Abstract: Switching valves, e.g. for a closed-type molding apparatus for manufacturing polyurethane elastomers and the like, comprising a valve body having a plurality of openings, preferably five, serving as inlet and outlet ports, and a preferably rotatable valve sleeve which serves for switching the openings without any danger of introducing any other material into the switching valve system. Connections are made between pairs of adjacent openings, one of them being cut off from communication.

Abstract: A urethane elastomer is produced by simultaneously reacting an organic polyisocyanate with(1) a chain polyol having a molecular weight of 400 to 5,000,(2) an aromatic diamine and(3) a polyol having at least one urethane bond and/or an amino alcohol having at least one urethane bond.

Abstract: This invention relates to a material mixing apparatus for use, for example, in the preparation of polyurethane elastomers, wherein a mixer chamber, a set of switching valves and pipelines are maintained to ensure a constantly flowing state for the materials, the apparatus being featured in that it allows to remove the mixed materials in any amount at any time yet preventing contamination of the work site, as a result of a preferably totally closed structure. Two exemplary embodiments are disclosed, having at least two material tanks and switching means, as well as an additional switching means which can serve for a liquid rinsing agent or for a mixture of the materials.

Abstract: Urethane elastomers are prepared by reacting a long-chain polyol having a molecular weight of 400 - 5000 in a one-shot operation with an organic diisocyanate and a halogenated aromatic diamine of the general formula: ##STR1## wherein X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are the same or different and each represents a halogen atom and n is zero or 1. According to this process, urethane elastomers possessing excellent physical characteristics can be produced economically and advantageously in the operations.