Packing laminate provided with crease lines

#The present invention relates to a packing laminate provided with crease lines for conversion to packing containers.

#The invention also relates to a method for the manufacture of a packing laminate.

#Packing containers of the non-returnable type are often manufactured of material in the form of webs or sheets provided with crease lines. The material is then converted by folding and sealing to a packing container of the desired shape. To this end a laminated material is used, among others, which contains different material layers which impart to the combined laminate the desired properties when stiffness, strength and impermeability to liquids are required. A packing laminate, used frequently, comprises a centrally positioned relatively thick carrier layer of fibrous material which layer is covered on both sides with homogeneous plastic layers. The plastic layers are constituted of thermoplastic material which makes possible a simple sealing of the material by heating and compression of the plastic layers on the two parts of material which are to be joined together.

#A preferred embodiment of the arrangement in accordance with the invention will now be described in detail with reference to the figures on the enclosed schematic drawing.

#FIG. 1 shows in perspective a part of a packing container wall with a sealing fin which has been folded to lie against the outside of the packing container laminate.

#FIG. 1a shows in perspective the reverse side of the packing container wall of FIG. 1 with the crease lines which are utilized in folding the packing container wall (as shown in FIG. 2) being shown.

#The packing laminate shown schematically in FIG. 1 is of a known type and comprises a relatively thick, central carrier layer of e.g. paper, which layer imparts the required stiffness to the material. In order to prevent the fibrous carrier layer from absorbing moisture from the environment and from the packed goods the carrier layer is provided on both sides with thin layers of a homogeneous plastic material which is preferably of the thermoplastic type. Depending on the type of contents which are to be kept in the packing container manufactured from the packing laminate the packing laminate may also comprise further layers for different purposes, e.g. an aluminium layer which is impervious to light so as to prevent the contents from being exposed to and affected by daylight. Further layers with special objectives are also conceivable. Since the type of laminate described is well-known to those versed in the art, the different layers have not been marked on the laminate shown in the figures, but for the sake of greater clarity the laminate has been drawn as if it consisted of a single layer.

#In FIG. 1 is shown a portion of a packing container wall 1 with a seal of the inside facing material to inside facing material type. This seal is achieved in that along the edge zones which are to be joined the thermoplastic layers of the material facing towards the inside of the packing container are heated, whereupon the layers are pressed against one another so that a seal is produced with a sealing fin 2 situated on the outside of the package. So that it should not form an obstacle and attach itself to neighbouring packages or the like the sealing fin 2 is subsequently folded so as to lie against the outside of the packing container. In the area of the seal the packing container will therefore have three-fold wall thickness and comprise, more particularly, an inner material layer 3 which constitutes the actual packing container wall in the sealing area, and two material layers 4 and 5 forming the sealing fin 2. The material layer 4 constitutes a part of the material layer 3 folded about 180.degree. and the material layer 5 constitutes a continuation of the opposite of the two wall portions sealed in the sealing fin.

#The type of seal described above is customary and occurs in a great number of packing containers of the non-returnable type. In a known non-returnable package which is used e.g. for liquid dairy products and which is manufactured by conversion of a material web to a tube provided with a longitudinal joint, which is filled with contents and is sealed off by means of transverse seals situated at equal distances, this type of seal is used. These packages which after filling and sealing are given a practically cushion-like shape are subsequently converted with the help of forming jaws to substantially parallelepipedic shape, whereby among other things the cushion-corners are pressed flat and are folded in and sealed against the sides of the packing container. As a result the sides on which the sealing fins are situated will be folded about 180.degree. along a crease line which is situated right-angled to the sealing fin.