Resin-coated metal powder, method for producing same and aqueous coating composition using same

A method for producing a resin-coated metal powder, the method comprising:

• mixing a metal powder;
• and a solution containing a hydrolyzable resin, the metal powder having a surface at least partially coated with the hydrolyzable resin,
• the hydrolyzable resin being represented by the general formula (1) described below, and having a polystyrene-equivalent numerical average molecular weight of 500 to 100,000 by gel permeation chromatography:
• wherein R1 represents a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, the linear or branched monovalent hydrocarbon group in which a part or all of hydrogen atoms may be substituted with an alkoxyalkyl group, an alkoxysilyl group, a hydroxyalkyl group, a polyoxyalkylene group, or a terminal alkyl polyoxyalkylene group,
• R3, R4, and R5 each independently represent a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms,
• R2 and R6 each independently represent a hydrogen atom or a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, and
• a and b represent numbers satisfying 0≤a<1, 0<b≤1, and a +b=1;
• and
• coating at least a part of said surface of the metal powder with the hydrolyzable resin.

A method for producing a resin-coated metal powder, the method comprising:

• mixing a metal powder and a silane coupling agent previously to obtain the metal powder treated with the silane coupling agent, the silane coupling agent having a polymerizable group having the general formula (2) described below:
• wherein R7 represents a linear or branched divalent hydrocarbon group having 1 to 10 carbon atoms, R8 and R9 represent a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, n represents an integer of 0 to 2, and R10 represents a hydrogen atom or a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms;
• and
• subjecting the metal powder treated with the silane coupling agent, a polymerizable monomer having the general formula (3) described below:
• wherein R11, R12, and R13 each independently represent a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, and R14 represents a hydrogen atom or a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms,
• and a silane coupling agent having a polymerizable group having the general formula (2) described above and/or a polymerizable monomer having the general formula (4) described below:
• wherein R15 represents a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, and R16 represents a hydrogen atom or a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms
• to radical polymerization reaction to coat at least a part of a surface of the metal powder treated with the silane coupling agent with the hydrolyzable resin to produce said resin-coated metal powder, said resin coated metal powder having a surface at least partially coated with the hydrolyzable resin,
• the hydrolyzable resin being represented by the general formula (1) described below, and having a polystyrene-equivalent numerical average molecular weight of 500 to 100,000 by gel permeation chromatography:
• wherein R1 represents a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, the linear or branched monovalent hydrocarbon group in which a part or all of hydrogen atoms may be substituted with an alkoxyalkyl group, an alkoxysilyl group, a hydroxyalkyl group, a polyoxyalkylene group, or a terminal alkyl polyoxyalkylene group,
• R3, R4, and R5 each independently represent a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms,
• R2 and R6 each independently represent a hydrogen atom or a linear or branched monovalent hydrocarbon group having 1 to 10 carbon atoms, and
• a and b represent numbers satisfying 0≤a<1, 0<b≤1, and a +b=1.