加熱する際の温度
としては、熱硬化性架橋剤によりマクロモノマーに含ま
れる熱架橋性官能基同士が十分に反応して、十分な架橋
構造が形成され得る熱硬化性架橋剤の架橋温度とするこ
とができる。The temperature at which the coating material applied to the object to be coated is heated is such that the thermosetting crosslinking agent causes the thermocrosslinkable functional groups contained in the macromonomer to sufficiently react with each other to form a sufficient crosslinked structure. It can be the crosslinking temperature of the thermosetting crosslinking agent which can be.

【００２２】[0022]

【作用】本発明に係る無溶剤型塗料を構成するマクロモ
ノマーや光重合性モノマーは、従来の塗料に基体樹脂と
して用いられるアクリル樹脂などと比べて分子量が小さ
く、それ自体の粘度が低い。また、粘度の高いアクリル
樹脂などを基体樹脂として含んでいない。このため、本
発明に係る無溶剤型塗料は、低粘度であるためスプレー
塗装性に優れ、微粒化した塗粒が得られる。The macromonomer and photopolymerizable monomer constituting the solvent-free coating material according to the present invention have a smaller molecular weight and a lower viscosity per se than the acrylic resin used as a base resin in conventional coating materials. Further, it does not contain a highly viscous acrylic resin as a base resin. Therefore, the solventless coating composition according to the present invention has a low viscosity and thus has excellent spray coatability, and finely divided coating particles can be obtained.

【００２３】そして飛行中の塗料に紫外線が照射される
と、塗料の塗粒中の光重合開始剤が活性化し、マクロモ
ノマーの片末端二重結合同士が反応するとともに、光重
合性モノマー同士が反応する。また、マクロモノマーと
光重合性モノマーとが反応する。この重合反応によるマ
クロモノマー及び光重合性モノマーの高分子化により塗
粒の粘度が上昇し、被塗物に塗着したときには垂れの生
じにくい粘度となっている。しかも塗粒の粒径は飛行中
に増大することは無いため、塗着時にも微粒子状であ
り、塗膜表面の平滑性にも優れている。When the paint in flight is irradiated with ultraviolet rays, the photopolymerization initiator in the paint particles is activated, the double bonds at one end of the macromonomer react with each other, and the photopolymerizable monomers are separated from each other. react. Further, the macromonomer and the photopolymerizable monomer react with each other. Due to the polymerization of macromonomers and photopolymerizable monomers by this polymerization reaction, the viscosity of the coating particles increases, and the viscosity is such that dripping does not easily occur when applied to an object to be coated. Moreover, since the particle size of the coating particles does not increase during flight, the coating particles are fine particles even when they are applied, and the coating film surface is excellent in smoothness.

【００２４】このように被塗物に形成されたウェット塗
膜は、含まれる熱硬化性架橋剤の架橋温度に加熱され焼
き付けられて塗装が終了する。この加熱時に、マクロモ
ノマーに含まれていた熱架橋性官能基同士が反応して架
橋構造が形成されるので、塗膜物性が一層向上する。The wet coating film thus formed on the article to be coated is heated to the crosslinking temperature of the thermosetting crosslinking agent contained therein and baked to complete the coating. During this heating, the thermally crosslinkable functional groups contained in the macromonomer react with each other to form a crosslinked structure, so that the physical properties of the coating film are further improved.

【００２５】[0025]

【実施例】以下、実施例により具体的に説明する。 （実施例１）熱架橋性官能基含有モノマーとしての２−
ヒドロキシエチルメタクリレートを含み、片末端にメタ
クロイル基をもつマクロモノマー（モノマー組成：メチ
ルメタクリレート／２−ヒドロキシエチルメタクリレー
ト＝８０／２０（重量比）、Ｍｗ＝２３００）３０重量
％と、光重合性モノマーとしてのトリプロピレングリコ
ールジアクリレート（東亜合成（株）製、「Ｍ−２２
０」、熱架橋性官能基を２つもつＵＶモノマー）３０重
量％と、熱硬化性架橋剤としてのメラミン樹脂（三井サ
アナミッド（株）製、「サイメル２３６」）３５重量％
と、光重合開始剤としての「ダロキュアー１１７３」
（日本チバガイギー（株）製）５重量％とを混合して、
本実施例に係る無溶剤型塗料とした。なお、この無溶剤
型塗料の粘度は、２５℃で１４０ｃＰであった。EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) 2- as a thermally crosslinkable functional group-containing monomer
30% by weight of a macromonomer containing hydroxyethyl methacrylate and having a metacroyl group at one end (monomer composition: methyl methacrylate / 2-hydroxyethyl methacrylate = 80/20 (weight ratio), Mw = 2300), and as a photopolymerizable monomer Tripropylene glycol diacrylate (manufactured by Toagosei Co., Ltd., “M-22
0 ", 30% by weight of a UV monomer having two heat-crosslinkable functional groups, and 35% by weight of a melamine resin (" CYMER 236 "manufactured by Mitsui Saanamid Co., Ltd.) as a thermosetting crosslinking agent.
And "Darocur 1173" as a photopolymerization initiator
5% by weight (manufactured by Nippon Ciba Geigy Co., Ltd.),
The solventless coating material according to this example was used. The viscosity of this solventless paint was 140 cP at 25 ° C.

【００２６】この無用剤型塗料を、スプレーガンを用い
て、被塗物としてのガラス板にスプレー塗装した。この
スプレー塗装時、８０Ｗ／ｃｍの紫外線ランプを用い
て、ＵＶ照射量：３０ｍＪ／ｃｍ² 、照射時間：０．１
秒として、飛行中の塗料に紫外線照射した。そして、被
塗物に塗着した塗料を１４０℃の温度に加熱して塗装を
終了した。This useless formulation was spray-painted on a glass plate as an article to be coated using a spray gun. At the time of this spray coating, using a UV lamp of 80 W / cm, UV irradiation amount: 30 mJ / cm ² , irradiation time: 0.1
In seconds, the paint in flight was exposed to UV light. Then, the coating material applied to the article was heated to a temperature of 140 ° C. to finish the coating.

【００２７】このように本実施例に係る無溶剤型塗料に
おいては、スプレー塗装時には１４０ｃＰの低粘度であ
るのでスプレーガンからは微細な塗粒が噴出する。そし
てスプレーガンから出てから被塗物に塗着するまでの僅
かな時間の間に塗粒に紫外線を照射すれば、飛行中の塗
粒の粘度は一挙に約１０００ｃｐ以上に上昇するので、
被塗物に塗着して形成された塗膜に垂れが生じるのが防
止される。また、被塗物に塗着した塗料は加熱されるこ
とにより、塗膜中に架橋構造が形成されるので、塗膜物
性が向上している。As described above, in the solventless paint according to the present embodiment, since the viscosity is low at 140 cP during spray coating, fine coating particles are ejected from the spray gun. Then, if the coating particles are irradiated with ultraviolet rays during a short time from when the spray gun is ejected until when they are applied to the object to be coated, the viscosity of the coating particles in flight increases to about 1000 cp or more at once.
It is possible to prevent the coating film formed by coating the object to be coated from dripping. In addition, since the coating material applied to the object to be coated is heated to form a crosslinked structure in the coating film, the physical properties of the coating film are improved.

【００２８】（実施例２）表１に示すように、実施例１
と同様のマクロモノマー３０重量％と、実施例１と同様
の光重合性モノマー１０重量％と、実施例１と同様の熱
硬化性架橋剤５５重量％と、実施例１と同様の光重合開
始剤５重量％とを混合し、本実施例に係る無溶剤型塗料
とした。この無溶剤型塗料の粘度は、２５℃で１９０ｃ
ｐであった。Example 2 As shown in Table 1, Example 1
30% by weight of the same macromonomer, 10% by weight of the same photopolymerizable monomer as in Example 1, 55% by weight of the same thermosetting crosslinking agent as in Example 1, and the same photopolymerization initiation as in Example 1 5% by weight of the agent was mixed to obtain a solventless paint according to this example. The viscosity of this solventless paint is 190c at 25 ° C.
It was p.

【００２９】（実施例３）表１に示すように、実施例１
と同様のマクロモノマー４８重量％と、光重合性モノマ
ーとしてのエチルヘキシルアクリレート（熱架橋性官能
基を１つもつＵＶモノマー）２８重量％と、実施例１と
同様の熱硬化性架橋剤１９重量％と、実施例１と同様の
光重合開始剤５重量％とを混合し、本実施例に係る無溶
剤型塗料とした。この無溶剤型塗料の粘度は、２５℃で
７０ｃｐであった。(Example 3) As shown in Table 1, Example 1
48% by weight of the same macromonomer, 28% by weight of ethylhexyl acrylate (UV monomer having one thermally crosslinkable functional group) as a photopolymerizable monomer, and 19% by weight of the same thermosetting crosslinking agent as in Example 1. And 5% by weight of the same photopolymerization initiator as in Example 1 were mixed to obtain a solventless coating material according to this example. The viscosity of this solventless paint was 70 cp at 25 ° C.

【００３０】（実施例４）表１に示すように、実施例１
と同様のマクロモノマー２８重量％と、光重合性モノマ
ーとしてのエチルヘキシルアクリレート（熱架橋性官能
基を１つもつＵＶモノマー）２８重量％と、実施例１と
同様の熱硬化性架橋剤３９重量％と、実施例１と同様の
光重合開始剤５重量％とを混合し、本実施例に係る無溶
剤型塗料とした。この無溶剤型塗料の粘度は、２５℃で
１３０ｃｐであった。(Example 4) As shown in Table 1, Example 1
28% by weight of the same macromonomer, 28% by weight of ethylhexyl acrylate (UV monomer having one thermally crosslinkable functional group) as a photopolymerizable monomer, and 39% by weight of the same thermosetting crosslinking agent as in Example 1. And 5% by weight of the same photopolymerization initiator as in Example 1 were mixed to obtain a solventless coating material according to this example. The viscosity of this solvent-free paint was 130 cp at 25 ° C.

【００３１】（実施例５）表１に示すように、実施例１
と同様のマクロモノマー３０重量％と、実施例１と同様
の光重合性モノマー３０重量％と、実施例１と同様の熱
硬化性架橋剤３９．５重量％と、実施例１と同様の光重
合開始剤０．５重量％とを混合し、本実施例に係る無溶
剤型塗料とした。この無溶剤型塗料の粘度は、２５℃で
１７０ｃｐであった。(Example 5) As shown in Table 1, Example 1
30% by weight of the same macromonomer, 30% by weight of the same photopolymerizable monomer as in Example 1, 39.5% by weight of the same thermosetting crosslinking agent as in Example 1, and the same light as in Example 1. A polymerization initiator of 0.5% by weight was mixed to obtain a solventless paint according to this example. The viscosity of this solvent-free paint was 170 cp at 25 ° C.

【００３２】（実施例６）表１に示すように、実施例１
と同様のマクロモノマー２０重量％と、光重合性モノマ
ーとしてのエチルヘキシルアクリレート（熱架橋性官能
基を１つもつＵＶモノマー）５重量％と、実施例１と同
様の熱硬化性架橋剤７０重量％と、実施例１と同様の光
重合開始剤５重量％とを混合し、本実施例に係る無溶剤
型塗料とした。この無溶剤型塗料の粘度は、２５℃で２
４０ｃｐであった。(Example 6) As shown in Table 1, Example 1
20% by weight of the same macromonomer, 5% by weight of ethylhexyl acrylate (UV monomer having one thermally crosslinkable functional group) as a photopolymerizable monomer, and 70% by weight of the same thermosetting crosslinking agent as in Example 1. And 5% by weight of the same photopolymerization initiator as in Example 1 were mixed to obtain a solventless coating material according to this example. The viscosity of this solventless paint is 2 at 25 ° C.
It was 40 cp.

【００３３】[0033]

【表１】 （ＵＶ照射量と粘度との関係）上記実施例１〜６の無溶
剤型塗料をそれぞれアルミ皿中に入れ、８０Ｗ／ｃｍの
紫外線ランプを用い、照射時間を変えながら紫外線を照
射して粘度を測定した。粘度測定時までの紫外線照射量
と粘度との関係を表２に示す。[Table 1] (Relationship between UV Irradiation Amount and Viscosity) The solventless paints of Examples 1 to 6 were placed in aluminum dishes and irradiated with ultraviolet rays while changing the irradiation time using an 80 W / cm ultraviolet lamp to adjust the viscosity. It was measured. Table 2 shows the relationship between the UV irradiation dose and the viscosity up to the time of viscosity measurement.

【００３４】[0034]

【表２】 表２より、紫外線を照射することにより塗料の粘度が上
昇することがわかる。そして、スプレー時の紫外線照射
で塗着時に必要な増粘効果を達成するためには、今回の
試験方法において２００ｍＪ／ｃｍ² 以下の照射量で１
０００ｃＰ以上に増粘する必要があると考えられ、この
条件を満たすのは実施例１〜４の塗料である。一方、実
施例５の塗料では光重合開始剤の添加量が少な過ぎたた
め、また実施例６の添加量では光重合性モノマーの添加
量が少なすぎたため、いずれも２２０ｍＪ／ｃｍ² と照
射量を多くしても十分な増粘効果が得られなかった。[Table 2] From Table 2, it can be seen that the viscosity of the coating material is increased by irradiating it with ultraviolet rays. Then, in order to achieve the thickening effect required for application by ultraviolet irradiation during spraying, in the test method of this time, an irradiation dose of 200 mJ / cm ² or less
It is considered necessary to increase the viscosity to 000 cP or more, and the paints of Examples 1 to 4 satisfy this condition. On the other hand, in the coating material of Example 5, the amount of the photopolymerization initiator added was too small, and in the amount of the addition of Example 6, the amount of the photopolymerizable monomer added was too small. Therefore, in both cases, the irradiation amount was 220 mJ / cm ² and the irradiation amount. Even if it increased, the sufficient thickening effect was not obtained.

【００３５】[0035]

【発明の効果】以上詳述したように本発明の塗装方法に
よれば、塗装時には低粘度であり塗粒は飛行中に増粘し
て塗着時に高粘度となるため、従来のハイソリッド塗料
や無溶剤型塗料でみられた垂れの不具合が防止される。
したがって従来に比べて厚膜に塗装することが可能とな
り、塗装品質が向上する。As described in detail above, according to the coating method of the present invention, the viscosity is low at the time of coating, and the coating particles are thickened during flight to have a high viscosity at the time of coating. Prevents the dripping problem seen with solvent-free paint.
Therefore, it becomes possible to coat a thicker film than in the past, and the coating quality is improved.

【００３６】また、塗料の飛行中に紫外線を照射し、被
塗物に塗着した塗料は加熱による架橋構造の形成により
硬化されるため、従来の無用剤型塗料のように塗膜に紫
外線を照射して硬化させる必要がなく、被塗物の形状に
制約が生じない。Further, since the coating material applied to the object to be coated is irradiated with ultraviolet rays during flight of the coating material and is cured by the formation of a cross-linking structure by heating, the coating film is exposed to ultraviolet rays like the conventional useless type coating material. There is no need to irradiate and cure, and there is no restriction on the shape of the article to be coated.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 熱架橋性官能基含有モノマーを１０〜４
０重量％含み片末端にエチレン性不飽和結合を有するマ
クロモノマーと、エチレン性不飽和結合を１つ又は２つ
有する少なくとも１種の光重合性モノマーと、熱硬化性
架橋剤と、光重合開始剤とからなる無溶剤型塗料を被塗
物に向けて噴霧する工程と、 飛行中の塗料に紫外線を照射する工程と、 上記被塗物に塗着した塗料を上記熱硬化性架橋剤の架橋
温度に加熱する工程とからなることを特徴とする塗装方
法。1. A heat-crosslinkable functional group-containing monomer is used in an amount of 10-4.
Macromonomer containing 0% by weight and having an ethylenically unsaturated bond at one end, at least one photopolymerizable monomer having one or two ethylenically unsaturated bonds, a thermosetting crosslinking agent, and photopolymerization initiation Spraying a solventless paint consisting of a coating agent toward the object to be coated, irradiating the coating material in flight with ultraviolet rays, and crosslinking the coating material applied to the object to be coated with the thermosetting crosslinking agent A coating method comprising the step of heating to a temperature.