Gas barrier structures

Claim 2

A composite structure comprising a base synthetic thermoplastic polymeric layer having two coatings on one side of the base layer, the first coating being adjacent the base layer and being a solvent-based urethane primer, which when dry allows an aqueous dispersion or solution of polyvinyl alcohol to "wet out" the primer, in an amount in the range of from 0.3 to 3.0 g/m² of the base layer, and the second coating being placed on the exposed surface of the first coating and comprising a polyvinyl alcohol gas barrier material in an amount in the range up to about 2.0 g/m² of said base layer, said second coating having been formed from a dispersion or solution.

Claim 3

The composite structure of Claim 1 wherein the primer is a two-component urethane primer.

Claim 4

The composite structure of Claim 1 or Claim 2 wherein the polyvinyl alcohol is present in an amount of from 0.15 to 1.0 g/m².

Claim 5

The composite structure of any preceding claim wherein the polyvinyl alcohol has a saponification value of at least 9 mole per cent.

Claim 6

The composite structure of Claim 4 wherein the polyvinyl alcohol has a saponification value of at least 99 mole percent.

Claim 7

The composite structure of any preceding claim wherein a heat-sealable layer is adhered to the second coating.

Claim 8

The composite structure of Claim 6 wherein the heat-sealable layer is adhesively coated to the second coating.

Claim 9

The composite structure of Claim 6 wherein the heat-sealable layer is extrusion coated to the second coating.

Claim 10

A composite structure comprising a base synthetic thermoplastic polymer layer selected from nylon, polyethylene, polypropylene, polyester, ionomer and ethylene/vinyl acetate copolymer, said layer having two coatings on one side thereof, the first coating being adjacent to the base layer and being a solvent-based primer, which when dry allows an aqueous dispersion or solution of polyvinyl alcohol to wet out the primer, in an amount of from 0.5 to 3.0 g/m² of the base layer, and the second coating being placed on the exposed dried surface of the first coating and comprising a polyvinyl alcohol gas barrier material in an amount in the range of from 0.15 to 1.0 g/m² of said base layer, said second coating having been formed from a dispersion or solution.

Claim 11

A composite structure comprising a base synthetic thermoplastic polymer layer selected from nylon, polyethylene, polypropylene, polyester, ionomer and ethylene/vinyl acetate copolymer, said layer having two coatings on one side thereof, the first coating being adjacent to the base layer and being a solvent-based primer, which when dry allows an aqueous dispersion or solution of polyvinyl alcohol to wet out the primer, in an amount of from 0.5 to 3.0 g/m² of the base layer, and the second coating being placed on the exposed dried surface of the first coating and comprising a polyvinyl alcohol gas barrier material in an amount in the range of from 0.15 to 1.0 g/m² of said base layer, said second coating having been formed from a dispersion or solution.

Claim 12

A composite structure of Claim 9 wherein the primer is a two-component primer.

Claim 13

A composite structure of Claim 9 or Claim 10 wherein the polyvinyl alcohol has a saponification value of at least 9 mole percent.

Claim 14

A process for forming a composite film comprising: a) coating a base film with a solvent-based urethane primer which when dry allows an aqueous solution or dispersion of polyvinyl alcohol to wet out the primer, and drying said primer to form a primer coating in an amount in the range of about 0.3 to about 3.0 g/m² of the base film; b) coating the dried primer with an aqueous dispersion or a solution of polyvinylalcohol, and drying said dispersion or solution to form a gas barrier coating in an amount in the range of about 0.5 to about 2.0 g/m² of the base film.

Claim 15

A process for forming a composite film comprising: a) coating a base film with a solvent-based urethane primer which when dry allows an aqueous solution or dispersion of polyvinyl alcohol to wet out the primer, and drying said primer to form a primer coating in an amount in the range of about 0.3 to about 3.0 g/m² of the base film; b) coating the dried primer with an aqueous dispersion or a solution of polyvinylalcohol, and drying said dispersion or solution to form a gas barrier coating in an amount in the range of about 0.5 to about 2.0 g/m² of the base film.

Claim 16

The process of Claim 12 wherein the gas barrier coating of composite film is subsequently adhesively laminated to a heat sealable film.

Claim 17

The process of Claim 12 or Claim 13 wherein the polyvinyl alcohol coating is present in an amount of from 0.15 to 1.0 g/m².

Claim 18

The process of any of Claims 12 to 14 wherein the base film is unoriented and the composite film is oriented after drying the polyvinyl alcohol coating.

Claim 19

The process of Claim 15 wherein the composite film is oriented monoaxially.

Claim 20

The process of any of Claims 12 to 14 wherein the base film is unoriented nylon film.

Claim 21

A food package comprising food enveloped in a film composite, said film composite comprising a base synthetic thermoplastic polymeric film on the outside of the package, a primer solvent-based urethane coating, in an amount of 0.3 to 2.0 g/m² of the base film, on the inner side of the base film, a polyvinyl alcohol gas barrier coating adjacent to the primer coating, in an amount of up to about 2.0 g/m² of the base film, and a heat sealable layer adhered to the gas barrier coating by adhesive lamination or extrusion lamination, said gas barrier layer having been coated from an aqueous dispersion or a solution thereof.

Claim 22

A food package comprising food enveloped in a film composite, said film composite comprising a base synthetic thermoplastic polymeric film on the outside of the package, a primer solvent-based urethane coating, in an amount of 0.3 to 2.0 g/m² of the base film, on the inner side of the base film, a polyvinyl alcohol gas barrier coating adjacent to the primer coating, in an amount of up to about 2.0 g/m² of the base film, and a heat sealable layer adhered to the gas barrier coating by adhesive lamination or extrusion lamination, said gas barrier layer having been coated from an aqueous dispersion or a solution thereof.