Multilayer film for medical solution pouches having reduced proficiency for forming bubbles

1. A method for reducing or preventing the formation of bubbles in a medical solution contained in a pouch after heat sterilization, the method comprising:

cast extruding a flexible multilayer film having an outer layer comprising a copolyester having a dicarboxylic acid component and a diol component;

incorporating a polyamide 612 into said copolyester layer, wherein polyamide 612 is present in an amount from about 15 to 35 weight percent based on the weight of the copolyester layer;

forming the flexible multilayer film into a pouch having an interior space for receiving a medical solution therein by orienting front and rear sheets comprising said flexible multilayer film in a face-to-face relationship and heat sealing said front and rear sheets to each other along opposing adjacent edges to define said interior space, wherein upon packaging a medical solution therein, the pouch is capable of passing the bubble test as set forth in the Chinese State Drug Package Container Material Standard No. YBB00112005, and wherein the multilayer film further comprises

a core layer comprising a combination of a metallocene very low density polyethylene having a density less than 0.910 g/cc and a high density polyethylene having a density greater than 0.940 g/cc;

a second outer layer comprising a combination of a propylene/ethylene copolymer and a styrene-ethylene-butylene-styrene block copolymer; and

first and second adhesive layers joining each of the outer layers to the core layer.

2. The method of claim 1 , wherein the polyamide 612 is incorporated in to the copolyester layer during the step of extruding the film.

3. The method of claim 1 , further including the step of introducing a medical solution into the pouch through an opening therein and sealing said opening closed.

4. The method of claim 1 , wherein polyamide 612 is present in an amount from about 20 to 30 weight percent based on the weight of the copolyester layer.

5. The method of claim 1 , wherein polyamide 612 is present in an amount from about 20 to 35 weight percent based on the weight of the copolyester layer.

6. A method for reducing or preventing the formation of bubbles in a medical solution contained in a pouch after heat sterilization, the method comprising:

cast extruding a flexible multilayer film having an outer layer comprising a copolyester having a dicarboxylic acid component and a diol component;

incorporating a polyamide 612 into said copolyester layer, wherein polyamide 612 is present in an amount from about 15 to 35 weight percent based on the weight of the copolyester layer;

forming the flexible multilayer film into a pouch having an interior space for receiving a medical solution therein by orienting front and rear sheets comprising said flexible multilayer film in a face-to-face relationship and heat sealing said front and rear sheets to each other along opposing adjacent edges to define said interior space, wherein upon packaging a medical solution therein, the pouch is capable of passing the bubble test as set forth in the Chinese State Drug Package Container Material Standard No. YBB00112005, wherein the multilayer film comprises

a first outer layer comprised of the copolyester and polyamide 612 wherein the polyamide 612 is present in an amount from about 15 to 35 weight percent based on the total weight percent of the first outer layer;

a core layer comprising a very low density polyethylene;

a second outer layer of a heat sealable material; and

a first and second adhesive layers joining the first and second outer layers to the core layer, respectively, and wherein the second outer layer comprises a combination of a propylene/ethylene copolymer and a styrene-ethylene-butylene-styrene block copolymer.

7. The method of claim 6 , wherein the propylene/ethylene copolymer is present in amount from about 70 to 90 weight percent and the styrene-ethylene-butylene-styrene block copolymer is present in an amount that is between about 10 and 30 weight percent, based on the total weight percent of the second outer layer.

8. The method of claim 6 , wherein the first adhesive layer comprises a very low density polyethylene having a density less than 0.910 g/cc.

9. A method for reducing or preventing the formation of bubbles in a medical solution contained in a pouch after heat sterilization, the method comprising:

cast extruding a flexible multilayer film having an outer layer comprising a copolyester having a dicarboxylic acid component and a diol component;

incorporating a polyamide 612 into said copolyester layer, wherein polyamide 612 is present in an amount from about 15 to 35 weight percent based on the weight of the copolyester layer;

forming the flexible multilayer film into a pouch having an interior space for receiving a medical solution therein by orienting front and rear sheets comprising said flexible multilayer film in a face-to-face relationship and heat sealing said front and rear sheets to each other along opposing adjacent edges to define said interior space, wherein upon packaging a medical solution therein, the pouch is capable of passing the bubble test as set forth in the Chinese State Drug Package Container Material Standard No. YBB00112005, and wherein the multilayer film further comprises

a core layer comprising a very low density polyethylene that is present in amount from about 80 to 92 weight percent and the high density polyethylene is present in an amount that is between about 8 and 20 weight percent, based on the total weight percent of the core layer;

a second outer layer of a heat sealable material; and

a first and second adhesive layers joining the first and second outer layers to the core layer, respectively.