Abstract: A process and apparatus for producing polyurethane foam, comprising bringing together under pressure one or more foam components and a gaseous CO2 auxiliary blowing agent and discharging the combination through a permeable discharge head in the form of plural individual wire meshes sintered together to form at least one composite element having a structure such as to require repeated division, divergence and convergence of flow paths and impingement of the individual flows with the sintered wire mesh and the flows through adjacent pores in three dimensions within its axial thickness, and at which the pressure is reduced for forming a froth, wherein the combination of the foam components and gaseous CO2 is arranged to be in a non-homogeneous state containing gas bubbles prior to passage through the discharge head.

Abstract: A method of manufacturing a thermally insulated building block (54a) comprises foaming a quantity of foamable plastics material in an enclosed space (56) between a building block (54) and a closure means (52), the quantity of material being sufficient to fill the enclosed space (56). The foamable material may be injected into a cavity in the block onto an outer surface of the block (54) or onto the closure means (52) prior to locating the block (54) and closure means (52) relative to each other to form the enclosed space (56) therebetween. The block (54) is transported between upper and lower parallel endless belts (55, 50) during foaming and either belt (55, 50) may provide the closure means (52). If the lower belt (50) provides the closure means (52) the upper belt (55) maintains the block (54) in contact with the closure means (52) during foaming.

Abstract: A continuous process for the production of a phenolic foam composite comprises bringing a preformed layer of flexible insulating material whose thermal conductivity is less than 0.10 W/m.degree. C. for example polystyrene foam into contact with a phenolic foam forming mixture and allowing the phenolic foam forming mixture to foam and set so as to form a layer of phenolic foam bonded to the layer of flexible insulating material.A second preformed layer of flexible insulating material whose thermal conductivity is also less than 0.10 W/m.degree. C. can be brought into contact with the phenolic foam forming mixture so as to form a sandwich structure with the layers of flexible insulating material bonded to opposite faces of the layer of phenolic foam. The effect of the layers of flexible insulating material is to decrease the variation in properties of the foam through its cross section.