Flexographic printing plates and masks for highlights printed with low contrast.

Abstract

A highlight microdot mask element has at least one drawing block, at least one drawing area which is light-transmitting, and at least one opaque island formed by at least one non-drawing block, wherein the arrangement of the plurality of drawing areas and the at least one opaque island includes at least one opaque island which defines a highlight microdot print surface pattern, and opaque void areas surrounding the highlight microdot pattern. A flexographic printing plate highlight microdot print head has at least one raised area, each raised area having at least one raised block which forms a print surface, and at least one internal recess formed by at least one recess block, wherein the arrangement of the plurality of raised areas and the at least one recess includes at least one internal recess which defines a highlight microdot print surface pattern of the highlight microdot structure, and recessed void areas surrounding the highlight microdot structure.

Description

[Technical Field]

[0001] The present disclosure relates to a mask for a flexographic printing plate precursor, an imaging assembly including the mask, a flexographic printing plate having a pattern of the mask, and a masking method using the same. More particularly, the present disclosure relates to flexographic printing using a pattern print head for a highlight area having highlight dots, as well as a mask, an assembly and a flexographic printing plate having the same or corresponding highlight dot features. [Background Art]

[0002] In the technical field of graphic arts, many well-established printing processes utilize an image carrier having a three-dimensional (3D) representation of image data. The most common printing method is flexographic printing, which uses a flexible relief plate or sleeve having relief to obtain a 3D representation of image data. The relief plate includes raised relief features raised from a plate floor, and the spaces between the raised features can be at the same level as the plate floor or exist as depressions that are dimensioned lower than the top of the raised relief features. In many cases, the raised relief surface is consistent across a plurality of raised features. It is the raised features that receive ink and transfer it to a substrate. These raised features are often referred to as dots or dot structures of a flexographic printing plate. Conventional flexographic prepress processes by chemical etching do not allow fine adjustment of relief properties other than the distance between dot structures and the relief depth between or around the dot structures.

[0003] Flexographic printing uses a flexible relief plate 20 to print on a wide variety of substrates, including paper, cardboard, plastic, and metal film. A schematic diagram of a flexographic printing press is shown in Figure 1. Ink 10 in the fountain pan 26 is taken in by a rubber fountain roll 12 and transferred to the surface of anilox roll 14. The surface of the anilox roll 14 consists of a series of concave cells, which allow for precise measurement of the ink volume. A doctor blade 16 removes any excess ink 10 from the anilox roll 14, after which the ink 10 is transferred to the printing cylinder 18. A flexographic printing plate 20, which can also be called a flexographic relief plate, is mounted on the printing cylinder 18. In the final step, the ink 10 is transferred from the relief plate 20 to the substrate 22, during which the impression cylinder 24 supports the substrate 22.

[0004] An embodiment of the flexographic printing plate 20 in Figure 1 can be seen as plate 200 in Figure 2. Plate 200 is shown to include a solid area raised feature 204, an isolated dot raised feature 208, and a raised feature 212 containing a series of shortly spaced dots produced by a halftone screen. The height of the plate relief from the plate bed 220 is indicated by the relief depth 216. For each aperture in the drawing layer, a cone of UV light (typically at an angle of about 40 degrees from the plate normal) propagates through plate 20 to form the conical relief dots 208 and 212. The spacing of the dot structure within the series of raised features 212 can be sufficiently spaced so that highlight areas can be printed. However, individual dots may still be visible in the printed highlight areas, which is a defect of flexographic printing in highlight areas that fade out to zero visibility in the image.

[0005] The process used to generate an image on a flexible relief plate 20 typically includes the following steps: exposing the back of the plate with UV light (Step 1); drawing the desired image by exposing an intermediate film (Step 2); laminating this film onto the plate (Step 3); exposing the plate through the film with UV light (Step 4); removing the film (Step 5); cleaning the unexposed plate material with a solvent (Step 6); further exposing to harden the plate (Step 7); drying the plate to remove as much solvent as possible (Step 8).

[0006] Step 1, backside exposure, is used to establish the bed portion 220 of the plate 20, as shown in Figure 2, a cross-sectional view of an exemplary plate 20. The intensity of the exposure decreases as the illumination penetrates the plate and is absorbed into the plate material. When the intensity falls below a threshold, the crosslinking in the polymer constituting the plate becomes insufficient, and the remaining underexposed polymer can be washed away. This is typically the top 0.5 mm of the plate. To form the relief, the front surface of the plate is exposed with sufficient intensity so that sufficient crosslinking occurs throughout, through the image layer, up to the plate bed portion 220.

[0007] In flexographic printing, the tonal range of an image is created by a proportional total ink amount using a halftone screen. Figure 3 shows a halftone screen 300 with a tonal range that changes from 0% of tone 310 to 100% of tone 320. The small dots of tone 310 are called highlight dots.

[0008] Under practical printing conditions, the goal is to produce structured highlight dots that print a highlight image with individual highlight dots that are almost invisible to the human eye, resulting in low contrast at normal viewing distances and being difficult for package viewers to see. The highlight image may fade out to zero visibility. In flexographic printing, which uses a raised printing surface of dot structure, the ink tends to be pushed out from the top of the dots during the printing process, resulting in the dots becoming larger than the size of the dot structure on the plate. There is a threshold point at which the dots with the lowest dot area percentage become visible to the human eye under normal viewing conditions. Since the normal viewing distance for a package is the length of an arm, the dot size that becomes visible is typically in the range of 50-60 micrometers.

[0009] However, the resolution of the eye is limited, which determines how close two objects can get before they blur into one. Humans are thought to be able to distinguish two lines separated by about 0.01 degrees, or a gap of 0.026 mm, at a distance of 15 cm from the face. In reality, objects 0.04 mm (40 micrometers) wide (the width of a human hair) can barely be distinguished by good eyes, and objects 0.02 mm wide cannot be distinguished (sciencefocus / com / the-human-body / how-small-can / the-naked-eye / see / ). Therefore, a 40-micrometer dot may be barely distinguishable by good eyes, and at 50-60 micrometers, the dot is visible to good eyes but barely distinguishable to poor eyes. This explains why halftone dots of about 40 micrometers are barely visible to the human eye at a focal length of 280 mm (11 inches), but these dots become clearly visible beyond 50-60 micrometers. The visibility of this dot size affects the printing of highlight areas in flexographic printing. The visibility of the dots can cause highlights to appear as polka dots.

[0010] On the other hand, the rotary gravure printing process consists of copper-clad cylinders with engraved cells that hold the ink to be printed, but many smaller dots are used, which shrink during printing without dot gain because the ink resists spreading. In gravure printing, small dots are printed, which have very low contrast and deceive the eye like a kind of illusion, and the print fades out to zero at a normal viewing distance, so that the dots disappear from view to the human eye. The dots printed in gravure printing appear to have brighter contrast, but this is because the cell walls of each dot tend to hold the ink, thereby transferring only a small portion of the ink in reality, and the percentage increases as the size of the cell increases.

[0011] In flexographic printing, attempts are made to print small dots in highlight areas, but the physical properties and limitations of the process of using dot structures for printing can be problematic. Historically, there has been a tendency to use smaller and lower-density dot structures to print highlight areas in an image. However, it has been found that if the print dot structure is too small, a donut shape or ring can form in the dots after printing. This donut shape or ring can form when dot gain occurs after printing, due to the dot structure's printhead compressing the ink and causing a halo effect, which appears as a donut or ring. The printing of the donut can occur because the ink accumulates on the outer ring, resulting in high contrast. As a result, there are problems with the ability of flexographic printing of highlight areas to fade out to zero visibility. When a visible edge is observed at the transition point due to dot gain after printing, the ring becomes visible, which contradicts the need to print highlight areas that can fade out to zero visibility in optimal printing.

[0012] Figure 4A shows gravure-printed dots compared to flexographic (flexo)-printed dots at 200x magnification. Flexographic dots are printed as microdots with dimensions of 25 micrometers, but due to the spreading of these small dots and the formation of donut or ring shapes, the printed dots appear to be approximately 45 micrometers in size, which is clearly visible to the eye as a donut or ring shape. However, gravure-printed dots appear faded or softer. At 1% coverage, there are approximately 12 flexo dots, with a gravure print tone of 3.3% and a flexo print tone of 3.1%. At 4% coverage, there are approximately 25 flexo dots, with a gravure print tone of 4.6% and a flexo print tone of 4%. This trend is similar at 3% and 4%, with gravure prints fading or becoming brighter, while flexographic prints have many halo dots. Figure 4B shows 1% tones of gravure and flexographic prints, illustrating the undesirable, prominent donut or ring-shaped patterns of microdots in the flexographic print. The number of flexographic dots is 4, while the number of gravure dots exceeds 20, a striking contrast. Therefore, creating smaller highlight dot structures for printing highlight areas does not appear suitable for the resulting highlight image, as the donut shape of the highlight microdots is visible in the flexographic print.

[0013] Flexographic printing requires a minimum dot size to guide UV light energy to the plate, curing the photopolymer and allowing for the precise formation of dot structures. Therefore, there are limits to how small the highlight dot structure can be. Furthermore, the donut effect causes the problem of undesirable, clearly visible small donut-shaped dots appearing due to the small printed dots. Flexographic printing tends to use smaller dot structures in the highlight areas of an image, but these dot structures can sometimes be too small to adequately form the correct shape on the plate. Smaller sizes can make the microdot structure unstable. Also, smaller sizes can cause printed microdots to expand in size, appearing visually as a donut shape.

[0014] In the past, dot structures and dot patterns on flexographic printing plates have been studied to improve print image quality. U.S. Patent No. 8,896,894 teaches structured microdots and methods for manufacturing and using them. U.S. Patent No. 9,067,402 teaches methods for forming flexographic printing systems. U.S. Patent No. 9,152,897 teaches flexographic printing systems and digital imaging for printing. U.S. Patent No. 9,235,126 teaches methods for forming flexographic printing plates using fine dot turns in the edge regions of an image and coarser patterns in the interior regions of the image. U.S. Patent No. 9,375,910 teaches a digital front-end for identifying pixels in a halftone image as part of an edge region or interior region, based on their proximity to image edge features. U.S. Patent No. 10,150,319 (International Publication No. 2018 / 226409 brochure) teaches a method for using a gap between a fine texture pattern (edge ​​region) and a coarse texture pattern (interior region). U.S. Patent Application Publication No. 2010 / 0224091 teaches a relief rear edge pattern for reducing rear edge inking voids.

[0015] Given the flaw in flexographic printing where donut-shaped dots are printed in the highlight areas instead of fading out to zero visibility, improvements to the flexographic printing plate are desirable to obtain better highlight images that fade out more smoothly to zero visibility. [Overview of the project] [Means for solving the problem]

[0016] In some embodiments, a highlight microdot mask element may include a plurality of drawing regions arranged in a highlight microdot printed surface pattern. Each drawing region may have at least one light-transmitting drawing block. The highlight microdot mask element may also include at least one opaque island formed by at least one non-drawing block within the highlight microdot printed surface pattern, and the arrangement of the plurality of drawing regions and at least one opaque island defines the highlight microdot pattern. The highlight microdot mask element may also include opaque void regions surrounding the microdot pattern formed by the plurality of non-drawing blocks. The blocks are arranged in a grid pattern, with the sides of each block within the grid. The blocks have a height in one direction and a width in a perpendicular direction. The blocks may be rectangular or square if the sides are equal. Drawing blocks may form recesses, openings (e.g., optical apertures), or optical paths from the drawing process, while non-drawing blocks in the mask are opaque or non-light-transmitting and do not form any optical paths. In some embodiments, each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel. Each pixel has a height and width of approximately 10 to 11 micrometers (e.g., substantially square). In some embodiments, the width of each drawing area is at least 1 / 4 pixel, the height of each drawing area is at least 1 pixel, the width of the microdot pattern ranges from 2 to 8 pixels, the height of the microdot pattern ranges from 3 to 8 pixels, the width of each internal opaque island is at least 1 / 4 pixel, and the height of each internal opaque island is at least 1 pixel.In some embodiments, the width of at least one drawing area is at least 1 / 2 pixel, the height of at least one drawing area is at least 2 pixels, the width of the microdot pattern is in the range of 2.5 pixels to 4 pixels, the height of the microdot pattern is in the range of 4 pixels to 6 pixels, the width of at least one internal opaque island is at least 1 / 2 pixel, the height of at least one internal opaque island is at least 2 pixels, and each non-drawn block is in contact with other drawing blocks by at least 1 / 4 pixel.

[0017] In some embodiments, the highlight microdot mask element may include: multiple drawing regions congruently form multiple outer boundary regions that form an outer boundary pattern, each outer boundary region having at least one drawing block and being light-transmitting; at least one internal opaque island formed by at least one non-drawing block within the outer boundary pattern; and opaque void regions surrounding the outer boundary pattern. In some embodiments, each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of about 10 to about 11 micrometers.

[0018] In some embodiments, the highlight microdot mask element may include: a plurality of outer boundary pixel regions forming a continuous annular boundary region where each drawing block touches another drawing block at least at a corner; or a plurality of outer boundary pixel regions forming a discontinuous annular boundary region where at least one gap of non-drawing blocks lies between two adjacent drawing blocks of the plurality of outer boundary pixel regions.

[0019] In some embodiments, the highlight microdot mask element may include: each outer boundary pixel region has a width of at least 1 / 4 pixel; each outer boundary pixel region has a height of at least 1 pixel; the outer boundary pattern has a width in the range of 2 to 8 pixels; the outer boundary pattern has a height in the range of 3 to 8 pixels; each internal opaque island has a width of at least 1 / 4 pixel; and each internal opaque island has a height of at least 1 pixel. In some embodiments, at least one outer boundary pixel region has a width of at least 1 / 2 pixel; at least one outer boundary pixel region has a height of at least 2 pixels; the outer boundary pattern has a width in the range of 2.5 to 4 pixels; the outer boundary pattern has a height in the range of 4 to 6 pixels; at least one internal opaque island has a width of at least 1 / 2 pixel; and at least one internal opaque island has a height of at least 2 pixels, with each non-drawn block touching another non-drawn block by at least 1 / 4 pixel.

[0020] In some embodiments, the highlight microdot mask element may include: one internal opaque island in a continuous annular boundary region; one internal opaque island in a discontinuous annular boundary region; multiple internal opaque islands in a continuous annular boundary region; or at least one of multiple internal opaque islands in a discontinuous annular boundary region. In some embodiments, the highlight microdot mask element according to claim 4 includes: one internal drawing region in a continuous annular boundary region; one internal drawing region in a discontinuous annular boundary region; multiple internal drawing regions in a continuous annular boundary region; or at least one of multiple internal drawing regions in a discontinuous annular boundary region. In some embodiments, the highlight microdot mask element may include: at least 20 total blocks; at least 16 drawing blocks in the pattern; at least one of at least 4 non-drawing blocks in at least one internal opaque island; or at least 20% of the total blocks are non-drawing blocks.

[0021] In some embodiments, the highlight microdot mask element may include: a plurality of outer boundary regions that collectively form a light-transmitting ring; at least one internal opaque island formed by a plurality of non-drawn blocks within the light-transmitting ring, wherein the island width is at least 1 / 2 pixel and the island height is at least 2 pixels; and an opaque void region surrounding the light-transmitting ring.

[0022] In some embodiments, a mask for a flexographic printing plate that generates highlights may include a highlight microdot mask element of one embodiment and an image pattern having a highlight mask region having the highlight microdot mask element. In some embodiments, the mask may include a highlight microdot region of a drawing material comprising a thermally ablable drawing layer having drawing blocks and non-drawing blocks arranged to form a highlight dot pattern on one highlight microdot, where one highlight microdot includes the highlight microdot mask element. In some embodiments, the mask may include: a light-transmitting ring formed by a plurality of drawing blocks, the ring thickness being at least 1 / 4 pixel, the orthogonal thickness being at least 1 pixel, the ring height being in the range of 3 to 8 pixels, and the ring width being in the range of 1 to 8 pixels; at least one internal opaque island formed by a plurality of non-drawing blocks within the light-transmitting ring, the internal opaque island having an island height of at least 1 pixel and an island width of at least 1 pixel; and an opaque void region surrounding the light-transmitting ring.

[0023] In some embodiments, the mask may include a drawing material having a thermally ablable drawing layer having drawing blocks and non-drawing blocks arranged to form an image pattern. The image pattern includes at least one highlight mask region having a plurality of highlight dot regions that form a highlight pattern within the image pattern. The highlight mask region includes a plurality of opaque regions in the thermally ablable drawing layer. Each opaque region is one or more non-drawing blocks. The highlight mask region includes a plurality of light-transmitting regions in the thermally ablable drawing layer. Each light-transmitting region may be one or more drawing blocks, and each highlight dot region includes at least one highlight microdot mask element.

[0024] In some embodiments, the mask may include: a light-transmitting ring formed by a plurality of drawing blocks, having a thickness of at least 1 / 4 pixel, a ring height in the range of 4 to 8 pixels, and a ring width in the range of 2 to 8 pixels; an internal opaque island formed by a plurality of non-drawing blocks within the light-transmitting ring, having an island width of at least 1 pixel and an island height of at least 2 pixels; and an opaque void region surrounding the light-transmitting ring formed by the plurality of non-drawing blocks.

[0025] In some embodiments, a method for forming a mask for a highlight-generating flexographic printing plate may include providing a drawable material having a thermal ablable drawing layer, providing an image pattern having at least one highlight region, the highlight region comprising a plurality of highlight microdot mask elements, each highlight microdot mask element comprising a microdot pattern formed by the arrangement of a plurality of drawing regions and at least one opaque island, and drawing on the drawable material to form a mask image on the thermal ablable drawing layer. In some embodiments, the mask image comprises an image pattern having at least one highlight region. In some embodiments, the highlight region comprises a plurality of highlight microdot mask elements. In some embodiments, each highlight microdot mask element comprises a microdot pattern formed by a plurality of drawing blocks in the thermal ablable drawing layer, and at least one opaque island in the thermal ablable drawing layer is formed by at least one non-drawing block. The drawing blocks and non-drawing blocks are arranged to jointly form a microdot pattern in the mask image, and the opaque void region formed by the plurality of non-drawing blocks surrounds the microdot pattern.

[0026] The flexographic printing plate highlight microdot printhead comprises: a plurality of raised regions arranged in a highlight microdot print surface pattern, each raised region forming a print surface; at least one internal recess formed by at least one recessed block within the highlight microdot print surface pattern, the arrangement of the plurality of raised regions and at least one recess defining a microdot pattern of microdots; and recessed void regions surrounding the microdot pattern formed by the plurality of recessed blocks, where the recessed surface of each recessed block includes a recessed void region lower than each print surface. In some embodiments, each raised or recessed block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of approximately 10 to 11 micrometers. In some embodiments, the width of each raised region is at least 1 / 4 pixel, the height of each raised region is at least 1 pixel, the width of the microdot pattern is in the range of 2 to 8 pixels, the height of the microdot pattern is in the range of 3 to 8 pixels, the width of each internal recess is at least 1 / 4 pixel, and the height of each internal recess is at least 1 pixel. In some embodiments, the width of at least one raised region is at least 1 / 2 pixel, the height of at least one raised region is at least 2 pixels, the width of the microdot pattern is in the range of 2.5 to 4 pixels, the height of the microdot pattern is in the range of 4 to 6 pixels, the width of at least one internal opaque island is at least 1 / 2 pixel, the height of at least one internal opaque island is at least 2 pixels, and each non-drawn block is in contact with other non-drawn blocks by at least 1 / 4 pixel.

[0027] In some embodiments, a flexographic printing plate highlight microdot print head can comprise: a plurality of raised regions forming a plurality of outer boundary regions that collectively form an outer boundary pattern, each outer boundary region having at least one raised block forming a printing surface; at least one internal recess formed by at least one recess block located within the outer boundary pattern; and a recessed void region surrounding the outer boundary pattern. In some aspects, each raised block or recess block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and a width of from about 10 micrometers to about 11 micrometers.

[0028] In some embodiments, a flexographic printing plate highlight microdot print head can comprise: a plurality of outer boundary regions forming a continuous annular boundary region, where each raised block contacts at least one corner of another raised block. In some embodiments, the plurality of outer boundary regions form a discontinuous annular boundary region with at least one concave gap between every two adjacent raised blocks of the plurality of outer boundary regions. In some aspects, the width of each outer boundary region is at least 1 / 4 pixel, the height of each outer boundary region is at least 1 pixel, the width of the outer boundary pattern ranges from 2 pixels to 8 pixels, the height of the outer boundary pattern ranges from 3 pixels to 8 pixels, the width of each internal recess block is at least 1 / 4 pixel, and the height of each internal recess block is at least 1 pixel. In some aspects, the width of at least one outer boundary region is at least 1 / 2 pixel, the height of at least one outer boundary region is at least 2 pixels, the width of the outer boundary pattern ranges from 2.5 pixels to 4 pixels, the height of the outer boundary pattern ranges from 4 pixels to 6 pixels, the width of at least one internal recess block is at least 1 / 2 pixel, the height of at least one internal recess block is at least 2 pixels, and each recess block contacts other recess blocks by at least 1 / 4 pixel.

[0029] In some embodiments, the flexographic printing plate highlight microdot print head may comprise at least one of: one inner recessed region within a continuous annular boundary region; one inner recessed region within a discontinuous annular boundary region; a plurality of inner recessed regions within a continuous annular boundary region; or a plurality of inner recessed regions within a discontinuous annular boundary region.

[0030] In some embodiments, the flexographic printing plate highlight microdot print head may comprise at least one of: one inner raised region within a continuous annular boundary region; one inner raised region within a discontinuous annular boundary region; a plurality of inner raised regions within a continuous annular boundary region; or a plurality of inner raised regions within a discontinuous annular boundary region.

[0031] In some embodiments, the flexographic printing plate highlight microdot print head may comprise at least one of: a total of at least 20 raised blocks and recessed blocks; at least 16 raised blocks in a pattern; at least 4 recessed blocks within at least one recessed region, or at least 20% of the total blocks are recessed blocks.

[0032] In some embodiments, the flexographic printing plate highlight microdot print head may comprise: a plurality of outer boundary regions collectively form a printing surface ring; at least one inner recessed region formed by a plurality of recessed blocks located within the printing surface ring, wherein the inner recessed region has a width of at least 1 / 2 pixel and a height of at least 2 pixels; and the recessed void region surrounds the printing surface ring.

[0033] In some embodiments, a flexographic printing plate may include a highlight microdot printhead of one embodiment and an image pattern having a highlight region having the highlight microdot printhead. In some embodiments, the flexographic printing plate may include a highlight microdot region of a relief drawing material having a relief-forming layer having raised and recessed blocks arranged to form a highlight microdot pattern on one highlight microdot, the one highlight microdot including the highlight microdot printhead.

[0034] In some embodiments, the flexographic printing plate may include a highlight microdot printhead from one embodiment and an image having a highlight region with the highlight microdot printhead.

[0035] In some embodiments, the flexographic printing plate is: a printing surface ring formed by a plurality of raised blocks, with a ring thickness of at least 1 / 4 pixel, a perpendicular thickness of at least 1 pixel, a ring height in the range of 3 to 8 pixels, and a ring width in the range of 1 to 8 pixels; and may include at least one internal recessed region formed by a plurality of recessed blocks within the printing surface ring, having a height of at least 1 pixel and a width of at least 1 pixel; the recessed void region surrounds the printing surface ring.

[0036] In some embodiments, a flexographic printing plate may include a relief drawing material having a relief-forming layer having raised and recessed blocks arranged to form an image pattern. The image pattern includes at least one highlight region having a plurality of highlight microdots that form a highlight pattern within the image pattern. Each highlight microdot includes a plurality of recessed regions in the relief-forming layer. Each recessed region may be one or more recessed blocks. Each highlight microdot includes a plurality of raised regions in the relief-forming layer. Each raised region may be one or more raised blocks, and each raised block of a highlight microdot has a printing surface.

[0037] In some embodiments, a flexographic printing plate may include: a printing surface ring formed by a plurality of raised blocks, the ring thickness being at least 1 / 4 pixel, the ring height being in the range of 4 to 8 pixels, and the ring width being in the range of 2 to 8 pixels; an internal recessed region formed by a plurality of recessed blocks within the printing surface ring, the internal recessed region having a width of at least 1 pixel and a width of at least 2 pixels; and a recessed void region surrounding the printing surface ring and formed by a plurality of recessed blocks.

[0038] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the descriptive aspects, embodiments, and features described above, other aspects, embodiments, and features will become apparent upon reference to the attached drawings and the detailed description below.

[0039] Brief explanation of the drawing In addition to the information above and below, other features of this disclosure will become more readily apparent by reading the following description and the accompanying claims with reference to the accompanying drawings. Given that these drawings depict only some embodiments of this disclosure and are therefore not intended to limit its scope, the disclosure will be described more specifically and in detail using the accompanying drawings. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic representation of a flexographic printing system and process. [Figure 2] This is a schematic cross-sectional view of one embodiment of a flexographic printing plate. [Figure 3] This is a flexographic printing representation of a highlight image that includes visible dots. [Figure 4A] Includes images of gravure printed dots compared to visible dots produced by flexographic printing. [Figure 4B] This is an enlarged view of Figure 4A. [Figure 4C] This is a schematic representation of flexographic printing of donut-shaped highlight dots. [Figure 4D] This is a schematic diagram of flexographic printing of highlight dots, where the gradient is darker in the center and becomes lighter and less visible towards the edges. [Figures 5A-5D] Includes a schematic representation of the highlight microdot printhead pattern for masks and flexographic printing plates. [Figure 6A] This is an SEM image of a microdot print head array showing print surface pattern 4A, with a scale bar of 250 micrometers (magnification 250×). [Figure 6B] Figure 6A is an SEM image of the highlight microdot printing head array with a scale bar of 100 micrometers (magnification 500×). [Figure 6C] This is an SEM image of a microdot print head array showing the 5Q5 print surface pattern, with a scale bar of 250 micrometers (magnification 250×). [Figure 6D] Figure 6C is an SEM image of the highlight microdot printing head array with a scale bar of 100 micrometers (magnification 500×). [Figure 6E] This is an SEM image of a microdot print head array showing the 5Q7 print surface pattern, with a scale bar of 250 micrometers (magnification 250×). [Figure 6F]Figure 6E is an SEM image of the highlight microdot printing head array with a scale bar of 100 micrometers (magnification 500×). [Figure 7A] This is a schematic cross-sectional view of an embodiment having a highlight microdot structure with a printed surface pattern. [Figure 7B] This is a schematic cross-sectional view of an embodiment having a highlight microdot structure with ink for a printed surface pattern. [Figure 8A] This is a schematic cross-sectional view showing incident infrared radiation useful for fabricating mask elements in one embodiment of the mask master according to the present invention. [Figure 8B] Figure 8A is a schematic cross-sectional view of an embodiment in which a mask element is formed from a mask master plate. [Figure 8C] This is a schematic cross-sectional view of one embodiment of a relief drawing assembly according to the present invention, which includes a mask element shown in Figure 8B that is in full optical contact with the relief forming master. [Figure 8D] Figure 8B is a schematic cross-sectional view of one embodiment in which a drawn relief-forming master is formed using incident UV radiation passing through a mask element shown. [Figure 8E] Figure 1D is a schematic cross-sectional view of an embodiment in which a relief image element is provided after drawing and a suitable development process for removing unexposed areas in the UV-sensitive layer of the drawn relief-forming master plate. [Figure 9] This is a schematic cross-sectional view of the relief molding plate. [Modes for carrying out the invention]

[0041] The elements and components in the figures can be arranged according to at least one of the embodiments described herein, and those skilled in the art can modify this arrangement according to the disclosure provided herein.

[0042] Detailed explanation In the following detailed description, references are made to the accompanying drawings which constitute part of this specification. In the drawings, similar reference numerals indicate typically similar components unless the context requires otherwise interpretation. The exemplary embodiments described in the detailed description, drawings, and claims are not limiting. Other embodiments and other modifications may be available without departing from the spirit or scope of the subject matter described herein. It will be readily apparent that the aspects of this disclosure described herein and illustrated in the drawings can be arranged, substituted, combined, separated, and designed in a wide variety of configurations, all of which are explicitly assumed in this application.

[0043] Generally, the present invention relates to a flexographic printing plate used to form a highlight image having a highlight region, wherein the highlight region can optionally fade out to a zero-visibility region. The flexographic printing plate may include a highlight microdot structure of the highlight pattern, which works together to form a flexo-highlight image that can fade out to near zero visibility. The present invention also relates to a mask used to generate a flexographic printing plate having a highlight pattern of highlight microdot structures. The present invention also relates to a method for designing and manufacturing the mask and the flexographic printing plate. The present invention also relates to a method of using a flexographic printing plate to generate a print image by flexographic printing having a highlight region that optionally fades out to zero visibility. For example, the present invention relates to Miracclon's Flexcel NX system.

[0044] Highlight microdot structures in flexographic printing plates can be formed as raised areas with a printed surface pattern that can form part of the highlight region, and multiple such highlight microdot structures form the highlight image. Figure 2 can be used to show a typical microstructure with a raised area (e.g., 208 above the floor 220). Highlight microdot structures are beneficial for flexographic printing of highlight images by reducing the visibility of each individual printed highlight microdot. Highlight microdot structures include a printed surface pattern that is printed on the surface with low visibility. In some embodiments, printed highlight dots may spread much larger than the normal visual threshold at a normal viewing distance, but may still appear as highlights rather than individual dots. In standard comparisons, the highlight region of a flexographic printing plate may contain highlight microdot structures of 5% or less of the highlight image region. The shape and features of each highlight microdot structure and highlight region are defined by the mask used in the manufacture of the flexographic printing plate. Therefore, the mask is designed to be beneficial for the manufacture of flexographic printing plates with highlight regions.

[0045] In some embodiments, a highlight microdot structure, as defined herein as having a highlight microdot pattern on a printhead, is configured to overcome the halo effect from microdots that are too small or that extend beyond the highlight microdot printhead pattern. For example, when gravure printing is compared to traditional flexographic printing for highlights, it is clear that gravure dots differ from flexographic dots (e.g., 35 micrometers). Figures 4A-4B show gravure-printed dots compared to dots produced by flexography (flexo) printing as described above. Flexographic dots are microdots with dimensions of 25 micrometers, but due to the spread of these small dots and the formation of a donut shape, this dimension appears to be approximately 45 micrometers, which is clearly visible to the eye as a donut shape. However, gravure-printed dots appear to fade out or softer to the eye.

[0046] Figure 4C shows a schematic diagram of how the flexographic microdot structure of a small printhead (e.g., 35 micrometers or less in size) forms a donut shape. The microdots 402 are composed of pixels 404 or groups of four pixels, as shown in the figure. If these pixels 404 are large enough (e.g., greater than 100 micrometers), they may be printed as solid dots 406; if they are small enough (e.g., less than 35 micrometers), they may be printed as halos or donut dots 408 by the printhead pushing the ink outwards. Donut dots are undesirable in highlight printing.

[0047] Figure 4D shows a schematic diagram of how a flexographic microdot structure with a patterned microdot printhead (e.g., a size greater than 35 micrometers with a printed surface pattern) forms fade-out print dots 420. Microdots 402 are composed of pixels 404 or groups of pixels as shown in the figure, but the pattern has been omitted for clarity. Highlight microdot patterns can be seen in Figures 5A-5D. These pixels 404 can be printed as print dots 420 that fade out in a circle 410 or ellipse 412 as the printhead pushes the ink outward from the patterned microdot printhead. The patterned microdot printhead avoids the donut dots shown in Figure 4C.

[0048] mask To produce a flexographic printing plate having a highlight image of highlight microdots, a mask of the desired pattern is first generated. The mask is made to have a negative image compared to the flexographic printing plate. If the mask includes optical apertures, curing light can pass through the mask and cure the flexographic printing plate material. Thus, the pattern of the mask represents the pattern of the flexographic printing plate, but the light-transmitting regions of the mask correspond to the raised structures on the flexographic printing plate, and the optically opaque regions of the mask correspond to the recessed structures on the flexographic printing plate. The following drawings are provided to illustrate an example of a patterned microdot printing head by showing the mask and the pattern for the resulting flexographic printing plate.

[0049] Figures 5A–5D show exemplary microdot printhead patterns 500, which are in the form of an arbitrary grid 502 of block 504. These drawings show a printhead template with a height of 5 blocks and a width of 16 blocks, but the height and width may vary, such as 4–6 blocks in height and 10–20 blocks in width. As shown here, each block is 1 pixel high and 1 / 4 pixel wide, so that 4 horizontally connected blocks form 1 pixel. The blocks are designed as either print blocks 506 or blank blocks 508. Print blocks 506 correspond to the light-transmitting blocks of the mask element and correspond to the raised structures or printed surfaces of the flexographic printing plate. Blank blocks 508 correspond to the optically opaque blocks of the mask element and correspond to the recesses or void spaces of the flexographic printing plate. For illustrative purposes, the grid 502 in Figures 5A–5D is located within a mask element 510. The mask element 510 may correspond to the highlight areas of an image. Each microdot print head pattern 500 is represented by an identifier such as patterns 4A, 4B, 5A, 5B, 5C, 5D, and 5E in Figure 5A; patterns 5F, 5G, 5H, 5I, 5Q1, 5Q2, 5Q3, and 5Q4 in Figure 5B; patterns 5Q05, 5Q06, 5Q07, 5Q08, 5Q09, 5Q10, 5Q11, and 5Q12 in Figure 5C; and patterns 5Q13, 5Q14, 5Q15, and 5Q16 in Figure 5E.

[0050] The grid 502 allows any block 504 to be selected as either a print block 506 or a blank block 508. The print blocks of the mask element 510 allow light, such as UV light, to pass through and form the corresponding structure on the flexographic printing plate. The print blocks within the mask element 510 are formed by drawing on a drawable layer of the mask material. These protocols are described in detail herein. In some embodiments, the pattern may include one print block 506 that does not have any adjacent print blocks 506, which is shown as one print block 506 where all adjacent blocks 504 (e.g., vertically or horizontally) are blank blocks 508. In some embodiments, the pattern 500 may include one blank block that does not have any adjacent blank blocks 508, which is shown as one blank block 508 where all adjacent blocks (e.g., vertically or horizontally) are print blocks 506.

[0051] A single block 504 can be called a quarter-pixel (e.g., quarter-pixel) block. In some embodiments, a pattern can include a horizontally adjacent pair of printed blocks 506 as the smallest segment of block 504, or a pair of blank blocks 508 as the smallest segment of block 504, which can be called half-pixel (e.g., half-pixel) blocks. By following these rules, a mask can be fabricated in a single laser pass at full speed and with minimal defect risk. Some patterns can include quarter-pixel and one-pixel blocks, as well as quarter-pixel and half-pixel blocks. Any combination of one or more horizontally adjacent quarter-pixel blocks can be used.

[0052] The mask element 510 can be a highlight microdot mask element, which includes a plurality of drawing areas 512 (e.g., print blocks 506) arranged in a highlight microdot printing surface pattern, such as pattern 5D. Each highlight microdot printing surface is for one highlight microdot feature within the mask element 510, which corresponds to one microdot structure of the corresponding flexographic printing plate for printing the highlight image. Each drawing area 512 may have at least one print block 506 (e.g., a drawing block) and may be light-transmitting. Additionally, at least one opaque island 514 is formed by at least one blank block 508 (e.g., a non-drawing block) within the highlight microdot printing surface pattern. The arrangement of the plurality of drawing areas 512 (e.g., one or more print blocks 506) and at least one opaque island 514 defines the highlight microdot printing surface pattern 515. Furthermore, there is an opaque void area 516 surrounding the microdot printing surface pattern 515, formed by a plurality of blank blocks 508 (e.g., non-drawing blocks).

[0053] Within the mask element 510, opaque areas formed by blank blocks 508 are not drawn, and the drawing areas are printed blocks 506 for light-transmitting areas. The blocks 504 are arranged in a grid 502 pattern, with each side of the block 504 located within the grid 502. The block 504 has a height in one direction (e.g., vertical) and a width in a perpendicular direction (e.g., horizontal), with the longer dimension being the vertical direction which defines the height. The block 504 can be a rectangle in 1 / 4 pixel or a 1 / 2 pixel block, as shown in the figure, and can be a square if the sides are equal. Printed blocks 506 can form recesses, openings (e.g., optical apertures), or optical paths in the mask element 510 from the drawing process, whereas the blank blocks 508 are non-drawn blocks within the mask element 510, and they are either opaque or non-light-transmitting and do not form any optical paths.

[0054] An example of pattern 5D shows print blocks 506 arranged in a continuous ring shape for a drawing area 512 having an internal opaque island 514 within it. Other patterns in Figure 5A also show a continuous ring shape. The ring shape provides the outer wall of the flexographic printing plate, defining the outer structure with internal recesses, voids, or holes for holding ink within the microdot structure. This patterned print surface (515) of the microdot structure helps the ink spread to provide highlight dots. The highlight dot structure of pattern 5D can be 5 pixels high (e.g., about 53 micrometers) and 2.5 pixels wide (e.g., about 26.5 micrometers). Pattern 5D has 6 pixels for transmitting UV light during the formation of the flexographic printing plate highlight dot structure, which is equivalent to 2 × 3 solid dots. The formed flexographic printing plate also has 2.5 pixels of recesses for holding ink, which is 29.4% of the open area of ​​the flexographic printing plate highlight dot structure. Therefore, the highlight microdot print head can be configured as shown in pattern 5D. Within the mask element 510, the print block 506 is a drawing block in terms of the drawing protocol for forming the mask element, and therefore the blank block 508 is a non-drawing block. In some embodiments, pattern 5C may be determined to be a semi-continuous ring shape because only the corners of the print block 506 are in contact, but there are no gaps between the ring-shaped components of the drawing area.

[0055] In some embodiments, each drawing block (e.g., print block 506) or non-drawing block (e.g., blank block 508) has a height of 1 pixel and a width of 1 / 4 pixel. Each pixel also has a height and width of approximately 10 to 11 micrometers. The width of each drawing area is at least 1 / 4 pixel. The height of each drawing area is at least 1 pixel.

[0056] As shown in the figure, the width of the highlight microdot printed surface pattern 515, for example, its drawing area 512, can be in the range of 2 to 8 pixels, 2.25 to 6 pixels, 2.5 to 5 pixels, or any range in between. The height of the highlight microdot printed surface pattern 515 (e.g., drawing area 512) can be in the range of 3 to 8 pixels, for example, 4 pixels, 5 pixels, 6 pixels, or 7 pixels. The width of each internal opaque island 514 can be at least 1 / 4 pixel, but can be in the range of being within the highlight microdot printed surface pattern 515 as shown in the pattern. The height of each internal opaque island 514 is at least 1 pixel, but can be in the range of being 2 pixels less than the height of the highlight microdot printed surface pattern 515.

[0057] In exemplary embodiments, the width of at least one drawing area 512 of the highlight microdot printed surface pattern 515 is at least 1 / 2 pixel, and can range from 3 / 4 pixel or 1 pixel along the edges (e.g., patterns 5A, 5B, 5C, etc.) to 1.5 pixels along the edges (e.g., patterns 5G, 5H, and 5I). The height of at least one drawing area 512 of the highlight microdot printed surface pattern 515 is at least 2 pixels, connected to each other at least through the corners, e.g., all patterns in Figure 5A. The width of the highlight microdot printed surface pattern 515 can range from 2.5 pixels to 4 pixels. The height of the highlight microdot printed surface pattern 515 can range from 4 pixels to 6 pixels. The width of at least one internal opaque island 514 is at least 1 / 2 pixel, but can be larger within the range that fits inside the highlight microdot printed surface pattern 515. The height of at least one internal opaque island in the highlight microdot printed surface pattern 515 can be at least 2 pixels, and each non-drawn block is in contact with another drawing block by at least 1 / 4 pixel. However, it should be understood that other embodiments are also possible.

[0058] Figure 5B shows patterns having outer boundary regions formed in continuous rings (5F, 5G), semi-continuous rings (5H, 5I), and discontinuous rings 5Q1, 5Q2, 5Q3, and 5Q4. In particular, the discontinuous rings include outer drawing regions 512a, which do not touch each other, thereby creating gaps of one or more blank blocks 508 between them. Patterns 5Q1, 5Q2, 5Q3, and 5Q4 include drawing regions 512, which form annular or ring-shaped structures with opaque islands 514. Also, patterns 5H, 5I, and 5Q3 show internal drawing blocks 519 that form drawing block islands. Patterns 5Q5, 5Q6, 5Q7, and 5Q8 in Figure 5C illustrate outer drawing regions, which can be random, zigzag, or symmetrical, and can also be used by having outer boundary drawing regions 512 with internal drawing regions and internal non-drawing regions.

[0059] Figures 5C–5D show 5Q05, 5Q06, 5Q07, 5Q08, 5Q09, 5Q10, 5Q11, 5Q12, 5Q13, 5Q14, 5Q15, and 5Q16, which illustrate additional examples of complex highlighted microdot patterns having a drawing area 512 (e.g., print block 506) with a width of 1 / 4 pixel.

[0060] In some embodiments, the highlight microdot mask element may include a plurality of drawing areas 512 arranged in a highlight microdot printed surface pattern. Each drawing area may include at least one drawing block (e.g., a printed block 506) and may be light-transmitting. The mask element 510 may include at least one opaque island 514 formed by at least one non-drawing block within the highlight microdot printed surface pattern 515. The arrangement of the plurality of drawing areas 512 and at least one opaque island 514 defines the highlight microdot pattern (515). An opaque void area 516 surrounds the microdot pattern, and this opaque void area 516 is formed by a plurality of non-drawing blocks (508). The blocks 504 are arranged in a grid pattern 502, with the sides of each block 504 within the block. The blocks 504 have a height in one direction and a width in the orthogonal direction. The blocks 504 may be rectangular or square if their sides are equal. The drawing block (506) can form depressions, openings (e.g., optical openings), or optical paths from the drawing process, but the non-drawing block (508) within the mask 510 is opaque or non-transmitting and does not form any optical paths.

[0061] In some embodiments, the highlight microdot mask element may include multiple drawing regions, which together form multiple outer boundary regions that form an outer boundary pattern. Each outer boundary region may have at least one drawing block, which may be light-transmitting, and form some kind of boundary around one or more non-drawing blocks. There is at least one internal opaque island within the outer boundary pattern, which is formed by at least one non-drawing block within the outer boundary pattern. There is also an opaque void region surrounding the outer boundary pattern. In some embodiments, each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of about 10 to about 11 micrometers.

[0062] In some embodiments, a highlight microdot mask element may include multiple outer boundary pixel regions, which form a continuous annular boundary region where each drawing block touches another drawing block at at least one corner (see, for example, patterns 4A-5I). In some embodiments, the multiple outer boundary pixel regions may form a discontinuous annular boundary region where there is a non-drawing block, which is at least one gap, between two adjacent drawing blocks of the multiple outer boundary pixel regions (see, for example, patterns 5Q1, 5Q2, 5Q3, 5Q4, 5Q5, 5Q6, 5Q7, and 5Q8, as well as 5Q05-5Q16).

[0063] In some embodiments, the highlight microdot mask element may include one internal opaque island within a continuous annular boundary region (e.g., patterns 4A-5A, 5C-5D, 5F, and 5G).

[0064] In some embodiments, the highlight microdot mask element may include one internal opaque island within a discontinuous annular boundary region (e.g., patterns 5Q1, 5Q2, 5Q3, and 5Q4).

[0065] In some embodiments, the highlight microdot mask element may include multiple internal opaque islands within a continuous annular boundary region (e.g., patterns 5B, 5E, and 5H).

[0066] In some embodiments, the highlight microdot mask element may include multiple internal opaque islands within a discontinuous annular boundary region (e.g., patterns 5Q05, 5Q06, 5Q08, 5Q11, 5Q12, 5Q13, 5Q14, 5Q15, and 5Q16).

[0067] In some embodiments, the highlight microdot mask element may include one internal drawing region within a contiguous annular boundary region (e.g., patterns 5B, 5E, and 5I).

[0068] In some embodiments, the highlight microdot mask element may include one internal drawing region within a discontinuous annular boundary region (e.g., pattern 5Q3).

[0069] In some embodiments, a highlight microdot mask element can include multiple internal drawing regions within a contiguous annular boundary region (e.g., pattern 5H).

[0070] In some embodiments, the highlight microdot mask element may include multiple internal drawing regions within a discontinuous annular boundary region (e.g., patterns 5Q08-5Q16).

[0071] Pattern 5Q1 shows a main continuous ring 520 having an outer drawing region 512a as an outlier island. Pattern 5Q1 has a semi-continuous main ring 522 and a discontinuous outer ring 524. Pattern 5Q3 includes a main continuous ring 520 having an outer drawing region 512a as an outlier island and an inner drawing block 519 as an inner drawing island. Pattern 5Q4 shows a semi-continuous main ring 522 and a discontinuous outer ring 524. Pattern 5Q05 shows a central opaque island 528 within a central semi-continuous drawing ring 530 and an outer discontinuous opaque ring 532 within an outer discontinuous drawing ring 534. Pattern 5Q06 then modifies the arrangement of the print blocks 506 and blank blocks 508 to form blank islands within various boundary print blocks 506. Together, the blank blocks 508 become areas that hold ink on the printing plate, and the print blocks 506 are the printing surfaces. The combination of retaining walls on the printing surface and ink storage areas in the blank block 508 enables ink retention and printing in a manner that reduces the formation of halo effects or donut dots. The microdot printhead pattern includes one or more ink storage areas (e.g., blank areas) within one or more structural printing surfaces (printing areas) that provide walls to the ink storage areas.

[0072] For example, pattern 5Q2 shows a mixture of half-pixels and quarter-pixels, which gives the printhead more structure and print surface area. This configuration does not increase depth, which is advantageous for smaller ink storage capacity.

[0073] For example, pattern 5Q1 has a height of 30 micrometers and a width of 10 micrometers.

[0074] For example, pattern 5Q05 contains 16 printed blocks, which is 16 quarter pixels. The number 4 represents the total pixel count, which is how much light can pass through the mask. Therefore, pattern 5Q05 is the number of printed blocks relative to the total number of pixels (e.g., number of printed blocks divided by 4).

[0075] In some embodiments, the highlight microdot mask element may include at least 20 total blocks, at least 24 blocks, at least 28 blocks, at least 30 blocks, at least 35 blocks, at least 40 blocks, at least 50 blocks, at least 55 blocks, at least 60 blocks, at least 65 blocks, or 70 blocks or more.

[0076] In some embodiments, the highlight microdot mask element may include at least 16 drawn blocks, at least 20 drawn blocks, at least 24 drawn blocks, or at least 26 drawn blocks within the pattern.

[0077] [Table 1]

[0078] In some embodiments, the print head pattern includes at least 29 print blocks that form at least one internal blank area within the ring area.

[0079] In some embodiments, the highlight microdot mask element may include at least four non-drawn blocks (blank blocks) that constitute at least one internal opaque island.

[0080] In some embodiments, the highlight microdot mask element may include at least 20% of the total blocks that are non-drawn blocks (blank blocks).

[0081] In some embodiments, the highlight microdot mask element may include multiple outer boundary regions of the printed block, which together form a light-transmitting ring. There may be at least one internal opaque island formed by multiple non-printed blocks within the light-transmitting ring. The internal opaque island may have an island width of at least 1 / 2 pixel and an island height of at least 2 pixels. There may also be an opaque void region surrounding the light-transmitting ring, which is located 4 pixels from an adjacent highlight microdot structure, or 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 75, or 100 or more pixels from an adjacent microdot structure.

[0082] In some embodiments, the mask element may include a highlight microdot mask element from one embodiment and an image pattern having a highlight mask region formed by the highlight microdot mask element. In some embodiments, the mask may include a highlight microdot region of a drawing material having a thermally ablable drawing layer having drawing blocks and non-drawing blocks arranged to form a highlight microdot pattern on a single highlight microdot structure. In some embodiments, the mask may include a light-transmitting ring formed by a plurality of drawing blocks, the ring thickness being at least 1 / 4 pixel and the orthogonal thickness being at least 1 pixel. The ring height may range from 3 to 8 pixels, and the ring width may range from 1 to 8 pixels. The highlight microdot pattern may include at least one internal opaque island formed by a plurality of non-drawing blocks within the light-transmitting ring. The internal opaque island may have an island height of at least 1 pixel and an island width of at least 1 pixel. The opaque void region surrounds the light-transmitting ring.

[0083] In some embodiments, the mask may include a drawing material having a thermally ablable drawing layer having drawing blocks and non-drawing blocks arranged to form an image pattern. The image pattern includes at least one highlight mask region, which has a plurality of highlight microdot structures that form a highlight pattern of the image pattern. The highlight mask region includes a plurality of opaque regions in the thermally ablable drawing layer. Each opaque region is one or more non-drawing blocks. The highlight mask region includes a plurality of light-transmitting regions in the thermally ablable drawing layer. Each light-transmitting region may be one or more drawing blocks, and each highlight dot region includes at least one highlight microdot mask element.

[0084] In some embodiments, the mask may include a light-transmitting ring formed by a plurality of drawing blocks, the ring thickness being at least 1 / 4 pixel, the ring height in the range of 4 to 8 pixels, and the ring width in the range of 2 to 8 pixels. An internal opaque island is formed by a plurality of non-drawing blocks within the light-transmitting ring. The internal opaque island may have an island width of at least 1 pixel and an island height of at least 2 pixels. There is an opaque void region surrounding the light-transmitting ring, formed by a plurality of non-drawing blocks.

[0085] In several embodiments, a method for forming a mask for a highlight-generating flexographic printing plate can be provided. The mask can be formed from a drawable material having a thermally ablable drawing layer. An image pattern having at least one highlight region is provided. The highlight region comprises a plurality of highlight microdot mask elements. Each highlight microdot mask element comprises a microdot pattern formed by the arrangement of a plurality of drawing regions and at least one opaque island. An image is then drawn on the drawable material and a laser is used to form a mask image within the thermally ablable drawing layer. In some embodiments, the mask image comprises an image pattern having at least one highlight region. In some embodiments, the highlight region comprises a plurality of highlight microdot mask elements. In some embodiments, each highlight microdot mask element comprises a microdot pattern formed by a plurality of drawing blocks within the thermally ablable drawing layer and at least one opaque island in the thermally ablable drawing layer. The drawing blocks and non-drawing blocks are arranged to jointly form a microdot pattern in the mask image, with opaque void regions formed by the plurality of non-drawing blocks surrounding the microdot pattern.

[0086] The mask is then used to create a flexographic printing plate having a relief image formed from raised areas higher than the floor, some of which are obtained from a highlight microdot structure having a highlight print head pattern.

[0087] Printed version The printing plate may include a highlight microdot structure configured to print the highlight areas of an image. The highlight dot structure may include a printhead with a printing surface larger than the minimum microdot used in flexographic printing (e.g., alignment microdots or U.S. Patent No. 8,896,894). However, the scale of each highlight dot structure is on the micrometer scale (e.g., 30–70, or 40–60, or about 50–55 micrometers), and thus it is a highlight microdot structure. However, the highlight microdot structure includes a printing surface pattern, which has printing surfaces and depressions, thereby allowing for highlight dots to be printed with ink to be larger than the minimum flexographic microdots. However, the printing surface pattern of the highlight microdot structure creates a visual illusion to the human eye, thereby allowing the visibility of the highlights to virtually fade out to zero visibility as desired. This enables a gradient of visibility in the resulting highlight image (see, for example, Figure 3).

[0088] Each highlight microdot structure may include a pattern of printed surfaces with recesses between them, arranged to form a highlight microdot printed surface pattern. The highlight microdot printed surface pattern may include blocks, which are protruding blocks with printed surfaces or recessed blocks capable of holding ink. The highlight microdot pattern includes recesses that hold ink and printed surfaces on which the ink is printed. However, this configuration enables printing that appears as highlight printing to the human eye, which was not possible with flexographic printing in the past. Printed highlight dots can have lower contrast by spreading the ink more thinly over an area larger than the smallest available microdot, thereby making them less visible to the human eye than smaller, normal high-contrast flexographic printing dots.

[0089] Figures 6A–6F show three embodiments of a highlight microdot structure array in the highlight region of a printing plate. These highlight microdot structures have cross-sectional dimensions (e.g., width, length, or diameter) of less than approximately 50 micrometers, as indicated by the size bar. The highlight microdot structures are shown without any features such as raised or recessed areas. Therefore, the highlight microdot structures do not include boundaries formed by raised areas, and recessed areas within the boundaries are formed by recessed areas without raised boundaries. Figure 6A is an SEM image of a microdot print head array showing printing surface pattern 4A (Figure 5A) with a 250 micrometer scale bar (magnification 250×). Figure 6B is an SEM image of the highlight microdot print head array of Figure 6A, with a scale bar of 100 micrometers (magnification 500×). Figure 6C is an SEM image of a microdot print head array showing printing surface pattern 5Q05 (Figure 5C) with a 250 micrometer scale bar (magnification 250×). Figure 6D is an SEM image of the highlighted microdot print head array in Figure 6C, with a scale bar of 100 micrometers (magnification 500×). Figure 6E is an SEM image of the microdot print head array showing the print surface pattern 5Q07 (Figure 5C) with a scale bar of 250 micrometers (magnification 250×). Figure 6F is an SEM image of the highlighted microdot print head array in Figure 6D, with a scale bar of 100 micrometers (magnification 500×).

[0090] Figures 6A-6F show a flexographic printing plate highlight microdot printhead that includes multiple raised regions forming a boundary structure, along with internal depressions surrounded by voids. The multiple raised regions are arranged in the highlight microdot print surface pattern. Each raised region has at least one raised block that forms the print surface. The microdot print surface pattern may include at least one internal depression formed by at least one depression block within the highlight microdot print surface pattern. The arrangement of the multiple raised regions and depressions defines the highlight microdot print surface of the highlight microdots. Each highlight microdot may have a print surface pattern with a print surface boundary and internal depressions. Each highlight microdot may be surrounded by depressions or depressions with depths that are significantly deeper or larger in dimension than the depression void regions on the highlight microdot printhead. Deep void regions surround each highlight microdot in the highlight microdot pattern formed by multiple depression blocks. The number of adjacent depression blocks is very large, forming deep depression void regions between each highlight microdot structure. Each recessed block has a recessed surface that is lower than each printed surface. The recesses around the highlight microdot structure are significantly deeper than the void recesses on the highlight microdot printhead.

[0091] A highlight microdot printhead can correspond to a mask used to form the printing plate. The mask is designed as a grid of blocks, thereby the highlight microdot printhead also includes a grid of blocks, some of which are protrusions (e.g., hardened) and some are recesses that form internal recesses within the boundaries of the protrusions (e.g., not hardened and removed). Thus, the raised blocks form boundaries that hold the recesses of the recessed blocks. As shown in Figures 6A-6F and 5A-5D, the blocks are arranged in a grid pattern, with the sides of each block within the grid. The blocks have height in one direction and width in the perpendicular direction. The blocks may be raised blocks with a printing surface, or they may be recessed blocks without a printing surface. The blocks may be rectangular or square if the sides are equal. Some of the blocks may be in the form of recesses, but the printing blocks have a printing surface that is higher than the recesses.

[0092] Figure 7A shows one embodiment of a flexographic printing plate 700, where the highlight image region 702 may include at least one highlight microdot structure 704 having a highlight microdot printhead 706 having a print surface pattern 708. The highlight microdot printhead 706 is a raised region 710 compared to a void region 712, which is a recessed area around the highlight microdot structure. The highlight microdot printhead 706 is patterned to have a raised region 714 and a recessed region 716, which form the same highlight microdot pattern as the print surface pattern 708. The raised region 714 forms a barrier around the recessed region 716 within the highlight microdot printhead 706. The outer raised region 714a is 2 blocks wide (e.g., 1 / 2 pixel). The shallow recessed area 718 inside the outer raised region 714a is 1 block wide (e.g., 1 / 4 pixel). The internal raised region 714b is 1 block wide (e.g., 1 / 4 pixel). The deep central recess 720 is 2 blocks wide (e.g., 1 / 2 pixel), and is thereby deeper than the shallow recess 718. Different patterns can have different shallow and deeper recesses depending on the recessed blocks and printed blocks. It should be understood that wider recesses can also be deeper. Thus, the highlight microdot printhead 706 may include a series of raised regions 714 (e.g., islands or barriers) and lower recessed areas 716, as shown in Figure 7B, which hold (e.g., pool) the ink 720 within the highlight microdot pattern 708. This combination of higher islands and lower recesses within the highlight microdot pattern controls ink transfer in a unique way to facilitate the realization of the visual image of the highlight regions.

[0093] A highlight microdot printhead may include an area that can range from square to rectangular or from circular to elliptical. The dimensions of the highlight microdot printhead may be at least 30 micrometers in its longest dimension, such as diameter or height, and more preferably more than 30 micrometers in its shortest dimension. The dimensions of the highlight microdot printhead may be at least 35 micrometers in its longest dimension, such as diameter or height, and more preferably more than 35 micrometers in its shortest dimension. A flexographic printing plate may have a highlight microdot printhead with a longest dimension (e.g., height or width) of less than 100 micrometers, less than 90 micrometers, less than 80 micrometers, less than 70 micrometers, less than 60 micrometers, less than 50 micrometers, or less than 40 micrometers, and greater than 35 micrometers, and with a shortest dimension greater than 35 micrometers. These sizes may range between any smaller value and any larger value as the endpoints of the range. In a particular example, a flexographic printing plate may have a highlight microdot printhead with a longest dimension of less than 70 micrometers. For example, the density of a highlight microdot structure can be measured using a standard density measurement method relating to the volume of ink being transferred. While the density can be numerically comparable to that of a standard flexographic microdot or dot, the post-printing effect of the highlight microdot is visually less distinct and less visible to the human eye at a normal viewing distance.

[0094] In some embodiments, blocks can have a height of 1 pixel and a width of 1 / 4 pixel (e.g., in the orthogonal direction). Some blocks can have a height of 1 pixel and a width of 1 / 2 pixel, 3 / 4 pixel, 1 pixel, or larger. Raised blocks can be made of a curable material formed by a SQUAREspot laser, which can be used to extend the microdot printhead over a wider area. Raised blocks form islands, and recessed blocks form depressions or voids. Combinations of raised and recessed blocks define the highlight microdot pattern. In some embodiments, raised blocks form wall structures or barrier structures, and recessed blocks form voids between them. The configuration of raised and recessed blocks within the highlight microdot pattern makes it possible to correctly form the highlight microdot structure on the plate through the transmission of UV light through a mask that defines the image. This configuration allows the ink to spread further outward around the dots in the printed highlight microdots, resulting in a thinner ink film, which in turn makes the printed highlight microdots less visible to the human eye at normal viewing distances.

[0095] The highlight printing area of ​​a flexographic printing plate can have a large number of individual highlight microdot structures. For example, highlight areas such as the center of an image or near the edges of an image can contain thousands of individual highlight microdot structures. The highlights may be one-color or multi-colored. The highlight microdot structure of this application can replace the smallest dots used in the past. Here, the highlights can be manufactured to have structured low-contrast highlights at the outer edge of the image in the lowest percentage of the tonal range. Thus, the highlight microdots can provide structured low-contrast highlights that can replace the very conspicuous conventional highlight dots as part of normal tone or process printing. The highlight microdot printhead is configured to spread the same or lesser amount of ink over a wider area, resulting in lower contrast and making it less visible at normal viewing distances. Therefore, the low-contrast highlights are less visible and less indistinct to the end consumer in a store under normal viewing conditions, compared to conventional highlight dots in flexographically printed images, and are much closer to the appearance of gravure-printed highlights. The highlight microdot structure shown here, along with the printed surface pattern, allows for the printing of highlight microdots without the appearance of donuts or rings. The printed highlight microdots appear as fading dots, which may have a visibility gradient where visibility decreases from the center outwards.

[0096] Masks and original mask plates A mask for use with a relief-forming plate having a photosensitive layer (e.g., a flexographic printing plate) can be fabricated from a mask master. The mask can be fabricated to have a negative image of the relief image of the flexographic printing plate and may include highlight regions having a highlight microdot structure, each of which has a patterned highlight microdot printhead. Thus, the digital image of the mask is created to include flexographic printing image features, including the highlight regions. The mask master can be fabricated to form a mask having highlight regions with a highlight microdot printhead pattern and can be processed with light (e.g., infrared, IR). The mask can then be combined with the relief-forming plate (e.g., by lamination) and processed, and the light-processed mask and relief-forming plate can be separated from each other to obtain a relief-containing flexographic printing plate having a highlight microdot structure with a microdot printhead pattern. During the separation process, it is important that the drawing relief-forming layer, which has the relief formed therein along with the highlight microdot printheads, is not damaged.

[0097] A mask master can be considered a writable material having a writable layer that forms a mask with highlight regions. The mask master can include three basic layers or films, as described below, in the order of (a) a transparent polymer carrier sheet, (b) a photothermal conversion (LTHC) layer, and (c) a non-halogenated silver thermal ablation writable layer (IL). Here, the LTHC layer cannot be ablated by thermal writing with light such as IR light. The non-halogenated silver thermal ablation writable layer can be ablated by thermal writing with light such as IR light, but this thermal ablation writable layer does not contain silver halides, and is therefore a thermal ablation-capable "non-halogenated silver" writable layer. Thus, the LTHC layer contains a substance that is not ablated by thermal energy during the writing of the IL layer with IR light. On the other hand, the IL layer contains a thermal ablation-capable substance. Only these three layers or films are essential to form a mask element (for example, called a mask) having a mask image within the IL layer. However, as will be discussed later, in some embodiments, (d) a transparent polymer overcoat layer can be directly placed on the IL, but this optional feature is not necessary for mask formation or the use of a mask image. Rather, it may be beneficial in some applications to provide ablation resistance.

[0098] A mask master used to form the mask elements that will ultimately be used to form the relief image of the flexographic printing plate can be prepared as described herein and then processed into a mask. In some embodiments, a mask master 810 is shown in Figure 8A, which has (a) a transparent polymer carrier sheet 815, (b) an LTHC layer 820 containing an ablation-free binder material having ablation-free particles 825 which will be described in more detail later, and (c) an ablation-free IL 830 positioned on top of the LTHC layer 820 to receive light 835 (IR light) indicated by an arrow.

[0099] Transparent polymer carrier sheet A transparent polymer carrier sheet can be any suitable transparent substrate or film. Beneficial transparent polymer carrier sheets may be, but are not limited to, transparent polymer films and sheets composed of one or more polymers, such as polyesters including poly(ethylene terephthalate), polymer(ethylene naphthalate), and fluorinated polyester polymers, polyethylene-polypropylene copolymers, polybutadiene, polycarbonate, polyacrylate (a polymer formed in part from one or more (meth)acrylate ethylenically unsaturated monomers), polyvinyl chloride and vinyl chloride polymers such as copolymers derived in part from vinyl chloride, hydrolyzed or non-hydrolyzed cellulose acetate, and other materials readily apparent to those skilled in the art. A transparent polymer carrier sheet may be composed of two or more polymer materials as a blend or composite, provided that the required transparency and protective properties are achieved. These can be formed as a single polymer film or a laminate of multiple polymer films. Generally, transparent polymer carrier sheets have an average dry thickness of at least 25 μm and up to 250 μm, or typically at least 75 μm and up to 175 μm.

[0100] For example, transparent polymer (ethylene terephthalate) sheets, which are available from various suppliers, are suitable as transparent polymer carrier sheets.

[0101] If necessary, the surface of the transparent polymer carrier sheet can be treated to alter its wettability and adhesion to the applied coating (e.g., LTHC layer coating). Such surface treatments include, but are not limited to, corona discharge treatment and the application of an undercoat, as long as the desired transparency (as described above) is achieved.

[0102] Optionally, the transparent polymer carrier sheet may also contain one or more "primary" ultraviolet radiation absorbing compounds (LTHC layer or IL, as described below). These one or more compounds may be the same as or different from the ultraviolet radiation absorbing compounds of the IL (see below). Each useful ultraviolet radiation absorbing compound generally absorbs electromagnetic radiation from at least 150 nm to a maximum of 450 nm. These compounds may be present in the transparent polymer carrier sheet in amounts ranging from at least 0.01% by weight to a maximum of 0.1% by weight, based on the total dry weight of the transparent polymer carrier sheet.

[0103] In addition, the transparent polymer carrier sheet may contain one or more "adhesion promoters," which improve adhesion between it and the adjacent LTHC layer. Useful adhesion promoters include, but are not limited to, gelatin, poly(vinylidene chloride), poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid), and polyethyleneimine.

[0104] Ablation-free photothermal (LTHC) layer The mask master also includes an ablation-free LTHC layer placed directly between the transparent polymer carrier sheet and the IL on the transparent polymer carrier sheet. A suitable LTHC layer composition has three basic components: (i) a first infrared radiation absorbing material, (ii) an ablation-free crosslinking binder material which is a thermally crosslinked organic polymer that cannot be ablated by light radiation such as IR radiation, and (iii) ablation-free particles that cannot be ablated by light radiation such as IR radiation, visible radiation, or UV radiation. The LTHC layer is generally installed as a relatively uniform coating on the transparent polymer carrier sheet (i.e., having a substantially continuous and nearly uniform wetting thickness), and then dried if any solvent remains in the composition formulation.

[0105] The LTHC layer is generally transparent, as defined above. In particular, the LTHC layer is transparent to UV radiation used to draw on the relief-forming plate, as will be defined later.

[0106] One or more infrared absorbing materials, collectively referred to herein as the “first” infrared absorbing material, if necessary, to distinguish them from a second infrared absorbing material in the IL (described later). The first infrared absorbing material may also be a transparent polymer carrier sheet. The first and second infrared absorbing materials may be one or more dyes or pigments, or mixtures thereof, that provide desired spectral absorption properties and are independently sensitive to electromagnetic radiation in the infrared electromagnetic wavelength range of at least 700 nm to 1,500 nm, typically at least 750 nm to 1,200 nm. Such materials are essentially fine particles and are dispersed in the (ii) ablation-free crosslinking binder material described later. For example, these may be black dyes or pigments, such as carbon black, metal oxides, and other materials described, for example, in U.S. Patent Application Publication No. 2005 / 0227182 ('182).

[0107] One suitable IR-absorbing pigment is carbon black, which is commercially available in many varieties with various particle sizes. Examples include RAVEN 450, 760 ULTRA, 890, 1020, 1250, and others from Colombian Chemicals (Atlanta, Georgia), as well as BLACK PEARLS 170, BLACK PEARLS 480, VULCAN XC72, BLACK PEARLS 1100, and others from Cabot Corporation. Other useful carbon blacks are surface-functionalized with soluble groups. Carbon blacks grafted onto hydrophilic nonionic polymers, such as FX-GE-003 (manufactured by Nippon Shokubai Co., Ltd.), or surface-functionalized with anionic groups, such as CAB-O-JET® 200 or CAB-O-JET® 300 (manufactured by Cabot Corporation), are also useful.

[0108] Useful primary infrared radiation absorbing materials also include IR dyes, which include, but are not limited to, cationic infrared absorbing dyes and photothermal bleaching dyes. Examples of suitable IR dyes include, but are not limited to, azo dyes, squiraryllium dyes, croconium dyes, triallylamine dyes, thiazulium dyes, indolium dyes, oxonol dyes, oxazolium dyes, cyanine dyes, merocyanine dyes, phthanocyanine dyes, indocyanine dyes, indotricarbocyanine dyes, oxatricarbocyanine dyes, thiocyanine dyes, thiatricarbocyanine dyes, merocyanine dyes, cryptocyanine dyes, naphthalocyanine dyes, polyaniline dyes, polypyrrole dyes, polythiophene dyes, chalcogenobilloalilidene and bi(chalcogenopyrilo)polymethine dyes, oxyindolidine dyes, pyririum dyes, pyrazolin azo dyes, oxazine dyes, naphthoquinone dyes, anthraquinone dyes, quinoneinemine dyes, methine dyes, allylmethine dyes, squaline dyes, oxazole dyes, croconine dyes, porphyrin dyes, and any substitutional or ionic forms of these dye classifications. Suitable dyes are also described in U.S. Patent No. 5,208,135 (Patel et al.), U.S. Patent No. 6,569,603 (Furukawa), and U.S. Patent No. 6,787,281 (Tao et al.), as well as in European Patent Application Publication No. 1,182,033 (Fijimaki et al.). A general description of one classification of suitable cyanide dyes is given by the formula in paragraph

[0026] of International Publication Brochure No. 2004 / 101280.

[0109] Near-infrared absorbing cyanide dyes are also useful, as described, for example, in U.S. Patent No. 6,309,782 (Hauck et al.), U.S. Patent No. 6,264,920 (Achilefu et al.), U.S. Patent No. 6,153,356 (Urano et al.), and U.S. Patent No. 5,496,903 (Watanabe et al.), all of which are incorporated herein by reference. Suitable dyes may be prepared using conventional methods and starting materials, or may be obtained from various suppliers, including American Dye Source (Baie D'Urfe, Quebec, Canada) and FEW Chemicals (Germany).

[0110] The first infrared radiation absorbing material is generally present in an amount sufficient to provide a transmitted optical density of at least 0.025 and typically at least 0.05 at the exposure electromagnetic radiation wavelength (e.g., IR). Generally, this is achieved by including at least 0.1% to a maximum of 5% by weight, or typically at least 0.3% to a maximum of 3% by weight, based on the total dry weight of the LTHC layer.

[0111] The first infrared absorbing material in the LTHC layer can be the same or a different chemical substance as the second infrared absorbing compound incorporated into the IL as described later. The infrared absorbing material in the LTHC layer may be different from the infrared absorbing material in the transparent polymer carrier. In most embodiments, the first and second infrared absorbing materials are the same chemical substance. The amounts of the first and second infrared absorbing materials in the drawable material may be the same or different. In most embodiments, they are present in different amounts in the drawable material.

[0112] As described above, the LTHC layer includes an ablation-non-crosslinking binder formed from one or more thermally crosslinkable organic polymer binders derived from a crosslinked thermally crosslinkable organic polymer binder. The term "thermally crosslinkable" means the presence of crosslinkable groups, including, for example, hydroxyl-containing polymers. Particularly useful thermally crosslinkable organic polymers include, but are not limited to, crosslinkable nitrocellulose, crosslinkable polyesters such as hydroxyl-containing polyesters, polyvinyl alcohols, polyvinyl acetals such as polyvinyl butyral, or combinations of two or more of these crosslinkable organic polymer materials. The corresponding ablation-non-crosslinking binder material can be obtained by crosslinking the listed thermally crosslinkable organic polymer materials.

[0113] The ablation-free crosslinking binder material, formed from a thermally crosslinked organic polymer, may be present in the LTHC layer in amounts ranging from at least 40% to a maximum of 90% by weight, and more likely, at least 50% to a maximum of 80% by weight, all based on the total dry weight of the LTHC layer.

[0114] The third essential component of the LTHC layer is ablation-non-ablation particles that cannot be ablated by light radiation or the heat resulting from light radiation; thus, ablation-non-ablation particles are considered thermally ablation-non-ablation particles. Thermally ablation-non-ablation particles are defined as those that cannot be thermally ablated by exposure to light radiation during mask formation or relief image formation. The average particle size of ablation-non-ablation particles can be at least 0.1 μm and up to 20 μm or at least 5 μm and up to 15 μm. The term "average" can be used here to refer to measured particle size of dispersed particles, which can be identified from the manufacturer's specifications or by measuring at least 10 different particles and taking the average.

[0115] The term "ablation-free" in relation to ablation-free particles is used here to mean that the particles are not sensitive to the laser drawing wavelength and intensity, compared to materials that are strongly affected by the laser drawing ablation process for mask formation. Furthermore, the particles are not sensitive to UV radiation during the formation of the relief image from the mask and relief-forming master plate. Materials sensitive to the laser thermal drawing ablation process are ablable because they strongly absorb the laser wavelength of the drawing laser and have low thermal decomposition temperatures; therefore, such materials are not used for ablation-free particles. Conversely, the ablation-free particles used in this invention do not strongly absorb the laser drawing wavelength and do not have a relatively low thermal decomposition temperature. Some of the thermally ablation-free particles may protrude from the LTHC layer, for example, into the IL, but are retained within the LTHC layer or at least partially embedded therein.

[0116] Useful ablation-free particles in the LTHC layer include, but are not limited to, silica, titanium dioxide, zinc oxide particles, or combinations of two or more of these particles. Silica particles are particularly useful in the particles of the present invention. Furthermore, such ablation-free particles may be present in the LTHC layer in amounts ranging from at least 0.2% by weight to a maximum of 10% by weight, or from at least 1% by weight to a maximum of 7% by weight, all based on the total dry weight of the LTHC layer.

[0117] Optionally, during formation, the LTHC layer may contain one or more thermal crosslinking agents to improve the handling of the mask element. Such optional thermal crosslinking agents promote crosslinking of the thermally crosslinkable organic binder polymer while coating and drying the LTHC layer to form an ablation-free crosslinking binder. Heat can be used for drying during the formation of the mask element. The thermal crosslinking agent can be present in an amount of at least 5% to a maximum of 25% by weight based on the total dry weight of the crosslinkable polymer crosslinked to the ablation-free LTHC layer. Such materials include, but are not limited to, melamine formaldehyde resins, dialdehydes, phenols, polyfunctional aziridines, isocyanates including polyisocyanates, and urea formaldehyde epoxies. However, since the formed LTHC layer is a crosslinking binder, the crosslinking agent may be entirely used, or not present in the formed ablation-free crosslinking material, or present only in small amounts.

[0118] The LTHC layer generally has an average dry thickness of at least 1 μm to a maximum of 5 μm, or typically at least 1 μm to a maximum of 3 μm.

[0119] Non-halogenated silver thermal ablation-compatible lithography layer (IL) The IL incorporated into the mask master is generally installed directly on the LTHC as a relatively uniform coating (i.e., substantially continuous and having a nearly uniform wettness), and then dried, if a solvent is present in the formulation. In most embodiments, the IL is a single coating or deposition layer, but in other embodiments, there may be multiple sublayers or subcoatings constituting the IL installed directly on the aforementioned LTHC layer.

[0120] As mentioned in the section on terminology, silver halides are not inherently present in IL. In other words, silver halides are intentionally added to or created in IL.

[0121] IL generally contains one or more ultraviolet (UV) absorbing materials as essential components. These compounds generally have an absorbance of at least 1.5 to a maximum of 5 in the electromagnetic radiation wavelength range from at least 300 nm to a maximum of 450 nm. Generally, useful UV absorbing materials include, but are not limited to, benzotriazoles, halogenated benzotriazoles, triazines, benzophenones, benzoates, salicylic acid, substituted acrylonitriles, cyanoacrylates, benzylidene malonate, oxalanilides, and mixtures thereof. Examples of useful UV absorbing materials include, but are not limited to, UV absorbing dyes or UV stabilizers commercially available under trade names such as Uvinul® (BASF), Keyplast® (Keystone Aniline Corporation), Sanduvor® (Sandoz Chemicals Corp.), Hostavin (Clariant), and Tinuvin® (BASF or Ciba). Examples of useful materials are described in U.S. Patent No. 5,496,685 (Farber et al.).

[0122] One or more ultraviolet radiation absorbing compounds may be present in the IL in amounts ranging from at least 10% to a maximum of 40% by weight, or typically from at least 15% to a maximum of 30% by weight, based on the total dry weight of the IL.

[0123] The IL also includes one or more second infrared radiation absorbing materials as a second essential component, which are defined similarly to the first infrared radiation absorbing materials described above with respect to the LTHC layer, and which may be the same as or different from the first infrared radiation absorbing materials. One or more second infrared radiation absorbing materials may be present in the IL in an amount sufficient to provide a transmitted optical density of at least 0.5, typically at least 0.75, at the exposure wavelength. Generally, this is achieved by including one or more second infrared radiation-sensitive compounds in an amount ranging from at least 3% to a maximum of 20% by weight, based on the total dry weight of the IL.

[0124] The IL may optionally contain one or more fluorocarbon additives to improve the generation of halftone dots (i.e., pixels) that are clearly defined, generally continuous, and have relatively sharp edges. Examples and amounts of useful fluorocarbon additives are described in paragraphs

[0087] to

[0089] of U.S. Patent No. 182 (mentioned above).

[0125] Additional optional components of IL include, but are not limited to, plasticizers, coating aids or surfactants, dispersing aids, fillers, and dyes, all of which are well known in the industry, as described, for example, in paragraphs

[0094] to

[0096] of U.S. Patent No. 182 (mentioned above). For example, IL may further include one or more fluorocarbon additives or one or more heat-absorbable dyes.

[0126] All of the essential and optional components mentioned above with respect to the IL are dispersed in one or more ablable polymer binder materials, which include both synthetic and naturally occurring polymer materials that can be ablated when exposed to light radiation such as IR radiation, visible radiation, or UV radiation. In some embodiments, the ablable polymer binder in the IL is not crosslinked and is therefore a non-crosslinked binder. Such materials can uniformly dissolve or disperse the essential and optional components throughout the IL. One or more ablable polymer binder materials may be present in amounts ranging from at least 25% to a maximum of 75% by weight, or typically from at least 35% to a maximum of 65% by weight, based on the total dry weight of the IL.

[0127] Useful ablable polymer binder materials include, but are not limited to, the materials described in paragraphs

[0081] to

[0085] of U.S. Patent No. 182. These materials are also known as “adhesive binders,” as described in paragraph

[0081] of U.S. Patent No. 182. Examples of these materials include, but are not limited to, acetyl polymers such as poly(vinyl butyral) available from Solution, Inc. (St. Louis, Missouri) as BUTVAR® B-76, and acrylamide polymers available from Henkel Corp. (Gulf Mills, Pennsylvania) as MACROMELT 6900. Pressure-sensitive adhesive polymers can also be used for this purpose.

[0128] In some embodiments, it is advantageous to use a binder material in the IL that is readily combustible by heat or thermally ablable and generates gases and volatile fragments at temperatures below 200°C. Examples of such materials include thermally ablable nitrocellulose, polycarbonates, poly(cyanoacrylate), polyurethanes, polyesters, polyorthoesters, polyacetals, and their copolymers, which may be non-crosslinked (see, for example, U.S. Patent No. 5,171,650, column 9, lines 41-50, the disclosure of which is incorporated herein by reference).

[0129] Other useful ablable materials for IL include poly(vinyl alcohol) and cellulosic polymers (such as nitrocellulose) having hydroxyl groups (or hydroxyl polymers) as described in sections

[0082] to

[0084] of U.S. Patent No. 182 (mentioned above). Other useful polymers include non-crosslinkable polyesters, polyamides, polycarbamates, polyolefins, polystyrene, polyesters, polyvinyl ethers, polyvinyl esters, and polyacrylates and polymethcretes having one and two carbon atoms and alkyl groups.

[0130] Particularly useful ablable materials for IL include, but are not limited to, polyurethane, poly(vinyl butyral), (meth)crilamide polymers, nitrocellulose, polyacetal, poly(cyanoacrylate), polymers derived at least in part from metal methacrylate, ethyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate, or combinations of two or more of these materials.

[0131] The average dry thickness of the IL can range from at least 0.5 μm to a maximum of 5 μm, or typically from at least 0.8 μm to a maximum of 2.5 μm.

[0132] Transparent polymer overcoat layer In some embodiments, the mask master plate optionally includes a transparent polymer overcoat layer that is directly installed on the IL, opposite the LTHC layer. Such a transparent polymer overcoat layer is not essential to the interests of the present invention. The transparent polymer overcoat layer generally comprises one or more transparent film-forming polymers or resins, which include, but are not limited to, methacrylate copolymers (a copolymer of ethyl methacrylate and methacrylic acid) and one or more fluoropolymers dispersed therein, as described, for example, in U.S. Patent No. 6,259,465 (Tutt et al.), whose disclosure is incorporated herein by reference. The transparent polymer overcoat layer can provide abrasion resistance during handling due to the presence of fluoropolymer particles. It can also function as a barrier to prevent the transfer of chemicals from the mask elements to the relief-forming master plate when they are in full optical contact.

[0133] A transparent polymer overcoat layer, if present, can be directly attached to the IL, and its average dry thickness can range from at least 0.05 μm to a maximum of 1 μm.

[0134] Formation of mask elements In some embodiments, the mask can be formed by generating exposed and unexposed regions in the IL of the mask master described herein. The selection of the drawing mechanism determines the variations that can be realized in mask image formation, which will be described later.

[0135] Ablation of the IL layer by exposing the mask master to light energy that produces an ablation effect can be performed in selected areas, such as the printing blocks of the grid of a highlight microdot print head, and is known as "image exposure." In some embodiments, image exposure can be achieved using thermal radiation from a computer-controlled scanning or rasterizing thermal or infrared laser. Any known scanning equipment can be used, including flatbed scanners, external drum scanners, and internal drum scanners. In these devices, the mask master material is fixed to a drum or bed, and a laser beam can be focused to a spot and impacted onto the IL of the mask master material. Two or more lasers can scan different areas of the IL simultaneously.

[0136] For example, the mask master material can be exposed to infrared radiation in an electromagnetic wavelength range of, for example, at least 700 to a maximum of 1500 nm. Such a mask master material includes, as described above, one or more second infrared radiation absorbing materials in the IL to provide sensitivity to infrared radiation. In these embodiments, the mask master material can be appropriately mounted on an infrared imager and exposed to infrared radiation using an infrared laser such as a computer-controlled scannable diode laser or Nd:YAG laser. Suitable infrared imagers include, but are not limited to, the TRENDSETTER imagesetter and ThermoFlex Flexographic CTP imager available from Eastman Kodak Company for use in CTP lithography printing plate applications and imaging flexographic elements; the DIMENSION imagesetter available from Presstek (Hudson, New Hampshire) useful for CTP lithography printing plate applications; the CYREL® Digital Imager (CDI SPARK) available from Esko-Graphics (Kennethaw, Georgia); and the OMNISETTER imager available from Misomex International (Hudson, New Hampshire) useful for imaging flexographic elements.

[0137] This exposure step is shown in Figure 8A for several embodiments, in which the mask master material 810 is exposed to exposure infrared radiation 835 with an image pattern of a block which is either a printed block or a blank block, as exemplified by the mask element 836 shown in Figure 8B, to provide exposed areas 840 and unexposed areas 842 corresponding to the mask image. As shown in the figure, the exposed areas 840 are ablated (printed block) and removed from the unexposed areas 842 (blank block). Thus, the exposed areas form the mask image.

[0138] The step of forming a mask image may also include, as desired, the step of removing either exposed or unexposed regions from the IL. In some embodiments, exposed regions of the IL are removed, for example, by ablating the exposed material in the IL. In this mechanism, the exposed regions of the IL are removed from the mask element by gas generation during ablation, leaving the mask image. Certain binders (e.g., uncrosslinked) may be present in the IL that decompose upon exposure to heat (e.g., generated by IL laser irradiation) and rapidly generate gas. This action should be distinguished from other mass transfer techniques in that it results in almost complete, rather than partial, movement of the IL through a chemical rather than physical change.

[0139] In other embodiments not shown, the mask image can be formed on a carrier sheet (and an LTHC layer placed thereon) by generating exposed and unexposed regions within the IL and selectively removing the unexposed regions.

[0140] In some embodiments, the mask image within the IL of the mask element can be cured by heat treatment, provided that the properties of the mask element are not adversely affected. Heat treatment can be carried out by various means, including, but not limited to, holding in an oven, hot air treatment, contact with a heated platen, or passing through a heated roller device. Heat treatment is not essential for curing.

[0141] In another embodiment, the mask image can be formed in the IL as described above, the exposure area can be transferred to the receptor sheet, and then it can be removed from the mask element and brought into contact with the relief forming plate. Such a procedure is well known in the industry.

[0142] In a peel-type imaging mechanism, the exposed areas of the IL can be removed from the carrier sheet (and the LTHC layer placed thereon) using an appropriate receptor sheet based on the differences in the adhesion properties of the IL. After image exposure of the mask master, the receptor sheet is separated from the carrier sheet, leaving either exposed or unexposed areas on the mask element.

[0143] relief forming master plate In some embodiments, a relief-forming master is fabricated and subsequently formed into a relief-drawing flexographic printing plate having a highlight region with a highlight microdot structure having a printed surface pattern. Many details of useful relief-forming masters, such as flexographic printing plates, letterpress printing plates, and printed circuit boards, are provided in U.S. Patent No. 182 (mentioned above). Such a relief-forming master may include a stable substrate of appropriate dimensions, a UV (ultraviolet)-sensitive relief-forming layer, and optionally, a cover sheet and / or metal layer between the substrate and the relief-forming layer. Suitable substrates include dimensionally stable polymer films and aluminum sheets. Polyester films are particularly useful. Any UV-sensitive material or element capable of generating a relief image using a mask element is useful in the practice of the present invention if it can form a patterned highlight-dot print head. A patterned highlight-dot print head can print the highlight dots described herein for better highlight-dot control and fade-out.

[0144] Figures 8C-8D show that the relief-forming master plate 855 typically includes a UV-sensitive layer 860 (for example, a photosensitive relief-forming layer having a low surface energy additive and being sensitive to curing UV radiation) supported on the substrate 865. Therefore, the resulting flexographic printing plate 866, shown in Figure 8E, has a highlight microdot structure 875 higher than the valleys 880 within the UV-sensitive layer 860.

[0145] In some embodiments, the relief-forming master generally includes a suitable, dimensionally stable substrate, a radiation-curable layer capable of forming a flexor relief image, and optionally a cover sheet on the radiation-curable layer and / or a metal layer between the substrate and the radiation-curable layer (e.g., shown as an interlayer boundary). Suitable substrates include flexible, dimensionally stable transparent polymer films, as well as metal substrates, such as aluminum sheets. Polyester films are particularly useful as flexible, dimensionally stable transparent substrates. The relief-forming master may optionally include a metal layer placed between the substrate and the radiation-curable layer. This metal layer may include copper or other metals or metal alloys.

[0146] In some embodiments, the radiation-curable layer may be a UV-sensitive layer that hardens with UV light. In some embodiments, the UV-sensitive layer may be at least one layer of a relief-forming plate formed from a UV-sensitive relief-forming material. Therefore, references to relief-forming materials or layers refer to UV-sensitive materials or layers that can be developed into a relief image by irradiation with UV light.

[0147] In some embodiments, the relief-forming master plate 900 in Figure 9 includes a backing material or base film 902 (e.g., a substrate), a relief-forming layer (e.g., a UV-sensitive material) 904, and optionally a removable cover sheet film 906 for protecting the photosensitive layer. In other options, a metal layer 910 may be placed between the substrate and the relief-forming layer.

[0148] In some embodiments, the backing material or base can be configured to support the relief-forming layer of the relief-forming master plate. The backing layer can be formed from a transparent or opaque material such as paper, cellulose film, plastic, or metal. Preferably, the backing layer is formed from a flexible transparent material. Examples of such materials are cellulose film or plastics such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyether, polyethylene, polyamide (Kevlar), or nylon. Preferably, the support layer is formed from polyethylene terephthalate (PET). It has also been found that a relief-forming layer having low surface energy additives can be bonded to the support layer. The support layer can be about 0.001 to about 0.010 inches thick. Optionally, various layers, such as an anti-halation layer and / or an adhesive layer, can be positioned between the backing layer and the relief-forming layer. In some embodiments, the adhesive layer may or may not contain an anti-halation material (e.g., a light-absorbing substance that prevents light refraction).

[0149] In some embodiments, the relief-forming layer can be a UV-sensitive material that forms a relief image by drawing and developing with UV light, and the relief image has a patterned highlight dot printhead to provide better highlight printing. In some embodiments, the photosensitive material can include a low surface energy material, which can provide many desirable properties to the relief image formation protocol, such as ease of vacuuming to reduce bubble formation and better lamination. In addition, the reduced peeling force makes it easier to remove the drawn mask from the relief-forming layer after the main UV exposure for forming the relief image. The protocol can then be performed by peeling the mask from the drawn relief-forming layer. Improved separation from lower surface energy and lower peeling force can be applied to larger plate sizes required for commercial applications. Therefore, in photosensitive relief-forming materials with lower surface energy and lower peeling force, the original plate assembly of the mask element and photopolymer plate is easier to separate.

[0150] In some embodiments, lower surface energy and lower peeling force are obtained by incorporating low surface energy additives into the photosensitive material composition. Low surface energy additives can be incorporated into the matrix of the photosensitive material, and may be present and dispersed within the body and on the surface of the photosensitive material. Often, low surface energy additives are homogeneously mixed into the photosensitive material. However, the additives may be provided randomly or non-uniformly (e.g., heterogeneously), or in a gradient such that the concentration increases preferentially on one side or the other.

[0151] In some embodiments, the low surface energy additive may include a silicone material, such as a silicone monomer having a reactive functional group. The reactive functional group can be selected to be polymerizable with other polymerizable monomers of the photosensitive material. This allows the silicone to be incorporated into the polymerizing material, thereby retained in the portion of the photosensitive material remaining after the relief formation process. As a result, the reactive functional group can be formulated from well-known functional groups that can participate in the polymerization reaction, or with specific types of other monomers having the same or different but appropriately reactive functional groups.

[0152] Low surface energy additives make it easier to separate the mask from the relief-forming plate. This provides lower surface energy to the relief image layer of the flexographic printing plate, which can be further advantageous for printing. This can reduce damage to the highlight dot printhead or its pattern.

[0153] In some embodiments, the silicone material of the low surface energy additive may contain acrylate functional groups, which may be reactive during polymerization. Acrylates (e.g., having hydrogen on the α-carbon) may be used, but other acrylates having substituents on the α-carbon may also be used. Other acrylates may be substituted acrylates due to substituents on the α-carbon. A common example is methacrylate having methyl on the α-carbon. The silicone portion may be attached to the oxygen of the ester of the acrylate portion. The silicone portion may contain linkers with the oxygen of the ester.

[0154] In some embodiments, the silicone material may include a polydimethylsiloxane (PDMS) main chain having alkyl or alkoxy side chains or acrylate groups such as acrylate or methacrylate. Such silicone acrylate additives are commercially available from various suppliers and may be called TEGO RAD (silicone polyether acrylate), e.g., TEGO RAD 2250, TEGO RAD 2300, TEGO RAD 2500, TEGO RAD 2700, CN9800 (difunctional aliphatic silicone acrylate oligomer), EBECRYL 350 (silicone diacrylate), or others.

[0155] In some embodiments, the silicone portion can be a monoacrylate, diacrylate, triacrylate, or other polyfunctional acrylate. Diacrylates and above can be involved in crosslinking with polymerizable monomers. As a result, polymerization can be used to crosslink a silicone polyfunctional acrylate monomer as a low surface energy additive. Therefore, the formation of a drawn UV-sensitive material can involve crosslinking the monomer with a silicone polyfunctional acrylate monomer.

[0156] In some embodiments, the low surface energy additive is not a silicone oil; that is, the low surface energy additive is not a free-state silicone in the material. Instead, embodiments include a low surface energy additive having a reactive functional group that can participate in polymerization, thereby covalently bonding the silicone to the polymerization material. In some embodiments, the low surface energy additive polymerizes when exposed to UV curing radiation. For example, silicone acrylate or silicone methacrylate can be used.

[0157] In some embodiments, low surface energy additives such as silicone acrylates may be included in the UV-sensitive material in amounts ranging from about 0.1% to about 5% by weight of the material, or from about 0.2% to about 4% by weight, or from about 0.3% to about 3% by weight, or from about 0.4% to about 2% by weight, or from about 0.5% to about 1%, or any of the ranges of the endpoints described, for example, 0.5% to about 2%.

[0158] In some embodiments, the low surface energy additive can be dispersed throughout the matrix. In some aspects, the low surface energy additive can be added to the upper surface of the UV-sensitive material.

[0159] The photosensitive layer may be in a positive or negative relief-forming plate, but is typically negative and generally includes a UV-sensitive layer (or a photocurable, relief image-forming layer, or photosensitive layer, etc.) containing a UV radiation-curable composition that hardens or solidifies by polymerization or crosslinking upon exposure to curing UV radiation. Many details regarding the various components of a UV-sensitive relief-forming plate are described in U.S. Patent No. 182 (above) and the references cited herein.

[0160] In some embodiments, the photosensitive material can be a UV-sensitive layer, which includes an elastomer binder, at least one polymerizable or photocurable monomer, a UV radiation-sensitive photopolymerization initiator, and a low surface energy additive, such as the polymerizable silicone material described herein. Suitable photopolymerization initiator compositions include, but are not limited to, those described in U.S. Patent No. 4,323,637 (Chen et al.), U.S. Patent No. 4,427,749 (Graetzel et al.), and U.S. Patent No. 4,894,315 (Feinberg et al.). Low surface energy additives can be added to the photopolymerization initiator composition to form a photosensitive material with reduced surface energy and reduced peel strength.

[0161] The elastomer binder may contain more polymers or resins that are soluble, swellable, or dispersible in aqueous, semi-aqueous, or organic solvent developers (described below), and may include, but is not limited to, blends of conjugated diolefins, block copolymers, core-shell type microgels, and macrogels, as well as pre-formed polymer polymers. The elastomer binder may contain at least 65% to a maximum of 90% by weight based on the total dry weight of the UV-sensitive layer.

[0162] In some embodiments, the elastomer binder may be a single polymer or a mixture of polymers (e.g., homopolymers, copolymers, random copolymers, block copolymers, or any number of different kinds of monomers) that are soluble, swollen, or dispersible in aqueous, semi-aqueous, or organic solvent developers (described below). Suitable binders include those described in U.S. Patent No. 3,458,311 (Alles), U.S. Patent No. 4,442,302 (Pohl), U.S. Patent No. 4,361,640 (Pine), U.S. Patent No. 3,794,494 (Inoue), U.S. Patent No. 4,177,074 (Proskow), U.S. Patent No. 4,431,723 (Proskow), and U.S. Patent No. 4,517,279 (Worns). Binders that are soluble, swellable, or dispersible in organic solvent developers include natural or synthetic polymers of conjugated diolefin hydrocarbons, including polyisoprene, 1,2-polybutadiene, 1,4-polybutadiene, butadiene / acrylonitrile, butadiene / styrene thermoplastic elastomer block copolymers, and other copolymers. Block copolymers discussed in U.S. Patent No. 4,323,636 (Chen), U.S. Patent No. 4,430,417 (Heinz), and U.S. Patent No. 4,045,231 (Toda) may be used. Elastomer binders may be present in an amount of at least about 65% by weight of the sensitive material. As used herein, the term binder includes core-shell type microgels and blends of microgels, as well as pre-formed polymer polymers, such as those described in U.S. Patent No. 4,956,252 (Fryd).

[0163] At least one polymerizable monomer can be configured to be compatible with the elastomer binder to such an extent that a clear, cloud-free, UV-sensitive, paintable layer is produced. Polymerizable monomers for this purpose are well known in the art and include ethylenically unsaturated polymerizable compounds with relatively low molecular weights (generally less than 30,000 Daltons). Suitable monomers have relatively low molecular weights, less than about 5000 Da. Throughout the specification, molecular weights are weight-average molecular weights unless otherwise specified. Examples of suitable polymerizable monomers include various mono and polyacrylates and acrylate derivatives of isocyanates, esters, and epoxides. In addition, suitable monomers include t-butyl acrylate, lauryl acrylate, alcohol and polyol acrylates and methacrylate mono and polyesters such as alkanols, e.g., 1,4-butanediol dialkylate, 2,2,4-trimethyl-1,3-pentanediol dimethacrylate, and 2,2-dimethylolpropane diacrylate, alkylene glycols such as tripropylene glycol diacrylate, butylene glycol dimethacrylate, hexamethylene glycol diacrylate, and hexamethylene glycol dimethacrylate, trimethylolpropane, ethoxylate trimethylolpropane, pentaerythritol such as pentaerythritol triacrylate, dipentaerythritol, and others. Other suitable monomers include isocyanates, esters, epoxy, and other acrylate and methacrylate derivatives, such as decamethylene glycol diacrylate, 2,2-di(p-hydroxyphenyl)propane diacrylate, 2,2-di(p-hydroxyphenyl)propane dimethacrylate, polyoxyethyl-2,2-di(p-hydroxyphenyl)propane dimethacrylate, and 1-phenylethylene-1,2-dimethacrylate. Further examples of monomers can be found in U.S. Patent No. 4,323,636 (Chen), U.S. Patent No. 4,753,865 (Fryd), U.S. Patent No. 4,726,877 (Fryd), and U.S. Patent No. 4,894,315 (Feinberg).The monoma may contain at least 5% to about 25% by weight of photosensitive material, which can be based on the total dry weight of the photosensitive material.

[0164] A photoinitiator can be any single compound or combination of compounds that is sensitive to ultraviolet radiation and generates free radicals that initiate the polymerization of one or more monomers without causing excessive termination reactions. A photoinitiator may be sensitive to visible or ultraviolet radiation. It may also not be sensitive to infrared and / or visible radiation and may be thermally inert below 185°C. Examples of suitable photoinitiators include substituted and unsubstituted polynuclear quinones. Examples of suitable systems are disclosed in U.S. Patent No. 4,460,675 (Gruetzmacher) and U.S. Patent No. 4,894,315 (Feinberg). Generally, photoinitiators are present in amounts of 0.001% to 10.0% by weight based on the weight of the photosensitive material.

[0165] In some embodiments, the photosensitive layer may include a di- or triblock copolymer (e.g., an elastomer), at least one photopolymerizable monomer, additives such as photopolymerization initiators, plasticizers, stabilizers, inhibitors, dyes, and solvents, and low surface energy additives such as silicone acrylate or silicone methacrylate.

[0166] In some embodiments, the plasticizer may be any suitable plasticizer known in the art for the photosensitive layer used as described herein. Examples of suitable plasticizers include aliphatic hydrocarbon oils, e.g., naphthenic oils and paraffinic oils, liquid polydienes, e.g., liquid polybutadiene and liquid polyisoprene. Generally, plasticizers are liquids with a molecular weight of less than about 5,000 Da, but can have molecular weights up to about 30,000 Da. Low molecular weight plasticizers also include molecular weights of less than about 30,000 Da.

[0167] In some embodiments, additives may include rheological modifiers, thermal polymerization inhibitors, stabilizers, inhibitors, tackifiers, dyes, antioxidants, anti-ozone agents, solvents, or fillers. These materials are commonly used in photosensitive layers, and examples can be provided in the references cited.

[0168] The thickness of the photosensitive layer may vary depending on the desired type of printing plate. In one embodiment, the photosensitive layer may be, for example, about 20 to 250 mils (500 to 6,400 micrometers) or more, more specifically, about 20 to 100 mils (500 to 2,500 micrometers) thick.

[0169] In some embodiments, the relief-forming master is a flexographic printing master, which includes a suitable UV-curable composition (e.g., a photosensitive material) in a UV-sensitive layer (e.g., a photosensitive layer) that, when exposed and developed through a mask element, provides a relief image to the flexographic printing plate. Such relief-forming masters generally include a suitable substrate made of a photosensitive material. Examples of commercially available flexographic printing masters include, but are not limited to, the FLEXCEL NX flexographic element available from Miraclon Corporation, the CYREL® Flexographic plate available from DuPont (Wilmington, Delaware), the NYLOFLEX°FAR 284 printing plate available from BASF (Germany), the FLEXILIGHT CBU plate available from Macdermid (Denba, Colorado), and the ASAHI AFP XDI available from Asahi Kasei (Japan). These flexographic printing masters can be modified to include low surface energy additives as described herein.

[0170] In some embodiments, the relief-forming master can also be used to form a printed circuit board, in which case a conductive layer (also known as the “printed circuit”) is formed on the substrate in a pattern defined by exposure through a mask element. A suitable master for a printed circuit board generally comprises a substrate, a metal layer, and a UV-sensitive dredging layer (e.g., a photosensitive material). Suitable substrates include, but are not limited to, polyimide films, glass-filled epoxy or phenol-formaldehyde, or any other insulating material known in the art. The metal layer covering the substrate is generally a conductive metal or alloy or metallic material such as copper. The UV-sensitive dredging layer may include a UV-curable resin, a polymerizable monomer or oligomer, a photopolymerization initiator, and a polymer binder. Further details of printed circuit boards are provided in U.S. Patent No. 182 (mentioned above).

[0171] Formation of relief image After both the mask element and the relief-forming master are formed as described above, the mask element includes a photosensitive layer having a low surface energy additive and being sensitive to curing UV radiation, and is brought into complete optical contact with the relief-forming master. This protocol can be implemented by placing the mask element on top of the relief-forming master or vice versa, which will be described in more detail later. For example, bringing the mask element into contact with and bonding it to the relief-forming master can be done using lamination equipment and processing. Vacuuming the mask element to the relief-forming master can also be done with or without lamination to achieve the desired complete optical contact.

[0172] Several embodiments of the present invention can be understood by referring to the general explanatory diagrams provided in the sequence of Figures 8A to 8E. As previously stated, Figure 8A shows a mask master 810 that is exposed to exposure infrared radiation 835 to form a mask element 836 (Figure 8B).

[0173] In Figure 8C, the mask element 836 includes an IL layer 815 on top of an LTHC layer 820 (e.g., having non-absorbable particles) on top of an ablated IL layer 830 in which a mask image is formed. The mask element 836 is shown to provide a relief image forming assembly 850 in close or complete optical contact with the relief forming master 855. The relief forming master 855 typically includes a UV-sensitive layer 860 (e.g., a photosensitive relief forming layer having low surface energy additives and being sensitive to curing UV radiation) supported on a substrate 865.

[0174] Figure 8D shows the step of exposing the relief image forming assembly 850 to UV radiation 870, indicated by the arrow. The UV radiation 870 passes through the transparent polymer carrier sheet 815 of the mask element 836, the LTHC layer 820, and the exposure area (e.g., the area where the element 840-IL layer is removed) to photocur the UV-sensitive layer 860 of the relief forming master 855.

[0175] After UV exposure, the mask element 836 can be removed from the UV-sensitive layer 860 of the relief-forming master plate 855, and the development protocol can provide a relief image (Figure 1F) within the UV-sensitive layer 860. As shown in the figure, the relief image includes relief image peaks 875 (e.g., highlight microdot structures) and relief image valleys 880 within the UV-sensitive layer 860.

[0176] Lamination As mentioned above, the mask element and the relief-forming master can be placed in perfect optical contact so as to provide an air-free interface at the shared interface. Generally, this is achieved by laminating the mask element to the UV-sensitive layer of the relief-forming master by applying appropriate pressure and / or heat to form an air-free or gap-free interface before UV exposure. However, if the relief-forming master is UV-sensitive, the lamination procedure may be unnecessary. In that case, as mentioned above, vacuuming the masking element from the relief-forming master may also be useful.

[0177] Commercially available laminators that provide both heat and uniform pressure can be used, including, but are not limited to, the KODAK Model 800XL Approval Laminator available from Eastman Kodak Company (Rochester, New York). The CODOR LPP650 Laminator available from CODOR (Amsterdam, Netherlands) and the LEDCO HD Laminator available from Filmsource (Kasselbück, Florida) may also be useful. If a clear polymer overcoat layer is attached directly to the IL of the mask element material, this can be removed before lamination or other operations that form full optical contact between the relief-forming plate and the mask element. The relief image forming assembly formed by joining the mask element and the relief-forming plate can be fed into the laminator at the desired speed, temperature, and pressure.

[0178] Useful lamination (laminator) devices and methods of use thereof are described, for example, in U.S. Patent No. 7,802,598 (Zwadlo et al.), the disclosure of which is incorporated herein by reference. As described therein, a prepress flexographic laminator can be used to laminate a mask element ("masking film") onto a relief-forming plate ("prepress flexographic printing plate") by applying a balanced, distortion-free, optimized laminating force to achieve perfect optical contact while minimizing lateral distortion.

[0179] In some embodiments, the relief-forming master does not have a separation layer, spacer layer, or anti-sticking layer on top of the UV-sensitive relief-forming layer, thereby achieving an air-free interface solely by pressure, because a relief-forming layer having a low-surface-energy additive within it can still be sticky or act as a pressure-sensitive adhesive due to the presence of polymerizable monomers. The amount of the low-surface-energy additive can be adjusted within parameters defined herein to obtain a desired or optimal level of tackiness. Too much low-surface-energy additive results in a less sticky surface, in which case thermal lamination may be used to provide optical contact bonding with the mask.

[0180] UV exposure Once complete optical contact is achieved between the mask element and the relief-forming master as described above, the relief-forming master can be exposed to curing UV radiation through the mask element to form a printed relief-forming master having exposed and unexposed regions within the UV-sensitive layer. The exposed regions are cured and solidified by polymerization of monomers within the UV-sensitive layer. The unexposed regions remain uncured, and the monomers do not polymerize. Therefore, uniformly emitted curing UV radiation is projected onto the relief-forming master through a mask, which preferentially blocks a portion of the ultraviolet radiation by the remaining portion of the IL layer. In the unmasked (exposed) regions, curing UV radiation causes solidification or curing of the UV-sensitive composition within the IL. The masked image is therefore substantially opaque to the exposure or curing UV radiation, meaning that the masked image should have a transmitted optical density of 2 or more, typically 3 or more, in the unexposed regions. The remaining portion of the IL layer still contains UV-sensitive material to absorb and block UV light. The unmasked (exposed) areas of the UV-sensitive composition can be substantially transparent, meaning they should have a transmitted optical density of 0.5 or less, even 0.1 or less, more typically at least 0.5 to a maximum of 0.1, or at least 0.1 to a maximum of 0.3. The transmitted optical density can be measured using a suitable filter in a densitometer, such as a MACBETH TR 927 densitometer.

[0181] Generally, exposure of the relief-forming plate through the mask element is achieved by flood exposure from a suitable source of UV radiation. Exposure can be performed in the presence of atmospheric oxygen. Exposure under vacuum is unnecessary because complete optical contact has already been established.

[0182] In the manufacture of relief drawing elements such as flexographic printing plates, generally, one side of the relief-forming plate is first exposed to curing UV radiation through its transparent substrate (known as "backside exposure") to create a thin, uniform cured layer (e.g., relief image valleys 880) on the substrate surface of the UV-sensitive layer. The relief-forming plate is then exposed to curing UV radiation through a mask element containing a mask image, thereby solidifying or curing the areas of the UV-sensitive layer that are not masked (exposed). The unexposed and uncured areas of the UV-sensitive layer can then be removed by a development process (described later), leaving behind a cured or solidified area (e.g., relief image peaks 75) that defines the relief image printing surface of a predetermined desired pattern of peaks 875 (e.g., highlight microdot structure) and valleys 880 in terms of shape and size. Backside exposure can be performed either before or after complete optical contact between the mask element and the relief-forming layer.

[0183] The appropriate wavelength or wavelength range for curing UV radiation is determined by the electromagnetic sensitivity of the relief formation layer. In some embodiments, the UV curing radiation can have one or more wavelengths in the range of at least 150 nm to a maximum of 450 nm, more typically at least 300 nm to a maximum of 450 nm. UV radiation sources for flood or full-surface exposure include, but are not limited to, carbon arcs, mercury vapor arcs, fluorescent lamps, electronic flash units, and photographic floodlights. UV radiation from mercury vapor lamps and solar lamps is particularly useful. Typical UV radiation sources include the SYLVANIA 350 BLACKLIGHT fluorescent lamp (FR 48T12 / 350 VL / VHO / 180,115 watts) with a central emission wavelength of approximately 354 nm, available from Topbulb (East Chicago, Indiana), and the BURGESS EXPOSURE FRAME, Model 5K-3343V511, which features the ADDALUX 754-18017 lamp, available from Burgess Industries, Inc. (Plymouth, Massachusetts). UV wavelength SQUAREspot lasers can also be used to form highlighted microdot printing surface patterns.

[0184] Other suitable UV radiation sources include platemakers that can be used for both exposing the relief-forming plate to radiation and developing the drawn relief-forming material after exposure. Examples of suitable platemakers include, but are not limited to, the KELLEIGH MODEL 310 PLATEMAKER, available from Kelleigh Corporation (Trenton, New Jersey), and the GPP500F PLATE PROCESSOR, available from Global Asia LTD. (Hong Kong).

[0185] The exposure time through the mask element depends on the properties and thickness of the UV-sensitive layer of the relief-forming plate and the source and intensity of the UV radiation. For example, in one embodiment, a FLEXCEL-SRH printing plate, available from Eastman Kodak Company, can be mounted on a KELLEIGH MODEL 310 PLATEMAKER and exposed to UV-A radiation through a transparent support for approximately 20 seconds on the back surface to create a thin, uniform hardened layer on the support side of the relief-forming plate. Then, the relief image forming assembly of the mask element and the relief-forming plate can be exposed to UV radiation through the mask element for approximately 14 minutes. In this way, the mask image information is transferred to the relief-forming plate (e.g., a flexographic printing plate).

[0186] Separation of the mask from the UV-sensitive layer In general, the methods described herein may also include removing the mask elements from full optical contact with the drawn relief-forming plate after UV exposure and before development. This can be done by any suitable method, such as peeling the two elements apart. For example, this can be achieved by peeling the mask elements from the drawn relief-forming plate.

[0187] In some embodiments, after UV exposure, the mask element can be removed by peeling it from the relief-forming layer. This can be done by supporting one of the mask element or the relief-forming master and then applying a peeling force to the edge or end of the other of the mask element or the relief-forming master (e.g., the relief-forming layer). Low surface energy additives can be used to obtain lower surface energy and lower peeling force, thereby making separation easier without damaging the relief-forming layer mask element. As a result, the easier peeling or separation due to lower surface energy and lower peeling force prevents delamination of the mask element, thereby allowing the mask element to be reused. Furthermore, lower surface energy and lower peeling force can also prevent quality degradation and undesirable damage to the ridges of the relief-forming layer.

[0188] In some embodiments, the mask element can be delaminated from the relief-forming plate, for example, by delaminating from the relief-forming layer. In these embodiments, the mask element is laminated to the relief-forming layer. The mask is then delaminated from the relief-forming layer after UV curing. However, such delamination does not mean that the mask itself is delaminated, or that different layers of the mask element are delaminated from one another. Here, the mask element is delaminated entirely from the relief-forming layer due to the presence of a low-surface-energy additive. Therefore, the mask is delaminated from the relief-forming layer, but the mask itself is not delaminated and is not damaged. Similarly, the relief-forming layer is not delaminated from the relief-forming plate.

[0189] In some embodiments, the relief-forming master does not need to have a transparent release layer on the UV-sensitive layer. Then, a low surface energy additive can facilitate the removal of the mask from the relief-forming master. Therefore, the UV-sensitive relief-forming layer can be in direct contact with the mask element, thereby separating the mask directly from the relief-forming layer. The low surface energy additive can reduce surface energy and adhesion, resulting in a clean separation that does not damage either the mask element or the relief-forming master.

[0190] Flexographic printing plate assemblies with a UV-sensitive layer contain a unique combination of materials, allowing for quick and complete mask peeling. "Completely" means that at least 95%, preferably at least 98%, at least 99%, or 100% of the mask is peeled off, with little to no material remaining. The composition of the UV-sensitive layer provides a peeling force of less than about 73 g / inch, preferably less than about 60 g / inch, and more preferably less than about 55 g / inch, with respect to the mask element containing the mask image. The relief-forming layer may have some peeling force with respect to the mask, for example, at least 1 g / inch, at least about 5 g / inch, or at least about 10 g / inch.

[0191] In some embodiments, the relief-forming layer is a solvent-cleanable printing plate master and has a peel force of less than about 73 g / inch, preferably less than about 60 g / inch, more preferably less than about 55 g / inch, with respect to the mask element including the mask image. The solvent-cleanable relief-forming layer may have some degree of peel force with respect to the mask, for example, at least 1 g / inch, at least about 5 g / inch, or at least about 10 g / inch.

[0192] In some embodiments, the relief-forming layer is a water-washable printing plate master and has a peel force of less than about 40 g / inch, preferably less than about 30 g / inch, more preferably less than about 20 g / inch, with respect to the mask element including the mask image. The water-washable relief-forming layer may have some degree of peel force with respect to the mask, for example, at least 1 g / inch, at least about 5 g / inch, or at least about 10 g / inch.

[0193] The peel force can be measured by attaching a 2.54 cm wide x 25.4 cm long strip of mask, laminated to the UV-sensitive layer with a low surface energy additive of a UV-exposed flexograph printing plate, to an IMASS SP-2000 slip / peel tester (IMASS Inc., Accord, Massachusetts) with double-sided tape, with the printing plate facing downwards. Peel the first end of the mask from the printing plate and attach it to the force gauge. Measure the maximum peel force in units of g / film in a straight inch (2.54 cm) width at a peel angle of 180° and a peel speed of 2 cm / second.

[0194] In some embodiments, the mask element, including the mask image, is removed from the UV-exposed UV-sensitive relief-forming layer of the flexographic printing plate by peeling it off at the interface between the mask element and the relief-forming layer. This peeling process can be carried out using vacuum to maintain position, as described in U.S. Patent No. 7,802,598. The corners of the mask element are then isolated from the printing plate at a speed of 2 to 10 cm / sec and a peeling angle of 150 to 180°, and while holding the drawn film near the surface of the vacuum table, it is peeled off in a continuous motion, essentially in the direction in which the drawn film was folded, so that the entire mask element is removed from the UV-sensitive layer of the printing plate. In practice of the present invention, at least 95% by weight of the dried mask element is removed in this operation, and therefore, in general, it can be said that the mask element is removed "completely" or substantially completely from the exposed radiation-curable layer of the plate. "Completely" means that at least 95%, preferably at least 98%, at least 99%, or 100% of the mask is removed, leaving little to no material behind.

[0195] developing After the mask elements are removed from the relief-forming layer, the drawn relief-forming plate is generally developed with a suitable developer (e.g., a processing solution or "washing solution") to form a relief image. Development removes the unexposed (uncured) areas of the UV-sensitive layer, leaving exposed (cured) areas that define the relief image as shown in Figure 8E, which is obtained from the relief-forming plate in Figure 9.

[0196] In this processing step, any known organic solvent system or aqueous developer can be used, including known developers that primarily contain chlorinated organic solvents. However, other useful developers are primarily non-chlorinated organic solvents. "Primarily" means that more than 50% (by volume) of the developer contains one or more non-chlorinated organic solvents, such as aliphatic hydrocarbons and long-chain alcohols (alcohols having at least seven carbon atoms). The remainder of the developer may be chlorinated organic solvents known in the art for this purpose.

[0197] Certain useful developers are primarily known as "perchloroethylene alternative solvents" (PAS), which are generally volatile organic compounds consisting typically of a mixture of aliphatic hydrocarbons and long-chain alcohols. Examples of such commercially available solvents include, but are not limited to, PLATESOLV from Hydrite Chemical Co. (Brookfield, Wisconsin), NYLOSOLV® from BASF (Germany), FLEXOSOL® from DuPont (Wilmington, Delaware), OptiSol® from DuPont (Wilmington, Delaware), and SOLVIT°QD from MacDermid (Denba, Colorado).

[0198] Other useful developers are described in U.S. Patent No. 5,354,645 (Schober et al.), whose disclosure is incorporated herein by reference, and include diethylene glycol dialkyl ethers, acetates or alcohols, carboxylates, and esters of alkoxy-substituted carboxylates. Further useful developers are described in U.S. Patent No. 6,162,593 (Wyatt et al.) and U.S. Patent No. 6,248,502 (Eklund), which describe developers containing diisopropylbenzene (DIPB).

[0199] Other useful developers are described in U.S. Patent No. 6,582,886 (Hendrickson et al.), which include methyl esters alone or mixtures of methyl esters with various cosolvents such as alcohols that dissolve in the methyl esters. U.S. Patent Publication No. 2010 / 0068651 (Bradfold) describes useful developers containing dipropylene glycol dimethyl ether (DME) alone or in combination with various cosolvents such as alcohols or aliphatic dibasic acid ethers. Yet another useful developer is described in U.S. Patent Publication No. 2011 / 0183260 (Fohrenkamm et al.). Another useful developer is described in U.S. Patent No. 8,771,925 (Fohrenkamm et al.), which contains diisopropylbenzene and one or more organic cosolvents, one of which is an aliphatic dibasic acid ester. Another useful developer is described in U.S. Patent No. 9,005,884 (Yawada et al.), which may contain alkali metal salts of saturated fatty acids having 12 to 18 carbon atoms and alkali metal salts of unsaturated fatty acids having 12 to 18 carbon atoms in a weight ratio of 20:80 to 80:20 of the first fatty acid salt to the second fatty acid salt.

[0200] Another useful developer is described in U.S. Patent No. 10,248,025 (Ollmann et al.). Such a flexographic developer may contain: a) a fatty acid composition comprising one or more saturated or unsaturated fatty acids or alkali metal salts thereof, each saturated or unsaturated fatty acid or alkali metal salt having 12 to 20 carbon atoms individually, present in an amount from at least 0.25% by weight to a maximum of 2.0% by weight, wherein at least 85% by weight of the fatty acid composition consists of C18 mono- or polyunsaturated fatty acids or alkyl metal salts thereof; b) an amount from at least 0.05% by weight to a maximum of 0.30% by weight of an aminopolycarboxylate or alkali metal salt thereof; c) an amount from at least 0.5% by weight to a maximum of 0.60% by weight of a buffer compound; and d) water.

[0201] Development can be carried out under known conditions, such as a minimum development time of 1 minute and a maximum development time of 20 minutes, and a temperature of at least 20°C and a maximum development time of 32°C. Specific development conditions are determined by the developing apparatus and the type of developer used, and can be adjusted by those skilled in the art.

[0202] Post-development processing of the relief image of a pre-drawn relief plate may be appropriate depending on the circumstances. Typical post-development processing includes removing excess solvent by drying the relief image and post-curing by exposing the relief image to curing radiation to further solidify or crosslink. The conditions for these processes are well known to those skilled in the art. For example, the relief image can be dried by suction or wiping, or dried in a forced-air or infrared oven. The drying time and temperature will be obvious to those skilled in the art. Post-curing can be performed using the same type of UV radiation previously used to expose the relief plate through the pre-drawn mask material.

[0203] If the relief image surface remains sticky, a de-sticking treatment (or "light finishing") can be used. These treatments, for example, using bromide or chlorine solutions or exposure to UV or visible radiation, are well known to those skilled in the art.

[0204] The resulting relief image can have a depth of at least 2% to a maximum of 100% of the initial thickness of the UV-sensitive layer (for example, if this layer is placed on a substrate). In the case of a flexographic printing plate, the maximum dry depth of the relief image can be at least 150 μm to a maximum of 1,000 μm, or typically at least 200 μm to a maximum of 500 μm. In the case of a printed circuit board, the UV-sensitive layer can be completely removed in either exposed or unexposed areas to expose the underlying metal layer. In such cases, the maximum depth of the relief image depends on the dry thickness of the UV-sensitive layer. Advantageously, in any embodiment, the shoulder angle of the relief image can be greater than 50°.

[0205] Therefore, in some embodiments, a method is employed such that the relief-forming master is a UV-sensitive flexographic printing master, and drawing and developing such a master provides a flexographic printing plate having a relief image layer formed from the relief-forming layer of the relief-forming master. Similarly, a relief printing plate can also be made from a suitable master element.

[0206] In some embodiments, the relief image layer can receive ink during the process of drawing the relief image with ink, as shown in Figure 1. The ink can be applied to the relief image layer in an appropriate amount that helps reduce dot gain after printing. Thus, the relief image can be made more resistant to dot gain after printing. This overcomes the problem of flexographic printing plates having excessively large dot gain after printing.

[0207] In some embodiments, the ink-covered relief image layer can be cleaned to remove the ink for various reasons, such as changing the color or cleaning the surface to apply new ink. Ink replacement can also help remove particles from the relief image layer that may be generated during the process. The cleaning system can be configured to facilitate ink cleaning and to make it easier to remove ink from feature areas of the surface (e.g., raised areas, valleys, etc.) after printing. This allows the relief to be kept clean, the printing plate to be stored, and reused for printing later.

[0208] Those skilled in the art will readily understand the diverse applications of such ink-coated elements in various industries, including flexographic printing of various packaging materials.

[0209] This can also be applied to packaging materials made from other substrates such as cardboard, corrugated cardboard, or labels, using water-based, UV-curable, or EB-curable inks. [Examples]

[0210] Examples definition When used herein to define various components of the ablation-non-photothermal conversion (LTHC) layer, the non-halogenated silver thermal ablation-enabled drawing layer (IL), and other materials, layers, and compositions (e.g., developers or processing solutions) used in practice of the present invention, singular articles (a, an, the) are intended to include one or more of those components (i.e., include multiple references), unless otherwise indicated.

[0211] Any term not explicitly defined in this application shall be understood to have the meaning generally accepted by those skilled in the art. Where an interpretation of a term would make it meaningless or essentially meaningless in the context, that term should be interpreted as having its standard dictionary meaning.

[0212] The use of numerical values ​​within the various ranges specified herein is considered approximate unless explicitly indicated otherwise, such as when the word “approximately” precedes both the minimum and maximum values ​​within the specified range. Thus, slight variations above and below the specified range may be useful in achieving substantially the same results as the numerical values ​​within that range. In addition, these disclosures of ranges shall be continuous ranges, including the minimum and maximum values ​​within that range, as well as the individual values ​​between the endpoints.

[0213] The ablation-free photo-to-thermal conversion layer is also identified herein as the LTHC layer.

[0214] Non-halogenated silver thermal ablationable writing layer is also identified herein as IL.

[0215] Unless otherwise specified herein, the term “drawable material” is used to refer to the articles of embodiments produced and used according to the present invention. Such drawable materials may also be known as “mask films,” “mask masters,” or “mask elements.” Drawable materials can be converted into “mask elements” by appropriate thermal (IR) drawing, which include mask images that can be used according to the present invention to form relief images.

[0216] Unless otherwise specified, percentages are based on weight.

[0217] As used herein, the term “relief-forming plate” refers to any drawable element or drawable material that can generate a relief image by exposure through a mask element. Examples of such relief-forming plates will be described in detail later, but some relief-forming plates include flexographic printing plates, letterpress printing plates, and printed circuit boards. Such relief-forming materials are described in U.S. Patent Application Publication No. 2005 / 0227182 (mentioned above), the disclosure of which is incorporated herein by reference. In that publication, relief-forming plates are generally identified as “radiation-sensitive elements.”

[0218] Unless otherwise specified, the terms “ablation” or “ablation” refer to laser thermal writing, which causes rapid local changes within a non-halogenated silver thermal ablable writing layer (IL) of a writeable material, thereby allowing the material to be ejected from the IL. This is distinct from other material transitions or writing techniques, such as melting, evaporation, or sublimation.

[0219] The terms “optical contact” and “perfect optical contact” refer to two layers or elements (such as a mask element and a relief-forming plate) that share an interface, are in close physical contact, and therefore have essentially no air gap or void between the contact surfaces, thus providing an “air-free interface.” More precisely, two surfaces are defined as being in optical contact when the reflective and transmitting properties of their interface are essentially well explained by Fresnel’s law relating to the reflection and transmission of light at refractive index boundaries.

[0220] Unless otherwise stated, the term “transparent” as used herein refers to the ability of a material or layer to transmit at least 95% of electromagnetic radiation to which it is irradiated (or incident), such as electromagnetic radiation having wavelengths of at least 200 nm to 750 nm (i.e., what is commonly known in the art as UV and visible radiation). The transparent polymer carrier sheets and LTHC layers described below have this property in particular.

[0221] The "average dry thickness" of a dry layer is generally the average of 10 different measurements taken from a cross-sectional image of the layer in its dry state.

[0222] The highlight area of ​​a flexographic printing plate is less than 100 micrometers, less than 90 micrometers, less than 80 micrometers, less than 70 micrometers, less than 60 micrometers, less than 50 micrometers, or less than 40 micrometers, and is considered to have microdots larger than 35 micrometers. The microdot dimensions are the longest dimensions of the microdot printhead. Microdots are present in 5% or less of the highlight area of ​​the flexographic printing plate. Areas with a higher density of dots or microdots, exceeding 5% of the area, are not considered highlight areas.

[0223] Those skilled in the art will see that, with respect to the processes and methods disclosed herein, the functions performed in those processes and methods may be performed in a different order. Furthermore, the steps and actions outlined are merely examples, and some of those steps and actions may be optional, or may be combined into fewer steps and actions, or may be extended into additional steps and actions, without diminishing the essence of the disclosed embodiments.

[0224] This disclosure is not limited to the specific embodiments described herein, which are intended to be examples of various aspects. Many improvements and modifications can be made without departing from the spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatus within the scope of this disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing description. These improvements and modifications are intended to be included within the scope of the accompanying claims. This disclosure is limited only by the language of the accompanying claims and the entire scope of equivalents to be recognized for such claims. This disclosure should be understood as not being limited to any particular method, reagent, compound, composition, or biological system, which, needless to say, can change. It should also be understood that the terminology used herein is intended to describe only specific embodiments and is not limiting.

[0225] With regard to substantially any use of plural and / or singular terms in this specification, those skilled in the art can appropriately interpret plural to singular and / or singular to plural terms as appropriate to the context and / or use. For clarity, various singular / plural substitutions may be explicitly noted in this specification.

[0226] Those skilled in the art will generally understand that the terminology used in this specification and, in particular, in the accompanying claims (e.g., the body of the accompanying claims) is intended to be generally "open" terminology (for example, the term "contains" should be interpreted as "contains but not limited to," the term "has" should be interpreted as "has at least," and the term "includes" should be interpreted as "contains but not limited to," etc.). Furthermore, those skilled in the art will understand that if a certain number of claim elements are intended to be introduced, such intention will be clearly stated in the claim, and if such statement is absent, such intention does not exist. For example, to aid understanding, the following accompanying claims may include the use of the prefatory phrases "at least one" and "one or more" to introduce claim elements. However, the use of such phrases should not be interpreted as implicitly limiting any particular claim containing such introduced claim elements to embodiments containing only one such element, even if the same claim contains the prefatory phrases "one or more" or "at least one" (for example, "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"), and the same applies to the use of definite articles used to introduce claim elements. Furthermore, even if a specific number of introduced claim elements is explicitly stated, a person skilled in the art will see that such a statement should be interpreted as meaning at least the stated number (for example, the sole statement "two elements" without other modifiers means at least two elements or two or more elements).Furthermore, in examples where similar phrasing to "at least one of A, B, and C, etc." is used, such constructions are generally intended to be understood by those skilled in the art (for example, "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, A and B, A and C, B and C, and / or A, B and C, etc.). In examples where similar phrasing to "at least one of A, B, or C, etc." is used, such constructions are generally intended to be understood by those skilled in the art (for example, "a system having at least one of A, B, or C" includes, but is not limited to, systems having only A, only B, only C, A and B, A and C, B and C, and / or A, B and C, etc.). Furthermore, a person skilled in the art will understand that virtually any disjunct word and / or phrase representing two or more alternative terms should be understood as construed to include, whether in the specification, claims, or drawings, one of those terms, any of those terms, or both of those terms. For example, the phrase "A or B" is understood to include the possibilities of "A" or "B" or "A and B".

[0227] In addition, where any feature or aspect of the present disclosure is described in relation to the Markush Group, a person skilled in the art will see that the disclosure also describes any individual component or subgroup of components within that Markush Group.

[0228] As will be apparent to those skilled in the art, for all purposes, including providing descriptive explanations, all scopes disclosed herein include all conceivable sub-scopes and combinations thereof. It will be readily understood that each of the scopes mentioned adequately explains and enables the division of the same scope into at least two, three, four, five, ten, etc., parts. As a non-limiting example, each scope discussed herein can be readily divided into a lower third, a middle third, an upper third, etc. Likewise, as will be apparent to those skilled in the art, all phrases such as “up to,” “at least,” etc., include the number stated and then refer to a scope that can be divided into sub-scopes as described above. Finally, as will be apparent to those skilled in the art, a certain scope includes each of its individual components. Therefore, for example, a group having 1 to 3 cells refers to each group having 1, 2, or 3 cells. Similarly, a group having 1 to 5 cells refers to each group having 1, 2, 3, 4, or 5 cells, and so on.

[0229] From the foregoing, it will be clear that the various embodiments of this disclosure are described herein for illustrative purposes only and can be modified in various ways without departing from the spirit and scope of this disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, and their exact scope and spirit are shown in the following claims.

[0230] All references cited herein are incorporated herein by their individual references.

Claims

1. Highlight microdot mask element, A drawing area arranged in a highlight microdot printed surface pattern, each drawing area having at least one drawing block and at least one drawing area that is light-transmitting, At least one opaque island formed by at least one non-drawn block within the highlight microdot printed surface pattern, wherein the arrangement of the plurality of drawing areas and the at least one opaque island defines the highlight microdot printed surface pattern, An opaque void region surrounding the highlight microdot pattern formed by multiple non-drawn blocks, A highlight microdot mask element that includes this element.

2. Each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of approximately 10 to 11 micrometers. The width of each drawing area is at least 1 / 4 pixel. The height of each drawing area is at least 1 pixel. The width of the aforementioned microdot pattern is in the range of 2 pixels to 8 pixels. The height of the aforementioned microdot pattern is in the range of 3 to 8 pixels. The width of each internal opaque island is at least 1 / 4 pixel. The height of each internal opaque island is at least 1 pixel. The highlight microdot mask element according to claim 1.

3. The width of at least one drawing area is at least 1 / 2 pixel, At least one drawing area has a height of at least 2 pixels. The width of the aforementioned microdot pattern is in the range of 2.5 pixels to 4 pixels. The height of the microdot pattern is in the range of 4 to 6 pixels. The width of at least one internal opaque island is at least 1 / 2 pixel, At least one internal opaque island has a height of at least 2 pixels, and each non-drawable block touches another drawable block by at least 1 / 4 of a pixel. The highlight microdot mask element according to claim 2.

4. The at least one drawing region forms at least one outer boundary region of an outer boundary pattern, and each outer boundary region has at least one drawing block and is light-transmitting. The at least one internal opaque island is formed by at least one non-drawn block within the outer boundary pattern, The opaque void region surrounds the outer boundary pattern. The highlight microdot mask element according to claim 1.

5. The highlight microdot mask element according to claim 4, wherein each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of about 10 micrometers to about 11 micrometers.

6. The at least one outer boundary pixel region forms a continuous annular boundary region where each drawing block touches another drawing block at least at its corner, or The multiple outer boundary pixel regions form a discontinuous annular boundary region, wherein at least one gap of non-drawn blocks lies between two adjacent drawing blocks of the multiple outer boundary pixel regions. The highlight microdot mask element according to claim 4.

7. The width of each outer boundary pixel region is at least 1 / 4 of a pixel. The height of each outer boundary pixel region is at least 1 pixel. The width of the outer boundary pattern is in the range of 2 pixels to 8 pixels. The height of the outer boundary pattern is in the range of 3 pixels to 8 pixels. The width of each internal opaque island is at least 1 / 4 pixel. The height of each internal opaque island is at least 1 pixel. The highlight microdot mask element according to claim 5.

8. The width of at least one outer boundary pixel region is at least 1 / 2 pixel, The height of at least one outer boundary pixel region is at least 2 pixels. The width of the outer boundary pattern is in the range of 2.5 pixels to 4 pixels. The height of the outer boundary pattern is in the range of 4 pixels to 6 pixels. The width of at least one internal opaque island is at least 1 / 2 pixel, At least one internal opaque island has a height of at least 2 pixels, and each non-drawable block touches another non-drawable block by at least 1 / 4 of a pixel. The highlight microdot mask element according to claim 7.

9. One internal opaque island within a continuous annular boundary region, One internal opaque island within a discontinuous annular boundary region, Multiple internal opaque islands within a continuous annular boundary region, or Multiple internal opaque islands within a discontinuous annular boundary region A highlight microdot mask element according to claim 4, comprising at least one of the following.

10. One internal drawing region within a continuous ring-shaped boundary region, One internal drawing region within a discontinuous annular boundary region, Multiple internal drawing regions within a continuous annular boundary region, or Multiple internal drawing regions within a discontinuous annular boundary region A highlight microdot mask element according to claim 4, comprising at least one of the following.

11. At least 20 total blocks, At least 16 drawing blocks in the aforementioned pattern, At least four non-drawable blocks within the at least one internal opaque island, It includes at least one of the following, or At least 20% of the total blocks are non-drawable blocks. The highlight microdot mask element according to claim 1.

12. One or more outer boundary regions that jointly form a light-transmitting ring, An internal opaque island formed by a plurality of non-drawable blocks within the light-transmitting ring, wherein the island width is at least 1 / 2 pixel and the island height is at least 2 pixels, The opaque void region surrounding the light-transmitting ring, A highlight microdot mask element according to claim 4, comprising:

13. A mask for a flexographic printing plate that generates highlights, The highlight microdot mask element according to claim 1, An image pattern having a highlight mask region with the aforementioned highlight microdot mask elements, A mask for a flexographic printing plate that generates highlights, including a mask for generating highlights.

14. A highlight microdot region of a drawing material comprising a thermally ablated drawing layer having drawing blocks and non-drawing blocks arranged to form a highlight microdot pattern on a single highlight microdot structure, wherein the single highlight microdot structure includes the highlight microdot mask element. A mask for a flexographic printing plate that generates highlights according to claim 13.

15. A mask for a flexographic printing plate that generates highlights, The highlight microdot mask element according to claim 4, An image having a highlight region with the aforementioned highlight microdot mask element, A mask for a flexographic printing plate that generates highlights, including a mask for generating highlights.

16. A light-transmitting ring formed by the plurality of drawing blocks, wherein the thickness of the ring is at least 1 / 4 pixel, the thickness of the orthogonal parts is at least 1 pixel, the ring height is in the range of 3 pixels to 8 pixels, and the ring width is in the range of 1 pixel to 8 pixels, The at least one internal opaque island formed by a plurality of non-drawable blocks within the light-transmitting ring, the internal opaque island having an island height of at least 1 pixel and an island width of at least 1 pixel, Includes, The opaque void region surrounds the light-transmitting ring. A mask for a flexographic printing plate that generates highlights according to claim 15.

17. A drawing material comprising a thermally ablated drawing layer having drawing blocks and non-drawing blocks arranged to form the image pattern, wherein the image pattern comprises at least one highlight mask region having a plurality of highlight dot regions that form a highlight pattern within the image pattern, the highlight mask region comprises a plurality of opaque regions of the thermally ablated drawing layer, each opaque region being one or more non-drawing blocks, the highlight mask region comprises a plurality of light-transmitting regions in the thermally ablated drawing layer, each light-transmitting region being one or more drawing blocks, and each highlight dot region comprising at least one highlight microdot mask element. A mask for a flexographic printing plate that generates highlights according to claim 13.

18. A light-transmitting ring formed by multiple drawing blocks, wherein the ring thickness is at least 1 / 4 pixel, the ring height is in the range of 4 pixels to 8 pixels, and the ring width is in the range of 2 pixels to 8 pixels. An internal opaque island formed by a plurality of non-drawable blocks within the light-transmitting ring, wherein the island width is at least 1 pixel and the island height is at least 2 pixels, An opaque void region surrounding the light-transmitting ring formed by multiple non-drawn blocks, A mask for a flexographic printing plate that generates the highlights according to claim 17, including the mask.

19. A method for forming a mask for a highlight generation flexographic printing plate, To provide a drawable material having a thermally ablated drawing layer, To provide an image pattern having at least one highlight region, wherein the highlight region includes a plurality of highlight microdot mask elements, and each highlight microdot mask element includes a highlight microdot pattern formed by the arrangement of a plurality of drawing regions and at least one opaque island. A method comprising drawing on the drawable material to form a mask image on the thermal ablable drawable layer, wherein the mask image includes the image pattern having at least one highlight region, the highlight region includes a plurality of highlight microdot mask elements, each highlight microdot mask element includes the microdot pattern formed by a plurality of drawing blocks in the thermal ablable drawable layer, the at least one opaque island in the thermal ablable drawable layer is formed by at least one non-drawable block, the drawing block and non-drawable block are arranged to jointly form the microdot pattern in the mask image, and the opaque void region formed by the plurality of non-drawable blocks surrounds the microdot pattern.

20. Each drawing block or non-drawing block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of approximately 10 to 11 micrometers. The width of each drawing area is at least 1 / 4 pixel. The height of each drawing area is at least 1 pixel. The width of the aforementioned microdot pattern is in the range of 2 pixels to 8 pixels. The height of the aforementioned microdot pattern is in the range of 3 to 8 pixels. The width of each internal opaque island is at least 1 / 4 pixel. The height of each internal opaque island is at least 1 pixel. The method according to claim 19.

21. This is a flexographic printing plate highlight microdot printhead, One or more raised regions arranged in a highlight microdot printing surface pattern, each raised region having at least one raised block that forms a printing surface, At least one internal recess formed by at least one recessed block within the highlight microdot printed surface pattern, wherein the arrangement of the one or more raised regions and the at least one recess defines the microdot printed surface pattern of the highlight microdot structure, A recessed void region surrounding the microdot pattern formed by a plurality of recessed blocks, wherein the recessed surface of each recessed block is lower than the printed surface, Flexographic printing plate highlight microdot printhead including.

22. Each raised or recessed block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of approximately 10 to 11 micrometers. The width of each raised region is at least 1 / 4 pixel. Each raised region has a height of at least 1 pixel. The width of the aforementioned highlight microdot printed surface pattern is in the range of 2 pixels to 8 pixels. The height of the aforementioned highlight microdot printed surface pattern is in the range of 3 pixels to 8 pixels. The width of each internal recess is at least 1 / 4 pixel. The height of each internal recess is at least 1 pixel. The flexographic printing plate highlight microdot print head according to claim 21.

23. The width of at least one raised region is at least 1 / 2 pixel, The height of at least one raised region is at least 2 pixels. The width of the aforementioned highlight microdot printed surface pattern is in the range of 2.5 pixels to 4 pixels. The height of the aforementioned highlight microdot printed surface pattern is in the range of 4 pixels to 6 pixels. The width of at least one internal recess is at least 1 / 2 pixel, At least one internal recess has a height of at least 2 pixels, and each recessed block is in contact with another recessed block by at least 1 / 4 pixel. The flexographic printing plate highlight microdot print head according to claim 22.

24. The one or more raised regions collectively form one or more outer boundary regions that form an outer boundary pattern, and each outer boundary region has at least one raised block that forms a printed surface. The at least one internal recess is formed by at least one recess within the outer boundary pattern, The recessed area surrounds the outer boundary pattern. The flexographic printing plate highlight microdot print head according to claim 21.

25. The flexographic printing plate highlight microdot printhead according to claim 24, wherein each raised or recessed block has a height of 1 pixel and a width of 1 / 4 pixel, and each pixel has a height and width of about 10 micrometers to about 11 micrometers.

26. The one or more outer boundary regions form a continuous annular boundary region in which each raised block contacts another raised block at least at an angle, or Multiple outer boundary regions form a discontinuous annular boundary region, wherein at least one gap, or recessed block, lies between two adjacent raised blocks of the multiple outer boundary regions. A flexographic printing plate highlight microdot print head according to claim 24.

27. The width of each outer boundary region is at least 1 / 4 pixel. The height of each outer boundary region is at least 1 pixel. The width of the outer boundary pattern is in the range of 2 pixels to 8 pixels. The height of the outer boundary pattern is in the range of 3 pixels to 8 pixels. The width of each internal recessed block is at least 1 / 4 pixel. The height of each internal recessed block is at least 1 pixel. A flexographic printing plate highlight microdot print head according to claim 25.

28. The width of at least one outer boundary region is at least 1 / 2 pixel, The height of at least one outer boundary region is at least 2 pixels. The width of the outer boundary pattern is in the range of 2.5 pixels to 4 pixels. The height of the outer boundary pattern is in the range of 4 pixels to 6 pixels. The width of at least one internal recessed block is at least 1 / 2 pixel, At least one internal recessed block has a height of at least 2 pixels, and each recessed block is in contact with another recessed block by at least 1 / 4 of a pixel. A flexographic printing plate highlight microdot print head according to claim 27.

29. One internal depression region within a continuous annular boundary region, One internal depression region within a discontinuous annular boundary region, Multiple internal depression regions within a continuous annular boundary region, or Multiple internal depression regions within a discontinuous annular boundary region A flexographic printing plate highlight microdot printhead according to claim 24, comprising at least one of the following.

30. One internally elevated region within a continuous ring-shaped boundary region, One internal elevation region within a discontinuous annular boundary region, Multiple internally raised regions within a continuous annular boundary region, or Multiple internally elevated regions within a discontinuous annular boundary region A flexographic printing plate highlight microdot printhead according to claim 24, comprising at least one of the following.

31. A total of at least 20 raised and recessed blocks, At least 16 raised blocks in the aforementioned pattern, At least four recessed blocks within the at least one recessed region, Includes at least one of the following: At least 20% of the total blocks are recessed blocks. The flexographic printing plate highlight microdot print head according to claim 21.

32. The one or more outer boundary regions collectively form a printed surface ring. An internal recessed region formed by a plurality of recessed blocks within the printed surface ring, comprising an internal recessed region having a width of at least 1 / 2 pixel and a height of at least 2 pixels, The recessed void region surrounds the printed surface ring. A flexographic printing plate highlight microdot print head according to claim 24.

33. It is a flexographic printing plate, The highlight microdot print head according to claim 21, An image pattern having a highlight region with the aforementioned highlight microdot print head, Flexographic printing plates including this.

34. A relief drawing material having a relief forming layer having raised blocks and recessed blocks arranged to form a highlight dot pattern on a single highlight microdot includes a highlight microdot region, the single highlight microdot includes the highlight microdot print head. The flexographic printing plate according to claim 33.

35. It is a flexographic printing plate, The highlight microdot print head according to claim 24, A flexographic printing plate including an image having a highlight region with the aforementioned highlight microdot print head.

36. A printed surface ring formed by multiple raised blocks, wherein the thickness of the ring is at least 1 / 4 pixel, the thickness of the orthogonal blocks is at least 1 pixel, the ring height is in the range of 3 pixels to 8 pixels, and the ring width is in the range of 1 pixel to 8 pixels. The at least one internal recessed region formed by a plurality of recessed blocks within the printed surface ring, the internal recessed region having a height of at least 1 pixel and a width of at least 1 pixel, Includes, The recessed void region surrounds the printed surface ring. The flexographic printing plate according to claim 35.

37. The relief drawing material includes a relief forming layer having raised blocks and recessed blocks arranged to form the image pattern, wherein the image pattern includes at least one highlight region having a plurality of highlight microdots that form a highlight pattern within the image pattern, each highlight microdot includes a plurality of recessed regions in the relief forming layer, each recessed region being one or more recessed blocks, and each highlight microdot includes a plurality of raised regions in the relief forming layer, each raised region being one or more raised blocks, and each of the raised blocks of the highlight microdot has a printed surface. The flexographic printing plate according to claim 33.

38. A printed surface ring formed by a plurality of raised blocks, wherein the thickness of the ring is at least 1 / 4 pixel, the height of the ring is in the range of 4 pixels to 8 pixels, and the width of the ring is in the range of 2 pixels to 8 pixels. The internal recessed region is formed by a plurality of recessed blocks within the printed surface ring, and the internal recessed region has a width of at least 1 pixel and a height of at least 2 pixels. The recessed void region surrounds the printed surface ring and is formed by a plurality of recessed blocks. The flexographic printing plate according to claim 37.

Images