초록 ▼

As a first aspect, the present invention is directed to a process for making a heat-shrinkable annular film, comprising: (A) extruding an annular extrudate downward from an annular die; (B) quenching the annular extrudate by applying a quenching liquid to the annular extrudate; (C) reheating the ext

As a first aspect, the present invention is directed to a process for making a heat-shrinkable annular film, comprising: (A) extruding an annular extrudate downward from an annular die; (B) quenching the annular extrudate by applying a quenching liquid to the annular extrudate; (C) reheating the extrudate to an orientation temperature of from 130° F. to 210° F., resulting in a reheated annular extrudate; and (D) orienting the reheated annular extrudate while the reheated annular extrudate is in the solid state, the orientation being carried out with a total orientation factor of at least 2, so that the resulting oriented, heat-shrinkable film has a total free shrink at 185° F. of at least 10 percent. The extrudate comprises at least one semi-crystalline polyamide selected from the group consisting of: (i) polyamide 6, (ii) polyamide 66, (iii) polyamide 6/66, and (iv) polyamide 6/12. The semi-crystalline polyamide makes up at least 5 volume percent of the annular extrudate. At least 50% of the quenching liquid cascades down the annular extrudate for a distance of at least 2 inches. The quenching liquid makes initial contact with the annular extrudate within 0.1 to 8 inches of the annular die.

대표청구항 ▼

What is claimed is: 1. A process for making a heat-shrinkable annular film, comprising: (A) extruding an annular multilayer extrudate downward from an annular die, the annular multilayer extrudate comprising: (i) a first layer which is an outer seal layer, the first layer comprising at least one me

What is claimed is: 1. A process for making a heat-shrinkable annular film, comprising: (A) extruding an annular multilayer extrudate downward from an annular die, the annular multilayer extrudate comprising: (i) a first layer which is an outer seal layer, the first layer comprising at least one member selected from the group consisting of a polyolefin having a density of from 0.88 g/cm3 to 0.917 g/cm3, and ionomer resin, and (ii) a second layer comprising at least one semi-crystalline polyamide selected from the group consisting of polyamide 6, polyamide 66, polyamide 6/66, and polyamide 6/12, and with the annular multilayer extrudate comprising at least one member selected from the group consisting of polyamide 6, polyamide 66, polyamide 6/66, and polyamide 6/12 in an amount of at least 30 volume percent, based on total film volume; (B) quenching the annular extrudate by applying a quenching liquid to the annular extrudate, with the quenching liquid absorbing heat from the annular extrudate as at least 50% of the quenching liquid cascades down the annular extrudate for a distance of at least 2 inches, the quenching liquid making initial contact with the annular extrudate at a distance of from 0.1 to 8 inches downstream of a point at which the annular extrudate emerges from the annular die; (C) reheating the extrudate to an orientation temperature of from 130° F. to 210° F., resulting in a reheated annular extrudate; (D) orienting the reheated annular extrudate while the reheated annular extrudate is in the solid state, the orientation being carried out with a total orientation factor of at least 2, so that an oriented, heat-shrinkable film is produced, the oriented film having a total free shrink at 185° F. of at least 30 percent; and wherein the process is carried out so that the film exhibits: % Transparency≧5.33(% Haze)−31.5. 2. The process according to claim 1, wherein the quenching liquid passes through a central passageway through the annular die and into to an interior volume within the annular extrudate, the interior volume being between a point at which the annular extrudate emerges from the annular die and a point at which the annular extrudate converges into lay-flat configuration, the quenching liquid being applied to an inside surface of the annular extrudate, the quenching liquid cascading downward into a collection pool above the point at which the annular extrudate converges into lay-flat configuration, with the quenching liquid being drawn out of the collection pool and up through a discharge conduit passing through the central passageway through the annular die, so that the extrudate is quenched by the quenching liquid cascading down the interior surface of the annular extrudate. 3. The process according to claim 1, further comprising quenching the extrudate by contacting an outside surface of the annular extrudate with the quenching liquid and supporting the annular extrudate with a means for supporting, the means for supporting being inside the annular extrudate, the supporting of the extrudate beginning at a distance of from 0 to 8 inches downstream the point at which the extrudate emerges from the annular die. 4. The process according to claim 3, wherein the means for supporting the extrudate comprises contacting an inside surface of the annular extrudate with a second quenching liquid provided to a second means for and supporting the annular extrudate with a means for supporting located inside the annular extrudate, the supporting of the extrudate beginning at a distance of from 0 to 8 inches downstream the point at which the extrudate emerges from the annular die. 5. The process according to claim 3, wherein the means for supporting is provided by supplying a gas to an interior volume within the annular extrudate, the interior volume being between a point at which the annular extrudate emerges from the annular die and a point at which the annular extrudate converges into lay-flat configuration, the gas being provided so that the interior volume has a pressure above ambient pressure. 6. The process according to claim 5, wherein the means for supporting further comprises an air shoe positioned in the interior volume of the annular extrudate, the air shoe emitting air therefrom to provide a supportive air cushion between the extrudate and the air shoe, the air shoe providing the supportive air cushion between the extrudate and the air shoe at a distance beginning from 0 to 8 inches downstream of the annular die. 7. The process according to claim 6, wherein the air shoe emits air having a temperature of from −10° C. to 25° C. 8. The process according to claim 6, wherein the air shoe emits air having a temperature of from 0° C. to 25° C. 9. The process according to claim 6, wherein the air shoe emits air having a temperature of from 5° C. to 10° C. 10. The process according to claim 6, wherein the air shoe has a length of from about 4 inches to about 50 inches, and a diameter of from about 1 inch to about 50 inches, the air shoe having a plurality of airflow holes therein, each hole having a diameter of from about 0.01 to about 0.25 inch, and the holes in the air shoe are within a distance of from about 2 millimeters to about 40 millimeters of one another. 11. The process according to claim 6, wherein air under a pressure of from about 1 to about 100 pounds per square inch is supplied to the air shoe. 12. The process according to claim 6, wherein a ratio of an inside diameter of the annular die gap to the outside diameter of the air shoe is from about 1:1.1 to about 1:0.5. 13. The process according to claim 1, wherein at least 70 percent of the quenching liquid cascades down the extrudate for a distance of at least 3 inches, the quenching liquid making initial contact with the extrudate at a distance of from 0.1 to 6 inches downstream of the annular die. 14. The process according to claim 1, wherein the quenching liquid is applied to an outside surface of the annular extrudate, and at least 80 percent of the quenching liquid cascades down the extrudate for a distance of at least 4 inches, the quenching liquid making initial contact with the extrudate at a distance of from 0.1 to 5 inches downstream of the annular die. 15. The process according to claim 1, wherein the quenching liquid is applied to an outside surface of the annular extrudate, and at least 90 percent of the quenching liquid cascades down the extrudate for a distance of at least 5 inches, the quenching liquid making initial contact with the extrudate at a distance of from 0.1 to 4 inches downstream of the annular die. 16. The process according to claim 1, wherein the quenching liquid is applied to an outside surface of the annular extrudate, and at least 99 percent of the quenching liquid cascades down the extrudate for a distance of at least 8 inches, the quenching liquid making initial contact with the extrudate at a distance of from 0.3 to 3 inches downstream of the annular die. 17. The process according to claim 16, wherein the quenching liquid making initial contact with the annular extrudate at a distance of from 1 to 3 inches downstream of the annular die. 18. The process according to claim 1, wherein the quenching liquid makes initial contact with the outside surface of the annual extrudate at a distance of from 1.5 to 3 inches downstream of the annular die. 19. The process according to claim 1, wherein the quenching liquid comprises water and the quenching liquid is emitted from a water ring and the quenching liquid is at a temperature of from 0° C. to 25° C. as it emerges from the water ring. 20. The process according to claim 19, wherein the quenching liquid is emitted from the water ring at a temperature of from 5° C. to 16° C. 21. The process according to claim 1, wherein the quenching liquid is applied to the annular extrudate from a plurality of water rings, with a stream of water being applied to the outside surface of the extrudate from each water ring. 22. The process according to claim 1, wherein the semi-crystalline polyamide makes up at least 35 volume percent of the annular extrudate, based on total extrudate volume, and the orientation is carried out with a total orientation factor of at least 5, and the oriented film exhibits a total free shrink at 185° F. of at least 30 percent. 23. The process according to claim 1, wherein the semi-crystalline polyamide makes up at least 40 weight percent of the annular extrudate, based on total extrudate weight, and the orientation is carried out with a total orientation factor of at least 6, and the oriented film exhibits a total free shrink at 185° F. of at least 40 percent. 24. The process according to claim 1, wherein the semi-crystalline polyamide makes up at least 50 weight percent of the annular extrudate, based on total extrudate weight, and the orientation is carried out with a total orientation factor of at least 7, and the oriented film exhibits a total free shrink at 185° F. of at least 50 percent. 25. The process according to claim 1, wherein the semi-crystalline polyamide makes up at least 60 weight percent of the annular extrudate, based on total extrudate weight, and the orientation is carried out with a total orientation factor of at least 8, and the oriented film exhibits a total free shrink at 185° F. of at least 55 percent. 26. The process according to claim 1, wherein the reheating is carried out by immersing the extrudate in a hot bath having a temperature of from 130° F. to 180° F., with the extrudate being immersed for a period of from 1 to 40 seconds. 27. The process according to claim 26, wherein the reheating is carried out by immersing the extrudate in a hot bath at a temperature of from 145° F. to 175° F., with the extrudate being immersed for a period of from 2 to 10 seconds. 28. The process according to claim 27, wherein the reheating is carried out by immersing the extrudate in a hot bath at a temperature of from 150° F. to 170° F., with the extrudate being immersed for a period of from 3 to 7 seconds. 29. The process according to claim 28, wherein the hot bath contains hot water, and the annular extrudate is reheated by immersion in the hot water. 30. The process according to claim 1, wherein the semi-crystalline polyamide in the second layer is a primary component present in a blend with a secondary component, with the primary component making up from 20 to 99 weight percent of the blend, and the secondary component making up from 1 to 80 weight percent of the blend, and the secondary component comprises at least one member selected from the group consisting of polyamide 6/69, polyamide MXD6, polyamide MXDI, polyamide 66/610, amorphous polyamide, polyether block amide copolymer, polyester, EVOH, polystyrene, polyolefin, and ionomer resin. 31. The process according to claim 1, wherein the annular extrudate has a total thickness of from about 5 mils to about 70 mils. 32. The process according to claim 1, wherein the heat-shrinkable film has a total thickness of from about 1 to 5 mils. 33. The process according to claim 1, wherein a biaxial orientation is carried out by passing the reheated extrudate over a trapped bubble of air while simultaneously drawing the reheated extrudate in its a longitudinal direction. 34. The process according to claim 1, further comprising annealing the heat-shrinkable multilayer film. 35. The process according to claim 1, further comprising irradiating the annular extrudate. 36. The process according to claim 1, further comprising extrusion-coating one or more additional layers onto the annular extrudate. 37. The process according to claim 36, wherein at least two additional layers are extrusion coated onto the annular extrudate, and at least one of the additional layers comprises polyvinylidene chloride. 38. The process according to claim 1, wherein the multilayer extrudate further comprises: (A) a third layer that serves as a barrier layer, the third layer comprising at least one member selected from the group consisting of hydrolyzed ethylene/vinyl acetate copolymer, polyvinylidene chloride, amorphous polyamide, polyamide MXD6, polyester, and polyacrylonitrile; and (B) a fourth layer that serves as a tie layer, the fourth layer being between the first layer and the third layer. 39. The process according to claim 38, wherein the first layer is a first outer layer, the fourth layer is a first tie layer, and the second layer is directly adhered to the third layer, and the multilayer film further comprises a fifth layer that is a second outer layer and a sixth layer that serves as a second tie layer, the sixth layer being between the fifth layer and third layer. 40. The process according to claim 39, wherein the extrudate has the following layer arrangement: seal/first tie/polyamide/second tie/barrier/third tie/second outer wherein the seal layer is the first layer, the first tie layer is the fourth layer, the polyamide layer is the second layer, the barrier layer is the third layer, the second tie layer is the sixth layer, and the outer layer is the fifth layer. 41. The process according to claim 39, wherein the polyamide layer is a first polyamide layer, and the film further comprises a seventh layer that is a second polyamide layer, and the film has the following layer arrangement: seal/first tie/first polyamide/barrier/second polyamide/second tie/second outer. 42. The process according to claim 39, wherein the second outer layer comprises at least one member selected from the group consisting of ethylene/alpha-olefin copolymer, olefin homopolymer, polyamide, polyester, ethylene/unsaturated ester copolymer, and ionomer resin. 43. The process according to claim 1, wherein the annular extrudate comprises polyamide in an amount of at least 85 volume percent, based on total film volume. 44. The process according to claim 43, wherein the annular extrudate comprises polyamide in an amount of at least 98 percent, based on total film volume. 45. The process according to claim 43, wherein the annular extrudate comprises polyamide in an amount of substantially 100 percent, based on total film volume. 46. The process according to claim 43, wherein the annular extrudate comprises: (A) a first layer, the first layer being an outer film layer which serves as a heat seal layer, the first layer comprising at least one member selected from the group consisting of: (i) a semi-crystalline polyamide having a melting point of up to 215° C. and (ii) a blend of a semi-crystalline polyamide having a melting point of above 215° C. with (a) amorphous polyamide and/or (b) or semi-crystalline polyamide having a melting point of up to 215° C.; and (B) a second layer comprising at least one semi-crystalline polyamide having a melt point above 215° C. 47. The process according to claim 46, wherein the second layer comprises a blend of the semi-crystalline polyamide having a melt point above 215° C. with at least one member selected from the group consisting of polyamide 6/12 having a melt point below 215° C., polyamide 6/69, polyamide MXD6, polyamide 66/610, and amorphous polyamide. 48. The process according to claim 1, wherein the annular extrudate is not irradiated before it is oriented.