Patent Application
20150013558
This disclosure is generally directed to systems and methods for forming robust prints. More specifically, this disclosure is directed to a system and method thereof that removes residual oils from freshly printed images produced by direct-to-paper printing.
Current printing systems use solid ink and utilize a continuous-web direct-to-paper print architecture, such as CiPress® by Xerox Corporation. During the continuous-web direct-to-paper process, ink is jetted onto the web. Thereafter, a high pressure roller nip, also referred to as a spreader, spreads the ink on the web to achieve the desired print image. In turn, silicone oil from the spreader is left on the ink.
After exiting the spreader, an aqueous overcoat is applied to the freshly printed image to ensure image robustness. The overcoat protects the ink of the printed image from being rubbed off or scratched off the surface of the media substrate (e.g., paper).
There is a challenge when overcoating freshly printed ink in the continuous-web direct-to-paper print architecture. Due to the low surface energy of the ink and the residual oil from the spreader that remains on the surface of the media substrate having the freshly printed ink, images with crease areas (white space) are produced.
There remains a need for a system and method that removes, prior to the overcoating step, residual oil from the surface of the media substrate having freshly printed ink.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments herein. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the disclosure herein, since the scope of the disclosure herein is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features.
Broadly, embodiments of the disclosure herein generally provide a printing system including an oil removal subsystem having an application device impregnated with an oil removal solution including a low carbon alcohol.
In another aspect of the disclosure herein, a system for online oil removal from printed media including an oil removal solution including a low carbon alcohol, the oil removal solution is operable downstream of a spreader of the printing system, and the oil removal solution is adapted to contact a printed media after the printed media contacts the spreader.
In yet another aspect of the disclosure herein a method for oil removal from printed media including receiving a printed media, applying to the printed media an oil removal solution containing low carbon alcohol, and removing oil removing solution from the printed media.
Various embodiments of the present disclosure will be described herein below with reference to the following figures wherein:
The present disclosure provides systems and methods that remove residual oils from freshly printed images produced by direct-to-paper printing prior to applying a protective overcoat to the printed image, thereby yielding a uniform image.
The system 10 may supply a continuous web of media 30, for example, paper, from a media source 40, such as a spool. The continuous web of media 30 may be unwound as needed, and propelled by a variety of motors, not shown. A set of rolls 50 may control the tension of the unwinding media 30 as the media 30 moves through a path 45. Along the path 45, there may be preheater 60, which can bring the media 30 to an initial predetermined temperature. The media 30 can then move through a printing device 70 including a series of print-heads 80. Each print-head 80 may extend across the width of the media 30.
Following the printing device 70 may be one or more mid-heaters 90. The mid-heaters 90 can use contact, radiant, conductive, and/or convective heat to bring the ink on the media to a temperature suitable for desired properties when the ink on the media is sent through the spreader 100. The temperature may depend on the type of ink used on the printing device 70. The ink may be, for example, a solid ink that may include hydrocarbon wax (>50%), resin, dispersant, and pigments, such as commercial Xerox® phase-change solid inks sold under the brand names of Phaser® or ColorQube®.
The spreader 100 may include any suitable system or apparatus that applies a predetermined pressure and, in some implementations, heat to the media 30. Thus, the spreader 100 may include drums (not shown), such as an image-side drum (not shown) and pressure roll (not shown) that apply heat and pressure to the media 30. In addition, the spreader 100 may include a cleaning/oiling station (not shown) associated with the image-side drum (not shown), suitable for cleaning and/or applying a layer of a lubricant, for example, amino silicone oil.
The spreader 100 takes what are essentially droplets, strings of droplets, or lines of ink on web media 30 and smears them by pressure, with or without heat, so that spaces between adjacent droplets are filled and the image becomes uniform. The media 140 leaving the spreader 100 may contain residual oil 150 on the printed image.
An oil removal subsystem 20 may be immediately downstream of the spreader 100 and immediately upstream of a coating station 110. The coating station 110 can be configured to coat a clear ink overcoating to the printed media.
In one embodiment according to the present disclosure, the oil removal subsystem 20 may be an offline system that can include an application device that is offline of the media path 45 such as a cloth impregnated with a low carbon alcohol. In such embodiment, a user may use the low carbon alcohol impregnated cloth to contact the printed image and thereby apply the low carbon alcohol to the residual oil on the image. Upon wiping the application device on the printed image, the residual oil may be removed.
In another embodiment according to the present disclosure, the oil removal subsystem 20 may be an online system that can include an application device that is online of the media path 45 such as shown on
The wetting roller 120 and/or the wiping roller 130 may be covered by a soft material, for example, cloth, fabric, or terry cloth. The wetting roller 120 can be impregnated with an oil removal solution, such as a low carbon alcohol solution. The residual oil 150 on the printed image is desirably miscible with the oil removal solution. Thereby, when the wetting roller 120 contacts the printed media, the residual oil tends to mix with the oil removal solution. Next, the media 140 passes by the wiping roller 130 to wipe off both oil removal solution and residual oil from the printed image.
The wiping material can be spread onto the printed image with a conformal sponge or cloth-type roller that is pre-wetted with a transfer roll. Immediately following this conformal roll, there can be a pick-up roll (also made of a porous material such as sponge or cloth) that can wipe the wetted print.
The oil removal solution in/on the wetting roller 120 may be a low carbon alcohol. The amount of the low carbon alcohol may be, for example, from about 5 to about 20 milliliters of low carbon alcohol per square meter of the printed media, or from about 7 to about 18 milliliters of low carbon alcohol per square meter of the printed media, or from about 10 to about 15 milliliters of low carbon alcohol per square meter of the printed media.
The specific low carbon alcohol used may depend on several factors, for example, miscibility with the residual oil, mild enough to avoid attack of the printed surface, volatile enough to evaporate so as not to compromise the overcoating step, and being non-toxic and mild which leaves no residue.
The number of carbons in the low carbon alcohol may be in embodiments from about 3 to about 8, or from about 3 to about 6, or from about 3 to about 5. If the low carbon alcohol has more than about 6 carbons, then the alcohol may have more hydrocarbon character and may tend to rub the solid ink off the printed media. In various embodiments, the low carbon alcohol may be, for example, isopropanol, 1-butanol, 2-butanols, hexyl alcohol, and 1-octanol. In one embodiment, the low carbon alcohol is, for example, isopropanol.
Table 1 shows some characteristics of exemplary low carbon alcohols according to the present disclosure
The amount of low carbon alcohol solution applied to the printed image can vary according to the amount of residual oil on the printed image. In other words, a greater amount of low carbon alcohol solution can be used for a greater amount of residual oil. However, this quantitative relationship is only general in nature.
The media 40 on which the printed image is located can be of varying types, such as uncoated paper, coated paper, or plastic film, for example, a polyester film made of polyethylene terephthalate (PET) such as Mylar® sold by DuPont, a biaxially oriented polypropylene (BOPP) film sold by Innovia, or aluminum foil. The specific media 40 used can vary inasmuch as it does not contact the low carbon alcohol solution according to some embodiments. Thus, there can be little, if any, contact between the low carbon alcohol solution and the media 40, which tends to minimize concern about potential adverse effects due to such contact.
The following Example illustrates one exemplary embodiment of the present disclosure. This Example is intended to be illustrative only to show one of several methods of removing oil from a printed media and is not intended to limit the scope of the present disclosure. Also, parts and percentages are by volume unless otherwise indicated.
Coating Method “A”—Meyer rod coating method
Solid ink prints were generated using a drum maintenance unit (DMU) that contains spreader oil, in lieu of the usual transfix oil used in a typical office printer mode. After printing the solid fills, a KimWipe® by Kimberly-Clark was moistened with isopropanol alcohol (IPA) and the print was rubbed in a gentle sweeping motion. Next, the treated print was coated with a Mathis Labcoater using a #2 ½ Meyer rod (wire-wound rod) and heated to 80° C. for 2 minutes with a series of coating formulations (see Table II).
Coating Method “B”—K-proof coating of overcoat (simulation of Interflex in-line coater/tinter process)
Solid ink prints (as described in method A) were cut to 5×8.5 inch rectangles, and subjected to coating with the overcoat solutions as indicated on Table II.
Robustness Measurements
Crease fold measurements were done to test the effectiveness of the coating in improving robustness—the more ink flaked off, the worse the coating integrity.
As shown in
It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various, presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
