Method for installing a printing plate on a sleeve, the sleeve and assemblies for printing with the printing plate

Abstract

The disclosure relates to a method for installing a printing plate on an outer surface of a sleeve, wherein the outer surface of the sleeve is provided with one or more grooves for allowing a gas, such as air or CO2, to escape from between the printing plate and the sleeve; the method comprising: installing the printing plate, preferably with a double-sided tape, on the sleeve over the one or more grooves and such that gas between the printing plate and the sleeve is allowed to escape via the one or more grooves.

Description

[0001] METHOD FOR INSTALLING A PRINTING PLATE ON A SLEEVE, THE SLEEVE AND ASSEMBLIES FOR PRINTING WITH THE PRINTING PLATE

[0002] The present invention relates to the technical field of installing a printing plate on an outer surface of a sleeve, said sleeve and the use thereof. The invention further relates to assemblies for printing with a printing plate, preferably for flexographic printing.

[0003] BACKGROUND

[0004] Printing with printing forms or printing plates has long been a conventional practice in the industry. This process involves the transfer of ink by pressing the printing plate onto a substrate to be printed on.

[0005] Conventional printing plates typically comprise a photopolymer layer that undergoes selective curing, often utilizing UV radiation. The cured portions create a desired relief pattern for printing, while the uncured areas are removed, e.g. washed away in a washer or removed in a thermal development unit. Alternatively, depending on the layer's composition, the opposite effect may be achieved. Before initiating the printing, the printing plate is taken to a mounting station where it is carefully affixed to a sleeve. Subsequently, the sleeve, together with the printing plate, is installed on a mandrel within a printing apparatus. Ink is then applied to the relief pattern of the printing plate. By rotating the mandrel and pressuring on the inked relief pattern against a substrate, an image can be printed on the substrate.

[0006] Achieving, good and consistent printing results has been forming a challenge within the industry. More so, printing deficiencies may still occur, for example due to improper mounting of the printing plate.

[0007] Therefore, there is still a need to improve existing techniques of installing a printing plate on a sleeve so that high quality prints can be achieved with the printing plate.

[0008] SUMMARY OF THE INVENTION

[0009] An object of embodiments of the present invention is to provide a method allowing an improved arrangement of a printing plate. Thereto, according to a first aspect, there is provided a method for installing a printing plate on an outer surface of a sleeve, wherein the outer surface of the sleeve is provided with one or more grooves for allowing a gas, such as air or CO2 to escape from between the printing plate and the sleeve. The method comprises installing the printing plate, preferably with an adhesive double-sided tape, on the sleeve over the one or more grooves and such that gas between the printing plate and the sleeve is allowed to escape via one or more grooves.

[0010] Embodiments of the present invention are based on the insight that bubble formation between the printing plate and the sleeve may cause printing deficiencies and impair high quality printing results. Testing and simulations have shown that such bubble formation may be caused by improper mounting and / or caused by gas formation resulting from material outgassing or vapor formation as a result of cleaning agents used to clean the sleeve. By providing the sleeve with one or more grooves, such bubble formation can be avoided as the gas formed under the printing plate can escape via the grooves. As a result, the printing plate can be better adhered to the sleeve and high-quality prints can be achieved with the printing plate. Additionally, the high-quality prints can be achieved more consistently and such consistency results in less waste. Namely, by improving the consistency, scrap works and / or bad prints which are otherwise to be dispensed with are reduced. As a result, there is less waste. Moreover, the inventors have also found that the printing plate can be affixed to a sleeve faster and / or more easily. Namely, in conventional techniques the printing plate has to be carefully affixed to the sleeve and bubble had to be avoided. By having the one or more grooves, the plate can be affixed more rapidly, preferably via a double-sided tape although it is also possible that the plate itself and / or the sleeve itself are provided with adhesive properties and / or that other fixation means are used.

[0011] According to an embodiment, the method further includes mounting the sleeve with the printing plate being installed thereon on an outer surface of an adapter or directly on an outer surface of a mandrel while providing a gas cushion, such as an air cushion, between an inner surface of the sleeve and an outer surface of the adapter or an outer surface the mandrel. Using the gas cushion facilitates the installing of the sleeve. The gas in the gas cushion is kept separate from gas in the one or more grooves of the sleeve. By keeping the separation of the gas from the gas cushion and the gas in the grooves, one can facilitate the installment of the sleeve by using the gas cushion whilst ensuring that no bubbles are formed as a result of using the gas cushion.

[0012] According to an embodiment, the method further includes installing the mandrel on which the sleeve is mounted, optionally with the adapter arranged between the sleeve and the mandrel, in a printing apparatus.

[0013] According to an embodiment, the method further includes cleaning the sleeve before the printing plate is installed thereon. Cleaning may be performed manually or in a cleaning apparatus. Cleaning may be performed mechanically e.g. by wiping with a cloth or a brush or other non-liquid cleaning means, or by dissolution or dispersion using a liquid cleaning agent e.g. water, a solvent or mixtures thereof or applying a gas or by a plasma treatment or an electrical treatment or combinations thereof. The cleaning preferably comprises cleaning with a liquid cleaning agent such as ethanol or propanol. This ensures a clean and smooth surface for the installation of the printing plate. As a result, the printing plate can make better contact with the sleeve, leading to improved adhesive attachment. This in turn results in a good quality and clarity of the printed images.

[0014] According to an embodiment, the step of installing the printing plate includes applying double-sided adhesive tape at least partially over the one or more grooves and adhering the printing plate on a top side of the adhesive double-sided taped. Preferably the surface area of the top side of the adhesive double-sided tap has at least the size of the printing plate. The use of adhesive double-sided tape offers several benefits in the printing process. Firstly, it provides a secure and reliable bond between the printing plate and the sleeve, this helps to maintain consistent printing and improves overall print accuracy. Secondly, the tape provides a convenient and efficient method for attaching the plate to the sleeve, eliminating the need for complex fastening mechanisms or the need for supplying adhesives directly to the sleeve and / or directly to the printing plate itself. This results in time savings and increased productivity during plate changeovers.

[0015] By having the surface area of the top side of the tape correspond to the bottom side of the printing plate, uniform contact is promoted between the printing plate and the sleeve surface, resulting in more consisted prints.

[0016] A typical adhesive tape comprises the following layers: a release liner (silicon coated), an adhesive (on the closed side), a primer, a backing, another primer, another adhesive (on the open side). The backing is relevant for some of the main features of a double-sided tape and mostly comprises polymer films, wovens or non-wovens from e.g. polyester, polyamides, polyacrylates, polyimides, polyolefins, polyurethanes, silicones, PVC, or combinations thereof. For rough surfaces, thicker foam tapes come into play. Thinner filmic tapes can be used for transparent bonding requirements and high-performance tapes are able to dissipate stress thanks to their viscoelastic behavior. The liner covers the adhesive system and is an important element for the application and removal process. Paper and filmic release liners with a variety of different features. The pressure-sensitively adhesive layer preferably comprises a polymer selected from the group consisting of natural rubbers, synthetic rubbers, polyacrylates, polyurethanes, epoxy resins, silicones, and mixtures of two or more of the above polymers. The pressure-sensitive adhesive layer of the adhesive tape may comprise additives which may contribute to the particular properties of the adhesive layer. These additives may be, for example, pigments, plasticizers, fillers, stabilizers, antioxidants, etc.

[0017] According to another aspect of the invention, there is provided a sleeve with an outer surface for holding a printing plate. The sleeve has an inner surface configured to be mounted on an adapter or an inner surface configured to be mounted directly on a printing mandrel by aid of a gas cushion supplied between the inner surface of the sleeve and an outer surface of the adapter or the mandrel. The outer surface of the sleeve is provided with one or more grooves for allowing gas to escape from between the printing plate and the sleeve. The gas can be air or any other gas resulting from material outgassing such as any volatile substances which originate from any one or more of the printing plate, or the adhesive, or cleaning agents. The gas may have been trapped between sleeve and tape during mounting of the tape onto the sleeve. The gas may be solvent vapor originating from cleaning and / or from residues within the sleeve and / or tape material, gaseous reaction products stemming from materials of the sleeve and / or tape.

[0018] The benefits as mentioned earlier in connection to the method equally apply for aspects of the sleeves and related assemblies. In particular, by designing the sleeve with the grooves, the bubble formation issue which may be caused by improper mounting and / or by gas formation is reduced. As a result, high quality prints can be achieved with a printing plate securely affixed on the sleeve.

[0019] Preferably, the one or more grooves include at least one groove having a groove length of at least 2 cm, preferably at least 3 cm, more preferably at least 4 cm. Preferably the majority, and more preferably each of the one or more grooves extend over at least 2 cm, preferably at least 3 cm. The length of the groove may have the same length as the axial length of the sleeve or may be longer. In case the groove is not linear and / or in case the groove is helical, then the length may be at least 110% of the as the axial length of the sleeve. In some cases, the length of the groove may be in the range of 110% to 35.000% of the as the axial length of the sleeve. The groove length can be measured along a center line of the groove which can be straight or curved and / or helical. In this manner, a good gas escape can be ensured.

[0020] Preferably, the sleeve has an outer surface with a total circumferential surface area At, wherein at least 50 %, preferably at least 65%, more preferably at least 75%, even more preferably at least 85 % of the total circumferential surface area At of the outer surface of the sleeve is even such that, when printing, a uniform supporting pressure is given by the outer surface of the sleeve to the printing plate. Notably, the term “even” as used herein refers to the surface of the outer sleeve being free from significant surface irregularities such as the grooves, ensuring consistent contact and providing uniform supporting pressure to the printing plate during the printing process. The even surface may have a rough texture having micro-scale irregularities that enhance the grip and / or attachment between the sleeve and the printing plate, preferably attached via a double-sided tape. By having the majority of the surface area being even, one ensures consistent contact between the printing plate and the sleeve. The printing sleeve may be substantially cylindrical, the use of the term even suggests that the respective portion of the outer surface of the cylindrical sleeve is uniform, and lacking in irregularities or variations. This evenness ensures that when printing, the outer surface of the sleeve applies a consistent and uniform supporting pressure to the printing plate. This uniform contact enables the even distribution of pressure across the printing plate, resulting in consistent ink transfer and improved print quality.

[0021] Preferably, the one or more grooves extend over a total grooved area Ag, wherein said total grooved area is at most 50% of the total circumferential surface area surface At of the outer surface of the sleeve and preferably between 0,3 - 50 % of the total surface area surface At, more preferably between 1 - 35 %, even more preferably between 2 - 25 %. The total grooved area Ag refers to the combined surface area occupied by the grooves on the outer surface of the sleeve, expressed as a percentage of the total circumferential surface area At of the sleeve. The grooved area allows for controlled gas escape between the printing plate and the sleeve through the grooves. By selecting a total grooved area Ag as described, the formation of air bubbles that could negatively impact ink transfer and print quality additionally is reduced or avoided, the remaining area of the sleeve provides for a uniform supporting pressure of the printing plate, promoting a good ink transfer. In particular, by having at least 50 % of the total circumferential surface area At of the sleeve without grooves and at most 50% being a grooved area Ag, defects are reduced and overall print quality and uniformity is increased.

[0022] Preferably, the grooves include a plurality of grooves distributed over the outer surface of the sleeve, preferably equally distributed. The grooves can be distributed in several ways as long as an effective gas escape via the grooves across the surface of the sleeve is provided. The grooves may function as channels for gas escape. The groove distribution may be chosen from the group of distributions comprising: random distribution, a linear line pattern, a crosshatched line pattern, a spiral pattern, a grid pattern, or concentric circles or combinations thereof.

[0023] The plurality of grooves typically has several individual grooves. In an embodiment, the individual grooves within the plurality of grooves may intersect, for example in the case of a grid pattern. Alternatively, the grooves may not intersect with each other, for example in the case of a spiral pattern. The majority of the individual grooves preferably have a groove length of at least 2 cm, preferably at least 3 cm to ensure a good gas escape. In some cases the length of the groves may be much longer as described above. The groove length in this instance can be measured from one end of the groove to the other opposite end of the groove along the center line.

[0024] Preferably, the plurality of grooves are distributed over the outer surface of the sleeve such that at least 0,1 to 10 distinct grooves are present per square centimeter of the outer surface area of the sleeve. Distributing a sufficient number of distinct grooves, preferably ranging from 0.1 to 10 grooves per square centimeter of the outer surface area of the sleeve, offers significant advantages in the printing process. The presence of an adequate density of distinct grooves ensures efficient gas escape and facilitates the removal of trapped air or gas between the printing plate and the sleeve, such as between the tape and the sleeve’s outer surface. The term "distinct grooves" refers to individual, separate, and recognizable channels or depressions on the outer surface of the sleeve. Each groove can thus maintain a distinct path which may or may not intersect with other grooves, such as neighboring grooves.

[0025] In an embodiment, the one or more grooves are isolated from the inner surface of the sleeve, such that any gas transfer between the gas within the one or more grooves and the gas of the gas cushion is prevented. By having the grooves isolated from the inner surface, any gas transfer between the grooves and the gas cushion which may be used for mounting the sleeve is prevented and any bubble formation is reduced or avoided.

[0026] Preferably, the outer surface of the sleeve has a rough texture having a roughness Ra value in the range of 10 pm - 300 pm. The rough texture enhances grip between the sleeve and / or the adhesive tape and / or the printing plate, facilitating a secure and reliable attachment. In particular, the rough texture enhances attachment of the printing plate with the sleeve if attached via an adhesive doublesided tape. The roughness Ra value is a commonly used parameter to quantify the surface roughness and can be measured using ISO 3274 (1996) in combination with ISO 4288 (1985).

[0027] Preferably, the sleeve has a wall thickness Tw as measured between the outer surface and inner surface, said thickness having a value from at least 0.5 mm, preferably 0.5 mm to 150 mm, more preferably 0.5 mm to 135 mm, even more preferably 0,8 to 20 mm. By having the wall thickness of at least 0.5 mm, structural integrity and strength of the sleeve is provided. A thicker wall enhances the sleeve's resistance to deformation. The one or more grooves typically have a depth. The depth of the one or more grooves is measured as a vertical measurement from the outer surface of the sleeve to the lowest point of the groove. It represents the extent to which the groove extends into the surface of the sleeve, for example the extent to which the surface is being recessed or carved. The one or more grooves may have a depth which is at least 5 %, preferably at least 10 %, more preferably at least 15 % and / or at most 85 %, preferably at most 95 % of the wall thickness Tw of the sleeve. The one or more grooves may have a depth in the range of 0,01 to 2 mm, preferably in the range of 0,05 to 1 mm, more preferably in the range of 0, 1 to 0,3 mm.

[0028] A deeper groove allows for a larger volume of trapped gas to be accommodated within the groove, providing ample space for its escape during installment of any of the printing plate, the double-sided tape and / or during storage and / or during the printing operation. The groove should be deep enough to serve the intended purpose of gas escape or other functionalities, but not excessively deep to the point of compromising the structural integrity or mechanical stability of the sleeve.

[0029] As seen from a cross section, the one or more grooves can have several possible cross-sectional shapes. Preferably, the shape is chosen from one or more of a triangle, a square, a rectangle, a trapezoid, a partial circle, a partial ellipse, a regular or irregular shape with multiple edges, or combinations thereof. The grooves can have a cross-section in the shape of a triangle of which the top lies 0,01 to 2 mm deep in the outer surface.

[0030] Preferably, the outer surface of the sleeve has a hardness in the range of 30 Shore A to 99 Shore D. The preferred hardness falls within the range of 60 Shore A to 95 Shore D, more preferably 70 Shore A to 80 Shore D. The hardness can be measured with a durometer according to ISO 7619-1 (2010). The hardness range provides a good balance between flexibility and rigidity, allowing the sleeve to act as a stable support for the printing plate.

[0031] The sleeve typically has a total length Ls as measured in a longitudinal direction between a first free edge and second free edge of the sleeve. The grooves typically each have a longitudinal length Lg. Preferably, the longitudinal length Lg is at least 30 %, preferably at least 50 %, more preferably at least 75% of the total length Ls of the sleeve. By having the length of the grooves along a significant portion of the sleeve's total length, a larger portion of groove is available for effective gas escape. This allows trapped air or gas to be expelled more effectively. The longitudinal length Lg is the distance covered by the one or more grooves as seen in the longitudinal direction. Each groove may individually have a groove length measured along the center line of the respective groove.

[0032] The sleeve can be a layered sleeve structure comprising at least an outer layer for holding the printing plate and at least an inner layer for sliding over the mandrel or over the adapter. Further intermediate layers may be present. The outer layer may have additional features or treatments to enhance its performance, such as a rough texture, as previously mentioned, to improve grip and attachment between the sleeve and the printing plate and optionally the double-sided tape. The materials used for the inner layer preferably exhibit properties such as low friction, high abrasion resistance, and compatibility with the printing mandrel or adapter surfaces. By having a layered sleeve structure with distinct outer and inner layers, the sleeve can be optimized in terms of durability, and ease of use. The outer layer should be configured to securely hold the printing plate, while the inner layer facilitates smooth sliding and positioning of the sleeve on the printing mandrel and / or adapter.

[0033] Preferably, the outer layer is formed from a non-metallic material, chosen from a polymer, a ceramic, a reinforced polymer, a foam, a rigid material, an elastic material, or combinations thereof.

[0034] Preferably, the inner layer is a fiber reinforced layer. The presence of fiber reinforcement enhances the strength and durability of the sleeve. The fibers used can be chosen from glass, carbon, or aramid fibers.

[0035] In an embodiment, an additional layer between the inner and outer layer can be present. The additional layer can have at least one of or any combination of the following properties:

[0036] - an elastic modulus, as measured via ISO 178, in the range of 0,05 to 700 GPa;

[0037] - a density in the range of 0,15 to 2,0 g / cm3;

[0038] - a flexural strength, as measured via ISO 178, in the range of 2,0 to 50 MPa;

[0039] - a compressive strength, as measured via ISO 604, in the range of 1,0 to 60 MPa.

[0040] The sleeve typically has a side surface. Preferably, the side surface is substantially perpendicular to the outer surface of the sleeve. Preferably, the one or more grooves extend until a free edge between the side surface and outer surface such that a channel connection is formed between the outer surface and the side surface which allows gas to escape via the channel connection. In this manner, the sleeve with the grooves can be easily manufactured whilst providing for an excellent gas escape.

[0041] Preferably, at least one groove is connected to a channel extending between the outer surface and the inner surface of the sleeve, wherein said channel is connected to an opening in the side surface of the sleeve for allowing gas to escape via said side surface or remains open at least outside the area where the tape is applied. Preferably, the channel substantially extends in a direction parallel to the outer surface and inner surface, e.g. extending parallel and in the middle between the outer and inner surface. By including such channel, each individual channel may be designed smaller such that the outer surface of the sleeve provides more supporting pressure for the printing plate while the case is still allowed to escape via the channel extending between the outer surface and the inner surface of the sleeve.

[0042] Preferably, the one or more grooves have an upper width in the range of 0,01 to 1 mm. In this manner, the grooves can receive a sufficient amount of gas to escape to reduce or avoid bubble formation while providing good support for the printing plate. Preferably, the one or more grooves have a lower width equal to or lower than an upper width. In another embodiment, the lower width is larger than the upper width. In this manner, more support is given while the larger lower width allows for receiving a larger volume of gas.

[0043] Preferably, the one or more grooves have a depth in the range of 0,01 to 2 mm, preferably in the range of 0, 1 to 1 mm, more preferably in the range of 0,2 to 0,5 mm.

[0044] The grooves may extend over the surface of the sleeve following any suitable shape or line. Preferably, the one or more grooves extend over the outer surface of the sleeve while having a shape chosen from: straight lines, curved lines, helical lines, zigzag lines, periodic or non-periodic wave lines, meandering lines, lines which form a shape or a lettering or a logo or combinations thereof.

[0045] Another aspect relates to the use of the sleeve as described herein, wherein the sleeve is used to receive a printing plate and wherein the sleeve with the printing plate is subsequently used for printing. Preferably, the printing plate is taped to the sleeve. Such use is extremely beneficial since higher print qualities can be achieved. Additionally, more consistency in print quality can be provided.

[0046] Further aspects relate to several inventive assemblies for printing, including and not limited to:

[0047] - a first assembly including the sleeve and the printing plate;

[0048] - a second assembly including the sleeve and a mandrel, and preferably a printing plate;

[0049] - a third assembly including the sleeve and an adapter, and preferably a printing plate and / or a mandrel.

[0050] Hence, according to an aspect, there is provided an assembly including a sleeve and a printing plate. In particular, an assembly that includes the sleeve with the grooves as described herein. The assembly further includes a printing plate which is installed on the outer surface of the sleeve over the one or more grooves such that gas from an interface between the printing plate and the sleeve is allowed to escape. This aspect is based on the inventive insight that the assembly can be used for high quality printing while consistent results can be achieved. Namely, by having the printing plate installed over the one or more grooves, bubble formation can be avoided. In this manner, improved printing quality is achieved. Preferably, this assembly further includes a mandrel and / or an adapter.

[0051] According to an aspect, there is provided an assembly comprising the sleeve and a mandrel. In particular, an assembly with the sleeve as described herein; wherein the sleeve is mounted directly on a printing mandrel. The printing mandrel, also known as a printing cylinder, holds the sleeve on which the printing plate can be installed securely in place, preferably via a double-sided tape. Preferably, the assembly further comprises a printing plate which is installed on the outer surface of the sleeve over one or more grooves such that gas from an interface between the printing plate and the sleeve is allowed to escape. The mandrel may be made of metal and / or carbon, for example, the mandrel may be a metal cylinder. The mandrel is typically configured to be installed in a printing device.

[0052] According to an aspect, there is provided an assembly with a sleeve and an adapter, in particular an assembly for printing with a printing plate. The assembly comprises the sleeve as described herein. The sleeve is mounted on the adapter which is mountable on a printing mandrel. The mandrel may have any of the features as described herein.

[0053] Preferably, the assembly further comprises a printing plate, wherein the printing plate is installed on the outer surface of the sleeve over the one or more grooves such that gas from an interface between the printing plate and the sleeve is allowed to escape.

[0054] Preferably, the adapter is provided with one or more gas guides so as to guide gas to an interface between the inner surface of the sleeve and an outer surface of the adapter for providing a gas cushion in between, wherein the gas of the gas cushion is for example compressed air or nitrogen dioxide (N2). The gas may be provided via any suitable inlet. Typically, the inlet of the adapter is arranged to correspond to an outlet of the mandrel such that gas from the outlet may flow to the inlet of the adapter so as to provide for a gas cushion at the outer surface of the adapter. In this manner, the sleeve can be easily mounted on or removed from the adapter.

[0055] In an embodiment, the adapter is made of aluminum, steel, or is made of a polymer and / or composite material such as engineered plastics or carbon fiber-reinforced composites. The adapter may include two parts: an inner layer that fits onto the mandrel and an outer layer that connects to the printing sleeve. Preferably, the assembly with the adapter further comprises a printing mandrel. Generally, the printing mandrel is made of metal, such as steel or aluminum, and is mounted into a printing apparatus after being provided with the sleeve and optionally the adapter.

[0056] Preferably, the printing plate is adhered to the outer surface of the sleeve, preferably with a doublesided tape. Preferably, the double-sided tape has the same surface area as a bottom surface area of the printing plate. The printing plate may have a dimensionally stable support may also be referred to as a carrier layer and can be made from a material chosen from the group consisting of metal, aluminum, steel, a polymer, and synthetic composites. Such support layer can be a PET sheet. Preferably, the carrier layer LI comprises a metal sheet, a steel, an alloy, a natural or artificial polymer, a polymer blend, a polymer film, or any combination thereof. Examples of suitable dimensionally stable carriers are plates, foils, and also conical and cylindrical tubes, known as sleeves, made of metals such as steel, aluminum, copper or nickel, or of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyamide or polycarbonate, of wovens or nonwovens such as woven glass fiber fabric, or of composite materials composed of glass fibers and plastics. Particularly suitable as dimensionally stable carriers are dimensionally stable carrier foils or metal sheets, examples being polyethylene or polyester foils or steel or aluminum sheets. The carrier foils or metal sheets have a thickness, generally speaking, of 50 to 1500 pm, preferably 75 to 400 pm, for example around 250 pm. If steel is used as carrier material, steel sheets having a thickness of 0.05 to 0.3 mm are preferred. For protection against corrosion, preference is given to using tin-plated steel sheets. These carrier foils or carrier sheets may be coated with a thin, adhesion-promoting layer, for example a layer 0.1 pm to 2 pm thick, on the side of the carrier foil facing the radiation-curable, relief-forming layer. In a preferred embodiment, the carrier layer is a PET carrier layer made from polyethylene terephthalate.

[0057] The printing sleeve may further comprise a rubber ring placed at the ends. The rubber ring may improve the holding in place of the sleeve.

[0058] According to a further aspect, there is provided a method for manufacturing a sleeve for holding a printing plate, said sleeve having an outer surface and an inner surface to be mounted on an adapter or directly on a printing mandrel by aid of a gas cushion supplied between the inner surface of the sleeve and an outer surface of the adapter or an outer surface of the mandrel.

[0059] A further aspect relates to a kit for printing, the kit comprising the sleeve as described herein. The kit further comprises a mandrel and / or an adapter. The sleeve can be installed on a mandrel, optionally while having the adapter between the sleeve and the mandrel. This kit is beneficial as it may receive the printing plate in an improved manner by having the grooves. In this manner, gas bubbles are avoided resulting in improved printing quality.

[0060] The method for manufacturing the sleeve comprises the steps of:

[0061] - providing a sleeve and creating at least one or more grooves in an outer surface of the sleeve or generating a sleeve layer with the one or more grooves via 3D printing;

[0062] - optionally, treating the sleeve having the one or more grooves with one or more process steps chosen from: grinding, polishing, deburring, blowing out, washing, blasting, brushing, plasma treatment or combinations thereof.

[0063] The technical features and benefits as described above, in particular in relation to the sleeve are equally applicable to the present method according to this aspect.

[0064] The one or more grooves in the outer surface can be created via any suitable technique, preferably via one or more of: scribing, milling, lasering, burning, melting, etching, dissolving, sawing, cutting, blasting, grinding, punching or embossing.

[0065] In addition or as an alternative to the creating of the grooves, grooves may be generated by 3D printing a sleeve, or at least a layer of the sleeve, with the one or more grooves. For example, a sleeve with grooves can be 3D printed, said grooves and / or additional grooves can be created in the outer surface of the groove by for example the scribing, milling, lasering, burning, melting, etching, dissolving, sawing, cutting, blasting, grinding, punching or embossing.

[0066] Notably, the one or more grooves can be manufactured so as to have any of the features and effects as described herein.

[0067] Most preferably, the one or more grooves are created in the outer surface of the sleeve with one or more of: scribing, milling, laser ablation, cutting. By scribing the outer surface, the grooves can be provided at low cost with minimal and non-complex equipment, a mere sharp tool is enough. For milling, one can use rotary cutters to remove material of the outer layer of the sleeve to create the grooves. This technique provides high precision, and the groove can be created in any suitable size. Also, laser ablation provides high precision as well as a more rapid manner to create the grooves. As such, productivity may be increased. Cutting offers simplicity and low cost, namely cutting tools are readily available and affordable. In an embodiment of the method, the method further comprises the step of:

[0068] - roughening the outer surface of the sleeve, preferably roughening via dry grinding, roughening via plasma treatment, roughening via sandpaper or placing an open cell foam structure over the outer surface. The roughening is preferably performed such that the outer surface has a rough texture, preferably a roughness Ra value in the range of 10 pm - 300 pm.

[0069] Preferably, the roughening is at least performed in the areas between the one or more grooves. The rough texture can enhance attachment.

[0070] BRIEF DESCRIPTION OF DRAWINGS

[0071] Embodiments of the invention will now be described in more detail with respect to the figures illustrating some preferred embodiments of the invention.

[0072] Figure 1 illustrates installing a printing plate on sleeve with a groove and mounting the sleeve with the printing plate directly on a mandrel.

[0073] Figure 2 illustrates installing a printing plate on sleeve with a groove and mounting the sleeve on an adapter before being installed on a mandrel.

[0074] Figure 3A shows a side view of a mandrel.

[0075] Figure 3B shows a cross-sectional view of the mandrel of figure 3A along section line AA.

[0076] Figure 4 shows a cross-sectional side view of the mandrel of figure 3B and a sleeve with a printing plate.

[0077] Figure 5 shows a cross-sectional side view of the mandrel of figure 3B and a sleeve with a printing plate wherein an adapter is installed between the sleeve and the mandrel.

[0078] Figures 6A, 6B, figures 7A, 7B and figures 8 A, 8B respectively show a top view and a corresponding cross-sectional side view of a sleeve mounted on mandrel according to embodiments of the invention. Figures 9A and 9B show a top view a sleeve according to embodiments of the invention. Figures 10A - 10D show cross-sectional side views of a sleeve mounted on an adapter which is mounted on a mandrel according to embodiments of the invention.

[0079] Figures 11A - 11C illustrate perspective views of a sleeve according to embodiments of the invention.

[0080] Figure 12 illustrates a partial cross-sectional view along section line BB of figure 11B.

[0081] Figure 13 illustrates schematically a sleeve according to embodiment, said sleeve being mounted on a mandrel within a printing apparatus. The figures are purely illustrative and serve only to increase the understanding of the invention.

[0082] DETAILED DESCRIPTION

[0083] Figure 1 shows a printing plate 100, a double-sided tape 150. The figure further shows a sleeve 200 with a groove 250 on the outer surface 210. Printing plate 100 can be installed on the outer surface 210 of the sleeve 200 as shown. Notably, more than one groove may be present as will be explained later on. The groove 250 allows for a gas, such as air or CO2, to escape from between the printing plate 100 and the sleeve 200. Figure 1 shows sleeve 200 having an inner surface 220 and outer surface 210. The inner surface of the sleeve refers to the side of the sleeve that faces inward when the sleeve is mounted on the printing mandrel 400 (or the adapter 300 as shown in figure 2). Printing plate 100 can be affixed on the outer surface 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. Notably, in addition or instead of the double-sided tape, the sleeve 100 and / or the printing plate 100 may be provided with adhesive means, such as an adhesive layer (not shown). Due to the groove 250, the printing plate 100 can be affixed more rapidly while still being fixed properly so as to achieve good and high-quality print results with the printing plate 100. The sleeve 200 with the printing plate 100 can be installed on an outer surface 310 of an adapter 300 (see figure 2) or directly on an outer surface 410 of the mandrel 400 (see figure 1). Installing the sleeve is preferably occasioned by providing a gas cushion, such as an air cushion, between an inner surface 220 of the sleeve 200 and the outer surface 310 of the adapter 300 or an outer surface 410 the mandrel 400. The gas cushion facilitates the installation of the sleeve 200 on the mandrel 400 or installing of the sleeve 200 on the adapter 300. As shown in figure 1 , the mandrel 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 adapter 300 (see e.g. figure 5) is used, the adapter is preferably provided with one or more gas guides 350. To provide the gas cushion, air or another gas can be used which can be supplied via inlet 401 of the mandrel. As illustrated in figures 4 and 5, there is preferably no connection between the gas cushion and gas in the one or more grooves 250 of the sleeve 200, in this manner the gas cushion is kept separate from the one or more grooves 250. In this manner, no bubbles can be formed as a result of gas originating from the gas cushion.

[0084] Figure 1 further shows in the right upper side that the printing plate 100 is installed on the outer surface 210 of the sleeve 200 and such that the plate 100 partially covers the groove 250. In this manner, gas is allowed to escape from between the printing plate 100 (and the double-sided tape) and the sleeve 200, such that bubble formation is reduced or avoided. In particular, bubbles underneath the printing plate 100 that may be formed due to improper mounting of the plate 100 and / or caused by gas formation resulting from material outgassing or vapor formation as a result of cleaning agents used to clean the sleeve 200 before the plate 100 is installed thereon.

[0085] The installation and affixing of the printing plate 100 to the sleeve 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 then brought and installed into a printing apparatus (not shown). Printing plate 100 can be provided with any printing pattern to transfer ink therewith. Before installing the printing plate 100 or before applying the double-sided tape 150 on the outer surface 210 of the sleeve 200, the outer surface may be cleaned by a cleaning agent.

[0086] Figure 1 further shows a double-side tape 150. Tape 150 may be applied at least partially over the one or more grooves 250 so as to adhere the printing plate 100 on a top side of the double-sided tape 150. To achieve uniform support, the surface area of the top side of the double-sided tape 150 is preferably substantially the same as the bottom side of the printing plate 100. The term “top” refers to the side facing away from the sleeve 200. The term “bottom” refers to the side facing towards the sleeve 200. Figure 1 further shows assembly 600 in the lower left side, the assembly 600 includes the printing plate 100, the sleeve 200, and the mandrel 400. Optionally, an adapter 300 (as e.g. shown in figure 2) is arranged in between the sleeve 200 and the mandrel 400.

[0087] Figure 2 illustrates printing plate 100 on the outer surface 210 of sleeve 200 with a groove 250. The sleeve 200 as shown is mounted on adapter 300 before being installed on mandrel 400. Afterwards, an assembly 700 is formed including the printing plate 100 affixed on the sleeve 200 with the one or more grooves 250, and further including the mandrel 400 and optionally an adapter 300. This assembly is then suitable for installation in a printing apparatus (see for example figure 13).

[0088] 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 typically has a cylindrical body serving as the main structure of the mandrel. The body can be manufactured from steel or aluminium. 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 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.

[0089] 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 220 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 the inner surface 220 of the sleeve over the outer surface 410 of the mandrel 400. When the gas cushion is removed, the sleeve 200 is fixed on the mandrel 400. The dimensions are typically chosen so that the sleeve cannot be moved without the gas cushion. An adapter 300 (not shown in figure 4) may be mounted first on the mandrel 400 following a similar principle (see figure 5).

[0090] Figure 5 illustrates the adapter 300 having one or more gas guides 350. The gas guide 350 acts as a passage with an inlet 301 and outlet 302. Inlet 301 is arranged to receive gas from the outlet 402 of the mandrel 400. Outlet 302 provides the gas cushion at the outer surface 310 of the adapter 300. In this manner the sleeve 200 may easily slide over the outer surface 310 of the adapter.

[0091] Both figures 4 and 5 also illustrate that the printing plate 100 is applied on the outer surface 210 of the sleeve 200 over the one or more grooves 250. In this manner, gas is allowed to escape from between the printing plate 100 and the sleeve 200, in particular is allowed to escape from between the double-sided tape 150 and the sleeve 200.

[0092] Figures 6A, 6B, figures 7A, 7B and figures 8A, 8B shall now be used to explain certain preferred embodiments of the sleeve 200 and certain preferred types of grooves 250. As for example shown in figure 6A (and figures 1, 2, 11A-11C), the sleeve 200 has an outer surface 210 which may have a total circumferential surface area At. Preferably, at least 50 % of said total circumferential surface area At is even such that, when printing, a uniform supporting pressure is given by the outer surface 210 of the sleeve 200 to the printing plate 100. The term “even” refers to the surface of the outer sleeve being free from significant surface irregularities such as the grooves 250. The even areas 240 between the grooves may have a rough texture with micro-scale irregularities that enhance the grip as will further be explained in connection to figure 12. The rough texture of the areas 240 between the grooves can be characterized by having a roughness Ra value in the range of 10 pm - 300 pm.

[0093] Figure 7A shows that the grooves 250 may extend over a total grooved area Ag. Preferably, said total grooved area Ag is at most 50% of the total circumferential surface area surface At of the sleeve 200. Figures 6A, 7A and 8A show that grooves 250 are equally distributed over the outer surface 210 of the sleeve. The grooves can be distributed in several ways.

[0094] In figure 6A the grooves 250 extend in longitudinal direction of the sleeve 200, more in particular the grooves 250 extend continuously without any interruptions in longitudinal direction of the sleeve. Particularly, figure 6A shows that the grooves 250 extend from a center of the outer surface 210 of the sleeve 200 up to both edges 201, 202 of the sleeve 200. Notably, the grooves may also extend up to (only) one of the edges of the sleeve 200. Or the grooves may be provided such that a first amount of the grooves extend to one edge 201 while a second amount of grooves extend to the other edge 202. Alternatively, some of the grooves 250 may not extend up to the edges 201, 202 and may only extend over the outer surface 210 and maintain a distance from the edges 201, 202 as for example shown in figures 7A and 8A.

[0095] The one or more grooves 250 may extend parallel to the longitudinal direction of the sleeve 200 (see figures 6 - 8). The grooves 250 may also form a grid pattern or a spiral pattern (see figures 9 A and 9B). Preferably, grooves 250 are distributed over the outer surface 210 so as to cover the outer surface such that at least 0,1 to 10 distinct grooves are present per square centimeter of the outer surface. The distinct grooves may or may not intersect with each other, for example they may intersect and form a grid.

[0096] In an embodiment, the distinct grooves have a length Lg which is preferably at least 50 % of the length Ls of the sleeve 200 (see for example figure 6A for the length Ls of the sleeve and figure 7A for the length Lg of the grooves 250). By having the grooves substantially long, a good gas escape is ensured. The grooves may be shorter as for example indicated in figure 8A. In such an embodiment, it is advised to have the grooves 250 connected to a channel 260 as shown in the side view in figure 8B. The channel 260 extends between the outer surface 210 and the inner surface 220 of the sleeve 200 and is connected to an opening 235 in the side surface 230 of the sleeve for allowing gas to escape via said side surface (as also illustrated by figure 11C).

[0097] Figure 8B shows that channel 260 extends parallel to the outer surface and inner surface and is located between surface and inner surface, preferably substantially in the middle between the outer and inner surface. By including such channel, each individual groove 250 may be designed smaller such that the outer surface 210 of the sleeve 200 provides more supporting pressure for the printing plate 100 while the gas is allowed to escape via the channel 260. The supporting pressure is typically given by the even areas 240 (preferably even and rough) between the grooves 250. As can be seen from the cross-sectional view of figures 6B, 7B and 8B the grooves 250 are separated from the inner surface of the sleeve 250. The term “inner surface” as used herein refers to the interior side of the sleeve, which is typically in contact with either the adapter or the printing mandrel during the printing process. Generally, the inner surface 220 of the sleeve 200 is typically configured to slide over the outer surface 310 of the adapter 300 or the outer surface 410 of the mandrel 400. The gas cushion helps to slide the inner surface of the sleeve over the adapter or the printing mandrel. As said, the grooves on the outer surface of the sleeve are preferably isolated from this inner surface. This means that there is no direct connection or communication between the grooves and the gas cushion when the gas cushion is supplied, for example via an external air supply. By having the grooves isolated from the inner surface, any gas transfer between the grooves and the gas cushion is prevented and any bubble formation is reduced or avoided.

[0098] In figure 6B, the grooves 250 extend up both edges 201, 202 of the sleeve. By having the grooves 250 extend up to at least one of the edges, gas escape is ensured, even when larger printing plates 100 are used. In figure 7B, the grooves 250 extend along the outer surface 2012 but are positioned at a distance from the edges 201, 202 of the sleeve. This may improve structural integrity of the sleeve 200. Also, it may be beneficial to include a channel 260 in the wall of the sleeve, wherein channel 260 connects the one or more grooves 250 on the outer surface to an opening 235 a side surface 230 of the sleeve.

[0099] Figure 8A further illustrates an example wherein several grooves 250 are distributed in a pattern over the longitudinal length of the sleeve. As said before, the sleeve typically has a total length Ls and the grooves typically each individually have a longitudinal length Lg. In this case, it is preferred that the sum of the longitudinal lengths Lg of the grooves is over at least 30 %, preferably at least 50 %, of the total length Ls of the sleeve 200. Or with other words, as seen along the same longitudinal line, at least 30 % thereof should include a groove 250. In this manner, a large amount of grooved space is available for gas escape. Notably, each groove may individually have a groove length measured along the center line of the respective groove.

[0100] Figures 6A, 7A, and 8A further indicate areas 240 on the outer surface of the sleeve 200. In particular, these areas preferably have a hardness in the range of 30 Shore A to 99 Shore D. The preferred hardness falls within the range of 60 Shore A to 95 Shore, preferably 70 Shore A to 80 Shore D. As explained earlier, the grooves 250 may extend over the outer surface 210 of the sleeve 200 several patterns, e.g. spiral pattern (figure 9A), a grid pattern (figure 9B).

[0101] Figure 9A shows a top view of a sleeve one which the grooves follow a spiral pattern. The groove 250 extends as a spiral over the outer surface 210 of the sleeve 200. The spiral groove 250 extends from one free edge 201 to the opposite free edge 202 of the sleeve 200. Preferably, the spiral groove covers enough grooved area Ag such that at most 50 %, preferably between 5 - 45 % of the total area At of the outer surface 210 of the sleeve is covered by a groove area Ag. It is preferred that total circumferential surface area At has at least at least 50 %, preferably at least 65% of even surface area. At least 50 %, preferably at least 65% of the total circumferential surface area At can be areas 240 without the one or more grooves 250. The even areas 240 can be made rough so that they have a rough texture. Roughening can be provided via any suitable technique, examples are the use of abrasive materials like sandpaper, chemical treatments and / or mechanical processes such as sandblasting.

[0102] Preferably, the outer surface 210 of the sleeve 200, in particular the areas in between the grooves 250 may have a rough texture having a roughness Ra value in the range of 10 pm - 300 pm. Preferably, the surface areas in or making up the grooves 250 are and / or are made smoother than the areas 240 in between the grooves. By having a groove 250 with a smooth internal surface area, an improved gas escape can be provided. In such embodiments, the areas 240 at the surface between the grooves 250 can have a first roughness Rai value and the areas within the one or more grooves 250 have a second roughness value Ra2, wherein Rai is higher than Ra2. A high Ra value indicates a rougher surface texture. Conversely, a low Ra value indicates a smoother surface texture. Preferably, the Rai is at least 1.2 times higher, more preferably 1.4 times than Ra2. The value Rai can be chosen from a value in the range of 10 pm - 300 pm.

[0103] Figure 9B illustrates an example wherein the grooves are arranged as a grid pattern, in the grid shown the grooves 250 making up the grid intersect. Generally, the grooves may extend over the outer surface along any pattern. Preferably a pattern designed such that at least 0,1 to 10 distinct grooves are present per square centimeter of the outer surface area 210 of the sleeve 200. In figure 9B, several distinct grooves make up the grid of grooves 250. Notably, figures 8 to 9 are mere examples as the grooves 250 can extend over the outer surface 210 of the sleeve 200 following any suitable shape or line. The grooves may extend over the surface of the sleeve following any suitable shape or line. Preferably, a shape chosen from: straight lines, curved lines, helical lines, zigzag lines, periodic or non-periodic wave lines, meandering lines, lines which form a shape or a lettering or a logo or combinations thereof. In the case of a lettering, it is generally preferred that the letters are formed as grooves that are connected to each other so as to allow a gas transfer via said connection from one letter to another. In this manner, improved gas escape can be achieved resulting in less bubble formation.

[0104] Figures 10A - 10D show cross-sectional side views of a sleeve 200 mounted on an adapter 300 which is mounted on a mandrel 400 according to embodiments of the invention. As such, it forms an assembly with a sleeve 200, the adapter 300 and the mandrel 400. Preferably, the assembly further includes printing plate 100, placed fully or partially over the one or more grooves 250 on the outer surface of the sleeve 200. Figures 10A-10D shall now be used to explain several ways of adapter 300 and mandrel 400 configurations.

[0105] In figure 10A the mandrel has an inlet 401 and several outlets 402. The adapter 300 is correspondingly configured to receive gas from the mandrel’s outlets 402 and to guide the gas via the gas guides 350 to the outer surface of the adapter 300 such that a gas cushion can be provided between the outer surface of the adapter 300 and the inner surface of the 210 of the sleeve 200. Indeed, the one or more gas guides 350 of the adapter 300 can be arranged in several ways, for example as shown in figures 10A-10D.

[0106] In figure 10B, it is shown that mandrel 40 has several gas outlets 402 distributed over and cylindrical body of the mandrel 400 as seen along the longitudinal axis. Each gas outlet 402 of the mandrel corresponds to an individual gas guide 350 through the wall of the adapter. The gas guides provide gas at distinct and distributed locations over het outer surface 320 of the adapter. In this manner, a better cushion effect may be created so that the sleeve 200 may be slid more easily over the outer surface 320 of the adapter 300.

[0107] In figure 10C, it is shown that the adapter 300 may have an opening 301 in the side surface of the adapter 300 which acts as a gas inlet 301. This gas inlet can be configured to receive gas from an external gas supply. In this manner, the gas may be provided to the gas guides 350 of the adapter 300 in an improved manner. Figure 10D illustrates the mandrel having the gas outlets 402 arranged at the same longitudinal position. This means that gas outlets 402 are arranged at a similar or the same distance from an end of the mandrel 400. Figure 10B illustrates the mandrel having several gas outlets being distributed as seen along the longitudinal length. This means that the gas outlets 402 of the mandrel 400 are arranged at different distances from an end of the mandrel.

[0108] Figures 11A - 11C illustrate perspective views of a sleeve according to embodiments of the invention. The figures show the sleeve 200 having an outer surface 210 and an inner surface 220. The outer surface has a groove 250. Notably, one or more grooves 250 may be present and the grooves can have any of the arrangement and features as described earlier above. The sleeve 200 further has a side surface 230. The side surface 230 typically extends substantially perpendicular to the inner and outer surface. Figures 11A - 11C indicate that the sleeve may have a layered structure. As shown, the sleeve 200 is constructed as a layered structure having an outer layer 211 and an inner layer 212.

[0109] The inner layer 212 is understood as the layer positioned on the inner side of the sleeve 200, closer to the printing mandrel 400 or adapter 300. The inner layer 212 is preferably configured to facilitate the smooth sliding and positioning of the sleeve 200 on the printing mandrel 400 or adapter 300. The outer layer 211 is the layer of the sleeve that is positioned on the outer side, closer to the external environment responsible for securely holding a printing plate (not shown). Preferably, the outer layer 211 is formed from a non-metallic material, chosen from a polymer, a ceramic, a reinforced polymer, a foam, a rigid material, an elastic material, or combinations thereof. Preferably, the inner layer 212 is a fiber reinforced layer. The presence of fiber reinforcement enhances the strength and durability of the sleeve. The fibers used can be chosen from glass, carbon, or aramid fibers. An additional layer (not shown) may be present between the inner layer 212 and outer layer 211. Preferably, the additional layer has an elastic modulus, as measured via ISO 178, in the range of 50 to 1200 MPA. This flexibility enables the sleeve to accommodate variations in the size and shape of the printing mandrel or adapter, providing a better fit and ensuring a secure grip. Preferably, the additional layer has a flexural strength, as measured via ISO 178, in the range of 2,0 to 50 Mpa. Flexural strength, also known as bending strength, is a measure of a material’s ability to resist deformation preferably on or fracture when subjected to bending forces. By having flexural strength within the range as mentioned, any distortion or warping of the sleeve is can be avoided for ensuring consistent performance.

[0110] Preferably, the additional layer has a compressive strength, as measured via ISO 604, in the range of 1 ,0 to 60 Mpa.

[0111] In figure 11 A the groove 250 extends over the outer surface reaches both free edges 201 and 202. In figure 1 IB the grooves 250 extends over the outer surface and remain at a distance of both free edges 201 and 202. In figure 11C, the bottom of the groove 250 has an opening 236 which is connected to opening 235 in the side surface 230 of the sleeve via a channel 260 (see for example the cross- sectional view in figure 8B). Channel 260 preferably extends through the circumferential wall in longitudinal direction of the sleeve. The interior of channel 260 is preferably kept isolated from the inner surface 220 of the sleeve 200. Channel 260 may be configured to connect a bottom of the groove 250 with an opening 235 in a side surface 230 of the sleeve 200. The opening 235 may be positioned at the side surface 230 or on the outer surface 210 near the side surface 230 or both, preferably the opening 235 is positioned at the side surface. Figure 11C only shows one groove, however is it understandable that several grooves can be present each connected to a channel for gas escape, for example each groove can be connected to their own channel or to an interconnected network of channels under the outer surface 210 of the sleeve, wherein said network is configured for allowing gas escape.

[0112] Figure 11 A further illustrates that sleeve 200 has a wall thickness Tw as measured between the outer surface 210 and inner surface 220. The wall thickness Tw preferably has a value of at least 0.5 mm, preferably 0.5 mm to 3 mm, more preferably 0.8 mm to 2.2 mm. By having the wall thickness of at least 0.5 mm structural integrity and strength to the sleeve is provided. A thicker wall enhances the sleeve’s resistance to deformation. Figure 11B and figure 12 illustrate that the one or more grooves 250 typically have a depth (figure 12 shows a partial cross section through section line BB in figure 1 IB). The depth dtof the one or more grooves 250 is illustrated as a vertical measurement from the outer surface 210 of the sleeve 200 to the lowest point of the groove. The vertical direction is here understood as the radial direction as the sleeve shown is cylindrical. Preferably, the one or more grooves 250 have a depth dtwhich is at least 5 %, preferably at least 10 %, more preferably at least 15 % and / or at most 85 %, preferably at most 95 % of the wall thickness Tw (see e.g. figure 11B). Preferably 20 - 90 % such that the groove allows for a good gas escape and maintains a good structural integrity or mechanical stability of the sleeve 200.

[0113] Figure 12 illustrates a partial cross-sectional view along section line BB of figure 11B. Notably, figure 12 forms an enlarged view to illustrate that the outer surface 210 can have a rough texture preferably having a roughness Ra value in the range of 10 pm - 300 pm. In particular in the areas 240 between the grooves 250. Such rough texture facilitates a secure and reliable attachment. In particular, if attached via a double-sided tape.

[0114] The one or more grooves 250, as seen from a cross section, can have several possible cross-sectional shapes. Figure 12 illustrates a triangle shape. However, also other shapes are possible and may be chosen from, a square, a rectangle, a trapezoid, a partial circle, a partial ellipse, a regular or irregular shape with multiple edges, or combinations thereof. Figure 12 further illustrates that the one or more grooves 250 may have an upper width Wuand a lower width Wi. Preferably the upper width is in the range of 0,01 to 1 mm. The lower width Wi is preferably equal to or lower than an upper width Wu. In another embodiment, the lower width Wi is larger than the upper width Wu. In this manner, more support is given while the larger lower width ensures more room such that a larger volume of gas may escape. Figure 12 further illustrates the groove having a depth dt. The depth of the one or more grooves 250 is preferably in the range of 0,01 to 6 mm, more preferably 0,1 to 5 mm, even more preferably 0,2 to 2 mm for allowing sufficient gas escape.

[0115] Figure 13 illustrates schematically that the sleeve 200 holds a printing plate 100, the sleeve is mounted on a mandrel 400 within a printing apparatus PA. Preferably the sleeve 200 holds the printing plate 100 by aid of a double-sided tape (now shown). The sleeve 200 has grooves 250 at the outer surface. Optionally, an adapter (not shown) may be arranged between the mandrel and the printing plate 100. In this manner, the sleeve 200 with the printing plate 100 can be used for printing by transferring ink to a substrate S. Generally, the grooves are preferably arranged or distributed along the whole circumference of the outer surface 210 of the sleeve 200. Improved print results can be achieved since gas is allowed to escape via the one or more grooves 250. In this manner, bubble formation is avoided or reduced which may otherwise negatively impact print quality.

[0116] The skilled person will appreciate on the basis of the above description that the invention can be embodied in different ways and on the basis of different principles. The invention is not limited to the above described embodiments. The above described embodiments and the figures are purely illustrative and serve only to increase understanding of the invention. The invention will not therefore be limited to the embodiments described herein, but is defined in the claims.

Claims

Claims1. A method for installing a printing plate (100) on an outer surface (210) of a sleeve (200), wherein the outer surface (210) of the sleeve is provided with one or more grooves (250) for allowing a gas to escape from between the printing plate and the sleeve; the method comprising: installing the printing plate (100), preferably with an adhesive double-sided tape (150), on the sleeve (200) over the one or more grooves (250) and such that gas between the printing plate (100) and the sleeve (200) is allowed to escape via the one or more grooves.

2. The method according to the previous claim, further comprising: mounting the sleeve (200) with the printing plate (100) being installed thereon on an outer surface (310) of an adapter (300) or directly on an outer surface (410) of the mandrel (400) while providing a gas cushion, such as an air cushion, between an inner surface (220) of the sleeve (200) and an outer surface (310) of the adapter (300) or an outer surface (410) the mandrel (400); and wherein the gas in the gas cushion is kept separate from gas in the one or more grooves (250) of the sleeve (200).

3. The method according to the previous claim, further comprising: installing the mandrel (400) on which the sleeve is mounted, optionally while the adapter is arranged between the sleeve and the mandrel, in a printing apparatus.

4. The method according to any of the previous method claims, further comprising: cleaning the sleeve (200) before the printing plate (100) is installed thereon.

5. The method according to any of the previous method claims, wherein installing the printing plate comprises applying the adhesive double-sided tape at least partially over the one or more grooves and adhering the printing plate on a top side of the adhesive double-sided taped, wherein preferably the printing plate has a bottom side having a surface area which corresponds to the surface area of the top side of the adhesive double-sided tape.

6. A sleeve (200) with an outer surface (210) for holding a printing plate (100), wherein the sleeve has an inner surface (220) configured to be mounted on an adapter (300) or directly on a printing mandrel (400) by aid of a gas cushion supplied between the inner surface (220) of the sleeve (200) and an outer surface (310) of the adapter (300) or an outer surface (410) of the mandrel (400);wherein the outer surface of the sleeve is provided with one or more grooves (250) for allowing gas to escape from between the printing plate and the sleeve.

7. The sleeve according to the previous claim, wherein the outer surface (210) has a total circumferential surface area At, wherein at least 50 %, preferably at least 65%, more preferably at least 75%, even more preferably at least 85 % of the total circumferential surface area At of the outer surface of the sleeve (200) is even such that, when printing, a uniform supporting pressure is given by the outer surface (210) of the sleeve (200) to the printing plate (100).

8. The sleeve according to the previous claim, wherein the one or more grooves (250) extend over a total grooved area Ag, wherein said total grooved area is at most 50% of the total circumferential surface area surface At of the outer surface of the sleeve (200) and preferably between 0,3 - 50 % of the total surface area surface At, more preferably between 1 - 35 %, even more preferably between 2 - 25 %.

9. The sleeve according to any of the previous sleeve claims, wherein the grooves (250) include a plurality of grooves distributed over the outer surface (210) of the sleeve (200), preferably equally distributed.

10. The sleeve according to the previous claim, wherein individual grooves within the plurality of grooves intersect or do not intersect with each other.

11. The sleeve according to any of the previous two claims, wherein the plurality of grooves are distributed over the outer surface (210) of the sleeve (200) such that at least 0,1 to 10 distinct grooves are present per square centimeter of the outer surface area (210) of the sleeve (200).

12. The sleeve according to any of the previous sleeve claims, wherein the one or more grooves (250) are isolated from the inner surface (220) of the sleeve, such that any gas transfer between the gas within the one or more grooves (250) and the gas of the gas cushion is prevented.

13. The sleeve according to any of the previous sleeve claims, wherein the inner surface (220) of the sleeve (200) is configured to slide over the outer surface (310) of the adapter (300) or the outer surface (410) of the mandrel (400).14.The sleeve according to any of the previous sleeve claims, wherein the outer surface (210) of the sleeve (200) has a rough texture having a roughness Ra value in the range of 10 pm - 300 pm.

15. The sleeve according to any of the previous sleeve claims, wherein the sleeve has a wall thickness Tw as measured between the outer surface (210) and inner surface (220), said thickness having a value from 0.5 mm to 150 mm, more preferably 0.5 mm to 135 mm.

16. The sleeve according to the previous claim, wherein the one or more grooves (250) have a depth in the range of 0,01 to 2 mm, preferably in the range of 0,05 to 1 mm, more preferably in the range of 0,1 to 0,3 mm.

17. The sleeve according to any of the previous claims, wherein as seen from a cross section, the one or more grooves (250) have a cross-sectional shape chosen from: a triangle, a square, a rectangle, a trapezoid, a partial circle, a partial ellipse, a regular or irregular shape with multiple edges, or combinations thereof.

18. The sleeve according to any of the previous sleeve claims, wherein the outer surface of the sleeve has a hardness in the range of 30 Shore A and 99 Shore D.19.The sleeve according to any of the previous sleeve claims, wherein the sleeve has a total length Ls as measured between a first free edge (201) and second free edge (202) of the sleeve (200); and wherein at least one groove (250) has a longitudinal length Lg which is over at least 30 %, preferably at least 50 %, more preferably at least 75% of the total length Ls of the sleeve (200).

20. The sleeve according to any of the previous sleeve claims, wherein the sleeve (200) is a layered sleeve structure comprising an outer layer (211) for holding the printing plate (100); and an inner layer (212) for sliding over the mandrel or over the adapter.

21. The sleeve according to the previous claim, wherein the outer layer (211) is formed from a non- metallic material, chosen from a polymer, a ceramic, a reinforced polymer, a foam, a rigid material, elastic material, or combinations thereof.

22. The sleeve according to any of the previous two claims, wherein the inner layer (212) is a fiber reinforced layer.

23. The sleeve according to any of the previous three claims, wherein the layered sleeve structure further comprises an additional layer between the inner and outer layer, said additional layer having at least one of the following properties: an elastic modulus, as measured via ISO 178, in the range of 0,05 to 700 GPA; a density in the range of 0,15 to 2,0 g / cm3; a flexural strength, as measured via ISO 178, in the range of 2,0 to 50 Mpa; a compressive strength, as measured via ISO 604, in the range of 1,0 to 60 Mpa.

24. The sleeve according to any of the previous sleeve claims, wherein the sleeve has a side surface (230) substantially perpendicular to the outer surface of the sleeve (200), and wherein the one or more grooves (250) extend until a free edge (231) between the side wall (230) and outer surface such that a channel connection is formed between the outer surface and the side surface for allowing gas to escape via the channel connection; and / or wherein at least one groove (250) is connected to a channel extending between the outer surface (210) and the inner surface (220) of the sleeve (200) and wherein said channel is connected to an opening (235) in the side surface (230) of the sleeve for allowing gas to escape via said side surface.

25. The sleeve according to any of the previous sleeve claims, wherein the one or more grooves (250) have an upper width in the range of 0,01 to 1 mm.

26. The sleeve according to any of the previous sleeve claims, wherein the one or more grooves (250) have a lower width equal to or lower than an upper width.

27. The sleeve according to any of the previous sleeve claims, wherein the one or more grooves (250) have a depth in the range of 0,01 to 2 mm.

28. Use of the sleeve (200) according to any of the previous sleeve claims, wherein said sleeve is used to receive a printing plate (100), preferably wherein the printing plate is taped to the sleeve; and wherein the sleeve with the printing plate is subsequently used for printing.

29. An assembly comprising the sleeve (200) as defined in any of the previous sleeve claims and a printing plate (100), wherein the printing plate (100) is installed on the outer surface (210) of the sleeve (200) over the one or more grooves (250) such that gas from an interface between the printing plate and the sleeve is allowed to escape.

30. An assembly comprising the sleeve (200) as defined in any of the previous sleeve claims, wherein the sleeve is mounted directly on a printing mandrel (400), preferably the assembly further comprises a printing plate (100) installed on the outer surface (210) of the sleeve (200) over the one or more grooves (250) such that gas from an interface between the printing plate and the sleeve is allowed to escape.

31. An assembly (700) for printing with a printing plate (100), said assembly comprising the sleeve (200) as defined in any of the previous sleeve claims, wherein the sleeve is mounted on an adapter (300) which is mountable on a printing mandrel (400), preferably the assembly further comprises a printing plate, wherein the printing plate (100) is installed on the outer surface of the sleeve (200) over the one or more grooves (250) such that gas from an interface between the printing plate (100) and the sleeve (200) is allowed to escape.

32. The assembly (700) according to the previous claim, wherein the adapter (300) is provided with one or more gas guides (350) so as to guide gas to an interface between the inner surface (210) of the sleeve (200) and an outer surface (320) of the adapter (300) for providing a gas cushion in between, wherein the gas of the gas cushion is for example compressed air or N2.

33. The assembly according to any of the claims 31-32, wherein the printing plate (100) is adhered to the outer surface (210) of the sleeve (200), preferably with a double-sided tape (150).

34. The assembly according to the previous claim, wherein the double-sided tape (150) has the same surface area as a bottom surface area of the printing plate (100).

35. A manufacturing method for manufacturing a sleeve (200) for holding a printing plate (100), said sleeve having an outer surface (210) and an inner surface (220) to be mounted on an adapter (300) or directly on a printing mandrel (400) by aid of a gas cushion supplied between the inner surface (220) of the sleeve (200) and an outer surface (310) of the adapter (300) or an outer surface (410) of the mandrel (400); wherein the method for manufacturing the sleeve comprises the steps of: providing a sleeve (200) and creating at least one or more grooves (250) in an outer surface of the sleeve; or generating a sleeve layer (200) with the one or more grooves (250) via 3D printing; optionally, treating the sleeve having the one or more grooves with one or more processsteps chosen from: grinding, polishing, deburring, blowing out, washing, blasting, brushing, plasma treatment or combinations thereof.

36. The manufacturing method according to the previous claim, wherein the one or more grooves are created with one or more of: scribing, milling, lasering, burning, melting, etching, dissolving, sawing, cutting, blasting, grinding, punching or embossing.

37. The manufacturing method according to the previous claim, wherein the one or more grooves are created with one or more of scribing, milling, laser ablation, cutting.

38. The manufacturing method according to any of the claims 35-37, wherein the method further comprises: roughening the outer surface (210) of the sleeve (200), preferably roughening via dry grinding, roughening via plasma treatment, roughening via sandpaper or placing an open cell foam structure over the outer surface.

Images