Abstract: The present invention concerns improving the properties of cellulose carbamate fibres. The wet strength properties in particular can be improved by treating the fibres with alkalis or organic bases, aiming to reduce the number of carbamate groups. The procedure may also be applied in the manufacturing of regenerated cellulose fibres.

Abstract: The invention is directed to a procedure for manufacturing cellulose carbamate by reacting isocyanic acid and cellulose at elevated temperature. In the procedure, cellulose, to which biuret or a mixture of biuret and urea has been admixed or absorbed, is heated at a temperature over 170.degree. C. for a sufficient time to produce a quantity of isocyanic acid sufficient for formation of the cellulose carbamate and for accomplishing the reaction between cellulose and isocyanic acid. The heating is accomplished at 170.degree.-250.degree. C., preferably at about 220.degree. C. The biuret quantity is 3-50% by weight of the cellulose weight and the urea quantity is 0-95% by weight of the cellulose weight.

Abstract: The production of cellulose carbamate fibers or films by reacting cellulose with urea to form cellulose carbamate which is dissolved in alkaline solution to form a spinning solution which is spun through an acid precipitation bath is improved by subjecting the cellulose carbamate prior to dissolution in alkaline solution to irradiation of about 0.05-10 Mrad. After dissolution in alkaline solution the same may be subjected to further mild irradiation.

Abstract: The invention relates to cellulose carbamate solutions having improved capacity for fiber spinning or film formation therefrom. The addition of urea to the aqueous alkali in which the cellulose carbamate is dissolved results in an increase in the amount of cellulose carbamate that can be dissolved and a decrease in the viscosity and clogging number of the solution as compared to such solutions without urea.

Abstract: The present invention concerns a procedure for producing cellulose carbamate from cellulose and urea. To avoid alkali treatment of the cellulose used as starting material with a view to decreasing the degree of polymerization of the cellulose, the cellulose in web form is exposed to a radiation dose of preferably 0.5 to 10 Mrad from a radiation source, whereafter the cellulose is reacted with urea at elevated temperature.

Abstract: The present invention concerns a procedure for precipitating cellulose carbamate from an aqueous alkali solution. The solution is brought into contact with an aqueous solution of sulphuric acid containing one or several cations selected from the group consisting of Na, Al, Mg, Zn and Ca cations, whereby in the precipitation of cellulose carbamate the advantage is gained that the dry matter content of the fibre can be made high enough.

Abstract: An alkali-soluble cellulose derivative is produced by treating cellulose with liquid ammonia having urea dissolved therein, removing the ammonia, resulting in cellulose having urea distributed therethrough, and heating the thus obtained cellulose-urea to cause reaction between the urea and cellulose and form alkali-soluble cellulose carbamate. This cellulose carbamate can be precipitated from alkaline solution in the form of cellulose carbamate film or fiber.