초록 ▼

An improvement in a process for the production of polyurethane foam is disclosed, in which a first component is admixed and reacted with a second component and in which the first component has a viscosity at least two times the viscosity of the second component, thereby resulting in a nonuniform dis

An improvement in a process for the production of polyurethane foam is disclosed, in which a first component is admixed and reacted with a second component and in which the first component has a viscosity at least two times the viscosity of the second component, thereby resulting in a nonuniform distribution of the cells of the foam. The improvement comprises admixing the second component with 1-5%, by weight, of the second component, of fumed silica prior to admixing the first and second components. The amount of fumed silica is controlled so that the polyurethane foam subsequently obtained has a substantially uniform distribution of cells. A process for the production of a foamed thermoplastic structure is also disclosed in which at least part of the normally liquid chlorofluorocarbon blowing agent is added as a composition comprising an admixture of 5-99%, by weight, of fumed silica and 1-95%, by weight, of a normally liquid chlorofluorocarbon adsorbed thereon. The composition is in the form of a dry free-flowing powder.

대표청구항 ▼

In a process for the production of polyurethane foam in which a first component is admixed and reacted, in the presence of a normally liquid blowing agent, with a second component said first component being an isocyanate, and said second component being a polyol and in which the first component has

In a process for the production of polyurethane foam in which a first component is admixed and reacted, in the presence of a normally liquid blowing agent, with a second component said first component being an isocyanate, and said second component being a polyol and in which the first component has a viscosity at least two times the viscosity of the second component, the difference in the viscosities being such that but for the improvement hereinafter set forth the resultant polyurethane foam would have nonuniform distribution of cells, the improvement comprising admixing the second component with 1-5%, by weight, of the second component, of fumed silica prior to admixing said first and second components, the amount of silica so admixed being such that the polyurethane foam subsequently obtained has a substantially uniform distribution of cells.