WO2005081915A2

WO2005081915A2 - Apparatus and process for manufacturing a film for applying varnish and colour onto an object

Info

Publication number: WO2005081915A2
Application number: PCT/US2005/005522
Authority: WO
Inventors: Maximilian Zaher
Original assignee: Demaxz, L.L.C.
Priority date: 2004-02-23
Filing date: 2005-02-22
Publication date: 2005-09-09
Also published as: CN1946571A; EP1732769A4; EP1732769A2; WO2005081915A3

Abstract

A process and apparatus for manufacturing a film that can be used to apply varnish and colour onto an object to be decorated. The process includes the steps of; (1) applying a layer of colour onto a first film, which has release properties; (2) applying a layer of varnish onto the colour layer of the first film; (3) partially curing the varnish layer; (4) transferring by release the layers of varnish and colour from the first film onto a second film having release properties, wherein the second film is more flexible than the first; and (5) further curing the transferred layer of varnish on the second film.

Description

Apparatus and Process for Manufacturing a Film for Applying Varnish and Colour onto an Object This application claims priority to U.S. Patent Application Serial No. 60/546,736 filed on February 23, 2004 which is incorporated by reference herein in its entirety. BACKGROUND OF INVENTION Technical Field The invention is concerned with a process and apparatus for manufacturing a film that can be used to apply colour and varnish onto an object to be decorated. Background Art Films comprising so-called release properties are well known in the prior art, see e.g. EP 1 053 793 Al and EP 0 573 676 Bl. The prior art knows both papers and films made of a resin the surfaces of which are prepared such that the film comprises release properties. If layers of colour or varnish are applied to such a film comprising release properties, the layers can be transferred onto a object to be decorated wherein the layers of varnish or colour are peeled off from the film. Typically these release properties are obtained or enhanced by applying a layer of a silicon based release agent between the film and the layers of colour and varnish. However, it is often undesirable to have a silicon residue remaining on the colour/varnish layers applied to the object to be decorated. The prior art according to EP 0 573 676 Bl discloses a process of decorating an object wherein a layer of varnish is applied onto a film comprising release properties. That layer of varnish is partially cured. A layer of colour is applied onto the partially cured varnish layer and a second layer of varnish is applied onto the colour layer. The second layer of varnish is also partially cured. Thereafter, the layers of varnish and colour, respectively, are transferred onto the object to be decorated (the "substrate"). After the transfer by release, the first and second varnish layers are completely cured. The "curing" is also called "cross linking". EP 1 053 793 Al teaches the application of varnish and colour onto an object by means of a release film, wherein a glue is applied on top of the varnish layers and colour layers of the release film. When transferring the layers onto the object to be decorated, the glue is in direct contact with the object. The prior art also knows a process of manufacturing a film that can be used to apply colour and varnish onto an object to be decorated wherein a first film comprising release properties is printed with a colour layer and, thereafter, that colour layer is transferred by release onto another film comprising release properties. The other film is more flexible than the first film. It is also well known in the prior art to use a so-called coating roller and a so- called pressure roller (also sometimes called a counter roller) for applying varnish onto a flexible film. The flexible film may preferably have so-called release properties such that the layer of varnish can be transferred from the film onto an object, e.g. after curing (cross-linking) or partial curing of the varnish, by peeling off the varnish layer. Films formed of materials such as polypropylene, polyethylene, polyvinyl alcohol, polyvinyl chloride, polymethylmeth-acrylate, or polyethylene terephthalate typically have favorable release properties. The release properties of films may also be enhanced with physical processes such as manipulating the surface tension of the firm (for example through a conventional corona treatment) or chemical processes such as the application of various conventional release agents. Objects of Invention It is an object of the present invention to provide a method and apparatus for manufacturing a film that can be used to apply colour and varnish onto an object to be decorated, wherein the colour and varnish comprise very good cohesion properties on the decorated object. The object to be decorated may e.g. be made from wood or a wood-like material, or the object may be made from plastics or the like. Also objects made of metal can be covered with colour and varnish by means of a film according to the present invention. Furthermore, objects made of glass or ceramic material can be decorated with colour and varnish by means of a film according to the present invention. To this end, the present invention teaches a process and apparatus for manufacturing a film that can be used to apply varnish and colour onto an object, the process comprising the steps of: (1) applying a layer of colour onto a first film, the first film comprising release properties; (2) applying a layer of varnish onto the layer of colour on the first film; (3) partially curing the layer of varnish; (4) transferring by release the layers of varnish and colour from the first film onto a second film comprising release properties, wherein the second film is more flexible than the first film; and (5) further curing the transferred layer of varnish on the second film. Alternatively, the present invention teaches a process of manufacturing a film that can be used to apply colour and varnish onto an object, the process comprising the steps of: (1) applying a layer of varnish onto a first film, the first film comprising release properties; (2) applying a layer of colour onto the layer of varnish on the first film; (3) partially curing the layer of varnish; (4) transferring by release the layers of colour and varnish from the first film onto a second film comprising release properties, wherein the second film is more flexible than the first film; and (5) further curing the transferred layer of varnish on the second film. Likewise, an apparatus for manufacturing the film could comprise: (1) a varnish application station for applying a layer of varnish onto a first film, the first film having release properties; (2) a first curing station for partially curing the layer of varnish; (3) a supply cylinder for supplying a second film, the second film being more flexible than the first film; (4) a transfer station for transferring by release at least the layer of varnish from the first film to the second film; and (5) a second curing station for further curing the layer of varnish. According to a preferred embodiment of the invention, the first film comprises a colour layer. The colour layer may be on top of the varnish layer or underneath the varnish layer, i.e. in direct contact with the first film. According to another preferred embodiment, a heating station, preferably a heating station using IR-radiation (Infra-Red), is arranged between the varnish application station and the first curing station. In this regard, the term "between" refers to the direction of movement of the first film through the apparatus, e.g. from a supply cylinder for the first film to the transfer station. According to other preferred embodiments of the invention, the first film is made of polypropylene, whereas the second film is made of polyolefine, polyethylene, or PVC. The partial curing in the first curing station is preferably performed by UV- sources emitting UV-radiation. Also, the complete curing of the varnish in the second curing station is, preferably, performed by UV-sources emitting UV-radiation. According to a preferred embodiment of the invention, the first film is made of polypropylene. Polypropylene is relatively stiff, as compared to other films known in the prior art as having release properties. On the other hand, a polypropylene film can be printed with a colour decoration in very good quality. If, in particular, three- dimensional objects are to be decorated, the relative stiffness (non flexibility) of the polypropylene film causes problems. Therefore, according to the present invention, the colour layer and the varnish layer applied onto the colour layer or underlying the colour layer are transferred, via release technique, onto another film comprising release properties, wherein the other film is relatively more flexible than the polypropylene film such that the colour layer and the varnish layer can be transferred from the more flexible film with high quality onto a three-dimensional object, including the edges or recesses in the object. Preferable materials for the second, more flexible film are polyolefines, polyethylens, polyvinyl chlorides (PVC), or polyvinyl alcohols (PVA). In one preferred embodiment, the colour and varnish layers are applied to the first and second films with out the use of (i.e., in the absence of) a release agent. Most preferable, the steps of the processes according to the present invention are performed in one and the same apparatus without time delay in between the steps. In particular, the step of transferring by release the layers of varnish and colour from the first film onto the second film are performed directly, with minimum time delay, after the partial curing of the layer of varnish. The partial curing is preferably performed by UV (Ultra Violet) radiation. The same applies to the further curing of the transferred varnish layer. The further curing is preferably a complete curing, i.e. a complete cross-linking of the varnish. The dye or ink most suitable for the present invention is selected as a UV- resistant dispersion colour. Preferably, the colour layer is formed by applying approximately 10 g (wet) or 3 g (dry) of dye per m² of film. Also sublimable dispersion dyes can be used for the colour layer. Sublimable dispersion dyes are dyes which change directly from a solid state to a gas state and tend to permeate into the substrate as opposed to remaining strictly of the substrate surface. The varnish to be used is known in the prior art, e.g. a varnish based on an alkyl- urethane-resin. The product obtained in accordance with the process and apparatus of the present invention is a film that can be used to apply colour and varnish onto an object to be decorated. The product is a film which can be manufactured and sold. It can be used by the customer e.g. in an apparatus using a membrane by which the film is pressed against the three-dimensional object to be decorated, as disclosed in EP 0 282 859 Bl. Also, the film manufactured in accordance with the present invention can be used in an injection moulding machine. Another embodiment of the present invention is directed to applying a varnish layer onto such a film which, preferably, has release properties. The film may be printed, before or after applying the varnish layer, with a colour layer. In the prior art it was very difficult, if not impossible, to apply relatively thick layers of varnish onto a film. The films in question here typically have a width of more than 100 cm, e.g. a width in the range of 160 to 180 cm. The machines according to the prior art were only capable of applying varnish layers having a thickness typically less than 60 μm. The present invention aims at providing an apparatus that is capable to be adapted to apply a variety of varnish layers of different thickness, in particular relatively thick varnish layers. The present invention provides an apparatus and process for applying varnish onto a film. The apparatus comprises a coating roller for transferring varnish from the coating roller onto the film and a pressure roller arranged adjacent the coating roller. A means is provided for advancing the film at a first velocity through a gap between the coating roller and the pressure roller in addition to means for rotating the coating roller such that the circumference of the coating roller adjacent the film moves at a second velocity different to the first velocity. According to one preferred embodiment of the invention, the means for advancing the film advances the film in a first direction through the gap between the coating roller and the pressure roller, and the means for rotating the coating roller rotates the coating roller such that the circumference of the coating roller adjacent the film moves in a second direction opposite to the first direction. In one alternate embodiment, the film enters the gap at an angle (α) different from zero with a plane that is tangential to both the coating roller and the pressure roller. According to another preferred embodiment of the invention, the coating roller comprises a rubber surface. According to a still further embodiment of the invention, a means is provided for moving at least one the pressure roller or coating roller in a direction parallel to the plane that is tangential to both the coating roller and the pressure roller.

Brief Description of the Drawings Figures 1 to 4 illustrate a first embodiment of a process of manufacturing a film that can be used to apply colour and varnish onto an object. Figures 5 to 7 illustrate another embodiment of such a process. Figure 8 illustrates an apparatus according to the present invention for manufacturing a film that can be used to apply varnish and colour onto an object. Figure 9 illustrates schematically one embodiment of the present invention for applying varnish onto a film. Detailed Description of Invention According to Figure 1 a first film 10 of polypropylene, which in one embodiment may be 15-40 urn thick, is printed with a layer which comprises a colour decoration and forms a colour layer 14. As used herein, the term "colour layer" includes a patterned ink layer such as a wood grain pattern or any other desired pattern. The printing process as such is known in the art, one example of which is referred to as a "Gravure" process. In one embodiment, the first film 10 will have a surface tension (or surface energy) of between approximately 30 and 42 dynes, and more preferably between approximately 35 and 40 dynes, and most preferably between approximately 39 and 40 dynes. This surface tension may be obtained by selection of a material naturally having this surface tension or by modification of the surface tension, such as by a corona treatment process. With the above surface tension, the colour layer may be applied without the use of a release agent. Thereafter, a layer 12 of a varnish is applied onto the layer 14 of colour. Normally, this varnish layer will range from 1 to 130 urn in thickness. These two steps result in the product shown in Figure 1. Thereafter, UV-radiation 18 indicated by arrows in Figure 2 is applied onto the film 10 carrying the layers of colour (14) and varnish (12). The intensity of the UV- radiation is controlled such that the varnish is not completely cured (cross-linked) but only partially cured, i.e. the varnish is still relatively soft. The degree of remaining softness of the varnish can be adjusted by the amount of UV-radiation and depends on the particular requirements which the final product film must fulfill which, on the other hand, depend on the dimensions and shape of the object eventually to be decorated. For example, the partial curing can be obtained by a radiation of approximately 50 to 80 watt/cm² depending of the thickness of the varnish layer. After the partial curing of the varnish layer 12, the layers of varnish and colour are immediately, preferably only with the time delay of the film moving from one station to the next, transferred by release-technique onto another, second film 16 which also comprises release properties. In one embodiment, second film 16 will have a surface tension similar to that described above and will not employ a release agent. The result of that transfer is shown in Figure 3, i.e. the layer 12 of varnish is in direct contact with the film 16 whereas the colour layer is on top of the varnish layer. After the transfer, the layer of varnish is completely cured by means of UV- radiation 20 as indicated in Figure 4. The complete curing (cross-linking) may be obtained e.g. by applying 120 watt/cm². The transfer from the first to the second film can be eased by applying a pressure of 1 to 2 bar and an elevated temperature of approximately 90°C to 180°C and more preferably approximately 90°C to 140°C. Thereafter, the film 16 comprising the colour layer 14 and the completely cured varnish layer 12 can be used for decorating a product. That decoration is performed in accordance with the prior art, i.e. the layers of varnish and colour are transferred by release onto the object, e.g. in accordance with EP 0 573 676 Bl (wherein the object is called a "substrate"), which is incorporated by reference herein. In accordance with the present invention, however, the complete curing, i.e. the complete cross-linking is not performed on the decorated object, i.e. the object carrying the colour layer and varnish layer, rather, according to the present invention, the complete curing is performed on the film 16 comprising the release properties. Thereafter the decoration is transferred from that film onto the object. Those skilled in the art will understand that colour layer 14 may consist of several sub-layers, such as a top coat, a primer, and an adhesive. When colour layer 14 is applied to the object, it is the adhesive sub-layer which binds the combined colour layer 14 and varnish layer 12 to the object. As nonlimiting examples, the adhesive could comprise a polyvinylacetate, a polyacrylate, a poly(methyl methacrylate) (PMMA), a polyolefin, or a melamine-formaldehyde (MF) resin. In a preferred embodiment, the adhesive will be both thermo-curable and UV curable. Preferably, the adhesive will be curable by UV sources such as mercury or gallium UV lamps. The adhesives may be made thermo-curable by including in their composition about 5% to 10% by weight of at least one of the following compounds: ester, ketone, benzyl hydroxene, glycol or water. Also as nonlimiting examples, the primer could be a adhesive compound such as described above, but further including the addition of about 10% to 50% of an iron dioxide pigment (with the percentage depending on the intensity of colour desired) or a titanium dioxide pigment if a white background is desired. Figure 5 illustrates a first film 10 which includes an adhesive layer 21 formed on first film 10, a primer layer 22 on adhesive layer 21, a colour layer 14 on primer layer 22 and a varnish layer 12 on colour layer 14. As an alternative embodiment shown in Figure 6, the primer layer 22 may be eliminated. Whether primer layer 22 is included in the overall film will depend upon what background colours are desired in the overall film. Some background colours may be produced by modification of adhesive layer 21 alone while other background colours will require the additional primer layer 22 to achieve the desired appearance. As discussed in reference to Figures 3 and 4, the various layers will be released to the second film 16 shown in Figure 7 and additional curing will take place. Where the above description discusses one layer applied "on" a film or another layer, this description includes the second layer being applied directly on the film or other layer and the second layer being applied indirectly on or over the film or other layer with some type of intervening layer. The final product illustrated in Figure 7 is a film 16 ready for decorating an object, as described above in more detail in connection with the embodiment shown in Figures 1 to 4. The embodiments illustrated in Figures 1 to 7 can be modified such that more than one colour layer is applied and more than one varnish layer is applied. For example, in the steps illustrated in Figures 1 and 2 as well as Figures 5 and 6, respectively, more than one varnish layer and/or more than one colour layer can be applied onto the film 10. Important is that, in accordance with the invention, the at least one varnish layer is partially cured on the polypropylene film before it is transferred to the more flexible second film 16 illustrated in Figure 3, 4 and 7, respectively. Figure 8 illustrates an apparatus for performing both of the afore-mentioned methods of manufacturing a film that can be used to apply varnish and colour onto an object. According to Figure 8, on a base 30 various stations are arranged to perform the necessary steps to obtain the film. A supply cylinder 32 is provided for supplying a printed first film 10. For example, that first film 10 may be already printed with a layer 14 of colour in accordance with Figures 1 to 4. In other words, the supply cylinder 32 in Figure 8 supplies a film 10 carrying a layer 14 of colour. The film 10 is advanced, via rollers 34, into a varnish application station 36. In the varnish application station 36, a varnish layer 12 (see Figure 1) is applied onto the layer 14 of colour. The varnish application station 36 comprises rollers 36a, 36b for applying the varnish onto the film. Such application rollers are known as such in the prior art. Alternatively, the application station 36 could comprise a set of rollers such as described below in reference to Figure 9. A varnish supply 36c is also indicated schematically in Figure 8. In that varnish application station 36, varnish is applied onto the film so that the film is completely covered with varnish, the colour layer being underneath the varnish. Typically, the varnish layer will have a thickness between 1 and 130 urn. Thereafter, the film is advanced to a heating station 38 in which the varnish is gently heated such that the varnish is more homogeneously distributed on the film. For the heating, IR-sources 38a are used. As one example, the varnish may be heated at 60 °C to 90 °C for 10 to 15 seconds, but this temperature and heating time may be varied as necessary. After passing the heating station 38, the film is advanced to a first curing station 40. The first curing station 40 comprises larger roller 40a on which the film is advanced in Figure 8 from the left-hand side to the right-hand side. Radially with regard to the roller 40a, UV-sources 40b are arranged for partially curing the varnish on the film 10. In a preferred embodiment, the partial curing is obtained by applying a power of 50 to 80 watt/cm², or even less than 50 watt/cm² if the varnish layer is sufficiently thin. The roller 40a is preferably cooled by water. The UV-sources 40b are fixed on a carriage 40c which can be moved from the position shown in full lines in the Figure to the position shown in dashed lines. The left-hand position, shown in full lines, is the operating position. After passing the first curing station 40, the film 10a carrying the partially cured varnish, is advanced to a transfer station 44. The transfer of the varnish layer and the colour layer by means of the transfer rollers 44a, 44b is promoted by applying a pressure of 1 to 2 bar between the rollers and also an elevated temperature in the range of 120°C to 180°C, depending on the material of the film being used. A supply cylinder 42 for supplying a second film 16 is also arranged near the transfer station 44 in order to supply the second film into that transfer station. The transfer station 44 comprises transfer rollers 44a and 44b in order to transfer both the varnish layer and the colour layer from the first film 10a onto the second film 16. As explained above, the second film 16 is more flexible than the first film 10a. Because the first film 10a has released properties, the colour layer and the partially cured varnish layer are transferred by release from the first film onto the second film. This technique of release transfer is known as such in the art. After that transfer, both the first and second film are advanced in common via a roller 46 and another roller 46a to a separating roller 48. At the separating roller 48, the first film 10 is separated from the second film 16a such that the second film 16a carrying the layer of colour and the layer of varnish is advanced to a second curing station 52, whereas the first film 10 is collected at a collecting roller 50. In the second curing station 52, the varnish layer on the second film 16a is completely cured by UV-radiation provided by UV-lamps 52b. The UV-lamps are arranged on a carriage 52c which can be moved into a non-operating position indicated by dashed lines in the Figure. The complete curing of the varnish is preferably obtained by applying 120 watt /cm², depending on the varnish that is used. As an alternative to UV curing, the second curing step could be accomplished by applying heat to the film, at second curing station 52. Normally, this heat curing is employed when the film is to be applied to an object having a complex or irregular surface shape. In one embodiment, UV lamps 52 will be replaced with an IR source for applying heat to film 16a. Naturally, other methods of applying heat to film 16a are within the scope of the present invention. Typically, the heat source should increase the temperature of the film¹ layers to approximately 90°C to 140°C, but other temperatures may be appropriate depending on the composition of the film layers. After the complete curing of the varnish in the second curing station 52, the completed film 16c is advanced via rollers 56 onto a collecting cylinder 58. On connecting cylinder 58, a complete product is ready for shipment to a customer that can use the film for applying varnish and colour onto an object by release technique because the second film 16 also comprises release properties. The alternate embodiment directed to applying a varnish layer onto a film such as described above comprises a coating roller 10 and a pressure roller 112 as seen in Figure 9. Pressure rollers are also sometimes called "counter rollers". The pressure roller 112 is non-steered; i.e. it is not powered and may rotate freely. A dosing roller 114 is arranged adjacent the coating roller 10 for transferring varnish from a supply (not shown) onto the coating roller 110. A plane 116 is tangential to both the coating roller 110 and the pressure roller 112, i.e. the plane 116 passes in- between the rollers, which are adjacent to each other. In a preferred embodiment of the invention, coating roller 110 will have a surface formed of an elastomeric material such as rubber or a similar synthetic or natural polymer. In a more preferred embodiment, the elastomeric surface will have a hardness on the Shore A scale of between approximately 30 and 80. A film 118 having release properties is advanced in the figures from the right hand side to the left hand side. In one embodiment, the release properties may be defined as the film having a surface tension (or surface energy) of between approximately 30 and 42 dynes, or more preferably between approximately 35 and 40 dynes, and most preferably between approximately 39 and 40 dynes. This surface tension may be obtained by selection of a material naturally having this surface tension or by modification of the surface tension, such as by a corona treatment process. The coating roller 110 is rotated around its axis 120 in a counter-clockwise direction as indicated by arrow 146 in the figure. Pressure roller 112 rotates about its axis 122 and is driven at the speed at which the film 118 is advanced. Both coating roller 110 and pressure roller 112 are driven by a conventional drive mechanism such as seen in Figure 8. Generally coating roller 110 and pressure roller 112 are arranged to be capable of exerting a given pressure on film 118 as it passes between the rollers. In a preferred embodiment, coating roller 110 and pressure roller 112 will exert a pressure of between approximately 1 and 4 bars on film 118. The film 118 is guided via rollers 124 and 126 such that, before being advanced between the coating roller and the pressure roller, it is not positioned in the tangential plane 116, but rather defines an angle α between the film 118 and the tangential plane 116, as indicated in the figure. That angle α is acute, and is preferably in the range between about 10° and 30°. As described above, film 118 is advanced in the figure from right to left. Pulling means for pulling the film in the direction 142 are not shown, but they are typically arranged in the figure to the left of the coating roller 110 and the pressure roller 112. For example, a conventional driven collecting roller would be suitable for pulling the film in the direction 142. Varnish is transferred by the coating roller 110 onto the film 118, and in particular onto the upper surface of film 118, as shown in the figure. The varnish is, preferably, curable by so-called cross-linking, which as such is well known in the art. For example, curing means (not shown) may be arranged to the left of the coating roller 110 and the pressure roller 112. A varnish container 128 is arranged underneath the pressure roller 112 to collect excess varnish not used for coating the film 118, e.g. varnish applied at the edges of the film 118. A support 130, which supports both the pressure roller 112 and the coating roller 110, allows rotation of the coating roller 110 and the pressure roller 112 in the direction of arrows 132, i.e. both the coating roller 110 and the pressure roller 112 can be rotated about an axis A that is passing through the axes 120 and 122 in the middle of both rollers. Since the figure shows a centre cross section through the rollers, the axis A is also in the plane of the drawings. By the rotation about axis A in direction of arrows 132, the relative arrangement and positioning between the rollers and the film 118 can be adjusted so that crinkles are avoided. Pressure roller 112 always rotates anti-clockwise as indicated by the arrow. Coating knifes 136, 138, which may be "soft" knives formed of a polyolefin material, are arranged to control the transfer of varnish from the dosing roller onto the coating roller, as is known in the art as such. The coating roller 110 and the dosing roller 114 rotate typically in opposite directions, as indicated by the arrows 146, 148. As is known in the art, the amount of varnish transferred to the film may be regulated by the distance between the coating knives and rollers and the pressure exerted on the film by coating roller 110 and pressure roller 112. Typical dimensions of the rollers are as follows: The coating roller 110 may have a typical diameter in the range between 180 and 300 mm, preferably about 240 mm. The pressure roller 112 may have the same dimensions. The dosing roller 14 has a diameter in the range of 100 to 200 mm, preferably about 160 mm. The dosing roller 114 is si aller than the coating roller. The width of the film is typically 160 to 180 cm. A soft knife 140 is arranged near the varnish collecting container 128 in order to clean the pressure roller 112 from excess or non-used varnish. As described above, the film 118 is advanced in the direction of arrow 142. The film 118 passes through a gap 144 between the coating roller 110 and the pressure roller 112. In one embodiment, the direction of rotation 146 of coating roller 110 and the speed of rotation are controlled such that the circumference of the coating roller 110 adjacent the film 118, i.e. the circumference of the coating roller actually transferring the varnish onto the film, is moving in the opposite direction with reference to the movement of the film. Therefore, the circumferential surface of the coating roller 110 has a velocity relative to the velocity of the film 118 in the opposite direction. That is, in a (moving) coordinate system in which the film 118 is at rest, the circumferential surface of the coating roller 110, which transfers the varnish onto the film, moves relative to the film with a definite velocity different from zero. Most preferably, in a stationary (non-moving) coordinate system (i.e. the coordinate system of the figure), the coating roller 110 has a circumferential surface that rotates counter-clockwise as indicated by arrow 146 in the figure. The dosing roller 114 rotates in a direction opposite to the direction of rotation of the coating roller 110, i.e. dosing roller 114 rotates clockwise. Typical examples of the velocities are as follows: The speed of advancement (velocity) of the film 118 in direction 142 may be in a range of 1-50 m/min, and more preferably 10 to 20 m/min. If the speed of advancement (velocity) of the film 118 is 20 m/min, the preferred rotational speed of the coating roller 10 is such that its surface velocity is 110 m/min. Generally speaking, if the speed X of the film 118 is relatively fast, e.g. over about 15 m/min, the rotational speed of the coating roller is such that its surface velocity is in a range of 30-70% of X. When the film speed is relatively fast, the drum and film velocities are in the same direction, i.e. the film is advanced in direction 142 and the coating roller rotates clockwise. If, on the other hand, the speed of advancement (velocity) of the film 118 is relatively slow, e.g. in the range of 1-5 m/min, the coating roller may rotate anti-clockwise in direction of arrow 146 with surface velocities in the range of 5-10 m/min. The velocities are adjusted in accordance with the specific requirements of the varnish coating to be applied onto the film, in particular the thickness of the varnish and the properties of the varnish. Depending on the thickness of the layer of varnish to be applied onto the film 118, the coating roller 110 may also rotate clockwise (i.e. opposite to arrow 146) with a circumferential speed smaller than the speed of advancement of the film 118 in the direction of arrow 142. For example, if the speed of advancement of film 118 in direction of arrow 142 is 10 m/min, a thicker layer may be applied by adjusting the circumferential speed of coating roller 110 in clockwise direction (opposite to arrow 146) to be between 3 m/min and 7 m/min, resulting in a corresponding lower relative speed between be circumference of the coating roller and the film. The amount of varnish applied onto the film 118 can also be controlled by how varnish 150 is fed in between the coating roller 110 and the dosing roller 114 as shown in the drawing. By adjusting the pressure between the dosing roller 114 and the coating roller 110 and/or the relative velocity between coating roller 110 and dosing roller 114, the amount of varnish applied by the coating roller 110 onto the film 118 is variably controllable. If only a very small amount of varnish shall be applied onto the film, i.e. a relatively thin varnish layer is to be applied onto the film 118, the dosing roller 114 may rotate in opposite direction as compared to the coating roller 110. This is indicated by the double-arrow 148. With the apparatus described above, layers of varnish can be applied onto the film 118 which are much thicker than possible with prior art machines, e.g. it is possible to apply a varnish layer having a thickness in the range of 120 μm to 130 μm with a constant thickness along the width and length of the film 118. A film 118 having release properties and coated with a varnish layer having a thickness in the afore-mentioned range is very suitable for applying varnish onto an object with a high degree of homogeneity of the varnish layer, especially in the area of the edges. Cracks and similar imperfections in the varnish layer are eliminated to a substantially greater degree than in the prior art. While the present invention is described in terms of applying a varnish layer, the invention's scope could include applying coating materials other than varnish. Also, as used herein, the term "velocity" is a vector quantity having both magnitude and direction. Thus, if film 118 is moving at 5 m/min in a first direction and the circumferential speed of coating roller 110 is 5 m/min in a second direction, the velocity of film 118 and coating roller 110 should be considered different.

Claims

1. Apparatus for manufacturing a film that can be used to apply varnish and colour onto an object, said apparatus comprising: a. a varnish application station for applying a layer of varnish onto a first film, said first film comprising release properties; b. a first curing station for partially curing said layer of varnish; c. a supply cylinder for supplying a second film, said second film being more flexible than said first film; d. a transfer station for transferring by release at least said layer of varnish from said first film to said second film; and e. a second curing station for further curing said layer of varnish.

2. Apparatus according to claim 1, wherein said first film comprises a colour layer.

3. Apparatus according to one of the claims 1 or 2, wherein a heating station is arranged between said varnish application station and said first curing station.

4. Apparatus according to claim 1, wherein said first film is made of polypropylene.

5. Apparatus according to claim 1, wherein said second film is made of polyolefine, polyethylene, or PVC.

6. Apparatus according to claim 1, wherein said first curing station comprises UV-sources.

7. Apparatus according to claim 1, wherein said second curing station comprises UV-sources.

8. Process of manufacturing a film that can be used to apply varnish and colour onto on object, said process comprising the steps of: a. applying a colour layer onto a first film, said first film comprising release properties; b. applying a varnish layer onto said colour layer on said first film; c. partially curing said varnish layer; d. transferring by release said varnish and colour layers from said first film onto a second film comprising release properties wherein said second film is more flexible than said first film; and e. further curing the transferred varnish layer on said second film.

9. A process according to claim 8, wherein said first film is made of polypropylene.

10. A process according to claim 8, wherein said second film is made of polyolefin, polyethylene, or PVC.

11. A process according to claim 8, wherein said partial curing is performed by UV-radiation.

12. A process according to claim 8, wherein said further curing is performed by UV-radiation.

13. A process according to claim 8, wherein said steps are carried out as a continuous process on a continuous length of film.

14. A process according to claim 8, wherein said varnish and colour layers are applied to said first and second films without the use of a release agent.

15. A process according to claim 8, wherein said first film has a surface energy of approximately 35 to 40 dynes.

16. A process according to claim 8, wherein an adhesive layer is applied to said first film prior to applying said colour layer.

17. A process according to claim 16, wherein a primer layer is applied to said adhesive layer.

18. An apparatus for applying varnish onto a film, said apparatus comprising: a. a coating roller for transferring varnish from the coating roller onto the film; b. a pressure roller arranged adjacent said coating roller; c. a means for advancing said film at a first velocity through a gap between said coating roller and said pressure roller; and d. a means for rotating said coating roller such that the circumference of the coating roller adjacent said film moves at a second velocity different to said first velocity.

19. Apparatus according to claim 18, wherein said means for advancing said film advances said film through the gap in a first direction, and said means for rotating said coating roller rotates said coating roller such that the circumference of the coating roller adjacent said film moves in a second direction opposite to said first direction.

20. Apparatus according to claim 18 or claim 19, wherein said film, before entering said gap, defines an angle (α) different from zero with a plane that is tangential to both the coating roller and the pressure roller.

21. Apparatus according to any one of claims 18 to 20, wherein said coating roller comprises an elastomeric surface.

22. Apparatus according to any one of claims 18 to 21, wherein means are provided for moving at least one of said pressure roller or coating roller in a direction parallel to a plane that is tangential to both the coating roller and the pressure roller.

23. An apparatus for applying a coating material onto a film, said apparatus comprising: a. a coating roller positioned in contact with a source of coating material; b. a pressure roller arranged adjacent said coating roller; c. a film advancing at a first velocity through a gap between said coating roller and said pressure roller; and d. wherein a circumference of said coating roller adjacent said film moves at a second velocity different to said first velocity.

24. Apparatus according to claim 23, wherein said first velocity and said second velocity produce a relative velocity between about 10 and 20 m/min.

25. Apparatus according to claim 21, wherein said elastomeric surface of said coating roller has a hardness on the Shore A scale of between approximately 30 and 80.

26. Apparatus according to claim 21, wherein said elastomeric surface comprises a rubber material.

27. Apparatus according to claim 18, wherein said coating roller and said pressure roller exert a pressure of between approximately 1 and 4 bars on said film.

28. A process for applying varnish onto a film, said process comprising the steps of: a. providing a coating roller arranged adjacent to a pressure roller; b. applying an amount of varnish to said coating roller; c. advancing a film between said coating roller and said pressure roller at a first velocity; d. rotating a circumference of said coating roller at a second velocity different from said first velocity; and e. a means for rotating said coating roller such that the circumference of the coating roller adjacent said film moves at a second velocity different to said first velocity.