초록 ▼

Hollow microspheres are made by a process which comprises forming a film of a dispersed particle film-forming composition (containing dispersed particles, a binder, a film stabilizing agent and a continuous liquid phase) across a coaxial blowing nozzle, applying a blowing gas at a positive pressure

Hollow microspheres are made by a process which comprises forming a film of a dispersed particle film-forming composition (containing dispersed particles, a binder, a film stabilizing agent and a continuous liquid phase) across a coaxial blowing nozzle, applying a blowing gas at a positive pressure on the inner surface of the dispersed particle composition film to blow the film and form, in the region of the coaxial blowing nozzle orifice, hollow dispersed particle microspheres having stable film walls, removing the hollow microspheres, treating them to bring dispersed particles into point to point contact and harden them to obtain hollow green microspheres, and subsequently subjecting them to a sufficiently high temperature for a sufficient period of time to remove the continuous liquid phase and to sinter the dispersed particles at their points of contact to form within the walls of said hollow microspheres interconnecting voids that are continuous from the outer wall surface to the inner wall surface of the hollow microspheres, and to obtain hollow porous microspheres having substantially uniform void content and substantially uniform distribution of the voids in their walls.

대표청구항 ▼

A method for making hollow porous microspheres of 200 to 10,000 microns diameter and of 1 to 1000 microns wall thickness from a stable dispersion of a dispersed particle film forming composition, said composition comprising dispersed particles in a continuous liquid phase, said method comprising fee

A method for making hollow porous microspheres of 200 to 10,000 microns diameter and of 1 to 1000 microns wall thickness from a stable dispersion of a dispersed particle film forming composition, said composition comprising dispersed particles in a continuous liquid phase, said method comprising feeding said dispersed particle composition and a blowing gas to a coaxial blowing nozzle, said coaxial blowing nozzle having an inner coaxial nozzle for said blowing gas and an outer coaxial nozzle for said dispersed particle composition and a coaxial blowing nozzle orifice, feeding said blowing gas to said inner nozzle, feeding said dispersed particle composition to said outer nozzle to blow and form, in the region of said coaxial blowing nozzle orifice, hollow dispersed particle composition microspheres having stable film walls, removing said hollow microspheres from the region of said coaxial blowing nozzle orifice, surface tension forces acting on said hollow microspheres to cause said hollow microspheres to form a spherical shape, treating said removed hollow microspheres to bring the dispersed particles into point to point contact and to harden them to obtain hollow green microspheres; and subjecting said hollow green microspheres to a sufficiently high temperature for a sufficient period of time to remove the continuous liquid phase from the hollow green microspheres and to sinter the dispersed particles at their points of contant and to form within the walls of said hollow microspheres interconnecting voids that are continuous from the outer wall surface to the inner wall surface of the hollow microspheres, and to obtain hollow porous microspheres having substantially uniform void content and substantially uniform distribution of the voids in the walls of the microspheres. The method of claim 1 wherein the sintered hollow porous microspheres are treated with a sol dispersion comprising small solid particles dispersed in a liquid to place the sol dispersion in the interconnecting voids in the walls of the hollow microspheres, the thus treated hollow microspheres are heated at elevated temperature to have the small solid particles from the sol dispersion link-up and form a rigid porous latticework of the small solid particles in the interconnecting voids and to remove the liquid in the sol dispersion from the microspheres wall voids to form micro pores in the walls of the microspheres.