sferisk perla of organic materials and makromeolkylert still for its framstellning

摘要

1457014 Cellular spherical polymer beads BATTELLE MEMORIAL INSTITUTE 19 March 1974 [20 March 1973] 12200/74 Headings C3C and C3R Spherical beads of rigid thermoset polymer contain a plurality of closed cells, the walls of the peripheral cells forming a continuous skin. The beads are made by making a mixture of at least one organic precursor, material which is capable of being transformed into a rigid thermoset polymer and at least one expansion agent, dividing this mixture into particles which are then introduced into a bed comprising at least one powdered inert material and which is subjected to agitation, while preventing the particles from touching one another, and heating the particles in the bed so as to cause their expansion and hardening the resultant cellular beads while still separated from one another. In The examples (a) phenol-formaldehyde resins in the resol stage or (b) a mixture of polyethers derived from propylene oxide and sorbitol or glycerol, and diphenylmethane-diisocyanate, are mixed with ethyl alcohol, petroleum ether, anhydrosorbitol monopalmitate/ethylene oxide condensate water, trichloromonofluoromethane, acid catalysts, a block copolymer of ethylene and propylene oxides and a siloxane and/or polyfurfuryl alcohol and the mixtures are passed through a syringe (i) to form droplets which are allowed to fall on a vibrating bed of talc which is heated to expand and harden the beads; or (ii) to form an extruded thread which is allowed to fall into liquid air where it is cut into particles which are then placed on to a bed of carbon black which is then heated.