Carbon dioxide barrier coating

1. A method of preparing a carbon dioxide barrier coating composition comprising mixing:

a) a polymer composition comprising;

i) a solution or dispersion of EVOH or an EVOH/PVOH mixture; and

ii) a polycarboxylic acid polymer;

with

b) a dispersion of clay;

wherein the clay is present in an amount of 35 to 50 weight % based on the total solid content of the carbon dioxide barrier coating composition;

wherein the carbon dioxide transmission rate of a 12 micron PET substrate coated with the carbon dioxide barrier coating composition is less than or equal to 1.3% of the carbon dioxide transmission rate of the uncoated 12 micron PET substrate, when measured at 23° C. and 0% relative humidity.

2. The method according to claim 1 , in which the polycarboxylic acid polymer is present in the amount of 5-20 weight % and the EVOH or PVOH/EVOH is present in the amount of 30-60 weight % of the total solid content of the carbon dioxide barrier coating composition.

3. The method of claim 1 wherein the EVOH is a vinyl alcohol-ethylene copolymer having an ethylene content of less than 20 mol. %.

4. The method of claim 1 wherein the clay dispersion is prepared using a high shear dispersion apparatus selected from a vortex, cavitation, or bead mill type dispersion apparatus.

5. A method of preparing a carbon dioxide barrier material, comprising applying the carbon dioxide barrier coating composition prepared according to the method of claim 1 onto a substrate to form the carbon dioxide barrier coating on the substrate and enhance the carbon dioxide barrier properties of the substrate;

wherein the carbon dioxide transmission rate of a 12 micron PET substrate coated with the carbon dioxide barrier coating composition is less than or equal to 1.3% of the carbon dioxide transmission rate of the uncoated 12 micron PET substrate, when measured at 23° C. and 0% relative humidity.

6. The method of claim 5 , wherein the step of applying onto the substrate a coating composition is carried out within 24 hours of completing the mixing of (i) the polymer composition with (ii) the dispersion of a clay.

7. The method of claim 5 , wherein the substrate is a flexible polymer film.

8. The method of claim 5 , wherein:

X=A /( B·C )>100, in which:

A=Carbon Dioxide Transmission Rate for the substrate at 23° C. and 0% RH without the barrier coating;

B=Carbon Dioxide Transmission Rate for the substrate at 23° C. and 0% RH with the barrier coating; and

C=Coating Weight in g/m 2 (dry).

9. The method of claim 5 , wherein the carbon dioxide barrier material is a laminate material comprising a first film, which is the substrate, and a second film, wherein the layer of the carbon dioxide barrier coating composition is present between the first film and a second film.

10. The method of claim 9 , wherein:

X =( A·D )/( B·C )>200,

in which:

A=Carbon Dioxide Transmission Rate for the laminate at 23° C. and 50% RH without the barrier coating;

B=Carbon Dioxide Transmission Rate for the laminate at 23° C. and 50% RH with the barrier coating;

C=Coating Weight in g/m 2 (dry); and

D=Bond Strength in N/15 mm;

wherein the bond strength D is greater than or equal to 1.0 N/15 mm.

11. A packaged article packaged in a carbon dioxide-rich environment, or a packaged carbonated liquid, wherein the packaging comprises a barrier material prepared according to the method of claim 5 .

12. A method of protecting an article from spoilage, prolonging the shelf life of an article and/or delaying deterioration of an article comprising packaging the article in a carbon dioxide-rich environment, in a package that comprises a carbon dioxide barrier material prepared in accordance with the method of claim 5 .