摘要:
A process for preparing a polyurethane foamed article including a hard foam encapsulated by a soft foam is provided. The process provides improved encapsulation over that described in EP 68820 by frothing the hard foam formulation, with for example carbon dioxide, before it is introduced onto the rising soft foam formulation. The hard foam formulation is frothed so that is density is between 75% and 145% of the soft foam formulation.
摘要:
A novel flexible polyurethane foam has a substantial number of cells with an internal residual cell surface greater than 60% and less than 90%. The novel foams have improved vibration damping characteristics.
摘要:
A flexible polyurethane foam article with regions of different hardness is made by introducing into a mould a foam formulation giving a foam of a given hardness and then introducing a foam formulation giving a foam of different hardness directly onto the first foam formulation at a time corresponding to a volume expansion in the range 100% to 2300%.
摘要:
A mixing head suitable for mixing two or more liquids is provided. During the mixing process, the liquids are first contacted in a zone of small dimensions in which turbulent mixing occurs and are then discharged into a zone of larger dimensions in which laminar flow is established. The two zones are so designed that there is a single piston operating in both zones and discharging the mixed product. The mixing head can be used to mix a polyol and a polyisocyanate during the formation of polyurethanes.
摘要:
Cold-cured molded polyurethane flexible foams having improved vibration damping properities are made by foaming in the presence of (1) a high molecular weight predominantly linear siloxane polyoxyalkylene block copolymer and (2) a solvent which is compatible with the block copolymer and which has a viscosity of 3 to 100 cps and a surface tension between 15 to 60 dynes/cm.