Method of finishing thermoplastic granules
AssigneeExxon Research & Engineering Co.
InventorsMike E. Muhle, Richard J. Stolz, Cecil W. Wright
Life of this patent
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Abstract
Thermoplastic granules are finished by blending thermoplastic granules with additive material to form a masterblend; intensively mixing the masterblend with additional thermoplastic granules under conditions (1) to increase the temperature of the thermoplastic to its softening temperature and (2) to increase the bulk density of the granules; and withdrawing and cooling the mixture to form free flowing granules containing additives thereon or therein.
Claims16
A method of finishing polyolefin thermoplastic granules which comprises:
- (a) blending the thermoplastic granules with additive material at a ratio wherein the additive material comprises from about 0.001 to 40 weight percent of the blend, and at a temperature below the softening point of the thermoplastic to form a masterblend;
- (b) continuously introducing the masterblend and additional polyolefin thermoplastic resin into an intensive mixer in a resin/masterblend weight ratio of between about 5:1 to 50:1, and mixing the masterblend and additional thermoplastic granules therein under conditions (i) to increase the temperature of the thermoplastic to its softening point but below its fluxing temperature whereby additive material is embedded into or onto substantially all the granules and (ii) to increase the bulk density of the blend by at least 5 percent without producing excessive fines;
- and
- (c) continuously withdrawing and cooling the mixture from the intensive mixer to from free-flowing discrete particles.
The method as defined in claim 2 wherein the blending rates and mixing ratio are such to provide the mixture with an additive material concentration of between about 0.01 and 5 weight percent based on the mixture.
A method of treating ethylene homopolymers or copolymers produced by gas phase, fluid bed process in the form of granules having an average particle size between about 0.03 and 0.1 inches, said method comprising
- (a) blending the granules and additive material at a ratio wherein the additive material comprises from about 0.5 to 20 wt% of the blend, and at a temperature below the softening point of the polymer to form a masterblend comprising polymer granules at least partially coated with additive material;
- (b) intensively mixing the masterblend with additional untreated polymer granules in a granules/masterblend weight ratio of between about 10:1 and 40:1, and at conditions (i) to increase the temperature of the polymer to its softening point, and (ii) to reduce the average particle size of the granules by at least 20% without producing excessive fines;
- whereby part of the additive material is transferred from the masterblend granule to the untreated granules, and
- (c) cooling the granules whereby the additive material becomes substantially permanently adhered to the granules.
Dependencies are inferred from the claim text.