PLASTIC FILM WITH AN ELASTIC CORD

Abstract

The invention relates to an apparatus (10) for embedding a continuous elastic cord (11) along an edge of a continuous plastic sheet (12). The apparatus comprises an adhesive applicator device operable to apply an adhesive (16) along the edge of the plastic sheet, a folder device (18, 20, 34) operable to provide a folded edge of the plastic sheet (12) so that the adhesive is within the folded edge, and a feed device (24) having a tension device (30) operable to feed the elastic cord (11) in tension into the folded edge so that the elastic cord (11) is in contact with the adhesive of the edge. A bonding device (38) is operable to activate the adhesive of the folded edge to bond the elastic cord (11) in tension to the adhesive within the folded edge and to bond the folded edge to the plastic sheet (12). The invention also relates to a plastic sheet having an elastic cord at an edge thereof, a method for manufacture of said plastic sheet, and products or covers made from said plastic sheet such as oversleeves, overshoes, hair nets or bin liners etc.

Claims

1. An apparatus for embedding a continuous elastic cord along an edge of a continuous plastic sheet, the apparatus comprising: an adhesive applicator device operable to apply an adhesive along the edge of the plastic sheet; a folder device operable to provide a folded edge of the plastic sheet so that the adhesive is within the folded edge; and a feed device having a tension device operable to feed the elastic cord in tension into the folded edge so that the elastic cord is in contact with the adhesive of the edge, wherein a bonding device is operable to activate the adhesive of the folded edge to bond the elastic cord in tension to the adhesive within the folded edge and to bond the folded edge to the plastic sheet.

2. An apparatus according to claim 1, wherein the apparatus is operable to embed another continuous elastic cord at an opposing edge of the continuous plastic sheet, the apparatus further comprising: another adhesive applicator device operable to apply the adhesive to the opposing edge of the plastic sheet, the folder device operable to provide an opposing folded edge of the plastic sheet so that the adhesive is within the opposing folded edge; and another feed device having a respective tension device operable to feed the other elastic cord in tension into the opposing folded edge so that the other elastic cord is in contact with the adhesive of the opposing edge, wherein another bonding device is operable to activate the adhesive of the opposing folded edge to bond the other elastic cord in tension to the adhesive within the opposing folded edge and to bond the opposing folded edge to the plastic sheet.

3. An apparatus according to claim 1, wherein the one or more adhesive applicator devices comprise a respective spray device operable to spray the adhesive along one or both edges of the plastic sheet, or a pressurized nozzle device to apply a bead or continuous strip of the adhesive along one or both edges of the plastic sheet.

4-5. (canceled)

6. An apparatus according to claim 1, wherein the folder device comprises a first roller, a second roller and a third roller, the plastic sheet being provided in tension between the first and third rollers, the second roller being between the first and third rollers and operable deflect the plastic sheet away from a plane between the first and third rollers such that the second roller is operable to turn one or both edges of the plastic sheet around a respective end of the second roller, and wherein the one or both folded edges of the plastic sheet are provided at the third roller.

7. (canceled)

8. An apparatus according to claim 1, wherein each feed device comprises a respective pulley wheel such that a respective elastic cord passes around a part-circumference of its associated pulley wheel, an edge of the respective pulley wheel being within an associated folded edge to provide said feed of the respective elastic cord into the associated folded edge.

9. (canceled)

10. An apparatus according to claim 8, wherein the edge of the respective pulley wheel is within its associated folded edge at a position between the second and third rollers.

11. (canceled)

12. An apparatus according to claim 1, wherein the adhesive is a hot-melt adhesive.

13. An apparatus according to claim 12, wherein the one or more bonding devices comprise at least one heated roller to heat the adhesive and to provide said activation thereof.

14. An apparatus according to claim 1, wherein the one or more bonding devices have an actuator to apply pressure to one or both folded edges.

15-29. (canceled)

30. A method of embedding a continuous elastic cord along an edge of a continuous plastic sheet, the method comprising: applying an adhesive along the edge of the plastic sheet; folding the edge of the plastic sheet so that the adhesive is within a folded edge; feeding the elastic cord in tension into the folded edge so that the elastic cord is in contact with the adhesive of the edge; and activating the adhesive of the folded edge to bond the elastic cord in tension to the adhesive within the folded edge and to bond the folded edge to the plastic sheet.

31. A method according to claim 30, further comprising: embedding another continuous elastic cord at an opposing edge of the continuous plastic sheet; applying the adhesive to the opposing edge of the plastic sheet; folding an opposing edge of the plastic sheet so that the adhesive is within the opposing folded edge; feeding the other elastic cord in tension into the opposing folded edge so that said other elastic cord is in contact with the adhesive of the opposing edge; and activating the adhesive of the opposing folded edge to bond the other elastic cord in tension to the adhesive within the opposing folded edge and to bond the opposing folded edge to the plastic sheet.

32. A method according to claim 30, and further including spraying the adhesive along one or both edges of the plastic sheet, or applying a bead or continuous strip of the adhesive along one or both edges of the plastic sheet.

33. (canceled)

34. A method according to claim 30, wherein the folding the one or both edges of the plastic sheet comprises providing the plastic sheet in tension between two locations and deflecting the plastic sheet away from a plane between said locations using a roller in order to turn one or both edges of the plastic sheet around a respective end of the roller.

35. A method according to claim 30, wherein said feeding comprises using a respective pulley wheel to introduce a respective elastic cord into an associated folded edge.

36. (canceled)

37. A method according to claim 30, and further including using a hot-melt adhesive.

38. A method according to claim 37, and further including heating the adhesive to provide said activation thereof.

39. A method according to claim 30, and further including applying pressure to one or both folded edges.

40-46. (canceled)

47. A method according to claim 30, and further including manufacturing bag products comprising overshoes, hair nets, bin liners, steering wheel covers, seat covers, vehicle covers, or fire alarm covers, or other protection covers using the one or more plastic sheets.

48. A method according to claim 30, and further including manufacturing tube products comprising oversleeves or other covers using the one or more plastic sheet.

49. A bag or tube product or cover manufactured using the apparatus of claim 1, or using the method of claim 30.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Other features of the invention will be apparent from the following description of preferred embodiments shown by way of example only with reference to the accompanying drawings, in which;

[0073] FIG. 1 shows a schematic side view of an apparatus for embedding an elastic cord at edges of a plastic film according to an embodiment of the invention;

[0074] FIG. 2 shows a perspective view of a part of the apparatus shown in FIG. 1;

[0075] FIG. 3 is a schematic side view of the stages of manufacture of the plastic film with the embedded elastic cord using the apparatus of FIGS. 1 and 2;

[0076] FIG. 4 shows a schematic side view of an apparatus for manufacturing tube or bag plastic film products according to an embodiment of the invention;

[0077] FIG. 5 shows a schematic side view of an apparatus for manufacturing bag plastic film products according to an embodiment of the invention;

[0078] FIG. 6 shows steps of a method according to an embodiment of the invention; and

[0079] FIG. 7 is a schematic side view of the stages of manufacture of the plastic film with the embedded elastic cord using the apparatus of FIGS. 1 and 2 according to another embodiment.

DETAILED DESCRIPTION

[0080] FIG. 1 shows a schematic side view of an apparatus 10 for embedding an elastic cord 11 at edges of a plastic film 12 according to an embodiment of the invention. The plastic film 12 is a thermoplastic film such as polyethylene which is provided on a supply reel 14. The plastic film 12 may be alternatively termed a web or a continuous sheet or film, and has a thickness in the region of 0.2 mm. The plastic film 12 may also be a non-woven thermoplastic fabric, which may be a spun-bonded polypropylene fabric. The elastic cord 11 may be alternatively termed a continuous elastic cord 11, and is substantially circular in section having a diameter of about 0.5 mm in the unstretched condition. In FIG. 1 the plastic film 12 is shown with a solid line, and the elastic cord 11 is shown with a dashed line. It will be understood from the following description that the elastic cord 11 is embedded at both edges or adjacent to the edges of the plastic film, and that the apparatus 10 is for the high-volume manufacturing of the plastic film 12 with the elastic cord 11 embedded at the edges of the film as a continuous process. However, in order to simplify the drawings the elastic cord 11 is described in detail for embedding at one edge only. The skilled person will know the requirements for duplication of the various parts of the apparatus 10 so that the elastic cord 11 is embedded at the other edge of the plastic film 12 at the same time.

[0081] An adhesive is applied to an edge of the plastic film 12, or adjacent to the edge of the plastic film 12, as shown at 16 using an adhesive applicator device (not shown). In one embodiment the adhesive is applied using a wheel (not shown) which is in contact with a bath of adhesive. In another embodiment the adhesive is sprayed onto the plastic film 12. The adhesive may be a hot-melt adhesive such that it cools shortly after being applied to the plastic film 12 at 16. A suitable hot-melt adhesive is available under the trade name BAMCare 511.

[0082] Other ways of applying the adhesive are also envisaged such as a double sided sticky tape, which may comprise a hot-melt adhesive. The adhesive is applied to an outer surface of the edge of the plastic film 12 such that the plastic film 12 can pass round a guide roller 18 without sticking to it. The guide roller 18 may be a driven roller to assist with passage of the plastic film 12 through the apparatus 10. A surface of the guide roller 18 may be rubber to assist with gripping the plastic film 12 to drive it through the apparatus 10.

[0083] A spray nozzle (not shown) with an electronically operated solenoid valve (not shown) may be used to spray the adhesive onto the plastic film 12 as shown at 16. In such an arrangement the spray nozzle is provided in communication with a pressurised reservoir (not shown) of the adhesive, for example a heated bath of hot-melt adhesive. The solenoid valve is then operated so that the adhesive is sprayed onto the edge of the plastic film 12. Using such a spray nozzle and solenoid valve may provide the advantage of an improved accuracy for applying the adhesive. Furthermore, such an arrangement may provide an improved start-up of the apparatus 10 when the plastic sheet 12 is accelerated from 0 m/s to 50 m/s or faster.

[0084] The next stage of the apparatus 10 comprises a feed roller 20 having a rebated end 22, followed by a conical pulley 24. The feed roller 20 and the conical pulley 24 operate to fold the edge of the plastic film 12 back on itself and to embed the elastic cord 11 within the folded edge. The feed roller 20 folds the edge of the plastic film to about 90 degrees as shown at 26, which is produced by the rebated end 22 of the feed roller 20 and due to the plastic film 12 being in tension. The plastic film 12 is then folded to 180 degrees as shown at 28 so that the plastic film 12 is folded back on itself. The conical pulley 24 is between the points 26, 28. The edge of the plastic film 12 is folded back on itself so that the overlap of the edge is about lcm. The overlap is sufficient to allow the cord 11 to be embedded within the edge of the plastic film 12 and may be in the range 0.5 to 1.5 cm. Whereas the edge of the plastic film 12 is described as being folded back on itself it will be understood that in effect the edge of the plastic film 12 is rotated back on itself.

[0085] In FIG. 1 the conical pulley 24 is shown to be provided with a supply of elastic cord 11 from a supply reel 30. The conical pulley 24 is a free running wheel that is not driven, and that rotates about a vertical axis 32. The plastic film 12 with the embedded cord 11 then passes round a drive roller 34, which may have a rubber surface. As such the elastic cord 11 is pulled from the supply reel 30 by the drive roller 34. The supply roller 30 is braked, i.e. slowed, relative to the plastic film 12 such that the elastic cord 11 running therefrom is stretched (i.e. tensioned). In such a manner the elastic cord 11 is embedded in the plastic film 12 in a stretched condition (i.e. a tensioned condition). The supply roller 30 may be slowed relative to the speed of the plastic film 12 using an adjustable brake (not shown), so that the tension of the elastic cord 11 can be adjusted. The supply roller 30 with the adjustable brake may be termed a tension device. Such an arrangement allows the tension of the elastic cord 11 to be adjusted, i.e. set so that it is at a constant tension, and after encapsulation in the edge of the plastic film 12 varying amounts of pleating or crumpling of the plastic film 11 can be achieved according the tension of the elastic cord 11.

[0086] It will also be noted from the drawings that the feed roller 20 is arranged to deflect the plastic film 12 away from a natural straight line or plane between the guide roller 18 and the drive roller 34. Such an arrangement promotes folding of the edge of the plastic film 12 to about 90 degrees as shown at 26 and then to 180 degrees as shown at 28.

[0087] As the plastic film 12 passes around the drive roller 34 it changed direction by 90 degrees, which further assists with urging the edge of the plastic sheet 12 back on itself to 180 degrees as shown at 28. One or more of the guide roller 18, feed roller 20 having the rebated end 22, the conical pulley 24, and the drive roller 34 may be termed a folder device. The guide roller 18, the feed roller 20, and the drive roller 34 may be termed respective first, second and third rollers of the folder device. The conical pulley 24 may be termed a feed device. The drive roller 34 has a groove to guide the elastic cord 11 as the plastic sheet 12 passes around the drive roller 34. In FIG. 1 the plastic sheet 12 then passes around an intermediate drive roller 36. The intermediate drive roller 36 further assists with driving the plastic film 11 through the apparatus 10, and may also provide an isolating effect for different parts of the plastic sheet 12. The drive roller 36 also has a groove (not shown) for the elastic cord 11. The edge of the plastic sheet 12 then passes between two heated rollers 38 which are urged towards each other during operation of the apparatus 10, as shown by arrows 40. Such movement of the heated rollers 38 may be provided by respective actuators such as hydraulic or pneumatic actuators (not shown). The speed of the circumferential surface of the two heated rollers 38 is matched. The two heated rollers 38 urge the plastic film 12 and the elastic cord 11 together, and also activate the adhesive so that the elastic cord 11 is bonded within the folded edge of the plastic film 12 as shown in FIG. 3 or 7. The heated rollers 38 seal the folded edge of the plastic film 12 over the elastic cord 11 to encapsulate it. Such encapsulation is achieved by raising the temperature of the edge of the plastic film 11 and applying pressure with the rollers 38 to form a scarf joint. Together the rollers 38 and the actuators may be termed a bonding device. After the heated rollers 38 the plastic film as shown at 42 cools to set the adhesive, and then the plastic film 42 may then be further processed. It will be understood that the elastic cord 11 is introduced into the folded edge by the conical pulley 24 at a position that allows full encapsulation by the heated rollers 38. With such an arrangement the plastic film 11 as shown at 42 in FIG. 1 has a tensioned elastic cord 11 encapsulated therein.

[0088] Also shown in FIG. 1 is that the edge of the plastic film 12 may pass through a guide channel 39 prior to entering the heated rollers 38. The guide channel 39 comprises two plates which are about the same width as the folded edge and are spaced apart. In one arrangement the guide channel may be a folded plate whereby the free ends thereof are spaced apart. The guide channel 39 may assist with maintaining the edge of the plastic sheet 12 and the cord 11 together prior to entering the heated rollers 38.

[0089] Each of the rollers 34, 36, 38 has a groove on the surface thereof which corresponds to the required position of the elastic cord 11 in the finished plastic film 12. The grooves assist with setting up of the apparatus 10, and also keep the plastic film 12 and the elastic cord 11 in the required position as they pass through the apparatus 10.

[0090] In the above description the elastic cord 11 is described as being embedded at one edge of the plastic film 12. However, in some embodiments the elastic cord 11 is also embedded at both edges of the plastic film 12 so that it can be manufactured into items such as oversleeves or bin liners as discussed below. It will be appreciated that embedding the elastic cord 11 at both edges of the plastic film 12 requires duplication of certain parts of the apparatus 10 such as the conical pulley 24, the supply reel 30, and the heated rollers 38 to embed the elastic cord 11 in the second edge of the plastic film 12. Furthermore the rebated end 22 of the roller 20 is also required to be present at the other end thereof. However, such duplicated parts of the apparatus 10 have been omitted from FIG. 1 for the purposes of clarity.

[0091] FIG. 2 shows a perspective view of a part of the apparatus shown in FIG. 1. In FIG. 2 like features to the arrangements of FIG. 1 are shown with like reference numerals. In FIG. 2 the rebated end 22 of the feed roller 20 is shown which has a smaller diameter than the main body of the feed roller 20. Also show is the conical pulley 24 which fits into the folded edge of the plastic film 12 at 25. In FIG. 2 the plastic film 12 is partially transparent and the conical pulley 24 is visible through the folded edge of the plastic film 12. The drive rollers 34, 36 are also visible through the partially transparent plastic film 12. The elastic cord 11 is shown to pass around the conical pulley 24 so that it is embedded in the folded edge of the plastic sheet 12 as it travels in the direction shown by arrow 27. Also shown in FIG. 2 is a guide pulley 44 for the elastic cord 11, and a support 46 for the conical pulley 24 and the guide pulley 44. The guide pulley 44 and the support 46 are not shown in the schematic drawing of FIG. 1 for the purposes of clarity. As shown in FIG. 2, just prior to the 180 degree folding shown at 28 the elastic cord 11 is introduced. The elastic cord 11 is inserted between the folded edge and the plastic film 12 at a position that allows full encapsulation thereof.

[0092] FIG. 3 is a schematic side view of the stages of manufacture of the plastic film 12 with the embedded elastic cord 11 using the apparatus 10 of FIGS. 1 and 2. In FIG. 3 like features to the arrangements of FIGS. 1 and 2 are shown with like reference numerals. In FIG. 3 about 4 cm of one edge part of the plastic film 12 is shown in each of the drawings 3a to 3e. It will be understood that the other edge of the plastic film 12 also has an elastic cord embedded therein, but this has been omitted for the purposes of clarity. FIG. 3a shows the adhesive application stage 16 of FIG. 1 whereby the adhesive is applied to the edge of the plastic film 12 as shown at 50. The adhesive 50 is applied in a continuous line along the edge of the plastic film 12 with a width in the region 0.5 cm to 2.0 cm. FIG. 3b shows the plastic film 12 after the hot-melt adhesive has dried (i.e. cooled) and at the point 26 shown in FIGS. 1 and 2 whereby the edge of the plastic film has been folded to about 90 degrees. FIG. 3c shows the plastic film 12 after the elastic cord 11 has been introduced into the folded edge at approximately a mid-point between the conical pulley 24 and the point 28. FIG. 3d shows the plastic film 12 after the point 28 where the edge thereof has been folded to 180 degrees. FIG. 3e shows the plastic film 12 at the heated rollers 38 whereby the hot-melt adhesive is activated and the folded edge is compressed so that the elastic cord 11 is bonded within the folded edge. The folded edge holds the elastic cord 11 in position due to the adhesive which grips and bonds the elastic cord 11 along a length thereof to the plastic film 12. It will be understood that the adhesive is applied to one or both edges of the continuous plastic film 12 so that there is a continuous bed of adhesive along one or both edges of the plastic film 12. The elastic cord 11 is then laid into one or both edges of the plastic film prior to activation of the adhesive with heat and pressure.

[0093] FIG. 4 shows a schematic side view of an apparatus 60 for manufacturing tube or bag plastic film products according to an embodiment of the invention. In FIG. 4 like features to the arrangements of FIGS. 1 and 2 are shown with like reference numerals. In FIG. 4 the apparatus 60 is shown to comprise a first apparatus 10, which is the same as the apparatus of FIGS. 1 and 2, and a second apparatus 61, which comprises the same components as the apparatus 10 in a mirror arrangement. Each of the apparatus 10, 61 is operable to produce a respective plastic film 42 having the elastic cord 11 embedded at one or both edges thereof. Respective drive rollers 62, 64 receive the plastic film 42 from each of the apparatus 10, 61. The two plastic films 42 change direction by 90 degrees at the drive rollers 62, 64 so that the plastic films 42 are parallel to each other with the respective elastic cords 11 of one plastic film 42 adjacent to the elastic cords of the other plastic film 12. The two plastic films 42 then pass through a welding device comprising two weld rollers 66 which have a heated blade (not shown) to periodically weld the two plastic films 42 together across a width thereof. The periodic welds are about 19 cm apart, and each weld is about lcm in width. The distance between welds may be adjusted as required, for example, so that it is between 4 cm to 30 cm. After the welding device 66 the plastic films 42 then pass through a cutting device comprising two rollers 68 which have a perforation blade (not shown) to periodically perforate (i.e. partially cut) the two plastic films 42 across the welded joint thereof, and to cut the two elastic cords 11 at each edge thereof. It will be appreciated that the plastic sheets 42 have elastic cords 11 at both edges thereof such welding, perforation and cutting produces a plastic sheet at 69 that can be readily torn along each perforation to provide a tubular product, such as an oversleeve, which has an elastic cord 11 embedded around each opening thereof. The plastic sheet at 69 may then be wound onto a storage reel 70. The rollers 66, 68 are driven rollers.

[0094] In one embodiment each apparatus 10, 61 is operable to product the plastic film 42 with the elastic cord 11 embedded at one edge only. With such an arrangement the welding HI device 66 is operable to periodically weld the two plastic films across a width thereof, and to continuously weld the adjacent edge of the plastic films 42 without the elastic cords 11. The cutting device 68 then periodically perforates (i.e. partially cuts) the two plastic films 42 across the welded joint thereof, and cuts the two elastic cords 11 at the one edge thereof. With such an arrangement the apparatus 60 can be used to manufacture bag plastic products using two plastic films 42 which only have the elastic cord 11 embedded at one edge thereof. The bag plastic products produced using such an apparatus have an elastic cord 11 embedded around an opening thereof, and the sides and bottom of the bag comprise are welded.

[0095] FIG. 5 shows a schematic side view of an apparatus 80 for manufacturing bag plastic film products according to an embodiment of the invention. In FIG. 5 like features to the arrangements of FIGS. 1, 2 and 4 are shown with like reference numerals. In FIG. 5 the apparatus 80 is shown to comprise the apparatus 10, which is the same as the apparatus of FIGS. 1 and 2. After the drive roller 62 the apparatus 80 has a folder device comprising a roller 63 and a folder wheel 82. The roller 63 runs along the complete width of the plastic film 12. The folder wheel 82 runs along the centre of the plastic film 12 between the elastic cords 11 and operates to push a centre of the plastic sheet 42 downward as shown at 83. The folder device also comprises a guide roller 84. The folder device 63, 82, 84 operates to fold the plastic film 12 and to turn the plastic film 42 through 90 degrees such that the plastic film 42 runs into the plane of drawing at 81 and is parallel with the plane of the drawings at 85.

[0096] As shown in FIG. 5 the guide roller 84 rotates around an axis 86 that is parallel with in the plane of the drawing such that after the guide roller 84 the folded plastic film 42 shown at 87 has two elastic cords 11 along one edge thereof. The folded plastic film 42 then passes through a welding device comprising two weld rollers 88 (only one of which is shown) which have a heated blade (not shown) to periodically weld the folded plastic film 42 together across a width thereof as shown at 90. The periodic welds 90 are about 19 cm apart, and each weld is about lcm in width. The distance between welds 90 may be adjusted as required, for example, so that it is between 4 cm to 30 cm. After the welding device 88 the folded plastic film 42 then pass through a cutting device comprising two rollers 90 (only one of which is shown) which have a perforation blade (not shown) to periodically perforate the folded plastic film 42 across the weld 90 as shown at 94. The cutting device 92 also cuts the two elastic cords 11 at the one edge of the folded plastic film 42. It will be appreciated that such welding, perforation and cutting produces a plastic sheet at 96 that can be readily torn along each perforation 94 to provide a bag product, such as an overshoe or a bin liner, which has an elastic cord 11 embedded around the opening thereof. The plastic sheet at 96 may then be wound onto a storage reel (not shown). The rollers 84, 88, 92 are driven rollers.

[0097] In FIG. 5 it will be appreciated that the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63 and the wheel 82 rotate about axes that are perpendicular to the plane of the drawing, whereas rollers 84, 88, 92 rotate around axes that are parallel with the plane of the drawing.

[0098] In the above embodiments the various rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92, the wheel 82, and the guide channel 39 operate to steer and centre the plastic film 12, 42 through the apparatus 10, 60, 80. Additional rollers or guides such as intermediate drive rollers or intermediate idler rollers may also be used to guide the plastic film 12 through the apparatus 10, 60, 80 but these have been omitted for the purposes of clarity. In the above description the various rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92 may alternatively be termed cylinders.

[0099] The above embodiments describe an apparatus 10, 61 for producing a plastic film 42 having an elastic cord 11 at each edge thereof. It will be appreciated that the elastic cord 11 is embedded at or adjacent to the edges of the plastic film 42. The above embodiments also describe apparatus 60 for making tube plastic film products that are open at both ends of the tube, such as oversleeves. Furthermore, the above embodiments also describe apparatus 80 for making bag plastic film products having a closed end, such as bin liners, hair nets, overshoes etc. It will be understood from the foregoing that the tube plastic film products have an elastic cord 11 embedded around each end thereof, and in the case of the tube plastic film product being an oversleeve each end thereof can be secured around the wrist and the elbow of the user. It will also be understood from the foregoing that the bag plastic film products have an elastic cord 11 embedded around the opening thereof, and in the case of the bag plastic film product being an overshoe or bin liner the end thereof can be secured around the ankle of the user, or around an opening of a dust bin.

[0100] It will be understood that during operation of the apparatus 10, 60, 80 the plastic film 12, 42 is at a constant speed in the apparatus 10. One or more sensing devices (not shown) may be used to monitor the speed of plastic film 12, 42 as it passes through the apparatus 10, 42. In one arrangement the sensing device comprises one or more of the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92 and the wheel 82 have a speed sensor to determine the speed of rotation as indicated by one or more of the arrows thereon in the FIGS. 1, 2, 4, 5. Alternatively the sensing devices may be cameras (not shown). The sensing devices are coupled to a control device (not shown) which has a processor to communicate with the drive rollers 18, 34, 36, 38, 62, 63, 64, 66, 68, 84, 88, 92 to adjust the speed of the plastic sheet 12, 42 through the apparatus 10, 60, 80 and the amount of glue applied at 16, and the actuators operating the heated rollers 38 as required. The sensing devices provide a feedback mechanism to maintain the operation of the apparatus 10, 60, 80.

[0101] In the above embodiments one or more of the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92, or the wheel 82 may be a driven roller or wheel, or may be an idler roller or wheel to assist with passage of the plastic sheet 12, 42 through the apparatus 10, 60, 80 and to provide the required feeding of the plastic film 12, 42 through the apparatus 10, 60, 80. The driven rollers are powered by one or more electric motors (not shown). One or more of the driven rollers may have rubber surfaces to assist with gripping of the plastic film 12, 42.

[0102] The heated rollers 38 and the welding device of the apparatus 10, 60, 80 are heated so that a surface thereof has a temperature in the region of 80 to 110 degrees. Heating of the rollers 38 and the welding device may be achieved using hot oil passing through them, or using electrical heating elements according to known arrangements. The heated rollers 38 and the welding device may have a surface with a high heat conductivity, such as a copper surface, to assist with welding of the plastic film 12, 42.

[0103] FIG. 6 shows a diagram of a method according to an embodiment of the invention, generally designated 100. It will be appreciated that the steps may be performed in a different order, and may not necessarily be performed in the order shown in FIG. 6. The method 100 is a method of embedding a continuous elastic cord 11 along an edge of a continuous plastic film 12.

[0104] The method includes applying an adhesive along the edge of the plastic film 12, as shown at 102. The method includes folding the edge of the plastic film 12 so that the adhesive is within a folded edge, as shown at 104. The method includes feeding the elastic cord 11 in tension into the folded edge so that the elastic cord 11 is in contact with the adhesive of the edge, as shown at 106. The method includes activating the adhesive of the folded edge to bond the elastic cord 11 in tension to the adhesive within the folded edge and to bond the folded edge to the plastic film 12, as shown at 108.

[0105] The method includes embedding another continuous elastic cord 11 at an opposing edge of the continuous plastic film 12. The method includes applying the adhesive to the opposing edge of the plastic film 12, as shown at 102. The method includes folding an opposing edge of the plastic film 12 so that the adhesive is within the opposing folded edge, as shown at 104. The method includes feeding the other elastic cord 11 in tension into the opposing folded edge so that said other elastic cord 11 is in contact with the adhesive of the opposing edge, as shown at 106. The method includes activating the adhesive of the opposing folded edge to bond the other elastic cord 11 in tension to the adhesive within the opposing folded edge and to bond the opposing folded edge to the plastic film 12, as shown at 108.

[0106] The method includes spraying the adhesive along one or both edges of the plastic film 12, as shown at 110. The method further includes applying the adhesive along one or both edges of the plastic film 12 with a width in the range 0.5 to 2.0 cm. Said folding the one or both edges of the plastic film 12 comprises providing the plastic film 12 in tension between two locations 18, 34 and deflecting the plastic film 12 away from a plane between said locations 18, 34 using a roller 20 in order to turn one or both edges of the plastic film 12 around a respective end of the roller 20, as shown at 112.

[0107] Said feeding comprises using a respective pulley wheel 24 to introduce a respective elastic cord 11 into an associated folded edge. Said feeding comprises setting the tension of the one or more elastic cords, as shown at 114.

[0108] The method includes using a hot-melt adhesive. The method further includes heating the adhesive to provide said activation thereof, as shown at 108. The method further includes applying pressure to one or both folded edges, as shown at 108. The method further includes using a thermoplastic for the plastic film 12. The method further includes using a single strand for each elastic cord 11.

[0109] In one arrangement the method further includes folding the plastic film 12 so that the elastic cords 11 of respective edges are adjacent to one another. In another arrangement the method further includes providing two continuous plastic films 12, each film having at least one elastic cord 11 at a respective edge thereof, the method including position the two plastic films 12 so that they are face to face with one another and so that respective elastic cords 11 of each film 12 are adjacent to one another.

[0110] The method further includes periodically welding the one or more plastic films 12 together across a width thereof, said welds being spaced apart along a length of the one or more plastic films 12. The method further includes continuously welding the two plastic films 12 along a length thereof in order to weld the respective edges of the two plastic films together.

[0111] The method further includes cutting the elastic cords 11 at each weld of the one or more plastic films 12, and perforating the one or more plastic films 12 along each weld across the width thereof. In one arrangement the method further includes manufacturing bag products comprising overshoes, hair nets or bin liners. In another arrangement the method further includes further including manufacturing tube products comprising oversleeves.

[0112] FIG. 7 is a schematic side view of the stages of manufacture of the plastic film with the embedded elastic cord using the apparatus of FIGS. 1 and 2 according to another embodiment. In FIG. 7 like features to the arrangements of FIGS. 1, 2 and 3 are shown with like reference numerals. In FIG. 7 about 4 cm of one edge part of the plastic film 12 is shown in each of the drawings 7a to 7e. It will be understood that the other edge of the plastic film 12 also has an elastic cord embedded therein, but this has been omitted for the purposes of clarity. FIG. 7a shows the adhesive application stage 16 of FIG. 1 whereby a bead of the adhesive is applied to the edge of the plastic film 12 as shown at 50. The bead of adhesive 50 is applied in a continuous line along the edge of the plastic film 12 with a diameter in the region 0.4 mm to 1 mm. FIG. 7b shows the plastic film 12 after the hot-melt adhesive has dried (i.e. cooled) and at the point 26 shown in FIGS. 1 and 2 whereby the edge of the plastic film has been folded to about 90 degrees. FIG. 7c shows the plastic film 12 after the elastic cord 11 has been introduced into the folded edge at approximately a mid-point between the conical pulley 24 and the point 28. FIG. 7d shows the plastic film 12 after the point 28 where the edge thereof has been folded to 180 degrees. FIG. 7e shows the plastic film 12 at the heated rollers 38 whereby the hot-melt adhesive is activated and the folded edge is compressed so that the elastic cord 11 is bonded within the folded edge. The folded edge holds the elastic cord 11 in position due to the adhesive which grips and bonds the elastic cord 11 along a length thereof to the plastic film 12. It will be understood that the adhesive is applied to one or both edges of the continuous plastic film 12 so that there is a continuous bed of adhesive along one or both edges of the plastic film 12. The elastic cord 11 is then laid into one or both edges of the plastic film prior to activation of the adhesive with heat and pressure.

[0113] A pressured nozzle may be used to apply the bead of adhesive. The pressured nozzle lays the bead of adhesive onto the plastic film 12 as shown at 16 so that the bead is stuck to the plastic film 12. In such an arrangement the pressurised nozzle is provided in communication with a pressurised reservoir (not shown) of the adhesive, for example a heated bath of hot-melt adhesive. The reservoir is provided under pressure by a suitable pump. A solenoid valve is used to open the pressurised nozzle to apply the bead of adhesive onto the edge of the plastic film 12. Using such a pressurised nozzle and solenoid valve may provide the advantage of an improved accuracy for applying the adhesive. Furthermore, such an arrangement may provide an improved start-up of the apparatus 10 when the plastic sheet 12 is accelerated from 0 m/s to 50 m/s or faster. In an alternative arrangement a swirl or strip of the adhesive may be applied to the edge of the plastic film 12. The adhesive applied may be continuous strip or continuous line of the adhesive.

[0114] In the above embodiments one or more of the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92, or the wheel 82 are a drum or cylinder. It is also envisaged that one or more of the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92, or the wheel 82 could be a belt, i.e. a continuous belt, having a flexible surface. With such an arrangement the belt may not be circular in shape, and may pass over a plurality of belt rollers, such as three of four belt rollers, during operation of the apparatus 10, 60, 80. Furthermore it is also envisaged that one or more of the rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92 could be a wheel or any circular device operable to allow the plastic film 12 to run over it.

[0115] In the above description the elastic cord 11 may be any suitable elastic cord 11 such as an elastic wire or elastic line, which may be a single strand or a multiple strands twisted together. The elastic cord 11 may be rubber or any suitable synthetic cord that is resilient. In a preferred embodiment the elastic cord 11 is a single thread elastomer which is available under the trade name DTEX.

[0116] The apparatus 10, 60, 80 described herein provides the advantage of a continuous process for manufacturing the plastic film 12, 42 having the encapsulated cord 11, which improves the speed of manufacture and the cost of manufacture thereof. The apparatus 10, 60, 80 may be used to manufacture any plastic film 12, 42 requiring an elastic cord 11 therein, such as plastic overshoes, oversleeves, hair nets, disposable bin liners, steering wheel covers, seat covers, vehicle covers, fire alarm covers, etc or any other cover used to protect items such as machinery or equipment that may be large or small.

[0117] The apparatus 10, 60, 80 described herein has an electronic controller device (not shown) to control the operation of the various parts of the apparatus 10, 60, 80. Such a controller device may be operable to control the speed of the various rollers 14, 18, 20, 30, 34, 36, 38, 62, 63, 66, 68, 70, 84, 88, 92, or the wheel 82, the operation of the adhesive application stage 16, the operation of the tension device, the operation of the heated rollers 38, the operation of the welding device 66, 88, the operation of the perforation device 68, 92, and the operation of the storage reel 70. The skilled person will understand the requirements of such a controller device and it will not be described further.