Manufacture of polymeric beads

Claim 1

A method of making beads that comprise a polymeric matrix formed from lipophilic polymerisable material and up to 40% of other polymerisable material and containing a substantially water insoluble lipophilic compound that will provide slow release of the lipophilic compound, or a reagent that can be liberated from the compound, into a fluid environment, and in which the lipophilic compound is insoluble in the polymerisable material at 25° C. and has a melting point greater than 25° C., the method comprising forming a homogeneous blend of the lipophilic compound in the polymerisable material in the substantial absence of nonpolymerisable solvent for said compound and at an elevated temperature greater than 25° C. at which the lipophilic compound is soluble in the lipophilic polymerisable material, and subjecting the blend to bead polymerisation while the blend is dispersed as a substantially stable dispersion of beads in an aqueous medium containing a hydrophilic polymerisation stabilizer.

Claim 2

A method of making beads that comprise a polymeric matrix formed from lipophilic polymerisable material and up to 40% of other polymerisable material and containing a substantially water insoluble lipophilic compound that will provide slow release of the lipophilic compound, or a reagent that can be liberated from the compound, into a fluid environment, and in which the lipophilic compound is insoluble in the polymerisable material at 25° C. and has a melting point greater than 25° C., the method comprising forming a homogeneous blend of the lipophilic compound in the polymerisable material in the substantial absence of nonpolymerisable solvent for said compound and at an elevated temperature greater than 25° C. at which the lipophilic compound is soluble in the lipophilic polymerisable material, and subjecting the blend to bead polymerisation while the blend is dispersed as a substantially stable dispersion of beads in an aqueous medium containing a hydrophilic polymerisation stabilizer.

Claim 17

A method of making beads that comprise a lipophilic matrix containing a substantially water insoluble, lipophilic, wax inhibitor and that will provide slow release of the wax inhibitor into a fluid environment, and in which the polymeric matrix has a softening point of 30 to 200 degrees C. as measured by a temperature graded hot bar and is formed by polymerisation of polymerisable material consisting of 80 to 99% by weight lipophilic monomer selected from methyl methacrylate and a blend of methyl methacrylate with a lesser amount of styrene and 1 to 20% by weight polymerisable hydrophilic monomer selected from acrylic acid and methacrylic acid, and the wax inhibitor is a behenyl ester of alkenyl succinic anhydride polymer having a molecular weight of 3,000 to 10,000 and is insoluble in the polymerisable material at 25 degrees C. but is soluble at 50 to 80 degrees C., and in which the method comprises forming a homogeneous blend of the wax inhibitor in the polymerisable material at a temperature of from 50 to 80 degrees C. and at which the wax inhibitor is soluble in the polymerisable material and subjecting the blend to bead polymerisation while the blend is dispersed as a substantially stable dispersion of beads in an aqueous medium containing a hydrophilic polymerisation stabiliser.

Claim 18

A method of making beads that comprise a lipophilic matrix containing a substantially water insoluble, lipophilic, wax inhibitor and that will provide slow release of the wax inhibitor into a fluid environment, and in which the polymeric matrix has a softening point of 30 to 200 degrees C. as measured by a temperature graded hot bar and is formed by polymerisation of polymerisable material consisting of 80 to 99% by weight lipophilic monomer selected from methyl methacrylate and a blend of methyl methacrylate with a lesser amount of styrene and 1 to 20% by weight polymerisable hydrophilic monomer selected from acrylic acid and methacrylic acid, and the wax inhibitor is a behenyl ester of alkenyl succinic anhydride polymer having a molecular weight of 3,000 to 10,000 and is insoluble in the polymerisable material at 25 degrees C. but is soluble at 50 to 80 degrees C., and in which the method comprises forming a homogeneous blend of the wax inhibitor in the polymerisable material at a temperature of from 50 to 80 degrees C. and at which the wax inhibitor is soluble in the polymerisable material and subjecting the blend to bead polymerisation while the blend is dispersed as a substantially stable dispersion of beads in an aqueous medium containing a hydrophilic polymerisation stabiliser.