JP2005211756A - Coat drying method - Google Patents
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この発明は、特に、水性ベース塗料と溶剤型クリア塗料とのウェット・オン・ウェット塗装における塗装乾燥方法に関する。 The present invention particularly relates to a coating drying method in wet-on-wet coating of a water-based base paint and a solvent-type clear paint.
周知の通り、自動車塗装に用いるベース塗料としては、塗料中の有機溶剤比率が比較的高い溶剤型ローソリッド塗料が一般的に使用されてきた。近年、環境への影響が省みられ、有機溶剤の排出規制が厳しくなるにつれ、広い用途分野にわたり、ベース塗料として、有機溶剤比率が低い水性ベース塗料が用いられるようになってきた。 As is well known, a solvent-type low solid paint having a relatively high organic solvent ratio has been generally used as a base paint for automobile painting. In recent years, as the impact on the environment has been eliminated and organic solvent emission regulations have become stricter, water-based base paints having a low organic solvent ratio have been used as base paints over a wide range of applications.
水性ベース塗料は、一般的に、固形分２０％程度，有機溶剤１０％程度，水７０％程度の重量比率を有している。この水性ベース塗料が、溶剤型塗料用の上塗工程において、溶剤型クリア塗料とのウェット・オン・ウェット塗装に用いられる場合があるが、従来、上記ウェット・オン・ウェット塗装時は、例えば、水性ベース塗料の塗装後に、ピンホール等の塗膜欠陥の発生を抑制すべく８０℃程度で３〜５分予備乾燥（プレヒート）して水をほとんど蒸発させ、その後に、クリア塗料をウェット・オン・ウェット塗装して、１４０℃程度で２０〜３０分焼付する手順で行なわれる。かかる技術によれば溶剤の削減及び良好な塗装外観の両立が可能であるが、例えば特開２００１−３１１０３５号公報（特許文献１）では、高湿条件下での塗膜の層間界面（すなわち水性ベース塗料とクリア塗料との間の界面）でのなじみや反転を制御し、高フリップフロップ性（視覚方向によって明度が異なる特性）を確保することで、ウェット・オン・ウェット塗装に更なる改良をもたらすことが知られている。 The water-based base paint generally has a weight ratio of about 20% solid content, about 10% organic solvent, and about 70% water. This water-based base paint may be used for wet-on-wet coating with a solvent-based clear paint in a solvent-based paint top coating process. After applying the base paint, pre-drying (preheat) at about 80 ° C for 3 to 5 minutes to prevent the occurrence of coating film defects such as pinholes, and then almost evaporate the water. It is carried out by a procedure of wet coating and baking at about 140 ° C. for 20 to 30 minutes. According to such a technique, it is possible to achieve both reduction of the solvent and good coating appearance. For example, in Japanese Patent Application Laid-Open No. 2001-311035 (Patent Document 1), an interlayer interface (that is, aqueous) Further improvements to wet-on-wet coating by controlling the familiarity and reversal at the interface between the base paint and the clear paint) and ensuring high flip-flop properties (characteristics with different brightness depending on the visual direction) It is known to bring.
ところで、ウェット・オン・ウェット塗装においてエネルギー削減や工程の短縮化を実現する方法の１つとして、プレヒート工程を簡素化する（つまりプレヒート温度を低温化したりプレヒート時間を短縮したりする）又はプレヒート工程自体を省略することが考えられる。しかし、プレヒート工程を簡素化すれば、プレヒート工程終了後にも、塗装面に塗着された水性ベース塗料に多量の水分が残り、この水分が、焼付工程時に突沸することにより、ピンホール等の塗膜欠陥が発生して仕上がり塗装面の外観性が悪くなるという問題があった。加えて、特にアルミフレーク等の発色部材を含有する水性ベース塗料を用いた場合には、水分の突沸によって、水性ベース塗料とクリア塗料との間の界面の乱れが生じ、水性ベース塗料内でアルミフレークの配向性が損なわれて、塗装面の光輝感が低下するという問題がある。 By the way, as one of the methods for realizing energy reduction and process shortening in wet-on-wet coating, the preheating process is simplified (that is, the preheating temperature is lowered or the preheating time is shortened) or the preheating process. It is conceivable to omit itself. However, if the preheating process is simplified, a large amount of moisture remains in the water-based base paint applied to the painted surface even after the preheating process is completed, and this moisture bumps during the baking process, so There was a problem that film appearance occurred and the appearance of the finished painted surface deteriorated. In addition, particularly when an aqueous base paint containing a coloring member such as aluminum flakes is used, disturbance of the interface between the aqueous base paint and the clear paint occurs due to bumping of water, and aluminum is contained in the aqueous base paint. There is a problem that the orientation of the flakes is impaired and the glitter of the painted surface is lowered.
本発明は、上記技術的課題に鑑みてなされたもので、プレヒート工程の低温化及び短縮化を行いつつ、仕上がり塗装面の良好な外観性を確保し得るウェット・オン・ウェット塗装における塗装乾燥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 technical problem, and is a method for drying coating in wet-on-wet coating that can ensure a good appearance of the finished painted surface while reducing the temperature and shortening the preheating process. The purpose is to provide.
本願の請求項１に係る発明は、水性塗料からなる第１の塗料に対して第２の塗料をウェット・オン・ウェット塗装し、焼付乾燥するようにした塗装乾燥方法において、上記第２の塗料中に含有される樹脂の極性を示す指標であるＳＰを１０以下に設定するとともに、焼付乾燥に際して、焼付温度５０℃以上１１０℃以下で５分以上にわたる第１の焼付乾燥を行った後に、焼付温度９０以上１５０℃以下で１０分以上にわたる第２の焼付乾燥を行なうことを特徴としたものである。
なお、「ＳＰ」とは、当該技術分野においてよく知られた物質の極性を示す溶解性パラメータであり、第１の塗料と第２の塗料との親和性の指標となる。
The invention according to claim 1 of the present application is the coating and drying method in which the second coating material is wet-on-wet applied to the first coating material comprising the water-based coating material, and is baked and dried. The SP, which is an index indicating the polarity of the resin contained therein, is set to 10 or less, and after baking, after the first baking and drying at a baking temperature of 50 ° C. to 110 ° C. for 5 minutes or more, baking is performed. The second baking and drying is performed at a temperature of 90 to 150 ° C. for 10 minutes or more.
Note that “SP” is a solubility parameter indicating the polarity of a substance well known in the art, and is an index of the affinity between the first paint and the second paint.
また、本願の請求項２に係る発明は、請求項１に係る発明において、上記第１の塗料が鱗片状の発色部材を含有する塗料であり、上記第２の塗料がクリア塗料であることを特徴としたものである。 The invention according to claim 2 of the present application is that, in the invention according to claim 1, the first paint is a paint containing a scale-like coloring member, and the second paint is a clear paint. It is a feature.
更に、本願の請求項３に係る発明は、請求項２に係る発明において、上記発色部材が、光輝材及び／又は光干渉材であることを特徴としたものである。 Furthermore, the invention according to claim 3 of the present application is characterized in that, in the invention according to claim 2, the coloring member is a bright material and / or a light interference material.
また、更に、本願の請求項４に係る発明は、請求項１〜３に係る発明のいずれかにおいて、上記第２の塗料が、有機溶剤を含有する塗料であることを特徴としたものである。 Furthermore, the invention according to claim 4 of the present application is characterized in that, in any of claims 1 to 3, the second paint is a paint containing an organic solvent. .
また、更に、本願の請求項５に係る発明は、請求項１〜４に係る発明のいずれかにおいて、上記ＳＰが、９以上１０以下であることを特徴としたものである。 Furthermore, the invention according to claim 5 of the present application is characterized in that, in any of the inventions according to claims 1 to 4, the SP is 9 or more and 10 or less.
また、更に、本願の請求項６に係る発明は、請求項１〜５に係る発明のいずれかにおいて、上記第１の焼付乾燥時における焼付温度を７０℃以上９０℃以下に設定することを特徴としたものである。 Furthermore, the invention according to claim 6 of the present application is characterized in that, in any of the inventions according to claims 1 to 5, the baking temperature at the time of the first baking drying is set to 70 ° C. or higher and 90 ° C. or lower. It is what.
また、更に、本願の請求項７に係る発明は、請求項１〜６に係る発明のいずれかにおいて、上記第１の焼付乾燥を１０分以上にわたって行なうことを特徴としたものである。 Furthermore, the invention according to claim 7 of the present application is characterized in that, in any of the inventions according to claims 1 to 6, the first baking drying is performed for 10 minutes or more.
本願の請求項１に係る発明によれば、ウェット・オン・ウェット塗装において、第１の塗料の塗装後のプレヒート工程の低温化及び短縮化を行った若しくはプレヒート工程を省略した場合にも、焼付工程時に、第１の塗料中に残存する水分が突沸することを防止して、ピンホール等の塗膜欠陥の発生を抑制することができ、仕上がり塗装面の良好な外観性を確保することができる。また、樹脂のＳＰが所定値以下である第２の塗料を用いることで、第１の塗料と第２の塗料との間の界面の乱れを抑制することができる。 According to the invention of claim 1 of the present application, in wet-on-wet coating, even when the preheating process after the first coating is performed at a low temperature and shortened or when the preheating process is omitted, baking is performed. During the process, the water remaining in the first paint can be prevented from bumping and the occurrence of coating film defects such as pinholes can be suppressed, and a good appearance of the finished painted surface can be ensured. it can. Moreover, the disorder | damage | failure of the interface between a 1st coating material and a 2nd coating material can be suppressed by using the 2nd coating material whose SP of resin is below a predetermined value.
また、本願の請求項２に係る発明によれば、請求項１に係る発明の作用及び効果により上記焼付工程時に第１の塗料中に残存する水分の突沸が防止されることから、第１の塗料に含有される発色部材の配向が乱れることもなく、意図した発色効果を得ることができる。 In addition, according to the invention according to claim 2 of the present application, the action and effect of the invention according to claim 1 prevents the bumping of moisture remaining in the first paint during the baking step. The intended coloring effect can be obtained without disturbing the orientation of the coloring member contained in the paint.
更に、本願の請求項３に係る発明によれば、有効な発色効果を得ることができる。 Furthermore, according to the invention of claim 3 of the present application, an effective coloring effect can be obtained.
また、更に、本願の請求項４に係る発明によれば、耐水性等の塗膜物性をより有効に確保することができる。 Furthermore, according to the invention of claim 4 of the present application, it is possible to more effectively ensure the coating film properties such as water resistance.
また、更に、本願の請求項５に係る発明によれば、リコート付着性等の塗膜物性をより有効に確保することができる。 Furthermore, according to the invention according to claim 5 of the present application, physical properties of the coating such as recoat adhesion can be more effectively ensured.
また、更に、本願の請求項６に係る発明によれば、請求項１に係る発明の作用及び効果を一層確実に実現することができる。 Furthermore, according to the invention of claim 6 of the present application, the operation and effect of the invention of claim 1 can be more reliably realized.
また、更に、本願の請求項７に係る発明によれば、請求項１に係る発明の作用及び効果を一層確実に実現することができる。 Furthermore, according to the invention of claim 7 of the present application, the operation and effect of the invention of claim 1 can be more reliably realized.
以下、本発明の実施形態について、添付図面を参照しながら説明する。
従来では、ウェット・オン・ウェット塗装におけるプレヒート工程の簡素化（低温化及び短縮化）を行なったり省略したりする場合、プレヒート工程終了時にも、塗装面に塗着された水性ベース塗料に水分が多量に残り、この水分が焼付工程時に突沸することにより、ピンホール等の塗膜欠陥が発生して、仕上がり塗装面の外観性が悪くなり、加えて、特にアルミフレーク等の発色部材を含有する水性ベース塗料を用いた場合には、水性ベース塗料内でアルミフレークの配向性が乱れ、塗装面の光輝感が低下するという問題があった。
Embodiments of the present invention will be described below with reference to the accompanying drawings.
Conventionally, when simplification (low temperature and shortening) of the preheating process in wet-on-wet coating is performed or omitted, even when the preheating process is finished, water is applied to the water-based base paint applied to the painted surface. A large amount remains and this moisture bumps during the baking process, resulting in coating film defects such as pinholes, resulting in poor appearance of the finished painted surface, and in addition, it contains coloring members such as aluminum flakes in particular. When the water-based base paint is used, there is a problem that the orientation of the aluminum flakes is disturbed in the water-based base paint and the brightness of the painted surface is lowered.
このような問題を解決するために、本願発明者は、まず、焼付工程時の初期温度を従来の場合より低く設定することで、水の蒸発が遅くなり、これにより、塗膜欠陥が抑制され、また、アルミフレークの配向性が損なわれないことを実証した。
更に、本願発明者は、樹脂のＳＰが所定値以下であるクリア塗料を用い、水性ベース塗料とクリア塗料との親和性を意図的に低下させることで、焼付工程時に水性ベース塗料とクリア塗料との間の界面の乱れが抑制され、アルミフレークの配向性を良好に維持し得ると考え、これを実証した。
本願発明は、かかる特性を関連付けて、特に、アルミフレークを含有する水性ベース塗料を塗装し、従来の場合より低温及び短時間でプレヒート工程を実施した場合若しくはプレヒート工程を省略した場合に、ＳＰが所定値以下であるクリア塗料を塗装し、その後、まず、水性ベース塗料の粘度が所定値以上になるまで従来の場合より低温で焼付乾燥を実施し、続けて、従来の場合と同じ温度まで昇温して焼付乾燥を実施することで、水性ベース塗料内のアルミフレークの良好な配向性を確保するものである。
In order to solve such a problem, the inventor of the present application first sets the initial temperature during the baking process lower than in the conventional case, thereby slowing the evaporation of water, thereby suppressing coating film defects. In addition, it was demonstrated that the orientation of the aluminum flakes is not impaired.
Furthermore, the inventor of the present application uses a clear paint whose resin SP is a predetermined value or less, and intentionally reduces the affinity between the water-based base paint and the clear paint. The disorder of the interface between the two was suppressed, and the orientation of the aluminum flakes could be maintained well, which was demonstrated.
The present invention relates to such characteristics, in particular, when an aqueous base paint containing aluminum flakes is applied, and when the preheating process is performed at a lower temperature and in a shorter time than the conventional case, or when the preheating process is omitted, the SP is Apply a clear paint that is less than or equal to the specified value, and then first bake and dry at a lower temperature than in the conventional case until the viscosity of the water-based base paint reaches or exceeds the specified value. By carrying out baking and drying, a good orientation of the aluminum flakes in the aqueous base paint is ensured.
図１は、プレヒート工程の簡素化（低温化及び短縮化）を行なった若しくはプレヒート工程を省略した場合における、従来及び本願発明の焼付温度及びクリア塗料の極性について異なる条件下での、水性ベース塗料内のアルミフレークの配向性（光輝感）の変化を模式的にあらわす図である。この図において、破線で示すラインＸは、従来の焼付条件及びＳＰが１０を超えるクリア塗料樹脂を用いて得られる配向性の変化をあらわし、また、一点鎖線で示すラインＹは、本発明の焼付条件及びＳＰが１０を超えるクリア塗料樹脂を用いて得られる配向性の変化をあらわし、更に、実線で示すラインＺは、本発明の焼付条件及びＳＰが１０以下であるクリア塗料樹脂を用いて得られる配向性の変化をあらわすものである。 FIG. 1 shows an aqueous base paint under different conditions with respect to the baking temperature and the polarity of the clear paint of the present invention when the preheating process is simplified (lowering and shortening) or the preheating process is omitted. It is a figure which shows typically the change of the orientation (brightness feeling) of the aluminum flakes in the inside. In this figure, a line X indicated by a broken line represents a change in orientation obtained using a conventional baking condition and a clear paint resin having an SP exceeding 10, and a line Y indicated by a one-dot chain line represents the baking of the present invention. The change in orientation obtained by using a clear paint resin having a condition and SP of more than 10 is shown. Further, a line Z shown by a solid line is obtained by using the clear paint resin having a baking condition of the present invention and SP of 10 or less. This represents a change in orientation.
横軸は、クリア塗料塗着時（Ｔ０），焼付開始時（Ｔ１），焼付初期（Ｔ２）及び焼付完了時（Ｔ３）の各時点をあらわす軸である。他方、縦軸は、水性ベース塗料内のアルミフレークの配向性をあらわす軸である。 The horizontal axis represents each time point when the clear paint is applied (T0), when baking starts (T1), at the beginning of baking (T2), and when baking is completed (T3). On the other hand, the vertical axis represents the orientation of the aluminum flakes in the aqueous base paint.
これらラインＸ，Ｙ，Ｚを比較して分かるように、従来の焼付条件及びクリア塗料樹脂のＳＰが１０を超える場合（ラインＸ）には、焼付開始から焼付初期までの間（Ｔ１〜Ｔ２）に、水性ベース塗膜内のアルミフレークの配向性が大きく乱れて光輝感が低下する。また、本発明の焼付条件及びクリア塗料樹脂のＳＰが１０を超える場合（ラインＹ）には、焼付開始から焼付初期までの間に、ラインＸの場合と比べて緩やかな勾配ではあるが、水性ベース塗膜内のアルミフレークの配向性が乱れて光輝感が低下する。これに対して、本発明の焼付条件及びクリア塗料樹脂のＳＰが１０以下である場合（ラインＺ）には、クリア塗料が塗着された時点から、水性ベース塗膜内のアルミフレークが乱れることはなく、一定に維持される。 As can be seen by comparing these lines X, Y, and Z, when the conventional baking conditions and the clear paint resin SP exceeds 10 (line X), from the start of baking to the initial baking (T1 to T2). In addition, the orientation of the aluminum flakes in the aqueous base coating film is greatly disturbed, resulting in a decrease in glitter. Further, when the baking condition of the present invention and the SP of the clear paint resin exceed 10 (line Y), the gradient is gentler than that of the line X from the start of baking to the initial baking stage, although it is water-based. The orientation of the aluminum flakes in the base coating film is disturbed, resulting in a decrease in glitter. On the other hand, when the baking condition of the present invention and the SP of the clear paint resin is 10 or less (line Z), the aluminum flakes in the aqueous base paint film are disturbed from the time when the clear paint is applied. Rather, it remains constant.
次に、ラインＺであわらすアルミフレークの配向性を実現する本発明の実施例に採用された各種塗料の調製方法について説明する。 Next, a method for preparing various paints employed in the examples of the present invention that achieves the orientation of the aluminum flakes lined with Z will be described.
水性ベース塗料の調製
水性ベース塗料Ａ又はＢは、アクリルエマルジョンＡ又はＢ２２０重量部，イオン交換水５５重量部，ジメチルアミノエタノール１重量部，アミノ樹脂（三井サイアナミド（株）製のサイメル３２７）２０重量部，光輝性顔料（例えば旭化成社製のアルミペーストＭＨ８８０１）２０．９重量部，表面調整剤（例えばエアープロダクツ社製のサーフィノール４４０）４．５重量部を均一分散することで得た。光輝性顔料は、鱗片状をなす発色材としての光輝材を含有する。なお、これに限定されることなく、光輝性顔料は、発色材として、光輝材の代わりに、光干渉材を含有しても、あるいは、光輝材及び光干渉材の両方を含有してもよい。
なお、かかる水性ベース塗料の調製方法、及び、以下に説明するアクリルエマルジョンＡ及びＢの製造方法は、例えば特開２００１−２４０７９１号公報に開示されるように、公知である。
Preparation of water-based base paint Water-based base paint A or B is acrylic emulsion A or B 220 parts by weight, ion-exchanged water 55 parts by weight, dimethylaminoethanol 1 part by weight, amino resin (Cymel 327 manufactured by Mitsui Cyanamid Co., Ltd.) 20 parts by weight Part, 20.9 parts by weight of a luster pigment (for example, aluminum paste MH8801 manufactured by Asahi Kasei Co., Ltd.) and 4.5 parts by weight of a surface conditioner (for example, Surfynol 440 manufactured by Air Products) were obtained by uniformly dispersing. The luster pigment contains a luster material as a coloring material having a scaly shape. Without being limited thereto, the bright pigment may contain a light interference material instead of the bright material as the color former, or may contain both the bright material and the light interference material. .
In addition, the preparation method of this water-based base coating material, and the manufacturing method of acrylic emulsion A and B demonstrated below are well-known as disclosed by Unexamined-Japanese-Patent No. 2001-240791, for example.
水性ベース塗料Ａ，Ｂにそれぞれ含有されるアクリルエマルジョンＡ，Ｂは、それぞれ、次のように製造された。
水性ベース塗料用のアクリルエマルジョンＡの製造
アクリルエマルジョンＡの製造に際しては、まず、反応容器に脱イオン水１２６重量部を加え、窒素気流中で混合攪拌しながら８０℃に昇温した。続いて、メタクリル酸メチル１０．２２重量部，アクリル酸エチル７３．４３重量部，メタクリル酸２−ヒドロキシエチル９．２８重量部，アクリルアミド４．００重量部，メタクリル酸３．０７重量部，アクアロンＨＳ−１０（第一工業製薬社製）０．５重量部，アデカリアソープＮＥ−２０（旭電化社製）０．５重量部及び脱イオン水１００重量部からなるモノマー乳化物と、過酸化アンモニウム０．３重量部及び脱イオン水１０重量部からなる開始剤溶液とを２時間にわたり並行して反応容器に滴下した。滴下終了後、２時間同温度で熟成した。続いて、４０℃まで冷却し、４００メッシュフィルターで濾過した後、脱イオン水６７．１重量部およびジメチルアミノエタノール０．３２重量部を加えてｐＨ６．５に調整し、平均粒子径２５０ｎｍ，不揮発分２５％のアクリルエマルジョンＡを得た。
The acrylic emulsions A and B contained in the water-based base coatings A and B, respectively, were produced as follows.
Production of Acrylic Emulsion A for Aqueous Base Paint In producing acrylic emulsion A, first, 126 parts by weight of deionized water was added to a reaction vessel, and the temperature was raised to 80 ° C. while mixing and stirring in a nitrogen stream. Subsequently, 10.22 parts by weight of methyl methacrylate, 73.43 parts by weight of ethyl acrylate, 9.28 parts by weight of 2-hydroxyethyl methacrylate, 4.00 parts by weight of acrylamide, 3.07 parts by weight of methacrylic acid, Aqualon HS Monomer emulsion consisting of 0.5 parts by weight of -10 (Daiichi Kogyo Seiyaku Co., Ltd.), 0.5 parts by weight of Adeka Soap NE-20 (manufactured by Asahi Denka) and 100 parts by weight of deionized water, and ammonium peroxide An initiator solution consisting of 0.3 parts by weight and 10 parts by weight of deionized water was dropped into the reaction vessel in parallel over 2 hours. After completion of dropping, the mixture was aged at the same temperature for 2 hours. Subsequently, after cooling to 40 ° C. and filtration through a 400 mesh filter, 67.1 parts by weight of deionized water and 0.32 parts by weight of dimethylaminoethanol were added to adjust the pH to 6.5. Acrylic emulsion A having a content of 25% was obtained.
水性ベース塗料用のアクリルエマルジョンＢの製造
他方、アクリルエマルジョンＢの製造に際しては、まず、反応容器に脱イオン水１３６重量部を加え、窒素気流中で混合攪拌しながら８０℃に昇温した。続いて、メタクリル酸メチル１０．２２重量部，アクリル酸エチル５８．３６重量部，メタクリル酸２−ヒドロキシエチル７．４２重量部，アクリルアミド４．００重量部，アクアロンＨＳ−１０（第一工業製薬社製）０．５重量部，アデカリアソープＮＥ−２０（旭電化社製）０．５重量部及び脱イオン水８０重量部からなるモノマー乳化物と、過酸化アンモニウム０．２４重量部及び脱イオン水１０重量部からなる開始剤溶液とを２時間にわたり並行して反応容器に滴下した。滴下終了後、１時間同温度で熟成した。更に、８０℃でアクリル酸エチル１５．０７重量部，メタクリル酸２−ヒドロキシエチル１．８６重量部，メタクリル酸３．０７重量部，過硫酸アンモニウム０．０６重量部及び脱イオン水１０重量部からなる開始剤溶液を０．５時間にわたり並行して反応溶液に滴下した。滴下終了後、２時間同温度で熟成した。続いて、４０℃まで冷却し、４００メッシュフィルターで濾過した後、脱イオン水６７．１重量部及びジメチルアミノエタノール０．３２重量部を加えてｐＨ６．５に調整し、平均粒子径２００ｎｍ，不揮発分２５％のアクリルエマルジョンＢを得た。
Production of Acrylic Emulsion B for Aqueous Base Paint On the other hand, in the production of acrylic emulsion B, first, 136 parts by weight of deionized water was added to the reaction vessel, and the temperature was raised to 80 ° C. while mixing and stirring in a nitrogen stream. Subsequently, 10.22 parts by weight of methyl methacrylate, 58.36 parts by weight of ethyl acrylate, 7.42 parts by weight of 2-hydroxyethyl methacrylate, 4.00 parts by weight of acrylamide, Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) (Manufactured) 0.5 parts by weight, Adekaria soap NE-20 (manufactured by Asahi Denka Co., Ltd.) 0.5 parts by weight and deionized water 80 parts by weight monomer emulsion, ammonium peroxide 0.24 parts by weight and deionized An initiator solution consisting of 10 parts by weight of water was dropped into the reaction vessel in parallel over 2 hours. After completion of dropping, the mixture was aged at the same temperature for 1 hour. Furthermore, it consists of 15.07 parts by weight of ethyl acrylate, 1.86 parts by weight of 2-hydroxyethyl methacrylate, 3.07 parts by weight of methacrylic acid, 0.06 parts by weight of ammonium persulfate and 10 parts by weight of deionized water at 80 ° C. The initiator solution was added dropwise to the reaction solution in parallel over 0.5 hours. After completion of dropping, the mixture was aged at the same temperature for 2 hours. Subsequently, after cooling to 40 ° C. and filtration through a 400 mesh filter, 67.1 parts by weight of deionized water and 0.32 parts by weight of dimethylaminoethanol were added to adjust the pH to 6.5, and the average particle size was 200 nm, non-volatile. An acrylic emulsion B of 25% min was obtained.
この実施形態では、ウェット・オン・ウェット塗装において、水性ベース塗料を塗装する前工程として、中塗り塗料Ａ又はＢが塗装され、焼付乾燥される。具体的には、中塗り塗料Ａ及びＢとして、以下のもの若しくは以下のように調製されたものを用いた。
中塗り塗料Ａ
中塗り塗料Ａとしては、溶剤型のＯＴＯＨ８７０グレー（日本ペイント社製）を使用した。
中塗り塗料Ｂ
中塗り塗料Ｂは、ポリエステル樹脂３０重量部、アミノ樹脂２５重量部、アクリル樹脂１５重量部、ウレタン変性ポリエステル樹脂３０重量部、二酸化チタン６０重量部、カーボンブラック１重量部、アクリル系表面調整剤０．２重量部及びイオン交換水１６１．２重量部を均一分散して水性の中塗り塗料Ｂを調製した。
ここで、ポリエステル樹脂としては、酸価５０，水酸基価１２０，数平均分子量２０００のものを用い、アミノ樹脂としては、サイメル３２７（三井サイアナミッド社製）を用い、また、アクリル樹脂としては、酸価５０，水酸基価１５０，数平均分子量５０００のもので、アミド基含有エチレン性モノマー２０質量％，酸性基含有エチレン性モノマー１０質量％，水酸基含有エチレン性モノマー５０質量％及び他のエチレン性モノマー５０質量％の共重合体を用い、更に、ウレタン変性ポリエステル樹脂としては、ｐＨが約７．５であるコロイダル分散ウレタン変性ポリエステル樹脂を用いる。
なお、かかる中塗り塗料Ｂの調製方法は、例えば特開２００２−１４６２８２号公報に開示されるように、公知である。
In this embodiment, in the wet-on-wet coating, the intermediate coating material A or B is applied and baked and dried as a pre-process for applying the aqueous base coating material. Specifically, as the intermediate coating materials A and B, the following materials or those prepared as follows were used.
Intermediate coating A
As the intermediate coating A, solvent-type OTOH 870 gray (manufactured by Nippon Paint Co., Ltd.) was used.
Intermediate coating B
The intermediate coating material B comprises 30 parts by weight of a polyester resin, 25 parts by weight of an amino resin, 15 parts by weight of an acrylic resin, 30 parts by weight of a urethane-modified polyester resin, 60 parts by weight of titanium dioxide, 1 part by weight of carbon black, and 0 of an acrylic surface conditioner. An aqueous intermediate coating material B was prepared by uniformly dispersing 2 parts by weight and 161.2 parts by weight of ion-exchanged water.
Here, as the polyester resin, those having an acid value of 50, a hydroxyl value of 120, and a number average molecular weight of 2000 are used. As an amino resin, Cymel 327 (manufactured by Mitsui Cyanamid) is used. As an acrylic resin, an acid value is used. 50, hydroxyl value 150, number average molecular weight 5000, amide group-containing ethylenic monomer 20% by mass, acidic group-containing ethylenic monomer 10% by mass, hydroxyl group-containing ethylenic monomer 50% by mass and other ethylenic monomers 50% by mass % Of a copolymer, and as the urethane-modified polyester resin, a colloidal dispersion urethane-modified polyester resin having a pH of about 7.5 is used.
In addition, the preparation method of this intermediate coating material B is well-known as disclosed by Unexamined-Japanese-Patent No. 2002-146282, for example.
溶剤型クリア塗料Ａ
溶剤型クリア塗料Ａとしては、ＯＴＯ５６３クリア（日本ペイント社製）を使用した。
Solvent type clear paint A
As solvent-type clear paint A, OTO563 clear (made by Nippon Paint Co., Ltd.) was used.
溶剤型クリア塗料Ｂ
溶剤型クリア塗料Ｂとしては、マックフローＯ−６００クリア（日本ペイント社製）を使用した。
Solvent type clear paint B
As the solvent-type clear paint B, MacFlow O-600 clear (manufactured by Nippon Paint Co., Ltd.) was used.
テストピースの作製
本願発明者は、上記の水性ベース塗料Ａ又はＢとクリア塗料Ａ又はＢとを用いた、低温及び短時間でのプレヒート工程を伴うウェット・オン・ウェット塗装の仕上がり品質について検証を行なった。この検証においては、次のように作製されたテストピース（中上塗り板Ａ〜Ｄ）を用いた。まず、リン酸亜鉛処理した厚み０．８ｍｍ，縦１０ｃｍ，横３０ｃｍのダル鋼板にＰＮ１２０Ｍ（日本ペイント社製）を乾燥膜厚が２０μｍになるように電着塗装し、１６０℃で３０分焼付乾燥して、電着板を作製する。この電着板に更なる処理を施して、以下の中上塗り板Ａ〜Ｄを作製する。
（中上塗り板Ａ）
電着板に中塗り塗料Ａを乾燥膜厚が３０μｍになるようにスプレー塗装し、１４０℃で３０分焼付乾燥した。続いて、水性ベース塗料を乾燥膜厚が１５μｍになるようにスプレー塗装し、４０℃で２分プレヒートした。続いて、クリア塗料を乾燥膜厚が３５μｍになるようにスプレー塗装し、所定の温度で焼付乾燥した。
（中上塗り板Ｂ）
電着板に中塗り塗料Ｂを乾燥膜厚が２０μｍになるようにスプレー塗装し、４０℃で２分プレヒートした。続いて、水性ベース塗料を乾燥膜厚が１５μｍになるようにスプレー塗装し、４０℃で２分プレヒートした。続いて、クリア塗料を乾燥膜厚が３５μｍになるようにスプレー塗装し、所定の温度で焼付乾燥した。
（中上塗り板Ｃ）
電着板に中塗り塗料Ａを乾燥膜厚が３０μｍになるようにスプレー塗装し、１４０℃で３０分焼付乾燥した。続いて、水性ベース塗料を乾燥膜厚が３〜３０μｍに成るようにスプレー塗装し、４０℃で２分プレヒートした。続いて、クリア塗料を乾燥膜厚が３５μｍになるようにスプレー塗装し、所定の温度で焼付乾燥した。
（中上塗り板Ｄ）
電着板に中塗り塗料Ｂを乾燥膜厚が２０μｍになるようにスプレー塗装し、４０℃で２分プレヒートした。続いて、水性ベース塗料を乾燥膜厚が３〜３０μｍに成るようにスプレー塗装し、４０℃で２分プレヒートした。続いて、クリア塗料を乾燥膜厚が３５μｍになるようにスプレー塗装し、所定の温度で焼付乾燥した。
Preparation of test piece The inventor of the present application verifies the finish quality of wet-on-wet coating using the above-mentioned water-based base paint A or B and clear paint A or B with a preheating process at a low temperature and in a short time. I did it. In this verification, test pieces (intermediate coating plates A to D) produced as follows were used. First, a galvanized steel plate with a thickness of 0.8mm, length 10cm, width 30cm was electrodeposited with PN120M (Nippon Paint Co., Ltd.) to a dry film thickness of 20μm and dried at 160 ° C for 30 minutes. Thus, an electrodeposition plate is produced. Further processing is performed on this electrodeposition plate to produce the following middle top coat plates A to D.
(Middle top coat A)
The electrodeposition plate was spray-coated with an intermediate coating material A so that the dry film thickness was 30 μm, and baked and dried at 140 ° C. for 30 minutes. Subsequently, the aqueous base paint was spray-coated so that the dry film thickness was 15 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the clear paint was spray-coated so that the dry film thickness was 35 μm, and baked and dried at a predetermined temperature.
(Middle top coat B)
The electrodeposition plate was spray-coated with an intermediate coating B so that the dry film thickness was 20 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the aqueous base paint was spray-coated so that the dry film thickness was 15 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the clear paint was spray-coated so that the dry film thickness was 35 μm, and baked and dried at a predetermined temperature.
(Middle top coat C)
The electrodeposition plate was spray-coated with an intermediate coating material A so that the dry film thickness was 30 μm, and baked and dried at 140 ° C. for 30 minutes. Subsequently, the aqueous base paint was spray-coated so that the dry film thickness was 3 to 30 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the clear paint was spray-coated so that the dry film thickness was 35 μm, and baked and dried at a predetermined temperature.
(Middle top coat D)
The electrodeposition plate was spray-coated with an intermediate coating B so that the dry film thickness was 20 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the aqueous base paint was spray-coated so that the dry film thickness was 3 to 30 μm, and preheated at 40 ° C. for 2 minutes. Subsequently, the clear paint was spray-coated so that the dry film thickness was 35 μm, and baked and dried at a predetermined temperature.
このように作製された中上塗り板Ａ〜Ｄの塗装面の光輝感，冷熱繰返し性，硬度及びピンホール限界膜厚について評価した。各評価は、次のように行った。
光輝感
変角光度計ＭＡ−６８（Ｘ−Ｒｉｔｅ社製）を用いて中上塗り板Ａ及びＢの塗装面のフロップインデックスを光輝感として測定した。そして、フロップインデックスが１２以上であった場合を非常に良好である、フロップインデックスが１０以上１２未満であった場合を良好である、フロップインデックスが１０未満であった場合を良好でないとして評価した。
冷熱繰返し性
中上塗り板Ａ及びＢを−２０℃で１時間保持した後３０分室温で保持した。更に、８０℃で１時間保持した後３０分室温で保持した。これを１サイクルとして５サイクル繰返し、５サイクルで割れが無かった場合を良好である、５サイクル未満で割れが発生した場合を良好でないとして評価した。
硬度
中上塗り板Ａ及びＢをＪＩＳＫ５４００ ８．４鉛筆引っかき値に準じて５回試験し、２回以上塗膜にすり傷が認められた時の鉛筆の濃度記号を塗膜の硬度とし、その濃度記号がＨ以上である場合を非常に良好である、ＨＢ以上Ｆ以下である場合を良好である、ＨＢ未満である場合を良好でないとして評価した。
ピンホール限界膜厚
中上塗り板Ｃ及びＤを観察してピンホールが発生しない位置を特定し、その位置の膜厚を測定してピンホール限界膜厚とした。そして、膜厚が２５μｍ以上である場合を非常に良好である、１５μｍ以上２５μｍ未満である場合を良好である、１５μｍ未満である場合を良好でないとして評価した。
The glossiness, the thermal repeatability, the hardness, and the pinhole limit film thickness of the coated surfaces of the intermediate top coat plates A to D thus produced were evaluated. Each evaluation was performed as follows.
The flop index of the coated surface of the intermediate top coating plates A and B was measured as a glitter feeling using a glitter variable angle photometer MA-68 (manufactured by X-Rite). Then, the case where the flop index was 12 or more was evaluated to be very good, the case where the flop index was 10 or more and less than 12 was good, and the case where the flop index was less than 10 was evaluated as not good.
The cold-repeatable intermediate top coat plates A and B were held at -20 ° C for 1 hour and then held at room temperature for 30 minutes. Further, it was kept at 80 ° C. for 1 hour and then kept at room temperature for 30 minutes. This was regarded as 1 cycle, repeated 5 cycles, and the case where there was no crack in 5 cycles was good, and the case where crack occurred in less than 5 cycles was evaluated as not good.
The top coating plates A and B in the hardness are tested five times according to JISK5400 8.4 pencil scratch value, and the pencil density symbol when the scratch is recognized more than once in the coating film is defined as the coating film hardness. A case where the symbol was H or higher was evaluated as being very good, a case where the symbol was HB or higher and F or lower was preferable, and a case where the symbol was lower than HB was evaluated as not good.
Observing the pinhole limit thickness in the topcoat plate C and D pinholes locates not occur, and the film pinhole limit film thickness by measuring the thickness at that position. The case where the film thickness was 25 μm or more was evaluated as being very good, the case where it was 15 μm or more and less than 25 μm was good, and the case where it was less than 15 μm was evaluated as not good.
表１〜３には、中塗り塗料Ａ，Ｂ，水性ベース塗料Ａ，Ｂ及びクリア塗料Ａ，Ｂを用いて、異なる焼付条件の下でウェット・オン・ウェット塗装を行なった各種例（実施例１〜６４及び比較例Ｒ１〜Ｒ２８）について得られた光輝感，冷熱繰返し性，硬度及びピンホール限界膜厚に関した評価結果をあらわす。
各表では、光輝感に関し、非常に良好であると評価された場合を「◎」であらわし、良好であると評価された場合を「○」であらわし、良好でないと評価された場合を「×」であらわす。
また、冷熱繰返し性に関して、良好であると評価された場合を「◎」であらわし、良好でないと評価された場合を「×」であらわす。
更に、硬度に関して、非常に良好であると評価された場合を「◎」であらわし、良好であると評価された場合を「○」であらわし、良好でないと評価された場合を「×」であらわす。
また、更に、ピンボール限界膜厚に関して、非常に良好であると評価された場合を「◎」であらわし、良好であると評価された場合を「○」であらわし、良好でないと評価された場合を「×」であらわす。
Tables 1 to 3 show various examples of wet-on-wet coating under different baking conditions using intermediate coatings A and B, aqueous base coatings A and B, and clear coatings A and B (Examples). 1 to 64 and Comparative Examples R1 to R28) represent the evaluation results regarding the glitter, the thermal repeatability, the hardness, and the pinhole limit film thickness.
In each table, regarding glitter feeling, a case where it was evaluated as being very good is represented by `` ◎ '', a case where it was evaluated as good is represented by `` ○ '', and a case where it was evaluated as not good was indicated as `` × ''. "
In addition, regarding cool and heat repeatability, a case where it is evaluated as good is represented by “」 ”, and a case where it is evaluated as not good is represented by“ x ”.
Furthermore, regarding hardness, “◎” represents a case where it was evaluated as very good, “○” represents a case where it was evaluated as good, and “x” represents a case where it was evaluated as not good. .
Furthermore, regarding the pinball limit film thickness, the case where it is evaluated as being very good is indicated by “◎”, the case where it is evaluated as being good is indicated by “◯”, and the case where it is evaluated as not good Is represented by “×”.
表１に示す実施例１〜３２は、中塗り塗料Ａ上に、水性ベース塗料Ａ又はＢとクリア塗料Ａとをウェット・オン・ウェット塗装するに際して、クリア塗料Ａが塗着された後にそれぞれ異なる焼付条件で焼付乾燥を行なうことで得られた中上塗り板Ａ又はＣについての評価をあらわしている。クリア塗料としては、樹脂のＳＰが９．６であるクリア塗料Ａを用いた。また、表２に示す実施例３３〜６４は、中塗り塗料Ｂ上に、水性ベース塗料Ａ又はＢとクリア塗料Ａとをウェット・オン・ウェット塗装するに際して、クリア塗料Ａが塗着された後にそれぞれ異なる焼付条件で焼付乾燥を行なうことで得られた中上塗り板Ｂ又はＤについての評価をあらわしている。クリア塗料としては、実施例１〜３２と同様に、樹脂のＳＰが９．６であるクリア塗料Ａを用いた。 Examples 1 to 32 shown in Table 1 differ from each other after the clear paint A is applied when the water-based base paint A or B and the clear paint A are wet-on-wet coated on the intermediate paint A. The evaluation about the intermediate | middle top coat board A or C obtained by baking drying on baking conditions is represented. As the clear paint, clear paint A having a resin SP of 9.6 was used. In Examples 33 to 64 shown in Table 2, when the water-based base paint A or B and the clear paint A are wet-on-wet coated on the intermediate paint B, the clear paint A is applied. The evaluation about the intermediate | middle top coating board B or D obtained by performing baking drying on different baking conditions is shown, respectively. As the clear paint, clear paint A having a resin SP of 9.6 was used as in Examples 1-32.
他方、表３に示す比較例Ｒ１〜Ｒ２８は、中塗り塗料Ａ又はＢ上に、水性ベース塗料Ａ又はＢとクリア塗料Ａ又はＢとをウェット・オン・ウェット塗装するに際して、クリア塗料Ａ又はＢが塗着された後にそれぞれ異なる焼付条件で焼付乾燥を行なうことで得られた中上塗り板Ａ〜Ｄについての評価をあらわしている。比較例Ｒ１〜Ｒ２４では、クリア塗料として、実施例１〜６４と同様に、樹脂のＳＰが９．６であるクリア塗料Ａを用い、他方、比較例Ｒ２５〜Ｒ２８では、樹脂のＳＰが１０．５であるクリア塗料Ｂを用いた。 On the other hand, in Comparative Examples R1 to R28 shown in Table 3, when the water-based base paint A or B and the clear paint A or B are wet-on-wet coated on the intermediate paint A or B, the clear paint A or B The evaluation about the intermediate | middle top coating board AD obtained by baking and drying on different baking conditions after each is applied is shown. In Comparative Examples R1 to R24, the clear paint A having a resin SP of 9.6 was used as the clear paint, as in Examples 1 to 64. On the other hand, in Comparative Examples R25 to R28, the resin SP was 10. Clear paint B, 5 was used.
実施例１〜６４では、樹脂のＳＰが９．６であるクリア塗料Ａの塗着後の焼付乾燥に際し、焼付温度５０〜１１０℃で５〜１５分にわたる第１の焼付乾燥が行なわれた後に、焼付温度９０〜１５０℃で１０〜３５分にわたる第２の焼付乾燥が行なわれ、全ての評価項目について「◎」又は「○」の評価が得られた。特に、全ての評価項目について「◎」が得られた実施例８，２４，４０，５６をみると、樹脂のＳＰは９．６、第１の焼付乾燥での焼付温度は８０℃、また、その焼付時間は１５分、第２の焼付乾燥での焼付温度は１３０℃、また、その焼付時間は２０分であった。 In Examples 1 to 64, after the first baking and drying were performed at a baking temperature of 50 to 110 ° C. for 5 to 15 minutes during the baking and drying after the application of the clear paint A having a resin SP of 9.6. The second baking and drying were performed at a baking temperature of 90 to 150 ° C. for 10 to 35 minutes, and “◎” or “○” was obtained for all evaluation items. In particular, in Examples 8, 24, 40, and 56 in which “◎” was obtained for all the evaluation items, the SP of the resin was 9.6, the baking temperature in the first baking and drying was 80 ° C., The baking time was 15 minutes, the baking temperature in the second baking drying was 130 ° C., and the baking time was 20 minutes.
これに対して、比較例Ｒ１〜Ｒ２８では、クリア塗料Ａ又はＢの塗着後の焼付乾燥に際し、焼付温度４０〜１３０℃で３分〜１５分にわたる第１の焼付乾燥が行なわれた後に、焼付温度７０〜１７０℃で５〜３５分にわたる第２の焼付乾燥が行なわれ、評価項目の１つ又は２つについて「×」の評価が得られた。具体的に、比較例Ｒ１，Ｒ２，Ｒ７，Ｒ８，Ｒ１３，Ｒ１４，Ｒ１９，Ｒ２０をみると、第１の焼付乾燥での焼付温度が４０又は１３０℃であり、実施例１〜６４で設定された条件を満足せず、かかる例では、光輝感及びピンホール限界膜厚について良好でないという結果が得られた。また、比較例Ｒ３，Ｒ９，Ｒ１５，Ｒ２１をみると、第１の焼付乾燥での焼付時間が３分であり、実施例１〜６４で設定された条件を満足せず、かかる例では、光輝感及びピンホール限界膜厚について良好でないという結果が得られた。 On the other hand, in Comparative Examples R1 to R28, after the first baking and drying were performed at a baking temperature of 40 to 130 ° C. for 3 to 15 minutes in the baking and drying after the application of the clear paint A or B, The second baking and drying was performed at a baking temperature of 70 to 170 ° C. for 5 to 35 minutes, and an evaluation of “x” was obtained for one or two evaluation items. Specifically, looking at comparative examples R1, R2, R7, R8, R13, R14, R19, R20, the baking temperature in the first baking drying is 40 or 130 ° C., which is set in Examples 1 to 64. In such an example, the result was that the glitter and the pinhole limit film thickness were not good. Further, in Comparative Examples R3, R9, R15, and R21, the baking time in the first baking drying is 3 minutes, and the conditions set in Examples 1 to 64 are not satisfied. The result was that the feeling and the pinhole limit film thickness were not good.
更に、比較例Ｒ４，Ｒ１０，Ｒ１６，Ｒ２２をみると、第２の焼付時間での焼付温度が７０℃であり、実施例１〜６４で設定された条件を満足せず、かかる例では、硬度について良好でないという結果が得られた。また、更に、比較例Ｒ５，Ｒ１１，Ｒ１７，Ｒ２３をみると、第２の焼付時間での焼付温度が１７０℃であり、実施例１〜６４で設定された条件を満足せず、かかる例では、冷熱繰返し性について良好でないという結果が得られた。 Further, in Comparative Examples R4, R10, R16, and R22, the baking temperature at the second baking time is 70 ° C., and the conditions set in Examples 1 to 64 are not satisfied. The result was not good for. Further, in Comparative Examples R5, R11, R17, and R23, the baking temperature at the second baking time is 170 ° C., and the conditions set in Examples 1 to 64 are not satisfied. As a result, it was found that the repetitive cooling and heating was not good.
また、更に、比較例Ｒ６，Ｒ１２，Ｒ１８，Ｒ２４をみると、第２の焼付時間での焼付時間が５分であり、実施例１〜６４で設定された条件を満足せず、かかる例では、硬度について良好でないという結果が得られた。
また、更に、比較例Ｒ２５〜２８をみると、クリア塗料のＳＰが１０．５であり、実施例１〜６４で設定された条件を満足せず、かかる例では、光輝感について良好でないという結果が得られた。
Further, when the comparative examples R6, R12, R18, and R24 are viewed, the baking time in the second baking time is 5 minutes, and the conditions set in Examples 1 to 64 are not satisfied. The result was that the hardness was not good.
Further, in Comparative Examples R25 to 28, the clear paint SP was 10.5, and the conditions set in Examples 1 to 64 were not satisfied. was gotten.
以上の結果より、第１の焼付乾燥での焼付温度は光輝感及びピンホールの限界膜厚に関係しており、５０℃以上１１０℃以下である場合に、良好な光輝感及びピンホールの限界膜厚が得られると判断することができる。特に、実施例４，８，１４，２０，２４，３０，３６，４０，４６，５２，５６，６２の評価結果に基づき、良好な光輝感及びピンホールの限界膜厚を確実に得るには、７０℃以上９０℃以下（例えば８０℃）であることが好ましい。 From the above results, the baking temperature in the first baking / drying is related to the brightness and the critical film thickness of the pinhole. It can be determined that a film thickness can be obtained. In particular, on the basis of the evaluation results of Examples 4, 8, 14, 20, 24, 30, 36, 40, 46, 52, 56, and 62, it is possible to reliably obtain good glitter and pinhole limit film thickness. It is preferably 70 ° C. or higher and 90 ° C. or lower (for example, 80 ° C.).
また、第１の焼付乾燥での焼付時間は光輝感及びピンホールの限界膜厚に関係しており、５分以上である場合に、良好な光輝感及びピンホールの限界膜厚が得られると判断することができる。特に、実施例４，８，１４，２０，２４，３０，３６，４０，４６，５２，５６，６２の評価結果に基づき、良好な光輝感及びピンホールの限界膜厚を確実に得るには、１０分以上（例えば１５分）であることが好ましい。 In addition, the baking time in the first baking and drying is related to the glitter and the critical film thickness of the pinhole, and when it is 5 minutes or more, the excellent glitter and the critical film thickness of the pinhole are obtained. Judgment can be made. In particular, on the basis of the evaluation results of Examples 4, 8, 14, 20, 24, 30, 36, 40, 46, 52, 56, and 62, it is possible to reliably obtain good glitter and pinhole limit film thickness. It is preferable that it is 10 minutes or more (for example, 15 minutes).
更に、第２の焼付乾燥での焼付温度は冷熱繰返し性及び硬度に関係しており、９０℃以上１５０℃以下である場合に、良好な冷熱繰返し性及び硬度が得られると判断することができる。特に、実施例５〜１０，２１〜２６，３７〜４２，５３〜５８の評価結果に基づき、良好な冷熱繰返し性及び硬度を確実に得るには、１１０℃以上１３０℃以下（例えば１３０℃）であることが好ましい。 Furthermore, the baking temperature in the second baking and drying is related to the thermal repeatability and hardness, and when it is 90 ° C. or higher and 150 ° C. or lower, it can be determined that good cold repeatability and hardness can be obtained. . In particular, based on the evaluation results of Examples 5 to 10, 21 to 26, 37 to 42, and 53 to 58, 110 ° C. or more and 130 ° C. or less (for example, 130 ° C.) in order to reliably obtain good cooling repeatability and hardness. It is preferable that
また、更に、第２の焼付乾燥での焼付時間は硬度に関係しており、１０分以上である場合に、良好な硬度が得られると判断することができる。特に、実施例５〜１０，２１〜２６，３７〜４２，５３〜５８の評価結果に基づき、良好な硬度を確実に得るには、１５分以上（例えば２０分）であることが好ましい。 Furthermore, the baking time in the second baking drying is related to the hardness, and it can be determined that good hardness can be obtained when the baking time is 10 minutes or more. In particular, on the basis of the evaluation results of Examples 5 to 10, 21 to 26, 37 to 42, and 53 to 58, it is preferably 15 minutes or more (for example, 20 minutes) in order to reliably obtain good hardness.
また、更に、クリア塗料のＳＰは光輝感に関係しており、１０以下である場合に、良好な光輝感が得られると判断することができる。特に、良好な光輝感を確実に得るには、９以上１０以下（例えば９．６）であることが好ましい。 Further, the SP of the clear paint is related to the glitter feeling, and when it is 10 or less, it can be determined that a good glitter feeling can be obtained. In particular, it is preferably 9 or more and 10 or less (eg, 9.6) in order to surely obtain a good glitter feeling.
第１の焼付乾燥での焼付温度及び焼付時間，第２の焼付乾燥での焼付温度及び焼付時間を上記のように設定することで、ウェット・オン・ウェット塗装において、水性ベース塗料塗装後のプレヒート工程の低温化及び短縮化を行った場合若しくはプレヒート工程を省略した場合にも、焼付工程時に、水性ベース塗料中に残存する水分が突沸することを防止して、ピンホール等の塗膜欠陥の発生を抑制することができ、仕上がり塗装面の良好な外観性を確保することができる。また、ＳＰが所定値以下であるクリア塗料を用いることで、水性ベース塗料とクリア塗料との間の界面の乱れを抑制することができ、アルミフレークの配向性を維持し、仕上がり塗装面において良好な光輝感を実現することができる。 By setting the baking temperature and baking time in the first baking and drying, and the baking temperature and baking time in the second baking and drying as described above, preheating after the aqueous base coating is applied in wet-on-wet coating. Even when the process temperature is reduced and shortened or when the preheating process is omitted, the water remaining in the aqueous base paint is prevented from suddenly boiling during the baking process, and coating defects such as pinholes are prevented. Generation | occurrence | production can be suppressed and the favorable external appearance of a finished coating surface can be ensured. In addition, by using a clear paint whose SP is less than or equal to a predetermined value, it is possible to suppress the disturbance of the interface between the water-based base paint and the clear paint, and maintain the orientation of the aluminum flakes, which is good on the finished painted surface Radiant feeling can be realized.
なお、本発明は、例示された実施形態に限定されるものでなく、本発明の要旨を逸脱しない範囲において、種々の改良及び設計上の変更が可能であることは言うまでもない。 It should be noted that the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the scope of the present invention.
Ｘ…従来の焼付条件及びＳＰが１０を超えるクリア塗料樹脂を用いて得られる、クリア塗料の塗着時から焼付完了時までの配向性の変化
Ｙ…本発明の焼付条件及びＳＰが１０を超えるクリア塗料樹脂を用いて得られる、クリア塗料の塗着時から焼付完了時までの配向性の変化
Ｚ…本発明の焼付条件及びＳＰが１０以下であるクリア塗料樹脂を用いて得られる、クリア塗料の塗着時から焼付完了時までの配向性の変化
X: change in orientation from the time of applying a clear paint to the time of completion of baking obtained by using a conventional paint condition and a clear paint resin having an SP of more than 10 Y: the condition of firing and SP of the present invention exceed 10. Change in orientation obtained from application of clear paint to completion of baking obtained by using clear paint resin Z: Clear paint obtained by using clear paint resin of baking condition of present invention and SP of 10 or less In orientation from the time of coating to the completion of baking
Claims (7)
上記第２の塗料中に含有される樹脂の極性を示すＳＰを１０以下に設定するとともに、
焼付乾燥に際して、焼付温度５０℃以上１１０℃以下で５分以上にわたる第１の焼付乾燥を行った後に、焼付温度９０以上１５０℃以下で１０分以上にわたる第２の焼付乾燥を行なうことを特徴とする塗装乾燥方法。 In the paint drying method in which the second paint is wet-on-wet applied to the first paint made of a water-based paint and baked and dried.
While setting SP indicating the polarity of the resin contained in the second paint to 10 or less,
In the baking drying, the first baking drying is performed for 5 minutes or more at a baking temperature of 50 ° C. to 110 ° C., and then the second baking drying is performed for 10 minutes or more at a baking temperature of 90 to 150 ° C. How to dry the paint.
The coating drying method according to any one of claims 1 to 6, wherein the first baking drying is performed for 10 minutes or more.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009028576A (en) * | 2007-07-24 | 2009-02-12 | Toyota Motor Corp | Method of forming multilayered coated film |
| JP2009034667A (en) * | 2007-07-06 | 2009-02-19 | Toyota Central R&D Labs Inc | Coating method, and coated object prepared by above method |
| JP2010075839A (en) * | 2008-09-25 | 2010-04-08 | Honda Motor Co Ltd | Method and facility for producing coated material |
| JP2010082535A (en) * | 2008-09-30 | 2010-04-15 | Toyota Central R&D Labs Inc | Coating method and coated body obtained by the same |
| US8795835B2 (en) | 2007-07-06 | 2014-08-05 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Coating method and coated article obtained by the same |
| KR101772690B1 (en) | 2015-12-31 | 2017-08-29 | 김종구 | Automatic multi-spray coating system |
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2004
- 2004-01-28 JP JP2004020056A patent/JP2005211756A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009034667A (en) * | 2007-07-06 | 2009-02-19 | Toyota Central R&D Labs Inc | Coating method, and coated object prepared by above method |
| US8795835B2 (en) | 2007-07-06 | 2014-08-05 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Coating method and coated article obtained by the same |
| JP2009028576A (en) * | 2007-07-24 | 2009-02-12 | Toyota Motor Corp | Method of forming multilayered coated film |
| JP2010075839A (en) * | 2008-09-25 | 2010-04-08 | Honda Motor Co Ltd | Method and facility for producing coated material |
| JP2010082535A (en) * | 2008-09-30 | 2010-04-15 | Toyota Central R&D Labs Inc | Coating method and coated body obtained by the same |
| KR101772690B1 (en) | 2015-12-31 | 2017-08-29 | 김종구 | Automatic multi-spray coating system |
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