GB2117320A - Transfer printing on articles having flat, curved or irregularly- shaped surfaces - Google Patents

Abstract

A pattern of sublimable dyestuff is applied to a solid article carrying a coating of polymeric material. In one embodiment, a motor vehicle shaped panel (e.g. door) to be printed, is brought adjacent heating head 20 carried by carriage 50 which is displaceable along rails 70, 72 and struts 78, 80 engage respectively with a gutter and the wheels of the vehicle. A transfer sheet or carrier printed with sublimable dye(s) is positioned on the panel to be printed. Heat applied causes migration of the dye(s) into the polymer coating (which may be pre- applied or may be the usual vehicle finish) on the panel. The method of the invention can be applied to other solid shaped articles, and can be carried in effect without use of pressure. For instance, a hand painted design can be caused to migrate into a polymer coating on an article simply by heat application, or a video signal control laser(s) to cause the migration of a coating of sublimable dye. <IMAGE>

Description

SPECIFICATION Transfer printing on articles having flat, curved or irregularly-shaped surfaces This invention concerns transfer printing on articles having flat, curved or irregularly-shaped surfaces.

The invention more particularly relates to a method of and apparatus for printing, using sublimable dyes, applied directly, or applied indirectly by means of a carrier sheet, e.g. as one or more transfers, on articles (for convenience hereinafter referred to as "receptors") having flat, curved or shaped surfaces, for example panels of motor vehicles, components or panels of machines, domestic appliances and the like, advertising panels and structures, and so on.

Transfer printing is fairly common within the textile industry, the two main known processes being intermittent flat bed printing and continuous rotary printing. Both of these known processes will effect transfer of print only onto flat even surfaces. This means that the known processes are impractical for use in the transfer printing of receptors having curved or irregularlyshaped surfaces, such as motor vehicle panels, machine panels or any regular or irregular curved, shaped or contoured object.

The application of slogans, instructions, legends and/or other designs, patterns lettering and the like to irregularly-shaped articles, such as motor vehicle panels, machinery and the like often involves time-consuming hand-painting and/or stencilling. Because it is labour intensive, it is very expensive. Moreover, the obtention of consistancy and accuracy of the reproduction is not easy.

An object of the present invention is to provide a method whereby printing upon the surfaces of solid articles, virtually of any shape, (for example vehicle body panels) can be achieved with the minimum of manual operations so that the above-discussed difficulties and disadvantages are obviated and constantly accurately-reproducible printing on successive articles, whether they be round, angled, rippled or otherwise shaped, can be reliably achieved.

A further object of the invention is to provide a form of apparatus for carrying the method as aforesaid into effect and which lends itself particuiarly conveniently to being rendered in a form suitable for printing motor vehicle body panels.

With the above-discussed objects in view the present invention provides, as a first feature, a method of transfer printing a solid article having a flat, curved or irregularly-shaped surface using one or more sublimable dyes, which comprises providing a synthetic polymer coating on said surface, applying the said coating in a desired pattern or design, and thereupon subjecting said surface to heat for an appropriate period of time, thereby to induce migration of the dye or dyes into said polymer coating.

The synthetic polymer coating may be present as a precoating on the article, for example a painted coating applied to the article during or after its manufacture. Such synthetic polymer coating may be an acrylic resin based pre-coating.

Acrylic resin based coatings are, of course, the usual finish coatings provided on motor vehicle panels.

As applied to the printing of panels of motor vehicles, the method of the invention may be so carried out that the or each panel is printed whilst in situ on the vehicle.

Various methods are available for applying the dye or the dyes to the surface to be printed. For instance, it can be achieved by being painted or otherwise coated directly onto the said surface.

However, if desired the dye is or the dyes are applied to the said surface by means of a carrier sheet or "transfer". This has the advantage that one can prepare one or more pre-printed carrier sheets or transfers as desired or necessary ready for printing a single article (or vehicle) or a succession of articles (or vehicles) at a time when the articles (vehicles) can conveniently be made avaiiable.

The carrier sheet may be a paper sheet, or it may be of a sheet material by which the dye is or the dyes are absorbed, and which is stretchable to accommodate itself to the shape of the surface to be printed.

In carrying the method of the invention into effect, the surface being printed may be subjected to heat by means of a heating head which is brought into register with the said surface. The arrangement may then be such that the heating head is sealed relative to the surface to be printed and the pressure prevailing in the space between said head and said surface is reduced. This will ensure that the carrier sheet is applied in its entirety against the surface to be printed.

As an alternative the heating head may be pressed towards the surface to be printed so as to apply pressure to the carrier sheet and press it against said surface.

The heating head may then be pressed towards the surface by supplying fluid under pressure and at an elevated temperature into a chamber, part of which is defined by a membrane which is pressed against the said surface.

As applied to printing on motor vehicle panels, the head may be supported upon a movable carriage so arranged that the vehicle can be driven into a position alongside the carriage, the carriage then being adjusted relative to the panel, and the head then being displaced into engagement with the said panel.

The invention further includes an article printed by the method aforesaid.

As another feature, the invention also provides apparatus for use in transfer printing a solid article having a flat, curved or irregularly-shaped surface and having a synthetic polymer coating on said surface, by causing migration into said surface of a sublimable dye or dyes applied over said coating in a desired pattern or design, comprising a heating head mounted for displacement so as to enable it to be registered with said surface and to subject the said surface to heat for an appropriate period of time.

For enabling the heating head to be used in conjunction with a carrier sheet or transfer and to ensure that said sheet or transfer can be firmly pressed against the surface to be printed, the head is preferably constructed and/or mounted to enable it to adapt itself to said surface, and this may be achieved for example, by being mounted, by way of a universal joint, upon an extensible rod of a hydraulic or pneumatic ram.

Naturally, the head should be arranged to assume a neutral initial position, e.g. a substantially vertical position, from which it can deflect upon being pressed towards the surface to be printed. This can be achieved by way of spring means connecting with the head.

In one practical rendering of the apparatus of the invention, the head comprises a backing carrying a flexible sheet or membrane for engagement against the surface to be printed, this sheet or membrane contributing to defining a chamber for receiving a fluid under pressure and at an elevated temperature.

In another practical rendering of the apparatus of the invention, the head comprises a vacuum casing having a sealing skirt for sealing with the article around the surface to be printed, means being connected to the casing for applying suction thereto. Then, a front face of the casing, surrounded by the skirt, preferably carries a plurality of infra-red heating elements.

For ensuring reliable sealing of the skirt with the article, around the surface to be printed, a plurality of profile rods are preferably provided around the vacuum casing so as to be individually extensible to engage with respective regions of the skirt and press the latter against the article, to seal therewith.

In the apparatus of the invention, the heating head is preferably carried by a frame which is mounted for up and down movement by way of guide rollers which run upon uprights forming part of a carriage which is displaceable horizontally upon rails. With this arrangement, a motor vehicle can be driven into position adjacent the heating head, and the carriage may then comprise struts, for instance one or more upper struts for engaging a vehicle cutter and one or more lower struts for engaging wheels of the vehicle, thereby to steady the apparatus relative to the vehicle.

In order that the invention may be fully understood, it will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic front view illustrating a first embodiment of the apparatus of the invention; Fig. 2 is a diagrammatic section taken as indicated by the line Il-Il of Fig. 1; Fig. 3 is a view similar to Fig. 1 but illustrating a second embodiment of the apparatus of the invention; Fig. 4 is a view, comparable with Fig. 2, but illustrating the embodiment of Fig. 3; Fig. 5 is a diagrammatic rear view with parts cut away, illustrating an alternative form the heating head may take; and Fig. 6 is a diagrammatic side view illustrating the heating head of Fig. 5 connected to suction means and adjusted for sealing against a relatively flat article to be printed.

Throughout the various figures of the drawings, like reference numerals have been allocated to like parts.

Referring firstly to Figs. 1 and 2 of the drawings, the preferred embodiment of the apparatus according to the invention as illustrated therein is specifically designed to enable it to be used for transfer printing on the door panels, side panels and like components of motor cars and comprises a heating head indicated generally by the reference numeral 20. This head 20 has been shown oniy diagrammatically in the drawings and comprises a backing plate 22 to which is secured an outer jacket or membrane 24, this being clamped to the plate 22 by its edges, by means of bolts shown schematically at 26 so as to define, between it and the backing plate 22, a chamber 28. Mounted within this chamber 28 is a suitable heating element (not shown) such as an electrical heating element and this serves to heat a liquid filling (e.g. of oil, not shown) within the chamber 28.For simplification of illustration, an inlet and outlet for the liquid and connections and ancillary components for the heating element have been omitted from these figures.

The membrane 24 may be of any suitable flexible, pliable or yielding material which will retain the liquid at an elevated temperature up to, for example, 2000C, for instance a high melting paint polyester plastics sheeting; or a plastics or metal foil. It is, however, preferably a silicon rubber. The liquid within the chamber 28 may be a mineral oil or a vegetable oil which remains liquid at temperatures up to 200or as aforesaid.

The heating head 20 is mounted on the free end of a piston rod 30 of a ram, indicated generally by the reference numeral 32, by means of a universal joint 34 which is shown diagrammatically in Fig. 2. The ram 32 is carried by a frame 36, and comprises a cylinder 38 bolted by a flange 40 on its front end to a cross plate 42 extending between spaced-apart upright side members 44 of the frame 36, these side members 44 being connected at top and bottom by horizontal top and bottom members 46, 48.

The frame 36 is mounted for up and down movement upon a carriage, indicated generally by the reference numeral 50, by rollers 52, carried by respective U-brackets 54 projecting laterally from the frame side members 44, engaging behind respective lateral flanges 56 of T-sectioned uprights 58 of the carriage 50. These uprights 58 are spaced apart by horizontal struts 60, and are provided at top and bottom with respective Ubrackets 62, 63 whereon are mounted rollers 64 which run on horizontal flanges 66, 68 respectively of upper and lower inverted-Tsectioned guide rails 70, 72.

Springs 74 between the horizontal struts 60 and the heating head 20 tend to hold the latter in the illustrated position, but permit the head 20 to be moved in its orientation about the universal joint 34 as will be evident later.

Each of the U-brackets 62 and 63 has affixed thereto, at the heating head side, a respective journal bracket 76 whereby a respective telescopic strut 78, 80 is connected to the carriage 50. The upper telescopic struts 78 each have on the outer and thereof a respective jaw arrangement 82 for engagement with a gutter or like formation on a motor vehicle (not shown) whose panels are to be printed; the lower telescopic struts 80 correspondingly has fingered or hook-like arrangements 84 for engagement with the wheels of the vehicle, e.g. by engaging with the hubs thereof.

The manner of use of the apparatus will readily be understood from the foregoing description.

Assuming a design to be required to be printed onto the side panelling (e.g a door panel) of a motor car, the struts 78, 80 are swung up to be out of the way and the car is driven into position with the panel to be printed disposed generally alongside the carriage 50 near to the head 20.

The carriage 50 is then moved along the guide rails 70, 72 to the correct position and the struts 78, 80 are swung to the illustrated positions and engaged respectively with the gutter sections and wheels of the car. These struts are then tightened up, by shortening, thereby to ensure a stable relationship between the carriage and the car.

It will be understood that if the car has already been finish painted (as will usually be the case) the panel required to be printed will already carry a finish coating of a sublimable-dye-receptive material, that is to say a coating of acrylic-based lacquer, previously applied thereto. If such a coating is not present, as a first stage in the printing, appropriate paint coats will be applied to the panel.

Assuming, therefore, the presence of the finish coat, the next step in the printing of the panel is to apply over the panel a carrier or transfer sheet, such as a paper or foil sheet, bearing the design required to be printed, applied thereto in sublimable dye(s). The carrier having been appropriately positioned, the ram 32 is actuated to extend the piston rod 30, thereby to press the head 20, by the membrane 24 against the carrier.

As a result the carrier is caused to conform in configuration to the shape and contours of the panel to be printed. The liquid within the chamber 28 is maintained at a suitable elevated temperature, related to the sublimable dye(s) of course, for instance in the region of 2000 C, for an appropriate period of time to cause the dye to migrate into the coating on the panel, thereby to print the desired design thereon. After this has been achieved, the ram 32 is retracted and the carrier sheet is removed.

These operations can, of course, be repeated as necessary on whatever other panels of the car may also be required to be printed, and upon completion, the vehicle is, of course, driven away.

Referring now to Figs. 3 and 4, this figure illustrates a second embodiment of the apparatus of the invention which is used in a manner similar to-that above described with reference to Figs. 1 and 2. In this embodiment, a forwardly extending platform 90 is clamped onto the lower horizontal struts 60 by bolts 92 through the platform 90 and a backing plate 94 below the struts 60. This platform 90 supports an oil reservoir 96 whereby heated oil can be pumped through the heating head 20 by way of inlet and outlet lines 98, 100.

The head 20 may incorporate one or more internal partitions providing for the interior thereof to incorporate one or more air chambers to which compressed air may be supplied by way of an air supply line 102 (not shown in Fig. 4).

The modified embodiment of the heating head 120 illustrated diagrammatically in Figs. 5 and 6 of the drawings differs from that shown in the preceding figures in that it comprises basically a vacuum box or chamber 122, made for instance of aluminium, and embodying a panel 124 of heat-insulating and electrically insulating material such as asbestos carrying a plurality of infra-red electrical heating elements 126. Around the outer side walls of the vacuum box 122 is a pliable skirt 128 which, in turn, is superimposed by a plurality of closely-adjacent profile rods 130 which are all diagrammatically illustrated and which can be extended in their longitudinal direction. A vacuum line 132 opens to the panel 124 at 125 under the control of a valve 1 34 and connects to a suction pump 136 and a vacuum reservoir 138.

The use of this arrangement is, of course, slightly different from the prior-described embodiments. It can be used for printing by use of a carrier or transfer, or in the case where the dye is or dyes are applied directly (e.g. by painting) onto the panel required to be printed. When the head 1 20 has been offered to the panel to be printed, the skirt 128 is sealed thereto by extending the profile rods 130 individually and fixing them in position pressing the skirt 1 28 to the panel. Suction is then applied to the region enclosed by the skirt 128, by opening the valve 134, and assures intimate contact with the carrier (where used) with the surface of the panel being printed.

The invention is not confined to the precise details of the foregoing examples and many variations may be made to the method of printing and the apparatus as described, within the scope of the following claims.

In the arrangements of Figs. 1 and 2, or Figs. 3 and 4, for instance, the chamber 28 may be subdivided for instance by means of a plate, for example composed of rigid asbestos sandwiched between aluminium sheets, separating a oil-filled outer portion of the chamber from heating elements on the backing plate 22. An air vent oil filler tube and pyro cable entry may be connected to the upper regions of the backing plate 22 in the arrangement of Figs. 1 and 2.

As already described, when using the apparatus to effect the transfer printing of a design or motto onto a motor vehicle panel, the vehicle panel is precoated with a synthetic polymer (which may be clear or coloured), for example an acrylic, polyester, polyurethane, nylon or methylmethacrylate polymer or a mixture thereof, or any other synthetic polymer for which the dye(s) to be printed have an affinity. Current motor vehicle finishes, based on acrylic resins, are suitable and thus may not require precoating prior to printing.

Normally in carrying the method of the invention into effect, a transfer on paper or any other suitable carrier such as foil will be printed, using sublimable dyes, which are normally known as disperse dyes as named in the colour index of the Society of Dyes and Colourists (SDC), 3rd edition.

The transfer, on paper or other suitable carrier, is placed in position on the surface and is held in place, e.g. by means of adhesive tape whilst the ram 32 is activated and the head 20 is forced into contact with the transfer and body panel, the head then faithfully following the contours of the surface or panel. The duration and extent of the pressure applied may be subject to a timing device and control circuitry to apply pressure and switch on the electrical heating elements, and thereafter to reiease pressure and switch off the heating elements.

The printing operation may be accomplished, for instance at pressures in the range of 0.5 to 5 pounds per square inch (approx. 0.035 to 0.35 kg.

per square cm.) and a temperature of 1 600 to 2400 (preferably about 2000C) for up to three minutes, these conditions normally being appropriate to induce dye migration into the polymer or other coating on the panel being printed. These figures for temperature and pressure may be varied according to practical requirements and reduction in the transfer time may be achieved by appropriate increase in temperature and reduction in pressure.

Upon completion of the printing, the heating head removed, and the image of the print will be found to be faithfully reproduced in the polymer coating. No after treatment will normally be necessary although the appearance of the print may be enhanced by a final coating of clear lacquer to impart a gloss appearance thereto. The dyes transfer in vapour form, so no other material leaves the carrier and the resulting print is fast and resistant to washing with water and common solvents. One obtains with the invention, therefore, all the advantages of paper printing, yet in relation to the printing of shaped panels. Of course, the method and apparatus can be used to print articles other than motor cars.

The use of the carrier sheet or transfer is not essential to the invention. The dye(s) may be painted directly onto the polymer coating, in the form of inks or the like, e.g. by hand painting, and subsequently, using the apparatus as disclosed or a plain heating head, without a pressure chamber 28, can be caused to migrate into the polymer layer. Any residue of the ink compounds are preferably removed by washing.

The heating head size is not critical. The head can be of any practical dimensions according to particular requirements and the shapes and sizes of the panels to be printed.

Where a carrier is used, this may be, for example, of hydrophilic material which is stretchable to accommodate various panel or surface shapes. Moreover, where a carrier is used, it may be adhered in place on the panel, for instance by the use of an adhesive, such as partially-hydrolysed polyvinyl alcohol adhesive, which does not interfere with dye transfer. Then, dye transfer can be achieved simply by heating, without the application of pressure.

Various heating head arrangements may be employed. For instance, the head may be constructed simply to transfer heat as infra-red energy, having no means for applying pressure either directly by means of a flexible membrane or indirectly by creating a vacuum.

The heating source incorporated in the head may vary according to the head arrangement used. A head having an oil-filied jacket may have the oil for filling the same pre-heated before entry into the jacket, or the arrangement may be such that the oil is electrically heated in situ. As described a infra-red heater may be used in a head construction having no flexible membrane for pressing against the article to be printed.

Moreover, a laser may be used as a heat source in the method of the invention. Such a laser may be driven by electronic circuitry, for example involving the conversion of television images into digital or analogue data which is used to switch and direct the laser beam so as to transfer yellow, red and blue dyes to build up a full trichromatic print or copy from an original television image.

Other modifications are possible.

Claims (30)

Claims

1. A method of transfer printing a solid article having a flat, curved or irregularly-shaped surface using one or more sublimable dyes, which comprises providing a synthetic polymer coating on said surface, applying the said coating in a desired pattern or design, and thereupon subjecting said surface to heat for an appropriate period of time, thereby to induce migration of the dye or dyes into said polymer coating.

2. A method as claimed in claim 1 wherein the synthetic polymer coating is a precoating on the article.

3. A method as claimed in claims 1 or 2 wherein the synthetic polymer coating is an acrylic resin based pre-coating.

4. A method as claimed in claim 3 wherein the solid article is a motor vehicle panel.

5. A method as claimed in claim 4 wherein the panel is printed whilst in situ on the vehicle.

6. A method as claimed in any preceding claim wherein the dye is or the dyes are applied to the said surface by being painted or otherwise coated directly onto the said surface.

7. A method as claimed in any of claims 1 to 5 wherein the dye is or the dyes are applied to the said surface by means of a carrier sheet.

8. A method as claimed in claim 7 wherein the carrier sheet is a paper sheet.

9. A method as claimed in claim 7 wherein the carrier sheet is sheet material by which the dye is or the dyes are absorbed, and which is stretchable to accommodate itself to the shape of the said surface.

10. A method as claimed in any preceding claim wherein the surface is subjected to heat by means of a heating head which is brought into register with the said surface.

11. A method as claimed in claims 7, 8 or 9 wherein the heating head is sealed relative to said surface and the pressure prevailing in the space between said head and said surface is reduced.

12. A method as claimed in claims 7, 8 or 9 and in claim 10 wherein the heating head is pressed towards said surface so as to apply pressure to the carrier sheet.

13. A method as claimed in claim 12 wherein the heating head is pressed towards the surface by supplying fluid under pressure and at an elevated temperature into a chamber, part of which is defined by a membrane which is pressed against the said surface.

14. A method as claimed in any of claims 10 to 13 wherein the head is supported upon a movable carriage, and the article is a panel on a motor vehicle, characterised in that the vehicle is driven into a position alongside the carriage, the carriage is adjusted relative to the panel, and the head is displaced into engagement with the said panel.

1 5. A method of transfer printing on a solid article substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 6. An article printed by the method of any of the preceding claims.

1 7. Apparatus for use in transfer printing a solid article having a flat, curved or irregularlyshaped surface having a synthetic polymer coating on said surface, by causing migration into said surface of a sublimable dye or dyes applied over said coating in a desired pattern or design, comprising a heating head mounted for displacement so as to enable it to be registered with said surface and to subject the said surface to heat for an appropriate period of time.

18. Apparatus as claimed in claim 1 7 wherein the head is constructed and/or mounted to enable it to adapt itself to the said surface.

1 9. Apparatus as claimed in claim 1 7 or 18 wherein the heating head is mounted upon a ram by which it can be urged towards engagement with the said surface.

20. Apparatus as claimed in claim 17, 18 or 19 wherein the head is mounted by way of a universal joint on the ram.

21. Apparatus as claimed in any of claims 17 to 20 wherein spring means connecting with the head yieldingly urges the head towards an initial orientation.

22. Apparatus as claimed in any of claims 1 7 to 21 wherein the head comprises a backing carrying a flexible sheet or membrane for engagement against the said surface, the sheet or membrane contributing to defining a chamber for receiving a fluid under pressure and at an elevated temperature.

23. Apparatus as claimed in any of claims 1 7 to 21 wherein the head comprises a vacuum casing having a sealing skirt for sealing with the article around the said surface, means being connected to the said casing for applying suction thereto.

24. Apparatus as claimed in claim 23 wherein a front face of the casing, surrounded by the skirt, carries a plurality of infra-red heating elements.

25. Apparatus as claimed in claim 23 or 24 wherein a plurality of profile rods are provided around the casing and are extensible individually for engagement with the skirt to press the latter against the article to seal therewith.

26. Apparatus as claimed in any of claims 17 to 25 wherein the head is carried by a frame which is mounted for up and down displacement.

27. Apparatus as claimed in claim 26 wherein the frame comprises guide rollers which run upon uprights forming part of a carriage which is displaceable horizontally upon rails.

28. Apparatus as claimed in claim 27 wherein the carriage comprises steadying struts for engagement with the article to be printed.

29. Apparatus as claimed in claim 28 and which is adapted for printing a panel surface of a motor vehicle, characterised in that the steadying struts include at least one upper strut adapted for engagement with a vehicle roof gutter and at least one lower strut adapted for engagement with a wheel of the vehicle.

30. Apparatus for use in transfer printing a solid article substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 or in Figs. 3 and 4, or in Fig. 5, or in Figs. 6 and 7 of the accompanying drawings.