Patent Application
20070017399
1. Field of the Invention
Embodiments described herein are directed to a dual heating system for generally any process where images are being heat transferred, such as processes involving decorative hot stamping foils, holographic foils, PMS color foils, silicon die impressed foils, and the like. More particularly, the embodiments are directed to a dual heating system for high speed printing of images, especially printed color images, on objects having a variety of sizes and shapes, by way of a hot stamping machine and/or a related hot stamping process or heat transfer mechanism.
2. Description of Related Art
Hot stamping machines, such as for example a Harvey roll-on deco machine, preferably a single head model HFR-100 or a double head model HFRO-200, typically contain a single heating element per head. Machines of this type are disclosed in U.S. Pat. No. 4,502,381. These machines were marketed by the Harvey Machine Co. of Nashville, Tenn. Another exemplary hot stamper is the PRECO™ automatic film transfer roll stamper machine, model KS-65. This machine was manufactured by the Preco Company of Osaka, Japan and also possesses a single heater.
The printing systems described above involve the transfer of predetermined images to objects. A commonly used system involves metal roller(s) that facilitates the transfer of images from a film to objects. The roller(s) impress the film over the surface of the object to transfer the image. Because objects that are impressed may have rounded surfaces, small imperfections that may appear in metal roller(s) do not provide a uniform image transfer. One method used to avoid this problem involves covering the metal roller(s) with a more flexible material such as silicone rubber. The flexibility of the silicone rubber coating or covering helps provide more continuous contact with the object surface and thus encourages a more uniform transfer. To further permit the transfer of the foil image, color or holographic foil on the object, heat and pressure must be applied from the roller against the film onto the object.
In such commonly used printing systems, the heating element is a part of the metal roller(s) of the respective hot stamping machine. As the number of printing transfers continue, a portion of heat is lost from the system. Therefore, the temperature of the heating element is often increased to maintain the outer surface of the rubber at a specific temperature, in order to compensate for the heat loss. However, if too much heat is generated from the heating element, adhesive between the metal roller(s) and the silicone rubber coating may separate and degrade, thereby leading to increased chances of delamination of the silicone rubber coating from the metal roller(s). As such, printing speeds are compromised because, for any number of reasons, the roller(s) cannot be readily heated beyond a certain temperature to compensate for the heat loss from the image transfer process. Consequently, although the printing system achieves its intended purpose, the speed at which printing transfers may be performed is limited by these temperature considerations.
Thus, there is a need for a manner by which to increase the printing speed without compromising the bond between the silicone rubber coating and metal roller(s).
Embodiments of the present invention provide a way in which the temperature of roller(s) in printing systems are maintained to facilitate proper image transfer, even at increased speeds. In accordance with the present invention, heat loss from image transfers in the printing system may be compensated by directly applying a secondary source of heat directly to the surface of the silicone rubber coating or covering on the outer surface of the first heater.
In one embodiment, direct application of heat to the silicone rubber coating of the first heater may be immediately preceding the image transfer to the object. In this manner, the additional heat retained in the silicone rubber coating comes in contact with, and is transferred to, the object in the subsequent image transfer. The bond between the metal roller(s) and the silicone rubber coating is left substantially undisturbed because the secondary heat source maintains the temperature so that the first heat source does not need to be substantially increased.
The additional heat provided to the first heater, through this secondary source, thereby allows for a higher number of impressions to be made per unit of time without substantial risks of delamination in the system.
A detailed description of embodiments of the invention will be made with reference to the accompanying drawings.
The present invention discloses a dual heating system and apparatus for hot-stamping machines or similar heat transfer mechanisms to achieve high-speed printing of images, such as for example printed color images, on objects having a variety of sizes and shapes, by way of a hot stamping machine and/or a related hot stamping process. The hot stamping machine may be a commercially available machine, for example a machine that is disclosed in U.S. Pat. Nos. 6,151,130 and 6,578,476, which are incorporated by reference herein.
Each object 70 is conveyed, in turn, by the conveyor 74 to a transfer position where it is supported by a positioning mechanism that positions the object 70 such that the exterior surface of the object contacts the print medium. The positioning mechanism holds the object 70 so that the contact point on the print medium is a portion on which an image to be transferred has been printed. In one embodiment, as shown in
During the printing process, the strip 42 may be advanced along by another transporter. In
The speed at which a printing system may operate depends on various factors, such as the size of the metal roller or the type of images to be transferred. In one preferred embodiment, a second, external heater 81 is located adjacent to the first heater 60. The external heater 81 allows supplementary heat to be added to the surface of the silicone rubber coating 68 of the first heater 60 such that approximately thirty impressions or more per minute may be achieved. Without external heater 81, approximately eighteen impressions per minute may be achieved. In some embodiments, the lower speed may be due, in part, to the fact that the heating element is in the center of the metal roller 62. Higher temperatures cannot generally be used, as higher temperatures tend to destroy the bond between the metal roller 62 and the silicone rubber coating 68. Thus, without the external heater 81, the speed at which heat may be transmitted from the first heater is limited.
By adding heat with the external heater 81, however, additional heat may be applied without destroying the bond between the silicone rubber coating 68 and the metal roller 62 because the heat is applied directly to the surface of the silicone rubber coating 68. The heat is substantially dissipated during the printing process, before the heat is able to reach the level where the metal roller 62 bonds with the rubber silicone coating 68. In this manner the second, external heater 81 may increase productivity by maintaining and even increasing the temperature without disturbing the bond.
After the image transfer, the object 70 is withdrawn from the image transfer position and may be placed on an exit conveyor 78. This exit conveyor may be a toothed conveyor, a walking beam, a conveyor belt, a rotary table, or any conveying means as is known in the art.
The stamping machine is provided with suitable mechanisms for conveying each object 70 in turn from the conveyor 74 to the transfer position, where it is supported by rollers 76, and for subsequently conveying the object 70, to which an image has been transferred, onto an exit conveyor 78. Conveyance of each object 70 to the transfer location is synchronized with the indexing movements of the strip 42.
All of the data for images to be printed are supplied to a formatting station 10 that performs a variety of tasks. Specifically, in the formatting station 10, each image is formatted to the desired size. In addition, data representing each image is associated with position data designating the location at which the image is to be printed, either on a print medium or directly on an object. Depending on image size, a number of images can be placed side-by-side on the printing medium, to form several parallel columns of images, as well as being distributed along the length of the medium.
After data representing a plurality of images has been formatted and associated with position data, the combined data can be then transferred to the controller of a digitally controlled color printer 20, which is capable of performing full color printing on a print medium in the form of a long web.
The printer 20 includes four print heads, each for printing black or a respective primary color in order to produce full color prints. The printer 20 is further equipped to receive an elongated print medium web 24 initially supplied to the printer 20 in the form of a roll 26. The web 24 is unwound from the roll 26 and fed through the printer 20 by a pathway that passes each print head in succession.
The image data may initially be in any commonly used graphic format, a typical example being a Post Script™ format. The data processing system associated with the printer 20 may be of a type that utilizes bit map images and may be constructed to directly receive bit map images from any one of the image sources or to convert images in other formats, such as Post Script™ formats, into bit map image files. Suitable printers and accompanying software programs may be those disclosed in U.S. Pat. No. 6,578,476 as well as other printers known in the art.
After being printed, the web 24 may be wound into a take-up roll 28 and after the entire length of the web 24 has been printed, it can be delivered, for example manually, to an image transfer station 40. Depending on the needs and capacity of the transfer station 40, the take-up roll 28 may be cut lengthwise into a plurality of strips 42. Each strip 42 carries one column of images and may be formed into a roll for delivery to the transfer station 40. The transfer station 40 also includes a source 44 of objects to which the printed images can be transferred.
Alternatively, the web 24 may be fed from the printer 20 to the image transfer station 40 without first being wound into a take-up roll. In this embodiment, it is unlikely that the web 24 will need to be cut lengthwise into the plurality of strips 42. Ink jet heads like those available from APRION may be used for “in line” printing. Such ink jet heads are capable of shooting ink onto substrates such as paper and plastic. These differ from the XEIKON™ in that the XEIKON™ process uses electrostatic particles of toner. Other methods of applying ink are also within the scope of the embodiments of the invention.
As may be seen in
The methods according to the present invention may include coating an adhesive onto the object to be printed prior to transfer of the image from the substrate to the object. Such adhesives are well known in the art. The adhesive may serve to more firmly adhere the image to the object being printed, by being placed on the area that is to be covered by the image. The amount of adhesive placed may vary depending on need or convenience. The adhesive may also be placed such that it extends beyond the image. Alternatively, the adhesive may be selectively placed so that, when printed, the image entirely covers the adhesive. The adhesive may be placed on the object by any means as in known in the art including, but not limited to, dipping, spraying, and painting.
To perform the printing and image transfer operations that involve first printing on a web then transferring the images as described above, there is provided a substrate, that is a specially constructed web 24, which is capable of being wound into a roll and receive printed images in a manner that allows subsequent transfer of those images to the peripheral surfaces of objects. For this purpose, the web 24 may be composed, as shown in
As should be evident, the print medium 24 may be fed through the printer 20 with the release coating 52 facing the print heads and may further be fed through a pathway of the hot stamping machine 46 so that the coating 52 comes in contact with the object to which a printed image is to be transferred. One material which may be employed as a substrate 50 is a 75-gauge polyester film, obtainable from many sources.
The coating 52 may be based on an acrylic polymer modified with additives to enhance release from the polyester film 50 and aid in adherence to the target surface of the object. The additives employed may include melamine or urea-formaldehyde resins, microcrystalline waxes, acetylenic diols, plasticizers, solvents, or the like. The coating 52 may be produced from a material with a solvent-based formulation or an emulsion-based formulation. The former will generally be applied in the form of a continuous film, while the latter will take the form of a discontinuous film that is converted into a continuous film as a result of coalescense of the emulsion particles under heat and pressure during the stamping process. The following are exemplary formulations for each coating type.
According to embodiments of the invention, the acrylic resin of the solvent-based composition is isobutyl methacrylate and/or butyl methacrylate polymer, and the styrene acrylic emulsion of the emulsion-based composition is an emulsion copolymer of styrene and 2-ethyl hexyl acrylate and/or butyl acrylate. The above formulas are given only by way of example; other formulations known to be suitable for use as coatings may be used.
Also within the scope of this invention is the use of a coating that has antimicrobial qualities, including antibiotic, antifungal, antiviral, and similar qualities. Since pens and similar writing instruments are often used by many different people, there is the possibility that they could transfer microbes from person to person. One possible solution to this problem is to incorporate sufficient amounts of an anti-microbial agent into the pen body. A problem with such approach, however, is that large quantities of the agent may be necessary to be effective. In the present invention, since only the outer surface of a pen is typically handled, only the outer surface is treated, e.g. by the use of a coating that contains such an antimicrobial agent.
Also within the scope of this invention is the use of a coating that has uv-protective qualities. Such a coating may be used to prevent fading and degradation on products that are exposed to ultraviolet rays, such as, for example, signage.
Either type of coating may be suitably applied to a Mylar® or other polyester substrate by, for example, a continuous web flexographic process or by other known techniques. After application, the coating may be dried under time and temperature conditions suitable for the vehicles employed.
Image data may be obtained simultaneously from a plurality of image sources. Each source may be a scanner, a computer, or the like.
According to the embodiments of the invention that involve printing first on a web and then transferring the images from the web to the objects, data from a plurality of sources, such as scanner 4 and memory 6 in
While the above description refers to particular embodiments of the present invention, it will be understood to those of ordinary skill in the art that modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover any such modifications as would fall within the true scope and spirit of the present invention.
The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive; the scope of the invention being indicated by the appended claims, rather than the foregoing description. All changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
