GB337806A - Improvements in the manufacture and production of artificial masses - Google Patents

Abstract

337,806. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Aug. 6, 1929. Polymerized vinyl alcohol-aldehyde condensation products.-Condensation products which may be rubber-like, plastic and elastic or hard and brittle are obtained by treating polymerized vinyl alcohols, obtainable by saponification of polymerized vinyl esters, with aliphatic aldehydes in the presence of acid catalysts. The reactions may be accelerated by heating and by the use of increased pressure. The condensation products, are in some examples suitable to form films and threads like artificial silk and may be modified by the addition of softening agents such as paraffin wax or combined with other materials such as natural or synthetic rubber, celluloid, and cellulose esters or ethers. The aldehydes may be employed in the form of their polymers such as trioxymethylene and metaldehyde, or derivatives such as acetals which split off aldehydes under reaction conditions. The products may be subjected to heat treatment in the presence of sulphur and sulphurizing agents such as sulphur chlorides, this treatment being more particularly useful when the products are obtained by the use of unsaturated aldehydes such as acrolein or crotonaldehyde. In examples : (1) Polymerized vinyl alcohol, obtained by saponifying with a one per cent solution of hydrochloric acid in ethyl alcohol a polymeric vinyl acetate that had been polymerized by means of benzoyl peroxide, is dissolved in water and heated while stirring with solution of formaldehyde under a reflux condenser, concentrated hydrochloric acid being added gradually. The excess of formaldehyde and acid are removed by steam distillation and the reaction product washed on hot rollers until dry. The insoluble product is converted into a dark coloured mass having the properties of hard rubber by the addition of sulphur and treatment between rollers at 150‹ C. and subsequent heating. (2) Acetaldehyde and concentrated hydrochloric acid are added to slightly polymerized vinyl alcohol obtained as in example 1 and dissolved in water, the whole being heated while stirring. A white rubber-like mass separates out and is worked up as described in the preceding example. (3) To polymerized vinyl alcohol prepared according to the previous examples and dissolved in water are added hydrochloric acid and crotonaldehyde, the mixture being heated while stirring. The precipitate is a pale, spongy tenacious mass. (4) Strongly polymerized vinyl alcohol, obtained by polymerizing vinyl acetate by means of sodium perborate and acetic anhydride and then saponifying the polymerized product with a weak hydrochloric acid solution as in the previous examples, is slowly added to a solution of aqueous sulphuric acid in solution of formaldehyde while cooling externally with ice. The viscous solution subsequently obtained is poured into ice water and a white and fibrous flaky precipitate obtained. (5) Polymerized vinyl alcohol obtained in the manner described in example 4 is dissolved in 70 per cent sulphuric acid, whereupon trioxymethylene is added. After stirring the solution is poured into ice water. The product is soluble in methylene chloride and chloroform and can be worked into transparent sheets similar to acetylcellulose or into films or threads like artificial silk. (6) Polymerized vinyl alcohol obtained in the manner described in example 4 is slowly added to a cooled solution of 60 per cent sulphuric acid and glyoxyl sulphate. After stirring and pouring into water a precipitate is obtained which can be worked up in the manner indicated in examples 4 and 5. Reference has been directed by the Comptroller to Specification 351,082, [Group IV].