GB333620A - Improvements in the manufacture of paper - Google Patents

Abstract

333,620. Haddan, R., (Raffold International Corporation). May 17, 1929. Sizing.-Sized paper is made from pulp stock having a carbonate filler and a paraffin emulsion mixed with the fibrous material. Alum may be added, and resin size may be used as a saponaceous emulsifying agent for the paraffin. The paraffin emulsion and the carbonate filler produce a stabLe flocculent precipitate which is non-sticky, non-agglomerant, and ink-resistant. The materials may also be applied to making of substantially unsized paper containing only about 0.5 per cent of size. The material may be mixed in the beater and the paper produced in the ordinary manner on a Fourdrinier, cylinder, or other forming, felting, shaping or moulding machine and dried and finished in the customary manner. The carbonate filler may be any filling materials such as calcium carbonate e.g. lime mud; calcium magnesium carbonate; calcium carbonate magnesium hydroxide; and other normal or compound carbonates of alkaline earth metals, magnesinm, or ammonia which give a pH value greater than 7.0 and which evolve carbon dioxide when treated with aqueous mineral acid; the term carbonate filler is also stated to include such compounds in association with old papers, broke, &c. The paraffin may be paraffin wax or any hydrocarbons of a waxv nature which are substantially unsaponifiable and inert and may be obtained from petroleum, shale, lignite, earth wax. &c. The resin size may be any product of an alkali on resin or on any synthetic resin acid. Other saponaceous emulsifying agents are ammonium oleate, sodium stearate, &c. or a mixture of these with or without montan wax may be used. The paraffin may be dispersed in a solution of sodium silicate &c. and precipitated with alum. The emulsions may be prepared in a. colloid mill. homogenizer &c. for example the resin and the paraffin may be melted together and the fluxed mass intimately mixed with an aqueous alkali such as sodium hydroxide, or with sodium silicate. If a colloid mill is used, the alkali solution is preferably heated and directed with the heated melt preferably in continuous proportionate streams into the inlet orifice of the null. Instead of alum as a precipitant, other aluminium salts, sulphuric acid, sodium bisulphate &c. may be used. The order of addition of the various ingredients to the fibrous mix may be varied. In an example of the proportions by weight of the ingredients; to 1760 parts of fibrous material made up with equal parts, on an air dry basis, of sulphite pulp, soda pulp, and old paper stock, are added 40 parts of saponaceous paraffin emulsion, 75 parts of alum, and 240 parts of calcium carbonate magnesium hydroxide.