Core-shell composite inorganic metal oxides and method of preparing for prevention of thermal oxidative degradation in polymer and resin compositions
This invention relates to products of aqueous and other chemical synthetic routes for encapsulation of a core material with an inorganic shell and finished compositions of a core-shell particulate material for application in thermoplastic, thermoset, and coatings resins prior to compounding or application or subsequent thermal processing steps. Disclosed is a composition of particles containing a shell of inorganic oxides or mixed-metal inorganic oxides and a core material of complex inorganic colored pigment, laser direct structuring additives, laser marking, or other beneficial metal oxides, metal compounds, or mixed-metal oxide materials, wherein the shell material is comprised of any single oxide or combination of oxides is taught. Preferred elements of composition for the shell are oxides and silicates of B, Ni, Zn, Al, Zr, Si, Sn, Bi, W, Mo, Cr, Mg, Mn, Ce, Ti, and Ba (or mixtures thereof). Applications may include, but are not limited to, coatings or plastic articles or materials for molded interconnect devices, durable goods, housings, assemblies, devices, and articles that are to be exposed to additional thermal processing. The resulting core-shell materials function in plastic and coatings formulations by minimizing or eliminating detrimental interactions with the resins and metal containing additives resulting in loss of mechanical properties.
1. A method of processing a plastic article where the plastic article comprises (a) from about 60% to about 98% of a plastic resin, (b) from about 0.25% to about 16% of a core-shell composite material comprising a core made up on a material selected from one or more metal oxides, metal compounds, mixed metal oxides, and mixtures thereof, and a shell which completely encapsulates the core and is selected from B, Ti, Ni, Al, Zr, Co, Mg, Mo, Zn, Si, Sn, Br, Cr, W, Ce, Mn, Ba and mixtures thereof, and (c) from 0% to about 24% of fillers and additives; wherein the core component (b) includes a laser direct structuring (LDS) additive; and said plastic article is subjected to a laser beam, followed by an electroless metal deposition step wherein the metal deposited is conformational to the laser irradiated area.
2. The method according to claim 1 wherein the core material is selected from CuO, Cu 2 O, CuCrO 4 , Cu(II) hydroxide phosphate, basic copper phosphate, and mixtures thereof.
3. The method according to claim 2 wherein the shell is comprised of a silica material.
4. The method according to claim 1 wherein the metal deposited comprises a metal selected from copper, gold, nickel, silver, zinc, tin and mixtures thereof.
5. The method according to claim 4 wherein the metal deposited comprises copper.
6. The method according to claim 1 wherein the core has a mean particle size of from about 0.05 μm to about 50 μm.
7. The method according to claim 6 wherein the shell is selected from SnO 2 , NiO, SiO x (wherein x is any integer commonly designated in the class of amorphous silicas), SiO 2 , Zn 2 SiO 4 , SiO 4 , Bi 2 O 3 , ZnO, WO 3 , Cr 2 O 3 , ZrO 2 , MoO 3 , TiO 2 , Ni 2 SiO 4 , and mixtures thereof.
8. The method, according to claim 7 wherein the core-shell composite includes one or more additional shells which do not have to completely encapsulate the core.
9. The method according to claim 8 wherein the core-shell composite comprises from about 0.5% to about 40% by weight of the shell, with the balance of the composite being the core.
10. The method according to claim 9 wherein, in the core-shell composite, the core material is selected from oxides selected from V, Zr, Bi, Ba, Cu, Rh, Ag, Mo, Zn, Nd, Co, Pr, La, Mg, Al, Ru, Si, Ti, Cr, Ce, In, Mn, Sr, Mo, Ni, Pd, Pt, Sn, Fe, Sb, W and Ca, and a metal compound selected from hydroxides, sulfides, phosphates, cyanates, thiocyanates, oxalates, and mixtures thereof.