GB567242A - Coating compositions - Google Patents

Abstract

A paint, enamel, or like composition having a pigment which forms a soft, readily redispersable sediment on standing, is obtained by preparing a solution of a cellulose derivative and mixing therewith a pigmented coating composition with which the cellulose derivative is incompatible, whereby the cellulose derivative is precipitated in the form of soft flocculent curds. The dispersed semi-solid curds act in the nature of an auxiliary pigment and bring about a desirable state of flocculation of the main pigment in the paint and result in increased body. The amount of cellulose derivative curd is preferably in the range of 0.1 to 4 per cent of the enamel solids. Ethyl cellulose is dissolved in a solvent such as xylene or a mixture of xylene and a petroleum naphtha. Butyl alcohol or other alcohol may be added. p The ethyl cellulose solution is placed in a ball or pebble mill and the rest of the paint mill base is added, and the composition is ground until even dispersion of the pigments and precipitated ethyl cellulose has taken place. The paint may be diluted by addition of solvents. In an example, a varnish comprising a resin, calcium hydrate, linseed oil and mineral spirits is mixed with iron naphthenate, barytes, carbon black and mineral spirits, and with a solution of ethyl cellulose in petroleum naphtha. The resin may be a natural or synthetic resin. In another example, a solution of ethyl cellulose is mixed with a paint comprising a linseed oil-modified alkyd resin, calcined pyrophyllite, basic calcium silicate, titanium dioxide, lead naphthenate, manganese naphthenate and petroleum naphtha. Other fillers or pigments which may be used are silica, whiting, lead chromate, zinc chromate, white lead, zinc oxide, litharge, red lead and calcium aluminate. The ethyl cellulose may have an ethoxy content of 43.5 to 50 per cent. Other cellulose derivatives which may be used are cellulose acetate, acetobutyrate and nitrate, and benzyl cellulose.