Patent GB-872800-A (GB)
Title: Improvements in the degumming of bast fibres
IPC: D01C1/02
Filed: 1959-07-03
Abstract: Bast fibres, e.g. ramie, jute, kenaf, hemp and flax, are degummed by subjecting a mass of the decorticated fibres to the oxidizing action of an aqueous solution of potassium permanganate at a temperature 85 DEG -100 DEG C. for 10-20 minutes and then to the reducing action of an aqueous solution of oxalic acid at a temperature of at least 85 DEG C. for a time such that the pectin component of the fibres is preferentially solubilized and the hemicellulose component is only slightly solubilized.  The potassium permanganate solution preferably has a concentration of 0,075%-0,15% by weight and the amount of solution employed is preferably 50-70 times the weight of the fibres. After treatment with the potassium permanganate solution the fibres are preferably flushed with water having a temperature of 55 DEG -65 DEG C. for 2-3 minutes and are then treated with the oxalic acid solution, which preferably has a concentration of 0,12%-0,18% by weight and is preferably applied for 10-20 minutes in an amount 50-70 times the weight of the fibres.  The fibres may then be flushed with water and subjected to a finishing step comprising treating them for 5-10 minutes with an aqueous solution, preferably in an amount 50-70 times the weight of the fibres, of sulphuric acid having a concentration below 1% by weight at a temperature of 60 DEG -70 DEG C. to remove the manganese oxalate formed during the previous treatment. China grass and mechanically decorticated ramie may be degummed by the process.  Specification 383,627 is referred to.ALSO:Bast fibres, e.g. ramie, jute, kenaf, hemp and flax, are degummed by subjecting a mass of the decorticated fibres to the oxidizing action of an aqueous solution of potassium permanganate at a temperature of 85 DEG -100 DEG C. for 10-20 minutes and then to the reducing action of an aqueous solution of oxalic acid at a temperature of at least 85 DEG C. for a time such that the pectin component of the fibres is preferentially solubilized and the hemicellulose component is only slightly solubilized.  The potassium permanganate solution preferably has a concentration of 0,075-0,15% by weight and the amount of solution employed is preferably 50-70 times the weight of the fibres.  After treatment with the potassium permanganate solution the fibres are preferably flushed with water having a temperature of 55 DEG -65 DEG C. for 2-3 minutes and are then treated with the oxalic acid solution, which preferably has a concentration of 0,12-0,18% by weight and is preferably applied for 10-20 minutes in an amount 50-70 times the weight of the fibres.  The fibres may then be flushed with water and subjected to a finishing step comprising treating them for 5-10 minutes with an aqueous solution, preferably in an amount 50-70 times the weight of the fibres, of sulphuric acid having a concentration below 1% by weight at a temperature of 60 DEG -70 DEG C., to remove the manganese oxalate formed during the previous treatment.  China grass and mechanically decorticated ramie may be degummed by the process, in which the fibres are also bleached. Specification 383,627 is referred to.