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 process and apparatus for producing a polymeric foam, wherein foam components are brought together under pressure and are passed through a permeable discharge head where the pressure is reduced. The permeable discharge head comprises a diffuser element having a structure such as to require division, divergence and convergence of flow paths in three dimensions within its axial thickness, considered in the direction of flow therethrough. The diffuser element comprises plural individual woven wire meshes sintered together to form a composite element. The invention also provides the diffuser element.

Abstract: An apparatus and process for producing polymeric foam, wherein reactive foam components and a low-boiling point frothing agent are brought together, sufficient pressure is applied to maintain the frothing agent in a liquid state and the mixture is passed through a permeable discharge head through which the mixture is discharged and wherein the pressure is reduced and froth is formed. The discharge head comprises one or more diffuser elements (80) having a structure such as to require division, divergence and convergence of flow paths in three dimensions within the axial thickness of the diffuser element, considered in the direction of flow therethrough. The diffuser element (80) is made of bonded, or sintered or sintered composite material, such as sintered wire.