| 摘要 |
<PICT:0981925/C3/1> <PICT:0981925/C3/2> <PICT:0981925/C3/3> In a dispenser for perfume, soap, insect repellant &c. (see Division A4) the perfume &c. is retained in liquid form in a sponge of polyurethane foam, which is expanded by treatment with benzyl alcohol, and is dispensed through an absorbent piston 12, the liquid from the sponge being forced into the piston and released slowly therefrom into the atmosphere. The piston consists of cellulose acetate in compressed granular form, the grain size being between 0.5 and 4.0 mm. Cellulose acetate grains are softened and swollen by mixing in a rotary mixer with ethylene glycol monoethyl ether in the proportions: 2 parts of cellulose acetate to 1 part of ethylene glycol, the latter being added in three stages in equal amounts and at intervals of one hour. The mix is then compressed under a pressure of 500 kilograms per square centimetre to bond the grains into a porous block which is air-dried before impregnation with perfume &c. The block is slightly hygroscopic so that partial pressure of absorbed moisture depresses the rate of volatilization. |
