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    • 专利摘要:
    PHOTOSENSITIVE RESIN LAMINATE AND THERMAL TREATMENT OF THE SAME. A photocurable printing plate comprising a backing layer having a photocurable layer disposed on it, a barrier layer disposed on the photocurable layer, and a layer of laser ablative mask disposed on top of the barrier layer. The method includes the steps of (1) imagining at least one polymerizable photo layer by ablating the laser ablative mask layer to create the embossed pattern on the photocurable printing plate and (2) exposing the printing plate to actinic radiation through the barrier layer and the mask layer to selectively crosslink the portions of the photocurable layer, thereby creating the embossed pattern, (3) developing the printing plate to remove the barrier layer, the ablative mask layer a laser and the uncured portions of the photocurable layer, as well as revealing the embossed pattern. The method can also be used with an analog sheet production process that uses a negative, rather than an ablative mask layer.
    公开号:BR112013022951B1
    申请号:R112013022951-9
    申请日:2012-03-20
    公开日:2020-10-27
    发明作者:Ryan W. Vest；David A. Recchia；Timothy Gotsick
    申请人:Macdermid Graphics Solutions, Llc.；
    IPC主号:
    专利说明:

    Field of the Invention
    [001] The present invention commonly refers to methods of processing resin laminates to produce flexographic elements of embossed image printing in order to optimize printing. Background of the Invention
    [002] Flexographic printing plates are embossed plates with image elements mounted on top of open areas. Generally, the sheet is a little soft, and flexible enough to wrap around a printing cylinder, and durable enough to print over a million copies. Such plates offer a number of advantages for the printer, based mainly on their durability and the ease with which they can be manufactured.
    [003] Flexography is commonly used for production in large quantities. Flexography is used to print on a variety of substrates, such as paper, paperboard, corrugated cardboard, films, sheets and laminates. Newspapers and grocery bags are relevant examples. Rough surfaces and elastic films (strecht films) can only be printed using flexography for economic reasons. Corrugated cardboard generally includes a corrugating medium, which is usually a layer of pleated or multi-groove cardboard, called a "flute", which is adjacent to a smooth paper or paper-like layer called a "coating" "{liner). The typical manufacture of corrugated cardboard is composed of a layer of flute between two layers of coating. Other embodiments can include multiple layers of flute and / or coating. The interlaced flute layers provide structural rigidity to the corrugated board. Since corrugated cardboard is used as packaging and in the form of boxes and containers, the coating layer that forms an outer surface of corrugated cardboard is often printed with the package identification information. The outer covering layer often has slight depressions due to the irregular support of the underlying flute layer.
    [004] A problem that can be encountered while printing on corrugated cardboard substrates is the occurrence of a printing effect known as "flute" (fluting) (which is also known as "banding" or "streaking" ( striping) or '' washboarding ''). The flute can occur when printing the coating on the outer surface of the corrugated cardboard, after the corrugated cardboard has been assembled. The flute effect is visible in dark print regions, that is, in higher density bands, alternating with light print regions, that is, in light density bands, which corresponds to the underlying corrugation structure of the corrugated board. . Dark printing occurs where the upper portions of the interspersed pleated structure support the printing surface of the coating. The fluted effect may be apparent in areas with a printed image that has tones or hue values (where the areas with ink represent a fraction of the total area), as well as in areas with the printed image (where the ink coverage is more complete). This fluted effect is usually more pronounced due to the shape of the dots produced by the digital process when printing with a flexographic printing element is produced by a digital workflow process. In addition, increasing the printing pressure does not eliminate flutes, and increasing the pressure can damage the corrugated board substrate. Therefore, other methods are needed to reduce flute when printing on corrugated substrates.
    [005] A typical flexographic printing plate, such as the one delivered by the manufacturer, is a multilayered article comprising, in order, a support, or a support layer, one or more unexposed photocurable layers; and, optionally, a protective layer or sliding film, and often a protective cover sheet.
    [006] The backing sheet or backing layer provides support for the plate. The backing sheet, or backing layer, can be formed from a transparent or opaque material, for example, paper, cellulose film, plastic, or metal. Preferred materials include sheets made from synthetic polymeric materials, such as polyesters, polystyrene, polyolefins, polyamides, and the like. Generally, the most widely used backing layer is a flexible polyethylene terephthalate film. The backing sheet may optionally comprise an adhesive layer for the more secure fixation of the photocurable layer (s). Optionally, an anti-halo layer can also be provided between the backing layer and one or more photocurable layers. The anti-halo layer is used to minimize the halo caused by the dispersion of UV light within the unimagined areas of the photocurable resin layer.
    [007] The photocurable layer (s) may include any of the known photopolymers, monomers, initiators, reactive or non-reactive diluents, fillers and pigments. The term "photocurable" refers to a composition that undergoes polymerization, crosslinking, or any other polymerization or curing reaction in response to actinic radiation, resulting in the fact that the unexposed parts of the material can be selectively separated and removed from exposed (cured) portions to form a relief or three-dimensional pattern of cured material. Preferred photocurable materials include an elastomeric compound, an ethylenically unsaturated compound having at least one terminal ethylene group, and a photoinitiator. Exemplary photocurable materials are described in European Patent Application No. 0 456 336 A2 and 0 640 878 A1 to Gross, et al., British Patent No. 1,366,769, US Patent No. 5,223,375 to Berrier, et al. , US Patent No. 3,867,153 to MacLahan, US Patent No. 4,264,705 to Allen, US Patent No. 4,323,636, 4,323,637, 4,369,246 and 4,423,135 all to Chen, eta /., US Patent No. 3,265,765 to Holden et al., US Patent No. 4,320,188 to Heinz et al., US Patent No. 4,427,759 to Graetzmacher, et al., US Patent No. 4,622,088 to Min, and Patent US No. 5,135,827 by Bohm et al., The materials of each of these documents being incorporated herein in their entirety as a reference. More than one photocurable layer can be used.
    [008] Photocurable materials are generally cross-linked (cured) and hardened by means of radical polymerization in at least some region of the actinic wavelength. As used herein, actinic radiation is radiation capable of polymerizing, crosslinking or curing the photocurable layer. Actinic radiation includes, for example, amplified (e.g., laser) and non-amplified light, particularly in the regions of the violet and ultraviolet wavelengths. A frequently used source of actinic radiation is a mercury arc lamp, although other sources are generally known to those skilled in the art.
    [009] The sliding film is a thin layer, which protects the photopolymer from dust and increases its ease of handling. In the conventional plate making process ("analog"), the sliding film is transparent to UV light. In this process, the printer removes the cover sheet from the plate's printing plate, and places a negative on top of the sliding film layer. The plate and the negative are then subjected to intense exposure to UV light through the negative. The areas exposed to light are cured or hardened, and the unexposed areas are removed (developed) to create the embossed image on the printing plate.
    [0010] In a "digital" or "direct to plate" plate production process, a laser is guided by an image stored in an electronic data file, and is used to create a negative in situ. digital mask layer (ie laser ablative), which is generally a sliding film that has been modified to include a radiation-opaque material. The portions of the laser ablative layer are then ablated by exposing the adhesive layer to laser radiation at a selected wavelength and laser power. Examples of laser ablative layers are disclosed, for example, in US Patent No. 5,925,500 to Yang et al. and US Patent Nos. 5,262,275 and 6,238,837 by Fan, the materials of each of these documents being incorporated herein in their entirety as a reference.
    [0011] After applying the image, the photosensitive printing element is developed to remove the unpolymerized portions of the layer of photocurable material and reveal the embossed reticulated image on the cured photosensitive printing element. Common development methods include washing with water or various solvents, often using a brush. Other possibilities for development include the use of an air or heating knife plus a blotter (ie, thermal development). Thermal development has the advantage that it does not require an additional drying step after development and therefore provides the ability of the printing plate process to be faster.
    [0012] The thermal development process works by processing the photopolymer printing plates by heating; and the differential melting temperature between the cured and uncured photopolymer is used to develop the imaging. The basic parameters of this process are known, as described in US Patent Nos. 7,122,295, 6,773,859, 5,279,697, 5,175,072 and 3,264,103 and in Patents WO 01/88 615, WO 01/18 604 and EP 1 239 329, whose teachings of each of these are incorporated here in their as a reference. These processes allow the elimination of the development solvents and the long drying times of the plates necessary to remove the solvent. The speed and efficiency of these processes allow their use in the manufacture of flexographic printing plates for newspapers and other publications, where delivery times and high productivity are important.
    [0013] So that the printing plates can be thermally developed, the composition of the photopolymer must be such that there is no substantial difference in the melting temperature between the cured and uncured polymer, as it is precisely this difference that allows the creation of an image on the photopolymer when heated. The cured photopolymer (ie the portions of the photopolymer that have not come into contact with actinic radiation) melts or softens substantially while the cured photopolymer remains intact and solid at the chosen temperature. Thus, the melting temperature difference allows the uncured photopolymer to be selectively removed, thus creating the desired image.
    [0014] Thereafter, the uncured photopolymer can be softened and / or melted and removed. In most cases, the heated printing element is brought into contact with an absorbent material that absorbs or else removes the softened and / or fused uncured photopolymer. This removal process is often called "blotting".
    [0015] The resulting surface, after development, has a relief pattern, which reproduces the image to be printed and normally includes both solid areas and standardized areas containing a plurality of relief points. After the embossed image is developed, the embossed image printing element can be mounted on a press and printing starts.
    [0016] The shape of the dots and the depth of the relief, among other factors, affect the quality of the printed image. It is very difficult to print small graphic elements, such as dots, thin lines and even text using flexographic printing plates, while “open reverse text” and shadows. In the lightest areas of the image (commonly referred to as "highlighted") the density of the image is represented by the total area of dots in a halftone screen representation of a continuous tone image. For amplitude-modulated (AM) tracking, this involves shrinking a plurality of halftone dots located on a periodic grid fixed to a very small size, where the highlight density is represented by the area of the dots. For frequency modulated (FM) tracking, the size of the halftone dots is generally kept at some fixed value, and the number of dots placed randomly or pseudo-randomly represents the image density, in both cases, it is necessary print point sizes too small to properly represent the highlighted areas.
    [0017] Maintaining small points on flexo plates can be very difficult, due to the nature of the plate production process. In digital plate production processes that use a layer of UV-opaque mask, the combination of the mask and exposure to UV rays produces raised dots that are generally tapered in shape. The smallest points mentioned are likely to be removed during processing, which means that the ink is not transferred to these areas during printing (the point is not "kept" on the plate and / or the press). In addition, if the stitch survives processing, they end up being susceptible to damage to the press. For example, small dots often fold over and / or partially break during printing, either causing excess ink or no ink to be transferred.
    [0018] In addition, photocurable resin compositions typically cure through radical polymerization under exposure to actinic radiation. However, the curing reaction can be inhibited by molecular oxygen, which is normally dissolved in resin compositions, because oxygen functions as a radical scavenger. Therefore, it is desirable that the dissolved oxygen is removed from the resin composition before exposure in terms of the image so that the photocurable resin composition can be cured more quickly and evenly.
    [0019] Various methods of removing dissolved oxygen have been developed for use in the technique. For example, removal of dissolved oxygen can be accomplished by placing the photosensitive resin sheet in an atmosphere of inert gas, such as gaseous carbon dioxide or gaseous nitrogen, before exposure, in order to displace dissolved oxygen. A notable drawback to this method is that the device requires a large space, which ends up being inconvenient and complicated. In addition, as will be discussed in more detail below, this approach has not been found to be particularly effective for digitally developed elements that are thermally developed.
    [0020] Another approach is to subject the plates to a preliminary exposure (for example, "bump exposure") of actinic radiation. During collision exposure, a "pre-exposure" dose of low intensity actinic radiation is used to sensitize the resin before the plate is subjected to the main dose of high intensity actinic radiation. Collision exposure is applied to the entire area of the plate and is a short, low exposure dose that reduces oxygen concentration, inhibits the photopolymerization of the plate (or other printing element) and assists in the preservation of fine traces (ie , highlight points, fine lines, isolated points, etc.) on the finished board. However, the pre-sensitization stage can also result in the filling of shadow tones, thus reducing the range of halftone tones in the image.
    [0021] Exposure to bump exposure requires specific conditions that are limited to only sequestering dissolved oxygen, such as the exposure time, the intensity of irradiated light and the like. In addition, a preliminary selective exposition has already been proposed, as explained, for example, in US Patent Publication No. 2009 / 0.043.138 by Roberts etal., The material of which is incorporated herein in its entirety as a reference.
    [0022] Other efforts have involved special plate formulations, either alone or in combination with collision exposure, as described in US Patent No. 5,330,882 to Kawaguchi, the material of which is incorporated herein in its entirety as a reference, which suggests the use of a separate dye that is added to the resin to absorb actinic radiation at wavelengths of at least 100 nm removed from the wavelengths absorbed by the main photoinitiator. US Patent No. 4,540,649 to Sakurai, which is incorporated herein in its entirety as a reference, describes a photocurable composition containing at least one water-soluble polymer, a photopolymerization initiator and a N-methylol condensation reaction product acrylamide, N-methylol methacrylamide, N-alkyloxymethyl acrylamide or N-alkyloxymethyl acrylamide and a melamine derivative, which, according to the inventors, eliminates the need for conditioning by pre-exposure and produces a chemical and thermally stable plate.
    [0023] However, all of these methods are still deficient in the production of an embossed image printing element that has an upper point structure, especially when they are designed to print corrugated cardboard substrates. In addition, all of the methods described above also did not demonstrate the production of an embossed image printing element having a superior dot structure when the embossed image is subjected to a thermal development step.
    [0024] When carrying out development in the presence of solvent, the main consideration is whether or not the solvent may swell and disperse / dissolve the uncured photopolymer and associated barrier layers, in combination with the appropriate mechanical agitation, which results in a clean printing plate free of contaminants, surface defects, or other unwanted phenomena derived from the common solvent for the platemaking industry.
    [0025] On the contrary, the thermal development of the plates sometimes requires other considerations. It was previously believed that digital plates, when exposed by conventional means (ie, in the air), were interchangeable even when subjected to a solvent development process or to a thermal development process, using the same formulation based on resin. The analog thermal process proved to be more difficult, often requiring the use of a new sliding film or properties unique to the resin itself, such as the very high melt flow.
    [0026] Thus, there is a need for an improved process for preparing embossed image printing elements.
    [0027] There is also a need for a better embossed image printing element that comprises an improved embossed structure including print points that are configured for superior printing performance on various substrates.
    [0028] The present invention generally relates to a digital plate with dots of a controlled architecture beneficial for printing (ie flat top, sloping shoulders).
    [0029] The present invention also provides a means for exposing and processing an analog sheet using the same exposure technique. Summary of the Invention
    [0030] It is an object of the present invention to provide an improved method for the thermal development of embossed digital image printing elements.
    [0031] It is another object of the present invention to provide an improved method of thermal development of analog elements of embossed image printing.
    [0032] It is another object of the present invention to provide an improved method of developing an embossed image printing plate that produces printing points with a flat top and sloping shoulders.
    [0033] It is yet another object of the present invention to provide a method of imagining and developing embossed image printing elements that provide a good result when printing on corrugated cardboard substrates.
    [0034] It is another object of the present invention to produce an embossed image printing plate that reduces printing flutes when printing on corrugated cardboard substrates.
    [0035] It is another object of the present invention to create an embossed image printing element comprising print points that have an upper dot structure in terms of the printing surface, edge definition, shoulder angle, depth and height of the print. Score.
    [0036] It is another object of the present invention to provide a dot shape and a structure where the printing element is highly resistant when printing on a flute.
    [0037] It is yet another object of the present invention to control the surface roughness of the embossed image printing element.
    [0038] The inventors of this document have found that a characteristic of plates processed by thermal means is the greater surface roughness of both the solid areas and the tops of the points, as well as the floor of the plate. This is due to the fact that blotting is unable to remove all photopolymers during heat treatment. There is always a small amount of residual polymer that remains on the plate, both in the embossed elements and on the plate floor. The texture of the paper blotter is usually transferred to this remaining photopolymer. In the areas of the floor of the board, this distinctive pattern has only a cosmetic effect. However, for the embossed elements, this texture can be problematic. If the texture's roughness is excessive , can affect print quality by actually transferring the pattern to the surface to be printed, resulting in qualitative defects in printing, often described as mottling or pinholing, and the quantitative defect in printing which is the reduction density of the solid ink (SID). These defects generally degrade the quality of printed articles made from plates with excessive roughness, reducing o the vibration of colors and making it difficult to obtain consistent color reproduction.
    [0039] Some degree of surface roughness of the plate may be beneficial for printing performance, but excessive surface roughness can have the negative effects described above. The definition of “excessive” surface roughness of the plate varies depending on many factors, including the printed substrate, the characteristics of the ink, and the amount of ink used in each image. Generally, the inventors have found that the surface roughness of the plate below 2,000 nm (Ra) is necessary to achieve a good and uniform coverage of the solid paint, with a preferred surface roughness of the plate below 1,200 nm, and a surface roughness of the priority plate less than 800 nm.
    [0040] For these purposes, in a preferred embodiment, the present invention generally relates to a method of developing a photocurable printing plate to produce an embossed pattern comprising a plurality of embossed points, where the embossing plate Photocurable printing comprises a backing layer that has at least one photocurable layer disposed on it, a barrier layer on top of the photocurable layer, and a layer of laser ablative mask disposed on top of the barrier layer, where the method comprises the steps of: a) imagining at least one photocurable layer through the selective ablation of the laser ablative mask layer in order to create an image on the surface of the photocurable printing plate; b) exposing the printing plate to actinic radiation through the barrier layer and the mask layer to one or more sources of actinic radiation to selectively crosslink and cure portions of at least one photocurable layer, where at least one photocurable layer is crosslinked and cured in the portions not covered by the mask layer, thus creating the relief pattern; and c) developing the printing plate to remove the barrier layer, the laser ablative mask layer and the uncured portions of the photocurable layer, as well as revealing the embossed pattern; the presence of the barrier layer produces printing points with the desired characteristics, where the barrier layer has an oxygen diffusion coefficient of less than 6.9 x 10-9 m2 / sec and an optical transparency of at least 50 %.
    [0041] In another preferred embodiment, the present invention generally relates to a method of developing a photocurable printing plate to produce an embossed pattern comprising a plurality of embossed points, where the photocurable printing plate comprises a layer support that has at least one photocurable layer disposed on it and a barrier layer disposed on at least one photocurable layer, where the method comprises the steps of: d) placing a negative of a desired relief image on the part top of the barrier layer; e) exposing the printing plate to actinic radiation through the barrier layer and the negative to crosslink and selectively cure at least one photocurable layer, where at least one photocurable layer is crosslinked and cured in areas that are not covered by the negative, thus creating the desired embossed image, and f) developing the printing plate to remove the barrier layer and uncured portions of the photocurable layer and revealing the desired embossed image; the presence of the barrier layer results in printing points with the desired characteristics, where the barrier layer has an oxygen diffusion coefficient of less than 6.9 x 10'9 m2 / sec and an optical transparency of at least 50%. Brief Description of Drawings
    [0042] For a more complete understanding of the invention, the reference is in the following description made in conjunction with the attached figures, where: Figure 1 shows the measurement of the shoulder angle of the point (0).
    [0043] Figure 2 represents the settings of the relief image.
    [0044] Figure 3 illustrates a means of characterizing the flatness of the printing surface of a point, where p is the distance along the top of the point and rt is the radius of curvature along the surface of the point.
    [0045] Figure 4 illustrates a flexion point and its edge, where p is the distance along the top of the point. This is used to characterize the sharpness re: p, where re is the radius of curvature at the intersection of the shoulder and the top of the point. Detailed Description of the Invention
    [0046] The inventors of the present invention have found that the shape and structure of a printing point has a profound impact on the way it prints. This is especially true for embossed digital image printing elements. The inventors of the present invention have also determined that there are special considerations that must be addressed when using thermal development processes to provide an embossed surface that includes the embossed printing points with the sloping shoulders and flat tops.
    [0047] The inventors of the present invention have found that there is an advantage in reducing the impact of oxygen inhibition during sheet exposure, while simultaneously maintaining the physical properties necessary to produce high-quality thermally processed printing plates.
    [0048] The present invention generally relates to the application of a barrier layer on (i) the photopolymer surface between the laser ablative mask layer and the photopolymer layer or (ii) the photopolymer layer surface between the photopolymer layer and negative photoliths (phototools). The sheet is then processed to remove the uncured photopolymers, thereby producing an embossed printing sheet. The function of the barrier layer is to serve as a barrier to oxygen, which allows the change in the shape of the points formed on the printing plate. The result of using this barrier layer is the advantageous control of the polymerization mechanism in such a way that the following occurs: 1) The points are formed without the restriction effect of oxygen inhibition, resulting in flat tops and inclined shoulder angles; 2) The polymerization rate is controlled to the extent that the optimal reverse depth is maintained and the shoulder angles are not excessively enlarged; 3) The barrier layer minimizes the creation of excessive surface roughness during heat treatment, and 4) The barrier layer allows more effective heat treatment in a printed way than the existing sheet constructions today.
    [0049] The present invention uses the aforementioned advantages of the barrier layer as an oxygen barrier and combines them with the surprising discovery that plates comprising a barrier layer perform better in printing studies than standard plates treated, as well as those exposed in inert gas media, thus showing reduced spot gains and clean solids and reverse printing.
    [0050] In a preferred embodiment, the present invention generally relates to a method of developing a photocurable printing plate to produce an embossed pattern comprising a plurality of embossed points, comprising a backing layer that it has at least one photocurable layer disposed on it, a barrier layer on top of the photocurable layer, and an ablative laser mask layer disposed on top of the barrier layer, where the method comprises the steps of: a) imagining at least a photocurable layer by selective ablation of the laser ablative mask layer in order to create an image on the surface of the photocurable printing plate; b) exposing the printing plate to actinic radiation through the barrier layer and the mask layer to one or more sources of actinic radiation to selectively crosslink and cure portions of at least one photocurable layer, where at least one photocurable layer is crosslinked and cured in the portions not covered by the mask layer, thus creating the relief pattern; and c) developing the printing plate to remove the barrier layer, the laser ablative mask layer and the uncured portions of the photocurable layer, as well as revealing the embossed pattern; the presence of the barrier layer produces printing points with the desired characteristics, where the barrier layer has an oxygen diffusion coefficient of less than 6.9 x 10'9 m2 / sec and an optical transparency of at least 50 %.
    [0051] The desired geometric parameters of the print points are usually one or more of the steep shoulder angles, the flatness of the point surface, the sufficient depth of the relief between the points, sharpness of the border at the point where the upper part of the stitch transits to the stitch's shoulder, low surface roughness and their combinations. You can manipulate the shape resulting from the printing points to optimize printing using the methods described here.
    [0052] The inventors of the present invention have found that a particular set of geometric features defines a flex point shape that produces superior printing performance. These geometric parameters include, but are not limited to: (1) the flatness of the stitch surface, (2) the shoulder angle of the stitch, (3) the depth of the relief between the stitches, and (4) edge sharpness at the stitch where the top of the stitch transits to the stitch's shoulder. These geometric parameters are described in more detail in the related Patent Applications Nos. 12 / 571,523 by Reechia and 12 / 660,451 by Reechia et al., Whose subject matter for each of these documents is incorporated herein in its entirety as a reference. However, the use of these geometric parameters to optimize the print quality of the printing points produced in the thermal development processes has not been previously investigated.
    [0053] Firstly, it was found that the point shoulder angle is a good indicator of printing performance. The point shoulder is defined in Figure 1 as the angle 0 formed by the side and the upper part of the point. At the extreme, a vertical column would have a shoulder angle of 90 °, but in practice, most flexion points have an angle that is considerably less, often close to 45 ° than 90 °.
    [0054] The shoulder angle can also vary depending on the size of the stitches. Small points, for example, ranging from 1 to 15%, may have large shoulder angles, while larger points, for example, greater than about 15%, may have smaller shoulder angles. It is desirable that all points have the widest possible shoulder angle. In one embodiment, the desired characteristics comprise sloping shoulder angles and the shoulder angle of each of the plurality of points is such that the total shoulder angle is greater than about 50 °, preferably greater than about 70 °.
    [0055] There are two competing geometric constraints on the shoulder angle - stitch stability and print sensitivity. A large shoulder angle minimizes print sensitivity and produces the largest working window on the press, but at the expense of the point's stability and durability. However, a smaller shoulder angle improves the stability of the stitch, but makes the stitch more sensitive to printing on the press. As used herein, the point shoulder angle is the angle formed by the intersection of a horizontal line (or in parallel with the top of the point, depending on the shape of the point's point) tangent to the top of the point and a line representing the side wall of the adjacent point.
    [0056] In another embodiment, the desired characteristics include the planarity of the point surface. The planarity of the upper part of a point can be measured with the radius of curvature along the upper surface of the points, rz, as shown in Figure 3. Preferably, the upper surface of the point has a planarity where the radius of curvature of the upper part the point is greater than the total thickness of at least one layer of photocurable material, more preferably twice the thickness of at least one layer of photocurable material, and more than three times the total thickness of the layer of photocurable material. photopolymer. The planar surface of the point is preferred over the entire range of tones. The planar surfaces of the point are more preferable, even over the points in the highlight range (that is, 0 to 10% tonal).
    [0057] In yet another embodiment, the desired characteristic of the printing points is the lower surface roughness and the surface roughness of the upper part of the plurality of embossed printing points is less than about 2,000 nm, preferably less than about 1,250 nm, and, primarily, less than 800 nm.
    [0058] In another embodiment, the desired characteristic of the printing points is the sufficient depth of the relief between the points, and a relief of the point of the printing element is greater than about 9% of the total relief of the plate, preferably, greater than about 12% of the total relief of the plate. The relief of the plate is expressed as the distance between the floor of the plate and the top of a solid relief surface, as shown in Figure 2. For example, a 0.125 inch (3.175 mm) thick plate is normally manufactured so to have a relief of 0.040 inch (1.016 mm). However, the relief of the plate is usually much greater than the relief between the points in the tone patches (that is, the "point relief), which is a result of the narrow spacing of the points in the tonal areas. The low relief between the points in the tonal areas means that the points are structurally well supported, but it can cause problems during printing as the ink accumulates on the plate and eventually fills in the areas between the points, causing the overlap ( bridging) from the dot or dirty print.The inventors found that the deepest point of the relief can significantly reduce this problem, leading to longer printing with less operator interference, a capability that is often called "cleaner printing".
    [0059] In another embodiment, the desired characteristic is the sharpness of the border at the point where the upper part of the point transits to the shoulder of the point. It is generally preferred that the edges of the stitch are sharp and well defined. These well-defined margins of the points better separate the "printing" part from the "support" part of the point, allowing a more consistent contact area between the point and the substrate during printing. The edge sharpness can be defined as the ratio of r, the radius of curvature (at the intersection of the shoulder and the top of the stitch) of p, the width of the top of the stitch or the print surface, as shown in Figure 4 For a truly round-tipped dot, it is difficult to define the exact printing surface because there is really no common sense border, and the re: p ratio can approach 50%. However, a point with a sharp edge will have a very small value of re, and re: p would be approximately zero. In practice, it is preferred that a re: p is less than 5%, with a re: p less than 2% being most preferred.
    [0060] A wide variety of materials can serve as a barrier layer. Four qualities that the inventors have identified in the production of effective barrier layers include optical transparency, low thickness, inhibition of oxygen transport and the ability to preferentially develop the barrier layer without using solvents or heating. The inhibition of oxygen transport is measured in terms of a low oxygen diffusion coefficient. As noted, the oxygen diffusion coefficient of the oxygen barrier membrane is typically less than about 6.9 x 10'9 m2 / sec, more preferably less than about 6.9 x 10'10 m2 / sec , and primarily, less than about 6.9 x 10'11 m2 / sec.
    [0061] The most preferred oxygen barrier layer is clear films that minimize light scattering. Examples of materials that are suitable for use as a barrier layer include polyamides, polyvinyl alcohol, hydroxyalkyl cellulose, polyvinyl-pyrrolidinoπ, ethylene and vinyl acetate copolymers, amphoteric interpolymers, cellulose acetate butyrate, cellulose alkyl, butrial, cyclic rubbers , and combinations of one or more of the previous elements.
    [0062] The barrier layer should be as thin as possible. Preferred thicknesses of the barrier layer are about 1 to 100 microns, with a thickness of about 1 to about 20 microns being most preferred.
    [0063] The barrier layer must have sufficient optical transparency so that the membrane does not impair the absorption or diversion of the actinic radiation used to expose the photosensitive printing plate. As such, it is preferable that the barrier layer has an optical transparency of at least 50%, and, preferably, at least 75%.
    [0064] The barrier layer must be sufficiently impermeable to the diffusion of oxygen so that it can effectively limit the diffusion of oxygen in the photocurable layer during exposure to actinic radiation. The present inventors have determined that the aforementioned barrier layer materials, and in the aforementioned thicknesses, will substantially limit the diffusion of oxygen into the photocurable layer when used as described herein.
    [0065] Appropriate thermal development processes are generally well known to those skilled in the art. In one embodiment, the thermal development step comprises the steps of: d) softening the non-crosslinked polymer on the exposed and imaged surface of the printing element through contact of the exposed surface and imaged with an absorbent layer capable of absorbing the non-portions - reticulated from at least one layer of photocurable material that has been heated to a temperature between 40 ° C and 200 ° C, e) heat at least said layer of photocurable material to a temperature between 40 ° C and 200 ° C, thus allowing the non-crosslinked portions of at least one layer of photocurable material to contact the absorbent layer in order to be absorbed by said absorbent layer, and f) to remove said absorbent layer containing the non-absorbent portion. reticulate of at least one photocurable layer over which the embossed pattern is revealed.
    [0066] Materials and techniques for developing suitable solvents are also known in the art.
    [0067] In addition, the barrier layer can be used in an analog construction where a barrier layer is applied to a photopolymer resin layer. A negative is then placed over the barrier layer, and sheet production takes place through standard analog sheet production practices.
    [0068] More specifically, in another preferred embodiment, the present invention generally relates to a method of developing a photocurable printing plate to produce an embossed pattern comprising a plurality of embossed points, where the printing plate A photocurable layer comprises a backing layer that has at least one photocurable layer arranged on it and a barrier layer arranged on at least one photocurable layer, where the method comprises the steps of: g) placing a negative of an image in desired relief at the top of the barrier layer; h) exposing the printing plate to actinic radiation through the barrier layer and the negative to crosslink and selectively cure at least one photocurable layer, where at least one photocurable layer is crosslinked and cured in areas that are not covered by the negative, thus creating the desired embossed image, ei) developing the printing plate to remove the barrier layer and uncured portions of the photocurable layer and revealing the desired embossed image; the presence of the barrier layer results in the plurality of printing points with desired characteristics, where the barrier layer has an oxygen diffusion coefficient of less than 6.9 x 10'9 m2 / sec and an optical transparency of at least minus 50%.
    [0069] Finally, once the plates are submitted to development, the printing element of the embossed image is mounted on a printer's printing cylinder and printing begins.
    [0070] Thus, it can be seen that the method of making the relief image printing element described here produces an relief image printing element having a relief pattern comprising relief points to be printed which are configured for performance excellent printing. In addition, using the method described here, it is possible to make thermally developed plates, both digital and analog, that optimize the geometric characteristics of the embossed points in the resulting embossed image in order to produce a desired result.
    权利要求:
    Claims (13)
    [0001]
    1. Method for developing a photocurable printing plate to produce an embossed pattern comprising a plurality of embossed dots, CHARACTERIZED by the fact that the photocurable printing plate comprises a backing layer that has at least one photocurable layer disposed on it , a barrier layer at the top of the photocurable layer, and a layer of laser ablative mask arranged at the top of the barrier layer, the method comprises the steps of: a) imagining at least one photocurable layer through the selective ablation of layer of the ablative laser mask to create an image; b) exposing the printing plate to actinic radiation through the barrier layer and the mask layer to one or more sources of actinic radiation to selectively crosslink and cure portions of at least one photocurable layer, wherein at least one photocurable layer it is cross-linked and cured in the portions not covered by the mask layer, thus creating the pattern in relief; and c) developing the printing element to remove the barrier layer, the laser ablative mask layer and the uncured portions of the photocurable layer and reveal the embossed pattern; wherein the barrier layer has an oxygen diffusion coefficient of less than 6.9 x 10'9 m2 / sec and an optical transparency of at least 50%.
    [0002]
    2. Method, according to claim 1, CHARACTERIZED by the fact that the print points have one or more characteristics selected from: a) steep shoulder angles, in which the shoulder angle of each one of the plurality of points is such that the total shoulder angle is greater than about 50 °; b) planarity of the point surface, wherein the planarity of an upper surface of the points is such that the radius of curvature of the upper surface of the points, rt, is greater than the total thickness of the at least one layer of photocurable material; c) sufficient depth of the relief between the points, where the relief of the point is greater than about 9% of the total relief of the plate; d) sharpness of the border at the point where the upper part of the point transits to the shoulder of the point, where the ratio of re: p is less than 5%; and e) low surface roughness, where the surface roughness of the upper part of the plurality of relief points is less than about 700 nm.
    [0003]
    3. Method according to claim 2, CHARACTERIZED by the fact that the at least one characteristic comprises steep shoulder angles.
    [0004]
    4. Method according to claim 3, CHARACTERIZED by the fact that the shoulder angle of each of the plurality of points is such that the total shoulder angle is greater than about 70 °.
    [0005]
    5. Method, according to claim 2, CHARACTERIZED by the fact that the at least one characteristic comprises the planarity of the point surface.
    [0006]
    6. Method according to claim 2, CHARACTERIZED by the fact that the at least one characteristic comprises the low surface roughness, optionally in which the surface roughness of the upper part of the plurality of embossed printing points is less than about 800 nm.
    [0007]
    7. Method, according to claim 2, CHARACTERIZED by the fact that the at least one characteristic comprises sufficient depth of the relief between the points, optionally in which the relief of the point of the printing element is greater than about 12% of the relief total plate.
    [0008]
    8. Method, according to claim 2, CHARACTERIZED by the fact that the at least one characteristic comprises sharpness of the edges of the points, optionally in which the re: p ratio is less than 2%.
    [0009]
    9. Method, according to claim 1, CHARACTERIZED by the fact that the barrier layer is selected from the group consisting of polyamides, polyvinyl alcohol, hydroxyalkyl cellulose, polyvinyl-pyrrolidinone, ethylene and vinyl acetate copolymers, interpolymers amphoterics, cellulose acetate butyrate, alkyl cellulose, butrial, cyclic rubbers, and combinations of one or more of the above elements.
    [0010]
    10. Method according to claim 1, CHARACTERIZED by the fact that the barrier layer has a thickness of about 1 to 100 microns, optionally wherein the barrier layer has a thickness of about 1 to about 20 microns .
    [0011]
    11. Method according to claim 1, CHARACTERIZED by the fact that the barrier layer has an optical transparency of at least about 75%.
    [0012]
    12. Method, according to claim 1, CHARACTERIZED by the fact that the development stage of the printing plate comprises: a) softening the non-crosslinked polymer on the exposed and imaged surface of the printing plate through contact of the exposed surface and imaged with an absorbent layer capable of absorbing the non-cross-linked portions of at least one layer of photocurable material that has been heated to a temperature between 40 ° C and 200 ° C; b) heating said at least one layer of photocurable material to a temperature between 40 ° C and 200 ° C and allowing the non-crosslinked portions of at least one layer of photocurable material to contact the absorbent layer to be absorbed by said absorbent layer; and c) removing said absorbent layer containing the non-crosslinked portion of at least one photocurable layer, on which the embossed pattern is revealed.
    [0013]
    13. Method, according to claim 1, CHARACTERIZED by the fact that the printing plate is not imaged in an inert environment.
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    同族专利:
    公开号 | 公开日
    WO2012145111A1|2012-10-26|
    EP2699964A4|2014-11-05|
    BR112013022951A2|2016-12-06|
    JP2015179284A|2015-10-08|
    US20120270156A1|2012-10-25|
    US8551688B2|2013-10-08|
    CA2830267C|2016-05-17|
    CN103477281B|2016-08-17|
    JP2014512576A|2014-05-22|
    JP5913567B2|2016-04-27|
    RU2013151128A|2015-05-27|
    EP2699964A1|2014-02-26|
    US20140004466A1|2014-01-02|
    EP2699964B1|2019-03-06|
    ES2720855T3|2019-07-25|
    CA2830267A1|2012-10-26|
    RU2554935C2|2015-07-10|
    US9223218B2|2015-12-29|
    JP6181704B2|2017-08-16|
    CN103477281A|2013-12-25|
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    法律状态:
    2018-04-03| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2018-08-28| B25D| Requested change of name of applicant approved|Owner name: MACDERMID GRAPHICS SOLUTIONS, LLC (US) |
    2019-07-16| B06T| Formal requirements before examination|
    2020-04-07| B09A| Decision: intention to grant|
    2020-10-27| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 20/03/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US13/091,466|US8551688B2|2011-04-21|2011-04-21|Photosensitive resin laminate and thermal processing of the same|
    US13/091.466|2011-04-21|
    PCT/US2012/029766|WO2012145111A1|2011-04-21|2012-03-20|Photosensitive resin laminate and thermal processing of the same|
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