Abstract: A liquid active substance-containing membrane having an anisotropic structure comprising (a) a polymeric cellular layer containing a myriad of minute closed cells and septa thereof and (b) a dense thin layer covering the surface of the cellular layer, wherein the minute cells contain therein a liquid active substance having a limited solubility in the polymer at normal temperature. The membrane of the present invention can be advantageously used to release a liquid active substance such as pheromones and pesticides at a substantially constant, controlled rate over a long period of time.

Abstract: A liquid active substance-containing membrane having an anisotropic structure comprising (a) a polymeric cellular layer containing a myriad of minute closed cells and septa thereof and (b) a dense thin layer covering the surface of the cellular layer, wherein the minute cells contain therein a liquid active substance having a limited solubility in the polymer at normal temperature. The membrane of the present invention can be advantageously used to release a liquid active substance such as pheromones and pesticides at a substantially constant, controlled rate over a long period of time.

Abstract: A process for producing a microcapsule containing a liquid active material is described, comprising the steps of:(1) dissolving in an organic solvent a polymer, esp. a polysulfone and an active material which has a limited solubility of about 0.01 to about 2 parts by weight in 100 parts by weight of said polymer and which is liquid at room temperature, the amount of said liquid active material added being more than the limited solubility and being about 2 to about 250 parts by weight per 100 parts by weight of the polymer and said organic solvent being capable of dissolving the respective components and being more volatile than said active material;(2) atomizing the resulting solution through a nozzle into a gaseous atmosphere to form a mist of tiny liquid droplets; and(3) removing the solvent from the droplets by evaporation so as to provide a microcapsule having the liquid active material confined by the wall of said microcapsule made of the polymer.