Insecticidal evaporator having a diffusion layer of olefin polymerizate

Claim 1

In an insecticidal evaporator comprising I an absorbent fibrous mass substrate impregnated with a liquid composition comprising a. from about 40 to 90% by weight of the total liquid composition of 2,2-dichlorovinyldimethylphosphate b. an epoxidised organic liquid compound having a maximum vapor pressure no greater than the vapor pressure of 2,2-dichlorovinyldimethylphosphate; and c. an organic compound which is miscible with or soluble in the mixture of 2,2-dichlorovinyldimethylphosphate and said epoxidised organic compound; and Ii a non-porous, olefin polymer diffusion layer covering at least part of said impregnated fibrous mass, the remaining surface of said fibrous mass being covered by an envelope impermeable to said liquid composition; said epoxidised organic compound promoting the exudation of 2,2-dichlorovinyldimethylphosphate at the exterior surface of said diffusion layer, the improvement comprising a method of reducing exudation of 2,2-dichlorovinyldimethylphosphate at the exterior surface position, by incorporating into the liquid composition as the organic compound (c), from about 1 to about 40% by weight of said composition, of an exudation-reducing agent selected from the group consisting of (1) a compound of the formula ##SPC2## in which X 1 represents hydrogen, X 2 represents hydrogen or one of the substituents defined for (R) n , or X 1 and X 2 jointly represent a divalent bridge of the formula --CH=CH--CH=CH-- and (R) n represents substitution on the nucleus of members selected from the group consisting of (α) 2 or 3 hydroxyl groups, (β) from 1 to 3 alkyl groups each having from 1 to 4 carbon atoms, (γ) 1 or 2 alkyl groups each having from 1 to 4 carbon atoms, conjointly with a hydroxyl group, and (δ) an alkoxy group having from 1 to 4 carbon atoms, one of which members may occupy the X 2 position, and (2) di-(2-chloroethoxy)-methane.