Ethylene vinyl alcohol copolymer blend, a process for producing a composite film therefrom and the composite film per se

Claim 2

An ethylene vinyl alcohol copolymer resin blend that is extrudable to produce a film of uniform caliber and excellent oxygen barrier properties, characterised by comprising about 95 to 80 weight percent of ethylene vinyl alcohol copolymer having a molecular weight of about 15,000 to 30,000 and a melting point temperature of about 325 degrees to 375 degrees Fahrenheit (163 to 191°C) and at least 1 weight percent, for example about 5 to 20 weight percent of a plasticizing agent selected from aromatic sulfonamide plasticizers, polyethyl oxazoline, polyvinyl pyrrolidone, polyvinyl formaldehyde, and polyamides having melting point temperatures below.about 400 degrees Fahrenheit (204°C), the plasticizing agent being compatible with . the copolymer and capable of intermolecular hydrogen bonding therewith.

Claim 3

The composition according to claim 1, characterised by containing at least 90 weight percent of the EVOH copolymer.

Claim 4

The composition according to claim 1 or claim 2, characterised in that the polyamide has a molecular weight in the range of about 5,000 to 10,000.

Claim 5

The composition according to claim 1, 2 or 3 characterised in that the plasticizing agent is an aromatic sulfonamide and is selected from o,p-toluene sulfonamide, N-ethyl-o,p-toluenesulfonamide and ethylbenzene sulfonamide.

Claim 6

A process for producing a composite film product of uniform caliper and excellent oxygen barrier properties, characterised by the steps comprising: a. producing an intimate blend of about 95 to 80 weight percent of an ethylene vinyl alcohol copolymer having a molecular weight of about 15,000 to 30,000 and a melt temperature of about 325 degrees to 375 degrees Fahrenheit (163 to 191 o C) and at least 1 weight percent, for example about 5 to 20 weight percent of a plasticizing material therefor; b. heating the composition to effect fusion thereof; c. continuously forcing the fused composition into a coextrusion die; d. simultaneously forcing a fused film-forming resin into the die, the film-forming resin having a composition different from that of the said blend, and being adherent thereto in the fused state; e. combining the blend and resin in the die into a laminar structure comprised of first and second layers, respectively; f. forcing the laminar structure through a die portion wherein said structure is substantially widened and thinned; g. extruding the resultant structure from the die as a composite film; and h. cooling the film to produce the composite film product.

Claim 7

A process for producing a composite film product of uniform caliper and excellent oxygen barrier properties, characterised by the steps comprising: a. producing an intimate blend of about 95 to 80 weight percent of an ethylene vinyl alcohol copolymer having a molecular weight of about 15,000 to 30,000 and a melt temperature of about 325 degrees to 375 degrees Fahrenheit (163 to 191 o C) and at least 1 weight percent, for example about 5 to 20 weight percent of a plasticizing material therefor; b. heating the composition to effect fusion thereof; c. continuously forcing the fused composition into a coextrusion die; d. simultaneously forcing a fused film-forming resin into the die, the film-forming resin having a composition different from that of the said blend, and being adherent thereto in the fused state; e. combining the blend and resin in the die into a laminar structure comprised of first and second layers, respectively; f. forcing the laminar structure through a die portion wherein said structure is substantially widened and thinned; g. extruding the resultant structure from the die as a composite film; and h. cooling the film to produce the composite film product.

Claim 8

The process according to claim 5, characterised by incorporating in the blend a plasticizing material selected from aromatic sulfonamides, polyethyl oxazoline, polyvinyl pyrrolidone, polyvinyl formaldehyde and polyamides having melting point temperatures below about 400 degrees Fahrenheit (204°C).

Claim 9

The process according to claim 6, characterised by the plasticizer being an aromatic sulfonamide selected from o,p-toluene sulfonamide, N-ethyl-o,p-toluenesulfonamide and ethylbenzene sulfonamide.

Claim 10

The process according to any of claims 5 to 7, characterised by the film-forming resin being selected from high molecular weight polyamides having a melting point temperature of about 415 degrees to 440 degrees Fahrenheit (213 to 227°C), partially hydrolyzed ethylene vinyl acetate copolymer adhesives, and anhydride modified polyolefin adhesives.

Claim 11

The process according to claim 8, characterised by the film-forming resin comprising a polyamide having a molecular weight in the range of about 20,000 to 30,000.

Claim 12

The process according to any of claims 5 to 9, characterised by the use of a stationary die in steps (c) to (g) and by casting the film extruded therefrom upon a chill roll.

Claim 13

The process according to any of claims 5 to 10, characterised by increasing the width of said structure in step (f) at least about 40 fold.

Claim 14

The process according to any of claims 5 to 11, characterised in that the thickness of said first layer does / not exceed, at any point across the width of said film, about 40 percent of the mean thickness value of said layer, and wherein at least about 60 percent of said layer has a thickness within about 20 percent of said mean value.

Claim 15

The process according to any of claims 5 to 12, characterised by introducing a second film-forming resin into said die, for combination with the blend and the first-mentioned resin into the laminar structure as a third layer thereof.

Claim 16

The process according to claim 13, characterised by disposing the third layer in full surface contact with the second layer which is the first-mentioned resin and which serves to bond the first and third layers together.

Claim 17

The process according to claim 13 or claim 14, characterised in that the second resin is selected from polyethylene, polypropylene, ethylene vinyl acetate copolymer, and ionomer resin.

Claim 18

The process according to claim 13 or claim 14, characterised in that the first and second resins both. comprise polyamide resins having molecular weights of about 20,000 to 30,000 and melting point temperatures of about 415 degrees to 440 degrees Fahrenheit (213 to 227 0 C), the second and third layers comprised of these resins being disposed on opposite sides of the first layer.

Claim 19

The process according to any of claims 13 to 16, characterised by introducing at least one additional film-forming resin into the die for combination with the blend and the first and second resins into the laminar structure, to form at least a fourth layer thereof.

Claim 20

The process according to claim 17, characterised by providing a fifth layer adjacent the fourth layer, the fifth layer being comprised of an ionomer and the fourth layer comprising an adhesive material which serves to bond the fifth layer to the third layer.

Claim 21

The process according to claim 18, characterised in that the film produced has an overall thickness of about three to five mils (0.08 to 0.13 mm), the first, second and third layers together comprising less than about 50 percent by volume of the film.

Claim 22

The process according to claim 19, characterised in that the second layer lies on the exterior of the film and is about 2.5 times the thickness of said first layer, and wherein the third layer is approximately one-half the thickness of the first layer.

Claim 23

The process according to any of claims 5 to 20, characterised by the additional steps of: i. reheating the film to a temperature suitable for thermoforming thereof; j. subjecting the heated film to mechanical or fluid pressure to stretch at least a portion thereof; and k. cooling the stretched film to set the film in its distorted condition, the set film being substantially free of pin-holes, cracks and like defects.

Claim 24

A composite film characterised in that it comprises successive layers of a film-forming polyamide resin, at least one plasticized ethylene vinyl alcohol copolymer, a film-forming polyamide resin, an adhesive and an ionomer resin, respectively, the film-forming polyamide resin having a molecular weight of about 20,000 to 30,000 and a melting point temperature of about 415 degrees to 440 degrees Fahrenheit (213 to 227°C), the EVOH copolymer having a molecular weight of about 15,000 to 30,000, a vinyl alcohol moiety . content of about 60 to 75'percent thereof, and a melting point temperature of about 325 degrees to 375 degrees Fahrenheit, (163 to 191°C), and said adhesive layer comprising an anhydride modified polyolefin or a partially hydrolyzed ethylene vinyl acetate copolymer.

Claim 25

A composite film characterised in that it comprises successive layers of a film-forming polyamide resin, at least one plasticized ethylene vinyl alcohol copolymer, a film-forming polyamide resin, an adhesive and an ionomer resin, respectively, the film-forming polyamide resin having a molecular weight of about 20,000 to 30,000 and a melting point temperature of about 415 degrees to 440 degrees Fahrenheit (213 to 227°C), the EVOH copolymer having a molecular weight of about 15,000 to 30,000, a vinyl alcohol moiety . content of about 60 to 75'percent thereof, and a melting point temperature of about 325 degrees to 375 degrees Fahrenheit, (163 to 191°C), and said adhesive layer comprising an anhydride modified polyolefin or a partially hydrolyzed ethylene vinyl acetate copolymer.

Claim 26

The film according to claim 22, characterised in that the film is about three to five mils thick (0.8 to 0.13 mm).

Claim 27

The film according to claim 23, characterised in that the adhesive layer is itself a composite comprised of a core having exterior layers of the said adhesive.