Patent GB-1100827-A (GB)
Title: New polybenzoxazoles, their production, and articles comprising them
IPC: C08G73/22
Filed: 1964-12-16
Abstract: Polybenzoxazoles <FORM:1100827/C3/1> where R is a trivalent aromatic radical with the O and N atoms attached directly to ring carbons in the ortho or peri position, the C atom is attached directly to a ring carbon of the R radical of the next unit, and n is high enough to provide an inherent viscosity of at least 0.1, may be prepared by cyclizing the polyamides of Specification 1,100,826 by heating at 250 DEG  to 500 DEG  C.  The polyamides may first be shaped. Foam polybenzoxazoles may be obtained by incorporating a blowing agent, with or without a filler, in the polyamide so that heating effects both foaming and cyclization or by dispersing bubbles (e.g. air, CO2, N2) in the polyamide before it is cyclized.  Additives may be incorporated by addition to the intermediate polyamide before or after shaping, e.g. fillers, pigments, conductive carbon black, metal particles, abrasives, dielectrics or lubricating polymers. Various applications of the polybenzoxazoles in the form of films, fibres, coatings and adhesives are specified.  Coatings and laminates.-Specified substrates which may be coated with or laminated by the polymers or to which films of the polymers may be laminated are metal sheets, fibres, wires and screens (e.g. Cu, brass, Al or steel); asbestos; sheets, fibres, foams or fabrics of glass or polymers, e.g. regenerated cellulose, wood, paper, polyolefines, polyesters, polyamides, polyimides, polymers of perfluoro-olefines, or polyurethanes; and leather sheets.  The polymer substrates may be surface treated to improve receptivity, e.g. metallized.  Reference has been directed by the Comptroller to Specification 1,008,854.ALSO:Polybenzoxazoles <FORM:1100827/B1-B2/1> where R is a trivalent aromatic radical with the O and N atoms attached directly to ring carbons in the ortho or peri position, the C atom is attached directly to a ring carbon of the R radical of the next unit, and n is high enough to provide an inherent viscosity of at least 0.1, may be prepared by cyclising the polyamides of Specification 1,100,826 by heating at 250 DEG  to 500 DEG C.  The polyamides may first be shaped.  Foam polybenzoxazoles may be obtained by incorporating a blowing agent, with or without a filler, in the polyamide so that heating effects both foaming and cyclisation or by dispersing bubbles (e.g. air, CO2, N2) in the polyamide before it is cyclised. Additives may be incorporated by addition to the intermediate polyamide before or after shaping, e.g. fillers, pigments, conductive carbon black, metal particles, abrasives, dielectrics or lubricating polymers. Various applications of the polybenzoxazoles in the form of films, fibres, coatings and adhesives are specified. Coatings and laminates  Specified substrates which may be coated with or laminated by the polymers or to which films of the polymers may be laminated are metal sheets, fibres, wires and screens (e.g. Cu, brass, Al or steel); asbestos; sheets, fibres, foams or fabrics of glass or polymers, e.g. regenerated cellulose, wood, paper, polyolefines, polyesters, polyamides, polyimides, polymers of perfluoroolefines, or polyurethanes; and leather sheets.  The polymer substrates may be surface treated to improve receptivity, e.g. metallised.  Reference has been directed by the Comptroller to Specification 1,008,854.