Abstract: Disclosed is cyclic urea derivatives represented by the following formula (A): ##STR1## wherein n is an integer of 0 or 1; m is an integer of 1 to 15; X is oxygen, sulfur or --NR.sub.1 -- (R.sub.1 is hydrogen or an alkyl group having 1 to 5 carbon atoms); R is an alkyl-, cycloalkyl -, aryl-, aralkyl-, alkaryl- and glycidyl group having 1 to 27 carbon atoms, or an alkyl-, cycloalkyl-, aryl-, aralkyl- and alkaryl group containing at least one ##STR2## O, S and N and having 1 to 27 carbon atoms with a molecular weight of 15 to 500, said groups substituted by glycidyl-, hydroxylic-, nitro groups, halogens, cyano-, formyl- or amino groups, or polyester-, polyether-, polyurethane and polyamide groups having a molecular weight of 500 to 100,000.

Abstract: This invention relates to an improvement of a thread forming screw including driven head, cylindrically formed shanks rolled type thread which has a following flank angle smaller than a progresssive flank angle and is interrupted by plural slot recesses locating in one revolution of the thread and being pretendedly formed as helical slot recesses. One of the recesses is formed by a duly inclined leading edge of an interrupted thread, a nearly perpendicular rearward edge of the one located at its leading side and a flat-like bottom located betweenthere. This configuration of the shank enable it to be easily driven into a workpiece because of the decreasing the engagement between the interrupted screw thread and the female thread formed thereby.

Abstract: The present invention relates to polymerizable cyclic urea derivatives which can be thermally split to give rise to an isocyanate group; and to a polymer having cyclic urea pendant groups, which can be cured by heating without any additional curing agent such as an isocyanate blocked with a volatile lower molecular weight material, so that volatile material is not released in a thermal curing process.