Patent ID: 6165550
Filing Date: 2000-12-26
Classification: C05G,C08G

Abstract:
A process for the preparation of symmetrical polyurea-urethane coated granular fertilizer particles comprising the steps of:coating fertilizer particles with a first compound followed by coating with a second compound, said first and second compounds being capable of reacting to form a urethane containing terminal isocyanate groups,2) polymerizing the urethane adduct from 1) with moisture on the surface of said fertilizer particles to form a symmetrical polyurea-urethane sealant coating that imparts slow release properties to the fertilizer,wherein said compounds comprise a) at least one organic polyisocyanate, ##STR5## wherein: R.sub.1 : represents a hydrogen atom, or a C.sub.1 to C.sub.4 alkyl group;R.sub.2 and R.sub.3 : may be the same or different, and each represents a C.sub.1 to C.sub.4 alkyl group, a ##STR6## group, wherein: R.sub.1 : is defined as above;or R.sub.2 and R.sub.3 are joined together in a ring, thereby forming a 3 to 8 membered cyclic ring; andx: represents a number from 1 to 4,with the quantities of a) and b) being such that the NCO:H ratio in each encapsulating layer is from about 1.6:1 up to about 10:1,and wherein the resultant symmetrical polyurea-urethane coated granular fertilizer particles contain from about 0.5 to about 15% by weight of polyurea-urethane, based on the total weight of the encapsulated fertilizer particles.