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AssigneeBASF SE
InventorsRonald Gabbard, Bernhard Schmied, Eric R. Weisenbach, Robert D. Ober
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An anti-lumping agent for use with expandable polystyrene beads is disclosed. The expandable polystyrene beads comprise a styrene or styrene derivative polymer in combination with a blowing agent. Typical blowing agents are C3-C6 hydrocarbons, with pentane being especially preferred. The anti-lumping agents include block copolymers formed from blocks of ethylene oxide and propylene oxide. Preferably, the copolymers have a number average molecular weight of from about 4,000 to 15,000, and a hydrophilic-lipophilic balance number of from about 16 to 29. The anti-lumping agents significantly reduce the lumping potential of the expandable polystyrene beads, especially when they are expanded to low densities of from about 1.5 to 0.75 lbs. per cubic foot, and more preferably to densities of from about 1.2 to 0.85.
An expandable polystyrene bead comprising an expandable styrene or styrene derivative polymer, from about 2% to about 5% by weight, based on the total weight of the bead, of a C3 to C6 hydrocarbon blowing agent, and an anti-lumping agent comprising a block copolymer of propylene oxide and ethylene oxide blocks, said block copolymer comprising from about 80% to 65% by weight ethylene oxide and from about 20% to 35% by weight propylene oxide, based on the total weight of the copolymer, and having a hydrophilic-lipophilic balance (HLB) value of from about 16 to 29.
A method for the formation of an expandable polystyrene bead comprising the steps of:
Dependencies are inferred from the claim text.