| 摘要 |
1. A microcapsule containing an organic liquid comprising an ultraviolet light sensitive, biologically active materia, and an effective amount of a particulate ultraviolet light protectant selected from titanium dioxide, zinc oxide and mixtures thereof suspended and thoroughly dispersed in the liquid. 2. A microcapsule according to Claim 1 in which the biologically active material is suspended in the liquid. 3. A microcapsule according to Claim 1 in which the biologically active material is dissolved in the liquid or comprises the liquid. 4. A microcapsule according to Claim 1 in which the particle size of the ultraviolet light protectant is from about 0.01 to about 2 microns. 5. A microcapsule according to Claim 1 in which the particle size of the ultraviolet light protectant is from about 0.02 to about 0.5 microns. 6. A microcapsule according to Claim 1 in which the ultraviolet light protectant is titanium dioxide. 7. A microcapsule according to Claim 1 in which the ultraviolet light protectant is a mixture of titanium dioxide and zinc dioxide. 8. A microcapsule according to Claim 1 in which the biologically active material comprises a pyrethroid. 9. A microcapsule according to Claim 1 in which the biologically active material comprises lambda-cyhalothrin. 10. A microcapsule according to Claim 1, wherein the capsule walls are formed of polyurea. 11. A microcapsule according to Claim 1, wherein the capsule walls are formed of a urea-formaldehyde polymer. 12. A process for preparing microcapsules containing a liquid comprising an ultraviolet light sensitive, biologically active material and an effective amount of a particulate ultraviolet light protectant selected from titanium dioxide, zinc dioxide and mixtures thereof suspended and thoroughly dispersed in the liquid, comprising the steps of: (a) preparing a suspension of the protectant having an average particle size of from about 0.01 to about 2 microns in an organic liquid which is immiscible with water and which contains an ultra violet light sensitive, biologically active material, in which the protectant is thoroughly dispersed in the liquid; (b) introducing the suspension into water containing a protective colloid and optionally a surfactant capable of maintaining the organic liquid as droplets in the water without extracting the protectant from the organic liquid into the water, the organic water containing in solution one or more prepolymers which can react to form a polymerat the interface of the organic liquid and water; (c) mixing the suspension of organic liquid in the aqueous phase under hogh shear to form an oil in water emulsion; and (d) adjusting as necessary the temperature and/or pH of the oil in water emulsion such that a polymerization reaction takes place at the liquid/water interface to form the microcapsules. 13. A process according to Claim 12 in which the biologically active material is a solid which is suspended in the liquid. 14. A process according to Claim 13 in which the biologically active material has an average panicle size of from about 0.01 to about 50 microns. 15. A process according to Claim 12 in which the biologically active material is dissolved in the liquid. 16. A process according to Claim 12 in which the panicle size of the droplets of organic liquid, after dispersion in the water, is from about 1 to about 30 microns. 17. A process according to Claim 12 in which the prepolymer comprises one or more organic polyisocyanates dissolved in the organic liquid which, when heated, forms a polyurea by hydrolysis of an isocyanate to an amine which, in turn. reacts with another isocyanale to form the polyurea. 18. A process according to Claim 17 in which the prepolymer is a mixture of polymethylene polyphenylisocyanate and an isomenc mixture of toluene diisocyanate. 19 A process according to Claim 12 in which the prepolymer is a urea-formaldehyde prepolymer in which about 50-98% of the methylol groups have been ethenfied with a C4 -C10 alcohol, and which forms a solid polymer at the organic liquid/water interface. 20. A process according to Claim 19 in which about 70-90% of the methylol groups of the prepolymer have been ethenfied with n-butanol. 21. A process according to Claim 12 in which the ultraviolet light protectant particles are thoroughly dispersed in the liquid by means of a dispersant. 22. A process according to Claim 21 in which the dispersant is a nonionic surfactant. 23. A process according to Claim 12 in which the microcapsules have an average particle size of about 1-200 microns 24 A process according to Claim 12 in which the biologically active material comprises a pyrethroid 25. A process according to Claim 12 in which the biologically active material comprises lambda-cyhalothrin. |
