Method for Decorating Natural Leather

Abstract

A method of decorating natural leather using an inkjet printing machine, the inkjet printing machine comprising: - a first vacuum belt (150) for conveying a non-woven fabric (200) configured as a second vacuum belt for conveying natural leather (300) under an inkjet print head (505); and wherein the method comprises: - applying a tape (1300) as a continuous sheet against the non-woven fabric from a tape roll, wherein the tape (1300) has an adhesive side and an opposite side, and the opposite side contacts the non-woven fabric; - applying natural leather (300) on the adhesive side of the tape (1300); - conveying the applied natural leather by moving the first vacuum belt (150), whereby the non-woven fabric (200) is moved by suction through the first vacuum belt (150), and the applied tape (1300) is moved under the inkjet print head (505) by the suction through the non-woven fabric (200); - marking the applied natural leather with droplets ejected by the inkjet print head (505) for decorating the natural leather while the tape (1300) is attached to the non-woven fabric (200).

Description

Technical Field

[0001] This embodiment relates to the manufacture of decorated natural leather by an inkjet printing press. Background Art

[0002] The manufacture of natural leather products is well-known and can generally be divided into five stages. Preparation stage 1 usually occurs partly at the abattoir and partly at the tannery, while stages 2 to 4 occur at the tannery and stage 5 occurs at the leather goods manufacturer. In the first stage, i.e., the preparation stage, the hide is removed from the animal (skinned) and pre-treated for the second stage of tanning. The pre-treatment can involve processes such as soaking, liming, dehairing, splitting and pickling (adjusting the pH value to aid the penetration of the tanning agent). In the tanning stage, the proteins of the raw hide or skin are converted into a stable material that will not decay. Chromium is most commonly used as the tanning agent, where the tanned product obtains a light blue color and is thus commonly referred to as "wet blue". In the third stage of crusting, the tanned leather is dried and softened. Crusting generally includes processes such as stripping (removing surface-fixed tannins), fatliquoring (fixing fats, oils and waxes to the leather fibers), dyeing, whitening, physical softening and buffing (abrasive grinding of the leather surface to reduce grain surface defects). In the fourth stage, called the finishing stage, the leather is prepared for sale to the leather goods manufacturer. Finishing operations can include painting, polishing and embossing. In the fifth stage, leather goods are manufactured, involving processes that can include cutting, punching, stitching, leather wrapping, decoration and embossing.

[0003] Natural leather has been decorated in the past by screen printing. However, screen printing is labor-intensive as a separate screen is required for each color. This is expensive and time-consuming, especially when personalization or customization is desired.

[0004] Digital printing techniques on finished leather have been studied, but many solutions for finished leather are still of poor quality. Inkjet technologies from textile printing using thermal transfer paper have been explored for leather printing. However, just like direct inkjet printing onto natural leather, it has been found that the process of inkjet printing a dye-based image onto a transfer paper and then transferring the image to the tanned leather by heating results in an unacceptable quality for many luxury leather products. Examples of such inkjet processes are disclosed in WO01 / 32434A (GILHAM) and US 2016067984A (CHUNG).

[0005] WO2019042952 (AGFA NV) discloses several methods for clamping natural leather on a support for decorating the natural leather by an inkjet printing method. Another way of pressing natural leather is disclosed in KR20170143170 (CHAE MYUNG SUK), in which a sheet is used to convey and support the natural leather in an inkjet printer.

[0006] Due to the forces between the interwoven fibers of the natural leather, it is not easy to process the natural leather on the support of an inkjet printer. Even during printing, the forces cause wrinkles, and the wrinkles lead to frequent collisions with the print head of the printer. The tufted leather side also makes processing on the support not easy. Increasing the ejection distance can overcome the collisions, but this results in a blurred inkjet printed decoration image. A vacuum support can help flatten the natural leather, but the forces and the leather side of the fibers and tufts (370) cause the leather to adhere uncontrollably to the vacuum support, especially at the edges of the natural leather.

[0007] When preparing the natural leather at the input side of an inkjet printer, the natural leather requires sufficient support. The same applies to the output side of the inkjet printer. The heavy natural leather may be of large size or multiple decorative pieces need to be produced quickly. A vacuum belt with high-precision transmission and sufficient stiffness may then become very expensive because the vacuum belt and thus the vacuum table should have a large length for arranging the large natural leather or multiple pieces at the input side and also for removing the leather at the output side of the inkjet printer. This makes the cost of manufacturing such an inkjet printer very high when speed accuracy / step accuracy still needs to be very high to achieve precise printing and high printing quality.

[0008] Therefore, there is a need to obtain a reliable inkjet printer for performing an efficient and fast method for manufacturing high-quality decorated natural leather, wherein the method avoids collisions with expensive print heads, is easy to mount the natural leather in the inkjet printer, and this applies to all kinds of natural leather, such as leather from cows, goats, snakes, etc., all of which have all different kinds of leather sides that need to be attached to the inkjet printer. SUMMARY OF THE INVENTION

[0009] To overcome the above problems, a preferred embodiment of the present invention has been achieved by a method for decorating natural leather using inkjet technology according to claim 1.

[0010] The present invention can be part of a production line for natural leather for decoration, wherein the production line can include other decoration techniques such as cooling, air inflation, embossing, laser ablation, laser marking, top coating, and the like, and it can include post-printing techniques such as cutting, folding, punching, and stitching. Therefore, an object of the present invention is also a manufacturing method for natural leather for decoration.

[0011] This embodiment is carried out by an inkjet printer, which includes two vacuum belts:

[0012] - A first vacuum belt (150), which is used to convey a second belt, and the second belt is adapted to convey a tape on which natural leather is applied below an inkjet print head (505). The inkjet print head (505) is used to print an image on the natural leather for decoration or even as an identification.

[0013] In this embodiment, the second belt is a vacuum belt, and more preferably a non-woven fabric (200) configured as a vacuum belt, and most preferably a felt configured as a vacuum belt.

[0014] WO2018 / 087119 (AGFA NV) discloses a comparable inkjet printer having such a "double-belt system".

[0015] This embodiment is a method for decorating natural leather, and the method includes:

[0016] - Applying a tape (1300) from an adhesive tape-roll, preferably as a continuous sheet against the non-woven fabric, wherein the tape (1300) has an adhesive side and an opposite side, and the opposite side contacts the non-woven fabric;

[0017] - Applying natural leather (300) on the adhesive side of the tape (1300);

[0018] - Conveying the natural leather by moving the first vacuum belt (150), whereby the non-woven fabric (200) is moved by the suction power through the first vacuum belt (150), and the applied tape (1300) is moved below the inkjet print head (505) by the suction through the non-woven fabric (200);

[0019] - Marking the applied natural leather with the ejected droplets of the inkjet print head (505) to decorate the natural leather while the tape (1300) is attached to the non-woven fabric (200).

[0020] The tape in the present invention has a thickness between 0.01 mm and 0.50 mm, preferably between 0.02 mm and 0.2 mm. The tape requires some kind of hard support in order to apply the natural leather flatly. The support is provided by the second vacuum belt. When the tape is directly applied on the first vacuum belt without using the second conveyor belt, the tape is sucked into the pores of the first vacuum belt, which results in poor flatness of the applied natural leather.

[0021] Using the second vacuum belt results in an inexpensive system with sufficient stiffness for applying the tape and the natural leather, even where the second vacuum belt is not supported on the first vacuum belt at the input side of the inkjet printer, where multiple panes can be applied, or one or more applied natural leathers can be scanned to know their contours and / or defects. Furthermore, at the output side, post-treatment of the decorated natural leather can be carried out while one or more decorated natural leathers are supported on the tape and the second vacuum belt, even if the second vacuum belt is not supported on the first vacuum belt.

[0022] Thus, the one or more natural leathers are preferably pressed against the adhesive side of the tape (1300) by an extrusion device. The extrusion device preferably includes a portion that frictionally traverses a portion of the natural leather (300) through relative movement between the pressing device and the tape (1300) carrying the natural leather (300). Thus, this portion traverses one side of the natural leather, where, over a period of time, this portion moves along the surface of the side with pressure (= friction).

[0023] The nonwoven fabric (200) preferably has an air permeability of less than 90 L / (dm 2 x min) or more preferably less than 70 L / (dm 2 xmin) and higher than 5 L / (dm 2 x min). Using felt as the nonwoven fabric (200) has thus been found to be a good material, whereby the tape (1300), including its edges, is held attached to the nonwoven fabric (200) by vacuum power.

[0024] The nonwoven fabric (200) may have an adhesive layer for additionally adhering the opposite side of the tape (1300) to the nonwoven fabric (200), and / or the tape (1300) also includes an adhesive layer on its opposite side for additionally adhering the opposite side of the tape (1300) to the nonwoven fabric (200). Such tapes are sometimes referred to as double-sided tapes.

[0025] The nonwoven fabric (200) itself is breathable and thus does not require additional perforations. The air permeability of the nonwoven fabric (200) is preferably less than 90 L / (dm2 x min).

[0026] Furthermore, it has been found that a felt, as the nonwoven fabric (200), while supporting the natural leather, gives the best results for pressing the tape against the felt. The felt preferably has no adhesive layer,

[0027] because it is not needed and this would cause glue contamination on the tape. The felt is preferably a polyester felt.

[0028] These and other objects of the present invention will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 An inkjet printer (500) suitable for inkjet printing on natural leather (300) according to the present invention is illustrated. The inkjet printer is illustrated as a TAURO from manufacturer AGFA NV TM .

[0030] Figure 2 , Figure 3 and Figure 4 illustrates a cross-sectional view from a preferred embodiment of the present invention, in which a print head (505) of an inkjet printer (500), not shown, prints an image (305) on natural leather (300), and a dryer (510) dries the image (305). The natural leather is conveyed on a tape (1300) which is supported on a nonwoven fabric (200) configured as a vacuum belt. The nonwoven fabric (200) is conveyed by another vacuum belt (150). The other vacuum belt (150) surrounds an upstream pulley (905), a downstream pulley (907) and a vacuum table (900). The conveyance of the natural leather (300) for printing proceeds from left to right as indicated by the curved arrow. The natural leather (300) is pressed against the nonwoven fabric (200) by a pressing device (700) having a portion (705), which is illustrated as a flat portion herein.

[0031] Figure 2 In is the nonwoven fabric (200) surrounding an upstream sliding support (805) and a downstream sliding support (807). Figure 3 and Figure 4 In is the nonwoven fabric (200) surrounding a plurality of pulleys (815, 817).

[0032] In Figure 4In the preferred embodiment of the inkjet printing press, additional features are added: a media set bar (600), a camera system (1004), a cutter (1005), and a regulator (1008) for guiding the second conveyor belt. The media set bar (600) also includes a pressure roller to press the leather against the tape.

[0033] Figure 5 A cross-sectional view of a pressure device (700) with a part (705) from a preferred embodiment of the present invention is illustrated.

[0034] Figure 6 , Figure 7 A top view and a cross-sectional view of a preferred embodiment of the present invention are illustrated. Natural leather (300) is carried on a tape (1300), which is supported on a non-woven fabric (200) configured as a vacuum belt. The vacuum belt is carried on another vacuum belt (150). The natural leather (300) has a grain side (350) and a leather side (370). The non-woven fabric (200) has a fiber layer (250) in contact with the leather side (370).

[0035] In Figure 7 an image (305) is inkjet printed on the natural leather (350). The non-woven fabric (200) consists of one fiber layer herein. Detailed Description

[0036] Natural leather

[0037] On the Jeti Tauro manufactured by AGFA NV TM problems were found with directly mounting natural leather (300) on its vacuum belt, because the vacuum power suction in this printing device was insufficient and because it was difficult to avoid wrinkles that collided with the print head (505) of this printing device. This embodiment is a solution for this, by extending the printing device with a non-woven fabric (200) configured as a second vacuum belt and applying a tape (1300) on the non-woven fabric (200), which is pressed by vacuum power. The natural leather (300) is applied on the tape (1300), which is the result of unwinding a tape roll.

[0038] Natural leather (300) comes in different grades, such as full grain, top grain, and split leather (also known as second layer leather). Top grain is basically full grain, but a part of the grain layer is sanded and the underlying split is removed. For the latter, the lower layer of the hide is removed and used to form split leather. Depending on the thickness of the lower layer, many splits can be formed. Split leather has a rough appearance and is usually used to make suede.

[0039] In this embodiment, natural leather (300) has two sides: a dermis side (370) and a grain side (350). The dermis side (370) is preferably the side that contacts the adhesive side of the tape (1300), and the grain side (350) is the side on which the image is printed.

[0040] To prevent the grain from being damaged and weakened, the hide or skin is preferably tanned with chromium, but other tanning methods such as vegetable tanning can also be used. After tanning, the leather is dried and softened into so-called semi-tanned leather. Semi-tanning may include processes such as stripping (removing surface-fixed tannins), fatliquoring (fixing fats, oils, and waxes to leather fibers), dyeing, whitening, physical softening, and buffing (grinding the leather surface to reduce grain defects). The natural leather (300) of this embodiment is preferably such semi-tanned leather. But it can also be raw hide, which is the animal skin removed from an animal. The animal skin is not tanned; or it can be a tanned hide, which is the raw hide tanned in a tannery. It is also called tanned natural leather or shortly tanned leather.

[0041] The hide can also be a part of the hide, such as the hip, abdomen, neck, leg, shoulder. The hide can also be full grain leather, top grain leather, or split leather.

[0042] The natural leather (300) of this embodiment can also be a hide piece used to manufacture leather products. The hide piece is also called a panel.

[0043] Inkjet printer

[0044] This embodiment is performed by an inkjet printer (500), but it can also be performed by any other printing device. The printing device marks a pattern on the surface of the natural leather (300), such as marking a pattern on the grain side (350) of the natural leather (300). Marking a pattern on the surface is also referred to as printing. The pattern represents an image, which can be text, a photo, a graphic, or a logo. The pattern is mainly the result of a halftone method of the image, such as the error diffusion method or the amplitude modulation halftone method. The pattern can have a colorless or colored color. By printing a pattern on the natural leather, the natural leather is decorated.

[0045] The input side of the inkjet printing device is the side where the natural leather is applied to the tape, and the output side of the inkjet printing device is the side from which the natural leather is removed from the tape (after printing or post-processing).

[0046] The marking of the printing device can be done by any conventional printing technique, such as offset printing, gravure printing, letterpress printing, screen printing. All of these conventional printing methods are described in: "Chapter 2. Printing Technologies With Permanent Printing Master", P204 - 448 in "Handbook of Print Media, Technologies and Production Methods" by Helmut Kipphan, ISBN 3 - 540 - 67326 - 1 Springer-Verlag Berlin Heidelberg New York, 2001. Such a printing device is also referred to as a conventional printing device.

[0047] Preferably, the printing apparatus in the present embodiment is a digital printing apparatus, such as an electrophotography-based apparatus, an imaging-based, a magnetography-based, an inkjet-based printing apparatus. Digital printing apparatuses are sometimes referred to as printing presses, and inkjet-based printing apparatuses are sometimes referred to as inkjet printers (500). All of these digital printing methods are described in "Chapter 4. Printing Computer to... Technologies" and "Subchapter 4.5 Computer to Print", P657 - 674, and "Chapter 5. Printing Technologies without a Printing Plate (NIP Technologies)", P676 - 758 of "Handbook of Print Media, Technologies and Production Methods" by Helmut Kipphan, ISBN 3 - 540 - 67326 - 1 Springer-Verlag Berlin Heidelberg New York, 2001. The printing apparatus may be a hybrid printing apparatus, in which conventional printing technologies are combined with digital and / or non-impact printing technologies in the printing apparatus.

[0048] Therefore, the preferred printing technology for the present embodiment is inkjet printing technology. Thus, the printing apparatus from the present embodiment is preferably an inkjet printer (500), which is a printing apparatus including an inkjet printhead (505). The inkjet technology may be continuous inkjet or drop-on-demand inkjet, which is preferably selected from the group consisting of thermal inkjet, piezoelectric inkjet, and electrostatic inkjet. The inkjet printer (500) is preferably a wide-format inkjet printer (500), where a printable width greater than 135 cm is common, but a printable width greater than 200 cm is also common. An example of such a wide-format inkjet printer in a multi-pass inkjet printing method is the Jeti Tauro manufactured by AGFA NV TM , which has a maximum printable width of 254 cm and can accommodate, for example, rigid media with lengths up to 400 cm. Another example of a wide-format inkjet printer using a single-pass inkjet printing method is the KBA RotaJet TM L-series.

[0049] An inkjet printer (500) may include a page-width inkjet printhead that covers the entire width or a width greater than that of the natural leather (300), i.e., a so-called single-pass inkjet printer. In a preferred embodiment, the pattern is inkjet printed in one pass, also known as the single-pass inkjet printing method, which ensures economic efficiency by having a greater throughput than the multi-pass inkjet printing method. Details regarding inkjet technology and the construction of inkjet printers can be found in "Inkjet Technology and Product Development Strategies" by Stephen F. Pond, Torrey Pines, 2000.

[0050] To enhance the adhesion of the pattern on the natural leather (300), the printing device may include a dryer to dry the marked pattern on the natural leather (300) and / or to make the marked pattern adhere better to the natural leather (300). In such a printing device, a typical dryer (510), sometimes also referred to as a curing device, includes an ultraviolet (UV) source and / or an infrared (IR) radiation source.

[0051] Drying of the marked pattern can be accomplished by radiation (UV and / or IR and / or NIR and / or SWIR) from the back side of the natural leather (300) to the printing side. Alternatively, drying of the marked pattern can be accomplished by radiation (UV and / or IR and / or NIR and / or SWIR) above the marked pattern.

[0052] Any ultraviolet light source can be used as a radiation source as long as it is part of the emitted light, such as a high-pressure or low-pressure mercury lamp, a cold cathode tube, a black light, a UV LED, a UV laser, and a flash lamp.

[0053] The IR source is preferably an NIR source ( = near-infrared source) such as an NIR lamp or an SWIR ( = short-wave infrared source) such as an SWIR lamp. The IR source may include a carbon infrared emitter, which has a very short response time. The IR source is also referred to as an infrared radiation source. The IR source may include a blower for blowing hot air heated by the IR source.

[0054] Expressed in another way, the printing device implementing this embodiment includes:

[0055] - A marking device for marking the natural leather (300), such as an inkjet head,

[0056] - A first vacuum belt (150) supported by an upstream pulley (P 上游 ) and a downstream pulley (P 下游 ) and including a printing area (A 印刷 ) and a vacuum area (A 真空 ).

[0057] - A pair of sliding supports for supporting a nonwoven fabric (200) configured as a second vacuum belt, wherein the pair of sliding supports includes a first sliding support (= upstream sliding support (S 上游 )) and a second sliding support (= downstream sliding support (S 下游 )); wherein the second sliding support (S 下游 ) is constructed downstream of the printing area (A 印刷 ) or the vacuum area (A 真空 ); and wherein the first sliding support (S 上游 ) is constructed upstream of the printing area (A 印刷 ) or the vacuum area (A 真空 ); and wherein the nonwoven fabric (200) configured as the second vacuum belt is supported at the printing area (A 印刷 ) or the vacuum area (A 真空 ). The sliding supports around which the nonwoven fabric (200) configured as the second vacuum belt is wound may each include a pulley.

[0058] The vacuum area (A 真空 ) preferably overlaps with the printing area (A 印刷 ) because adhesion by vacuum power during printing is very important for printing quality such as dot positioning accuracy. The printing area (A 印刷 ) (size and form) is mainly defined by the marking device and its movement (or not), such as a front - and - back movable inkjet print head in a multi - pass inkjet printer, and the vacuum area (A 真空 ) (size and form) is mainly defined by the orifices in the first vacuum belt (150) and the vacuum power of the vacuum table (900) below the first vacuum belt (150).

[0059] Before the printing area (A 印刷 ) of the printing device from this embodiment is an upstream area (A 上游 ), where natural leather (300) is applied to a tape in the printing device, supported by the second vacuum belt, and where the nonwoven fabric (200) configured as the second vacuum belt lands on the first vacuum belt (150) at the upstream belt contact position (C CB1,上游,CB2 ). Thus, the upstream belt contact position (C CB1,上游,CB2 ) is the contact position where the second vacuum belt lands on the first vacuum belt (150), and this contact position is at the upstream side of the printing device from this embodiment.

[0060] After the printing area (A 印刷 ) of the printing device from this embodiment is a downstream area (A 下游), wherein the natural leather (300) is removed from the tape in the printing device, and wherein the nonwoven fabric (200) configured as the second vacuum belt exits the first vacuum belt (150) at the downstream belt contact position (C CB1,下游,CB2 ). Thus, the downstream belt contact position (C CB1,下游,CB2 ) is the contact position where the nonwoven fabric (200) configured as the second vacuum belt exits the first vacuum belt (150), and this contact position is at the downstream side of the printing device from this embodiment.

[0061] The nonwoven fabric (200) configured as the second vacuum belt exits the upstream sliding support (S S,上游 ) at the upstream sliding support contact position (C 上游 ). The nonwoven fabric (200) configured as the second vacuum belt lands on the downstream sliding support (S S,下游 ) at the downstream sliding support contact position (C 下游 ).

[0062] The inkjet printer (500) may include a coating device for applying a primer coat on the natural leather (300) when the natural leather (300) is supported on the tape supported by the nonwoven fabric (200), or for applying a top coat on the decorated natural leather when the natural leather is supported on the tape supported by the nonwoven fabric (200).

[0063] Before the printing area (A 印刷 ) of the printing device from this embodiment is the upstream area (A 上游 ), wherein the natural leather (300) is inserted into / onto the printing device (input side), and wherein the natural leather (300) is attached to the first vacuum belt (150) at the upstream belt contact position (C CB1,上游,印刷接收器 ) and lands on the tape supported by the nonwoven fabric (200) configured as the second vacuum belt at the upstream belt contact position (C CB2,上游,印刷接收器 ).

[0064] * Thus, C CB1,上游,印刷接收器 is the contact position where the natural leather (300) attaches to the first vacuum belt (150), and this contact position is at the upstream side of the printing device from this embodiment.

[0065] * Thus, C CB2,上游,印刷接收器 is the contact position where the natural leather (300) lands on the tape supported by the second vacuum belt, and this contact position is at the upstream side of the printing device from this embodiment.

[0066] After the printing area (A 印刷 ) of the printing device from this embodiment is the downstream area (A 下游), wherein natural leather (300) is output from a printing device, and wherein natural leather (300) leaves the first vacuum belt (150) at a downstream belt contact location (C CB1,下游,印刷接收器 ), and leaves the tape supported by the non-woven fabric (200) configured as a second vacuum belt at a downstream belt contact location (C CB2,下游,印刷接收器 ).

[0067] * Thus, C CB1,下游,印刷接收器 is the contact location where natural leather (300) detaches from the first vacuum belt (150), and this contact location is on the downstream side of the printing device from this embodiment.

[0068] * Thus, C CB2,下游,印刷接收器 is the contact location where natural leather (300) leaves the tape supported by the second vacuum belt, and this contact location is on the downstream side of the printing device from this embodiment.

[0069] First vacuum belt

[0070] The inkjet printer (500) of this embodiment includes two vacuum belts:

[0071] - The first vacuum belt (150), which is used to convey a second belt, and this second belt is suitable for conveying natural leather (300) under the inkjet print head (505).

[0072] - The second vacuum belt is also a vacuum belt, and more preferably a vacuum belt made of non-woven fabric (200).

[0073] A conveyor belt is a belt used to convey a load such as natural leather (300). The conveyor belt has a support side and a back side, and the printed load is conveyed on the support side, and this back side contacts a pair of pulleys or sliding supports (805, 807).

[0074] The longitudinal axes of these pulleys are substantially parallel to convey the conveyor belt straight on these pulleys. These parallel pulleys are also called belt pulleys (905, 907). The first vacuum belt (150) is such a conveyor belt.

[0075] The width of the first vacuum belt (150) is the distance of the belt measured in a direction parallel to the pair of pulleys. The width of the belt is the distance between the edges of the conveyor belt that span the conveyor belt parallel to these parallel pulleys.

[0076] The length of the first vacuum belt (150) is the distance of the belt measured perpendicular to the parallel direction of the pair of pulleys. It defines the length of the loop formed by the belt.

[0077] The minimum path of the first vacuum belt (150) is the minimum distance that the belt can be conveyed on its pair of pulleys.

[0078] The conveying direction of the first vacuum belt (150) is perpendicular to the direction in which the belt is conveyed by a pair of pulleys around which the belt loops or forms a loop. The conveying direction of the first vacuum belt (150) defines the path followed by the belt on the pair of pulleys around which it loops.

[0079] The pulley is preferably a cylinder mounted on a central axis rod. The pulley includes a pulley cover that contacts the first vacuum belt (150).

[0080] The pulley may include a belt guide to prevent or minimize belt creep on the pair of pulleys. Belt creep is the phenomenon of the belt moving vertically from left to right or from right to left on the pulley in a direction perpendicular to the conveying direction.

[0081] In this embodiment, the first vacuum belt (150) also loops around the vacuum table (900). Accordingly, the first vacuum belt (150) includes a plurality of apertures through which a vacuum region (A 真空 ) can be generated in the printing apparatus by the vacuum power of the vacuum table (900). If, for example, the vacuum table (900) includes a plurality of vacuum sub-chambers, such a vacuum region may include a plurality of vacuum sub-regions. Accordingly, the first vacuum belt (150) is a permeable conveyor belt, more precisely a breathable conveyor belt, sometimes referred to as a porous conveyor belt. The bottom of the first vacuum belt (150), which is the back side, contacts the vacuum table (900), and the top of the first vacuum belt (150), which is the support side, includes a support area for the non-woven fabric (200) configured as the second vacuum belt in this embodiment. The looping of the conveyor belt is sometimes referred to in the literature as "forming a loop" around its pulleys. In this embodiment, the first vacuum belt (150) forms a loop around the vacuum table (900) and a pair of pulleys, namely the upstream pulley (P 上游 ) and the downstream pulley (P 下游 ).

[0082] The width of the first vacuum belt (150) is preferably between 1 meter and 10 meters, more preferably between 3 meters and 6 meters.

[0083] The printing apparatus from this embodiment preferably includes feature means to align the longitudinal axes of the pair of pulleys (P 上游 and P 下游 ) of this embodiment to become parallel to each other. Such adjusting means are known in the prior art. Using more than two pulleys around which the first vacuum belt (150) loops is also known in the prior art, especially additional pulleys are used to change the tension of the conveyor belt or to control the conveyor belt to have a straight path on the surrounding pulleys.

[0084] Printing devices with a vacuum belt are known in the prior art, and the vacuum belt is used to convey a printing receiver on which a pattern is marked. An example of such a printing device is the Jeti Tauro manufactured by AGFA NV TM manufactured by TM .

[0085] Preferably, the first vacuum belt (150) from this embodiment has two or more layers of material, wherein the lower layer provides linear strength and shape, also known as the carcass, and the upper layer is called the covering or support side. The carcass is preferably a woven fabric web, and more preferably a woven fabric web of polyester, nylon, fiberglass or cotton. The material of the covering includes preferably various rubbers, and more preferably plastic compounds, and most preferably thermoplastic polymer resins. The covering of the first vacuum belt (150) is, in a preferred embodiment of this embodiment, the side that supports the non-woven fabric (200) configured as the second vacuum belt in the vacuum area (A 真空 ) of the printing device. Since the non-woven fabric (200) in this embodiment is also a vacuum belt, the vacuum area (A 真空 ) is located at the non-woven fabric for adsorbing the tape (1300).

[0086] The carcass of the first vacuum belt (150) is, in a preferred embodiment of this embodiment, the side that contacts the pair of pulleys from this embodiment. The carcass is preferably impregnated with polyurethane in this embodiment to minimize the noise of conveying and rubbing the first vacuum belt (150) on the pair of pulleys and on the vacuum table (900).

[0087] The support side (top side, covering) of the first vacuum belt (150) preferably includes a thermoplastic polymer resin coated on a rough layer. The support area of this embodiment is preferably a ground engineering plastic composition, or includes polyethylene terephthalate (PET), polyamide (PA), high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyoxymethylene (POM) and / or polyaryletherketone (PAEK).

[0088] The top surface of the first vacuum belt (150) (and thus the covering on which the non-woven fabric (200) configured as the second vacuum belt from this embodiment is carried) includes preferably rigid polyurethane with a preferred thickness between 0.2 and 2.5 mm (measured from the top surface to the bottom surface). The total thickness of the first vacuum belt (150) (measured from the top surface to the bottom surface) is preferably between 1.2 and 7 mm.

[0089] The first vacuum belt (150) may include a thermoplastic intermediate layer for easily looping around the pair of pulleys from this embodiment.

[0090] The thickness of the first vacuum belt (150) is preferably between 1 mm and 5 mm; more preferably between 1.5 mm and 3.5 mm. The thickness of the first vacuum belt (150) is selected to carry the second conveyor belt and the natural leather (300), but in particular for said load, a thickness between 2 mm and 3 mm is preferred.

[0091] Measured from the back side of the first vacuum belt (150), the pitch line of the first vacuum belt (150) is preferably less than one third of the thickness of the first vacuum belt (150), more preferably less than one fifth of the thickness of the first vacuum belt (150), and this back side is the side that contacts the pulley it surrounds.

[0092] The pitch line of the first vacuum belt (150) is preferably between 0 and 2 mm; more preferably between 0 and 1 mm, and most preferably between 0.1 and 0.8 mm. These distances are measured from the back side of the first vacuum belt (150), and this back side is the side that contacts the pulley it surrounds.

[0093] This pitch line of the first vacuum belt (150) is important for high marking accuracy in this embodiment; especially in printing devices with high printing resolution and inkjet printing devices including inkjet heads capable of ejecting small droplets of less than 12 pL. The pitch line is the plane within the conveyor belt that neither undergoes stretching nor compression when the belt bypasses the pulley, that is, the neutral plane of the belt structure.

[0094] In order to better suck towards the non-woven fabric (200) configured as the second vacuum belt and the first vacuum belt (150) on the vacuum table (900), the first vacuum belt (150) has a plurality of holes so that air can be guided and sucked through the first vacuum belt (150). A plurality of these holes can be small in size, preferably with a diameter ranging from 0.3 to 10 mm, more preferably with a diameter ranging from 0.4 to 5 mm, most preferably with a diameter ranging from 0.5 to 2 mm, and preferably evenly spaced on the first vacuum belt (150), preferably spaced 3 mm to 50 mm apart, more preferably spaced from 4 to 30 mm apart, and most preferably spaced from 5 to 15 mm apart, so as to be able to generate a uniform vacuum pressure that sucks the non-woven fabric (200) configured as the second vacuum belt together with the first vacuum belt (150).

[0095] The first vacuum belt (150) is tensioned between a pair of pulleys from this embodiment. In this embodiment, this tension can be caused by aligning the parallel pulleys and / or widening the distance between the longitudinal axes of the pair of pulleys. This tension of the first vacuum belt (150) is important for heavy printing receivers and for the correct printing alignment of the marking pattern.

[0096] The first vacuum belt (150) is installed in a demanding procedure in a printing device, wherein the tension on the pair of pulleys is controlled and measured, for example, by widening the longitudinal axes from each other. The two edges (left and right) of the conveyor belt are also controlled to calculate the travel and / or drift of the conveyor belt on the pair of pulleys. By adjusting the tension, the travel and / or drift are controlled. The stability of the drift and / or travel and the tension of the first vacuum belt (150) are then controlled for more than one hour (= relaxation phase). If some deformation in the first vacuum belt (150) is seen during this demanding procedure, a waiting time of 12 hours is required for the relaxation of the first vacuum belt (150), after which the entire procedure must be restarted.

[0097] The effective tensile force on the first vacuum belt (150) must be at least equal to or even greater than the force required for slip-free conveyance.

[0098] The tensioning of the first vacuum belt (150) can be controlled by attaching an additional pulley around which the first vacuum belt (150) is looped and which can be angled relative to the longitudinal axis of the pair of pulleys. Such an additional pulley is sometimes referred to as an alignment pulley or alignment roller.

[0099] The conveyance of the first vacuum belt (150) is preferably driven by a motor, more preferably by an electric stepper motor; in order to generate a torque on one of its pulleys from the pair of pulleys by friction on the first vacuum belt (150) and the power pulley, the natural leather (300) on the tape (1300) and the non-woven fabric (200) configured as the second vacuum belt are conveyed in the conveyance direction. The use of an electric stepper motor enables more controllable conveyance of the natural leather (300), for example, for changing the conveyance speed and moving the load on the vacuum belt in continuous distances. An example of a conveyor belt with an electric stepper motor is described in EP 1235690 (ENCAD INC) for media conveyance in a wide-format printer. The preferred embodiment includes a system for conveying the first vacuum belt (150) in continuous distances also referred to as discrete step increments for conveying the natural leather (300) and the non-woven fabric (200) configured as the second vacuum belt.

[0100] Another way to convey the first vacuum belt (150) is through a belt stepping conveyor system with high-precision positioning capabilities due to a moving belt gripper mounted on a linear movement system, so as to convey the first vacuum belt (150) in continuous distances while the moving belt gripper engages the first conveyor belt, and the moving belt gripper moves from an initial position to an end position through this linear movement system. The first vacuum belt (150) is stalled by the engagement of a stationary belt gripper while the moving belt gripper moves back to its original position, otherwise the stationary belt gripper has released the conveyor belt. An example of such a conveyor system is disclosed in WO2014184226 (AGFA NV).

[0101] When conveying the first vacuum belt (150), any kind of encoder mechanism can be employed to control the linefeed distance. Generally, a rotary encoder is connected to the belt drive roller; belonging to this pair of pulleys. The information provided by the encoder is processed by the printing device to control the linefeed distance.

[0102] The printing device may include multiple conveyor belts as the first vacuum belt (150), which, for example, have different numbers of orifices to generate different vacuum forces.

[0103] The preferred first vacuum belt for this embodiment is disclosed in US20180264851 (AGFA NV), or the more preferred first vacuum belt for this embodiment is disclosed in EP3266619 (AGFA NV).

[0104] Vacuum table

[0105] The vacuum table (900) is a vacuum support. The vacuum chamber included in the printing device of this embodiment presses the natural leather (300) against the vacuum table (900). The natural leather (300) and the vacuum table (900) "clamp" the tape (1300), the first vacuum belt (150), and the non-woven fabric (200) configured as the second vacuum belt.

[0106] Preferably, the vacuum table (900) in this embodiment includes a set of air channels to provide a pressure difference through the vacuum chamber at the support layer of the vacuum table (900) to generate a vacuum area (A 真空 )), and includes a set of orifices connected to this set of air channels at the bottom surface of the printing table. These orifices at the bottom layer can be circular, oval, square, rectangular, and / or grooves parallel to the bottom layer of the vacuum table (900), such as slits.

[0107] The support layer of the printing table should be constructed to prevent damage to the natural leather (300), non-woven fabric, or vacuum support (if applicable). For example, the orifices connected to the air channels at the support layer may have rounded edges. The support layer of the printing table may be constructed to have low friction specifications.

[0108] The top surface of the vacuum table (900), also referred to as the support surface, or a part of the vacuum table (900), such as the inner side of its air channels, may be coated to have properties that are easy to clean (e.g., due to dust or ink leakage). The coating is preferably a dust-proof and / or ink-proof and / or hydrophobic coating. Preferably, the top surface of the vacuum table (900) or a part of the vacuum table (900), such as the inner side of its air channels, is treated by a hydrophobic method that repels ink by creating a smooth and repellent surface with reduced friction.

[0109] The vacuum support air channel is an air channel from the support surface to the bottom surface of the vacuum support. If the perimeter of the vacuum support air channel at the support surface is substantially circular, it is also referred to as a suction hole.

[0110] The area of the vacuum support air channel at the support surface of the vacuum support is preferably between 0.3 mm 2 and 5 mm 2 in this embodiment. More preferably, the perimeter of the vacuum support air channel at the support surface has the same shape as a circle, ellipse, oval, rectangle, triangle, square, rectangle, pentagon, hexagon, heptagon, octagon, or any polygon having at least three sides.

[0111] The vacuum support air channel preferably tapers in the direction of the bottom surface to achieve the best vacuum pressure effect at the support surface.

[0112] The distribution of the air channels on the support surface of the vacuum support is preferably between 1 air channel per dm 2 and 100 air channels per dm 2 , more preferably between 5 air channels per dm 2 and 50 air channels per dm 2 .

[0113] The perimeter of the suction hole is preferably from 0.3 to 10 mm in diameter, more preferably from 0.4 to 5 mm in diameter, and most preferably from 0.5 to 2 mm in diameter. Also referred to as the vacuum area (A 真空) The vacuum zone air channels in the suction zone are preferably evenly spaced on the vacuum support, preferably spaced from 3 mm to 50 mm, more preferably spaced from 4 mm to 30 mm, and most preferably spaced from 5 mm to 15 mm, so as to be able to generate a uniform vacuum pressure that holds the natural leather (300) against the vacuum support.

[0114] The vacuum chamber is a rigid enclosure made of many materials. Preferably, it may include metal. The material selection is based on strength, pressure, and permeability. The materials of the vacuum chamber may include stainless steel, aluminum, low-carbon steel, brass, high-density ceramics, glass, or acrylic fiber.

[0115] The vacuum pump provides a vacuum pressure inside the vacuum chamber, and the vacuum pump is connected to the vacuum pump input, such as an orifice in the vacuum chamber, through a vacuum pump connector such as a tube. Between the vacuum pump connectors, a vacuum controller such as a valve or a tap may be provided to control the vacuum in the sub-vacuum chamber in which the orifice is located.

[0116] A preferred vacuum table for this embodiment is disclosed in US9962963 (AGFA NV). Another preferred vacuum table for this embodiment is disclosed in US9573393 (AGFA NV).

[0117] Second vacuum belt

[0118] The inkjet printer (500) of this embodiment includes two vacuum belts:

[0119] A first vacuum belt (150) for conveying a second belt, which is adapted to convey natural leather (300) under the inkjet printhead (505).

[0120] - The second vacuum belt is a vacuum belt, and more preferably a vacuum belt made of a nonwoven fabric (200).

[0121] The nonwoven fabric (200) configured as the second vacuum belt in this embodiment has the function of supporting the natural leather (300) in this embodiment. The second vacuum belt thus surrounds at least two sliding supports that may be pulleys. The nonwoven fabric (200) configured as the second vacuum belt actually wraps around the first vacuum belt (150) and loops in the same direction as the first vacuum belt (150).

[0122] The area for applying the tape (1300) on the second vacuum belt is preferably larger than the natural leather (300) and is preferably flat. The tape (1300) partially covers the second vacuum belt to have good adhesion at the edge of the tape (1300). When the size of the second vacuum belt is the same as that of the tape (1300) and the tape (1300) completely covers the belt, the edge of the tape (1300) may wrinkle (wave or curl). This may cause the tape (1300) or the supported natural leather to collide with the print head (505) of the inkjet printer (500).

[0123] The second vacuum belt includes one or more fiber layers, and the other side (≠ the additional side) of the tape (1300) preferably contacts the fiber layer from the one or more fiber layers. The fiber layer is easily attached to the fiber and tufted true leather side (370). The fiber layer can be coated and / or be a non-woven fabric (200), such as felt. The felt can be wool felt, but preferably it is polyester felt. Recycled polyester felt can also be used. Polyester felt is most preferred because the felt has a tighter structure and they can be used at an operating temperature higher than 30 °C. The polyester felt can be mixed with other materials such as wool fabric.

[0124] To minimize the vacuum power for air suction in this embodiment, the air permeability of the second vacuum belt can be between 30 and 120 L / (dm 2 x min) at a pressure difference of 200 Pa, preferably between 35 and 90 L / (dm 2 x min). The air permeability can be measured by an AKUSTRON air permeability tester that complies with industrial standards DIN 53887, DIN 53120, ISO9237, and ASTM D 737-96. TM Therefore, the air permeability is measured in minutes (abbreviated as "min").

[0125] If the second vacuum belt includes multiple layers on top of each other, one or more of the layers are fiber layers, but preferably all layers are fiber layers. The layers also need to be breathable. The air permeability of the second vacuum belt is measured over all the multiple layers. Preferably, the first layer of the multiple layers in contact with the tape (1300) has a lower air permeability than the second layer, which is the subsequent layer of the first layer. Most preferably, the subsequent layer of one of the multiple layers has a higher air permeability.

[0126] In this embodiment, the second conveyor belt may include registration marks for arranging natural leather (300) or more than one natural leather on a semi-transparent or transparent tape (1300). The registration marks may be a ruler, a grid of n×m small squares, or one or more small lines for easily registering the natural leather (300) or even more than one natural leather (300). The marks may include identification codes or means for calculating distances. The registration marks may also be part of the tape. The registration marks may be a ruler, a grid of n×m small squares, or one or more small lines for easily registering the natural leather (300) or even more than one natural leather (300).

[0127] For ease of handling and to have a certain stiffness, the weight of the second vacuum belt is preferably between 0.6 and 2.5 kg / m 2 between. Then, the thickness of the belt is preferably between 0.5 mm and 4 mm, more preferably between 1.5 mm and 3 mm. In a preferred embodiment, the thickness of the second vacuum belt is twice or more the thickness of the natural leather (300) supported on the tape, but more preferably, the thickness of the second vacuum belt does not exceed 100 times the thickness of the natural leather (300) supported on the tape.

[0128] The hot pressing of the decorated natural leather may also be performed in the production line when the leather is still attached to the tape (1300) with the leather side (370). The production line of this embodiment then also includes a hot press for the hot pressing. Thus, the natural leather (300) is preferably semi-tanned leather, which is more preferably primed by a coating device before printing the decorative image and most preferably top-coated by the coating device after printing the image, and the coating device is then part of the production line. The primer coat, natural leather (300), decorative image, and top coat may then be clamped together by the hot pressing step. Simultaneously with or after the hot pressing step, a skin texture relief may additionally be applied to the top coat.

[0129] The conveyance preferably takes place in continuous distances also referred to as discrete stepping increments, which are caused by the conveyance of the first vacuum belt (150).

[0130] The support side of the second vacuum belt may be impregnated and / or coated with PUR and / or glue, and this support side is the side that contacts the opposite side (= non-adhesive side) of the tape (1300) in this embodiment. Additionally, the other side that should contact the first conveyor belt may also be impregnated for better sliding, for example, impregnated with PUR.

[0131] When one or more natural leathers are supplied on the tape (1300), the position can be scanned by a camera system (1004) above the tape (1300). The camera system (1004) is then part of the inkjet printer (500) of the present embodiment. If the second vacuum belt has registration marks and the tape (1300) is a semi-transparent or transparent registration device or identification code, the scanning can be used to optimize the supply chain of the decorated natural leather of the present embodiment. In the post-treatment of the decorated natural leather, if the natural leather is still on the second vacuum belt, the identification code and the position of the one or more natural leathers can be used, for example, in cutting or hot pressing or embossing or top coating of the natural leather. The use of a scanner system in an inkjet printer for printing natural leather is disclosed in paragraphs

[0049] and claim 17 of US2013 / 0239833 (CODUS HOLDINGS LIMITED). To capture the natural leather well by the camera system (1004), the tape is preferably matte, and thus matte, to avoid capturing the incident light on the tape. Unrolling the tape from the tape roll of the tape (1300) before applying it to the second conveyor belt may cause annoying noise, which can be limitedly isolated, for example, by applying a soundproof box around the tape roll of the tape. The unrolling of the tape may include the steps of stretching the tape before applying it to the second conveyor belt to avoid wrinkles in the tape, for example, by using a spreading roller.

[0132] When one or more natural leathers are scanned by the camera system (1004), the edges forming the contour can be detected and provided to the inkjet printer or an image converter such as a raster image processor to prevent ink from being spilled on the edges of the one or more natural leathers and on the tape and / or the second conveyor belt when an image such as a decorative pattern is printed on the one or more natural leathers. The image is mostly stored in the memory as a rectangular pixel array. The contour of the held natural leather is not always rectangular and is mostly irregular in shape. Prevention can be easily carried out by masking a part of the image based on the detected edges of the one or more natural leathers. The scanner can even detect bites or bad parts in the one or more natural leathers, so that no ink is spilled on the parts or bites either. Scanning and detecting the known position of the one or more natural leathers can also be used to nest an image above the one or more natural leathers, such as in an application from Elitron TM : in the EliNest application.

[0133] The camera system can be a digital 2D-camera or 3D-camera or line-camera positioned above the tape. The camera system can have means for conveying the camera towards or away from the natural leather in three dimensions (height, width and length). The camera system can also have one or more lenses for capturing scaled images from the natural leather held on the breathable support.

[0134] The nonwoven fabric (200) configured as the second vacuum belt also wraps around a pair of sliding supports (805, 817) that are substantially parallel to each other. The sliding supports are also substantially parallel to the pair of pulleys around which the first vacuum belt (150) from this embodiment wraps. In a preferred embodiment of this embodiment, the sliding supports in the pair of sliding supports are part of a pair of pulleys (815, 817), and more preferably the pair of sliding supports is another pair of pulleys, so it is not the pair of pulleys around which the first vacuum belt (150) wraps. Such a pulley in another pair of pulleys including the sliding supports from this embodiment can be non-rotatable, but preferably can rotate around its longitudinal axis. The rotation of the pulley is preferably carried out by the friction of the nonwoven fabric (200) configured as the second vacuum belt when being conveyed by the first vacuum belt (150). The rotation of the pulley can be driven by a motor, for example to easily handle the nonwoven fabric (200) configured as the second vacuum belt on the first vacuum belt (150), or to slightly control the conveying direction and movement of the nonwoven fabric (200) configured as the second vacuum belt.

[0135] For a better understanding of the present invention: the pair of sliding supports (S 上游 and S 下游 ) are mounted outside the first vacuum belt (150), so the first vacuum belt (150) does not wrap around the pair of sliding supports, and the pair of sliding supports is not part of the pair of pulleys around which the first vacuum belt (150) from this embodiment wraps, and thus, the first vacuum belt (150) does not contact the pair of sliding supports (805, 807).

[0136] The nonwoven fabric (200) configured as the second vacuum belt may contact the pair of sliding supports, which may be another pair of pulleys, through the air flow of the air cushion system included in the sliding supports at its back side. The side of the sliding support on which the nonwoven fabric (200) configured as the second vacuum belt from this embodiment is supported is called the support surface or support side of the sliding support.

[0137] The nonwoven fabric (200) configured as the second vacuum belt can also be wound around an additional pulley or a plurality of additional pulleys such as a dancer roller, which do not contact the first vacuum belt (150) and are configured outside the first vacuum belt (150).

[0138] Due to the rotation of the nonwoven fabric (200) configured as the second vacuum belt, the nonwoven fabric contacts the first vacuum belt (150) by suction in the vacuum area (A 真空 ), while causing the first vacuum belt (150) to rotate around a pair of pulleys (P 上游 , P 下游 ) from this embodiment of it. The natural leather (300) on the nonwoven fabric (200) configured as the second vacuum belt is conveyed in the printing apparatus between a sliding support (also referred to as the upstream sliding support (S 上游 )) and another sliding support (also referred to as the downstream sliding support (S 下游 )). The pair of sliding supports (805, 807) around which the nonwoven fabric (200) configured as the second vacuum belt is wound includes the upstream sliding support (S 上游 ) and the downstream sliding support (S 下游 ). Similarly, the pair of pulleys around which the first vacuum belt (150) is wound above it includes the upstream pulley (P 上游 ) and the downstream pulley (P 下游 ), and the nonwoven fabric (200) configured as the second vacuum belt and thus the natural leather (300) are conveyed between this pair of pulleys. The marking of the natural leather (300) is performed between the upstream sliding support (S 上游 ) and the downstream sliding support (S 下游 ).

[0139] The conveying directions of the first vacuum belt (150), the natural leather (300), and the nonwoven fabric (200) configured as the second vacuum belt are determined to be from the upstream area to the downstream area, from the upstream sliding support (S 上游 ) to the downstream sliding support (S 下游 ), and from the upstream pulley (P 上游 ) to the downstream pulley (P 下游 ).

[0140] The width of the non-woven fabric (200) configured as the second vacuum belt is the distance of the non-woven fabric (200) configured as the second vacuum belt measured in the direction parallel to the pair of sliding supports. The width of the non-woven fabric (200) configured as the second vacuum belt is the distance between the edges of the non-woven fabric (200) configured as the second vacuum belt that spans the non-woven fabric (200) parallel to these parallel sliding supports. The width of the non-woven fabric (200) is preferably between 1 m and 10 m.

[0141] A plurality of natural leathers can be placed adjacent to each other on the tape (1300) supported on the non-woven fabric (200). The inkjet printer (500) can have a movable alignment pin that slides above the media latch to be fixed at a desired position. The alignment pin aligns one of the plurality of natural leathers. Jeti Tauro manufactured by AGFA NV TM Has such a pin configuration to print on one or more aligned natural leathers using the so-called media latch.

[0142] The configuration from this embodiment enables the addition of pinch rollers before and sufficiently close to the media latch. See also Figure 4 . This enables the continued printing of natural leathers:

[0143] A first set of natural leathers is applied to a tape having a pressure-sensitive adhesive on its adhesive side and is moved in the direction of the print head to decorate the first set of natural leathers. At the same time, a second set of natural leathers is applied against the media latch, which moves towards the tape (downward), and the pinch rollers move away from the tape (upward). Thus, the second set of natural leathers is applied between the pinch rollers and against the media latch. The second set of natural leathers slides above the moving tape but is held in place by the media latch moving towards the tape (downward). If all of the natural leathers in the second set are applied, the pinch rollers descend (downward) in the direction of the tape and press the second set of natural leathers against the adhesive side of the tape, which activates the adhesive. At the same time, the media latch moves away from the tape (upward), whereby the second set of natural leathers moves in the direction of the print head to decorate the second set of natural leathers. Therefore, it is important that the pinch rollers are positioned very close to the media latch. They are parallel to each other, and the distance is preferably between 10 mm and 500 mm. If the distance is too large, it is found that one or more of the natural leathers in the set are squeezed against the media latch. This method enables rapid production because the inkjet printer can continuously print a set of natural leathers. The pinch rollers preferably have an outer layer of PTFE to overcome the problem of the applied natural leather rotating around the pinch rollers. The outer layer of the pinch rollers is the layer that contacts the natural leather.

[0144] The length of the nonwoven fabric (200) configured as the second vacuum belt is the distance of the nonwoven fabric (200) configured as the second vacuum belt measured perpendicular to the parallel direction of the pair of sliding supports. It defines the length of the loop formed by the nonwoven fabric (200) configured as the second vacuum belt.

[0145] The conveying direction of the nonwoven fabric (200) configured as the second vacuum belt is the direction in which the nonwoven fabric (200) configured as the second vacuum belt is conveyed, and this direction is perpendicular to the pair of sliding supports around which the nonwoven fabric (200) configured as the second vacuum belt is looped or formed into a loop. The conveying direction of the nonwoven fabric (200) configured as the second vacuum belt defines the path followed by the conveyor belt on the pair of sliding supports around which it is looped.

[0146] The sliding supports may include belt guides to prevent or minimize the wandering of the nonwoven fabric (200) configured as the second vacuum belt above the pair of sliding supports, and this wandering is the left-to-right or right-to-left movement of the nonwoven fabric (200) configured as the second vacuum belt in a direction perpendicular to the conveying direction of the nonwoven fabric (200) configured as the second vacuum belt.

[0147] The printing device from this embodiment preferably includes an adjusting device to align the longitudinal axes of the pair of sliding supports of this embodiment to become parallel to each other.

[0148] The printing device may include a plurality of conveyor belts, as the nonwoven fabric (200) configured as the second vacuum belt. For example, and as a preferred embodiment, the plurality of conveyor belts use different adhesives to create different adhesive zones according to the printing receivers carried on these plurality of conveyor belts configured as the second vacuum belt. Then, the plurality of conveyor belts are also looped around the pair of sliding supports from this embodiment.

[0149] In a preferred embodiment, the nonwoven fabric (200) configured as the second vacuum belt includes a scale and / or a divider, which can be used to measure, for example, the movement and / or speed of the nonwoven fabric (200) configured as the second vacuum belt, or the dimensions of the natural leather (300), by means of sensors such as encoders and optical linear encoders. After reading the scale and / or the divider, the signal from a sensor such as an optical linear encoder determines the position of the nonwoven fabric (200) configured as the second vacuum belt, or the speed of the nonwoven fabric (200) configured as the second vacuum belt, in the control system, and indirectly determines the position of the natural leather (300) carried on the nonwoven fabric (200) configured as the second vacuum belt. The encoder can have a digital resolution between 0.01 μm and 250 μm, more preferably between 0.01 and 50 μm, and most preferably between 0.01 and 10 μm. This small digital resolution is important for calculating the true continuous distance of movement from the encoder signal, especially when the nonwoven fabric (200) configured as the second vacuum belt moves at a continuous distance. The scale and / or the divider can be included on the support side of the nonwoven fabric (200) configured as the second vacuum belt, which is the side connected to the natural leather (300), and / or included on the back side of the nonwoven fabric (200) configured as the second vacuum belt, which is the side connected to the first vacuum belt (150).

[0150] In a preferred embodiment of the present embodiment, the nonwoven fabric (200) configured as the second vacuum belt hangs, more preferably hangs freely, between a downstream sliding support (S 下游 ) and an upstream sliding support (S 上游 ). The tension between the downstream sliding support and the upstream sliding support (S 上游 ) is preferably lower than the tension on the first vacuum belt (150) from the present embodiment, and more preferably is not tensioned between the downstream sliding support and the upstream sliding support (S 上游 ). For clarity, the tension here means the force on the conveyor belt in the conveying direction, also called the conveying direction tension. The additional advantage of the lower tension or non-tensioned conveyance of the nonwoven fabric (200) configured as the second vacuum belt between the downstream sliding support and the upstream sliding support (S 上游 ) is that the service life of the nonwoven fabric (200) configured as the second vacuum belt is increased.

[0151] The sum of the tensions within the nonwoven fabric (200) configured as the second vacuum belt is preferably lower than the sum of the tensions within the first vacuum belt (150), especially during printing.

[0152] If the tension of the non-woven fabric (200) configured as the second vacuum belt is equal to or higher than that of the first vacuum belt (150), it is found that the non-woven fabric (200) configured as the second vacuum belt is prone to creasing and / or unpredictable internal tension, which results in a positional change of the natural leather (300) on top of the non-woven fabric (200) configured as the second vacuum belt. This positional change reduces the printing quality of the printed pattern or may cause the natural leather (300) to collapse against the marking device or dryer from the printing equipment. Additionally, this makes it more difficult to apply the non-woven fabric (200) configured as the second vacuum belt around the first conveyor belt and the upstream sliding support (S 上游 ) and the downstream sliding support (S 下游 ). Therefore, the total tension within the non-woven fabric (200) configured as the second vacuum belt is preferably lower than the total tension within the first vacuum belt (150), especially during printing.

[0153] Pressure device

[0154] The pressure device in this embodiment is used to apply pressure against the tape (1300) and thus against the natural leather (300) on the second vacuum belt and the first vacuum belt (150) of this embodiment.

[0155] In this embodiment, the pressure device includes a portion for frictionally traversing a part of the natural leather (300) by relative movement between the pressure device and the tape (1300) carrying the natural leather (300).

[0156] Therefore, this portion traverses one side of the natural leather (300), and during a period of time, this portion moves along the surface of the side with pressure (= friction). The period of time is preferably more than 50 μs. The device for pressing the natural leather (300) against the tape (1300) is thus not a roller that causes a very short contact squeeze (≠ friction). Preferably, the portion is a flat portion angled towards the second vacuum belt, such as configured as a slit. This flat portion can also be a leaf spring or a cartridge spring. If the portion is a flat portion, it is preferably adapted to frictionally traverse the natural leather (300) when conveying the natural leather (300) on the tape (1300). The angle between the flat portion and the second vacuum belt is preferably less than 65°, more preferably less than 30°. The angle is at least 0.5°.

[0157] The flat portion preferably has resilience, wherein when the portion is moved relative to the pressure device and the tape (1300) carrying the natural leather (300) with friction across the natural leather (300), the flat portion becomes (almost) parallel to the tape (1300) of the present embodiment. Due to the resilience, fewer scratches caused by the portion appear on the natural leather (300). The flat portion is preferably made of or includes the following: metal, steel, polyethylene terephthalate (PET), polyamide (PA), high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), and / or polyaryletherketone (PAEK). The end of the portion that contacts the natural leather (300) when the portion is moved relative to the pressure device across the natural leather (300) with friction between the tape (1300) is preferably rounded to prevent scratches on the natural leather (300), or includes a soft block to block the sharp end of the portion.

[0158] The inkjet printer (500) preferably includes a height regulator for adjusting the distance between the portion and the first vacuum belt (150), and thus the second vacuum belt and the tape (1300). The thickness of the natural leather can vary, so the height regulator is beneficial for controlling the pressing of the natural leather against the second vacuum belt. The non-woven fabric (200), especially felt, and the natural leather (300) are compressible, which makes the extrusion feasible.

[0159] Base coat

[0160] The base coat applied to natural leather (300) such as semi-tanned leather provides an image quality level commensurate with the luxurious appearance of the leather, because the low viscosity of the inkjet ink causes them to penetrate quickly into the leather, resulting in a reduction in image quality.

[0161] The base coat can be applied as a single layer, or can be applied as multiple layers. The multiple layers can even have different compositions for improving properties such as adhesion or flexibility.

[0162] The base coat preferably includes a polyurethane-based polymer or copolymer, because it has been found that this improves the flexibility of the printed leather. The base coat preferably also includes a polyamide polymer or copolymer, because it has been found that polyamide improves the compatibility with semi-tanned leather and improves the strength of the base coat. The base coat is preferably applied by spraying, but can also be applied by any known coating technique, such as knife coating, extrusion coating, slide hopper coating, and curtain coating. It can be applied before attaching the natural leather (300) to the tape (1300) in the present embodiment, or it can be applied when the natural leather (300) has been attached to the tape (1300).

[0163] The undercoat can be transparent, but preferably it is an opaque undercoat. If an opaque undercoat is applied when the natural leather (300) has already been attached to the tape (1300), preferably measures are taken to not spray or coat the area where the identifier, registration device, ruler or positioning mark of the tape is located, or alternatively cover them with, for example, a removable piece of tape (1300) before spraying or coating. In this way, the identifier or positioning mark can still be observed by the human eye.

[0164] The undercoat can be a white undercoat to enhance the color vividness of the inkjet printed image, but preferably, the undercoat has a color similar to the color of the genuine leather and the grain. Any desired color can be selected for the genuine leather or the grain and the undercoat, such as red, green, brown, black, blue, etc.

[0165] Top coat

[0166] A topcoat can be applied to the decorative image and the undercoat for enhancing the scratch resistance of the decorative image.

[0167] The topcoat can be applied as a single layer, or can be applied as multiple layers. The multiple layers can even have different compositions for improving properties such as scratch resistance.

[0168] The protective topcoat can have the same or a similar composition to the undercoat. Generally, the protective topcoat is optimized to some extent according to the leather application. For example, in contrast to leather shoes, flexibility is not important for a leather book cover. Therefore, the protective topcoat for the book cover can be optimized for scratch resistance.

[0169] The topcoat preferably includes a cross-linker and a polymer or copolymer based on polyurethane and / or polyamide.

[0170] Adhesive for nonwoven fabric (200)

[0171] In a less preferred embodiment, an adhesive is applied to the non-woven fabric (200) configured as the second vacuum belt so as to ensure retention not only by vacuum power. The adhesive thus forms a sticky layer on the second vacuum belt. The most preferred embodiment of this embodiment is the second vacuum belt without the sticky layer.

[0172] The adhesive is used to attach the tape (1300) to the second vacuum belt of this embodiment. The adhesive can be applied to the second vacuum belt, applied to the tape (1300), or applied to both of them.

[0173] Any adhesive known in the art, from classical well-known adhesives to bionic-based adhesives, can be used in this embodiment. Repositionable adhesives are preferred because they facilitate the process of ensuring that the leather is attached to the carrier completely flatly without causing collision with the inkjet print head. Removable pressure-sensitive adhesives are also known from applications such as Post-It TM notes from 3M.

[0174] There is no limitation on the way of applying the adhesive to the surface, which can be, for example, by coating or spraying. Repositionable spray adhesives are preferred because when separating the carrier from the leather, they cause no damage or very limited damage to the dermis side (370). A commercial example of a suitable spray adhesive is 3M TM Repositionable 75 Spray Adhesive. Spray adhesives are also called aerosol adhesives.

[0175] Tape (1300)

[0176] In a preferred embodiment, the tape (1300) is transparent or translucent, and the nonwoven fabric (200) includes registration marks for easily arranging the natural leather (300) on the tape (1300). In another preferred embodiment or in combination with the previous preferred embodiment, the tape (1300) may include registration marks for easily arranging the natural leather (300) on the tape (1300). If the tape (1300) is transparent or translucent, the registration marks can be marked on the adhesive side or marked on the opposite side.

[0177] The tape (1300) is unwound from a tape roll. In a preferred embodiment, after the decorated natural leather is separated from the tape (1300), the tape (1300) is wound up again at the output side of the inkjet printer. The wound-up tape (1300) can be reused at the input side of the inkjet printer.

[0178] The tape (1300) preferably has a width greater than 80% of the width of the nonwoven fabric (200), and more preferably, the carrier of the tape (1300) has a thickness between 10 μm and 500 μm, preferably between 10 and 300 μm. A small thickness is preferred because it results in less waste.

[0179] The adhesiveness of the adhesive side is preferably activated by pressure, heat, or applied moisture.

[0180] The adhesive side has a sticky layer, which preferably includes acrylic adhesives, epoxy resins, rubber-based adhesives, silicone adhesives, polyurethane adhesives, and / or isocyanate adhesives.

[0181] The carrier materials suitable for the tape are laminate materials, films (e.g., BOPP, PO, MOPP, PP, PE, polyester such as PET, PA, PU, PVC), foams, foamed or metallized films. These films themselves can in turn consist of several individual layers, e.g., these layers are coextruded into a film. Polyolefins are preferred, but also include copolymers of ethylene and polar monomers such as styrene, vinyl acetate, methyl methacrylate, butyl acrylate or acrylic acid. It can be a homopolymer such as HDPE, LDPE, MDPE, or a copolymer of ethylene and another olefin such as propylene, butene, hexene or octene (e.g., LLDPE, VLLDE). Polypropylene (e.g., polypropylene homopolymer, polypropylene random copolymer or polypropylene block copolymer) is also suitable. According to the present invention, films with excellent uniaxial and biaxial stretching can be used as the film. Uniaxially stretched polypropylene is characterized by its very high tensile strength and low elongation in the longitudinal direction and is, for example, used for the production of strapping tapes. Films based on polyester, preferably polyethylene terephthalate or especially polypropylene, are particularly preferred. The film preferably has a thickness of 10 μm to 100 μm. The film can be colored and / or transparent. The film may be unstretched.

[0182] If textiles are selected as the carrier material, all known textile carriers such as knitted fabrics, gauzes, tapes, woven fabrics, tufted fabrics, felts, fabrics (including canvas, twill and satin weaves), knitted fabrics (including warp knitted fabrics and knitgoods) or non-woven fabrics can be used as the textile support, and "non-woven fabrics" should be understood to mean at least textile fabrics according to EN29092 (1988) as well as stitch-bonded non-woven fabrics and similar systems. In addition, laminated fabrics and knitted fabrics can also be used.

[0183] Preferably, the adhesive applied to the carrier material is a pressure-sensitive adhesive (PSA), i.e., an adhesive that allows for permanent connection even under relatively weak pressure due to almost all bonding reasons and can be separated from the primer again after use with substantially no residue. The adhesiveness of the adhesive is based on its adhesion properties, and the removability is based on their cohesion properties.

[0184] All known adhesive systems can be used to produce the tape from the carrier. In addition to adhesives based on natural or synthetic rubber, in particular silicone adhesives and polyacrylate adhesives can be used, preferably low molecular weight acrylate hot melt pressure sensitive adhesives. The adhesive can be selected from the group of natural rubber or synthetic rubber or any mixture of natural rubber and / or synthetic rubber, and the one or more natural rubbers are substantially made of all available qualities, such as Crepe, RSS, ADS, TSR or CV type, depending on the required purity and viscosity level, and one or more synthetic rubbers can be selected from the group of random copolymer styrene butadiene rubber (SBR), butadiene rubber (BR), synthetic polyisoprene (IR), butyl rubber (IIR), halogenated butyl rubber (XIIR), acrylate rubber (ACM), ethylene vinyl acetate copolymer (EVA) and polyurethane and / or their blends.

[0185] The adhesive on the carrier of the tape can be a fibrous adhesive system, preferably an imitation of the adhesive system of beetles, flies, spiders or gecko toes. However, the imitation of the setae found on gecko toes is most preferred because of its adhesion ability.

[0186] The adhesion level of the adhesive on the carrier is preferably the adhesion force to BA steel measured according to EN1939 - European Committee for Standardization (CEN) between 60 and 600 cN / 20 mm, and more preferably, for good adhesion and also for easy removal of leather, the adhesion force to BA steel measured according to EN1939 - European Committee for Standardization (CEN) between 80 and 300 cN / 20 mm.

[0187] Ink for colored inkjet

[0188] One or more colored inkjet inks for inkjet printing can be selected from water-based colored inkjet inks, solvent-based colored inkjet inks and radiation-curable colored inkjet inks. However, the one or more colored inkjet inks are preferably one or more radiation-curable inkjet inks, and most preferably one or more UV-curable inkjet inks.

[0189] The one or more colored inkjet inks preferably contain organic color pigments because they allow a high color gamut to be obtained on natural leather (300). Carbon black and titanium dioxide are inorganic pigments, which can be advantageously used in this embodiment to form black and white colored inkjet inks respectively.

[0190] In a preferred embodiment, the one or more colored inkjet inks form a CMYK(W) or CRYK(W) inkjet ink set.

[0191] Other Example 1

[0192] This embodiment is suitable for achieving the same result. The nonwoven fabric (200) configured as the second conveyor belt may also be an adhesive conveyor belt.

[0193] Accordingly, a method for decorating natural leather with an inkjet printer, the inkjet printer including a first vacuum belt (150) for conveying a second conveyor belt, the second conveyor belt being an adhesive conveyor belt; and

[0194] wherein the method includes:

[0195] - applying a tape (1300) from a tape roll as a continuous sheet against the adhesive conveyor belt, wherein the tape (1300) has an adhesive side and an opposite side, and the opposite side contacts the adhesive conveyor belt;

[0196] - applying natural leather (300) on the adhesive side of the tape (1300);

[0197] - conveying the applied natural leather by moving the first vacuum belt (150), whereby the adhesive conveyor belt moves by suction through the first vacuum belt (150), and the applied tape (1300) moves under the inkjet print head (505) by adhering to the adhesive layer of the adhesive conveyor belt;

[0198] - marking the applied natural leather with droplets ejected from the inkjet print head (505) for decorating the natural leather while the tape (1300) is attached to the adhesive conveyor belt.

[0199] The adhesive conveyor belt is a non-porous conveyor belt having an adhesive side formed by an adhesive layer. Preferably, the adhesive applied as a layer to the conveyor belt is a pressure-sensitive adhesive (PSA), i.e., an adhesive that allows permanent connection due to almost all adhesion reasons even under relatively weak pressure and can be separated from the primer again after use with substantially no residue. The adhesiveness of the adhesive is based on its adhesion performance, and the removability is based on their cohesion performance.

[0200] To produce a sticky conveyor belt from a conveyor belt, all known adhesive systems can be used. In addition to adhesives based on natural or synthetic rubber, silicone adhesives and polyacrylate adhesives can in particular be used, preferably low molecular weight acrylate hot melt pressure sensitive adhesives. The adhesive can be selected from the group of natural rubber or synthetic rubber or from any mixture of natural rubber and / or synthetic rubber, and the one or more natural rubbers are substantially made from all available qualities, such as Crepe, RSS, ADS, TSR or CV types, depending on the required purity and viscosity levels, and one or more synthetic rubbers can be selected from the group of random copolymer styrene butadiene rubber (SBR), butadiene rubber (BR), synthetic polyisoprene (IR), butyl rubber (IIR), halogenated butyl rubber (XIIR), acrylate rubber (ACM), ethylene vinyl acetate copolymer (EVA) and polyurethane and / or their blends.

[0201] The adhesive on the conveyor belt can be a fibrous adhesive system, preferably an imitation of the adhesive system of the toes of beetles, flies, spiders or geckos. However, the imitation of the bristles found on the gecko's toes is most preferred due to its adhesion ability.

[0202] The sticky conveyor belt can also be a sticky vacuum belt, whereby the tape is also attached to the sticky vacuum belt by suction. The sticky conveyor belt can be a non-woven fabric (200), such as in this embodiment and its preferred embodiments, but then the non-woven fabric (200) has a sticky layer on top of it.

[0203] Other Example 2

[0204] This embodiment can be adapted to achieve the same result. The non-woven fabric (200) configured as the second conveyor belt can also be a conveyor belt used with a double-sided tape.

[0205] Therefore, a method of decorating natural leather with an inkjet printer, the inkjet printer including a first vacuum belt (150) for conveying a second conveyor belt; and

[0206] wherein the method includes:

[0207] - Applying a double-sided tape (1300) as a continuous sheet against the conveyor belt from a tape roll, wherein the tape (1300) has a first adhesive side and a second adhesive side, and the second adhesive side contacts the conveyor belt.

[0208] - Applying natural leather (300) on the first adhesive side of the tape (1300);

[0209] - The applied natural leather is conveyed by moving the first vacuum belt (150), whereby the second conveyor belt is moved by the suction force through the first vacuum belt (150), and the applied tape (1300) is moved by adhesion to the second conveyor belt under the inkjet print head (505), which adhesion is caused by the adhesion to the second adhesive side;

[0210] - The applied natural leather is marked with the ejected droplets of the inkjet print head (505) for decorating the natural leather while the tape (1300) is attached to the second conveyor belt.

[0211] The conveyor belt may be a nonwoven fabric (200), such as in this embodiment and its preferred embodiments. The conveyor belt may also be a vacuum belt that uses the vacuum power from the first vacuum belt.

[0212] Other Example 3

[0213] This embodiment; "Other Embodiment 1" and "Other Embodiment 2" may be adapted to achieve the same result: The tape may be configured as a conveyor belt around the second conveyor belt and is thus not applied by a roll. The system is then referred to as a "triple-belt system". The third conveyor belt may surround at least two sliding supports located outside the second conveyor belt. One of the sliding supports may be a pulley.

Claims

1. A method for decorating natural leather using an inkjet printer, the inkjet printer comprising a first vacuum belt (150) for conveying a non-woven fabric (200) configured as a second vacuum belt; and wherein the method includes: - applying a tape (1300) from a tape roll as a continuous sheet against the non-woven fabric, wherein the tape (1300) has an adhesive side and an opposite side, and the opposite side contacts the non-woven fabric; - applying natural leather (300) on the adhesive side of the tape (1300); - conveying the applied natural leather by moving the first vacuum belt (150), whereby the non-woven fabric (200) is moved by suction through the first vacuum belt (150), and the applied tape (1300) is moved under the inkjet print head (505) by the suction through the non-woven fabric (200); - marking the applied natural leather with droplets ejected by the inkjet print head (505) for decorating the natural leather while the tape (1300) is attached to the non-woven fabric (200).

2. The method for decorating natural leather according to claim 1, wherein, The printing machine includes a device for applying pressure on the adhesive side of the tape (1300) to the natural leather (300).

3. The method for decorating natural leather according to claim 2, wherein, The device for applying pressure on the adhesive side of the tape (1300) to the natural leather (300) includes a part for frictionally traversing a part of the natural leather (300) by relative movement between the pressure device and the tape (1300) carrying the natural leather (300).

4. The method for decorating natural leather according to claim 1, wherein, The nonwoven fabric (200) has a air permeability of less than 90 L / (dm 2 x min).

5. The method for decorating natural leather according to claim 2, wherein, The nonwoven fabric (200) has a gas permeability of less than 90 L / (dm 2 x min).

6. The method for decorating natural leather according to claim 4, wherein, The non-woven fabric (200) is felt.

7. The method for decorating natural leather according to claim 1, wherein, The non-woven fabric (200) includes an adhesive layer for additionally adhering the opposite side of the tape (1300) to the non-woven fabric (200).

8. The method for decorating natural leather according to claim 1, wherein, The tape (1300) includes an adhesive layer on its opposite side for additionally adhering the opposite side of the tape (1300) to the non-woven fabric (200).

9. The method for decorating natural leather according to claim 1, wherein, The tape (1300) is transparent, and wherein the non-woven fabric (200) includes registration marks for arranging the natural leather (300) on the tape (1300).

10. The method for decorating natural leather according to claim 1, wherein, The tape (1300) includes registration marks for arranging the natural leather (300) on the tape (1300).

11. The method for decorating natural leather according to claim 10, wherein, The registration marks are marked on the opposite side and / or the adhesive side of the tape (1300).

12. The method for decorating natural leather according to claim 1, wherein, After the decorated natural leather is separated from the tape (1300), the tape (1300) is rolled up, and wherein the tape (1300) has a width greater than 80% of the width of the non-woven fabric (200).

13. The method for decorating natural leather according to claim 2, wherein, The non-woven fabric (200) includes an adhesive layer for additionally adhering the opposite side of the tape (1300) to the non-woven fabric (200).

14. The method for decorating natural leather according to claim 2, wherein, The tape (1300) includes an adhesive layer on its opposite side for additionally adhering the opposite side of the tape (1300) to the non-woven fabric (200).

15. The method for decorating natural leather according to claim 2, wherein, The tape (1300) is transparent, and the nonwoven fabric (200) includes registration marks for disposing the natural leather (300) on the tape (1300).

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