Process for the production of cellulosic moulded bodies

Abstract

The invention relates to a process for the manufacture of cellulosic flat films and cellulosic membranes in the form of flat membranes whereby a solution of cellulose in an aqueous tertiary amine oxide is moulded in film form using an extrusion nozzle which has an oblong extrusion gap and is led into a precipitation bath via an air gap whereby the cellulosic flat film is formed in the precipitation bath, characterized in that the cellulosic flat film is stretched in the transverse direction after entering the precipitation bath.

We claim:  
     
       1. Process for the manufacture of cellulose flat films comprising: 
       providing a solution of cellulose in an aqueous tertiary amine oxide,  
       conveying the solution through an extrusion nozzle having an oblong extrusion gap whereby the solution is in the form of a film,  
       conveying the extruded solution through an air gap into a precipitation bath, whereby a cellulose flat film is formed, and  
       stretching the cellulosic flat film in the transverse direction.  
     
     
       2. Process according to  claim 1  further comprising stretching the cellulosic flat film in the longitudinal direction in the air gap wherein the film is stretched in the range of 0.2 to 5 times. 
     
     
       3. Process according to  claim 1  or  claim 2  further comprising washing the cellulose flat film prior to stretching the cellulose flat film. 
     
     
       4. Process according to  claim 1  or  claim 2  further comprising washing the cellulose flat film, drying the cellulosic flat film, and moistening the dried cellulosic flat film prior to stretching. 
     
     
       5. Process according to  claim 1  or  claim 2  further comprising washing the cellulose flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       6. Process according to  claim 3  comprising stretching the cellulosic flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       7. Process according to  claim 4  comprising stretching the cellulosic flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       8. Process according to  claim 1  or  claim 2  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       9. Process according to  claim 3  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       10. Process according to  claim 4  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       11. Process according to  claim 5  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       12. Process according to  claim 6  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       13. Process according to  claim 7  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       14. Process for manufacturing a cellulosic flat membrane having a desired permeability comprising the steps of: 
       providing a solution of cellulose in an aqueous tertiary amine oxide,  
       conveying the solution through an extrusion nozzle having an oblong extrusion gap whereby the solution is in the form of a film,  
       conveying the extruded solution through an air gap into a precipitation bath, whereby a cellulose flat film is formed,  
       stretching the cellulosic flat film in the transverse direction to produce a cellulosic flat membrane having a desired permeability.  
     
     
       15. Process according to  claim 14  further comprising stretching the cellulosic flat film in the longitudinal direction in the air gap wherein the film is stretched in the range of 0.2 to 5 times. 
     
     
       16. Process according to  claim 14  or  claim 15  further comprising washing the cellulose flat film prior to stretching the cellulose flat film. 
     
     
       17. Process according to  claim 14  or  claim 15  further comprising washing the cellulose flat film, drying the cellulosic flat film, and moistening the dried cellulose flat film prior to stretching. 
     
     
       18. Process according to  claim 14  or  claim 15  comprising stretching the cellulosic flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       19. Process according to  claim 16  comprising stretching the cellulosic flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       20. Process according to  claim 17  comprising stretching the cellulose flat film in the air gap wherein the film is stretched up to 3.5 times. 
     
     
       21. Process according to  claim 14  or  claim 15  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       22. Process according to  claim 16  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       23. Process according to  claim 17  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       24. Process according to  claim 18  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       25. Process according to  claim 19  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       26. Process according to  claim 20  wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 
     
     
       27. Process according to  claim 14  or  claim 15  further comprising utilizing the stretched cellulosic flat film to make one selected from the group consisting of a packaging material for foodstuffs, a waste bag, a carrier bag, a film for agricultural applications, a film for diapers, a substrate for compounds, a film for use in an office, a film for use in a household, and a membrane to separate substances in mixtures. 
     
     
       28. Process according to  claim 1  or  claim 2 , further comprising drying the film whilst fixing the film.  
     
     
       29. Process according to  claim 14  or  15 , further comprising drying the film whilst fixing the film.