Nippon Paint Compnay, Ltd.

Toyota Jidosha Kabushiki Kaisha

Yoshio Kojima

Mitsuo Yamada

Kenshiro Tobinaga

Satoru Uchidoi

Hiroyuki Kageyama

Hisaki Tanabe

Hiroharu Ohsugi

Tatsuo Yoshida

Ryoichi Murakami

Makoto Ando

Satoshi Kodama

Hirotaka Kanato

Atsushi Ohgaki

Seiji Yokoi

Shoki Tsuji

Toshiaki Sakamoto

The present invention provides a lead-free cationic electrodeposition coating composition which contains an aqueous medium, a binder resin composed of a cationic epoxy resin and a blocked isocyanate curing agent dispersed or dissolved in the aqueous medium, a neutralizing acid in order to neutralize the cationic epoxy resin, an organic solvent, and a metal catalyst, wherein the electrodeposition coating composition has a volatile organic content of 1% by weight or less, a metal ion content of 500 ppm or less, a neutralizing acid amount of 10 to 30 mg equivalent based on 100 g of binder resin solid content. The lead-free cationic electrodeposition coating composition has high throwing power, and exert a little influence on the environment due to its low VOC, low metal ion content, and reduced consumption of a coating composition itself.

Lead-free cationic electrodeposition coating composition, and electrodeposition coating process

With the use of a lead-free cationic electrodeposition coating composition containing a sulfonium-modified epoxy resin, an amine-modified novolak-type epoxy resin, and a blocked isocyanate curing agent as a binder resin, wherein the content of volatile organic components is 1% by weight or less, the coating liquid conductivity is 1000 to 2500 &#x3bc;S/cm, and the minimum film-forming temperature of the coated layer electrodeposited on an object to be coated is 20 to 35&#xb0; C., electrodeposition coating is carried out at or above the temperature which is lower by 2&#xb0; C. than the minimum film-forming temperature and at or below the temperature which is higher by 6&#xb0; C. than the minimum film-forming temperature.

Electrodeposition coating method using lead-free cationic electrodeposition coating composition

Disclosed is a three coat one bake coating process for forming an intermediate coated film, a base coated film and a clear coated film on an electrodeposition coated film. The electrodeposition coating composition is a lead-free cationic electrodeposition coating composition which has a volatile organic content of 1% by weight or less, a metal ion content of 500 ppm or less, a neutralizing acid amount of 10 to 30 mg equivalent based on 100 g of binder resin solid content. The intermediate coating composition and/or the base coated composition comprises a specific amount of a nonaqueous dispersion resin as a resin component. In the coating process, a baking step is omitted from the conventional intermediate coating process, or from the conventional base coating process.

Process for forming layered coated film, and layered coated film

Cathodic electrodeposition paints of the type in which a cationically modified epoxy resin is crosslinked with a blocked polyisocyanate crosslinker are disclosed. The paint contains a cationically modified epoxy resin having at least one oxazolidone ring in the molecule and a Tg ranging between 0.degree. C. and 35.degree. C., and a blocked alicyclic polyisocyanate. The use of lead based anticorrosive pigments may be eliminated or substantially reduced. When the alicyclic polyisocyanate is a bicycloalkane polyisocyanate, the use of organic solvent may also be reduced.

Cathodic electrodeposition paint

The present invention provides a cationic electrodeposition coating composition which satisfies both stability of paint with time and corrosion resistance when baked at low-temperature. A cationic electrodeposition coating composition comprises:

Cationic electrodeposition coating composition

The present invention provides a paint film with fewer craters and indentations, while maintaining performance as an electrodeposition paint. The electrodeposition paint composition contains an aqueous dispersing system containing an electrodepositable resin and a block polymer containing polysiloxane units and polyalkylene oxide units.

Electrodeposition paint composition containing

A cathodic electrodeposition paint containing as a binder resin an amine-epoxy resin adduct and a blocked polyisocyanate crosslinker is disclosed. The binder resin and the crosslinker are emulsified in an aqueous medium containing a neutralizing agent with the aid of amine adduct of a monoepoxide compound having a hydrophobic group or block. Not only the amine-monoepoxide adduct functions as a surfactant but also it is deposited electrically and then cured with the crosslinker integrally with the binder resin.

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Nara, Japan

Yoshio Kojima