FIELD OF THE DISCLOSURE

[0001] The present disclosure generally relates to a reusable adhesion layer utilized to temporarily hold a flexographic printing plate during a flexographic printing process.

BACKGROUND

[0002] Flexographic printing is sometimes utilized to transfer designs to paper and other media. In flexographic printing, a flexible printing plate is sometimes coupled to a printing cylinder. The flexible printing plate includes a design as print relief that utilizes ink to transfer the design from the flexible printing plate to the paper or other media. The flexible printing plate is sometimes coupled to the printing cylinder via double-sided adhesive tape, double-sided adhesive tape covered by a photopolymerizable layer, or double-sided adhesive tape covered by an adhesion layer with adhesion elements in the form of fibrillar microstructures (adhesion elements). The photopolymerizable layer is sticky and has adherent characteristics allowing the flexible printing plate to be adhered thereto and subsequently removed therefrom, rendering the photopolymerizable layer reusable for a subsequent flexible printing plate. The fibrillar microstructures of the adhesion layer similarly allows the flexible printing plate to be adhered thereto and subsequently removed therefrom, but via van der Waals forces and electrostatic interaction rather than via an inherent tackiness.

[0003] However, use of each of the double-sided adhesive tape, the photopolymerizable layer, and the adhesion layer with the fibrillar microstructures presents problems. First, the doublesided adhesive tape is non-reusable and, thus, waste is generated after every use of the doublesided adhesive tape. Further, removal of the double-sided adhesive tape from the printing cylinder leaves residue on the printing cylinder, which deteriorates subsequent performance of the printing cylinder. Second, the photopolymerizable layer, although reusable, can result in the formation of air bubbles between the photopolymerizable layer and the flexible printing plate. The air bubbles can diminish printing quality. Further, the adhesion between the photopolymerizable layer and the flexible printing plate can be too strong, which causes difficulty in removing the flexible printing plate from the photopolymerizable layer. Third and finally, the adhesion layer with the fibrillar microstructures can sometimes have limited effectiveness in printing performance and adhering the flexible printing plate to the adhesion layer.

SUMMARY

[0004] The present disclosure addresses those problems in several ways. First, the disclosure presents an adhesion layer with adhesion elements that releasably attach to a flexible printing plate via electrostatic and van der Waals forces, and the adhesion layer forms a contiguous surface for the flexible printing plate with edges of the adhesion layer forming a seam. The contiguous surface allows an operator to place the flexible printing plate anywhere upon the adhesive layer, and the seal can be sealed below the adhesion elements, which improves printing performance.

[0005] Second, the disclosure presents an adhesion layer with first adhesion elements facing outward to allow for attachment to a flexible printing plate and second adhesion elements facing inward to allow for attachment to a printing cylinder or a cylindrical shell (sleeve). The utilization of the second adhesion elements allows the adhesion layer to be attached to the printing cylinder or the cylindrical shell without the aid of a double-sided adhesive tape, which reduces waste and avoids residue issues.

[0006] Third, the disclosure presents an adhesion layer with regions of differing densities of adhesion elements. The differing densities of the adhesion elements can be tailored to improve adherence of the flexible printing plate to the adhesion layer, and act as a visual cue to an operator as to where to optimally place the flexible printing plate on the adhesion layer, which can increase printing performance.

[0007] In all cases, the flexible printing plate can be applied to and removed from the adhesion layer repeatedly, without the need to replace a double-sided adhesive tape after every removal of the flexible printing plate, which reduces waste and residue. Further, because the adhesion elements are disparate raised features with air gaps therebetween, unacceptable air bubbles are unlikely to form between the adhesion layer and the flexible printing plate. Further benefits will become apparent upon reading the disclosure.

[0008] According to a first aspect of the present disclosure, a flexographic printing assembly comprises: (a) a printing cylinder, or a cylindrical shell configured to be coupled to a printing cylinder, whichever of the printing cylinder or the cylindrical shell comprising (i) an outer circumferential surface and (ii) a longitudinal axis; and (b) an adhesion layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, the adhesion layer comprising (i) a carrier sheet and (ii) first adhesion elements extending from the carrier sheet radially outward away from the longitudinal axis of the printing cylinder or the cylindrical shell, each of the first adhesion elements comprising an elongated body extending from the carrier sheet and an end face configured to releasably couple to a flexible printing plate; wherein, edges of the adhesion layer oppose each other and form a seam.

[0009] According to a second aspect of the present disclosure, the first aspect is presented, wherein (a) the outer circumferential surface of the printing cylinder or cylindrical shell further comprises a length that is parallel to the longitudinal axis; and (b) the adhesion layer is spirally disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, and the seam that the edges of the adhesion layer form is spirally disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell along at least a portion of the length of whichever of the printing cylinder or the cylindrical shell.

[0010] According to a third aspect of the present disclosure, the first aspect is presented, wherein the seam that the edges of the adhesion layer form is disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell parallel to the longitudinal axis of the of the printing cylinder or the cylindrical shell.

[0011] According to a fourth aspect of the present disclosure, any one of the first through third aspects is presented, wherein the seam is sealed with a sealant.

[0012] According to a fifth aspect of the present disclosure, the flexographic printing assembly of any one of the first through fourth aspects further comprises a double-sided adhesive layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, wherein the adhesion layer is disposed over the double-sided adhesive layer.

[0013] According to a sixth aspect of the present disclosure, any one of the first through fifth aspects is presented, wherein the adhesion layer further comprises second adhesion elements extending from the carrier sheet radially inward toward the longitudinal axis of the printing cylinder or the cylindrical shell, each of the second adhesion elements comprising an elongated body extending from the carrier sheet and an end face operably coupled to the outer circumferential surface of the printing cylinder or the cylindrical shell.

[0014] According to a seventh aspect of the present disclosure, the flexographic printing assembly of any one of the first through sixth aspects further comprises a flexible printing plate releasably coupled to the first adhesion elements of the adhesion layer.

[0015] According to an eighth aspect of the present disclosure, the flexographic printing assembly of the seventh aspect further comprises a temporary sealant sealing edges of the flexible printing plate to the adhesion layer.

[0016] According to a ninth aspect of the present disclosure, the eighth aspect is presented, wherein the temporary sealant comprises a polymer that is water-soluble, a polymer that degrades in the presence of electromagnetic radiation having a wavelength within the range of 250 nm to 800 nm, or a polymer that degrades in the presence of nucleophiles.

[0017] According to a tenth aspect of the present disclosure, any one of the first through ninth aspects is presented, wherein (a) the adhesion layer further comprises (i) a first region of the first adhesion elements and (ii) a second region of the first adhesion elements; and (b) a density of the first adhesion elements at the first region is different than a density of the first adhesion elements at the second region.

[0018] According to an eleventh aspect of the present disclosure, any one of the first through tenth aspects is presented, wherein the adhesion layer further comprises a secondary polymer sheet coupled to the carrier sheet, with the carrier sheet disposed between the secondary polymer sheet and the first adhesion elements.

[0019] According to a twelfth aspect of the present disclosure, any one of the first through eleventh aspects is presented, wherein the first adhesion elements of the adhesion layer comprise a hardness, a density, or a height that is predetermined.

[0020] According to a thirteenth aspect of the present disclosure, any one of the first through twelfth aspects is presented, wherein the first adhesion elements comprise polyurethane.

[0021] According to a fourteenth aspect of the present disclosure, a flexographic printing assembly comprises (a) a printing cylinder, or a cylindrical shell configured to be coupled to a printing cylinder, whichever of the printing cylinder or the cylindrical shell comprising (i) an outer circumferential surface and (ii) a longitudinal axis; and (b) an adhesion layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, the adhesion layer comprising (i) a carrier sheet, (ii) first adhesion elements extending from the carrier sheet radially outward away from the longitudinal axis of the printing cylinder or the cylindrical shell, each of the first adhesion elements comprising an elongated body extending from the carrier sheet and an end face configured to releasably couple to a flexible printing plate, and (iii) second adhesion elements extending from the carrier sheet radially inward toward the longitudinal axis of the printing cylinder or the cylindrical shell, each of the second adhesion elements comprising an elongated body extending from the carrier sheet and an end face releasably coupled to the outer circumferential surface of the printing cylinder or the cylindrical shell.

[0022] According to a fifteenth aspect of the present disclosure, the fourteenth aspect is presented, wherein the first adhesion elements and the second adhesion elements comprise at least one of: different compositions, different heights, end faces of different shapes, and different densities.

[0023] According to a sixteenth aspect of the present disclosure, any one of the fourteenth through fifteenth aspects is presented, wherein edges of the adhesion layer oppose each other and form a seam.

[0024] According to a seventeenth aspect of the present disclosure, the sixteenth aspect is presented, wherein the seam is sealed with a sealant.

[0025] According to an eighteenth aspect of the present disclosure, the flexographic printing assembly of any one of the fourteenth through seventeenth aspects further comprises a doublesided adhesive layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, wherein the adhesion layer is disposed over the double-sided adhesive layer. [0026] According to a nineteenth aspect of the present disclosure, the flexographic printing assembly of any one of the fourteenth through eighteenth aspects further comprises a flexible printing plate releasably coupled to the first adhesion elements of the adhesion layer.

[0027] According to a twentieth aspect of the present disclosure, any one of the fourteenth through nineteenth aspects is presented, wherein (a) the adhesion layer further comprises (i) a first region of the first adhesion elements and (ii) a second region of the first adhesion elements; and (b) a density of the first adhesion elements at the first region is different than a density of the first adhesion elements at the second region.

[0028] According to a twenty-first aspect of the present disclosure, any one of the fourteenth through twentieth aspects is presented, wherein the first adhesion elements comprise polyurethane.

[0029] According to a twenty-second aspect of the present disclosure, a flexographic printing assembly comprises: (a) a printing cylinder, or a cylindrical shell configured to be coupled to a printing cylinder, whichever of the printing cylinder or the cylindrical shell comprising (i) an outer circumferential surface and (ii) a longitudinal axis; and (b) an adhesion layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, the adhesion layer comprising (i) a carrier sheet, (ii) a first region of adhesion elements, and (iii) a second region of adhesion elements, each of the adhesion elements of the first region and the second region extending from the carrier sheet radially outward away from the longitudinal axis of the printing cylinder or the cylindrical shell, and each of the adhesion elements comprising an elongated body extending from the carrier sheet and an end face configured to releasably couple to a flexible printing plate; wherein a density of the adhesion elements at the first region is different than a density of the adhesion elements at the second region.

[0030] According to a twenty-third aspect of the present disclosure, the twenty-second aspect is presented, wherein one of the first region or the second region of the adhesion elements is positioned to releasably couple with edges and corners of a flexible printing plate, while the other of the first region or the second region of the adhesion elements is positioned to releasably couple with a central portion of the flexible printing plate.

[0031] According to a twenty-fourth aspect of the present disclosure, any one of the twenty- second through twenty-third aspects is presented, wherein the end faces of the adhesion elements at the first region have a shape that is different than a shape of the end faces of the adhesion elements at the second region.

[0032] According to a twenty-fifth aspect of the present disclosure, any one of the twenty- second through twenty-fourth aspects is presented, wherein edges of the adhesion layer oppose each other and form a seam. [0033] According to a twenty-sixth aspect of the preset disclosure, the twenty-fifth aspect is presented, wherein the seam is sealed with a sealant.

[0034] According to a twenty-seventh aspect of the present disclosure, the flexographic printing assembly of any one of the twenty-second through twenty-sixth aspects further comprises a double-sided adhesive layer disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell, wherein the adhesion layer is disposed over the double-side adhesive layer.

[0035] According to a twenty-eighth aspect of the present disclosure, the flexographic printing assembly of any one of the twenty-second through twenty-seventh aspects further comprises a flexible printing plate releasably coupled to the first adhesion elements of the adhesion layer.

[0036] According to a twenty-ninth aspect of the present disclosure, any one of the twenty- second through twenty-eighth aspects is presented, wherein the first adhesion elements comprise polyurethane.

[0037] According to a thirtieth aspect of the present disclosure, a method comprises: (a) disposing an adhesion layer over an outer circumferential surface of (i) a printing cylinder or (ii) a cylindrical shell configured to be coupled to a printing cylinder; (b) aligning edges of the adhesion layer together to form a seam; and (c) sealing the seam with a sealant; wherein (a) whichever of the printing cylinder or cylindrical shell further comprises a longitudinal axis; and (b) the adhesion layer comprises (i) a carrier sheet and (ii) first adhesion elements extendingfrom the carrier sheet radially outward away from the longitudinal axis of the printing cylinder or the cylindrical shell, each of the first adhesion elements comprising an elongated body extending from the carrier sheet and an end face configured to releasably couple to a flexible printing plate. [0038] According to a thirty-first aspect of the present disclosure, the thirtieth aspect is presented, wherein the seam is aligned parallel to the longitudinal axis of the printing cylinder or the cylindrical shell.

[0039] According to a thirty-second aspect of the present disclosure, the thirtieth aspect is presented, wherein the seam is spirally disposed over the outer circumferential surface of the printing cylinder or the cylindrical shell along at least a portion of the length of whichever of the printing cylinder or the cylindrical shell. [0040] According to a thirty-third aspect of the present disclosure, the method of any one of the thirtieth through thirty-second aspects further comprises, before disposing the adhesion layer over the outer circumferential surface of the printing cylinder or the cylindrical shell, disposing a double-sided adhesive layer over the outer circumferential surface of the printing cylinder or the cylindrical shell so that the adhesion layer is disposed over the double-sided adhesive layer.

[0041] According to a thirty-fourth aspect of the present disclosure, the method of any one of the thirtieth through thirty-third aspects further comprises disposing a flexible printing plate onto the first adhesion elements of the adhesion layer.

[0042] According to a thirty-fifth aspect of the present disclosure, the method of any one of the thirtieth through thirty-fourth aspects further comprises (a) performing a printing operation with the flexible printing plate, while the flexible printing plate is disposed on the first adhesion elements of the adhesion layer; (b) removing the flexible printing plate from the adhesion layer; (c) cleaning the first adhesion elements of the adhesion layer; (d) disposing the flexible printing plate or another flexible printing plate on the first adhesion elements of the adhesion layer; and (e) repeating the steps (a)-(d) at least 200 times without removing the adhesion layer.

[0043] According to a thirty-sixth aspect of the present disclosure, any one of the thirtieth through thirty-fifth aspects is presented, wherein cleaning the first adhesion elements of the adhesion layer comprises contacting the first adhesion elements with a solvent.

[0044] According to a thirty-seventh aspect of the present disclosure, any one of the thirtieth through thirty-sixth aspects is presented, wherein (a) the adhesion layer further comprises (i) a first region of the first adhesion elements and (ii) a second region of the first adhesion elements; (b) a density of the first adhesion elements at the first region is different than a density of the first adhesion elements at the second region; and (c) edges and corners of the flexible printing plate are disposed on the first region of the adhesion elements, while a central region of the flexible printing plate is disposed on the second region of the adhesion elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the Drawings:

[0046] FIG. 1 is a perspective view of a flexographic printing assembly that includes a printing cylinder, a cylindrical shell on the printing cylinder, a double-sided adhesive layer on the cylindrical shell, an adhesion layer on the double-sided adhesive layer, and a flexible printing plate on the adhesion layer;

[0047] FIG. 2 is an elevation view of a cross-section of the flexographic printing assembly of FIG.

1 taken through line ll-ll of FIG. 1, illustrating the adhesion layer wrapped around the doublesided adhesive layer and forming a seam with edges of the adhesion layer facing each other;

[0048] FIG. 3 is a magnified view of area III of FIG. 2, illustrating the adhesion layer of FIG. 1 including first adhesion elements extending away from a carrier sheet;

[0049] FIG. 4A is an overhead view of the adhesion layer of FIG. 1 not yet forming a component of the flexographic printing assembly, illustrating the first adhesion elements extending from the carrier sheet;

[0050] FIG. 4B is a perspective view of area IVB of FIG. 4, illustrating the first adhesion elements extending from the carrier sheet;

[0051] FIG. 5 is an elevation view, similar to FIG. 1, but this time showing the flexographic printing assembly with the adhesion layer applied to the double-sided adhesive layer so that the seam of the adhesion layer forms a spiral along a length of the printing cylinder and the cylindrical shell;

[0052] FIG. 6 is an elevation view of a cross-section, similar to FIG. 1, of another version of the flexographic printing assembly that does not include the double-sided adhesive layer but includes another embodiment of the adhesion layer that is applied directly to the cylindrical shell;

[0053] FIG. 7 is a magnified view of area VII of FIG. 6, illustrating the adhesion layer of FIG. 5 including second adhesion elements in addition to the first adhesion elements, with the second adhesion elements facing the opposite direction as the first adhesion element, so as to extend toward the longitudinal axis when applied to the cylindrical shell;

[0054] FIG. 8 is an overhead view of another embodiment of the adhesion layer, illustrating the first adhesion elements of the adhesion layer including a first region and a second region having different densities of the first adhesion elements; and

[0055] FIG. 9 is a schematic flow chart of a method of the disclosure that utilizes the adhesion layer. DETAILED DESCRIPTION

[0056] Referring now to FIGS. 1 and 2, a flexographic printing assembly 10 includes a printing cylinder 12 and a cylindrical shell 14. The cylindrical shell 14 is coupled to the printing cylinder 12. For example, in embodiments, the printing cylinder 12 includes an outer diameter 16, and the cylindrical shell 14 includes an inner diameter 18 that is smaller than the outer diameter 16 of the printing cylinder 12. Thus, the cylindrical shell 14 can be formed as a sleeve that is subsequently forced over the outer diameter 16 of the printing cylinder 12 and maintained in position via interference fit.

[0057] The printing cylinder 12, and the cylindrical shell 14 when attached to the printing cylinder 12, share a longitudinal axis 20. The printing cylinder 12 and the cylindrical shell 14 each include an outer circumferential surface 22, 24, respectively. The outer circumferential surfaces 22, 24 face away from the longitudinal axis 20. The outer circumferential surface 22 of the printing cylinder 12 defines the outer diameter 16 of the printing cylinder 12. Both the outer circumferential surface 22 of the printing cylinder 12 and the outer circumferential surface 24 of the cylindrical shell 14 share a common length 26, respectively, when coupled, which is parallel to the longitudinal axis 20.

[0058] The flexographic printing assembly 10 further includes an adhesion layer 28. The adhesion layer 28 is disposed over the outer circumferential surface 22 of the printing cylinder 12 and, if utilized, the adhesion layer 28 is disposed over the outer circumferential surface 24 of the cylindrical shell 14. In embodiments, the adhesion layer 28 is disposed directly upon the outer circumferential surface 22 of the printing cylinder 12. In embodiments, the adhesion layer 28 is disposed directly upon the outer circumferential surface 24 of the cylindrical shell 14. In other embodiments, at least one intervening layer, as further discussed below, is disposed between the printing cylinder 12 and the adhesion layer 28, and, if included, between the cylindrical shell 14 and the adhesion layer 28. Disposing the adhesion layer 28 over the cylindrical shell 14 rather than the printing cylinder 12 allows a user to apply the cylindrical shell 14, with the adhesion layer 28 attached, to the printing cylinder 12 when needed. This disclosure hereinafter generally assumes that the adhesion layer 28 is attached to the cylindrical shell 14, but it should be understood that the adhesion layer 28 can be applied to the printing cylinder 12 without incorporation of the cylindrical shell 14.

[0059] Referring now additionally to FIGS. 3, 4A, and 4B, the adhesion layer 28 includes a carrier sheet 30 and first adhesion elements 32 extending from the carrier sheet 30. When the adhesion layer 28 is coupled to the printing cylinder 12, the first adhesion elements 32 extend outward away from the longitudinal axis 20. Each of the first adhesion elements 32 includes an elongated body 34 and terminates with an end face 36. The elongated body 34 extends from the carrier sheet 30. In embodiments, the carrier sheet 30 has a thickness 38 within a range of from 125 pm to 600 pm.

[0060] The end faces 36 of the first adhesion elements 32 are collectively configured to releasably couple to a flexible printing plate 40. The first adhesion elements 32, at the end faces 36, form a microstructure surface 42 that contacts the flexible printing plate 40. In embodiments, the elongated body 34 has a diameter 44 within a range of from 4 pm to 80 pm and a height 46 within a range of from 10 pm to 150 pm. In embodiments, the end face 36 is substantially flat or concave (as in the illustrated embodiments), and has a diameter 48 within a range of from 5 pm to 80 pm. In embodiments, the first adhesion elements 32 include a neck portion 50 between the elongated body 34 and the end face 36, and the neck portion 50 has a diameter 52 within a range of from 10 pm to 35 pm. In embodiments, the quantity of the first adhesion elements 32 of the adhesion layer 28 is within a range of from 3,000 to 600,000 first adhesion elements 32 per square centimeter area parallel to the carrier sheet 30. It is believed that the adhesion between the end faces 36 of the first adhesion elements 32 and a flexible printing plate 40 is established by van der Waals forces and electrostatic interaction.

[0061] In embodiments, the first adhesion elements 32 can have a polymer composition. In embodiments, the polymer is selected from the group consisting of polyurethane, polysiloxane, and an acrylate. The first adhesion elements 32 can be formed via a molding process. The polymer of the first adhesion elements 32 can be a thermoplastic or a thermoset. Suitable thermosets include formaldehyde resins, polyurethanes, unsaturated polyester resins, epoxy resins, diallyl phthalate resins, silicone resins, and rubbers. Suitable thermoplastics include polyolefins (including derivatives and copolymers), polypropylene (including derivatives and copolymers), polybutene, styrene polymers, vinyl polymers, fluoropolymers, polyacryl- and methacryl copolymers, polyacrylates, polymethacrylates, polyoxymethylene, polyamides, aromatic (saturated) polyesters, aromatic polysulfides and polysulfones, aliphatic polyesters, aromatic polyimide, liquid crystalline polymers, ladder polymers, biopolymers, conductive/luminescent polymers, aliphatic polyketones, polymer ceramics, and polymer ceramics, including derivatives and copolymers thereof. In embodiments, the carrier sheet 30 and the first adhesion elements 32 attached thereto are composed of the same material. However, the carrier sheet 30 and the first adhesion elements 32 can have different compositions.

[0062] In embodiments, one or more of the composition, a hardness, a density, the height 46, and the shape of the end face 36 is predetermined. Predetermining one or more of the composition, the hardness, the density, the height 46, and the shape of the end face 36 of the first adhesion elements 32 tailor the degree of adhesion to any particular flexible printing plate 40. "Density," for purposes of this disclosure, means the number of adhesion elements per unit of area parallel to the major surface of the carrier sheet 30 from which the adhesion elements extend.

[0063] In embodiments, the adhesion layer 28 further includes a secondary polymer sheet 54, which provides additional structural support to the adhesion layer 28. The secondary polymer sheet 54 is coupled to the carrier sheet 30. For example, the secondary polymer sheet 54 can be layered onto the carrier sheet 30. In such embodiments, the carrier sheet 30 is disposed between the secondary polymer sheet 54 and the first adhesion elements 32. The secondary polymer sheet 54 can be polyethylene terephthalate or polyethylene naphthalate, among other options. The secondary polymer sheet 54 can be electrostatically coupled to the carrier sheet 30, or the secondary polymer sheet 54 can be coupled to the carrier sheet 30 via an adhesive.

[0064] Referring now additionally to FIG. 5, in embodiments, the adhesion layer 28 includes edges 56a, 56b that oppose each other and form a seam 58, when the adhesion layer 28 is attached to the cylindrical shell 14. In embodiments, such as that illustrated at FIGS. 2 and 3, the seam 58 is parallel to the longitudinal axis 20. In other embodiments, such as that illustrated at FIG. 5, the adhesion layer 28 is spirally disposed over the cylindrical shell 14, along at least a portion of the length 26 thereof. In such embodiments, the seam 58 that the edges 56a, 56b of the adhesion layer 28 form is likewise spirally disposed over the cylindrical shell 14. The seam 58 is disposed closer to the longitudinal axis 20 than the end faces 36 of the first adhesion elements 32.

[0065] In embodiments, the seam 58 that the adhesion layer 28 forms is sealed with a sealant. The sealant prevents contaminants, such as solvent, from flowing below the adhesion layer 28 and disrupting the adhesion of the adhesion layer 28 to the cylindrical shell 14. The sealant does not need to have a thickness that extends as far away from the longitudinal axis 20 as end faces 36 of the first adhesion elements 32. Rather, in embodiments, the sealant is applied to be flush with the carrier of the adhesion layer 28.

[0066] In embodiments, the flexographic printing assembly 10 further includes a double-sided adhesive layer 60. In embodiments where the cylindrical shell 14 is not utilized, the double-sided adhesive layer 60 is disposed over the outer circumferential surface 22 of the printing cylinder 12. In embodiments where the cylindrical shell 14 is utilized, the double-sided adhesive layer 60 is disposed over the outer circumferential surface 24 of the cylindrical shell 14. In both embodiments, the adhesion layer 28 is disposed over an outer surface 62 of the double-sided adhesive layer 60. In embodiments, the double-sided adhesive layer 60 is or includes a foam, fiber, or film tape or sheet with adhesive disposed on both major surfaces of the tape or sheet. The foam of the double-sided adhesive layer 60 can include a polyurethane or a polyolefin, among other options, and can be open-cell or closed-cell.

[0067] Referring now to FIGS. 6 and 7, in embodiments, the adhesion layer 28 further includes second adhesion elements 64 in addition to the first adhesion elements 32. The second adhesion elements 64 extend from the carrier sheet 30 radially inward toward the longitudinal axis 20. Like the first adhesion elements 32, the second adhesion elements 64 each include an elongated body 34 that terminates in an end face 36. The first adhesion elements 32 and the second adhesion elements 64 face in opposite directions. In embodiments of the adhesion layer 28 that include the second adhesion elements 64, the flexographic printing assembly 10 need not include the double-sided adhesive layer 60, and the adhesion layer 28 directly contacts the outer circumferential surface 24 of the cylindrical shell 14, with the end faces 36 of the second adhesion elements 64 operably coupled thereto. As mentioned, the cylindrical shell 14 may be omitted, and in such embodiments, the adhesion layer 28 directly contacts the outer circumferential surface 22 of the printing cylinder 12, with the end faces 36 of the second adhesion elements 64 operably coupled thereto.

[0068] The first adhesion elements 32 and the second adhesion elements 64 may share a carrier sheet 30 in common. Alternatively, the first adhesion elements 32 can be formed on a carrier sheet 30 (with or without a secondary polymer sheet 54), the second adhesion elements 64 can be formed on a different carrier sheet 30 (with or without a secondary polymer sheet 54), and the two carrier sheets 30 (or secondary polymer sheets 54) can be bonded together.

[0069] In embodiments, the first adhesion elements 32 have different characteristics than the second adhesion elements 64. The differing characteristics result in the first adhesion elements 32 and the second adhesion elements 64 having different levels of adhesion. The level of adhesion that is optimal for the second adhesion elements 64 to adhere to the printing cylinder 12 or the cylindrical shell 14, as the case may be, may be different than the level of adhesion that is optimal for the flexible printing plate 40 to adhere to the first adhesion elements 32. In embodiments, the characteristics that differentiate the first adhesion elements 32 from the second adhesion elements 64 include one or more of: compositions that are different, hardnesses that are different, heights 46 that are different, end faces 36 of different shapes, and densities (e.g., number of adhesion elements per unit area) that are different.

[0070] In embodiments, the flexographic printing assembly 10 includes the flexible printing plate 40. The flexible printing plate 40 is releasably coupled to the first adhesion elements 32 of the adhesion layer 28. The flexible printing plate 40 is utilized to deposit ink onto a substrate with the desired patterns and images. The flexible printing plate 40 can be formed of rubber or photopolymer blends, among other options, with a polyethylene terephthalate backing. The flexible printing plate 40 is typically manufactured flat.

[0071] A temporary sealant can seal edges of the flexible printing plate 40 to the adhesion layer 28. The flexible printing plate 40 typically is flat in its native, unapplied, state, and slightly resists bending to form on the adhesion layer 28. The temporary sealant helps prevent edges 66 and corners 68 of the flexible printing plate 40 from lifting off the adhesion layer 28. A temporary sealant is any sealant that can be dissolved or otherwise removed from the flexible printing plate 40 and the adhesion layer 28. In embodiments, the temporary sealant is a water-soluble polymer, such as polyvinyl alcohol, ethylene vinyl alcohol, polyacrylic acid, alkali-neutralized polymers of acrylic acid, carboxymethyl cellulose, a polyacrylamide, polyethylene glycol, and copolymers of any of the foregoing. In embodiments, the temporary sealant is a polymer that readily degrades when impinged upon by electromagnetic radiation having a wavelength within a range of from 250 nm to 800 nm. In embodiments, the temporary sealant is a polymer that readily degrades by the action of nucleophiles, such as the hydroxide ion or a sulfide. The temporary sealant helps prevent cleaning solvents and contaminants from the printing process from entering between the flexible printing plate 40 and the adhesion layer 28. Such cleaning solvents and contaminants might cause the edges 66 and the corners 68 of the flexible printing plate 40 to separate from the adhesion layer 28. The composition of the temporary sealant allows the temporary sealant to be removed easily from both the flexible printing plate 40 and the adhesion layer 28 after the printing process has completed.

[0072] Referring now to FIG. 8, in embodiments, the adhesion layer 28 further includes a first region 70 of the first adhesion elements 32 and a second region 72 of the first adhesion elements 32. In embodiments, a density of the first adhesion elements 32 at the first region 70 is different than a density of the first adhesion elements 32 at the second region 72. In embodiments, the end faces 36 of the first adhesion elements 32 at the first region 70 have a shape that is different than a shape of the end faces 36 of the first adhesion elements 32 at the second region 72. Through differentiation of the density or shape of the end faces 36, the first region 70 and the second region 72 can be tailored to have different degrees of adhesion to the flexible printing plate 40.

[0073] The first region 70 and the second region 72 can be positioned relative to each other so that the first adhesion elements 32 of both the first region 70 and the second region 72 releasably couple to the flexible printing plate 40 - but to different areas of the flexible printing plate 40. For example, (i) the first region 70 of the first adhesion elements 32 can be positioned relative to the second region 72 of the first adhesion elements 32 to releasably couple with the edges 66 and the corners 68 of the flexible printing plate 40, while (ii) the second region 72 of the first adhesion elements 32 is positioned relative to the first region 70 to releasably couple with a central portion 74 of the flexible printing plate 40. The density of the first adhesion elements 32 of the first region 70, or the shape of the end faces 36 of the first adhesion elements 32 of the first region 70, can be tailored to provide increased adhesion to the edges 66 and the corners 68 of the flexible printing plate 40, which more readily separate from the adhesion layer 28 than the central portion 74 of the flexible printing plate 40. In turn, the density of, or the shape of the end faces 36, of the first adhesion elements 32 of the second region 72 can be tailored to have relatively less adhesion to the central portion 74 of the flexible printing plate 40 than the adhesion of the first adhesion elements 32 of the first region 70 to the edges 66 and the corners 68 of the flexible printing 40. Visual differentiation between the first region 70 and the second region 72 of the first adhesion elements 32, in embodiments, provides a visual guide for a user as to where the flexible printing plate 40 should be applied upon the adhesion layer 28. The differing densities of the first region 70 and the second region 72 can provide such visual indication to the user.

[0074] Referring now to FIG. 9, a method 76 is herein described. At a step 78, the method 76 includes disposing the adhesion layer 28 over the outer circumferential surface 22, 24 of (i) the printing cylinder 12 or (ii) the cylindrical shell 14 that is configured to be coupled to the printing cylinder 12. Before the adhesion layer 28 is so disposed, the outer circumferential surface 22, 24 can be cleaned with a solvent to remove any residue or debris that would hinder adhesion of subsequent material to the outer circumferential surface 22, 24.

[0075] At a step 80, the method 76 includes aligning the edges 58a, 58b of the adhesion layer 28 together to form the seam 58. In embodiments, as discussed, the seam 58 is aligned parallel to the longitudinal axis 20. In other embodiments, as discussed, the seam 58 is spirally disposed over the outer circumferential surface 22, 24 of the printing cylinder 12 or the cylindrical shell 14, as the case may be. An automated taping machine may be utilized to apply the adhesion layer 28 spirally onto the printing cylinder 12, which may dramatically reduce the time required to prepare the printing cylinder 12 and cylindrical shell 14 for the printing process.

[0076] At a step 82, the method 76 includes sealing the seam 58 with a sealant, which can be any of those previously discussed. [0077] In embodiments, at a step 84 that occurs before the step 78, the method 76 further includes disposing the double-sided adhesive layer 60 over the outer circumferential surface 22, 24 of the printing cylinder 12 or the cylindrical shell 14, as the case may be. As a consequence, the adhesion layer 28, at the step 78, is disposed over the double-sided adhesive layer 60. To dispose the double-sided adhesive layer 60 onto the cylindrical shell 14, a sheet of the material forming the double-sided adhesive layer 60 is cut slightly larger than the cylindrical shell 14, both along the longitudinal axis 20 and the circumference of the cylindrical shell 14. The cut sheet of the material is placed on a surface (such as a marble table) and the cylindrical shell 14 is rolled on the cut sheet of the material with the use of a bar for even pressure. As the cylindrical shell 14 is rolled on the cut sheet of the material, the cut sheet of the material adheres to the cylindrical shell 14, thus forming the double-sided adhesive layer 60. The printing cylinder 12 with the double-sided adhesive layer 60 attached can be inspected for air bubbles or debris under the double-sided adhesive layer 60. Small bubbles can be popped. If large bubbles or debris are present under the double-sided adhesive layer 60, then the double-sided adhesive layer 60 is removed and a new attempt is made to apply the double-sided adhesive layer 60 with a new piece of material. After the double-sided adhesive layer 60 is applied with sufficient quality, the material is trimmed to create a perfect seam parallel to the longitudinal axis 20. The doublesided adhesive layer 60 can be applied instead to the outer circumferential surface 22 of the printing cylinder 12 in the same manner, if no cylindrical shell 14 is to be utilized.

[0078] In embodiments where the double-sided adhesive layer 60 is disposed over the outer circumferential surface 22, 24 of the printing cylinder 12 or the cylindrical shell 14, as the case may be, the step 78 of disposing the adhesion layer 28 over the double-sided adhesive layer 60 can be performed as follows. The adhesion layer 28 is placed on a flat surface with the first adhesion elements 32 facing the flat surface. In embodiments of the adhesion layer 28 without the second adhesion elements 64, the carrier sheet 30, or secondary polymer sheet 54 if utilized, faces upwards away from the flat surface. Any protective film over the double-sided adhesive layer 60 is removed. The printing cylinder 12, or the cylindrical shell 14, as the case may be, with the double-sided adhesive layer 60 is rolled over and attached to the carrier sheet 30 (or secondary polymer sheet 54, if utilized) of the adhesion layer 28. If inspection reveals bubbles

Y1 or debris, then the double-sided adhesive layer 60 and the adhesion layer 28 are removed and another attempt is made. The adhesion layer 28 is sized to form the seam 58, as explained at the step 80. At this point, the printing cylinder 12, or the cylindrical shell 14, as the case may be, with the adhesion layer 28 can be packaged into protective paper and sent to a user. In embodiments of the adhesion layer 28 with the second adhesion elements 64, the double-sided adhesive layer 60 is not included, and the second adhesion elements 64 face upward on the flat surface, and the printing cylinder 12 or the cylindrical shell 14, as the case may be, is rolled over and attached to the second adhesion elements 64.

[0079] In embodiments, at a step 86, the method 76 further includes disposing the flexible printing plate 40 onto the first adhesion elements 32 of the adhesion layer 28. As discussed, the first adhesion elements 32 adhere to the flexible printing plate 40 via electrostatic interaction and van der Waals forces. In embodiments of the adhesion layer 28 that include the first region 70 and the second region 72 of the first adhesion elements 32, the edges 66 and the corners 68 of the flexible printing plate 40 can be disposed onto the first region 70, while the central region of the flexible printing plate 40 can be disposed on the second region 72 of the first adhesion elements 32. The flexible printing plate 40 can be applied with a roller either manually or with the aid of a machine.

[0080] In embodiments, at a step 88, the method 76 further includes performing a printing operation with the flexible printing plate 40, while the flexible printing plate 40 is disposed on the adhesion layer 28. The printing operations that can be performed are known in the art. In general, as the printing cylinder 12 rotates, the flexible printing plate 40 captures ink. As the printing cylinder 12 rotates about the longitudinal axis 20, an impression drum distributes a substrate (e.g., paper) to the printing cylinder 12. The flexible printing plate 40 transfers ink to the substrate. The printing operation typically utilizes multiple flexible printing plates 40 to create an image, with each flexible printing plate 40 transferring ink of one color to the substrate. [0081] In embodiments, after the step 88, the method 76 further includes a step 90 of removing the flexible printing plate 40 from the adhesion layer 28. For example, one of the corners 68 of the flexible printing plate 40 can be pulled away from the adhesion layer 28. Such pulling causes the flexible printing plate 40 to separate from the adhesion layer 28. The flexible printing plate 40 can be pulled sufficiently to remove the flexible printing plate 40 from the adhesion layer 28. [0082] In embodiments, at a step 92, the method 76 further includes cleaning the first adhesion elements 32 of the adhesion layer 28. For example, the first adhesion elements 32 can be contacted with a solvent, such as isopropyl alcohol, or soap and water. The cleaning removes ink, oil, and other residue from the adhesion layer 28. The presence of debris between the adhesion layer 28 and the flexible printing plate 40 may diminish print quality.

[0083] In embodiments, at a step 94, the method 76 further includes disposing the flexible printing plate 40 or another flexible printing plate 40 onto the first adhesion elements 32 of the adhesion layer 28.

[0084] In embodiments, at a step 96, the method 76 further includes repeating the steps 88-94 at least 200 times without removing the adhesion layer 28. Because the adhesion layer 28 adheres to the flexible printing plate 40 in a non-permanent, self-adhesive fashion, one or more flexible printing plates 40 can be applied to and removed from the same adhesion layer 28 many times. In addition, because the flexible printing plate 40 is coupled to the printing cylinder 12 via direct contact with the adhesion layer 28 rather than via direct contact with the double-sided adhesive layer 60, the doubled-sided adhesive layer 60 does not need to be removed and replaced after every printing operation is performed with the flexible printing plate 40. Thus, inclusion of the adhesion layer 28 results in less waste. Further, the presence of the first adhesion elements 32 between the carrier sheet 30 and the flexible printing plate 40 helps prevent the formation of air bubbles between the adhesion layer 28 and the flexible printing plate 40. The presence of such air bubbles can diminish print quality. Finally, because the adhesion layer 28 can be made quite thin, the adhesion layer 28 can be utilized with cylindrical shells 14 with a wide range of outer diameters 16.