GB802683A - Oriented films of substituted oxacyclobutane polymers - Google Patents

Abstract

Unsupported molecularly orientated films are made from polymers of 3 : 3-bis-(chloromethyl)-oxacyclobutane, the polymers having a specific viscosity greater than 0.3 when measured as a 0.1 per cent solution in cyclohexane at 50 DEG C. (corresponding to a molecular weight of at least 10,000). Sheets or ribbons of the polymer are extruded at 160-260 DEG C., rapidly quenched to 0-80 DEG C. within one minute, preferably within 10 seconds, and then subjected, at 0-50 DEG C., to strain in one direction or, either simultaneously or in succession, in two directions substantially at right-angles to each other. Alternatively, the films may be prepared by solvent casting, fused at 160-260 DEG C. on a chrome plate coated with a silicone oil to prevent sticking, and then orientated by drawing as already described. The film, prepared by either process, may then be heat-set at 60-125 DEG C. Stabilizers may be added to the polymer against, for example, the action of light or heat, and phenols are suitable for this purpose; a long list of suitable phenols is given. Plasticizers may also be added, and many alkyl esters, oils, polyethers, and halogenated hydrocarbons are specified. If desired, pigments may be incorporated before the formation of the film. The process may also be applied to copolymers of 3 : 3-bis-(chloromethyl)-oxacyclobutane with other 3 : 3-disubstituted oxacyclobutanes, and several such copolymers are described. Specification 758,450 is referred to. Reference has been directed by the Comptroller to Specification 723,777.