Intermediate Transfer Member

Abstract

An intermediate transfer member (ITM) (44) of a printing system (10), the ITM including (a) an outer layer (102) configured to receive droplets (11) of printing fluid for generating an image thereon and to transfer the image to a target substrate (50), and (b) a stack (107) of flexible support layers, the stack including a mesh (109) having (i) a first section filled with a first layer (106) having a first modulus of elasticity at an axis along which the ITM (44) is tensioned, and (ii) a second section disposed in contact with the first layer (106) and filled with a second layer (108) having a second modulus of elasticity at the axis, the second modulus of elasticity being different from the first modulus of elasticity. The stack (107) is configured to maintain a predetermined extension of the ITM (44) along the axis upon application of a specified level of tension to the ITM (44).

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 296,173, filed January 4, 2022, the disclosure of which is incorporated herein by reference.

[0002] The present invention relates generally to digital printing, and more particularly to a method and system for improving the stiffness and electrical conductivity of an intermediate transfer member. [Background technology]

[0003] Various techniques have been disclosed for improving the stiffness and electrical conductivity of intermediate members used in printing systems.

[0004] For example, US Patent No. 6,753,050 describes an image transfer sheet that includes an image-imparting layer and an adhesive layer. The adhesive layer enables the image to be transferred to a substrate.

[0005] U.S. Patent No. 9,180,659 describes an aqueous transfix blanket and a printer including the aqueous transfix blanket. The aqueous transfix blanket includes a screen layer including a plurality of mesh wires, the screen layer defining a plurality of spaces between the plurality of mesh wires. The aqueous transfix blanket further includes a first layer positioned above the screen layer and a second layer positioned below the screen layer, the plurality of spaces providing a plurality of air gaps between the first layer positioned above the screen layer and the second layer positioned below the screen layer.

[0006] US Patent No. 10,606,191 describes layered articles that can be used for indirect printing by analog or digital processes. When configured as a transfer member, the layered article can serve to receive ink in any form, allow the ink to be processed to form an ink image, and allow the ink image to be applied to a substrate. The transfer member includes a support layer and an image-forming layer that can be formed from a silicone matrix containing dispersed carbon black particles. Methods for preparing these are also disclosed.

[0007] US Patent Application Publication No. 2015 / 0210065 describes a transfer member or blanket for use in an aqueous inkjet printer. The transfer member includes a surface layer comprising an elastomeric matrix having copper particles and carbon nanotubes dispersed therein. The weight percent of the copper particles in the surface layer is about 1 weight percent to about 30 weight percent. The weight percent of the carbon nanotubes is about 1 weight percent to about 10 weight percent. Summary of the Invention

[0008] Embodiments of the invention described herein provide an intermediate transfer member (ITM) for a printing system, the ITM including (a) an outer layer configured to receive droplets of printing fluid for generating an image thereon and transfer the image to a target substrate, and (b) a stack of flexible support layers, the stack including a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity at an axis along which tension is applied to the ITM, and (ii) a second section disposed in contact with the first layer and impregnated with a second layer having a second modulus of elasticity different from the first modulus of elasticity at the axis. Upon application of a specified level of tension to the ITM, the stack of flexible support layers is configured to retain a predefined elongation of the ITM along the axis.

[0009] In some embodiments, the mesh includes woven fiberglass. In other embodiments, the second layer includes a material selected from the list of materials consisting of: (i) epoxy, (ii) polyaryletherketone (PAEK), (iii) polysaccharide, (iv) polyimide, polyethylene terephthalate, and (v) a combination of two or more of the materials in the list. In yet other embodiments, the ITM includes an additional outer layer configured to contact the ITM module, the ITM module configured to move the ITM along an axis, the additional outer layer including: (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives.

[0010] In one embodiment, the one or more conductive additives are configured to discharge static charge from the flexible substrate. In another embodiment, the conductive additives include one or more additives selected from the list of additives consisting of: (i) one or more nanotubes (NTs), (ii) one or more particles, and (iii) one or more combinations of NTs and particles. In yet another embodiment, the NTs include carbon nanotubes (CNTs) selected from the list of CNTs consisting of: (i) multi-walled CNTs (MWCNTs), (ii) single-walled CNTs (SWCNTs), and (iii) one or more combinations of MWCNTs and MWCNTs.

[0011] In some embodiments, the additional outer layer includes one of: (i) a first volume concentration of MWCNTs, (ii) a second volume concentration of SWCNTs less than the first volume concentration, and (iii) a combination of MWCNTs and SWCNTs having a third volume concentration less than the first volume concentration and greater than the second volume concentration to obtain a predetermined electrical conductivity of the additional outer layer. In other embodiments, the CNTs are configured to modify one or both of: (i) a third elastic modulus of the additional outer layer, and (ii) a thermal conductivity of the additional outer layer. In yet other embodiments, the one or more particles are selected from the list of particles consisting of: (i) metal nanoparticles (NPs), (ii) carbon-based NPs, (iii) metal-coated glass particles, (iv) graphene particles, (v) graphite particles, and (vi) a combination of two or more particles selected from the list of particles.

[0012] Further, in accordance with an embodiment of the present invention, there is provided a method of manufacturing an intermediate transfer member (ITM) of a printing system, the method including (i) manufacturing an outer layer for receiving droplets of printing fluid and generating an image thereon, and (ii) transferring the image to a target substrate. A stack of flexible support layers is manufactured by filling (i) a first section of a mesh of a first layer having a first modulus of elasticity in an axis where tension is applied to the ITM, and (ii) a second section of a mesh of a second layer, disposed in contact with the first layer and having a second modulus of elasticity in the axis, different from the first modulus of elasticity. The ITM is manufactured by integrating at least the outer layer and the stack of flexible support layers.

[0013] Further, in accordance with an embodiment of the present invention, there is provided an intermediate transfer member (ITM) of a printing system, the ITM including (a) a first outer layer configured to receive droplets of printing fluid to form an image thereon and transfer the image to a target substrate, and (b) a second outer layer configured to contact an ITM module configured to move the ITM along an axis, the second outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives.

[0014] In some embodiments, the ITM includes a stack of flexible support layers, the stack including a mesh having (i) a first section filled with a first layer having a first elastic modulus in an axis along which tension is applied to the ITM, and (ii) a second section positioned in contact with the first layer and filled with a second layer having a second elastic modulus different from the first elastic modulus in the axis, wherein the stack of flexible support layers is configured to maintain a predetermined elongation of the ITM along the axis upon application of a particular level of tension to the ITM.

[0015] According to an embodiment of the present invention, there is further provided a system including an intermediate transfer member (ITM) and an imaging station. The ITM includes (a) an outer layer configured to receive droplets of printing fluid to form an image thereon and transfer the image to a target substrate, and (b) a stack of flexible support layers, the stack including a mesh having (i) a first section filled with a first layer having a first modulus of elasticity in an axis along which tension is applied to the ITM, and (ii) a second section disposed in contact with the first layer and filled with a second layer having a second modulus of elasticity in the axis, the second section being different from the first modulus of elasticity. Upon application of a specified level of tension to the ITM, the stack of flexible support layers is configured to hold a predefined extension of the ITM along the axis. The imaging station is configured to apply droplets of printing fluid to the ITM.

[0016] In some embodiments, the system includes an impression station configured to engage between the ITMs and the target substrate at an engagement point to transfer an image from the ITMs to the target substrate.

[0017] According to an embodiment of the present invention, a system including an intermediate transfer member (ITM) and an imaging station is further provided. According to an embodiment of the present invention, a printing system intermediate transfer member (ITM) is further provided, the ITM includes (a) a first outer layer configured to receive droplets of printing fluid to form an image thereon and transfer the image to a target substrate, and (b) a second outer layer configured to contact an ITM module configured to move the ITM along an axis, the second outer layer includes (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along an axis, and (ii) one or more conductive additives. The imaging station is configured to apply droplets of printing fluid to the ITM.

[0018] Further, according to an embodiment of the present invention, there is provided an intermediate transfer member (ITM) of a printing system, the ITM including: (a) an outer layer configured to contact an ITM module configured to move the ITM along an axis, the outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; and (b) a stack of flexible support layers, the stack including a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity at an axis along which tension is applied to the ITM, and (ii) a second section disposed in contact with the first layer and impregnated with a second layer having a second modulus of elasticity different from the first modulus at the axis. Upon application of a specified level of tension to the ITM, the stack of flexible support layers is configured to retain a predefined elongation of the ITM along the axis.

[0019] Further, in accordance with an embodiment of the present invention, there is provided a method of manufacturing an intermediate transfer member (ITM) for a printing system, the method comprising: (i) manufacturing a first layer, which is an outer layer of the ITM for receiving droplets of printing fluid to generate an image thereon, and (ii) transferring the image to a target substrate. A second layer is bonded to the first layer. The second layer includes a matrix that holds particles in their respective predetermined positions, such that upon receiving optical radiation that passes through the first layer, the particles heat the ITM by absorbing at least a portion of the optical radiation.

[0020] In some embodiments, the method includes producing the second layer by integrating particles into a matrix, disposing the particles within the bulk of the matrix at a predetermined distance from each other and from the interface between the first layer and the second layer.

[0021] Further, in accordance with an embodiment of the present invention, there is provided an intermediate transfer member (ITM) of a printing system, the ITM including: (a) a first outer layer configured to receive droplets of printing fluid to form an image thereon and transfer the image to a target substrate; (b) an inner layer coupled to the first outer layer, the second layer including a matrix configured to hold particles at respective predetermined positions, the second layer configured to receive optical radiation passing through the first outer layer, the particles configured to heat the ITM by absorbing at least a portion of the optical radiation; and (c) a second outer layer configured to contact an ITM module configured to move the ITM along an axis, the second outer layer including: (i) a flexible substrate configured to conform to one or more components of the ITM module and have a predetermined friction with at least one of the one or more components to move the ITM along the axis; and (ii) one or more conductive additives.

[0022] According to an embodiment of the present invention, an intermediate transfer member (ITM) of a printing system is provided, the ITM including: (a) an inner layer coupled to a first outer layer that receives droplets of printing fluid for generating an image thereon and transfers the image to a target substrate, the second layer including a matrix configured to hold particles in respective given positions, the second layer configured to receive optical radiation passing through the first outer layer, the particles configured to heat the ITM by absorbing at least a portion of the optical radiation; and (b) a second outer layer configured to be placed in contact with an ITM module, the ITM module configured to move the ITM along an axis, the second outer layer including: (i) a flexible substrate configured to conform to one or more components of the ITM module and have a predetermined friction with at least one of the one or more components to move the ITM along the axis; and (ii) one or more conductive additives.

[0023] The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken in conjunction with the drawings, in which: [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic side view of a digital printing system according to one embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view of a blanket for a digital printing system according to an embodiment of the present invention. [Diagram 3] 3A-3C are schematic cross-sectional views of a process sequence for manufacturing the blanket depicted in FIG. 2 according to one embodiment of the present invention. [Figure 4] 3 is a flow chart that generally illustrates a method for improving the stiffness and electrical conductivity of the blanket illustrated in FIG. 2, in accordance with one embodiment of the present invention. [Diagram 5] 3 is a schematic cross-sectional view of a blanket having a different structure than that of FIG. 2 above, according to another embodiment of the present invention. [Figure 6] 6A-6C are schematic cross-sectional views of a process sequence for manufacturing the blanket of FIG. 5, in accordance with one embodiment of the present invention. [Figure 7] 6 is a flow chart that generally illustrates a method for manufacturing the blanket of FIG. 5, in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] overview Some printing systems include an intermediate member configured to receive an image and transfer the image to a target substrate. In some cases, the intermediate member includes a flexible member formed into an infinite loop and having one or more panels intended to receive one or more of the images. The infinite loop and flexibility of the intermediate member is necessary to rotate the intermediate member multiple times such that (i) with each rotation, one or more panels transfer one or more images to the target substrate, and (ii) with the next rotation, one or more panels are ready to receive the next image(s). The target substrate can include one or more sheets, a continuous web, or other suitable substrate, and the intermediate member is moved using any suitable movement device, such as motorized rollers.

[0026] It should be noted that excessive elasticity of the intermediate member (i.e., higher than a specified value) may result in one or more types of distortions in the printed image, such as registration errors. Furthermore, as the intermediate member is moved, friction between the rollers and the intermediate member may result in unwanted electrostatic charging of the intermediate member. The unwanted charging may (i) damage components of the printing system (e.g., due to unwanted discharges that may occur between components of the system) and (ii) cause distortions in the printed image (e.g., ink droplets jetted onto the surface of the blanket may bend in an undesirable direction).

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention described below provide an efficient method and system for improving the stiffness and electrical conductivity of an intermediate transfer member (ITM) in a digital printing system.

[0028] In some embodiments, a digital printing system includes a print assembly having (i) an imaging station configured to apply droplets of printing fluid (e.g., eject ink droplets) to a surface of the ITM, also referred to herein as a blanket, to generate an image thereon, (ii) an impression station configured to transfer the image from the blanket to a target substrate (e.g., a sheet), and (iii) a blanket module configured to move the blanket (a) to generate the image by receiving ink droplets from the imaging station, and (b) to transfer the image to the sheet. The digital printing system further includes a processor configured to control the print assembly.

[0029] In this example, the blanket includes a flexible member formed into an infinite loop having (a) a plurality of panels, each panel intended to receive an image, and (b) one or more sections not intended to receive an image. The blanket module is configured to rotate the blanket through a plurality of revolutions, and at each panel and each revolution, the processor controls the printing assembly to generate an image and subsequently transfer the image to the sheet, such that at the next revolution, each of the panels is ready to receive the next image.

[0030] In some embodiments, the blanket includes a laminate, such as (i) a release layer, (ii) one or more skeleton layer(s), (iii) a grip layer, and additional layers as described in detail below in Figures 2-3 and 5-6. It should be noted that the release layer and the grip layer are disposed at first and second respective outer ends of the blanket laminate, and thus are also referred to herein as the first and second outer layers, respectively.

[0031] In some embodiments, the release layer includes an ink-receptive surface configured to receive an ink image and transfer the ink image to a target substrate. In some printing applications, it may be necessary to at least partially dry droplets of a printing fluid (such as ink) using optical radiation, such as, but not limited to, infrared (IR) radiation, directed at a surface of the release layer. In some embodiments, the blanket includes an infrared (IR) layer bonded to the release layer and substantially opaque to infrared (IR) radiation. The IR layer has a matrix including a suitable type of silicone and carbon black (CB) particles embedded within the matrix of the IR layer.

[0032] In some embodiments, the IR layer is configured to receive IR radiation that passes through the release layer, and in response to the IR radiation, the CB particles are configured to heat at least the IR layer and the release layer of the ITM so as to at least partially dry ink droplets applied to the release layer.

[0033] In some embodiments, the CB particles are incorporated (e.g., embedded) in the silicone matrix and positioned within the bulk of the matrix of the IR layer at a predetermined distance from each other and from the outer surface of the release layer. In such embodiments, due to the low thermal conductivity of the silicone matrix, the heat emitted from the CB particles is typically uniformly distributed within the IR layer and the release layer, thereby allowing the ink to dry at least partially uniformly across the outer surface of the release layer.

[0034] In some embodiments, the grip layer has a high friction surface and is configured to provide physical contact between the blanket and a blanket module having rollers and other components for moving the blanket in said rotation. In some embodiments, the grip layer includes a matrix made from (i) a flexible material(s), such as silicone or other suitable material, and (ii) an electrically conductive additive, such as, but not limited to, carbon nanotubes (CNTs), embedded in the silicone matrix and configured to improve the electrical conductivity of the grip layer.

[0035] As previously mentioned, as the blanket is moved by the blanket module, friction between the gripping layer and components of the blanket module (such as the rollers and dancers shown in FIG. 1) can cause unintended and unwanted static electricity to be generated on the blanket. In some embodiments, the improved electrical conductivity of the gripping layer achieved by implementing CNT additives embedded in a silicone matrix reduces and typically eliminates the static electricity effect, thereby preventing damage to the printing system and distortion(s) of the printed image.

[0036] In some embodiments, one or more of the skeleton layer(s) includes a fiberglass fabric made from a woven mesh of glass fibers impregnated with one or more materials, as shown in detail in Figures 2-3 and 5-6 below. In one implementation, a first section of the fiberglass fabric is impregnated with an elastic layer, such as a silicone elastomer (e.g., vinyl-terminated polydimethylsiloxane (PDMS)), and a second section of the fiberglass fabric is impregnated with a layer that is stiffer than silicone, such as an epoxy layer, disposed between the grip layer and the silicone layer. In this implementation, (i) the silicone layer maintains sufficient flexibility of the blanket required to receive and transfer images, as described above, and (ii) the epoxy layer improves the stiffness of the blanket (e.g., spring constant, as described in detail in Figure 2 below) to control the stability of a specified dimension of the moved blanket. It should be noted that improving the stability of the blanket dimensions reduces the frequency of blanket replacement, improving the availability and output of the printing system. In another implementation, a fiberglass fabric made from a woven mesh of glass fibers is impregnated with an elastic layer. For example, the mesh is filled with a clear silicone elastomer such as PDMS. Note that in this implementation, the mesh is not filled with any kind of epoxy layer. In yet another embodiment, the mesh may be filled with only an epoxy layer and not with PMDS.

[0037] The disclosed technology improves (i) the quality of images printed in digital printing systems having an intermediate transfer member, (ii) the productivity of such systems, and (iii) the costs associated with sequential printing of batches of images.

[0038] System Description 1 is a schematic side view of a digital printing system 10 according to an embodiment of the present invention. In some embodiments, the system 10 includes a rotating flexible blanket 44 that circulates through an imaging station 60, a drying station 64, an impression station 84, and a blanket treatment station 52. In the context of the present invention and in the claims, the terms "blanket" and "intermediate transfer member (ITM)" are used interchangeably and refer to a flexible member that includes one or more layers used as an intermediate member formed in an endless loop. The endless loop is configured to receive an ink image, for example from the imaging station 60, and transfer the ink image to a target substrate, as described in more detail below.

[0039] In an operational mode, imaging station 60 is configured to form a mirror ink image (herein referred to as an "ink image" (not shown) or for simplicity as an "image") of digital image 42 on an upper run of the surface of blanket 44. The ink image is then transferred to a target substrate (e.g., paper, folding carton, multi-layer polymer, or any suitable flexible packaging in the form of a sheet or continuous web) disposed beneath the lower run of blanket 44.

[0040] In the context of the present invention, the term "run" refers to the length or segment of blanket 44 between any two given rollers along which blanket 44 is guided.

[0041] In some embodiments, during installation, blanket 44 may be bonded edge-to-edge using a seam portion (also referred to herein as seam 45), thereby forming a continuous blanket loop (also referred to herein as a closed loop). Exemplary methods and systems for attaching seams are described in detail in U.S. Patent Application Publication No. 2020 / 0171813, the disclosure of which is incorporated herein by reference.

[0042] In some embodiments, imaging station 60 typically includes a plurality of print bars 62, with each print bar 62 mounted on a frame (not shown) positioned at a fixed height above the surface of an upper run of blanket 44. In some embodiments, each print bar 62 includes a strip of print heads that are the same width as the print area on blanket 44, and include individually controllable print nozzles that are configured to eject ink and other types of printing fluids onto blanket 44, as described in more detail below.

[0043] In some embodiments, imaging station 60 may include any suitable number of print bars 62 (also referred to herein as bars 62 for simplicity). Each bar 62 may include a printing fluid, such as a water-based ink, of a different color. The inks typically have visible colors, such as, but not limited to, cyan, magenta, red, green, blue, yellow, black, and white. In the example of FIG. 1, imaging station 60 includes seven print bars 62, but may include, for example, four print bars 62 having any selected color, such as cyan (C), magenta (M), yellow (Y), and black (K).

[0044] In some embodiments, the print heads are configured to eject ink droplets of different colors onto the surface of blanket 44 to form ink images (not shown) on the surface of blanket 44. In this example, blanket 44 is moved along the X-axis of an XYZ coordinate system of system 10, and the ink droplets are directed by the print heads, typically parallel to the Z-axis of the coordinate system.

[0045] In some embodiments, the different print bars 62 are spaced apart from one another along an axis of movement (also referred to herein as (i) the direction of movement 94 of the blanket 44 or (ii) the printing direction). In this example, the direction of movement of the blanket 44 is parallel to the X-axis, and each print bar 62 extends along the Y-axis of the XYZ coordinate system 10. In this configuration, precise spacing between the bars 62 along the X-axis, and synchronization between the delivery of ink drops of each bar 62 and the movement of the blanket 44, is essential to enable correct placement of the image pattern.

[0046] In the context of this disclosure and the claims, the terms “inter-color pattern placement,” “pattern placement accuracy,” “inter-color alignment,” “C2C alignment,” and “color alignment” are used interchangeably and refer to any placement accuracy of two or more colors relative to one another.

[0047] In some embodiments, system 10 includes a heater 66, such as an infrared-based heater with a hot gas or air blower and / or a gas or air blower for flowing gas or air at any suitable temperature. Heater 66 is positioned between print bars 62 and configured to partially dry ink drops deposited on the surface of blanket 44. This air flow between print bars can help, for example, (i) reduce condensation on the surface of the print head and / or handle satellites (e.g., residue or small drops distributed around the main ink drop), and / or (ii) prevent clogging of the orifices of the inkjet nozzles of the print head, and / or (iii) prevent drops of different colors of ink on blanket 44 from undesirably blending into one another.

[0048] In some embodiments, system 10 includes a drying station 64. Drying station 64 is configured to deliver infrared radiation and cooling air (or other gas) and / or blow hot air (or other gas) onto a surface of blanket 44. In some embodiments, drying station 64 may include an infrared-based lighting assembly (not shown) and / or an air blower 68 or any other suitable drying device.

[0049] In some embodiments, at drying station 64, the ink image formed on blanket 44 is exposed to radiation and / or hot air to more completely dry the ink, evaporating most or all of the liquid carrier and leaving behind only a layer of resin and colorant that has been heated to the point of becoming a tacky ink film.

[0050] In some embodiments, system 10 includes a blanket module 70 (also referred to herein as an ITM module) that includes a rotating flexible ITM, such as blanket 44. In some embodiments, blanket module 70 includes one or more rollers 78. At least one of rollers 78 includes a motion encoder (not shown). The motion encoder is configured to record the position of blanket 44 in order to control the position of sections of blanket 44 relative to respective print bars 62. In some embodiments, one or more motion encoders may be integrated with additional rollers and other moving components of system 10.

[0051] In some embodiments, such motion encoders typically include at least one rotary encoder configured to generate rotation-based position signals indicative of the angular displacement of the respective rollers. It should be noted that in the context of the present invention and the claims, the terms "indicating" and "indicating" are used interchangeably.

[0052] Additionally or alternatively, blanket 44 may include an integrated encoder (not shown) for controlling the operation of various modules of system 10. One implementation of an integrated motion encoder is described in detail, for example, in PCT International Publication Nos. WO2021 / 044303 and WO2020 / 003088, the disclosures of which are incorporated herein by reference in their entireties.

[0053] In some embodiments, blanket 44 is guided in blanket module 70 over rollers 76, 78 and other rollers described herein, as well as a powered tensioning roller (also referred to herein as dancer assembly 74). Dancer assembly 74 is configured to control the amount of slack in blanket 44, the movement of which is shown diagrammatically in FIG. 1 by a double-headed arrow. Furthermore, slight stretching of blanket 44 due to aging does not affect the ink image placement performance of system 10, and only requires that more slack be taken up by tensioning dancer assembly 74.

[0054] In some embodiments, dancer assembly 74 may be motorized. The configuration and operation of rollers 76 and 78 are described in more detail, for example, in U.S. Patent Application Publication No. 2017 / 0008272 and the aforementioned PCT International Publication No. WO2013 / 132424, the disclosures of which are incorporated herein by reference in their entireties.

[0055] In some embodiments, the system 10 includes a blanket tension drive roller (BTD) 99 and a blanket control drive roller (BCD) 77, which are driven by first and second motors, respectively (typically electric motors (not shown)), and configured to rotate about their own first and second axes, respectively.

[0056] In some embodiments, system 10 may include one or more tension sensors (not shown) positioned at one or more locations along blanket 44. The tension sensors may be incorporated within blanket 44 or may include sensors external to blanket 44 using any other suitable technique for obtaining a signal indicative of the mechanical tension applied to blanket 44. In some embodiments, processor 20 and additional controllers of system 10 are configured to receive signals generated by the tension sensors to monitor the tension applied to blanket 44 and control the operation of dancer assembly 74.

[0057] At impression station 84, blanket 44 passes between impression cylinder 82 and pressure cylinder 90, which are configured to hold a compressible blanket (shown below in FIG. 3). In some embodiments, a motion encoder is integrated with at least one of impression cylinder 82 and pressure cylinder 90.

[0058] In some embodiments, system 10 includes a control console 12. Control console 12 is configured to control multiple modules of system 10, such as a blanket module 70, an imaging station 60 disposed above the blanket module 70, and a substrate transport module 80. Substrate transport module 80 is disposed below blanket module 70 and includes one or more impression stations, as described below.

[0059] In some embodiments, console 12 includes a processor 20 (typically a general purpose processor) having suitable front end and interface circuitry for interfacing with and receiving signals from the controller of dancer assembly 74 and controller 54 via cable 57. Additionally or alternatively, console 12 may include any suitable type of application specific integrated circuit (ASIC) and / or digital signal processor (DSP) and / or any other suitable type of processing unit configured to perform any type of processing on data processed in system 10.

[0060] In some embodiments, the controller 54 (shown diagrammatically as a single device) may include one or more electronic modules mounted at predetermined locations on the system 10. At least one of the electronic modules of the controller 54 may include an electronic device, such as a control circuit or processor (not shown), configured to control the various modules and stations of the system 10. In some embodiments, the processor 20 and control circuitry may be programmed in software to perform functions used by the printing system and store data for the software in the memory 22. The software may be downloaded to the processor 20 and control circuitry in electronic form, for example over a network, or may be provided on a non-transitory tangible medium, such as an optical, magnetic, or electronic memory medium.

[0061] In some embodiments, the console 12 includes a display 34. The display 34 is configured to display data and images received from the processor 20, or input inserted by a user (not shown) using an input device 40. In some embodiments, the console 12 may have any other suitable configuration, for example, alternative configurations of the console 12 and display 34 are described in detail in U.S. Patent No. 9,229,664, the disclosure of which is incorporated herein by reference.

[0062] In some embodiments, the processor 20 is configured to display on the display 34 a digital image 42 including one or more segments (not shown) of the image 42, and / or various types of test patterns that may be stored in the memory 22.

[0063] In some embodiments, the blanket treatment station 52 (also referred to herein as a cooling station) is configured to treat the blanket, for example, by cooling it and / or applying a treatment fluid to the outer surface of the blanket 44 and / or cleaning the outer surface of the blanket 44. The blanket treatment station 52 can reduce the temperature of the blanket 44 to a desired temperature level before the blanket 44 enters the imaging station 60. Treatment may be performed by passing the blanket 44 over one or more rollers or blades configured to cool and / or clean and / or apply a treatment fluid to the outer surface of the blanket.

[0064] In some embodiments, the blanket treatment station 52 may further include one or more bars (not shown) positioned adjacent to the print bar 62 so that treatment fluid may be applied to the blanket 44 by spraying in addition to or instead of the print bar 62.

[0065] In some embodiments, the processor 20 is configured to receive a signal indicative of the temperature of the surface blanket 44, for example from a temperature sensor (not shown), to monitor the temperature of the blanket 44 and control operation of the blanket treatment station 52. Examples of such treatment stations are described, for example, in PCT International Publication Nos. WO 2013 / 132424 and WO 2017 / 208152, the disclosures of which are incorporated herein by reference in their entireties.

[0066] 1, station 52 is mounted between impression station 84 and imaging station 60, however, station 52 may be mounted adjacent blanket 44 at any other or additional suitable location or locations between impression station 84 and imaging station 60. As previously mentioned, station 52 may additionally or instead be mounted on a bar adjacent imaging station 60.

[0067] 1, impression cylinder 82 and pressure cylinder 90 impress an ink image onto a target flexible substrate, such as individual sheet 50, which is transported by substrate transport module 80 through impression station 84 from input stack 86 to output stack 88. In this example, a rotary encoder (not shown) is integrated with impression cylinder 82.

[0068] In some embodiments, the lower run of blanket 44 selectively interacts with impression cylinder 82 at impression station 84 to impress an image pattern onto a target flexible substrate compressed between blanket 44 and impression cylinder 82 under the action of pressure from pressure cylinder 90. For a single-sided press (i.e., printing on one side of sheet 50) as shown in FIG. 1, only one impression station 84 is required.

[0069] In other embodiments, the module 80 may include two or more impression cylinders (not shown) to allow for one or more duplex printing. The two impression cylinder configuration allows for single-sided printing to be performed twice as fast as duplex printing. In addition, mixed lots of single-sided and double-sided printing may be printed. In alternative embodiments, a different configuration of the module 80 may be used to print on a continuous web substrate. Detailed descriptions and various configurations of double-sided printing systems and systems for printing on continuous web substrates are provided, for example, in U.S. Pat. Nos. 9,914,316 and 9,186,884, PCT International Publication No. WO 2013 / 132424, U.S. Patent Application Publication No. 2015 / 0054865, and U.S. Provisional Application No. 62 / 596,926, the disclosures of which are incorporated herein by reference in their entirety.

[0070] In some embodiments, a sheet 50 or continuous web substrate (not shown) is carried by module 80 from an input stack 86 and passes through a nip (not shown) disposed between impression cylinder 82 and pressure cylinder 90. Within the nip, the surface of blanket 44 bearing the ink image is pressed firmly against sheet 50 (or other suitable substrate) by, for example, a compressible blanket of pressure cylinder 90, such that the ink image is pressed onto the surface of sheet 50 and cleanly separated from the surface of blanket 44. The sheet 50 is then transported to an output stack 88.

[0071] 1, roller 78 is positioned on the upper run of blanket 44 and is configured to maintain blanket 44 taut as it passes adjacent imaging station 60. Additionally, for imaging station 60 to form an image on the surface of blanket 44, it is particularly important to control the speed of blanket 44 beneath imaging station 60 to obtain accurate jetting and deposition of ink droplets.

[0072] In some embodiments, the impression cylinder 82 is periodically engaged and disengaged from the moving blanket 44 to transfer an ink image from the blanket 44 to a target substrate passing between the blanket 44 and the impression cylinder 82. In some embodiments, the system 10 is configured to apply a torque to the blanket 44 using the roller and dancer assemblies described above to maintain the upper run taut and substantially isolate the upper run of the blanket 44 from the effects of mechanical vibrations experienced in the lower run.

[0073] In some embodiments, system 10 includes image quality control station 55 (also referred to herein as an automated quality control (AQM) system), which functions as a closed-loop inspection system integrated into system 10. In some embodiments, image quality control station 55 may be positioned adjacent impression cylinder 82, as shown in FIG. 1, or may be positioned in any other suitable location within system 10.

[0074] In some embodiments, image quality control station 55 includes a camera (not shown) configured to capture one or more digital images of the aforementioned ink images printed on sheet 50. In some embodiments, the camera may include any suitable image sensor, such as a contact image sensor (CIS) or a complementary metal oxide semiconductor (CMOS) image sensor, and a scanner including a slit having a width of about one meter or any other suitable width.

[0075] In the context of this disclosure and the claims, the term "about" or "approximately" in relation to any numerical value or range indicates a suitable dimensional tolerance that enables the collection of parts or components to function for its intended use as described herein.

[0076] In some embodiments, the digital images acquired by station 55 are sent to a processor, such as processor 20 or any other processor of station 55, configured to evaluate the quality of each printed image. Based on the evaluation and signals received from controller 54, processor 20 is configured to control the operation of the modules and stations of system 10. In the context of the present invention and the claims, the term "processor" refers to any processing unit, such as processor 20 or any other processor or controller, connected to or integrated with station 55, which is configured to process signals received from the camera and / or spectrophotometer of station 55. It should be noted that the signal processing operations, control-related instructions, and other computational operations described herein may be performed by a single processor or may be shared among multiple processors of one or more individual computers.

[0077] In some embodiments, station 55 is configured to inspect the quality of the printed images and test patterns to monitor various attributes such as, but not limited to, perfect image alignment with sheet 50 (also referred to herein as image-to-substrate alignment), color-to-color (C2C) alignment, printed features, image uniformity, color profile and linearity, and print nozzle functionality. In some embodiments, processor 20 is configured to automatically detect geometric distortions or other errors in one or more of the aforementioned attributes.

[0078] In some embodiments, the processor 20 is configured to analyze the detected distortions in order to apply corrective actions to the malfunctioning module and / or send instructions to other modules or stations of the system 10 to compensate for the detected distortions.

[0079] In some embodiments, system 10 may print testing marks (not shown) or other suitable features, for example, on the chamfer or edges of sheets 50. By acquiring images of the testing marks, station 55 is configured to measure various types of distortions, for example, C2C alignment, image-to-substrate alignment, different widths between colors (referred to herein as "bar-to-bar width delta" or "color-to-color width difference"), various types of local distortions, and front-to-back registration errors (in duplex printing). In some embodiments, processor 20 is configured to (i) sort sheets 50 having distortions that exceed a first set of predefined thresholds, for example, to a reject tray (not shown), (ii) initiate corrective action for sheets 50 having distortions that exceed a second, lower set of predefined thresholds, and (iii) output sheets 50 having minor distortions (e.g., below the second set of thresholds) to output stack 88.

[0080] In some embodiments, processor 20 is configured to detect deviations in the profile and linearity of the printed colors based on signals received from the spectrophotometers of stations 55 .

[0081] In some embodiments, the processor of station 55 is configured to determine whether to stop operation of system 10, for example, if the density of distortion exceeds a specified threshold. The processor of station 55 is further configured to initiate corrective action in one or more of the modules and stations of system 10, as described above. In some embodiments, corrective action may be performed on-the-fly (while system 10 continues the printing process) or offline, by stopping printing operations and repairing the problem in the respective module and / or station of system 10. In other embodiments, any other processor or controller of system 10 (e.g., processor 20 or controller 54) is configured to initiate corrective action or stop operation of system 10, if the density of distortion exceeds a specified threshold.

[0082] Additionally or alternatively, processor 20 is configured to receive signals, for example from station 55, indicative of additional types of distortions and problems in the printing process of system 10. Based on these signals, processor 20 is configured to automatically estimate the level of pattern placement accuracy and additional types of distortions and / or defects not previously described. In other embodiments, any other suitable method for inspecting the patterns printed on sheet 50 (or any other substrate previously described) may be used, for example using an external (e.g., offline) inspection system, or any type of measurement fixture and / or scanner. In these embodiments, based on information received from the external inspection system, processor 20 is configured to initiate any suitable corrective action and / or stop operation of system 10.

[0083] The configuration of the system 10 is shown as a simplified example only for clarity of the present invention. The components, modules, and stations described in the printing system 10, as well as further components and configurations, are described in detail in the following documents: U.S. Patent Nos. 9,327,496 and 9,186,884, PCT International Publication Nos. WO2013 / 132438, WO2013 / 132424, and WO2017 / 208152, and U.S. Patent Application Publication Nos. 2015 / 0118503 and 2017 / 0008272, the disclosures of which are incorporated herein by reference in their entirety.

[0084] The particular configuration of system 10 is presented as an example to illustrate the particular problems addressed by embodiments of the present invention and to show the application of these embodiments in improving the performance of such systems, but embodiments of the present invention are in no way limited to this particular type of example system, and the principles described herein may be applied to any other type of printing system as well.

[0085] Control of blanket elasticity and electrical conductivity The flexibility of blanket 44 is essential to perform image reception and transmission as described above in Figure 1. Additionally, the elastic modulus (also referred to as the modulus of elasticity) of blanket 44 typically determines the stiffness or flexibility of blanket 44 in response to a force (e.g., tension) applied to blanket 44 in multiple axes or in a particular axis or direction.

[0086] In this example, the elastic modulus is a constant that measures the resistance of blanket 44 to elastically (i.e., non-permanently) deforming when a stress (e.g., tension) is applied to blanket 44 by system 10 (e.g., blanket module 70). It should be noted that the elastic modulus of a particular element (e.g., blanket 44) may vary with respect to axis. For example, as shown in FIG. 1 above, blanket 44 is subjected to the greatest tension in the X-axis. Thus, in some embodiments, blanket 44 is configured to have the greatest elastic modulus along the X-axis.

[0087] In some cases, uncontrolled deformation of blanket 44 can result in distorted printed images. In one example, if deformation occurs on a portion of blanket 44 while receiving ink drops (e.g., from print bar 62), C2C registration errors can occur in the printed image. In another example, if deformation occurs on a portion of blanket 44 while transferring the image to sheet 50, image-to-substrate registration errors can occur in the printed image.

[0088] The elastic modulus of the blanket 44, in the tests described herein, is defined as the slope of the stress-strain curve in the region of elastic deformation. Thus, a stiffer blanket 44 may have a higher elastic modulus in one or more axes of symmetry.

[0089] In some embodiments, different amounts of tension are applied simultaneously to different sections of blanket 44. Different tension amounts are used to maintain different levels of tension in the blanket as it is moved to different locations within system 10. For example, the tension (e.g., in direction 94) applied to blanket 44 must be (i) very precisely controlled when it passes near imaging station 60 (to prevent C2C registration errors) and (ii) less precisely controlled when it passes between impression station 84 and blanket handling station 52. Furthermore, the different controlled levels of tension can result in cyclical levels of stretching of blanket 44 as it is moved to different locations within system 10. Thus, blanket 44 exhibits a spring behavior, and thus the measured spring constant of blanket 44 is indicative of its elastic modulus.

[0090] In the context of this disclosure and in the claims, the terms "rigid," "hard," and "firm" and grammatical variations thereof (e.g., stiffness, hardness, and firmness) are used interchangeably and refer to the resistance of blanket 44 to elastic deformation when tension is applied to blanket 44.

[0091] In some embodiments, the inventors have developed a method for using a suitable test product to test and measure the spring constant of the blanket 44. In this example, the inventors used a tension gauge product from the Lloyd Materials Testing Equipment product line supplied by Ametek Inc. (Berwyn, PA) or other suitable supplier.

[0092] In some embodiments, the test procedure involves applying about 20 cycles of tension (e.g., a gradually increasing force or a constant force) of about 2 Newtons (N) to 20 N to a section about 20 mm wide and about 150 mm long, measured along the X and Y axes, respectively, of the XYZ coordinate system shown in Figure 1. Tension was applied along the X, Y, and diagonal directions at about 45° to the X and Y axes at a rate of about 20 mm / min.

[0093] In some embodiments, the above test procedures and settings were applied to various configurations of blanket 44, as shown below in Figure 2. The spring constants of blanket 44, which indicate the stiffness of the blanket, were calculated to select the optimal blanket 44 configuration for each printing application performed with system 44.

[0094] In some cases, as the blanket 44 moves, friction between the blanket 44 and various components of the system 10 (e.g., rollers 76 and 78, BCD 77, BTD 99, dancer assembly 74) can cause unwanted static electricity to build up on the blanket 44. The unwanted charge can be discharged and cause damage to various components of the system 10. For example, the accumulated charge can be conducted toward the print bar 62 through ink drops that land on the blanket surface and cause damage to one or more print nozzles. Additionally, the charge trapped on the blanket 44 can cause ink drops that are jetted toward the surface of the blanket 44 to be deflected in an undesirable direction. The deflection of one or more ink drops from their intended location to another location can cause distortion in the image printed by the system 10.

[0095] In the embodiment described below in FIG. 2, several configurations of blanket 44 can be used to address the above-mentioned problems of uncontrolled deformation and charging of blanket 44.

[0096] Figure 2 is a schematic cross-sectional view of a blanket 44 according to an embodiment of the present invention. In the example of Figure 2, a portion of blanket 44 is moved in direction 94 between one print bar 62 (shown in Figure 1 above) and one roller 78 rotating clockwise, and the cross-section is shown in Figure 2.

[0097] In some embodiments, blanket 44 includes a release layer 102 having an ink-receptive surface 103 configured to (i) receive droplets 11 of printing fluid(s) from print bar 62 to generate an image thereon (also referred to herein as an ink image), and (ii) transfer the image to sheet 50. It is noted that the outer layer of blanket 44, release layer 102, and particularly surface 103, is configured to provide a low release force to the ink image, as measured by the wetting angle between surface 103 and the ink image (also referred to herein as the receding contact angle (RCA)).

[0098] In some embodiments, the release layer 102 is made from a typically transparent silicone elastomer, such as vinyl-terminated polydimethylsiloxane (PDMS), or any other suitable type of silicone polymer, or any other suitable material. In this example, the release layer may typically have a thickness of about 10 μm to 70 μm, or may have any other suitable thickness (e.g., greater than about 10 μm).

[0099] In some embodiments, blanket 44 includes an infrared layer (IR) 101 that can be used with blanket 44 in printing applications that require infrared irradiation of blanket 44 by drying station 64, as described above in FIG. 1.

[0100] In some embodiments, the IR layer 101 has an exemplary thickness of about 30 μm to 150 μm and is configured to absorb, for example, all, or at least a majority of, the IR radiation of the IR beam emitted from the drying station 64. For example, the confined IR layer 101 is adapted to absorb, within its top 5 μm, about 50% of the IR radiation of the IR beam. In other words, the IR layer 101 is substantially opaque to the IR beam.

[0101] In some embodiments, the IR layer 101 is added to the release layer 102 and has one surface that interfaces with the release layer 102 and another surface that interfaces with another layer 104, which is described in more detail below.

[0102] In some embodiments, the IR layer 101 comprises a matrix made from silicone (such as PDMS) and a plurality of particles disposed at specific locations within the bulk of the PDMS matrix of the IR layer 101. In some embodiments, the particles comprise a suitable type of pigment, such as, but not limited to, commercially available carbon black (CB) particles, each with a typical diameter range of about 10 μm (for an IR layer about 30 μm thick) to 30 μm (for an IR layer about 50 μm thick).

[0103] In some embodiments, the particles are embedded in the bulk of the IR layer 101 within a distance of about 10 μm or 20 μm from said surface of the IR layer. The particles are uniformly arranged along the IR layer 101 at a distance of about 0.1 μm to 5 μm from each other. In other embodiments, the distance to the surface of the IR layer 101 and the distance between the particles can vary between different blankets, for example, at least one particle can be in close proximity to or touching any surface of the IR layer 101.

[0104] Additional embodiments relating to the IR layer 101 and other variations of IR layers, and the manufacture of blankets 44 having the above-described IR layer, are described in more detail in PCT International Publication No. WO2021 / 105806, the disclosure of which is incorporated herein by reference. Additionally, some embodiments relating to the manufacture of blankets 44 having IR layer 101 are also described below in Figures 5 and 6.

[0105] In some embodiments, blanket 44 includes a conformal layer 104 (also referred to herein as a compliant layer), typically made from PDMS with a black pigment additive. Conformal layer 104 is bonded to IR layer 101, or to release layer 102 if IR layer 101 is excluded from blanket 44. In such embodiments, the conformal layer may typically have a thickness of about 50 μm to 400 μm, or any other suitable thickness.

[0106] In some embodiments, conformal layer 104 is configured to attenuate a substantial intensity of light at selected wavelengths from being transmitted and / or reflected.

[0107] It will be appreciated that the level of attenuation will depend on various parameters, such as the thickness of the layers and the wavelength of light emitted by the sensing assembly. For example, UV wavelengths (e.g., about 10 nm to 400 nm) may be attenuated more than visible light (400 nm to 700 nm) and infrared (IR) wavelengths (e.g., about 700 nm to 1 mm).

[0108] In some embodiments, the conformal layer 104 may have different mechanical properties (e.g., greater resistance to tension) than the release layer 102. Such desired property differences can be obtained, for example, by utilizing a different composition for the release layer 102, by changing the ratio between the components used to prepare the release layer 102 formulation, and / or by adding additional components to such formulation, and / or by selecting different curing conditions during the manufacturing process of the blanket 44. For example, implementing a filler particle additive (not shown) in the PMDS of the conformal layer 104 may increase the mechanical strength of the conformal layer 104 relative to the release layer 102.

[0109] In some embodiments, conformal layer 104 has a hardness (and other elastic properties) that enables release layer 102 and surface 103 to conform (i.e., closely follow) the surface contours of a substrate (e.g., sheet 50) upon which the ink image is imprinted.

[0110] In some embodiments, blanket 44 includes a reinforcing laminate, also referred to herein as a stack of flexible support layers 107 or a skeleton of blanket 44, which are bonded to conformal layer 104 and are described in more detail below. In some embodiments, support layer 107 is configured to provide blanket 44 with the necessary flexibility in the X, Y and Z axes, and further improve mechanical resistance to deformation or tearing (primarily in the X axis, but also in the Y axis) that may be caused by torque applied to blanket 44 (e.g., by BCD 77, BTD 99, and dancer assembly 74).

[0111] In some embodiments, support layer 107 of blanket 44 includes a mesh 109 made from woven fiberglass or other suitable material(s) and configured to be flexible in the XYZ axes, yet has a high mechanical resistance to deformation compared to the silicone-based layers (such as layers 102 and 104) of blanket 44. The resistance to deformation (also referred to herein as the stiffness or rigidity of each layer) is measured using the test procedures described above, and has a metric referred to herein as the modulus of elasticity, the measurement and calculation of which is described above.

[0112] In some embodiments, mesh 109 of support layer 107 is typically between about 90 μm and 120 μm thick (measured in the Z-axis) and has first and second sections that are infilled with layers 106 and 108, respectively, as described herein. Note that layers 106 and 108 are formed along with the woven glass fabric of mesh 109, the infilling and other processes of mesh 109 being described in more detail in FIG. 3 below.

[0113] In some embodiments, layer 106 (also referred to herein as an adhesion layer) is made from PDMS or other suitable material and has a typical thickness (measured in the Z-axis) of between about 20 μm and 50 μm, or other suitable thickness.

[0114] In some embodiments, the layer 108 is an epoxy (e.g., C 21 H 25 ClO5), also referred to herein as epoxy resins. In this example, the epoxy resin is based on the reaction product of bisphenol A and epichlorohydrin, although in other embodiments, the epoxy resin may be based on any other suitable molecule known in the art, produced using any suitable reaction.

[0115] For example, layer 108 is made from RESOLTECH HTGL 210 product supplied by Resoltech (ROUSSET 13790, France) and Hardener HTGL 216 product with some additives, but may also include other suitable products supplied by other suitable suppliers. It should be noted that layer 108 has a different, and usually larger, elastic modulus than layer 106 in the same axis and / or direction (e.g., in the 94 or X-axis direction). In other words, layer 108 is stiffer (i.e., stiffer) than layer 106.

[0116] In other embodiments, layer 108 is made from other suitable materials or compound of elements, such as, but not limited to, polyaryletherketones (PAEKs), starches, also referred to herein as polysaccharides, polyimides, polyethylene terephthalates, etc. In still other embodiments, layer 108 is made from any suitable combination of two or more of the materials listed above, which may also include the aforementioned epoxies.

[0117] In some embodiments, layer 108 is typically about 50 μm thick (measured in the Z-axis) or other suitable thickness such that the combined (i.e., sum) thickness of layers 106 and 108 is approximately equal to the thickness of mesh 109. It should be noted that layers 106 and 108 are typically placed in contact with one another. In some cases, the adhesion between the materials selected for layers 106 and 108 may not be high enough to bond between layers 106 and 108. In such embodiments, the reinforcement of mesh 109 keeps layers 106 and 108 in contact with one another. In alternative embodiments, the materials selected for layers 106 and 108 may have a sufficiently high mutual adhesion, or the third section of mesh 109 may be filled with an additional suitable intermediate layer that can be used to bond between layers 106 and 108.

[0118] In other embodiments, the sum of the thicknesses of layers 106 and 108 may differ from the thickness of mesh 109, for example, if additional sections of mesh 109 are infilled with one or more additional layers. In yet other embodiments, mesh 109 may be infilled with only a single layer, such as layer 108, which is stiffer than one or more silicone-based layers of blanket 44.

[0119] In another embodiment, layer 106, which is typically used to bond between layers 108 and 104, may be omitted from the construction of blanket 44. In such an embodiment, the section of mesh 109 that is infilled in layer 106 may infill at least a section of layer 104. In other words, the section of mesh 109 may infill a portion of layer 104.

[0120] In other embodiments, instead of stack 107, the blanket may include a mesh 109 completely filled with the PMDS (and / or other suitable materials and / or variations of the PMDS described above) of layer 106. In other words, in this support layer, the entire size (along the Z-axis) of the woven glass fabric of mesh 109 is filled with PMDS and not the epoxy or other materials of layer 108 described above. In such embodiments, a typical thickness (measured along the Z-axis) of mesh 109 and layer 106 is between about 50 μm and 200 μm.

[0121] In some embodiments, different configurations of the stack of flexible support layers 107 were tested using the above test procedures. In addition, various configurations were also characterized using additional types of tests. The various configurations are based on the materials selected and the thicknesses of the layers mentioned above, resulting in various sets of mechanical properties for the blanket 44. For example, the calculated spring constant in tests performed using the Lloyd system is between about 20 and 50 when only silicone-based (e.g., PMDS) layers are used for the blanket 44, but when the same test procedures are applied to a blanket 44 having layers 108 made of epoxy (as shown in FIG. 2) or starch, the calculated spring constant is between about 70 and 120. In other words, the use of epoxy or starch for layers 108 results in a blanket 44 with a spring constant of about three times higher.

[0122] In one embodiment, based on the characteristics and requirements of the printing application, a user of the system 10 can select an appropriate configuration of the blanket 44 from among the above exemplary configurations of the blanket 44. It is noted that the selection of the most appropriate configuration provides the user with improved quality printed images by improving the blanket dimensional stability. For example, an optimal stiffness of the blanket 44 reduces the level of C2C registration errors (e.g., when applying the droplets 11 to the surface 103) and also reduces the level of image-to-substrate error(s) (e.g., during the image transfer process). Furthermore, obtaining an optimal stiffness of the blanket 44 can also reduce the frequency of blanket replacement, thereby improving the availability, utilization, and output of images printed by the system 10 during a given time interval (e.g., 24 hours).

[0123] In some embodiments, blanket 44 includes a high friction layer (also referred to herein as grip layer 110), typically made from transparent PDMS, configured to provide physical contact between blanket 44 and components of system 10 configured to move blanket 44 in direction 94. In this example, the list of parts that contact blanket 44 includes at least rollers 76 and 78, BCD 77, BTD 99, and dancer assembly 74, as described above in FIG. 1. Note that blanket 44 may also contact portions of blanket processing station 52. For clarity of description, one or more of the above parts may also be referred to herein as a "component" or "transfer component" that is placed in contact with blanket 44.

[0124] In some embodiments, the grip layer 110 is made of a relatively soft material (e.g., PMDS), but the outer surface of the blanket 44 that faces the transfer component (also referred to herein as surface 113) has high friction such that the blanket 44 can withstand torque applied by the BCD 77, BTD 99, roller 78, etc., without slipping.

[0125] In some embodiments, the gripping layer 110 may have a thickness of between about 90 μm and 120 μm, but may alternatively be of other suitable thicknesses.

[0126] In some cases, friction between the blanket 44 and one or more transfer components can result in the generation of unwanted static electricity in the grip layer 110. Due to the electrical conductivity of PMDS and other variations in the silicone-based and epoxy-based layers of the blanket 44, the generated charge can become trapped within the blanket 44. The charge carriers of the trapped static charge typically migrate to the outer layers of the blanket 44, which in this example are the grip layer 110 and the release layer 102.

[0127] In some cases, the trapped static charge may be discharged through the droplets 11 to the print bar 62 and, in extreme cases, may damage the nozzles of the print bar. Additionally, the trapped static charge on the release layer 102 may cause one or more droplets 11 to deflect, resulting in each droplet 11 landing on the surface 103 at a location(s) different from the droplet's intended location(s) on the surface 103. More specifically, different types of printing fluids (e.g., different color inks) applied to the surface 103 by the imaging station 60 may have different susceptibility to trapped charges. In such cases, images printed by the system 11 may experience C2C registration errors.

[0128] In some embodiments, the gripping layer 110 includes one or more particles and / or nanotubes of an electrically conductive additive (ECA) 111. In some embodiments, the maximum size of the largest ECA 111 is less than about 10% of the thickness of the gripping layer 110. Furthermore, the ECAs 111 are typically uniformly spaced apart from one another along the gripping layer 110, with the distance being defined based on the type and concentration level of the ECA, as described below.

[0129] In this example, the at least one ECA 111 includes carbon nanotubes (CNTs), such as single-walled CNTs (SWCNTs) or multi-walled CNTs (MWCNTs). The volume concentration of CNTs in the gripping layer 110 is between about 0.1% and 20%.

[0130] In some embodiments, a majority (e.g., about 95% or more), typically all of the ECA 111 is disposed within the bulk of the grip layer 110 such that both the surface 113 and the interface between layers 108 and 110 remain uniform (i.e., free of ECA 111). In the context of this disclosure and claims, the term "bulk" refers to about 80% of the grip layer 110, disposed away from the surface 113 and the interface between layers 108 and 110 at a distance of about 10% of the thickness of the grip layer 110. For example, if the grip layer 110 has a thickness of about 100 μm, most or all of the ECA 111 will be confined within a section of the grip layer 110 disposed at a distance of more than about 10 μm from the surface 113 and the interface between layers 108 and 110.

[0131] In some embodiments, the SWCNTs comprise rolled layers of graphene having a typical diameter of about 1.3 nanometers, or other suitable diameter, and the length of the SWCNTs can be on the order of thousands of nanometers. The SWCNTs have a single cylindrical wall and are typically tubes with capped ends. In this example, the SWCNTs comprise a masterbatch of SWCNTs dispersed in vinyl-terminated polydimethylsiloxane (PDMS), such as the TUBAII MATRIX 602 product supplied by OCSIAL (Rudelange, Luxembourg), but may comprise other suitable products supplied by other suitable suppliers.

[0132] In some embodiments, the MWCNTs comprise multiple rolled graphene layers, typically arranged in concentric tubes. In this example, the outer diameter of the MWCNTs may have a typical diameter size between about 2 nm and 1000 nm, depending on the number of concentric tube walls trapped within the MWCNT. Typically, the distance between any adjacent tube pair of the MWCNTs is between about 0.32 nm and 0.36 nm, which is approximately the same as the distance between the graphene layers in graphite.

[0133] In this example, the MWCNTs comprise multi-walled carbon nanotubes (MWCNTs) in vinyl-terminated DMS such as the Silcosperse™ EC 106116 product supplied by Avient Corporation (Avon Lake, Ohio, USA), but may comprise other suitable products supplied by other suitable suppliers.

[0134] In some embodiments, ECA111 can include any suitable combination of SWCNTs and MWCNTs described above.

[0135] In other embodiments, the at least one ECA 111 may comprise particles made of carbon (e.g., nanoparticles (MPs) in the form of black carbon, C60), or metal-based NPs, such as silver NPs or glass particles coated with a metal (e.g., silver or other suitable metal). In yet other embodiments, the at least one ECA 111 may comprise graphene or graphite. It should be noted that the size of all the above-mentioned ECAs 111 is typically less than about 1000 nm, or less than about 10% of the thickness of the grip layer 110.

[0136] Additionally or alternatively, the ECA 111 may include any suitable combination of the nanotubes and / or particles and / or nanoparticles described above, and / or any other suitable type of ECA 111.

[0137] In some embodiments, the ECA 111 is configured to increase the electrical conductivity of the gripping layer 110 and discharge (i.e., by electrical conduction) generated static charge from the blanket 44. In some embodiments, the inventors have developed techniques for testing the electrical conductivity of the blanket 44. One example is to measure the electrical resistance on the surfaces 113 and / or 103 of the blanket 44. In this example, after moving the blanket 44 through the system 10 (to intentionally generate a static charge for testing and measurement), the measurement is performed at a temperature of about 25° C. to 100° C. using a Fluke 1507 Insulation Resistance Tester or Fluke 179 Insulation Resistance Tester product supplied by Fluke Corporation, Everett, Wash., a wholly owned subsidiary of Fortive Corporation.

[0138] In some embodiments, the concentration of ECA 111 is determined based on the specified electrical conductivity of the blanket 44. Thus, the ECA 111, which has a higher electrical conductivity compared to the other types of ECA 111 described above, is embedded in the gripping layer 110 at a lower volume concentration. For example, SWCNTs have a higher electrical conductivity compared to silver particles. Thus, the volume concentration of SWCNTs embedded in the gripping layer 110 can be less than the volume concentration of silver particles. It should be noted that the electrical conductivity of CNTs is approximately 1000 times higher than that of copper and silver particles.

[0139] In other cases, blanket 44 may become charged by charge carriers generated by other undesired or unintended mechanisms. In some embodiments, ECA 111 is configured to conduct any type of charge carriers trapped within blanket 44.

[0140] In some cases, the temperature of blanket 44 may increase beyond a specified tolerance level. This can occur due to friction as described above and / or due to overheating of blanket 44 by drying station 64, for example, during the drying process of ink droplets applied to surface 103.

[0141] In some embodiments, the ECA 111 is configured to conduct excess heat generated in the blanket 44 such that one or more transfer components (or other suitable devices of the system 10) can be used as a heat slug to dissipate the excess heat, thereby cooling the blanket 44. More specifically, the thermal conductivity of both types of CNTs (SWCNTs and MWCNTs) in the ECA 111 is approximately eight times that of copper (considered to be one of the most thermally conductive metallic elements). Thus, implementing CNTs may improve heat dissipation from the blanket 44.

[0142] In some embodiments, both types of CNTs (SWCNTs and MWCNTs) in the ECA 111 improve some properties of the layer 110 and therefore the blanket 44. For example, the weight of CNTs is about half that of metal particles of the same size. Thus, the overall weight of the blanket 44 is controllable and can be reduced.

[0143] In some embodiments, the tensile strength of CNTs is about 100 times that of stainless steel or other metal particles of the same size. Additionally, the elastic modulus of CNTs is about 7 times that of stainless steel particles. Thus, the tensile strength (and elastic modulus) of blanket 44 can be controlled (e.g., increased) by implementing CNTs in layer 110 and, if desired, in other suitable layers of blanket 44.

[0144] In some embodiments, implementing CNTs in layer 110 and / or one or more other suitable layers of blanket 44 may improve the chemical stability of blanket 44 and various components of system 10. For example, CNTs are more resistant to corrosion than the metal particles discussed above. Thus, implementing CNTs (rather than metal particles) in layer 110 may increase the lifespan of blanket 44 and therefore the productivity (uptime, output, etc.) of system 10. Additionally, an increased lifespan of blanket 44 reduces the amount of waste associated with the operation of system 11, thus making system 11 more environmentally friendly to use.

[0145] It should be noted that in this example, blanket 44 has both (i) improved stiffness (obtained by implementing a stack of flexible support layers 107, more specifically layer 108 impregnated with mesh 109) and (ii) improved electrical conductivity (obtained by implementing ECA 111 in at least layer 110). However, system 10 can also operate with other blankets having only one of the above features, e.g., improved stiffness only or improved electrical conductivity only, as described in the embodiments described in the next two paragraphs.

[0146] In other embodiments, instead of blanket 44, system 10 may include a predetermined blanket. The predetermined blanket may include a suitable ECA 111 in one or more layers to improve the electrical conductivity of the blanket. Additionally, the predetermined blanket may not include any stiffening layers, such as layer 108, or other stiffening layers at all. Instead, the predetermined blanket may only have a layer with high flexibility and low modulus of elasticity, such as silicone or PMDS. In such embodiments, the predetermined blanket may have a higher electrical conductivity but a lower stiffness compared to blanket 44.

[0147] In yet other embodiments, instead of blanket 44, system 10 may include a different blanket. The alternative blanket may not include ECA 111 or other suitable mechanisms for improving electrical conductivity, but may have the improved rigidity provided by the stack of flexible support layers 107, and more particularly layer 108 impregnated with mesh 109 as described above.

[0148] In an alternative embodiment, the IR layer 101 confined between layers 102 and 104 may be omitted from the blanket 44, for example in printing applications that do not require the blanket 44 to be exposed to infrared radiation by the drying station 64.

[0149] The particular configuration of blanket 44 is shown as an example to illustrate the particular problems (e.g., stretching and static charging) addressed by embodiments of the present invention and to show the application of these embodiments in improving the performance of such flexible intermediate transfer members, however, embodiments of the present invention are in no way limited to this particular type of exemplary blanket and the principles described herein may be similarly applied to other types of flexible intermediate transfer members used in any type of printing system.

[0150] FIG. 3 is a schematic cross-sectional view of a process sequence for manufacturing blanket 44 as described in FIG. 2 above, according to one embodiment of the present invention.

[0151] The process sequence begins at step 1, which provides a carrier 116 that is used only for the manufacturing process of blanket 44 and is removed after the manufacturing process is completed. In this example, the manufacturing method for blanket 44 is performed when the layers of blanket 44 are inverted (e.g., upside down) compared to the configuration shown in FIG. 2 above.

[0152] In some embodiments, the carrier 116 may be formed of a flexible foil, such as a flexible foil comprising aluminum, nickel, and / or chromium. In one embodiment, the foil comprises a sheet of aluminized polyethylene terephthalate (PET) (also referred to herein as polyester), such as PET coated with fumed aluminum metal.

[0153] In some embodiments, the carrier 116 may be formed of an antistatic polymer film, such as a polyester film. Antistatic film properties can be achieved using a variety of techniques, such as adding various additives, such as ammonium salts, to the polymer composition.

[0154] In some embodiments, the carrier 116 has a polished flat surface (not shown) having a roughness (Ra) of about 50 nm or less, also referred to herein as the carrier contact surface.

[0155] In some embodiments, in step 1, a fluid first curable composition (not shown) is provided from which a release layer 102 is formed on the carrier contact surface. In this example, the thickness of the release layer 102 ranges from about 20 μm to 70 μm, as shown in FIG. 2 above.

[0156] In some embodiments, the release layer 102 includes an ink-receptive surface 103 configured to receive an ink image and transfer the ink image to the sheet 50, as described above in Figure 1. It is noted that the release layer 102, and in particular the surface 103, is configured to provide a low release force to the ink image, as measured by the wetting angle between the surface 103 and the ink image, also referred to herein as the receding contact angle (RCA), as described above in Figure 2.

[0157] In some embodiments, the release layer 102 can be uniformly applied to a PET-based carrier 116, planarized to a thickness of about 5 μm to 200 μm, and cured at 120-130° C. for about 2-10 minutes to obtain the aforementioned release layer 102 thickness (e.g., about 20 μm to 70 μm). Note that the hydrophobicity of the ink transfer surface 103 can have an RCA of about 60° for a 0.5-5 microliter (μl) drop of distilled water. In some embodiments, the RCA of the surface 105 of the release layer 102 can be much higher, typically about 90°.

[0158] In some embodiments, the PET carrier used to manufacture the ink transfer surface 103 may have a typical RCA of about 40° or less. All contact angle measurements were performed using a contact angle analyzer "Easy Drop" FM40Mk2 from Kruss™ GmbH, (Borsteler Chaussee 85, 22453 Hamburg, Germany) and / or a Dataphysics OCA15 Pro from Particle and Surface Sciences Pty. Ltd. (Gosford, NSW, Australia).

[0159] In some embodiments, during step 1, an IR layer 101 is formed on a surface 105 of the release layer 102. As described above in FIG. 2 , the IR layer 101 includes a matrix made from silicone (such as PDMS) and a number of particles (not shown) disposed at specific locations within the bulk of the PDMS matrix of the IR layer 101.

[0160] In alternative embodiments, for example in printing applications that do not require the blanket 44 to be exposed to infrared radiation by drying station 64, the blanket 44 may exclude the IR layer 101. In such embodiments, step 1 may exclude the formation of the IR layer 101, and the method may proceed by forming the next layer (described in step 2 below) directly on the surface 105 of the release layer 102.

[0161] In step 2, a conformal layer 104 is applied to the outer surface of the IR layer 101. In this example, the conformal layer 104 has a thickness between about 50 μm and 400 μm, as shown above in FIG. 2. In some embodiments, attaching the conformal layer 104 to the outer surface of the IR layer 101 may require the application of a suitable adhesive or bonding composition in addition to the conformal layer 104 material.

[0162] In an alternative embodiment, the IR layer 101 is omitted from the construction of the blanket 44, and thus the conformal layer 104 is applied directly to the surface 105 of the release layer 102. In such an embodiment, attachment of the conformal layer 104 to the surface 105 may require the application of a suitable adhesive or bonding composition in addition to the material of the conformal layer 104.

[0163] In step 3, a first section of mesh 109 is impregnated into adhesive layer 106 and the impregnated glass fiber fabric of mesh 109 is added to conformal layer 104. In some embodiments, the thickness of the adhesive layer is between about 20 μm and 50 μm and the thickness of mesh 109 is between about 90 μm and 120 μm, as shown in FIG.

[0164] In step 4, a second section of mesh 109 is filled with layer 108 made from epoxy, starch, or other suitable material or combination of materials as detailed above in Figure 2. Note that layer 108 has a greater (or different) elastic modulus than that of layer 106 (e.g., in direction 94 or X-axis) as shown in Figure 2 above, and is approximately 50 μm thick.

[0165] In some embodiments, steps 3 and 4 complete the production of the stack of flexible support layers 107.

[0166] In other embodiments, the fabrication of flexible support layer 107 may be performed using any other suitable sequence. For example, the filling of mesh 109 with woven glass fabric may be performed in a separate process, after which the entire stack of flexible support layer 107 (i.e., mesh 109 filled into layers 106 and 108) may be bonded to conformal layer 104.

[0167] In yet other embodiments, the fiberglass filling of mesh 109 may be performed in a separate process, after which conformal layer 104 may be bonded to the completed stack of flexible support layers 107. In such embodiments, release layer 102 and carrier 116 may be bonded to conformal layer 104.

[0168] In alternative embodiments, instead of the support layer 107, the blanket 44 may have any suitable type of different structure, such as having a mesh 109 that is (i) completely filled only with the epoxy layer 108, or (ii) completely filled only with the PMDS of the adhesive layer 106 (as described in more detail in Figures 5 and 6 below). It should be noted that if the mesh 109 is completely filled only with the PMDS of the adhesive layer 106, the process of step 3 above includes completely filling the mesh 109 with the PMDS of the adhesive layer 106, and step 4 may be omitted from the process sequence of Figure 3. That is, step 4 may be optional.

[0169] Additionally or alternatively, instead of support layer 107, blanket 44 may have any other suitable construction including any suitable combination of selected layers.

[0170] In step 5, completing the method of making the blanket 44 laminate, a gripping layer 110 including one or more particles and / or nanotubes of an electrically conductive additive (ECA) 111 is applied to layer 108 of support layer 107. In this example, the thickness of gripping layer 110 is between about 90 μm and 120 μm, as shown in FIG. 2 above.

[0171] In some embodiments, step 5 includes mounting or placing the ECA 111 in the bulk of the grip layer 110, which is then added to the layer 108.

[0172] In other embodiments, the PMDS matrix of the grip layer 110 is applied to layer 108 and then the ECA 111 is disposed within the bulk of the grip layer 110 .

[0173] In either embodiment, the ECA 111 must be uniformly located within the bulk of the grip layer 110 in order to obtain uniform electrical (and thermal) conductivity along the grip layer 110. It should be noted that as long as the dispersion of the MWCNTs in the uncured silicone is uniform and stable, the coated layer will be sufficiently uniform.

[0174] In some embodiments, layer 108 is made from epoxy and layer 110 is made from PMDS or another form of silicone. Because adhesion between epoxy and PMDS may be low, layers 108 and 110 may be bonded using a coupling agent. In some embodiments, the coupling agent comprises a bonding layer (not shown) that may be applied between layers 108 and 110. In other embodiments, the coupling agent may be added to layer 110, but the coupling agent may also be applied as an adhesion promoter on the epoxy layer. In an alternative embodiment, a third section (not shown) of mesh 109 (not filled with layers 106 or 108 and disposed between layers 108 and 110) may be filled with at least a portion of grip layer 110 to ensure a sufficiently strong bond between layers 108 and 110 is obtained.

[0175] In some embodiments, after step 5 is completed, the carrier 116 is removed from the stack shown in step 5, completing the production of the blanket 44.

[0176] Additional embodiments relating to one or more layers of blanket 44, and manufacturing techniques for at least a portion of the blanket 44 laminate, are described in detail in PCT Application PCT / IB2019 / 055288 and PCT International Publication WO2017 / 208144, the disclosures of which are incorporated herein by reference.

[0177] The particular sequence of steps 1-5 in FIG. 3 is shown as an example. However, embodiments of the present invention are in no way limited to this particular sequence of steps, which is simplified for conceptual clarity. Moreover, the principles described herein are equally applicable to other types of process flows used to manufacture blanket 44 or other suitable types of ITMs having any suitable layer configuration. These layers may have any suitable thickness and be made of any suitable materials that differ from the exemplary configuration of blanket 44 described in FIG. 2 and the process flow for manufacturing blanket 44 described in FIG. 3 above.

[0178] FIG. 4 is a flow chart that generally illustrates a method for improving the stiffness and electrical conductivity of blanket 44, in accordance with one embodiment of the present invention.

[0179] The method begins with a release layer and conformal layer manufacturing step 200 in which a release layer 102 is added to a carrier 116, as described in detail in step 1 of FIG. 3 above, followed by adding a conformal layer 104 to the release layer 102, as described in detail in step 2 of FIG. 3 above.

[0180] In a support layer fabrication step 202, a first section and a second section of the mesh 109 are inundated with a silicone-based layer 106 and an epoxy-based layer 108, respectively, to fabricate a stack of support layers 107. In a support layer integration step 204, the stack of support layers 107 is added to the conformal layer 104. It should be noted that in steps 202 and 204, the entire stack of support layers 107 is fabricated and then added to the conformal layer 104.

[0181] In other embodiments, steps 202 and 204 may be replaced by another two-step process, for example (i) mesh 109 (a first section of which is already saturated with adhesion layer 106) is added to conformal layer 104, and then (ii) a second section of mesh 109 is saturated with layer 108, as described in some embodiments of steps 3 and 4 of FIG.

[0182] In an alternative embodiment, steps 202 and 204 may be replaced with a three-step process, for example (i) adding mesh 109 to conformal layer 104, followed by (ii) infiltrating layer 106 with a first section of mesh 109, followed by (iii) infiltrating layer 108 with a second section of mesh 109.

[0183] In a grip layer fabrication step 206, a grip layer 110 made from silicone (e.g., PMDS) and an ECA 111, such as the CNT additive described in detail in FIG. 2 above, is fabricated and added to the stack of support layers 107 as described in step 5 of FIG. 3 above.

[0184] In other embodiments, the grip layer 110 of the blanket 44 is manufactured without the ECA 111, such that the grip layer 110 includes a PMDS that may not include additives or may include additives that are not related to altering (e.g., improving) the electrical conductivity of the blanket 44.

[0185] In alternative embodiments, instead of the additives mentioned above, layer 110 can include other types of composites having a combination of two materials with different physical and / or chemical properties. For example, a matrix made of any suitable type of silicone (e.g., PMDS) and one or more fibers disposed within the bulk of the PMDS. The fibers can be arranged in a one-dimensional (1D) array (e.g., the longitudinal axis of the fibers is parallel to the X-axis, in other suitable directions relative to the X-axis, or parallel to the Y-axis) or in a two-dimensional (2D) array of fibers (which may or may not be interwoven). The array of fibers can be arranged in any suitable direction relative to the X-, Y-, and Z-axes shown in FIG. 1 above. Additionally or alternatively, blanket 44 can include a conductive layer disposed within the bulk of grip layer 110 and / or between any two layers of blanket 44, e.g., between grip layer 110 and layer 108, or any other location within blanket 44.

[0186] In a carrier removal step 208 that concludes the method, the carrier 116 is removed from the release layer 102 and the fabrication of the blanket 44 is completed.

[0187] In other embodiments, blanket 44 may include, instead of the stack of support layers 107, a stack of different support layers, such as mesh 109 impregnated into one or more of layers 104, 106, 108, and 110. In such embodiments, one or more of layers 104, 106, and 108 may be omitted from the construction of blanket 44.

[0188] 5 is a schematic cross-sectional view of a blanket 47 according to another embodiment of the present invention, which can be used in place of blanket 44 of FIG.

[0189] 2 above, in some embodiments, instead of stack 107, blanket 47 includes mesh 109 (shown in FIG. 2 above) completely filled with PMDS (and / or other suitable materials and / or variations of PMDS as described above) of layer 106. In other words, in this support layer, the entire size (along the Z-axis) of the woven glass fabric of mesh 109 is filled with PMDS of layer 106, and not the epoxy or other material of layer 108 shown in FIGS. 2 and 3 above. In such embodiments, a typical thickness (measured along the Z-axis) of mesh 109 and layer 106 is between about 50 μm and 200 μm.

[0190] In some embodiments, layers 101, 102, 104, and 110 of blankets 44 and 47 are substantially similar, i.e., have substantially the same thickness and materials, as the corresponding layers 101, 102, 104, and 110 described in detail above in Figures 2 and 3.

[0191] In other embodiments, blanket 47 may exclude at least one of layers 101, 102, 104, and 110, or may have any suitable variation in one or more of these layers.

[0192] FIG. 6 is a schematic cross-sectional view of a processing sequence for producing a blanket 47 according to an embodiment of the invention.

[0193] The process sequence begins in step 1 with providing a carrier 116, followed by forming a release layer 102 on surface 103 of the release layer 102, as described in detail above in Figure 3. In step 2, an IR layer 101 is formed on surface 105 of the release layer 102, also as described in step 1 of Figure 3 above.

[0194] In step 3, a conformal layer 104 is applied to the outer surface of the IR layer 101 using, for example, the process detailed in step 2 of FIG. 3 above.

[0195] In step 4, mesh 109 is completely filled with the PMDS of layer 106 and the combination of mesh 109 and layer 106 is placed on the outer surface of conformal layer 104.

[0196] In step 5, which completes the method of making the blanket 47 laminate, a gripping layer 110 comprising one or more particles and / or nanotubes of an electrically conductive additive (ECA) 111 is applied to layer 106 (permeating mesh 109). In this example, the thickness of gripping layer 110 is between about 90 μm and 120 μm, as shown in detail in Figures 2 and 3 above.

[0197] In some embodiments, after step 5 is completed, carrier 116 is severed from layer 102, thereby removing it from the stack shown in step 5, completing the manufacture of blanket 47.

[0198] FIG. 7 is a flow chart that generally illustrates a method of manufacturing the blanket 47 with improved stiffness and electrical conductivity described in FIGS. 5 and 6, in accordance with one embodiment of the present invention.

[0199] The method begins with a release layer and IR layer manufacturing step 300 in which the release layer 102 is added to the carrier 116, as described in detail in step 1 of FIG. 6 above, followed by the addition of an IR layer 101 to the outer surface of the release layer 102, as described in detail in step 2 of FIG. 6 above.

[0200] In conformal layer fabrication step 302, conformal layer 104 is applied to the outer surface of IR layer 101 as detailed in step 3 of FIG. 6 above.

[0201] In the support layer fabrication step 304, mesh 109 is infused into silicone-based layer 106 to fabricate a support layer that is a combination of mesh 109 and layer 106. The support layer is then applied to the outer surface of conformal layer 104, as shown in Figure 6 above.

[0202] In a grip layer fabrication step 306, a grip layer 110 made from ECA 111 and silicone (e.g., PMDS), such as the CNT additive described in more detail in FIG. 2 above, is fabricated and added to the support layer (made from the PMDS-filled mesh 109 of layer 106) as described in more detail in step 5 of both FIG. 3 and FIG. 6 above.

[0203] In other embodiments, the grip layer 110 of the blanket 47 is manufactured without the ECA 111, such that the grip layer 110 can include a PMDS that may not include additives or can include additives that are not related to altering (e.g., improving) the electrical conductivity of the blanket 47.

[0204] In alternative embodiments, instead of the additives mentioned above, layer 110 can include other types of composite materials having a combination of two materials with different physical and / or chemical properties. For example, a matrix made of any suitable type of silicone (e.g., PMDS) and one or more fibers disposed within the bulk of the PMDS. The fibers can be arranged in a one-dimensional (1D) array (e.g., the longitudinal axis of the fibers is parallel to the X-axis, in other suitable directions relative to the X-axis, or parallel to the Y-axis) or in a two-dimensional (2D) array of fibers (which may or may not be interwoven). The array of fibers can be arranged in any suitable direction relative to the X-, Y-, and Z-axes shown in FIG. 1 above. Additionally or alternatively, blanket 47 can include a conductive layer disposed within the bulk of grip layer 110 and / or between any two layers of blanket 47, e.g., between grip layer 110 and layer 106, or any other location within blanket 47.

[0205] In a carrier removal step 308 that concludes the method, carrier 116 is removed from release layer 102 and fabrication of blanket 47 is complete.

[0206] Although the embodiments described herein primarily address digital printing using flexible intermediate transfer members, the methods and systems described herein may be used in other applications, such as any type of printing system and process having any suitable type of intermediate device (e.g., member) for receiving an image and transferring the image to a target substrate.

[0207] Thus, the above-described embodiments are cited by way of example, and it will be understood that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof that would occur to one skilled in the art upon reading the above description and that are not disclosed in the prior art. Documents incorporated by reference into this patent application are to be considered as part of this application. Except where any term is defined in such incorporated documents in a manner that contradicts the definition expressly or impliedly formed herein, only the definition in this specification shall be considered.

Claims

1. 1. An intermediate transfer member (ITM) of a printing system, comprising: an outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; a stack of flexible support layers, the stack including: a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity in an axis along which the ITM is tensioned; and (ii) a second section disposed in contact with the first layer, the second section impregnated with a second layer having a second modulus of elasticity different from the first modulus of elasticity in the axis; Including, and wherein the stack of flexible support layers is configured to maintain a predetermined elongation of the ITM along the axis upon application of a specified level of tension to the ITM. Said ITM.

2. The ITM of claim 1 , wherein the mesh comprises woven fiberglass.

3. 10. The ITM of claim 1, wherein the second layer comprises a material selected from the list of materials consisting of: (i) epoxy, (ii) polyaryletherketone (PAEK), (iii) polysaccharides, (iv) polyimide, polyethylene terephthalate, and (v) a combination of two or more of the materials in the list.

4. The ITM of any one of claims 1 to 3, comprising an additional outer layer configured to contact an ITM module, the ITM module configured to move the ITM along the axis, the additional outer layer comprising (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives.

5. The ITM of claim 4 , wherein the one or more conductive additives are configured to discharge static charge from the flexible substrate.

6. 5. The ITM of claim 4, wherein the conductive additive comprises one or more additives selected from the list of additives consisting of: (i) one or more nanotubes (NTs); (ii) one or more particles; and (iii) a combination of the one or more NTs and particles.

7. 7. The ITM of claim 6, wherein the NT comprises a carbon nanotube (CNT) selected from the list of CNTs consisting of: (i) a multi-walled CNT (MWCNT), (II) a single-walled CNT (SWCNT), and (iii) a combination of one or more MWCNTs and SWCNTs.

8. 8. The ITM of claim 7, wherein the additional outer layer comprises one of: (i) a first volume concentration of MWCNTs; (ii) a second volume concentration of SWCNTs less than the first volume concentration; and (iii) a combination of the MWCNTs and SWCNTs having a third volume concentration less than the first volume concentration and greater than the second volume concentration to obtain a predetermined electrical conductivity of the additional outer layer.

9. 8. The ITM of claim 7, wherein the CNTs are configured to modify one or both of: (i) a third elastic modulus of the additional outer layer; and (ii) a thermal conductivity of the additional outer layer.

10. 8. The ITM of claim 7, wherein the one or more particles are selected from the list of particles consisting of: (i) metal nanoparticles (NPs), (ii) carbon-based NPs, (iii) metal-coated glass particles, (iv) graphene particles, (v) graphite particles, and (vi) a combination of two or more of the particles selected from the list of particles.

11. 1. A method of manufacturing an intermediate transfer member (ITM) for a printing system, comprising: (i) producing an outer layer for receiving droplets of printing fluid to form an image thereon, and (ii) transferring said image to a target substrate; producing a stack of flexible support layers by filling (i) a first section of a mesh of a first layer having a first modulus of elasticity in an axis along which the ITM is tensioned, and (ii) a second section of the mesh of a second layer disposed in contact with the first layer, the second section having a second modulus of elasticity in the axis, the second modulus of elasticity being different from the first modulus of elasticity; producing the ITM by consolidating a stack of at least the outer layer and the flexible support layer; The method comprising:

12. The method of claim 11 , wherein manufacturing the stack includes using the mesh comprising woven fiberglass fabric.

13. 12. The method of claim 11, wherein manufacturing the stack includes using the second layer comprising a material selected from the list of materials consisting of: (i) epoxy, (ii) polyaryletherketone (PAEK), (iii) polysaccharide, (iv) polyimide, polyethylene terephthalate, and (v) a combination of two or more materials from the list.

14. The method of any one of claims 11 to 13, further comprising: producing an additional outer layer for placement in contact with an ITM module to move the ITM along the axis, wherein creating the additional outer layer comprises: (i) receiving a flexible substrate that conforms to one or more components of the ITM module and has friction with at least one of the one or more components to move the ITM along the axis; and (ii) disposing one or more conductive additives on the flexible substrate.

15. The method of claim 14 , wherein the one or more conductive additives are for discharging static charge from the flexible substrate.

16. 15. The method of claim 14, wherein disposing the conductive additive comprises disposing one or more additives selected from the list of additives consisting of: (i) one or more nanotubes (NTs); (ii) one or more particles; and (iii) a combination of the one or more NTs and particles.

17. 17. The method of claim 16, wherein the NTs comprise carbon nanotubes (CNTs) selected from the list of CNTs consisting of: (i) multi-walled CNTs (MWCNTs), (ii) single-walled CNTs (SWCNTs), and (iii) a combination of one or more MWCNTs and SWCNTs.

18. 20. The method of claim 17, comprising adding to the additional outer layer one of: (i) a first volume concentration of the MWCNTs; (ii) a second volume concentration of the SWCNTs less than the first volume concentration; and (iii) a combination of the MWCNTs and the SWCNTs having a third volume concentration to obtain a predetermined electrical conductivity of the additional outer layer.

19. 17. The method of claim 16, wherein adding the CNTs comprises modifying one or both of: (i) a third elastic modulus of the additional outer layer; and (ii) a thermal conductivity of the additional outer layer.

20. 17. The method of claim 16, wherein disposing the one or more particles comprises selecting the one or more particles from a list of particles consisting of: (i) metal nanoparticles (NPs), (ii) carbon-based NPs, (iii) metal-coated glass particles, (iv) graphene particles, (v) graphite particles, and (vi) combinations of two or more of the particles selected from the list of particles.

21. 1. An intermediate transfer member (ITM) of a printing system, comprising: a first outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; a second outer layer configured to contact an ITM module configured to move the ITM along an axis, the second outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; The ITM comprising:

22. 22. The ITM of claim 21, wherein the one or more conductive additives are configured to discharge static charge from the flexible substrate.

23. 23. The ITM of any one of claims 21-22, wherein the conductive additive comprises one or more additives selected from the list of additives consisting of: (i) one or more nanotubes (NTs); (ii) one or more particles; and (iii) a combination of the one or more NTs and particles.

24. 24. The ITM of claim 23, wherein the NT comprises a carbon nanotube (CNT) selected from the list of CNTs consisting of: (i) a multi-walled CNT (MWCNT), (ii) a single-walled CNT (SWCNT), and (iii) a combination of one or more MWCNTs and MWCNTs.

25. 25. The ITM of claim 24, wherein the additional outer layer comprises one of: (i) a first volume concentration of the MWCNTs; (ii) a second volume concentration of the SWCNTs less than the first volume concentration; and (iii) a combination of the MWCNTs and the SWCNTs having a third volume concentration less than the first volume concentration and greater than the second volume concentration to obtain a predetermined electrical conductivity of the additional outer layer.

26. 23. The ITM of any one of claims 21 to 22, comprising a stack of flexible support layers, the stack comprising a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity in the axis along which tension is applied to the ITM, and (ii) a second section disposed in contact with the first layer and impregnated with a second layer having a second modulus of elasticity different from the first modulus of elasticity in the axis, the stack of flexible support layers being configured to maintain a predetermined elongation of the ITM along the axis upon application of a particular level of tension to the ITM.

27. 27. The ITM of claim 26, wherein the mesh comprises woven fiberglass.

28. 27. The ITM of claim 26, wherein the second layer comprises a material selected from the list of materials consisting of: (i) epoxy, (ii) polyaryletherketone (PAEK), (iii) polysaccharides, (iv) polyimide, polyethylene terephthalate, and (v) a combination of two or more of the materials in the list.

29. 1. A system comprising: An intermediate transfer member (ITM), comprising: an outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; a stack of flexible support layers, the stack including a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity in an axis along which the ITM is tensioned, and (ii) a second section disposed in contact with the first layer, the second section impregnated with a second layer having a second modulus of elasticity different from the first modulus of elasticity in the axis; Including, and wherein the stack of flexible support layers is configured to maintain a predetermined elongation of the ITM along the axis upon application of a specified level of tension to the ITM. The ITM; an imaging station configured to apply the droplets of the printing fluid to the ITM; The system comprising:

30. 30. The system of claim 29, comprising an impression station configured to engage between the ITM and the target substrate at an engagement point to transfer the image from the ITM to the target substrate.

31. 1. A system comprising: An intermediate transfer member (ITM), comprising: a first outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; a second outer layer configured to contact an ITM module configured to move the ITM along an axis, the second outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; The ITM comprising: an imaging station configured to apply the droplets of the printing fluid to the ITM; The system comprising:

32. 32. The system of claim 31, comprising an impression station configured to engage between the ITM and the target substrate at an engagement point to transfer the image from the ITM to the target substrate.

33. 1. An intermediate transfer member (ITM) of a printing system, comprising: an outer layer configured to contact an ITM module configured to move the ITM along an axis, the outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; a stack of flexible support layers, the stack including a mesh having (i) a first section impregnated with a first layer having a first modulus of elasticity in an axis along which the ITM is tensioned, and (ii) a second section disposed in contact with the first layer, the second section impregnated with a second layer having a second modulus of elasticity different from the first modulus of elasticity in the axis; Including, and wherein the stack of flexible support layers is configured to maintain a predetermined elongation of the ITM along the axis upon application of a specified level of tension to the ITM. Said ITM.

34. 1. An intermediate transfer member (ITM) of a printing system, comprising: a first layer, the first layer being an outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; a second layer coupled to the first layer, the second layer including a matrix configured to hold particles in respective predetermined positions, the second layer configured to receive optical radiation passing through the first layer, the particles configured to heat the ITM by absorbing at least a portion of the optical radiation; The ITM comprising:

35. 35. The ITM of claim 34, comprising a third layer, an additional outer layer configured to contact an ITM module configured to move the ITM along an axis, the outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives.

36. The ITM of any of claims 34-35, comprising a fourth layer comprising a mesh impregnated with an elastic material.

37. 37. The ITM of claim 36, wherein the elastic material comprises silicone and has a predetermined elastic modulus in an axis along which tension is applied to the ITM, and wherein the fourth layer is configured to maintain a predetermined elongation of the ITM along the axis when a particular level of tension is applied to the ITM.

38. 1. A method of manufacturing an intermediate transfer member (ITM) for a printing system, comprising: producing a first layer, the first layer being an outer layer of the ITM for (i) receiving droplets of printing fluid to form an image thereon and (ii) transferring the image to a target substrate; bonding a second layer to the first layer, the second layer including a matrix that holds particles in their respective predetermined positions, the particles heating the ITM upon receiving optical radiation passing through the first layer by absorbing at least a portion of the optical radiation; The method comprising:

39. 40. The method of claim 38, comprising fabricating the second layer by integrating the particles into the matrix, the particles being positioned within the bulk of the matrix at a predetermined distance from each other and from an interface between the first layer and the second layer.

40. 1. An intermediate transfer member (ITM) of a printing system, comprising: a first outer layer configured to receive droplets of printing fluid to form an image thereon and to transfer the image to a target substrate; an inner layer coupled to the first outer layer, the second layer including a matrix configured to hold particles in respective predetermined positions, the second layer configured to receive optical radiation passing through the first outer layer, the particles configured to heat the ITM by absorbing at least a portion of the optical radiation; a second outer layer configured to contact an ITM module configured to move the ITM along the axis, the second outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have a predetermined friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; The ITM comprising:

41. 41. The ITM of claim 40, wherein the one or more conductive additives are configured to discharge static charge from the flexible substrate.

42. 42. The ITM of any one of claims 40-41, wherein the conductive additive comprises one or more additives selected from the list of additives consisting of: (i) one or more nanotubes (NTs); (ii) one or more particles; and (iii) a combination of the one or more NTs and particles.

43. 43. The ITM of claim 42, wherein the NT comprises a carbon nanotube (CNT) selected from the list of CNTs consisting of: (i) a multi-walled CNT (MWCNT), (II) a single-walled CNT (SWCNT), and (iii) a combination of one or more MWCNTs and SWCNTs.

44. 44. The ITM of claim 43, wherein the second outer layer comprises one of: (i) a first volume concentration of the MWCNTs; (ii) a second volume concentration of the SWCNTs less than the first volume concentration; and (iii) a combination of the MWCNTs and the SWCNTs having a third volume concentration less than the first volume concentration and greater than the second volume concentration to obtain a predetermined electrical conductivity of the second outer layer.

45. 43. The ITM of claim 42, wherein the CNTs are configured to modify one or both of: (i) a third elastic modulus of the second outer layer; and (ii) a thermal conductivity of the second outer layer.

46. 1. An intermediate transfer member (ITM) of a printing system, comprising: an inner layer coupled to a first outer layer for receiving droplets of printing fluid for generating an image thereon and for transferring the image to a target substrate, the second layer including a matrix configured to hold particles at respective given positions, the second layer configured to receive optical radiation passing through the first outer layer, the particles configured to heat the ITM by absorbing at least a portion of the optical radiation; a second outer layer configured to contact an ITM module configured to move the ITM along the axis, the second outer layer including (i) a flexible substrate configured to conform to one or more components of the ITM module and have a predetermined friction with at least one of the one or more components to move the ITM along the axis, and (ii) one or more conductive additives; The ITM comprising:

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