PLASTIC LAMINATE AND FLEXIBLE TUBE

Abstract: A plastic laminate consisting of at least one plastic web and at least two plastic films disposed at each side of the plastic web and preferably connected to the web by bonding is disclosed, where the laminate is pliable, and where respective melting points of the plastic films are approximately the same. Also, a flexible tube made by successive rolling up and welding edge to edge of a strip of plastic laminate in a way known per se, preferably during simultaneous embedding of a reinforcing thread in the welding area, is disclosed. By choosing suitable plastic films there may be achieved an improved plastic laminate and a correspondingly improved flexible tube which advantageously may be used for different purposes and which also may find application in direct contact with foodstuffs.

Description: Plastic Laminate and Flexible Tube The present invention concerns a plastic laminate of the kind indicated in claim 1. Particularly, the invention concerns a plastic laminate developed as an alternative to the usual PNC-laminates on the market today, and which e.g. are used for: - liners for water basins and swimming pools - underroofs in buildings - tarpaulins for covering e.g. house roofs - tarpaulins for keeping out water or sunlight (turnips and potatoes) - tarpaulins for lorries (covering goods or for sides and roof of trailers) - clothing and furniture covering - flexible hoses with steel or plastic threads welded in for air, water or venti- lation - flexible hoses with steel or plastic threads welded in for process and foodstuff industry - as external finishing layer on certain products (expansion joints) - packing (for foodstuffs with an approved external layer) In other words, the invention has the purpose of indicating a new and improved plastic laminate which may be used for the above purposes, and which furthermore may find application directly in contact with foodstuffs. The plastic laminate according to the invention is characterised in that the laminate is pliable, and that respective melting points of the plastic films are approximately the same. By choosing suitable plastic films, there may hereby be achieved a new and improved plastic laminate which may advantageously be used for the purposes indicated in the introduction and which furthermore may find application directly in con- tact with foodstuffs. Suitably, the plastic laminate according to the invention is thus designed so that the plastic web has a total thickness in the range 60 - 200 μm, preferably about 80 μm, and is made of polyester, and that the plastic films each have a thickness in the range 50 - 200 μm, preferably 65 - 105 μm, and are made of polyethylene or polypropylene. Particularly for covering purposes (tarpaulins) of almost any kind it will be an extra advantage that the plastic laminate according to the invention is designed so that between the plastic web and one of the plastic films there is disposed a further plastic film in the form of an e.g. coloured polyurethane film. Hereby is achieved a very du- rable plastic laminate in a simple way with a particularly exclusive look as the soft and pliable polyurethane film may furthermore be dyed with strong colours. Accordingly, it may be particularly advantageous that the plastic laminate according to the invention is designed so that the plastic films, which constitute respective outer sides of the plastic laminate, consist of transparent plastic films of neutral colour, and that the plastic web is made of coloured plastic threads or of plastic threads dyed after the weaving as characteristic colours are used which may, for example, serve as indication of the application of the plastic laminate. Thus it will be obvious if a plastic laminate according to the invention for use as bed in water basins or swimming pools is provided with a strongly blue coloured plastic web. For building applications, e.g. as underroof in buildings, it will be suitable to use a plastic web with a strong yellow or orange colour. For covering purposes in the nature, e.g. in farming, the plastic web may accordingly be dyed in suitable green colour shades. In the same way, the above described plastic laminate with an intermediate plastic film of dyed polyurethane film may serve as an indication of the area of use of the tarpaulin. A green plastic laminate according to the invention of this kind may, for example be intended for covering purposes in farming, a blue plastic laminate according to the invention of this kind may, for example, be intended for maritime use, whereas a cor- responding red plastic laminate, like the other coloured plastic laminates of this kind, may be intended for making custom-made tarpaulins for lorries, trailers etc. The invention also concerns a flexible tube which in a way known per se is made by successive rolling up and welding edge to edge of a strip of plastic laminate, preferably during simultaneous embedding of a reinforcing thread in the welding area, the flexible rube being characterised in that the strip is made of a plastic laminate according to the invention, and that the reinforcing thread is of plastic or steel, preferably steel. Suitably, the flexible tube according to the invention may be designed so that it is made from a plastic laminate where the plastic web has a total thickness in the range 60 - 200 μm, preferably about 80 μm, and is made of polyester, and that the plastic films have a thickness in the range 50 - 200 μm, preferably 65 - 105 μm, and are made of polyethylene or polypropylene so that the total thickness of the plastic laminate is in the range 160 - 600 μm. With the purpose of giving the flexible tube according to the invention an extra durable outer side, it may be advantageous that it is made of plastic laminate comprising a further plastic film in the form of an e.g. coloured polyurethane film disposed between the plastic web and one of the plastic films. For application for different purposes it may furthermore be suitable that the flexible tube according to the invention is made from a plastic laminate where plastic films constituting respective outer sides of the plastic laminate consist of a transparent plastic film of neutral colour, and that the plastic web is made of coloured plastic threads or of plastic threads dyed after the weaving as characteristic colours are used which may, for example, serve as indication of the application of the plastic laminate. The invention will now be explained in more detail in the following in connection with some examples of making plastic laminate and flexible tube, respectively, according to the invention. Example 1 : By means of a suitable laminating facility, a plastic web of polyester with a thickness of about 80 μm with two plastic films of polyethylene with a thickness of about 105 μm are laminated in such a way that the plastic web is enclosed by the plastic films, in that a suitable glue is used, e.g. a hot-melt glue based on polyamide. The plastic web and the plastic films are woven and made, respectively, in such a way that the finished plastic laminate is pliable (flexible). Example 2: By means of a suitable laminating facility, a plastic web of polyamide with a thickness of about 80 μm with two plastic films of polypropylene with a thickness of about 65 μm are laminated in such a way that the plastic web is enclose by the plastic films, in that a suitable glue, e.g. an thermoplastic elastomer, is used. The plastic web and the plastic films are woven and made, respectively, in such a way that the finished plastic laminate is pliable. Example 3: By means of a suitable laminating facility, a plastic web of polyester with a thickness of about 80 μm with three plastic films, namely two outer films of substantially transparent polyethylene with a thickness of about 65 μm and one polyurethane film, preferably dyed, with a thickness of about 100 μm disposed between the outer films, are laminated in such a way that the plastic web is enclosed by the plastic films as suitable glues, e.g. thermoplastic poly amides or elastomers, are used. The plastic web and the plastic films are woven and made, respectively, in such a way that the finished plastic laminate is pliable. Example 4: By means of a suitable laminating facility, a plastic web, e.g. of polyester, with a thickness of about 80 μm made of dyed plastic threads, or dyed after the weaving, as characteristic colours are used which e.g. may serve as indication to the area of use of the plastic laminate, with two plastic films of neutral colour, e.g. of polyethylene, with a thickness of about 65 μm is laminated. A suitable glue is used, e.g. a thermoplastic elastomer. The plastic web and the plastic films are woven and made, respectively, in such a way that the finished plastic laminate is pliable. Example 5: A plastic laminate according to any of the examples 1 - 4 is cut into strips with a width of about 25 mm, corresponding to a tube diameter of 20 - 50 mm. By means of a suitable apparatus, a flexible tube is made by successive rolling up and welding (hot air welding) edge to edge of a strip of the plastic laminate under simultaneous embedding of a reinforcing thread of steel (or plastic) in the weld area, i.e. in such a way that the reinforcing thread in the finished flexible tube is enclosed between the two welded edges of the helical strip, i.e. so that an inner side edge section of the strip is continually welded together with an opposite outer side edge section of the strip by pressure and heat action as the melting points of the respective outer plastic films of the strip of plastic laminate are the same or approximately the same. Example 6: A plastic laminate according to any of the examples 1 - 4 is cut into strips with a width of about 32 mm, corresponding to a tube diameter of 50 - 500 mm. By means of a suitable apparatus, a flexible tube is made by successive rolling up and welding (hot air welding) edge to edge of a strip of the plastic laminate under simultaneous embedding of a reinforcing thread of steel (or plastic) in the weld area, i.e. in such a way that the reinforcing thread in the finished flexible tube is enclosed between the two welded edges of the helical strip, i.e. so that an inner side edge section of the strip is continually welded together with an opposite outer side edge section of the strip by pressure and heat action as the melting points of the respective outer plastic films of the strip of plastic laminate are the same or approximately the same. Also, it is to be mentioned that plastic web and plastic films, respectively, may be provided with suitable additives with the purpose of imparting different properties of technical or utility nature to the finished plastic laminate and the flexible tubing, re- spectively, for example, the plastic web and/or the plastic films may be added fire re- tardants, plasticizers, antistatic agents, dyes etc. An overriding requirement for the finished plastic laminate and the finished flexible tube is that the plastic laminate, irrespectively of thickness, has to be fire resisting, and that the plastic laminate is simultaneously to be approved for use with foodstuffs. A fire retarding plastic laminate according to the invention may, depending on the thickness, be made in two ways. In case of thin laminates one may chose to place a fire resisting plastic web in the centre and to laminate a combustible plastic film approved for foodstuffs at both sides of the plastic web. By heavier plastic laminates, e.g. for tarpaulins, one may choose to dispose a fire retarding plastic web in the centre and to laminate a fireretarding plastic film approved for foodstuffs on both sides of the plastic web. Finally, it is to be mentioned that in some cases it may be advantageous to omit making the web fire resisting as fire retardants may imply that the plastic web becomes brittle. In order to maintain the fire retarding effect, a metal film (or other fireproof film) may be disposed on both sides of the web and in this way make a fire retarding barrier. This method may advantageously e.g. be used in connection with a 5-layer laminate, i.e. where the thickness of the centre web is e.g. 40 - 50 μm, the thickness of the metal film on both sides of the web is e.g. 20 - 25 μm and the thicknesses of the outer films are e.g. 40 - 50 μm. For other purposes, it may be advantageous to dispose a barrier-film at the centre of the laminate. If a barrier for certain gases and if protection of the barrier- film against sharp objects is desired, a web may be laid on both sides of the barrier-film before a PNC-free film is laid outermost on both outer sides of the laminate. Such a 5-layer laminate may typically be used for making flexible tubing for ventilation, e.g. in coal mines, where there is need for conducting ventilating air through the galleries and where for security against the leaking of gas into the ventilating tubes. The barrier-film is thus protected against mechanical damages by the outer layers of web and cover films when the miners are moving about with the tubes.

Claims: CLAIMS 1. A plastic laminate consisting of at least one plastic web and at least two plastic films disposed at each side of the plastic web and preferably connected to the web by bonding, characterised in that the laminate is pliable, and that respective melting points of the plastic films are approximately the same. 2. A plastic laminate according to claim 1, characterised in that the plastic web has a total thickness in the range 60 - 200 μm, preferably about 80 μm, and is made of polyester, and that the plastic films each have a thickness in the range 50 - 200 μm, preferably 65-105 μm, and are made of polyethylene or polypropylene. 3. A plastic laminate according to claim 1 and 2, characterised in that between the plastic web and one of the plastic films there is disposed a further plastic film in the form of an e.g. coloured polyurethane film. 4. A plastic laminate according to claim 1-3, characterised in that the plastic films, which constitute respective outer sides of the plastic laminate, consist of transparent plastic films of neutral colour, and that the plastic web is made of coloured plastic threads or of plastic threads dyed after the weaving as characteristic colours are used which may, for example, serve as indication of the application of the plastic laminate. 5. A flexible rube made by successive rolling up and welding edge to edge of a strip of plastic laminate, preferably during simultaneous embedding of a reinforcing thread in the welding area, characterised in that the strip is made of a plastic laminate according to claim 1, and that the reinforcing thread consists of plastic or steel, preferably steel. 6. A flexible tube according to claim 5, characterised in that it is made of a plastic laminate where the plastic web has a total thickness in the range 60 - 200 μm, preferably about 80 μm, and is made of polyester, and that the plastic films have a thickness in the range 50 - 200 μm, preferably 65 - 105 μm, and are made of polyethylene or polypropylene so that the total thickness of the plastic laminate is in the range 160 - 600 μm. 7. A flexible tube according to claim 5, characterised in that it is made of a plastic laminate comprising a further plastic film in the form of an e.g. coloured polyurethane film disposed between the plastic web and one of the plastic films. 8. A flexible tube according to claim 5, characterised in that it is made of a plastic laminate according to claim 4, i.e. the plastic films constituting respective outer sides of the plastic laminate consist of a transparent plastic film of neutral colour, and that the plastic web is made of coloured plastic threads or of plastic threads dyed after the weaving as characteristic colours are used which may, for example, serve as indication of the application of the plastic laminate.

Inventors: CHRISTENSEN KIM VALLY ELLENTOF, CHRISTENSEN, KIM, VALLY, ELLENTOFT
Applicants: CHRISTENSEN KIM VALLY ELLENTOF, KIMLON INVEST APS, CHRISTENSEN, KIM, VALLY, ELLENTOFT
Application year: 2001
Main classification: B23B27
IPC codes: B32B27, F16L11