Releasable flexographic printing mask with laser thermal imaging film containing lecithin

Abstract

A mask element for flexographic printing is provided. The mask element may be used to prepare a mask having a mask image. The mask element may include: a transparent polymer carrier sheet; a substrate layer on the transparent polymeric carrier sheet, wherein the substrate layer comprises lecithin in a polymeric binder; and an imaging layer on the base layer, where the imaging layer includes a non-silver halide thermally ablatable material comprising an ablatable polymeric binder and a colorant (e.g., carbon black) and optionally an infrared (IR) dye. In some aspects, the mask element also includes a transparent topcoat layer on the imaging layer. The mask may include an imaging region in an imaging layer and a non-imaging region in the imaging layer.

Description

Background Technology

[0001] field: This disclosure relates to a lecithin-containing thermal imaging film for flexographic printing masks, and methods of manufacturing and using the same. More specifically, this disclosure relates to a thermal imaging film containing lecithin before or after having mask elements formed therein, wherein the lecithin improves the peelability of the thermal imaging film from the imaged relief forming layer of the flexographic printing plate.

[0002] Description of related technologies: Previously, photosensitive materials have been combined with masks that can be used to form embossed images in flexographic printing plate precursors. However, the optical properties of the materials used for the masks may alter the embossed image formed by the photosensitive embossing layer, which may not be optimal. Typically, masks have adhesive properties to the photosensitive embossing layer, resulting in low efficiency in mask removal. This loss of efficiency may be attributed to prolonged processing time of the embossing layer or to the loss of the imaged embossing layer due to mask residue (e.g., mask portions) remaining on the embossing layer. Therefore, optimizing the physical properties of the mask can improve the removal of the mask from the irradiated layer of the embossing layer on the flexographic printing plate.

[0003] Photosensitive embossing materials having embossing materials or photosensitive layers are known in the art. Important advances in the art and available materials for manufacturing flexographic embossed images are described in U.S. Patent No. 8,142,987 (Ali et al., hereinafter referred to as US '987). US '987 describes suitable mask element precursors, photosensitive materials for embossing layers, and processes and apparatus for forming mask elements from mask precursors and ultimately forming embossed images from photosensitive embossing precursor materials.

[0004] Typically, a mask is placed in close contact with the photosensitive embossing precursor material using a lamination apparatus or vacuum drawdown, or both, and subjected to overall exposure to photochemical radiation (e.g., ultraviolet (UV) radiation) to cure the photosensitive composition in unmasked areas of the embossing precursor material, thereby forming a negative image of the mask in the photosensitive embossing precursor. The mask can then be removed by peeling, and uncured areas on the embossing material can be removed using a developing process. After drying and UV curing, the resulting imaged embossing precursor has an embossed image suitable for flexographic or letterpress printing operations. However, any residue of a portion of the mask on the imaged embossing precursor can cause problems and may render the embossed image unusable.

[0005] Advances in mask element precursors are described in U.S. Patent No. 7,799,504 (Zwadlo et al.). Other useful mask element precursors and their application processes are described in U.S. Patent Nos. 8,198,012 (Zwadlo et al.), 8,945,813 (Kidnie), and 9,250,527 (Kidnie). Advances in photosensitive materials are described in US No. 2019 / 0258154 (Kidnie).

[0006] Previously, methods have been used to incorporate low surface energy monomers into the imaged relief forming layer during the polymerization process to improve peel strength.

[0007] The claimed subject matter is not limited to addressing any shortcomings or implementations operating only in environments such as those described above. This background is provided merely to illustrate instances where this disclosure may be applied. Summary of the Invention

[0008] In some embodiments, a mask element for flexographic printing may include: a substrate, typically referred to as a carrier sheet; a polymer layer on the substrate, typically referred to as a base layer, wherein the polymer layer includes lecithin; and a non-silver halide thermally ablative imaging layer containing a colorant (e.g., carbon black) on the polymer layer. Optionally, the ablative imaging layer may contain at least one infrared absorbing material in a thermally ablative polymer binder. The substrate may be a transparent polymer carrier sheet. The polymer layer may be a base layer on the substrate, wherein the base layer may also be referred to herein or in the cited references as a base layer. The lecithin-containing polymer layer may include non-crosslinked nitrocellulose or other similar materials. The non-silver halide thermally ablative imaging layer may be an imaging layer having an ablative material (e.g., non-crosslinked nitrocellulose), a colorant (e.g., carbon black), and an infrared (IR) dye (e.g., selective for IR light absorption) (e.g., without silver halide). The mask element may be a mask precursor for preparing a mask having a mask image. In some aspects, the mask element may also include a transparent overcoat layer on the imaging layer.

[0009] In some embodiments, the mask element may include a sufficient amount of lecithin to reduce the peeling force required to remove the mask from the imaged relief-forming layer. The sufficient amount of lecithin may be from about 0.1% to about 25% by weight of the substrate layer, or from about 5% to about 20% by weight of the substrate layer. The lecithin may be derived from a powder or liquid source. In some aspects, the lecithin is uniformly distributed throughout the substrate layer. The lecithin is a mixture of at least two glycerophospholipids, indicating that it is lecithin. Therefore, the lecithin may include at least two of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, or phosphatidic acid.

[0010] In some embodiments, the polymer substrate may be free of IR dyes. That is, the substrate may be free of IR dyes that selectively absorb UV light, such IR dyes absorbing IR light better than visible or UV light.

[0011] In some implementations, the imaging layer may be free of ultraviolet (UV) dyes. That is, the imaging layer may be free of UV dyes that selectively absorb UV light, such UV dyes absorbing UV light better than visible or IR light.

[0012] In some implementations, the imaging layer does not contain particles, such as thermally ablationable particles or non-thermally ablationable particles (non-thermally ablationable particles).

[0013] Some embodiments of the mask element can have different configurations. In some aspects, the substrate layer is free of UV dyes. In some aspects, the substrate layer optionally contains 0-10% IR dyes. In some aspects, at least one plasticizer may be present in the substrate layer. The plasticizer in the substrate layer may be present in an amount from about 1% to about 30%. In some aspects, carbon black in the imaging layer may be present in an amount from about 30% to about 70%. In some aspects, infrared dyes in the imaging layer may be present in an amount from about 0.1% to about 15%. Furthermore, at least one plasticizer may be present in the imaging layer. The plasticizer in the imaging layer may be present in an amount from about 1% to about 30%. In some aspects, the plasticizer in the substrate layer may be selected from ATBC, Alchemix, PEG-1000, and combinations thereof. In some aspects, the plasticizer in the imaging layer may be selected from ATBC, PEG-1000, and combinations thereof. In some aspects, the plasticizer may be a non-phthalate plasticizer.

[0014] In some embodiments, the mask may include a mask element in which at least one mask image is formed. The mask may include an imaging region in the imaging layer, wherein the imaging region has an optical aperture that is substantially free of carbon black and its non-crosslinked nitrocellulose. The mask may include a non-imaging region in the imaging layer, wherein the non-imaging region contains non-crosslinked nitrocellulose, carbon black, and infrared dye, and optionally a plasticizer. The optical density of the mask in the non-imaging region may be greater than 3.0, while the optical density in the fully ablated imaging region may be less than about 0.20.

[0015] In some embodiments, a method of manufacturing a mask element may include: forming a transparent polymer carrier sheet; forming a substrate layer on the transparent polymer carrier sheet; and forming an imaging layer on the substrate layer. The method may include forming a transparent topcoat layer on the imaging layer. The method may include forming a substrate layer comprising at least one plasticizer. The method may include forming an imaging layer comprising at least one plasticizer.

[0016] In some embodiments, a method of manufacturing a mask may include: providing a mask element of one embodiment, having no imaging regions in its imaging layer; and imaging the mask element with infrared light to form imaging regions in the imaging layer. In some aspects, the imaging process ablates carbon black, non-crosslinked polymer binders, and other materials in the imaging layer to form optical apertures that present the mask image. In some embodiments, a method of manufacturing a mask for flexographic printing may include exposing a thermally ablation imaging layer to infrared radiation to selectively ablate regions in the thermally ablation imaging layer. A mask image is formed in the thermally ablation imaging layer, wherein the mask image includes regions of the thermally ablation imaging layer and regions of the thermally ablation imaging layer that have been thermally ablated.

[0017] In some implementations, a mask image is formed within the imaging layer. The mask image includes regions of the thermally ablationable imaging layer and regions of the thermally ablationable imaging layer that have been thermally ablated.

[0018] In some embodiments, the embossing assembly may include an embossing precursor and a mask element for flexographic printing. The mask may include: a transparent carrier sheet substrate; a polymer base layer on the substrate, optionally having a plasticizer and / or at least one first infrared absorbing material; a thermally ablation imaging layer on the polymer base layer, having at least one second infrared absorbing material (e.g., non-carbon black), a colorant (e.g., carbon black) in a thermally ablation polymer binder (e.g., non-crosslinked nitrocellulose), and optionally a plasticizer. A mask image is formed in the thermally ablation imaging layer. The mask image includes areas of the thermally ablation imaging layer and areas of the thermally ablation imaging layer that have been thermally ablated.

[0019] In some embodiments, a method of manufacturing an embossing assembly may include: placing a mask element on the embossing surface of the embossing layer; and forming a complete optical contact between the mask element and the embossing surface. In some aspects, the method may include at least one of: laminating a mask element to the embossing surface; or coupling a mask element to the embossing surface by vacuum suction.

[0020] In some embodiments, a method of creating an embossed image in an embossing assembly may include: providing an embossing assembly according to one embodiment; exposing an embossing layer of an embossing precursor to curing UV radiation through a mask element to form an imaged embossing layer, wherein in the imaged embossing layer, UV-exposed areas form aggregated areas, while unexposed areas form non-aggregated areas; removing the mask element from the imaged embossing layer; and developing the imaged embossing layer by removing the non-aggregated areas in the imaged embossing layer, thereby forming an embossed image element having an embossed image.

[0021] In some embodiments, a method of manufacturing an embossing assembly may include: providing a mask element according to an embodiment; providing an embossing layer according to an embodiment; placing the top surface of the mask element on the embossing surface of the embossing layer; and forming a complete optical contact between the mask element and the embossing surface. In some aspects, the method may include laminating the mask element to the embossing surface. In some aspects, the method may include coupling the mask element to the embossing surface by vacuum suction.

[0022] In some embodiments, a method of creating an embossed image in an embossing assembly may include: providing an embossing assembly according to an embodiment; exposing an embossing layer to curing UV radiation through a mask element to form an imaged embossing layer, wherein UV-exposed areas in the imaged embossing layer form polymerized regions, while unexposed areas form non-polymerized regions; removing the mask element from the imaged embossing layer; and developing the imaged embossing layer by removing the non-polymerized regions in the imaged embossing layer, thereby forming an embossed image element having an embossed image (e.g., without non-polymerized regions). In some aspects, the method may include polymerizing at least one photopolymerizable monomer at the embossed surface of the embossed image of the embossed image element.

[0023] The above overview is illustrative only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent from the accompanying drawings and the following detailed description. Brief description of the attached diagram

[0025] The foregoing and following information, as well as other features of this disclosure, will become more apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. It should be understood that these drawings depict only a few embodiments according to this disclosure and should not be construed as limiting its scope, which will be described in a more specific and detailed manner using the drawings.

[0026] Figure 1A This is a schematic cross-sectional view of a mask precursor according to one embodiment of the present invention, and shows the incident infrared radiation used to manufacture the mask element.

[0027] Figure 1B It is by Figure 1A A schematic cross-sectional view of one embodiment of the mask element formed by the mask precursor shown.

[0028] Figure 1C This is a cross-sectional schematic diagram of an embossed image forming assembly according to an embodiment of the present invention, the assembly comprising, as shown below... Figure 1B The mask element shown is in complete optical contact with the relief forming precursor.

[0029] Figure 1D It uses incident UV radiation through Figure 1B The diagram shows a cross-sectional schematic of one embodiment of a mask element forming an imaged relief forming precursor.

[0030] Figure 1E Is Figure 1D A cross-sectional schematic diagram of one embodiment of an embossed image element provided after imaging and undergoing appropriate development processes to remove unexposed areas in the UV-sensitive layer of the imaged embossing precursor.

[0031] Figure 2 This includes data showing the peel force required for Examples 1-6 compared to comparative examples.

[0032] The elements and components in the figure can be arranged according to at least one embodiment described herein, and such arrangement can be modified by those skilled in the art based on the disclosure provided herein.

[0033] Detailed description

[0034] In the following detailed description, reference is made to the accompanying drawings, which form part of this document. In the drawings, similar symbols generally identify similar components unless the context otherwise requires. The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments and modifications may be utilized without departing from the spirit or scope of the subject matter set forth herein. It will be readily understood that aspects of this disclosure, as generally described and illustrated herein, can be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are expressly contemplated herein.

[0035] In summary, this technology provides an improved mask for UV exposure of curable materials in an embossing stencil and allows for easier peeling from the stencil. Compared to other masks, the mask of this technology has improved peeling capability without damaging the embossing stencil. Easier peeling also allows for more consistent peeling, thus reducing defects. Consequently, the resulting embossing exhibits higher quality and better performance.

[0036] In some embodiments, a mask element for flexographic printing is provided. This mask element can be used to prepare a mask having a mask image. The mask element may include: a transparent polymer carrier sheet; a base layer on the transparent polymer carrier sheet, wherein the base layer comprises an adhesive, lecithin, and optionally a plasticizer; and an imaging layer on the base layer, wherein the imaging layer comprises a thermally ablationable material formed from a polymeric adhesive containing a colorant. Optionally, the colorant may be carbon black. Furthermore, the imaging layer may include an infrared (IR) dye and optionally a plasticizer. In some aspects, the mask element also includes a transparent top coating on the imaging layer.

[0037] The Kodak Flexcel NX system uses Flexcel NX TIL-R thermal imaging film (US 8,945,813) to manufacture flexographic printing plates. However, the use of TIL-R requires a longer main UV exposure time (e.g., 14 min for a 30 mW UV light source or 22 min for a 20 mW light source) to produce high-resolution printing plates (e.g., retaining small highlight dots). Alternatively, TIL thermal imaging film (US 10,768,520) can be used, which has a UV exposure time of 12 min (e.g., 21 J / cm²) when using a 30 mW light source. 2 Long master UV exposure times are detrimental to the productivity of the plate-making process. Therefore, shorter master UV exposure times (e.g., 10 to 12 min for a 30 mW UV light source) obtained using the improved mask described in this paper are highly desirable for improving plate-making efficiency.

[0038] Compared to the ablation of the TIL-R mask precursor, the composition of this mask can provide highly efficient ablation of the mask precursor, as evidenced by the optical density (OD) of the masked portion of the mask of the present invention being between about 3.5 and about 3.8.

[0039] OD is measured by an X-Rite transmission densitometer and is defined by the following equation: OD = -log T λ = -log [(%T λ ) / 100] In some embodiments, the improved mask has an optical density between 3.5 and 3.8 in the non-imaging region and less than or about 0.20 in the fully ablated imaging region. For example, the OD of the fully ablated imaging region in the mask can be less than or about 0.18, more preferably less than or about 0.15, more preferably less than or about 0.13, and even more preferably less than or about 0.12. Specific examples include improved masks with an OD range of about 0.11 to about 0.13. The percentage of UV light transmittance in the ablated region can be about 70%-80%, or about 74%-77%, or about 75%. The OD range of the non-imaging region can be 3.5 to 3.8. The higher optical OD of the non-imaging region of the mask prevents image formation in unwanted areas. For example, an OD of 3.0 corresponds to a transmittance of only 0.1%.

[0040] In some implementations, the improved mask can also have shorter exposure times, such as shorter energy exposure times, for example, a reduced number of joules per square centimeter. Previous masks could have 24 J / cm². 2 UV exposure, while the improved mask can have 17 J / cm 2 Up to 19 J / cm 2 And up to 21 J / cm 2 UV exposure.

[0041] In some embodiments, the improved mask of the present invention also provides excellent stability of the imaging film under low to high humidity conditions. This is ideal for the transport, storage, and loading and unloading of the imaging film into imaging devices to manufacture the mask. Therefore, the improved mask can exhibit excellent resistance to edge curling under both low and high humidity conditions.

[0042] In addition, the improved mask can provide a suitable flexographic printing plate with 0.4% dot coverage at 200 lpi.

[0043] Masks and mask precursors

[0044] This technology provides an improved thermal imaging film, referred to as a mask precursor or mask element before imaging and as a mask after imaging. Specifically, the thermal imaging film (TIF) comprises an imaging layer that is imaged upon exposure to infrared light. The imaging layer may be referred to as a non-silver halide thermally ablation imaging layer because it does not contain silver halide and is thermally ablationable by infrared light. The imaging layer is provided in the mask precursor along with a substrate layer and optionally has a protective topcoat layer sandwiched between them. A transparent polymer carrier sheet may be used as a substrate to retain the substrate layer, such that the optional protective topcoat layer lies on top of the imaging layer. The optional protective topcoat layer may be treated with small inorganic or organic particles ranging from 0.3 micrometers to 3 micrometers.

[0045] A mask can be configured for use with an embossing precursor having a photosensitive layer, wherein the top surface contacts the photosensitive layer of the embossing precursor. The mask is obtained by imaging the mask precursor (e.g., a mask element) with IR light. Thus, the mask precursor can be fabricated and treated with light (e.g., IR) to form the mask. The mask can then be bonded to the embossing precursor (e.g., by lamination) and treated with light (e.g., UV), after which the mask and the light-treated embossing precursor are separated from each other.

[0046] Because it has an imageable layer that forms the mask, the mask precursor can be considered an imageable material. In some embodiments, the mask precursor may sequentially comprise three or four layers or films: (a) a transparent polymer carrier sheet (film); (b) a substrate layer; (c) a thermally ablation imaging layer; and (d) an optional particle-treated protective topcoat. The thermally ablation imaging layer can be ablated by thermal imaging with light (e.g., IR light), but this thermally ablation imaging layer does not contain silver halides and is therefore a thermally ablation-free “silver halide” imaging layer.

[0047] Although the protective topcoat is ablation-compatible, it may contain ablation-compatible or non-ablation-compatible particles. While the protective topcoat may include non-ablation-compatible particles, it is still ablation-compatible. In part, the matrix of the protective topcoat may be a non-crosslinked polymer, making it ablation-compatible.

[0048] The mask precursor, which is ultimately used to form the mask element for creating the relief image, can be prepared and processed into a mask as described herein. In some embodiments, the mask precursor 110 is as follows: Figure 1A As shown, it has (a) a transparent polymer carrier sheet 150 on which (b) a substrate layer 120 is directly disposed, (c) an ablationable imaging layer 130 is directly disposed on the substrate layer 120 and positioned to receive light 35 as indicated by the arrow; and (d) an optional protective topcoat 138 with optional particle treatment provided on the ablationable imaging layer 130.

[0049] Transparent polymer carrier sheet

[0050] Transparent polymer carrier sheets can be any suitable transparent substrate or film. Useful transparent polymer carrier sheets can be, but are not limited to, transparent polymer films and sheets composed of one or more polymers, such as polyesters, including polyethylene terephthalate, polyethylene naphthalate, fluoropolyester polymers, polyethylene-polypropylene copolymers, polybutadiene, polycarbonate, polyacrylates (polymers formed at least partially from one or more (meth)acrylate vinyl unsaturated monomers), vinyl chloride polymers (e.g., copolymers of polyvinyl chloride and at least partially derived from vinyl chloride), hydrolyzed or unhydrolyzed cellulose acetate, and other materials obvious to those skilled in the art. Transparent polymer carrier sheets can be composed of two or more polymer materials as a mixture or composite material, provided the desired transparency and protective properties are achieved. They can be formed as a single polymer film or a laminate of multiple polymer films. Generally, the average dry thickness of transparent polymer carrier sheets is at least 25 μm and up to and including 250 μm, or typically at least 75 μm and up to and including 175 μm.

[0051] For example, transparent poly(ethylene terephthalate) sheets, available from a variety of commercial sources, are suitable as transparent polymer carrier sheets.

[0052] If necessary, the surface of the transparent polymer carrier sheet can be treated to alter its wettability and adhesion to applied coatings (such as a base coat). Such surface treatments include, but are not limited to, corona discharge treatment and the application of a base coat, as long as the desired transparency is achieved (as described above).

[0053] If desired, the transparent polymer substrate may optionally contain one or more “first” ultraviolet (UV) absorbing compounds (e.g., UV dyes), but may also be free of any UV absorbing compounds. These compounds may be the same as or different from the UV absorbing compounds in the imaging layer (see below). Each useful UV absorbing compound typically absorbs electromagnetic radiation at least 150 nm and up to and including 450 nm. Based on the total dry weight of the transparent polymer substrate, these compounds may be present in the transparent polymer substrate in an amount of at least 0.01% by weight and up to and including 0.1% by weight. However, the transparent polymer substrate may be free of any IR dyes and / or UV dyes.

[0054] In addition, the transparent polymer carrier sheet may contain one or more "adhesion promoters" to improve its adhesion to adjacent substrate layers. Useful adhesion promoters include, but are not limited to, gelatin, poly(vinylidene chloride), poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid), and polyethyleneimine.

[0055] basal layer

[0056] In some embodiments, the mask precursor further includes a base layer disposed on a transparent polymer carrier sheet and directly between the transparent polymer carrier sheet and the imaging layer. The base layer can be prepared as conventional base layers (or barrier layers) (see, for example, US 9,250,527), or as described in the embodiments described in more detail below. For example, the base layer in the imageable material comprises a thermoflammable polymer binder, which is nitrocellulose, poly(cyanoacrylate), or a combination thereof. Now, the base layer includes lecithin, which allows the mask to be more easily peeled off from a flexographic printing plate as described herein. Lecithin helps maintain the integrity of the mask during the peeling process. Therefore, peeling can be performed more easily, with greater consistency and less damage. Lecithin can promote the retention of the imaging layer on the carrier sheet.

[0057] In some embodiments, suitable substrates and their preparation are described, for example, in U.S. Patent Nos. 5,468,591 and 5,576,144 to Pearce et al. and U.S. Patent No. 6,369,844 to Neumann et al. The substrate may include an adhesive, more specifically, a “thermally combustible” adhesive. Suitable thermocombustible adhesives are reported in U.S. Patent No. 6,521,390 to Leininbach et al. By way of example only, suitable thermocombustible adhesives include non-crosslinked poly(alkyl cyanoacrylate) and non-crosslinked nitrocellulose. Propellant-generating polymers, such as glycidyl azide polymers (“GAP”) and other azide-containing polymers, described in U.S. Patent No. 5,278,023 to Bills et al. and U.S. Patent No. 6,027,849 to Vogel, can be used as polymeric adhesives for the substrate.

[0058] In some embodiments, the base layer may include non-crosslinked nitrocellulose, with or without additional non-crosslinked polymer binders. The molecular weight of the nitrocellulose group units ranges from 459.28 to 594.28 Da, and the molecular formula is represented as [C6H7O2(ONO2)3]. n Where n can be a number from 0 to a larger number. The substrate layer can be ablated using IR radiation as described herein. However, during mask formation, the substrate layer may not actually be ablated, or may only be partially ablated. In some cases, the substrate layer will not have pores corresponding to the mask. However, in other cases or embodiments, the substrate layer may include pores that match the mask. The substrate layer can provide a buffer between the imaging layer and the carrier sheet, which facilitates mask formation.

[0059] The mask element of the present invention includes lecithin in a substrate layer. The lecithin may be present in an amount of about 0.1% to about 25% by weight of the substrate layer, or about 5% to about 20% by weight of the substrate layer, or about 10% to about 15% by weight of the substrate layer. The lecithin may be any identifiable lecithin, or any composition of lecithin identified or indicated as having a mixture of glycerophospholipids. The lecithin incorporated into the binder may be from a powder or liquid source, or any other form. However, particles and liquids may be advantageously used for incorporation into the substrate layer. Although the lecithin may be uniformly distributed throughout the imaging layer, the surface of the substrate layer adjacent to the transparent polymer carrier sheet may have more lecithin. For example, the lecithin may be primarily located at the surface of the substrate layer that bonds to the carrier sheet.

[0060] In some embodiments, lecithin is a mixture of at least two glycerophospholipids. Lecithin may include at least two of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, or phosphatidic acid. In one example, lecithin may include: about 20% to about 50% by weight of phosphatidylinositol; about 20% to about 50% by weight of phosphatidylcholine; about 5% to about 50% by weight of phosphatidylethanolamine; about 5% to about 25% by weight of other phospholipids; and optionally the balance of oil, carbohydrates, sterols, and water to form 100% by weight of lecithin. In another example, lecithin may include: about 30% to about 40% by weight of plant-derived oil; about 20% to about 25% by weight of phosphatidylinositol; about 19% to about 25% by weight of phosphatidylcholine; about 8% to about 20% by weight of phosphatidylethanolamine; about 5% to about 15% by weight of other phospholipids; about 4% to about 6% by weight of free carbohydrates; about 1% to about 6% by weight of sterols; and optionally the balance of water, to form 100% by weight of lecithin. The colorant includes carbon black pigment in the imaging layer, wherein the carbon black pigment is present in an amount of about 30% to about 70% by weight.

[0061] In some embodiments, the substrate layer may be free of UV dyes (e.g., materials that absorb UV light). The substrate layer is typically applied as a relatively uniform coating onto a transparent polymer carrier sheet (i.e., substantially continuous and having a fairly uniform wet thickness), and then dried if any solvents are present in the composition formulation. The substrate layer is typically transparent as defined herein. In particular, the substrate layer is transparent to UV radiation used for imaging the relief-forming precursor. Therefore, the substrate layer may be free of UV dyes or materials that selectively absorb UV light.

[0062] In some embodiments, the base layer may include at least one plasticizer. The plasticizer in the base layer is present in an amount of about 1% to about 50% by weight, about 5% to about 55% by weight, about 10% to about 40% by weight, or about 20% to about 30% by weight. The plasticizer may be represented by acetylthiolitic tributyl citrate (ATBC), Alchemix, and PEG-1000, or combinations thereof. The plasticizer Alchemix may be Alchemix 2340, which may be referred to as NQ Solve 1086, and may be a polyester resin in a mixture of ethyl acetate and ethanol, wherein ethyl acetate is 1% to 30% by weight (or 15% to 20% by weight), ethanol is 1% to 10% by weight (or 5% to 10% by weight), and the balance is polyester resin. The polyester resin may be a low molecular weight polyester having hydroxyl functional groups. In one example, the number-average molecular weight Mn of the polyester composition may be between about 500 and about 10,000 Da or up to 1,000 Da, the polydispersity may be less than about 2, preferably less than about 1.8, the hydroxyl functionality may be between 2 and 3, the hydroxyl value may be between about 160 and about 260, and the acid value may be less than about 10. PEG-1000 may be polyethylene glycol with a molecular weight of about 1,000 Da.

[0063] The substrate layer may be free of IR dyes, but may optionally include IR dyes, for example, from 0% to up to 10%, or up to 8%, or up to 5%, or up to 3%, or up to 2%, or up to 1%. One or more infrared absorbing materials may be collectively identified herein as “first” infrared radiation absorbing materials in order to distinguish them, if necessary, from second infrared radiation absorbing materials in the imaging layer (described below). The first and second infrared radiation absorbing materials may be one or more dyes or pigments, or mixtures thereof, which will provide the desired spectral absorption characteristics and be sensitive to electromagnetic radiation in the infrared electromagnetic wavelength range of at least 700 nm and up to and including 1,500 nm, and typically at least 750 nm and up to and including 1,200 nm. For example, the substrate layer may be free of black dyes or pigments, such as carbon black, metal oxides, and other materials, such as those described in US '987 (mentioned above). Thus, the substrate layer may be particularly free of carbon black, such as carbon black chips (e.g., pre-dispersions). Although IR dyes may be included, such IR dyes may be specific to IR light and exclude broadband light absorbers such as carbon black in the substrate layer.

[0064] Useful first infrared radiation absorbing materials also include IR dyes, including but not limited to cationic infrared absorbing dyes and dyes that can be photothermally bleached. Examples of suitable IR dyes include, but are not limited to, azo dyes, squarilium dyes, croconate dyes, triarylamine dyes, thiazolyl dyes, indolon dyes, oxonol dyes, oxazolium dyes, cyanine dyes, merocyanine dyes, phthalocyanine dyes, indocyanine dyes, indocyanine tricarbon dyes, oxatricarbocyanine dyes, thiocyanine dyes, thiocyanine dyes, merocyanine dyes, cryptocyanine dyes, naphthylphthalocyanine dyes, polyaniline dyes, polypyrrole dyes, polythiophene dyes, chalcogenopyryloarylidene, and bi(chalcogenopyrylo)polymethyllidene. Polymethine dyes, oxindolazine dyes, pyranonium dyes, pyrazoline azo dyes, oxazine dyes, naphthoquinone dyes, anthraquinone dyes, quinone imine dyes, methine dyes, arylmethhine dyes, squarine dyes, oxazole dyes, croconine dyes, porphyrin dyes, and any substituted or ionic forms of the above-mentioned dyes. Suitable dyes are also described in U.S. Patent Nos. 5,208,135 (Patel et al.), 6,569,603 (Furukawa), and 6,787,281 (Tao et al.), and EP Publication 1,182,033 (Fijimaki et al.).

[0065] Near-infrared absorbing cyanine dyes are also useful and are described, for example, in U.S. Patent No. 6,309,792 (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 (Watanate et al.), the disclosures of all of which are incorporated herein by reference. Suitable dyes can be formed using conventional methods and starting materials or are available from a variety of commercial sources, including American Dye Source (Baie D'Urfe, Quebec, Canada) and FEW Chemicals (Germany).

[0066] The first infrared radiation absorbing material is typically present in an amount sufficient to provide a transmitted light density of at least 0.025 and typically at least 0.05 at the wavelength of the exposed electromagnetic radiation (e.g., IR). This is typically achieved by including at least 0.1 wt% and up to and including 5 wt% based on the total dry weight of the substrate layer, or typically at least 0.3 wt% and up to and including 3 wt%.

[0067] The first infrared radiation absorbing material in the substrate layer can be the same or different chemical material from the second infrared radiation absorbing compound incorporated into the imaging layer as described below. The infrared radiation absorbing material in the substrate layer can also differ from the infrared radiation absorbing material in the transparent polymer carrier. In most embodiments, the first and second infrared radiation absorbing materials are the same chemical material, but black substances such as carbon black are excluded. The infrared radiation absorbing material can be selective in absorbing infrared light and is therefore not a broadband absorber that absorbs UV, visible light, or other non-IR light. The amounts of the first and second infrared radiation absorbing materials in the imageable material can be the same or different. In most embodiments, they are present in different amounts in the imageable material.

[0068] In some embodiments, the base layer may comprise an ablative, non-crosslinked adhesive material formed of an organic polymer, in an amount of at least 30% by weight and up to and including 90% by weight, or more likely in an amount of at least 50% by weight and up to and including 80% by weight, or 60% to 75%, all based on the total dry weight of the layer. In some aspects, plasticizers and lecithin may be included in the aforementioned amounts, with or without IR dyes, and the adhesive may be the remainder of the material.

[0069] The substrate typically has an average dry thickness of at least 0.5 μm and up to and including 5 μm, or typically at least 0.8 μm and up to and including 3 μm.

[0070] In some embodiments, the base layer may be free of crosslinked nitrocellulose or other crosslinking adhesives. Furthermore, the base layer may be free of crosslinking agents that can crosslink nitrocellulose. Additionally, the base layer may be free of crosslinking polymers.

[0071] In some implementations, the substrate may be particle-free, such as ablation-compatible or non-ablation-compatible particles. The substrate may also be particle-free of metal oxides.

[0072] In some implementations, the substrate may not contain metallization layer material or metal therein.

[0073] Thermally ablation imaging layer (IL)

[0074] The imaging layer incorporated into the mask precursor is typically applied directly onto the substrate as a relatively uniform coating (i.e., substantially continuous and with a fairly uniform wet thickness), and then dried if any solvent is present in the formulation. In most embodiments, the imaging layer is a single-coated or applied layer, but in other embodiments, the imaging layer, which may be applied directly onto the substrate, consists of multiple sublayers or subcoatings.

[0075] Imageable materials can include ablative polymers, often referred to as binders. Suitable binders can dissolve or disperse other components contained in the imageable material. Depending on the imaging system, binders can have various uses. One function of binders is to facilitate the subsequent transfer of the resulting mask image to a photosensitive layer. Adhesives that provide thermoplasticity can simplify the transfer of the mask image to the photosensitive material. Adhesives that provide better adhesion to the photosensitive material can also be helpful. Based on the solids content of the imageable material, the total binder is typically present in an amount of about 25–75 wt%, more preferably about 35–65 wt%.

[0076] In some embodiments, it is advantageous to use a binder material in the imaging layer that is readily thermally combustible or ablation-prone and generates gas and volatile debris at temperatures below 200°C. Examples of such materials are thermally ablationable nitrocellulose, polycarbonate, poly(cyanoacrylate), polyurethane, polyester, polyorthoester, polyacetal, polyamide, polyurethane, polyolefin, polystyrene, polyether, polyethylene ether, polyethylene ester, and polyacrylate and polymethacrylate having alkyl groups having 1 and 2 carbon atoms. Furthermore, copolymers (see, for example, U.S. Patent No. 5,171,650, Ellis et al., column 9, lines 41-50, the disclosure of which is incorporated herein by reference) can be used in ablationable binders. Ablationable polymer binder materials can be non-crosslinked. These polymers are prepared to be ablationable.

[0077] In some embodiments, the ablationable adhesive may include, for example, the materials described in

[0081] through

[0085] of US '987. These materials may also be referred to as "adhesive adhesives," for example, as described in

[0081] of US '987. Examples of such materials include, but are not limited to, acetyl polymers, such as poly(vinyl butyral)s, which may be available, for example, from Solution, Inc. (St. Louis, Mo.) as BUTVAR® B-76; and acrylamide polymers, which may be available from Henkel Corp. (Gulph Mills, Pa.) as MACROMELT 6900. Other useful ablationable materials for imaging layers have hydroxyl groups (or hydroxyl polymers), such as poly(vinyl alcohol) and cellulose polymers (e.g., nitrocellulose).

[0078] In some embodiments, the ablationable material for the imaging layer may include polyurethane, poly(vinyl butyral), (meth)acrylamide polymer, polyacetal, poly(cyanoacrylate), polymers at least partially derived from any one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate and isobutyl methacrylate, or combinations of two or more of these materials.

[0079] As the terminology states, silver halides are essentially absent in the imaging layer. In other words, silver halides are not intentionally added to or generated in the imaging layer.

[0080] In some embodiments, the imaging layer comprises non-crosslinked nitrocellulose, carbon black or other colorants and infrared dyes, and optionally a plasticizer. The nitrocellulose may be non-crosslinked as described herein.

[0081] The imaging layer may include a colorant, such as carbon black, of which many commercially available varieties have various particle sizes. Examples include RAVEN 450, 760 ULTRA, 890, 1020, and 1250 from Columbia Chemicals Co. (Atlanta, Ga), and BLACK PEARLS 170, BLACK PEARLS 480, VULCAN XC72, and BLACK PEARLS 1100 from Cabot Corporation. Carbon black can be received as a dispersion or as a chip. Predisol C Black 7 from Sun Chemical is preferred due to its high pigment-to-binder ratio. Other useful carbon blacks are surface-functionalized with solubilizing groups. Carbon black grafted onto hydrophilic nonionic polymers (e.g., FX-GE-003 (manufactured by Nippon Shokubai)) or carbon black surface-functionalized with anionic groups (e.g., CAB-O-JET® 200 or CAB-O-JET® 300 (manufactured by Cabot Corporation)) is also useful. For example, carbon black flakes may comprise carbon black material (e.g., pigment) dispersed in a binder and provided in small pieces or flakes (e.g., not as a solution or in a solvent), wherein the flakes are used to prepare a layer having carbon black. However, other light-absorbing colorants may be used. Darker colorants may be preferred over lighter colorants. Darker colorants (such as carbon black) may be present in amounts of 1% to about 30%, about 5% to about 20%, or about 10% to about 15% of the imaging layer.

[0082] The imaging layer may include at least one plasticizer. The plasticizer in the imaging layer is present in an amount of about 1% to about 50% by weight, about 5% to about 40% by weight, or about 10% to about 30% by weight. Representative plasticizers may be acetyl ATBC, Alchemix, and PEG-1000, or combinations thereof, as described above.

[0083] In some embodiments, the plasticizer may include multiple ester groups, such as polymers having ester or multiple ester moieties, which may include alkyl groups. For example, ATBC includes four alkyl esters coupled together, while Alchemix is ​​a polyester. Additionally, polyethers, such as PEG, polypropylene glycol, and combinations thereof, may be used. Thus, compounds or polymers having multiple ether groups or multiple ester groups, each ether group or ester group having an associated alkyl component. Alkyl ethers and alkyl esters, such as those having multiple alkyl ether moieties or alkyl ester moieties, are also possible.

[0084] In some embodiments, Alchemix or polyester polymers are excluded from the plasticizer. Therefore, in some embodiments, the plasticizer in the imaging layer may include a compound having multiple alkyl ester moieties coupled together in a branched structure, or a polymer with multiple alkyl ester moieties linked in the chain.

[0085] In some embodiments, the imaging layer comprises one or more ultraviolet radiation absorbing materials (UV light absorbing materials) as components. These compounds typically have an absorbance of at least 1.5 and up to and including 5 in the electromagnetic radiation wavelength range of at least 300 nm and up to and including 450 nm. Generally, useful ultraviolet radiation absorbing materials include, but are not limited to, benzotriazoles, halobenzotriazoles, triazines, benzophenones, benzoate esters, salicylates, substituted acrylonitriles, cyanoacrylates, benzylmalonate, oxalaniline, and mixtures thereof. Examples of useful ultraviolet radiation absorbing materials include, but are not limited to, UV absorbing dyes or UV stabilizers sold under the names 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.). However, embodiments of the imaging layer also omit any UV dyes.

[0086] The imaging layer also comprises one or more second infrared radiation absorbing materials, which are defined in the same way as the first infrared radiation absorbing materials used in the substrate layer described above, and may be the same as or different from the first infrared radiation absorbing materials. The amount of one or more second infrared radiation absorbing materials present in the imaging layer is sufficient to provide a transmitted light density of at least 0.5, typically at least 0.75, at the exposure wavelength. This is typically achieved by including at least 3% by weight and up to and including 20% ​​by weight of one or more second infrared radiation-sensitive compounds based on the total dry weight of the imaging layer. The IR dyes in the imaging layer may be specifically designed to absorb IR light better than visible and UV light; therefore, the IR dyes are not blackbody materials that absorb broadband light.

[0087] The imaging layer may optionally include one or more fluorocarbon additives to improve the generation of halftone dots (i.e. pixels) with well-defined, generally continuous, and relatively sharp edges. Examples of useful fluorocarbon additives and amounts are provided in

[0087] to

[0089] of US '987 (as described above).

[0088] Other optional components of the imaging layer include, but are not limited to, other plasticizers, coating aids or surfactants, dispersants, fillers, and colorants, all of which are well known in the art, for example, as described in

[0094] to

[0096] of US '987 (as described above). For example, the imaging layer may also contain one or more fluorocarbon additives or one or more non-thermally ablative colorants. Examples of other suitable plasticizers (e.g., co-plasticizers) may include aliphatic hydrocarbon oils, such as naphthenic oils and paraffin oils; liquid polydienes, such as liquid polybutadiene and liquid polyisoprene. Typically, co-plasticizers are liquids with a molecular weight of less than about 5,000 Da, but molecular weights can also be as high as about 30,000 Da. Plasticizers with low molecular weights will cover molecular weights of less than about 30,000 Da. These other co-plasticizers may also be used in the substrate layer.

[0089] In some embodiments, the ablative polymer binder in the imaging layer is uncrosslinked, and therefore a non-crosslinked binder. Furthermore, the imaging layer may not contain a crosslinking agent capable of crosslinking nitrocellulose. Such materials are capable of dissolving or dispersing the necessary and optional components uniformly throughout the imaging layer. Based on the total dry weight of the imaging layer, one or more ablative polymer binder materials may be present in an amount of at least 25% by weight and up to and including 75% by weight, or typically at least 35% by weight and up to and including 65% by weight.

[0090] The average dry thickness of the imaging layer may be at least 0.5 μm and up to and including 5 μm, or typically at least 0.8 μm and up to and including 2.5 μm.

[0091] Protective topcoat

[0092] The mask precursor may optionally include a transparent polymer topcoat, which is disposed directly on the imaging layer, on the opposite side of the substrate layer. This transparent polymer topcoat may optionally be a grain-treated protective topcoat. Adding particles to such a grain-treated protective topcoat provides the present invention with the advantages of improved resolution and increased specular dot retention.

[0093] Protective topcoat coatings typically comprise one or more transparent film-forming polymers or resins, including but not limited to methacrylic acid copolymers (e.g., copolymers of ethyl methacrylate and methacrylic acid). The bulk of the protective topcoat coating may include small particles as described herein. These particles may be inorganic particles, which may be silica or metal oxide particles with a size less than 1 micrometer. The metal oxide particles may be ablative, such as iron oxide particles. Alternatively, the metal oxide particles may be non-ablative, such as titanium dioxide or zinc oxide. Non-ablative silica particles may also be used. These inorganic particles may be 0.001 micrometers to about 0.99 micrometers, or about 0.01 micrometers to about 0.75 micrometers, or about 0.05 micrometers to about 0.5 micrometers, or about 0.1 micrometers to about 0.25 micrometers, or any range between any of the foregoing values.

[0094] The inorganic particles can be the non-ablative particles described herein. However, the protective topcoat treated with particles is ablative, thus the polymer matrix is ​​non-crosslinked. The matrix can be prepared to be ablative, which can be similar to the matrix composition of the imaging layer.

[0095] The protective topcoat can be directly attached to the imaging layer, and the average dry thickness can be at least 0.05 μm and up to and including 1 μm. The thickness can vary depending on the implementation.

[0096] In some embodiments, it is advantageous to use a thermally flammable or thermally ablative adhesive material in the protective topcoat that generates gas and volatile debris at temperatures below 200°C. Examples of such materials are thermally ablative nitrocellulose, polycarbonate, poly(cyanoacrylate), poly(methacrylate), poly(ethyl acrylate), polyurethane, polyester, polyorthoester, polyacetal, and copolymers thereof (see, for example, U.S. Patent No. 5,171,650, Column 9, Lines 41-50, the disclosure of which is incorporated herein by reference), which may be non-crosslinked. One example is a 1:1 methacrylate-ethyl acrylate copolymer, such as Kolicoat® MAE30 DP.

[0097] Other useful ablationable materials for protective topcoats have hydroxyl groups (or hydroxyl polymers), as described in

[0082] to

[0084] of US '987 (as stated above), such as polyvinyl alcohol and cellulose polymers (e.g., nitrocellulose), which may be non-crosslinked. Examples of useful polymers are grouped as non-crosslinked polyesters, polyamides, polyurethanes, polyolefins, polystyrene, polyethers, polyethylene ethers, polyethylene esters, and polyacrylates and polymethacrylates having alkyl groups having 1 or 2 carbon atoms, and copolymers thereof. Particularly useful ablationable materials for protective topcoats include, but are not limited to, polyurethanes, polyvinyl butyral, (meth)acrylamide polymers, nitrocellulose, polyacetals, poly(cyanoacrylates), polymers at least partially derived from any one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate, or combinations of two or more of these materials, such as copolymers, which may be non-crosslinked.

[0098] Furthermore, the protective topcoat may include fluoro-particles of one or more fluoropolymers dispersed therein, such as those described in U.S. Patent No. 6,259,465 (Tutt et al.), the disclosure of which is incorporated herein by reference. One example may include polytetrafluoroethylene (PTFE). The fluoro-particles may be present in an amount from about 1% to about 40%, preferably about 33%.

[0099] In addition, the protective topcoat may include surfactants, such as fluoro-surfactants. A fluoro-surfactant could be Capstone FS-3100. Fluoro-surfactants can be present in amounts significantly less than fluorinated particles.

[0100] In some embodiments, the protective topcoat may include a silicone-containing surface additive. The silicone-containing surface additive may be a polyether-modified polydimethylsiloxane, such as BYK 333. The silicone may be present in a significantly smaller amount than that of a fluorinated surfactant.

[0101] mask

[0102] Because it has an imageable layer that forms a mask, a mask precursor can be considered an imageable material. In some embodiments, the mask precursor may sequentially comprise the following four layers or films: (a) a transparent polymer carrier sheet (film) optionally having a first ultraviolet absorbing compound; (b) a base layer having lecithin, optionally also having a first infrared radiation absorbing compound and / or a plasticizer; (c) a thermally ablative imaging layer (IL) having a colorant (e.g., carbon black), a second infrared radiation absorbing compound, optionally having an ultraviolet absorbing compound and optionally a plasticizer; and (d) an optional protective top coating that has been particle-treated.

[0103] The mask precursor, ultimately used to form the relief image for manufacturing the mask element, can be prepared and processed into a mask as described herein. In some embodiments, the mask precursor 110 is as follows: Figure 1A As shown, it comprises (a) a transparent polymer carrier sheet 115 on which (b) a lecithin-containing substrate layer 120 is directly disposed, (c) an ablationable imaging layer 130 directly disposed on the substrate layer 120 and positioned to receive light 35 as indicated by arrow 35, and (d) a protective topcoat 138 provided on the ablationable imaging layer 130. It should be noted that the protective topcoat 138 is optional and may be omitted in all figures.

[0104] For some implementation plans, the exposure steps are... Figure 1A As shown, the mask precursor material 110 is exposed to infrared radiation 35 for exposure in an image-by-image pattern to provide, for example, Figure 1B The mask elements shown correspond to the exposed area 140 and the unexposed area 142. As shown, the exposed area 140 is ablated and removed from the unexposed area 142. Therefore, the exposed area 140 forms a mask image.

[0105] Some embodiments of the present invention can be referenced Figures 1A to 1E The order provides a general explanation for understanding. As mentioned above, Figure 1A This describes the exposure to infrared radiation 35 for forming a mask element. Figure 1B ) mask precursor 110.

[0106] exist Figure 1C In this embodiment, mask element 136 includes a transparent polymer carrier sheet 115 on a substrate layer 120 over an ablated imaging layer 130 having a mask image formed therein and an ablated protective topcoat 138. By contacting the optional protective topcoat 138, mask element 136 is positioned in close or full optical contact with an embossing precursor 155 to provide an embossed image forming assembly 150. Embossing precursor 155 includes a UV-sensitive layer 160 typically carried on a substrate 165.

[0107] Figure 1D The step of exposing the embossed image forming assembly 150 to UV radiation 170, indicated by the arrow, is shown. The UV radiation 170 passes through the exposure area of ​​the imaging layer 130 in the transparent polymer carrier sheet 115, the substrate layer 120, and the mask element 136 (e.g., element 140 - the removed portion of the imaging layer), and then through the exposure area in the particle-treated protective topcoat 138, thereby causing photocuring in the UV-sensitive layer 160 of the embossed forming precursor 155.

[0108] After UV exposure, the mask element 136 can be removed from the UV-sensitive layer 160 of the embossed precursor 155, and the development process can be as follows: Figure 1E An embossed image is provided as shown in the UV-sensitive layer 160. Figure 1E As shown, the embossed image includes embossed image peaks 175 and embossed image valleys 180 in the UV-sensitive layer 160.

[0109] Forming a mask

[0110] In some implementations, a mask can be formed by creating exposed and unexposed areas in the imaging layer of the mask precursor implementation described herein. The choice of imaging mechanism will determine the possible variations in the formed mask image, as described below.

[0111] Exposing the mask precursor to ablation light energy to ablate the imaging layer and protective topcoat can be performed in selected areas; this is also known as "image-by-image exposure." In some implementations, image-by-image exposure can be achieved using thermal radiation from a thermal or infrared laser, scanned or rasterized under computer control. Any known scanning device can be used, including planar scanners, external drum scanners, and internal drum scanners. In these devices, the mask precursor material is fixed on a drum or bed, and a laser beam is focused into a spot that is projected onto the imaging layer of the mask precursor material. Two or more lasers can simultaneously scan different areas of the imaging layer.

[0112] For example, the mask precursor material can be exposed to infrared radiation, for instance, in the electromagnetic wavelength range of at least 700 and up to and including 1500 nm. Such mask precursor materials contain one or more second infrared radiation absorbing materials as described above in the imaging layer to provide sensitivity to infrared radiation. In these embodiments, the mask precursor material can be suitably mounted on an infrared imager and exposed to infrared radiation using an infrared laser (e.g., a diode laser or Nd:YAG laser that can be scanned under computer control). Suitable infrared imagers include, but are not limited to: TRENDSETTER imagesetters and ThermoFlex flexographic CTP imagers available from EastmanKodak Company for CTP lithography applications and imaging flexographic elements; DIMENSION imagesetters available from Presstek (Hudson, NH) for CTP lithography applications; CYREL® digital imagers (CDISPARK) available from Esko-Graphics (Kennesaw, Ga.); and OMNISETTER imagers available from Misomex International (Hudson, NH) for imaging flexographic elements.

[0113] For some implementation plans, this exposure step is in Figure 1A As shown, the mask precursor material 110 is exposed to infrared radiation 35 for exposure in an image-by-image pattern to provide, for example, Figure 1B The mask element 136 shown corresponds to the exposed area 140 and the unexposed area 142 of the mask image. As shown, the exposed area 140 is ablated and removed from the unexposed area 142. Thus, the exposed area forms the mask image.

[0114] If necessary, the process of forming the mask image may also include removing exposed or unexposed areas from the imaging layer. In some embodiments, the exposed areas of the imaging layer are removed, for example, by ablation of the exposed material in the imaging layer. In this mechanism, the exposed areas of the imaging layer are removed from the mask element by generating gas during the ablation process, leaving a mask image. The imaging layer may contain a specific binder (e.g., non-crosslinked) that decomposes rapidly to generate gas when exposed to heat (e.g., heat generated by IR laser irradiation). This action differs from other mass transfer techniques in that a chemical rather than a physical change results in almost complete rather than partial mass transfer of the imaging layer.

[0115] In other embodiments not shown, a mask image can be formed on a carrier sheet by creating exposed and unexposed areas in the imaging layer and selectively removing the unexposed areas.

[0116] In some implementations, the mask image in the imaging layer of the mask element can be cured by heat treatment, provided that the performance of the mask element is not adversely affected. Heat treatment can be performed by various means, including but not limited to oven storage, hot air treatment, contact with a heated platform, or via a heated roller device. Curing is not always required to undergo heat treatment.

[0117] In other embodiments, a mask image can be formed in the imaging layer as described above, and the exposed area can be transferred onto a receiver sheet, which is then removed from the mask element before the receiver sheet comes into contact with the relief forming precursor. Such procedures are well known in the art.

[0118] In the stripping imaging mechanism, the exposed areas of the imaging layer can be removed from the carrier sheet using a suitable receiving sheet based on the differential adhesion properties within the imaging layer. After image-by-image exposure of the mask precursor, the receiving sheet is separated from the carrier sheet, leaving the exposed or unexposed areas within the mask element.

[0119] Precursor to relief formation

[0120] In some implementations, a photosensitive embossing material can be used in the embossing-forming photopolymer plate precursor. The photosensitive embossing layer can be processed to form an embossed image. The photosensitive embossing layer can also be used in solvent-washable or water-washable plates.

[0121] US '987 (as described above) provides extensive details on useful embossing precursors (such as flexographic printing plate precursors, letterpress printing plate precursors, and printed circuit boards). Such embossing precursors may comprise a suitable dimensionally stable substrate and a UV (ultraviolet) sensitive embossing layer, and optionally a coversheet and / or metal layer between the substrate and the embossing layer. Suitable substrates include dimensionally stable polymer films and aluminum sheets. Polyester films are particularly useful. In practicing this invention, they are useful when any UV-sensitive material or element (in which an embossed image can be produced using a mask element) contains low surface energy additives.

[0122] In some embodiments, the embossing precursor typically includes a suitable dimensionally stable substrate, a radiation-curable layer in which a flexographic embossed image can be formed, and optionally an overlay on the radiation-curable layer and / or a metal layer between the substrate and the radiation-curable layer. Suitable substrates include flexible, dimensionally stable transparent polymer films and metal substrates, such as aluminum sheets. Polyester films are particularly useful as flexible, dimensionally stable, and transparent substrates. The embossing precursor may optionally include a metal layer disposed between the substrate and the radiation-curable layer. This metal layer may include copper or other metals or metal alloys.

[0123] Some embodiments also include a removable cover sheet that protects the radiation-curable layer from fingerprints and other damage and is disposed on the radiation-curable layer. In some embodiments, the flexographic printing plate precursor also includes a metal layer between the substrate and the radiation-curable layer, or includes both a cover sheet sandwiching the radiation-curable layer and a metal layer.

[0124] In some embodiments, the radiation-curable layer may be a UV-sensitive layer that is cured by UV light. In some aspects, the UV-sensitive layer may be at least one layer of an embossing precursor formed from a UV-sensitive embossing material. Therefore, the embossing material or layer referred to is a UV-sensitive material or layer that can be irradiated with UV light and developed into an embossed image.

[0125] In some embodiments, the embossing precursor includes: a backing film or base film (e.g., as a substrate), an embossing layer (e.g., a UV-sensitive material), and an optional removable cover film to protect the photosensitive layer. In another option, a metal layer may be located between the substrate and the embossing layer.

[0126] In some embodiments, a backing film or base film can be configured to provide support for the embossing layer of the embossing precursor. The backing layer can be formed of a transparent or opaque material (e.g., paper, cellulose film, plastic, or metal). The backing layer is preferably formed of a flexible, transparent material. Examples of such materials are cellulose films or plastics such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyether, polyethylene, polyamide (Kevlar), or nylon. Preferably, the support layer is formed of polyethylene terephthalate (PET). It has also been found that embossing layers containing low surface energy additives can adhere to the support layer. The thickness of the support layer can be from about 0.001 to about 0.010 feet. Optionally, various layers (e.g., anti-halo layers and / or adhesive layers) can be located between the backing layer and the embossing layer. In some aspects, the adhesive layer may include an anti-halo material (e.g., a light-absorbing substance to prevent light refraction), or it may not contain such an anti-halo material.

[0127] In some implementations, the embossing layer can be a UV-sensitive material that forms an embossed image after imaging and development with UV light, wherein the embossed image has a reduced surface energy. Adding low-surface-energy additives to the UV-sensitive material provides several desirable properties for embossed image formation schemes, such as easier vacuuming and better lamination to reduce bubble formation. Furthermore, the reduced peel strength allows for easier removal of the imaged mask from the embossing layer after the main UV exposure to form the embossed image.

[0128] In some embodiments, reduced surface energy and reduced peel strength are achieved by incorporating low surface energy additives into the composition of the photosensitive material. The low surface energy additives can be contained within the matrix of the photosensitive material so that they are present and distributed within and on the surface of the photosensitive material. Typically, the low surface energy additives are uniformly mixed in the photosensitive material. However, the additives can be provided randomly or heterogeneously (e.g., non-uniformly), or in a gradient of concentration preferentially increasing to one side or the other.

[0129] In some embodiments, the low surface energy additive may comprise a silicone material, such as a silicone monomer having reactive functional groups. The reactive functional groups can be selected to polymerize with other polymerizable monomers of the photosensitive material. This allows the silicone to be incorporated into the polymerized material, thereby retaining it on the photosensitive material portion left after the embossing process. Therefore, the reactive functional groups can be tailored from well-known functional groups that can participate in the polymerization of other monomers of a specific type having the same or different but suitable reactive functional groups.

[0130] In some embodiments, the photosensitive material may be a UV-sensitive layer comprising: an elastomeric adhesive; at least one polymerizable or photocurable monomer; and a photopolymerizable photoinitiator sensitive to UV radiation. Suitable photoinitiator compositions include, but are not limited to, those described in U.S. Patent Nos. 4,323,637 (Chen et al.), 4,427,749 (Graetzel et al.), and 4,894,315 (Feinberg et al.).

[0131] The elastomeric adhesive may include a greater number of polymers or resins that can be dissolved, swollen, or dispersed in aqueous, semi-aqueous, or organic solvent developers (see below), and may include, but is not limited to, natural or synthetic polymers of conjugated dienes, block copolymers, core-shell microgels, and blends of microgels with preformed macromolecular polymers. Based on the total dry weight of the UV-sensitive layer, the elastomeric adhesive may comprise at least 65% by weight and up to and include 90% by weight.

[0132] In some embodiments, the elastomeric adhesive may be a single polymer or a mixture of polymers (e.g., homopolymers, copolymers, random copolymers, block copolymers, any of which have any number of monomers of different types) that can be dissolved, swollen, or dispersed in aqueous, semi-aqueous, or organic solvent developers. Suitable adhesives include those described in U.S. Patent Nos. 3,458,311 (Alles), 4,442,302 (Pohl), 4,361,640 (Pine), 3,794,494 (Inoue), 4,177,074 (Proskow), 4,431,723 (Proskow), and 4,517,279 (Worns). Adhesives that are soluble, swollen, or dispersible in organic solvent developers include natural or synthetic polymers of conjugated dienes, 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 Nos. 4,323,636 (Chen), 4,430,417 (Heinz), and 4,045,231 (Toda) may be used. Elastomer adhesives may be present in an amount of at least about 65% by weight of the photosensitive material. The term adhesive, as used herein, encompasses core-shell microgels and blends of microgels and preformed macromolecular polymers, such as those described in U.S. Patent No. 4,956,252 (Fryd).

[0133] At least one polymerizable monomer can be configured to be compatible with elastic adhesives to the extent that it produces a clear, unclouded UV-sensitive imageable layer. Polymerizable monomers for this purpose are well known in the art and include vinyl-unsaturated polymerizable compounds with relatively low molecular weights (typically less than 30,000 Daltons). Suitable monomers have relatively low molecular weights, less than about 5,000 Da. Unless otherwise described, all molecular weights are weight-average molecular weights throughout this specification. Examples of suitable polymerizable monomers include various monoacrylates and polyacrylates, acrylate derivatives of isocyanates, esters, and epoxides. In addition, examples of suitable monomers include tert-butyl acrylate, lauryl acrylate; and acrylate and methacrylate monoesters and polyesters of alcohols and polyols (e.g., alkanols), such as: alkanols (examples of their corresponding monoesters and polyesters are, for example, 1,4-butanediol diacrylate, 2,2,4-trimethyl-1,3-pentanediol dimethacrylate and 2,2-dimethylolpropane diacrylate), alkylene glycols (examples of their corresponding monoesters and polyesters are, for example, tripropylene glycol diacrylate, butanediol dimethacrylate, hexamethylene glycol diacrylate and hexamethylene glycol dimethacrylate), trimethylolpropane, ethoxylated trimethylolpropane, pentaerythritol (examples of their corresponding monoesters and polyesters are, for example, pentaerythritol triacrylate), dipentaerythritol, etc. Other examples of suitable monomers include acrylates and methacrylate derivatives of isocyanates, esters, epoxides, etc., such as decamethylene glycol diacrylate, 2,2-bis(p-hydroxyphenyl)propane diacrylate, 2,2-bis(p-hydroxyphenyl)propane dimethacrylate, polyoxyethyl-2,2-bis(p-hydroxyphenyl)propane dimethacrylate, and 1-phenylethylene-1,2-dimethacrylate. Further examples of monomers can be found in U.S. Patent Nos. 4,323,636 (Chen), 4,753,865 (Fryd), 4,726,877 (Fryd), and 4,894,315 (Feinberg). The monomer may constitute at least 5% by weight and about 25% by weight of the photosensitive material, this weight percentage being based on the total dry weight of the photosensitive material.

[0134] Photoinitiators can be any single compound or combination of compounds sensitive to ultraviolet radiation, generating free radicals that initiate the polymerization of one or more monomers without excessive termination. Photoinitiators can be sensitive to visible or ultraviolet radiation. They can also be insensitive to infrared and / or visible radiation and can be thermally inert at 185°C and below. Examples of suitable photoinitiators include substituted and unsubstituted polynuclear quinones. Examples of suitable systems are disclosed in U.S. Patent Nos. 4,460,675 (Gruetzmacher) and 4,894,315 (Feinberg). Based on the weight of the photosensitive material, the photoinitiator is typically present in amounts from 0.001 wt% to 10.0 wt%.

[0135] In some embodiments, the photosensitive layer may include: a diblock or triblock copolymer (e.g., an elastomer); at least one photopolymerizable monomer; a photopolymerization initiator; a plasticizer; additives such as stabilizers, inhibitors, colorants, and solvents; and a low surface energy monomer, such as silicone acrylate or silicone methacrylate.

[0136] In some embodiments, the plasticizer can be any plasticizer known in the field of photosensitive layers that is suitable for use as described herein. Examples of suitable plasticizers include aliphatic hydrocarbon oils, such as naphthenic oils and paraffin oils; liquid polydienes, such as liquid polybutadiene and liquid polyisoprene. Typically, plasticizers are liquids with a molecular weight of less than about 5,000 Da, but molecular weights can be as high as about 30,000 Da. Plasticizers with low molecular weights will cover molecular weights of less than about 30,000 Da.

[0137] In some embodiments, additives may include rheology modifiers, thermal polymerization inhibitors, stabilizers, inhibitors, thickeners, colorants, antioxidants, anti-ozone agents, solvents, or fillers. These materials are commonly used in photosensitive layers, and examples are provided in the accompanying references.

[0138] The thickness of the photosensitive layer can vary depending on the type of printing plate required. In one embodiment, the thickness of the photosensitive layer can be, for example, about 20-250 mils (500-6,400 micrometers) or greater, more specifically about 20-100 mils (500-2,500 micrometers).

[0139] In some embodiments, the embossing precursor is a flexographic printing plate precursor that includes a suitable UV-curable composition (e.g., a photosensitive material) in a UV-sensitive layer (e.g., a photosensitive layer) to provide an embossed image in the flexographic printing plate when exposed and developed through a mask element. Such embossing precursors typically include a suitable substrate with a photosensitive material. Examples of commercially available flexographic printing plate precursors include, but are not limited to: FLEXCEL NX flexographic elements available from Miraclon Corporation; CYREL® flexographic plates available from DuPont (Wilmington, Del.); NYLOFLEX° FAR 284 plates available from BASF (Germany); FLEXILIGHT CBU plates available from Macdermid (Denver, Co.); and ASAHI AFP XDI available from Asahi Kasei (Japan).

[0140] In some embodiments, embossing precursors can also be used to form printed circuit boards, wherein a conductive layer (also referred to as a “printed circuit”) is formed on a substrate according to a pattern determined by exposure via a mask element. Suitable precursors for printed circuit boards typically include a substrate, a metal layer, and a UV-sensitive imageable layer (e.g., a photosensitive material). Suitable substrates include, but are not limited to, polyimide films, glass-filled epoxy or phenolic resins, or any other insulating material known in the art. The metal layer covering the substrate is typically a conductive metal, such as copper or a metal alloy. The UV-sensitive imageable layer may include a UV-curable resin, a polymerizable monomer or oligomer, a photoinitiator, and a polymer binder. Further details of printed circuit boards are provided in US '987 (as described above).

[0141] Forming relief images

[0142] After forming both the mask and the relief forming precursor as described above, a protective topcoat (or an imaging layer without a protective topcoat) is brought into full optical contact with the relief forming precursor, which contains a photosensitive layer sensitive to UV radiation for curing. This can be achieved by placing either the protective topcoat or the imaging layer of the mask onto the relief forming precursor, or vice versa, as described in more detail below. For example, contact and coupling between the top surface of the mask and the relief forming precursor can be performed using lamination equipment and processes. Alternatively, the desired full optical contact can be achieved by vacuum suction of the top surface of the mask onto the relief forming precursor, with or without lamination.

[0143] Some embodiments of the present invention can be referenced Figures 1A to 1E The general instructions provided in the order are for understanding. When using mask precursor 110, ablation may also ablate a portion of the substrate 120.

[0144] In some embodiments, a method for forming an embossed image is provided. The method may include providing an embossing assembly comprising a mask and an embossing precursor in complete optical contact with the mask. The method may then include exposing an embossing layer of the embossing precursor through the mask to curing ultraviolet radiation to form an imaged embossing layer in which ultraviolet-exposed areas form polymeric regions and unexposed areas form non-polymeric regions. The method may then include removing the mask from the imaged embossing layer. Lecithin in the base layer of the mask may facilitate the intact peeling and removal of the entire mask from the imaged embossing layer. The imaged embossing layer can be developed by removing the non-polymeric regions in the imaged embossing layer, thereby forming an embossed image element having an embossed image.

[0145] In some aspects, exposure is performed using a mask with an optical density greater than 3.0 (e.g., 3.5–3.8) in non-imaging areas and less than about 0.20 in fully ablated imaging areas. In other aspects, exposure is performed at a rate less than about 24 joules / cm². 2 Less than or approximately 22 joules / cm 2 Less than or approximately 21 joules / cm 2 Less than or approximately 20 joules / cm 2 Less than or approximately 19 joules / cm 2 Less than or approximately 18 joules / cm 2 Or less than or approximately 17 joules / cm² 2 It was carried out.

[0146] In some implementations, exposure is performed using a mask that has no DigiCap pattern and an optical density of less than or about 0.18, less than or about 0.16, less than or about 0.12, or less than or about 0.11.

[0147] laminated

[0148] As described above, the mask element and the embossing precursor can be placed in full optical contact to provide an airless interface at the shared interface between the top surface of the mask and the UV-sensitive layer. Typically, this is achieved by applying appropriate pressure or heat, or both, before UV exposure to press the mask layer against the UV-sensitive layer of the embossing precursor to form an airless or seamless interface. As mentioned above, it may be useful to subsequently vacuum-pump the mask element onto the embossing precursor.

[0149] Commercially available laminators that provide both heat and uniform pressure can be used, including but not limited to: the KODAK model 800XL APPROVAL LAMINATOR available from EastmanKodak Company (Rochester, NY); the CODOR LPP650 LAMINATOR available from CODOR (Amsterdam, Netherlands); and the LEDCO HD laminator available from Filmsource (Casselbury, FL).

[0150] In some implementations, an optional protective top coating may be removed before lamination or other operations that form complete optical contact between the mask and the embossing precursor. The embossed image forming assembly formed by the coupled mask and embossing precursor can be fed into the laminator at the desired speed, temperature, and pressure.

[0151] Useful laminating (laminating) apparatus and methods of using 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 (“mask”) onto an embossing precursor (“prepress flexographic plate”) by applying a balanced, non-deformation, optimized lamination pressure to achieve full optical contact while minimizing lateral distortion.

[0152] In some implementations, the embossing precursor has a release layer, spacer layer, or anti-sticking layer on the UV-sensitive embossing layer.

[0153] UV Exposure

[0154] After achieving full optical contact between the mask and the relief-forming precursor (as described above), the relief-forming precursor can be exposed to curing UV radiation through the mask to form an imaged relief-forming precursor with exposed and unexposed areas in the UV-sensitive layer. The exposed areas are cured and solidified by the polymerization of monomers in the UV-sensitive layer. The unexposed areas remain uncured, and the monomers are not polymerized. Therefore, uniformly emitted curing UV radiation is projected onto the relief-forming precursor through the mask image, which preferentially blocks a portion of the UV radiation through the remaining portion of the imaging layer. In the unmasked (exposed) areas, curing UV radiation causes the UV-sensitive composition in the imaging layer to harden or solidify. Therefore, the mask image is substantially opaque to either exposure or curing UV radiation, meaning that the transmitted light density of the mask image in the unexposed areas should be 2 or higher, typically 3 or higher. The remaining portion of the imaging layer still comprises UV-sensitive material to absorb and block UV light. The unmasked (exposed) areas of the UV-sensitive composition can be substantially transparent, meaning their transmitted light density should be 0.5 or less, 0.2 or less, or even 0.1 or less. The light density of the masked (unexposed) areas in the mask can be at least about 3 and higher. Transmitted light density can be measured using a suitable filter on a densitometer (e.g., a MACBETH TR 927 densitometer).

[0155] Typically, the exposure of the relief-forming precursor through a mask element is accomplished via floodwise exposure from a suitable UV radiation source. Exposure can be performed in the presence of atmospheric oxygen. Since complete optical contact has already been established, exposure in a vacuum is not necessary.

[0156] In manufacturing embossed imaging elements (e.g., flexographic printing plates), one side of the embossing precursor is typically first exposed to UV radiation for curing through its transparent substrate (referred to as "back exposure") to create a thin and uniform cured layer (e.g., embossed image valley 80) on the substrate side of the UV-sensitive layer. The embossing precursor is then exposed to UV radiation for curing through a mask containing a mask image, causing the UV-sensitive material to harden or cure in the unmasked (exposed) areas. The unexposed and uncured areas in the UV-sensitive layer can then be removed by a developing process (described below), leaving cured or hardened areas that define the printed surface of the embossed image (e.g., embossed image peak 75), having a predetermined pattern of the desired shape and size of the peaks 75 and valleys 80. Back exposure can be performed before or after the mask element establishes full optical contact with the embossed layer.

[0157] The suitable wavelength or wavelength range for UV radiation used for curing will depend on the electromagnetic susceptibility of the embossed layer. In some embodiments, the UV curing radiation may have one or more wavelengths ranging from at least 150 nm to up to and including 450 nm, or more typically from at least 300 nm to up to and including 450 nm. UV radiation sources for floodlighting or overall exposure include, but are not limited to, carbon arc lamps, mercury vapor arc lamps, fluorescent lamps, electronic flash devices, and photographic floodlights. UV radiation from mercury vapor lamps and sunlamps is particularly useful. Representative UV radiation sources include: a SYLVANIA 350 BLACKLIGHT fluorescent lamp (FR 48T12 / 350VL / VHO / 180, 115 watts) with a center emission wavelength of approximately 354 nm, available from Topbulb (East Chicago, Ind.); and a BURGESS EXPOSURE FRAME, model 5K-3343V511, with an ADDALUX 754-18017 lamp, available from Burgess Industries, Inc. (Plymouth, Mass.).

[0158] Other suitable UV radiation sources include plate-making machines, which can be used to expose the embossing precursor to radiation and to develop the imaged embossing material after radiation exposure. Examples of suitable plate-making machines include, but are not limited to, the KELLEIGH MODEL 310 plate-making machine available from Kelleigh Corporation (Trenton, NJ); and the GPP500F plate processor available from Global Asia Ltd. (Hong Kong).

[0159] The exposure time through the mask depends on the nature and thickness of the UV-sensitive layer of the embossing precursor, as well as the UV radiation source and intensity. For example, in one embodiment, a FLEXCEL-SRH plate precursor from Eastman Kodak Company can be mounted on a KELLEIGH MODEL 310 plate-making machine and exposed to UV-A radiation through a transparent support for approximately 20 seconds to prepare a thin and uniform cured layer on the support side of the embossing precursor. The embossing image forming assembly, consisting of the mask and the embossing precursor, can then be exposed to UV radiation through the mask for approximately 14 minutes. Thus, mask image information is transferred to the embossing precursor (e.g., a flexographic plate precursor).

[0160] Separate the mask from the UV-sensitive layer

[0161] Generally, the method described herein may also include removing the mask from full optical contact with the imaged relief-forming precursor after UV exposure and before development. Such removal can be performed by separating the top surface of the mask from the relief image. This can be accomplished using any suitable method, such as peeling the two elements apart. For example, this can be achieved by pulling the mask away from the imaged relief-forming precursor. The lecithin in the mask's base layer helps keep the mask body intact, allowing the imaged mask layer to adhere better to the base layer and the carrier sheet.

[0162] In some implementations, after UV exposure, the mask can be removed from the embossing layer by peeling the top surface of the mask from the embossing layer. This can be done by providing support to one of the mask or embossing precursors and then applying tension to the edge or end of the other (e.g., the embossing layer).

[0163] In some implementations, the mask can be delaminated from the embossing precursor, for example, by peeling the protective topcoat from the embossing layer. In these implementations, the mask is laminated onto the embossing layer. Then, after UV curing, the mask is peeled from the embossing layer. However, such peeling is not intended to indicate that the mask itself peels off, causing the different layers of the mask to peel off from each other. Here, the mask is peeled off from the embossing layer as a whole because lecithin helps the mask remain intact. Therefore, when the mask is peeled from the embossing layer, the mask itself is not peeled off and damaged. Similarly, the embossing layer is not peeled off from the embossing precursor.

[0164] In some implementations, the embossing precursor may include or omit a transparent release layer on the UV-sensitive layer. Therefore, the UV-sensitive embossing layer can be in direct contact with the top surface of the mask, allowing separation to directly detach the mask from the embossing layer.

[0165] In some implementations, the embossing layer can be applied with less force during the peeling of the mask and the imaged embossed image precursor (e.g., a flexographic printing plate precursor). The mask can be peeled off from the embossing precursor more quickly and completely, leaving almost no residual material. This effect provides faster development of the imaged embossed image precursor because there is little or no residual material to inhibit the development process. Because peeling is easier, the flexographic imaging assembly requires minimal handling and clamping force, and the process can be easily performed at room temperature. Therefore, heating may not be required during the curing process.

[0166] The flexographic printing plate assembly with a UV-sensitive layer comprises a unique combination of materials that allows for rapid and complete mask peeling. "Complete" means that at least 95%, preferably at least 98%, at least 99%, or 100% of the mask is peeled off, leaving little or no residual material. The composition of the UV-sensitive layer provides a peeling force relative to the mask containing the mask image of less than about 210 g / inch (82.7 g / cm), preferably less than about 150 g / inch (59.06 g / cm), preferably less than 75 g / inch (29.5 g / cm), preferably less than 60 g / inch (23.6 g / cm), preferably less than 50 g / inch (19.7 g / cm), and more preferably less than about 45 g / inch (17.71 g / cm).

[0167] In some embodiments, the mask containing the mask image is removed from the UV-exposed UV-sensitive relief layer of the flexographic printing plate precursor by peeling it off at the interface between the mask and the relief layer. This peeling process can be performed using a vacuum to hold it in place, as described in U.S. Patent No. 7,802,598. Then, at a rate of 2 to 10 cm / s and a peeling angle of 150-180°, a corner of the mask element is pulled away from the printing plate, thereby substantially pulling the imaged film back onto itself and keeping the imaged film close to the vacuum stage surface during continuous movement until the entire mask element is removed from the UV-sensitive layer of the printing plate. In practice of the invention, at least 95% by weight, preferably 100% by weight, of the dry mask element is removed in this operation; therefore, it can generally be said that the mask element is removed “completely” or substantially completely from the exposed radiation-curable layer of the precursor. “Completely” means that at least 95%, preferably at least 98%, at least 99%, or 100% of the mask is peeled off, leaving little or no residual material.

[0168] development

[0169] After removing the mask from the relief-forming layer, the imaged relief-forming precursor is typically developed using a suitable developer (or processing solution, or "rinsing solution") to form a relief image. The purpose of development is to remove unexposed (uncured) areas from the UV-sensitive layer, leaving the exposed (cured) areas that define the relief image, such as... Figure 1E As shown.

[0170] Development can be performed under known conditions, such as for a duration of at least 1 minute and up to and including 20 minutes, and at a temperature of at least 20°C and up to and including 32°C. The type of developing apparatus and the specific developer used will determine the specific developing conditions and can be adjusted by those skilled in the art.

[0171] In some cases, post-development processing of the relief image in the relief-forming precursor may be appropriate. Typical post-development processing includes drying the relief image to remove any excess solvent, and post-curing by exposing the relief image to curing radiation to induce further hardening or cross-linking. The conditions of these processes are well known to those skilled in the art. For example, the relief image can be blotted or wiped dry, or dried in a forced-ventilation or infrared oven. Drying times and temperatures are readily apparent to a skilled technician. Post-curing can be performed using the same type of UV radiation previously used to expose the relief-forming precursor through an imaged mask material.

[0172] If the embossed image surface remains sticky, a de-sticking (or "light finishing") operation can be used. Such treatments, for example, by treatment with bromide or chlorine solutions or exposure to UV or visible radiation, are well known to those skilled in the art.

[0173] The resulting embossed image depth can be at least 2% and up to and including 100% of the original thickness of the UV-sensitive layer (e.g., if the layer is disposed on a substrate). For flexographic printing plates, the maximum dry depth of the embossed image can be at least 150 μm and up to and including 1,000 μm, or typically at least 200 μm and up to and including 500 μm. For printed circuit boards, the UV-sensitive layer can be completely removed, whether in exposed or unexposed areas, to expose the underlying metal layer. In these components, the maximum depth of the embossed image depends on the dry thickness of the UV-sensitive layer. Advantageously, in any embodiment, the embossed image can have a shoulder angle greater than 50°.

[0174] Those skilled in the art can readily see the diverse applications of such inking elements across various industries, including flexographic printing on a wide range of packaging materials.

[0175] The imaging material of this invention for generating mask images can be used to prepare relief printing plates, such as flexographic and letterpress printing plates. The mask can also be used as a photomask. "A photomask is an opaque plate or film with apertures or transparent portions that allow light to pass through in a defined pattern. They are commonly used in photolithography, especially in the production of integrated circuits (ICs or 'chips')."

[0176] Example

[0177] Using the test target, the commercially available Kodak Flexcel NX TIL-R was imaged using a Kodak Flexcel NX wide imager at a roller speed of 95 RPM and a laser power setting of 25 W. This produced an optical density of 0.80 (15.84% transmittance) for the Flexcel NX DigiCap pattern. The optical density was measured using an X-Rite transmission densitometer. When the test target was in "DC-free NX" (DigiCap-free) mode and imaging was performed using the DC-free imager settings of the imager equipment, the OD or Dmin was displayed as 0.18 (66.07% transmittance).

[0178] The imaged TIL-R was then laminated onto a 1.14 mm Flexcel NXH photopolymer substrate using a Kodak Flexcel NX laminator. The laminated mask and photopolymer substrate interlayer / assembly were then exposed to a total of 27 joules / cm² using an "EVO 5" exposure apparatus. 2 The material is exposed to UV light to form an imaged relief material. Then, the photosensitive polymer, exposed image by image, is processed by flexographic equipment, dried, and post-exposed according to normal procedures to create a finished flexographic printing plate ready for flexographic printing. This plate reproduces all highlight dots down to 0.8% at 150 lpi.

[0179] The flexographic printing plate was manufactured according to the general procedure described in Comparative Example 1 above. The table below shows the composition of the improved mask elements in Examples 1-6 and compares them with Comparative Examples 1-4.

[0180]

[0181] Therefore, Examples 1-6 all demonstrate improved peel strength relative to at least some of the comparative examples. Examples 2-6 are all superior to Comparative Example 1. Notably, Comparative Examples 3-4 show other substances, such as Teflon particles or sunflower oil. Therefore, the examples all demonstrate suitable or improved OD and / or peel strength.

[0182] Figure 2 Includes a chart showing the peel strength (g / cm) of the different embodiments in the table above. As shown, Example 1 has suitable peel strength, while Examples 2-6 show significant improvements in peel strength. Therefore, lecithin in the basal layer can surprisingly and unexpectedly provide a significant improvement in peel strength and beneficial OD.

[0183] In the examples, other matrices besides nitrocellulose (NC) may be used, such as PCA, where PCA is a mixture of 70% by weight poly(methyl cyanoacrylate) and 30% by weight poly(ethyl cyanoacrylate). ATBC and lecithin (either powder or liquid) are described herein. Nitrocellulose (NC) is E150 from Scholel and 5 / 6 SS from Alchemix.

[0184] Summarize

[0185] Data shows that the improved mask can be removed more easily from the imaged embossing layer with less energy. Therefore, the mask can be peeled off faster, using less energy, and / or leaving less mask residue on the imaged embossing layer—an economic improvement that the improved mask provides. Less mask residue on the imaged embossing layer. This will increase the overall productivity of platemaking, as UV exposure time is a rate-limiting step for most practitioners who need to make multiple plates.

[0186] This invention reduces manufacturing costs through a simple design and by using lower-cost raw materials and / or reducing high-cost raw materials. Compared to TIL-R, the improved mask improves the mask's humidity / temperature sensitivity by reducing edge warping of the coating film. This will help reduce problems with loading the imaging film into the imaging device, as high edge warping can hinder the loading of the imaging film.

[0187] definition

[0188] As used herein, unless otherwise stated, the singular forms “a”, “an” and “the” are intended to include one or more components (i.e., include plural pronouns) when defining the various components of the substrate, the non-silver halide thermally ablation imaging layer, and other materials, layers, and compositions (e.g., developer or processing fluid) used in the practice of this invention.

[0189] Every term not explicitly defined in this application shall be understood to have a meaning generally accepted by those skilled in the art. If the interpretation of a term would render it meaningless or substantially meaningless in the context, then the term shall be interpreted to have a standard dictionary meaning.

[0190] Unless otherwise explicitly stated, the use of numerical values ​​within the various ranges specified herein is considered an approximation, as indicated by the word "approximately" preceding both the minimum and maximum values ​​within the ranges. In this way, variations slightly above and below the ranges can be used to achieve substantially the same results as values ​​within the ranges. Furthermore, these ranges are intended to be disclosed as continuous ranges, encompassing every value between the minimum and maximum values, as well as the endpoints of the ranges.

[0191] The non-halide silver ablation imaging layer is also referred to as the imaging layer in this paper.

[0192] Unless otherwise stated herein, the term "imageable material" is used to refer to articles prepared and used according to embodiments of the present invention. Such imageable materials may also be referred to as "mask films," "mask precursors," or "mask elements." Imageable materials can be converted into "mask elements" by suitable thermal (IR) imaging, which contain a mask image that can be used to form an embossed image according to the present invention.

[0193] Unless otherwise stated, all percentages are by weight.

[0194] As used herein, the term "embossing precursor" refers to any imageable element or imageable material in which an embossed image can be produced by exposure through a mask element. Examples of such embossing precursors are detailed below, but some embossing precursors include flexographic printing plate precursors, letterpress printing plate precursors, and printed circuit boards. U.S. Patent Application Publication 2005 / 0227182 (as described above) describes details of useful embossing materials, the disclosure of which is incorporated herein by reference. In that publication, embossing precursors are generally identified as "radiation-sensitive elements".

[0195] Unless otherwise stated, the terms "ablative" or "ablation" refer to thermal imaging using a laser that causes rapid, localized changes in the imaging layer of an imageable material, thereby causing material in the imaging layer to be ejected from the imaging layer. This differs from other material transfer or imaging techniques (such as melting, evaporation, or sublimation).

[0196] The terms "optical contact" and "perfect optical contact" have the same meaning and refer to two layers or two elements (such as in the case of mask and relief forming precursors) sharing an interface and being in close physical contact, such that there are essentially no air gaps or voids between the contact surfaces, thus providing an "airless interface." More precisely, two surfaces are defined as being in optical contact when the reflection and transmission properties of the interface between the two surfaces are described essentially entirely by Fresnel's law (which describes the reflection and transmission of light at refractive index boundaries).

[0197] Unless otherwise stated, the term “transparent” as used herein means the ability of a material or layer to transmit at least 95% of the projected (or incident) electromagnetic radiation, such as electromagnetic radiation with wavelengths of at least 200 nm to, including, 750 nm (i.e., UV and visible radiation commonly known in the art).

[0198] The “average dry thickness” of a given dry layer is usually the average of 10 different measurements of the dry cross-sectional image of that layer.

[0199] Those skilled in the art will understand that the functions performed in the processes and methods disclosed herein may be implemented in different orders. Furthermore, the steps and operations outlined are provided merely as examples, and some of these steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations without departing from the essence of the disclosed embodiments.

[0200] This disclosure is not limited to the specific embodiments described herein, which are intended as illustrative of various aspects. Many modifications and variations are possible without departing from its spirit and scope, as will be apparent to those skilled in the art. In addition to those listed herein, functionally equivalent methods and apparatus within the scope of this disclosure will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims and the full scope of their equivalents. It should be understood that this disclosure is not limited to specific methods, reagents, compound compositions, or biological systems, which are of course subject to variation. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0201] Regarding the use of virtually any plural and / or singular terms in this document, those skilled in the art may convert plural to singular or vice versa as needed by the context and / or application. For clarity, various singular / plural permutations may be explicitly described herein.

[0202] Those skilled in the art will understand that, generally, the terminology used herein, particularly in the appended claims (e.g., the body of the appended claims), is intended to be “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “including but not limited to,” etc.). Those skilled in the art will further understand that if there is an intention to introduce a particular number of recitations, such intention will be explicitly stated in the claims; and in the absence of such recitations, such intention does not exist. For example, for ease of understanding, the appended claims below may contain the use of the introductory phrases “at least one” and “one or more” to introduce the recitations. However, the use of such phrases should not be construed as implying that the introduction of a claim statement by the indefinite article “a(a)” or “an” limits any particular claim containing such an introduced claim statement to an embodiment containing only one such statement, even when the same claim includes the introductory phrase “one or more” or “at least one” and an indefinite article such as “a(a)” or “an” (e.g., “a(a)” and / or “an” should be interpreted as meaning “at least one” or “one or more”); the same applies to the use of definite articles used to introduce claim statements. Furthermore, even when a specific number of introduced claim statements is explicitly stated, those skilled in the art will recognize that such statements should be interpreted as meaning at least the number stated (e.g., a simple statement of “two statements” without other modifiers means at least two statements, or two or more statements). Furthermore, in cases where conventions such as "at least one of A, B, and C" are used, such structures are generally intended to have the meaning of the convention as understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, systems having only A, only B, only C, having A and B, having A and C, having B and C, and / or systems having A, B, and C, etc.). In cases where conventions such as "at least one of A, B, or C" are used, such structures are generally intended to have the meaning of the convention as understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" will include, but is not limited to, systems having only A, only B, only C, having A and B, having A and C, having B and C, and / or systems having A, B, and C, etc.). Those skilled in the art will further understand that, whether in the specification, claims, or drawings, any transitional words and / or phrases presenting two or more alternative terms should be understood to consider the possibility of including one, any one, or both of the terms.For example, the phrase “A or B” would be understood to include the possibility of “A” or “B” or “A and B”.

[0203] Furthermore, if any feature or aspect of this disclosure is described according to the Markush Group, those skilled in the art will recognize that this disclosure is therefore also described according to any single member or subgroup of the Markush Group.

[0204] As those skilled in the art will understand, for any and all purposes, such as providing a written description, all scopes disclosed herein also cover any and all possible subscopes and combinations thereof. Any listed scope can be readily identified as sufficiently descriptive and enabling the same scope to be decomposed into at least two equal halves, three equal parts, four equal parts, five equal parts, ten equal parts, etc. As a non-limiting example, each scope discussed herein can be readily decomposed into a lower third, a middle third, and an upper third, etc. As those skilled in the art will also understand, all language such as “up to”, “at least”, etc., includes the referenced number and refers to a scope that can subsequently be decomposed into subscopes as described above. Finally, as those skilled in the art will understand, a scope includes each individual member. Thus, for example, a group having 1-3 units means a group having 1, 2, or 3 units. Similarly, a group having 1-5 units means a group having 1, 2, 3, 4, or 5 units, and so on.

[0205] As can be understood from the foregoing, various embodiments of this disclosure have been described herein for illustrative purposes, and various modifications can be made without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed herein are not intended to be restrictive, and the true scope and spirit are indicated by the following claims. All references cited herein are incorporated herein by reference in their entirety.

Claims

1. A mask element for flexographic printing, the mask element comprising: Transparent polymer carrier sheet; The substrate layer on the transparent polymer carrier sheet, wherein the substrate layer comprises a polymer adhesive and lecithin; as well as The imaging layer on the substrate layer, wherein the imaging layer comprises a non-silver halide thermally ablation material, the non-silver halide thermally ablation material comprising an ablation polymer binder and a colorant.

2. The mask element of claim 1, wherein the lecithin is present in the substrate layer at about 0.1% to about 25% by weight.

3. The mask element of claim 2, wherein the lecithin is present in the substrate layer at about 5% to about 20% by weight.

4. The mask element of claim 1, wherein the lecithin is derived from a powder or liquid source.

5. The mask element of claim 4, wherein the lecithin is uniformly distributed throughout the substrate layer.

6. The mask element of claim 1, wherein the lecithin is a mixture of at least two glycerophospholipids.

7. The mask element of claim 6, wherein the lecithin comprises at least two of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, or phosphatidic acid.

8. The mask element of claim 7, wherein the lecithin may comprise: About 20% by weight to about 50% by weight of phosphatidylinositol; About 20% by weight to about 50% by weight of phosphatidylcholine; About 5% by weight to about 50% by weight of phosphatidylethanolamine; Other phospholipids, approximately 5% by weight to approximately 25% by weight; and The remaining amount of oil, carbohydrates, sterols, and water may be used to form 100% by weight of lecithin.

9. The mask element of claim 7, wherein the lecithin may comprise: Approximately 30% to approximately 40% by weight of plant-derived oils; About 20% to about 25% by weight of phosphatidylinositol; About 19% by weight to about 25% by weight of phosphatidylcholine; Phosphatidylethanolamine: approximately 8% by weight to approximately 20% by weight; Other phospholipids, approximately 5% to approximately 15% by weight; About 4% to about 6% by weight of free carbohydrates; About 1% by weight to about 6% by weight of sterols; and Optionally, the remaining water is used to form 100% by weight of lecithin.

10. The mask element of claim 1, wherein the colorant comprises carbon black pigment in the imaging layer, wherein the carbon black pigment is present in an amount of about 30% to about 70% by weight.

11. The mask element of claim 1, further comprising a transparent top coating layer on the imaging layer.

12. The mask element of claim 1, further comprising at least one of the following: The plasticizer in the substrate layer, wherein the plasticizer in the substrate layer is present in an amount of about 0.01% by weight to about 40% by weight; or The plasticizer in the imaging layer, wherein the plasticizer in the imaging layer is present in an amount of about 5% to about 40% by weight.

13. The mask element of claim 12, wherein the plasticizer and the lecithin together in the base layer are in the range of 5% to 30% by weight.

14. The mask element of claim 13, wherein at least one of the following is satisfied: The plasticizer in the base layer is selected from tributyl acetylglucosyl citrate, polyester, polyether, or a combination thereof; or The plasticizer in the imaging layer is selected from tributyl acetylglucosamine, polyether, or a combination thereof.

15. The mask element of claim 1, further comprising an infrared dye in the imaging layer, the infrared dye being present in an amount of about 0.1% to about 15%.

16. A mask comprising: The mask element of claim 1, wherein the mask comprises: The imaging region in the imaging layer, wherein the imaging region has an optical aperture substantially free of the ablationable polymer binder and the colorant; and The non-imaging region in the imaging layer, wherein the non-imaging region has the ablationable polymer binder and the colorant.

17. The mask of claim 16, wherein the optical density of the mask in the non-imaging region is about 3.5 to about 3.

9.

18. The mask of claim 16, wherein the mask has a peeling force of less than 205 g / inch (80.70 g / cm).

19. The mask of claim 16, wherein the mask has a peeling force of about 40 g / inch (16.1 g / cm) to about 210 g / inch (82.68 g / cm).

20. A relief forming component comprising: The mask as described in claim 16; as well as The relief forming precursor is in complete optical contact with the mask.

21. A method for preparing a mask element as claimed in claim 1, comprising: Form the transparent polymer carrier sheet; The substrate layer is formed on the transparent polymer carrier sheet; as well as The imaging layer is formed on the substrate layer, wherein the imaging layer includes the lecithin.

22. A method for preparing the mask as described in claim 16, comprising: Provide a mask element that has no imaging region in the imaging layer; as well as The mask element is imaged with infrared light to form the imaging region in the imaging layer.

23. A method for forming a relief image, comprising: An embossing assembly is provided, the embossing assembly including a mask and an embossing precursor in full optical contact with the mask, wherein the mask includes: Transparent polymer carrier sheet; A base layer on the transparent polymer carrier sheet, wherein the base layer comprises a polymer binder and lecithin; and The imaging layer on the substrate layer, wherein the imaging layer comprises a non-silver halide thermally ablation material, the non-silver halide thermally ablation material comprising an ablation polymer and a colorant; The imaging region in the imaging layer, wherein the imaging region has an optical aperture substantially free of the ablationable polymer and the colorant; and The non-imaging region in the imaging layer, wherein the non-imaging region has the ablationable polymer and the colorant; The relief forming layer of the relief forming precursor is exposed to curing ultraviolet radiation through the mask to form an imaged relief forming layer, in which the ultraviolet exposed areas form aggregated areas and the unexposed areas form non-aggregated areas. Remove the mask from the imaged relief forming layer; and The imaged relief layer is developed by removing the non-aggregated areas in the imaged relief layer, thereby forming an relief image element with a relief image.

24. The method of claim 23, wherein the peeling force for removing the mask from the imaged relief forming layer is less than 205 g / inch (80.70 g / cm).

25. The method of claim 23, wherein the mask has a peeling force of about 40 g / inch (16.1 g / cm) to about 210 g / inch (82.68 g / cm) for removal from the imaged relief forming layer.

Images