Nippon Paint Compnay, Ltd.

Toyota Jidosha Kabushiki Kaisha

Satoru Uchidoi

Mitsuo Yamada

Yoshio Kojima

Hiroyuki Sakamoto

Ichiro Kawakami

Takao Saito

Satoshi Kodama

Seiji Yokoi

Sho Takeshita

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

A method for forming double-layer coatings excellent in smoothness and resistant to yellowing is provided which comprises electrodepositing a cationic electrodeposition coating composition to form an uncured cationically electrodeposited coating, applying an intermediate coating composition to said uncured coating to form an uncured intermediate coating, and heating both uncured coatings simultaneously, said cationic electrodeposition coating composition containing a sulfonium group- and propargyl group-containing resin composition.

Method for forming double-layer coatings, method for forming multilayer coatings, and multilayer coatings

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Osaka-fu, Japan

Satoru Uchidoi