Support covered with a chitosan-based coating and method for the production thereof

1. A support comprised of a substrate formed of organic and/or inorganic fibres and a chitosan-based coating layer on at least one face of the substrate, wherein the coating layer is a dried residue of an aqueous chitosan-based solution which is comprised of prehydrolyzed chitosan having an average molar mass of less then 130,000 g/mol which is present in the solution in a concentration between 6 and 30% by weight, and wherein the chitosan-based coating layer contains at least 80% by weight of the prehydrolyzed chitosan.

2. A support according to claim 1 , wherein the prehydrolyzed chitosan is present in the coating layer in an amount of from 6 to 15 g/m 2 in dry matter.

3. A support according to claim 1 , wherein the coating layer is in the form of a continuous film.

4. A support according to claim 1 , wherein the prehydrolyzed chitosan has an average molar mass of between 15,000 and 40,000 g/mol.

5. A support according to claim 1 , wherein the prehydrolyzed chitosan concentration in the aqueous solution is between 7 and 12% by weight.

6. A support according to claim 1 , wherein the aqueous solution is further comprised of citric acid in an amount sufficient to dissolve the prehydrolyzed chitosan.

7. A support according to claim 1 , wherein the amount of the prehydrolyzed chitosan in the coating layer is 7 g/m 2 in dry matter.

8. A support according to claim 1 , further comprising a wax layer which covers the chitosan-based coating layer.

9. A process for making a chitosan-coated support member, the process comprising the sequential steps of:

(a) prehydrolyzing chitosan so as to achieve an average molar mass thereof of less than 130,000 g/mol;

(b) forming an aqueous chitosan-based solution comprised of between 6 and 30% by weight of the prehydrolyzed chitosan obtained according to step (a);

(c) coating the aqueous chitosan-based solution onto a face of a substrate formed of organic and/or inorganic fibers to provide a chitosan-based coating layer on the substrate which contains at least 80% by weight of chitosan; and thereafter

(d) drying the chitosan-coated support member so that the prehydrolyzed chitosan remains as a dried layer on the substrate to thereby form the chitosan-coated support member.

10. A process according to claim 9 , wherein step (c) is practiced so as to coat the aqueous chitosan-based solution onto the face of the substrate in only one step.

11. A process according to claim 9 , wherein step (c) is performed by the Meyer bar or blade type coating, metering size-press, coating with an engraved cylinder by direct coating, by transfer coating or reverse coating, curtain coating, by size-press.

12. A process according to claim 9 , wherein step (b) comprises introducing wax into the aqueous chitosan-based solution so that the wax is present in an amount of between 0.1 and 20% by weight of the chitosan.

13. A process according to claim 9 , wherein step (c) is practiced so that the prehydrolyzed chitosan is present in the coating layer in an amount of from 6 to 15 g/m 2 in dry matter.

14. A process according to claim 13 , wherein the prehydrolyzed chitosan is present in the coating layer in an amount of 7 g/m 2 in dry matter.

15. A process according to claim 9 , wherein step (c) is practiced so as to form the coating layer as a continuous film.

16. A process according to claim 9 , wherein step (a) is practiced to obtain prehydrolyzed chitosan having an average molar mass of between 15,000 and 40,000 g/mol.

17. A process according to claim 9 , wherein the prehydrolyzed chitosan concentration in the aqueous chitosan-based solution is between 7 and 12% by weight.

18. A process according to claim 9 , wherein step (b) includes incorporating citric acid into the aqueous chitosan-based solution in an amount sufficient to dissolve the chitosan therein.