Polyethylene multilayer film
AssigneePentacast S.r.l.
InventorGiuseppe Brambilla
Life of this patent
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Abstract
Process for the preparation of a polyethylene multilayer film starting from linear low density polyethylene (LLDPE) by cast-extrusion, wherein the multilayer material coming out from a spreading head is collected on a first roller cooled with water maintained between 10° and 25° C. and the film coming out from the first cooling roller is sent to a second roller cooled with water maintained at a temperature lower than that of the first roller and the second roller has a peripheral velocity or speed of rotation 10-40% higher than that of the first roller. Multilayer film having a yield point and an ultimate elongation comprised within certain limits.
Claims10
A process for preparing a polyethylene multilayer film, having a yield point between 15 and 80 N/nm2 and an ultimate elongation between 50 and 500% wherein a core layer comprises linear low density polyethylene, by cast extrusion, comprising the steps of:
- a) extruding the LLDPE having a density between 0.915 and 0.935 g/cm3 and at least a polymeric material having adhesion properties by a battery of extruders,
- b) stratifying the extruded material in function of the extruder it comes from,
- c) ejecting the stratified material into the atmosphere by forcing it through a lip of a spreading head,
- d) passing the stratified material exiting from the spreading head over a first cooling roller, wherein the first cooling roller is cooled with water and maintained between 10 and 25C, and
- e) conveying the stratified material exiting from the first cooling roller to a second cooling roller, wherein the second cooling roller is cooled with water to a temperature lower than that of the first cooling roller and maintained between 10° and 20° C., while the peripheral velocity of the second cooling roller is 10-40% higher than the first cooling roller, thereby forming the polyethylene multilayer film.
Dependencies are inferred from the claim text.