Process for producing celluose moldings

Details Process for producing celluose moldings Process for producing celluose moldings

1993-11-04

1995-03-28

Tentoni, Leo B.

Plastic and nonmetallic article shaping or treating: processes

With step of cooling to a temperature of zero degrees c. or...

264187, 2642108, 26421111, 26421117, 2642112, 264235, 2642888, 2642905, B29C 3516, B29C 4700, D01D 506, D01F 202

Patent

active

054014476

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a method for producing regenerated cellulose shaped articles, such as a fiber, a film, or a fine powder (or finely divided particle).


BACKGROUND ART

In general, cellulose shaped articles (fiber, film, powder) are produced by mixing a solution, prepared by dissolving cellulose into a solvent by a certain type of method, into a nonsolvent. The methods for dissolving cellulose now used industrially for the above object include two methods: the viscose method found around 100 years ago (late 1890) wherein solid state alkali-cellulose is made by causing an around 20% aqueous alkali solution to act on the cellulose, causing carbon disulfide to react with this, then dissolving in an alkali and the cuprammonium method in which the cellulose is dissolved in a cuprammonium solution. The cellulose molecules in the solutions obtained by these methods do not dissolve in the form of cellulose, but dissolve as a certain cellulose derivative (cellulose xanthate in the viscous method and a cellulose cuprammonium complex in the cuprammonium method). Accordingly, when a cellulose shaped article is manufactured, it is necessary to use regeneration, i.e., a process in which the cellulose derivative is returned to cellulose, in addition to coagulation. For example, when producing a regenerated cellulose fiber, it has been known up to now that the setting of the conditions in the regeneration process is an important factor determining the physical properties of the obtained fiber. Thus, studies have been made to optimize the coagulating and regenerating conditions, aiming at superior physical properties, from various viewpoints, such as improvement of the dope, coagulation conditions (composition of coagulating bath, temperature of coagulation, length of coagulating bath, bath flow, nozzle). For example, mention can be made of the method of using a Muller bath, the polynosic method, the HW modulus method, the high tenacity rayon method, the Lilienfeld method using a concentrated sulfuric acid for the coagulating bath, etc. for the viscose rayon method and the free fall and stretch spinning method etc., for the cuprammonium method. In addition, as a method of dissolving cellulose, studies have focused on cadoxens (cadmium/ethylenediamine/alkali), nioxens (nickel/ethylenediamine/alkali), EWNN (iron/tartaric acid/alkali), and other metal complexes, but these are not superior to the cuprammonium method and the viscose method in terms of safety and economy. Also, neither of the above methods can avoid the generation of toxic gases or discharge of heavy metals in the process of preparation of the solutions or the process of production of the shaped articles, and therefore, have problems when viewed from the standpoint of the work environment or the global environment.
That is, (1) these make use of carbon disulfide and ammonium, which have an adverse effect on the human body, and these have explosive limits. (2) They include copper, which is a heavy metal, and produce harmful waste gas in the processes of dissolution/coagulation/regeneration/scouring, so a vast amount of energy and water are required for their reclamation/purification/disposal, the process becomes longer, and the facilities become longer and larger. (3) Due to (1) and (2), the regenerated cellulose fiber industry must inevitably become a labor-intensive type production style.
On the other hand, voices arose, mostly in the West, from the 1960s to the 1970s warning of the continued industrial use of traditional techniques like the viscose method and the cuprammonium method. The first wave of this which appeared most remarkably was with the pullout of many companies from the viscose rayon business. The second wave has been with the now under way movement toward restriction of discharge and the prohibition of use of harmful substances due to the global scale environmental problems, such as seen in the Environmental Summit. With the above as a background, research has been under way since the 1970s, primarily in Canada a

REFERENCES:
patent: 1881740 (1932-10-01), Lilienfeld
patent: 2169207 (1939-08-01), Lilienfeld et al.

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