Cellulose article manufacturing method
AssigneeViskase Corporation
InventorsNorman Abbye Portnoy, Edward Makoto Kajiwara, Paul Edmund Ducharme, Jr.
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Abstract
In a method for forming a cellulose tube suitable for use as a food casing or as cellophane film, in which a solution of nonderivatized cellulose, tertiary amine N-oxide and water is extruded through an air gap of at least five inches, and into a water bath, such that a wet cellulose tube is formed. The wet tube is inflated from about 55% to 140% or more and dried thereby substantially retaining its work-to-rupture characteristics, especially when compared to viscose-derived tubes.
Claims8
A method for forming a seamless cellulose tubular film of nonderivatized cellulose comprising:
- a) extruding a solution of nonderivatized cellulose, tertiary amine N-oxide cellulose solvent and water as a tube through an air gap and into a nonsolvent bath while internally cooling said tube in said air gap;
- b) removing the tertiary amine N-oxide solvent from the extruded tube to form a substantially solvent-free wet tube of nonderivatized cellulose having a substantially uniform first diameter;
- and
- c) inflating said wet tube to a second larger diameter and maintaining said second larger diameter while drying said wet tube such that the resulting seamless cellulose tubular film
- i) has a dry flat width at least 55% to about 200% greater than the flat width of said wet tube and
- ii) retains a greater percentage of work-to-rupture than a comparable viscose cellulose tubular film subjected to the same drying conditions.
A method for forming a seamless cellulose tubular film of nonderivatized cellulose comprising:
- a) downwardly extruding from an annular die orifice, a solution of nonderivatized cellulose, tertiary amine N-oxide cellulose solvent and water at a temperature between about 200.degree. F. and about 240.degree. F., the solution being extruded in the form of a tube;
- b) continuously passing said extruded tube from said annular die orifice downwardly through an air length and into a nonsolvent first bath, the air length as measured from the annular die gap to the surface of the first bath being about 4 to 12 inches;
- c) internally cooling said tube of extruded solution in said air length;
- d) maintaining said extruded tube in contact with the nonsolvent first bath for a time sufficient for removing the tertiary amine N-oxide solvent from the extruded tube to form a substantially solvent-free wet tube of nonderivatized cellulose;
- e) passing said solvent-free wet tube through a nonsolvent second bath;
- f) drawing the wet tube from the nonsolvent second bath and inflating it to expand the diameter of the wet tube from about 55% to about 200%;
- g) maintaining the inflated diameter of the wet tube while drying it to form said seamless cellulose tubular film that has a dry flat width from at least 55% to about 200% greater than its wet flat width.
A method of forming a tubular cellulose film comprising:
- a) continuously extruding a solution of cellulose, N-methylmorpholine oxide (NMMO) and water from an annular die orifice through an air length 4 to 11 inches and into a bath of nonsolvent liquid containing an 11% to 19% NMMO solution at a temperature of 50.degree. to 80.degree. F.;
- b) retaining said continuously extruded solution in said first bath for a time to remove sufficient NMMO from said extruded solution to form a wet tube having a first diameter;
- c) drawing the wet tube from said bath;
- d) inflating said wet tube to a second diameter up to 140% grater than said first diameter;
- and
- e) maintaining said second diameter while drying said wet tube to form said tubular cellulose film and said film, when rewet, having a retained transverse work-to-rupture such that the value of said retained work-to-rupture versus the percent of said wet tube diameter increase is a line having a slope greater than -0.836.
Dependencies are inferred from the claim text.