Patent GB-951503-A (GB)
Title: Dielectric cyanoethylated cellulose compositions
IPC: C08B11/04
Filed: 1962-05-17
Abstract: Compositions having a high dielectric constant and a low dissipation factor comprises 5 to 50% by weight of cyanoethylated hydroxyethyl cellulose and 50 to 95% cyanoethylated cellulose, each of the said percentage ranges being based on the total weight of the cellulosic portion of the composition and each of said cyanoethylated materials having a degree of substitution of at least 2.0 and preferably at least about 2.3.  The composition is preferably prepared by reacting a mixture of hydroxyethyl cellulose and cellulose (in such relative proportions as to give cyanoethylated products in relative proportions within the percentage ranges prescribed above) with excess acrylonitrile in the presence of an alkali metal hydroxide in a known manner until the reacted material has a degree of substitution of at least 2.0, neutralizing the resultant solution conjointly precipitating the resultant material, washing the material until its residual electrolyte content is less than 200 parts per million and collecting and drying the washed product.  The cyanoethylated hydroxyethyl cellulose and the cyanoethylated cellulose may be separately prepared, purified and mixed in the required proportions, or the hydroxyethyl cellulose and the cellulose may be separately cyanoethylated and the reaction products thus obtained mixed in the required proportions, before the precipitation, washing and drying steps. The compositions of the invention may be used as dielectric compositions in the form of films in the fabrication of electroluminescent devices and capacitors. U.S.A. Specifications 2,774,004, 2,792,447, 2,838,715, 2,901,652 and 2,918,594 are referred to.ALSO:Compositions having a high dielectric constant and a low dissipation factor comprise 5 to 50% by weight of cyanoethylated hydroxyethyl cellulose and 50 to 95% cyanoethylated cellulose, each of the said percentage ranges being based on the total weight of the cellulosic portion of the composition and each of said cyanoethylated materials having a degree of substitution of at least 2.0 and preferably at least about 2.3.  The composition is preferably prepared by reacting a mixture of hydroxyethyl cellulose and cellulose (in such relative proportions as to give cyanoethylated products in relative proportions within the percentage ranges prescribed above) with excess acrylonitrile in the presence of an alkali metal hydroxide in a known manner until the reacted material has a degree of substitution of at least 2.0, neutralizing the resultant solution conjointly precipitating the resultant material, washing the material until its residual electrolyte content is less than 200 parts per million and collecting and drying the washed product.  The cyanoethylated hydroxyethyl cellulose and the cyanoethylated cellulose may be separately prepared, purified and mixed in the required proportions, or the hydroxyethyl cellulose and the cellulose may be separately cyanoethylated and the reaction products thus obtained mixed in the required proportions, before the precipitation, washing and drying steps.  The compositions of the invention may be used in the form of films in the fabrication of electroluminescent devices. U.S.A. Specifications 2,774,004, 2,792,447, 2,838,715, 2,901,652 and 2,918,594 are referred to.