Importance

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Abstract

A controlled release preparation of an active material comprising a reaction product obtained by reacting (a) a copolymer consisting essentially of maleic anhydride and at least one polyalkylene glycol ether represented by formula (I): ##STR1## wherein B represents a residue of a compound having from 2 to 8 hydroxyl groups; R.sup.1 represents an alkenyl group having from 2 to 5 carbon atoms; AO represents an oxyalkylene group having from 2 to 18 carbon atoms or a combination thereof which may be linked together in blocks or at random; R.sup.2 represents a hydrocarbon group having from 1 to 24 carbon atoms; a represents a positive integer, b and c each represents 0 or a positive integer, and a+b+c=2 to 8; l.gtoreq.0, m.gtoreq.0, n.gtoreq.0, and l+m+n =1 to 1000; and (b) an active material. The preparation is soluble both in water and in an organic solvent and exhibits activity for a prolonged period of time.

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First Claim