Patent GB-475535-A (GB)
Title: Improved manufacture of impregnated tubes
IPC: B29C53/50
Filed: 1936-05-22
Abstract: A tube such as a casing for edible products comprises a thin paper &c. strip having the overlapping margins secured by adhesive, the whole being coated with a cellulose ether; the paper &c. may be so impregnated and covered with the cellulose ether that the structure may be regarded as a seamless cellulose ether tubular matrix enclosing the paper strip.  In a preferred method, a long-fibred paper is used; this is curved about a longitudinal axis, the margins are pasted together preferably with a cellulose ether, and the tube is then treated with a cellulose ether solution and finished either by passage through a precipitating bath or by drying to remove organic solvent according to the type of cellulose solution applied to the tube.  The solution may be applied to either or both sides of the tube, and as an alternative, the cellulose solution may be applied before the paper strip is formed into a tube.  For carrying out the impregnation and coating of the paper tube, the apparatus described in Specification 475,534 may be employed, this being particularly suitable for use with a precipitating bath.  With a caustic soda solution of an hydroxyalkyl cellulose ether, a suitable precipitating bath contains 5--12 per cent sulphuric acid and 10--15 per cent sodium sulphate (or 10--20 per cent ammonium sulphate); and after washing, the coated tube is passed through a bath containing glycerine or other hygroscopic agent, and then dried.  In the case of a cellulose ether soluble in organic solvents, a plasticizer may be introduced into the coating solution.  Reference has been directed by the Comptroller to U.S.A. Specification 1,829,702.ALSO:A casing for sausages &c. comprises a thin paper &c. strip having the overlapping margins secured by adhesive, the whole being coated with a cellulose ether; the paper &c. may be so impregnated and covered with the cellulose ether that the structure may be regarded as a seamless cellulose ether tubular matrix enclosing the paper strip.  In a preferred method, a long-fibred paper is used; this is curved about a longitudinal axis, the margins are pasted together preferably with a cellulose ether, and the tube is then treated with a cellulose ether solution and finished either by passage through a precipitating bath or by drying to remove organic solvent according to the type of cellulose solution applied to the tube.  The solution may be applied to either or both sides of the tube, and as an alternative, the cellulose solution may be applied before the paper strip is formed into a tube.  For carrying out the impregnation and coating of the paper tube, the apparatus described in Specification 475,534 may be employed, this being particularly suitable for use with a precipitating bath.  After washing the tube leaving the precipitating bath, the latter is passed through a bath containing glycerine or other hygroscopic agent, and then dried.  In the case of a cellulose ether soluble in organic solvents, a plasticizer may be introduced into the coating solution.  Reference has been directed by the Comptroller to U.S.A. Specification 1,829,702.