This invention relates generally to decoration of cylindrical articles made from synthetic fabric-coated, neoprene rubber sheet. Specifically, it relates to the decoration of such articles through dye sublimation means.

The insulating, cylindrical cover for beverage bottles or cans takes a number of similar forms and is referred to variously as a cozy, stubby holder, stubby cooler, koozie, beer can cooler and so on. It is commonly moulded in a single piece from expanded polystyrene foam or fabricated from fabric-coated neoprene rubber sheet. Throughout the following, the term, 'beer can cooler', will be used to signify an insulating, cylindrical cover for beverage bottles or cans or similar article made from fabric-coated neoprene rubber sheet material.

The technology of printing images onto cylindrical surfaces is well known in the art. Where such images extend substantially around the circumferential area of an article, screen printing has commonly been employed. As screen printing limits both the colour complexity and resolution of the created image, dye sublimation printing is now widely employed. In dye sublimation printing, simply stated, an image is printed onto a dye receptive transfer medium, hi small to medium-scale operations, printing is via the inkjet process and the image transfer medium is normally a type of coated paper. The printed image transfer medium is pressed with the image against the surface to receive it and heated, the solid dye vaporising and instantaneously sublimating onto the receiving surface. Dye sublimation printing is normally only possible with certain synthetic materials which absorb the vaporised dye and cannot be used with natural materials unless they have been suitably treated. Dye sublimation printing enables the transferring of complex, brightly coloured and finely-detailed images and is used in a very wide range of applications.

A common application of dye sublimation printing is the decoration of cylindrical surfaces of souvenir mugs made from a polymer material, the image transfer process occurring in a mug press. The mug press comprises a flexible metal sleeve enclosing a flexible, electrical heating element. The metal sleeve takes the form of an incomplete cylinder with a narrow, axially-arranged slot remaining open to accommodate the mug handle. One edge of the slot is fixed to a support and the other is able to be deflected inwardly towards the first by a suitable mechanism, urging the heating element against a mug positioned within it. Image transfer is effected by wrapping the image transfer medium carrying the desired image around the mug with the image in contact with the mug surface, placing the mug in the mug press and tightening or clamping the metal sleeve for an appropriate period. The metal sleeve is then released, the mug removed and the image transfer medium discarded. The image transferred to the mug is immediately permanent, fixed and unsmudgeable.

When dye sublimation printing began to be used in the decoration of beer can coolers, because of the similarly cylindrical shape, it is natural that the apparatus employed would be adapted from the commonly used mug press. During the image transfer process, the adapted apparatus applies positive pressure to the image transfer medium, thereby compressing the neoprene rubber of the beer can cooler. While very large volumes of fabric-coated, neoprene rubber beer can coolers are now printed using the adapted apparatus, it is commonly acknowledged that the image quality achieved is inferior to that achieved with mugs. The inferior image quality is normally ascribed to the fact that the neoprene rubber material is not rigid and that the inherent flexibility somehow adversely affects image quality. Attempts have been made to mitigate the problem by printing beer can coolers in-the-flat prior to assembly by sewing, or by making beer can coolers which are simply wrapped around a can or bottle and retained by Velcro pads or other means.

The object of the present invention is to provide an apparatus using dye sublimation technology for printing on cylindrical beer can coolers made from a fabric- coated, neoprene rubber material, the apparatus providing an image quality more or less equal to that achieved with rigid image-receiving substrates.

According to the present invention, an image is transferred to a cylindrical beer can cooler made from a fabric-coated, neoprene rubber material using dye sublimation technology. The fabric coating of the neoprene rubber material from which the beer can cooler is made is normally white or approximately white. The desired image is preprinted on a sheet of image transfer medium. The beer can cooler is slid over a cylindrical mandrel, the external diameter of the mandrel being selected to provide a light interference fit, and the sheet of image transfer medium wrapped around the beer can cooler with the image in contact with the coating fabric. The sheet of image transfer medium is normally secured in place on the beer can cooler during the image transfer process using some form of light adhesive tape. The wrapped beer can cooler is placed between the two halves of a metal platen pre-heated to a suitable temperature, the halves being brought together to form a cylindrical cavity. The internal diameter of the cylindrical cavity is selected to provide a light sliding fit between the external surface of the image transfer medium and the internal surface of the cavity. The neoprene rubber material from which the beer can cooler is made is highly vesicular and heat from the platen causes gas within the vesicles to expand rapidly, thereby expanding the neoprene rubber into light but firm contact with the internal surface of the cavity. The image transfer medium sandwiched between the two is heated and dye vaporisation and sublimation takes place in the manner described. The platen halves are then parted, the image transfer medium is removed and discarded and the beer can cooler removed from the mandrel. It will readily be appreciated that expansion of an image will cause a decrement in image quality. Conversely, contraction or condensation of an image, as occurs upon cooling of a beer can cooler following completion of the image transfer process, will cause a concomitant sharpening of image quality.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which:

Figure 1 is a side view of a simple image transfer unit;

Figure 2 is a transverse cross-sectional view on A-A of the platen of the image transfer unit depicted at Figure 1 ;

Figure 3 is a longitudinal cross-sectional view of a typical platen of an image transfer unit made in accordance with the present invention;

Figure 4 is a partial side view of a mechanism to wrap sheet image transfer medium around workpieces;

Figure 5 is a plan view of a mechanical schematic diagram of a system to automatically perform all functions of the image transfer process;

Figure 6 is a longitudinal cross-sectional view of a mandrel of the present invention showing cooling provisions.

It should be noted that the figures are drawn to different scales and no meaning should be drawn from this. With reference to Figure 1, an image transfer unit utilising dye sublimation technology is provided for the transferring of images onto the curved surfaces of cylindrical substrates, the images extending through a circumferential distance of up to 360°. Said image transfer unit comprised base 1, tower 2, cantilevered support 3, actuator 4 and platen upper part 5 and lower part 6. With additional reference to Figure 2, said platen upper part is connected to said actuator by actuator rod 7, operation of said actuator displacing said actuator rod in an axial sense to lift said platen upper part from abutment with said platen lower part or to restore said platen upper part to a position of abutment with said platen lower part. Cheek plates 14 fixed to said platen lower part make a sliding fit with the flat side surfaces of said platen upper part and serve to maintain both said platen parts in alignment when they are separated by the action of said actuator. Dowels 10 in bores 9 serve to maintain both said platen parts in accurate alignment when their adjacent edges are in abutment. In the preferred embodiment, said dowels are pressed in an interference fit into said bores in one said platen part and make an accurate, sliding fit with said bores in the other said platen part. Also in the preferred embodiment, the leading ends of said dowels are suitably rounded or chamfered to facilitate their entry into said bores. Said platen upper and lower parts have semi- cylindrical cavities 8 formed within them such that, when faces 40, 41 of said platen upper and lower parts are positioned in abutment, a smooth, right-cylindrical cavity 21 is formed between the two. Importantly, said abutting faces of said platen upper and lower parts must be fully complementary and their edges accurately formed and preserved.

Actuator rod 7 is provided with threaded spigot 12 which is screwed and tightened into threaded bore 13 in the upper surface of said platen upper part. Said platen lower part is fixed to base 1. A plurality of more or less equally-spaced heating elements 11 are installed in bores in said platen upper and lower parts and connected to electrical power supply and control means via cables 16, 17. Cable 16 connected to said platen upper part is provided with coiled or convoluted part 20 to permit movement of said platen upper part without stressing of said cable. Both said cables are connected via quick-disconnection means 18, 19 to permit quick replacement of said platen upper and lower parts. Said electrical power supply and control means are accommodated variously within said base, tower or cantilevered support. Visual indication means 15 are fixed to the upper surface of said cantilevered support. In the preferred embodiment, said electrical power and control means are based upon a microprocessor-based control unit which provides any of the functions of timing, platen thermostatic temperature control, platen heating control, platen opening and closing, workpiece displacement and visual and/or aural warning generation.

With reference to Figure 3, beer can cooler 29 of fabric-coated neoprene rubber is supported on cylindrical mandrel 22. The external diameter of said mandrel is selected to ensure that a light interference fit is created between said mandrel and said beer can cooler. One end of said mandrel is closed by flange 26 which is provided with handle or manipulating bar 27. A sheet of image transfer medium 28 carrying an image printed in a sublimatable dye is wrapped around beer can cooler 29, the orientation of said image transfer medium being such that its pre-printed image abuts the exterior surface of said beer can cooler, hi the preferred embodiment, said image transfer medium is secured in place on said beer can cooler during said image transfer process using some form of light adhesive tape (not shown), said adhesive tape being stretchable and permitting unrestricted expansion of said image transfer medium via relative movement of its overlapping ends as said neoprene rubber material of said beer can cooler expands. Said fabric coating of said neoprene rubber material of said beer can cooler is preferably white or other light colour. Said image transfer medium is a thin, flexible sheet of one of the materials commonly employed for the purpose and which are well known in the art. The internal diameter of cylindrical cavity 21 is selected to provide a light sliding fit between the external diameter of said wrapped image transfer medium and the internal surface of said cavity.

To effect a transfer of said image carried by said image transfer medium to said fabric coating of said beer can cooler, said platen upper and lower parts 5, 6 are separated by the action of said actuator applied via actuator rod 7 to lift said platen upper part; said mandrel bearing said beer can cooler wrapped in said sheet of image transfer medium is inserted fully between said separated platen upper and lower parts which are pre-heated to a temperature in the range 185° C to 200° C; said platen upper and lower parts are then closed. The neoprene rubber material from which said beer can cooler is made is highly vesicular and heat from said platen causes gas within said vesicles to expand rapidly, thereby expanding said neoprene rubber into light but firm contact with the internal surface of said cavity. Said image transfer medium sandwiched between said fabric coating of said neoprene rubber and said cavity internal surface is heated and dye vaporisation and sublimation onto said fabric coating takes place in the manner described. It should be noted that said image transfer takes place with only a minimum compression of said neoprene rubber material. Where other forms of ink are dye are used in said image transfer unit, said platen upper and lower parts are optionally heated in the temperature range 150° C to 250° C.

In the preferred embodiment, flange 26 is provided with circumferential shoulder 25 which enters complementary circumferential recess 23 in the end of said platen upper and lower parts in their abutting positions. When beer can cooler 29 is in position on said mandrel, the open end of said beer can cooler abuts the inner face 32 of said circumferential shoulder, ensuring that said beer can cooler is fully entered into said cylindrical cavity of said platen upper and lower parts in their abutting positions. The lower panel 30 of said beer can cooler remains unheated during said image transfer process. In an alternative embodiment (not shown), said actuator is deleted and said platen upper part is raised and lowered manually by means of a simple, lever-operated mechanism. In another alternative embodiment (not shown), base 1, tower 2 and cantilevered support 3 are made wider and the lower parts of a plurality of said platens are fixed in parallel arrangement to said base. The upper parts of said platens are fixed to a common bar which is raised and lowered by one or more said actuators via said actuator rods, operation of said actuators displacing said actuator rods in an axial sense to lift said bar and, thereby, said platen upper parts from abutment with said complementary platen lower parts or to lower said bar and restore said platen upper parts to a position of abutment with said complementary platen lower parts. In another alternative embodiment (not shown), said actuators are deleted and said bar is raised or lowered manually by means of a simple, lever-operated mechanism.

Where cooling of mandrel 22 is required between image transfer cycles, handle or manipulating bar 27 is provided with internal duct 33 through which a flow of cooling air is passed at the appropriate time. The edges of the open end of distributor cap 34 are pressed unto narrow circumferential groove 24 formed in the inner surface of flange 26. A plurality of suitable orifices (not shown) are provided in said distributor cap, said orifices discharging generally tangential jets of air over the internal surface of said mandrel. The internal surface of said mandrel is optionally ribbed or grooved to provide additional heat transfer surface area. With additional reference to Figure 6, where cooling of mandrel 22 is required between image transfer cycles, in an alternative embodiment, handle or manipulating bar 27 is provided with internal duct 33 through which a flow of cooling water is passed at the appropriate time. Accommodated within the interior of said mandrel is cylindrical body 35 made from a suitable thin, thermally conductive material. The diameter of said cylindrical body is made such as to provide a clearance in the range 1.5 to 10 millimetres between the external surface of said body and the internal surface of said mandrel. Return flow duct 36 is made coaxial with said cylindrical body, extending throughout its length and passing coaxially out through duct 33. Radially arranged flow vanes 37, 39 are fixed to the end surfaces of said cylindrical body, the ends of said vanes optionally being extended radially to abut the internal surface of said mandrel for the purpose of positively locating said cylindrical body. Flow vanes 39 are fixed also to the inner surface of closure 38 which is sealingly pressed into the end of the interior of said mandrel. A suitable opening 44 is provided at the end of return flow duct 36 adjacent closure 38. Water entering via duct 33 is deflected outwardly by flow vanes 37, passes through annular space 45, is deflected inwardly by flow vanes 39 and thence flows out through return flow duct 36.

With reference to Figures 4 and 5, turret 45 controllably rotating on vertical axis (indicated as 68) is provided with one or more radially arranged rams 49 upon the outer ends of which are fixed mandrels 22 made in accordance with the present invention. Said rams are able to be extended radially for an accurately determined distance and can be controllably rotated, hi the preferred embodiment, said turret is provided with four said rams separated at 90°. Situated around said turret and separated at 90° are loading station 69, wrapping station 70, image transfer station 71 and unloading station 72. Said turret is rotated upon axis 68 into fixed positions coincident with the axes of said stations by a stepper motor or other actuator with accurate indexing provisions.

At Station 69, angularly descending chute 46 is provided with a continuous supply of said blank beer can coolers from a hopper (not shown). Said chute conducts a continuous supply of said blank beer can coolers to opening 47 at its lower end. Said beer can coolers are orientated such that their open ends appear successively at said opening. If required, means are provided to vibrate said hopper and said chute to ensure the continued flow of said beer can coolers. Following the previous rotation of said turret, ram 48 was stopped such that mandrel 22 is aligned with opening 47 and, therefore, with the presenting open end of the next said beer can cooler. Ram 48 is then extended to carry mandrel 22 towards the open end of said beer can cooler. In the preferred embodiment, a blast of air of short duration is discharged from the outer end of said mandrel as it closely approaches the open end of said beer can cooler, said air blast acting to pressurise the interior of said beer can cooler and open its mouth to facilitate reception of said mandrel. Advancement of said mandrel is continued to the full depth of said beer can cooler, following which said mandrel and said beer can cooler are retracted to the position depicted in the figure. A replacement said beer can cooler then falls into place opposite opening 47. Said turret then rotates through an angle of 90° to bring said mandrel carrying said beer can cooler into position aligned with Station 70.

At Station 70, ram (now depicted as 49) is rotated to rotate beer can cooler 29 while camera 52 scans its surface via line of sight 53 to detect the sewn, axially arranged seam on the side of said beer can cooler. The signal from said camera is processed in a suitable machine vision system. Rotation of said beer can cooler is interrupted to position said seam where it is required in relation to the image to be transferred to said beer can cooler. Ram 49 is then extended to advance said beer can cooler into two open, part-cylindrical arrays of axially arranged rollers 54 rotationally supported in carrier plates 61 at each end. Said carrier plates are pivotally supported on pivot 64 passing through overlapping lugs 63 formed on them. Struts 66 are pivotally attached by pivots

67 to lugs 62 formed on said carrier plates. Force applied by a suitable actuator (not shown) via struts 66 acts to pivotally deploy said carrier plates to the closed position depicted in the figure or to displace them into a downwardly directed position in which a said mandrel and said beer can cooler is able to pass over and clear of them along plane of displacement 75. With said roller arrays in the closed position depicted, said rollers bear against the external surface of said beer can cooler. A pre-printed sheet of said image transfer medium 28 is fed from a cassette 42 via guide 43 to enter between first roller 73 and said beer can cooler. Said mandrel and beer can cooler are then rotated by ram 49 to wrap said sheet of image transfer medium around said beer can cooler beneath rollers 54. As the tail of said sheet of image transfer medium leaves guide 43 , rotation of said mandrel and said beer can cooler is briefly interrupted and a tube 76 having a plurality of small orifices along its length is raised by a suitable mechanism (not shown) to deposit a plurality of small spots of peelable adhesive onto said sheet of image transfer medium. Rotation of said mandrel and said beer can cooler is then continued to complete the wrapping of said sheet of image transfer medium around said beer can cooler, in which situation said spots of adhesive create sufficient adhesion between the overlapping part of said sheet of image transfer material to retain said sheet of image transfer medium in place on said beer can cooler. The mechanism (not shown) to displace tube 76 and to supply it with said adhesive is fixed to guide 43. In an alternative embodiment (not shown) said camera is deleted and a small jockey wheel is deployed to ride on the exterior surface of a said beer can cooler to detect the irregularity of said sewn seam. Said roller array is then opened fully and ram 49 retracted to withdraw said mandrel and said beer can cooler wrapped in said sheet of image transfer medium and return them to the position depicted. Said turret then rotates through an angle of 90° to bring said mandrel carrying said beer can cooler wrapped in said sheet of image transfer medium into position aligned with Station 71.

At Station 71, ram (now depicted as 50) is extended to position said wrapped beer can cooler between the open, pre-heated platen upper and lower parts (as depicted in Figure 2) of image transfer unit 1, 2, 3. Said platen parts are then closed for the required time to effect the image transfer process in the manner described. Said platen upper and lower parts are then opened and ram 50 retracts to withdraw said platen and said beer can cooler from them. Said turret then rotates through an angle of 90° to bring said mandrel carrying said beer can cooler still wrapped in said sheet of image transfer medium into position aligned with Station 72.

At Station 72, ram (now depicted as 51) is rotated to bring the overlapping part of said sheet of image transfer medium into a position such that the free end is slightly above the line of discharge of multiple nozzles 74. Small air receivers 55 are charged with compressed air via air line 56 and suitable valves (not shown) discharge explosive jets of air via said nozzles to strip said sheet of image transfer medium from said beer can cooler and drop it into chute 60 where it passes to a storage bin (not shown) for disposal. Ram 51 is then extended to bring said beer can cooler between jaws 57 displaced by levers 58 operated by a suitable actuator (not shown). Said jaws close to grip said beer can cooler while said ram retracts to withdraw said mandrel from it. Said jaws then open to drop said printed beer can cooler into chute 59 for packing. In an alternative embodiment (not shown), said image transfer medium is delivered from a continuous roll and cut to length by automatic cutting means.

In the preferred embodiment, a microprocessor-based control unit regulates all functions of said automated image transfer apparatus. Camera 29 and nozzles 74 are situated above or below the plane of travel of said mandrel and said beer can cooler. Chute 60 is situated below the same plane.

hi an alternative embodiment (not shown), the image transfer unit depicted at Figure 1 is modified such that base 1 is extended outwardly for a suitable distance to support a mandrel withdrawal unit. Said mandrel withdrawal unit comprises a sliding bearing, return spring and electrically-operated latch mechanism. Said sliding bearing is positioned collinear with the axis of cylindrical cavity (depicted as 21 in Figure 3) when said platen upper and lower parts are in abutment and is raised slightly simultaneously with the raising of said platen upper part. A mandrel such as that depicted in Figure 3 is employed in the said embodiment, its handle or manipulating bar 27 being extended and sized to provide a sliding fit in said sliding bearing. Said return spring acts against the structure of said mandrel withdrawal unit and the outer end of said handle or manipulating bar to urge said handle or manipulating bar towards outward displacement and thus disengagement of said mandrel (and a said beer can cooler installed on it) from said cylindrical cavity. Said electrically-operated latch mechanism prevents such displacement of said handle or manipulating bar from occurring, hi operation, with said mandrel displaced away from said cylindrical cavity, a said beer can cooler is positioned on said mandrel and a said sheet of image transfer medium wrapped and secured around it. Said mandrel, said wrapped beer can cooler and said handle or manipulating bar are then manually, slidingly displaced inwardly to position said wrapped beer can cooler between the open, pre-heated mandrel upper and lower parts (depicted as 5, 6 in Figure 2) in which position said electrically-operated latch is automatically engaged. Said raising of said sliding bearing acts to provide clearance of said wrapped beer can cooler from said platen lower part. A control is then operated to initiate an automatic image transfer cycle, in the preferred embodiment, said control taking the form of a 'Start' button. Said automatic image transfer cycle comprises closure of said mandrel upper and lower parts with simultaneous lowering of said sliding bearing, timing of the period of closure required to effect said image transfer process, opening of said mandrel upper and lower parts with simultaneous raising of said sliding bearing, operation of said electrically-operated latch mechanism to release said handle or manipulating bar to permit said return spring to withdraw said mandrel and said wrapped beer can cooler from between said mandrel upper and lower halves, and the initiation of a visual or aural indication of completion of the image transfer cycle.

In the preferred embodiment of said image transfer process, the external diameter of mandrel 22 (as depicted in Figure 3) and the internal diameter of cylindrical cavity 31 (as depicted in Figure 2) are determined for each type of neoprene rubber used and, where necessary, for each batch. Said mandrel and said platen are thus made in a range of diameters and installed in said image transfer apparatus as required.

The coefficient of thermal expansion of a particular sample of neoprene rubber material is largely dependent upon the size and number of gas vesicles within it. The determination of the diameters of said mandrel and said cylindrical cavity to be used in transferring an image to a particular batch of beer can coolers must thus be made by careful measurement of the increase in thickness of the sample resulting from its heating to the image transfer temperature. For optimal image transfer efficiency, a said beer can cooler installed on said mandrel and wrapped in said sheet of image transfer medium must make a light sliding fit in said cylindrical cavity. Where the coefficient of thermal expansion of a particular sample of neoprene rubber material is relatively large, an unacceptable clearance would be required between said mandrel/beer can cooler/image transfer medium combination and the internal surface of said cylindrical cavity to prevent excessive compression of said neoprene rubber material during heating, such clearance resulting in uneven pressure upon said image transfer medium and, as a result, erratic image transfer. Where this is the case, in an alternative embodiment (not shown), said mandrel carrying a beer can cooler is preheated in an oven to a specified temperature below that at which dye vaporisation occurs, the resultant expansion of said neoprene rubber material restoring the desired clearance from the internal surface of said cylindrical cavity. Said image transfer medium is wrapped around said beer can cooler in the manner described immediately prior to the image transfer process. The temperature to which said mandrel and beer can cooler combination must be pre-heated is determined experimentally. In another alternative embodiment (not shown), where an unacceptable clearance would similarly be required between said mandre^eer can cooler/image transfer medium combination and the internal surface of said cylindrical cavity, said mandre^eer can cooler/image transfer medium combination is supported coaxially within said cylindrical cavity upon said handle or manipulating bar, said material of said beer can cooler being heated, initially, by radiant heat and convective airflow and progressively expanding until said image transfer medium contacts the inner surface of said cylindrical cavity, whereupon said image transfer process occurs. During this process, said image transfer medium is secured in place on said beer can cooler using some form of light adhesive tape, said adhesive tape being stretchable and permitting unrestricted expansion of said image transfer medium via relative movement of its overlapping ends as the material of said beer can cooler expands.

The objective is to ensure that the image transfer process take place with minimal compression of said neoprene rubber material. The contraction resulting from cooling following completion of said image transfer process then acting to sharpen and improve the quality of said transferred image. Additionally, as said neoprene rubber material of said beer can cooler is not compressed during said image transfer process, the transferred image can be made to extend precisely to the upper and lower edges of said beer can cooler. Other image transfer methods result in narrow lines of white, imprinted substrate at said upper and lower edges, said lines detracting from the aesthetic appeal of the finished work.