Coating line and process for forming a multilayer component coating on a substrate

Abstract

A process for forming a multilayer composite coating on a substrate is provided. The process includes forming an electrodeposition coating layer on the substrate by electrodeposition of a curable electrodepositable coating composition over at least a portion of the substrate. Optionally, the coated substrate is heated to a temperature and for a time sufficient to cure the electrodeposition coating layer. A basecoating layer is formed on the electrodeposition coating layer by depositing an aqueous curable basecoating composition directly onto at least a portion of the electrodeposition coating layer. Optionally, the basecoating layer is dehydrated. A top coating layer is formed on the basecoating layer by depositing a curable top coating composition which is substantially pigment-free directly onto at least a portion of the basecoating layer. The top coating layer, the basecoating layer, and, optionally, the electrodeposition coating layer are cured simultaneously.

1 . A process for forming a multilayer composite coating on a substrate, the process comprising: forming a first basecoating layer on the substrate by depositing an aqueous curable first basecoating composition over at least a portion of the substrate with no intervening primer-surfacer layer, optionally, dehydrating the first basecoating layer; forming a second basecoating layer on the first basecoating layer by depositing an aqueous curable second basecoating composition, which is the same or different from the first basecoating composition, directly onto at least a portion of the first basecoating layer, optionally, dehydrating the second basecoating layer; forming a top coating layer on the second basecoating layer by depositing a curable top coating composition which is substantially pigment-free directly onto at least a portion of the second basecoating layer; and curing the top coating layer, the second basecoating layer, and the first basecoating layer simultaneously. 
     
     
         2 . The process of  claim 1 , wherein the substrate is a metallic substrate. 
     
     
         3 . The process of  claim 2 , wherein the substrate is a non-metallic substrate. 
     
     
         4 . The process of  claim 2 , wherein the first basecoating composition is applied over a weldable primer coating layer which had been previously applied over the substrate. 
     
     
         5 . The process of  claim 4 , wherein the weldable primer coating layer is formed by depositing a weldable primer coating composition over the substrate, the weldable primer coating composition comprising: (A) a resinous binder comprising: (1) at least one functional group-containing polymer, and (2) at least one curing agent having functional groups reactive with the functional groups of (1); and (B) at least one electroconductive pigment dispersed in resinous binder (A). 
     
     
         6 . A coating line, comprising: an electrocoating zone including at least one electrodeposition bath; a basecoat zone located downstream of and adjacent to the electrocoating zone, the basecoat zone comprising a cut-in station, a first basecoat station, and a second basecoat station; and a topcoat zone located downstream of and adjacent to the basecoat zone. 
     
     
         7 . The coating line of  claim 6 , wherein the cut-in station is located upstream of the first basecoat station and the first basecoat station is located upstream of the second basecoat station. 
     
     
         8 . The coating line of  claim 6 , wherein the first basecoat station includes at least one bell applicator in flow communication with a source of a first basecoat composition comprising a first resinous binder and a first pigment composition. 
     
     
         9 . The coating line of  claim 8 , wherein the second basecoat station includes at least one gun applicator in flow communication with a source of a second basecoat composition comprising a second resinous binder and a second pigment composition, with the second pigment composition being different than the first pigment composition. 
     
     
         10 . The coating line of  claim 9 , wherein the cut-in station includes at least one applicator in flow communication with a source of the second coating composition. 
     
     
         11 . The coating station of  claim 9 , wherein the cut-in station is in flow communication with a source of a mixture of the first and second basecoat compositions. 
     
     
         12 . The coating line of  claim 6 , wherein the basecoat zone further includes at least one drying oven. 
     
     
         13 . The coating line of  claim 6 , wherein the cut-in station is located downstream of the first basecoat station and/or the second basecoat station. 
     
     
         14 . The coating line of  claim 6 , wherein there is no drying device positioned between the first and second basecoat stations.