Production of poly alpha-1,3-glucan formate films
The present invention is directed toward a process for making poly alpha-1,3-glucan formate films. These films are translucent or transparent and can be used in packaging applications.
1. A film comprising poly alpha-1,3-glucan formate, wherein the poly alpha-1,3-glucan formate has a formate degree of substitution (DoS) from at least 0.1 to 3, and wherein the film has at least one of:
(a) haze less than 10%; and
(b) tensile strength from 10 to 60 MPa.
2. The film according to claim 1 , wherein the film further comprises chitosan formate.
3. The film according to claim 2 , wherein the film is a packaging film.
4. The film according to claim 1 , wherein the film is a packaging film.
5. A process for making a poly alpha-1,3-glucan formate and chitosan formate film comprising:
(a) dissolving poly alpha-1,3-glucan in a formic acid and water solvent composition to provide a solution of poly alpha-1,3-glucan formate;
(b) dissolving chitosan, either in dry form or as a pre-dissolved chitosan-formic acid solution, into the solution formed in part (a)
(c) contacting the solution of poly alpha-1,3-glucan formate and chitosan formate with a surface; and
(d) removing the solvent composition to form a film of poly alpha-1,3-glucan formate and chitosan formate.
6. The process according to claim 5 , wherein the poly alpha-1,3-glucan is dissolved in the solvent composition at a concentration from 5 wt % to 20 wt %.
7. The process according to claim 5 , wherein the solvent composition comprises at least 80% formic acid and at most 20% water.
8. The process according to claim 5 , wherein the solvent composition is removed by:
(a) evaporation at room temperature or elevated temperature and at room pressure or reduced pressure;
(b) optionally rinsing the film with water; and
(c) optionally repeating step (a).
9. A process for making a poly alpha-1,3-glucan film comprising:
(a) dissolving poly alpha-1,3-glucan in a formic acid and water solvent composition to provide a solution of poly alpha-1,3-glucan formate;
(b) contacting the solution of poly alpha-1,3-glucan formate with a surface;
(c) removing the solvent composition to form a poly alpha-1,3-glucan formate film; and
(d) removing the formate in the poly alpha-1,3-glucan formate film to form the poly alpha-1,3-glucan film.
10. The process according to claim 9 , wherein the poly alpha-1,3-glucan is dissolved in the solvent composition at a concentration from 5 wt % to 20 wt %.
11. The process according to claim 9 , wherein the solvent composition comprises at least 80% formic acid and at most 20% water.
12. The process according to claim 9 , wherein the solvent composition is removed by evaporation at room temperature or elevated temperature and at room pressure or reduced pressure.
13. The process according to claim 9 , wherein the formate in the poly alpha-1,3-glucan formate film is removed by washing the poly alpha-1,3-glucan formate film with aqueous sulfuric acid, wet heating or by treatment with aqueous basic solutions.
14. The process according to claim 9 , wherein the process further comprises dissolving chitosan, either in dry form or as a pre-dissolved chitosan-formic acid solution, into the solution formed in part (a) thereby forming a poly alpha-1,3-glucan and chitosan film in part (d).