1. Field of the Invention
The present invention relates to flexible polyurethane foams having a high flame resistance and smoke resistance and to heat compression-moldings thereof.
2. Description of the Prior Art
Polyurethane foams have a broad use from seat and cushion materials for furniture, vehicles and ships to cloths and architecture materials. Furthermore, it has been known that foam sheets can be obtained by compression-molding the polyurethane foam under heating by utilizing the thermoplasticity of flexible polyurethane foams and the foam sheets have been broadly used for both surface adhesive tapes; imitation leathers; packing cushion materials for protecting optical machines, precision machines and glass; a slip preventer for a mat; prevention of shock noise when a door is opened and closed; wrapping and the like.
Substantially all the above described materials are inflammable and in order to satisfactorily adapt the foam sheet to the above described uses, it has been recently demanded to use flame resistant polyurethane foams.
However, the well known processes, that is, use of phosphorus compounds, a combined use of halogen and phosphorus compounds, use of a metal oxide, such as antimony oxide, use of a reactive flame retardant and the like can give a certain degree of flame resistance to polyurethane foams but the generation of smoke when burning is rather larger than the case where no flame retardant is used and there has been a great problem in view of the smoke emission.
Moreover, the process heretofore carried out for molding the foam into a sheet comprises compressing a flexible polyurethane foam at a high temperature 150.degree.-200.degree. C. for a long time and this process has not been preferable in view of save of energy and productivity.