Zinc phosphate-containing surface conditioning agent phosphate conversion-treated steel plate and painted steel plate, and zinc phosphate dispersion

Abstract

A zinc phosphate-containing surface conditioning agent to be used for surface conditioning as pretreatment for zinc phosphate conversion coating of a metallic material, which contains from 500 to 20,000 ppm of zinc phosphate and which has a pH of from 3 to 11, wherein said zinc phosphate has an average particle size of at most 3 μm and D 90 of at most 4 μm.

What is claimed is:  
     
         1 . A zinc phosphate-containing surface conditioning agent to be used for surface conditioning as pretreatment for zinc phosphate conversion coating of a metallic material, which contains from 500 to 20,000 ppm of zinc phosphate and which has a pH of from 3 to 11, wherein said zinc phosphate has an average particle size of at most 3 μm and D 90  of at most 4 μm.  
     
     
         2 . A process for producing a phosphate conversion-treated steel plate, which comprises immersing a metallic material in the zinc phosphate-containing surface conditioning agent as defined in  claim 1 , followed by phosphate conversion treatment.  
     
     
         3 . A process for producing a painted steel plate, which comprises immersing a metallic material in the zinc phosphate-containing surface conditioning agent as defined in  claim 1 , followed by phosphate conversion treatment and further by painting.  
     
     
         4 . A zinc phosphate dispersion to be used for preparation of a zinc phosphate-containing surface conditioning agent to be used for surface conditioning as pretreatment for zinc phosphate conversion coating of a metallic material, which contains from 0.5 to 50 wt % of zinc phosphate and which has a pH of from 3 to 11, wherein said zinc phosphate has an average particle size of at most 3 μm and D 90  of at most 4 μm.