Plastic and nonmetallic article shaping or treating: processes – Vacuum treatment of work
Patent
1998-01-09
1999-11-30
Peselev, Elli
Plastic and nonmetallic article shaping or treating: processes
Vacuum treatment of work
264187, 2642108, 26421114, 26421117, 1062001, 1062002, 1062003, D01F 202
Patent
active
059937106
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of manufacturing cellulosic moulded members in which a solution containing cellulose dissolved in amino oxides is shaped in a nozzle and the shaped solution is led after an air gap into a precipitation medium. The invention relates in addition to a cellulosic moulded member, produced by shaping a solution containing cellulose dissolved in amino oxides.
Within the framework of the present invention, cellulosic moulded members are understood to be especially fibres such as fibres of finite length, for example staple fibres, but also filaments which are generally combined into yarns. However, films and membranes are also understood to be cellulosic moulded members, the membranes being used in the form of flat membranes and hollow fibre membranes for mass transfer and/or heat exchange, for example in dialysis or oxygenation.
Because of high investment costs and especially because of the great strain on the environment, there is considerable interest in finding alternatives to the viscose process by which at present the majority of cellulose regenerated fibres are manufactured. One of the most promising processes is the spinning of solutions of cellulose in amino oxides, preferably in N-methyl-morpholine-N-oxide (NMMNO), not least because with this process the complicated path via a derivatisation of the cellulose is avoided. It is known that cellulose is soluble in a NMMNO-water system and can be processed into textile fibres by spinning into a mostly aqueous NMMNO-solution (DE 28 30 685, DD 142 898, EP 0 490 870).
High strengths and moduli are characteristic for the fibres produced by the NMMNO process in comparison with viscose fibres. Thus the ultimate tensile strengths lie generally in an approximate range of about 20 to 50 cN/tex and the initial moduli in a range above about 1,500 cN/tex. This means that the strengths are pleasingly high, but often higher than necessary and the moduli clearly too high for some applications in the area of textile fibres with good properties for textile use, in which area the usual viscose fibres which have proved their worth for textile use in clothing have been used with initial moduli clearly below 1,500 cN/tex.
Although the NMMNO process is already being used in commercial production and the fibres produced by this method have proved to be successful for some textile applications, the latter show a number of differences in comparison with the fibres manufactured by the viscose process and cannot therefore be used in textiles in the usual fashion. They show, amongst other things, brittleness and a tendency to fibrillate in the wet state. Also, the values achieved for breaking elongation are not satisfactory. What proves to be disadvantageous, too, is that the variation range of the textile physical characteristic values, when the manufacturing conditions are changed, is small.
Chanzy et al. (Polymer 31 (1990), 400-405) showed a possible way of influencing the strength and modulus of fibres by adding inorganic salts, such as e.g. ammonium chloride or calcium chloride to the NMMNO spinning solution of the cellulose. A clear increase in strength and modulus is achieved by this. The fibres tend therefore even more to brittleness and fibrillation. Fibres of this type, which show the typical behaviour of high-strength, high-modulus fibres, are eminently suitable for many technical purposes, especially in the form of composites in a fixed matrix, but cannot be used in textiles as widely as usual.
A possible way of reducing the modulus to a limited extent, and thus the brittleness of the fibres, consists in using, instead of the precipitation bath generally used and consisting of an aqueous NMMNO solution, a solution of NMMNO in isopropanol or amyl alcohol (SU 1 224 362) or adding certain hydrophilic additives both to the spinning solution and to the precipitation bath. The very slight reduction in strength occurring here can be tolerated since the fibres still have strengths which correspond to those of viscose fibres. Seen overall, these proce
REFERENCES:
patent: 4426228 (1984-01-01), Brandner et al.
patent: 5792399 (1998-08-01), Mervert et al.
Fink Hans-Peter
Frigge Konrad
Nywalt Martin
Purz Hans Joachim
Wachsmann Ulrich
Fraunhofer-Gesellschaft zur Forderung der Angewandten Forschung
Peselev Elli
LandOfFree
Cellulosic molding process and cellulosic moldings does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cellulosic molding process and cellulosic moldings, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cellulosic molding process and cellulosic moldings will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1667508