Method of making an elastic film, in particular for a hygienic article
An elastic film for a hygienic article is made by first premixing polymer components to form a polymer composite that contains styrene block copolymers and then extruding the polymer composite to make at least one layer. During the premixing or the extruding zeolites are added having pores of a size larger than 2.5 Angstrom and smaller than 5.5 Angstrom.
1. A method of making an elastic film used in making a diaper closure or elastic for a diaper, the method comprising the steps of:
(a) premixing polymer components and a white oil approved for use in medical applications as a plasticizer oil to form a polymer composite that contains styrene block copolymers;
(b) extruding the polymer composite to make an elastic film having at least one layer; and
(c) adding during the premixing or the extruding in a proportion of 1% by weight to 5% by weight of the elastic film, a mixture of first and second zeolites of the ZSM-5 structural type wherein the first and second zeolites in the mixture have pore openings of approximately 3 Angstroms and approximately 5 Angstroms respectively, so that the first and second zeolites thereby forming the elastic film having at least one layer with a polymer matrix, wherein the zeolites are embedded in the polymer matrix and homogeneously distributed throughout the polymer matrix so that the elastic film having at least one layer minimizes the odor of styrene monomers released by the styrene block copolymers.
2. The method of making an elastic film defined in claim 1 wherein the polymer mixture contains more than 40% by weight of styrene block copolymers.
3. The method of making an elastic film defined in claim 1 wherein the polymer composite contains a styrene block copolymer, polystyrene and polyethylene.
4. The method of making an elastic film defined in claim 2 wherein styrene block polymer is a styrene isoprene styrene block copolymer (SIS), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS) or a mixture of these polymers.
5. The method of making an elastic film defined in claim 1 wherein according to step (c) the amount of zeolite in the mixture of the first and second zeolites having different pore sizes added during the premixing or the extruding of the polymer composite is 5% by weight of the elastic film.