Abstract: Expandable styrene-maleic anhydride copolymer particles which comprises a copolymer resin obtained by reaction of a styrene-maleic anhydride copolymer with a hydroxy compound and further impregnated with a volatile blowing agent.

Abstract: A process for producing expandable thermoplastic resin beads which comprises suspending in an aqueous medium 20 to 70% by weight of a random copolymer of propylene and ethylene containing 1 to 10% by weight of ethylene and 99 to 90% by weight of propylene and 30 to 80% by weight of a vinyl aromatic monomer such as styrene, polymerizing the vinyl aromatic monomer in the presence of a polymerization catalyst to graft the vinyl aromatic monomer onto the backbone of the random copolymer and, optionally, adding a cross-linking agent, to form graft-copolymerized thermoplastic resin beads, and introducing a blowing agent into the thermoplastic resin beads. The resulting resin beads have excellent foamability and molding fusability, and a foamed shaped article having superior thermal stability can be prepared from these beads.

Abstract: A process for producing expandable thermoplastic resin beads which comprises suspending in an aqueous medium 20 to 70% by weight of polypropylene resin particles and 30 to 80% by weight of a vinyl aromatic monomer such as styrene, polymerizing the vinyl aromatic monomer in the presence of a polymerization catalyst to graft the vinyl aromatic monomer onto the backbone of polypropylene and, optionally, adding a cross-linking agent, to form graft-copolymerized thermoplastic resin beads, and introducing a blowing agent into the thermoplastic resin beads. The resulting resin beads have excellent foamability and molding fusability, and a foamed shaped article having superior thermal stability can be prepared from these beads.

Abstract: Expandable styrene-maleic anhydride copolymer particles in which the base copolymer is chemically modified with a hydroxy compound such as 1,4-butanediol, diethylene glycol, glycerine or bisphenol which are useful in the production of various foamed articles having low density without overcharging thereof and good thermal stability.

Abstract: Expandable styrene polymer particle compositions containing an expanding agent which is volatilizable and does not dissolve or may slightly swell the styrene polymer particles and a small amount of sulfur containing compound having the general formula: ##EQU1## wherein, R.sub.1 and R.sub.2 are the same or different lower alkyl, aralkyl or aryl groups, R.sub.1 and R.sub.2 may be joined together to form an alkylene group, andR.sub.3 is a metal ion, ammonium or organic amine each of which form soluble salts in an organic solvent, or a group ##EQU2## wherein n is an integer of from 0 to 5 and R.sub.1 and R.sub.2 are the same as the above.

Abstract: Expandable styrene polymer particle compositions containing (1) an expanding agent, which is volatilizable and does not dissolve or may slightly swell the styrene polymer particles, and having a boiling point lower than the softening point of the styrene polymer particles, and (2) a small amount of sulfur containing compound having the following general formula: ##EQU1## wherein R.sub.1 and R.sub.2 are the same or different higher alkyl groups having 12 - 18 carbon atoms and R.sub.3 and R.sub.4 are the same or different lower alkylene groups having 1 - 4 carbon atoms.