Abstract: Copper microparticles that are fine and contain substantially none of agglomerated particles. For example, there are provided copper microparticles of 0.005 to 2.0 ?m average particle diameter (D) as measured by an electron microscope, 0.005 to 2.0 ?m average particle diameter (d) as measured by a dynamic light scattering particle size distribution measuring apparatus and 0.7 to 2 d/D ratio. There is provided a process comprising mixing a divalent copper oxide with a reducing agent in the presence of a complexing agent and a protective colloid in a liquid medium to thereby produce copper microparticles without formation of a univalent copper oxide from the divalent copper oxide.

Abstract: An object of the present invention is to provide: a light stabilizer emulsion composition which has good long-term storage stability and does not deteriorate various physical properties of a coating film to be formed even when the composition is added to an aqueous coating agent composition; and an aqueous coating agent composition containing the light stabilizer emulsion composition. The light stabilizer emulsion composition of the present invention is characterized by containing: an emulsifier having as a hydrophilic group a polyether chain obtained by a reaction between two or more kinds of alkyleneoxides and having as a hydrophobic group a hydrocarbon group having 1 to 30 carbon atoms; at least one of a light stabilizer and a UV absorber; and water. Further, the aqueous coating agent composition of the present invention is characterized by containing the light stabilizer emulsion composition.

Abstract: Ceramic or base metal particles of a mean diameter of 0.01 to 0.5 .mu.m having thereon bactericidal metal particles of a mean diameter of 0.0001 to 0.1 .mu.m (the mean diameter of the bactericidal metal particles is smaller than the mean diameter of the ceramic or base metal particles) are effective to give a bactericidal surface of a plastic article when they are embedded on the surface under the condition that a portion of the particle is exposed over the surface of the plastic article. The above ceramic or base metal particles having the bactericidal metal particles on their surface are also effective to sterilize liquid or solid material.

Abstract: A coated palladium fine powder comprising palladium particles of a mean particle size in the range of 0.1 to 1.0 .mu.m which are coated with nickel or alloy of nickel with other metal are employable, optionally in combination with palladium particles or palladium-coated ceramic particles of a mean particle size in the range of 0.1 to 1.0 .mu.m, for preparing an electroconductive paste.