Snia Viscosa Societa Nazionale Industria Applicazioni Viscosa S.p.a.

Asahi Kasei Kogyo Kabushiki Kaisha

Societa Nazionale Industria Applicazioni Viscosa S.p.a.

Ugo Paoletti

Novello Leoncini

Gianfranco Angelini

Tommaso Benai

Alessandro Volterra

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 is described for the continuous spinning of viscose rayon. Said ocess is characterized by the fact that after the coagulation and drawing of the yarn, a two-stage setting is carried out, the first stage being at higher temperature and acidity than the second stage. The two-stage setting permits one to obtain a yarn which is not only perfectly set but is also substantially desulphurated and the classic desulphuration operation is thus eliminated. The setting is followed by at least one washing and by the other conventional treatments, with the exception of the desulphuration. The viscose rayon continuous spinning process is carried out while the yarn travels in a substantially helical path.

Process for the continuous spinning of viscose rayon

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 is provided herein for continuously spinning viscose yarns by euding viscose into a coagulating bath to form filaments and partially coagulating these filaments to a coagulation index of between 15 and 18, while concurrently stretching said filaments to the desired stretch ratio and then subjecting the filaments to a 2-stage coagulation treatment in which (1) the filaments are advanced without further chemical treatment onto e.g. a first advancing roller where partial spontaneous coagulation occurs such that the coagulation index is between 5 and 8 and (2) a second stage coagulation which comprises contacting the filaments with an acid bath at a temperature between 50.degree. and 100.degree. C. until complete coagulation occurs such that the coagulation index is between 0 and 1. The aforementioned process permits the spinning operation to occur at a much greater speed than was hitherto possible without increasing dimensions of the treatment zones or apparatus.

A device for the continuous spinning of viscose rayon includes a main or cessing roller and a plurality of secondary or advancing rollers set askew with respect to the processing roller. The processing and advancing rollers are carried bracket-like by a support arm in which they are rotatively supported. The actuating structures are located in the vicinity of the supports of the respective rollers. The support arm is hollow and contains the roller supports and the actuating structures, and is located at the end of the unit at which the yarns leave the same after being processed. A plurality of spinning units are arranged in rows and the rows are born by a frame carrying all the necessary accessory devices. Means are provided for preventing the escape of fumes from the treatment liquors into the surrounding room.

Device for the continuous spinning of viscose rayon

The removal of water from viscose rayon yarns in the continuous spinning of such yarns is improved by subjecting the yarns to the action of an air jet before the thermal drying treatment. The air jet impinges on the yarns adjacent their passage from the last liquid treatment zone to the drying zone and is directed approximately tangentially to the treatment roller, that is to the helicoidal path of the yarn. The removal of the water is completed by thermal drying. Up to 50% of the water content, and several times the dry weight of the yarn, is eliminated by the pneumatic treatment. The air jet is directed on the yarn by means of a slit-shaped nozzle having its larger dimension substantially parallel to the treatment roller. A plurality of yarns can be treated concurrently on the same device having a plurality of guide rollers.

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Monza, Italy

Ugo Paoletti