JP6091106B2 - Marking material subsystem - Google Patents

Description

  The present disclosure relates to marking and printing methods and systems, and more specifically, marking materials such as UV lithographic printing inks and offset inks, i.e., printing materials, that can be used to variably data for multiple components (e.g., multiple colors). The present invention relates to a marking and printing method and system.

  Today, offset lithographic printing is a common printing method (in the description herein, both the terms “print” and “mark” can be used interchangeably). In a typical lithographic printing process, a printing plate is produced that includes “image areas” made of hydrophobic and lipophilic materials and “non-image areas” made of hydrophilic materials. The plate may be a flat plate, cylinder, or belt surface. An image area is an area corresponding to a portion that is filled with a printing material such as ink or a marking material on a final printed matter (that is, a target substrate), and a non-image area is filled with the marking material on the final printed matter. This is a region corresponding to a portion that has not been made. The hydrophilic region accepts a water-based liquid and is easily wetted by the water-based liquid. This water-based liquid is commonly referred to as fountain solution (typically composed of water and a small amount of alcohol, and other additives and / or surfactants to reduce surface tension). The hydrophobic region accepts ink without mixing with the fountain solution. On the other hand, the fountain solution formed on the hydrophilic region forms a liquid “peeling layer” and repels ink. Accordingly, the hydrophilic region of the printing plate corresponds to a place where the final printed matter is not printed, that is, a “non-image region”.

  The ink can be transferred directly to a substrate such as paper, or can be applied to an intermediate surface such as an offset (or blanket) cylinder in an offset printing system. The offset cylinder is covered with a conformable dressing or sleeve having a surface that can be fitted with the underlying irregularities, and these conformable dressings or sleeves have a depth from the crest to trough of the surface of the stamp to be imaged. It may have a surface that is deeper from the mountains to the valleys slightly deeper. Further, the surface roughness of the offset blanket cylinder eliminates defects such as spots and allows a more uniform layer of printing material to be applied to the base. Apply sufficient pressure to transfer the image from the offset cylinder to the substrate. This pressure is created by sandwiching a substrate between the offset cylinder and the pressure cylinder.

  One variation is called lithographic printing, i.e. driography, which does not require drying or water, and the cylinder of the printing plate is coated with oil-repellent silicone rubber and patterned to form a negative image of the printed image. The printing material is applied directly to the plate cylinder without first applying some fountain solution as in the conventional or “wet” lithographic printing described above. The printing material includes ink, which may or may not include some volatile solvent additives. This ink is preferentially applied to the image forming area to form a latent image. When solvent additives are used for blending the ink, the solvent additives are preferentially diffused on the surface of the silicon rubber, thereby forming a release layer and repelling the printing material. The printing material is further repelled by the low surface energy silicone rubber. As explained above, the latent image can be transferred again to the background or transferred to the background via an offset cylinder.

  The lithographic and offset printing techniques described above use a permanently patterned printing plate and are therefore only useful when printing many identical copies of magazines, newspapers, etc. (long printing operations). is there. However, with these techniques, it is not possible to create and print a new pattern between pages without removing and replacing the printing cylinder and / or printing plate (i.e., with this technique, for example, digital printing) It is not possible to change the image between prints like a system to achieve really fast variable data printing). Furthermore, the cost of permanently patterned printing plates or cylinders can be amortized by printing a large number of prints. Thus, in contrast to printing with a digital printing system, the cost per print for a small print operation of the same image is higher than the cost per print for a larger print operation of the same image.

  One limitation that has not been overcome in known systems that perform variable data lithographic printing is that many of these systems can only produce monochromatic images. As long as any such system provides multi-color printing, printing is performed using multiple separate print engines, one color at a time, in multiple printing processes. Multicolor printing is eagerly desired for a number of reasons such as cost, complexity, maintenance, size, energy consumption, etc., which are not optimal in a plurality of print engine systems.

  Accordingly, the present disclosure relates to a system and method for providing variable data lithographic printing and offset lithographic printing that overcomes the disadvantages identified above and other disadvantages that will become apparent below by this disclosure. be able to. The present disclosure relates to various embodiments of a multicolor variable imaging lithographic marking system and related methods based on variable patterning of fountain solution.

  In such a system, an image recreatable layer is provided in an image creating section such as a drum, a printing plate, a belt, and a roll. In order to be able to receive and transport a fountain solution layer from the fountain solution subsystem, this layer has special properties such as composition and surface roughness. An optical patterning subsystem, such as a scan modulated laser, patterns the fountain solution layer using the characteristics of the reimageable layer selected to facilitate this patterning. The ink is then applied in the ink application subsystem, and the ink is selectively present in the gap formed by the patterning subsystem in the dampening water layer, thereby forming a latent image of the ink. The The latent image of the ink is then transferred to the ground, the reimageable surface is cleaned, and this process can be repeated. This provides fast variable marking.

  According to one aspect of the present disclosure, a plurality of ink application subsystems are provided, each having a different color ink. Each ink application subsystem moves independently to engage (ie, close) and separate from the image reproducible surface layer of the image generator. The patterning subsystem creates a first pattern in the fountain solution and, as described above, the first ink application subsystem engages the re-imageable surface and the first color ink Create a latent image. The latent image of the first color ink is transferred to the base by a transfer nip or the like, and the image reproducible surface layer of the image creating unit is cleaned. A second pattern is created in the fountain solution, the first ink application subsystem separates from the image recreatable surface, and as described above, the second ink application subsystem is the image recreatable surface. To generate a latent image of the second color ink. The substrate then passes again through the transfer nip and receives the latent image of the second color ink on the latent image of the first color ink. In a general four-color process, this pattern formation, engagement, and ink printing continuous operation can be repeated four times in total for each color. In practice, this process can be repeated more frequently if different color systems are used, or if different printing effects are desired.

  According to another aspect of the present disclosure, after the latent image of the first color ink is transferred to the ground, the image is partially cured on the ground, and the transferred color is returned from the ground to the image creating unit. , Oil stains caused by applying the next color layer thereon can be suppressed. This partial curing can be done from the back side or the front side (or both sides) of the substrate, and can be performed by UV irradiation, heating, or other methods appropriate to the particular ink and substrate used. In some embodiments, a sheet-like substrate such as paper is conveyed on a single drum from the first pass to the last pass. In another embodiment, another substrate handling mechanism is used.

FIG. 1 is a side view of a system for variable lithographic printing of multiple components according to an embodiment of the present disclosure. FIG. 2A is a side view of a portion of an image recreating portion of an image creation drum, plate or belt that does not use an intermediate layer, according to an embodiment of the present disclosure, in the layer of the image reproducible surface. A state in which fine particles having absorptivity are dispersed and contained is shown. FIG. 2B is a side view of a cut-away portion of an image re-creation section of an image creation drum, plate or belt using an intermediate layer, according to an embodiment of the present disclosure. FIG. 3 is a side view of a portion of the image recreation portion of an image creation drum, plate or belt according to another embodiment of the present disclosure, wherein the layer of the image recreatable surface is for absorbing light. The color is shown. FIG. 4 is a side view of a portion of the image recreation portion of an image creation drum, plate or belt according to yet another embodiment of the present disclosure, wherein the layer of the image recreatable surface is optically transparent or It is translucent and shown on a layer that absorbs light. FIG. 5A is an explanatory view showing the feature of the unevenness of the image forming surface for defining RSm and the feature of its size. FIG. 5B is an explanatory diagram showing the feature of the unevenness of the image forming surface for defining Ra and the feature of the size. 6 is an enlarged side view of a portion of the image re-creation unit shown in FIG. 2 with wet water applied thereon and patterned with light B according to an embodiment of the present disclosure. FIG. 7 is an illustration of an ink application subsystem having a rotationally installed metering (formation) roller that receives ink from a supply roller and selectively transfers the ink to a reimageable surface in accordance with an embodiment of the present disclosure. It is a side view. FIG. 8 illustrates applying a uniform layer of ink over a patterned layer of dampening water and a portion of the reimageable surface layer revealed by dampening water patterning according to an embodiment of the present disclosure. It is a side view of the ink application | coating subsystem used for. FIG. 9 is a side view of a system for variable color lithographic printing of multiple colors according to another embodiment of the present disclosure. FIG. 10 is a side view of a serial system for variable lithographic printing of multiple components according to an embodiment of the present disclosure.

  With reference to FIG. 1, illustrated is a system 10 for variable lithographic printing of multiple colors according to one embodiment of the present disclosure. The system 10 includes an image creating unit 12 (in this embodiment, a drum, but a plate, a belt, and the like can also be used), and a number of subsystems are arranged around the image creating unit 12. These subsystems are described in detail below. The image creating unit 12 applies the ink image to the base 14 by sandwiching the base 14 between the image creating unit 12 and the pressure roller 18 at the nip 16. Various types of substrates such as paper, plastic or composite sheet film, ceramic, glass, etc. can be used. For clarity and brevity of this description, this substrate is assumed to be paper, but the present disclosure is not limited to these substrate forms. For example, other substrates can include cardboard, corrugated packaging materials, wood, ceramic tiles, fabrics (eg, cloth, curtain fabrics, clothing, etc.), transparent or plastic films, metal foils, etc. . A wide range of marking materials can be used, including those with pigment densities greater than 10% by weight, including but not limited to metallic inks or white inks that are convenient for packaging. In order to make this part of the present disclosure clear and concise, we generally use the term ink, which includes pigments and others that can be applied by the systems and methods disclosed herein. It goes without saying that a series of marking materials such as these materials are also included.

  Referring to FIG. 2, the image creating unit 12 is shown in a partial cross section. In one embodiment, the image generator 12 includes a structural attachment layer 22 (e.g., metal, ceramic, plastic, etc.) and a thin image reproducible layer 20 formed thereon, both image recreating. A portion 24 is formed to form a rewritable printing bracket. The image regenerator 24 further includes additional structural layers, such as the intermediate layer 21 shown in FIG. 2B, which is either below the image reproducible surface layer 20 and above or below the structural attachment layer 22. Placed in. The intermediate layer 21 may be electrically insulating (or conductive) or thermally insulating (or thermally conductive), and may have a variable compressibility, a variable durometer, and the like. In some embodiments, the intermediate layer 21 comprises a closed cell polymer foam sheet and a mesh mesh layer (such as cotton) that are laminated together by a thin adhesive layer. In general, blankets are in terms of compressibility and durometer using a 3-4 layer system with a thickness between 1 mm and 3 mm, including a thin top layer 20, designed to obtain optimum roughness and surface energy characteristics. Optimized. The image re-creation unit 24 can take the form of an independent drum or roll or a flat blanket wrapped around the cylinder body 26. In another embodiment, the reimageable portion 24 is a stretchable continuous sleeve that is placed over the cylinder body 26. Flat plates, belts, webs and other configurations (which may or may not be supported by the lower drum structure) are also within the scope of this disclosure. For the following discussion, it is assumed that the image recreatable portion 24 is conveyed by the cylinder body 26, but it will be appreciated that many different configurations can be envisaged by the present disclosure as discussed above.

  The reimageable surface layer 20 is made of a polymer such as polydimethylsiloxane (PDMS, or more commonly referred to as silicon) and is resistant to, for example, silica to reinforce the silicon and optimize its durometer. It has an abradable filler and can include catalyst particles that promote curing and crosslinking of the silicon material. Alternatively, silicon moisture cured (also known as tin cured) silicon can be used as opposed to catalytically cured (also known as platinum cured) silicon. Returning to FIG. 2A, the reimageable surface layer 20 may contain a small proportion of radiation sensitive particulate material 27 that absorbs laser energy very efficiently. In some embodiments, for example, a small percentage of carbon black in the form of microscale (eg, average particle size less than 10 μm) or nanoscale particles (eg, average particle size less than 1000 nm) or nanotubes. Radiosensitivity can be obtained by mixing with. Other radiation-sensitive materials that can be blended in silicon include graphene, iron oxide nanoparticles, nickel-plated nanoparticles, and the like.

  Alternatively, layer 20 of the reimageable surface can be colored, as shown in FIG. 3, or otherwise processed to provide uniform radiation sensitivity. In yet another method, described in more detail below, the layer 20 of the reimageable surface is substantially transparent to light energy from the source, and as shown in FIG. The light energy (eg, layer 22 may include components that are at least partially absorbing).

  Reimageable surface to apply ink evenly (without pinholes, beads or other inconvenience) to the reimageable surface, and then encourage the ink to lift and transfer onto the substrate The layer 20 has a weak adhesive force to the ink at the contact point, but still needs to have good lipophilicity and wettability to the ink. One material having such characteristics is silicon. Alternatively, other materials can be used that provide this property, such as certain mixtures such as polyurethane, fluorocarbon, and the like. In terms of providing suitable wettability with dampening water (such as a water-based fountain liquid), the silicon surface need not be hydrophilic, and may actually be hydrophobic. This is because a wettable surfactant such as a silicone glycol copolymer can be added to the fountain solution, which allows the fountain solution to wet the silicon surface.

  Thus, while water-based solutions are one embodiment of fountain solution that can be used in embodiments of the present disclosure, features such as repelling oil, being easy to vaporize, decomposable, or selectively removable It goes without saying that other non-aqueous fountain solutions with low surface tension can be used. One such class of liquids is hydrofluoroethers (HFE) such as the Novec brand Engineered Fluid manufactured by 3M Company, St. Paul, Minnesota. These liquids have various advantageous properties, some of which are relevant to the present disclosure, as described below. (1) The heat of vaporization is significantly lower than that of water, so that when using an optical laser to selectively vaporize dampening water to form a latent image, a smaller laser to obtain a given printing speed Only power is needed, or faster printing speeds can be obtained with a given laser power. (2) The heat capacity is smaller, and the same effect as described above can be obtained. (3) Almost no solid residue remains after vaporization, whereby the requirements for cleaning can be relaxed and / or long-term stability can be improved. (4) The vapor pressure and boiling point can be manipulated, thereby improving the stability of forced vaporization performed by selecting a space. (5) It has a low surface energy required for proper wettability of the image forming unit. And (6) harmless with respect to environment and toxicity. By adding additional additives, the conductivity of the wet water can be controlled. Other suitable alternatives include florinate having all or most of the above properties and other liquids known in the art. It goes without saying that these types of liquids can be used not only in an undiluted state, but also as an aqueous or non-aqueous solution or as a component of an emulsion.

  Also, by controlling and defining the appropriate amount of filler nanoparticles in the silicon, as well as the exact chemistry of the silicon material consisting of different combinations of polymer chain length and end-group capping chemistry, The surface energy of silicon can be optimized to provide good wettability. For example, a single component moisture-cured silicon that has been tin catalyzed with a low density silica filler has been found to have a distributed surface energy between 24 and 26 dynes / cm. Certain additives can also be added to the marking material to significantly reduce the surface tension of the marking material and improve its surface wettability to silicon. In order to facilitate dispersion and curing, these additives may include known copolymer fluoro or leveling agents based on silicon chemistry, which also incorporate other polymer groups. For example, the leveling agent can reduce the surface tension of the ink to 21 dynes / cm.

  If silicon is used as layer 20 for the reimageable surface, other particles 27 can be embedded in layer 20 to promote the catalyst for silicon curing and crosslinking.

図５Ａおよび図５Ｂを参照すると、ＲＳｍはサンプル長Ｌ内の形状要素の幅Ｘの平均値として規定され、Ｒａはサンプル長Ｌに渡る平均基線測定に対する頂点の平均に関連する。したがって、ＲＳｍは、山から山の間隔の特性であり、Ｒａは山の高さの特性である。Ａ〜Ｌ^２の寸法を有するサンプル領域Ａの特性を用いることで、これらの定義を２つの寸法に渡って展開することができる。 According to one embodiment, the roughness of the layer 20 of the image reproducible surface is approximately the same as the thickness of the desired dampening water layer to efficiently store dampening water so that the dampening water is in the desired non-image creation area. To prevent it from spreading across the boundaries. For example, the reimageable surface layer 20 may have measured surface roughness characteristics RSm and R, which are defined below.

Referring to FIGS. 5A and 5B, RSm is defined as the average value of the width X of the shape element within the sample length L, and Ra is related to the average of the vertices relative to the average baseline measurement over the sample length L. Therefore, RSm is a peak-to-peak interval characteristic, and Ra is a peak height characteristic. By using the characteristics of the sample region A having dimensions of A to L ^2, can be developed across these definitions into two dimensions.

  It is desirable to arrange the peaks and valleys slightly irregularly to reduce the possibility of moiré interference with a line screen pattern. Furthermore, it is desirable that the spatial distance between the mountains is slightly smaller than the dot size of the smallest line screen, for example, smaller than 10 μm. With this roughness, the surface can easily retain moist water, and at the same time, the moire effect can be eliminated, and the ink can be applied more uniformly and transferred more efficiently. This will be described in more detail below. In some embodiments, RSm is less than about 20 μm and Ra is less than about 4.0 μm. In a more specific embodiment, RSm is less than 10 μm and Ra is between 0.1 μm and 4.0 μm.

  Also, the reimageable surface layer 20 is abrasion resistant (even when pulled) to uniformly transfer ink from the surface to a porous or rough paper medium. ) Must have some flexibility. The reimageable surface layer 20 has sufficient thickness to provide adequate resilience and durometer and sufficient flexibility to coat ink on different types of media having different levels of roughness. Can be created. Of course, it is possible to design a system for printing on specific types of media without the need to support various types of media. In one embodiment, the thickness of the silicon layer forming layer 20 of the reimageable surface is in the range of 0.5 μm to 4 mm.

  Ultimately, there should be no water droplets or dewetting on the surface of the reimageable surface layer 20 and the ink should be able to flow uniformly over the surface. Various materials such as silicon can be manufactured or roughened to have various surface energies, and additives can be used to adjust their surface energy. The reimageable surface layer 20 has nominally low values of dynamic chemical adhesion, but is sufficient to improve ink wettability and sufficient wettability / affinity of ink without water droplets. Surface energy.

  Returning to FIG. 1, the dampening water subsystem 30 is disposed at the first position around the image creating unit 12. The dampening water subsystem 30 generally includes a series of rollers (referred to as a watering unit) to provide uniform wetting on the surface of the layer 20 of the reimageable surface. It is well known that there are various types and configurations of watering units. The purpose of the watering unit is to provide a layer of dampening water 32 having a uniform and controllable thickness. In some embodiments, this layer has a thickness in the range of 0.2 μm to 1.0 μm and is very uniform with no pinholes. The dampening water 32 is mainly composed of water, and optionally a small amount of isopropyl alcohol or ethanol is added to suppress the original surface tension and lower the vaporization energy required for the next laser pattern formation. Furthermore, ideally, a small amount of a suitable surfactant is added at a weight-converted rate to encourage a large amount of watering to the layer 20 on the reimageable surface. In some embodiments, the surfactant comprises a family of silicon glycol copolymers such as trisiloxane copolyol compounds or dimethicone copolyol compounds, which can be added to a uniform diffusion and from more than 22 dynes / cm by adding a small amount by weight. Easily promotes low surface tension. The surface tension can be suppressed even with other fluorosurfactants. Optionally, a radiation sensitive colorant may be included in the dampening water 32 to partially absorb the laser energy in the patterning process, as will be described in detail below.

  In addition to or in lieu of chemical methods, mechanical / electrical methods can be used to facilitate the wetting of the dampening water 32 onto the layer 20 of the reimageable surface. For example, by applying a high electric field between the watering roller and the image reproducible surface layer 20, the force of static electricity works to form a uniform film of dampening water 32 on the image reproducible surface layer. Pull up to 20. This electric field can either sustain a charge sufficiently by applying a voltage between the watering roller and the layer 20 of the reimageable surface or by charging a transient current in the layer 20 itself of the imageable surface. Is generated. The dampening water 32 may be conductive. Thus, in this embodiment, an insulating layer (not shown) can be added to the watering roller and / or below the layer 20 of the reimageable surface. By using electrostatic force, it is possible to reduce the amount of surfactant or remove it from dampening water.

  The dampening water subsystem 30 weighs the dampening water 32 and applies it to the layer 20 of the reimageable surface and then weighs it using a sensor 34 such as a field-type non-contact laser gloss sensor or a laser contrast sensor. The thickness of wet water can be measured. An example of such a sensor is that sold by Wenglor Sensors (Bieber Creek, Ohio). Control of the dampening water subsystem 30 can be automated using these sensors.

  In certain embodiments, after applying an accurate and uniform amount of dampening water, the optical patterning subsystem 36 can be used to selectively vaporize the dampening water layer, eg, using laser energy. A latent image is formed in the damp water. Here, however, the reimageable surface layer 20 ideally approaches the top surface 28 (FIG. 2) as much as possible to absorb most of the energy and heat the dampening water to maintain spatial resolution. The total energy wasted in doing so must be minimized and the heat diffusing horizontally must be suppressed. Alternatively, for example, by adding a suitable radiation sensitive component that is at least partially absorptive at the wavelength of the incident radiation to the moist water, or an appropriate wavelength that is readily absorbed by the moist water (eg, water is 2 It is preferable to absorb most of the incident radiation (such as a laser) energy in the dampening water layer itself by selecting a radiation source (having a peak absorption band near a wavelength of .94 micrometers).

  There are a variety of systems and methods for supplying energy to pattern dampening water across a reimageable surface, and together with the various system components disclosed and claimed herein, these systems and methods. Can be used. However, it will be appreciated that the present disclosure is not limited by the particular patterning system and method.

  Referring to FIG. 6, there is an enlarged view of the area of the image recreatable portion 24 having a layer 32 of dampening water applied onto the layer 20 of the image reproducible surface, the optical pattern from the optical patterning subsystem 36. It is shown that the wet water layer 32 is selectively vaporized by irradiation with formation energy (for example, light beam B). The vaporized dampening water becomes part of the atmosphere around the system 10. As a result, a pattern of the wet water region 38 and the gap 40 for receiving the ink is formed on the layer 20 of the image reproducible surface. Due to the relative movement between the image generator 12 and the optical patterning subsystem 36 (eg in the direction of arrow A), the patterning of the dampening water layer 32 can proceed in the process direction.

  Returning to FIG. 1, after patterning the dampening water layer 32, one of a series of ink application subsystems 46a, 46b, 46c, 46d may be used to form the dampening water layer 32 and the reimageable surface. A uniform ink layer 48 (shown in FIG. 6) is applied over layer 20. In the embodiments disclosed herein, it goes without saying that marking materials other than ink (non-aqueous marking materials, finishes, surface treatment agents, etc.) can be used whether or not they are visible. Thus, although the “marking material applicator” may be more general and comprehensive, the term “ink application” subsystem is used in the following description for ease of reference. Four ink application subsystems are shown in FIG. Each of these subsystems corresponds to a color component, such as a cyan, magenta, yellow, and black color system. Alternatively, the system 10 can add or reduce ink application subsystems as appropriate to other color systems, printing effects, and the like. Adding or reducing inking subsystems in this manner can be readily understood by those skilled in the art from this disclosure. For illustrative purposes, it is assumed that each ink application subsystem applies different colors of ink, but various configurations are possible, so that each ink application subsystem (not just) uses different marking materials as well as colors. Can be applied. For example, between two such ink application subsystems, one subsystem can apply a color with a flat finish and the other subsystem can apply the same color with a reflective finish (in some cases) Can be different patterns between the two subsystems). Standard ink can be applied on the one hand and magnetically readable ink on the other. Similarly, it is possible to apply a standard ink on the one hand and a uniform surface finish on the other. Accordingly, the scope of the methods and systems disclosed and claimed herein is not inherently limited by the actual material being applied.

  Optionally, an air knife 44 can be sprayed onto the layer 20 of the reimageable surface. To maintain clean and dry air supply and control of air temperature and reduce contamination by dust, the air knife 44 can control the flow of air over the surface layer in front of the ink application subsystem.

  Each ink application subsystem 46a, 46b, 46c, 46d may include a “keyless” system that uses an anilox roller to meter the offset ink applied on one or more forming rollers. Alternatively, each ink application subsystem 46a, 46b, 46c, 46d can be comprised of conventional components having a series of forming rollers that use an electrical machine key to determine the correct ink supply. The general aspects of the architecture of the inking subsystem depend on the application of the present disclosure and can be easily understood by those skilled in the art.

  Each ink application subsystem 46a, 46b, 46c, 46d can be activated to engage and disengage from the reimageable surface 20. Engagement means that the inking subsystem or component thereof is in close proximity to the reimageable surface and causes the material carried thereby to be transferred onto the reimageable surface. This can mean either physical contact between the two or no physical contact, which depends on many factors. Similarly, separating means placing the ink application subsystem or components thereof where the conveyed material is not easily transferred from the ink application subsystem to the reimageable surface. In the embodiment shown in FIG. 1, each ink application subsystem can be viewed as a substantially radial track or armature with respect to the image generator 12. There are many other embodiments for engaging and separating the ink application subsystem and the reimageable surface 20 that are also within the scope of this disclosure. One such alternative embodiment 50 is shown in FIG. This embodiment 50 includes an ink application subsystem 52, which includes a metering (formation) roller 54 that is rotatably disposed, receives ink from the anilox roller 56, and supplies the ink to the image generator 12. The image is selectively transferred to the image recreatable surface 20. The forming roller 54 rotates about the central axis at the first position 54a so that the surface of the forming roller 54 does not engage the reimageable surface 20. The center of rotation of the forming roller 54 can be rotated around the center 56a of the anilox roller 56 and moved to the second position 54b so that the surface of the forming roller 54 engages the re-imageable surface 20. . Thus, when the forming roller 54 engages the image recreatable surface 20, the ink from the tank 58 is applied to the image recreatable surface 20 and the forming roller 54 is separated from the image recreatable surface 20. The ink from the tank 58 is not applied to the image reproducible surface 20.

  Returning to FIG. 6, since the ink from the ink application subsystem 46 initially wets the layer 20 of the reimageable surface, the ink is exposed to the irradiated portion of the layer 20 of the reimageable surface ( It must have a sufficiently low cohesive energy to be applied separately to the dampening water gap 40) that receives the ink and sufficient hydrophobicity to be repelled by the dampening water region 38. The wet water has a low viscosity and repels oil, so separation occurs naturally in the wet water layer with very low dynamic cohesive energy. For this reason, the area covered with damp water repels all ink. In areas without dampening water, if the cohesion between the inks is significantly lower than the adhesion between the ink and the layer 20 of the reimageable surface, the ink will be between these areas at the exit of the nip of the forming roller. To separate. Accordingly, the viscosity of the ink used must be relatively low in order to efficiently fill the gap 40 and adhere effectively to the layer 20 of the reimageable surface. For example, if another known UV ink is used and layer 20 of the reimageable surface is made of silicon, it may be necessary to slightly change the viscosity and viscoelasticity of the ink to reduce cohesion, Can moisten the silicon. This rheological modification can be achieved by adding a low proportion of low molecular weight monomers or by using low viscosity oligomers in the ink formulation. In addition, wetting agents and leveling agents can be added to the ink to reduce the surface tension of the ink so as to efficiently wet the surface of the silicon.

  In addition to this rheological consideration, it is also important that the ink composition maintain the hydrophobic character, as repelled by the dampening water region 38. This can be maintained by selecting a resin and solvent for the offset ink having hydrophobic and nonpolar chemical groups (molecules). When the dampening water covers the layer 20, the ink cannot diffuse, emulsifies and quickly dissolves in the dampening water, and the dampening water has a much lower viscosity than the ink, so the entire dampening water layer has a film Separation occurs, thereby repelling the ink and preventing all ink from sticking to the area of the layer 20 covered with a sufficient amount of dampening water. In general, the thickness of the dampening water covering layer 20 is between 0.1 μm and 4.0 μm, and in some embodiments is 0.2 μm to 2.0 μm due to the exact nature of the surface irregularities.

  In a particular embodiment, a metering roller 62 having a forming roller 60 as shown in FIG. 7 can be used. By adjusting the amount of ink supplied through a roller system using a distribution roller, adjusting the pressure between the supply roller and the forming roller 60 and the forming roller 62, and adjusting the outflow from the ink tray using the ink key. The thickness of the ink covering the roller 60 and the optional roller 62 from the original roller, such as an anilox roller, can be controlled. Ideally, the thickness of the ink applied to the rollers 60, 62 should be at least twice the desired final thickness to be transferred to the reimageable layer 20 because of film separation. No need for a key that can control the overall thickness of the ink film by using an anilox roller with uniformly formed holes to carry the ink and maintaining the temperature to achieve the desired ink viscosity It is also possible to use the system. In general, the final film thickness may be approximately 1-2 μm.

  Ideally, an optimized ink system will separate and apply ink to the reimageable surface at a ratio of about 50:50 (ie, 50% will remain on the ink forming roller and 50% will be reimaged per pass). It is transferred to the surface that can be created). However, if the separation ratio can be controlled well, it is possible to separate at other ratios. For example, to separate at a ratio of 70:30, the ink layer on the image reproducible surface layer 20 is 30% of its nominal thickness when present on the outer peripheral surface of the forming roller. It is well known that the ability to separate further decreases by suppressing the thickness of the ink layer. By suppressing the thickness in this way, the remaining background ink can be left and the ink can be removed very cleanly from the image reproducible surface. However, the cohesive strength or internal bonding of this ink also plays an important role.

  Returning to FIG. 1, the first color ink supplied by the first ink application subsystem is applied to the reimageable surface in the region of the gap in the layer of fountain solution provided thereon. A first ink application subsystem, such as subsystem 46a, is engaged with the reimageable surface 20 so that a latent image of the first color ink is thereby formed. Next, the latent image of the first color ink is transferred to the base 14 by, for example, passing the base 14 through the nip 16 between the image creating unit 12 and the pressure roller 18. Sufficient pressure is applied between the image forming unit 12 and the pressure roller 18 so that the ink in the gap 40 (FIG. 8) physically contacts the base 14. Due to the adhesiveness of the ink to the base 14 and the strong internal cohesiveness, the ink separates from the layer 20 of the image reproducible surface and sticks to the base 14. The pressure roller or other nip 16 components can be cooled to further improve the transfer of the latent image of ink to the substrate 14. In practice, the base 14 itself can be maintained at a relatively lower temperature than the ink on the image creation unit 12 or locally cooled to assist the ink transfer process. Transfer (measured by mass) can transfer ink from the layer 20 of the image reproducible surface with an efficiency higher than 95%, and can be transferred with an efficiency exceeding 99% if the system is optimized is there.

  The substrate 14 can be held in place in the system so that the substrate 14 can easily re-pass through the nip 16 with each successive pass applying a latent image of one color of ink. More specifically, any residual ink and residual wet water remaining on the reimageable surface 20 after the nip 16 must be removed, preferably without damaging or scraping the surface. Most of the dampening water can be easily and quickly removed by using an air knife 70 that jets a sufficient air flow. The cleaning subsystem 72 can remove residual ink. The application of the fountain solution and the pattern formation of the fountain solution are repeated. This creates a new pattern in the fountain solution layer. The ink application subsystem 46a separates from the reimageable surface 20, and the ink application subsystem 46b moves to engage the image recreatable surface 20. As a result, the second color is applied to the pattern-formed dampening solution layer on the ink image recreatable surface 20, and a latent image of the second color ink can be formed. For example, by passing the background 14 through the nip 16 between the image creating unit 12 and the pressure roller 18, the latent image of the second color ink is transferred to the background 14. There are a variety of methods for aligning the substrate 14 that receives the latent image of the second color ink, and one of them is used (the description of this method is outside the scope of this disclosure) Ensure alignment of the latent image. This process is similarly repeated for the ink application subsystems 46c and 46d.

  To help prevent oil stains, color stains, and transferred colors from returning to the image creation unit from the background, after the latent image with a certain color of ink has been transferred to the background, the image is partially Can be cured. This partial curing can be accomplished by irradiating UV irradiation, heat, or other source 74 appropriate to the particular ink and substrate used, from the back or front side (or both sides) of the substrate. In addition, the ink can be partially cured on the reimageable surface 20 before being transferred to the substrate 14, such as by UV, heat, or other source 76.

  In the illustrated embodiment, the substrate 14 is held on the surface of the pressure roller 18 for each pass through the nip 16. The rotation of the image creating unit 12 and the rotation of the pressure roller 18 ensure the alignment described above in synchronization. The substrate 14 rotates n times (eg, n is the number of ink application subsystems) and then leaves the pressure roller 18. According to another embodiment 80 shown in FIG. 9, instead of transferring the latent image of each color directly to the substrate 14, it is continuously applied to the belt 82 (a web, a printing plate or other intermediate member is similarly used). be able to).

  Another method for indirectly transferring the ink pattern from the image generator to the substrate is also contemplated by this disclosure. For example, referring to FIG. 9, another embodiment 80 of the present disclosure includes a low mass, relatively flexible belt, or web image receiver 82, which has an image thereon. Has a re-creatable surface. Similar to the above embodiment, the watering system 84 applies a layer 86 of fountain solution onto the surface of the image receiver 82. One of various methods and systems is used to ensure a uniform and desired thickness of the fountain solution layer. Pattern the layer of fountain solution by a patterning subsystem 88 such as a scanning and modulating laser source. A plurality of ink application subsystems 90a, 90b, 90c, 90d, and the like are arranged close to each other without contacting the image recreatable surface of the image creating unit 82. The image creating unit 82 has a certain degree of flexibility. A plurality of engagement mechanisms 91a, 91b, 91c, 91d and the like are arranged on the opposite side of the ink application subsystems 90a, 90b, 90c, 90d and the like, and the image creating unit 82 is arranged therebetween. Each engagement mechanism 91a, 91b, 91c, 91d, etc. is moved independently in order to bend the image creation unit 82 and engage with the corresponding subsystem among the ink application subsystems 90a, 90b, 90c, 90d, etc. In this way, the ink is applied on the image creating unit 82. Therefore, for example, as shown in the figure, the engaging mechanism 91a bends the image creating unit 82 and engages it with the ink application subsystem 90a, so that the ink of the first color or composition is regenerated in the image creating unit 82. It can be applied on the createable surface. As described above, this ink is preferentially deposited in the gap formed by the patterning subsystem 88 to form a latent image of the colored ink on the surface of the image creating unit 82.

  For example, by passing the background 92 through the nip 94 between the image creating unit 82 and the pressure roller 96, the latent image of the colored ink is transferred to the background 92. Other aspects of image optimization can be partially cured and the substrate 92 can be held in place for a series of passes related to application of the image.

  After passing through the nip 94, any residual ink and residual dampening water remaining on the re-imageable surface of the image generator 82 is combined with the cleaning subsystem 100 (or other suitable cleaning method and subsystem). Removed using 98. As described above, the application of the fountain solution and the pattern formation of the fountain solution are repeated. This creates a new pattern in the fountain solution layer. The engaging portion 91a is retracted and activated so that the engaging portion 91b bends the image recreatable surface of the image creating portion 82 and engages with the ink application subsystem 90b. As a result, the ink application subsystem 90b applies the second color ink to the pattern-formed dampening solution layer on the image recreatable surface of the image generation unit 82, and attaches the second color ink. A latent image can be formed. The latent image of the second color ink is transferred to the base 92. Similarly, this process is repeated for the ink application subsystems 90c and 90d.

  In the above-described embodiment, printing by a plurality of passes is mainly performed. As a result, a plurality of colors are continuously applied to the patterned intermediate transfer portion, the colored pattern is transferred to the base, and the intermediate transfer portion is cleaned. On the other hand, in certain embodiments, it is desirable to transfer individual color images directly directly to the substrate. Such a case is, for example, a case where the base is continuous or longer than the outer periphery of the pressure roller, and it is not practical to hold the base and pass the base through the nip many times.

  Referring to FIG. 10, an embodiment 110 of a serial structure for multi-color variable data lithographic printing that prints directly on the substrate is shown. According to the embodiment 110, the plurality of image creation units 112a, 112b, 112c, 112d, and the like are configured to engage with the base 116 that moves in proximity to the image creation units. Each include, for example, different color ink application subsystems 114a, 114b, 114c, 114d, and the like. Basically discussed above, each image generator 112a, 112b, 112c, 112d includes an image re-creatable layer on top of it from the dampening water subsystem 118a, 118b, 118c, 118d, etc. Each receives dampening water. The fountain solution layer on each reimageable surface is patterned by patterning subsystems 120a, 120b, 120c, 120d, etc., respectively. In each ink application subsystem 114a, 114b, 114c, 114d, etc., a unique ink material (eg, different colors, different ink compositions, different opacity, etc.) is applied over the patterned fountain solution layer, Unique latent image images are formed on the image creating sections 112a, 112b, 112c, 112d, etc., respectively. The unique latent image is continuously transferred to the base 116 through the nips 122a, 122b, 122c, 122d and the like. Each re-imageable surface can then be cleaned with cleaning subsystems 124a, 124b, 124c, 124d, and the like. After each image creating unit 112a, 112b, 112c, 112d and the like transfer those latent image images to the ground 116, optionally the curing subsystem 126a, 126b, 126c, etc. (UV curing for UV curable ink) The image on 116 can be at least partially cured. A full UV cure (or other material processing) subsystem 128 can also be provided after the last ink application.

  In such an embodiment, each image creation unit includes a base on which an image can be recreated, and a unique dampening water layer that is patterned and applied with ink is provided on the base on which the image can be recreated. However, in certain embodiments, one or more of the image creators can carry a permanent image pattern, and the permanent image pattern is inked and imaged. The image is transferred to the intermediate or final base together with the image from the image re-creatable surface of the creation unit. In this way, variable printing elements and non-variable printing elements can be combined before printing on the substrate, or can be combined when printing on the substrate.

  A system having a single imaging cylinder that does not use an offset cylinder or a blanket cylinder has been described and described herein. The reimageable surface layer is made from a material that matches the roughness of the print media via a high pressure cylinder, but maintains the good tensile strength required for high volume printing. Traditionally, this mass printing is the role of an offset cylinder or blanket cylinder in an offset printing system. However, using an offset roller means additional parts maintenance and repair / part replacement issues, increased production costs, and additional energy consumption to maintain the rotational motion of the drum (or belt, plate, etc.) Suggests a larger system with Thus, although it is anticipated that the present disclosure will allow the use of offset cylinders in a complete printing system, such is not required. Instead, the layer of the image reproducible surface is directly brought into contact with the base to transfer the ink image from the layer of the image reproducible surface to the base. As a result, all of the part cost, the repair / part replacement cost, and the required operating energy can be suppressed.

  When the first layer is said to be “on” or “on” the second layer or substrate, the first layer is in direct contact with the second layer or substrate, or the first layer It goes without saying that it is in direct contact with the mediating layer (s) that can be placed between the first layer and the second layer or substrate. Further, when the first layer is said to be “on” or “on” the second layer or substrate, the first layer may be the entire second layer or substrate, or the second layer or substrate. Can be covered.

  When operating in accordance with the method described herein, the invention described herein allows the ink transfer efficiency from the image generator to the substrate to meet a high ink transfer efficiency criterion, for example, greater than 95%, In some cases, over 99%. The present disclosure also teaches combining the function of a printing cylinder with the function of an offset cylinder. Among them, a re-writable image creation surface can be made from a material that can be adapted to the roughness of the print medium via a high pressure cylinder, which is good enough for mass printing. High tensile strength. Thus, the systems and methods disclosed herein have the added advantage of reducing the number of high inertia drum components compared to typical offset printing systems. Although any number of offset ink types can be used to implement the disclosed system and method, it is particularly useful with UV lithographic inks.

  The physics of modern devices and their manufacturing methods is not absolute, but rather a statistical effort to produce the desired devices and / or results. Even if the utmost attention is paid to the reproducibility of processing, the cleanliness of manufacturing equipment, the purity of starting materials and processing materials, deformations and defects occur. Accordingly, the limitations in this description or in the claims cannot be read or should be read as absolute. The limitations of the claims are not intended to define the boundaries of this disclosure, up to and including those limitations. To further emphasize this, the term “substantially” can be used occasionally in this specification in connection with the limitations of the claims (considerations for deformations and defects are terms But not limited to that limit to use with). As a limitation of this disclosure, it is difficult to accurately define themselves, but this term is intended to be interpreted as "to a considerable extent", "almost practical", "within technical limits", etc. To do.

  Moreover, while the foregoing detailed description has presented a number of preferred exemplary embodiments, there are numerous variations and these preferred exemplary embodiments are merely shown as representative examples thereof. Of course, it is not intended to limit the scope, applicability, or configuration of the disclosure in any way. The above-disclosed and other features and functions, or alternatives thereof, can desirably be incorporated into various other systems or applications. Various alternatives, modifications, changes, or improvements in or for which it is not foreseeable or foreseeable at this time can be carried out by those skilled in the art and are also encompassed by the following claims Intended.

  Accordingly, the above description provides those skilled in the art with useful guidance for the practice of this disclosure, and without departing from the spirit and scope of this disclosure as defined by the claims thereto. It is anticipated that various changes in functionality and configuration can be performed.

Claims (4)

A marking material subsystem for a variable data lithographic printing system comprising:
A plurality of marking material assemblies, each marking material assembly comprising:
A marking material source;
A marking material transfer subsystem that receives the marking material from the marking material source and applies the marking material to the surface of the image generator ;
A marking material assembly comprising:
A control mechanism for selectively engaging / separating each of the plurality of marking material assemblies and the surface of the image creating unit ;
Only including,
A liquid layer is applied to the surface of the image creating unit,
In the liquid layer, a pattern is formed by irradiation of light,
The liquid layer includes a radiation sensitive component selected to absorb the irradiated light.
Marking material subsystem.   Each of the marking material assemblies and the image creation unit is controlled by the control mechanism such that only one of the marking material assemblies is always engaged with the surface of the image creation unit at any time. The marking material subsystem of claim 1 that controls the engagement and disengagement.   The marking material transfer subsystem includes a marking material forming roller, and the control mechanism includes an assembly that mechanically engages and separates the marking material forming roller from the surface of the image creation unit. A marking material subsystem according to claim 1.   The control mechanism causes the marking material forming roller to engage and disengage from the surface of the image creation unit, while all the remaining components of the marking material subsystem are positioned relative to the image creation unit. 4. The marking material subsystem of claim 3, wherein the marking material subsystem is fixed.

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