Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/02—Engraving; Heads therefor
  • B41C1/04—Engraving; Heads therefor using heads controlled by an electric information signal
  • B41C1/05—Heat-generating engraving heads, e.g. laser beam, electron beam
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/12—Printing plates or foils; Materials therefor non-metallic other than stone, e.g. printing plates or foils comprising inorganic materials in an organic matrix
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/1053—Imaging affecting physical property or radiation sensitive material, or producing nonplanar or printing surface - process, composition, or product: radiation sensitive composition or product or process of making binder containing
  • Y10S430/1055—Radiation sensitive composition or product or process of making
  • Y10S430/106—Binder containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/1053—Imaging affecting physical property or radiation sensitive material, or producing nonplanar or printing surface - process, composition, or product: radiation sensitive composition or product or process of making binder containing
  • Y10S430/1055—Radiation sensitive composition or product or process of making
  • Y10S430/106—Binder containing
  • Y10S430/108—Polyolefin or halogen containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/145—Infrared
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/146—Laser beam
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/165—Thermal imaging composition

Definitions

• the invention relates to laser-engravable flexographic printing elements with relief-forming elastomeric layers containing syndiotactic 1,2-polybutadiene, processes for producing relief-printing elements from the laser-engravable flexographic printing elements and the use of syndiotactic 1,2-polybutadiene as a binder in the elastomeric relief-forming layers.
• WO 93/23252 discloses laser-engravable, flexographic printing elements comprising, on a support, a laser-engravable, elastomeric layer containing at least one thermoplastic elastomer as a binder, and methods for producing flexographic printing plates.
• the laser-engravable elastomer layer amplified thermochemically by heating or photochemically by irradiation with actinic light and then the printing relief engraved with a laser.
• EP-A 0 076 588 discloses photowettable flexographic printing elements containing a mixture of 30 to 70% syndiotactic 1,2-polybutadiene with a degree of crystallinity of 5 to 20%, a content of 1,2-linked units of 85% and a molecular weight above 100,000 g / mol and 70 to 30% cis-l, 4-polyisoprene.
• the printing elements are exposed imagewise with UV light and developed by washing out the uncrosslinked areas with an organic solvent.
• No. 4,517,278 discloses a flexographic printing plate which is melt-pressed from a photosensitive molding composition, the molding composition containing syndiotactic 1,2-polybutadiene (I) which is swollen with the solution of an ethylenically unsaturated monomer (II) and a photoinitiator (III).
• (I) has an average molecular weight of 10,000 to 300,000 g / mol, a content of 1,2-linked polybutadiene units of at least 80% and a degree of crystallinity of 10 to 30%.
• (II) is an ester of methacrylic acid with a C -C 20 alkanol and (III) is benzoin or a benzoin alkyl ether.
• pellets of (I) are swollen in a solution of (II) and then melt-pressed into 0.1 to 10 mm thick plates. This process can only be carried out discontinuously and is complex.
• the printing plates produced in the examples require xylene as a detergent for development.
• Shore A hardnesses of 60 to 65 can only be achieved by using larger amounts of non-crosslinking plasticizers such as vinyl ethers or phthalates. These form enamel edges during laser engraving.
• the object of the invention is to provide improved laser-engravable flexographic printing elements.
• the object is achieved by a laser-engravable flexographic printing element comprising, on a flexible carrier, an elastomeric relief-forming, laser-engravable, thermally or photochemically crosslinkable layer containing as a binder at least 5% by weight of syndiotactic 1,2-polybutadiene with a content of 1,2-linked butadiene - Units from 80 to 100%, a degree of crystallinity from 5 to 30% and an average molecular weight of 20,000 to 300,000 g / mol.
• laser-engravable is to be understood to mean that the elastomeric relief-forming layer has the property of absorbing laser radiation, in particular the radiation from an IR laser, so that it is removed at those locations where it is exposed to a laser beam of sufficient intensity
• the layer is preferably vaporized or thermally or oxidatively decomposed without melting and its decomposition products are removed from the layer in the form of hot gases, vapors, smoke or small particles.
• the elastomeric relief-forming layers produced using the special syndiotactic 1,2-polybutadiene as a binder result in very sharp and high-resolution relief elements during laser engraving.
• Laser engraving does not form any enamel edges, but only weak deposits that can be removed mechanically or by simple post-treatment with water or alcohol.
• the elastomeric relief-forming layers can be photocrosslinked extremely quickly by irradiation with UV-A light.
• the relief-forming elastomeric, laser-engravable layer preferably contains
• component F (f) 0 to 30% by weight, preferably 0 to 10% by weight, of further conventional additives as component F.
• the elastomeric relief-forming layer contains syndiotactic 1,2-polybutadiene with a content of 1,2-linked butadiene units of 80 to 100%, a degree of crystallinity of 5 to 30% and an average molecular weight of 20,000 to 300,000 g / mol.
• the content of 1,2-linked butadiene units is preferably 90 to 95%, particularly preferably 90 to 92%, the degree of crystallinity from 10 to 30%, particularly preferably 15 to 30% and the average molecular weight from 80,000 to 200,000 g / mol, particularly preferably from 100,000 to 150,000 g / mol.
• the elastomeric relief-forming layer may contain further binders as component A2.
• binders are the known three-block copolymers of the SIS or SBS type, which can also be completely or partially hydrogenated.
• Elastomeric polymers of the ethylene / propylene diene type, Ethylene / acrylic acid rubbers or elastomeric polymers based on acrylates or acrylate copolymers can be used.
• Further examples of suitable polymers are disclosed in DE-A 22 15 090, EP-A 084 851, EP-A 819 984 or EP-A 553 662. Two or more different additional binders can also be used.
• the elastomeric relief-forming layer contains, as component B, crosslinking oligomeric plasticizers which have reactive groups in the main chain and / or reactive lateral and / or terminal groups.
• Suitable plasticizers are, for example, polybutadiene oils, polyisoprene oils, allyl citrates and other synthetic plasticizers containing allyl groups with a viscosity of 500 to 150,000 mPas at 25 ° C., which may have functional end groups such as OH groups.
• Unsaturated fatty acids and their derivatives such as oleic acid, linoleic acid, linolenic acid, undecanoic acid, erucic acid and their derivatives, for example their esters, and unsaturated terpenes and their derivatives are also suitable.
• polybutadiene oils and polyisoprene oils mentioned are preferred as crosslinking oligomeric plasticizers. These preferably have a viscosity of 500 to 100,000 mPas, particularly preferably 500 to 10,000 mPas at 25 ° C.
• Polybutadiene oils from Chemetall, Hüls and Elf Atochem, for example, are suitable. These have a molecular weight of approx. 1000 to approx. 3000 g / mol, a content of 1,2-linked units of frequently 40 to 50%, often only approx. 20% or 1%, a flash point of 170 ° C. up to 300 ° C and a viscosity of 700 to 100,000 mPas at 25 ° C.
• cross-linking oligomeric plasticizers By using the cross-linking oligomeric plasticizers, melting phenomena during laser engraving are avoided particularly efficiently. Furthermore, a particularly good ink transfer of the printing relief layers is achieved, for example with water-based or alcohol-based printing inks or UN-curable printing inks.
• the elastomeric relief-forming layer optionally contains ethylenically unsaturated monomers.
• the ethylenically unsaturated monomers are advantageous, but not necessary, since the elastomeric relief-forming layer can crosslink even in its absence.
• the monomers should be compatible with the binders and should have at least one polymerizable, ethylenically unsaturated double bond. Suitable monomers generally have a boiling point of more than 100 ° C. at atmospheric pressure and a molecular weight of up to 3,000 g / mol, preferably up to 2,000 g / mol.
• Esters or amides of acrylic acid or methacrylic acid with monofunctional or polyfunctional alcohols, amines, amino alcohols have proven particularly advantageous or hydroxyethers and esters, styrene or substituted styrenes, esters of fumaric or maleic acid or allyl compounds.
• suitable monomers are butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isobornyl methacrylate,
• Dioctyl fumarate and N-dodecyl maleimide Mixtures of different monomers can also be used.
• the elastomeric relief-forming layer optionally contains photoinitiators and / or thermally decomposing initiators.
• the presence of photoinitiators is not necessary, but is advantageous since the elastomeric relief-forming layer can be crosslinked photochemically even in the absence of photoinitiators. If the elastomeric relief-forming layer is to be thermally crosslinked, the presence of thermally decomposing initiators in amounts of 0.1 to 5% by weight, based on the sum of components A to F, is generally necessary.
• the elastomeric relief-forming layer can also be crosslinked photochemically and thermally, it being possible for component D to contain photoinitiators and / or thermally decomposing initiators.
• Suitable photoinitiators are benzoin or benzoin derivatives, such as methylbenzoin or benzoin ether, benzene derivatives such as benzil ketals, acylarylphosphine oxides, acylarylphosphinic acid esters and multinuclear quinones, without the enumeration being restricted to this.
• Those photoinitiators which have a high absorption between 300 and 450 nm are preferably used.
• Suitable thermally decomposing initiators are, for example, peroxy esters, such as t-butyl peroctoate, t-amyl peroctoate, t-butyl peroxy isobutyrate, t-butyl peroxymaleic acid, t-amyl perbenzoate, di-t-butyl diperoxyphthalate, t-butyl perbenzoate, t-butyl peracetate or 2,5-butyl peracetate ) -2,5-dimethylhexane, certain diperoxyketals such as l, l-di (t-amylperoxy) cyclohexane, l, l-di (t-butylperoxy) cyclohexane, 2,2-di (t-butylperoxy) butane or ethyl-3 , 3-di (t-butylperoxy) butyrate, certain dialkyl peroxides such as di-t-butyl per
• the elastomeric relief-forming layer can contain absorbers for laser radiation.
• the presence of the absorbers is advantageous, but not necessary, provided the binders already absorb laser radiation of a suitable wavelength, for example that of a CO 2 laser.
• Suitable absorbers for laser radiation have a high absorption in the range of the laser wavelength.
• absorbers are suitable which have a high absorption in the near infrared and in the longer-wave NIS range of the electromagnetic spectrum.
• Such absorbers are particularly suitable for absorbing the radiation from powerful ⁇ d-YAG lasers (1064 nm) and from IR diode lasers, which typically have wavelengths between 700 and 900 nm and between 1200 and 1600 nm.
• Suitable absorbers for laser radiation in the infrared spectral range are highly absorbing dyes such as phthalocyanines, ⁇ aphthalocyanines, cyanines, quinones, metal complex dyes such as dithiolenes or photochromic dyes.
• Suitable absorbers are inorganic pigments, in particular intensely colored inorganic pigments such as chromium oxides, iron oxides, carbon black or metallic particles.
• Finely divided soot types with a particle size between 10 and 50 nm are particularly suitable as absorbers for laser radiation.
• suitable absorbers for laser radiation are iron-containing solids, in particular intensely colored iron oxides.
• iron oxides are commercially available and are usually used as color pigments or as pigments for magnetic recording.
• Suitable absorbers for laser radiation are, for example, FeO, goethite (alpha-FeOOH), Akaganeit (beta-FeOOH), lepidocrocite (gamma-FeOOH), hematite (alpha-Fe 2 O 3 ), maghemite (gamma-Fe 2 O 3 ), magnetite (Fe 3 O 4 ) or Berthollide.
• doped iron oxides or mixed oxides of iron with other metals can be used.
• Examples of mixed oxides are Umbra Fe O 3 xn MnO 2 or Fe x Al (1-x) OOH, in particular various spinel black pigments such as Cu (Cr, Fe) 2 O 4 , Co (Cr, Fe) 2 O 4 or Cu ( Cr, Fe, Mn) 2 O.
• Examples of dopants are, for example, P, Si, Al, Mg, Zn or Cr. Such dopants are usually added in small amounts as part of the synthesis of the oxides to control particle size and shape.
• the iron oxides can also be coated. Such coatings can be applied, for example, in order to improve the dispersibility of the particles. These coatings can consist, for example, of inorganic compounds such as SiO and / or A1OOH.
• Organic coatings for example organic adhesion promoters such as
• Aminopropyl (trimethoxy) silane can be applied.
• Particularly suitable absorbers for laser radiation are FeOOH, Fe 2 O 3 and Fe 3 O 4, most preferably Fe O 4.
• the elastomeric relief-forming layer can contain further additives as component F.
• Other additives are non-crosslinking plasticizers, fillers, dyes, compatibilizers or dispersing agents.
• the flexographic printing elements according to the invention have the usual layer structure and consist of a flexible dimensionally stable support, optionally an elastomeric underlayer, one or more elastomeric relief-forming, laser-engravable layers, the various layers being able to be connected by adhesive layers, and one optionally with a detackification layer (release -layer) coated protective film.
• the flexographic printing element according to the invention comprise a flexible, dimensionally stable support.
• suitable flexible, dimensionally stable supports for laser-engravable flexographic printing elements are plates, foils and conical and cylindrical tubes (sleeves) made of metals such as steel, aluminum, copper or nickel or of plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polycarbonate, optionally also fabrics and nonwovens, such as glass fiber fabrics and composite materials, for example made of glass fibers and plastics.
• Dimensionally stable carrier films such as polyester films, in particular PET or PEN films, are particularly suitable as dimensionally stable carriers.
• Flexible metallic supports that are so thin that they can be bent around printing cylinders are particularly advantageous. On the other hand, they are also dimensionally stable and so thick that the carrier is not kinked during the production of the laser-engravable element or the assembly of the finished printing plate on the printing cylinder.
• the elastomer relief-forming, laser-engravable layer is present on the carrier, optionally on an elastomeric underlayer.
• the elastomeric relief-forming, laser-engravable layer can also have a multilayer structure. These laser-engravable, cross-linkable partial layers can be of the same, approximately the same or different material composition. Such a multilayer structure, in particular a two-layer structure, is sometimes advantageous because it enables surface properties and layer properties to be optimized independently of one another in order to achieve an optimal printing result.
• the laser-engravable flexographic printing element can, for example, have a thin laser-engravable top layer, the composition of which was selected with a view to optimum color transfer, while the composition of the layer underneath was selected with regard to optimum hardness or elasticity.
• the thickness of the elastomeric relief-forming, laser-engravable layer or of all relief-forming layers together is generally between 0.1 and 7 mm. The thickness is selected by the person skilled in the art depending on the intended use of the printing plate.
• the laser-engravable flexographic printing elements according to the invention can optionally comprise further layers.
• an underlayer With such an underlayer, the mechanical properties of the relief printing plates can be changed without the properties of the actual printing relief layer being influenced.
• So-called elastic substructures serve the same purpose and are located on the side of the dimensionally stable support opposite the laser-engravable layer.
• Further layers can be adhesive layers that connect the support with layers lying above or different layers with one another.
• the laser-engravable flexographic printing element can be protected against mechanical damage by a protective film, for example made of PET, which is located on the top layer in each case and which is removed before laser engraving.
• the protective film can also be siliconized or provided with a suitable stripping layer to make it easier to remove.
• the laser-engravable flexographic printing element can, for example, by dissolving or dispersing all components in a suitable solvent and pouring them onto one Carrier are manufactured.
• several layers can be cast onto one another in a manner known per se.
• the individual layers can be cast onto temporary supports, for example, and the layers can then be connected to one another by lamination.
• photochemically crosslinkable systems can be produced by extrusion and / or calendering. In principle, this technology can also be used for thermally crosslinkable systems, provided that only those components are used that do not crosslink at the process temperature.
• Relief printing elements are obtained from the laser-engravable flexographic printing elements according to the invention by thermal and / or photochemical crosslinking of the elastomeric relief-forming layer and engraving of a printing relief.
• the invention thus also relates to a method for producing a relief printing element with the steps
• the elastomeric relief-forming, laser-engravable layer can be crosslinked photochemically and / or thermally.
• the photochemical crosslinking takes place in particular by irradiation with short-wave visible or long-wave ultraviolet light.
• radiation of higher energy such as short-wave UV light or X-rays, or - with suitable sensitization - also longer-wave light is in principle suitable.
• Electron radiation is also particularly suitable for crosslinking.
• the thermal crosslinking is generally brought about by heating the flexographic printing element to temperatures of generally 80 to 220 ° C., preferably 120 to 200 ° C. over a period of 2 to 30 minutes.
• Particularly suitable for laser engraving are CO 2 lasers with a wavelength of 10640 nm, but also Nd-Y AG lasers (1064 nm) and IR diode lasers or solid-state lasers, which typically have wavelengths between 700 and 900 nm and between 1200 and 1600 nm exhibit.
• lasers with shorter wavelengths can also be used, provided the laser is of sufficient intensity.
• a frequency-doubled (532 nm) or frequency-tripled (355 nm) Nd-YAG laser can also be used, or eximer lasers (eg 248 nm).
• eximer lasers eg 248 nm.
• the image information to be engraved is transferred directly from the lay-out computer system to the laser apparatus.
• the lasers can be operated either continuously or in pulsed mode.
• the relief layer is removed very completely by the laser, so that intensive post-cleaning is generally not necessary. If desired, the printing plate obtained can still be cleaned. Such a cleaning step removes layer components which have been detached but which may not yet be completely removed from the plate surface. As a rule, simple treatment with water or methanol is completely sufficient.
• Layers are produced analogously to the process described in Example 1, with the difference that 116 g of JSR RB 810, 24 g of Lithene PH, 16 g of lauryl acrylate, 2.4 g of Lucirin® BDK and 1.6 g of Kerobit® TBK at 110 ° C. be dissolved in 240 g of toluene.
• Layers are produced analogously to the process described in Example 1, with the difference that 116 g of JSR 810, 16 g of Lithene PH, 16 g of lauryl acrylate, 8 g of hexanediol diacrylate, 2.4 g of Lucirin® BDK and 1.6 g of Kerobit® TBK are added 110 ° C be dissolved in 240 g of toluene.
• Layers are produced analogously to the process described in Example 1, with the difference that 108 g of JSR RB 810, 16 g of Lithene PH, 24 g of hexanediol divinyl ether, 8 g of hexanediol diacrylate, 2.4 g of Lucirin® BDK and 1.6 g of Kerobit® TBK be dissolved in 240 g of toluene at 110 ° C.
• Layers are produced analogously to the process described in Example 1, with the difference that 92 g JSR RB 810, 32 g Kraton® D-1161, 16 g Lithene PH, 8 g Lauryl acrylate, 8 g hexanediol diacrylate, 2.4 g Lucirin® BDK and 1.6 g Kerobit® TBK at 110 ° C in 240 g toluene.
• JSR RB 810 16 g Plastomoll® DNA, 16 g Lithene PH and 1.6 g Kerobit® TBK and 16 g Printex® A are kneaded for 15 minutes in a laboratory kneader at a predetermined temperature of 100 ° C.
• the compound thus obtained (158.4 g) is dissolved in 240 g of toluene at 110 ° C. After the solution has cooled to 60 ° C., 1.6 g of dicumyl peroxide are added. After homogenization by stirring, the solution obtained is applied with the aid of a doctor knife to a plurality of transparent PET films in such a way that a homogeneous dry layer thickness of 1.20 mm is obtained.
• the layers produced in this way are first dried at 25 ° C. for 18 hours and finally at 50 ° C. for 3 hours. The dried layers are then laminated onto an equally large piece of a second PET film. After a storage period of one day, the layer is thermally crosslinked at 160 ° C. for 15 minutes and characterized as described below.
• Comparative Example A 124 g Kraton® D-1161, 16 g Lithene® PH, 16 g lauryl acrylate, 2.4 g Lucirin® BDK and 1.6 g Kerobit® TBK are dissolved in 240 g toluene at 110 ° C.
• the homogeneous solution obtained is cooled to 70 ° C. and applied to a plurality of transparent PET films using a doctor knife in such a way that a homogeneous dry layer thickness of 1.20 mm is obtained.
• the layers produced in this way are first dried at 25 ° C. for 18 hours and finally at 50 ° C. for 3 hours. The dried layers are then laminated onto an equally large piece of a second PET film. After a storage period of one day, the layer is crosslinked photochemically according to the procedure explained below and characterized as described below.
• Layers are produced analogously to the process described in comparative example A, with the difference that 124 g of Kraton® D-1161, 16 g of Lithene® PH, 16 g of lauryl acrylate, 2.4 g of Lucirin® BDK and 1.6 g of Kerobit® TK 110 ° C be dissolved in 240 g of toluene.
• the photochemical crosslinking of the example layers described was carried out with a nyloflex® F III imagesetter from BASF Drucksysteme GmbH, by first removing the transparent PET protective film and then irradiating the entire area with UVA light without vacuum for the duration of the exposure series.
• the transparent PET protective film was first removed and the layer was then heated for the duration of the crosslinking at the selected temperature without inertization.
• the layers obtained from the examples and comparative examples were each photochemically or thermally crosslinked in steps of one minute crosslinking time.
• the exposure time at which the breaking stress was maximum was determined as the optimal crosslinking time t opt and an uncrosslinked layer was crosslinked with this optimal crosslinking time for all examples and comparative examples.
• the following properties were determined from the layers crosslinked in this way and the corresponding uncrosslinked layers as a reference:
• a laser system with a rotating outer drum (Meridian Finesse, ALE) was used for the laser engraving tests, which was equipped with a CO 2 laser with an output power of 250 W.
• the laser beam was focused on a diameter of 20 ⁇ m.
• the flexographic printing elements to be engraved were stuck to the drum with adhesive tape and the drum was accelerated to 250 rpm.
• the letter A Helvetica font, font size 24 pt
• the resolution was 1270 dpi.
• a section of the engraved letter A was photographed using a light microscope at 32x magnification.
• two lines with a width of 20 ⁇ m were engraved into the respective material at a distance of 20 ⁇ m. Scanning electron microscope images were taken of the negative line pairs.
• RS edge sharpness sharpness of the surface edges 1: No irregularities or breakouts 2: Only occasional wave formation or breakouts 3: Repeated breakouts and deformations with low amplitude 4: Numerous irregularities, breakouts, deformations
• TD depth definition shape and uniformity of the relief depths 1: depths sharply delimited, uniform flanks 2: depths slightly deformed, flanks weakly grooved
• Figures 1.1 - 1.8 and 2.1 - 2.8 show the photographic and scanning electron microscope images on which the assessment is based.
• FIG. 1.1 is a photograph of the "A” section - Example 1.
• FIG. 1.2 is a photograph of the "A” section - Example 2
• 1.8 is a photograph of the "A" section - comparative example B.
• Table 2 summarizes the assessments of the features mentioned and the arithmetic mean of all features.
• the superior quality of the relief elements produced by laser engraving in flexographic printing elements based on syndiotactic 1,2-polybutadiene (examples) in comparison to conventional flexographic printing elements (comparative examples) can be recognized.
• the finest relief elements such as the negative line pairs shown can be reproduced in high quality.
• the quality of larger engraved relief elements, as shown by way of example in the section of the letter A is significantly better for flexographic printing elements based on syndiotactic 1,2-polybutadiene, since strong melting phenomena or material deposits on the printing surface are avoided.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Plasma & Fusion (AREA)
• Manufacturing & Machinery (AREA)
• Printing Plates And Materials Therefor (AREA)
• Laminated Bodies (AREA)
• Adhesive Tapes (AREA)

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• 2001
  • 2001-04-18 DE DE10118987A patent/DE10118987A1/de not_active Withdrawn
• 2002
  • 2002-04-15 EP EP02740469A patent/EP1381511B1/de not_active Expired - Lifetime
  • 2002-04-15 DE DE50202172T patent/DE50202172D1/de not_active Expired - Lifetime
  • 2002-04-15 AT AT02740469T patent/ATE288358T1/de not_active IP Right Cessation
  • 2002-04-15 US US10/475,216 patent/US7101653B2/en not_active Expired - Lifetime
  • 2002-04-15 JP JP2002581196A patent/JP2004523401A/ja active Pending
  • 2002-04-15 WO PCT/EP2002/004162 patent/WO2002083418A1/de not_active Ceased

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