Importance

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Abstract

An improvement is disclosed in a process for producing foamed articles of thermo-plastic or thermo-setting compounds. The improvement reduces the number of steps normally followed to make a foamed product and cuts down on the time. The improvement comprises the steps of intensively mixing and thermokinetically heating a batch of the compounds with a foaming agent having a preselected trigger temperature to initiate gas evolution, the mixing and heating occurring in an enclosed mixing chamber with a plurality of blades attached to arms rotating about an axis, with a blade tip speed of at least about 18 meters per second, mixing until the compounds and the foaming agent are heated above the trigger temperature of the foaming agent to a mixture having a predetermined discharge temperature representing a state of flux of the compounds suitable for forming and the mixture having a viscosity sufficient to contain gas evolved from the foaming agent, discharging the batch from the chamber when the batch reaches the predetermined temperature, and feeding the mixture from the discharged batch to a forming unit while foaming is still occurring.

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First Claim