WO2001014140A1

WO2001014140A1 - Pre-inked thermoplastic medium useful for forming thermal images thereon

Info

Publication number: WO2001014140A1
Application number: PCT/US2000/023215
Authority: WO
Inventors: Ravi Venkataraman; Russell Moss
Original assignee: Identity Group, Inc.
Priority date: 1999-08-24
Filing date: 2000-08-24
Publication date: 2001-03-01
Also published as: AU7331600A

Abstract

The present invention is directed to a mono-layer and multi-layer thermoplastic material which is utilized to form an image which is comprised of open-cells in the area that is designed to transfer ink and enclosed or sealed cells in the area which is designed to be impermeable to ink or other print medium. The present invention also includes mono-layer materials that are inked prior to imaging and multi-layer materials wherein at least one layer is inked prior to imaging the surface of a layer.

Description

PRE-INKED THERMOPLASTIC MEDIUM USEFUL FOR FORMING

THERMAL IMAGES THEREON

This is a continuation-in- art of co-pending United States Patent Application Serial No. 08/990,660, now United States Patent No. 5,942,312.

FIELD OF THE INVENTION

The present invention relates generally to image plates or printing plates formed from a thermoplastic medium and the manufacture and use of the same. More specifically, the present invention relates to various geometric shapes of image plates (e.g., layered sheets, cylindrical plates and image rolls) formed from an open-celled thermoplastic medium which may be used with thermal imaging techniques.

BACKGROUND OF THE INVENTION

In recent years, the field of manufacturing or producing printing plates such as rubber stamps has experienced rapid advancement. Resinous relief printing plates, planographic printing plates, and intaglio printing plates, all formed using photosensitive resins now enjoy widespread use. In addition, a number of methods are known for forming printing plates using stencil images. These methods generally involve the use of a thermal printer or a wire dot printer to form a stencil image on a sheet, which is then utilized as a printing plate. The three principal areas of stamp manufacturing focus on combinations or modifications of molding, etching, and thermal imaging. U.S. Patent No. 5,665,524, for example, describes a printing plate which is formed from an open-celled thermoplastic medium wherein the open-cells are sealed upon exposing to energy rays. SUMMARY OF THE INVENTION

The present invention is directed to the manufacture and use of image recording material (e.g., mono-layer and multi-layer printing plates, cylinders, and rolls).

One embodiment of the present invention is directed to a thermoplastic medium in the form of mono-layered or multi-layered sheets. Another embodiment is directed to a thermoplastic material in a cylinder, roll (e.g. a mono- or multi-layered sheet that is rolled up) or other useful geometric shape which is then processed via imaging processes known in the art, including thermography and photo-flash imaging to form a background image of closed cells and an image of open cells on a printing plate. Yet another embodiment of the present invention is a multi-layered thermoplastic medium which includes at least one pre-inked layer prior to forming a thermal image thereon. As described more fully in U.S. Patent No. 5,942,312, the thermoplastic medium is heated and sealed in predetermined areas and other areas of open- cells are not heated and are thereby left open so that they can transfer an ink constituent contained within the thermoplastic medium to material to be printed on. The thermal imaging process results in the formation of a background image (or non-image) of closed cells being formed on the thermoplastic medium which is substantially impermeable to the ink constituent, and an image portion. When mounted in a hand stamper, roller, printer, or other device, the thermoplastic medium effuses ink through the open cells when pressure is applied.

The multi-layer embodiment may include a thermoplastic medium as a first layer and a second layer selected from the group consisting of an adhesive layer, protective layer, imaging membrane, thermal transfer ribbon, ink reservoir layer, and combinations of these and other layers. Obviously, the term multilayer is meant to include more than one layer or a plurality of layers. In those embodiments that are pre-inked, the necessity of inking the image recording material after the image is formed reduces mess, is more time efficient, and eliminates a step in the production line. Even minimally pre-inking the image recording material allows for better "wicking" of the ink which improves the capillary action of the image recording material.

One feature of the present invention resides generally in a multi-layer image recording material comprised of a first layer and a second layer, said first layer comprised of an open-cell thermoplastic material and said second layer being positioned adjacent to said first layer. The multilayer image recording material, wherein said second layer is substantially impermeable to ink. The image recording material, wherein said second layer is a thermal transfer ribbon. The multi-layer image recording material, wherein said thermal transfer ribbon is removably attached. The multilayer image recording material, wherein said second layer is an adhesive. The multi-layer image recording material, wherein said adhesive further comprises a peal-away membrane. The multi-layer image recording material, wherein said second layer is pre-inked. The multi-layer image recording material further comprising a third layer. The multi-layer image recording material, wherein said third layer is a membrane.

Another feature of the present invention resides broadly in an image recording material comprised of an open-cell thermoplastic material, wherein said image recording material is formed in a predetermined geometric shape, said predetermined geometric shape being selected from the group consisting of a sphere, a cylinder, and a roll. The image recording material, wherein said geometric shape is a cylinder. The image recording material, wherein said cylinder is hollow. The image recording material, wherein said cylinder is comprised of a plurality of layers. The image recording material, wherein at least one of the plurality of layers is pre- inked. The image recording material, wherein one of the plurality of layers is a membrane. The image recording material, wherein one of the plurality of layers is an adhesive.

Another feature of the invention resides broadly in a thermal head printer comprised of a print head, a drive mechanism, and a roll mounting wherein said printer is adapted to receive a roll of thermoplastic medium. The thermal head printer further comprising a mounting for a thermoplastic film.

Yet another feature of the present invention resides broadly in a method of printing rolls of thermoplastic media using a thermal printer.

The present invention will be more fully appreciated with reference to the figures and the detailed specification which follows:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an isometric view of a thermoplastic material which is at least partially saturated with an ink constituent prior to forming an image thereon;

Fig. 2 is a top plan view of the pre-inked thermoplastic medium being processed by a thermal head printer;

Fig. 3 is an isometric view of the thermoplastic material which has been processed into a printing plate having an open-cell ink-effusing face area and a sealed background image thereon; Fig. 4 is a highly enlarged cross section through line 4-4 of Fig. 3 illustrating a letter of the printing plate;

Fig. 5 is an elevated perspective view of a multi-layered sheet of thermoplastic material which has been processed into a printing plate having an open-cell ink-effusing face area and a sealed background image;

Fig. 6 is an elevated perspective view of a multi-layered sheet of thermoplastic material, wherein at least one layer is removably attached to the other layers;

Fig. 7 is an elevated perspective view of a multi-layered sheet of thermoplastic material, wherein at least one membrane separates the layers;

Fig. 8 is an elevated perspective view of a rolled sheet of thermoplastic material, the sheet being at least partially saturated with an ink constituent;

Fig. 9 is an elevated perspective view of a multi-layered rolled sheet of thermoplastic material;

Fig. 10 is an elevated perspective view of an imaged roll which has been processed into a printing plate;

Fig. 11 is an elevated perspective view of a cylinder of thermoplastic material which is at least partially saturated with an ink constituent;

Fig. 12 is an elevated perspective view of a multi-layered cylinder of thermoplastic material wherein at least one layer is at least partially saturated with an ink constituent; Fig. 13 is an elevated perspective view of a hollow cylinder of thermoplastic material which has been processed into a cylindrical printing plate;

Fig. 14 is a side view, with some exterior components removed, of a thermal printer that is used to image the rolled sheet or cylindrical thermoplastic material; and

Fig. 15 is an elevated perspective view of a thermal printer that is used to image ink rolls.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In order that the invention may be described and understood more fully, the following detailed description is set forth.

The terms "energy beam" or "energy ray" as sometimes used herein refer to any ray, beam, radiation or light which is capable of supplying thermal energy to an open-celled sheet, and is preferably selected from ultraviolet rays, infrared rays, visible rays and electron rays. Preferable sources of the energy ray include flash lamps, strobe lamps, laser generators and the like. Of course, a wide variety of rays, beams, radiation, and types of light, together with their associated sources may be employed. The printing plates of the present invention may be obtained either by attaching to the open-celled sheet 30 a mask film capable of selectively intercepting the energy rays and then applying the energy rays over the mask, or may be obtained by direct thermal contact with a thermal head printer, electron beam generator, or laser beam. A pattern of image 38 and non-image 34 areas on the open-celled sheet 30 is then formed by selectively applying the thermal energy rays resulting in printing plate 40, cylindrical printing plate 42, or printing roll 44. As used in this disclosure, "thermoplastic recording material" or "thermoplastic medium" means an organic material, normally a polymer, which exhibits plasticity at some stage of manufacture and which can be shaped by application of heat and/or pressure. The "thermoplastic medium" is comprised of "open-celled" material. The thermoplastic material itself is preferably a polyethylene, and more preferably, an ethylene-olefin copolymer. However, polyurethanes, polyacetals, polystyrenes and polyamides may also be used. The levels of saturation of the thermoplastic medium 30 and the amount of ink constituent held within the thermoplastic medium may vary depending on, among other things, the specific density of the ink constituent 36, the type and density of polymer used, and the degree of porosity in the thermoplastic sheet.

As used herein, the thermoplastic recording material or "image recording material" could be any shape, size, or dimension. For example, the image recording material may be "sheet-Uke" in form to be presented to an imaging process similar to that of a sheet of paper. The image recording material may also exist as a continuous roll 44 that can be presented to the imaging process device. The image recording material may be sized prior to imaging or following the imaging process and can either be presented for imaging as a single unit 30 or as a subunit of a larger stock. For example, in one embodiment of the present invention, the image recording material is generally a cylindrically-shaped thermoplastic material (e.g., as shown in Figs. 11-13), whose surface can be effected by the application of heat and/or pressure to form an image thereon. The cylinders can be mono-layer or multi-layered.

The image recording material can be either homogeneous or heterogeneous in its construction, such that layers 62 of similar or differing material may be combined to form the image recording material. In the layered embodiments 60, 70, 90, less than all of the layers can contain an ink constituent prior to imaging, or alternatively none of the layers are pre-inked prior to imaging.

As used herein, "membrane" includes impermeable, as well as semipermeable and permeable membranes that are reactive, for example, to force, pressure, temperature, energy, moisture, fight, or chemical stimulus, or any combination of these and other factors. The membrane 48 may be an adhesive coating, or a combination of adhesive and non-adhesive layers. "Membrane" may include removable protective layers that are on the exterior surface of the image recording material.

The thermoplastic material 30 is preferably open-celled. "Open- celled" refers to a continuous cell structure where the cells communicate directly or indirectly with other cells in the thermoplastic material 30, whereby liquid can pass from cell to cell. "Open-cell" may be used herein to interchangeably refer to the characteristic of the thermoplastic medium 30 and to the fact that the cells 32 of the thermoplastic medium 30 have interstitial spaces which may be filled with an ink constituent. Accordingly, "open-celled" further refers to microporous and porous structures within the thermoplastic medium which are sufficiently sized to store and/or transfer ink and which communicate either directly or indirectly with each other and therefore which may function to transfer ink 36 to the material to be printed on. "Closing", "solidification", "melting", "waxing", "sealing", "thermalizing" or "hardening" of the surface of the thermoplastic medium are all terms that may be used herein to refer to the substantial elimination of open-cells 32 in a specific area which renders that portion of the thermoplastic medium 30 impermeable to an ink constituent. Generally, the thermoplastic medium 30 has a predetermined shape, length, width, thickness and density. The surface of the thermoplastic medium 30 is melted and sealed at least at the surface layer, and more preferably, melted sufficiently to form the sealed or closed portion 34 while retaining the open-cell image 38. Not sealing the entire space behind the open-cells 32 allows the open-cells 32 behind the sealed cells to be repositories of printing fluid. The background portion 34 corresponds to the non-image portion of the original image and substantially prevents transfer of printing material 36 through the thermoplastic medium in these areas. The areas of the thermoplastic medium 30 which are not in contact with the heating elements (i.e., laser or modulated thermal energy) are generally formed as a mirror image of the image to be printed on a print material, and as a mirror image of the image viewed on a screen. This results in the proper translation from screen to stamp to paper. The image portion 38 of the printing plate 40, the cylindrical printing plate 42, or the printing roll 44 is comprised of open-cells 32 which function as an area of ink 36 effusion. Therefore, when placed in contact with a material to be printed on, an ink constituent 36 or similar material is transferred from the open-cells 32 of the image 38 to the paper in the desired pattern. Thus, when the thermoplastic material 30 is mounted as a printing plate 40 or cylinder 42 in, for instance, a hand stamper or roller, the open- cell 32 portions of the thermoplastic medium 30 are able to transfer ink to the material to be printed on, i.e., paper, in those regions 38 which do not contain a layer of sealed cells 34. Conversely, the sealed portions 34 prevent the transfer of ink.

The particular device or procedure utilized to seal the open-cell thermoplastic material can be any of those known in the art. One type is direct thermal imaging via a thermal head printer 20 as shown in Fig. 2. The thermal imaging prints a background image 34 on the thermoplastic material 30 by heating with image-wise modulated energy the thermoplastic material 30. This allows an image 38 to be formed of open-cells 32 and a non- image or background 34 to be formed of closed cells. A microprocessor based graphics system may be used to generate the image. A "line" of an image seen on the view screen of the microprocessor normally results in this "line" being formed as a mirror image of the fine viewed on the screen, and the mirror image is formed of open-cells 32 on the printing plate 40 or cylinder. Similarly those portions of the graphics which are non-images (i.e., white on a black and white monitor) result in the non-image portions 34 being formed of closed or sealed cells.

One type of thermal imaging device 80 that can be used for cylindrical image recording material, appears in Fig. 14. This device uses a thermal head printer 20 similar to that shown in Fig. 2. In those embodiments employing cylindrical thermoplastic imaging material (e.g., Figs. 11-13), the image recording material to be printed would be mounted in the position of the interior spool 84 wherein the image recording material would rotate relative to the thermal imaging head 20, thereby forming a thermal image 38 onto the cylinder. To protect the print head and improve image sharpness, thermoplastic film unwinds from the external spool 82, travels across the thermal printing head, and rewinds onto a finished spool, if desired.

The methods of manufacturing, making, using or processing the thermoplastic medium of the present invention are described more specifically below. More specifically, a method described herein relates to forming a pattern on a pre-inked open-cell thermoplastic material 30 to form an imaged material (e.g., a printing plate 40, cylindrical printing plate 42 or printing roll 44). In general terms the methods are comprised of generating a signal corresponding to the pattern to be formed on the open-cell thermoplastic foam 30, receiving the signal corresponding to the pattern (image 38 and non-image 34) to be formed on the open-cell thermoplastic foam 30, and driving a thermal image device (i.e., laser, thermal print head or photo flash system), to heat the pre-inked open-cell thermoplastic foam 30, thereby sealing at least a surface layer of open-cells 32 in a region which correspond to the background 34 of the entire pattern formed on the open-cell printing plate. Preferably, the printing plate 40 or cylinder 42, is formed from a sheet or cylinder of pre-inked thermoplastic foam 30 and the unheated open-cell portion 38 is formed as a raised relief image. To accomplish this end, it is more preferable to seal at least several layers of open-cells 32 so that the background portion 34 is formed of at least several layers of closed cells and depressed, thereby resulting in the image portion 38 being formed as a raised or relief image of open-cells. Although the term "layer" as used herein refers to a single layer of open-cells, "several layers" refers to more than just a surface layer of cells. When several layers are sealed, the background portion 34 is not on the same plane as the print surface open- cells 32 of image 38. Fig. 4 illustrates this relief concept in a somewhat exaggerated manner.

Thermoplastic medium 30 can be formed from a number of thermoplastic resins, including by way of example, and not limitation, polyethylene, polyolefins, polyacytals, polyurethanes, polystyrene, and polyamide. It has been found that an ethylene-olefin copolymer is particularly suitable for the present invention. It is preferable that the thermoplastic medium 30 be "open-celled" prior to the application of heat. In being "open-celled" the thermoplastic medium 30 has interstitial space which may be filled with an ink constituent 36. Many techniques are known for forming open-celled thermoplastic material, including blowing air through the system while the material is forming or using a salt-washout technique. The open-cells 32, for example those illustrated in Figs. 1-4, appear as large "pores". The thermoplastic medium 30 which has "open-cells" 32 is designed to allow an ink constituent 36 to be at least temporarily stored in the thermoplastic medium 30 and transferred to an absorbent material (not shown) at a later time. "Open-cell" includes microporous structures which are sufficiently sized to store or transfer ink 36, and cells 32 which are able to communicate directly with other cells 32 or pockets in the thermoplastic foam 30. This allows ink constituent 36 or an emulsified resin to pass from cell 32 to cell 32. The ink constituent 36 is illustrated as black particles for the sake of clarity. Practically any ink constituent may be used with the present invention. For example, a black ink comprised of 83% 2-ethyl-l, 3- hexandiol, 8.5% solvent black 7 dye, and 8.5% solvent black 5 dye may be used. Selection of an appropriate ink constituent 36 and the amount utilized requires analysis of a number of factors. For instance, a type of ink 36 which conducts heat from the area which is to be melted (background portion 34) to the image forming portion 32 is undesirable. As the ink 36 leaves the open- cells of the print plate 40, an ink image is formed on ink absorbing paper. When thermal energy is apphed to the surface of the thermoplastic foam 30, the surface of the thermoplastic foam 30 melts or solidifies resulting in melted portion 34 of printing plate 40 which eliminates communication between the ink constituent 36 behind the melted portion 34 of the formed print plate 40 and the print medium. Since portion 34 is substantially impermeable to liquid transfer, these areas are suitable in functioning as non-image areas which are not designed to transfer ink 36. Melting or solidifying a portion of the print face of the thermoplastic medium 30 results in a background image 34 of the thermoplastic foam, substantially preventing communication between the underlying open-cells 32 containing ink 36 and the paper. Within the thermoplastic foam 30, the ink 36 moves from one cell 32 to the next and may in fact take a very circuitous route to the material to be printed on.

Referring in particular to Fig. 3 and Fig. 4, the printing plate 40 discussed herein as formed by a thermal imaging process which seals open- cells 32 is illustrated. The surface of the thermoplastic foam 30, which is in contact with the energy rays, is melted or solidified resulting in a melting of the open-cells 32 of the thermoplastic foam 30 to form a non-image 34 which is impermeable to the transfer of liquid or resin while the image portion 38 (lettering) maintains an open-cell 32 structure which permits the transfer of liquid or resin 36 from the printing plate 40 to the material to be printed on. The portions 34 of the thermoplastic foam 30 which are heated and melted are on a lower plane than the open-celled image forming portion 38. Thus the image 38 is formed as a relief of open-cells (32). Fig. 1 illustrates the embodiment of an ink constituent or other suitable ink material being infused into the open-cells 32 of the thermoplastic foam 30 prior to the desired image being formed on thermoplastic sheet 30. Ink can fill the entire open-celled structure of the thermoplastic medium 30 except in those melted or solidified surface portion 34 and the ink 36 can be transferred to the paper or print medium except in those areas 34 that are melted and sealed.

An image forming process is illustrated in Fig. 2 where the thermoplastic foam 30 is placed on a receiving bed 50 of a thermal head printer 20 and a thermal head (not shown but located below the thermoplastic foam 30) is driven to form the desired image (sealed non-image portion 34 and open-celled image portion 38) on printing plate 40. The imagewise modulated energy is apphed directly to the surface of the thermoplastic foam 30. If the thermoplastic foam or sheet 30 is pre-inked it is preferable that the ink constituent 36 contained within the thermoplastic foam 30 is at a predetermined concentration, whereby the ink constituent 36 does not egress out of the foam 30 without force or pressure being applied to the foam 30. It is preferable that the force exerted on the thermoplastic foam 30 as it is being processed does not cause ink 36 to egress out of the foam 30. This is beneficial in that, when the foam 30 is being processed through, for example, a thermal head printer 20 as shown in Fig. 2, the foam 30 does not release the ink constituent 36 prior to the image being formed thereon. Therefore, it is preferable that the predetermined concentration of the ink constituent 36 be at a lower level than that necessary to completely saturate the thermoplastic recording material 30. The optimal saturation level depends on a number of factors, including, but not limited to, type, density, viscosity, surface tension, etc. of the ink, and type and density of thermoplastic recording material 30. Although specific examples are provided herein, it is to be understood that the present invention is not to be so limited. The thermoplastic sheet 30 is preferably pre-inked within the saturation levels for optimum conditions, such as minimal mess (egress of ink 36) on the printer and sharp, clear, clean images being formed on printing plate 40, cylindrical printing plate 42 or printing roll 44.

The printing plate 40 which is formed in accordance with the present invention is formed by placing a thermoplastic material 30 in sheet form in contact with an ink constituent 36 to thereby form a partially saturated thermoplastic medium 30, wherein the thermoplastic medium 30 is at least partially saturated with ink constituent 36. After the step of placing and soaking the thermoplastic material in an ink constituent 36, thermal energy is applied to selected areas of the partially saturated thermoplastic medium 30 to thereby form a background image 34 on said printing plate 40.

Layered printing plates (e.g., Figs. 5-7), layered cylindrical printing plate (e.g., Fig. 12), and layered printing roll (e.g., Fig. 9) are formed in accord with the present invention by placing at least one layer of thermoplastic material 30 in contact with an ink constituent 36 to thereby form a partially saturated thermoplastic medium. Subsequent to placing at least one layer of thermoplastic material 30 in contact with ink constituent 36, one of three steps can follow. First, if the partially saturated layer and the layer to be imaged have been assembled prior to saturation, then the layered thermoplastic medium can be imaged, wherein thermal energy is applied to selected areas of the layer to be imaged, thereby forming a background image. Second, if the layers are disarticulated, the layer to be imaged can be imaged and then attached to the partially saturated layer, or the layers can be assembled and then the layer to be imaged can be imaged. Third, the partially saturated layer can itself be imaged, either prior to or following assembly with at least one other layer.

In these methods, the image 38 is formed of open-cells 32 which are in contrast to the sealed background layer 34. The partially saturated thermoplastic medium is comprised of a thermoplastic foam 30 which is subject to absorbing ink and is saturated less than 100%, preferably in the range of about 50% to about 80%, and even more preferably in the range of about 70% to about 80% saturation with said ink constituent 36.

The present invention may also be characterized as a method of forming a pattern (image 38 and non-image 34) on a shaped thermoplastic material 30. The first step normally includes the steps of designing an image to be reproduced by the imaged material. Normally, the design step is performed on a conventional computer, using any suitable computer software program capable of yielding the selected results. Normally, the imaging data is routed to a controller in much the same way that the information would be communicated to a printer. Thus, the method specifically includes creating an image associated with a set of electronic data, converting the electronic data into a mirror image of said data and forming said mirror image on a surface of the thermoplastic material 30. The formation of the image on the thermoplastic material 30 can occur via a number of standard printing processes which close cells on the thermoplastic foam 30 to form background image 34. These include, but are not limited to, photoflash imaging, engraving, laser etching.

The orientation of the multiple layers depends on the orientation of the thermal print head. In Fig. 9, which can be better understood if viewed in context with Fig. 14, a thermal transfer ribbon 201 is interposed between the thermal print head 20 and the themoplastic medium. The thermal transfer ribbon 201 prevents undesirable effusion of ink onto the print head 20. Of course the thermal transfer ribbon 201 could be placed on both sides of the thermoplastic foam. Thermal transfer ribbon 201 may be those known in the art which are suitable to the present invention and include, for example, those available from Markem TTR, Part No. 81716002135 MJ, 716 Black 00, Lot No. 5980A6, 135MMX300M, The thermal transfer ribbon 201 may be placed in between the thermoplastic foam 26 and the thermal head and/or printer head and/or printer body to prevent ink from coming in contact with these items. The thermal transfer ribbon 201 keeps the print head free of ink and, if desired, transfers a layer of wax to the foam to aid in sealing background. Not only does the thermal transfer ribbon 201 aid in sealing the background, it also results in a sharper and cleaner break between the background image and image portion 38.

The present invention is also directed to a method of forming a pattern on a printing plate 40, cylindrical printing plate or printing roll, wherein the pattern consists of an open-celled portion 32 filled with ink constituent 36 and closed or sealed portion 34. A signal which corresponds to the pattern to be formed on the printing plate 40 is normally generated with a computer graphic program or other microprocessor system which sends information to a driver circuit which in turn communicates with the print device. Once the signal is received, the corresponding pattern (image 38 and background image 34) is formed on the printing plate 40. It is preferable that the open-cell image portion 38 is formed as a relief pattern and therefore does not exist on the same plane as the melted portion or closed cells 34 which form the background image on the printing plate 40.

In a preferred embodiment, the thermal printer of the present invention is capable of printing on cylindrical or substantially cyhndrical rolls of thermoplastic media, preferably thermoplastic foam. The printer is generally comprised of a housing or frame that incorporates the separate mechanical apparati of the printer in the desired arrangement. The printer includes a print head for imparting thermal energy to form images on the thermoplastic medium. The print head is preferably attached to a linear slide that applies pressure to the print head in the print position. A linear slide is preferred to a cam. The pressure on the print head is such that the print head can be adapted for printing on foam that is not exactly cyhndrical in shape. If the pressure is variable, then the print head can adapt to follow the contours of the roll being printed. The print head is preferably attached to a the linear slide so that it is at a slight angle, preferably 10 degrees, from horizontal.

In one embodiment, in print position, the print head is in direct thermal contact with the portions of the thermoplastic medium to be printed. The expression "direct thermal contact" as used herein with regard to the formation of an image on a thermoplastic medium is very similar to "direct thermography" as known in the related art, except that the recording material is an open-celled thermoplastic material and the chemical or physical change is the closing or sealing of the open-cells to form a background image. When the thermal head is placed in "direct" contact with the thermoplastic medium, the thermal head heats and induces a chemical or physical change in the desired portions of the thermoplastic medium. For printing, a shaft holds the roll to be printed in place beneath the printer head. In one embodiment, the roll is manually placed on the shaft for printing and then removed after printing. The shaft rotates at the desired speed during printing and turns the roll so that the roll may be printed where desired. The rotation of the shaft is effected by a gear in mechanical contact with a drive gear that is turned by a stepper motor. Alternatively, for example, the cylinder may be rotated by a drive plate in cooperation with a drive gear and drive roller assembly. A thermal printer could be designed to handle rolls of any size; however, rolls that are 4 inches or less in width are preferred because print heads of 4 inches are typically available.

In a preferred embodiment, a thermal film is placed between the print head and the roll during printing to protect the printer head. The thermal film may also be coated with wax on the side adjacent to the roll in order to improve the image quality or seal on the cylinder. The thermal film is preferably fed between the printer head and the cyhnder from a spool that is mounted on the thermal printer housing. The used thermal film may be taken up on a separate spool or may be cut off between print jobs.

In a preferred embodiment of the present invention, the printing device for printing on open-cell thermoplastic foam includes a signal interface assembly for receiving a signal corresponding to an image to be formed on the open-cell thermoplastic foam and a thermal print head driven by the signal. The thermal print head prints a background image on the thermoplastic foam by heating the thermoplastic foam and sealing at least a surface layer of the open-cell thermoplastic foam. This allows an image to be formed of open cells and a non-image or background to be formed of closed cells. Also in a preferred embodiment, the thermal printer is operated through a computer that runs software for selection and downloading of images to the printer head. The signal interface assembly is comprised of a communication port, preferably both a parallel port and a serial port which are adapted to receive information, preferably from a computer graphics software. One of the more advantageous aspects of the present invention is that essentially any software can be used to generate the image to be formed on the thermoplastic medium. If the software can interface with a standard printer (i.e. laser or dot matrix), it can be utilized with the present invention. A "line" of an image seen on the view screen normally results in this "line" being formed as a mirror image of the fine, and the mirror image is formed of open cells on the roll. Similarly those portions of the graphics which are non-images (i.e. white on a black and white monitor) result in the non-image formed of closed cells. In a preferred embodiment, a control cabinet is provided for operation of the thermal head printer.

Although the invention has been described in terms of particular embodiments in an application, one of ordinary skill in the art, in hght of this teaching, can generate additional embodiments and modifications without departing from the spirit of, or exceeding the scope of, the claimed invention. Accordingly it is to be understood that the drawings and the descriptions herein are proffered by way of example only to facilitate comprehension of the invention and should not be construed to hmit the scope thereof.

Claims

WHAT IS CLAIMED IS:

1. A multi-layer image recording material comprised of a first layer and a second layer, said first layer comprised of an open-cell thermoplastic material and said second layer being positioned adjacent to said first layer.

2. The multi-layer image recording material of claim 1, wherein said second layer is substantially impermeable to ink.

3. The image recording material of claim 2, wherein said second layer is a thermal transfer ribbon.

4. The multi-layer image recording material of claim 3, wherein said thermal transfer ribbon is removably attached.

5. The multi-layer image recording material of claim 2, wherein said second layer is an adhesive.

6. The multi-layer image recording material of claim 5, wherein said adhesive further comprises a peal-away membrane.

7. The multi-layer image recording material of claim 1, wherein said second layer is pre-inked.

8. The multi-layer image recording material of claim 7 further comprising a third layer.

9. The multi-layer image recording material of claim 8, wherein said third layer is a membrane.

10. An image recording material comprised of an open-cell thermoplastic material, wherein said image recording material is formed in a predetermined geometric shape, said predetermined geometric shape being selected from the group consisting of a sphere, a cyhnder, and a roll.

11. The image recording material of claim 10, wherein said geometric shape is a cylinder.

12. The image recording material of claim 11, wherein said cylinder is hollow.

13. The image recording material of claim 11, wherein said cylinder is comprised of a plurality of layers.

14. The image recording material of claim 13, wherein at least one of the plurality of layers is pre-inked.

15. The image recording material of claim 13, wherein one of the plurality of layers is a membrane.

16. The image recording material of claim 13, wherein one of the plurality of layers is an adhesive.