Abstract: An optical polyurethane resin composition contains a polyisocyanate component including at least one cyclic polyisocyanate selected from the group consisting of alicyclic polyisocyanates, aralkyl polyisocyanates, and modified compounds thereof; and a polyol component having an average hydroxyl value of 280 to 1240 mg KOH/g and an average functionality of more than 2 and less than 5.

Abstract: An optical polyurethane resin composition contains a polyisocyanate component including at least one cyclic polyisocyanate selected from the group consisting of alicyclic polyisocyanates, aralkyl polyisocyanates, and modified compounds thereof; and a polyol component having an average hydroxyl value of 280 to 1240 mg KOH/g and an average functionality of more than 2 and less than 5.

Abstract: A prepainted steel sheet has a chemically conversion-treated zinc-plated steel sheet and a coating formed on the surface of said zinc-plated steel sheet. The coating is formed by painting and baking of a solvent-type-paint composition. The paint composition contains a polyester resin.

Abstract: The invention relates to a thermosetting coating composition for precoated steel sheets which are required to have high hardness, good workability and stain resistance, to a precoated steel sheet having a film of the coating composition, and to a method for producing such precoated steel sheets.

Abstract: A method for producing a polyurethane elastomer which comprises reacting (1) either a polyisocyanate and a polyol or an isocyanate-terminated prepolymer obtainable by reacting said polyisocyanate with said polyol with (2) a diol of general formula ##STR1## wherein A.sub.1 and A.sub.2 are the same or different and each represents a bond, --O-- or --COO--; R.sub.1 and R.sub.2 are the same or different and each represents C.sub.1-6 alkylene; X.sub.1 and X.sub.2 are the same or different and each represents H or hydroxyalkyl and (3) a triol having a hydroxyl equivalent of 60 to 500, gives a polyurethane elastomer with improved tensile strength, tear strength and other mechanical properties.

Abstract: A flame-retardant, unsaturated polyester resin composition comprising a halogen-containing unsaturated polyester obtained by halogenating an unsaturated polyester prepared by the reaction of (a) dicyclopentadiene, (b) .alpha.,.beta.-ethylenically unsaturated dicarboxylic acid or its anhydride, (c) tetrahydrophthalic acid or its anhydride and (d) polyhydric alcohol.Crosslinked products of the composition exhibit increased halogen content and elevated deflection temperature, and are particularly useful for electric appliances, building materials, automobiles, railroad wagons, airplanes, etc.

Abstract: A process for producing a halogen-containing unsaturated polyester which comprises halogenating a dicyclopentadiene-terminated unsaturated polyester by feeding the unsaturated polyester into a reaction system which contains halogen. The unsaturated polyester or a resin composition containing the same shows a by far improved color tone, as compared with conventional ones, and also exhibits an increased halogen content and an elevated deflection temperature. They can be advantageously used as raw materials in every industrial fields, such as electrical appliances, construction materials, automobiles, railroad wagons and airplanes.