Snia Viscosa Societa Nazionale Industria Applicazioni Viscosa

Asahi Kasei Kogyo Kabushiki Kaisha

Gianfranco Angelini

Roberto Leoni

Alberto Baldini

Angelo Calloni

Ugo Paoletti

Novello Leoncini

Bice Pallesi

Process for the continuous production of viscose rayon yarns having a high egree of whiteness, comprising extruding a viscose solution into a coagulating bath, drawing and coagulating the extruded filaments, advancing said filaments in a substantially helical path while they undergo all the treatments required for the production of the finished yarn, which process is characterized by, after the exit of the filaments from the spinning bath, completion of the coagulation to a coagulation index not higher than 1 and a treatment with water having a non-alkaline pH.

Process for the continuous production of viscose rayon yarns having high

A process for the xanthation of alkali-cellulose comprises the reaction of he alkali-cellulose with CS.sub.2 in excess with respect to the desired xanthate substitution degree at a pressure which increases from the initial 110 mm Hg to about 400-500 mm Hg and at a temperature increasing from about 21.degree. C. to about 23.degree.-25.degree. C. The unreacted CS.sub.2 is removed from the reactor, once the desired xanthate substitution degree is reached, by application of a vacuum. This viscose rayon continuous spinning process eliminates the need for the usual desulphuration phase for decreasing the sulphur content and for bleaching the product. The viscose obtained has reduced content of compounds capable of forming elementary sulphur. The regenerated cellulose yarn has improved characteristics as to the sulphur content and degree of whiteness.

Process for the preparation of viscose and process for the spinning of

A process for the preparation of high concentration solutions of cellulose erivatives in organic solvents comprises contacting with paraformaldehyde and the solvent a cellulose which has a polymerization degree lower than 300 and preferably not significantly higher than 200. The solvent is selected from among dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

Process for the preparation of solutions of cellulose derivatives in

A process for the preparation of regenerated cellulose shaped bodies from inning dopes comprising solutions of methylol derivatives of cellulose in organic solvent selected from dimethylformamide, dimethylacetamide, dimethylsulphoxide and N-methyl-pyrrolidone is described. The cellulose derivative is coagulated from the spinning dope in a coagulating bath, the main component of which is a high-boiling alcohol capable of reacting with the free (para)formaldehyde and with the bound (para)formaldehyde of the methylol derivative to a degree varying with the temperature. It is possible to prepare filaments and yarns having excellent characteristics by starting from solutions having high CH.sub.2 O and cellulose concentrations and high MS ratios.

Process for the preparation of regenerated cellulose formed bodies from

A process for the preparation of regenerated cellulose formed bodies from lutions of cellulose derivatives in organic solvents is disclosed. The cellulose derivatives is firstly precipitated in a coagulating bath constituted of a cellulose non-solvent, non-regenerating organic liquid, then the coagulated body is drawn in subsequent baths and the cellulose is regenerated. The drawing and the regeneration occur, at least in part, concurrently.

A process for the dissolution of cellulose in organic solvents such as dihylformamide, dimethylacetamide, and N-methylpyrrolidone is described which comprises contacting the cellulose with an excess of paraformaldehyde and with the solvent at elevated temperatures, preferably higher than 115.degree. C. The amount of paraformaldehyde used preferably corresponds to at least 13 CH.sub.2 O units per anhydroglucosidic unit of the cellulose. The solution obtained can be rendered stable at room temperature by heating it under stirring to lower the paraformaldehyde content, preferably to not less than 8 CH.sub.2 O units per anhydroglucosidic unit. Formed bodies of regenerated cellulose can be obtained from said solutions by coagulating them in an aqueous bath, which may be alkaline or may be a mixture of water and the solvent of the solution, or even by evaporating the solvent.

Process for the dissolution of cellulose in organic solvents, solutions

A process for the preparation of formed bodies of regenerated cellulose f cellulose derivative solutions in dimethylsulphoxide is disclosed. The solution is extruded and coagulated in a coagulating bath which is a saline acqueous solution having a substantially non-alkaline or preferably a substantially neutral reaction, a formed body being thus produced.

Process for the preparation of formed bodies of regenerated cellulose

A process for the preparation of solutions of cellulose derivatives from which formed bodies, such as fibres or films, of regenerated cellulose can be obtained by coagulation and regeneration, e.g. by wet spinning, is disclosed. The cellulose is transformed into a methylol derivative containing more than 2 units of formaldehyde per anydroglucosidic unit, which derivative is soluble in organic solvents of the class consisting of polar aprotic solvents constituted by N-substituted amides, pyridine and formamide. The methylol derivative is prepared by treating cellulose with paraformaldehyde and dimethylsulphoxide. The methylol derivative is then dissolved in one of the aforesaid solvents, preferably dimethylformamide or dimethylacetamide, to provide spinnable viscous solutions from which formed bodies can be obtained, e.g. by spinning in an aqueous alkaline bath.

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Buscate, Italy

Gianfranco Angelini