Preparation of expandable styrene polymers
AssigneeAtofina Chemicals, Inc.
InventorJerome Wicher
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Abstract
Enhanced conversion rates are realized in a suspension polymerization process for styrene through the use of peroxide initiators having one hour half life temperatures from 101° to 111° C. are disclosed. Also disclosed are suitable initiator combinations which provide polymeric products with low residual monomer content at reduced process temperatures, polymerizable compositions containing such initiators and products produced by such processes and compositions.
Claims10
An improved process for the polymerization of styrene monomer to produce expandable polystyrene wherein styrene is polymerized in a process comprising the following steps:
- A. heating an aqueous suspension comprising styrene monomer and at least two organic peroxide initiators, one of said organic peroxide initiators having a lower one hour half life decomposition temperature and at least one other of said organic peroxide initiators having a higher one hour half life decomposition temperature, for a time and at a temperature sufficient to effect at least partial decomposition of said lower half life organic peroxide and initiate polymerization of said styrene monomer, and
- B. subsequently raising the temperature of said aqueous suspension above the initial heating temperature to complete decomposition of the organic peroxide initiators in said suspension and provide complete polymerization of said styrene monomer,
- wherein the improvement comprises at least one of the organic peroxide initiators incorporated in said suspension being an “intermediate” temperature peroxide.
An improved aqueous suspension suitable for polymerization to provide expandable polystyrene, said suspension comprising styrene monomer and at least two organic peroxide initiators, one of said organic peroxide initiators having a lower one hour half life decomposition temperature and at least one other of said organic peroxide initiators having a higher one hour half life decomposition temperature, wherein the improvement comprises one of the organic peroxide initiators in said suspension being an “intermediate” temperature peroxide.
Dependencies are inferred from the claim text.