the heat sealing layer of the multilayer film of the present invention comprising a polypropylene ( pp ) homopolymer or copolymer has a vicat softening point of less than 105 ° c . measured under astm d 1525 . pp might be present as a heterogeneous or a homogeneous polymer produced with single site catalyst . it may also be a blend of such a material with following 1 . another pp polymer such as random copolymer or homopolymer ( among others ) 2 . a polyethylene polymer such as an alpha olefin copolymer with density 0 . 860 to about 0 . 960 or such as an ethylene ester copolymer 3 . a cyclic olefin copolymer 4 . a styrene polymer 5 . an ionomer or a methacrylic acid copolymer 6 . polybutene polymer in a preferred case , the vicat softening point of the heat sealing layer is less than 100 ° c . as mentioned above , this is an unexpected effect , as the vicat softening point of the polymer is so close to the actual thermal conditions that the material is subjected ( going up to 95 ° c .). the vicat softening point is the determination of the softening point for materials such as polypropylene or polyethylene , which have no definite melting point . it is taken as the temperature at which the specimen is penetrated to a specified depth by a flat - ended needle with a defined circular or square cross - section , under a specified load . the oxygen barrier used may be a material such as a polyvinylidene chloride homopolymer or copolymer or an ethylene vinyl alcohol copolymer ( evoh ). other oxygen barrier materials are also well known in the art . as example , oxygen barrier materials , also polyamides or polyesters may be used . 1 . a polypropylene homopolymer or copolymer having a vicat softening point of less than 105 ° c . measured under astm d 1525 . it is preferably a homogeneous polymer produced with single site catalyst , 2 . pp polymer such as random copolymer or homopolymer ( among others ) 2 . polyethylene polymer such as an alpha olefin copolymer with density 0 . 860 to about 0 . 960 or such as an ethylene ester copolymer 3 . a cyclic olefin copolymer 4 . a styrene polymer 5 . an ionomer or a methacrylic acid copolymer 1 . styrene butadiene copolymer 2 . a blend of styrene butadiene copolymer and an ethylene alpha olefin copolymer between the inner heat sealing layer and the oxygen barrier layer may exist further layers that could comprise any of the polymers mentioned in the possibilities for inner heat sealing layer . preferred materials are ethylene vinyl acetate , ethylene alpha olefin copolymers , ema polymers , polypropylene copolymers , polybutylene , styrene homopolymers or copolymers . any of the layers described above may also include additives well known in the art such as slip agents , antiblock , polymer processing aids , antistatic , antifog , acid scavengers , odour scavengers and the like . a person skilled in the art may select the right additives according to any particular needs . in a preferred version of the application , the film is irradiated with e beam radiation of levels from 1 to 10 mrad . a 5 layer film is produced in a double bubble ( the double bubble method is described in u . s . pat . no . 3 , 456 , 044 , incorporated herein by reference ) commercial line with the following structure : inner ( sealing ) layer , 100 % pp1 adjacent layer 93 % e1 + 7 % additives barrier layer pvdc commercial grade adjacent layer 30 % m1 + 65 % e3 + 5 % additives outer layer 95 % s1 + 5 % additives a 5 layer film is produced in a double bubble ( the double bubble method is described in u . s . pat . no . 3 , 456 , 044 ) commercial line with the following recipe inner ( sealing layer ), 80 % pp1 + 20 % pp2 adjacent layer 93 % e1 + 7 % additives barrier layer pvdc commercial grade adjacent layer 30 % mi + 65 % e3 + 5 % additives outer layer 95 % s1 + 5 % additives a 5 layer film is produced in a double bubble ( the double bubble method is described in u . s . pat . no . 3 , 456 , 044 ) commercial line with the following recipe inner ( sealing layer ), 100 % pp3 adjacent layer 93 % e1 + 7 % additives barrier layer pvdc commercial grade adjacent layer 30 % m1 + 65 % e3 + 5 % additives outer layer 95 % s1 + 5 % additives in all the above examples , the thickness of the layers are ( in microns ) 8 , outer layer 10 , adjacent layer 4 , barrier layer 6 , adjacent layer 27 , heat sealing layer under exactly the same conditions a commercial product fmxbk was produced . all the samples were e - beam radiated with a dose of 4 mrad prior to bag making . material from samples 1 , 2 , 3 , and comparative sample were made into bag configuration in a pouch making machine . then the bags were filled with water and sealed at the open end . then the bags were put in a hot water bath and cooked at 95 c for 5 hours . after this thermal treatment , the bags were examined if their seals were destroyed and if delamination was noticed .