Patent GB-713914-A (GB)
Title: Improvements in or relating to the surface colouring of regenerated cellulose
IPC: B05D7/02
Filed: 1952-09-11
Abstract: Glossy metallic or pigmented layers are applied to surfaces of regenerated cellulose by applying a dispersion of an alkali resistant metal powder or of a mixture having a metallic gloss or of a pigment in an alkaline solution of hydroxy alkyl cellulose, preferably hydroxy ethyl cellulose, to the whole or a part of the surface of regenerated cellulose while the latter is in a moist condition, the surface being then treated with acid and afterwards washed free of acid with water.  The dispersion may be applied to regenerated cellulose which contains acid; where the metallic powder or pigment is not discoloured by hydrogen sulphide, this may be regenerated cellulose which has been coagulated by an acid bath, but has not yet been washed.  The covering layer is then treated in an acid coagulation bath, and the acid removed by washing.  The process may be applied to capsules or bands of the type which are kept moist until required for application.  The dispersion may be applied by printing, by spraying or by rollers. The pigment may be bronze powder, or silver-grey pigment mixed with mica particles or a layer containing mica particles may be deposited on a base coloured silver-grey by pigments.  In an Example, 2 parts of a copper bronze having a particle size of 50 to 150 microns are dispersed in a solution of 5 parts of hydroxy ethyl cellulose having a substitution degree of 0.34 in 7 parts of water containing 6 parts of sodium hydroxide.  This is sprayed on a tube of regenerated cellulose from which the acid used for coagulating the viscose has been removed. The tube is carried through the air and thereafter passed through a 10 per cent. solution of sulphuric acid and then to and fro in a vessel with running water to remove the acid.  Specification 604,750 is referred to.ALSO:Glossy metallic or pigmented layers are applied to surfaces of regenerated cellulose by applying a dispersion of an alkali resistant metal powder or of a mixture having a metallic gloss or of a pigment in an alkaline solution of hydroxy alkyl cellulose, preferably hydroxy ethyl cellulose, to the whole or a part of the surface of regenerated cellulose while the latter is in a moist condition, the surface being then treated with acid and afterwards washed free of acid with water.  The dispersion may be applied to regenerated cellulose which contains acid; where the metallic powder or pigment is not discoloured by hydrogen sulphide, this may be regenerated cellulose which has been coagulated by an acid bath, but has not yet been washed.  The covering layer is then treated in an acid coagulation bath, and the acid removed by washing.  The process may be applied to capsules or bands of the type which are kept moist until required for application.  The dispersion may be applied by printing, by spraying or by rollers. The pigment may be bronze powder, or silver-grey pigment mixed with mica particles or, a layer containing mica particles may be deposited on a base coloured silver-grey by pigments.  In an example, 2 parts of a copper bronze having a particle size of 50 to 150 microns are dispersed in a solution of 5 parts of hydroxy ethyl cellulose having a substitution degree of 0.34 in 7 parts of water containing 6 parts of sodium hydroxide.  This is sprayed on a tube of regenerated cellulose from which the acid used for coagulating the viscose has been removed. The tube is carried through the air and thereafter passed through a 10 per cent. solution of sulphuric acid and then to and fro in a vessel with running water to remove the acid.  Specification 604,750, [Group IV(a)], is referred to.