An object of the present invention is to provide a method for forming a multilayer coating film, the method capable of achieving excellent finished appearance and excellent corrosion resistance without affecting electrodeposition coatability even when a part or all of the water-washing step is omitted after chemical conversion treatment, and to provide a coated article. The invention provides a method for forming a multilayer coating film, comprising forming a chemical conversion coating film and an electrodeposition coating film on a metal substrate by Step 1 of immersing a metal substrate in a chemical conversion treatment solution to form a chemical conversion coating film, and Step 2 of omitting a part or all of the water-washing step, and performing electrodeposition coating on the metal substrate using a cationic electrodeposition coating composition to form an electrodeposition coating film, wherein the chemical conversion treatment solution contains less than 500 ppm of sodium ions on a mass basis, and hexafluorozirconic acid. The chemical conversion treatment solution preferably contains no less than 5 ppm to less than 50 ppm of sodium ions, no less than 5 ppm to less than 90 ppm of calcium ions, less than 100 ppm of potassium ions, and less than 90 ppm of magnesium ions, on a mass basis; and is used continuously.

The invention provides a method of improving the corrosion resistance of a metal substrate. The method comprises: (a) electrophoretically depositing on the substrate a curable electrodepositable coating composition to form a coating over at least a portion of the substrate, and (b) heating the substrate to a temperature and for a time sufficient to cure the coating on the substrate. The electrodepositable coating composition comprises a resinous phase dispersed in an aqueous medium, the resinous phase comprising: (1) an ungelled active hydrogen-containing, cationic salt group-containing resin electrodepositable on a cathode; (2) an at least partially blocked polyisocyanate curing agent; and (3) a pigment component comprising an inorganic, platelike pigment having an average equivalent spherical diameter of at least 0.2 microns. The electrodepositable coating composition demonstrates a pigment-to-binder ratio of at least 0.5. The coating composition contains less than 8 percent by weight of a grind vehicle.

An electrocoating composition and a coating formed from the composition are described herein. The electrocoating composition includes at least an epoxy resin component, an isocyanate-functional component and a silica-based additive. The coating shows about 40 to 70% reduction in edge corrosion relative to a conventional coating.

An electrocoat system for electrodeposition is described. The system includes an inorganic bismuth-containing compound or a mixture of inorganic and organic bismuth-containing compounds. The system demonstrates a high degree of crosslinking and produces a cured coating with optimal crosslinking and corrosion resistance.

The present invention relates to a cationic electrodeposition coating composition containing a resin emulsion containing an aminated resin (A) and a blocked isocyanate curing agent (B), characterized in that a deposited electrodeposition coating film of the cationic electrodeposition coating composition has a coating film viscosity in a range of 5,000 to 1,000,000 mPa.Math.s at 110 C., and a portion resulting from removal of a resin component from the deposited electrodeposition coating film of the cationic electrodeposition coating composition has a polarity term in a range of 2 to 30 mN/m.

A problem to be solved by the present invention is to provide a method for forming a multilayer coating film, the method being capable of achieving excellent finished appearance and excellent corrosion resistance without affecting electrodeposition coatability even when a part or all of the water-washing step is omitted after chemical conversion treatment, and to provide a coated article. The invention provides a method for forming a multilayer coating film, comprising forming a chemical conversion coating film and an electrodeposition coating film on a metal substrate by Step 1 of immersing a metal substrate in a chemical conversion treatment solution to form a chemical conversion coating film, and Step 2 of omitting a part or all of the water-washing step, and performing electrodeposition coating on the metal substrate using a cationic electrodeposition coating composition to form an electrodeposition coating film, wherein when the electrodeposition coating is performed in Step 2, the solution adhered to and/or deposited on the metal substrate has an electrical conductivity of less than 10,000 S/cm.

An electrocoating composition is provided herein. The electrocoating composition includes an aqueous carrier. The electrocoating composition further includes a film forming binder. The film forming binder includes an epoxy-amine adduct and a blocked polyisocyanate crosslinking agent. The electrocoating composition further includes an anti-crater agent selected from the group of a polyester resin dispersion, a polyacrylate resin dispersion, and a combination thereof. The electrocoating composition further includes a supplemental anti-crater agent including a polyether modified polysiloxane.

The present technology relates generally to aqueous dispersion or emulsion compositions that include a polymeric binder resin and an ether amine. Specifically, the polymeric binder resin includes acid functional groups, at least a portion of which are neutralized by the ether amine such that the polymeric binder resin is dissolved or dispersed in the water, provided that the polymeric binder resin is not a polyurethane and the ether amine is a compound of formula I: wherein R.sup.1 and R.sup.2 are independently C.sup.1-C.sup.4 alkyl or C.sup.3-C.sup.4 cycloalkyl group; or R.sup.1 and R.sup.2, together with the nitrogen to which they are attached, form a C.sup.4-C.sup.5 membered heterocycloalkyl ring; A is a C.sup.1-C.sup.6 alkylene or C.sup.1-C.sup.6 cycloalkylene ring; and R.sup.3 is C.sup.1-C.sup.4 alkyl or C.sup.3-C.sup.4 cycloalkyl group; provided that the compound of formula I contains no more than 10 carbons.

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The invention provides a method of improving the corrosion resistance of a metal substrate. The method comprises: (a) electrophoretically depositing on the substrate a curable electrodepositable coating composition to form a coating over at least a portion of the substrate, and (b) heating the substrate to a temperature and for a time sufficient to cure the coating on the substrate. The electrodepositable coating composition comprises a resinous phase dispersed in an aqueous medium, the resinous phase comprising: (1) an ungelled active hydrogen-containing, cationic salt group-containing resin electrodepositable on a cathode; (2) an at least partially blocked polyisocyanate curing agent; and (3) a pigment component comprising an inorganic, platelike pigment having an average equivalent spherical diameter of at least 0.2 microns. The electrodepositable coating composition demonstrates a pigment-to-binder ratio of at least 0.5. The coating composition contains less than 8 percent by weight of a grind vehicle.

The present invention provides a cationic electrodeposition coating composition that has both good anti-cissing property and good coating film appearance. This is a cationic electrodeposition coating composition containing a silicone compound (A) having an SP value of more than 10.5 and 15.0 or less, and a film forming resin (B), wherein the silicone compound (A) is contained in an amount of 0.01 parts by mass or more and 4.5 parts by mass or less per 100 parts by mass of the resin solid content of the film forming resin (B). For example, the silicone compound (A) is at least one species selected from the group consisting of a polyether modified silicone compound (A-1), a polyester modified silicone compound (A-2), and a polyacrylic modified silicone compound (A-3).