PRODUCTION OF POLY ALPHA-1,3-GLUCAN FORMATE FILMS
A process for making poly alpha-1,3-glucan formate films by extrusion is disclosed. These films are translucent or transparent and can be used in packaging applications.
1 . A process for making a poly alpha-1,3-glucan formate film comprising:
(a) dissolving poly alpha-1,3-glucan in an aqueous formic acid solvent composition to provide a solution of poly alpha-1,3-glucan formate;
(b) extruding the solution of poly alpha-1,3-glucan formate 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 formate film.
2 . The process according to claim 1 , wherein the solvent composition comprises:
(a) at least about 80% formic acid and at most about 20% water;
(b) at least about 90% formic acid and at most about 10% water; or
(c) at least about 95% formic acid and at most 5% water.
3 . The process according to claim 1 , wherein the solvent composition further comprises a solubility additive, a plasticizer additive or a mixture thereof.
4 . The process according to claim 1 , wherein the poly alpha-1,3-glucan is dissolved in the solvent composition at a concentration of:
(a) from about 2 wt % to about 20 wt %;
(b) from about 3 wt % to about 15 wt %; or
(c) from about 5 wt % to about 10 wt %.
5 . The process according to claim 1 , wherein the coagulation bath comprises a water bath.
6 . The process according to claim 1 , wherein the film-shaped wet gel has a breaking stress of at least about 1.5 MPa, at least about 2.0 MPa or at least about 2.5 MPa.
7 . A poly alpha-1,3-glucan formate film made according to claim 1 .
8 . A film comprising poly alpha-1,3-glucan formate.
9 . The film according to claim 8 , 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 of from about 10 to about 100 MPa.
10 . The film according to claim 8 , wherein the poly alpha-1,3-glucan formate has a formate degree of substitution (DoS) of from about at least 0.1 to 3.
11 . A label, packaging article or security document comprising the film of claim 8 .
12 . An article labelled with or packaged by the label or packaging article of claim 11 .
13 . A process for making a poly alpha-1,3-glucan film comprising:
(a) dissolving poly alpha-1,3-glucan in an aqueous formic acid solvent composition to provide a solution of poly alpha-1,3-glucan formate;
(b) extruding the solution of poly alpha-1,3-glucan formate 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;
(e) removing the water from the film-shaped wet gel to form a poly alpha-1,3-glucan formate film; and
(f) removing the formate in the poly alpha-1,3-glucan formate film to form the poly alpha-1,3-glucan film.
14 . The process according to claim 13 , 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 sulfuric acid, dilute caustic, basic buffer or by boiling in acidic or basic water.