TH9768B - Expandable polystyrene resin granules and their processing - Google Patents

Abstract

Expandable styrene resin beads with internal voids, where the number of voids in the area from the bead surface to a depth of 0.1 mm in the radial direction does not exceed 100 per mm² as counted on the approximate cross-section of the bead. The fabrication process of expandable styrene resin beads is by suspension polymerization, where styrene monomer is suspended in an aqueous medium with a precursor and suspending agents, and a binder is incorporated into the resulting polymer beads. Alkali metal salts or ammonium salts of persulfuric acid are added to the reaction system in amounts of 0.5 to 30 ppm compared to the aqueous medium when the conversion rate of the monomer is in the range of 0 to 30%, and electrolytes are added to the reaction system at concentrations of 0.02 to 5.0 mol/L compared to the aqueous medium when the conversion rate is 30% or more. The expanded styrene resin beads do not require accelerated aging and, when pre-expanded, exhibit minimal variation. Within the cell, the expanding styrene resin beads are largely unaffected by storage conditions.

Claims (5)

1.Expandable styrene resin granules With a blank hole inside In which the number of spaces that exist in the area from The surface of the tablet to a depth of 0.1 mm, along the radial direction, will not exceed 100 per sq mm, as counted on the cross section that runs approximately through the center of the grain. 2. Expandable polystyrene resin as in claim 1, where the number of voids available on the exempt area The area from the surface of the tablet to a depth of 0.3 mm, along the radial direction, is not less than 250 per sq mm, as counted on the cross section approximately across the center of the grain. 3.Expandable styrene resin granules As in claim 1, the aforementioned expanded polystyrene tablets have a grain size of 0.3 to 3 mm. 4.Production process of styrene resin beads It is expandable by polymerization suspended, which consists of suspending styrene monomer in an active medium. With substrate and suspension To obtain polystyrene resin granules and the inclusion of blowing agents in such styrene resin granules. Which are added alkali metal salts or Persulfuric acid ammonium salts were injected into the reaction system at an amount of 0.5 to 30 ppm by weight compared to the acidic medium at the rate of change. Of these monomers in the range from 0 to 30% with moles and additions of electrolytes in addition to Alkali metal salts Or the ammonium salts of the aforesulfuric acid in the reaction system at a concentration of 0.02 to 5.0 mol / L compared to the acquyase medium. While the rate of change Such a monomer is more than 30% by mole. 5. The process, as in claim 4, where one substance is selected from a group consisting of Polyethylene wax, ethylene-Bisamid, hexachabromocyclodidizane, tald and methacrylic acid lower alkyl. Esterco polymers with not less than 5% methacrylic acid lower alkyl ester units are present in Aqueous medium in a concentration of 0.0001 to 0.95% by weight compared to the styrene monomer.