Method for laminating a tubular film

Abstract

The invention refers to a method for laminating a tubular film (1) preferably manufactured by means of blown film (co-) extrusion with a material capable of absorbing resin or liquids, wherein the tubular film (1) is laminated over its entire perimeter with several layers (10, 11, 12, 13; 20, 21, 22; 30, 31) overlapping or positioned directly opposite one another on their front sides containing material capable of absorbing resin or liquids, so that essentially there are no areas left along the perimeter of the tubular film (1) not covered by the laminated layers (10, 11, 12, 13; 20, 21, 22; 30, 31). The invention also refers to a tubular film laminated in such a way and to various applications.

Claims

1. A method for laminating a tubular film with a liquid or resin absorbing material, comprising: laminating the tubular film over its entire perimeter with a plurality of separate layers of the liquid or resin absorbing material (“absorbing material layers”) in such a manner that (a) no single absorbent material layer completely encircles the perimeter of the tubular film, (b) a first absorbent material layer partially encircles the perimeter of the tubular film, (c) one or more additional absorbent material layers are used to cover the perimeter of the tubular film between lateral sides of the first absorbent material layer; and (d) the absorbent material layers are bonded to the tubular film or to each other by the laminating step; the absorbing material layers overlap along adjacent lateral sides so that there are essentially no areas left along the perimeter of the tubular film that are not covered by the absorbing material layers; and in an initial flat state wherein the tubular film has a first side and a second side defined between opposite lateral edges, the tubular film is laminated on the first side with a first absorbing material layer with an excess length that extends beyond at least one of the folded lateral edges, the tubular film laminated on the second side with a second absorbing material layer.

2. The method according to claim 1, wherein the first absorbing material layer is laminated to the tubular film with an excess length over both of the lateral edges of the tubular film in the initial flat state.

3. The method according to claim 1, wherein each of the first and second absorbing material layers is laminated to the tubular film with an excess length over opposite ones of the lateral edges and are pressed against the lateral edges to create a material bond so that in an expanded circular cross-sectional shape of the tubular film, one of the lateral edges is overlapped by the first absorbing material layer and the other lateral edge is overlapped by the second absorbing material layer.

4. The method according to claim 1, wherein each of the first and second absorbing material layers is laminated to the tubular film with an excess length over each of the lateral edges and are pressed against each other at the lateral edges.

5. The method according to claim 1, wherein the first absorbing material layer is laminated to a first side of the tubular film with an excess length over both lateral edges, the second absorbing material is laminated to the second side and has a length corresponding to that of the second side or narrower, wherein the first absorbing material layer is turned and pressed against the lateral edges.

6. The method according to claim 1, wherein the first absorbing material layer is laminated to a first side of the tubular film with an excess length over both lateral edges and is turned over the lateral edges and pressed against the second side of the tubular film, the second absorbing material layer is laminated to the second side of the tubular film and overlaps the turned over portions of the first absorbing material layer.

7. The method according to claim 1, wherein the tubular film is formed as a hose without a sealing seam, or is formed from a flat film and has one sealing seam.

8. The method according to claim 1, wherein the tubular film has a width from 20 mm to 4000 mm when laid out flat, and a thickness of 20 μm to 4000 μm.

9. The method according to claim 1, wherein the tubular film has a layer facing the absorbing material layers that: a) contains a thermoplastic olefin homo- or copolymer polyethylene more than 50% by weight, or b) contains a polyamide homo- or copolymer more than 50% by weight, or c) contains a thermoplastic elastomer (TPE) more than 50% by weight, and wherein another layer of the tubular film that does not face the absorbing material layers contains a homo- or copolyamide (PA) or a thermoplastic elastomer (TPE) more than 50% by weight.

10. The method according to claim 1, wherein the absorbing material layers are made of a foam or an elastic material containing fibers in the form of: a) Nonwovens, b) felts, c) woven fabrics, d) knit fabrics, e) knitted materials, or f) unidirectional weaves.

11. The method according to claim 1, wherein the absorbing material layers have: a) a basis weight between 5 g/m2 and 1000 g/m2, and b) a thickness of up to 1 cm.

12. The method according to claim 1, wherein the laminations are done through extrusion lamination or glue lamination or heat lamination, wherein for heat lamination, an external layer of the tubular film to be laminated is provided with a thermally activated adhesive during extrusion of the film.

13. A method for laminating a tubular film with a liquid or resin absorbing material, comprising: laminating the tubular film over its entire perimeter with a plurality of separate layers of the liquid or resin absorbing material (“absorbing material layers”) in such a manner that (a) no single absorbent material layer completely encircles the perimeter of the tubular film, (b) a first absorbent material layer partially encircles the perimeter of the tubular film, (c) one or more additional absorbent material layers are used to cover the perimeter of the tubular film between lateral sides of the first absorbent material layer; and (d) the absorbent material layers are bonded to the tubular film or to each other by the laminating step; the absorbing material layers overlap along adjacent lateral sides so that there are essentially no areas left along the perimeter of the tubular film that are not covered by the absorbing material layers; and further comprising: a) in an initial flat state wherein the tubular film has a top side and a bottom side defined between opposite lateral edges, the tubular film is first laminated on each of the top side and bottom side with a first and a second absorbing material layer, respectively; b) the tubular film is brought to a second flat state by turning or rolling the tubular film such that a new top side is formed containing an unfolded one of the lateral edges and a new bottom side is formed containing an unfolded one of the lateral edges, the unfolded lateral edges lying opposite one another; c) in the second flat state, the tubular film is laminated with a third absorbing material layer on the new top side that extends over the unfolded lateral edge and overlaps the first absorbing material layer, and laminated with a fourth absorbing material layer on the new bottom side that extends over the unfolded lateral edge and overlaps the second absorbing material layer; and d) wherein a width of the third and fourth absorbing material layers is less than a width of the first and second absorbing material layers.

14. A method for laminating a tubular film with a liquid or resin absorbing material, comprising: laminating the tubular film over its entire perimeter with a plurality of separate layers of the liquid or resin absorbing material (“absorbing material layers”) in such a manner that (a) no single absorbent material layer completely encircles the perimeter of the tubular film, (b) a first absorbent material layer partially encircles the perimeter of the tubular film, (c) one or more additional absorbent material layers are used to cover the perimeter of the tubular film between lateral sides of the first absorbent material layer; and (d) the absorbent material layers are bonded to the tubular film or to each other by the laminating step; the absorbing material layers overlap along adjacent lateral sides so that there are essentially no areas left along the perimeter of the tubular film that are not covered by the absorbing material layers; and further comprising: a) in an initial flat state wherein the tubular film has a top side and a bottom side defined between opposite lateral edges, the tubular film is first laminated on one of the top side or bottom side with a first absorbing material layer; b) the tubular film is brought to a second flat state by turning or rolling the tubular film by an angle greater than 90° such that a new top side and a new bottom side are defined, one of the new top side or new bottom side having less of the laminated first absorbing material layer than the other respective new bottom side or new top side; c) in the second flat state, the tubular film is laminated on the new top side or new bottom side having less of the laminated first absorbing material layer with a second absorbing material layer that overlaps the first absorbing material layer; d) the tubular film is brought to a third flat state by turning or rolling the tubular film by an angle greater than 90° so that an unlaminated area of the tubular film is laid out flat along another new top side or bottom side; and e) in the third flat state, the unlaminated area is laminated with a third absorbing material layer that overlaps the first and the second absorbing material layers.

15. The method according to claim 1, further comprising combining the laminated tubular film with an outer tubular film of a tube liner for trenchless sewage pipe renovation, wherein the laminated tubular film is an inner tubular film of the tube liner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained with the help of some embodiments. The same reference signs in the various figures stand for the same or equivalent characteristics. The figures show:

(2) FIGS. 1-4 are successive steps of a first embodiment of a method according to the invention for laminating a tubular film shown in cross section;

(3) FIGS. 5-9 are successive steps of a second embodiment;

(4) FIGS. 10-13 are successive steps of a third embodiment, in cross section through the film in flat and expanded state;

(5) FIGS. 14, 15 is a tubular film laminated in a fourth way in flat and in expanded state, in each case in cross section;

(6) FIGS. 16, 17 is a tubular film laminated in a fifth way in flat and in expanded state, in each case in cross section;

(7) FIGS. 18, 19 is a tubular film laminated in a sixth way in flat and in expanded state, in each case in cross section, and

(8) FIGS. 20, 21 is a tubular film laminated in a seventh way in flat and in expanded state, in each case in cross section.

DETAILED DESCRIPTION

(9) Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

(10) FIGS. 1-4 reproduces in a simplified way the successive lamination steps of an embodiment of the method according to the invention for a tubular film 1 shown in cross section. The tubular film 1 extends many meters into the picture plane (as all others described below). In FIG. 1, the non-laminated tubular film 1 is shown in a first, laid out flat, state. In this position, the tubular film 1 has a bottom side 2a and a top side 3a, as well as two edges 4, 5 with small bending radius, which join the bottom and top side 2a, 3a together.

(11) This tubular film 1 is laminated through known extrusion lamination, for example, on the bottom side 2a first with a layer 10 containing a material capable of absorbing resin or a material capable of absorbing liquid (however, “resin-absorbent” will hereinafter always be used to encompass both) or fully consisting of this material, and afterwards—if necessary, after turning the tubular film around depending on the lamination machine used—laminated on the top side 3a with preferably a layer 11 made of the same resin-absorbent material. The order is not important, though. This two-time lamination results in the tubular film 1 shown in FIG. 2, which has a resin-absorbent layer 10 on the bottom side 2a and a resin-absorbent layer 11 on the top side 3a.

(12) The resin-absorbent layers 10, 11 are, for example, elastic nonwovens and, in this case, polyester nonwovens having a polyethylene coating or pure polyethylene nonwovens or polypropylene nonwovens or polyacrylonitrile (PAN)-based materials or also glass nonwovens. Other examples of materials are mentioned above.

(13) According to the double lamination, the tubular film is turned by 90° here—for example, using a known turning hub—, so that it takes the position shown in FIG. 3, named here as second flat state. In this case, the two edges 4, 5 now lie directly opposite one another. In this second (laid out flat) state, the tubular film 1 now has a new bottom side 3b and a new top side 4b.

(14) A lamination machine—preferably the same one—is now used once again for laminating these two sides 3b, 4b one after the other with a resin-absorbent layer 12 and 13. The result is the tubular film 1 laminated with four resin-absorbent layers 10-13, as shown in FIG. 4. The important thing in this embodiment is that the resin-absorbent layers 12, 13 cover the edges 4, 5, whereby the widths of the resin-absorbent layers 12, 13 have been selected here to be narrower than the widths of the resin-absorbent layers 10, 11. As a result of this, the multiple layering with resin-absorbent layers is avoided in many areas that do not need it and a savings of material can be accomplished.

(15) The lamination with successive lamination steps described with the help of FIGS. 1-4 can also be done with merely two lamination steps. In this case, the bottom side 2a and the top side 3a are simultaneously laminated in a lamination machine (FIG. 2) designed accordingly. After subsequent twisting or turning of the two-sided laminated tubular film 1 by 90° (see FIG. 3), done for example with a known turning hub, the two sides 2b and 3b now lying down and up are laminated simultaneously in one single lamination step. The result corresponds to the one shown in FIG. 4. The two lamination steps (first the lamination of the bottom side 2a and top side 3a, then the lamination of the bottom side 2b and top side 3b) can be done in a tandem lamination installation in which, for example, the second lamination machine is arranged downstream from the first. The turning hub is arranged between the two lamination machines. A winding of the film laminated in the first lamination step (and, if need be, already twisted or turned by 90°) and a subsequent unwinding before the second lamination are not necessary in this case; winding is foreseen only at the end of the complete lamination process.

(16) In the lamination according to FIGS. 1-4, the widths or the four layers to be laminated can all be equally wide, or different or partially the same and partially different.

(17) Another lamination option is shown in FIGS. 5-9, where in a first (laid out flat) state of the tubular film 1, one side is laminated—here the top side 12 of the tubular film—with a resin-absorbent layer 20 (FIG. 5). Afterwards, the tubular film is turned by approx. 120° in a second laid-flat state of the tubular film 1 (FIG. 6), so that most of layer 20 is found on the bottom side of the tubular film 1. After that, another resin-absorbent layer 21 (FIG. 7) is laminated on the new top side, and then the tubular film is once again turned by about 120° to a third flat state of the tubular film 1 (FIG. 8). In a last step, a third resin-absorbent layer 22 is laminated, resulting in a tubular film 1 having three resin-absorbent layers 20, 21, 22 (FIG. 9). In this case, the border areas of the three layers 20, 21, 22 overlap.

(18) The angles of approx. 120° given for the second embodiment are not mandatory, but represent a preferable—symmetric—approach in which it is possible to work by turning everything in each case around the same angles and use the sane layer widths in order to obtain equally large overlapping areas of the three lamination layers.

(19) The spaces between the layers and the tubular film shown schematically and of the first or second embodiment do not necessarily mean that they are actually present. Depending on lamination conditions, these spaces can also be closed—partially or fully—by the resin-absorbent layers or by adhesives too.

(20) The described approach ensures that in the case of the second embodiment merely three laminated layers must be laminated in two turning methods, whereas in the first embodiment it is only necessary to turn once, but four lamination layers are needed.

(21) FIGS. 10-13 shows a third embodiment for laminating a tubular film with one layer 30 projecting over both edges 4, 5 that is laminated on the top side 3a of the tubular film. The adhesive or binding polymer used in the extrusion or coating (extrusion coating or extrusion lamination) is also applied in the area of the edges 4, 5, so that the two protruding border areas 35 can be bent downwards by about 90°, pressing against the edges according to FIG. 11. Afterwards, with or without turning the tubular film 1 by 180°, an additional layer 31 is laminated on the other side (bottom side 2a in FIG. 10). The width of layer 31 has been chosen here so it ends essentially flush laterally with edges 4, 5 of the tubular film 1 (see FIG. 12). When the laminated tubular film 1 is expanded, the protruding border areas 35 of layer 30 overlap the ends 36 of layer 31 laminated on the tubular film 1 (FIG. 13). If the intention is to use the tubular film 1 as inner tubular film for trenchless sewage pipe renovation in order to place a resin carrier layer on layers 30, 31, these protruding border areas 35 do not interfere.

(22) A modification of the embodiment shown in FIGS. 10 to 13 provides that the borders 35 of layer 30 are pulled further downwards (i.e. layer 30 is wider than shown in FIGS. 10-13) turned over by almost 180° on the borders 36 of layer 31 and glued to it.

(23) In the third embodiment according to FIGS. 10-13, layer 31 can also be laminated first as an alternative. A further alternative provides the simultaneous lamination of the two layers 30, 31.

(24) FIGS. 14 and 15 show a fourth embodiment. Here, layer 30 laminated on the top side 3a of the tubular film 1, which is wider than the tubular film 1, is turned over on the edges 4, 5 of the tubular film 1 and therefore it also lies against the bottom side 2a of the tubular film 1 with its borders 35. In this case, the borders 35 are also preferably firmly bonded to the bottom side 2a, especially with glue. The other layer 31 is laminated on these borders 35 and against the still uncovered areas of the bottom side 2a of the tubular film. Here, layer 31 has more or less the width of the tubular film 1. However, layer 31 can also be designed in a narrower way, in which case it will then still overlap the borders 35 of layer 30 with its borders 36.

(25) FIG. 15 shows the tubular film 1 with the laminated layers 30, 31 once again in cross section. It can be discerned how the border areas 35 of the layer 30 lie against the tubular film 1, while the border areas 36 of layer 31 lie against the border areas 35 of layer 30.

(26) A fifth embodiment is shown in FIGS. 16 and 17. According to FIG. 16, two layers 30, 31 have also been laminated (one after the other or simultaneously) on the bottom and top side 2a, 3a of a tubular film 1 laid out flat. In the left side shown in FIG. 16, the top layer 30 protrudes downward above the edge 4, while on the right side shown in FIG. 16, layer 31 protrudes upwards over the edge 5. Both border areas 35, 36 protruding in such a way are bonded to edges 4 or 5 as with the embodiment according to FIGS. 10-13. The result is therefore an overlapping of the border areas 35, 36 of the two layers 30, 31, as shown in FIG. 17. It is also possible in the embodiment of FIGS. 16 and 17, with at least somewhat wider layers 30, 31, to turn over by almost 180° one protruding border 35 and the other protruding border 36 and to glue them on layer 31 and layer 30, respectively, while applying pressure.

(27) A sixth variant is shown in FIGS. 18 and 19. Here, the two layers 30, 31 end essentially flush with the two edges 4, 5—once again seen in cross section—or protrude slightly (as shown in FIG. 18). The two border areas 35, 36 of layers 30, 31, not overlapping here, bump into one another in the expanded state of the tubular film 1 (FIG. 19) or there is a very small space between them, i.e. the front sides of both layers 30, 31 are directly opposite one another. Preferably, the film is fully covered with the material capable of absorbing resin or liquids.

(28) A seventh variant is shown in FIGS. 20 and 21. Here, the two layers 30, 31 project over both edges 4, 5 and their projecting border areas 35, 36 are glued to one another or—to express it in a general way—are joined together, preferably by machine. The corresponding adhesives or glues are advantageously used in such a way that the border areas 35, 36 to be joined together are likewise provided with this glue or adhesive. In this variant, the edges 4, 5 are encapsulated or “welded in” when seen in cross section. If the laminated tubular film 1 is expanded and used as inner tube film, for example, the border areas 35, 36 joined together are folded over, as FIG. 21 shows.

(29) A corresponding sequence of the lamination of a tubular film according to FIG. 20 can look like this: First of all, an adhesive layer is applied on the top side of the tubular film laid out flat to be laminated and die absorbent layer 31, for example in form of a nonwoven, is laminated with a two-sided excess length of a few centimeters, preferably up to 10 cm. The one-sided laminated tubular film 1 is then turned on its own longitudinal axis by 180° and a second adhesive layer is applied from above—to be more precise, both on the now uncovered new tubular film top side film and on the protruding (inner) borders of the first lamination layer 31. Now a second lamination sheet 30 can be laminated, likewise with excess length, whereby the projecting border areas of the first and second lamination layer 30, 31 are also glued with one another.

(30) A possible embodiment for an inner tubular film used for essentially complete lamination according to the invention with nonwoven layers, for example, looks like this:

(31) TABLE-US-00001 Layer Proportion Thickness number Composition layer in % in μm 1 Lupolen 2420 F 70 70 Nonwoven Exceed 1327 CA 30 side 2 Admer NF498E 100 10 3 Durethan C38 F 100 40 4 Admer NF498E 100 10 5 Lupolen 2420 F 70 70 inside Exceed 1327 CA 30 Sum: 200 μm

(32) The multilayered film mentioned above contains on the external (“nonwoven”) side to be laminated, which lies opposite the resin-impregnated carrier layer in the tube liner, Lupolen 2420 F, an LDPE made by the LyondellBasell Polymers Co., and Exceed 1327 CA made by the ExxonMobil Chemical Company. The latter is an ethylene copolymer manufactured by means of metallocen catalysis in whose polymerization hexane as additional comonomer is used apart from ethylene.

(33) An adhesive promoter that can be typically used is Admer NF498E, for example, an LDPE modified with maleic anhydride groups made by the Mitsui Co. Admer® substances are PE copolymers with maleic anhydride groups (MA groups) that adhere strongly to PET, EVOH and PA, can be processed very well and are characterized by thermal stability equivalent to conventional PE.

(34) Durethan B40 FAM (Lanxess) is a PA 6 and Durethan C38 F (Lanxess) is a copolyamide of medium viscosity. Basically, commercially available polyamides can be used as polyamides (PA), for example (respective brand names in parentheses) those made by the companies Lanxness (Durethan, see above), BASF (Ultramid), DuPont (Zytel), DSM Engineering Plastics (Akulon, Stanyl), EMS-Chemie (Grilamid, Grivory, Grilon), Evonik (Vestamid, Trogamid), Radici (Radilon, Radiflam, Raditer, Heraform, Heraflex) Rhodia (Technyl,Stabamid), UBE, DSM (Novamid), Atofina (Rilsan).

(35) According to one first example of the lamination according to the invention, during the course of extrusion lamination, the polyethylene (PE) outer or nonwoven side of the tubular film mentioned above (layer number 1) is fully bonded to a 40 g/m.sup.2 nonwoven (layer with resin-absorbent material) having the name Berotex-LLDPE (version 05) made by Fiberweb Berlin GmbH. The coat weight (CW) of the glue for extrusion lamination is 20 g/m.sup.2.

(36) According to a second example, during the course of extrusion lamination, the layer with layer number 1 of the above-mentioned multilayered film is bonded completely to the 30 g/m.sup.2 nonwoven of the Freudenberg Vliesstoffe SE & Co. KG Co. (Lutrabond FD 20030_27). The coat weight (CW) is once again 20 g/m.sup.2.

(37) According to a third example, during the course of extrusion lamination, the layer with layer number 1 of the multilayered film mentioned above is bonded completely to the 50 g/m.sup.2 nonwoven of the company Freudenberg Vliesstoffe SE & Co. KG (Lutrabond FD 20050_27). The coat weight (CW) is once again 20 g/m.sup.2.

(38) It has been found out that elongation until splice or break is not worsened by the above-mentioned lamination examples of the inner tubular film with nonwoven. Quite the contrary, elongation until splice or break even improves when the inner tube film is bonded to the respective nonwoven. The inventors believe that the most likely cause is that the susceptible edges, in particular, are better protected.

(39) The invention is not limited to the embodiments shown in the figures.