METHOD FOR THE SCRAP-FREE MANUFACTURE OF COATED PROFILES AND THERMALLY SHAPED CONTAINERS

Abstract: A method and a device for scrap-free manufacture of coated profiles and thermoformed containers. A hollow pipe having a cross-section suitable for the desired profile is extruded. The extruded hollow profile is cut longitudinally. Thereafter the profile is planar laminated by a web formed material having desired characteristics. The cut, laminated profile thereafter is formed into the original shape thereof, or another suitable shape, and is formed into container casings. When thermoforming containers, a hollow profile is ex­ truded from a thermoformable material in an extruder, this hollow profile is cut, in one or several longitudinal cuts. In web or roller form such cut profile is supplied to a so called scrap-free thermoforming machinery, where the thermo­ formed containers are manufactured.

Description: Field of the invention The present invention relates to a method and a device for manufacturing of coated profiles, preferably for contai­ ners and for thermoforming of containers. More precisely, the invention relates to scrap-free manufacturing of a con­ tainer body to be closed by at least one end piece and scrap-free thermoforming of containers, respectively. Background of the invention and prior art The problem of the present invention is to minimize the scrap when manufacturing packages, especially packages having qualified barrier characteristics, for instance of the quality required for full conserves. According to a specific embodiment of the invention, the problem of the invention is to make the total procedure, from plastics granulate to a finished packing container, waste or scrap-free, starting out from so called "scrap-­ free" thermoforming technique. The general problem of minimizing waste has, of course, been dealt with before and it is known to extrude an ex­ trudate in pipe form and laminate such pipe by a barrier material. In the Swedish patent No. 751017069 there is shown a method of applying a barrier laminate cross-wise an ex­ truded pipe. According to another method, described in Swedish patent application No. 850170160, the starting point is a profile, which may be solid or hollow, and strips are applied in the longitudinal direction of the profile. In the first mentioned case, where the extrudate is a hollow extrudate, and in the last mentioned case, when the extrudate is a hollow profile, there if obtained an abso­ lutely scrap free manufacture of the "supporting container" casing requiring the largest amount of material, i.e. the seamless inner layer. That, which has been said, is one of the reasons for making extrusion of hollow profiles a most competitive approach to the package manufacturing technique. The dimension of the extrudate defines exactly the dimension of the casing of the container without any need for scrap in­ troducing working, for instance edge cutting. However, according to one embodiment of the present invention fur­ ther working includes a thermo forming process of the so called scrap-free type. According to prior art, webs obtained by planar extru­ sion of plastics through a straight orfice onto a mould roller, in contrary to the cut profile of the present inven­ tion, obtain marginal regions which do not meet the stipu­ lated tolerances, implying that such marginal regions have to be removed as waste material, for instance by roller cutting. However, when extruding pipes and cutting such into casings, the transport volume, from the manufacturing place of the casings and the packages to the filling place, if said locations are geografically separate, will be pretty large and "air containing". The prior art lamination operations are carried out against a support which perhaps does not always provide a sufficient pressure for lamination, meaning there is a risk for air bubbles and an inferior end product. In certain cases the prior art lamination methods do also imply problems with matching the print of the package. Summary of the invention The object of the present invention is to offer alterna­ tives to the known methods and broaden the concept of scrap-­ free manufacturing of a container casing and a thermoformed container by starting out from a hollow profile, which by being cut longitudinally in a waste free manner is given well defined edge regions without any need for subsequent working, at least not scrap introducing working. The invention provides a method of scrap-free manufac­ turing of a coated profile, preferably a container casing. The method is characterized in that the hollow profile with a cross section, possibly obtained after calibration, suitable for, preferably identical to, the desired profile is extruded from an extrudable material in an extruder, that the profile is cut longitudinally, and that the cut profile is planar laminated by a strip type of material having the desired characteristics. Preferably, a container casing of a predetermined length is manufactured from the cut, laminated profile, for in­ stance by reshaping to the original shape, sealing the body longitudinally and cutting it. In order to allow a so called in-plant forming of a con­ tainer, the planar laminated, cut profile is delivered in roller form to the place for manufacturing container casings. After such casings have been manufactured, each one is provided with a first end piece or sealed cross-wise, the end sealed container casing is filled with a product, and the container casing is closed by a second end piece or by a cross-wise seal. In another embodiment where the manufacturing of the package and the filling thereof are carried out geogra­ phically at the same place, the container casing is manu­ factured in line with the planar lamination, and the con­ tainer casing is provided with a first end piece, the end sealed container casing is filled with a product, and fi­ nally the container casing is closed by a second end piece or by a cross-wise seal. In order to obtain a high barrier package, the strip shaped material is selected as a material having qualified gas and water vapour barrier characteristics, for instance a material comprising a metal foil, metallized plastics material or a laminate of high barrier plastics. A preferred embodiment of end pieces, one or two, com­ prises an end piece formed as a layer structure, where an outer layer, proferably of plastics, acts as a mechani­ cally protective barrier and a layer inside said layer acts as a barrier layer. The wall thickness of the extruded hollow profile is determined by the size of the package, however, wall thick­ nesses in the interval 0,2 to 1,0 mm are preferable. According to a further embodiment, the present inven­ tion provides a method for a waste or scrap-free manufac­ ture of packing containers. The method is characterized in that the hollow profile is extruded from a thermoformable material in an extruder, that the hollow profile is cut longitudinally, and that the cut hollow profile in web or roller form or as individual blanks, is supplied to a so called scrap-free thermoforming machinery, for manufacture of said packing containers. In one specific embodiment the hollow profile is coex­ truded, the combination of material is selected such that the hollow profile is given high gas and vapour barrier characteristics, and such that the thermoformed packing container will be heat sealable. The longitudinal or lengthwise cutting may comprise one or several cuts, dependent on the cross section of the hollow profile and the desired size for the thermoforming operation, which is to follow. The wall thickness of the extruded hollow profile ex­ ceeds considerably the film thickness of so called blown films and is at least approximately 0,2 mm. The cut hollow profile may also be planar laminated if necessary, for instance by a metal foil before further pro­ cess steps are applied. The invention also provides a device for scrap-free manufacture of a coated profile, preferably a container casing. The device is characterized by an extruder for ex­ truding a hollow profile having a cross section, possibly after calibration, suited for, preferably equal to, the cross section of the profile, by a device for cutting longi­ tudinally the profile, and by a device for planar lamination of the cut profile with the strip shaped material having de­ sired characteristics. In one embodiment, where the coated profile is a con­ tainer casing, there is a device for manufacturing of con­ tainer casings from cut, laminated profiles. Said device for manufacture of container casings com­ prises preferably a forming device for forming the profile into the original shape, a device for sealing the formed profile longitudinally, and a cutter device for cutting the sealed profile into the predetermined lengths. Preferably, the device for sealing longitudinally com­ prises a strip applicator for applying a strip in the longi­ tudinal joint in order to seal and/or form a barrier. The invention will now be exemplified by reference to the accompanying drawings. Brief description of the drawings Fig. 1 in a schematic side view shows the extruder in a line for manufacturing containers according to the present invention. Fig. 2 shows the cutting and laminating units of the manu­ facturing line, Fig. 3 shows the pipe forming unit of the line, Fig. 4 shows the cutting unit of the line, Fig. 5 shows the filling and sealing unit, Fig. 6 in a schematic side view shows the extruder of an­ other manufacturing line according to the present invention, Fig. 7 shows the cutting and laminating units or stations of the line, Fig. 8 shows the roller unit and palleting station, Fig. 9 shows the pipe forming unit of an inplant line for manufacturing of containers, Fig. 10 shows the cutter unit of the line, Fig. 11 shows the filling and end sealing unit of the line, Fig. 12 shows an alternative embodiment of an end sealing unit, where one end of each container casing is sealed crosswise, and Fig. 13 schematically shows scrap-free manufacture of thermoformed containers or cups. Description of preferred embodiments The extruder 10 in Fig. 1 provides an extrudate 11 in pipe form having a circular cross section 12. The extru­ date may comprise a thermoplastic material, for instance polyprophylene or a copolymer comprising polyprophylene having a thickness in the interval approximately 0,2-1,0 mm. Having in mind that the material normally forms part of a package which is to withstand high temperatures at ste­ rilisation, polyprophylene or suitable copolymeres are pre­ ferable. If so desired a suitable calibration device (not shown) may be arranged between the extruder 10 and a pulling bench 13. It is essential that the cross section of the extruded pipe basically corresponds to the cross section of the desired container casing. A cutting device 14 is arranged for cutting the pipe 11 in the longitudinal direction. Downstreams said cutting device there is arranged guide rails 15 for guiding the cut pipe or hollow profile into such a "flattened" shape that it will be insertable in the nip of a planar lamina­ tion unit, comprising laminating rollers 16, 17 and a glue applicator (not shown) and a drying unit (not shown). To the laminating nip between the rollers 16, 17 there is fed a web 18 of a high barrier material, for instance aluminium foil, from a storage roller 19. The material is fed over a guide roller 20. The term "planar lamination" means general methods for laminating between pairs of rollers, for instance lamination by use of a two component glue or some more up to date version of hot melt, for in­ stance "MOREPRIME". As is well known, planar lamination is very reliable and the risk for the entrapped air spaces mentioned in the introduction is practically not existing. Usually, the web 18 is a laminate or a metal foil which has been coated on both sides thereof or lacquered. Gene­ rally there is required a so called roller cutting opera­ tion for obtaining the correct web width. In spite of the fact that certain waste cannot be avoided, such waste does not comprise waste containing also the thick material of the hollow profile. Following to the planar lamination operation, the cut pipe or laminate 21 is represented by the web 18 and the cut pipe 11. This laminate is fed to a forming and welding station 39 comprising a forming member 22 and a weld device 23, for instance a high frequency welding equipment, for providing a longitudinal joint. Preferably, a sealing strip 24 is used and attached against the joint, and the weld may be a but weld. Alternatively, there may of course be an overlap joint. Pulling benches 25 and 26 transport the formed and welded or sealed pipe to a cutter 27. Individual con­ tainer casings 28 are transferred to a conveyer 29. This conveyor transports the containers to a bottom applicator unit, shown by a singel arrow 30, for mounting of a bottom piece 31. The structure of such a bottom is basically described in the publications mentioned at the introduction. It may be mentioned that the end piece, top or bottom piece, com­ prises an outer layer, generally of plastics, and a barrier layer, for instance of aluminium foil, arranged inside the plastics layer. A further conveyor 32 transports the containers 28 having bottom pieces thereon to a filler 33. Thereafter an end sealing station 34 is arranged for applying a top piece 35, basically of the same type as the end piece 31, however, usually without any arrangement for easy opening. The ready packed and sealed container 28 finally arrives at an output conveyor 36 leading to a packing station (not shown). The line just described is an integrated container manu­ facturing and filling line. In Figs. 6-11 there is shown an­ other application. The arrangement and the procedure, respectively, in Figs. 6 and 7 coincides exactly with what is shown in Figs. 1 and 2. Reference numbers just having an addition of a prime sign have been used in Figs. 6 and 7. In Fig. 8 there is shown how the cut, laminated hollow profile forming the web 21′ is winded up to a roller 37. Such rollers 37 thereafter are placed transport ready on a pallet 38. The object of this is to offer an in plant manu­ facture of containers starting out from the roller material. Figs. 9-11 illustrate a "plant" or filling unit. From a roller 137 a web of material 121′ is withdrawn, comprising the "flattened" pipe material laminated to a barrier material 18, and is formed and welded in a station 39′, identical to the station 39. The ready-formed and longitudinally sealed pipe 40′ is drawn by a pulling bench 26′ towards a cutter 27′. This one cuts the pipe into container casings 28′ of the desired length. The conveyor 25′ feeds the casings to the arrangement in Fig. 11, which is identical to the one in Fig. 5. Inside the circle 41 in Fig. 11 there is shown in a perspective view what the finished containers look like. Inside the circle 42 in Fig. 12 there is shown an alter­ native design, where instead for an end piece 35′ there has been accomplished a cross seal 35″, basically of "tube type". The double arrows 43 in Fig. 12 indicate the cross sealing station where the seal 35′ is accomplished, in an arrangement which for the rest is identical to the one in Fig. 11 and which therefore has the same reference numerals with the additional of a biss-sign. In Fig. 13 the reference number 10 denotes three extru­ ders, each one supplying a flow of material 112, 113 and 114, respectively, to an extruder head 111. In this particu­ lar case, at the output from the head 111, there is obtained a hollow profile in the form of a pipe 115 having a circular cross section and comprising three material layers 112, 113 and 114, where the mid layer for instance may be a gas and vapour barrier layer of "SARAN" and inner and outer layers of polyprophylene. A calibrator 116 may, if so required, be inserted bet­ ween the extruder 111 and a cutter station 117. In the sta­ tion 117 the profile 115 is cut longitudinally, in this case in three strips or webs 118. A pulling bench 119 is arranged for pulling the webs 118 to a cutter, the output of which is a foursided blank. The cutting operation may also be deleted, which is in­ dicated by the encircled section 22. In this case the webs 118 are supplied directly or in roller form for the subse­ quent processing. In this particular case such processing or manufac­ ture takes place in a machinery 123, being a thermoforming machinery of the so called scrap-free type. The machinery is of a well known type, for instance of the type provided by Cincinatti Milacron, Ohio, USA. The machinery has an embossing station 120, where blanks are formed waste free into a size adapted to the final size of a container or tray 125 to be produced in a thermoforming station 126 from the embossed or preformed blank 127. The preforming or embossing generally means a scrap-free re­ distribution of the material of the blanks or webs 118, which are used, for instance redistribution from a four-­ sided contour into a round contour or a thinner centre region than the marginal region. Although specific embodiments have been described and shown on the drawings, it is realized that modifications and alternatives are possible within the scope of the claims. Instead of scrap-free thermoforming in the last embodiment there may for instance be used a traditional thermoforming machinery when manufacturing foursided packing containers from the cut, extruded pipe.

Claims: 1. A method of waste free manufacture of a coated profile having desired characteristics, wherein: a hollow profile having a cross section, possibly obtained after calibration, suitable for, preferably identical to the cross section of the desired profile is extruded from an extrudable material in an extruder, the profile is cut in the longitudinal direction thereof, and the cut profile in planar laminated by a web formed material having the desired characteristics. 2. A method as in claim 1, wherein: a container casing is manufactured from a predetermined length of the cut, laminated profile. 3. A method as in claim 2, wherein: the planar laminated cut profile is delivered in roller form to a manufacturing place for container casings, container casings are manufactured at the manufacturing place, each container casing is welded with a first end piece or provided with a cross-wise seal, the end sealed container casing is filled with the desired product, and the container casing is sealed by a second end piece or by a cross-wise seal. 4. A method as in claim 2, wherein: the container casing is manufactured in line with the planar lamination, the container casing thereafter is provided with a first end piece or a cross-wise seal, the end sealed container casing is filled with a desired product, and the container casing is sealed by a second end piece or by a cross-wise seal. 5. A method as in claim 4, wherein: the web formed material is selected as a material having high gas and water vapour barrier characteristics, for in­ stance a material comprising metal foil, metallized plas­ tics or a laminate of a high barrier plastics. 6. A method as in claim 5, wherein: the end piece is formed as a layer structure, where an outer layer, preferably of plastics, acts as a deformation protec­ tive layer, and the layer inside such layer acts as a barrier layer. 7. A method as in claim 1, wherein: the wall thickness of the extruded hollow profile is selec­ ted in the interval approximately 0,2-1,0 mm. 8. A method for waste free manufacture of packing containers, wherein: a hollow profile is extruded from a thermoformable material in an extruder, the hollow profile is cut in the longitudinal direction thereof, and the cut hollow profile, in web or roller form or as indivi­ dual blanks, is supplied to a thermoforming machinery for the manufacture of said packing containers. 9. A method as in claim 8, wherein: the hollow profile is coextruded, the combination of materials, in a manner known per se, is selected such that the hollow profile is given a high gas and vapour barrier, and such that the thermoformed packing container will be heat sealable. 10. A method according to claim 8, wherein: the hollow profile is cut by several longitudinal cuts. 11. A method as in claim 8, wherein: the wall thickness of the extruded hollow profile is selec­ ted such that it at least is approximately 0,2 mm. 12. A method as in claim 1, wherein: the cut hollow profile also is planar laminated before further process steps are carried out. 13. A method as in claim 1, wherein: the cut hollow profile is supplied to a so called scrap-­ free thermoforming machinery known per se. 14. A device for scrap free manufacture of a coated profile having desired characteristics, comprising: an extruder for extruding a hollow profile having a cross section, possibly after calibration, suitable for, prefe­ rably equal to the cross section of the profile, a device for cutting the profile in the longitudinal direc­ tion, and a device for planar lamination of the cut profile with a web formed material having the desired characteristics. 15. A device as in claim 14, where the coated profile is a container casing, comprising: a device for manufacturing container casings from the cut, laminated profile. 16. A device according to claim 15, wherein: said device for manufacturing container casings comprises a forming device for forming the cut, planar laminated pro­ file to the desired shape, preferably the orginal shape thereof, a device for sealing longitudinally the formed pro­ file, and a cutter device for cutting the sealed profile to the predetermined length. 17. A device according to claim 16, wherein: the device for sealing longitudinally comprises a strip applicator device for applying a strip over the longi­ tudinal joint for sealing.

Inventors: LARSSON, LENNART, PILTZ, LARS ERIC
Applicants: AB AKERLUND & RAUSING
Application year: 1987
Main classification: B29D22
IPC codes: B29C65, B29C69, B29C53, B29D22