Abstract:
A system for printing adhesives immerses a wire in a reservoir of adhesive for a period of time sufficient to allow the wire to be coated with the adhesive. The system places the coated wire in close proximity to a designated medium onto which the adhesive will be applied and directs a stream of gas to contact the coated wire and cause at least some of the adhesive on the wire to be deposited onto the designated medium. Two-part ink systems include a fluid and a second material that is microencapsulated in the fluid, a second material that exists as a microemulsion in the fluid, and two fluids that are mixed or combined upon jetting and that react on the print medium.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is related and claims priority to U.S. Provisional Patent Application Ser. Nos. 60/886417 and 60/886338, both of which were filed Jan. 24, 2007 and are incorporated herein by reference as if fully set forth. 
     
    
     BACKGROUND 
       [0002]    One known printer technology includes a print head that (1) immerses a wire in a reservoir of pigmented liquid material (e.g., ink) for a period of time sufficient to allow the wire to be coated with ink, (2) places the coated wire in close proximity to a print medium, and (3) directs a stream of air to contact the coated wire and thereby causes at least some of the ink on the wire to be deposited onto the print medium. The speed of the wire, the proximity of the wire to the print medium, and the force of the air stream may be digitally controlled by a processor, controller, microprocessor, or other computing device to ensure that a desired image resolution is achieved. By forming a print head with multiple wires; multiple, differently colored ink reservoirs; and multiple air streams, and by controlling and coordinating the metering of the ink and the position of the print head in relation to the print medium, a digital image can be created on a large-sized print medium. U.S. Pat. Nos. 5,944,893; 5,972,111; 6,089,160; 6,090,445; 6,190,454; 6,319,555; 6,398,869; and 6,786,971, all of which are incorporated herein by reference as if fully set forth, describe this printer technology in greater detail. 
         [0003]      FIG. 1  is a perspective view of one embodiment of the above-identified prior art single color ink injector, generally indicated at  10 , for depositing paint, ink, dye, or other liquid pigmented material that could be used for painting or printing onto a print medium to which a motor  14  is attached. A pulley  13  having a circumscribing groove  38  defined therein is secured to a shaft  15  of motor  14 . An elongate frame member  32  depends from and is secured to a plate  12  and extends into a reservoir of ink  24 . A rotatable or stationary guide  34  is attached to a distal end  37  of elongate frame member  32 . Guide  34  is illustrated as a cylindrical, non-rotatable member having a groove  40  circumscribing guide  34  in which a wire cable  36 , can slide during rotation of wheel  13 . Wire cable  36  is described in greater detail in the above-identified patents. Wire cable  36  is disposed in groove  38  circumscribing the wheel  13  and in groove  40  circumscribing guide  34 . 
         [0004]    An elongate reservoir retaining member  16  is attached to plate  12  and includes a flange  18  defining a notch  20  between the flange  18  and elongate reservoir retaining member  16 . Notch  20  is configured to receive a top lip  22  of ink reservoir  24 . A bottom plate  26  is secured to a distal end  28  of elongate reservoir retaining member  16  with a threaded nut  31  that is threaded onto a threaded shaft  33 . Threaded shaft  33  is secured to distal end  28  of elongate reservoir retaining member  16 . Bottom plate  26  abuts against the bottom  30  of the ink reservoir  24  and holds it between flange  18  and bottom plate  26 . 
         [0005]    An air supply hose  42  is secured to a nozzle body  44  and supplies air through a nozzle orifice  46  that is aimed at a portion of cable  36 . A cable guide  48  defining a longitudinal slot  50  is positioned proximate nozzle orifice  46 . Cable  36  rides within slot  50  and is thus held in relative position to nozzle orifice  46  so that air passing therethrough does not substantially move cable  36  from in front of nozzle orifice  46  or cause cable  36  to substantially vibrate. 
         [0006]    Rotation of shaft  15  is controlled by a controller, generally indicated at  57 , comprising circuitry  54  in a module  56  that receives signals from a signal generating device  52 , such as a personal computer employing a microprocessor or other devices that can supply discrete signals to instruct selective rotation of the shaft  15  of the motor. Circuitry  54  receives one or more signals from generating device  52  and rotates shaft  15  of the motor according to the signals. 
         [0007]    In operation, ink contained in reservoir  24  is picked up by cable  36  and advanced by rotation of wheel  13 , indicated by the arrow, in front of nozzle orifice  46 . Air that is blown through nozzle orifice  46  disperses or pulls ink from cable  36  toward the print medium. Depending on the viscosity of the ink, the cross-sectional diameter of cable  36 , and the diameter of wheel  13 , a relatively precise amount of ink can be deposited on print medium. Such an apparatus may produce images having a resolution of approximately 50 dpi or better. The ink is dispersed onto a substrate  58 , as illustrated in  FIG. 2 . 
       SUMMARY 
       [0008]    Embodiments consistent with the present invention are directed to an improved method of an apparatus for applying adhesives. 
         [0009]    An improved adhesive applicator or fluid delivery system (1) immerses a wire in a reservoir of adhesive for a period of time sufficient to allow the wire to be coated with the adhesive, (2) places the coated wire in close proximity to a designated medium onto which the adhesive will be applied, and (3) directs a stream of gas to contact the coated wire and to thereby cause at least some of the adhesive on the wire to be deposited onto the designated medium. The speed of the wire and the force of the air stream may be digitally controlled by a processor, controller, microprocessor, or other computing device to ensure that a desired image resolution is achieved. Because the fluid delivery system is free of most of the mechanical limitations of traditional ink jet print heads, the system is compatible with adhesive application. When compared to the traditional coating operations for adhesives, the fluid delivery system allows controlled delivery, both in terms of location on the print medium and drop size (and thus coat weight). The system thus allows for greater positional and coat weight control of adhesives on the print medium or substrate, which is especially useful where precise control is desired. 
         [0010]    One embodiment of the adhesive applicator includes a motor having a rotatable shaft, a wheel rotatable by the shaft of the motor, and an idler. A cable disposed around at least a portion of the wheel and a portion of the idler is advanceable by the wheel. The cable has a quantity of adhesive coated onto at least a portion of it. The cable is placed in close proximity to at least one fluid nozzle positioned and oriented for directing a jet of fluid toward the cable to remove an amount of the adhesive from the cable and direct the amount toward the medium onto which adhesive application is desired. 
         [0011]    One method of applying adhesive to a desired medium involves coating at least a portion of an exterior surface of a cable with an adhesive and then placing the coated portion of the cable in close proximity to the designated medium. An air stream is then directed at the portion of the cable coated with the adhesive such that a metered amount of the adhesive is removed from the exterior surface of the cable and is deposited onto the designated medium. 
         [0012]    The above-described print head is able to print a wide variety of materials because of its construction. Specifically, it lacks a nozzle through which the material to be printed must pass. Consequently, materials that could heretofore not be printed with a single print head in an ink jet printer can now be printed in this manner. 
         [0013]    Embodiments consistent with the present invention are also directed to printing two-part ink systems using the printer described above. 
         [0014]    One exemplary two-part ink system includes a fluid and a second material that is microencapsulated in the fluid material. Another exemplary two-part ink system includes a fluid and a second material that exists as a microemulsion in the fluid material. Another exemplary two-part ink system has two fluids that are mixed or combined upon jetting and that react on the print medium. Yet another exemplary two-part ink system includes a class of inks that are combined together before addition to the ink reservoir. Preferred two-part inks have a viscosity that is between about 200 cP and 2000 cP. These inks include, but are not limited to, urethanes, epoxies, reactive-crosslinked, and catalyzed systems. 
         [0015]    One embodiment of a method involves coating at least a portion of an exterior surface of a cable with the two-part ink system and directing an air stream at the portion of the cable coated with the ink system. The force of air in the air stream causes a metered amount of the ink system to be removed from the exterior surface of the cable and to be deposited onto a print medium that is placed in close proximity to the cable. Advancement of the cable through the air stream is electronically controlled. 
         [0016]    One embodiment of an apparatus for digitally printing a high resolution image on a print medium includes a support structure, a carriage associated with and movable in at least one direction relative to the support structure, and a plurality of paint injectors secured to the carriage. Each of the paint injectors includes a motor having a rotatable shaft, a wheel rotatable by the shaft, an idler, and an elongate segment disposed around at least a portion of the wheel and a portion of the idler. The elongate segment is advanceable by the wheel and has a quantity of fluid material coated onto at least a portion of it. The fluid material is a two-part ink system. The paint injectors also each include at least one fluid nozzle positioned and oriented for directing a jet of fluid toward at least a portion of the elongate segment to remove an amount of the fluid material from the elongate segment and direct the amount toward a surface of a print medium. A controller that is electronically connected to each motor controls the rotation of each wheel and controls the position of the carriage relative to the support structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings, 
           [0018]      FIG. 1  is a perspective view of one embodiment of a fluid delivery system or printer; 
           [0019]      FIG. 2  is a side view of the fluid delivery system of  FIG. 1 ; and 
           [0020]      FIG. 3  is a diagram of a system to use the printer to print materials onto a substrate. 
       
    
    
     DETAILED DESCRIPTION  
     Printing Adhesives 
       [0021]    In operation, adhesive contained in reservoir  24  is picked up by wire cable  36  and advanced by rotation of wheel  13 , indicated by the arrow, in front of nozzle orifice  46 . Air that is blown through nozzle orifice  46  disperses or pulls the adhesive from cable  36  toward the designated medium onto which adhesive application is desired. Depending on the viscosity of the adhesive in the reservoir, the cross-sectional diameter of cable  36 , and the diameter of wheel  13 , a relatively precise amount of adhesive can be dispensed. Further, because the adhesive to be dispensed does not pass through a nozzle, the percent solid of the adhesive can be greater than the prior art adhesive applicators permitted. 
         [0022]    Exemplary adhesives that can be used in the adhesive applicator of the present invention include, but are not limited to, those in the following: U.S. Pat. Nos. 6,982,107; 6,946,177; 6,927,315; 6,911,243; 6,903,151; 6,887,917; 6,861,139; 6,855,386; 6,838,150; 6,835,271; 6,832,445; 6,777,080; 6,777,079; 6,767,935; 756,098; and 6,753,379. Preferred adhesives have a viscosity that is between about 200 cP and 2000 cP. These adhesives can be used in a wide variety of applications, including, but not limited to, consumer and office goods such as Post-it® Notes and related products; commercial graphics applications, such as billboards; traffic safety applications, such as signage and road markers; automotive applications; industrial applications, such as sandpaper; and medical applications, such as dental products. 
         [0023]    The adhesive applicator of the present invention is based on printer technology that is described in U.S. Pat. Nos. 5,944,893; 5,972,111; 6,089,160; 6,090,445; 6,190,454; 6,319,555; 6,398,869; and 6,786,971, all of which are incorporated herein by reference as if fully set forth. 
       Two-Part Ink Systems 
       [0024]    The printer described above can be used to implement two-part ink systems. 
         [0025]    One exemplary two-part ink system includes a fluid and a second material that is microencapsulated in the fluid material. The two materials can be designed to react with one another but would be prevented from doing so because of the physical barrier that the microencapsulation provides. When the two-part ink system is directed toward the print medium by force of the air stream, the momentum imparted is sufficient to burst the microbubbles and cause the fluids to mix or react. Alternatively, where the momentum is insufficient to burst the microbubbles, the force of the drop of ink colliding with the print medium will cause the microbubbles to burst and for the two materials in the two-part ink system to react or mix. 
         [0026]    A second exemplary two-part ink system includes a fluid and a second material that exists as a microemulsion in the fluid material. The two materials could be designed to react with one another but would be prevented from doing so because of the physical barrier that the microemulsion provides. 
         [0027]    A third exemplary two-part ink system includes two fluids that are mixed or combined upon jetting and that react on the print medium. This implementation could be effected, for example, by having two separate heads, each of which jets one of the two fluids such that they react or mix upon contact on the print medium. Alternatively, this implementation could be effected, for example, by mixing or combining the two fluids at the point of spraying. 
         [0028]    A fourth exemplary two-part ink system includes two components or inks that are combined together before addition to the ink reservoir and thus before jetting. The two components are designed to be mixed together for optimal properties of the ink after application. These two-part ink systems have a viscosity that is between about 200 cP and 2000 cP and cannot be printed through existing ink jet systems. 
         [0029]    As used herein, the term “ink” is meant to include any pigmented material, including, but not limited to, inks, dyes, paints, or other similarly pigmented liquids. While a wide variety of two-part ink systems could be used, one preferred class of two-part ink systems is epoxy-based systems. 
         [0030]    As used herein, the term “print medium” is meant to include any print medium known in the art, including but not limited to paper, plastic, synthetic paper, metal foil, vinyl, and films, and variations thereof. 
         [0031]    As used herein, the term “cable” is meant to include the use of a wire, a cable formed of multiple wires, a rod, a saw tooth wheel, or variations thereof. 
       Multi-Color Printing 
       [0032]    The printer described above can be used to generate digitally non-impact printed samples, potentially multi-colored, on the following materials: diaper fasteners; hooks; macro-closures; films; nonwovens; laminates; elastics; and superabsorbents. Also, it can be used to print on those materials using, for example, the following: adhesives; cohesives; coatings; lotions; skin care compositions; and absorbent compositions. 
         [0033]    The non-impact digital printing can provide an improved overall cost, speed, quality, and flexibility. For elastics it provides cost effective stretch with elastomeric materials disposed only in specific areas and in specific amounts of printed ink with a large degree of flexibility in design patterns without investing in custom equipment such as rolls or dies for each new design or pattern needed for tailorability, aesthetics, and customization. 
         [0034]    Customization, differentiation and performance enhancement via color, patterns, shapes, or combinations thereof is considered important for certain products. For example, a visual indication of a fit and status of a diaper is also an ever-growing need and trend. Current technologies do not allow for cost effective means of achieving these needs. For example, changing colors in an extrusion process can negatively impact yields, resulting in increased manufacturing costs. Providing multiple colored elastics with current technologies can be cost prohibitive. Also, ink printing of large areas becomes expensive. Moreover, to achieve intense colors, high amounts of ink have to be applied, which may lead to increased manufacturing costs and the ink rubbing off during use of the printed article. The printer described above, in addition to design flexibility, allows for easy integration of multiple colors in diaper components or other products. Colored and especially multi-colored elastics can provide for a visual indication of functional attributes such as a stretch indication. 
         [0035]    The printer described above can also be used in a process for applying a composition onto a substrate web comprising the following steps: providing a substrate; and non-impact printing a composition onto at least one side of the substrate using a printer in which the composition does not pass through an orifice during the printing process. The resulting printed material can then be used as is, further processed, integrated with other materials or processes, or transferred onto other substrates. 
       Printing System 
       [0036]      FIG. 3  is a diagram of a system  130  to use the printer to print ink onto a substrate. System  130  includes a print head  148  mounted on a track  142  supported by vertical posts  144  and  146 , a wall, or other support. Print head  148  corresponds with printing system  10 . A drive unit  134 , using a motor, controls movement of print head  148  along track  142  in an x-direction as indicated by arrows  140 . A substrate support  150  is located on a track  136 , which would be supported by a vertical post, wall, or other support. A drive unit  132 , using a motor, controls movement of substrate support  150  along track  136  in a y-direction as indicated by arrows  138 . A substrate can be mounted or otherwise affixed to substrate support  150 , and a line or pattern can be printed upon the substrate by print head  148 . The configuration of the line or pattern is determined by the coordinated movement of print head  148  along track  142  and the substrate on substrate support  150  along track  136 . 
         [0037]    A computer  100 , corresponding with controller  57  and used to implement controller  57 , electronically controls print head  148  and drive units  132  and  134  for moving substrate support  150  and print head  148 , respectively. Computer  100  can include, for example, the following components: a memory  112  storing one or more applications  114 ; a secondary storage  120  for providing non-volatile storage of information; an input device  116  for entering information or commands into computer  100 ; a processor  122  for executing applications stored in memory  112  or secondary storage  120 , or as received from another source; an output device  118  for outputting information, such as information provided in hard copy or audio form; and a display device  124  for displaying information in visual or audiovisual form. Computer  100  can optionally include a connection to a network such as the Internet, an intranet, or other type of network. 
         [0038]    Computer  100  can be programmed to control movement of print head  148  along track  142  and substrate support  150  along track  136 . In particular, computer  100  can be programmed to electronically control movement of print head  148 , via drive unit  134 , in x-direction  140  laterally across a substrate on substrate support  150 , and computer  100  can be programmed to electronically control movement of the substrate on substrate support  150 , via drive unit  132 , in y-direction  138  vertically with respect to print head  148 . Computer  100  also controls print head  148 , as described above, for movement of the wire and delivery of the ink from the wire to the substrate. Computer  100  can also be programmed to control an air solenoid in system  10 . The use of tracks  136  and  142  for coordinated movement of substrate support  150  and print head  148 , respectively, thus effectively functions as an X-Y stage for using the printer to print a wide variety of shapes and configurations of patterns, lines, or other elements. As an alternative, lines or patterns can be printed using one of the following techniques: coordinated movement of print head  148  in the y-direction and substrate support  150  in the x-direction; movement of print head  148  in both the x-direction and y-direction; or movement of substrate support  150  in both the x-direction and y-direction. 
         [0039]    Computer  100  can also be programmed to control the printer for radial printing. In particular, a first orifice can direct an air jet at the wheel or wire to remove paint in a purely radial direction, while other orifices supplying air can be angled above the air jet created by the first orifice to help eliminate conical divergence of the paint as it is pulled from the surfaces of the wheel or wire.