Hollow spheres
AssigneeMinnesota Mining and Manufacturing Company
InventorWarren R. Beck
Life of this patent
Estimating the term…
Abstract
Novel hollow spheres are made by tumbling solidifiable liquid globules of binder material in a mass of minute solid discrete free-flowing particles. The particles serve as a parting agent during the tumbling action, keeping the globules separate from one another, and become at least partially absorbed into the globules. As the tumbling proceeds, the globules are first converted to a hollow, generally spherical condition by the action of a volatile void-forming agent in the binder material, and then solidify. The new hollow spheres made by this process have a solidified seamless exterior wall that carries at least on its exterior surface partially embedded, partially protruding parting agent particles, and usually is filled throughout at least a major portion of its thickness by parting agent particles.
Claims32
A free-flowing mass of hollow spheres where individually are about 2 centimeters or less in diameter and comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space, the exterior wall of the individual spheres being a composite structure that comprises a single thickness of binder material and a plurality of solid particles held by the binder material;
- at least a major portion of said thickness of binder material being filled by the particles, with a portion of the particles being totally embedded in the binder material, and with the outermost particles being only partially embedded in the binder material and partially exposed whereby they form the exterior surface of the sphere that contacts adjacent spheres in the mass.
A free-flowing mass of hollow spheres which individually are about 2 centimeters or less in diameter and comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space;
- the exterior wall of the individual spheres comprising a layer of binder material and a plurality of hard irregular abrasive granules, at least some of which are partially embedded in the binder material and partially exposed whereby they form the exterior surface of the sphere that contacts adjacent spheres in the mass.
A free-flowing mass of hollow spheres which individually are about 2 centimeters or less in diameter and comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space, the exterior wall of the spheres being a composite structure that comprises a single thickness of inorganic binder material and a plurality of byproduct-fine particles held by the binder material;
- at least a major portion of said thickness of binder material being filled by the particles, with a portion of the particles being totally embedded in the binder material, and with the outermost particles being only partially embedded in the wall and partially exposed whereby they form the exterior surface of the sphere that contacts adjacent spheres in the mass.
A free-flowing mass of resiliently compressible hollow spheres which individually are about 2 centimeters or less in diameter and comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space, the exterior wall of the individual spheres comprising a layer of elastomeric binder material and elastomeric particles, at least some of which are partially embedded in the binder material and partially exposed whereby they form the exterior surface of the sphere that contacts adjacent spheres in the mass.
A free-flowing mass of hollow spheres averaging between about 0.05 and 2 centimeters in diameter prepared by
- (A) tumbling together and thoroughly mixing (1) solidifiable liquid globules of binder material that contain a source of void-forming agent adapted to evolve as a gas and convert the liquid globules to a hollow condition and (2) a mass of minute discrete free-flowing parting agent particles that are wetted by, and at least partially absorbed into, the liquid globules during the tumbling action;
- sufficient parting agent particles being present so that any portion of liquid globules uncovered by parting agent particles tumble against discrete unabsorbed parting agent particles;
- (B) providing conditions during the tumbling action, and tumbling for a sufficient time, for the void-forming agent to evolve as a gas and form a central interior space within the liquid globules and for the thus-hollowed liquid globules to solidify;
- and
- (C) collecting the converted globules after they have solidified to a shape-retaining condition;
- said spheres having a solidified seamless spherical exterior wall that defines and encloses a central interior space and that comprises a single thickness of binder material and a plurality of parting agent particles, at least a major portion of said thickness being filled by the particles, with the outermost particles being only partially embedded in the wall and partially exposed whereby they form the exterior surface of the sphere that contacts adjacent spheres in the mass.
A method for preparing a mass of hollow spheres comprising:
- (A) tumbling together and thoroughly mixing (1) solidifiable liquid globules of binder material that contain a source of void-forming agent adapted to evolve as a gas and convert the liquid globules to a hollow condition and (2) a mass of minute discrete free-flowing parting agent particles that are wetted by, and at least partially absorbed into, the liquid globules during the tumbling action;
- sufficient parting agent particles being present so that any globules uncovered by parting agent particles tumble against discrete unabsorbed parting agent particles;
- (B) providing conditions during the tumbling action, and tumbling for a sufficient time, for the void-forming agent to evolve as a gas form a central interior space within the liquid globules and for the thus-hollowed liquid globules to solidify;
- and
- (C) collecting the converted globules after they have solidified to a shape-retaining condition.
Dependencies are inferred from the claim text.