Resinous compositions having improved gas permeation resistance and molded structures thereof

Claim 2

A MOLDED STRUCTURE, SAID MOLDED STRUCTURE HAVING BEEN FORMED BY MEANS OF EXTRUSION MOLDING FROM A MOLTEN MIXTURE CONTAINING (A) A POLYOLEFIN AND (B) A SAPONIFIED PRODUCT OF AN ETHYLENE-VINYL ACETATE COPOLYMER HAVING AN ETHYLENE CONTENT OF 25 TO 50 MOLE PERCENT AND A DEGREE OF SAPONIFICATION OF AT LEAST 96 PERCENNT AT A WEIGHT RATIO OF A:B RANGING FROM 95: 5 TO 75:25, SAID MOLDED STRUCTURE HAVING A LAYER STRUCTURE IN WHICH THE POLYMER COMPOSITION IS DIFFERENT IN THE THICKNESS DIRECTION BUT SUBSTANTIALLY IDENTICAL IN THE PLANE DIRECTION AND EVERY TWO ADJACENT LAYER ARE BONDED TO EACH OTHER WITHOUT ANY INTERMEDIATE BONDING LAYER OF AN ADHESIVE, SAID LAYER STRUCTURE CONSISTING ESSENTIALLY OF (A) AT LEAST ONE LAYER IN WHICH THE SAPONIFIED ETHYLENE-VINYL ACETATE COPOLYMER IS PREDOMINANTLY DISTRIBUTED, (B) AT LEAST ONE LAYER IN WHICH THE POLYOLEFIN IN PREDOMINANTLY DISTRIBUTED, AND (C) AT LEAST ONE LAYER WHICH COMPRISES THE SAPONIFIED ETHYLENE-VINYL ACETATE COPOLYMER AND THE POLYOLEFIN IN AMOUNTS SUBSTANTIALLY THE SAME AS THE AVERAGE CONTENT OF THE ETHYLENE-VINYL ACETATE COPOLYMER AND THE POLYOEFIN OF LAYERS (A) AND (B), SAID LAYER (C) INTERVENTING BETWEEN SAID LAYER (A) AND LAYER (B) TO BOND THEM INTERVENING, SAID LAYER STRUCTURE PROVIDING AN IMPROVED GAS PERMEATION RESISTANCE, AND WHEREIN WHEN SAID MOLDED STRUCTURE IS DIVIDED IN THREE LAYERS IN THE THICKNESS DIRECTION, AT LEAST ONE LAYER (A) CONTAINS THE ETHYLENEVINYL ACETATE COPOLYMER SAPONIFIED PRODUCT IN AN AMOUNT EXPRESSED BY FOLLOWING FORMULA

Claim 3

A molded structure set forth in claim 1, wherein the polyolefin is a crystalline homopolymer or copolymer of an olefin expressed by the following formula

Claim 4

A molded structure set forth in claim 1, wherein the polyolefin is a low density polyethylene having a density of from 0.917 to 0.929 g/cc and a melt index of from 0.05 to 5.0 g/10 cm.

Claim 5

A molded structure set forth in claim 1, wherein the polyolefin is a medium density polyethylene having a density of from 0.930 to 0.939 g/cc.

Claim 6

A molded structure set forth in claim 1, wherein the polyolefin is a high density polyethylene having a density of at least 0.940 g/cc.

Claim 7

A molded structure as set forth in claim 1, wherein the polyolefin is an isotactic polypropylene.

Claim 8

A molded structure set forth in claim 1, wherein the ethylene-vinyl acetate copolymer saponified product has an intrinsic viscosity ( eta ), measured at 30*C. with use of a mixed solvent of 85 percent by weight of phenol and 15 percent by weight of water, of from 0.07 to 0.17 l/g.

Claim 9

A molded structure according to claim 1 wherein when said molded structure is divided in three layers in the thickness direction, a first surface layer is said layer (a), and a second layer is said layer (b) and an intermediate layer is said layer (c).

Claim 10

A molded structure according to claim 1 wherein when said molded structure is divided in three layers in the thickness direction, two surface layers comprise said layer (a) and an intermediate layer comprises said layer (b).

Claim 11

A molded structure according to claim 1 wherein when said molded structure is divided in three layers in the thickness direction, two surface layers comprise said layer (b) and an intermediate layer comprises said layer (a).

Claim 12

A molded structure, said molded structure having been formed by means of extrusion molding from a molten mixture containing (A) a polyolefin and (B) a saponified product of an ethylene-vinyl acetate copolymer having an ethylene content of 25 to 50 mole percent and a degree of saponification of at least 96 percent at a weight ratio of A : B ranging from 95 : 5 to 75 : 25, under such condition that the difference between the average flow rate of the polyolefin melt and the average flow rate of the meLt of the saponified ethylene-vinyl acetate copolymer is at least 1 cm/sec and the molten mixture moves through the extrusion apparatus in the form of a laminar flow, said molded structure having a layer structure in which the polymer composition is different in the thickness direction but substantially identical in the plane direction said layer structure consisting essentially of (a) at least one layer in which the saponified ethylene-vinyl acetate copolymer is predominantly distributed, (b) at least one layer in which the polyolefin is predominantly distributed, and (c) at least one layer which comprises a mixture of saponified ethylene-vinyl acetate copolymer and the polyolefin in an approximately the same amount as the average content of layers (a) and (b), said layer (c) intervening between said layer (a) and layer (b) to bond them integrally, said layer structure providing an improved gas permeation resistance, and wherein when said molded structure is divided in three layers in the thickness direction, at least one layer (a) contains the ethylene-vinyl acetate copolymer saponified product in an amount expressed by following formula M1 m1X wherein X is the average content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said molded structure, m1 is a number of from 1.2 to 4, and M1 is the content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said layer, and at least one layer (b) contains the ethylene-vinyl acetate copolymer saponified product in an amount expressed by the following formula M2 m2X wherein X is as defined above, m2 is a number of from 0 to 0.9, and M2 is the content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said layer.

Claim 13

A molded structure, said molded structure having been formed by means of extrusion molding from a molten mixture containing (A) a polyolefin and (B) a saponified product of an ethylene-vinyl acetate copolymer having an ethylene content of 25 to 50 mole percent and a degree of saponification of at least 96 percent at a weight ratio of A : B ranging from 95 : 5 to 75 : 25, under such condition that the difference between the average flow rate of the polyolefin melt and the average flow rate of the meLt of the saponified ethylene-vinyl acetate copolymer is at least 1 cm/sec and the molten mixture moves through the extrusion apparatus in the form of a laminar flow, said molded structure having a layer structure in which the polymer composition is different in the thickness direction but substantially identical in the plane direction said layer structure consisting essentially of (a) at least one layer in which the saponified ethylene-vinyl acetate copolymer is predominantly distributed, (b) at least one layer in which the polyolefin is predominantly distributed, and (c) at least one layer which comprises a mixture of saponified ethylene-vinyl acetate copolymer and the polyolefin in an approximately the same amount as the average content of layers (a) and (b), said layer (c) intervening between said layer (a) and layer (b) to bond them integrally, said layer structure providing an improved gas permeation resistance, and wherein when said molded structure is divided in three layers in the thickness direction, at least one layer (a) contains the ethylene-vinyl acetate copolymer saponified product in an amount expressed by following formula M1 m1X wherein X is the average content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said molded structure, m1 is a number of from 1.2 to 4, and M1 is the content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said layer, and at least one layer (b) contains the ethylene-vinyl acetate copolymer saponified product in an amount expressed by the following formula M2 m2X wherein X is as defined above, m2 is a number of from 0 to 0.9, and M2 is the content (percent by weight) of the ethylene-vinyl acetate copolymer saponified product in said layer.