Method of making uniformly-sized expandable polymeric particles
AssigneeCellofoam A.G.
InventorStuart B. Smith
Life of this patent
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Abstract
A method of making expandable polymeric particles having a uniform size comprising the size classification of partially polymerized particles and subsequent full polymerization and impregnation with blowing agent of only those particles of a desired size.
Claims15
In a method of making expandable polymeric particles by way of suspension polymerization, the improvement of achieving expandable polymeric particles falling within a desired size range comprising the steps of:
- (a) interrupting said suspension polymerization at the completion of a first stage at which time the polymerization of the polymerizable material is not more than 80% complete yet forms particles having sufficient physical integrity to withstand size classification;
- (b) classifying said particles by size to yield partially polymerized particles falling within a desired size range;
- (c) completing the polymerization of said desirably-sized partially polymerized particles during a second stage suspension polymerization;
- and
- (d) impregnating the desirably-sized particles with blowing agent.
A method of making expandable polymeric particles from polymerizable material comprising the steps:
- (a) conducting a first stage suspension polymerization of said polymerizable material to a point where the particles so-formed have sufficient physical integrity to withstand size classification but before the polymerization is more than 80% complete;
- (b) classifying the partially polymerized particles into particles of desired size and particles of undesirable size;
- (c) conducting a second stage suspension polymerization of said desirably-sized partially polymerized particles and impregnating the particles with blowing agent in the course of said second stage polymerization;
- and
- (d) recycling said undesirably-sized partially polymerized particles for dissolution in polymerizable material used as feedstock for said first stage polymerization.
A method of making expandable polystyrene beads comprising the steps:
- (a) conducting a first stage suspension polymerization of styrene to a point where the so-formed polystyrene beads will withstand the rigors of size classification but before the polymerization is more than 80% complete;
- (b) classifying the partially polymerized polystyrene beads by size;
- (c) conducting a second stage suspension polymerization of desirably-sized partially polymerized polystyrene beads resulting from step (b) and rendering said beads expandable in the course of said polymerization via impregnation with blowing agent.
In a method of making expandable polymeric particles by way of suspension polymerization, the improvement of achieving expandable polymeric particles falling within a desired size range comprising the steps of:
- (a) interrupting said suspension polymerization at the completion of a first stage at which time the polymerization of the polymerizable material is about 70% complete and the particles have sufficient physical integrity to withstand size classification;
- (b) classifying said particles by size to yield partially polymerized particles falling within a desired size range;
- (c) completing the polymerization of said desirably-sized partially polymerized particles during a second stage suspension polymerization;
- and
- (d) impregnating the desirably-sized particles with blowing agent.
A method of making expandable polymeric particles from polymerizable material comprising the steps:
- (a) conducting a first stage suspension polymerization of said polymerizable material to a point where the particles so-formed have sufficient physical integrity to withstand size classification and the polymerization is about 70% complete;
- (b) classifying the partially polymerized particles into particles of desired size and particles of undesirable size;
- (c) conducting a second stage suspension polymerization of said desirably-sized partially polymerized particles and impregnating the particles with blowing agent in the course of said second stage polymerization;
- and
- (d) recycling said undesirably-sized partially polymerized particles for dissolution in polymerizable material used as feedstock for said first stage polymerization.
A method of making expandable polystyrene beads comprising the steps:
- (a) conducting a first stage suspension polymerization of styrene to a point where the so-formed polystyrene beads will withstand the rigors of size classification and the polymerization is about 70% complete;
- (b) classifying the partially polymerized polystyrene beads by size;
- and
- (c) conducting a second stage suspension polymerization of desirably-sized partially polymerized polystyrene beads resulting from step (b) and rendering said beads expandable in the course of said polymerization via impregnation with blowing agent.
Dependencies are inferred from the claim text.