Sleeve for holding a printing plate

Abstract

A sleeve (200) for use with a printing plate (100), said sleeve having a sleeve axis, wherein the sleeve comprises a cylindrical inner layer (220) configured to be mounted on an adapter sleeve (300) or on a printing mandrel (400), a cylindrical outer layer, and a support material arranged between the inner layer and the outer layer and interconnecting the inner layer and the outer layer, said support material comprising a plurality of support elements (240).

Description

[0001] Sleeve for holding a printing plate

[0002] FIELD

[0003] The field of the invention relates to a sleeve, such as a printing sleeve for mounting a printing plate, preferably a flexographic printing plate, or an adaptor sleeve for mounting a printing sleeve, and to methods for producing such sleeves.

[0004] BACKGROUND

[0005] Flexographic printing is a printing process, where a printing ink is transferred from the raised portions of the printing plate onto a substrate. Flexographic printing uses flexible printing plates allowing printing on many different types of substrates (paper, cardboard, films). Alongside offset printing and gravure printing, flexographic printing is one of the most important printing processes in the packaging industry.

[0006] With the flexographic printing machines, a distinction is made between multi-cylinder and centralcylinder printing machines. In the case of a central-cylinder printing machine, the individual printing units are arranged around a central cylinder over which the substrate web is passed. In the case of multi-cylinder printing machines, the individual printing units are arranged in series. The printing units consist of a cylinder assembly with a mandrel and a printing sleeve, an engraved roll for inking the printing form, and an ink trough from which the printing ink goes onto the engraved roll.

[0007] At its most simple, the cylinder assembly consists of a mandrel onto which the flexographic printing plate is adhered. A great advantage of flexographic printing over other printing processes is its format variability. Through the use of mandrels with different diameters, it is possible for different formats to be printed. A term used by the skilled person is that of the repeat length. The repeat length corresponds to the printed length on one complete rotation of the cylinder assembly. Changing over the heavy steel cylinders, however, takes time. Accordingly, flexographic printing machines are nowadays available with which the repeat length can be altered more simply by means of adaptor sleeves. The adaptor sleeve is arranged onto the mandrel. The wall thicknesses of customary adaptor sleeves typically range from 7 mm to 300 mm. A printing sleeve is arranged on the adaptor sleeve, said printing sleeve carrying the printing plate, usually pre -mounted. Adaptor sleeves and printing sleeves are nowadays generally also referred to as sleeves. Sleeves are often manufactured of plastic. They are significantly lighter than corresponding steel cylinders, and can therefore be changed over much more easily in the printing machine.

[0008] The construction of a sleeve is usually as follows (from inside to outside): a multilayered inner layer comprising a thin inner layer of GRP material (GRP = glass-fiber reinforced plastic), a thin compressible layer and an outer layer of GRP material; an intermediate layer of variable thickness; and an outer layer. The layered structure of the inner layer allows the sleeve to be expanded by means of compressed air. This inner layer customarily has a thickness of 1 mm up to 4 mm. The intermediate layer may be a polyurethane foam layer with a thickness of several mm to several cm. The function of this layer is to build up the layer thickness, or to produce the desired repeat length. The outer layer may be a thin GRP layer, to ensure the mechanical and chemical stability of the sleeve.

[0009] In order to ensure that an adaptor sleeve is easily engaged, the mandrel may have air bores which emit a flow of compressed air. As a result of the compressed air, an air cushion is built up, thereby expanding the internal diameter of the adaptor sleeve, and the adaptor sleeve glides over the mandrel. If the supply of air is halted, the adaptor sleeve clamps to the mandrel and is fixed firmly on it. To allow the printing sleeve to be pulled onto the adaptor sleeve, the adaptor sleeve likewise customarily contains an air conduction system. In the prior art there are two known systems here. Either the compressed air is guided directly from the mandrel (bridge system), or there is a separate air connection to one of the end faces of the adaptor sleeve (Airo system).

[0010] SUMMARY

[0011] An object of embodiments of the invention is manufacturing of a stable, lightweight sleeve with good mechanical stability and a low thermal expansion coefficient.

[0012] According to a first aspect of the invention there is provided a sleeve for use with a printing plate, such as a printing sleeve or an adaptor sleeve. The sleeve comprises a cylindrical inner layer, a support material arranged on said cylindrical inner layer and optionally a cylindrical outer layer. The cylindrical inner layer is configured to be mounted on an adaptor sleeve and / or on a printing mandrel. Typically, the cylindrical inner layer is a compressible layer allowing the sleeve to be expanded by compressed air. The support material comprises biobased and / or recycled material. By using a biobased and / or recycled material the necessary thickness and strength can be given to the sleeve in a sustainable manner. Further such materials can be chosen to be lightweight and sufficiently rigid.

[0013] In the context of this specification, the term “biobased material” refers to a material intentionally made from substances and / or materials derived from living (or once-living) organisms. Examples of biobased materials are a polyester made of bio-based alcohols, polyester comprising plant fibers, a polymer made of biological monomers (e.g. PLA), a wood based material, a wood composite, a biobased polyurethane, plant and / or animal fibers (e.g. cotton, wool, flax, silk), natural polymers (e.g. cellulose, starch, lignin, etc.), leather, paper, cardboard, etc.

[0014] Optionally the biobased material may be impregnated or treated, for example coated, to limited or avoid spores, fungus, bugs, water uptake, swelling, etc. For example, when the biobased material is wood, the wood may be coated with a coating configured to limit or avoid water uptake and swelling.

[0015] In the context of this specification, the term “recycled material” refers to a material which originates from a waste material and is recycled to generate a recycled material. Examples of suitable recycled materials are recycled thermoplastic polymers which are extrudable, such as PP, ABS, PET.

[0016] Preferably, the inner layer is multilayered and comprises a compressible layer and a base layer. Optionally, it may comprise a further base layer, so that the compressible layer is inserted between two base layers. For example, the compressible layer may be inserted in between a lower and upper base layer, preferably a lower and upper fiber reinforced sublayer. Preferably the base layer is a fiber reinforced layer, for example a polyester fiber reinforced layer, but it is also possible to use non- fiber-reinforced layers for the base layer, such as a nickel layer or a foil. Preferably, the compressible layer has a hardness between 25 and 65 Shore A measured according to ISO 7619-1:2010.

[0017] Preferably, the biobased and / or recycled material comprises fibers, preferably wood fibers, and more preferably the fibers are oriented fibers oriented in a direction which on average is substantially perpendicular to the sleeve axis. In this manner, the mechanical stability and the thermal expansion coefficient in the fiber direction can be improved.

[0018] Optionally, the biobased and / or recycled material may comprise multiple layers. In such embodiments, the orientation of the fibers in the different layers may be different. For example, in one layer the fibers may be oriented fibers oriented in a direction which on average is substantially perpendicular to the sleeve axis and in another layer the fibers may be oriented fibers oriented in a direction which on average is substantially parallel to the sleeve axis. In a more specific example, a layer with fibers oriented in a direction which on average is substantially parallel to the sleeve axis is inserted between two layers with fibers oriented in a direction which on average is substantially perpendicular to the sleeve axis. In that manner the advantage of strength (due to the perpendicular orientation) may be combined with the less expensive option of having parallel fibers.

[0019] Preferably, the support material comprises one or more support elements, more preferably a plurality of support bars, forming spacer elements between the inner layer and the outer layer. By arranging multiple bars parallel to each on the inner layer a stable support layer can be formed. However, a bar shape is not essential, and other shapes, such as a checkerboard structure may also be used. Also, a support element may be arranged in a spiral like manner around the inner layer.

[0020] Preferably, the one or more support elements are made of a biobased and / or recycled material, more preferably wood or wood composites, for example wood with polymers.

[0021] In an exemplary embodiment a so-called pressboard comprising paper scraps or a wood board comprising wood scraps may be used.

[0022] In an exemplary embodiment, the one or more support elements have a higher compressive strength in a first direction, preferably a direction perpendicular to the sleeve axis, than in a second direction, said second direction being preferably perpendicular to the first direction, more preferably parallel to the sleeve axis. In this manner, a sleeve with a stable outer diameter can be obtained.

[0023] Preferably, the support elements are a plurality of support elements positioned in an equidistant manner in a circumferential direction and / or in a direction parallel to the sleeve axis. In this manner any forces exerted on the sleeve can be well distributed.

[0024] Preferably, a maximum distance between adjacent support elements as measured at an outer surface of the support elements is below 10 mm. The distance between adjacent support elements may increase between an inner surface adjacent to the inner layer and an outer surface of the support elements. At the level of the inner layer the distance may be zero or small, for example between 1 and 8 mm. Optionally, the support elements are arranged in a plurality of layers and / or in a plurality of segments and preferably all support elements are interconnected, for example by arranging a connecting layer between the multiple layers or by arranging connecting elements between adjacent segments.

[0025] Preferably, the support elements have a compressive strength higher than 0,5 MPa, preferably higher than 1 MPa, measured according to DIN 52185 - 1976-09. For example, when wood is used as the support material, the compressive strength may even be above 30 MPa. Preferably, the compressive strength is measured in a direction which corresponds to the radial direction perpendicular on the axial direction of the sleeve, when arranged on the inner layer of the sleeve.

[0026] Preferably, the support elements have a density of 0,1 g / cm3to 0,8 g / cm3, more preferably a density of 0,2 g / cm3to 0,5 g / cm3.

[0027] Optionally, a space between adjacent support elements is filled with a gas, a liquid and / or a solid material or combinations thereof. When filled with gas, the sleeve is sealed to avoid or limit the escape of gas. The sleeve may comprise a gas impermeable material arranged to avoid the escape of gas. Preferably, the sealing is achieved by including in the inner layer and the outer layer an inner and outer gas impermeable layer, respectively, as well as gas impermeable end layers at end faces of the sleeve, said end layers preferably interconnecting the inner and outer gas impermeable layer.

[0028] Optionally, the gas, the liquid and / or the solid material in the space between at least two support elements is above ambient pressure. This may further improve the mechanical stability. For example, the solid material may comprise a foam, a polymer, a glass, a powder, fibers, a gel, a interpenetrating polymer network, a polyurethane, an epoxy, and / or a fiber reinforced material or combinations thereof. The solid material may comprise or consist of biobased and / or recycled material.

[0029] Preferably, at least one of the inner layer and the outer layer comprises or consists of a fiber reinforced material. Optionally, also the support material may comprise a fiber reinforced material.

[0030] In an exemplary embodiment, the outer layer has a Shore D hardness between 70 and 95 measured according to ISO 7619-1:2010. This will result in a so-called hard coated sleeve. To achieve such hardness the outer layer may be or comprise a fiber reinforced layer. For example, the outer layer may be a fiber reinforced polyurethane layer or a multilayered structure comprising a barrier layer for example made of a fiber reinforced resin and a top layer for example made of polyurethane. In the latter example, the barrier layer may have a thickness between 1 and 4 mm and the top layer may have a thickness between 1 and 3 mm. In yet another example the outer layer is not fiber reinforced.

[0031] In another exemplary embodiment, the outer layer comprises a compressible layer having a Shore A hardness between 30 and 80 measured according to ISO 7619-1:2010. This will result in a so-called compressible sleeve. The compressible layer may be for example a polyurethane layer, typically not fiber reinforced.

[0032] Preferably, the support material comprises at least one support substrate, more preferably at least one flexible support substrate. The term “flexible” in this context must be understood in that the flexible support is sufficiently flexible for it to be wrapped around the inner layer without breaking. Preferably, the at least one support substrate interconnects the plurality of support elements. This is however not a requirement. Thus, the support substrate may function as a flexible connection element or not. The at least one support substrate may extend as at least one cylindrical layer between the inner and outer layer. For example, a support substrate may be arranged against the inner layer and / or against the outer layer and / or in between the inner and outer layer with support elements on either side of the support substrate. Such a support substrate may have, for example, a thickness between 0.01 and 2 mm, preferably between 0,01 and 1,5 mm, more preferably between 0,01 and 1 mm.

[0033] Optionally, the inner and / or the outer layer is electrically conductive, wherein optionally the inner and the outer layer are electrically connected to each other. In this manner, electrostatic discharges may be conducted by the sleeve to ground. The electrical connection may comprise a metal, a semiconductor, a conductive polymer and / or a conductive resin (one or two component system) or combinations thereof.

[0034] Preferably, the water content of the support material, and in particular the support elements is below 20%, preferably below 10%.

[0035] Preferably, a thickness of the inner layer is between 0.7 and 15 mm, more preferably between 0.7 and 4 mm; and / or a thickness of the outer layer is between 3 and 7 mm; and / or a thickness of a layer containing the support material between the inner and the outer layer is between 5 and 600 mm, more preferably between 5 and 50 mm.

[0036] Preferably, an inner diameter of the sleeve is between 57 and 580 mm and the outer diameter of the sleeve is between 65 and 588 mm. The biobased and / or recycled material may comprise for example balsa wood, Kiri wood, eucalyptus, bamboo, willow, birch, Poplar, Silver fir, Spruce, Pine, Pasture, Douglas fir, Alder, Lime tree, Larch, Pine, Trembler, Bluebell tree, Black alder, Silver birch, Weeping willow, Maple -leaved plane tree, White mulberry 'Fruitless', common horse chestnut, Norway maple, and preferably comprises: balsa wood, Kiri wood, Spruce, or combinations thereof. More preferably, the support elements comprise any of the above mentioned wood types or combinations thereof, more preferably balsa wood, Kiri wood and / or Spruce.

[0037] Preferably, the biobased and / or recycled material has a thermal expansion coefficient below 50 * 106 / K, preferably below 30 * 106 / K, more preferably below 10 * 106 / K according to ASTM E228- 22.

[0038] Preferably, the biobased and / or recycled material has a humidity below 30%, preferably below 25%, more preferably below 10% according to DIN EN 13182-3:2005-06.

[0039] Preferably, the support elements comprise the same length, width and / or thickness. However, it is also possible to combine different support elements, for example support elements of a different shape and / or material.

[0040] The support elements may have for example a rectangular, prismatic, triangular, hexagonal, polygonal, circular, elliptic, trapezoidal, rhombic, arc segmental, square, rectangle, isosceles trapezoid, right-angled trapezoid, parallelogram, rhombus, kite quadrilateral cross section in the plane perpendicular to the sleeve axis, and preferably have a trapezoidal cross section with the smaller side towards the inner layer. The support elements may have for example a rectangular, prismatic, triangular, hexagonal, polygonal, circular, elliptic, trapezoidal, rhombic, arc segmental, square, rectangular, isosceles trapezoid, right-angled trapezoid, parallelogram, rhombus, kite quadrilateral cross section in the plane parallel to the sleeve axis, preferably rectangular.

[0041] Preferably, looking in a circumferential direction of the sleeve, between 8 and 1000 support elements are arranged next to each other.

[0042] Preferably, the support elements have a width and a thickness measured in a radial direction of the sleeve, and wherein a ratio of the thickness to the width is between 1:50 - 10, preferably between 1:20 - 5, more preferably between 1:8 - 3. For example, the support elements may have a thickness between 5 mm and 40 mm and a width between 10 mm and 50 mm. Preferably, the support elements have a thickness, measured in a radial direction of the sleeve, in a range of 1 to 100 mm, more preferably 5 to 50 mm. Preferably, the support elements have a length measured in an axial direction of the sleeve, in the range of 1 mm to 5000 mm, and optionally each support element may be made by gluing smaller pieces together. Preferably, the support elements have a width of 1 to 100 mm.

[0043] According to a further aspect there is provided a method for producing a sleeve for use with a printing plate, said method comprising: providing a cylindrical inner layer configured to be mounted on an adaptor sleeve and / or on a printing mandrel, arranging a support material comprising a biobased and / or recycled material on the cylindrical inner layer, and, optionally, arranging a cylindrical outer layer over said support material.

[0044] Preferably, the support material comprises one or more support elements and / or one or more support substrates, which may have any one or more of the properties described above for the sleeve. The support elements may be interconnected via the support substrate prior to arranging the support material on the inner layer. For example, the support elements may be fixed to a support substrate first, and then the support substrate may be fixed to the inner layer according to a predetermined pattern. In this way, the support material may be arranged in a simple manner to the inner layer.

[0045] Preferably, the support material is attached to the inner layer and / or the outer layer by any one of the following: adhering, such as gluing, screwing, stapling, riveting, clamping, melting, clipping, or combinations thereof. Further any one of the following may be used: hooks, clamps and clips, velcro and adhesive tape, suction cups, cords and chains, rings, S-hooks, screws and dowels.

[0046] Preferably, an adhesive layer is applied on the cylindrical inner layer prior to the step of arranging the support material on the inner layer, and wherein the arranging comprises rolling the cylindrical inner layer with adhesive over the support material. When the support material comprises a plurality of support elements, the support elements may be arranged according to a pattern on a flat surface, and the cylindrical inner layer equipped with an adhesive may be rolled over said support elements.

[0047] Optionally, during the attachment of the support material, and in particular the one or more support elements, the support material is kept in place by a temporary fixation means. Preferably the temporary fixation means comprises a cord, a wire, a band, a mesh, a network, a suction means, a clamp, a hook, a woven, a nonwoven or combinations thereof, which is optionally wound around the one or more support elements on the sleeve.

[0048] Optionally, the one or more support elements are shaped, preferably ground, such that the support elements, when arranged on the cylindrical inner layer, have an outer surface coinciding with a substantially cylindrical outer surface.

[0049] In an exemplary embodiment, the support elements comprise a plurality of elongate bars arranged parallel to each other, more preferably in an equidistant manner.

[0050] Optionally, the support material comprises at least one support substrate, preferably a barrier layer with fiber reinforced resin. Preferably, the at least one support substrate is applied on the one or more support elements and / or below the one or more support elements and / or between two layers of support elements.

[0051] According to another aspect there is provided a sleeve for holding a printing plate. The sleeve comprises a cylindrical inner layer configured to be mounted on an adapter sleeve or on a printing mandrel, a cylindrical outer layer, and a support material arranged between the inner layer and the outer layer and interconnecting the inner layer and the outer layer, said support material comprising a plurality of support elements.

[0052] By using a plurality of support elements, it is possible to obtain a stable, lightweight sleeve which can easily be manufactured. As compared to a structure where the complete area between the inner and outer layer is filled with a filling support material, the use of multiple support elements at a distance of each other allows reducing the weight whilst still providing adequate mechanical stability. The manufacturing can be relatively easy because the support elements can easily and precisely be mounted onto the inner layer.

[0053] Preferably, the support elements comprise fibers which are oriented in a direction substantially perpendicular to the sleeve axis.

[0054] Preferably, the support elements are positioned in an equidistant manner, wherein a minimum distance measured at an outer surface of the inner layer is larger than 1mm, wherein preferably a maximum distance between adjacent support elements is smaller than 10 mm. Preferably, a minimum distance between adjacent support elements, measured at an inner surface of the outer layer, is larger than 1 mm, preferably larger than 3 mm, more preferably larger than 5 mm, wherein preferably a maximum distance between adjacent support elements, measured at an inner surface of the outer layer, is smaller than 50 mm. It is noted that in such embodiments, the distance between adjacent support elements, measured at the outer surface of the inner layer may be smaller than at the inner surface of the outer layer, or even zero.

[0055] In an exemplary embodiment, the support elements comprise multiple support elements arranged at a distance of each other seen in a direction parallel to an axis of the sleeve.

[0056] In an exemplary embodiment, the support elements are elongate elements extending in a circumferential direction of the sleeve, wherein optionally an elongate element thereof extends over at least 30% of a circumference of the inner layer, for example over at least 50% or even over the entire circumference.

[0057] Preferably, the support elements are connected to each other. Preferably, the support material comprises at least one flexible connection element interconnecting the plurality of support elements. By interconnecting the support elements with a flexible connection element, the support elements can be easily arranged around the cylindrical inner layer. For example, the cylindrical inner layer may be rolled over the interconnected support element to arrange the interconnected support elements on the inner layer. Therefore, one object of the flexible connection element is to improve the manufacturing process of the sleeve, since the support elements interconnected by the flexible connection element can be wound easily around the inner layer.

[0058] In an exemplary embodiment a flexible connection element of said at least one flexible connection element may located at a distance of the inner layer and the outer layer. Alternatively or in addition, a flexible connection element may be located on the inner layer and / or on the outer layer.

[0059] Preferably, the at least one flexible connection element comprises a flexible connection substrate. The flexible connection substrate preferably has a thickness between 0.1 mm and 5 mm, more preferably between 0.5 mm and 2 mm. For example, the at least one flexible connection element may comprise a mat, a film, a mesh, a woven or non-woven material and / or a porous material or combinations thereof. Preferably, the support elements are positioned on, preferably attached to, at least one side of the flexible connection substrate. For example, the support elements may be attached to the flexible connection substrate by any one or more of the following: adhesive, nails, staples, adhesive tape, etc.

[0060] Optionally, the at least one flexible connection element comprises an adhesive or the at least one flexible connection element is meltable. For example, the flexible connection substrate may have an adhesive side on which the support elements are fixed.

[0061] Preferably, the support elements are connected by the at least one flexible connection element in a pattern, preferably a regular pattern, for example a pattern of parallel stripes, a cubic pattern, a hexagonal pattern, a checkerboard pattern or a spiral pattern.

[0062] Preferably, the at least one flexible connection element comprises a biobased and / or recycled material. Thus, in some exemplary embodiments both the support elements as well as the at least one flexible connection element may be made of biobased and / or recycled material.

[0063] Preferably, the at least one flexible connection element, and in particular the at least one flexible connection substrate, extends over substantially the full length of the sleeve.

[0064] Optionally, the support elements are hollow, partially hollow or porous, wherein the support elements may be gas filled. In this manner the weight of the support elements and thus of the sleeve, may be reduced.

[0065] The support elements may comprise or be made of any one of the following materials or a combination thereof: rigid polymer, foam, ceramic, porous material, fiber reinforced material, metal, wood, wood composites, such as wood with polymers, fibers, wherein said support elements are preferably made of a biobased material and / or a recycled material. Any of the above specified biobased and / or recycled materials specified above for the first aspect may also be used for the other aspects.

[0066] In an exemplary embodiment, the support elements are less compressible in a first direction, preferably a direction perpendicular to the sleeve axis, than in a second direction, preferably a direction perpendicular to the first direction, more preferably a direction parallel to the sleeve axis. The support elements may have a cross section in the plane perpendicular and / or parallel to the sleeve axis which has any one of the following shapes: rectangular, prismatic, triangular, hexagonal, polygonal, circular, elliptic, trapezoidal, arc segmental, isosceles trapezoid, right-angled trapezoid, parallelogram, rhombus kite quadrilateral.

[0067] Preferably, the support elements are attached to the flexible connection element, for example by an adhesive, or mechanically fixed (for example stapled), or by melting, preferably by an expanding, foaming adhesive.

[0068] The flexible connection element may comprise paper, polymers, polymer resins, natural fibers, synthetic fibers, glass fibers, carbon fibers and / or metal fibers or combinations thereof. Preferably, the flexible connection element comprises or is made of biobased and / or recycled materials.

[0069] Optionally, the flexible connection element may be perforated, for example in order to be permeable for an adhesive used to fix the support elements. The adhesive may comprise or consist of a melt adhesive, an urethane adhesive, an epoxy adhesive, a silicon based adhesive and / or a biobased adhesive (for example starch) or combinations thereof, preferably polyester, polyurethane or wood glue.

[0070] Optionally, the flexible connection element is penetrable for a liquid, in particular an adhesive such as one of the exemplary adhesives specified in the paragraph above. For example, the flexible connection element may have a porosity of at least 1% and / or a size of the openings higher than 0,1 mm, average pore size. For example, the flexible connection element may be a carbon fabric having an openness between 1% and 10% measured by DIN 53865.

[0071] Preferably, the flexible connection element has a basis weight between 1 g / m2to 1000g / m2.

[0072] Optionally, the flexible connection element is hydrophobic.

[0073] Optionally, the flexible connection element is at least partially soluble in the adhesive in order to improve the strength of the connection.

[0074] Other preferred features, such as the dimensions of the support elements, of the inner layer and of the outer layer, the conductive properties of the inner and outer layer, the structure of the inner and outer layer, etc., may be as described above for the first aspect. According to a further aspect, there is provided a method to produce a sleeve for use with a printing plate. The method comprises the steps of : providing a cylindrical inner layer configured to be mounted on an adapter or on a printing mandrel, providing a plurality of support elements interconnected to each other, arranging the plurality of interconnected support elements on said inner layer, optionally filling voids between the support elements, optionally attaching further layers to the support elements, arranging a cylindrical outer layer around the plurality of support elements.

[0075] By interconnecting the support elements prior to being arranged on the cylindrical inner layer, a precise positioning of the support elements on the inner layer can be obtained.

[0076] Preferably, the support elements are connected to each other by means of at least one flexible connection element, wherein more preferably the at least one flexible connection element is attached to an outer surface of the cylindrical inner layer. The at least one flexible connection element may have any one of the properties specified above.

[0077] The attaching of the support elements to the at least one flexible connection element may be performed by gluing, screwing, stapling, riveting, partial or complete melting and cooling of the connection element, partial melting and cooling of the support elements or combinations thereof.

[0078] Optionally, an adhesive is arranged on the inner layer and the attaching of the support elements is done by rolling the cylindrical inner layer with the adhesive over the interconnected support elements. In that manner, the support elements may be arranged on the inner layer in a very robust and simple manner, whilst ensuring a precise and stable positioning of the support elements on the inner layer.

[0079] The method may further comprise any one or more of the following steps: grinding the support elements, gluing the support elements, fixing the support elements, for example with a tape, cord, film or cloth, until an adhesive applied to the support elements is firm.

[0080] A further aspect of the invention concerns the use of the sleeve according to any of the embodiments described above in a printing device.

[0081] A further aspect of the invention concerns an assembly comprising the sleeve according to any of the previous embodiments, a printing mandrel and optionally a further cylinder, for example an adaptor sleeve if the sleeve is a printing sleeve or a printing sleeve if the sleeve is an adaptor sleeve. Embodiments of the invention are also defined by any one of the following clauses:

[0082] 1. A sleeve (200) for use with a printing plate (100), said sleeve having a sleeve axis and comprising: a cylindrical inner layer (220) configured to be mounted on an adapter sleeve (300) and / or on a printing mandrel (400), a support material (250) arranged on said cylindrical inner layer, an optional cylindrical outer layer (210) arranged on said support material; wherein the support material comprises biobased and / or recycled material.

[0083] 2. The sleeve according to clause 1 , wherein the biobased and / or recycled material comprises any one or more of the following: wood, recycled thermoplastic polymer, biobased polyurethane.

[0084] 3. The sleeve according to clause 1 or 2, wherein the support material comprises or consists of a biobased material which is impregnated and / or treated, such as coated with a coating configured to limit water uptake.

[0085] 4. The sleeve according to any one of the previous clauses, wherein the inner layer is multilayered and comprises a compressible layer and a base layer, preferably a fiber reinforced base layer, wherein preferably the compressible layer has a hardness between 25 and 65 Shore A according to ISO 7619-1:2010.

[0086] 5. The sleeve according to any one of the previous clauses, wherein the biobased and / or recycled material comprises fibers, preferably wood fibers, wherein preferably the fibers are oriented fibers oriented in a direction which on average is substantially perpendicular to the sleeve axis.

[0087] 6. The sleeve according to any one of the previous clauses, wherein the support material comprises one or more support elements (240), preferably a plurality of support bars, forming spacer elements between the inner layer and the outer layer.

[0088] 7. The sleeve according to clause 6, wherein the one or more support elements are made of a biobased and / or recycled material, preferably wood or wood composites, for example wood with polymers.

[0089] 8. The sleeve according to clause 6 or 7, wherein the support elements are a plurality of support elements positioned in an equidistant manner.

[0090] 9. The sleeve according to any of the clauses 6 - 8, wherein a maximum distance (dmax) between adjacent support elements as measured at an outer surface of the support elements is below 10 mm.

[0091] 10. The sleeve according to any of the clauses 6 - 9, wherein the support elements are arranged in a plurality of layers and / or a plurality of segments which are interconnected. 11. The sleeve according to any of the clauses 6 - 10, wherein the support elements have a compressive strength higher than 0,5 MPa, preferably higher than 1 MPa.

[0092] 12. The sleeve according to any of the clauses 6 -l l, wherein the support elements have a density of 0,1 g / cm3 to 0,8 g / cm3.

[0093] 13. The sleeve according to any of the clauses 6 - 12, wherein a space between adjacent support elements is filled with a gas, a fluid and / or a solid material or combinations thereof.

[0094] 14. The sleeve according to the previous clause, further comprising at least one gas impermeable material configured to avoid gas escaping from the space.

[0095] 15. The sleeve according to any of the previous clauses, wherein at least one of the inner layer, the outer layer and the support material comprises or consists of a fiber reinforced material.

[0096] 16. The sleeve according to any of the previous clauses, wherein the outer layer has a Shore D hardness between 70 and 95.

[0097] 17. The sleeve according to any one of the clauses 1 - 15, wherein the outer layer comprises a compressible layer having a Shore A hardness between 30 and 80.

[0098] 18. The sleeve according to any of the previous clauses, wherein the support material comprises at least one support substrate, preferably at least one flexible substrate.

[0099] 19. The sleeve according to clause 6 and 18, wherein the at least one support substrate (230) interconnects the support elements.

[0100] 20. The sleeve according to clause 18 or 19, wherein the at least one support substrate (230) extends as at least one cylindrical layer between the inner layer and the outer layer.

[0101] 21. The sleeve according to any of the previous clauses, wherein the inner and / or the outer layer is electrically conductive, wherein optionally the inner and the outer layer are electrically connected to each other.

[0102] 22. The sleeve according to any of the previous clauses, wherein a thickness of the inner layer is between 0.7 and 15 mm, preferably between 0.7 and 4 mm; and / or wherein a thickness of the outer layer is between 3 and 7 mm; and / or wherein a thickness of a layer containing the support material between the inner and the outer layer is between 5 and 600 mm.

[0103] 23. A method for producing a sleeve (200) for holding a printing plate (100), said method comprising: providing a cylindrical inner layer (220) configured to be mounted on an adapter (300) or on a printing mandrel (400), arranging a support material comprising a biobased and / or recycled material on the cylindrical inner layer, optionally, arranging a cylindrical outer layer over said support material. 24. The method according to clause 23, wherein the support material is attached to the inner layer and / or the outer layer by any one of the following: adhering, such as gluing, screwing, stapling, riveting, clamping, melting, clipping, or combinations thereof.

[0104] 25. The method according to any one of the clauses 23 - 24, wherein during the attachment of the support material, the support material is kept in place by a temporary fixation means, wherein preferably the temporary fixation means comprises a cord, a wire, a band, a mesh, a network, a suction means, a clamp, a hook, a woven, a nonwoven or combinations thereof, which are optionally wound around the support material on the sleeve.

[0105] 26. The method according to any one of the clauses 23 - 25, wherein the support material comprises one or more support elements.

[0106] 27. The method according to clause 26, wherein the one or more support elements are shaped, preferably ground, such that the support elements, when arranged on the cylindrical inner layer, have an outer surface coinciding with a substantially cylindrical outer surface.

[0107] 28. The method according to any of the clauses 23 - 27, wherein an adhesive layer is applied on the cylindrical inner layer prior to the step of arranging the support material on the inner layer, and wherein the arranging comprises rolling the cylindrical inner layer with adhesive over the support material.

[0108] 29. The method of any of the clauses 23 - 28, wherein the support material comprises a plurality of support elements arranged according to a pattern on a flat surface, and wherein the cylindrical inner layer with adhesive is rolled over said support elements.

[0109] 30. The method of the previous clause, wherein the support elements comprise a plurality of elongate bars arranged parallel to each other, preferably in an equidistant manner.

[0110] 31. The method according to any one of the clauses 23 - 30, wherein the support material comprises at least one support substrate, preferably a layer with fiber reinforced resin.

[0111] 32. The method of clause 26 and clause 31 , wherein the at least one support substrate is applied on the one or more support elements and / or below the one or more support elements and / or between two layers of support elements.

[0112] 33. Use of the sleeve according to any of the clauses 1 - 22 in a printing device.

[0113] 34. An assembly comprising the sleeve according to any of the clauses 1 - 22, a printing mandrel and / or a further cylinder, for example an adaptor sleeve.

[0114] BRIEF DESCRIPTION OF THE FIGURES

[0115] The accompanying drawings are used to illustrate presently preferred non-limiting exemplary embodiments of the exposure unit of the present invention. The above and other advantages of the features and objects of the invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings, in which:

[0116] Figure 1 illustrates installing a printing plate on a printing sleeve and mounting the printing sleeve with the printing plate directly on a mandrel.

[0117] Figure 2 illustrates installing a printing plate on a printing sleeve and mounting the printing sleeve on an adaptor sleeve before being installed on a mandrel.

[0118] Figure 3A shows a side view of a mandrel.

[0119] Figure 3B shows a cross-sectional view of the mandrel of figure 3A along section line AA.

[0120] Figure 4 shows a cross-sectional side view of the mandrel of figure 3B and a printing sleeve with a printing plate.

[0121] Figure 5 shows a cross-sectional side view of the mandrel of figure 3B and a printing sleeve with a printing plate wherein an adaptor sleeve is installed between the printing sleeve and the mandrel. Figure 6 is a schematic cross section of an exemplary embodiment of a printing sleeve;

[0122] Figure 7 is a schematic perspective view of another exemplary embodiment of a printing sleeve;

[0123] Figure 8 is a schematic cross section of another exemplary embodiment of a printing sleeve;

[0124] Figure 9 is a schematic perspective view of another exemplary embodiment of a printing sleeve;

[0125] Figure 10 is a schematic top view of an exemplary embodiment of the support material before being arranged on the inner layer;

[0126] Figure 11 is a schematic top view of another exemplary embodiment of the support material before being arranged on the inner layer;

[0127] Figure 12 is a schematic perspective view of another exemplary embodiment of the support material before being arranged on the inner layer;

[0128] Figures 13A and 13B are schematic cross section views of further exemplary embodiments of the support material before being arranged on the inner layer;

[0129] Figure 14 is a schematic perspective view of another exemplary embodiment of a printing sleeve;

[0130] Figures 15 A and 15B are schematic cross section views of further exemplary embodiments of the support material before being arranged on the inner layer;

[0131] Figure 16 is a schematic cross section of an embodiment of a sleeve.

[0132] DETAILED DESCRIPTION OF EMBODIMENTS

[0133] Figure 1 shows a printing plate 100 and a double-sided tape 150. The figure further shows a sleeve 200. Printing plate 100 can be installed on an outer surface of the sleeve 200 as shown. The sleeve 200 is mounted on a printing mandrel 400 as shown in Figure 1 or on an adaptor sleeve 300 as shown in Figure 2. Printing plate 100 can be affixed on the sleeve 200 via any suitable attachment, preferably via an adhesive double-sided tape 150. The adhesive double-sided tape preferably has substantially the same size as the bottom of the printing plate 150. In addition or instead of the double-sided tape, the sleeve 200 and / or the printing plate 100 may be provided with adhesive means, such as an adhesive layer (not shown).

[0134] The sleeve 200 with the printing plate 100 can be installed on an outer surface of the adaptor sleeve 300 as shown in Figure 2 or directly on an outer surface of the mandrel 400 as shown in Figure 1. Installing the sleeve 200 is preferably occasioned by providing a gas cushion, such as an air cushion, between the inner surface of the sleeve 200 and the outer surface of the adaptor sleeve 300 or the outer surface the mandrel 400. The gas cushion facilitates the installation of the sleeve 200 on the mandrel 400 or on the adaptor sleeve 300. As shown in figure 1 , the mandrel 400 may have a gas inlet 401 and one or more gas outlets 402 at the circumferential surface of the mandrel to provide the gas cushion between the sleeve 200 and the mandrel 400 (see e.g. figure 4). If an adaptor sleeve 300 is used, the adaptor sleeve 300 is preferably provided with one or more gas guides. To provide the gas cushion, air or another gas can be used which can be supplied via inlet 401 of the mandrel 400.

[0135] The installation and affixing of the printing plate 100 to the sleeve 200 is typically performed in a mounting station (not shown) to provide easy access. Afterwards, the sleeve 200 mounted on a printing mandrel 400 to form assembly 600 is brought and installed into a printing apparatus (not shown). Printing plate 100 can be provided with any printing pattern to transfer ink therewith. Figure 1 further shows assembly 600 in the lower left corner. The assembly 600 includes the printing plate 100, the sleeve 200 and the mandrel 400.

[0136] As illustrated in Figure 2, an adaptor sleeve 300 may be arranged in between the sleeve 200 and the mandrel 400. The sleeve 200 is mounted on adaptor sleeve 300 before being installed on mandrel 400. Afterwards, an assembly 700 is formed including the printing plate 100 affixed on the sleeve 200, adaptor sleeve 300 and mandrel 400. This assembly 700 is then suitable for installation in a printing apparatus.

[0137] Figure 3A shows a side view of a mandrel 400 with an outer surface 410 and mounting flanges. Figure 3B shows a cross-sectional view along section line AA of Figure 3A. The mandrel 400 typically has a cylindrical body serving as the main structure of the mandrel 400. The body can be manufactured from steel or aluminum. Mandrel 400 further has mounting flanges 412a, 412b located at a first end and second end of the mandrel 400. The mounting flanges 412a, 412b provide secure mounting points to install the mandrel 400 in a printing apparatus (e.g. a printing press). The mandrel 400 and / or the flanges 412 may include any fastening mechanisms to ensure proper alignment and fixation. The mandrel 400 may have a gas inlet 401 configured to receive gas from an external gas supply (not shown). The gas may be pushed through an opening 402 in the body of the mandrel 400 to the outer surface 410 of the mandrel via one or more gas outlets 401.

[0138] Figure 4 shows a cross-sectional side view of the mandrel of Figure 3B and a sleeve 200 with a printing plate 100. The printing plate 100 is preferably affixed to the sleeve 200 by aid of tape 150. The sleeve 200 has an inner surface configured to be mounted on the mandrel 400. By supplying a gas cushion (not shown), e.g. via air outlet 402 of the mandrel 400, the sleeve 200 can be easily mounted on the mandrel 400 by sliding the sleeve 200 over the outer surface of the mandrel 400. When the gas cushion is removed, the sleeve 200 is fixed on the mandrel 400.

[0139] Figure 5 illustrates a similar configuration but with an adaptor sleeve 300 having one or more gas guides 350 arranged between the mandrel 400 and the sleeve 200. The gas guide 350 acts as a passage with an inlet 301 and outlet 302. Inlet 301 is arranged to receive gas from outlet 402 of the mandrel 400. Outlet 302 provides the gas cushion at the outer surface 310 of the adaptor sleeve 300. In this manner the sleeve 200 may slide easily over the outer surface of the adaptor sleeve 300.

[0140] Figure 6 illustrates schematically a first embodiment of a sleeve for use with a printing plate. It is noted that the sleeve of Figure 6 is indicated with reference numeral 200 which refers to a printing sleeve in the figures described above, but the sleeve of Figure 6 could also be an adaptor sleeve 300. The Sleeve 200 comprises a cylindrical inner layer 220 configured to be mounted on an adapter sleeve 300 or on a printing mandrel 400, a cylindrical outer layer 210, and a support material 250 arranged between inner layer 220 and outer layer 210. The support material 250 comprises a plurality of support elements 240. Preferably the support elements 240 are support bars, forming spacer elements between inner layer 220 and outer layer 210. Preferably, the support elements 240 comprise biobased and / or recycled material. The biobased and / or recycled material may have any one or more of the properties described above in the summary.

[0141] Preferably, at least one of inner layer 220, outer layer 210 and support material 250 comprises or consists of a fiber reinforced material. The inner layer 220 and outer layer 210 will be described in more detail with reference to Figure 16.

[0142] Preferably, the support elements 240 have any one or more of the properties described in the summary. The support elements 240 may be elongated elements extending in a direction parallel to the axis of the sleeve. In Figure 6, only few support elements 240 are shown at a relative large distance of each other, but typically many more support elements 240 may be arranged between inner layer 220 and outer layer 210, and the distance between the support elements 240 may be smaller. Preferably, a maximum distance (dmax) between adjacent support elements 240 as measured at an outer surface of the support elements is below 10 mm.

[0143] Optionally, the support elements 240 are less compressible in a radial direction perpendicular to the sleeve axis, than in a direction parallel to the sleeve axis.

[0144] Figure 7 illustrates another exemplary embodiment of a sleeve. In this embodiment a plurality of support elements 240 is arranged at a distance of each other, seen in direction DI parallel to the sleeve axis A of the sleeve 200. Further the support elements 240 are interconnected by means of a flexible connection element, here a thin flexible connection substrate 230, also called support substrate in the summary above, which is arranged around the inner layer 220. Also, in the embodiment of Figure 6 such a flexible connection substrate 230 may be present. The flexible connection substrate 230 or support substrate 230 may have any one or more of the properties described above in the summary. Preferably, the support elements 240 are attached to an upper side of the flexible connection substrate 230. This attachment is preferably realized prior to arranging the flexible connection substrate 230 with support elements 240 on the inner layer 220. Preferably, the flexible connection substrate 230 extends over substantially the full length of the sleeve.

[0145] Preferably, the support elements 240 are connected by the at least one flexible connection element in a regular pattern, for example a pattern of elongated strips or bars. The strips or bars may extend over a full length of the sleeve or multiple strips or bars at a distance of each other may cover a full length (seen in the direction DI), as shown in Figure 7. Similarly, the strips or bars may extend over a full circumference of the sleeve or multiple strips or bars at a distance of each other may cover a full circumference as in the embodiment of Figure 6.

[0146] The flexible connection substrate 230 comprises a mat, a film, a mesh, a woven or non-woven material and / or a porous material or combinations thereof. The flexible connection substrate 230 may comprise or consist of a biobased and / or recycled material. Figure 8 illustrates an embodiment which is similar to the embodiment of Figure 6, but where a flexible connection element 230’ is arranged at a distance of the inner layer 220 and at a distance of the outer layer 210. In such an embodiment the support elements 240 may be fixed directly on the inner layer 220. Although not shown, it will be understood that optionally also a flexible connection substrate 230 as shown in Figure 7 may be present between the support elements 240 and the inner layer 220 in which case the support elements 240 may be fixed to the flexible connection substrate. Alternatively or in addition, a flexible connection substrate (not shown) may be present between the support elements 240 and the outer layer 210.

[0147] Figure 9 illustrates an embodiment which is similar to the embodiment of Figure 7, but where a flexible connection element 230’ is arranged at a distance of the inner layer 220 and at a distance of the outer layer 210. In such an embodiment the support elements 240 may be fixed directly on the inner layer 220. Although not shown, it will be understood that optionally also a flexible connection substrate 230 as shown in Figure 7 may be present between the support elements 240 and the inner layer 220 in which case the support elements 240 may be fixed to the flexible connection substrate. Alternatively or in addition, a flexible connection substrate 230 may be present between the support elements 240 and the outer layer 210.

[0148] Figures 10 and 11 illustrate two possible patterns for arranging the support elements 240 on a flexible connection layer 230. Figures 10 and 11 illustrate the flexible connection layer 230 in a flat state, before it is fixed on the cylindrical inner layer 220. In the embodiment of Figure 10 an array of support elements 240 is arranged in an equidistant manner: multiple support elements 240 are arranged at a distance of each other, both as seen in an axial direction DI as in a circumferential direction D2. In an alternative embodiment the distances between adjacent support elements in the directions DI and D2 may be different. In the embodiment of Figure 11 the support elements extend over the full length L in the axial direction DI and are arranged in an equidistant manner in the circumferential direction D2 at a distance d of each other. Figures 12 shows an embodiment similar to the embodiment of Figure 11 in a perspective view. It is noted that the distance d in the flat state illustrated in Figure 11 may also be zero. If the cross section of the support elements 240 is rectangular then there will still be a distance between the upper surfaces of the support elements 240 when in the mounted state on a cylindrical inner layer. Optionally the upper surfaces of the support elements 240 may be rounded so that in the mounted state the upper surfaces of the support elements 240 extend along a cylindrical surface around the sleeve axis. Figure 13 A shows an embodiment similar to the embodiment of Figure 10 or 11 in a cross section view. Figure 13B illustrates that the support elements 240 may be arranged in a plurality of layers which are interconnected, for example by means of a flexible connection layer 230’ which is inserted between two adjacent layers of support elements 240. In the illustrated embodiment adjacent support elements 240 in different layers are offset over a certain distance. However, it is also possible that adjacent support elements 240 of adjacent layers are arranged on top of each other, so that they are not offset by a distance. Figure 14 illustrates a further embodiment in which support elements 240 have been arranged in multiple layers between inner layer 220 and outer layer 210 of sleeve 200. In this embodiment, multiple support elements 240 are arranged adjacent to and at a distance of each other in an axial direction DI.

[0149] Figure 15 A shows an embodiment similar to the embodiment of Figure 7 in an axial cross section view. Figure 15B illustrates that the support elements 240 may be arranged in a plurality of layers which are interconnected, for example by means of flexible connection elements 230’ which extend in each layer of the multiple layers. Optionally the support elements 240 of a first layer may be fixed, e.g. glued, to the support elements 240 of an adjacent layer. In the illustrated embodiment adjacent support elements 240 in different layers are offset over a certain distance. However, it is also possible that adjacent support elements 240 of adjacent layers are arranged on top of each other, so that they are not offset by a distance.

[0150] In the embodiments of the Figures discussed above, inner layer 220 and / or outer layer 210 may be electrically conductive, wherein optionally inner and outer layer 220, 210 are electrically connected to each other. Preferably, a thickness of inner layer 220 is between 0.7 and 15 mm, preferably between 0.7 and 4 mm; and / or a thickness of outer layer 210 is between 3 and 7 mm; and / or a thickness of a layer containing the support material 250, 230 and / or 230’ between inner layer 220 and outer layer 210 is between 5 and 600 mm.

[0151] Preferably, the connection substrates 230, 230’ are compressible substrates.

[0152] The illustrated sleeve may be manufactured using the following method. The method may comprise: providing a cylindrical inner layer 220 configured to be mounted on an adapter 300 or on a printing mandrel 400, arranging a support material 250 preferably comprising a biobased and / or recycled material on the cylindrical inner layer, optionally, arranging a cylindrical outer layer over said support material. In a preferred embodiment, the method may comprise: providing a cylindrical inner layer 220 configured to be mounted on an adapter sleeve (300 or on a printing mandrel 400, providing a plurality of support elements 240 interconnected to each other, for example using a flexible connection element such as a connection substrate 230, 230’, wherein the support elements 240 are preferably made of a recycled and / or biobased material, arranging the plurality of interconnected support elements 240 on said inner layer, optionally filling voids between the support elements, optionally attaching further layers, such as a further connecting substrate 230, to the support elements 240, arranging a cylindrical outer layer 210 around the plurality of support elements 240.

[0153] The support material 250 may be attached to the inner layer 220 and / or the outer layer 210 by any one of the following: adhering, such as gluing, screwing, stapling, riveting, clamping, melting, clipping, or combinations thereof.

[0154] During the attachment of the support material 250, the support material 250 may be kept in place by a temporary fixation means, wherein preferably the temporary fixation means comprises a cord, a wire, a band, a mesh, a network, a suction means, a clamp, a hook, a woven, a nonwoven or combinations thereof, which are optionally wound around the support material on the sleeve.

[0155] When the support material 250 comprises one or more support elements 240, the one or more support elements 240 may be shaped, preferably ground, such that the support elements 240, when arranged on the cylindrical inner layer 220, have an outer surface coinciding with a substantially cylindrical outer surface.

[0156] Optionally, an adhesive layer is applied on the cylindrical inner layer 220 prior to the step of arranging the support material 250 on the inner layer 220, and the arranging may comprise rolling the cylindrical inner layer 22 with adhesive over the support material 250, e.g. a support material as illustrated in Figures 10-12. As illustrated, the support material 250 may comprise a plurality of support elements 240 arranged according to a pattern on a flat surface, and the cylindrical inner layer 220 with adhesive may be rolled over said support elements 240. Alternatively, the adhesive may be arranged on the support material 250. Preferably, the support elements 240 comprise a plurality of elongate bars arranged parallel to each other, preferably in an equidistant manner. As explained above in connection with for example Figures 10-12, 13A and 13B, the support material 250 may comprise at least one support substrate 230, 230’, preferably a barrier layer with glass fiber reinforced resin. A support substrate 230, 230’ may be applied on the one or more support elements 240 and / or below the one or more support elements 240 and / or between two layers of support elements 240.

[0157] Figure 16 shows a sleeve 200 implemented as a hollow cylinder. The sleeve 200 has a layer structure which has, in this order from inside to outside: an inner layer 220 consisting of a base layer 220a and a compressible layer 220b; a filling layer comprising a support material 250, preferably a biobased and / or recycled support material. For example, the support material 250 may comprise support elements 240 as described above or may be in one piece; an outer layer 210.

[0158] Optionally, the inner layer 220 may comprise a further base layer (not shown), so that the compressible layer 220b is inserted between two base layers. For example, the compressible layer 220b may be inserted in between a lower and upper base layer, preferably a lower and upper fiber reinforced sublayer. Preferably, the base layer 220a is a fiber reinforced layer, for example a polyester fiber reinforced layer, but it is also possible to use non-fiber-reinforced layers for the base layer, such as a nickel layer or a foil. Preferably, the compressible layer 220b has a hardness between 25 and 65 Shore A measured according to ISO 7619-1:2010.

[0159] In a first exemplary embodiment, the outer layer 210 has a Shore D hardness between 70 and 95 measured according to ISO 7619-1:2010. This will result in a so-called hard coated sleeve. To achieve such hardness the outer layer 210 may be or comprise a fiber reinforced layer. For example, the outer layer 210 may be a fiber reinforced polyurethane layer or a multilayered structure comprising a barrier layer for example made of a fiber reinforced resin and a top layer for example made of polyurethane foam. In another exemplary embodiment, the outer layer 210 comprises a compressible layer having a Shore A hardness between 30 and 80 measured according to ISO 7619- 1:2010. This will result in a so-called compressible sleeve. The compressible layer may be for example a polyurethane layer, typically not fiber reinforced.

[0160] Preferably, a thickness of the inner layer 220a, b is between 0.7 and 15 mm, more preferably between 0.7 and 4 mm; and / or a thickness of the outer layer 210 is between 3 and 7 mm; and / or a thickness of a layer containing the support material 250 between the inner and the outer layer is between 5 and 600 mm, more preferably between 5 and 50 mm.

Claims

Claims1. A sleeve (200) for use with a printing plate (100), said sleeve having a sleeve axis, wherein the sleeve comprises a cylindrical inner layer (220) configured to be mounted on an adapter sleeve (300) or on a printing mandrel (400), a cylindrical outer layer, and a support material arranged between the inner layer and the outer layer and interconnecting the inner layer and the outer layer, said support material comprising a plurality of support elements (240).

2. The sleeve according to claim 1, wherein the support elements comprise fibers which are oriented in a direction substantially perpendicular to the sleeve axis.

3. The sleeve according to any of the previous claims, wherein the support elements are positioned in an equidistant manner, wherein a minimum distance measured at an outer surface of the inner layer is larger than 1 mm, wherein preferably a maximum distance between adjacent support elements is smaller than 10 mm.

4. The sleeve according to any of the previous claims, wherein a minimum distance between adjacent support elements, measured at an inner surface of the outer layer, is larger than 1 mm, preferably larger than 3 mm, more preferably larger than 5 mm, wherein preferably a maximum distance between adjacent support elements is smaller than 50 mm.

5. The sleeve according to any of the previous claims, wherein the support elements comprise multiple support elements arranged at a distance of each other seen in a direction parallel to an axis of the sleeve.

6. The sleeve according to any of the previous claims, wherein the support elements are elongate elements extending in a circumferential or in an axial direction of the sleeve.

7. The sleeve according to any of the previous claims, wherein the support elements are connected to each other.

8. The sleeve according to claim 7, wherein the support material comprises at least one flexible connection element (230) interconnecting the plurality of support elements.

9. The sleeve according to claim 8, wherein a flexible connection element of said at least one flexible connection element is located at a distance of the inner layer and the outer layer.

10. The sleeve according to claim 8 or 9, wherein the at least one flexible connection element comprises a flexible connection substrate, said flexible connection substrate preferably having a thickness between 0.1 mm and 5 mm, more preferably between 0.5 mm and 2 mm.

11. The sleeve according to claim 10, wherein the support elements are positioned on, preferably attached to, at least one side of the flexible connection substrate.

12. The sleeve according to any one of the claims 8 - 11, wherein the support elements are connected by the at least one flexible connection element in a pattern, preferably a regular pattern, for example a pattern of parallel stripes, a cubic pattern, a hexagonal pattern, a checkerboard pattern or a spiral pattern.

13. The sleeve according to any one of the claims 8 - 12, wherein the at least one flexible connection element comprises a mat, a film, a mesh, a woven or non-woven material and / or a porous material or combinations thereof.

14. The sleeve according to any of the claims 8 - 13, wherein the at least one flexible connection element comprises an adhesive or wherein the at least one flexible connection element is meltable.

15. The sleeve according to any of the claims 8 - 14, wherein the at least one flexible connection element comprises a biobased and / or recycled material.

16. The sleeve according to any one of the previous claims, wherein the support elements are hollow, partially hollow or porous, wherein preferably the support elements are gas filled.

17. The sleeve according to any one of the previous claims, wherein the support elements comprise or are made of any one of the following materials or a combination thereof: rigid polymer, foam, ceramic, porous material, fiber reinforced material, metal, wood, woodcomposites, such as wood with polymers, fibers, plant and / or animal fibers, wherein said support elements are preferably made of a biobased material and / or a recycled material.

18. The sleeve according to any one of the previous claims, wherein the support material comprises or consists of a biobased material which is impregnated and / or treated, such as coated with a coating configured to limit water uptake.

19. The sleeve according to any one of the previous claims, wherein the support elements have a cross section in the plane perpendicular and / or parallel to the sleeve axis which has any one of the following shapes: rectangular, prismatic, triangular, hexagonal, polygonal, circular, elliptic, trapezoidal, arc segmental, isosceles trapezoid, right-angled trapezoid, parallelogram, rhombus kite quadrilateral.

20. The sleeve according to any one of the previous claims, wherein the support elements have a thickness, measured in a radial direction of the sleeve, in the range of 1 to 100 mm, preferably 5 to 30 mm.

21. The sleeve according to any one of the previous claims, wherein the support elements have a width of 1 to 100 mm and a length in the range of 1 mm to 5000 mm.

22. The sleeve according to any one of the previous claims, wherein, looking in a circumferential direction of the sleeve, between 8 and 1000 support elements are arranged next to each other.

23. The sleeve according to any one of the previous claims, wherein the support elements have a width and a thickness measured in a radial direction of the sleeve, and wherein a ratio of the thickness to the width is between 1 :50 - 10, preferably between 1 :20 - 5, more preferably between 1:8 - 3.

24. The sleeve according to any one of the previous claims, wherein the support elements have a compressive strength higher than 0,5 MPa, preferably higher than 1 MPa.

25. The sleeve according to any one of the previous claims, wherein the support elements have a density of 0,1 g / cm3to 0,8 g / cm3.

26. The sleeve according to any one of the previous claims, wherein a space between adjacent support elements is filled with a gas, a fluid and / or a solid material or combinations thereof, wherein optionally the gas, the fluid and / or the solid material in the space between at least two support elements is above ambient pressure.

27. The sleeve according to any one of the previous claims, further comprising a gas impermeable material arranged to avoid the escape of gas present between the inner and the outer layer.

28. The sleeve according to any one of the previous claims, wherein the support material comprises at least one fiber reinforced and / or flexible layer on at least one side of the support elements.

29. The sleeve according to any one of the previous claims, wherein the inner and / or the outer layer is electrically conductive, wherein optionally the inner and the outer layer are electrically connected to each other.

30. A method to produce a sleeve (200) for use with a printing plate (100), said method comprising the steps of: providing a cylindrical inner layer (220) configured to be mounted on an adapter sleeve (300) or on a printing mandrel (400), providing a plurality of support elements interconnected to each other, arranging the plurality of interconnected support elements on said inner layer, optionally filling voids between the support elements, optionally attaching further layers to the support elements, arranging a cylindrical outer layer around the plurality of support elements.

31. The method according to claim 30, wherein the support elements are connected to each other by means of at least one flexible connection element, wherein the at least one flexible connection element is attached to an outer surface of the cylindrical inner layer.

32. The method according to claim 31, wherein the attaching of the support elements with the flexible connection element is performed by gluing, screwing, stapling, riveting, partial or complete melting and cooling of the connection element, partial melting and cooling of the support elements or combinations thereof.

33. The method according to claim 31 or 32, wherein an adhesive is arranged on the inner layer and wherein the attaching of the support elements is done by rolling the cylindrical inner layer with the adhesive over the interconnected support elements.

34. The method according to any of the claims 30 - 33, comprising at least one of the steps: grinding the support elements, gluing the support elements, fixing the support elements, until an adhesive applied to the support elements is firm.

35. Use of a sleeve according to any of the claims 1 - 29 in a printing device.

36. An assembly comprising a sleeve according to any of the claims 1 - 29, a printing mandrel and / or a further cylinder.

Images