PRODUCTION OF POLY ALPHA-1,3-GLUCAN FILMS
An extrusion process for making a poly alpha-1,3-glucan film is disclosed. These films can be translucent and used in packaging applications.
1 . A process for making a poly alpha-1,3-glucan film comprising:
(a) dissolving poly alpha-1,3-glucan in a solvent composition to provide a solution of poly alpha-1,3-glucan;
(b) extruding the solution of poly alpha-1,3-glucan into a coagulation bath to make a film-shaped wet gel;
(c) washing the film-shaped wet gel with water;
(d) optionally, plasticizing the film-shaped wet gel with a plasticizer additive; and
(e) removing the water from the film-shaped wet gel to form a poly alpha-1,3-glucan film.
2 . The process according to claim 1 , wherein the solvent composition comprises an aqueous base.
3 . The process according to claim 2 , wherein the aqueous base is selected from the group consisting of aqueous potassium hydroxide, aqueous sodium hydroxide and aqueous tetraethyl ammonium hydroxide.
4 . The process according to claim 1 , wherein the concentration of the base in the solvent composition is:
(a) from about 5 wt % to about 15 wt %; or
(b) from about 7 wt % to about 13 wt %.
5 . The process according to claim 1 , wherein the solvent composition further comprises a solubility additive, a plasticizer additive or a mixture thereof.
6 . The process according to claim 1 , wherein the concentration of the poly alpha-1,3-glucan in the solution is in the range of:
(a) from about 10 wt % to about 30 wt %; or
(b) from about 15 wt % to about 23 wt %.
7 . The process according to claim 1 , wherein the coagulation bath comprises an aqueous acid or methanol.
8 . The process according to claim 7 , wherein the aqueous acid comprises aqueous sulfuric acid.
9 . The process according to claim 7 , wherein the coagulation bath further comprises sodium sulfate, potassium sulfate, boric acid or a mixture of two or more thereof.
10 . The process according to claim 1 , wherein the film-shaped wet gel has a tensile strength of at least about 1.5 MPa, at least about 2.0 MPa or at least about 2.5 MPa.
11 . A poly alpha-1,3-glucan film made according to claim 1 .
12 . A film comprising poly alpha-1,3-glucan.
13 . The film according to claim 12 , wherein the film has at least one of:
(a) a haze of less than about 10%, less than about 5% or less than about 3%; or
(b) a breaking stress from about 10 to about 100 MPa.
14 . A label, packaging article or security document comprising the film of claim 12 .
15 . An article labelled with or packaged by the label or packaging article of claim 14 .