Method and unit for sterilizing packaging sheet material for manufacturing sealed packages of pourable food products

#The present invention relates to a method and unit for sterilizing packaging sheet material for manufacturing sealed packages of pourable food products.

#As is known, numerous pourable food products, such as fruit juice, UHT (ultra-high-temperature processed) milk, wine, tomato sauce, etc., are sold in packages formed, on fully automatic packaging machines, from packaging sheet material, which may be constituted by pre-cut blanks or by a continuous web or strip of packaging material which is folded and longitudinally sealed to define a continuous, longitudinally sealed packaging material tube.

#The packaging material may be constituted by a single or multi-layer plastics material, polymeric material, mineral-filled polymeric material or a laminated paperboard-type material. By way of example, one known type of paperboard-type packaging material has a multilayer structure comprising a layer of paper material covered on both sides with layers of heat-seal material, e.g. polyethylene. In the case of aseptic packages for long-storage products such as UHT milk, the packaging sheet material comprises a layer of barrier material defined, for example, by an aluminum film, which is superimposed on a layer of heat-seal plastic material and is in turn covered with another layer of heat-seal plastic material which eventually defines the inner face of the package contacting the food product.

#Preferred embodiment/s of the invention is/are disclosed in the following description and illustrated in the accompanying drawings, in which:

#FIG. 1 shows a lateral elevation of a portion of a packaging machine for producing aseptic sealed packages of pourable food products and featuring a sterilizing unit in accordance with the present invention;

#FIG. 2 shows an enlarged view in perspective of the FIG. 1 sterilizing unit;

#Reference number 1 in FIG. 1 indicates as a whole a packaging machine for producing aseptic sealed packages (not shown) of pourable food products from a packaging sheet material 2.

#Machine 1 comprises a sterilizing unit 3 for sterilizing the packaging sheet material 2, which is fed, for example, off a known reel (not shown) along a substantially vertical path P. More specifically, on leaving the reel, packaging sheet material 2 is fed, in the illustrated example, along a substantially horizontal path Q and is detoured along vertical path P by a guide roller 4.

#To produce packages with pre-applied auxiliary items, such as reclosable opening devices 5 of plastic material—e.g. of the type illustrated in International Patent Application WO 98/18684 filed by the present Applicant—packaging sheet material 2 is fed through a conventional application unit (not shown)—e.g. an injection-molding unit of the type described in International Patent Application WO 98/18608 filed by the present Applicant—at the output of which packaging sheet material 2 comprises a succession of opening devices 5 equally spaced along an intermediate longitudinal portion of packaging sheet material 2. At the output of the application unit and upstream from sterilizing unit 3, storage (not shown) is conveniently provided to store packaging sheet material 2 and compensate for the different feeds of the two units (step feed and continuous feed respectively).