Patent Application
20050140768
1. Field of the Invention
The present invention relates to a durable thermal transfer image. Specifically, it relates to a subsurface imaged thermal transfer label and a method of manufacture.
2. Brief Description of Related Art
Thermal transfer printing traditionally involves variably boding ink from a thin PET carrier (ink, carrier, and release coating comprising a ribbon) to a substrate. A positive image is printed on a substrate. The PET carrier is then stripped away from the substrate, removing the ink from all areas that have not been bonded via heat and pressure. While the printed image is fairly durable, it is subject to attack from abrasion and chemicals, particularly solvents similar to the ones used to coat the ink on the PET carrier.
Traditional approaches to improving durability of the image have required a separate process to overlaminate the printed image with a protective film (usually coated with a pressure sensitive adhesive). This adds complexity to the process, and typically requires either costly equipment or manual labor. Extensive development work has been undertaken to improve the durability of the thermal transfer inks, but some chemicals (usually solvents such as MEK, xylene, toluene, etc.) are still extremely damaging to the printed image.
Chemical resistance is a common challenge in industrial labeling applications, laboratory tracking applications, and other markets. Existing solutions involve costly and unwieldy overlaminating/diecutting stations, extensive manual labor, or expensive and marginally effective ribbon ink. Durable thermal transfer printing applications typically require an expensive, resin based ribbon to achieve good levels of durability.
Many customers are unwilling to overlaminate their labels by hand by applying a separate clear label, and are not interested in the additional cost of the overlaminate film.
Thermal transfer printing traditionally involves variably boding ink from a thin PET carrier (ink, carrier, and release coating comprising a ribbon) to a substrate. A positive image is printed on a substrate. The PET carrier is then stripped away from the substrate, removing the ink from all areas that have not been bonded via heat and pressure. While the printed image is fairly durable, it is subject to attach from abrasion and chemicals, particularly solvents similar to the ones used to coat the ink on the PET carrier. There is a need for a cost effective durable label.
This invention is a new method of protecting printed images from challenging application conditions such as chemical exposure and abrasion, and is a new product construction.
This invention significantly changes the use of thermal transfer technology. The thermal transfer ribbon is imaged onto a waste medium rather than onto the target substrate. The waste media and ink is stripped away leaving the desired image on the PET carrier. The carrier, with the desired image remaining, is then laminated onto a pressure sensitive adhesive substrate, creating the finished product. The image is protected from environmental attack by the thin PET film used as the carrier for the thermal transfer ink. This method enables creation of a sub-surface printed image (with corresponding durability) without adding a secondary laminating and diecutting step, without adding the cost of a laminate film, and without the need for an expensive thermal transfer topcoated film. This invention provides a simple and low cost method for producing protected images that will readily endure abrasion and chemical attack.
This invention creates a new use of the thermal transfer ribbon both in print method and film usage, creating a protected image with minimal cost and complexity. This invention provides an inexpensive label for use in challenging conditions. Additional cost savings are realized by the use of inexpensive wax ribbons. Durable thermal transfer printing applications typically require an expensive, resin based ribbon to achieve good levels of durability.
This system for creating a PET protected image can use a less expensive wax based ribbon. This process is on-demand, increasing throughput and reducing the amount of human intervention required in creating sub-surface printed or overlaminated labels and tags. The PET carrier is also chemically coated in order to reduce friction with the printhead; these coatings can also help repel chemical attack.
Thermal transfer ribbons are currently used to create positive images on a target substrate, leaving the surface ink open to attack by abrasion and chemicals.
With the inventive process, negative images of the desired indicia are transferred to a waste substrate, leaving only the desired image on the ribbon carrier. The ribbon carrier is then laminated to a pressure sensitive adhesive label stock, creating a sub-surface printed label. The surface layer of PET protects the image from abrasion, chemical attack, and other environmental conditions that degrade standard thermal transfer images. The finished label can then be cut in some manner, such as by an automated cutter located after the laminating point. An automated cutter can be indexed via a sensor mark image created on the ribbon in the same manner as the other indicia. A cut through the liner (such as a linear slit) would allow easy removal of the liner.
Thermal transfer printing traditionally involves variably boding ink from a thin PET carrier 10 (ink, carrier, and release coating comprising a ribbon) to a substrate. A positive image is printed on a substrate. The PET carrier 10 is then stripped away from the substrate, removing the ink from all areas that have not been bonded via heat and pressure. While the printed image is fairly durable, it is subject to attack from abrasion and chemicals, particularly solvents similar to the ones used to coat the ink on the PET carrier.
The inventive method is a new method of protecting printed images from challenging application conditions such as chemical exposure and abrasion and an inventive label construction.
This invention changes the use of thermal transfer technology. The thermal transfer ribbon is imaged onto a waste medium 20 rather than onto the target substrate. The negative of the desired image on the waste medium is stripped away leaving the image on the PET carrier 10. The carrier 10, with the desired image remaining, is then laminated onto a pressure sensitive adhesive substrate, creating the finished product. The image is protected from environmental attack by the thin PET film used as the carrier for the thermal transfer ink. This method enables creation of a sub-surface printed image (with corresponding durability) without adding a secondary laminating and diecutting 70 step, without adding the cost of a laminate film, and without the need for an expensive thermal transfer topcoated film.
This system for creating a PET protected image preferably uses a less expensive wax based ribbon as the waste medium 20. This process is truly on-demand, increasing throughput and reducing the amount of human intervention required in creating sub-surface printed or overlaminated labels and tags. The PET carrier is also chemically coated in order to reduce friction with the printhead; these coatings can help repel chemical attack.
With this process, negative images of the desired indicia are transferred to a waste substrate 20, leaving only the desired image on the ribbon carrier 10. The ribbon carrier is then laminated using an adhesive 46 to a pressure sensitive adhesive 4 label stock 40, creating a sub-surface printed label. The surface layer of PET protects the image from abrasion, chemical attack, and other environmental conditions that degrade standard thermal transfer images. The finished label can then be cut in some manner, such as an automated cutter located after the laminating point. An automated cutter 70 can be indexed via a sensor mark image created on the ribbon in the same manner as the other indicia. A cut through the liner 42 (such as a linear slit) would allow easy removal of the liner 42.
Label stock 40 can be chosen based on the application. The process and construction can be used with a variety of stock such as film or paper label stocks. This method can also be used to create over-laminated tags. The label supply roll construction would be as follows: liner, adhesive, tag stock. A self-wound linerless stock could also be used to create tags; an example of the construction in this case would be one tag layer with a release coating and one adhesive layer.
An alternate embodiment would incorporate white thermal transfer ribbon ink printed in standard, positive indicia. The resulting imaged carrier could be laminated to a colored (for example, black) label stock with transparent adhesive, or a white or clear label stock with a colored adhesive. Alternate combinations of color in ribbon ink, film, or adhesive, printed in negative or positive images are also possible with this concept. The resulting imaged carrier would be a mask or stencil. The indicia would appear the color of the carrier or adhesive and be visible against the white ink background.
An alternate embodiment involves laminating the imaged ribbon carrier to transfer adhesive with no base label stock. A linerless transfer adhesive eliminates the need for the liner uptake mechanism. This would result in an extremely thin and flexible label. An opaque white transfer adhesive could be used in order to provide contrast with dark ribbon ink, or vice versa. Clear adhesive could be used if the target substrate provides contrast with the ribbon ink.
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An alternate embodiment would incorporate a two-step process, wherein one standard thermal transfer printer would image the ribbon 10 onto a waste substrate 20 and rewind the ribbon 10 onto a core. A second pass through the printer would then laminate the imaged ribbon 10 onto the label or tag stock. Placing two printers in series, processing a continuous web of ribbon, would provide another method for creating this product.
Additional functionality can be incorporated by adding components to the PET carrier such as UV absorbent chemicals.
This construction could allow security functions if the carrier is tinted with a non-carbon black pigment; an IR scanner would read the thermal transfer ink through the black carrier, and the construction would be difficult to duplicate with normal methods.
This application claims the benefit of U.S. Provisional Application 60/504 423 entitled Subsurface Imaged labels and Tags Using Thermal Transfer Ribbon Carrier as Overlaminate and Method of Manufacture, filed Sep. 18, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60504423 | Sep 2003 | US |
