| 摘要 |
<p>1535487 Polyurethane foam FOAM CUTTING ENGS Inc 16 June 1977 [17 June 1976] 25250/77 Heading C3R [Also in Division B2] Open-celled polyurethane foam is treated by the application of a modifying ingredient, e.g. a dye, pigment, colour stabilizer (e.g. titanium dioxide) or fire retardant, by a method comprising (a) applying an excess of a liquid e.g. an aqueous solution or dispersion of the modifying ingredient to a mass of the foam, (b) removing most of the excess of the liquid by squeezing the mass, (c) passing a gas (e.g. air), the temperature of which is between 350‹ and 500‹ F. through the material for a period of time sufficient (i) to raise the temperature of the polyurethane mass to a point at which the polyurethane will absorb the modifying ingredients, and (ii) to vaporize the liquid present in the solution or dispersion, the period of time (suitably about a minute) being insufficient to cause charring of the polyurethane, so as to permanently incorporate the modifying ingredient into the foam, and (d) allowing the mass to cool. Preferably the mass is passed through a bath of the solution or dispersion for a period of time sufficient to allow permeation of the mass, and the gaseous material is circulated downwardly through the foam by suction. Suitable apparatus is illustrated.</p> |
